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Sample records for reservoir pressure reduction

  1. 49 CFR 236.554 - Rate of pressure reduction; equalizing reservoir or brake pipe.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 4 2012-10-01 2012-10-01 false Rate of pressure reduction; equalizing reservoir or brake pipe. 236.554 Section 236.554 Transportation Other Regulations Relating to Transportation...; Locomotives § 236.554 Rate of pressure reduction; equalizing reservoir or brake pipe. The...

  2. 49 CFR 236.554 - Rate of pressure reduction; equalizing reservoir or brake pipe.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 4 2011-10-01 2011-10-01 false Rate of pressure reduction; equalizing reservoir or brake pipe. 236.554 Section 236.554 Transportation Other Regulations Relating to Transportation...; Locomotives § 236.554 Rate of pressure reduction; equalizing reservoir or brake pipe. The...

  3. 49 CFR 236.554 - Rate of pressure reduction; equalizing reservoir or brake pipe.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... GOVERNING THE INSTALLATION, INSPECTION, MAINTENANCE, AND REPAIR OF SIGNAL AND TRAIN CONTROL SYSTEMS, DEVICES, AND APPLIANCES Automatic Train Stop, Train Control and Cab Signal Systems Rules and Instructions... 49 Transportation 4 2013-10-01 2013-10-01 false Rate of pressure reduction; equalizing reservoir...

  4. 49 CFR 236.554 - Rate of pressure reduction; equalizing reservoir or brake pipe.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... GOVERNING THE INSTALLATION, INSPECTION, MAINTENANCE, AND REPAIR OF SIGNAL AND TRAIN CONTROL SYSTEMS, DEVICES, AND APPLIANCES Automatic Train Stop, Train Control and Cab Signal Systems Rules and Instructions... 49 Transportation 4 2010-10-01 2010-10-01 false Rate of pressure reduction; equalizing reservoir...

  5. 49 CFR 236.554 - Rate of pressure reduction; equalizing reservoir or brake pipe.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... GOVERNING THE INSTALLATION, INSPECTION, MAINTENANCE, AND REPAIR OF SIGNAL AND TRAIN CONTROL SYSTEMS, DEVICES, AND APPLIANCES Automatic Train Stop, Train Control and Cab Signal Systems Rules and Instructions... 49 Transportation 4 2014-10-01 2014-10-01 false Rate of pressure reduction; equalizing reservoir...

  6. Interpreting isotopic analyses of microbial sulfate reduction in oil reservoirs

    NASA Astrophysics Data System (ADS)

    Hubbard, C. G.; Engelbrektson, A. L.; Druhan, J. L.; Cheng, Y.; Li, L.; Ajo Franklin, J. B.; Coates, J. D.; Conrad, M. E.

    2013-12-01

    Microbial sulfate reduction in oil reservoirs is often associated with secondary production of oil where seawater (28 mM sulfate) is commonly injected to maintain reservoir pressure and displace oil. The hydrogen sulfide produced can cause a suite of operating problems including corrosion of infrastructure, health exposure risks and additional processing costs. We propose that monitoring of the sulfur and oxygen isotopes of sulfate can be used as early indicators that microbial sulfate reduction is occurring, as this process is well known to cause substantial isotopic fractionation. This approach relies on the idea that reactions with reservoir (iron) minerals can remove dissolved sulfide, thereby delaying the transport of the sulfide through the reservoir relative to the sulfate in the injected water. Changes in the sulfate isotopes due to microbial sulfate reduction may therefore be measurable in the produced water before sulfide is detected. However, turning this approach into a predictive tool requires (i) an understanding of appropriate fractionation factors for oil reservoirs, (ii) incorporation of isotopic data into reservoir flow and reactive transport models. We present here the results of preliminary batch experiments aimed at determining fractionation factors using relevant electron donors (e.g. crude oil and volatile fatty acids), reservoir microbial communities and reservoir environmental conditions (pressure, temperature). We further explore modeling options for integrating isotope data and discuss whether single fractionation factors are appropriate to model complex environments with dynamic hydrology, geochemistry, temperature and microbiology gradients.

  7. Pressure effect on dissimilatory sulfate reduction

    NASA Astrophysics Data System (ADS)

    Williamson, A. J.; Carlson, H. K.; Coates, J. D.

    2015-12-01

    Biosouring is the production of H2S by sulfate reducing microorganisms (SRM) in-situ or in the produced fluids of oil reservoirs. Sulfide is explosive, toxic and corrosive which can trigger equipment and transportation failure, leading to environmental catastrophe. As oil exploration and reservoir development continue, subsequent enhanced recovery is occurring in progressively deeper formations and typical oil reservoir pressures range from 10-50 MPa. Therefore, an understanding of souring control effects will require an accurate understanding of the influence of pressure on SRM metabolism and the efficacy of souring control treatments at high pressure. Considerable work to date has focussed on souring control at ambient pressure; however, the influence of pressure on biogeochemical processes and souring treatments in oil reservoirs is poorly understood. To explore the impact of pressure on SRM, wild type Desulfovibrio alaskensis G20 (isolated from a producing oil well in Ventura County, California) was grown under a range of pressures (0.1-14 MPa) at 30 °C. Complete sulfate reduction occurred in all pressures tested within 3 days, but microbial growth was inhibited with increasing pressure. Bar-seq identified several genes associated with flagella biosynthesis (including FlhB) and assembly as important for survival at elevated pressure and fitness was confirmed using individual transposon mutants. Flagellar genes have previously been implicated with biofilm formation and confocal microscopy on glass slides incubated with wild type D. alaskensis G20 showed more biomass associated with surfaces under pressure, highlighting the link between pressure, flagellar and biofilm formation. To determine the effect of pressure on the efficacy of SRM inhibitors, IC50 experiments were conducted and D. alaskensis G20 showed a greater resistance to nitrate and the antibiotic chloramphenicol, but a lower resistance to perchlorate. These results will be discussed in the context of

  8. Different pressure grids for reservoir simulation in heterogeneous reservoirs

    SciTech Connect

    Guerillot, D.R.; Verdiere, S.

    1995-12-31

    Petroleum reservoirs are made of highly heterogeneous rocks. These reservoirs could be described by geostatistical models composed of millions of cells. Currently, fluid flow simulations performed within these media need upscaling (or averaging) techniques. Hence, their results are given by averaging on cells which are much larger than the geological model cells. To overcome this problem, the Dual Mesh Method is proposed here, whose purpose is to solve the pressure equation on a low resolution grid, and then to interpolate pressure over the fine mesh by taking into account small scale heterogeneities of the mediums. The aim of this paper is the interpolation step; its implementation is presented and illustrated in a five-spot pattern for three different rock characteristics.

  9. Perchlorate reduction by microbes inhabiting oil reservoirs

    NASA Astrophysics Data System (ADS)

    Liebensteiner, Martin; Stams, Alfons; Lomans, Bart

    2014-05-01

    Microbial perchlorate and chlorate reduction is a unique type of anaerobic respiration as during reduction of (per)chlorate chlorite is formed, which is then split into chloride and molecular oxygen. In recent years it was demonstrated that (per)chlorate-reducing bacteria may employ oxygenase-dependent pathways for the degradation of aromatic and aliphatic hydrocarbons. These findings suggested that (per)chlorate may be used as oxygen-releasing compound in anoxic environments that contain hydrocarbons, such as polluted soil sites and oil reservoirs. We started to study perchlorate reduction by microbes possibly inhabiting oil reservoirs. One of the organisms studied was Archaeoglobus fulgidus. This extremely thermophilic archaeon is known as a major contributor to souring in hot oil reservoirs. A. fulgidus turned out to be able to use perchlorate as terminal electron acceptor for growth with lactate (Liebensteiner et al 2013). Genome based physiological experiments indicated that A. fulgidus possesses a novel perchlorate reduction pathway. Perchlorate is first reduced to chlorite, but chlorite is not split into chloride and molecular oxygen as occurs in bacteria. Rather, chlorite reacts chemically with sulfide, forming oxidized sulfur compounds, which are reduced to sulfide in the electron transport chain by the archaeon. The dependence of perchlorate reduction on sulfur compounds could be shown. The implications of our findings as novel strategy for microbiological enhanced oil recovery and for souring mitigation are discussed. Liebensteiner MG, Pinkse MWH, Schaap PJ, Stams AJM and Lomans BP (2013) Archaeal (per)chlorate reduction at high temperature, a matter of abiotic-biotic reactions. Science 340: 85-87

  10. Transient pressure analysis in composite reservoirs

    SciTech Connect

    Tang, R.W.K.; Brigham, W.E.

    1982-08-01

    The problem of fluid flow in a radially composite reservoir is discussed. Recently published was the most general analytic solution available thus far. That analytic solution is analyzed, and the results are presented. The solution is dependent upon the following dimensionless parameters (if well-bore storage and skin effect are neglected): (1) dimensionless time based on the discontinuity radius, (2) the dimensionless discontinuity radius, (3) the mobility ratio, and (4) the diffusivity ratio. The range of parameters used in generating the results include dimensionless radius time of 0.01 t

  11. Pressure test data reveal reservoir barriers/faults

    SciTech Connect

    Hurd, J.D.

    1984-07-30

    A review of transient pressure test data from an oil reservoir in Libya indicated not only the suspected fault barriers, but also the non-sealing portions of the faults. Extensive seismic data indicated much faulting, and directional trends had been interpreted to be generally northwest-southeast. The reservoir is a heterogeneous dolomite with average permeability of 40 to 50 md and contains neither natural fractures not stratification. Vertical displacement (throw) of each fault block is indicated to be within the range of the dolomite thickness, i.e., 40 to 180 ft. Therefore, when the fault throw is greater than reservoir thickness there is sealing, and when the throw is less than reservoir thickness the faults are non-sealing.

  12. Intraocular pressure reduction and regulation system

    NASA Technical Reports Server (NTRS)

    Baehr, E. F.; Burnett, J. E.; Felder, S. F.; Mcgannon, W. J.

    1979-01-01

    An intraocular pressure reduction and regulation system is described and data are presented covering performance in: (1) reducing intraocular pressure to a preselected value, (2) maintaining a set minimum intraocular pressure, and (3) reducing the dynamic increases in intraocular pressure resulting from external loads applied to the eye.

  13. Reservoir transport and poroelastic properties from oscillating pore pressure experiments

    NASA Astrophysics Data System (ADS)

    Hasanov, Azar K.

    Hydraulic transport properties of reservoir rocks, permeability and storage capacity are traditionally defined as rock properties, responsible for the passage of fluids through the porous rock sample, as well as their storage. The evaluation of both is an important part of any reservoir characterization workflow. Moreover, permeability and storage capacity are main inputs into any reservoir simulation study, routinely performed by reservoir engineers on almost any major oil and gas field in the world. An accurate reservoir simulation is essential for production forecast and economic analysis, hence the transport properties directly control the profitability of the petroleum reservoir and their estimation is vital for oil and gas industry. This thesis is devoted to an integrated study of reservoir rocks' hydraulic, streaming potential and poroelastic properties as measured with the oscillating pore pressure experiment. The oscillating pore pressure method is traditionally used to measure hydraulic transport properties. We modified the method and built an experimental setup, capable of measuring all aforementioned rock properties simultaneously. The measurements were carried out for four conventional reservoir-rock quality samples at a range of oscillation frequencies and effective stresses. An apparent frequency dependence of permeability and streaming potential coupling coefficient was observed. Measured frequency dispersion of drained poroelastic properties indicates an intrinsically inelastic nature of the porous mineral rock frame. Standard Linear Model demonstrated the best fit to the experimental dispersion data. Pore collapse and grain crushing effects took place during hydrostatic loading of the dolomitic sample and were observed in permeability, coupling coefficient and poroelastic measurements simultaneously. I established that hydraulically-measured storage capacities are overestimated by almost one order of magnitude when compared to elastically

  14. Aortic reservoir function, estimated myocardial demand and coronary perfusion pressure following steady-state and interval exercise.

    PubMed

    Lane, A D; Heffernan, K S; Rossow, L M; Fahs, C A; Ranadive, S M; Yan, H; Baynard, T; Wilund, K; Fernhall, B

    2012-09-01

    Aortic reservoir function is a measure of the aorta's ability to distribute blood during diastole, attenuating the pulsatility of blood flow, and is important in balancing cardiac flow. Effects of acute high versus moderate exercise intensity on reservoir function and cardiac energetics is unknown. Eighteen athletes completed a interval (INT) and steady-state (SS) cycling bout at 60% of VO(2) peak. Reservoir function was calculated as the ratio of diastolic run-off to stroke volume and expressed as a percentage. Coronary perfusion pressure was derived from tissue Doppler imaging and echocardiography. Systolic tension-time integral (TTI) from the aortic pressure waveform served as a measure of myocardial oxygen consumption. All measures were made at rest, 30-min postexercise and 60-min postexercise. Average reservoir function before SS was 76%, which was reduced to 62% 30-min post-SS and 67% 60-min post-SS (P<0.05). Significantly greater reductions in reservoir function were seen following INT (from 71% pre-INT to 45% 30-min post-INT and 53% 60-min INT, P<0.05). Estimated coronary perfusion pressure was reduced 30 min following INT but not SS; both bouts reduced coronary perfusion pressure at 60-min postexercise (P<0.05). TTI increased following both INT and SS at 30- and 60-min postexercise with greater increases following INT (P<0.05). Following exercise, reservoir function was associated with TTI (P<0.05), but not coronary perfusion pressure (P>0.05). We conclude that reservoir function is attenuated following acute SS and INT, but these reductions were greater post-INT, suggesting that exercise intensity affects reservoir function. Reduction of reservoir function following exercise is related to TTI, a reflection of myocardial oxygen consumption but apparently not associated with coronary perfusion pressure.

  15. Intraocular pressure reduction and regulation

    NASA Technical Reports Server (NTRS)

    Baehr, E. F.; Mcgannon, W. J.

    1979-01-01

    System designed to reduce intraocular pressure hydraulically to any level desired by physician over set time and in controlled manner has number of uses in ophthalmology. Device may be most immediately useful in treatment of glaucoma.

  16. Intraocular pressure reduction and regulation

    NASA Technical Reports Server (NTRS)

    Baehr, E. F.; Mcgannon, W. J.

    1979-01-01

    System designed to reduce intraocular pressure hydraulically to any level desired by physician over set time and in controlled manner has number of uses in ophthalmology. Device may be most immediately useful in treatment of glaucoma.

  17. Pressure-Reduction Technique for Crystal Growth

    NASA Technical Reports Server (NTRS)

    Shlichta, P. J.

    1981-01-01

    Large crystals grown by varying pressure rather than temperature. In constant temerature pressure-reduction process crystal growth promoted as solubility decreases by factor of more than 10. Technique used to study crystal growth kinetics by "pressure wave"" analog of conventional "thermal wave" experiments. Technique has advantages of faster response and freedom from convective interference.

  18. Negative pressure device for intra-abdominal pressure reduction

    NASA Astrophysics Data System (ADS)

    David, M.; Geido, D.; Pracca, F.; Sánchez, G.; Simini, F.; Zoppolo, C.

    2007-11-01

    A device that generates negative extra-abdominal pressure (ABDOPRE) for treatment of patients with high intra-abdominal pressure was developed. It includes pressure sensors for transducing intra-abdominal pressure through an intra-vesical catheter and negative pressure in the vacuum bell which is placed over the abdomen. By means of a control system, a pattern for reducing IAP is set, according to a clinical protocol. The external negative pressure is generated using a vacuum pump connected to the bell. The system registers the values of interest for the medical history. The system is being tested over ICU patients, registering a satisfactory IAP reduction.

  19. Drag reduction in reservoir rock surface: Hydrophobic modification by SiO2 nanofluids

    NASA Astrophysics Data System (ADS)

    Yan, Yong-Li; Cui, Ming-Yue; Jiang, Wei-Dong; He, An-Le; Liang, Chong

    2017-02-01

    Based on the adsorption behavior of modified silica nanoparticles in the sandstone core surface, the hydrophobic surface was constructed, which consists of micro-nanoscale hierarchical structure. This modified core surface presents a property of drag reduction and meets the challenge of high injection pressure and low injection rate in low or ultra-low permeability reservoir. The modification effects on the surface of silica nanoparticles and reservoir cores, mainly concerning hydrophobicity and fine structure, were determined by measurements of contact angle and scanning electron microscopy. Experimental results indicate that after successful modification, the contact angle of silica nanoparticles varies from 19.5° to 141.7°, exhibiting remarkable hydrophobic properties. These modified hydrophobic silica nanoparticles display a good adsorption behavior at the core surface to form micro-nanobinary structure. As for the wettability of these modified core surfaces, a reversal has happened from hydrophilic into hydrophobic and its contact angle increases from 59.1° to 105.9°. The core displacement experiments show that the relative permeability for water has significantly increased by an average of 40.3% via core surface modification, with the effects of reducing injection pressure and improving injection performance of water flooding. Meanwhile, the mechanisms of drag reduction and improving water injection operation induced from the modified core surface were uncovered. The present study will establish a fundamental understanding on the drag reduction at the core surface modified by nanofluids and its applications in more industries.

  20. Local Turgor Pressure Reduction via Channel Clustering.

    PubMed

    Scher-Zagier, Jonah K; Carlsson, Anders E

    2016-12-20

    The primary drivers of yeast endocytosis are actin polymerization and curvature-generating proteins, such as clathrin and BAR domain proteins. Previous work has indicated that these factors may not be capable of generating the forces necessary to overcome turgor pressure. Thus local reduction of the turgor pressure, via localized accumulation or activation of solute channels, might facilitate endocytosis. The possible reduction in turgor pressure was calculated numerically, by solving the diffusion equation through a Legendre polynomial expansion. It was found that for a region of increased permeability having radius 45 nm, as few as 60 channels with a spacing of 10 nm could locally decrease the turgor pressure by 50%. We identified a key dimensionless parameter, p = P1a/D, where P1 is the increased permeability, a is the radius of the permeable region, and D is the solute diffusion coefficient. When p > 0.44, the turgor pressure is locally reduced by >50%. An approximate analytic theory was used to generate explicit formulas for the turgor pressure reduction in terms of key parameters. These findings may also be relevant to plants, where the mechanisms that allow endocytosis to proceed despite high turgor pressure are largely unknown. Copyright © 2016 Biophysical Society. Published by Elsevier Inc. All rights reserved.

  1. Understanding creep in sandstone reservoirs - theoretical deformation mechanism maps for pressure solution in granular materials

    NASA Astrophysics Data System (ADS)

    Hangx, Suzanne; Spiers, Christopher

    2014-05-01

    Subsurface exploitation of the Earth's natural resources removes the natural system from its chemical and physical equilibrium. As such, groundwater extraction and hydrocarbon production from subsurface reservoirs frequently causes surface subsidence and induces (micro)seismicity. These effects are not only a problem in onshore (e.g. Groningen, the Netherlands) and offshore hydrocarbon fields (e.g. Ekofisk, Norway), but also in urban areas with extensive groundwater pumping (e.g. Venice, Italy). It is known that fluid extraction inevitably leads to (poro)elastic compaction of reservoirs, hence subsidence and occasional fault reactivation, and causes significant technical, economic and ecological impact. However, such effects often exceed what is expected from purely elastic reservoir behaviour and may continue long after exploitation has ceased. This is most likely due to time-dependent compaction, or 'creep deformation', of such reservoirs, driven by the reduction in pore fluid pressure compared with the rock overburden. Given the societal and ecological impact of surface subsidence, as well as the current interest in developing geothermal energy and unconventional gas resources in densely populated areas, there is much need for obtaining better quantitative understanding of creep in sediments to improve the predictability of the impact of geo-energy and groundwater production. The key problem in developing a reliable, quantitative description of the creep behaviour of sediments, such as sands and sandstones, is that the operative deformation mechanisms are poorly known and poorly quantified. While grain-scale brittle fracturing plus intergranular sliding play an important role in the early stages of compaction, these time-independent, brittle-frictional processes give way to compaction creep on longer time-scales. Thermally-activated mass transfer processes, like pressure solution, can cause creep via dissolution of material at stressed grain contacts, grain

  2. Major influencing factors of water flooding in abnormally high-pressure carbonate reservoir

    NASA Astrophysics Data System (ADS)

    Qingying, Hou; Kaiyuan, Chen; Zifei, Fan; Libing, Fu; Yefei, Chen

    2017-01-01

    The higher pressure coefficient is the major characteristics of the abnormal high pressure carbonate reservoirs, which the pressure coefficient generally exceeds 1.2 and the initial formation pressure is higher than normal sandstone reservoirs. Due to the large pressure difference between initial formation and saturated pressure, oil wells are capable to production with high flow rate by the natural energy at early production stage. When the formation pressure drops to the saturation pressure, the water or gas is usually injected to stabilize the well productivity and sustain the formation pressure. Based on the characteristics of Kenkiak oilfield, a typical abnormal high pressure carbonate reservoir, a well group model is designed to simulate and analyze the influence factors on water flooding. The conclusion is that permeability, interlayer difference and reserve abundance are the main three factors on the water flooding development in these reservoirs.

  3. Steam Pressure Reduction, Opportunities, and Issues

    SciTech Connect

    Berry, Jan; Griffin, Mr. Bob; Wright, Anthony L

    2006-01-01

    Steam pressure reduction has the potential to reduce fuel consumption for a minimum capital investment. When the pressure at the boiler is reduced, fuel and steam are saved as a result of changes in the high-pressure side of the steam system from the boiler through the condensate return system. In the boiler plant, losses from combustion, boiler blowdown, radiation, and steam venting from condensate receivers would be reduced by reducing steam pressure. Similarly, in the steam distribution system, losses from radiation, flash steam vented from condensate receivers, and component and steam trap leakage would also be reduced. There are potential problems associated with steam pressure reduction, however. These may include increased boiler carryover, boiler water circulation problems in watertube boilers, increased steam velocity in piping, loss of power in steam turbines, and issues with pressure reducing valves. This paper is based a Steam Technical Brief sponsored by the U.S. Department of Energy (DOE) Office of Energy Efficiency and Renewable Energy and Enbridge Gas Distribution, Inc. (5). An example illustrates the use of DOE BestPractices Steam System Assessment Tool to model changes in steam, fuel, electricity generation, and makeup water and to estimate resulting economic benefits.

  4. Critically Pressured Free Gas Reservoirs Below Gas Hydrate Provinces

    NASA Astrophysics Data System (ADS)

    Hornbach, M. J.; Saffer, D. M.; Holbrook, W. S.

    2002-12-01

    Paleoceanographic evidence suggests that methane hydrates play a significant role in global climate change; however, mechanisms for sustained methane release into the biosphere during periods of global warming are poorly understood (Katz et al. 1999, Kennett et al., 2000). Here, we evaluate the possibility that gas flux into the hydrate stability zone, and perhaps into the oceans and atmosphere is mechanically regulated by hydrofracture or fault reactivation in overlying hydrate-bearing sediments. Our results reveal that a critical gas column thickness exists below most hydrate provinces in basin settings, implying that these hydrate provinces are poised for mechanical failure. Our results suggest that a free gas "wedge" of increasing thickness with BSR depth occurs in hydrate basins, and that a mechanically regulated maximum thickness of free gas exists. Furthermore, our results are consistent with observations of thicker free gas zones in deep hydrate basins and thin free gas zones on active, possibly water-phase overpressured, continental margins. Incorporating our result with Dickens' 2001 model for estimating BSR depths along ocean margins, and assuming 50% sediment porosity with gas filling 1% of the pore space, we calculate a value for the total free methane gas reservoir below all hydrate provinces to be 1/8 the total methane trapped in hydrate, or ~1300 Gt if 10,000 Gt of methane exists in hydrate (Kvenvolden, 1993). One key implication is that a significant reservoir of methane may exist as free gas beneath hydrate provinces that is highly sensitive to changes in pressure and temperature.

  5. Reviving Abandoned Reservoirs with High-Pressure Air Injection: Application in a Fractured and Karsted Dolomite Reservoir

    SciTech Connect

    Robert Loucks; Stephen C. Ruppel; Dembla Dhiraj; Julia Gale; Jon Holder; Jeff Kane; Jon Olson; John A. Jackson; Katherine G. Jackson

    2006-09-30

    Despite declining production rates, existing reservoirs in the United States contain vast volumes of remaining oil that is not being effectively recovered. This oil resource constitutes a huge target for the development and application of modern, cost-effective technologies for producing oil. Chief among the barriers to the recovery of this oil are the high costs of designing and implementing conventional advanced recovery technologies in these mature, in many cases pressure-depleted, reservoirs. An additional, increasingly significant barrier is the lack of vital technical expertise necessary for the application of these technologies. This lack of expertise is especially notable among the small operators and independents that operate many of these mature, yet oil-rich, reservoirs. We addressed these barriers to more effective oil recovery by developing, testing, applying, and documenting an innovative technology that can be used by even the smallest operator to significantly increase the flow of oil from mature U.S. reservoirs. The Bureau of Economic Geology and Goldrus Producing Company assembled a multidisciplinary team of geoscientists and engineers to evaluate the applicability of high-pressure air injection (HPAI) in revitalizing a nearly abandoned carbonate reservoir in the Permian Basin of West Texas. The Permian Basin, the largest oil-bearing basin in North America, contains more than 70 billion barrels of remaining oil in place and is an ideal venue to validate this technology. We have demonstrated the potential of HPAI for oil-recovery improvement in preliminary laboratory tests and a reservoir pilot project. To more completely test the technology, this project emphasized detailed characterization of reservoir properties, which were integrated to access the effectiveness and economics of HPAI. The characterization phase of the project utilized geoscientists and petroleum engineers from the Bureau of Economic Geology and the Department of Petroleum

  6. REVIVING ABANDONED RESERVOIRS WITH HIGH-PRESSURE AIR INJECTION: APPLICATION IN A FRACTURED AND KARSTED DOLOMITE RESERVOIR

    SciTech Connect

    Robert Loucks; Steve Ruppel; Julia Gale; Jon Holder; Jon Olsen; Deanna Combs; Dhiraj Dembla; Leonel Gomez

    2003-06-01

    The Bureau of Economic Geology and Goldrus Producing Company have assembled a multidisciplinary team of geoscientists and engineers to evaluate the applicability of high-pressure air injection (HPAI) in revitalizing a nearly abandoned carbonate reservoir in the Permian Basin of West Texas. The characterization phase of the project is utilizing geoscientists and petroleum engineers from the bureau of Economic Geology and the Department of Petroleum Engineering (both at The University of Texas at Austin) to define the controls on fluid flow in the reservoir as a basis for developing a reservoir model. This model will be used to define a field deployment plant that Goldrus, a small independent oil company, will implement by drilling both vertical and horizontal wells during the demonstration phase of the project. Additional reservoir data are being gathered during the demonstration phase to improve the accuracy of the reservoir model. The results of the demonstration are being closely monitored to provide a basis for improving the design of the HPAI field deployment plan. The results of the reservoir characterization field demonstration and monitoring program will be documented and widely disseminated to facilitate adoption of this technology by oil operators in the Permian Basin and elsewhere in the US.

  7. Determination of the Pressure Field in a Reservoir-Deformed Bed Exposed to Vibrowaves

    NASA Astrophysics Data System (ADS)

    Abbasov, É. M.; Agaeva, N. A.

    2017-01-01

    On the basis of theoretical investigations, the authors have determined the pressure field in a deformable bed exposed to vibrowaves. A study has been made of the propagation of various forms of elastic waves in a deformable bed. An analytical expression has been obtained for the bottom-hole pressure with account of the deformation of thebed's reservoir. It has been shown that the degree of attenuation of elastic waves in beds with deformable reservoirs increases strongly compared to undeformable ones.

  8. Improving multi-objective reservoir operation optimization with sensitivity-informed dimension reduction

    NASA Astrophysics Data System (ADS)

    Chu, J.; Zhang, C.; Fu, G.; Li, Y.; Zhou, H.

    2015-08-01

    This study investigates the effectiveness of a sensitivity-informed method for multi-objective operation of reservoir systems, which uses global sensitivity analysis as a screening tool to reduce computational demands. Sobol's method is used to screen insensitive decision variables and guide the formulation of the optimization problems with a significantly reduced number of decision variables. This sensitivity-informed method dramatically reduces the computational demands required for attaining high-quality approximations of optimal trade-off relationships between conflicting design objectives. The search results obtained from the reduced complexity multi-objective reservoir operation problems are then used to pre-condition the full search of the original optimization problem. In two case studies, the Dahuofang reservoir and the inter-basin multi-reservoir system in Liaoning province, China, sensitivity analysis results show that reservoir performance is strongly controlled by a small proportion of decision variables. Sensitivity-informed dimension reduction and pre-conditioning are evaluated in their ability to improve the efficiency and effectiveness of multi-objective evolutionary optimization. Overall, this study illustrates the efficiency and effectiveness of the sensitivity-informed method and the use of global sensitivity analysis to inform dimension reduction of optimization problems when solving complex multi-objective reservoir operation problems.

  9. Transient pressure behavior for a horizontal well with multiple finite-conductivity fractures in tight reservoirs

    NASA Astrophysics Data System (ADS)

    Guo, Jingjing; Wang, Haitao; Zhang, Liehui

    2015-08-01

    Horizontal drilling and multi-stage hydraulic fracturing have been common and efficient practices in exploitation of tight reservoirs. Establishing corresponding mathematical models and analyzing transient pressure behaviors of this type of well-reservoir configuration can provide a better understanding of fluid flow patterns in formation as well as estimations of important parameters. Most current models proposed for fractured horizontal wells in tight reservoirs do not incorporate either reservoir permeability loss during the production, which is believed to be non-ignorable or finite conductivity of hydraulic fractures. A coupling model for a multi-fractured horizontal well (MFHW) in tight reservoirs is presented in this article, in which finite conductivity of hydraulic fractures and stress-dependant reservoir permeability are taken into account simultaneously. A semi-analytical solution is obtained in the Laplace domain by using source function theory, Laplace transformation, perturbation technique, discretization of fractures, and superposition principle. Analysis of transient pressure responses indicates that several characteristic flow periods of fractured horizontal wells in tight reservoirs can be identified, including linear flow in fracture, bi-linear flow, linear flow in reservoir, pseudo-radial flow around fractures, and pseudo-radial flow around the horizontal wellbore and fractures. Parametric analysis shows that fracture conductivity, fracture spacing, fracture length, permeability modulus, and skin effect can significantly influence the transient pressure responses of fractured horizontal wells in tight reservoirs. The model presented in this article can be applied to obtain important parameters pertinent to reservoir or fractures by type curve matching, and it can also provide useful information for optimizing fracture parameters. Finally, the model presented in this article can also be easily extended to dual-porosity cases.

  10. Genesis of the characteristic pulmonary venous pressure waveform as described by the reservoir-wave model.

    PubMed

    Bouwmeester, J Christopher; Belenkie, Israel; Shrive, Nigel G; Tyberg, John V

    2014-09-01

    Conventional haemodynamic analysis of pulmonary venous and left atrial (LA) pressure waveforms yields substantial forward and backward waves throughout the cardiac cycle; the reservoir wave model provides an alternative analysis with minimal waves during diastole. Pressure and flow in a single pulmonary vein (PV) and the main pulmonary artery (PA) were measured in anaesthetized dogs and the effects of hypoxia and nitric oxide, volume loading, and positive-end expiratory pressure (PEEP) were observed. The reservoir wave model was used to determine the reservoir contribution to PV pressure and flow. Subtracting reservoir pressure and flow resulted in 'excess' quantities which were treated as wave-related.Wave intensity analysis of excess pressure and flow quantified the contributions of waves originating upstream (from the PA) and downstream (from the LA and/or left ventricle (LV)).Major features of the characteristic PV waveform are caused by sequential LA and LV contraction and relaxation creating backward compression (i.e.pressure-increasing) waves followed by decompression (i.e. pressure-decreasing) waves. Mitral valve opening is linked to a backwards decompression wave (i.e. diastolic suction). During late systole and early diastole, forward waves originating in the PA are significant. These waves were attenuated less with volume loading and delayed with PEEP. The reservoir wave model shows that the forward and backward waves are negligible during LV diastasis and that the changes in pressure and flow can be accounted for by the discharge of upstream reservoirs. In sharp contrast, conventional analysis posits forward and backward waves such that much of the energy of the forward wave is opposed by the backward wave.

  11. Genesis of the characteristic pulmonary venous pressure waveform as described by the reservoir-wave model

    PubMed Central

    Bouwmeester, J Christopher; Belenkie, Israel; Shrive, Nigel G; Tyberg, John V

    2014-01-01

    Conventional haemodynamic analysis of pulmonary venous and left atrial (LA) pressure waveforms yields substantial forward and backward waves throughout the cardiac cycle; the reservoir wave model provides an alternative analysis with minimal waves during diastole. Pressure and flow in a single pulmonary vein (PV) and the main pulmonary artery (PA) were measured in anaesthetized dogs and the effects of hypoxia and nitric oxide, volume loading, and positive-end expiratory pressure (PEEP) were observed. The reservoir wave model was used to determine the reservoir contribution to PV pressure and flow. Subtracting reservoir pressure and flow resulted in ‘excess’ quantities which were treated as wave-related. Wave intensity analysis of excess pressure and flow quantified the contributions of waves originating upstream (from the PA) and downstream (from the LA and/or left ventricle (LV)). Major features of the characteristic PV waveform are caused by sequential LA and LV contraction and relaxation creating backward compression (i.e. pressure-increasing) waves followed by decompression (i.e. pressure-decreasing) waves. Mitral valve opening is linked to a backwards decompression wave (i.e. diastolic suction). During late systole and early diastole, forward waves originating in the PA are significant. These waves were attenuated less with volume loading and delayed with PEEP. The reservoir wave model shows that the forward and backward waves are negligible during LV diastasis and that the changes in pressure and flow can be accounted for by the discharge of upstream reservoirs. In sharp contrast, conventional analysis posits forward and backward waves such that much of the energy of the forward wave is opposed by the backward wave. PMID:25015922

  12. Pre-injection brine production for managing pressure in compartmentalized CO₂ storage reservoirs

    DOE PAGES

    Buscheck, Thomas A.; White, Joshua A.; Chen, Mingjie; ...

    2014-12-31

    We present a reservoir management approach for geologic CO₂ storage that combines CO₂ injection with brine extraction. In our approach,dual-mode wells are initially used to extract formation brine and subsequently used to inject CO₂. These wells can also be used to monitor the subsurface during pre-injection brine extraction so that key data is acquired and analyzed prior to CO₂ injection. The relationship between pressure drawdown during pre-injection brine extraction and pressure buildup during CO₂ injection directly informs reservoir managers about CO₂ storage capacity. These data facilitate proactive reservoir management, and thus reduce costs and risks. The brine may be usedmore » directly as make-up brine for nearby reservoir operations; it can also be desalinated and/or treated for a variety of beneficial uses.« less

  13. Pre-injection brine production for managing pressure in compartmentalized CO₂ storage reservoirs

    SciTech Connect

    Buscheck, Thomas A.; White, Joshua A.; Chen, Mingjie; Sun, Yunwei; Hao, Yue; Aines, Roger D.; Bourcier, William L.; Bielicki, Jeffrey M.

    2014-12-31

    We present a reservoir management approach for geologic CO₂ storage that combines CO₂ injection with brine extraction. In our approach,dual-mode wells are initially used to extract formation brine and subsequently used to inject CO₂. These wells can also be used to monitor the subsurface during pre-injection brine extraction so that key data is acquired and analyzed prior to CO₂ injection. The relationship between pressure drawdown during pre-injection brine extraction and pressure buildup during CO₂ injection directly informs reservoir managers about CO₂ storage capacity. These data facilitate proactive reservoir management, and thus reduce costs and risks. The brine may be used directly as make-up brine for nearby reservoir operations; it can also be desalinated and/or treated for a variety of beneficial uses.

  14. Pore pressure prediction in laminated shaly sand reservoir: A case study of Bintuni Basin

    NASA Astrophysics Data System (ADS)

    Haris, A.; Parlindungan, E.; Riyanto, A.

    2017-07-01

    Pore pressure prediction has been carried out using well log and seismic velocity data to evaluate pore pressure character of the laminated shally sand reservoir in Bintuni Basin, West Papua. The majority of the thin laminated reservoir are below resolving power of logging tool. The main factor of reservoir behavior, which typically exhibits composition mineral of lithic, micaceous and glauconitic, has a strong relationship with conductive mineral. Based on total gas mud logging data, there is some potential gas reservoir. In this study, non-normal high pore pressure was identified in some intervals and designed for cases where compaction disequilibrium is the cause of fluid expansion on the compaction state of the impermeable sediments. We used Eaton's method to estimate pore pressure gradient. We also performed seismic velocity model analysis to estimate the effective stress using empirical Bowers and Terzaghi method, where horizontal and vertical pressure data were distributed using probabilistic neural network method. Our analysis on the pore pressure distribution map, which is combined with the time structure, shows that the correlation of non normal pore pressure is found not only in height structure but also in the low structure, particularly at the southern part of the study area.

  15. REVIVING ABANDONED RESERVOIRS WITH HIGH-PRESSURE AIR INJECTION: APPLICATION IN A FRACTURED AND KARSTED DOLOMITE RESERVOIR

    SciTech Connect

    Robert Loucks; Steve Ruppel; Julia Gale; Jon Holder; Jon Olson; Deanna Combs; Dhiraj Dembla

    2004-06-01

    The Bureau of Economic Geology (BEG) and Goldrus Producing Company have assembled a multidisciplinary team of geoscientists and engineers to evaluate the applicability of high-pressure air injection (HPAI) in revitalizing a nearly abandoned carbonate reservoir in the Permian Basin of West Texas. The characterization phase of the project is utilizing geoscientists and petroleum engineers from the Bureau of Economic Geology (BEG) and the Department of Petroleum and Geosystems Engineering (both at The University of Texas at Austin) to define the controls on fluid flow in the reservoir as a basis for developing a reservoir model. This model will be used to define a field deployment plan that Goldrus, a small independent oil company, will implement by drilling both vertical and horizontal wells during the demonstration phase of the project. Additional reservoir data were to be generated during the demonstration phase to improve the accuracy of the reservoir model. The demonstration phase has been delayed by Goldrus because of funding problems. Since the first of the year, Goldrus has been active in searching for partners to help finance the project. To this end it has commissioned several small consulting studies to technically support its effort to secure a partner. After financial support is obtained, the demonstration phase of the project will proceed. Since just after the beginning of the year, BEG has curtailed project activities and spending of DOE funds except for the continued support of one engineering student. This student has now completed his work and has written a thesis describing his research (titled ''Stimulating enhanced oil recovery (EOR) by high-pressure air injection (HPAI) in west Texas light oil reservoir''). We plan to recommence our work on the project as soon as the operator obtains necessary funding to carry out the demonstration phase of the project. In order to complete all activities specified in the proposal, it will be necessary to request

  16. Pressurization Risk Assessment of CO2 Reservoirs Utilizing Design of Experiments and Response Surface Methods

    NASA Astrophysics Data System (ADS)

    Guyant, E.; Han, W. S.; Kim, K. Y.; Park, E.; Han, K.

    2015-12-01

    Monitoring of pressure buildup can provide explicit information on reservoir integrity and is an appealing tool, however pressure variation is dependent on a variety of factors causing high uncertainty in pressure predictions. This work evaluated pressurization of a reservoir system in the presence of leakage pathways as well as exploring the effects of compartmentalization of the reservoir utilizing design of experiments (Definitive Screening, Box Behnken, Central Composite, and Latin Hypercube designs) and response surface methods. Two models were developed, 1) an idealized injection scenario in order to evaluate the performance of multiple designs, and 2) a complex injection scenario implementing the best performing design to investigate pressurization of the reservoir system. A holistic evaluation of scenario 1, determined that the Central Composite design would be used for the complex injection scenario. The complex scenario evaluated 5 risk factors: reservoir, seal, leakage pathway and fault permeabilities, and horizontal position of the pathway. A total of 60 response surface models (RSM) were developed for the complex scenario with an average R2 of 0.95 and a NRMSE of 0.067. Sensitivity to the input factors was dynamic through space and time; at the earliest time (0.05 years) the reservoir permeability was dominant, and for later times (>0.5 years) the fault permeability became dominant for all locations. The RSM's were then used to conduct a Monte Carlo Analysis to further analyze pressurization risks, identifying the P10, P50, P90 values. This identified the in zone (lower) P90 values as 2.16, 1.77, and 1.53 MPa and above zone values of 1.35, 1.23, 1.09 MPa for monitoring locations 1, 2, and 3, respectively. In summary, the design of experiments and response surface methods allowed for an efficient sensitivity and uncertainty analysis to be conducted permitting a complete evaluation of the pressurization across the entire parameter space.

  17. Reduction of Orifice-Induced Pressure Errors

    NASA Technical Reports Server (NTRS)

    Plentovich, Elizabeth B.; Gloss, Blair B.; Eves, John W.; Stack, John P.

    1987-01-01

    Use of porous-plug orifice reduces or eliminates errors, induced by orifice itself, in measuring static pressure on airfoil surface in wind-tunnel experiments. Piece of sintered metal press-fitted into static-pressure orifice so it matches surface contour of model. Porous material reduces orifice-induced pressure error associated with conventional orifice of same or smaller diameter. Also reduces or eliminates additional errors in pressure measurement caused by orifice imperfections. Provides more accurate measurements in regions with very thin boundary layers.

  18. Pressure reduction with a hospitalized population using a mattress overlay.

    PubMed

    Suarez, C H; Reynolds, A

    1995-01-01

    Billions of dollars are spent each year on treating pressure ulcers. With healthcare costs climbing and reform the order of the day, it is essential for researchers to identify a device which reduces pressure, is easy to use and is cost effective. This study used a Mini-Tipe pressure sensor to measure pressure readings over the sacral and trochanter areas of 17 subjects identified as being at risk for skin breakdown. Pressures were compared on a standard hospital mattress and an anatomically contoured mattress overlay. There was a 48 percent reduction in mean pressures over the sacral area and a 23 percent reduction over the trochanter. No correlations between pressures and demographic data were identified. Further research is warranted to determine the effects of variables found in an "at risk" population on pressure reduction with various products.

  19. REVIVING ABANDONED RESERVOIRS WITH HIGH-PRESSURE AIR INJECTION: APPLICATION IN A FRACTURED AND KARSTED DOLOMITE RESERVOIR

    SciTech Connect

    Robert Loucks; Stephen C. Ruppel

    2006-02-01

    The field operator, Goldrus Producing Company, has been unable to secure funding needed to continue the field demonstration phase of the project. Accordingly, we have temporarily halted all project activities until necessary funding is obtained. Goldrus felt confident that funds could be acquired by third quarter 2005 at which time it would have been necessary to request a project extension to complete the originally designed study. A project extension was granted but it appears Goldrus will have difficulty securing funds. We Bureau of Economic Geology are investigating a new approach on how to fulfill our initial objectives of promoting high-pressure air injection of Ellenburger reservoirs.

  20. Layer definition and pressure buildup case histories in a carbonate reservoir

    SciTech Connect

    Vadgama, U.N.; Arifi, N.A.

    1981-01-01

    This paper presents case histories of pressure buildup analysis in a layered carbonate reservoir (Zella/Aswad Fields in the Socialist People's Libyan Arab Jamahiria). The productive formation consists of several dolomite and limestone layers separated by thin tight streaks. Lack of pressure communication between layers has been determined by pressure measurements in the individual layers using the Repeat Formation Tester (RFT). Results of the two-dimensional radial model simulated pressure buildup performance are compared to the actual measured pressure buildup data. 14 refs.

  1. Alternative method to Mariotte reservoir system for maintaining constant hydraulic pressure

    USGS Publications Warehouse

    Thamir, Falah; ,

    1991-01-01

    Several problems with the Mariotte reservoir system were discovered when it was used to apply a constant water pressure as a boundary condition for a prolonged period. The constant-pressure boundary condition is required for some laboratory experiments to study water flow through porous media. The observed problems were caused by temperature and barometric-pressure fluctuations while the flow rates were very small and caused erroneous water flow-rate measurements. An alternative method was developed and used where the water pressure is controlled by regulating its level by using water-level sensing electrodes. The new method eliminated the effects of temperature and barometric-pressure fluctuations and maintained an acceptable accuracy of the estimated water flow rate without compromising the advantages of the Mariotte reservoir.

  2. Review: Alternative Placement of Penile Prosthesis Reservoir and AUS Pressure Regulating Balloon.

    PubMed

    Reznicek, Daniel G; Bryson, Richard; Kramer, Andrew C

    2015-03-01

    Ectopic placement of prosthetic balloons and reservoirs in urological surgery has gained popularity, and early experience suggests that such placement is safe and efficacious. We review the artificial urinary sphincter (AUS) pressure regulating balloon (PRB) and inflatable penile prosthesis (IPP) reservoir placement and the factors relating to ectopic vs. traditional paravesical placement of these devices. Articles from peer-reviewed journals, abstracts, and surgeons' series of outcomes form the basis for this review. Relevant mechanical function of devices and pertinent anatomy is reviewed. To review the current data regarding ectopic and conventional reservoir placement for the AUS and IPP. Traditional and ectopic placements of the AUS PRB and IPP reservoir have been shown to be safe and effective. There are well-documented risks associated with both traditional and ectopic approaches, and these risks must be weighed in the context of a specific clinical scenario and surgeon comfort. Traditional and ectopic placement of prosthetic balloons and reservoirs should be guided by patient characteristics and surgeon experience. Our early experience is in agreement with that of others in that ectopic placement of these devices appears to be a viable alternative in the appropriately selected patient and may be a technically easy procedure to learn for the experienced prosthetic surgeon. Reznicek DG, Bryson R, and Kramer AC. Alternative placement of penile prosthesis reservoir and AUS pressure regulating balloon. Sex Med Rev 2015;3:48-55. Copyright © 2015 International Society for Sexual Medicine. Published by Elsevier Inc. All rights reserved.

  3. Pressure losses in fracture-dominated reservoirs: the wellbore constriction effect

    SciTech Connect

    Murphy, H.

    1980-01-01

    Improved energy production from many types of energy reservoirs such as hot dry rock geothermal as well as hydraulically fractured oil, gas, and other geothermal reservoirs requires a better understanding of the fluid mechanics in the vicinity of the fracture-wellbore intersection. Typically, the aperture (smallest dimension) of a hydraulic fracture is only of the order of 1 mm (0.04 in.) so that reasonable energy production rates from geothermal systems require fairly large flow velocities within the fractures, particularly so as the wellbore-fracture intersection is approached. The high velocities and accelerations result in non-Darcian, often turbulent, flow and increased pressure losses. These flow phenomena were investigated experimentally for the simple case where the fracture plane and the wellbore drilling axis are orthogonal and the implication of these experimental results are examined by investigating the pressure losses in a hot dry rock reservoir.

  4. REVIVING ABANDONED RESERVOIRS WITH HIGH-PRESSURE AIR INJECTION: APPLICATION IN A FRACTURED AND KARSTED DOLOMITE RESERVOIR

    SciTech Connect

    Robert Loucks; Steve Ruppel; Julia Gale; Jon Holder; Jon Olson

    2005-01-01

    The Bureau of Economic Geology (BEG) and Goldrus Producing Company have assembled a multidisciplinary team of geoscientists and engineers to evaluate the applicability of high-pressure air injection (HPAI) in revitalizing a nearly abandoned carbonate reservoir in the Permian Basin of West Texas. The characterization phase of the project is utilizing geoscientists and petroleum engineers from the Bureau of Economic Geology (BEG) and the Department of Petroleum and Geosystems Engineering (both at The University of Texas at Austin) to define the controls on fluid flow in the reservoir as a basis for developing a reservoir model. This model will be used to define a field deployment plan that Goldrus, a small independent oil company, will implement by drilling both vertical and horizontal wells during the demonstration phase of the project. Additional reservoir data were to be generated during the demonstration phase to improve the accuracy of the reservoir model. The demonstration phase has been delayed by Goldrus because of funding problems. Since the first of the year, Goldrus has been active in searching for partners to help finance the project. After financial support is obtained, the demonstration phase of the project will proceed. Since just after the beginning of the year, BEG has curtailed project activities and spending of DOE funds except for the continued support of one engineering student. This student has now completed his work and his thesis was reported on in the last semi-annual report. We plan to recommence our work on the project as soon as the operator obtains necessary funding to carry out the demonstration phase of the project. In order to complete all activities specified in the proposal, we requested and received an extension of the project to September 30, 2005. We are confident that Goldrus will obtain the necessary funding to continue and that we can complete the project by the end of the extension data. We strongly believe that the results of

  5. Transient-pressure analysis in geothermal steam reservoirs with an immobile vaporizing liquid phase

    USGS Publications Warehouse

    Moench, A.F.; Atkinson, P.G.

    1978-01-01

    A finite-difference model for the radial horizontal flow of steam through a porous medium is used to evaluate transient-pressure behavior in the presence of an immobile vaporizing or condensing liquid phase. Graphs of pressure drawdown and buildup in terms of dimensionless pressure and time are obtained for a well discharging steam at a constant mass flow rate for a specified time. The assumptions are made that the steam is in local thermal equilibrium with the reservoir rocks, that temperature changes are due only to phase change, and that effects of vapor-pressure lowering are negligible. Computations show that when a vaporizing liquid phase is present the pressure drawdown exhibits behavior similar to that observed in noncondensable gas reservoirs, but delayed in time. A theoretical analysis allows for the computation of this delay and demonstrates that it is independent of flow geometry. The response that occurs upon pressure buildup is markedly different from that in a noncondensable gas system. This result may provide a diagnostic tool for establishing the existence of phase-change phenomena within a reservoir. ?? 1979.

  6. Pressure-velocity relations in reservoir rocks: Modified MacBeth's equation

    NASA Astrophysics Data System (ADS)

    Grana, Dario

    2016-09-01

    The knowledge of the saturation and pressure effects on elastic properties is a key factor in reservoir monitoring. The relation between saturation changes and velocity variations is well known in rock physics and at seismic frequency it can be satisfactorily described by Gassmann's equations. The pressure effect still requires deeper investigations in order to be included in rock physics models for 4D studies. Theoretical models of velocity-pressure relations often do not match lab measurements, or contain empirical constants or theoretical parameters that are difficult to calibrate or do not have a precise physical meaning. In this work, I present a new model to describe the pressure sensitivity of elastic moduli for clastic rocks. The proposed model is an extension of MacBeth's relations. These equations are then integrated within a complete rock physics model to describe the relation between rock properties (porosity and clay content), dynamic attributes (saturation and pressure) and elastic properties. The proposed model is calibrated with laboratory measurements of dry samples over a wide range of pressure variations and then applied to well data to simulate different production scenarios. The complete rock physics model can then be used in time-lapse inversion to predict the distribution of dynamic property changes in the reservoir within an inversion workflow for reservoir monitoring.

  7. HIGH-PRESSURE AIR INJECTION: APPLICATION IN A FRACTURED AND KARSTED DOLOMITE RESERVOIR

    SciTech Connect

    Robert Loucks; Steve Ruppel; Julia Gale; Jon Holder; Jon Olsen; Deanna Combs; Dhiraj Dembla; Leonel Gomez

    2003-12-10

    The Bureau of Economic Geology and Goldrus Producing Company have assembled a multidisciplinary team of geoscientists and engineers to evaluate the applicability of high-pressure air injection (HPAI) in revitalizing a nearly abandoned carbonate reservoir in the Permian Basin of West Texas. The characterization phase of the project is utilizing geoscientists and petroleum engineers from the Bureau of Economic Geology and the Department of Petroleum Engineering (both at The University of Texas at Austin) to define the controls on fluid flow in the reservoir as a basis for developing a reservoir model. This model will be used to define a field deployment plan that Goldrus, a small independent oil company, will implement by drilling both vertical and horizontal wells during the demonstration phase of the project. Additional reservoir data are being gathered during the demonstration phase to improve the accuracy of the reservoir model. The results of the demonstration will being closely monitored to provide a basis for improving the design of the HPAI field deployment plan. The results of the reservoir characterization field demonstration and monitoring program will be documented and widely disseminated to facilitate adoption of this technology by oil operators in the Permian Basin and elsewhere in the U.S.

  8. Pressure and fluid-flow response to production from reservoirs bounded by faults with relay structures

    SciTech Connect

    Matthaei, S.K.; Aydin, A.; Pollard, D.D.

    1996-12-31

    Compartmentatilization of hydrocarbon reservoirs by faults is a widely observed phenomenon in the North Sea and the Niger delta oil fields among others. Faults with significant throw or heave are identifiable in seismic surveys. However, toward their terminations or near relay structures, slip decreases so portions of the faults may be invisible in seismic data. Therefore, we use outcrop analogs to constrain the model geometry and permeability distributions to investigate the influence on fluid flow during production of such relay structures and the apparent terminations of faults in seismic images. We employ field measurements of the geometry, width and permeability of fault terminations and relay structures in the Entrada Sandstone, Arches National Park, Utah, to construct fluid flow models of a fault-bounded analog reservoir. Production from wells drilled into this reservoir is simulated with a novel high-resolution finite element code. Starting with initially uniform reservoir pressure, the results of these simulations based on geologically realistic parameters, comprise pressure differentials that build up during production across seismically detectable faults with associated deformation bands and joints in the relay structure. For a typical relay structure, we explore the implications of these results for fault-seal stability and for changes in reservoir flow patterns if fault permeability changes during production.

  9. Pressure and fluid-flow response to production from reservoirs bounded by faults with relay structures

    SciTech Connect

    Matthaei, S.K.; Aydin, A.; Pollard, D.D. )

    1996-01-01

    Compartmentatilization of hydrocarbon reservoirs by faults is a widely observed phenomenon in the North Sea and the Niger delta oil fields among others. Faults with significant throw or heave are identifiable in seismic surveys. However, toward their terminations or near relay structures, slip decreases so portions of the faults may be invisible in seismic data. Therefore, we use outcrop analogs to constrain the model geometry and permeability distributions to investigate the influence on fluid flow during production of such relay structures and the apparent terminations of faults in seismic images. We employ field measurements of the geometry, width and permeability of fault terminations and relay structures in the Entrada Sandstone, Arches National Park, Utah, to construct fluid flow models of a fault-bounded analog reservoir. Production from wells drilled into this reservoir is simulated with a novel high-resolution finite element code. Starting with initially uniform reservoir pressure, the results of these simulations based on geologically realistic parameters, comprise pressure differentials that build up during production across seismically detectable faults with associated deformation bands and joints in the relay structure. For a typical relay structure, we explore the implications of these results for fault-seal stability and for changes in reservoir flow patterns if fault permeability changes during production.

  10. Mechanical characterization of a CO2 fractured reservoir by means of microseismicity induced by high pressure injection tests

    NASA Astrophysics Data System (ADS)

    De Simone, Silvia; Soler, Joaquim; Carrera, Jesus; Slooten, Luit Jan; Ortiz, Gema

    2014-05-01

    Reservoir characterization is an essential issue in geological storage of CO2 in Technological Development Plant (TDP). In particular, hydromechanical characterization of the caprock-reservoir system is crucial, in order to define the maximum suitable injection pressure and the in-situ mechanical properties. Thus, it is possible to conjecture the hydromechanical behavior of the system during CO2 injection. Microseismicity induced by fluid injection may be used as instruments to find out fractured reservoir properties. Indeed, the hydromechanical response is controlled by permeability (k), Young modulus (E) and Poisson ratio (ν). In caprock-reservoir systems, reservoir stiffness controls the stress transfer towards the caprock, where failure may occur. Therefore, the location of the microseismic hypocenters could give information on the reservoir stiffness. In this work we propose a simulation and calibration method of the microseismicity induced by high pressure fluid injection in a fractured reservoir. Coupled hydromechanical models are peformed. The methology is applied to a particular case study.

  11. Rapid reduction of blood pressure with acute oral labetalol.

    PubMed Central

    Davies, A B; Bala Subramanian, V; Gould, B; Raftery, E B

    1982-01-01

    1 The effect of acute oral administration of labetalol on intra-arterial pressures in a group of ten hypertensive patients has been evaluated. 2 A single dose of 200 mg labetalol produced a significant reduction in systolic and diastolic pressures within 1 h of administration. 3 Within 24 h of initial administration, 200 mg three times daily produced a significant reduction in ambulant arterial levels of systolic pressure for 21 h and diastolic pressure for 14 h in the day. 4 Acute therapy lowered resting levels but there was no significant reduction in systolic pressure during either isometric or dynamic exercise. 5 Acute therapy was not associated with any significant postural hypotension. PMID:7082539

  12. An analytical model for pressure of volume fractured tight oil reservoir with horizontal well

    NASA Astrophysics Data System (ADS)

    Feng, Qihong; Dou, Kaiwen; Zhang, Xianmin; Xing, Xiangdong; Xia, Tian

    2017-05-01

    The property of tight oil reservoir is worse than common reservoir that we usually seen before, the porosity and permeability is low, the diffusion is very complex. Therefore, the ordinary depletion method is useless here. The volume fracture breaks through the conventional EOR mechanism, which set the target by amplifying the contact area of fracture and reservoir so as to improving the production of every single well. In order to forecast the production effectively, we use the traditional dual-porosity model, build an analytical model for production of volume fractured tight oil reservoir with horizontal well, and get the analytical solution in Laplace domain. Then we construct the log-log plot of dimensionless pressure and time by stiffest conversion. After that, we discuss the influential factors of pressure. Several factors like cross flow, skin factors and threshold pressure gradient was analyzed in the article. This model provides a useful method for tight oil production forecast and it has certain guiding significance for the production capacity prediction and dynamic analysis.

  13. 3-D Modeling of Pore Pressure Diffusion Beneath Koyna and Warna Reservoirs, Western India

    NASA Astrophysics Data System (ADS)

    Yadav, Amrita; Gahalaut, Kalpna; Purnachandra Rao, N.

    2017-05-01

    The mechanism of reservoir-triggered seismicity is well-understood and explains the earthquake occurrence at different reservoir sites. It can be attributed to the stresses due to water loading and to changes in fluid pressure in pores within the rock matrix. In the present study a 3-D fluid flow numerical model is used to investigate the pore pressure diffusion as a cause for continued seismicity in the Koyna-Warna region in western India. It is shown that reservoir water level fluctuations are sufficient to trigger earthquakes at the seismogenic depths in the region. Our numerical model suggests that a vertical fault with hydraulic conductivity in the range 2-6 m/day facilitates the diffusion of pressure at focal depths of earthquakes in the Koyna-Warna region. Also, for triggering of earthquakes a higher vertical conductivity is required for the Warna region than for the Koyna region. A lag of two months period is found between the maximum water level and the significant hydraulic head required to trigger earthquakes at the focal depth using the appropriate hydraulic conductivity for both the reservoirs.

  14. 3-D Modeling of Pore Pressure Diffusion Beneath Koyna and Warna Reservoirs, Western India

    NASA Astrophysics Data System (ADS)

    Yadav, Amrita; Gahalaut, Kalpna; Purnachandra Rao, N.

    2017-03-01

    The mechanism of reservoir-triggered seismicity is well-understood and explains the earthquake occurrence at different reservoir sites. It can be attributed to the stresses due to water loading and to changes in fluid pressure in pores within the rock matrix. In the present study a 3-D fluid flow numerical model is used to investigate the pore pressure diffusion as a cause for continued seismicity in the Koyna-Warna region in western India. It is shown that reservoir water level fluctuations are sufficient to trigger earthquakes at the seismogenic depths in the region. Our numerical model suggests that a vertical fault with hydraulic conductivity in the range 2-6 m/day facilitates the diffusion of pressure at focal depths of earthquakes in the Koyna-Warna region. Also, for triggering of earthquakes a higher vertical conductivity is required for the Warna region than for the Koyna region. A lag of two months period is found between the maximum water level and the significant hydraulic head required to trigger earthquakes at the focal depth using the appropriate hydraulic conductivity for both the reservoirs.

  15. Equation of state density models for hydrocarbons in ultradeep reservoirs at extreme temperature and pressure conditions

    NASA Astrophysics Data System (ADS)

    Wu, Yue; Bamgbade, Babatunde A.; Burgess, Ward A.; Tapriyal, Deepak; Baled, Hseen O.; Enick, Robert M.; McHugh, Mark A.

    2013-10-01

    The necessity of exploring ultradeep reservoirs requires the accurate prediction of hydrocarbon density data at extreme temperatures and pressures. In this study, three equations of state (EoS) models, Peng-Robinson (PR), high-temperature high-pressure volume-translated PR (HTHP VT-PR), and perturbed-chain statistical associating fluid theory (PC-SAFT) EoS are used to predict the density data for hydrocarbons in ultradeep reservoirs at temperatures to 523 K and pressures to 275 MPa. The calculated values are compared with experimental data. The results show that the HTHP VT-PR EoS and PC-SAFT EoS always perform better than the regular PR EoS for all the investigated hydrocarbons.

  16. An alternative to reduction of surface pressure to sea level

    NASA Technical Reports Server (NTRS)

    Deardorff, J. W.

    1982-01-01

    The pitfalls of the present method of reducing surface pressure to sea level are reviewed, and an alternative, adjusted pressure, P, is proposed. P is obtained from solution of a Poisson equation over a continental region, using the simplest boundary condition along the perimeter or coastline where P equals the sea level pressure. The use of P would avoid the empiricisms and disadvantages of pressure reduction to sea level, and would produce surface pressure charts which depict the true geostrophic wind at the surface.

  17. [Diffusion flux of partial pressure of dissolved carbon dioxide in Wan'an reservoir in spring].

    PubMed

    Mei, Hang-Yuan; Wang, Fu-Shun; Yao, Chen-Chen; Wang, Bao-Li

    2011-01-01

    In order to understand the emission of greenhouse gases (CO2) from the river-type reservoir, this study investigated the partial pressure of CO2 [p(CO2)], in the surface water, inflow waters, outflow waters of the Wan'an reservoir in China in the May 2009. p(CO2) in the inflow water, outflow water were calculated from titration method, and the surface water p(CO2) was measured underway using a continuous measurement system (equilibrator-NDIR system). Results showed that the inflow water from the Zhangshui, Meijiang, Taojiang have higher p(CO2) than atmosphere level, with the values of 211.5, 91.7, 259.7 Pa respectively. p(CO2) in the surface water of the incoming section of Wan'an reservoir was between 180-210 Pa, and in the middle section and central section near the dam, p(CO2) in the surface water were about 140-180 Pa and 70-110 Pa. In the outflow waters, p(CO2) reached to 176.2 Pa, higher than that in central section. As a result, it can be concluded that the surface water, inflow waters, outflow waters in the Wan'an reservoir are all the source to CO2. However there is clear evidence showing that the reservoir indeed has a role in mitigating the CO2 emission in this case.

  18. Influences of porous reservoir Laplace pressure on emissions from passively fed ionic liquid electrospray sources

    SciTech Connect

    Courtney, Daniel G. Shea, Herbert

    2015-09-07

    Passively fed ionic liquid electrospray sources are capable of efficiently emitting a variety of ion beams with promising applications to spacecraft propulsion and as focused ion beams. Practical devices will require integrated or coupled ionic liquid reservoirs; the effects of which have not been explored in detail. Porous reservoirs are a simple, scalable solution. However, we have shown that their pore size can dramatically alter the beam composition. Emitting the ionic liquid 1-ethyl-3-methylimidazolium bis(triflouromethylsulfonyl)amide, the same device was shown to yield either an ion or droplet dominated beam when using reservoirs of small or large pore size, respectively; with the latter having a mass flow in excess of 15 times larger than the former at negative polarity. Another source, emitting nearly purely ionic beams of 1-ethyl-3-methylimidazolium tetrafluoroborate, was similarly shown to emit a significant droplet population when coupled to reservoirs of large (>100 μm) pores; constituting a reduction in propulsive efficiency from greater than 70% to less than 30%. Furthermore, we show that reservoir selection can alter the voltage required to obtain and sustain emission, increasing with smaller pore size.

  19. Effect of ambient-pressure reduction on multibubble sonochemiluminescence

    NASA Astrophysics Data System (ADS)

    Tuziuti, Toru; Hatanaka, Shin-ichi; Yasui, Kyuichi; Kozuka, Teruyuki; Mitome, Hideto

    2002-04-01

    The effect of ambient-pressure reduction on multibubble sonochemiluminescence (MBSCL) is studied experimentally with a luminol solution through measurements of MBSCL intensity as a function of ultrasound irradiation time, applied voltage to a transducer and ultrasonic frequencies to accomplish high efficiency in chemical reactions. From the measurement of ambient-pressure dependence, it is shown that there is an ambient pressure that produces the maximum intensity of the MBSCL and the maximum intensity appears at higher ambient pressure as the applied voltage to the transducer increases. The highest intensity of MBSCL is obtained by appropriate reduction of ambient pressure both for various applied voltages and frequencies. This is caused by both the number of bubbles induced with supersaturation of the gas in a luminol solution and the variation in bubble dynamics.

  20. Noise reduction in solid-state lasers using a SHG-based buffer reservoir.

    PubMed

    El Amili, Abdelkrim; Alouini, Mehdi

    2015-04-01

    The cancellation of resonant intensity noise, from a few kHz up to several GHz, is reported using a second-harmonic generation (SHG) buffer reservoir in a Nd:YAG solid-state laser. This approach is shown to be well suited and easily optimizable for reducing the excess noise lying at the laser relaxation oscillations as well as that originating from the beating between the lasing mode and nonlasing adjacent longitudinal modes. A thorough analysis of noise spectra of both laser and SHG signals confirms definitely that noise reduction is a consequence of a deep laser dynamics modification rather than noise evacuation mechanism.

  1. Lava lake level as a gauge of magma reservoir pressure and eruptive hazard

    USGS Publications Warehouse

    Patrick, Matthew R.; Anderson, Kyle R.; Poland, Michael P.; Orr, Tim R.; Swanson, Donald A.

    2015-01-01

    Forecasting volcanic activity relies fundamentally on tracking magma pressure through the use of proxies, such as ground surface deformation and earthquake rates. Lava lakes at open-vent basaltic volcanoes provide a window into the uppermost magma system for gauging reservoir pressure changes more directly. At Kīlauea Volcano (Hawaiʻi, USA) the surface height of the summit lava lake in Halemaʻumaʻu Crater fluctuates with surface deformation over short (hours to days) and long (weeks to months) time scales. This correlation implies that the lake behaves as a simple piezometer of the subsurface magma reservoir. Changes in lava level and summit deformation scale with (and shortly precede) changes in eruption rate from Kīlauea's East Rift Zone, indicating that summit lava level can be used for short-term forecasting of rift zone activity and associated hazards at Kīlauea.

  2. Reduction of digital plantar pressure by debridement and silicone orthosis.

    PubMed

    Slater, R A; Hershkowitz, I; Ramot, Y; Buchs, A; Rapoport, M J

    2006-12-01

    The lesser digits are frequent sites of elevated plantar pressure and ulceration in the diabetic foot. We sought to determine whether debridement of callus and the wearing of a custom molded digital orthosis could significantly reduce digital plantar pressure. Fourteen patients with distal digital callus were studied. For each patient, the toe with the highest plantar pressure was selected. A computerized pressure mat was used to record the plantar pressure before and after debridement with and without a moldable silicone digital orthosis. Mean peak plantar digital pressures before treatment were 2.80+/-0.7 kg/cm2 for the entire group. The digital orthosis alone reduced plantar pressure to a mean of 1.95+/-0.65 kg/cm2 p < 0.05. Treatment by debridement similarly reduced pressure to 1.99+/-0.76 kg/cm2 p < 0.05. The most effective reduction of pressure for all patients, as well as the most statistically significant, occurred when both treatments were given, with mean peak plantar pressure falling to 1.28+/-0.61 kg/cm2 p < 0.01. Debridement and custom molded digital orthoses alleviate distal digital plantar pressure. Since elevated plantar pressure increases the risk of neuropathic ulceration, these treatments should be considered in the prophylactic care of appropriate patients.

  3. Flexible Decision Variables in Short-term Operation of Reservoirs Using Dimension Reduction Approach

    NASA Astrophysics Data System (ADS)

    Hosseini, P.; Chen, D.; Leon, A.; Gibson, N. L.

    2015-12-01

    This paper presents a multi-objective optimization model to find flexible decision variables (e.g., turbine flows) in reservoir operation. Flexible decision variables could give the decision maker a range of options instead of single deterministic optimal solutions. In our formulation, each decision variable is modeled by a random variable, and the eventual decision will be but one realization. The optimal probability distribution is found by maximizing the expected value of the objective. Finding flexible decision variables can be computationally intensive especially for multi-reservoir systems. To increase the computational speed of the optimization, a dimension reduction method is used, namely the Karhunen Loe`ve (KL) expansion. KL expansion is closely related to Principal Component Analysis (PCA) and can be used to efficiently represent the random processes by only a few random variables. When using this method, deterministic optimal Pareto solutions are used as the initial population for the optimization. The Grand Coulee reservoir, located in the Columbia River, is used as the test case. The results show that the decision space can be represented with very few random variables and the computational time can therefore be drastically reduced.

  4. Pressure and fluid saturation prediction in a multicomponent reservoir, using combined seismic and electromagnetic imaging

    SciTech Connect

    Hoversten, G.M.; Gritto, Roland; Washbourne, John; Daley, Tom

    2002-06-10

    This paper presents a method for combining seismic and electromagnetic measurements to predict changes in water saturation, pressure, and CO{sub 2} gas/oil ratio in a reservoir undergoing CO{sub 2} flood. Crosswell seismic and electromagnetic data sets taken before and during CO{sub 2} flooding of an oil reservoir are inverted to produce crosswell images of the change in compressional velocity, shear velocity, and electrical conductivity during a CO{sub 2} injection pilot study. A rock properties model is developed using measured log porosity, fluid saturations, pressure, temperature, bulk density, sonic velocity, and electrical conductivity. The parameters of the rock properties model are found by an L1-norm simplex minimization of predicted and observed differences in compressional velocity and density. A separate minimization, using Archie's law, provides parameters for modeling the relations between water saturation, porosity, and the electrical conductivity. The rock-properties model is used to generate relationships between changes in geophysical parameters and changes in reservoir parameters. Electrical conductivity changes are directly mapped to changes in water saturation; estimated changes in water saturation are used along with the observed changes in shear wave velocity to predict changes in reservoir pressure. The estimation of the spatial extent and amount of CO{sub 2} relies on first removing the effects of the water saturation and pressure changes from the observed compressional velocity changes, producing a residual compressional velocity change. This velocity change is then interpreted in terms of increases in the CO{sub 2}/oil ratio. Resulting images of the CO{sub 2}/oil ratio show CO{sub 2}-rich zones that are well correlated to the location of injection perforations, with the size of these zones also correlating to the amount of injected CO{sub 2}. The images produced by this process are better correlated to the location and amount of injected

  5. Compaction bands in high temperature/pressure diagenetically altered unconventional shale gas reservoirs

    NASA Astrophysics Data System (ADS)

    Regenauer-Lieb, K.; Veveakis, M.; Poulet, T.

    2014-12-01

    Unconventional energy and mineral resources are typically trapped in a low porosity/permeability environment and are difficult to produce. An extreme end-member is the shale gas reservoir in the Cooper Basin (Australia) that is located at 3500-4000 m depth and ambient temperature conditions around 200oC. Shales of lacustrine origin (with high clay content) are diagenetically altered. Diagenesis involves fluid release mineral reactions of the general type Asolid ↔ Bsolid +Cfluid and switches on suddenly in the diagenetic window between 100-200oC. Diagenetic reactions can involve concentrations of smectite, aqueous silica compound, illite, potassium ions, aqueous silica, quartz, feldspar, kerogen, water and gas . In classical petroleum engineering such interlayer water/gas release reactions are considered to cause cementation and significantly reduce porosity and permeability. Yet in contradiction to the expected permeability reduction gas is successfully being produced. We propose that the success is based on the ductile equivalent of classical compaction bands in solid mechanics. The difference being that that the rate of the volumetric compaction is controlled by the diagenetic reactions. Ductile compaction bands are forming high porosity fluid channels rather than low porosity crushed grains in the solid mechanical equivalent. We show that this new type of volumetric instability appears in rate-dependent heterogenous materials as Cnoidal waves. These are nonlinear and exact periodic stationary waves, well known in the shallow water theory of fluid mechanics. Their distance is a direct function of the hydromechanical diffusivities. These instabilities only emerge in low permeability environment where the fluid diffusivity is about an order of magnitude lower than the mechanical loading. The instabilities are expected to be of the type as shown in the image below. The image shows a CT-scan of a laboratory experiment kindly provided by Papamichos (pers

  6. Microbial iron reduction under deep subsurface pressure conditions

    NASA Astrophysics Data System (ADS)

    Picard, A.; Daniel, I.; Testemale, D.; Hazemann, J.; Oger, P.

    2009-12-01

    The deep subsurface is characterized by hostile conditions in terms of temperature, pressure and nutrient availability. Our current view of the biosphere extension is restricted to depths shallower than the isotherm associated to the highest observed temperature for life, i.e. 122°C. At this temperature, depending on the geological setting, pressure varies between ambient pressure at geothermal springs and 350 MPa in cold subduction zones. In this high-pressure biosphere, biological iron reduction is an important process linked to carbon oxidation. Among the factors governing reaction rates and yields in the deep subsurface, pressure could be of importance due its effects on kinetic and equilibrium reactions. The understanding and modelling of Fe reduction in natural environments, especially in the subsurface, can be first comprehended thanks to studies of Fe reduction in pure cultures; indeed the study of the effects of high pressure on Fe-reducing bacteria in pure cultures can serve as a basic model for the effects of pressure on Fe reduction in the subsurface. We investigated the effects of pressure on the reduction of Fe(III) to Fe(II) by the bacterial model Shewanella oneidensis MR-1. This strain is a mesophilic and piezosensitive counterpart of the psychrophilic and piezophilic Shewanella representatives that have been frequently isolated from deep-sea environments. Kinetics of Fe(III) reduction to Fe(II) were monitored in situ by X-ray Absorption Spectroscopy (XAS) in an appropriate pressure vessel dedicated to in situ XAS measurements (Testemale et al. 2005). Measurements were performed at the BM30B beamline of the European Synchrotron Radiation Facilty (Grenoble, France). Experiments were conducted from 0.1 MPa to 100 MPa at MR-1 optimal temperature (30°C). Iron reduction was monitored until 100 MPa in cultures of MR-1 at a concentration of 10e8 cells/ml. This shows that the metabolic activity of a piezosensitive microbe extends far beyond its pressure

  7. Evolution of pore fluid pressures in a stimulated geothermal reservoir inferred from earthquake focal mechanisms

    NASA Astrophysics Data System (ADS)

    Terakawa, T.; Deichmann, N.

    2014-12-01

    We developed an inversion method to estimate the evolution of pore fluid pressure fields from earthquake focal mechanism solutions based on the Bayesian statistical inference and Akaike's Bayesian information criterion (ABIC). This method's application to induced seismicity in the Basel enhanced geothermal system in Switzerland shows the evolution of pore fluid pressures in response to fluid injection experiments. For a few days following the initiation of the fluid injection, overpressurized fluids are concentrated around the borehole and then anisotropically propagate within the reservoir until the bleed-off time. Then, the pore fluid pressure in the vicinity of the borehole drastically decreases, and overpressurized fluids become isolated in a few major fluid pockets. The pore fluid pressure in these pockets gradually decreases with time. The pore fluid pressure in the reservoir is less than the minimum principal stress at each depth, indicating that the hydraulic fracturing did not occur during stimulation. This suggests that seismic events may play an important role to promote the development of permeable channels, particularly southeast of the borehole where the largest seismic event (ML 3.4) occurred. This is not directly related to a drastic decrease in fault strength at the hypocenter, but rather the positive feedback between permeability enhancement and poro-elastic and stress transfer loading from slipping interfaces. These processes likely contribute to this event's nucleation.

  8. Analytical solution of geological carbon sequestration under constant pressure injection into a horizontal radial reservoir

    NASA Astrophysics Data System (ADS)

    Jhang, R.; Liou, T.

    2013-12-01

    Carbon capture and sequestration (CCS) is believed to be an economically feasible technology to mitigate global warming by capturing carbon dioxide (CO2), the major component of greenhouse gases, from the atmosphere and injecting it into deep geological formations.Several mechanisms can help trap CO2 in the pore space of a geological reservoir, stratigraphic and structural trapping, hydrodynamic trapping, and geochemical trapping.Besides these trapping mechanisms, another important issue that deserves careful attention is the risk of CO2 leakage. The common ';constant injection rate' scenario may induce high pressure buildup that will endanger the mechanical integrity as well as the sealing capability of the cap rock. Instead of injecting CO2 at a constant mass rate, CO2 can be injected into the reservoir by fixing the pressure (usually the bottom-hole pressure) in the injection borehole. By doing so, the inevitable pressure buildup associated with the constant injection scheme can be completely eliminated in the constant pressure injection scheme. In this paper, a semi-analytical solution for CO2 injection with constant pressure was developed. For simplicity, structural and geochemical trapping mechanisms were not considered. Therefore, a horizontal reservoir with infinite radial extent was considered. Prior to injection, the reservoir is fully saturated with the formation brine. It is assumed that CO2 does not mix with brine such that a sharp interface is formed once CO2 invades the brine-saturated pores. Because of the density difference between CO2 and brine, CO2 resides above the interface. Additional assumptions were also made when building up the brine and CO2 mass balance equations: (1) both of the fluids and the geological formations are incompressible, (2) capillary pressure is neglected, (3)there is no fluid flow in the vertical direction, and the horizontal flow satisfies the Darcy's law.In order to solve for the height of brine-CO2 interface, the two

  9. A triple-continuum pressure-transient model for a naturallyfractured vuggy reservoir

    SciTech Connect

    Wu, Y-S.; Ehlig-Economides, C.; Qin, Guan; Kang, Zhijang; Zhang,Wangming; Ajayi, Babatunde; Tao, Qingfeng

    2007-08-28

    We present an analytical approach for pressure transienttest analysis in naturally fractured vuggy reservoirs. This analysisapproach relies on a triple-continuum concept, using observed geologicaldata from carbonate oil formations in western China, to describetransient flow behavior in fracture-vug-matrix reservoirs. In theconceptual mathematical model, fractured vuggy rock is considered as atriple-continuum medium, consisting of fractures, rock matrix, and vugs(or cavities). Similar to the classical double-porosity model, thefracture continuum is assumed to be responsible for the occurrence ofglobal flow, while vuggy and matrix continua (providing primary storagespace) interact locally with each other as well as with globallyconnected fractures. Furthermore, the triple continua of fractures,matrix, and vugs are assumed to have uniform and homogeneous propertiesthroughout, and intercontinuum flows between them are at pseudosteadystate. With these assumptions, we derive analytical solutions in Laplacespace for transient flow toward a well in an infinite and finitereservoir with wellbore storage and skin effects. The analyticalsolutions reveal typical pressure responses in a fracture-vug-matrixreservoir and can be used for estimating vug properties, in addition tofracture and matrix parameters, through properly designed and conductedwell tests. As application examples, actual well test data from afractured-vuggy reservoir in Western China are analyzed using the triplecontinuum model.

  10. Use of betaxolol in the reduction of elevated intraocular pressure.

    PubMed

    Radius, R L

    1983-06-01

    Forty eyes in 20 patients with elevated intraocular pressure were treated with either a 0.125% betaxolol ophthalmic solution or a placebo. After 2, 4, and 6 weeks of twice-daily therapy, the eyes receiving the betaxolol had a mean percent reduction in IOP greater than that in the eyes treated only with the drug vehicle (placebo). Both solutions were well tolerated.

  11. Reservoir response to thermal and high-pressure well stimulation efforts at Raft River, Idaho

    SciTech Connect

    Plummer, Mitchell; Bradford, Jacob; Moore, Joseph; Podgorney, Robert

    2016-08-01

    An injection stimulation test begun at the Raft River geothermal reservoir in June, 2013 has produced a wealth of data describing well and reservoir response via high-resolution temperature logging and distributed temperature sensing, seismic monitoring, periodic borehole televiewer logging, periodic stepped flow rate tests and tracer injections before and after stimulation efforts. One of the primary measures of response to the stimulation is the relationship between fluid pressure and flow rate, short-term during forced flow rate changes and the long-term change in injectivity. In this paper we examine that hydraulic response using standard pumping test analysis methods, largely because pressure response to the stimulation was not detected, or measurable, in other wells. Analysis of stepped rate flow tests supports the inference from other data that a large fracture, with a radial extent of one to several meters, intersects the well in the target reservoir, suggests that the flow regime is radial to a distance of only several meters and demonstrates that the pressure build-up cone reaches an effective constant head at that distance. The well’s longer term hydraulic response demonstrated continually increasing injectivity but at a dramatically faster rate later from ~2 years out and continuing to the present. The net change in injectivity is significantly greater than observed in other longterm injectivity monitoring studies, with an approximately 150–fold increase occurring over ~2.5 years. While gradually increasing injectivity is a likely consequence of slow migration of a cooling front, and consequent dilation of fractures, the steady, ongoing, rate of increase is contrary to what would be expected in a radial or linear flow regime, where the cooling front would slow with time. As a result, occasional step-like changes in injectivity, immediately following high-flow rate tests suggest that hydro shearing during high-pressure testing altered the near

  12. Modeling Responses of Naturally Fractured Geothermal Reservoir to Low-Pressure Stimulation

    DOE Data Explorer

    Fu, Pengcheng; Carrigan, Charles R.

    2012-01-01

    Hydraulic shearing is an appealing reservoir stimulation strategy for Enhanced Geothermal Systems. It is believed that hydro-shearing is likely to simulate a fracture network that covers a relatively large volume of the reservoir whereas hydro-fracturing tends to create a small number of fractures. In this paper, we examine the geomechanical and hydraulic behaviors of natural fracture systems subjected to hydro-shearing stimulation and develop a coupled numerical model within the framework of discrete fracture network modeling. We found that in the low pressure hydro-shearing regime, the coupling between the fluid phase and the rock solid phase is relatively simple, and the numerical model is computationally efficient. Using this modified model, we study the behavior of a random fracture network subjected to hydro-shearing stimulation.

  13. Practical application of fractal pressure-transient analysis in naturally fractured reservoirs

    SciTech Connect

    Acuna, J.A.; Ershaghi, I.; Yortsos, Y.C.

    1995-09-01

    Pressure-transient tests in naturally fractured reservoirs often exhibit nonuniform responses. Various models explain such nonuniformity; however, their relevance is often not justified on a geologic basis. Fractal geometry provides a method to account for a great variety of such transients under the assumption that the network of fractures is fractal. This paper presents an application to real well test in various fractured reservoirs. The physical meaning of the fractal parameters is presented in the context of well testing. Examples showing a behavior similar to the finite-conductivity fracture model or the spherical flow are presented and explained by the alternative of fractal networks. A behavior that can be mistakenly interpreted as a double-porosity case is also analyzed.

  14. Vapor pressure lowering effects due to salinity and suction pressure in the depletion of vapor-dominated geothermal reservoirs

    SciTech Connect

    Battistelli, A.; Calore, C.; Pruess, K.

    1995-03-01

    The equation-of-state module able to handle saline brines with non-condensible gas, developed for the TOUGH2 simulator, has been improved to include vapor pressure lowering (VPL) due to suction pressure as represented by Kelvin`s equation. In this equation the effects of salt are considered whereas those of non-condensible gas have currently been neglected. Numerical simulations of fluid production from tight matrix blocks have been performed to evaluate the impact of VPL effects due to salinity and suction pressure on the depletion behaviour of vapor-dominated geothermal reservoirs. Previous studies performed neglected VPL due to suction pressure showed that for initial NaCl mass fractions above threshold values, {open_quotes}sealing{close_quotes} of the block occurs and large amounts of liquid fluid may not be recovered. On the other hand, below the threshold value the matrix block dries out due to fluid production. The inclusion of VPL due to suction pressure does not allow complete vaporization of the liquid phase. As a result, the threshold NaCl concentration above which sealing of the matrix block occurs is increased. Above the {open_quotes}critical{close_quotes} NaCl concentration, block depletion behaviour with and without the VPL due to suction pressure is almost identical, as liquid phase saturation remains high even after long production times. As the VPL due to suction pressure depends mainly on capillary pressure, the shape of capillary pressure functions used in numerical simulations is important in determining VPL effects on block depletion.

  15. Neutron flux reduction programs for reactor pressure vessel

    SciTech Connect

    Yoo, C.S.; Kim, B.C.

    2011-07-01

    The objective of this work is to implement various fast neutron flux reduction programs on the belt-line region of the reactor pressure vessel to reduce the increasing rate of reference temperature for pressurized thermal shock (RT PTS) for Korea Nuclear Unit 1. A pressurized thermal shock (PTS) event is an event or transient in pressurized water reactors (PWRs) causing severe overcooling (thermal shock) concurrent with or followed by significant pressure in the reactor vessel. A PTS concern arises if one of these transients acts in the belt-line region of a reactor vessel where a reduced fracture resistance exists because of neutron irradiation. Generally, the RT PTS value is continuously increasing according to the fast neutron irradiation during the reactor operation, and it can reach the screening criterion prior to the expiration of the operating license. To reduce the increasing rate of RT PTS, various neutron flux reduction programs can be implemented, which are focused on license renewal. In this paper, neutron flux reduction programs, such as low leakage loading pattern strategy, loading of neutron absorber rods, and dummy fuel assembly loading are considered for Korea Nuclear Unit 1, of which the RT PTS value of the leading material (circumferential weld) is going to reach the screening criterion in the near future. To evaluate the effects of the neutron flux reduction programs, plant and cycle specific forward neutron transport calculations for the various neutron flux reduction programs were carried out. For the analysis, all transport calculations were carried out by using the DORT 3.1 discrete ordinate code and BUGLE-96 cross-section library. (authors)

  16. CONCEPTUAL MODEL FOR ORIGIN OF ABNORMALLY PRESSURED GAS ACCUMULATIONS IN LOW-PERMEABILITY RESERVOIRS.

    USGS Publications Warehouse

    Law, B.E.; Dickinson, W.W.

    1985-01-01

    The paper suggests that overpressured and underpressured gas accumulations of this type have a common origin. In basins containing overpressured gas accumulations, rates of thermogenic gas accumulation exceed gas loss, causing fluid (gas) pressure to rise above the regional hydrostatic pressure. Free water in the larger pores is forced out of the gas generation zone into overlying and updip, normally pressured, water-bearing rocks. While other diagenetic processes continue, a pore network with very low permeability develops. As a result, gas accumulates in these low-permeability reservoirs at rates higher than it is lost. In basins containing underpressured gas accumulations, rates of gas generation and accumulation are less than gas loss. The basin-center gas accumulation persists, but because of changes in the basin dynamics, the overpressured accumulation evolves into an underpressured system.

  17. Reservoir Modeling for Production Management

    SciTech Connect

    Brown, Donald W.

    1989-03-21

    For both petroleum and geothermal resources, many of the reservoirs are fracture dominated--rather than matrix-permeability controlled. For such reservoirs, a knowledge of the pressure-dependent permeability of the interconnected system of natural joints (i.e., pre-existing fractures) is critical to the efficient exploitation of the resource through proper pressure management. Our experience and that reported by others indicates that a reduction in the reservoir pressure sometimes leads to an overall reduction in production rate due to the ''pinching off'' of the joint network, rather than the anticipated increase in production rate. This effect occurs not just in the vicinity of the wellbore, where proppants are sometimes employed, but throughout much of the reservoir region. This follows from the fact that under certain circumstances, the decline in fracture permeability (or conductivity) with decreasing reservoir pressure exceeds the far-field reservoir ''drainage'' flow rate increase due to the increased pressure gradient. Further, a knowledge of the pressure-dependent joint permeability could aid in designing more appropriate secondary recovery strategies in petroleum reservoirs or reinjection procedures for geothermal reservoirs.

  18. High Pressure Reduction of Selenite by Shewanella oneidensis MR-1

    NASA Astrophysics Data System (ADS)

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

    2007-12-01

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

  19. Reduction of CO2 using a Rhenium Bipyridine Complex Containing Ancillary BODIPY Redox Reservoirs

    SciTech Connect

    Teesdale, Justin; Pistner, Allen; Yapp, Glenn P. A.; Ma, Yingzhong; Lutterman, Daniel A; Rosenthal, Joel

    2014-01-01

    The reduction of carbon dioxide to chemical fuels such as carbon monoxide is an important challenge in the field of renewable energy conversion. Given the thermodynamic stability of carbon dioxide, it is difficult to efficiently activate this substrate in a selective fashion and the development of new electrocatalysts for CO2 reduction is of prime importance. To this end, we have prepared and studied a new fac-ReI(CO)3 complex supported by a bipyridine ligand containing ancillary BODIPY moieties ([Re(BB2)(CO)3Cl]). Voltammetry experiments revealed that this system displays a rich redox chemistry under N2, as [Re(BB2)(CO)3Cl] can be reduced by up to four electrons at modest potentials. These redox events have been characterized as the ReI/0 couple, and three ligand based reductions two of which are localized on the BODIPY units. The ability of the BB2 ligand to serve as a noninnocent redox reservoir is manifest in an enhanced electrocatalysis with CO2 as compared to an unsubstituted Re-bipyridine complex lacking BODIPY units ([Re(bpy)(CO)3Cl]). The second order rate constant for reduction of CO2 by [Re(BB2)(CO)3Cl] was measured to be k = 3400 M 1s 1 at an applied potential of 2.0 V versus SCE, which is roughly three times greater than the corresponding unsubstituted Re-bipyridine homologue. Photophysical and photochemical studies were also carried out to determine if [Re(BB2)(CO)3Cl] was a competent platform for CO2 reduction using visible light. These experiments showed that this complex supports unusual excited state dynamics that are not typically observed for fac- ReI(CO)3 complexes.

  20. Designing cyclic pressure pulsing in naturally fractured reservoirs using an inverse looking recurrent neural network

    NASA Astrophysics Data System (ADS)

    Artun, E.; Ertekin, T.; Watson, R.; Miller, B.

    2012-01-01

    In this paper, an inverse looking approach is presented to efficiently design cyclic pressure pulsing (huff 'n' puff) with N 2 and CO 2, which is an effective improved oil recovery method in naturally fractured reservoirs. A numerical flow simulation model with compositional, dual-porosity formulation is constructed. The model characteristics are from the Big Andy Field, which is a depleted, naturally fractured oil reservoir in Kentucky. A set of cyclic pulsing design scenarios is created and run using this model. These scenarios and corresponding performance indicators are fed into the recurrent neural network for training. In order to capture the cyclic, time-dependent behavior of the process, recurrent neural networks are used to develop proxy models that can mimic the reservoir simulation model in an inverse looking manner. Two separate inverse looking proxy models for N 2 and CO 2 injections are constructed to predict the corresponding design scenarios, given a set of desired performance characteristics. Predictive capabilities of developed proxy models are evaluated by comparing simulation outputs with neural-network outputs. It is observed that networks are able to accurately predict the design parameters, such as the injection rate and the duration of injection, soaking and production periods.

  1. Diesel engine emissions reduction by multiple injections having increasing pressure

    DOEpatents

    Reitz, Rolf D.; Thiel, Matthew P.

    2003-01-01

    Multiple fuel charges are injected into a diesel engine combustion chamber during a combustion cycle, and each charge after the first has successively greater injection pressure (a higher injection rate) than the prior charge. This injection scheme results in reduced emissions, particularly particulate emissions, and can be implemented by modifying existing injection system hardware. Further enhancements in emissions reduction and engine performance can be obtained by using known measures in conjunction with the invention, such as Exhaust Gas Recirculation (EGR).

  2. Seismically induced pressure transients at geothermal reservoirs in the eastern Marmara region

    NASA Astrophysics Data System (ADS)

    Woith, Heiko; Wang, Rongjiang; Caka, Deniz; Irmak, T. Serkan; Tunc, Berna; Luehr, Birger-G.; Baris, Serif

    2014-05-01

    The potential role of fluids in processes related to the triggering of earthquakes and volcanic eruptions is frequently emphasized. Here, we focus on the response of hydrogeological systems to earthquakes, specifically on seismically induced pore-pressure variations in geothermal areas located in the eastern Marmara region. At a 500 m deep artesian geothermal well the pressure is continuously being monitored at a sampling rate of 100 Hz. A seismometer is co-located close to the well-head and the data are recorded by the same digitizer. Hydro-seismograms were recorded in relation to local and distant earthquakes. The ML=5.2 Manyas earthquake which occurred on 20 October 2006 at a distance of 77 km led to a dynamic response of the pore pressure of the order of 4 mbar triggered upon the arrival of the S-wave. Four days later, the ML=5.2 Gemlik earthquake at a distance of 20 km led to a dynamic pore pressure response of the order of 15 mbar triggered upon the arrival of the P-wave. In both cases the peak amplitude of the ground velocity was about 2 mm/s. Weak oscillations of the pore pressure were observed during the passage of surface waves generated by remote earthquakes at distances of up to 9,000 km. Additionally to the dynamic response, a small persistent pressure increase of 1 and 2 mbar had been recorded after both local earthquakes. According to preliminary results, the observed pressure increase is opposite to the static pressure decrease predicted by Okada's model. At the present stage we conclude that the response of the Armutlu geothermal system to earthquakes is likely caused by a dynamic interaction of passing seismic waves (P-, S-, and surface waves) with the fluid reservoir in case a threshold of the ground shaking is exceeded.

  3. Effect of Thermophilic Nitrate Reduction on Sulfide Production in High Temperature Oil Reservoir Samples.

    PubMed

    Okpala, Gloria N; Chen, Chuan; Fida, Tekle; Voordouw, Gerrit

    2017-01-01

    Oil fields can experience souring, the reduction of sulfate to sulfide by sulfate-reducing microorganisms. At the Terra Nova oil field near Canada's east coast, with a reservoir temperature of 95°C, souring was indicated by increased hydrogen sulfide in produced waters (PW). Microbial community analysis by 16S rRNA gene sequencing showed the hyperthermophilic sulfate-reducing archaeon Archaeoglobus in Terra Nova PWs. Growth enrichments in sulfate-containing media at 55-70°C with lactate or volatile fatty acids yielded the thermophilic sulfate-reducing bacterium (SRB) Desulfotomaculum. Enrichments at 30-45°C in nitrate-containing media indicated the presence of mesophilic nitrate-reducing bacteria (NRB), which reduce nitrate without accumulation of nitrite, likely to N2. Thermophilic NRB (tNRB) of the genera Marinobacter and Geobacillus were detected and isolated at 30-50°C and 40-65°C, respectively, and only reduced nitrate to nitrite. Added nitrite strongly inhibited the isolated thermophilic SRB (tSRB) and tNRB and SRB could not be maintained in co-culture. Inhibition of tSRB by nitrate in batch and continuous cultures required inoculation with tNRB. The results suggest that nitrate injected into Terra Nova is reduced to N2 at temperatures up to 45°C but to nitrite only in zones from 45 to 65°C. Since the hotter zones of the reservoir (65-80°C) are inhabited by thermophilic and hyperthermophilic sulfate reducers, souring at these temperatures might be prevented by nitrite production if nitrate-reducing zones of the system could be maintained at 45-65°C.

  4. Nitric oxide production and blood pressure reduction during haemodialysis.

    PubMed

    Chang, Chiz-Tzung; Chien, Ming-Hui; Yang, Kai-Liang; Yu, Chien-Chih; Hsu, Jing-Fang; Wang, I-Kuan; Lim, Paik-Seong; Huang, Chiu-Ching

    2014-09-01

    A decrease of systolic blood pressure in excess of 20 mmHg during haemodialysis treatment (IDD) is common for haemodialysis patients. Intradialytic hypotension (IDH) is symptomatic IDD by definition. Overproduction of nitric oxide (NO) is a possible cause of IDD. Dialysate nitrate and nitrite amount can be used as an indicator of intradialysis NO production. Our aim was to find the predictor of NO production in IDD patients. Partial dialysate samples were collected during the whole haemodialysis session and total dialysate nitrate and nitrite amount was measured to assess the association of intradialysis NO production with blood pressure change. There were 31 IDD patients and 71 patients who did not develop IDD (NIDD) included in the study. Among the IDD patients, 13 were IDH patients with a mean systolic blood pressure lower than that of the other 18 symptomless IDD patients (96.6 ± 3.4 mmHg vs 125.0 ± 3.8 mmHg, P<0.001). The median value of NO production was higher in the IDD than in the NIDD patients (447.7 μg vs 238.8 μg, P<0.001). The NO production correlated linearly with blood pressure reduction (R=0.487, P<0.001). The multivariate analysis showed that NO production was positively associated with predialysis systolic blood pressure. Nitric oxide production during haemodialysis was higher in IDD than in NIDD patients. IDH often occurred when systolic blood pressure was reduced to below 100 mmHg. The amount of NO produced during haemodialysis, which may be associated with predialysis systolic blood pressure, can be used to predict intradialysis blood pressure decrease. © 2014 Asian Pacific Society of Nephrology.

  5. Ab initio molecular dynamics with a classical pressure reservoir: simulation of pressure-induced amorphization in a Si35H36 cluster

    PubMed

    Martonak; Molteni; Parrinello

    2000-01-24

    We present a new constant-pressure ab initio molecular dynamics method suitable for studying, e.g., pressure-induced structural transformations in finite nonperiodic systems such as clusters. We immerse an ab initio treated cluster into a model classical liquid, described by a soft-sphere potential, which acts as a pressure reservoir. The pressure is varied by tuning the parameter of the liquid potential. We apply the method to a Si35H36 cluster, which undergoes a pressure-induced amorphization at approximately 35 GPa, and remains in a disordered state even upon pressure release.

  6. Hornblende phenocrysts record a pressure gradient in and contamination of the Taylor Creek Rhyolite magma reservoir

    SciTech Connect

    Jones, C.; Wittke, J. ); Duffield, W. ); Davis, A. )

    1993-04-01

    The Taylor Creek Rhyolite of southwestern New Mexico comprises 20 coeval porphyritic lava domes erupted from a large vertically zoned reservoir of silicic magma. The rhyolite is high-silica, subalkaline, and is nearly constant in major-element composition. Trace elements and [sup 87]Sr/[sup 86]Sr[sub i] (0.705 to 0.713) define vertical zoning that records a downward-decreasing imprint of minor (<1 wt%) partial assimilation of Proterozoic roof rocks. Consistent with the major-element homogeneity, electron-microprobe analyses of hornblende phenocrysts show little or no measurable variation in principal constituents. The hornblende is edenite whose mean composition and standard deviation of 110 analyses are SiO[sub 2], 44.66 [+-] 0.64; TiO[sub g], 1.27 [+-] 0.13; Al[sub 2]O[sub 3], 6.80 [+-] 0.31; FeO, 21.00 [+-] 1.60; MnO, 1.19 [+-] 0.16; MgO, 9.94 [+-] 1.09; CaO, 10.51 [+-] 0.22; Na[sub 2]O, 2.22 [+-] 0.13; K[sup 2]O, 0.98 [+-] 0.08; F, 2.04 [+-] 0.35; Cl, 0.20 [+-] 0.03. Except for FeO, MnO, and MgO, compositional variations are non systematic and mostly within analytical uncertainty. FeO and Mno exhibit strong negative correlation with MgO. Individual hornblende crystals are zoned to relatively MgO-rich and FeO-MnO-poor rims, opposite what might be expected if the Taylor Creek Rhyolite magma reservoir evolved chemically isolated from its surroundings. Hornblende with rims richest in MgO occurs in domes fed from the uppermost part of the reservoir. Calculated pressures based on Al in hornblende range from 1.6 to 2.0 kb, [+-] 0.5 kb. Though the range of calculated P is encompassed within the uncertainty, the lowest hornblende pressure is for a dome fed from, or near, the top of the reservoir, whereas the chemically defined vertical zoning.

  7. Pressure transient behavior of dilatant non-Newtonian/Newtonian fluid composite reservoirs

    SciTech Connect

    Okpobiri, G.A.; Ikoku, C.U.

    1983-11-01

    This study investigates pressure falloff testing in non-Newtonian/Newtonian fluid composite reservoirs. The non-Newtonian fluids of interest exhibit dilatant behavior. Initial water saturation is accounted for. Application of non-Newtonian well test analysis techniques and conventional Horner (Newtonian) techniques is investigated. The effects of different injection times before shut-in, external radii, flow behavior indexes and non-Newtonian fluid consistencies on the pressure transient behavior constitute the salient features of this work. It is shown that early time falloff pressure data can be analyzed by non-Newtonian techniques while the late shut-in data, under certain conditions, can be analyzed by the conventional Horner method. The time when the Newtonian fluid starts influencing the non-Newtonian falloff curves and the location of the non-Newtonian fluid front can be estimated by using the radius of investigation equation for power-law fluids and volumetric balance equation respectively. Rheological consideration is made to illustrate the pressure transient behavior.

  8. A method for determining transverse permeability of tight reservoir cores by radial pressure pulse decay measurement

    NASA Astrophysics Data System (ADS)

    Yang, Zehao; Dong, Mingzhe; Zhang, Shaojie; Gong, Houjian; Li, Yajun; Long, Feifei

    2016-10-01

    A transverse pressure pulse decay (TPPD) method is presented to measure transverse permeability of tight reservoir cores in a cell with finite volume. Given appropriate assumptions, a mathematical model based on the specially designed experiment is formulated, and its general solution is proposed. Early-time and late-time techniques are further presented for convenient postprocessing applications of experimental data. Meanwhile, sensitivity analysis of TPPD method is given. It is found that a good TPPD experimental principle can be obtained by adjusting test gas, experimental pressure, dimension of core sample, and volume ratio (λ). The volume ratio error (λerror) analysis reveals the following: (1) a larger λerror results in increased transverse permeability error (kerror); (2) the volume ratio (λ) is better not very close to 0.754; (3) when λ is equal to or greater than 1, the kerror resulting from λerror is monotonic decreasing as the volume ratio increases. In practice, λ is usually equal to or greater than 1 due to the very small pore volume of a tight core. But this does not mean that the volume ratio should be as large as possible. The reason for this is that a pressure transducer with higher resolution is needed to record pressure change. That means experimental apparatus is much more costly. And such a TPPD experiment requires a much longer time to attain the late-time straight line behavior. The best choice is to find an optimal balance point among experimental cost, time, and accuracy.

  9. Evaluation of membrane oxygenators and reservoirs in terms of capturing gaseous microemboli and pressure drops.

    PubMed

    Guan, Yulong; Palanzo, David; Kunselman, Allen; Undar, Akif

    2009-11-01

    An increasing amount of evidence points to cerebral embolization during cardiopulmonary bypass (CPB) as the principal etiologic factor of neurologic complications. In this study, the capability of capturing and classification of gaseous emboli and pressure drop of three different membrane oxygenators (Sorin Apex, Terumo Capiox SX25, Maquet QUADROX) were measured in a simulated adult model of CPB using a novel ultrasound detection and classification quantifier system. The circuit was primed with 1000 mL heparinized human packed red blood cells and 1000 mL lactated Ringer's solution (total volume 2000 mL, corrected hematocrit 26-28%). After the injection of 5 mL air into the venous line, an Emboli Detection and Classification Quantifier was used to simultaneously record microemboli counts at post-pump, post-oxygenator, and post-arterial filter sites. Trials were conducted at normothermic (35 degrees C) and hypothermic (25 degrees C) conditions. Pre-oxygenator and post-oxygenator pressure were recorded in real time and pressure drop was calculated. Maquet QUADROX membrane oxygenator has the lowest pressure drops compared to the other two oxygenators (P < 0.001). The comparison among the three oxygenators indicated better capability of capturing gaseous emboli with the Maquet QUADROX and Terumo Capiox SX25 membrane oxygenator and more emboli may pass through the Sorin Apex membrane oxygenator. Microemboli counts uniformly increased with hypothermic perfusion (25 degrees C). Different types of oxygenators and reservoirs have different capability of capturing gaseous emboli and transmembrane pressure drop. Based on this investigation, Maquet QUADROX membrane oxygenator has the lowest pressure drop and better capability for capturing gaseous microemboli.

  10. Prostaglandin Pathway Gene Therapy for Sustained Reduction of Intraocular Pressure

    PubMed Central

    Barraza, Román A; McLaren, Jay W; Poeschla, Eric M

    2009-01-01

    Cyclooxygenase-2 (COX-2) is a rate-limiting enzyme in prostaglandin (PG) biosynthesis. In the eye, loss of COX-2 expression in aqueous humor–secreting cells has been associated with primary open-angle glaucoma (POAG). Reduction of intraocular pressure (IOP) is the main treatment goal in this disease. We used lentiviral vectors to stably express COX-2 and other PG biosynthesis and response transgenes in the ciliary body epithelium and trabecular meshwork (TM), the ocular suborgans that produce aqueous humor and regulate its outflow, respectively. We show that robust ectopic COX-2 expression and PG production require COX-2 complementary DNA (cDNA) sequence optimization. When COX-2 expression was coupled with a similarly optimized synthetic PGF2α receptor transgene to enable downstream signaling, gene therapy produced substantial and sustained reductions in IOP in a large animal model, the domestic cat. This study provides the first gene therapy for correcting the main cause of glaucoma. PMID:19953083

  11. Fissure-Block Model for Transient Pressure Analysis in Geothermal Steam Reservoirs

    SciTech Connect

    Moench, A.F.; Denlinger, R.

    1980-12-16

    At an earlier Stanford workshop, Moench (1978) presented a nonisothermal, radial flow, fissure-block, finite-difference model for geothermal steam reservoirs which was later used to simulate pressure buildup data for a steam well in Larderello, Italy (Moench and Neri, 1979). The model assumed the blocks to be impermeable but capable of conducting heat to the fissures which had been cooled by vaporization. In the present paper the model is revised to account for steam transport and vaporization within the blocks. This is a necessary consideration in order to accouht f o r the longevity of production wells i n The Geysers. The blocks, which may be i n i t i a l l y saturated w i t h l i q u i d water, are assumed t o have low i n t r i n s i c permeability and low p o r o s i t y relative to the fissures. Results computed with this finite-difference model are compared, for isothermal conditions, with the solutions of Boulton and Streltsova (1977). Under these conditions the model is similar to that of Kazemi (1969). When vaporization occurs in the blocks from a small amount of uniformly-distributed liquid water it is also possible to apply Boulton and Streltsova's solutions. This i s done by allowing for the apparent compressibility of the two-phase fluid mixture in the block. Comparison with Boulton and Streltsova's solutions under two-phase conditions is given in order to verify the finite-difference code. Numerical results are also presented showing pressure buildup following production with the blocks initially nearly saturated with liquid water. Effects of different thermal boundary conditions, block sizes and production times on pressure buildup curves are examined. After further refinements the model will be calibrated, using available pressure buildup data from representative wells in The Geysers, and used to provide a means for estimating pore pressure and temperature gradients within reservoir blocks. This information will be used to calculate changes in

  12. The TRINITY Study: distribution of systolic blood pressure reductions

    PubMed Central

    Sugimoto, Danny H; Chrysant, Steven G; Melino, Michael; Lee, James; Fernandez, Victor; Heyrman, Reinilde

    2013-01-01

    Background Elevated systolic blood pressure is more difficult to control than elevated diastolic blood pressure. The objective of this prespecified analysis of the Triple Therapy with Olmesartan Medoxomil, Amlodipine, and Hydrochlorothiazide in Hypertensive Patients Study (TRINITY) was to compare the efficacy of olmesartan medoxomil (OM) 40 mg, amlodipine besylate (AML) 10 mg, and hydrochlorothiazide (HCTZ) 25 mg triple-combination treatment with the component dual-combination treatments in reducing elevated seated systolic blood pressure (SeSBP). Methods The 12-week TRINITY study randomized participants to either one of the three component dual-combination treatments (OM 40 mg/AML 10 mg, OM 40 mg/HCTZ 25 mg, or AML 10 mg/HCTZ 25 mg) or the triple-combination treatment. The primary outcome of this analysis was the categorical distribution of SeSBP reductions at week 12 from baseline with OM 40 mg/AML 10 mg/HCTZ 25 mg versus the dual-combination treatments. Results SeSBP reductions >50 mmHg were seen in 24.4% of participants receiving triple-combination treatment versus 8.1%–15.8% receiving dual-combination treatment. More participants receiving triple-combination treatment achieved the SeSBP target of <140 mmHg (73.6% versus 51.3%–58.8%; P < 0.001) and the seated blood pressure target of <140/90 mmHg (69.9% versus 41.1%–53.4%; P < 0.001). Prevalence and severity of adverse events were similar in all treatment groups. Conclusion Treatment with OM 40 mg/AML 10 mg/HCTZ 25 mg was well tolerated and more effective in reducing SeSBP than the dual-combination treatments. PMID:23901293

  13. The Supraglottic Effect of a Reduction in Expiratory Mask Pressure During Continuous Positive Airway Pressure

    PubMed Central

    Masdeu, Maria J.; Patel, Amit V.; Seelall, Vijay; Rapoport, David M.; Ayappa, Indu

    2012-01-01

    supraglottic effect of a reduction in expiratory mask pressure during continuous positive airway pressure. SLEEP 2012;35(2):263-272. PMID:22294817

  14. Ambient pressure oxygen reservoir apparatus for use during one-lung anaesthesia.

    PubMed

    Pfitzner, J; Peacock, M J; Daniels, B W

    1999-05-01

    An ambient pressure oxygen reservoir bag apparatus for connecting to the nonventilated lung as soon as single-lung ventilation is initiated is described. The theoretical benefits are the facilitation of collapse of the lung on the side of surgery and a reduced likelihood of arterial desaturation. Although these main benefits are yet to be proven, the authors believe that the weight of theoretical argument and practical observation serves to justify the use of the apparatus while the outcome of suitably designed clinical trials is awaited. It can be used for all one-lung anaesthetics and is especially recommended for thoracoscopic surgery, where temporary re-expansion of the nonventilated lung is either counter-productive or contraindicated, and where there is a possibility that lung collapse may be delayed.

  15. Blood pressure reduction following accumulated physical activity in prehypertensive

    PubMed Central

    Saxena, Yogesh; Gupta, Rani; Moinuddin, Arsalan; Narwal, Ravinder

    2016-01-01

    Context: Accumulated moderate physical activity (PA) for 30 min in a day is the only recommended treatment of prehypertension. Objective: We investigated autonomic modulation as a possible mechanism for the decrease in blood pressure (BP) during the rest periods in each 10 min session of PA. Design, Setting, and Participants: We conducted a single-blind randomized multi-arm control trial on 40 prehypertensive (pre-HT) young male adults. Methods: Participants were randomly divided by using random number table into four groups. Control (no intervention); Group 1 (walking at 50% of predicted VO2 peak); Group 2 (walking at 60% of predicted VO2 peak); Group 3 (walking at 70% of predicted VO2 peak). BP, heart rate variability (HRV), and heart rate recovery 1 min (HRR 1 min) were measured at baseline and during the rest period after each session of 10 min over 30 min of accumulated physical activity (PAcumm). Results: Significant diastolic BP (DBP) reduction (P < 0.001) was observed during the rest period after each session of PAcumm in intervention groups. An average reduction in DBP was more in pre-HT undertaking PAcumm at 70% of predicted VO2 Peak. Decrease in the mean value of low-frequency (LF) and LF/high-frequency ratio was observed following PAcumm in all intervention groups irrespective of the intensity of PA. No significant association of reduction of BP with HRV and HRR 1 s was observed. Conclusion: Reduction in BP was observed during the rest period after each 10 min session of PAcumm irrespective of the intensity of PA. Autonomic modulation does not seem to be the possible mechanism for the reduction in BP during the sessions. PMID:27843840

  16. Simulating the gas hydrate production test at Mallik using the pilot scale pressure reservoir LARS

    NASA Astrophysics Data System (ADS)

    Heeschen, Katja; Spangenberg, Erik; Schicks, Judith M.; Priegnitz, Mike; Giese, Ronny; Luzi-Helbing, Manja

    2014-05-01

    LARS, the LArge Reservoir Simulator, allows for one of the few pilot scale simulations of gas hydrate formation and dissociation under controlled conditions with a high resolution sensor network to enable the detection of spatial variations. It was designed and built within the German project SUGAR (submarine gas hydrate reservoirs) for sediment samples with a diameter of 0.45 m and a length of 1.3 m. During the project, LARS already served for a number of experiments simulating the production of gas from hydrate-bearing sediments using thermal stimulation and/or depressurization. The latest test simulated the methane production test from gas hydrate-bearing sediments at the Mallik test site, Canada, in 2008 (Uddin et al., 2011). Thus, the starting conditions of 11.5 MPa and 11°C and environmental parameters were set to fit the Mallik test site. The experimental gas hydrate saturation of 90% of the total pore volume (70 l) was slightly higher than volumes found in gas hydrate-bearing formations in the field (70 - 80%). However, the resulting permeability of a few millidarcy was comparable. The depressurization driven gas production at Mallik was conducted in three steps at 7.0 MPa - 5.0 MPa - 4.2 MPa all of which were used in the laboratory experiments. In the lab the pressure was controlled using a back pressure regulator while the confining pressure was stable. All but one of the 12 temperature sensors showed a rapid decrease in temperature throughout the sediment sample, which accompanied the pressure changes as a result of gas hydrate dissociation. During step 1 and 2 they continued up to the point where gas hydrate stability was regained. The pressure decreases and gas hydrate dissociation led to highly variable two phase fluid flow throughout the duration of the simulated production test. The flow rates were measured continuously (gas) and discontinuously (liquid), respectively. Next to being discussed here, both rates were used to verify a model of gas

  17. Using Fully Coupled Hydro-Geomechanical Numerical Test Bed to Study Reservoir Stimulation with Low Hydraulic Pressure

    DOE Data Explorer

    Fu, Pengcheng; Johnson, Scott M.; Carrigan, Charles R.

    2012-01-31

    This paper documents our effort to use a fully coupled hydro-geomechanical numerical test bed to study using low hydraulic pressure to stimulate geothermal reservoirs with existing fracture network. In this low pressure stimulation strategy, fluid pressure is lower than the minimum in situ compressive stress, so the fractures are not completely open but permeability improvement can be achieved through shear dilation. We found that in this low pressure regime, the coupling between the fluid phase and the rock solid phase becomes very simple, and the numerical model can achieve a low computational cost. Using this modified model, we study the behavior of a single fracture and a random fracture network.

  18. Thermodynamic Constraints on Sulfate Reduction and Methanogenesis in a Coalbed Methane Reservoir

    NASA Astrophysics Data System (ADS)

    Kirk, M. F.; Marquart, K. A.; Wilson, B. H.; Flynn, T. M.; Vinson, D. S.

    2014-12-01

    In this study we consider how commercial natural gas production could affect sulfate reduction and methanogenesis in coal-bearing sediments of the Cherokee Basin, Kansas, USA. Controls on the activity of these two groups of microbes are important to understand because their activity and interactions may influence methane formation and retention in unconventional reservoirs. During November 2013, we collected water and gas samples from 16 commercial gas wells for geochemical and microbiological analysis. Results indicate that methane in the coalbeds formed biologically and that both methanogens and sulfate reducers are present. Gas samples consisted almost entirely of methane (C1/(C2+C3) = 2638 on avg.) and the δD and δ13C of methane averaged -222‰ VSMOW and -61‰ VPDB, respectively. Archaeal sequences in our samples were nearly all classified within groups of methanogens (avg. 91%) and cultivable methanogens were present in all water samples. On average, 6% of the bacterial sequences from our samples were classified in groups of sulfate reducers and sulfate available to support their activity ranged up to 110 μM in concentration. Any interaction that occurs between these groups may be influenced by the energetics of their metabolic reactions. Thermodynamic calculations show that methanogens hold an energy advantage over sulfate reducers if dissolved methane concentrations are low. Under current conditions, methanogens see between 12 and 16 kJ mol-1 more usable free energy than sulfate reducers, if we assume a minimal methane concentration (1 μM). However, usable energy for methanogens would equal that available to sulfate reducers at methane concentrations ranging between 144 and 831 μM, well below saturation levels. Production activities that hold methane concentration below these levels, therefore, would help maintain an energy advantage for methanogens. In contrast, if production activities cause sulfate concentrations to increase, sulfate reducers would

  19. Active CO2 Reservoir Management: A Strategy for Controlling Pressure, CO2 and Brine Migration in Saline-Formation CCS

    NASA Astrophysics Data System (ADS)

    Buscheck, T. A.; Sun, Y.; Hao, Y.; Court, B.; Celia, M. A.; Wolery, T.; Tompson, A. F.; Aines, R. D.; Friedmann, J.

    2010-12-01

    CO2 capture and sequestration (CCS) in deep geological formations is regarded as a promising means of lowering the amount of CO2 emitted to the atmosphere and thereby mitigate global warming. The most promising systems for CCS are depleted oil reservoirs, particularly those suited to CO2-based Enhanced Oil Recovery (CCS-EOR), and deep saline formations, both of which are well separated from the atmosphere. For conventional, industrial-scale, saline-formation CCS, pressure buildup can have a limiting effect on CO2 storage capacity. To address this concern, we analyze Active CO2 Reservoir Management (ACRM), which combines brine extraction and residual-brine reinjection with CO2 injection, comparing it with conventional saline-formation CCS. We investigate the influence of brine extraction on pressure response and CO2 and brine migration using the NUFT code. By extracting brine from the lower portion of the storage formation, from locations progressively further from the center of injection, we can counteract buoyancy that drives CO2 to the top of the formation, which is useful in dipping formations. Using “push-pull” manipulation of the CO2 plume, we expose less of the caprock seal to CO2 and more of the storage formation to CO2, with more of the formation utilized for trapping mechanisms. Plume manipulation can also counteract the influence of heterogeneity. We consider the impact of extraction ratio, defined as net extracted brine volume (extraction minus reinjection) divided by injected CO2 volume. Pressure buildup is reduced with increasing extraction ratio, which reduces CO2 and brine migration, increases CO2 storage capacity, and reduces other risks, such as leakage up abandoned wells, caprock fracturing, fault activation, and induced seismicity. For a 100-yr injection period, a 10-yr delay in brine extraction does not diminish the magnitude of pressure reduction. Moreover, it is possible to achieve pressure management with just a few brine-extraction wells

  20. Improved reservoir description of the Heidrun Field, Norway, using a combination of sedimentological, geochemical and pressure data

    SciTech Connect

    Van Graas, G.W.; Odden, W. ); Svela, E. )

    1996-01-01

    The Tilje Fm. on the Heidrun Field was deposited in a shallow marine to parallic setting dominated by tidal processes. The resulting, often heterolithic, sedimentary sequences can potentially act as barriers to fluid flow due to lack of lateral continuity of sand bodies, and restricted vertical permeability due to clay drapes and tentacular bedding. Based on the sedimentological model and RFT pressure data, a number of potential barriers to fluid flow were identified. In order to substantiate the existence of these barriers a suite of core samples was collected for geochemical analysis. Using core extracts instead of test oils allows for a denser sampling of the reservoir, providing a more detailed description of any variations in reservoir fluid composition. Gas chromatograms of the core extracts show the presence of two oil types in Tilje reservoirs: (A) a strongly biodegraded oil, (B) a mixture of degraded and non-degraded oil. Intervals containing different oil types are usually sharply delineated, with no suggestion of a gradual change from one type to the other. Both oil types are also found at different relative positions, i.e. type A is found both above and below type B within one well. These observations can be explained by a dual charge model: (i) a first charge of biodegraded oil filling the entire Tilje reservoir; (ii) a second (or continuous) charge of non-degraded oil, arriving after the reservoir has passed the temperature threshold for biodegradation (approx. 70[degrees]C), which was unable to penetrate the entire reservoir. The resulting distribution pattern clearly outlines the presence of barriers to fluid flow. The reservoir units thus identified agree in many cases with the model based on the sedimentological and pressure data. In a few cases a different depth is indicated for a barrier, while also some additional barriers are indicated by the geochemical data.

  1. Improved reservoir description of the Heidrun Field, Norway, using a combination of sedimentological, geochemical and pressure data

    SciTech Connect

    Van Graas, G.W.; Odden, W.; Svela, E.

    1996-12-31

    The Tilje Fm. on the Heidrun Field was deposited in a shallow marine to parallic setting dominated by tidal processes. The resulting, often heterolithic, sedimentary sequences can potentially act as barriers to fluid flow due to lack of lateral continuity of sand bodies, and restricted vertical permeability due to clay drapes and tentacular bedding. Based on the sedimentological model and RFT pressure data, a number of potential barriers to fluid flow were identified. In order to substantiate the existence of these barriers a suite of core samples was collected for geochemical analysis. Using core extracts instead of test oils allows for a denser sampling of the reservoir, providing a more detailed description of any variations in reservoir fluid composition. Gas chromatograms of the core extracts show the presence of two oil types in Tilje reservoirs: (A) a strongly biodegraded oil, (B) a mixture of degraded and non-degraded oil. Intervals containing different oil types are usually sharply delineated, with no suggestion of a gradual change from one type to the other. Both oil types are also found at different relative positions, i.e. type A is found both above and below type B within one well. These observations can be explained by a dual charge model: (i) a first charge of biodegraded oil filling the entire Tilje reservoir; (ii) a second (or continuous) charge of non-degraded oil, arriving after the reservoir has passed the temperature threshold for biodegradation (approx. 70{degrees}C), which was unable to penetrate the entire reservoir. The resulting distribution pattern clearly outlines the presence of barriers to fluid flow. The reservoir units thus identified agree in many cases with the model based on the sedimentological and pressure data. In a few cases a different depth is indicated for a barrier, while also some additional barriers are indicated by the geochemical data.

  2. Effect of Salinity on Effective CO2 Permeability in Reservoir Rock Determined by Pressure Transient Methods: an Experimental Study on Hawkesbury Sandstone

    NASA Astrophysics Data System (ADS)

    Rathnaweera, T. D.; Ranjith, P. G.; Perera, M. S. A.

    2015-09-01

    The determination of effective carbon dioxide (CO2) permeability in reservoir rock and its variation is of great interest in the process of CO2 sequestration in deep saline aquifers, as CO2 sequestration-induced permeability alternations appear to create major problems during the CO2 injection process. The main objective of this study is to investigate the effect of salinity on the effective CO2 permeability of reservoir rock under different injection pressures. A series of high-pressure tri-axial experiments was, therefore, performed to investigate the effect of salinity on effective CO2 permeability in Hawkesbury sandstone under various brine concentrations. The selected brine concentrations were 0, 10, 20, and 30 % sodium chloride (NaCl) by weight and the experiments were conducted for a range of CO2 injection pressures (2, 4, 6, 8, 10, and 12 MPa) at a constant confinement of 20 MPa and a temperature of 35 °C, respectively. According to the results, the degree of salinity of the aquifer's pore fluid plays a vital role in the effective CO2 permeability variation which occurs with CO2 injection, and the effective permeability decreases with increasing salinity in the range of 0-30 % of NaCl. Interestingly, in dry reservoir rock samples, the phase transition of the injection of CO2 from gas to super-critical condition caused a sudden reduction of CO2 permeability, related to the slip flow effect which occurs in gas CO2. Transfer into vapor or super-critical CO2 causes this slip flow to be largely reduced, reducing the reservoir permeability for CO2 movement in dry reservoir rock samples. However, this behavior was not observed for water- and brine-saturated samples, and an increasing trend of effective CO2 permeability was observed with increasing injection pressure. A detailed chemical analysis was then conducted to understand the physical phenomenon causing the salinity effect on effective CO2 permeability using scanning electron microscopy analyses. Such

  3. Superposition well-test method for reservoir characterization and pressure management during CO2 injection

    NASA Astrophysics Data System (ADS)

    White, J. A.

    2014-12-01

    As a significant fraction of a carbon storage project's budget is devoted to site characterization and monitoring, there has been an intense drive in recent years to both lower cost and improve the quality of data obtained. Two data streams that are cheap and always available are pressure and flow rate measurements from the injection well. Falloff testing, in which the well is shut-in for some period of time and the pressure decline curve measured, is often used to probe the storage zone and look for indications of hydraulic barriers, fracture-dominated flow, and other reservoir characteristics. These tests can be used to monitor many hydromechanical processes of interest, including hydraulic fracturing and fault reactivation. Unfortunately, the length of the shut-in period controls how far away from the injector information may be obtained. For operational reasons these tests are typically kept short and infrequent, limiting their usefulness. In this work, we present a new analysis method in which ongoing injection data is used to reconstruct an equivalent falloff test, without shutting in the well. The entire history of injection may therefore be used as a stand in for a very long test. The method relies upon a simple superposition principle to transform a multi-rate injection sequence into an equivalent single-rate process. We demonstrate the effectiveness of the method using injection data from the Snøhvit storage project. We also explore its utility in an active pressure management scenario. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

  4. Subsurface monitoring of reservoir pressure, temperature, relative humidity, and water content at the CAES Field Experiment, Pittsfield, Illinois: system design

    SciTech Connect

    Hostetler, D.D.; Childs, S.W.; Phillips, S.J.

    1983-03-01

    This subsurface-instrumentation design has been developed for the first Compressed Air Energy Storage (CAES) field experiment to be performed in porous media. Energy storage will be accomplished by alternating the injection and withdrawal of compressed air in a confined sandstone aquifer near Pittsfield, Illinois. The overall experiment objective is to characterize the reservoir's geochemical and thermohydraulic response to imposed CAES conditions. Specific experiment objectives require monitoring: air-bubble development; thermal development; cyclic pressure response; reservoir dehydration; and water coning. Supporting these objectives, four parameters will be continuously monitored at depth in the reservoir. They are: temperature; pressure; pore-air relative humidity; and pore-water content. Reservoir temperatures and pressures will range to maximum values approaching 200/sup 0/C and 300 psi, respectively. Both pore-air relative humidity and pore-water content will range from approx. 0 to 100%. This report discusses: instrumentation design; sensor and sensor system calibration; field installation and testing; and instrument-system operation. No comprehensive off-the-shelf instrument package exists to adequately monitor CAES reservoir parameters at depth. The best available sensors were selected and adapted for use under expected ranges of reservoir conditions. The instrumentation design criteria required: suitable sensor accuracy; continuous monitoring capability; redundancy; maximum sensor integrity; contingency planning; and minimum cost-information ratio. Three wells will be instrumented: the injection/withdrawal (I/W) well and the two instrument wells. Sensors will be deployed by wireline suspension in both open and backfilled (with sand) wellbores. The sensors deployed in the I/W well will be retrievable; the instrument-well sensors will not.

  5. Carbon dioxide reduction in low-pressure ICP

    NASA Astrophysics Data System (ADS)

    Dudin, Stanislav; Dakhov, Alexander

    2016-09-01

    This work experimentally investigates the efficiency of carbon dioxide dissociation in inductively coupled plasma (ICP) at low gas pressure. The plasma source operates at 13.56 MHz in the RF power range of 100-500 W. Pure CO2 is fed into the plasma while the output gas composition is measured by a mass spectrometer. The pressure range inside the source was changed in the range of 1-200 mTorr. Excitation processes in the plasma are studied by means of optical emission spectroscopy, and the plasma density along with the electron temperature are monitored using a Langmuir probe. Experimental results have shown that the conversion efficiency of CO2 to CO and O2 increases with the RF and reaches the values more than 50%. A theoretical treatment of the dissociation pathway is also given allowing estimation of the mean dissociation length of the carbon dioxide molecule in plasma. The plasma parameters necessary for efficient CO2 reduction are discussed.

  6. Method for growth of crystals by pressure reduction of supercritical or subcritical solution

    NASA Technical Reports Server (NTRS)

    Shlichta, P. J. (Inventor)

    1985-01-01

    Crystals of high morphological quality are grown by dissolution of a substance to be grown into the crystal in a suitable solvent under high pressure, and by subsequent slow, time-controlled reduction of the pressure of the resulting solution. During the reduction of the pressure interchange of heat between the solution and the environment is minimized by performing the pressure reduction either under isothermal or adiabatic conditions.

  7. Associations and clinical relevance of aortic-brachial artery stiffness mismatch, aortic reservoir function, and central pressure augmentation.

    PubMed

    Schultz, Martin G; Hughes, Alun D; Davies, Justin E; Sharman, James E

    2015-10-01

    Central augmentation pressure (AP) and index (AIx) predict cardiovascular events and mortality, but underlying physiological mechanisms remain disputed. While traditionally believed to relate to wave reflections arising from proximal arterial impedance (and stiffness) mismatching, recent evidence suggests aortic reservoir function may be a more dominant contributor to AP and AIx. Our aim was therefore to determine relationships among aortic-brachial stiffness mismatching, AP, AIx, aortic reservoir function, and end-organ disease. Aortic (aPWV) and brachial (bPWV) pulse wave velocity were measured in 359 individuals (aged 61 ± 9, 49% male). Central AP, AIx, and aortic reservoir indexes were derived from radial tonometry. Participants were stratified by positive (bPWV > aPWV), negligible (bPWV ≈ aPWV), or negative stiffness mismatch (bPWV < aPWV). Left-ventricular mass index (LVMI) was measured by two-dimensional-echocardiography. Central AP and AIx were higher with negative stiffness mismatch vs. negligible or positive stiffness mismatch (11 ± 6 vs. 10 ± 6 vs. 8 ± 6 mmHg, P < 0.001 and 24 ± 10 vs. 24 ± 11 vs. 21 ± 13%, P = 0.042). Stiffness mismatch (bPWV-aPWV) was negatively associated with AP (r = -0.18, P = 0.001) but not AIx (r = -0.06, P = 0.27). Aortic reservoir pressure strongly correlated to AP (r = 0.81, P < 0.001) and AIx (r = 0.62, P < 0.001) independent of age, sex, heart rate, mean arterial pressure, and height (standardized β = 0.61 and 0.12, P ≤ 0.001). Aortic reservoir pressure independently predicted abnormal LVMI (β = 0.13, P = 0.024). Positive aortic-brachial stiffness mismatch does not result in higher AP or AIx. Aortic reservoir function, rather than discrete wave reflection from proximal arterial stiffness mismatching, provides a better model description of AP and AIx and also has clinical relevance as evidenced by an independent association of aortic reservoir pressure with LVMI.

  8. Effects of pressure drawdown and recovery on the Cerro Prieto beta reservoir in the CP-III area

    SciTech Connect

    Truesdell, A.H.; Lippmann, M.J.

    1998-02-01

    The production characteristics of wells in the northwestern Cerro Prieto III area changed greatly when the Cp-III power plant went on line in 1986. Fluid extraction in the field more than doubled and reservoir-wide boiling started immediately, greatly increasing the enthalpy of produced fluids. Some well fluids showed a decrease in chloride due to adiabatic steam condensation in the well and separator, and others were enriched in chloride due to boiling. As reservoir drawdown increased, entrance of cooler and more dilute groundwaters into the reservoir became evident (i.e., condensation stopped, and there was a decrease in enthalpy and chloride in produced fluids). Although some groundwater inflow was from the leaky western margin of the reservoir, the majority is in the northeast, inferred to be local and downward, possibly through more permeable zones associated with the normal fault H. This natural recharge and some reinjection have slowed and possibly reversed pressure drawdown throughout CP-III. Enthalpy has decreased and liquid saturation has increased as the steam-rich zone in the upper part of the reservoir has either disappeared or become thinner.

  9. By how much does dietary salt reduction lower blood pressure? III--Analysis of data from trials of salt reduction.

    PubMed Central

    Law, M R; Frost, C D; Wald, N J

    1991-01-01

    OBJECTIVE--To determine whether the reduction in blood pressure achieved in trials of dietary salt reduction is quantitatively consistent with estimates derived from blood pressure and sodium intake in different populations, and, if so, to estimate the impact of reducing dietary salt on mortality from stroke and ischaemic heart disease. DESIGN--Analysis of the results of 68 crossover trials and 10 randomised controlled trials of dietary salt reduction. MAIN OUTCOME MEASURE--Comparison of observed reductions in systolic blood pressure for each trial with predicted values calculated from between population analysis. RESULTS--In the 45 trials in which salt reduction lasted four weeks or less the observed reductions in blood pressure were less than those predicted, with the difference between observed and predicted reductions being greatest in the trials of shortest duration. In the 33 trials lasting five weeks or longer the predicted reductions in individual trials closely matched a wide range of observed reductions. This applied for all age groups and for people with both high and normal levels of blood pressure. In people aged 50-59 years a reduction in daily sodium intake of 50 mmol (about 3 g of salt), attainable by moderate dietary salt reduction would, after a few weeks, lower systolic blood pressure by an average of 5 mm Hg, and by 7 mm Hg in those with high blood pressure (170 mm Hg); diastolic blood pressure would be lowered by about half as much. It is estimated that such a reduction in salt intake by a whole Western population would reduce the incidence of stroke by 22% and of ischaemic heart disease by 16% [corrected]. CONCLUSIONS--The results from the trials support the estimates from the observational data in the accompanying two papers. The effect of universal moderate dietary salt reduction on mortality from stroke and ischaemic heart disease would be substantial--larger, indeed, than could be achieved by fully implementing recommended policy for

  10. Reduction of particulate carryover from a pressurized fluidized bed

    NASA Technical Reports Server (NTRS)

    Patch, R. W.

    1979-01-01

    A bench scale fluidized bed combustor was constructed with a conical shape so that the enlarged upper part of the combustor would also serve as a granular bed filter. The combustor was fed coal and limestone. Ninety-nine tests of about four hours each were conducted over a range of conditions. Coal-to-air ratio varied from 0.033 to 0.098 (all lean). Limestone-to-coal ratio varied from 0.06 to 0.36. Bed depth varied from 3.66 to 8.07 feet. Temperature varied from 1447 to 1905 F. Pressure varied from 40 to 82 psia. Heat transfer area had the range zero to 2.72 ft squared. Two cone angles were used. The average particulate carry over of 2.5 grains/SCF was appreciably less than cylindrical fluidized bed combustors. The carry over was correlated by multiple regression analysis to yield the dependence on bed depth and hence the collection efficiency, which was 20%. A comparison with a model indicated that the exhaust port may be below the transport disengaging height for most of the tests, indicating that further reduction in carry over and increase in collection efficiency could be affected by increasing the freeboard and height of the exhaust port above the bed.

  11. Light oil recovery from cyclic CO sub 2 injection; Influence of low pressures, impure CO sub 2 , and reservoir gas

    SciTech Connect

    Monger, T.G.; Ramos, J.C.; Thomas, J. )

    1991-02-01

    This paper is a laboratory and field investigation of the CO{sub 2} huff n puff process for the enhanced recovery of light crude oil. Cyclic CO{sub 2} displacement results with live and dead oils in watered-out Berea cores are presented. Sixty-five single-well cyclic CO{sub 2} field tests conducted in a pressure-depleted reservoir are evaluated.

  12. Analysis of formation pressure test results in the Mount Elbert methane hydrate reservoir through numerical simulation

    USGS Publications Warehouse

    Kurihara, M.; Sato, A.; Funatsu, K.; Ouchi, H.; Masuda, Y.; Narita, H.; Collett, T.S.

    2011-01-01

    Targeting the methane hydrate (MH) bearing units C and D at the Mount Elbert prospect on the Alaska North Slope, four MDT (Modular Dynamic Formation Tester) tests were conducted in February 2007. The C2 MDT test was selected for history matching simulation in the MH Simulator Code Comparison Study. Through history matching simulation, the physical and chemical properties of the unit C were adjusted, which suggested the most likely reservoir properties of this unit. Based on these properties thus tuned, the numerical models replicating "Mount Elbert C2 zone like reservoir" "PBU L-Pad like reservoir" and "PBU L-Pad down dip like reservoir" were constructed. The long term production performances of wells in these reservoirs were then forecasted assuming the MH dissociation and production by the methods of depressurization, combination of depressurization and wellbore heating, and hot water huff and puff. The predicted cumulative gas production ranges from 2.16??106m3/well to 8.22??108m3/well depending mainly on the initial temperature of the reservoir and on the production method.This paper describes the details of modeling and history matching simulation. This paper also presents the results of the examinations on the effects of reservoir properties on MH dissociation and production performances under the application of the depressurization and thermal methods. ?? 2010 Elsevier Ltd.

  13. Physical Mechanisms of Failure, Ultralow Partial Pressure Lubrication, and the Reservoir Effect in MEMS

    NASA Astrophysics Data System (ADS)

    Hook, David Adam

    measurements relating to microsystem contact conditions experiments must be conducted on actual microdevices. In the work presented here I have used microelectromechanical system (MEMS) tribometers to measure the friction and adhesive forces of SAM coated surfaces over the coarse of many sliding cycles as well as normal contacting cycles. It is shown that robustly adhered monolayer coatings degrade extremely rapidly and there is a direct correlation between the respective energies dissipated both in sliding and normal contacting cycles and the time it takes for the layers to degrade. Also it is shown that devices fail in two main modes: one where wear of the devices in the form of dislocation of polysilicon grains leads to a low/adhesion high wear regime and another where high adhesive forces are developed and the devices fail with little to no wear. In the studies of ultra low partial pressure lubrication of devices a clear correlation between lubricant mobility to device lubrication is observed even in the presence of a vapor, which should in principle be able to replenish removed lubricant in between sliding cycles. We show that ultralow partial pressures nominally corresponding to submonolayer coverages of ethanol and pentanol show a distinct decrease in coefficient of friction and lubricate MEMS microcontacts however this is only loosely correlated to their effectiveness as lubricants. Pentanol was only shown to lubricate at the point at which it becomes mobile on the surface where as ethanol is mobile at all times and lubricates effectively at very low partial pressures. Trifluoroethanol is not mobile at any portion of its isotherm and does not effectively lubricate the contacts. We also show the ability of the surrounding SAM to act as a lubricant reservoir when vapors of ethanol are removed. The correlation of lubricant mobility to lubrication can be used to predict the effectiveness to new lubricants as well as allow for the tailoring of lubricants to specific

  14. The use of wireline pressure measurements to refine reservoir description, Main Body B waterflood, Elk Hills oil field, Kern County, California

    SciTech Connect

    Wilson, M. ); Love, C. ); Fishburn, M. ); Humphrey, M. )

    1991-02-01

    The Main Body B, one of five large Stevens sand reservoirs at Elk Hills, occupies the eastern half of the 31S anticline. Early in the production history of this reservoir, the Elk Hills unit initiated peripheral water injection to maintain reservoir pressure. Water injection has proceeded at a rate approximately equal to the voidage created by oil and gas production and has moved water upstructure creating an oil bank. Bechtel Petroleum Operations Inc., the current unit operator, drills five to ten new wells each year to fully exploit this oil bank. In 1985, the unit added wireline pressure measurements to the open-hole logging programs of these infill wells for the purpose of evaluating the net effect of injection into and production from the Main Body B reservoir. A typical well provides the opportunity to obtain 8-10 pressures from the Main Body B. To date, the Unit has measured wireline pressures in more than two dozen wells. The wireline measurements have shown a broader than expected range of formation pressures (1,600 {plus minus} psi to 4,200 {plus minus} psi). The pressures show that this is a layered reservoir with little vertical pressure communication between some of the layers. In some parts of the reservoir, wireline pressures indicate horizontal continuity of the layers between wells and in other areas pressure differences between adjacent wells may indicate faults or cementation barriers. Permeabilities calculated from the sampling drawdown are the same order of magnitude as brine permeabilities obtained from core and show that higher-pressured layers of the reservoir have lower permeability. These observations fundamentally alter performance evaluation of the Main Body B waterflood.

  15. Pore Pressure prediction in shale gas reservoirs using neural network and fuzzy logic with an application to Barnett Shale.

    NASA Astrophysics Data System (ADS)

    Aliouane, Leila; Ouadfeul, Sid-Ali; Boudella, Amar

    2015-04-01

    The main goal of the proposed idea is to use the artificial intelligence such as the neural network and fuzzy logic to predict the pore pressure in shale gas reservoirs. Pore pressure is a very important parameter that will be used or estimation of effective stress. This last is used to resolve well-bore stability problems, failure plan identification from Mohr-Coulomb circle and sweet spots identification. Many models have been proposed to estimate the pore pressure from well-logs data; we can cite for example the equivalent depth model, the horizontal model for undercompaction called the Eaton's model…etc. All these models require a continuous measurement of the slowness of the primary wave, some thing that is not easy during well-logs data acquisition in shale gas formtions. Here, we suggest the use the fuzzy logic and the multilayer perceptron neural network to predict the pore pressure in two horizontal wells drilled in the lower Barnett shale formation. The first horizontal well is used for the training of the fuzzy set and the multilayer perecptron, the input is the natural gamma ray, the neutron porosity, the slowness of the compression and shear wave, however the desired output is the estimated pore pressure using Eaton's model. Data of another horizontal well are used for generalization. Obtained results clearly show the power of the fuzzy logic system than the multilayer perceptron neural network machine to predict the pore pressure in shale gas reservoirs. Keywords: artificial intelligence, fuzzy logic, pore pressure, multilayer perecptron, Barnett shale.

  16. Compaction and Permeability Reduction of Castlegate Sandstone under Pore Pressure Cycling

    NASA Astrophysics Data System (ADS)

    Bauer, S. J.

    2014-12-01

    We investigate time-dependent compaction and permeability changes by cycling pore pressure with application to compressed air energy storage (CAES) in a reservoir. Preliminary experiments capture the impacts of hydrostatic stress, pore water pressure, pore pressure cycling, chemical, and time-dependent considerations near a borehole in a CAES reservoir analog. CAES involves creating an air bubble in a reservoir. The high pressure bubble serves as a mechanical battery to store potential energy. When there is excess grid energy, bubble pressure is increased by air compression, and when there is energy needed on the grid, stored air pressure is released through turbines to generate electricity. The analog conditions considered are depth ~1 km, overburden stress ~20 MPa and a pore pressure ~10MPa. Pore pressure is cycled daily or more frequently between ~10 MPa and 6 MPa, consistent with operations of a CAES facility at this depth and may continue for operational lifetime (25 years). The rock can vary from initially fully-to-partially saturated. Pore pressure cycling changes the effective stress.Jacketed, room temperature tap water-saturated samples of Castlegate Sandstone are hydrostatically confined (20 MPa) and subjected to a pore pressure resulting in an effective pressure of ~10 MPa. Pore pressure is cycled between 6 to 10 MPa. Sample displacement measurements yielded determinations of volumetric strain and from water flow measurements permeability was determined. Experiments ran for two to four weeks, with 2 to 3 pore pressure cycles per day. The Castlegate is a fluvial high porosity (>20%) primarily quartz sandstone, loosely calcite cemented, containing a small amount of clay.Pore pressure cycling induces compaction (~.1%) and permeability decreases (~20%). The results imply that time-dependent compactive processes are operative. The load path, of increasing and decreasing pore pressure, may facilitate local loosening and grain readjustments that results in the

  17. Implications of Limited Thermophilicity of Nitrite Reduction for Control of Sulfide Production in Oil Reservoirs

    PubMed Central

    Fida, Tekle Tafese; Chen, Chuan; Okpala, Gloria

    2016-01-01

    ABSTRACT Nitrate reduction to nitrite in oil fields appears to be more thermophilic than the subsequent reduction of nitrite. Concentrated microbial consortia from oil fields reduced both nitrate and nitrite at 40 and 45°C but only nitrate at and above 50°C. The abundance of the nirS gene correlated with mesophilic nitrite reduction activity. Thauera and Pseudomonas were the dominant mesophilic nitrate-reducing bacteria (mNRB), whereas Petrobacter and Geobacillus were the dominant thermophilic NRB (tNRB) in these consortia. The mNRB Thauera sp. strain TK001, isolated in this study, reduced nitrate and nitrite at 40 and 45°C but not at 50°C, whereas the tNRB Petrobacter sp. strain TK002 and Geobacillus sp. strain TK003 reduced nitrate to nitrite but did not reduce nitrite further from 50 to 70°C. Testing of 12 deposited pure cultures of tNRB with 4 electron donors indicated reduction of nitrate in 40 of 48 and reduction of nitrite in only 9 of 48 incubations. Nitrate is injected into high-temperature oil fields to prevent sulfide formation (souring) by sulfate-reducing bacteria (SRB), which are strongly inhibited by nitrite. Injection of cold seawater to produce oil creates mesothermic zones. Our results suggest that preventing the temperature of these zones from dropping below 50°C will limit the reduction of nitrite, allowing more effective souring control. IMPORTANCE Nitrite can accumulate at temperatures of 50 to 70°C, because nitrate reduction extends to higher temperatures than the subsequent reduction of nitrite. This is important for understanding the fundamentals of thermophilicity and for the control of souring in oil fields catalyzed by SRB, which are strongly inhibited by nitrite. PMID:27208132

  18. An iron-iron hydrogenase mimic with appended electron reservoir for efficient proton reduction in aqueous media

    PubMed Central

    Becker, René; Amirjalayer, Saeed; Li, Ping; Woutersen, Sander; Reek, Joost N. H.

    2016-01-01

    The transition from a fossil-based economy to a hydrogen-based economy requires cheap and abundant, yet stable and efficient, hydrogen production catalysts. Nature shows the potential of iron-based catalysts such as the iron-iron hydrogenase (H2ase) enzyme, which catalyzes hydrogen evolution at rates similar to platinum with low overpotential. However, existing synthetic H2ase mimics generally suffer from low efficiency and oxygen sensitivity and generally operate in organic solvents. We report on a synthetic H2ase mimic that contains a redox-active phosphole ligand as an electron reservoir, a feature that is also crucial for the working of the natural enzyme. Using a combination of (spectro)electrochemistry and time-resolved infrared spectroscopy, we elucidate the unique redox behavior of the catalyst. We find that the electron reservoir actively partakes in the reduction of protons and that its electron-rich redox states are stabilized through ligand protonation. In dilute sulfuric acid, the catalyst has a turnover frequency of 7.0 × 104 s−1 at an overpotential of 0.66 V. This catalyst is tolerant to the presence of oxygen, thereby paving the way for a new generation of synthetic H2ase mimics that combine the benefits of the enzyme with synthetic versatility and improved stability. PMID:26844297

  19. An iron-iron hydrogenase mimic with appended electron reservoir for efficient proton reduction in aqueous media.

    PubMed

    Becker, René; Amirjalayer, Saeed; Li, Ping; Woutersen, Sander; Reek, Joost N H

    2016-01-01

    The transition from a fossil-based economy to a hydrogen-based economy requires cheap and abundant, yet stable and efficient, hydrogen production catalysts. Nature shows the potential of iron-based catalysts such as the iron-iron hydrogenase (H2ase) enzyme, which catalyzes hydrogen evolution at rates similar to platinum with low overpotential. However, existing synthetic H2ase mimics generally suffer from low efficiency and oxygen sensitivity and generally operate in organic solvents. We report on a synthetic H2ase mimic that contains a redox-active phosphole ligand as an electron reservoir, a feature that is also crucial for the working of the natural enzyme. Using a combination of (spectro)electrochemistry and time-resolved infrared spectroscopy, we elucidate the unique redox behavior of the catalyst. We find that the electron reservoir actively partakes in the reduction of protons and that its electron-rich redox states are stabilized through ligand protonation. In dilute sulfuric acid, the catalyst has a turnover frequency of 7.0 × 10(4) s(-1) at an overpotential of 0.66 V. This catalyst is tolerant to the presence of oxygen, thereby paving the way for a new generation of synthetic H2ase mimics that combine the benefits of the enzyme with synthetic versatility and improved stability.

  20. Water quality change in dam reservoir and shallow aquifer: analysis on trend, seasonal variability and data reduction.

    PubMed

    Chowdhury, Shakhawat; Al-Zahrani, Muhammad

    2014-10-01

    Change of water quality in dam reservoir and aquifer complicates safe drinking water supply. Few parameters are monitored to control water quality in these sources. Adequate knowledge on the correlation structure, interaction effect, trends and seasonal variability of these parameters is essential to control water quality. This study applied time series and multivariate analyses on 15 water quality parameters, collected from the King Fahd dam reservoir (L1) and aquifer (L2) in Saudi Arabia during April 2010 to February 2012. Moderate to strong correlations were observed between sulfate, hardness, fluoride, chloride, magnesium, conductivity, turbidity and total dissolved solids (TDS), while separate clusters were visible for TDS-chloride-magnesium-conductivity; fluoride-turbidity; chloride-hardness; ammonia-nitrate; and calcium-magnesium-hardness. Four major principal components explained 81.1% and 83.2% of the overall variances in L1 and L2, respectively. The factor analysis showed that 53% and 67% of the data were necessary to explain 81.3% and 83.2% of total variances for L1 and L2, respectively, indicating the possibility of data reduction. Possible degradation of water quality in these sources was highlighted, while such degradation may require enhanced treatment for producing drinking water in future.

  1. Reduction of disinfection by-product precursors in reservoir water by coagulation and ultrafiltration.

    PubMed

    Wang, Feng; Gao, Baoyu; Ma, Defang; Yue, Qinyan; Li, Ruihua; Wang, Qianwen

    2016-11-01

    In this study, reservoir water intended for drinking water supply was treated by (i) ultrafiltration (UF) (ii) coagulation (CW) (iii) coagulation combined with ultrafiltration (CW-UF). To probe the influences of three treatment processes on disinfection byproduct (DBP) precursors in source water, the changes of dissolved organic matter (DOM) amounts and physicochemical properties, and disinfection byproduct (DBP) formation characteristics during chlorine disinfection were investigated. Both carbonaceous DBP (C-DBP) and nitrogenous DBP (N-DBP) formation and speciation were analyzed. The influence of chlorine dose, contact time on DBP formation and speciation were also studied to optimize the disinfection conditions to minimize the DBP formation. Compared with UF and CW alone, CW-UF improved the dissolved organic carbon (DOC) removal from about 20 % to 59 %. The three-dimensional excitation and emission matrix (3DEEM) fluorescence spectroscopy analysis showed that CW-UF had high removal efficiency in microbial products (Region IV), fulvic acid-like (Region III) and humic acid-like (Region V). The total C-DBP was determined by the formation of trihalomethanes and trichloromethane was the most abundant species (40 %). The most abundant N-DBP species was dichloroacetonitrile (32.5 %), followed by trichloroactetonitrile. CW-UF effectively reduced the risk of DBPs in drinking water supply by reducing 30.8 % and 16.9 % DBPs formation potential compared with UF and CW alone. Increasing contact time improved the yields of both C-DBPs and N-DBPs. Chlorine dosage had slight influence on DBP yield in this study.

  2. Finite element analysis of land subsidence above depleted reservoirs with pore pressure gradient and total stress formulations

    NASA Astrophysics Data System (ADS)

    Gambolati, Giuseppe; Ferronato, Massimiliano; Teatini, Pietro; Deidda, Roberto; Lecca, Giuditta

    2001-04-01

    The solution of the poroelastic equations for predicting land subsidence above productive gas/oil fields may be addressed by the principle of virtual works using either the effective intergranular stress, with the pore pressure gradient regarded as a distributed body force, or the total stress incorporating the pore pressure. In the finite element (FE) method both approaches prove equivalent at the global assembled level. However, at the element level apparently the equivalence does not hold, and the strength source related to the pore pressure seems to generate different local forces on the element nodes. The two formulations are briefly reviewed and discussed for triangular and tetrahedral finite elements. They are shown to yield different results at the global level as well in a three-dimensional axisymmetric porous medium if the FE integration is performed using the average element-wise radius. A modification to both formulations is suggested which allows to correctly solve the problem of a finite reservoir with an infinite pressure gradient, i.e. with a pore pressure discontinuity on its boundary.

  3. Reduction of Ammonia and Tar in Pressurized Biomass Gasification

    SciTech Connect

    Wang, W.; Olofsson, G.

    2002-09-19

    The present paper intended to present the results of parametric study of the formation of ammonia and tar under pressurized gasification conditions. By the use of multivariate data analysis, the effects of operating parameters were determined and their influences could be quantified. In order to deal with cases in which high levels of ammonia and tar were produced, study of catalytic hot gas cleaning was performed, aiming to discuss the removal efficiency and test catalysts.

  4. Biomechanics of Schlemm's canal endothelium and intraocular pressure reduction.

    PubMed

    Stamer, W Daniel; Braakman, Sietse T; Zhou, Enhua H; Ethier, C Ross; Fredberg, Jeffrey J; Overby, Darryl R; Johnson, Mark

    2015-01-01

    Ocular hypertension in glaucoma develops due to age-related cellular dysfunction in the conventional outflow tract, resulting in increased resistance to aqueous humor outflow. Two cell types, trabecular meshwork (TM) and Schlemm's canal (SC) endothelia, interact in the juxtacanalicular tissue (JCT) region of the conventional outflow tract to regulate outflow resistance. Unlike endothelial cells lining the systemic vasculature, endothelial cells lining the inner wall of SC support a transcellular pressure gradient in the basal to apical direction, thus acting to push the cells off their basal lamina. The resulting biomechanical strain in SC cells is quite large and is likely to be an important determinant of endothelial barrier function, outflow resistance and intraocular pressure. This review summarizes recent work demonstrating how biomechanical properties of SC cells impact glaucoma. SC cells are highly contractile, and such contraction greatly increases cell stiffness. Elevated cell stiffness in glaucoma may reduce the strain experienced by SC cells, decrease the propensity of SC cells to form pores, and thus impair the egress of aqueous humor from the eye. Furthermore, SC cells are sensitive to the stiffness of their local mechanical microenvironment, altering their own cell stiffness and modulating gene expression in response. Significantly, glaucomatous SC cells appear to be hyper-responsive to substrate stiffness. Thus, evidence suggests that targeting the material properties of SC cells will have therapeutic benefits for lowering intraocular pressure in glaucoma.

  5. An experimental model of episodic gas release through fracture of fluid confined within a pressurized elastic reservoir

    NASA Astrophysics Data System (ADS)

    Rocco, Stefano; Woods, Andrew W.; Harrington, Jon; Norris, Simon

    2017-01-01

    We present new experiments that identify a mechanism for episodic release of gas from a pressurized, deformable reservoir confined by a clay seal, as a result of the transition from bulk deformation to channel growth through the clay. Air is injected into the center of a thin cylindrical cell initially filled with a mixture of bentonite clay and water. For sufficiently dry mixtures, the pressure initially increases with little volume change. On reaching the yield stress of the clay-water mixture, the lid of the cell then deforms elastically and an air-filled void forms in the center of the cell as the clay is driven radially outward. With continued supply of air, the pressure continues to increase until reaching the fracture strength of the clay. A fracture-like channel then forms and migrates to the outer edge of the cell, enabling the air to escape. The pressure then falls, and the clay flows back toward the center of the cell and seals the channel so the cycle can repeat. The phenomena may be relevant at mud volcanoes.

  6. A parametric analysis of capillary pressure effects during the carbon sequestration injection process in a sandstone reservoir

    NASA Astrophysics Data System (ADS)

    Wu, H.; Pollyea, R.

    2016-12-01

    Geological Carbon Sequestration (GCS) is considered as a key method for mitigating the adverse effects of steadily increasing atmospheric CO2 concentrations. Numerical simulation is one technique for better understanding the injection, migration and leakage of supercritical CO2 (scCO2) during GCS. At the field scale, capillary pressure (Pcap) is an important factor governing the subsurface movement of scCO2. Constitutive models of Pcap as a function of wetting phase saturation (Sw) are essential to field-scale GCS simulations; however, such Pcap models are based on core-scale laboratory measurements. As a result, there exists uncertainty in the application of laboratory-measured Pcap models to field-scale GCS simulations. In this study, a parametric analysis of commonly used van Genucthen Pcap model is undertaken to quantify the effects of variability in the model parameter space. The study focuses on two parameters: the non-wetting phase entry pressure (P0) and the pore-size distribution index (λ), the latter of which controls curvature of the Pcap model. A two-dimensional parameter space is selected that covers a wide range of laboratory-scale Pcap measurements in the scCO2-brine system, and scCO2 injection processes are modeled within a homogeneous sandstone reservoir over the complete parameter space. Simulation results demonstrate how changes in the Pcap model parameters influence scCO2 migration within the storage reservoir. Maximum injection pressure is largely insensitive to variability of Pcap model parameters; however, vertical scCO2 migration is strongly controlled by Pcap model parameter selection. Since vertical scCO2 migration is the key point to estimate scCO2 leakage risk through caprock sealing, these results illustrate the importance of Pcap model parameter selection in field-scale numerical models of GCS.

  7. Effect of longer-term modest salt reduction on blood pressure.

    PubMed

    He, F J; MacGregor, G A

    2004-01-01

    Many randomised trials assessing the effect of salt reduction on blood pressure show reduction in blood pressure in individuals with high blood pressure. However, there is controversy about the magnitude and the clinical significance of the fall in blood pressure in individuals with normal blood pressure. Several meta-analyses of randomised salt reduction trials have been published in the last few years. However, most of these included trials of very short duration (e.g. 5 days) and included trials with salt loading followed by salt deprivation (e.g. from 20 to 1 g/day) over only a few days. These short-term experiments are not appropriate to inform public health policy which is for a modest reduction in salt intake over a prolonged period of time. A meta-analysis by Hooper et al is an important attempt to look at whether advice to achieve a long-term salt reduction (i.e. more than 6 months) in randomised trials causes a fall in blood pressure. However, most trials included in this meta-analysis achieved a small reduction in salt intake; on average, salt intake was reduced by 2 g/day. It is, therefore, not surprising that this analysis showed a small fall in blood pressure, and that a dose-response to salt reduction was not demonstrable. To assess the effect of the currently recommended modest reduction in salt intake (WHO 2003; SACN 2003; Whelton 2002), on blood pressure in individuals with normal and elevated blood pressure. To assess whether the magnitude of the reduction in blood pressure is dependent on the magnitude of the reduction in salt intake. We searched MEDLINE, EMBASE, Cochrane library, CINAHL, and reference list of original and review articles. We included randomised trials with a modest reduction in salt intake and a duration of 4 or more weeks. Data were extracted independently by two persons. Mean effect sizes were calculated using both fixed and random effect models using Review Manager 4.2.1 software. Weighted linear regression was used to

  8. 12 min/week of high-intensity interval training reduces aortic reservoir pressure in individuals with metabolic syndrome: a randomized trial.

    PubMed

    Ramos, Joyce S; Dalleck, Lance C; Ramos, Maximiano V; Borrani, Fabio; Roberts, Llion; Gomersall, Sjaan; Beetham, Kassia S; Dias, Katrin A; Keating, Shelley E; Fassett, Robert G; Sharman, James E; Coombes, Jeff S

    2016-10-01

    Decreased aortic reservoir function leads to a rise in aortic reservoir pressure that is an independent predictor of cardiovascular events. Although there is evidence that high-intensity interval training (HIIT) would be useful to improve aortic reservoir pressure, the optimal dose of high-intensity exercise to improve aortic reservoir function has yet to be investigated. Therefore, this study compared the effect of different volumes of HIIT and moderate-intensity continuous training (MICT) on aortic reservoir pressure in participants with the metabolic syndrome (MetS). Fifty individuals with MetS were randomized into one of the following 16-week training programs: MICT [n = 17, 30 min at 60-70% peak heart rate (HRpeak), five times/week]; 4 × 4-min high-intensity interval training (4HIIT) (n = 15, 4 × 4 min bouts at 85-95% HRpeak, interspersed with 3 min of active recovery at 50-70% HRpeak, three times/week); and 1 × 4-min high-intensity interval training (1HIIT) (n = 18, 1 × 4 min bout at 85-95% HRpeak, three times/week). Aortic reservoir pressure was calculated from radial applanation tonometry. Although not statistically significant, there was a trend for a small-to-medium group × time interaction effect on aortic reservoir pressure, indicating a positive adaptation following 1HIIT compared with 4HIIT and MICT [F (2,46) = 2.9, P = 0.07, η = 0.06]. This is supported by our within-group analysis wherein only 1HIIT significantly decreased aortic reservoir pressure from pre to postintervention (pre-post: 1HIIT 33 ± 16 to 31 ± 13, P = 0.03; MICT 29 ± 9-28 ± 8, P = 0.78; 4HIIT 28 ± 10-30 ± 9 mmHg, P = 0.10). Three sessions of 4 min of high-intensity exercise per week (12 min/week) was sufficient to improve aortic reservoir pressure, and thus may be a time-efficient exercise modality for reducing cardiovascular risk in individuals with MetS.

  9. Reduction of ventricular size after shunting for normal pressure hydrocephalus related to CSF dynamics before shunting.

    PubMed Central

    Tans, J T; Poortvliet, D C

    1988-01-01

    Reduction of ventricular size was determined by repeated computed tomography in 30 adult patients shunted for normal pressure hydrocephalus (NPH) and related to the pressure-volume index (PVI) and resistance to outflow of cerebrospinal fluid (Rcsf) measured before shunting. Rapid and marked reduction of ventricular size (n = 10) was associated with a significantly lower PVI than slow and moderate to marked (n = 13) or minimal to mild reduction (n = 7). Otherwise no relationship could be found between the reduction of ventricular size and PVI or Rcsf. It is concluded that both rate and magnitude of reduction of ventricular size after shunting for NPH are extremely variable. High brain elasticity seems to be the best predictor of rapid and marked reduction. PMID:3379425

  10. Phospholipids fatty acids of drinking water reservoir sedimentary microbial community: Structure and function responses to hydrostatic pressure and other physico-chemical properties.

    PubMed

    Chai, Bei-Bei; Huang, Ting-Lin; Zhao, Xiao-Guang; Li, Ya-Jiao

    2015-07-01

    Microbial communities in three drinking water reservoirs, with different depth in Xi'an city, were quantified by phospholipids fatty acids analysis and multivariate statistical analysis was employed to interpret their response to different hydrostatic pressure and other physico-chemical properties of sediment and overlying water. Principle component analyses of sediment characteristics parameters showed that hydrostatic pressure was the most important effect factor to differentiate the overlying water quality from three drinking water reservoirs from each other. NH4+ content in overlying water was positive by related to hydrostatic pressure, while DO in water-sediment interface and sediment OC in sediment were negative by related with it. Three drinking water reservoir sediments were characterized by microbial communities dominated by common and facultative anaerobic Gram-positive bacteria, as well as, by sulfur oxidizing bacteria. Hydrostatic pressure and physico-chemical properties of sediments (such as sediment OC, sediment TN and sediment TP) were important effect factors to microbial community structure, especially hydrostatic pressure. It is also suggested that high hydrostatic pressure and low dissolved oxygen concentration stimulated Gram-positive and sulfate-reducing bacteria (SRB) bacterial population in drinking water reservoir sediment. This research supplied a successful application of phospholipids fatty acids and multivariate analysis to investigate microbial community composition response to different environmental factors. Thus, few physico-chemical factors can be used to estimate composition microbial of community as reflected by phospholipids fatty acids, which is difficult to detect.

  11. Reduction of abdominal pressure in patients with ascites reduces gastroesophageal reflux.

    PubMed

    Navarro-Rodriguez, T; Hashimoto, C L; Carrilho, F J; Strauss, E; Laudanna, A A; Moraes-Filho, J P P

    2003-01-01

    The effect of the reduction of intra-abdominal pressure on the lower esophageal sphincter pressure (LESP) and the 24-hour pH monitoring were studied in 16 patients with ascites before and after paracentesis. LESP did not change (P > 0.05) with the reduction of intra-abdominal pressure (before paracentesis: 17.48 mmHg and postparacentesis: 18.67 mmHg). The results were divided into two groups according to the achieved reduction in intra-abdominal pressure group A were those in who the reduction was greater than 70% and B consisted of those a reduction of less than 70%. LESP did not change even when results for each group were considered separately (P > 0.05): group A (before: 15.60 mmHg; after: 18.09 mmHg); group B (before: 23.09 mmHg; after: 20.40 mmHg). However the 24-h pH monitoring showed pathological reflux in patients with ascites that was reduced with the paracentesis (P < 0.05; total number of reflux episodes before paracentesis was 520.26, and after, 136.26). All pH-monitoring parameters were statistically different (P < 0.05) before and after the reduction of intra-abdominal pressure for group A but not for group B. LESP does not change significantly (P > 0.05) when the intra-abdominal pressure is significantly reduced (P < 0.05). Patients with ascites showed gastroesophageal reflux. Intra-abdominal pressure reduction greater than 70% lead to a significant reduction in gastroesophageal reflux.

  12. Comparison of CO2 trapping in highly heterogeneous reservoirs with Brooks-Corey and van Genuchten capillary pressure curves

    NASA Astrophysics Data System (ADS)

    Gershenzon, Naum; Soltanian, Mohamadreza; Ritzi, Robert, Jr.; Dominic, David

    2015-04-01

    Geological heterogeneities essentially affect the dynamics of a CO2 plume in subsurface environments. Recent studies have led to new conceptual and quantitative models for sedimentary architecture in fluvial deposits over a range of scales that are relevant to the performance of some deep saline reservoirs [1, 2]. Previously we showed how the dynamics of a CO2 plume, during and after injection, is influenced by the hierarchical and multi-scale stratal architecture in such reservoirs [3]. The results strongly suggest that representing these small scales (few cm in vertical direction and few meters in horizontal direction) features and representing how they are organized within a hierarchy of larger-scale features, is critical to understanding capillary trapping processes. The results also demonstrated the importance of using separate capillary pressure and relative permeability relationships for different textural facies types. Here we present the result of simulation of CO2 trapping in deep saline aquifers using two different conventional approaches, i.e. Brooks-Corey and van Genuchten, to capillary pressure. We showed that capillary trapping as well as dissolution rates are very different for the Brooks-Corey and van Genuchten approaches if reservoir consists from various species with different capillary pressure and relative permeability curves. We also found a dramatic difference in simulation time; using the van Genuchten approach improves convergence and thus reduces calculation time by one-two orders of magnitude. [1] Bridge, J.S. (2006), Fluvial facies models: Recent developments, in Facies Models Revisited, SEPM Spec. Publ., 84, edited by H. W. Posamentier and R. G. Walker, pp. 85-170, Soc. for Sediment. Geol. (SEPM), Tulsa, Okla [2] Ramanathan, R., A. Guin, R.W. Ritzi, D.F. Dominic, V.L. Freedman, T.D. Scheibe, and I.A. Lunt (2010), Simulating the heterogeneity in channel belt deposits: Part 1. A geometric-based methodology and code, Water Resources

  13. Reduction of Islands in Full-pressure Stellarator Equilibria

    SciTech Connect

    S.R. Hudson; D.A. Monticello; A.H. Reiman

    2001-04-30

    The control of magnetic islands is a crucial issue in designing Stellarators. Islands are associated with resonant radial magnetic fields at rational rotational-transform surfaces and can lead to chaos and poor plasma confinement. In this article, we show that variations in the resonant fields of a full-pressure stellarator equilibrium can be related to variations in the boundary via a coupling matrix, and inversion of this matrix determines a boundary modification for which the island content is significantly reduced. The numerical procedure is described and the results of island optimization are presented. Equilibria with islands are computed using the Princeton Iterative Equilibrium Solver, and resonant radial fields are calculated via construction of quadratic-flux-minimizing surfaces. A design candidate for the National Compact Stellarator Experiment [Phys. Plasmas 8, 2001], which has a large island, is used to illustrate the technique. Small variations in the boundary shape are used to reduce island size and to reverse the phase of a major island chain.

  14. Comparison of different barometric pressure reductions for gravity data and resulting consequences

    NASA Astrophysics Data System (ADS)

    Kroner, C.; Jentzsch, G.

    1999-10-01

    Different methods of barometric pressure reductions are applied on data recorded with the superconducting gravimeter at Potsdam, Germany. The results are compared regarding their success in removing barometric pressure effects in different frequency ranges. Among the corrections, pure regression methods are used as well as a combination of a physical correction using atmospheric Green's functions [Merriam, J.B., 1992. Atmospheric pressure and gravity. Geophys. J. Int. 109, 488-500; Merriam, J.B., 1995. The atmospheric pressure correction in gravity at Cantley Quebec. In: Hsu, H.T. (Ed.), Proceedings of the 12th International Symposium on Earth Tides. Science Press, Beijing, pp. 161-168; Sun, H.-P., 1995. Static deformation and gravity changes at the earth's surface due to the atmospheric pressure. PhD Thesis, Cath. Univ. Louvain, Belgium] and a local reduction coefficient. This combination is required due to the lack of a sufficient number of local barometric pressure data sets. After applying the physical correction on the gravity data, the local coefficient is determined in two ways: as a fit between station pressure and the partly pressure corrected gravity and as a theoretical value calculated with atmospheric Green's functions and station pressure. The efficiency of the corrections is compared by the results of tidal and spectral analyses as well as coherences between corrected, detided gravity and barometric pressure. In comparison to the standard correction with one regression coefficient, we get similar or slightly improved corrections (depending on the frequency) when applying a frequency-dependent admittance or a correction including atmospheric Green's functions. In general, we find no or only small differences in the corrections that emerge for short periods (periods≤2 days) and bigger changes in the long-periodic range (periods>2 days). We attribute the lacking improvement in the short periods to the partly too low sampling rate of the pressure data

  15. Multifunctional Low Pressure Turbine for Core Noise Reduction, Improved Efficiency, and NOx Reduction

    NASA Technical Reports Server (NTRS)

    Miller, Chris; Shyam, Vikram; Rigby, David; Acosta, Waldo

    2013-01-01

    Determining the feasibility of the induced synthetic jet is key, and is still TBD. center dot Available LPT vane volume is sufficient for tens of resonators per span-wise hole spacing, so physically feasible. center dot Determination of acoustic attenuation requires accurate model of vane, resonator locations, flow field and incident waves. (TBD) center dot Determination of NOx reduction is also TBD.

  16. [Reduction effects of agricultural management practices on non-point source pollution in a watershed in Three Gorges Reservoir Area].

    PubMed

    Huang, Zhi-Lin; Tian, Yao-Wu; Xiao, Wen-Fa; Liu, Zhi-Yan

    2010-06-01

    Taking a typical watershed in the Three Gorges Reservoir Area (TGRA) as test object, the AnnAGNPS model was used to evaluate the reduction effects of different cropping, different fertilization level, conservation tillage practice (CTP), conservation reserve program (CRP), and conversion of cropland into forestland program (CCFP) on the output of agricultural non-point source pollution (NPS) in the watershed. The simulation results showed that different cropping had no significant difference in the effect of reducing sediment yield, but had significant difference in the effect of reducing phosphorus output. Fertilization level had significant effects on the outputs of total nitrogen and total phosphorus. CTP decreased the sediment yield significantly but increased the nutrient output. CRP reduced sediment yield, but had less effect in reducing nutrient output. CCFP reduced both sediment yield and nutrient output significantly. After the implementation of CCFP, the sediment yield output on the croplands with a slope greater than 10 degrees was less than 5 t x hm(-2) and the nutrient output was within the permissible limit.

  17. High H2S contents and other effects of thermochemical sulfate reduction in deeply buried carbonate reservoirs: a review

    NASA Astrophysics Data System (ADS)

    Nöth, S.

    The accumulation of high H2S concentrations in oil and gas fields is usually associated with deeply buried high-temperature carbonate reservoirs and is attributed to the abiological oxidation of hydrocarbons by sulfate - thermochemical sulfate reduction (TSR). This review aims at providing an overview of the literature and assessing existing uncertainties in the current understanding of TSR processes and their geological significance. Reaction pathways, various reaction products, the autocatalytic nature of TSR, and reaction kinetics are discussed. Furthermore, various criteria for recognizing TSR effects, such as petrographic/diagenetic alterations and stable isotope geochemistry of the inorganic as well as the organic reactants, are summarized and evaluated. There is overwhelming geological evidence of TSR taking place at a minimum temperature of 110-140°C, but the temperature discrepancy between experimental data and nature still exists. However, the exact nature and mechanisms of catalysts which influence TSR are not known. Local H2S variations may reflect steady-state conditions dominated by H2S buildups and flux out of the system. The latter is controlled by lithological and geological factors.

  18. Implications of Sub-Hydrostatic Pressures in the Bravo Dome Natural CO2 Reservoir for the Long-Term Security of Geological Carbon Dioxide Storage

    NASA Astrophysics Data System (ADS)

    Akhbari, D.; Hesse, M. A.; Larson, T.

    2014-12-01

    The Bravo Dome field in northeast New Mexico is one of the largest gas accumulations worldwide and the largest natural CO2 accumulation in North America. The field is only 580-900 m deep and located in the Permian Tubb sandstone that unconformably overlies the granitic basement. Sathaye et al. (2014) estimated that 1.3 Gt of CO2 is stored at the reservoir. A major increase in the pore pressure relative to the hydrostatic pressure is expected due to the large amount of CO2 injected into the reservoir. However, the pre-production gas pressures indicate that most parts of the reservoir are approximately 5 MPa below hydrostatic pressure. Three processes could explain the under pressure in the Bravo Dome reservoir; 1) erosional unloading, 2) CO2 dissolution into the ambient brine, 3) cooling of CO2after injection. Analytical solutions suggest that an erosion rate of 180 m/Ma is required to reduce the pore pressures to the values observed at Bravo Dome. Given that the current erosion rate is only 5 m/Ma (Nereson et al. 2013); the sub-hydrostatic pressures at Bravo Dome are likely due to CO2dissolution and cooling. To investigate the impact of CO2 dissolution on the pore pressure we have developed new analytical solutions and conducted laboratory experiments. We assume that gaseous CO2 was confined to sandstones during emplacement due to the high entry pressure of the siltstones. After emplacement the CO2 dissolves in to the brine contained in the siltstones and the pressure in the sandstones declines. Assuming the sandstone-siltstone system is closed, the pressure decline due to CO2 dissolution is controlled by a single dimensionless number, η = KHRTVw /Vg. Herein, KH is Henry's constant, R is ideal gas constant, T is temperature, Vw is water volume, and Vg is CO2 volume. The pressure drop is controlled by the ratio of water volume to CO2 volume and η varies between 0.1 to 8 at Bravo Dome. This corresponds to pressure drops between 0.8-7.5 MPa and can therefore account

  19. [Experimental study. Reduction of pressure in areas of risk of developing pressure ulcers with a hydrocellular dressing].

    PubMed

    Torra i Bou, J E; Rueda López, J; Ramón Cantón, C

    2000-03-01

    The handling of pressure is a basic measure in the prevention and treatment of bed sores. It is possible to reduce and ease pressure by various means including changes in posture, use of special surfaces for handling pressure as well as the use of local applications or external applications which reduce pressure. Today nurses have a large quantity of external applications available to use although only some hydrocellular ones are capable to reduce pressure due to their hydrocellular structure. An experimental study was designed to calculate the level of pressure before and after applying an Allevyn hydrocellular external application in the area of the sacrum, ischium, and heel of three healthy volunteers; first, Volunteer A, a 85 kg. 170 cm man; second, Volunteer B, a 54.3 kg. 159 cm woman; and third, Volunteer C, a 69.4 kg 164 cm man. Measures were taken on two types of surfaces: a viscoelastic foam mattress and a conventional hospital mattress. All measurements were repeated at 0, 30, 45 and 60 degrees of inclination. Pressure was determined by means of a Talley pressure monitor, Oxford Pressure Monitor MK II. A total of 144 pressure reading were taken. The overall average reduction after applying a external hydrocellular application on all volunteers, at all inclinations and on all surfaces for each of the three zones were 19.5% in the sacrum, 13.8% in the ischium and 20.15% in the heel. Even though our study has its limitations, such as young, healthy volunteers, we can establish that the external hydrocellular application studied does have a local reducing effect on pressure. Since every external hydrocellular application has its own specific structure, the results of our study can not be applied with certainty to other external applications inside the hydrocellular group.

  20. Fluid Pressure Variation in a Sedimentary Geothermal Reservoir in the North German Basin: Case Study Groß Schönebeck

    NASA Astrophysics Data System (ADS)

    Huenges, Ernst; Trautwein, Ute; Legarth, Björn; Zimmermann, Günter

    2006-10-01

    The Rotliegend of the North German basin is the target reservoir of an interdisciplinary investigation program to develop a technology for the generation of geothermal electricity from low-enthalpy reservoirs. An in situ downhole laboratory was established in the 4.3 km deep well Groβ Schönebeck with the purpose of developing appropriate stimulation methods to increase permeability of deep aquifers by enhancing or creating secondary porosity and flow paths. The goal is to learn how to enhance the inflow performance of a well from a variety of rock types in low permeable geothermal reservoirs. A change in effective stress due to fluid pressure was observed to be one of the key parameters influencing flow properties both downhole and in laboratory experiments on reservoir rocks. Fluid pressure variation was induced using proppant-gel-frac techniques as well as waterfrac techniques in several different new experiments in the borehole. A pressure step test indicates generation and extension of multiple fractures with closure pressures between 6 and 8.4 MPa above formation pressure. In a 24-hour production test 859 m3 water was produced from depth indicating an increase of productivity in comparison with former tests. Different depth sections and transmissibility values were observed in the borehole depending on fluid pressure. In addition, laboratory experiments were performed on core samples from the sandstone reservoir under uniaxial strain conditions, i.e., no lateral strain, constant axial load. The experiments on the borehole and the laboratory scale were realized on the same rock types under comparable stress conditions with similar pore pressure variations. Nevertheless, stress dependences of permeability are not easy to compare from scale to scale. Laboratory investigations reflect permeability variations due to microstructural heterogeneities and the behavior in the borehole is dominated by the generation of connections to large-scale structural patterns.

  1. Complete Fiber/Copper Cable Solution for Long-Term Temperature and Pressure Measurement in Supercritical Reservoirs and EGS Wells

    SciTech Connect

    Pastouret, Alan; Gooijer, Frans; Overton, Bob; Jonker, Jan; Curley, Jim; Constantine, Walter; Waterman, Kendall Miller

    2015-11-13

    High Temperature insulated wire and optical fiber cable is a key enabling technology for the Geothermal Technologies Program (GTP). Without insulated electrical wires and optical fiber, downhole temperature and pressure sensors, flow meters and gauges cannot communicate with the surface. Unfortunately, there are currently no insulated electrical wire or fiber cable constructions capable of surviving for extended periods of deployment in a geothermal well (240-325°C) or supercritical (374°C) reservoir. This has severely hindered engineered reservoir creation, management and utilization, as hot zones and cool water intrusions cannot be understood over time. The lack of a insulated electrical wire and fiber cable solution is a fundamental limitation to the viability of this energy source. The High Temperature Downhole Tools target specification is development of tools and sensors for logging and monitoring wellbore conditions at depths of up to 10,000 meters and temperatures up to 374oC. It well recognized in the industry that no current electronic or fiber cable can be successfully deployed in a well and function successfully for more a few days at temperatures over 240oC. The goal of this project was to raise this performance level significantly. Prysmian Group’s objective in this project was to develop a complete, multi-purpose cable solution for long-term deployment in geothermal wells/reservoirs that can be used with the widest variety of sensors. In particular, the overall project objective was to produce a manufacturable cable design that can perform without serious degradation: • At temperatures up to 374°C; • At pressures up to 220 bar; • In a hydrogen-rich environment; and • For the life of the well (> 5 years). This cable incorporates: • Specialty optical fibers, with specific glass chemistry and high temperature and pressure protective coatings for data communication and distributed temperature and pressure sensing, and • High

  2. Temperature-pressure conditions in coalbed methane reservoirs of the Black Warrior basin: Implications for carbon sequestration and enhanced coalbed methane recovery

    USGS Publications Warehouse

    Pashin, J.C.; McIntyre, M.R.

    2003-01-01

    Sorption of gas onto coal is sensitive to pressure and temperature, and carbon dioxide can be a potentially volatile supercritical fluid in coalbed methane reservoirs. More than 5000 wells have been drilled in the coalbed methane fields of the Black Warrior basin in west-central Alabama, and the hydrologic and geothermic information from geophysical well logs provides a robust database that can be used to assess the potential for carbon sequestration in coal-bearing strata.Reservoir temperature within the coalbed methane target zone generally ranges from 80 to 125 ??F (27-52 ??C), and geothermal gradient ranges from 6.0 to 19.9 ??F/1000 ft (10.9-36.2 ??C/km). Geothermal gradient data have a strong central tendency about a mean of 9.0 ??F/1000 ft (16.4 ??C/km). Hydrostatic pressure gradients in the coalbed methane fields range from normal (0.43 psi/ft) to extremely underpressured (<0.05 psi/ft). Pressure-depth plots establish a bimodal regime in which 70% of the wells have pressure gradients greater than 0.30 psi/ft, and 20% have pressure gradients lower than 0.10 psi/ft. Pockets of underpressure are developed around deep longwall coal mines and in areas distal to the main hydrologic recharge zone, which is developed in structurally upturned strata along the southeastern margin of the basin.Geothermal gradients within the coalbed methane fields are high enough that reservoirs never cross the gas-liquid condensation line for carbon dioxide. However, reservoirs have potential for supercritical fluid conditions beyond a depth of 2480 ft (756 m) under normally pressured conditions. All target coal beds are subcritically pressured in the northeastern half of the coalbed methane exploration fairway, whereas those same beds were in the supercritical phase window prior to gas production in the southwestern half of the fairway. Although mature reservoirs are dewatered and thus are in the carbon dioxide gas window, supercritical conditions may develop as reservoirs

  3. Critically pressured free-gas reservoirs below gas-hydrate provinces.

    PubMed

    Hornbach, Matthew J; Saffer, Demian M; Holbrook, W Steven

    2004-01-08

    Palaeoceanographic data have been used to suggest that methane hydrates play a significant role in global climate change. The mechanism by which methane is released during periods of global warming is, however, poorly understood. In particular, the size and role of the free-gas zone below gas-hydrate provinces remain relatively unconstrained, largely because the base of the free-gas zone is not a phase boundary and has thus defied systematic description. Here we evaluate the possibility that the maximum thickness of an interconnected free-gas zone is mechanically regulated by valving caused by fault slip in overlying sediments. Our results suggest that a critical gas column exists below most hydrate provinces in basin settings, implying that these provinces are poised for mechanical failure and are therefore highly sensitive to changes in ambient conditions. We estimate that the global free-gas reservoir may contain from one-sixth to two-thirds of the total methane trapped in hydrate. If gas accumulations are critically thick along passive continental slopes, we calculate that a 5 degrees C temperature increase at the sea floor could result in a release of approximately 2,000 Gt of methane from the free-gas zone, offering a mechanism for rapid methane release during global warming events.

  4. Understanding CO2 Plume Behavior and Basin-Scale Pressure Changes during Sequestration Projects through the use of Reservoir Fluid Modeling

    USGS Publications Warehouse

    Leetaru, H.E.; Frailey, S.M.; Damico, J.; Mehnert, E.; Birkholzer, J.; Zhou, Q.; Jordan, P.D.

    2009-01-01

    Large scale geologic sequestration tests are in the planning stages around the world. The liability and safety issues of the migration of CO2 away from the primary injection site and/or reservoir are of significant concerns for these sequestration tests. Reservoir models for simulating single or multi-phase fluid flow are used to understand the migration of CO2 in the subsurface. These models can also help evaluate concerns related to brine migration and basin-scale pressure increases that occur due to the injection of additional fluid volumes into the subsurface. The current paper presents different modeling examples addressing these issues, ranging from simple geometric models to more complex reservoir fluid models with single-site and basin-scale applications. Simple geometric models assuming a homogeneous geologic reservoir and piston-like displacement have been used for understanding pressure changes and fluid migration around each CO2 storage site. These geometric models are useful only as broad approximations because they do not account for the variation in porosity, permeability, asymmetry of the reservoir, and dip of the beds. In addition, these simple models are not capable of predicting the interference between different injection sites within the same reservoir. A more realistic model of CO2 plume behavior can be produced using reservoir fluid models. Reservoir simulation of natural gas storage reservoirs in the Illinois Basin Cambrian-age Mt. Simon Sandstone suggest that reservoir heterogeneity will be an important factor for evaluating storage capacity. The Mt. Simon Sandstone is a thick sandstone that underlies many significant coal fired power plants (emitting at least 1 million tonnes per year) in the midwestern United States including the states of Illinois, Indiana, Kentucky, Michigan, and Ohio. The initial commercial sequestration sites are expected to inject 1 to 2 million tonnes of CO2 per year. Depending on the geologic structure and

  5. Core flooding tests to investigate the effects of IFT reduction and wettability alteration on oil recovery during MEOR process in an Iranian oil reservoir.

    PubMed

    Rabiei, Arash; Sharifinik, Milad; Niazi, Ali; Hashemi, Abdolnabi; Ayatollahi, Shahab

    2013-07-01

    Microbial enhanced oil recovery (MEOR) refers to the process of using bacterial activities for more oil recovery from oil reservoirs mainly by interfacial tension reduction and wettability alteration mechanisms. Investigating the impact of these two mechanisms on enhanced oil recovery during MEOR process is the main objective of this work. Different analytical methods such as oil spreading and surface activity measurements were utilized to screen the biosurfactant-producing bacteria isolated from the brine of a specific oil reservoir located in the southwest of Iran. The isolates identified by 16S rDNA and biochemical analysis as Enterobacter cloacae (Persian Type Culture Collection (PTCC) 1798) and Enterobacter hormaechei (PTCC 1799) produce 1.53 g/l of biosurfactant. The produced biosurfactant caused substantial surface tension reduction of the growth medium and interfacial tension reduction between oil and brine to 31 and 3.2 mN/m from the original value of 72 and 29 mN/m, respectively. A novel set of core flooding tests, including in situ and ex situ scenarios, was designed to explore the potential of the isolated consortium as an agent for MEOR process. Besides, the individual effects of wettability alteration and IFT reduction on oil recovery efficiency by this process were investigated. The results show that the wettability alteration of the reservoir rock toward neutrally wet condition in the course of the adsorption of bacteria cells and biofilm formation are the dominant mechanisms on the improvement of oil recovery efficiency.

  6. A direct method for determining complete positive and negative capillary pressure curves for reservoir rock using the centrifuge

    SciTech Connect

    Spinler, E.A.; Baldwin, B.A.

    1997-08-01

    A method is being developed for direct experimental determination of capillary pressure curves from saturation distributions produced during centrifuging fluids in a rock plug. A free water level is positioned along the length of the plugs to enable simultaneous determination of both positive and negative capillary pressures. Octadecane as the oil phase is solidified by temperature reduction while centrifuging to prevent fluid redistribution upon removal from the centrifuge. The water saturation is then measured via magnetic resonance imaging. The saturation profile within the plug and the calculation of pressures for each point of the saturation profile allows for a complete capillary pressure curve to be determined from one experiment. Centrifuging under oil with a free water level into a 100 percent water saturated plug results in the development of a primary drainage capillary pressure curve. Centrifuging similarly at an initial water saturation in the plug results in the development of an imbibition capillary pressure curve. Examples of these measurements are presented for Berea sandstone and chalk rocks.

  7. Comparison of CO2 trapping in highly heterogeneous reservoirs with Brooks-Corey and van Genuchten type capillary pressure curves

    NASA Astrophysics Data System (ADS)

    Gershenzon, Naum I.; Ritzi, Robert W., Jr.; Dominic, David F.; Mehnert, Edward; Okwen, Roland T.

    2016-10-01

    Geological heterogeneities affect the dynamics of carbon dioxide (CO2) plumes in subsurface environments in important ways. Previously, we showed how the dynamics of CO2 plumes are influenced by the multiscaled sedimentary architecture in deep brine fluvial-type reservoirs. The results confirm that representing small-scale features and the corresponding heterogeneity in saturation functions, along with hysteresis in saturation functions, are all critical to understanding capillary trapping processes. Here, we show that when heterogeneity and hysteresis are represented, the two conventional approaches for defining saturation functions, Brooks-Corey and van Genuchten, represent fundamentally different physical systems. The Brooks-Corey approach represents heterogeneity in entry pressures, and leads to trapping by capillary pinning. The van Genuchten approach represents a network of pores transporting the nonwetting fluid, across rock types, with negligible capillary entry pressure, and leads to capillary retardation. These differences significantly affect the large-scale characteristics of CO2 plumes (i.e., their mass, shape, and position).

  8. Intraocular pressure reduction with a fixed treatment protocol in the Early Manifest Glaucoma Trial.

    PubMed

    Heijl, Anders; Leske, M Cristina; Hyman, Leslie; Yang, Zhongming; Bengtsson, Boel

    2011-12-01

    To evaluate: (i) the relationship between intraocular pressure (IOP) reduction attained with a fixed treatment protocol and the untreated IOP level; (ii) the consistency of IOP reduction over time; and (iii) whether there is a threshold pretreatment IOP level below which IOP reduction might be less effective. Results are based on 128 patients with glaucoma with field defects, who were randomized to the treatment arm of the Early Manifest Glaucoma Trial (EMGT). The EMGT fixed treatment protocol consisted of 360° laser trabeculoplasty and topical betaxolol eye drops B.I.D. Treatment was unchanged as long as progression did not occur. Analyses assessed the initial IOP reduction after 3 months and also the mean reduction based on all follow-up values; IOP changes over time were evaluated with linear regression analysis. Factors influencing initial and mean IOP reduction were also explored using linear models. Mean age at baseline was 68 years, and untreated baseline IOP ranged from 13 to 30.5 mmHg. On average, eyes with higher baseline IOP experienced larger pressure reductions than eyes with lower baseline IOP, whether expressed in mmHg or as percentages. Each mmHg of higher baseline IOP was associated with approximately 0.6 mmHg larger IOP reduction. IOP changed little over time, with 66% of patients changing less than 0.5 mmHg/year, and only 13% (17/128) changing >1.0 mmHg/year. The treatment protocol did not achieve any average IOP reduction in eyes with baseline pressures ≤ 15 mmHg. Factors related to more IOP reduction at 3 months were higher baseline IOP and positive refractive error, while higher baseline IOP and male gender (more reduction) and cardiovascular disease history (less reduction) were associated with mean IOP on treatment. With a fixed treatment protocol, the IOP reduction achieved depended very strongly on baseline untreated IOP levels. There seemed to be a lower threshold around 15 mmHg, where therapy did not result in any reduction of IOP

  9. Fast low-temperature plasma reduction of monolayer graphene oxide at atmospheric pressure

    NASA Astrophysics Data System (ADS)

    Bodik, Michal; Zahoranova, Anna; Micusik, Matej; Bugarova, Nikola; Spitalsky, Zdenko; Omastova, Maria; Majkova, Eva; Jergel, Matej; Siffalovic, Peter

    2017-04-01

    We report on an ultrafast plasma-based graphene oxide reduction method superior to conventional vacuum thermal annealing and/or chemical reduction. The method is based on the effect of non-equilibrium atmospheric-pressure plasma generated by the diffuse coplanar surface barrier discharge in proximity of the graphene oxide layer. As the reduction time is in the order of seconds, the presented method is applicable to the large-scale production of reduced graphene oxide layers. The short reduction times are achieved by the high-volume power density of plasma, which is of the order of 100 W cm-3. Monolayers of graphene oxide on silicon substrate were prepared by a modified Langmuir-Schaefer method and the efficient and rapid reduction by methane and/or hydrogen plasma was demonstrated. The best results were obtained for the graphene oxide reduction in hydrogen plasma, as verified by x-ray photoelectron spectroscopy and Raman spectroscopy.

  10. Fast low-temperature plasma reduction of monolayer graphene oxide at atmospheric pressure.

    PubMed

    Bodik, Michal; Zahoranova, Anna; Micusik, Matej; Bugarova, Nikola; Spitalsky, Zdenko; Omastova, Maria; Majkova, Eva; Jergel, Matej; Siffalovic, Peter

    2017-04-07

    We report on an ultrafast plasma-based graphene oxide reduction method superior to conventional vacuum thermal annealing and/or chemical reduction. The method is based on the effect of non-equilibrium atmospheric-pressure plasma generated by the diffuse coplanar surface barrier discharge in proximity of the graphene oxide layer. As the reduction time is in the order of seconds, the presented method is applicable to the large-scale production of reduced graphene oxide layers. The short reduction times are achieved by the high-volume power density of plasma, which is of the order of 100 W cm(-3). Monolayers of graphene oxide on silicon substrate were prepared by a modified Langmuir-Schaefer method and the efficient and rapid reduction by methane and/or hydrogen plasma was demonstrated. The best results were obtained for the graphene oxide reduction in hydrogen plasma, as verified by x-ray photoelectron spectroscopy and Raman spectroscopy.

  11. Multifunctional Low-Pressure Turbine for Core Noise Reduction, Improved Efficiency, and Nitrogen Oxide (NOx) Reduction

    NASA Technical Reports Server (NTRS)

    Miller, Christopher J.; Shyam, Vikram; Rigby, David L.

    2013-01-01

    This work studied the feasibility of using Helmholtz resonator cavities embedded in low-pressure-turbine (LPT) airfoils to (1) reduce core noise by damping acoustic modes; (2) use the synthetic jets produced by the liner hole acoustic oscillations to improve engine efficiency by maintaining turbulent attached flow in the LPT at low-Reynolds-number cruise conditions; and (3) reduce engine nitrogen oxide emissions by lining the internal cavities with materials capable of catalytic conversion. Flat plates with embedded Helmholtz resonators, designed to resonate at either 3000 or at 400 Hz, were simulated using computational fluid dynamics. The simulations were conducted for two inlet Mach numbers, 0.25 and 0.5, corresponding to Reynolds numbers of 90 000 and 164 000 based on the effective chordwise distance to the resonator orifice. The results of this study are (1) the region of acoustic treatment may be large enough to have a benefit; (2) the jets may not possess sufficient strength to reduce flow separation (based on prior work by researchers in the flow control area); and (3) the additional catalytic surface area is not exposed to a high velocity, so it probably does not have any benefit.

  12. [Reduction of plantar peak pressure by limiting stride length in diabetic patients].

    PubMed

    Drerup, B; Kolling, Ch; Koller, A; Wetz, H H

    2004-09-01

    Plantar peak pressure is a diagnostically significant parameter for the evaluation of the risk of foot ulceration in patients with diabetic neuropathy. The prophylaxis and therapy of the diabetic foot therefore is to a large extent oriented on peak pressure, and is aimed at an extensive reduction in this parameter. This is mainly accomplished with protective footwear including shoe modifications and cushioning. In comparison, other approaches affecting the loading and motion pattern of the patient are of minor importance--as for example control of gait pattern. In this study we examined shortening of stride length as a possible measure in reducing plantar peak pressure during gait. In 17 diabetic patients without acute foot ulcerations, stride length was reduced to 33% of leg length using an elastic hobble. This led to a reduction in stride length of 23%. At the same time, the walking speed was significantly reduced by 27% and the cadence by 5.7%. As a consequence, the peak pressure was reduced in nearly all regions of the foot--except the small toes. In the metatarsal region peak pressure is reduced by 14.5%. Thus, a reduction in stride length offers the possibility of reducing plantar peak pressure as a supplementary measure in addition to orthopaedic footwear. However, at present clinical feasibility has not yet been established.

  13. Oxygen and sulfur isotope fractionation during methane dependent sulfate reduction in high pressure continuous incubation studies

    NASA Astrophysics Data System (ADS)

    Deusner, C.; Brunner, B.; Holler, T.; Widdel, F.; Ferdelman, T. G.

    2009-12-01

    The anaerobic oxidation of methane (AOM) coupled to sulfate reduction in marine sediments is an important sink in the global methane budget. However, many aspects of methane dependent sulfate reduction are not fully understood. We developed a novel high pressure biotechnical system to simulate marine conditions with high concentrations of dissolved gases, e.g. at gas seeps and gas hydrate systems. The system allows for batch, fed-batch and continuous gas-phase free incubation. We employ this system to study the kinetics and isotope fractionation during AOM at varying methane partial pressures up to 10 MPa. We present the results of long-term continuous and fed-batch incubations with highly active naturally enriched biomass from microbial mats from the Black Sea. During these experiments the methane partial pressure was increased stepwise from 0.1 to 10 MPa. The methane dependent sulfate reduction rate increased from 0.1 mmol/l/d to 3.5 mmol/l/d resulting from the increase in methane concentration and microbial growth. Sulfate reduction was negligible in the absence of methane. The sulfur and oxygen isotope fractionation during sulfate reduction was strongly influenced by the concentration of dissolved methane. Sulfur isotope fractionation was highest at low methane concentrations, and lowest at high methane concentrations. Relative to sulfate reduction rates, oxygen isotope exchange between sulfate and water was highest at low methane concentrations, and lowest at high methane concentrations.

  14. Hyperbaric reservoir fluids: High-pressure phase behavior of asymmetric methane + n-alkane systems

    NASA Astrophysics Data System (ADS)

    Flöten, E.; de Loos, Th. W.; de Swaan Arons, J.

    1995-01-01

    In this paper, experimental three-phase equilibrium (solid n-alkane + liquid + vapor) data for binary methane + n-alkane systems are presented. For the binary system methane + tetracosane, the three-phase curve was determined based on two phase equilibrium measurements in a composition range from x c24 = 0.0027 to x c24 = 1.0. The second critical endpoint of this system was found at p = (1114.7 ± 0.5) M Pa. T = (322.6 ± 0.25) K, and a mole fraction of tetracosane in the critical fluidphase of x c24 = 0.0415 ± 0.0015. The second critical endpoint occurs where solid tetracosane is in equilibrium with a critical fluid phase ( S c24 + L = V). For the binary systems of methane with the n-alkanes tetradecane, triacontane, tetracontane, and pentacontane, only the coordinates of the second critical endpoints were measured. The second critical endpoint temperature is found close to the atmospheric melting point temperature of the n-alkane. The pressures at the second critical endpoints do not exceed 200 MPa. Based on these experimental data and data from the literature, correlations for the pressure. temperature, and fluid phase composition at the second critical endpoint of binary methane + n-alkane systems with n-alkanes between octane and pentacontane were developed.

  15. Effect of the Reservoir Volume on the Discharge Pressures in the Injection System of the N.A.C.A. Spray Photography Equipment

    NASA Technical Reports Server (NTRS)

    Rothrock, A M; Lee, D W

    1932-01-01

    Tests were made to determine the effect of the reservoir volume on the discharge pressures in the injection system of the N.A.C.A. spray photography equipment. The data obtained are applicable to the design of a common rail fuel-injection system. The data show that an injection system of the type described can be designed so that not more than full load fuel quantity can be injected into the engine cylinders, and so that the fuel spray characteristics remain constant over a large range of engine speeds. Formulas are presented for computing the volume of the reservoir and the diameter of the discharge orifice.

  16. Underwater plasma-MIG arc welding: Shielding technique and pressure reduction by a centrifugal pump

    SciTech Connect

    Creutz, M.; Mewes, D.; Bartzsch, J.; Draugelates, U.

    1995-12-31

    In comparison to hyperbaric underwater welding in diving chambers, wet welding techniques promise higher flexibility and lower costs. One technique for creating a local dry and pressure reduced welding zone is the use of a centrifugal pump. Results of experimental investigations in combination with a plasma-MIG arc welding system are presented in this paper. Special importance is attached to the local pressure reduction in view of the fact that low pressure, i.e. a high pressure difference between surrounding water and dry welding area, is a good condition for welding but is difficult to be obtained with other shielding systems than pressure chambers. Plasma-MIG welding has been done under water with a good result on the weld quality. Values of the hardness of the joint and the appearance of the weld structure are nearly comparable to atmospheric welds.

  17. Augmentation pressure is influenced by ventricular contractility/relaxation dynamics: novel mechanism of reduction of pulse pressure by nitrates.

    PubMed

    Fok, Henry; Guilcher, Antoine; Li, Ye; Brett, Sally; Shah, Ajay; Clapp, Brian; Chowienczyk, Phil

    2014-05-01

    Augmentation pressure (AP), the increment in aortic pressure above its first systolic shoulder, is thought to be determined mainly by pressure wave reflection but could be influenced by ventricular ejection characteristics. We sought to determine the mechanism by which AP is selectively reduced by nitroglycerin (NTG). Simultaneous measurements of aortic pressure and flow were made at the time of cardiac catheterization in 30 subjects (11 women; age, 61±13 years [mean±SD]) to perform wave intensity analysis and calculate forward and backward components of AP generated by the ventricle and arterial tree, respectively. Measurements were made at baseline and after NTG given systemically (800 μg sublingually, n=20) and locally by intracoronary infusion (1 μg/min; n=10). Systemic NTG had no significant effect on first shoulder pressure but reduced augmentation (and central pulse pressure) by 12.8±3.1 mm Hg (P<0.0001). This resulted from a reduction in forward and backward wave components of AP by 7.0±2.4 and 5.8±1.3 mm Hg, respectively (each P<0.02). NTG had no significant effect on the ratio of amplitudes of either backward/forward waves or backward/forward compression wave energies, suggesting that effects on the backward wave were largely secondary to those on the forward wave. Time to the forward expansion wave was reduced (P<0.05). Intracoronary NTG decreased AP by 8.3±3.6 mm Hg (P<0.05) with no significant effect on the backward wave. NTG reduces AP and central pulse pressure by a mechanism that is, at least in part, independent of arterial reflections and relates to ventricular contraction/relaxation dynamics with enhanced myocardial relaxation.

  18. Iron reduction and mineralization of deep-sea iron reducing bacterium Shewanella piezotolerans WP3 at elevated hydrostatic pressures.

    PubMed

    Wu, W F; Wang, F P; Li, J H; Yang, X W; Xiao, X; Pan, Y X

    2013-11-01

    In this study, iron reduction and concomitant biomineralization of a deep-sea iron reducing bacterium (IRB), Shewanella piezotolerans WP3, were systematically examined at different hydrostatic pressures (0.1, 5, 20, and 50 MPa). Our results indicate that bacterial iron reduction and induced biomineralization are influenced by hydrostatic pressure. Specifically, the iron reduction rate and extent consistently decreases with the increase in hydrostatic pressure. By extrapolation, the iron reduction rate should drop to zero by ~68 MPa, which suggests a possible shut-off of enzymatic iron reduction of WP3 at this pressure. Nano-sized superparamagnetic magnetite minerals are formed under all the experimental pressures; nevertheless, even as magnetite production decreases, the crystallinity and grain size of magnetite minerals increase at higher pressure. These results imply that IRB may play an important role in iron reduction, biomineralization, and biogeochemical cycling in deep-sea environments.

  19. Reduction of titanium dioxide to metallic titanium conducted under the autogenic pressure of the reactants.

    PubMed

    Eshed, Michal; Irzh, Alexander; Gedanken, Aharon

    2009-08-03

    We report on a reaction to convert titanium dioxide to titanium. The reduction reaction was done under the autogenic pressure of the reactants at 750 degrees C for 5 h. The MgO, a by-product, was removed by acids to obtain pure metallic titanium.

  20. Natriuresis and blood pressure reduction in hypertensive patients with diabetes mellitus: the NESTOR study.

    PubMed

    Zhang, Yi; Agnoletti, Davide; Wang, Ji-Guang; Xu, Yawei; Safar, Michel E

    2015-01-01

    The antihypertensive effect of indapamide has never been clearly understood, particularly in hypertensive patients with diabetes mellitus. A total of 565 patients were randomly selected to receive either indapamide 1.5 mg or enalapril 10 mg daily for 12 months. Brachial blood pressure (BP) and plasma and urinary electrolytes were measured at baseline and at the end of follow-up. Sodium and potassium levels and excretion rates were measured in overnight urine collections. After 12 months' treatment, similar significant reductions were observed in systolic and diastolic BP and pulse pressure levels in both treatment arms (P < .001). However, age, body mass index, diabetes duration, and plasma sodium reductions were shown to be major, independent factors influencing BP reduction with indapamide, but not with enalapril. Regression coefficients were positive for age and plasma sodium reductions (P ≤ .009) but negative for body mass index and diabetes duration (P ≤ .008). Similar findings were observed for pulse pressure. These results were more notable in elderly patients, did not differ regardless of whether BP reduction was measured in absolute or percent values, and were associated with increased sodium and potassium excretion rates.Indapamide is more effective than enalapril at reducing BP in elderly diabetic hypertensives with marked sodium retention.

  1. Right ventricular coronary blood flow patterns during aortic pressure reduction in renal hypertensive dogs.

    PubMed

    Smolich, J J; Weissberg, P L; Friberg, P; Korner, P I

    1991-04-01

    We measured right ventricular coronary blood flow with radioactive microspheres during graded aortic pressure reduction in 13 normal dogs and in 13 renal hypertensive dogs with left ventricular hypertrophy. Under anaesthesia and controlled loading conditions, mean aortic pressure was lowered from control (128 mmHg in normal and 146 mmHg in hypertensive dogs) to approximately 100, 90 and 80 mmHg. In normal dogs, right ventricular blood flow was not affected by this pressure reduction, consistent with effective right ventricular autoregulation. In hypertensive dogs, however, right ventricular blood flow was maintained between a mean aortic pressure of 146 and 90 mmHg (range 75-79 ml min(-1) 100 g(-1] but fell by 18% to 63 ml min 100 g(-1) at a mean aortic pressure of 80 mmHg (P less than 0.005). We conclude that autoregulation of right ventricular blood flow was preserved in chronic hypertension but that, compared to normal dogs, the lower limit of autoregulation was reset to a higher pressure level. Moreover, the similarity of right ventricular-to-body weight ratios in the two groups implied that this change was a consequence of hypertension-induced structural changes in the coronary vasculature.

  2. Operation of a Pressurized System for Continuous Reduction of CO2

    SciTech Connect

    Eric J. Dufek; Tedd E. Lister; Simon Stone; Michael E. McIlwain

    2012-09-01

    A Ag-based pressurized electrochemical system equipped for continuous reduction of CO2 is presented. At elevated pressures the quantity of CO which can be generated is 5 times that observed at ambient pressure with faradaic efficiencies as high as 92% observed at 350 mA cm-2. For operation at 225 mA cm-2 and 60 degrees C the cell voltage at 18.5 atm was 0.4 V below that observed at ambient pressure. Increasing the temperature further to 90 degrees C led to a cell voltage below 3 V (18.5 atm and 90 degrees C), which equates to an electrical efficiency of 50%.

  3. Pressure-vessel-damage fluence reduction by low-leakage fuel management. [PWR

    SciTech Connect

    Cokinos, D.; Aronson, A.L.; Carew, J.F.; Kohut, P.; Todosow, M.; Lois, L.

    1983-01-01

    As a result of neutron-induced radiation damage to the pressure vessel and of an increased concern that in a PWR transient the pressure vessel may be subjected to pressurized thermal shock (PTS), detailed analyses have been undertaken to determine the levels of neutron fluence accumulation at the pressure vessels of selected PWR's. In addition, various methods intended to limit vessel damage by reducing the vessel fluence have been investigated. This paper presents results of the fluence analysis and the evaluation of the low-leakage fuel management fluence reduction method. The calculations were performed with DOT-3.5 in an octant of the core/shield/vessel configuration using a 120 x 43 (r, theta) mesh structure.

  4. Quantifying the Reduction Intensity of Handaxes with 3D Technology: A Pilot Study on Handaxes in the Danjiangkou Reservoir Region, Central China

    PubMed Central

    Li, Hao; Kuman, Kathleen; Li, Chaorong

    2015-01-01

    This paper presents an approach to analyzing the reduction intensity of handaxes with the aid of 3D scanning technology. Two quantitative reduction indices, the Scar Density Index (SDI) and the Flaked Area Index (FAI), are applied to handaxes from the third terrace of the Danjiangkou Reservoir Region (DRR), central China, dated to the Middle Pleistocene. The results show that most of the DRR handaxes in this sample show moderate reduction, which also reflects a least-effort reduction strategy and a generally short use-life for these tools. Detailed examination of the DRR handaxes by sector reveals that the tips generally show the most reduction, while the bases show the least shaping, with cortex often preserved on the base to facilitate handling. While western Acheulean assemblages in this regard are variable, there are many examples of handaxes of varying age with trimming of the bases. We also found no significant differences in the levels of reduction between the two main raw materials, quartz phyllite and trachyte. However, the type of blank used (large flakes versus cobbles) and the type of shaping (bifacial, partly bifacial and unifacial) do play a significant role in the reduction intensity of the DRR handaxes. Finally, a small number of handaxes from the younger (the early Late Pleistocene) second terrace of the DRR was compared with those from the third terrace. The results indicate that there is no technological change in the reduction intensity through time in these two DRR terraces. PMID:26331954

  5. Quantifying the Reduction Intensity of Handaxes with 3D Technology: A Pilot Study on Handaxes in the Danjiangkou Reservoir Region, Central China.

    PubMed

    Li, Hao; Kuman, Kathleen; Li, Chaorong

    2015-01-01

    This paper presents an approach to analyzing the reduction intensity of handaxes with the aid of 3D scanning technology. Two quantitative reduction indices, the Scar Density Index (SDI) and the Flaked Area Index (FAI), are applied to handaxes from the third terrace of the Danjiangkou Reservoir Region (DRR), central China, dated to the Middle Pleistocene. The results show that most of the DRR handaxes in this sample show moderate reduction, which also reflects a least-effort reduction strategy and a generally short use-life for these tools. Detailed examination of the DRR handaxes by sector reveals that the tips generally show the most reduction, while the bases show the least shaping, with cortex often preserved on the base to facilitate handling. While western Acheulean assemblages in this regard are variable, there are many examples of handaxes of varying age with trimming of the bases. We also found no significant differences in the levels of reduction between the two main raw materials, quartz phyllite and trachyte. However, the type of blank used (large flakes versus cobbles) and the type of shaping (bifacial, partly bifacial and unifacial) do play a significant role in the reduction intensity of the DRR handaxes. Finally, a small number of handaxes from the younger (the early Late Pleistocene) second terrace of the DRR was compared with those from the third terrace. The results indicate that there is no technological change in the reduction intensity through time in these two DRR terraces.

  6. Pressure drop reduction and heat transfer deterioration of slush nitrogen in triangular and circular pipe flows

    NASA Astrophysics Data System (ADS)

    Ohira, Katsuhide; Kurose, Kizuku; Okuyama, Jun; Saito, Yutaro; Takahashi, Koichi

    2017-01-01

    Slush fluids such as slush hydrogen and slush nitrogen are characterized by superior properties as functional thermal fluids due to their density and heat of fusion. In addition to allowing efficient hydrogen transport and storage, slush hydrogen can serve as a refrigerant for high-temperature superconducting (HTS) equipment using MgB2, with the potential for synergistic effects. In this study, pressure drop reduction and heat transfer deterioration experiments were performed on slush nitrogen flowing in a horizontal triangular pipe with sides of 20 mm under the conditions of three different cross-sectional orientations. Experimental conditions consisted of flow velocity (0.3-4.2 m/s), solid fraction (0-25 wt.%), and heat flux (0, 10, and 20 kW/m2). Pressure drop reduction became apparent at flow velocities exceeding about 1.3-1.8 m/s, representing a maximum amount of reduction of 16-19% in comparison with liquid nitrogen, regardless of heating. Heat transfer deterioration was seen at flow velocities of over 1.2-1.8 m/s, for a maximum amount of deterioration of 13-16%. The authors of the current study compared the results for pressure drop reduction and heat transfer deterioration in triangular pipe with those obtained previously for circular and square pipes, clarifying differences in flow and heat transfer properties. Also, a correlation equation was obtained between the slush Reynolds number and the pipe friction factor, which is important in the estimation of pressure drop in unheated triangular pipe. Furthermore, a second correlation equation was derived between the modified slush Reynolds number and the pipe friction factor, enabling the integrated prediction of pressure drop in both unheated triangular and circular pipes.

  7. Potential Biomarker Peptides Associated with Acute Alcohol-Induced Reduction of Blood Pressure

    PubMed Central

    Wakabayashi, Ichiro; Marumo, Mikio; Nonaka, Daisuke; Shimomura, Tomoko; Eguchi, Ryoji; Lee, Lyang-Ja; Tanaka, Kenji; Hatake, Katsuhiko

    2016-01-01

    The purpose of this study was to explore the peptides that are related to acute reduction of blood pressure after alcohol drinking. Venous blood was collected from male healthy volunteers before and after drinking white wine (3 ml/kg weight) containing 13% of ethanol. Peptidome analysis for serum samples was performed using a new target plate, BLOTCHIP®. Alcohol caused significant decreases in systolic and diastolic blood pressure levels at 45 min. The peptidome analysis showed that the levels of three peptides of m/z 1467, 2380 and 2662 changed significantly after drinking. The m/z 1467 and 2662 peptides were identified to be fragments of fibrinogen alpha chain, and the m/z 2380 peptide was identified to be a fragment of complement C4. The intensities of the m/z 2380 and m/z 1467 peptides before drinking were associated with % decreases in systolic and diastolic blood pressure levels at 45 min after drinking compared with the levels before drinking, while there were no significant correlations between the intensity of the m/z 2662 peptide and % decreases in systolic and diastolic blood pressure levels after drinking. The m/z 1467 and 2380 peptides are suggested to be markers for acute reduction of blood pressure after drinking alcohol. PMID:26815288

  8. Negative pressure pulmonary edema after nasal fracture reduction in an obese female patient: a case report

    PubMed Central

    Choi, Eunkyung; Yi, Junggu; Jeon, Younghoon

    2015-01-01

    Postoperative negative pressure pulmonary edema (NPPE) is a rare, but well-known life-threatening complication of acute upper airway obstruction (UAO) which develops after general anesthesia. The pronounced inspiratory efforts following UAO lead to excessive negative inspiratory pressure, which may cause acute pulmonary edema. Early recognition and prompt treatment of NPPE is necessary to prevent patient morbidity and mortality. In addition, the physician should carefully manage the patient who has risk factors of UAO to prevent this situation. We experienced a case of NPPE following laryngospasm after tracheal extubation in an obese patient who underwent open reduction of orbital wall and nasal bone surgery. PMID:26316826

  9. Controlling Eutrophication in A Mediterranean Shallow Reservoir by Phosphorus Loading Reduction: The Need for an Integrated Management Approach.

    PubMed

    Zaragüeta, Mikel; Acebes, Pablo

    2017-04-01

    Increased nutrient enrichment in Mediterranean standing waters has enhanced the risk of being affected by cyanobacterial blooms. Because phosphorus abatement is shaped as a crucial strategy for controlling eutrophication, this study introduces a structural thinking, experiential learning laboratory with animation dynamic model elaborated for Cazalegas Reservoir (Spain) to assess the feasibility of implementing a set of internal and external control measures and hydromorphological adjustments to meet the goal of oligotrophication. This shallow reservoir is another case where recurrent eutrophication has led to reach annual mean total phosphorus concentrations (0.16 ± 0.08 mg total phosphorus/L) over the threshold of current water policies, triggering cyanobacterial growth up to undesirable levels in summer time (approximately 50,000 cells/mL). Modeling results showed that (i) after upgrading water treatment in the main tributary, (ii) applying a lanthanum-modified bentonite into the water column and sediment, and (iii) increasing reservoir water level, in-lake P concentrations and cyanobacterial abundance decreased in an 88% (below 0.01 mg total phosphorus/L) and 84% (below 6000 cells/mL), respectively in the most critical periods. However, the constraints of the proposed management strategies are associated with their costs of implementation and the time span for a stable trophic recovery of the reservoir. In that end, integrated management approaches are aimed to be adopted by water managers to reach adequate ecological status of freshwater bodies.

  10. Controlling Eutrophication in A Mediterranean Shallow Reservoir by Phosphorus Loading Reduction: The Need for an Integrated Management Approach

    NASA Astrophysics Data System (ADS)

    Zaragüeta, Mikel; Acebes, Pablo

    2017-04-01

    Increased nutrient enrichment in Mediterranean standing waters has enhanced the risk of being affected by cyanobacterial blooms. Because phosphorus abatement is shaped as a crucial strategy for controlling eutrophication, this study introduces a structural thinking, experiential learning laboratory with animation dynamic model elaborated for Cazalegas Reservoir (Spain) to assess the feasibility of implementing a set of internal and external control measures and hydromorphological adjustments to meet the goal of oligotrophication. This shallow reservoir is another case where recurrent eutrophication has led to reach annual mean total phosphorus concentrations (0.16 ± 0.08 mg total phosphorus/L) over the threshold of current water policies, triggering cyanobacterial growth up to undesirable levels in summer time (approximately 50,000 cells/mL). Modeling results showed that (i) after upgrading water treatment in the main tributary, (ii) applying a lanthanum-modified bentonite into the water column and sediment, and (iii) increasing reservoir water level, in-lake P concentrations and cyanobacterial abundance decreased in an 88% (below 0.01 mg total phosphorus/L) and 84% (below 6000 cells/mL), respectively in the most critical periods. However, the constraints of the proposed management strategies are associated with their costs of implementation and the time span for a stable trophic recovery of the reservoir. In that end, integrated management approaches are aimed to be adopted by water managers to reach adequate ecological status of freshwater bodies.

  11. Differences in mechanisms between weight loss-sensitive and -resistant blood pressure reduction in obese subjects.

    PubMed

    Masuo, K; Mikami, H; Ogihara, T; Tuck, M L

    2001-07-01

    This study was conducted to clarify the mechanisms involved in the sensitivity for blood pressure (BP) reduction in response to weight loss. In particular, we focused on the contributions of sympathetic nervous system activity and fasting plasma leptin and insulin levels to BP levels during weight loss in obese subjects with weight loss-sensitive and -resistant BP reduction. Sixty-one young, obese untreated hypertensive men (HT) and 52 obese normotensive men (NT) were enrolled in a weight loss program consisting of a low caloric diet and aerobic exercise over a 24-week period. At entry and at week 24, body mass index (BMI), BP, plasma norepinephrine (NE), leptin and insulin were measured. Successful weight loss and BP reduction were respectively defined as a more than a 10% reduction in BMI or mean BP from baseline at week 24. More than 60% of subjects in either group successfully achieved weight loss by this definition. The percentage of subjects who successfully achieved BP reduction was higher (64%) among those subjects who achieved weight loss than among those who did not (22%). Plasma NE level at entry in subjects who failed to achieve BP reduction despite weight loss was significantly higher than that in subjects who succeeded in BP reduction. Plasma leptin and insulin levels were similar between subjects with and without BP reduction. In addition, the absolute decrement and percent decrement in plasma NE in subjects who succeeded in BP reduction were significantly greater than those in subjects who failed to reduce their BP. Absolute and percent decrements in plasma leptin and insulin were similar in both groups. These results suggest that individuals who are resistant to weight loss-induced BP reduction have more sympathetic overactivity both at the outset of and during weight loss.

  12. Acquisition and reduction of blade-mounted pressure transducer data from a Low Aspect Ratio Fan

    NASA Astrophysics Data System (ADS)

    Russler, Patrick M.

    1995-02-01

    This report details the acquisition and reduction of blade-mounted, high-response, pressure transducer data. These data were acquired during the Augmented Damping of Low Aspect Ratio Fans (ADLARF) test conducted at the Compressor Research Facility (CRF) located at Wright-Patterson A.F.B. , Ohio. This report, which is exclusively concerned with the acquisition and digitizing of the blade-mounted data, is intended to compliment other related reports by documenting the data acquisition and reduction procedures. The primary goal of this work is to detail the methodology by which unsteady blade forces and momentum can he determined using blade-mounted pressure transducer data. The secondary goal is to use these data to show how inlet distortion and resulting unsteady forces affect the blade resonance of high-speed fans. By achieving the primary goal in this report, it is hoped that the secondary goal can be better achieved using data from future tests.

  13. Pressure-drop Reduction and Heat-transfer Deterioration of Slush Nitrogen in Square Pipe flow

    NASA Astrophysics Data System (ADS)

    Ohira, Katsuhide; Nakagomi, Kei; Takahashi, Koichi; Aoki, Itsuo

    Pressure drop and heat transfer tests were carried out using slush nitrogen flowing in a horizontal square pipe at flow velocity between 1.0 and 4.9 m/s, with a mass solid fraction between 6 and 26 wt.%, and with heat fluxes of 0, 10 and 20 kW/m2. Pressure drop reduction became apparent at flow velocity of 2.5 m/s and over, with the maximum amount of reduction being 12% in comparison with liquid nitrogen, regardless of heating, while heat transfer deterioration became apparent at flow velocity of 1.0 m/s and over, with the maximum amount of deterioration being 16 and 21% at 10 and 20 kW/m2, respectively.

  14. Pressure-overload-induced heart failure induces a selective reduction in glucose oxidation at physiological afterload.

    PubMed

    Zhabyeyev, Pavel; Gandhi, Manoj; Mori, Jun; Basu, Ratnadeep; Kassiri, Zamaneh; Clanachan, Alexander; Lopaschuk, Gary D; Oudit, Gavin Y

    2013-03-15

    Development of heart failure is known to be associated with changes in energy substrate metabolism. Information on the changes in energy substrate metabolism that occur in heart failure is limited and results vary depending on the methods employed. Our aim is to characterize the changes in energy substrate metabolism associated with pressure overload and ischaemia-reperfusion (I/R) injury. We used transverse aortic constriction (TAC) in mice to induce pressure overload-induced heart failure. Metabolic rates were measured in isolated working hearts perfused at physiological afterload (80 mmHg) using (3)H- or (14)C-labelled substrates. As a result of pressure-overload injury, murine hearts exhibited: (i) hypertrophy, systolic, and diastolic dysfunctions; (ii) reduction in LV work, (iii) reduced rates of glucose and lactate oxidations, with no change in glycolysis or fatty acid oxidation and a small decrease in triacylglycerol oxidation, and (iv) increased phosphorylation of AMPK and a reduction in malonyl-CoA levels. Sham hearts produced more acetyl CoA from carbohydrates than from fats, whereas TAC hearts showed a reverse trend. I/R in sham group produced a metabolic switch analogous to the TAC-induced shift to fatty acid oxidation, whereas I/R in TAC hearts greatly exacerbated the existing imbalance, and was associated with a poorer recovery during reperfusion. Pressure overload-induced heart failure and I/R shift the preference of substrate oxidation from glucose and lactate to fatty acid due to a selective reduction in carbohydrate oxidation. Normalizing the balance between metabolic substrate utilization may alleviate pressure-overload-induced heart failure and ischaemia.

  15. Atomic-scale observation of pressure-dependent reduction dynamics of W18O49 nanowires using environmental TEM.

    PubMed

    Zhang, Zhengfei; Sheng, Liping; Chen, Lu; Zhang, Ze; Wang, Yong

    2017-06-28

    The real-time observation of structural evolution of materials can provide critical information for understanding their reduction mechanisms under different environments. Herein, we report the atomic-scale observation of the reduction dynamics of W18O49 nanowires (NWs) using environmental transmission electron microscopy. Intriguingly, the reduction pathway is found to be affected by oxygen pressure. Under high oxygen pressure (∼0.095 Pa), a W18O49 NW epitaxially transforms into a WO2 NW via mass transport across the interface between (010)W18O49 and (101)WO2. While under low oxygen pressure (∼0.0004 Pa), the transformation follows the sequence of W18O49(NW) → WO2(NW) → β-W(nanoparticles), which is identified as a new reduction pathway. These findings reveal the pressure-dependent reduction and a new transformation pathway, and extend our current understanding of the reduction dynamics of metal oxides.

  16. Stress reduction in sputter deposited films using nanostructured compliant layers by high working-gas pressures

    NASA Astrophysics Data System (ADS)

    Karabacak, Tansel; Senkevich, Jay. J.; Wang, Gwo-Ching; Lu, Toh-Ming

    2005-07-01

    We present a strategy of stress reduction in sputter deposited films by a nano-compliant layer at the substrate using physically self-assembled nanostructures obtained at high working-gas pressures prior to the deposition of a continuous film. This technique is all in situ, and the nanostructures are made of the same material as the deposited thin film and requires no lithography process. This nanostructured layer has a lower material density and can act as a compliant layer to reduce the stress of the subsequently deposited continuous film grown under low gas pressure. By using this approach we were able to reduce stress values significantly in sputter deposited tungsten films and the strategy of alternating high and low Ar gas pressures leads to the growth of much thicker films without delamination.

  17. Aortic pressure reduction redistributes transmural blood flow in dog left ventricle

    SciTech Connect

    Smolich, J.J.; Weissberg, P.L.; Broughton, A.; Korner, P.I. )

    1988-02-01

    The authors studied the effect of graded aortic blood pressure reduction on left ventricular (LV) blood flow in anesthetized, autonomically blocked, open-chest dogs at constant heart rate and mean left atrial pressure. Aortic diastolic pressure (ADP) was lowered from rest to 90, 75, and 60 mmHg with an arteriovenous fistula. Global and regional LV blood flow was measured with radioactive microspheres. Mean LV blood flow fell stepwise from 145 ml {center dot} min{sup {minus}1} {center dot} 100 g{sup {minus}1} at rest to 116 ml {center dot} min{sup {minus}1} {center dot} 100 g{sup {minus}1} at ADP of 60 mmHg, whereas the endocardial-to-epicardial flow ratio decreased from 1.20 to 084. The transmural redistribution of LV blood flow was not accompanied by increases in LV oxygen extraction, depression of LV contractility, LV dilatation or LV electrical dysfunction and also occurred in the presence of considerable coronary vasodilator flow reserve. Electrical evidence of subendocardial ischemia appeared at ADP of 32 mmHg and an endocardial-to-epicardial flow ratio of 0.41 in a subgroup of animals. They conclude that the redistribution of LV flow during moderate aortic pressure reduction was an appropriate physiological adjustment to uneven transmural alterations in regional LV wall stress and that it preceded a more pronounced redistribution evident with myocardial ischemia.

  18. Thermal conductivity reduction of crystalline silicon by high-pressure torsion.

    PubMed

    Harish, Sivasankaran; Tabara, Mitsuru; Ikoma, Yoshifumi; Horita, Zenji; Takata, Yasuyuki; Cahill, David G; Kohno, Masamichi

    2014-01-01

    We report a dramatic and irreversible reduction in the lattice thermal conductivity of bulk crystalline silicon when subjected to intense plastic strain under a pressure of 24 GPa using high-pressure torsion (HPT). Thermal conductivity of the HPT-processed samples were measured using picosecond time domain thermoreflectance. Thermal conductivity measurements show that the HPT-processed samples have a lattice thermal conductivity reduction by a factor of approximately 20 (from intrinsic single crystalline value of 142 Wm(-1) K(-1) to approximately 7.6 Wm(-1) K(-1)). Thermal conductivity reduction in HPT-processed silicon is attributed to the formation of nanograin boundaries and metastable Si-III/XII phases which act as phonon scattering sites, and because of a large density of lattice defects introduced by HPT processing. Annealing the samples at 873 K increases the thermal conductivity due to the reduction in the density of secondary phases and lattice defects.

  19. Force reduction induced by unidirectional transversal muscle loading is independent of local pressure.

    PubMed

    Siebert, Tobias; Rode, Christian; Till, Olaf; Stutzig, Norman; Blickhan, Reinhard

    2016-05-03

    Transversal unidirectional compression applied to muscles via external loading affects muscle contraction dynamics in the longitudinal direction. A recent study reported decreasing longitudinal muscle forces with increasing transversal load applied with a constant contact area (i.e., leading to a simultaneous increase in local pressure). To shed light on these results, we examine whether the decrease in longitudinal force depends on the load, the local pressure, or both. To this end, we perform isometric experiments on rat M. gastrocnemius medialis without and with transversal loading (i) changing the local pressure from 1.1-3.2Ncm(-2) (n=9) at a constant transversal load (1.62N) and (ii) increasing the transversal load (1.15-3.45N) at a constant local pressure of 2.3Ncm(-2) (n=7). While we did not note changes in the decrease in longitudinal muscle force in the first experiment, the second experiment resulted in an almost-linear reduction of longitudinal force between 7.5±0.6% and 14.1±1.7%. We conclude that the observed longitudinal force reduction is not induced by local effects such as malfunction of single muscle compartments, but that similar internal stress conditions and myofilament configurations occur when the local pressure changes given a constant load. The decreased longitudinal force may be explained by increased internal pressure and a deformed myofilament lattice that is likely associated with the decomposition of cross-bridge forces on the one hand and the inhibition of cross-bridges on the other hand. Copyright © 2016 Elsevier Ltd. All rights reserved.

  20. Capillary pressure - saturation relations for supercritical CO2 and brine: Implications for capillary/residual trapping in carbonate reservoirs during geologic carbon sequestration

    NASA Astrophysics Data System (ADS)

    Wang, S.; Tokunaga, T. K.

    2014-12-01

    In geologic carbon sequestration (GCS), data on capillary pressure (Pc) - saturation (Sw) relations are routinely needed to appraise reservoir processes. Capillarity and its hysteresis have been often experimentally studied in oil-water, gas-water and three phase gas-oil-water systems, but fewer works have been reported on scCO2-water under in-situ reservoir conditions. Here, Pc-Sw relations of supercritical (sc) CO2 displacing brine, and brine rewetting the porous medium to trap scCO2 were studied to understand CO2 transport and trapping behavior in carbonate reservoirs under representative reservoir conditions. High-quality drainage and imbibition (and associated capillary pressure hysteresis) curves were measured under elevated temperature and pressure (45 ºC, 8.5 and 12 MPa) for scCO2-brine as well as at room temperature and pressure (23 ºC, 0.1 MPa) for air-brine in unconsolidated limestone and dolomite sand columns using newly developed semi-automated multistep outflow-inflow porous plate apparatus. Drainage and imbibition curves for scCO2-brine deviated from the universal scaling curves for hydrophilic interactions (with greater deviation under higher pressure) and shifted to lower Pc than predicted based on interfacial tension (IFT) changes. Augmented scaling incorporating differences in IFT and contact angle improved the scaling results but the scaled curves still did not converge onto the universal curves. Equilibrium residual trapping of the nonwetting phase was determined at Pc =0 during imbibition. The capillary-trapped amounts of scCO2 were significantly larger than for air. It is concluded that the deviations from the universal capillary scaling curves are caused by scCO2-induced wettability alteration, given the fact that pore geometry remained constant and IFT is well constrained. In-situ wettability alteration by reactive scCO2 is of critical importance and must be accounted for to achieve reliable predictions of CO2 behavior in GCS reservoirs.

  1. Reservoir sedimentology

    SciTech Connect

    Tillman, R.W.; Weber, K.J.

    1987-01-01

    Collection of papers focuses on sedimentology of siliclastic sandstone and carbonate reservoirs. Shows how detailed sedimentologic descriptions, when combined with engineering and other subsurface geologic techniques, yield reservoir models useful for reservoir management during field development and secondary and tertiary EOR. Sections cover marine sandstone and carbonate reservoirs; shoreline, deltaic, and fluvial reservoirs; and eolian reservoirs. References follow each paper.

  2. Pore Characterization of Shale Rock and Shale Interaction with Fluids at Reservoir Pressure-Temperature Conditions Using Small-Angle Neutron Scattering

    NASA Astrophysics Data System (ADS)

    Ding, M.; Hjelm, R.; Watkins, E.; Xu, H.; Pawar, R.

    2015-12-01

    Oil/gas produced from unconventional reservoirs has become strategically important for the US domestic energy independence. In unconventional realm, hydrocarbons are generated and stored in nanopores media ranging from a few to hundreds of nanometers. Fundamental knowledge of coupled thermo-hydro-mechanical-chemical (THMC) processes that control fluid flow and propagation within nano-pore confinement is critical for maximizing unconventional oil/gas production. The size and confinement of the nanometer pores creates many complex rock-fluid interface interactions. It is imperative to promote innovative experimental studies to decipher physical and chemical processes at the nanopore scale that govern hydrocarbon generation and mass transport of hydrocarbon mixtures in tight shale and other low permeability formations at reservoir pressure-temperature conditions. We have carried out laboratory investigations exploring quantitative relationship between pore characteristics of the Wolfcamp shale from Western Texas and the shale interaction with fluids at reservoir P-T conditions using small-angle neutron scattering (SANS). We have performed SANS measurements of the shale rock in single fluid (e.g., H2O and D2O) and multifluid (CH4/(30% H2O+70% D2O)) systems at various pressures up to 20000 psi and temperature up to 150 oF. Figure 1 shows our SANS data at different pressures with H2O as the pressure medium. Our data analysis using IRENA software suggests that the principal changes of pore volume in the shale occurred on smaller than 50 nm pores and pressure at 5000 psi (Figure 2). Our results also suggest that with increasing P, more water flows into pores; with decreasing P, water is retained in the pores.

  3. Fracturing high-permeability reservoirs increases productivity

    SciTech Connect

    Dusterhoft, R.G. ); Chapman, B.J. )

    1994-06-20

    Hydraulic fracturing of high-permeability reservoirs has increased long-term hydrocarbon production and reduced sand production in many areas of the world. A key element is the reduction of near well bore drawdown during production. Drawdown, the difference between reservoir and production pressures, is the driving force for flow into the well bore. As drawdown increases because of higher production rates or depletion, formation instability may cause fines and sand to migrate into the well bore region. A greater well bore radius reduces both radial velocity and drawdown. Fracturing beyond the well bore region effectively bypasses the damaged zone, increasing the effective radius of the well bore and enabling higher flow rates with lower drawdown pressures. In essence, the reservoir energy is used more efficiently because the conductive proppant bed bypasses the near well bore restrictions. The paper discusses candidate well selection; proppant selection; sand control; minifrac procedures; spurt losses; fracture design; equipment; case histories in West Africa and offshore Louisiana.

  4. Effect of Intensive Blood Pressure Treatment on Heart Failure Events in the Systolic Blood Pressure Reduction Intervention Trial.

    PubMed

    Upadhya, Bharathi; Rocco, Michael; Lewis, Cora E; Oparil, Suzanne; Lovato, Laura C; Cushman, William C; Bates, Jeffrey T; Bello, Natalie A; Aurigemma, Gerard; Fine, Lawrence J; Johnson, Karen C; Rodriguez, Carlos J; Raj, Dominic S; Rastogi, Anjay; Tamariz, Leonardo; Wiggers, Alan; Kitzman, Dalane W

    2017-04-01

    Acute decompensated heart failure (ADHF) was a frequent common outcome in SPRINT (Systolic Blood Pressure Intervention Trial). We examined whether there was differential reduction in ADHF events from intensive blood pressure [BP] treatment among the 6 key, prespecified subgroups in SPRINT: age ≥75 years, prior cardiovascular disease, chronic kidney disease, women, black race, and 3 levels of baseline systolic BP (≤132 versus >132 to <145 versus ≥145 mm Hg). ADHF was defined as hospitalization for ADHF, confirmed and formally adjudicated by a blinded events committee using standardized protocols. At 3.29 years follow-up, there were 103 ADHF events (2.2%) among 4683 standard arm participants and 65 ADHF events (1.4%) among 4678 intensive arm participants (Cox proportional hazards ratio, 0.63; 95% confidence interval, 0.46-0.85; P value =0.003). In multivariable analyses, including treatment arm, baseline covariates that were significant predictors for ADHF included chronic kidney disease, cardiovascular disease, age≥75 years, body mass index, and higher systolic BP. The beneficial effect of the intervention on incident ADHF was consistent across all prespecified subgroups. Participants who had incident ADHF had markedly increased risk of subsequent cardiovascular events, including a 27-fold increase (P<0.001) in cardiovascular death. Targeting a systolic BP<120 mm Hg, compared with <140 mm Hg, significantly reduced ADHF events, and the benefit was similar across all key, prespecified subgroups. Participants who developed ADHF had markedly increased risk for subsequent cardiovascular events and death, highlighting the importance of strategies aimed at prevention of ADHF, especially intensive BP reduction. URL: http://www.clinicaltrials.gov. Unique identifier: NCT01206062. © 2017 American Heart Association, Inc.

  5. Reduction of mosquito biting pressure by timed-release 0.3% aerosolized geraniol.

    PubMed

    Revay, Edita E; Junnila, Amy; Kline, Daniel L; Xue, Rui-De; Bernier, Ulrich R; Kravchenko, Vasiliy D; Yefremova, Zoya A; Müller, Günter C

    2012-10-01

    We conducted a study to determine the degree of personal protection provided by the Terminix(®) ALLCLEAR(®) Mosquito Mister - Lantern Edition. This outdoor unit was operated to disperse an aerosolized aqueous 0.3% geraniol emulsion in timed-release intervals of 5.0, 7.5, and 10.0 min. Human volunteers participated in landing catch experiments to test the effect of geraniol sprayed at pre-set time intervals, at two distances: (1) 18 ft (5.49 m), the maximum effective distance claimed by the manufacturer, and (2) 9 ft (2.74 m), half the effective distance from the unit. When aerosolized geraniol was dispensed, reductions in biting pressure (landing, probing and biting mosquitoes) of Culex pipiens and Aedes albopictus, at all times and distances, were evident compared to dispensation of the water spray control. The degree of protection correlated well with the distance from the subject and the time interval of releases. The 5 min time interval mode reduced overall biting pressure by more than 90% at 9 ft (2.74 m) and 18 ft (5.49 m). Reduction of biting pressure in the 7.5 min mode was still well over 80% and even in the 10 min mode, overall protection was slightly above 80% at a distance of 9 ft. The lowest but still reasonable protection level was observed in the 10 min mode, at the periphery of the area the unit claims to protect (300 ft(2)), with a biting pressure reduction of approximately two-thirds. Copyright © 2012 Elsevier B.V. All rights reserved.

  6. Description of coherent structures in the atmospheric boundary layer by model reduction of the surface pressure

    NASA Astrophysics Data System (ADS)

    Lyons, Gregory William

    The flow of coherent turbulent structures into a wind turbine is associated with vibrational blade excitation. Successful forecasting of such turbulent events for control system input would increase the lifetime of turbine components. The coherence of these features suggests description by model reduction. To this end, an array of pressure transducers was deployed on the ground at Reese Technology Center in Lubbock, Texas, and the pressure fluctuations were recorded over nearly two diurnal cycles. A program for computation of the dynamic mode decomposition was developed with special consideration for the case of a non-stationary, nonlinear system. A simulated surface-pressure perturbation was first decomposed, to inform the interpretation of experimental data. Several sets of surface-pressure data were decomposed for various meteorological conditions. The resulting dynamic modes and eigenvalues describe the spatial and temporal coherence of local features in the atmospheric boundary layer. In each case, modes were identified that can be associated with wave-like pressure fluctuations that propagate either at convective or acoustic speeds.

  7. Modified pressure distribution patterns in walking following reduction of plantar sensation.

    PubMed

    Eils, Eric; Nolte, Stefan; Tewes, Markus; Thorwesten, Lothar; Völker, Klaus; Rosenbaum, Dieter

    2002-10-01

    The aim of the present study was to investigate the influence of reduced plantar sensation on pressure distribution patterns during gait of 40 healthy subjects (25.3+/-3.3 yr, 70.8+/-10.6 kg and 176.5+/-7.8 cm) with no history of sensory disorders. Plantar sensation in the subjects was reduced by using an ice immersion approach, and reduced sensitivity was tested with Semmes-Weinstein monofilaments. All subjects performed six trials of barefoot walking over a pressure distribution platform under normal as well as iced conditions. Plantar cutaneous sensation was significantly reduced after the cooling procedure (p<0.0001). Pressure distribution analysis showed substantially modified plantar pressure distribution patterns during the roll-over process (ROP) under iced conditions. Analysis of peak pressures revealed significant reductions under the toes and under the heel (p<0.001). The contact time and the relative impulse for the whole foot did not change significantly between the two conditions. For the different areas, a significant load shift from the heel and toes towards the central and lateral forefoot and the lateral midfoot was observed. The results indicate the strong influence of reduced afferent information of the sole of the foot on the ROP in walking.

  8. Impact of Stress Reduction Interventions on Hostility and Ambulatory Systolic Blood Pressure in African American Adolescents

    PubMed Central

    Wright, Lynda Brown; Gregoski, Mathew J.; Tingen, Martha S.; Barnes, Vernon A.; Treiber, Frank A.

    2012-01-01

    This study examined the impact of breathing awareness meditation (BAM), life skills (LS) training, and health education (HE) interventions on self-reported hostility and 24-hour ambulatory blood pressure (ABP) in 121 African American (AA) ninth graders at increased risk for development of essential hypertension. They were randomly assigned to BAM, LS, or HE and engaged in intervention sessions during health class for 3 months. Before, after, and 3 months following intervention cessation, self-reported hostility and 24-hour ABP were measured. Results indicated that between pre- and postintervention, BAM participants displayed significant reductions in self-reported hostility and 24-hour systolic ABP. Reductions in hostility were significantly related to reductions in 24-hour systolic ABP. Between postintervention and follow-up, participants receiving LS showed a significant reduction in hostility but not in 24-hour ABP. Significant changes were not found for the HE group in 24-hour ABP or self-reported hostility, but these change scores were significantly correlated. The implications of the findings are discussed with regard to behavioral stress reduction programs for the physical and emotional health of AAs. PMID:22485058

  9. Autocyclic eruptivity of basaltic systems: New insights into processes of reservoir replenishment and pressurization from high-resolution borehole strain data recorded at Hekla Volcano

    NASA Astrophysics Data System (ADS)

    Hautmann, S.; Linde, A. T.; Roberts, M. J.; Sacks, S. I.

    2016-12-01

    Volcanic eruptions are typically accompanied by ground deflation due to the withdrawal of magma from depth and its effusion at the surface. Based on continuous high-resolution borehole strain data, we show that ground deformation was absent during the major effusion phases of the 1991 and 2000 eruptions of Hekla Volcano, Iceland. This lack of surface deformation provides a novel window into processes in subsurface reservoirs of basaltic volcanoes as the records challenge the classic model of magma intrusion/withdrawal as source for volcanic ground uplift/subsidence. We incorporate geodetic, petrologic and geochemical observables into theoretical models of magma chamber dynamics in order to constrain quantitatively alternative co- and inter-eruptive physical mechanisms that govern magma propagation and system pressurization. We find the lack of surface deformation during lava effusion to be linked to chamber replenishment from below whilst magma migrates as a buoyancy-driven flow from the reservoir top towards the surface. We further demonstrate that volatile ascent generates the pressure build-up in the reservoir during episodes of volcanic repose and surface re-inflation. Our model explains the persistent periodic eruptivity at Hekla throughout historic times with self-initiating cycles and is conceptually relevant to other studies on basaltic volcanic systems.

  10. The influence of a rapid drawdown and prolonged dewatering on angling pressure, catch and harvest in a Nebraska reservoir

    USGS Publications Warehouse

    DeBoer, Jason A.; Webber, Christa M.; Dixon, Taylor A.; Pope, Kevin L.

    2015-01-01

    Reservoirs can be dynamic systems, often prone to unpredictable and extreme water-level fluctuations, and can be environments where survival is difficult for zooplankton and larval fish. Although numerous studies have examined the effects of extreme reservoir drawdown on water quality, few have examined extreme drawdown on both abiotic and biotic characteristics. A fissure in the dam at Red Willow Reservoir in southwest Nebraska necessitated an extreme drawdown; the water level was lowered more than 6 m during a two-month period, reducing reservoir volume by 76%. During the subsequent low-water period (i.e., post-drawdown), spring sampling (April–June) showed dissolved oxygen concentration was lower, while turbidity and chlorophyll-a concentration were greater, relative to pre-drawdown conditions. Additionally, there was an overall increase in zooplankton density, although there were differences among taxa, and changes in mean size among taxa, relative to pre-drawdown conditions. Zooplankton assemblage composition had an average dissimilarity of 19.3% from pre-drawdown to post-drawdown. The ratio of zero to non-zero catches was greater post-drawdown for larval common carp and for all larval fishes combined, whereas we observed no difference for larval gizzard shad. Larval fish assemblage composition had an average dissimilarity of 39.7% from pre-drawdown to post-drawdown. Given the likelihood that other dams will need repair or replacement in the near future, it is imperative for effective reservoir management that we anticipate the likely abiotic and biotic responses of reservoir ecosystems as these management actions will continue to alter environmental conditions in reservoirs.

  11. Evolution of pore-fluid pressure during folding and basin contraction in overpressured reservoirs assessed by combined fracture analysis and calcite twinning paleopiezometry

    NASA Astrophysics Data System (ADS)

    Beaudoin, Nicolas; Lacombe, Olivier; Bellahsen, Nicolas; Amrouch, Khalid; Daniel, Jean-Marc

    2014-05-01

    Reconstructing the evolution of paleofluid (over)pressure in sedimentary basins during deformation is a challenging problem, especially when no hydrocarbon-bearing fluid inclusions are available to provide barometric constraints on the fluid system. This contribution reports the application to a natural case (the Bighorn Basin) of recent methodological advance to access fluid (over)pressure level prevailing in strata during sub-seismic fracture development. The fluid pressure evolution in the Mississippian-Permian Madison-Phosphoria carbonate reservoir is tentatively reconstructed from the early Sevier Layer Parallel Shortening to the Laramide folding in two basement-cored folds: the Sheep Mountain Anticline and the Rattlesnake Mountain Anticline, located on both edges of the Bighorn Basin. This reconstruction is based on a combination of stress inversion of fault slip data, calcite twins paleopiezometry and rock mechanics. Results point out that supra-hydrostatic pressure values prevail in the carbonate reservoir during most of its whole Sevier-Laramide history, and a coeval evolution between fluid overpressure and differential stress build-up is also emphasized. In each fold, a maximum value of 30-35 MPa for overpressure (i.e. above hydrostatic value) is recorded, just before Laramide folding, while minimum values of 0 MPa or 7 MPa are recorded during Sevier foreland flexure/forebulge and Laramide folding, respectively. After normalization to the same depth for both folds of differential stress magnitudes obtained from calcite twins paleopiezometry, the reconstructed values for the two folds can be compared and this comparison provides an image of the evolution fluid pressure levels at the basin scale. Until folding, the evolution of the fluid overpressure during deformation can be interpreted as reflecting large-scale fluid migrations in a laterally connected reservoir. The drop of fluid overpressure recorded in both folds during folding illustrates the

  12. Pressure management as a leakage reduction and water demand management tool: The case of the City of Mutare, Zimbabwe

    NASA Astrophysics Data System (ADS)

    Marunga, Antony; Hoko, Zvikomborero; Kaseke, Evans

    Water is now considered a scarce but essential resource, which should be managed in an integrated manner. The traditional approaches of resource development are now considered as unsustainable. Water demand management (WDM), the new approach, aims at influencing demand, thus improving distribution efficiency. Leakage control and pressure management are some of the WDM strategies. The study was carried out in Mutare and investigated the potential for leakage control through pressure management. The city experiences high water losses due to an aged system of reticulation, faulty metering of 25% and high system pressures. Unaccounted for water (UFW) for the city during the study period averaged 57%. UFW for the two specific study areas in Chikanga averaged 47% and 32%. One of the areas was investigated for leakage reduction through pressure management. The normal operating pressure in the system was 75-80 m. Epanet was used for modelling pressure distribution. Results from logged minimum night flows (MNF) show that at 77 m UFW due to leakage was 25%. A pressure reduction from 77 m to 50 m resulted in 25% reduction in MNF. Further reduction of pressure below 50 m resulted in deterioration of service. No flow was received at the highest point when the pressure was set at 30 m. At this pressure, results from Epanet gave -0.84 m pressure at the highest point. The hydraulic model predicted 50 m as minimum pressure for an acceptable minimum pressure in the system. It was concluded that operating the system at 50 m in the area under pressure management reduced the MNF by 25% without affecting the service. There is great potential for leakage control through pressure management. It is recommended that leakage control through pressure management be investigated in other parts of the city using Epanet as a tool. Replacement of very old pipes should be considered together with other strategies.

  13. Improvement in diastolic intraventricular pressure gradients in patients with HOCM after ethanol septal reduction

    NASA Technical Reports Server (NTRS)

    Rovner, Aleksandr; Smith, Rebecca; Greenberg, Neil L.; Tuzcu, E. Murat; Smedira, Nicholas; Lever, Harry M.; Thomas, James D.; Garcia, Mario J.

    2003-01-01

    We sought to validate measurement of intraventricular pressure gradients (IVPG) and analyze their change in patients with hypertrophic obstructive cardiomyopathy (HOCM) after ethanol septal reduction (ESR). Quantitative analysis of color M-mode Doppler (CMM) images may be used to estimate diastolic IVPG noninvasively. Noninvasive IVPG measurement was validated in 10 patients undergoing surgical myectomy. Echocardiograms were then analyzed in 19 patients at baseline and after ESR. Pulsed Doppler data through the mitral valve and pulmonary venous flow were obtained. CMM was used to obtain the flow propagation velocity (Vp) and to calculate IVPG off-line. Left atrial pressure was estimated with the use of previously validated Doppler equations. Data were compared before and after ESR. CMM-derived IVPG correlated well with invasive measurements obtained before and after surgical myectomy [r = 0.8, P < 0.01, Delta(CMM - invasive IVPG) = 0.09 +/- 0.45 mmHg]. ESR resulted in a decrease of resting LVOT systolic gradient from 62 +/- 10 to 29 +/- 5 mmHg (P < 0.001). There was a significant increase in the Vp and IVPG (from 48 +/- 5to 74 +/- 7 cm/s and from 1.5 +/- 0.2 to 2.6 +/- 0.3 mmHg, respectively, P < 0.001 for both). Estimated left atrial pressure decreased from 16.2 +/- 1.1 to 11.5 +/- 0.9 mmHg (P < 0.001). The increase in IVPG correlated with the reduction in the LVOT gradient (r = 0.6, P < 0.01). Reduction of LVOT obstruction after ESR is associated with an improvement in diastolic suction force. Noninvasive measurements of IVPG may be used as an indicator of diastolic function improvement in HOCM.

  14. Improvement in diastolic intraventricular pressure gradients in patients with HOCM after ethanol septal reduction

    NASA Technical Reports Server (NTRS)

    Rovner, Aleksandr; Smith, Rebecca; Greenberg, Neil L.; Tuzcu, E. Murat; Smedira, Nicholas; Lever, Harry M.; Thomas, James D.; Garcia, Mario J.

    2003-01-01

    We sought to validate measurement of intraventricular pressure gradients (IVPG) and analyze their change in patients with hypertrophic obstructive cardiomyopathy (HOCM) after ethanol septal reduction (ESR). Quantitative analysis of color M-mode Doppler (CMM) images may be used to estimate diastolic IVPG noninvasively. Noninvasive IVPG measurement was validated in 10 patients undergoing surgical myectomy. Echocardiograms were then analyzed in 19 patients at baseline and after ESR. Pulsed Doppler data through the mitral valve and pulmonary venous flow were obtained. CMM was used to obtain the flow propagation velocity (Vp) and to calculate IVPG off-line. Left atrial pressure was estimated with the use of previously validated Doppler equations. Data were compared before and after ESR. CMM-derived IVPG correlated well with invasive measurements obtained before and after surgical myectomy [r = 0.8, P < 0.01, Delta(CMM - invasive IVPG) = 0.09 +/- 0.45 mmHg]. ESR resulted in a decrease of resting LVOT systolic gradient from 62 +/- 10 to 29 +/- 5 mmHg (P < 0.001). There was a significant increase in the Vp and IVPG (from 48 +/- 5to 74 +/- 7 cm/s and from 1.5 +/- 0.2 to 2.6 +/- 0.3 mmHg, respectively, P < 0.001 for both). Estimated left atrial pressure decreased from 16.2 +/- 1.1 to 11.5 +/- 0.9 mmHg (P < 0.001). The increase in IVPG correlated with the reduction in the LVOT gradient (r = 0.6, P < 0.01). Reduction of LVOT obstruction after ESR is associated with an improvement in diastolic suction force. Noninvasive measurements of IVPG may be used as an indicator of diastolic function improvement in HOCM.

  15. Study of polytropic exponent based on high pressure switching expansion reduction

    NASA Astrophysics Data System (ADS)

    Wang, Xuanyin; Luo, Yuxi; Xu, Zhipeng

    2011-10-01

    Switching expansion reduction (SER) uses a switch valve to substitute the throttle valve to reduce pressure for high pressure pneumatics. The experiments indicate that the simulation model well predicts the actual characteristics. The heat transfers and polytropic exponents of the air in expansion tank and supply tanks of SER have been studied on the basis of the experiments and the simulation model. Through the mathematical reasoning in this paper, the polytropic exponent can be calculated by the air mass, heat, and work exchanges of the pneumatic container. For the air in a constant volume tank, when the heat-absorption is large enough to raise air temperature in discharging process, the polytropic exponent is less than 1; when the air is experiencing a discharging and heat-releasing process, the polytropic exponent exceeds the specific heat ratio (the value of 1.4).

  16. Veins in Paleo-reservoir as a Natural Indication of Coupled Changes in Pore Pressure and Stress, Salt Wash Graben of SE Utah, USA

    NASA Astrophysics Data System (ADS)

    Gwon, S.; Edwards, P.; Kim, Y. S.

    2015-12-01

    Hydrofracturing associated with elevated fluid pressure coupled with changes in stress has been crucial in enhancing the production and recovery of hydrocarbons. Furthermore, it is also an important issue to access the efficiency and stability of long-term CO2 geologic storage reservoirs. Veins are mineral-filled extension fractures developed along the plane of σ1-σ2 and perpendicular to σ3, and the fluid pressure must exceed σ3applied to the plane when the vein opens. Therefore, vein is a well-known natural analogue for fluid migration in a paleo-reservoir. In the Salt Wash Graben of SE Utah, CO2-charged vein systems hosted in the bleached Entrada Formation are well developed and examined to understand the conditions of fluid pressure and stress during the injections of CO2-charged fluid. Based on color and relative cross-cutting relationship in the field, veins are subdivided into two sets; sub-vertical black mineral-rich veins and orthogonal calcite veins that have previously been described as 'grid-lock fractures'. The vein distribution and fluid leakage along through-going fractures in mechanic units allow us to determine the stress regime and driving stress condition through 3D-Mohr circle reconstruction. The results of this statistical analysis for the veins show that the orthogonal veins indicate a 'stress transition' with maximum principal stress direction changing from vertical to NNW-SSE sub-horizontal which coincides with the current regional stress regime. The possible causes of the stress transition can be considered. The process of repeated sealing, reactivation and localization of veins within the bleached zone is a natural indication of a coupled change in pore pressure and stress in the reservoir. Thus, an understanding of the effect of stress changes due to the volumetric injection of CO2 in the subsurface as well as a knowledge of how pre-existing fractures affect fluid flow with respect to elevated pore pressures in layered rocks are

  17. Reduction of the bulk modulus at high pressure in CrN.

    PubMed

    Rivadulla, Francisco; Bañobre-López, Manuel; Quintela, Camilo X; Piñeiro, Alberto; Pardo, Victor; Baldomir, Daniel; López-Quintela, Manuel Arturo; Rivas, José; Ramos, Carlos A; Salva, Horacio; Zhou, Jian-Shi; Goodenough, John B

    2009-12-01

    Nitride coatings are increasingly demanded in the cutting- and machining-tool industry owing to their hardness, thermal stability and resistance to corrosion. These properties derive from strongly covalent bonds; understanding the bonding is a requirement for the design of superhard materials with improved capabilities. Here, we report a pressure-induced cubic-to-orthorhombic transition at approximately 1 GPa in CrN. High-pressure X-ray diffraction and ab initio calculations show an unexpected reduction of the bulk modulus, K0, of about 25% in the high-pressure (lower volume) phase. Our combined theoretical and experimental approach shows that this effect is the result of a large exchange striction due to the approach of the localized Cr:t3 electrons to becoming molecular-orbital electrons in Cr-Cr bonds. The softening of CrN under pressure is a manifestation of a strong competition between different types of chemical bond that are found at a crossover from a localized to a molecular-orbital electronic transition.

  18. Microfluidic vapor-diffusion barrier for pressure reduction in fully closed PCR modules.

    PubMed

    Czilwik, G; Schwarz, I; Keller, M; Wadle, S; Zehnle, S; von Stetten, F; Mark, D; Zengerle, R; Paust, N

    2015-02-21

    Microfluidic systems for polymerase chain reaction (PCR) should be fully closed to avoid vapor loss and to exclude the risk of contaminating the laboratory environment. In closed systems however, the high temperatures of up to 95 °C associated with PCR cause high overpressures up to 100 kPa, dominated by the increase of vapor partial pressure upon evaporation. Such high overpressures pose challenges to the mechanical stability of microfluidic chips as well as to the liquid handling in integrated sample-to-answer systems. In this work, we drastically reduce the pressure increase in fully closed PCR systems by integrating a microchannel that serves as a vapor-diffusion barrier (VDB), separating the liquid-filled PCR chamber from an auxiliary air chamber. In such configurations, propagation of vapor from the PCR chamber into the auxiliary air chamber and as a consequence the increase of pressure is limited by the slow diffusion process of vapor through the VDB. At temperature increase from 23 °C to 95 °C, we demonstrate the reduction of overpressure from more than 80 kPa without the VDB to only 35 kPa with the VDB. We further demonstrate proper function of VDB and its easy integration with downstream processes for PCR based nucleic acid amplification within centrifugal microfluidics. Without integration of the VDB, malfunction due to pressure-induced delamination of the microfluidic chip occurred.

  19. Compaction of North-sea chalk by pore-failure and pressure solution in a producing reservoir

    NASA Astrophysics Data System (ADS)

    Keszthelyi, Daniel; Dysthe, Dag; Jamtveit, Bjorn

    2016-02-01

    The Ekofisk field, Norwegian North sea,is an example of compacting chalk reservoir with considerable subsequent seafloor subsidence due to petroleum production. Previously, a number of models were created to predict the compaction using different phenomenological approaches. Here we present a different approach, we use a new creep model based on microscopic mechanisms with no fitting parameters to predict strain rate at core scale and at reservoir scale. The model is able to reproduce creep experiments and the magnitude of the observed subsidence making it the first microstructural model which can explain the Ekofisk compaction.

  20. Stress reduction programs in patients with elevated blood pressure: a systematic review and meta-analysis.

    PubMed

    Rainforth, Maxwell V; Schneider, Robert H; Nidich, Sanford I; Gaylord-King, Carolyn; Salerno, John W; Anderson, James W

    2007-12-01

    Substantial evidence indicates that psychosocial stress contributes to hypertension and cardiovascular disease (CVD). Previous meta-analyses of stress reduction and high blood pressure (BP) were outdated and/or methodologically limited. Therefore, we conducted an updated systematic review of the published literature and identified 107 studies on stress reduction and BP. Seventeen trials with 23 treatment comparisons and 960 participants with elevated BP met criteria for well-designed randomized controlled trials and were replicated within intervention categories. Meta-analysis was used to calculate BP changes for biofeedback, -0.8/-2.0 mm Hg (P = NS); relaxation-assisted biofeedback, +4.3/+2.4 mm Hg (P = NS); progressive muscle relaxation, -1.9/-1.4 mm Hg (P = NS); stress management training, -2.3/-1.3 mm (P = NS); and the Transcendental Meditation program, -5.0/-2.8 mm Hg (P = 0.002/0.02). Available evidence indicates that among stress reduction approaches, the Transcendental Meditation program is associated with significant reductions in BP. Related data suggest improvements in other CVD risk factors and clinical outcomes.

  1. Stress Reduction Programs in Patients with Elevated Blood Pressure: A Systematic Review and Meta-analysis

    PubMed Central

    Rainforth, Maxwell V.; Schneider, Robert H.; Nidich, Sanford I.; Gaylord-King, Carolyn; Salerno, John W.; Anderson, James W.

    2007-01-01

    Substantial evidence indicates that psychosocial stress contributes to hypertension and cardiovascular disease (CVD). Previous meta-analyses of stress reduction and high blood pressure (BP) were outdated and/or methodologically limited. Therefore, we conducted an updated systematic review of the published literature and identified 107 studies on stress reduction and BP. Seventeen trials with 23 treatment comparisons and 960 participants with elevated BP met criteria for well-designed randomized controlled trials and were replicated within intervention categories. Meta-analysis was used to calculate BP changes for biofeedback, −0.8/−2.0 mm Hg (P = NS); relaxation-assisted biofeedback, +4.3/+2.4 mm Hg (P = NS); progressive muscle relaxation, −1.9/−1.4 mm Hg (P = NS); stress management training, −2.3/−1.3 mm (P = NS); and the Transcendental Meditation program, −5.0/−2.8 mm Hg (P = 0.002/0.02). Available evidence indicates that among stress reduction approaches, the Transcendental Meditation program is associated with significant reductions in BP. Related data suggest improvements in other CVD risk factors and clinical outcomes. PMID:18350109

  2. Capillary pressure-saturation relations for supercritical CO2 and brine in limestone/dolomite sands: implications for geologic carbon sequestration in carbonate reservoirs.

    PubMed

    Wang, Shibo; Tokunaga, Tetsu K

    2015-06-16

    In geologic carbon sequestration, capillary pressure (Pc)-saturation (Sw) relations are needed to predict reservoir processes. Capillarity and its hysteresis have been extensively studied in oil-water and gas-water systems, but few measurements have been reported for supercritical (sc) CO2-water. Here, Pc-Sw relations of scCO2 displacing brine (drainage), and brine rewetting (imbibition) were studied to understand CO2 transport and trapping behavior under reservoir conditions. Hysteretic drainage and imbibition Pc-Sw curves were measured in limestone sands at 45 °C under elevated pressures (8.5 and 12.0 MPa) for scCO2-brine, and in limestone and dolomite sands at 23 °C (0.1 MPa) for air-brine using a new computer programmed porous plate apparatus. scCO2-brine drainage and imbibition curves shifted to lower Pc relative to predictions based on interfacial tension, and therefore deviated from capillary scaling predictions for hydrophilic interactions. Fitting universal scaled drainage and imbibition curves show that wettability alteration resulted from scCO2 exposure over the course of months-long experiments. Residual trapping of the nonwetting phases was determined at Pc = 0 during imbibition. Amounts of trapped scCO2 were significantly larger than for those for air, and increased with pressure (depth), initial scCO2 saturation, and time. These results have important implications for scCO2 distribution, trapping, and leakage potential.

  3. The research on borehole stability in depleted reservoir and caprock: using the geophysics logging data.

    PubMed

    Yuan, Junliang; Deng, Jingen; Luo, Yong; Guo, Shisheng; Zhang, Haishan; Tan, Qiang; Zhao, Kai; Hu, Lianbo

    2013-01-01

    Long-term oil and gas exploitation in reservoir will lead to pore pressure depletion. The pore pressure depletion will result in changes of horizontal in-situ stresses both in reservoirs and caprock formations. Using the geophysics logging data, the magnitude and orientation changes of horizontal stresses in caprock and reservoir are studied. Furthermore, the borehole stability can be affected by in-situ stresses changes. To address this issue, the dehydration from caprock to reservoir and roof effect of caprock are performed. Based on that, the influence scope and magnitude of horizontal stresses reduction in caprock above the depleted reservoirs are estimated. The effects of development on borehole stability in both reservoir and caprock are studied step by step with the above geomechanical model.

  4. The Research on Borehole Stability in Depleted Reservoir and Caprock: Using the Geophysics Logging Data

    PubMed Central

    Deng, Jingen; Luo, Yong; Guo, Shisheng; Zhang, Haishan; Tan, Qiang; Zhao, Kai; Hu, Lianbo

    2013-01-01

    Long-term oil and gas exploitation in reservoir will lead to pore pressure depletion. The pore pressure depletion will result in changes of horizontal in-situ stresses both in reservoirs and caprock formations. Using the geophysics logging data, the magnitude and orientation changes of horizontal stresses in caprock and reservoir are studied. Furthermore, the borehole stability can be affected by in-situ stresses changes. To address this issue, the dehydration from caprock to reservoir and roof effect of caprock are performed. Based on that, the influence scope and magnitude of horizontal stresses reduction in caprock above the depleted reservoirs are estimated. The effects of development on borehole stability in both reservoir and caprock are studied step by step with the above geomechanical model. PMID:24228021

  5. Generation of isotopically and compositionally distinct water during thermochemical sulfate reduction (TSR) in carbonate reservoirs: Triassic Feixianguan Formation, Sichuan Basin, China

    NASA Astrophysics Data System (ADS)

    Jiang, Lei; Worden, Richard H.; Cai, Chunfang

    2015-09-01

    Thermochemical sulfate reduction (TSR), the reaction of petroleum with anhydrite in reservoirs resulting in the growth of calcite and the accumulation of H2S, has been documented in the Feixianguan Formation dolomite reservoir in the Sichuan Basin, China. Fluid inclusion salinity and homogenization temperature data have shown that TSR results in a decrease in salinity from a pre-TSR value of 25 wt.% down to 5 wt.% as a result of water created as a byproduct of progressive TSR. We have studied the isotopic character of the water that resulted from TSR in the Feixianguan Formation by analyzing the oxygen isotopes of TSR calcite and determining the oxygen isotopes of the water in equilibrium with the TSR calcite at the temperatures determined by aqueous fluid inclusion analysis. We have compared these TSR-waters to water that would have been in equilibrium with the bulk rock, also at the temperatures determined by aqueous fluid inclusion analysis. We have found that the TSR-waters are relatively depleted in oxygen isotopes (by up to 8‰ compared to what would be expected at equilibrium between the bulk rock and water) since this type of water was specifically derived from anhydrite. The generation of relatively large volumes of low salinity, low δ18O water associated with advanced TSR in the Feixianguan Formation has also been reported in the Permian Khuff Formation in Abu Dhabi and from sour Devonian fields in the Western Canada Basin. This suggests that TSR-derived water may be a common phenomenon, the effects of which on mesogenetic secondary porosity and reservoir quality have previously been underappreciated.

  6. Perceived standing position after reduction of foot-pressure sensation by cooling the sole.

    PubMed

    Fujiwara, Katsuo; Asai, Hitoshi; Miyaguchi, Akiyoshi; Toyama, Hiroshi; Kunita, Kenji; Inoue, Katsumi

    2003-04-01

    We investigated the influence of the reduction of foot-pressure sensation by cooling the sole of the foot, at 1 degree C for 30 or 40 minutes, on the perception of standing position varied in the anteroposterior direction. The subjects were 16 healthy undergraduates. Firstly, for 4 of the subjects, cooling the sole of the foot decreased sensory information from the mechanoreceptors in the sole, by testing for an increase in the threshold for two-point discrepancy discrimination on the sole of the foot and for the disappearance of postural change with vibration to the sole. Next, the perception of standing position was measured by reproduction of a given standing reference position involving forward or backward leaning under both normal and cooled conditions of the feet. Standing position was varied in relation to the location of the center of foot pressure, defined as distance from the heel in percentage of the length of the foot. The reference positions, representing various locations of the center of foot pressure, were set at 10% increments from 20% to 80% of the length of the foot. With eyes closed, the subject first experienced the reference position and then attempted to reproduce it. The mean location of the center of foot pressure in the quiet standing posture was 45.7%. At the 40%, 50%, and 60% reference positions, those closest to quiet standing, absolute errors of reproduction were significantly larger than at other reference positions in both the normal and the cooled conditions. They were significantly larger in the cooled than in the normal condition. The 50% and 60% reference positions were reproduced significantly further forward in the cooled than in the normal condition. These results may be explained as due to an absence of marked changes in sensory information from both muscular activity and foot pressure when moving to reference positions close to the quiet standing posture.

  7. Petroleum reservoir data for testing simulation models

    SciTech Connect

    Lloyd, J.M.; Harrison, W.

    1980-09-01

    This report consists of reservoir pressure and production data for 25 petroleum reservoirs. Included are 5 data sets for single-phase (liquid) reservoirs, 1 data set for a single-phase (liquid) reservoir with pressure maintenance, 13 data sets for two-phase (liquid/gas) reservoirs and 6 for two-phase reservoirs with pressure maintenance. Also given are ancillary data for each reservoir that could be of value in the development and validation of simulation models. A bibliography is included that lists the publications from which the data were obtained.

  8. Effects of high hydrostatic pressure and chemical reduction on the emulsification properties of gum arabic.

    PubMed

    Ma, Fanyi; Bell, Alan E; Davis, Fred J; Chai, Yunxi

    2015-04-15

    Gum arabic is widely used in the food industry as an additive, both as a thickener and an emulsifier. This study has compared the emulsification properties of two types of gums, KLTA (Acacia senegal) and GCA (Acacia seyal), both in their native/untreated forms and after exposure to high pressure (800 MPa). Further studies were undertaken to chemically modify the disulphide linkages present and to investigate the effects of their reduction on the diffusion of the carbohydrate materials. The emulsification properties of the gum samples were examined by determining the droplet size distribution in a "model" oil-in-water system. Results showed that high pressure treatment and chemical reduction of gums changed the emulsification properties of both gums. The high molecular weight component in arabinogalactan-proteins (AGP/GP), and more "branched" carbohydrates present in gum arabic, may be responsible for the emulsification properties of GCA gum, indicating that the emulsification mechanisms for KLTA and GCA were different. Copyright © 2014 Elsevier Ltd. All rights reserved.

  9. Hybrid Wing-Body (HWB) Pressurized Fuselage Modeling, Analysis, and Design for Weight Reduction

    NASA Technical Reports Server (NTRS)

    Mukhopadhyay, Vivek

    2012-01-01

    This paper describes the interim progress for an in-house study that is directed toward innovative structural analysis and design of next-generation advanced aircraft concepts, such as the Hybrid Wing-Body (HWB) and the Advanced Mobility Concept-X flight vehicles, for structural weight reduction and associated performance enhancement. Unlike the conventional, skin-stringer-frame construction for a cylindrical fuselage, the box-type pressurized fuselage panels in the HWB undergo significant deformation of the outer aerodynamic surfaces, which must be minimized without significant structural weight penalty. Simple beam and orthotropic plate theory is first considered for sizing, analytical verification, and possible equivalent-plate analysis with appropriate simplification. By designing advanced composite stiffened-shell configurations, significant weight reduction may be possible compared with the sandwich and ribbed-shell structural concepts that have been studied previously. The study involves independent analysis of the advanced composite structural concepts that are presently being developed by The Boeing Company for pressurized HWB flight vehicles. High-fidelity parametric finite-element models of test coupons, panels, and multibay fuselage sections, were developed for conducting design studies and identifying critical areas of potential failure. Interim results are discussed to assess the overall weight/strength advantages.

  10. Pressure and partial wetting effects on superhydrophobic friction reduction in microchannel flow

    NASA Astrophysics Data System (ADS)

    Kim, Tae Jin; Hidrovo, Carlos

    2012-11-01

    Friction reduction in microchannel flows can help alleviate the inherently taxing pumping power requirements associated with the dimensions involved. One possible way of achieving friction reduction is through the introduction of surface microtexturing that can lead to a superhydrophobic Cassie-Baxter state. The Cassie-Baxter state is characterized by the presence of air pockets within the surface microtexturing believed to act as an effective "shear free" (or at least shear reduced) layer, decreasing the overall friction characteristics of the surface. Most work in this area has concentrated on optimizing the surface microtexturing geometry to maximize the friction reduction effects and overall stability of the Cassie-Baxter state. However, less attention has been paid to the effects of partially wetted conditions induced by pressure and the correlation between the liquid-gas interface location within the surface microtexturing and the microchannel flow characteristics. This is mainly attributed to the difficulty in tracking the interface shape and location within the microtexturing in the typical top-down view arrangements used in most studies. In this paper, a rectangular microchannel with regular microtexturing on the sidewalls is used to visualize and track the location of the air-water interface within the roughness elements. While visually tracking the wetting conditions in the microtextures, pressure drops versus flow rates for each microchannel are measured and analyzed in terms of the non-dimensional friction coefficient. The frictional behavior of the Poiseuille flow suggests that (1) the air-water interface more closely resembles a no-slip boundary rather than a shear-free one, (2) the friction is rather insensitive to the degree of microtexturing wetting, and (3) the fully wetted (Wenzel state) microtexturing provides lower friction than the non-wetted one (Cassie state), in corroboration with observations (1) and (2).

  11. Competitive, microbially-mediated reduction of nitrate with sulfide and aromatic oil components in a low-temperature, western Canadian oil reservoir.

    PubMed

    Lambo, Adewale J; Noke, Kim; Larter, Steve R; Voordouw, Gerrit

    2008-12-01

    Fields from which oil is produced by injection of sulfate-bearing water often exhibit an increase in sulfide concentration with time (souring). Nitrate added to the injection water lowers the sulfide concentration by the action of sulfide-oxidizing, nitrate-reducing bacteria (SO-NRB). However, the injected nitrate can also be reduced with oil organics by heterotrophic NRB (hNRB). Aqueous volatile fatty acids (VFAs; a mixture of acetate, propionate, and butyrate) are considered important electron donors in this regard. Injection and produced waters from a western Canadian oil field with a low in situ reservoir temperature (30 degrees C) had only 0.1-0.2 mM VFAs. Amendment of these waters with nitrate gave therefore only partial reduction. More nitrate was reduced when 2% (v/v) oil was added, with light oil giving more reduction than heavy oil. GC-MS analysis of in vitro degraded oils and electron balance considerations indicated that toluene served as the primary electron donor for nitrate reduction. The differences in the extent of nitrate reduction were thus related to the toluene content of the light and heavy oil (30 and 5 mM, respectively). Reduction of nitrate with sulfide by SO-NRB always preceded that with oil organics by hNRB, even though microbially catalyzed kinetics with either electron donor were similar. Inhibition of hNRB by sulfide is responsible for this phenomenon. Injected nitrate will thus initially be reduced with sulfide through the action of SO-NRB. However, once sulfide has been eliminated from the near-injection wellbore region, oil organics will be targeted by the action of hNRB. Hence, despite the kinetic advantage of SO-NRB, the nitrate dose required to eliminate sulfide from a reservoir depends on the concentration of hNRB-degradable oil organics, with toluene being the most important in the field under study. Because the toluene concentration is lower in heavy oilthan in light oil, nitrate injection into a heavy-oil-producing field of

  12. Blood pressure reduction due to hemoglobin glycosylation in type 2 diabetic patients

    PubMed Central

    Cabrales, Pedro; Vázquez, Miguel A Salazar; Vázquez, Beatriz Y Salazar; Rodríguez-Morán, Martha; Intaglietta, Marcos; Guerrero-Romero, Fernando

    2008-01-01

    Objective: To test the hypothesis that glycosylation of hemoglobin constitutes a risk factor for hypertension. Methods: A total of 129 relative uniform diabetic subjects (86 women and 42 men) were enrolled in a cross sectional study. Exclusion criteria included alcohol consumption, smoking, ischemic heart disease, stroke, neoplasia, renal, hepatic, and chronic inflammatory disease. Systolic and diastolic pressures were recorded in subsequent days and mean arterial blood pressure (MAP) was determined. Hemoglobin glycosylation was measured by determining the percentage glycosylated hemoglobin (HbA1c) by means of the automated microparticle enzyme immunoassay test. Results: MAP was found to be independent of the concentration of HbA1c; however, correcting MAP for the variability in hematocrit, to evidence the level of vasoconstriction (or vasodilatation) showed that MAP is negatively correlated with the concentration of HbA1c (p for trend <0.05), when patients treated for hypertension are excluded from the analysis. Patients treated for hypertension showed the opposite trend with increasing MAP as HbA1c increased (p for the difference in trends <0.05). Conclusions: Glycosylation per se appears to lead to blood pressure reduction in type 2 diabetic patients untreated for hypertension. Treatment for hypertension may be associated with a level of endothelial dysfunction that interferes with the antihypertensive effect of HbA1c. PMID:19066010

  13. ACE inhibition prevents Na and water retention and MABP increase during reduction of renal perfusion pressure.

    PubMed

    Boemke, W; Seeliger, E; Rothermund, L; Corea, M; Pettker, R; Mollenhauer, G; Reinhardt, H W

    1995-09-01

    Two groups of six dogs were studied during 4 control days and 4 days of reduced renal perfusion pressure (rRPP) servo controlled at 20% below the individual dog's 24-h mean arterial blood pressure (MABP) during control days, i.e., below the threshold for renin release. On rRPP days, endogenous activation of plasma aldosterone and angiotensin II was inhibited by the angiotensin-converting enzyme inhibitor captopril. The dogs were kept on a high-Na and high-water intake. Unlike studies during rRPP alone, there was no Na and water retention during rRPP+captopril. Glomerular filtration rate dropped by approximately 9%, and MABP remained in the range of control days. Plasma renin activity rose to values 14 times greater than control, whereas plasma aldosterone decreased by approximately 60%. Atrial natriuretic peptide remained in the range of controls. In conclusion, angiotensin-converting enzyme inhibition can prevent the otherwise obligatory Na and water retention and systemic MABP increase during a 20% reduction in renal perfusion pressure. This is achieved most likely via the captopril-induced fall in angiotensin II and plasma aldosterone levels.

  14. Use of Acetate, Propionate, and Butyrate for Reduction of Nitrate and Sulfate and Methanogenesis in Microcosms and Bioreactors Simulating an Oil Reservoir

    PubMed Central

    Shen, Yin; An, Dongshan; Voordouw, Gerrit

    2017-01-01

    ABSTRACT Acetate, propionate, and butyrate (volatile fatty acids [VFA]) occur in oil field waters and are frequently used for microbial growth of oil field consortia. We determined the kinetics of use of these VFA components (3 mM each) by an anaerobic oil field consortium in microcosms containing 2 mM sulfate and 0, 4, 6, 8, or 13 mM nitrate. Nitrate was reduced first, with a preference for acetate and propionate. Sulfate reduction then proceeded with propionate (but not butyrate) as the electron donor, whereas the fermentation of butyrate (but not propionate) was associated with methanogenesis. Microbial community analyses indicated that Paracoccus and Thauera (Paracoccus-Thauera), Desulfobulbus, and Syntrophomonas-Methanobacterium were the dominant taxa whose members catalyzed these three processes. Most-probable-number assays showed the presence of up to 107/ml of propionate-oxidizing sulfate-reducing bacteria (SRB) in waters from the Medicine Hat Glauconitic C field. Bioreactors with the same concentrations of sulfate and VFA responded similarly to increasing concentrations of injected nitrate as observed in the microcosms: sulfide formation was prevented by adding approximately 80% of the nitrate dose needed to completely oxidize VFA to CO2 in both. Thus, this work has demonstrated that simple time-dependent observations of the use of acetate, propionate, and butyrate for nitrate reduction, sulfate reduction, and methanogenesis in microcosms are a good proxy for these processes in bioreactors, monitoring of which is more complex. IMPORTANCE Oil field volatile fatty acids acetate, propionate, and butyrate were specifically used for nitrate reduction, sulfate reduction, and methanogenic fermentation. Time-dependent analyses of microcosms served as a good proxy for these processes in a bioreactor, mimicking a sulfide-producing (souring) oil reservoir: 80% of the nitrate dose required to oxidize volatile fatty acids to CO2 was needed to prevent souring in both

  15. Persistence of Sulfadoxine-Pyrimethamine Resistance Despite Reduction of Drug Pressure in Malawi.

    PubMed

    Artimovich, Elena; Schneider, Kristan; Taylor, Terrie E; Kublin, James G; Dzinjalamala, Fraction K; Escalante, Ananias A; Plowe, Christopher V; Laufer, Miriam K; Takala-Harrison, Shannon

    2015-09-01

    In 2007, Malawi replaced sulfadoxine-pyrimethamine (SP) with an artemisinin-based combination therapy as the first-line treatment for uncomplicated Plasmodium falciparum malaria in response to failing SP efficacy. Here we estimate the effect of reduced SP pressure on the prevalence of SP-resistant parasites and the characteristics of the associated selective sweeps flanking the resistance loci. Samples obtained from individuals with clinical malaria during a period of high SP use (1999-2001), a transitional period (2007-2008), and a period of low SP use (2012) were genotyped for resistance markers at pfdhfr-ts codons 51, 59, and 108 and pfdhps codons 437, 540, and 581. Expected heterozygosity was estimated to evaluate the genetic diversity flanking pfdhfr-ts and pfdhps. An increase in the prevalence of the resistance haplotypes DHFR 51I/59R/108N and DHPS 437G/540E occurred under sustained drug pressure, with no change in haplotype prevalence 5 years after reduction in SP pressure. The DHPS 437G/540E/581G haplotype was observed in 2007 and increased in prevalence during a period of reduced SP pressure. Changes to the sweep characteristics flanking pfdhfr-ts and pfdhps were minimal. In contrast to the rapid and complete return of chloroquine-susceptible falciparum malaria after chloroquine was withdrawn from Malawi, a reemergence of SP efficacy is unlikely in the near future. © The Author 2015. Published by Oxford University Press on behalf of the Infectious Diseases Society of America. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

  16. Effects of dietary fish and weight reduction on ambulatory blood pressure in overweight hypertensives.

    PubMed

    Bao, D Q; Mori, T A; Burke, V; Puddey, I B; Beilin, L J

    1998-10-01

    Obesity is a major factor contributing to hypertension and increased risk of cardiovascular disease. Regular consumption of dietary fish and omega3 fatty acids of marine origin can lower blood pressure (BP) levels and reduce cardiovascular risk. This study examined the potential effects of combining dietary fish rich in omega3 fatty acids with a weight loss regimen in overweight hypertensive subjects, with ambulatory BP levels as the primary end point. Using a factorial design, 69 overweight medication-treated hypertensives were randomized to a daily fish meal (3.65 g omega3 fatty acids), weight reduction, the 2 regimens combined, or a control regimen for 16 weeks. Sixty-three subjects with a mean+/-SEM body mass index of 31.6+/-0.5 kg/m2 completed the study. Weight fell by 5.6+/-0.8 kg with energy restriction. Dietary fish and weight loss had significant independent and additive effects on 24-hour ambulatory BP. Effects were greatest on awake systolic and diastolic BP (P<0.01); relative to control, awake pressures fell 6.0/3.0 mm Hg with dietary fish alone, 5.5/2.2 mm Hg with weight reduction alone, and 13.0/9.3 mm Hg with fish and weight loss combined. These results also remained significant after further adjustment for changes in urinary sodium, potassium, or the sodium/potassium ratio, as well as dietary macronutrients. Dietary fish also significantly reduced 24-hour (-3.1+/-1.4 bpm, P=0.036) and awake (-4.2+/-1.6 bpm, P=0. 013) ambulatory heart rates. Weight reduction had a significant effect on sleeping heart rate only (-3.2+/-1.7 bpm, P=0.037). Combining a daily fish meal with a weight-reducing regimen led to additive effects on ambulatory BP and decreased heart rate. The effects were large, suggesting that cardiovascular risk and antihypertensive drug requirements are likely to be reduced substantially by combining dietary fish meals rich in omega3 fatty acids with weight-loss regimens in overweight medication-treated hypertensives. The reduction in heart

  17. Blood pressure reduction does not reduce perihematoma oxygenation: a CT perfusion study.

    PubMed

    Kate, Mahesh P; Hansen, Mikkel B; Mouridsen, Kim; Østergaard, Leif; Choi, Victor; Gould, Bronwen E; McCourt, Rebecca; Hill, Michael D; Demchuk, Andrew M; Coutts, Shelagh B; Dowlatshahi, Dariush; Emery, Derek J; Buck, Brian H; Butcher, Kenneth S

    2014-01-01

    Blood pressure (BP) reduction after intracerebral hemorrhage (ICH) is controversial, because of concerns that this may cause critical reductions in perihematoma perfusion and thereby precipitate tissue damage. We tested the hypothesis that BP reduction reduces perihematoma tissue oxygenation.Acute ICH patients were randomized to a systolic BP target of <150 or <180 mm Hg. Patients underwent CT perfusion (CTP) imaging 2 hours after randomization. Maps of cerebral blood flow (CBF), maximum oxygen extraction fraction (OEF(max)), and the resulting maximum cerebral metabolic rate of oxygen (CMRO2(max)) permitted by local hemodynamics, were calculated from raw CTP data.Sixty-five patients (median (interquartile range) age 70 (20)) were imaged at a median (interquartile range) time from onset to CTP of 9.8 (13.6) hours. Mean OEF(max) was elevated in the perihematoma region (0.44±0.12) relative to contralateral tissue (0.36±0.11; P<0.001). Perihematoma CMRO2(max) (3.40±1.67 mL/100 g per minute) was slightly lower relative to contralateral tissue (3.63±1.66 mL/100 g per minute; P=0.025). Despite a significant difference in systolic BP between the aggressive (140.5±18.7 mm Hg) and conservative (163.0±10.6 mm Hg; P<0.001) treatment groups, perihematoma CBF was unaffected (37.2±11.9 versus 35.8±9.6 mL/100 g per minute; P=0.307). Similarly, aggressive BP treatment did not affect perihematoma OEF(max) (0.43±0.12 versus 0.45±0.11; P=0.232) or CMRO2(max) (3.16±1.66 versus 3.68±1.85 mL/100 g per minute; P=0.857). Blood pressure reduction does not affect perihematoma oxygen delivery. These data support the safety of early aggressive BP treatment in ICH.

  18. Blood pressure reduction after gastric bypass surgery is explained by a decrease in cardiac output.

    PubMed

    van Brussel, Peter M; van den Bogaard, Bas; de Weijer, Barbara A; Truijen, Jasper; Krediet, C T Paul; Janssen, Ignace M; van de Laar, Arnold; Kaasjager, Karin; Fliers, Eric; van Lieshout, Johannes J; Serlie, Mireille J; van den Born, Bert-Jan H

    2017-02-01

    Blood pressure (BP) decreases in the first weeks after Roux-and-Y gastric bypass surgery. Yet the pathophysiology of the BP-lowering effects observed after gastric bypass surgery is incompletely understood. We evaluated BP, systemic hemodynamics, and baroreflex sensitivity in 15 obese women[mean age 42 ± 7 standard deviation (SD) yr, body mass index 45 ± 6 kg/m(2)] 2 wk before and 6 wk following Roux-and-Y gastric bypass surgery. Six weeks after gastric bypass surgery, mean body weight decreased by 13 ± 5 kg (10%, P < 0.001). Office BP decreased from 137 ± 10/86 ± 6 to 128 ± 12/81 ± 9 mmHg (P < 0.001, P < 0.01), while daytime ambulatory BP decreased from 128 ± 14/80 ± 9 to 114 ± 10/73 ± 6 mmHg (P = 0.01, P = 0.05), whereas nighttime BP decreased from 111 ± 13/66 ± 7 to 102 ± 9/62 ± 7 mmHg (P = 0.04, P < 0.01). The decrease in BP was associated with a 1.6 ± 1.2 l/min (20%, P < 0.01) decrease in cardiac output (CO), while systemic vascular resistance increased (153 ± 189 dyn·s·cm(-5), 15%, P < 0.01). The maximal ascending slope in systolic blood pressure decreased (192 mmHg/s, 19%, P = 0.01), suggesting a reduction in left ventricular contractility. Baroreflex sensitivity increased from 9.0 [6.4-14.3] to 13.8 [8.5-19.0] ms/mmHg (median [interquartile range]; P < 0.01) and was inversely correlated with the reductions in heart rate (R = -0.64, P = 0.02) and CO (R = -0.61, P = 0.03). In contrast, changes in body weight were not correlated with changes in either BP or CO. The BP reduction following Roux-and-Y gastric bypass surgery is correlated with a decrease in CO independent of changes in body weight. The contribution of heart rate to the reduction in CO together with enhanced baroreflex sensitivity suggests a shift toward increased parasympathetic cardiovascular control.

  19. Investigational and experimental drugs for intraocular pressure reduction in ocular hypertension and glaucoma.

    PubMed

    Lusthaus, Jed Asher; Goldberg, Ivan

    2016-10-01

    Intraocular pressure (IOP) is the most significant modifiable risk factor to prevent onset or progression of glaucoma. Glaucoma prevalence continues to increase, emphasizing the need for improved ocular hypotensive treatment options. To try to improve on both tolerance and IOP control of currently available therapies, different receptors or mechanisms are being explored to reduce IOP more effectively and to improve tolerance. We review synthetic topical and oral drugs in early development for the management of ocular hypertension and glaucoma. New therapeutic agents for IOP control have been discovered; some appear to be reasonably tolerated. IOP reduction may be limited with some agents, but other benefits although unproven may compensate for this, such as less ocular surface disease, enhanced neuro-protection or increased ocular blood flow. Further product development promises improved treatment options for ocular hypertensives and glaucoma sufferers.

  20. Brinzolamide nanocrystal formulations for ophthalmic delivery: reduction of elevated intraocular pressure in vivo.

    PubMed

    Tuomela, Annika; Liu, Peng; Puranen, Jooseppi; Rönkkö, Seppo; Laaksonen, Timo; Kalesnykas, Giedrius; Oksala, Olli; Ilkka, Jukka; Laru, Johanna; Järvinen, Kristiina; Hirvonen, Jouni; Peltonen, Leena

    2014-06-05

    Nanocrystal-based drug delivery systems provide important tools for ocular formulation development, especially when considering poorly soluble drugs. The objective of the study was to formulate ophthalmic, intraocular pressure (IOP) reducing, nanocrystal suspensions from a poorly soluble drug, brinzolamide (BRA), using a rapid wet milling technique, and to investigate their IOP reducing effect in vivo. Different stabilizers for the nanocrystals were screened (hydroxypropyl methylcellulose (HPMC), poloxamer F127 and F68, polysorbate 80) and HPMC was found to be the only successful stabilizer. In order to investigate both the effect of an added absorption enhancer (polysorbate 80) and the impact of the free drug in the nanocrystal suspension, formulations in phosphate buffered saline (PBS) at pH 7.4 and pH 4.5 were prepared. Particle size, polydispersity (PI), solid state (DSC), morphology (SEM) as well as dissolution behavior and the uniformity of the formulations were characterized. There was rapid dissolution of BRA (in PBS pH 7.4) from all the nanocrystal formulations; after 1 min 100% of the drug was fully dissolved. The effect was significantly pronounced at pH 4.5, where the dissolved fraction of drug was the highest. The cytotoxicity of nanocrystal formulations to human corneal epithelial cell (HCE-T) viability was tested. The effects of the nanocrystal formulations and the commercial product on the cell viability were comparable. The intraocular pressure (IOP) lowering effect was investigated in vivo using a modern rat ocular hypertensive model and elevated IOP reduction was seen in vivo with all the formulations. Notably, the reduction achieved in experimentally elevated IOP was comparable to that obtained with a marketed product. In conclusion, various BRA nanocrystal formulations, which all showed advantageous dissolution and absorption behavior, were successfully formulated. Copyright © 2014 Elsevier B.V. All rights reserved.

  1. Numerical modeling of the simulated gas hydrate production test at Mallik 2L-38 in the pilot scale pressure reservoir LARS - Applying the "foamy oil" model

    NASA Astrophysics Data System (ADS)

    Abendroth, Sven; Thaler, Jan; Klump, Jens; Schicks, Judith; Uddin, Mafiz

    2014-05-01

    In the context of the German joint project SUGAR (Submarine Gas Hydrate Reservoirs: exploration, extraction and transport) we conducted a series of experiments in the LArge Reservoir Simulator (LARS) at the German Research Centre of Geosciences Potsdam. These experiments allow us to investigate the formation and dissociation of hydrates at large scale laboratory conditions. We performed an experiment similar to the field-test conditions of the production test in the Mallik gas hydrate field (Mallik 2L-38) in the Beaufort Mackenzie Delta of the Canadian Arctic. The aim of this experiment was to study the transport behavior of fluids in gas hydrate reservoirs during depressurization (see also Heeschen et al. and Priegnitz et al., this volume). The experimental results from LARS are used to provide details about processes inside the pressure vessel, to validate the models through history matching, and to feed back into the design of future experiments. In experiments in LARS the amount of methane produced from gas hydrates was much lower than expected. Previously published models predict a methane production rate higher than the one observed in experiments and field studies (Uddin et al. 2010; Wright et al. 2011). The authors of the aforementioned studies point out that the current modeling approach overestimates the gas production rate when modeling gas production by depressurization. They suggest that trapping of gas bubbles inside the porous medium is responsible for the reduced gas production rate. They point out that this behavior of multi-phase flow is not well explained by a "residual oil" model, but rather resembles a "foamy oil" model. Our study applies Uddin's (2010) "foamy oil" model and combines it with history matches of our experiments in LARS. Our results indicate a better agreement between experimental and model results when using the "foamy oil" model instead of conventional models of gas flow in water. References Uddin M., Wright J.F. and Coombe D

  2. Late blood pressure reduction in SHR subjected to transient captopril treatment in youth: possible mechanisms.

    PubMed

    Zicha, J; Dobesová, Z; Kunes, J

    2008-01-01

    Spontaneously hypertensive rats (SHR) are characterized by enhanced nifedipine-sensitive component of sympathetic vasoconstriction. Our study tried to elucidate the mechanisms responsible for long-term reduction of blood pressure (BP) in SHR subjected to early transient captopril treatment. Adult untreated SHR aged 30-34 weeks were compared with animals subjected to chronic captopril treatment for 6 weeks either in youth (between 4 and 10 weeks of age) or in adulthood (between 24 and 30 weeks of age). Antihypertensive effects of captopril were more pronounced in young than adult SHR. This was due to greater attenuation of sympathetic and nifedipine-sensitive BP components and prevention of residual BP rise in young captopril-treated SHR in which the reductions of nifedipine-sensitive BP component and residual BP persisted for 20 weeks after captopril withdrawal. The magnitude of nifedipine-sensitive component of sympathetic vasoconstriction is decisive for BP maintenance not only in untreated SHR but also in SHR during active captopril treatment by or after its withdrawal.

  3. A meta-analysis of randomized controlled trials of azilsartan therapy for blood pressure reduction.

    PubMed

    Takagi, Hisato; Mizuno, Yusuke; Niwa, Masao; Goto, Shin-Nosuke; Umemoto, Takuya

    2014-05-01

    Although there have been a number of azilsartan trials, no meta-analysis of the findings has been conducted to date. We performed the first meta-analysis of randomized controlled trials of azilsartan therapy for the reduction of blood pressure (BP) in patients with hypertension. MEDLINE, EMBASE and the Cochrane Central Register of Controlled Trials were searched from the beginning of the records through March 2013 using web-based search engines (PubMed and OVID). Eligible studies were prospective randomized controlled trials of azilsartan (including azilsartan medoxomil) vs. any control therapy that reported clinic or 24-h mean BP as an outcome. For each study, data for the changes from baseline to final clinic systolic BP (SBP) and diastolic BP (DBP) in both the azilsartan group and the control group were used to generate mean differences and 95% confidence intervals (CIs). Of 27 potentially relevant articles screened initially, 7 reports of randomized trials of azilsartan or azilsartan medoxomil therapy enrolling a total of 6152 patients with hypertension were identified and included. Pooled analysis suggested a significant reduction in BP changes among patients randomized to 40 mg of azilsartan vs. control therapy (clinic SBP: -4.20 mm Hg; 95% CI: -6.05 to -2.35 mm Hg; P<0.00001; clinic DBP: -2.58 mm Hg; 95% CI: -3.69 to -1.48 mm Hg; P<0.00001; 24-h mean SBP: -3.33 mm Hg; 95% CI: -4.74 to -1.93 mm Hg; P<0.00001; 24-h mean DBP: -2.12 mm Hg; 95% CI: -2.74 to -1.49 mm Hg; P<0.00001). In conclusion, azilsartan therapy appears to provide a greater reduction in BP than control therapy in patients with hypertension.

  4. Blood pressure reduction in diabetes: lessons from ACCORD, SPRINT and EMPA-REG OUTCOME.

    PubMed

    Sarafidis, Pantelis A; Lazaridis, Antonios A; Ruiz-Hurtado, Gema; Ruilope, Luis M

    2017-06-01

    In patients with diabetes mellitus, the presence of hypertension substantially increases the risk of cardiovascular events, and reductions in blood pressure (BP) can reduce cardiovascular morbidity and mortality. Following evidence from trials randomizing patients to diastolic BP levels, previous guidelines recommended an office BP target of <130/80 mmHg in individuals with diabetes mellitus. However, the evidence for this systolic BP (SBP) target was derived from observational studies. When the results of the ACCORD-BP study showed that those individuals with diabetes mellitus and a target BP of <120 mmHg had a cardiovascular risk that is similar to those with <140 mmHg, all guidelines returned to a recommended SBP of <140 mmHg. However, the ACCORD-BP trial was limited by the low number of cardiovascular events observed, whereas the mean SBP in the 'conventional' arm was 133 mmHg. The SPRINT study, showing cardiovascular benefits in hypertensive patients without diabetes mellitus randomized to SBP <120 mmHg versus those randomized to <140 mmHg, came in contrast with the ACCORD-BP, but a detailed evaluation reveals many similarities between the two trials. Finally, the EMPA-REG OUTCOME study, with impressive cardiovascular mortality reduction with empagliflozin, suggested that reduction of SBP to around 130 mmHg is safe and might explain part of these beneficial results. In this Review, we evaluate the implications of the ACCORD-BP, SPRINT and EMPA-REG OUTCOME trials and previous studies for the optimal BP target in diabetes mellitus.

  5. Effect of longer-term modest salt reduction on blood pressure.

    PubMed

    He, Feng J; Li, Jiafu; Macgregor, Graham A

    2013-04-30

    A reduction in salt intake lowers blood pressure (BP) and, thereby, reduces cardiovascular risk. A recent meta-analysis by Graudal implied that salt reduction had adverse effects on hormones and lipids which might mitigate any benefit that occurs with BP reduction. However, Graudal's meta-analysis included a large number of very short-term trials with a large change in salt intake, and such studies are irrelevant to the public health recommendations for a longer-term modest reduction in salt intake. We have updated our Cochrane meta-analysis. To assess (1) the effect of a longer-term modest reduction in salt intake (i.e. of public health relevance) on BP and whether there was a dose-response relationship; (2) the effect on BP by sex and ethnic group; (3) the effect on plasma renin activity, aldosterone, noradrenaline, adrenaline, cholesterol, low-density lipoprotein (LDL), high-density lipoprotein (HDL) and triglycerides. We searched MEDLINE, EMBASE, Cochrane Hypertension Group Specialised Register, Cochrane Central Register of Controlled Trials, and reference list of relevant articles. We included randomised trials with a modest reduction in salt intake and duration of at least 4 weeks. Data were extracted independently by two reviewers. Random effects meta-analyses, subgroup analyses and meta-regression were performed. Thirty-four trials (3230 participants) were included. Meta-analysis showed that the mean change in urinary sodium (reduced salt vs usual salt) was -75 mmol/24-h (equivalent to a reduction of 4.4 g/d salt), the mean change in BP was -4.18 mmHg (95% CI: -5.18 to -3.18, I (2)=75%) for systolic and -2.06 mmHg (95% CI: -2.67 to -1.45, I (2)=68%) for diastolic BP. Meta-regression showed that age, ethnic group, BP status (hypertensive or normotensive) and the change in 24-h urinary sodium were all significantly associated with the fall in systolic BP, explaining 68% of the variance between studies. A 100 mmol reduction in 24 hour urinary sodium (6 g

  6. Numerical investigation of a coupled moving boundary model of radial flow in low-permeable stress-sensitive reservoir with threshold pressure gradient

    NASA Astrophysics Data System (ADS)

    Wen-Chao, Liu; Yue-Wu, Liu; Cong-Cong, Niu; Guo-Feng, Han; Yi-Zhao, Wan

    2016-02-01

    The threshold pressure gradient and formation stress-sensitive effect as the two prominent physical phenomena in the development of a low-permeable reservoir are both considered here for building a new coupled moving boundary model of radial flow in porous medium. Moreover, the wellbore storage and skin effect are both incorporated into the inner boundary conditions in the model. It is known that the new coupled moving boundary model has strong nonlinearity. A coordinate transformation based fully implicit finite difference method is adopted to obtain its numerical solutions. The involved coordinate transformation can equivalently transform the dynamic flow region for the moving boundary model into a fixed region as a unit circle, which is very convenient for the model computation by the finite difference method on fixed spatial grids. By comparing the numerical solution obtained from other different numerical method in the existing literature, its validity can be verified. Eventually, the effects of permeability modulus, threshold pressure gradient, wellbore storage coefficient, and skin factor on the transient wellbore pressure, the derivative, and the formation pressure distribution are analyzed respectively. Project supported by the National Natural Science Foundation of China (Grant No. 51404232), the China Postdoctoral Science Foundation (Grant No. 2014M561074), and the National Science and Technology Major Project, China (Grant No. 2011ZX05038003).

  7. Pressure pyrolysed non-precious oxygen reduction catalysts for proton exchange membrane fuel cells

    NASA Astrophysics Data System (ADS)

    Nallathambi, Vijayadurga

    2011-12-01

    Worldwide energy demand has driven long-term efforts towards developing a clean, hydrogen-based energy economy. Polymer electrolyte membrane fuel cells (PEMFC) are low emissions and high efficiency devices that utilize the power of hydrogen and are a key enabling technology for the hydrogen economy. Carbon supported platinum-black is the state-of the art catalyst for oxygen reduction in a PEMFC because it can withstand the acidic environment. However, the high cost and low abundance of this precious metal has limited large-scale commercialization of PEMFCs. Current efforts focus on developing alternative inexpensive, non-noble metal-based catalysts for oxygen reduction with performance comparable to conventional platinum based electrocatalysts. In this work, inexpensive metal-nitrogen-carbon (MNC) catalysts have been synthesized by pyrolyzing transition metal and nitrogen precursors together with high surface area carbon materials in a closed, constant-volume quartz tube. High pressure generated due to nitrogen precursor evaporation lead to increased surface nitrogen content in the catalysts post-pyrolysis. Electrochemical oxygen reduction activity of MNC catalysts was analyzed using half-cell Rotating Ring Disc Electrode (RRDE) studies. The effect of nitrogen precursor morphology on the generation of active sites has been explored in detail. By increasing the Nitrogen/Carbon ratio of the nitrogen precursor, the accessible active site density increased by reducing carbon deposition in the pores of the carbon support during pyrolysis. The most active catalysts were obtained using melamine, having a N/C ratio of 2. Single PEMFC measurements employing MNC catalysts as cathodes indicated kinetic current density as high as 15 A cm-3 at 0.8 ViR-free and over 100 h of stable current at 0.5 V were observed. Effects of carbon free ammonia generating solid nitrogen precursors such as urea and ammonium carbamate were also studied. These precursors etched the carbon support

  8. Phytoplankton Composition and Abundance in Restored Maltański Reservoir under the Influence of Physico-Chemical Variables and Zooplankton Grazing Pressure.

    PubMed

    Kozak, Anna; Gołdyn, Ryszard; Dondajewska, Renata

    2015-01-01

    In this paper we present the effects of environmental factors and zooplankton food pressure on phytoplankton in the restored man-made Maltański Reservoir (MR). Two methods of restoration: biomanipulation and phosphorus inactivation have been applied in the reservoir. Nine taxonomical groups of phytoplankton represented in total by 183 taxa were stated there. The richest groups in respect of taxa number were green algae, cyanobacteria and diatoms. The diatoms, cryptophytes, chrysophytes, cyanobacteria, green algae and euglenophytes dominated in terms of abundance and/or biomass. There were significant changes among environmental parameters resulting from restoration measures which influenced the phytoplankton populations in the reservoir. These measures led to a decrease of phosphorus concentration due to its chemical inactivation and enhanced zooplankton grazing as a result of planktivorous fish stocking. The aim of the study is to analyse the reaction of phytoplankton to the restoration measures and, most importantly, to determine the extent to which the qualitative and quantitative composition of phytoplankton depends on variables changing under the influence of restoration in comparison with other environmental variables. We stated that application of restoration methods did cause significant changes in phytoplankton community structure. The abundance of most phytoplankton taxa was negatively correlated with large zooplankton filter feeders, and positively with zooplankton predators and concentrations of ammonium nitrogen and partly of phosphates. However, restoration was insufficient in the case of decreasing phytoplankton abundance. The effects of restoration treatments were of less importance for the abundance of phytoplankton than parameters that were independent of the restoration. This was due to the continuous inflow of large loads of nutrients from the area of the river catchment.

  9. Phytoplankton Composition and Abundance in Restored Maltański Reservoir under the Influence of Physico-Chemical Variables and Zooplankton Grazing Pressure

    PubMed Central

    Kozak, Anna; Gołdyn, Ryszard; Dondajewska, Renata

    2015-01-01

    In this paper we present the effects of environmental factors and zooplankton food pressure on phytoplankton in the restored man-made Maltański Reservoir (MR). Two methods of restoration: biomanipulation and phosphorus inactivation have been applied in the reservoir. Nine taxonomical groups of phytoplankton represented in total by 183 taxa were stated there. The richest groups in respect of taxa number were green algae, cyanobacteria and diatoms. The diatoms, cryptophytes, chrysophytes, cyanobacteria, green algae and euglenophytes dominated in terms of abundance and/or biomass. There were significant changes among environmental parameters resulting from restoration measures which influenced the phytoplankton populations in the reservoir. These measures led to a decrease of phosphorus concentration due to its chemical inactivation and enhanced zooplankton grazing as a result of planktivorous fish stocking. The aim of the study is to analyse the reaction of phytoplankton to the restoration measures and, most importantly, to determine the extent to which the qualitative and quantitative composition of phytoplankton depends on variables changing under the influence of restoration in comparison with other environmental variables. We stated that application of restoration methods did cause significant changes in phytoplankton community structure. The abundance of most phytoplankton taxa was negatively correlated with large zooplankton filter feeders, and positively with zooplankton predators and concentrations of ammonium nitrogen and partly of phosphates. However, restoration was insufficient in the case of decreasing phytoplankton abundance. The effects of restoration treatments were of less importance for the abundance of phytoplankton than parameters that were independent of the restoration. This was due to the continuous inflow of large loads of nutrients from the area of the river catchment. PMID:25906352

  10. Reinjection into geothermal reservoirs

    SciTech Connect

    Bodvarsson, G.S.; Stefansson, V.

    1987-08-01

    Reinjection of geothermal wastewater is practiced as a means of disposal and for reservoir pressure support. Various aspects of reinjection are discussed, both in terms of theoretical studies as well as specific field examples. The discussion focuses on the major effects of reinjection, including pressure maintenance and chemical and thermal effects. (ACR)

  11. Pressure dependence of the oxygen reduction reaction at the platinum microelectrode/nafion interface - Electrode kinetics and mass transport

    NASA Technical Reports Server (NTRS)

    Parthasarathy, Arvind; Srinivasan, Supramaniam; Appleby, A. J.; Martin, Charles R.

    1992-01-01

    The investigation of oxygen reduction kinetics at the platinum/Nafion interface is of great importance in the advancement of proton-exchange-membrane (PEM) fuel-cell technology. This study focuses on the dependence of the oxygen reduction kinetics on oxygen pressure. Conventional Tafel analysis of the data shows that the reaction order with respect to oxygen is unity at both high and low current densities. Chronoamperometric measurements of the transport parameters for oxygen in Nafion show that oxygen dissolution follows Henry's isotherm. The diffusion coefficient of oxygen is invariant with pressure; however, the diffusion coefficient for oxygen is lower when air is used as the equilibrating gas as compared to when oxygen is used for equilibration. These results are of value in understanding the influence of O2 partial pressure on the performance of PEM fuel cells and also in elucidating the mechanism of oxygen reduction at the platinum/Nafion interface.

  12. Evolution of the Cerro Prieto reservoirs under exploitation

    SciTech Connect

    Truesdell, A.H.; Lippmann, M.J.; Puente, H.G.

    1997-07-01

    The Cerro Prieto Geothermal field of Baja California (Mexico) has been under commercial production to generate electricity since 1973. Over the years, the large amount of Geothermal fluids extracted (at present about 12,000 tons per hour) to supply steam to the power plants has resulted in a reduction of pressures, changes in reservoir processes, and increased flow of cooler groundwater into the geothermal system. The groundwater recharging the reservoir moves horizontally through permeable layers, as well as vertically through permeable fault zones. In addition, the supply of deep hot waters has continued unabated, and perhaps has increased as reservoir pressure decreased. Since 1989, this natural fluid recharge has been supplemented by injection which presently amounts to about 20% of the fluid produced. Changes in the chemical and physical characteristics of the reservoir fluids due to the drop in pressures and the inflow of cooler groundwaters and injectate have been detected on the basis of wellhead data. These changes point to reservoir processes like local boiling, phase segregation, steam condensation, mixing and dilution. Finally, the study identified areas where fluids are entering the reservoir, as well as indicated their source (i.e. natural Groundwater recharge versus injectate) and established the controlling geologic structures.

  13. Forensic analysis of crib mattress properties on pediatric CPR quality--can we balance pressure reduction with CPR effectiveness?

    PubMed

    Niles, Dana E; Maltese, Matthew R; Nishisaki, Akira; Seacrist, Thomas; Leffelman, Jessica; Hutchins, Larissa; Schneck, Nancy; Sutton, Robert M; Arbogast, Kristy B; Berg, Robert A; Nadkarni, Vinay M

    2013-08-01

    Single mode, pressure reduction (PR) crib mattresses are increasingly employed in hospitals to prevent skin injury and infection. However, single mode PR mattresses risk large mattress deflection during CPR chest compressions, potentially leading to inadequate chest compressions. New, dual mode PR crib mattress technology provides less mattress deflection during chest compressions (CCs) with similar PR characteristics for prevention of skin injury. Epochs of 50 high-quality CCs (target sternum-spine compression depth ≥ 38 mm) guided by real-time force/deflection sensor (FDS) feedback were delivered to CPR manikin with realistic CC characteristics on two PR crib mattresses for four conditions: (1) single mode+backboard; (2) dual mode+backboard; (3) single mode-no backboard; and (4) dual mode-no backboard. Mattress displacement was measured using surface reference accelerometers. Mattress displacement ≥ 5 mm was prospectively defined as minimal clinically important difference. PR qualities of both mattresses were assessed by tissue interface pressure mapping. During simulated high quality CC, single mode had significantly more mattress displacement compared to dual mode (mean difference 16.5 ± 1.4mm, p<0.0001) with backboard. This difference was greater when no backboard was used (mean difference 31.7 ± 1.5mm, p<0.0001). Both single mode and dual mode met PR industry guidelines (mean surface pressure <50 mm Hg). Chest compressions delivered on dual mode pressure reduction crib mattresses resulted in substantially smaller mattress deflection compared to single mode pressure reduction mattresses. Skin pressure reduction qualities of dual mode pressure reduction crib mattress were maintained. We recommend that backboards continue to be used in order to mitigate mattress deflection during CPR on soft mattresses. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

  14. Use of Acetate, Propionate, and Butyrate for Reduction of Nitrate and Sulfate and Methanogenesis in Microcosms and Bioreactors Simulating an Oil Reservoir.

    PubMed

    Chen, Chuan; Shen, Yin; An, Dongshan; Voordouw, Gerrit

    2017-04-01

    Acetate, propionate, and butyrate (volatile fatty acids [VFA]) occur in oil field waters and are frequently used for microbial growth of oil field consortia. We determined the kinetics of use of these VFA components (3 mM each) by an anaerobic oil field consortium in microcosms containing 2 mM sulfate and 0, 4, 6, 8, or 13 mM nitrate. Nitrate was reduced first, with a preference for acetate and propionate. Sulfate reduction then proceeded with propionate (but not butyrate) as the electron donor, whereas the fermentation of butyrate (but not propionate) was associated with methanogenesis. Microbial community analyses indicated that Paracoccus and Thauera (Paracoccus-Thauera), Desulfobulbus, and Syntrophomonas-Methanobacterium were the dominant taxa whose members catalyzed these three processes. Most-probable-number assays showed the presence of up to 10(7)/ml of propionate-oxidizing sulfate-reducing bacteria (SRB) in waters from the Medicine Hat Glauconitic C field. Bioreactors with the same concentrations of sulfate and VFA responded similarly to increasing concentrations of injected nitrate as observed in the microcosms: sulfide formation was prevented by adding approximately 80% of the nitrate dose needed to completely oxidize VFA to CO2 in both. Thus, this work has demonstrated that simple time-dependent observations of the use of acetate, propionate, and butyrate for nitrate reduction, sulfate reduction, and methanogenesis in microcosms are a good proxy for these processes in bioreactors, monitoring of which is more complex.IMPORTANCE Oil field volatile fatty acids acetate, propionate, and butyrate were specifically used for nitrate reduction, sulfate reduction, and methanogenic fermentation. Time-dependent analyses of microcosms served as a good proxy for these processes in a bioreactor, mimicking a sulfide-producing (souring) oil reservoir: 80% of the nitrate dose required to oxidize volatile fatty acids to CO2 was needed to prevent souring in both. Our data

  15. Provocative intraocular pressure challenge preferentially decreases venous oxygen saturation despite no reduction in blood flow.

    PubMed

    O'Connell, Rachael A; Anderson, Andrew J; Hosking, Sarah L; Bui, Bang V

    2015-03-01

    Ocular disease can both alter the retina's oxygen requirements, and decrease its ability to cope with changes in metabolic demand. We examined the influence of a moderate intraocular pressure (IOP) elevation on three outcome measures: arterial and venous oxygen saturation, blood flow, and the pattern electroretinogram (PERG). We increased IOP to ˜30 mmHg in 23 healthy participants (22-39 years) using a mechanical probe applied to the eyelid, thereby lowering ocular perfusion pressure (OPP) by ~30%. The Oxymap retinal oximeter was used to measure oxygen saturation for arteries and veins. Blood flow, volume and velocity were measured using the Heidelberg retinal flowmeter and steady-state PERG waveforms (8.34 Hz) were recorded bilaterally (200 sweeps). For each outcome measure, data was obtained three times: at baseline, 1 min into sustained IOP elevation, and 1 min after the probe was removed. During IOP elevation, changes in oxygen saturation of retinal arteries failed to reach statistical significance [F(1,30) = 3.69, p = 0.05], whereas venous oxygen saturation was significantly reduced [F(1,21) = 27.43, p < 0.01]. Blood flow increased slightly [F(2,40) = 6.28, p < 0.0001], PERG amplitude significantly reduced [F(2,44) = 24.24, p < 0.0001] and PERG phase was significantly delayed [F(2,44) = 17.00, p < 0.0001]. Contralateral eyes were unchanged. OPP reduction correlated little with PERG amplitude, PERG phase or venous oxygen saturation. Mild, acute IOP elevation increases arterio-venous oxygen saturation differences primarily through lowering venous oxygen saturation, suggesting increased oxygen consumption by healthy neurons when physiologically stressed. © 2014 The Authors Ophthalmic & Physiological Optics © 2014 The College of Optometrists.

  16. Human norovirus surrogate reduction in milk and juice blends by high pressure homogenization.

    PubMed

    Horm, Katie Marie; Harte, Federico Miguel; D'Souza, Doris Helen

    2012-11-01

    Novel processing technologies such as high pressure homogenization (HPH) for the inactivation of foodborne viruses in fluids that retain nutritional attributes are in high demand. The objectives of this research were (i) to determine the effects of HPH alone or with an emulsifier (lecithin) on human norovirus surrogates-murine norovirus (MNV-1) and feline calicivirus (FCV-F9)-in skim milk and orange juice, and (ii) to determine HPH effects on FCV-F9 and MNV-1 in orange and pomegranate juice blends. Experiments were conducted in duplicate at 0, 100, 200, 250, and 300 MPa for <2 s and plaque was assayed in duplicate. In milk, FCV-F9 was reduced by ≥4 and ∼1.3 log PFU/ml at 300 and 250 MPa, respectively, and ≥4- and ∼1-log PFU/ml reductions were obtained in orange juice at 300 and 250 MPa, respectively. In orange juice or milk combined with lecithin, FCV-F9 was reduced to nondetectable levels at 300 MPa, and by 1.77 and 0.78 log PFU/ml at 250 MPa. MNV-1 in milk was reduced by ∼1.3 log PFU/ml only at 300 MPa, and by ∼0.8 and ∼0.4 log PFU/ml in orange juice at 300 and 250 MPa, respectively. MNV-1 in milk or orange juice containing lecithin at 300 MPa showed 1.32- and 2.5-log PFU/ml reductions, respectively. In the pomegranate-orange juice blend, FCV-F9 was completely reduced, and MNV-1 was reduced by 1.04 and 1.78 log PFU/ml at 250 and 300 MPa, respectively. These results show that HPH has potential for commercial use to inactivate foodborne virus surrogates in juices.

  17. Blood pressure reduction and noncontrast CT markers of intracerebral hemorrhage expansion.

    PubMed

    Morotti, Andrea; Boulouis, Gregoire; Romero, Javier M; Brouwers, H Bart; Jessel, Michael J; Vashkevich, Anastasia; Schwab, Kristin; Afzal, Mohammad Rauf; Cassarly, Christy; Greenberg, Steven M; Martin, Reneé Hebert; Qureshi, Adnan I; Rosand, Jonathan; Goldstein, Joshua N

    2017-08-08

    To validate various noncontrast CT (NCCT) predictors of hematoma expansion in a large international cohort of ICH patients and investigate whether intensive blood pressure (BP) treatment reduces ICH growth and improves outcome in patients with these markers. We analyzed patients enrolled in the Antihypertensive Treatment of Acute Cerebral Hemorrhage II (ATACH-II) randomized controlled trial. Participants were assigned to intensive (systolic BP <140 mm Hg) vs standard (systolic BP <180 mm Hg) treatment within 4.5 hours from onset. The following NCCT markers were identified: intrahematoma hypodensities, black hole sign, swirl sign, blend sign, heterogeneous hematoma density, and irregular shape. ICH expansion was defined as hematoma growth >33% and unfavorable outcome was defined as modified Rankin Scale score >3 at 90 days. Logistic regression was used to identify predictors of ICH expansion and explore the association between NCCT signs and clinical benefit from intensive BP treatment. A total of 989 patients were included (mean age 62 years, 61.9% male), of whom 186/869 experienced hematoma expansion (21.4%) and 361/952 (37.9%) had unfavorable outcome. NCCT markers independently predicted ICH expansion (all p < 0.01) with overall accuracy ranging from 61% to 78% and good interrater reliability (k > 0.6 for all markers). There was no evidence of an interaction between NCCT markers and benefit from intensive BP reduction (all p for interaction >0.10). NCCT signs reliably identify ICH patients at high risk of hematoma growth. However, we found no evidence that patients with these markers specifically benefit from intensive BP reduction. NCT01176565. © 2017 American Academy of Neurology.

  18. Sustained sympathetic and blood pressure reduction 1 year after renal denervation in patients with resistant hypertension.

    PubMed

    Hering, Dagmara; Marusic, Petra; Walton, Antony S; Lambert, Elisabeth A; Krum, Henry; Narkiewicz, Krzysztof; Lambert, Gavin W; Esler, Murray D; Schlaich, Markus P

    2014-07-01

    Renal denervation (RDN) reduces muscle sympathetic nerve activity (MSNA) and blood pressure (BP) in resistant hypertension. Although a persistent BP-lowering effect has been demonstrated, the long-term effect on MSNA remains elusive. We investigated whether RDN influences MSNA over time. Office BP and MSNA were obtained at baseline, 3, 6, and 12 months after RDN in 35 patients with resistant hypertension. Office BP averaged 166±22/88±19 mm Hg, despite the use of an average of 4.8±2.1 antihypertensive drugs. Baseline MSNA was 51±11 bursts/min ≈2- to 3-fold higher than the level observed in healthy controls. Mean office systolic and diastolic BP significantly decreased by -12.6±18.3/-6.5±9.2, -16.1±25.6/-8.6±12.9, and -21.2±29.1/-11.1±12.9 mm Hg (P<0.001 for both systolic BP and diastolic BP) with RDN at 3-, 6-, and 12-month follow-up, respectively. MSNA was reduced by -8±12, -6±12, and -6±11 bursts/min (P<0.01) at 3-, 6-, and 12-month follow-up. The reduction in MSNA was maintained, despite a progressive fall in BP over time. No such changes were observed in 7 control subjects at 6-month follow-up. These findings confirm previous reports on the favorable effects of RDN on elevated BP and demonstrate sustained reduction of central sympathetic outflow ≤1-year follow-up in patients with resistant hypertension and high baseline MSNA. These observations are compatible with the hypothesis of a substantial contribution of afferent renal nerve signaling to increased BP in resistant hypertension and argue against a relevant reinnervation at 1 year after procedure.

  19. Relationship between corneal hysteresis and lamina cribrosa displacement after medical reduction of intraocular pressure

    PubMed Central

    Perez-Lopez, Marta; Palacios-Pozo, Elena; Davo-Cabrera, Juan

    2017-01-01

    Purpose To evaluate the relationship between the displacement of the lamina cribrosa (LC) and prelaminar tissue with corneal hysteresis (CH) using spectral-domain coherence tomography (SD-OCT) after reducing intraocular pressure (IOP) with medical treatment. Methods Sixty-one eyes of 61 patients with ocular hypertension or primary open-angle glaucoma who were going to start with treatment were imaged by means of 12 cross-sectional scans of the optic nerve using enhanced depth imaging SD-OCT before and after 1 week of treatment. We used the ‘follow-up’ mode to make sure that all the measurements were performed in the same location. We also measured the CH using an Ocular Response Analyzer, and we related it to the magnitude of displacement of LC and prelaminar tissue and the thickness of both structures. Results There was a significant variation of LC thickness from 132.66±37.40 to 160.09±41.13 µm (p<0001). LC distance was significantly reduced from 258.53±145 µm before treatment to 239.86±135 µm after it. No significant changes were found in the thickness and movement of prelaminar tissue before and after treatment. The only factors related with LC displacement were CH (R2=0.48) and age (R2=0.42). Conclusions A significant increase in LC thickness and a reduction in the posterior displacement of LC but not in the prelaminar tissue were demonstrated after IOP reduction with medical treatment. The factors most related with LC displacement were age and CH. PMID:27474156

  20. Seal assessment and estimated storage capacities of a targeted CO2 reservoir based on new displacement pressures in SW Wyoming, U.S.A.

    NASA Astrophysics Data System (ADS)

    Spaeth, Lynsey; Campbell-Stone, Erin; Lynds, Ranie; Frost, Carol; McLaughlin, J. Fred

    2013-04-01

    single wetting phase at elevated pressures and temperatures, resulting in an interfacial tension of 0 milliNewton/meter. Under these conditions the pore throat radius of sealing units is assumed to be the principle inhibitor to flow through the seal. Experimental data indicate pore throat radii range from 39.2 to 113.5 nanometers in the confining system, and preliminary column height calculations indicate that, depending on the size of the plume, reservoir thickness will most likely be the limiting factor to the amount of CO2 that can be sequestered rather than the column height.

  1. 49 CFR 393.50 - Reservoirs required.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... pressure or vacuum below 70 percent of that indicated by the air or vacuum gauge immediately before the.... Each service reservoir system on a motor vehicle shall be protected against a loss of air pressure or... NECESSARY FOR SAFE OPERATION Brakes § 393.50 Reservoirs required. (a) Reservoir capacity for air-braked...

  2. 49 CFR 393.50 - Reservoirs required.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... pressure or vacuum below 70 percent of that indicated by the air or vacuum gauge immediately before the.... Each service reservoir system on a motor vehicle shall be protected against a loss of air pressure or... NECESSARY FOR SAFE OPERATION Brakes § 393.50 Reservoirs required. (a) Reservoir capacity for air-braked...

  3. 49 CFR 393.50 - Reservoirs required.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... pressure or vacuum below 70 percent of that indicated by the air or vacuum gauge immediately before the.... Each service reservoir system on a motor vehicle shall be protected against a loss of air pressure or... NECESSARY FOR SAFE OPERATION Brakes § 393.50 Reservoirs required. (a) Reservoir capacity for air-braked...

  4. 49 CFR 393.50 - Reservoirs required.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... pressure or vacuum below 70 percent of that indicated by the air or vacuum gauge immediately before the.... Each service reservoir system on a motor vehicle shall be protected against a loss of air pressure or... NECESSARY FOR SAFE OPERATION Brakes § 393.50 Reservoirs required. (a) Reservoir capacity for air-braked...

  5. Uncertainty quantification for evaluating impacts of caprock and reservoir properties on pressure buildup and ground surface displacement during geological CO2 sequestration

    SciTech Connect

    Bao, Jie; Hou, Zhangshuan; Fang, Yilin; Ren, Huiying; Lin, Guang

    2013-08-12

    A series of numerical test cases reflecting broad and realistic ranges of geological formation properties was developed to systematically evaluate and compare the impacts of those properties on geomechanical responses to CO2 injection. A coupled hydro-geomechanical subsurface transport simulator, STOMP (Subsurface Transport over Multiple Phases), was adopted to simulate the CO2 migration process and geomechanical behaviors of the surrounding geological formations. A quasi-Monte Carlo sampling method was applied to efficiently sample a high-dimensional parameter space consisting of injection rate and 14 subsurface formation properties, including porosity, permeability, entry pressure, irreducible gas and aqueous saturation, Young’s modulus, and Poisson’s ratio for both reservoir and caprock. Generalized cross-validation and analysis of variance methods were used to quantitatively measure the significance of the 15 input parameters. Reservoir porosity, permeability, and injection rate were found to be among the most significant factors affecting the geomechanical responses to the CO2 injection. We used a quadrature generalized linear model to build a reduced-order model that can estimate the geomechanical response instantly instead of running computationally expensive numerical simulations. The injection pressure and ground surface displacement are often monitored for injection well safety, and are believed can partially reflect the risk of fault reactivation and seismicity. Based on the reduced order model and response surface, the input parameters can be screened for control the risk of induced seismicity. The uncertainty of the subsurface structure properties cause the numerical simulation based on a single or a few samples does not accurately estimate the geomechanical response in the actual injection site. Probability of risk can be used to evaluate and predict the risk of injection when there are great uncertainty in the subsurface properties and operation

  6. Influence of Titration of Neurohormonal Antagonists and Blood Pressure Reduction on Renal Function and Decongestion in Decompensated Heart Failure

    PubMed Central

    Wilson, F. Perry; Brisco, Meredith A.; Bellumkonda, Lavanya; Jacoby, Daniel; Coca, Steven G.; Parikh, Chirag R.; Tang, W.H. Wilson; Testani, Jeffrey M.

    2015-01-01

    Background Reduction in systolic blood pressure (SBP reduction) during the treatment of acute decompensated heart failure (ADHF) is strongly and independently associated with worsening renal function (WRF). Our objective was to determine if SBP reduction or titration of oral neurohormonal antagonists during ADHF treatment negatively influences diuresis and decongestion. Methods and Results SBP reduction was evaluated from admission to discharge in consecutive ADHF admissions (n=656). Diuresis and decongestion was examined across a range of parameters such as diuretic efficiency, fluid output, hemoconcentration, and diuretic dose. The average reduction in SBP was 14.4 ± 19.4 mmHg and 77.6% of the population had discharge SBP lower than admission. SBP reduction was strongly associated with WRF (OR=1.9, 95% CI: 1.2-2.9, p=0.004), a finding that persisted after adjusting for parameters of diuresis and decongestion (OR=2.0, 95% CI: 1.3-3.2, p=0.002). However, SBP reduction did not negatively impact diuresis or decongestion (p≥0.25 for all parameters). Uptitration of neurohormonal antagonists occurred in over 50% of admissions and was associated with a modest additional reduction in blood pressure (≤ 5.6 mmHg). Notably, WRF was not increased and diuretic efficiency was significantly improved with the uptitration of neurohormonal antagonists. Conclusions Despite a higher rate of WRF, blood pressure reduction was not associated with worsening of diuresis or decongestion. Furthermore, titration of oral neurohormonal antagonists was actually associated with improved diuresis in this cohort. These results provide reassurance that the guideline recommended titration of chronic oral medication during ADHF hospitalization may not be antagonistic to the short-term goal of decongestion. PMID:26699390

  7. Oleic acid content is responsible for the reduction in blood pressure induced by olive oil.

    PubMed

    Terés, S; Barceló-Coblijn, G; Benet, M; Alvarez, R; Bressani, R; Halver, J E; Escribá, P V

    2008-09-16

    Numerous studies have shown that high olive oil intake reduces blood pressure (BP). These positive effects of olive oil have frequently been ascribed to its minor components, such as alpha-tocopherol, polyphenols, and other phenolic compounds that are not present in other oils. However, in this study we demonstrate that the hypotensive effect of olive oil is caused by its high oleic acid (OA) content (approximately 70-80%). We propose that olive oil intake increases OA levels in membranes, which regulates membrane lipid structure (H(II) phase propensity) in such a way as to control G protein-mediated signaling, causing a reduction in BP. This effect is in part caused by its regulatory action on G protein-associated cascades that regulate adenylyl cyclase and phospholipase C. In turn, the OA analogues, elaidic and stearic acids, had no hypotensive activity, indicating that the molecular mechanisms that link membrane lipid structure and BP regulation are very specific. Similarly, soybean oil (with low OA content) did not reduce BP. This study demonstrates that olive oil induces its hypotensive effects through the action of OA.

  8. Mechanism of coronary flow reserve reduction in systemic sclerosis: insight from intracoronary pressure wire studies.

    PubMed

    Pintér, Tünde; Faludi, Réka; Magyari, Balázs; Vorobcsuk, András; Kumánovics, Gábor; Minier, Tünde; Czirják, László; Komócsi, András

    2011-04-01

    Functional impairment of coronary microcirculation is thought to be a major pathway in the development of primary cardiac involvement in SSc; however, the underlying mechanism is not fully understood. We aimed to investigate the mechanisms of coronary flow reserve (CFR) reduction in patients with SSc. Seventeen SSc patients and 17 gender- and age-matched controls were enrolled. Coronary angiography and determination of coronary flow parameters including index of myocardial resistance (IMR) using intracoronary pressure wire at basal conditions and during vasodilator-induced maximal hyperaemia were performed. Transit times of repeated intracoronary saline injection were measured to evaluate the role of cold exposure. SSc patients with decreased CFR had accelerated basal coronary flow velocity (P < 0.05), and their IMR in hyperaemia (IMR(hyp)) did not differ from either SSc patients with normal CFR or from the controls (P = 0.292 and P =  0.308). The coronary flow velocity of SSc patients correlated with the IMR at baseline (IMR(bas)) (r  = 0.56, P  = 0.019). Injection of room temperature saline did not provoke changes in coronary transit times. The lack of decrease in the maximal vasodilatation response indicates that there is no irreversible functional damage at the level of the coronary arterioles. In patients with reduced CFR, the decreased basal IMR and higher velocity reflect compensatory vasodilatory mechanisms probably triggered by ischaemic signals deriving from abnormal myocardial microcirculation.

  9. Reduction in lateral lipid mobility of lipid bilayer membrane by atmospheric pressure plasma irradiation

    NASA Astrophysics Data System (ADS)

    Suda, Yoshiyuki; Tero, Ryugo; Yamashita, Ryuma; Yusa, Kota; Takikawa, Hirofumi

    2016-03-01

    Plasma medicine is an emerging research field in which various applications of electrical discharge, especially in the form of nonequilibrium plasma at atmospheric pressure, are examined, for example, the application of plasma to biological targets for various purposes such as selective killing of tumor cells and blood stanching. We have focused on the behavior of an artificial cell membrane system at the solid-liquid interface. To evaluate the lateral lipid mobility, we measured the diffusion coefficient of the supported lipid bilayer (SLB) composed of dioleoylphosphatidylcholine with fluorescence recovery after photobleaching by confocal laser scanning microscopy. It was found that the diffusion coefficient was decreased by plasma irradiation and that the diffusion coefficient decreasing rate proceeded with increasing plasma power. We investigated the effects of stimulation with an equilibrium chemical, H2O2, on the SLB and confirmed that the diffusion coefficient did not change at least up to a H2O2 concentration of 5 mM. These results indicate that transient active species generated by plasma play critical roles in the reduction in SLB fluidity. The effects of the two generated major oxidized lipid species, hydroxyl- or hydroperoxy-phosphatidylcholine (PC) and acyl-chain-truncated PCs terminated with aldehyde or carboxyl group, on lateral lipid mobility are discussed.

  10. Use of negative-pressure dressings and split-thickness skin grafts following penile shaft reduction and reduction scrotoplasty in the management of penoscrotal elephantiasis.

    PubMed

    Stokes, Tracey H; Follmar, Keith E; Silverstein, Ari D; Weizer, Alon Z; Donatucci, Craig F; Anderson, Everett E; Erdmann, Detlev

    2006-06-01

    From 1988 to 2005, 8 men who presented with penoscrotal elephantiasis underwent penile shaft degloving and reduction scrotoplasty, followed by transplantation of a split-thickness skin graft (STSG) to the penile shaft. The etiology of elephantiasis in these patients included self-injection of viscous fluid and postsurgical obstructive lymphedema. In the 6 most recent cases, negative-pressure dressings were applied over the STSG to promote graft take, and STSG take rate was 100%. The results of our series corroborate those of a previous report, which showed circumferential negative-pressure dressings to be safe and efficacious in bolstering STSGs to the penile shaft. Furthermore, these results suggest that the use of negative-pressure dressings may improve graft take in this patient population.

  11. Sedimentary reservoir oxidation during geologic CO2 sequestration

    NASA Astrophysics Data System (ADS)

    Lammers, Laura N.; Brown, Gordon E.; Bird, Dennis K.; Thomas, Randal B.; Johnson, Natalie C.; Rosenbauer, Robert J.; Maher, Katharine

    2015-04-01

    Injection of carbon dioxide into subsurface geologic reservoirs during geologic carbon sequestration (GCS) introduces an oxidizing supercritical CO2 phase into a subsurface geologic environment that is typically reducing. The resulting redox disequilibrium provides the chemical potential for the reduction of CO2 to lower free energy organic species. However, redox reactions involving carbon typically require the presence of a catalyst. Iron oxide minerals, including magnetite, are known to catalyze oxidation and reduction reactions of C-bearing species. If the redox conditions in the reservoir are modified by redox transformations involving CO2, such changes could also affect mineral stability, leading to dissolution and precipitation reactions and alteration of the long-term fate of CO2 in GCS reservoirs. We present experimental evidence that reservoirs with reducing redox conditions are favorable environments for the relatively rapid abiotic reduction of CO2 to organic molecules. In these experiments, an aqueous suspension of magnetite nanoparticles was reacted with supercritical CO2 under pressure and temperature conditions relevant to GCS in sedimentary reservoirs (95-210 °C and ∼100 bars of CO2). Hydrogen production was observed in several experiments, likely caused by Fe(II) oxidation either at the surface of magnetite or in the aqueous phase. Heating of the Fe(II)-rich system resulted in elevated PH2 and conditions favorable for the reduction of CO2 to acetic acid. Implications of these results for the long-term fate of CO2 in field-scale systems were explored using reaction path modeling of CO2 injection into reservoirs containing Fe(II)-bearing primary silicate minerals, with kinetic parameters for CO2 reduction obtained experimentally. The results of these calculations suggest that the reaction of CO2 with reservoir constituents will occur in two primary stages (1) equilibration of CO2 with organic acids resulting in mineral-fluid disequilibrium, and

  12. Reservoir limnology

    SciTech Connect

    Thornton, K.W.; Kimmel, B.L.; Payne, F.E.

    1990-01-01

    This book addresses reservoirs as unique ecological systems and presents research indicating that reservoirs fall into two or three highly concatenated, interactive ecological systems ranging from riverine to lacustrine or hybrid systems. Includes some controversial concepts about the limnology of reservoirs.

  13. Void reduction in autoclave processing of thermoset composites. I - High pressure effects on void reduction. II - Void reduction in a microwave curing process

    NASA Astrophysics Data System (ADS)

    Boey, F. Y. C.; Lye, S. W.

    1992-07-01

    Two novel methods for reducing void levels in thermoset composites are reported. The first procedure, which eliminates vacuum application, uses high pressure of up to 7000 kPa, by means of an isostatic press, effectively reducing the void levels to below 3 percent. The second process uses microwave curing by means of a modified approach involving vacuum bagging and applied autoclave pressure. This process achieves a void level of 4 percent.

  14. Reduction of intraocular pressure and glaucoma progression: results from the Early Manifest Glaucoma Trial.

    PubMed

    Heijl, Anders; Leske, M Cristina; Bengtsson, Bo; Hyman, Leslie; Bengtsson, Boel; Hussein, Mohamed

    2002-10-01

    To provide the results of the Early Manifest Glaucoma Trial, which compared the effect of immediately lowering the intraocular pressure (IOP), vs no treatment or later treatment, on the progression of newly detected open-angle glaucoma. Randomized clinical trial. Two hundred fifty-five patients aged 50 to 80 years (median, 68 years) with early glaucoma, visual field defects (median mean deviation, -4 dB), and a median IOP of 20 mm Hg, mainly identified through a population screening. Patients with an IOP greater than 30 mm Hg or advanced visual field loss were ineligible. Patients were randomized to either laser trabeculoplasty plus topical betaxolol hydrochloride (n = 129) or no initial treatment (n = 126). Study visits included Humphrey Full Threshold 30-2 visual field tests and tonometry every 3 months, and optic disc photography every 6 months. Decisions regarding treatment were made jointly with the patient when progression occurred and thereafter. Glaucoma progression was defined by specific visual field and optic disc outcomes. Criteria for perimetric progression were computer based and defined as the same 3 or more test point locations showing significant deterioration from baseline in glaucoma change probability maps from 3 consecutive tests. Optic disc progression was determined by masked graders using flicker chronoscopy plus side-by-side photogradings. After a median follow-up period of 6 years (range, 51-102 months), retention was excellent, with only 6 patients lost to follow-up for reasons other than death. On average, treatment reduced the IOP by 5.1 mm Hg or 25%, a reduction maintained throughout follow-up. Progression was less frequent in the treatment group (58/129; 45%) than in controls (78/126; 62%) (P =.007) and occurred significantly later in treated patients. Treatment effects were also evident when stratifying patients by median IOP, mean deviation, and age as well as exfoliation status. Although patients reported few systemic or ocular

  15. Time Course of Change in Blood Pressure From Sodium Reduction and the DASH Diet.

    PubMed

    Juraschek, Stephen P; Woodward, Mark; Sacks, Frank M; Carey, Vincent J; Miller, Edgar R; Appel, Lawrence J

    2017-11-01

    Both sodium reduction and the Dietary Approaches to Stop Hypertension (DASH) diet lower blood pressure (BP); however, the patterns of their effects on BP over time are unknown. In the DASH-Sodium trial, adults with pre-/stage 1 hypertension, not using antihypertensive medications, were randomly assigned to either a typical American diet (control) or DASH. Within their assigned diet, participants randomly ate each of 3 sodium levels (50, 100, and 150 mmol/d, at 2100 kcal) over 4-week periods. BP was measured weekly for 12 weeks; 412 participants enrolled (57% women; 57% black; mean age, 48 years; mean systolic BP [SBP]/diastolic BP [DBP], 135/86 mm Hg). For those assigned control, there was no change in SBP/DBP between weeks 1 and 4 on the high-sodium diet (weekly change, -0.04/0.06 mm Hg/week) versus a progressive decline in BP on the low-sodium diet (-0.94/-0.70 mm Hg/week; P interactions between time and sodium <0.001 for SBP and DBP). For those assigned DASH, SBP/DBP changed -0.60/-0.16 mm Hg/week on the high- versus -0.42/-0.54 mm Hg/week on the low-sodium diet (P interactions between time and sodium=0.56 for SBP and 0.10 for DBP). When comparing DASH to control, DASH changed SBP/DBP by -4.36/-1.07 mm Hg after 1 week, which accounted for most of the effect observed, with no significant difference in weekly rates of change for either SBP (P interaction=0.97) or DBP (P interaction=0.70). In the context of a typical American diet, a low-sodium diet reduced BP without plateau, suggesting that the full effects of sodium reduction are not completely achieved by 4 weeks. In contrast, compared with control, DASH lowers BP within a week without further effect thereafter. URL: http://www.clinicaltrials.gov. Unique identifier: NCT00000608. © 2017 American Heart Association, Inc.

  16. Design of novel melatonin analogs for the reduction of intraocular pressure in normotensive rabbits.

    PubMed

    Alarma-Estrany, Pilar; Guzman-Aranguez, Ana; Huete, Fernando; Peral, Assumpta; Plourde, Robert; Pelaez, Teresa; Yerxa, Benjamin; Pintor, Jesús

    2011-06-01

    Melatonin, the MT(2) melatonin receptor agonist IIK7 [N-butanoyl-2-(2-methoxy-6H-isoindolo[2,1-a]indol-11-yl)ethanamine], and the putative MT(3) melatonin receptor agonist 5-MCA-NAT [5-methoxycarbonylamino-N-acetyltryptamine] have previously been shown to reduce intraocular pressure (IOP) in ocular normotensive rabbits. To gain a better understanding of the structure-activity relationship of compounds that activate MT(2) and MT(3) receptors mediating reductions in IOP, novel melatonin analogs with rationally varied substitutions were synthesized and tested for their effects on IOP in ocular normotensive rabbits (n = 160). All synthesized melatonin analogs reduced IOP. The best-effect lowering IOP was obtained with the analogs INS48848 [methyl-1-methylene-2,3,4,9-tetrahydro-1H-carbazol-6-ylcarbamate], INS48862 [methyl-2-bromo-3-(2-ethanamidoethyl)-1H-indol-5-ylcarbamate], and INS48852 [(E)-N-(2-(5-methoxy-1H-indol-3-yl)ethyl)-3-phenylprop-2-enamide]. These compounds produced dose-dependent decreases in IOP that were maximal at 0.1 mM (total dose of 0.259 μg for INS48848, 0.354 μg for INS48862, and 0.320 μg for INS48852) and 1 mM (total dose of 2.59 μg for INS48848, 3.54 μg for INS48862, and 3.20 μg for INS48852), with maximal reductions of 36.0 ± 4.0, 24.0 ± 1.5, and 30.0 ± 1.5% for INS48848, INS48862, and INS48852, respectively. Studies using melatonin receptor antagonists (luzindole, prazosin, and DH97 [N-pentanoyl-2-benzyltryptamine]) indicated that INS48862 and INS48852 activate preferentially a MT(2) melatonin receptor and suggest that INS48848 may act mainly via a MT(3) receptor. The most effective compounds were also well tolerated in a battery of standard ocular surface irritation studies. The implication of these findings to the design of novel drugs to treat ocular hypertension is discussed.

  17. Pre-drill Pore pressure estimation in shale gas reservoirs using seismic genetic inversion: Application to Barnett shale.

    NASA Astrophysics Data System (ADS)

    Ouadfeul, Sid-Ali; Aliouane, Leila; Eladj, Said

    2017-04-01

    In this paper, the seismic genetic inversion is used for estimation of the pore pressure before drilling, the first stage is to invert the 3D seismic cube recorded in the Fot Worth basin located in the United States of America using the artificial neural network. The Multilayer Perceptron neural network is trained in a supervised mode using the stacked 3D seismic amplitudes near three wells as an input and the calculated acoustic impedances derived from the density and sonic logs recorded in these wells as an output. During the training the weights of connections between neurons are optimized, then the whole seismic cube is propagated though the neural machine. The output of this machine is the cube of the acoustic impedance. A linear relationship between the depth and velocity are derived using sonic well-log data of a vertical well, this relationship will be us ed as a vertical trend in the Eaton's model. The acoustic impedances are used to deduce the pore pressure from the Eaton's model. The proposed process is applied to derive the pore pressure in the Lower Barnett shale, obtained results can be used for well-bore stability and hydraulic fracture planning and simulation.

  18. 28-day intraocular pressure reduction with a single dose of brimonidine tartrate-loaded microspheres.

    PubMed

    Fedorchak, Morgan V; Conner, Ian P; Medina, Carlos A; Wingard, Jeremy B; Schuman, Joel S; Little, Steven R

    2014-08-01

    Treatment of glaucoma by intraocular pressure (IOP) reduction is typically accomplished through the administration of eye drops, the difficult and frequent nature of which contributes to extremely low adherence rates. Poor adherence to topical treatment regimens in glaucoma patients can lead to irreversible vision loss and increased treatment costs. Currently there are no approved treatments for glaucoma that address the inherent inefficiencies in drug delivery and patient adherence. Brimonidine tartrate (BT), a common glaucoma medication, requires dosing every 8-12 h, with up to 97% of patients not taking it as prescribed. This study provides proof-of-principle testing of a controlled release BT formulation. BT was encapsulated in poly(lactic-co-glycolic) acid microspheres and drug release was quantified using UV-Vis spectroscopy. For in vivo studies, rabbits were randomized to receive a single subconjunctival injection of blank (no drug) or BT-loaded microspheres or twice daily topical 0.2% BT drops. The microspheres released an average of 2.1 ± 0.37 μg BT/mg microspheres/day in vitro. In vivo, the percent decrease in IOP from baseline was significantly greater in the treated eye for both topical drug and drug-loaded microspheres versus blank microspheres throughout the 4-week study, with no evidence of migration or foreign body response. IOP measurements in the contralateral, untreated eyes also suggested a highly localized effect from the experimental treatment. A treatment designed using the release systems described in this study would represent a vast improvement over the current clinical standard of 56-84 topical doses over 28 days.

  19. Home-based isometric exercise training induced reductions resting blood pressure.

    PubMed

    Wiles, Jonathan D; Goldring, Natalie; Coleman, Damian

    2017-01-01

    Isometric exercise training (IET) reduces resting blood pressure (BP). Most previous protocols impose exercise barriers which undermine its effectiveness as a potential physical therapy for altering BP. An inexpensive, home-based programme would promote IET as a valuable tool in the fight against hypertension. The aims of this study were: (a) to investigate whether home-based wall squat training could successfully reduce resting BP and (b) to explore the physiological variables that might mediate a change in resting BP. Twenty-eight healthy normotensive males were randomly assigned to a control and a 4 week home-based IET intervention using a crossover design with a 4 week 'washout' period in-between. Wall squat training was completed 3 × weekly over 4 weeks with 48 h between sessions. Each session comprised 4 × 2 min bouts of wall squat exercise performed at a participant-specific knee joint angle relative to a target HR of 95% HRpeak, with 2 min rest between bouts. Resting heart rate, BP, cardiac output, total peripheral resistance, and stroke volume were taken at baseline and post each condition. Resting BP (systolic -4 ± 5, diastolic -3 ± 3 and mean arterial -3 ± 3 mmHg), cardiac output (-0.54 ± 0.66 L min(-1)) and heart rate (-5 ± 7 beats min(-1)) were all reduced following IET, with no change in total peripheral resistance or stroke volume compared to the control. These findings suggest that the wall squat provides an effective method for reducing resting BP in the home resulting primarily from a reduction in resting heart rate.

  20. Mechanisms compensating Na and water retention induced by long-term reduction of renal perfusion pressure.

    PubMed

    Seeliger, E; Boemke, W; Corea, M; Encke, T; Reinhardt, H W

    1997-08-01

    Endogenous downregulation of plasma aldosterone (Aldo) concentration, despite increased plasma renin activity (PRA), has been suggested to compensate Na and water retention, which is induced by long-term reduction of renal perfusion pressure (rRPP). To determine whether fixed plasma Aldo concentration would prevent equilibration of 24-h Na and water balances during rRPP, chronically instrumented, freely moving beagle dogs were kept under standardized conditions (daily intake 5.5 mmol Na/kg body wt) and studied for 4 consecutive days under the following conditions: control without rRPP (protocol 1) and rRPP + infusion of Aldo (rRPP + Aldo, protocol 2). Because Aldo administration reduces PRA and, thereby, angiotensin II (ANG II) levels ANG II was additionally infused in protocol 3 (rRPP + ANG II + Aldo). During rRPP + Aldo, 24-h Na balances were never equilibrated. Daily Na retention was approximately 3.5 mmol/kg body wt on day 1 and decreased to approximately 1.6 mmol/kg body wt on day 4; 24-h water balances changed in a similar manner. PRA decreased stepwise. On all rRPP + ANG II + Aldo days, Na and water retentions were more extensive than during rRPP + Aldo. Daily Na retention decreased from approximately 4.4 mmol/kg body wt on day 1 to approximately 3.0 mmol/kg body wt on day 4. Plasma atrial natriuretic peptide increased during both protocols. It is concluded that 1) endogenous downregulation of components of the renin-angiotensin-aldosterone system is a pivotal compensatory mechanism to reduce Na and water retention and 2) natriuretic and diuretic factors seem to be of minor potency, because not even the sum of all could counterbalances the Na- and water-retaining effects of Aldo and ANG II.

  1. A rotating two-phase gas/liquid flow for pressure reduction in underwater plasma arc welding

    SciTech Connect

    Steinkamp, H.; Creutz, M.; Mewes, D.; Bartzsch, J.

    1994-12-31

    Plasma arc welding processes are used in off-shore industry for the construction and maintenance in the wet surrounding of underwater structures and pipelines. In greater water depth the density of the plasma gas increase because of the greater hydrostatic pressure. This causes an increase of the conductive heat losses to the wet surrounding. To keep up the energy flux to the workpiece a pressure reduction is favorable against the surrounding. To keep up the energy flux to the workpiece a pressure reduction is favorable against the surrounding. The plasma arc has to burn in a locally dry area. This requirement can be fulfilled by a rotating disc placed above the workpiece. In the gap between the lower end of the cylinder and the workpiece a rotating two-phase flow is maintained. The flow around the rotating disc is experimentally investigated. The rotating disc is placed above the surface of the workpiece which is simulated by a flat plate. Water is forced out of the cylinder due to centrifugal forces set up by the rotating disc and flat plate. The velocity distribution in the flow is measured by Laser-Doppler-Anemometry. The phase distribution in the two-phase flow in the gap is measured by local electrical probes. The static pressure in the gaseous atmosphere is reduced in comparison to the hydrostatic pressure of the surrounding water. The pressure reduction is given by the void fraction, the phase distribution and the volume flow rates of both phases in the gap as well as by the speed of revolution and the design of the disc and the work surface. Apart from the investigations on the fluid dynamics, the method to reduce the pressure was technically proved. Experiments were carried out under water with a plasma MIG welder.

  2. 49 CFR 229.49 - Main reservoir system.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 4 2011-10-01 2011-10-01 false Main reservoir system. 229.49 Section 229.49... Main reservoir system. (a)(1) The main reservoir system of each locomotive shall be equipped with at... reservoir of air under pressure to be used for operating those power controls. The reservoir shall...

  3. 49 CFR 229.49 - Main reservoir system.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 4 2012-10-01 2012-10-01 false Main reservoir system. 229.49 Section 229.49... Main reservoir system. (a)(1) The main reservoir system of each locomotive shall be equipped with at... reservoir of air under pressure to be used for operating those power controls. The reservoir shall...

  4. Sustained superhydrophobic friction reduction at high liquid pressures and large flows.

    PubMed

    Carlborg, Carl Fredrik; van der Wijngaart, Wouter

    2011-01-04

    This Article introduces and experimentally explores a novel self-regulating method for reducing the friction losses in large microchannels at high liquid pressures and large liquid flows, overcoming previous limitations with regard to sustainable liquid pressure on a superhydrophobic surface. Our design of the superhydrophobic channel automatically adjusts the gas pressure in the lubricating air layer to the local liquid pressure in the channel. This is achieved by pneumatically connecting the liquid in the microchannel to the gas-pockets trapped at the channel wall through a pressure feedback channel. When liquid enters the feedback channel, it compresses the air and increases the pressure in the gas-pocket. This reduces the pressure drop over the gas-liquid interface and increases the maximum sustainable liquid pressure. We define a dimensionless figure of merit for superhydropbic flows, W(F) = P(L)D/γ cos(θ(c)), which expresses the fluidic energy carrying capacity of a superhydrophobic microchannel. We experimentally verify that our geometry can sustain three times higher liquid pressure before collapsing, and we measured better friction-reducing properties at higher W(F) values than in previous works. The design is ultimately limited in time by the gas-exchange over the gas-liquid interface at pressures exceeding the Laplace pressure. This method could be applicable for reducing near-wall laminar friction in both micro and macro scale flows.

  5. Effect of longer term modest salt reduction on blood pressure: Cochrane systematic review and meta-analysis of randomised trials.

    PubMed

    He, Feng J; Li, Jiafu; Macgregor, Graham A

    2013-04-03

    To determine the effects of longer term modest salt reduction on blood pressure, hormones, and lipids. Systematic review and meta-analysis. Medline, Embase, Cochrane Hypertension Group Specialised Register, Cochrane Central Register of Controlled Trials, and reference list of relevant articles. Randomised trials with a modest reduction in salt intake and duration of at least four weeks. Data were extracted independently by two reviewers. Random effects meta-analyses, subgroup analyses, and meta-regression were performed. Thirty four trials (3230 participants) were included. Meta-analysis showed that the mean change in urinary sodium (reduced salt v usual salt) was -75 mmol/24 h (equivalent to a reduction of 4.4 g/day salt), and with this reduction in salt intake, the mean change in blood pressure was -4.18 mm Hg (95% confidence interval -5.18 to -3.18, I(2)=75%) for systolic blood pressure and -2.06 mm Hg (-2.67 to -1.45, I(2)=68%) for diastolic blood pressure. Meta-regression showed that age, ethnic group, blood pressure status (hypertensive or normotensive), and the change in 24 hour urinary sodium were all significantly associated with the fall in systolic blood pressure, explaining 68% of the variance between studies. A 100 mmol reduction in 24 hour urinary sodium (6 g/day salt) was associated with a fall in systolic blood pressure of 5.8 mm Hg (2.5 to 9.2, P=0.001) after adjustment for age, ethnic group, and blood pressure status. For diastolic blood pressure, age, ethnic group, blood pressure status, and the change in 24 hour urinary sodium explained 41% of the variance between studies. Meta-analysis by subgroup showed that in people with hypertension the mean effect was -5.39 mm Hg (-6.62 to -4.15, I(2)=61%) for systolic blood pressure and -2.82 mm Hg (-3.54 to -2.11, I(2)=52%) for diastolic blood pressure. In normotensive people, the figures were -2.42 mm Hg (-3.56 to -1.29, I(2)=66%) and -1.00 mm Hg (-1.85 to -0.15, I(2)=66%), respectively. Further

  6. Reduction of Injection-Induced Pore-Pressure and Stress in Basement Rocks Due to Basal Sealing Layers

    NASA Astrophysics Data System (ADS)

    Chang, Kyung Won; Segall, Paul

    2017-07-01

    Our previous study (Chang and Segall, J Geophys Res Solid Earth 121(4):2708-2726, 2016a) demonstrated that diffusion of pore-pressure and stress into basement rocks can cause slip on deep faults, potentially inducing seismicity. Recent studies suggest that the presence of a bottom-sealing layer between the injection horizon and basement will reduce the magnitude of injection-induced pore-pressure in the basement due to contrasts in permeability and/or storage capacity. In this study, we examine the role of basal sealing horizons in induced seismicity on basement faults by adding a layer beneath the reservoir into the two-dimensional, fully coupled poroelastic model developed previously. We consider two types of basal seals: (1) a low-permeability seal and (2) a high-storativity seal. The analysis of the spatio-temporal change in Coulomb stress and time-dependent rate of earthquake nucleation confirms that both types of seal inhibit direct pore-pressure diffusion into basement rocks, but poroelastic stresses are still transmitted, potentially inducing earthquakes. The high-storativity seal reduces the transmission of poroelastic stresses into the basement, minimizing seismicity on basement faults in comparison to the low-permeability seal.

  7. Isotopic insights into microbial sulfur cycling in oil reservoirs

    PubMed Central

    Hubbard, Christopher G.; Cheng, Yiwei; Engelbrekston, Anna; Druhan, Jennifer L.; Li, Li; Ajo-Franklin, Jonathan B.; Coates, John D.; Conrad, Mark E.

    2014-01-01

    Microbial sulfate reduction in oil reservoirs (biosouring) is often associated with secondary oil production where seawater containing high sulfate concentrations (~28 mM) is injected into a reservoir to maintain pressure and displace oil. The sulfide generated from biosouring can cause corrosion of infrastructure, health exposure risks, and higher production costs. Isotope monitoring is a promising approach for understanding microbial sulfur cycling in reservoirs, enabling early detection of biosouring, and understanding the impact of souring. Microbial sulfate reduction is known to result in large shifts in the sulfur and oxygen isotope compositions of the residual sulfate, which can be distinguished from other processes that may be occurring in oil reservoirs, such as precipitation of sulfate and sulfide minerals. Key to the success of this method is using the appropriate isotopic fractionation factors for the conditions and processes being monitored. For a set of batch incubation experiments using a mixed microbial culture with crude oil as the electron donor, we measured a sulfur fractionation factor for sulfate reduction of −30‰. We have incorporated this result into a simplified 1D reservoir reactive transport model to highlight how isotopes can help discriminate between biotic and abiotic processes affecting sulfate and sulfide concentrations. Modeling results suggest that monitoring sulfate isotopes can provide an early indication of souring for reservoirs with reactive iron minerals that can remove the produced sulfide, especially when sulfate reduction occurs in the mixing zone between formation waters (FW) containing elevated concentrations of volatile fatty acids (VFAs) and injection water (IW) containing elevated sulfate. In addition, we examine the role of reservoir thermal, geochemical, hydrological, operational and microbiological conditions in determining microbial souring dynamics and hence the anticipated isotopic signatures. PMID:25285094

  8. Isotopic insights into microbial sulfur cycling in oil reservoirs.

    PubMed

    Hubbard, Christopher G; Cheng, Yiwei; Engelbrekston, Anna; Druhan, Jennifer L; Li, Li; Ajo-Franklin, Jonathan B; Coates, John D; Conrad, Mark E

    2014-01-01

    Microbial sulfate reduction in oil reservoirs (biosouring) is often associated with secondary oil production where seawater containing high sulfate concentrations (~28 mM) is injected into a reservoir to maintain pressure and displace oil. The sulfide generated from biosouring can cause corrosion of infrastructure, health exposure risks, and higher production costs. Isotope monitoring is a promising approach for understanding microbial sulfur cycling in reservoirs, enabling early detection of biosouring, and understanding the impact of souring. Microbial sulfate reduction is known to result in large shifts in the sulfur and oxygen isotope compositions of the residual sulfate, which can be distinguished from other processes that may be occurring in oil reservoirs, such as precipitation of sulfate and sulfide minerals. Key to the success of this method is using the appropriate isotopic fractionation factors for the conditions and processes being monitored. For a set of batch incubation experiments using a mixed microbial culture with crude oil as the electron donor, we measured a sulfur fractionation factor for sulfate reduction of -30‰. We have incorporated this result into a simplified 1D reservoir reactive transport model to highlight how isotopes can help discriminate between biotic and abiotic processes affecting sulfate and sulfide concentrations. Modeling results suggest that monitoring sulfate isotopes can provide an early indication of souring for reservoirs with reactive iron minerals that can remove the produced sulfide, especially when sulfate reduction occurs in the mixing zone between formation waters (FW) containing elevated concentrations of volatile fatty acids (VFAs) and injection water (IW) containing elevated sulfate. In addition, we examine the role of reservoir thermal, geochemical, hydrological, operational and microbiological conditions in determining microbial souring dynamics and hence the anticipated isotopic signatures.

  9. Reduction of lattice disorder in protein crystals by high-pressure cryocooling.

    PubMed

    Huang, Qingqiu; Gruner, Sol M; Kim, Chae Un; Mao, Yuxin; Wu, Xiaochun; Szebenyi, Doletha M E

    2016-02-01

    High-pressure cryocooling (HPC) has been developed as a technique for reducing the damage that frequently occurs when macromolecular crystals are cryocooled at ambient pressure. Crystals are typically pressurized at around 200 MPa and then cooled to liquid nitrogen temperature under pressure; this process reduces the need for penetrating cryoprotectants, as well as the damage due to cryocooling, but does not improve the diffraction quality of the as-grown crystals. Here it is reported that HPC using a pressure above 300 MPa can reduce lattice disorder, in the form of high mosaicity and/or nonmerohedral twinning, in crystals of three different proteins, namely human glutaminase C, the GTP pyrophosphokinase YjbM and the uncharacterized protein lpg1496. Pressure lower than 250 MPa does not induce this transformation, even with a prolonged pressurization time. These results indicate that HPC at elevated pressures can be a useful tool for improving crystal packing and hence the quality of the diffraction data collected from pressurized crystals.

  10. Reduction of lattice disorder in protein crystals by high-pressure cryocooling

    PubMed Central

    Huang, Qingqiu; Gruner, Sol M.; Kim, Chae Un; Mao, Yuxin; Wu, Xiaochun; Szebenyi, Doletha M. E.

    2016-01-01

    High-pressure cryocooling (HPC) has been developed as a technique for reducing the damage that frequently occurs when macromolecular crystals are cryocooled at ambient pressure. Crystals are typically pressurized at around 200 MPa and then cooled to liquid nitrogen temperature under pressure; this process reduces the need for penetrating cryoprotectants, as well as the damage due to cryocooling, but does not improve the diffraction quality of the as-grown crystals. Here it is reported that HPC using a pressure above 300 MPa can reduce lattice disorder, in the form of high mosaicity and/or nonmerohedral twinning, in crystals of three different proteins, namely human glutaminase C, the GTP pyrophosphokinase YjbM and the uncharacterized protein lpg1496. Pressure lower than 250 MPa does not induce this transformation, even with a prolonged pressurization time. These results indicate that HPC at elevated pressures can be a useful tool for improving crystal packing and hence the quality of the diffraction data collected from pressurized crystals. PMID:26937238

  11. Ductile shear zones can induce hydraulically over-pressured fractures in deep hot-dry rock reservoirs: a new target for geothermal exploration?

    NASA Astrophysics Data System (ADS)

    Schrank, C. E.; Karrech, A.; Regenauer-Lieb, K.

    2014-12-01

    It is notoriously difficult to create and maintain permeability in deep hot-dry rock (HDR) geothermal reservoirs with engineering strategies. However, we predict that long-lived, slowly deforming HDR reservoirs likely contain hydraulically conductive, over-pressured fracture systems, provided that (a) the underlying lower crust and/or mantle are not entirely depleted of fluids and (b) the fracture system has not been drained into highly permeable overlying rocks. Such fracture systems could be targeted for the extraction of geothermal energy. Our prediction hinges on the notion that polycrystalline creep through matter transfer by a liquid phase (dissolution-precipitation creep) is a widespread mechanism for extracting fluids from the lower crust and mantle. Such processes - where creep cavities form during the slow, high-temperature deformation of crystalline solids, e.g., ceramics, metals, and rocks - entail the formation of (intergranular) fluid-assisted creep fractures. They constitute micron-scale voids formed along grain boundaries due to incompatibilities arising from diffusion or dislocation creep. Field and laboratory evidence suggest that the process leading to creep fractures may generate a dynamic permeability in the ductile crust, thus extracting fluids from this domain. We employed an elasto-visco-plastic material model that simulates creep fractures with continuum damage mechanics to model the slow contraction of high-heat-producing granites overlain by sedimentary rocks in 2D. The models suggest that deformation always leads to the initiation of a horizontal creep-damage front in the lower crust. This front propagates upwards towards the brittle-ductile transition (BDT) during protracted deformation where it collapses into highly damaged brittle-ductile shear zones. If the BDT is sufficiently shallow or finite strain sufficiently large, these shear zones trigger brittle faults emerging from their tips, which connect to the sub-horizontal damage

  12. Cesium reservoir and interconnective components. Final test report: TFE Verification Program

    SciTech Connect

    Not Available

    1994-03-01

    The program objective is to demonstrate the technology readiness of a TFE (thermionic fuel element) suitable for use as the basic element in a thermionic reactor with electric power output in the 0.5 to 5.0 MW range. A thermionic converter must be supplied with cesium vapor for two reasons. Cesium atoms adsorbed on the surface of the emitter cause a reduction of the emitter work function to permit high current densities without excessive heating of the emitter. The second purpose of the cesium vapor is to provide space-charge neutralization in the emitter-collector gap so that the high current densities may flow across the gap unattenuated. The function of the cesium reservoir is to provide a source of cesium atoms, and to provide a reserve in the event that cesium is lost from the plasma by any mechanism. This can be done with a liquid cesium metal reservoir in which case it is heated to the desired temperature with auxiliary heaters. In a TFE, however, it is desirable to have the reservoir passively heated by the nuclear fuel. In this case, the reservoir must operate at a temperature intermediate between the emitter and the collector, ruling out the use of liquid reservoirs. Integral reservoirs contained within the TFE will produce cesium vapor pressures in the desired range at typical electrode temperatures. The reservoir material that appears to be the best able to meet requirements is graphite. Cesium intercalates easily into graphite, and the cesium pressure is insensitive to loading for a given intercalation stage. The goals of the cesium reservoir test program were to verify the performance of Cs-graphite reservoirs in the temperature-pressure range of interest to TFE operation, and to test the operation of these reservoirs after exposure to a fast neutron fluence corresponding to seven year mission lifetime. In addition, other materials were evaluated for possible use in the integral reservoir.

  13. Fractured petroleum reservoirs

    SciTech Connect

    Firoozabadi, A.; Chang, E.; Tang, G.Q.

    2000-01-10

    Total compressibility in a fractured reservoir is estimated using the pressure response due to gravitational potential variations. Both the moon and the sun gravitational potentials are accounted for using the full expression by inclusion of longer-period components. The semi-diurnal and diurnal pressure data show substantial long-term variations. The gravitational potential also contains the same variation trend; the ratio between the potential and pressure has a fairly uniform value over successive cycles. The computed total compressibility is also fairly constant and independent of the cycle. Results show the effects of the time interval over which the pressure measurements are performed as well as the location.

  14. The effect on pregnancy rates of tubal perfusion pressure reductions achieved by guide-wire tubal catheterization.

    PubMed

    Papaioannou, Spyros; Afnan, Masoud; Girling, Alan J; Coomarasamy, Aravinthan; Ola, Bolarinde; Olufowobi, Olufemi; McHugo, Josephine M; Hammadieh, Nahed; Sharif, Khaldoun

    2002-08-01

    Selective salpingography enables us to measure the Fallopian tube perfusion pressure which, when high, can be effectively reduced with the use of transcervical guide-wire tubal catheterization. Whether fertility prognosis improves as a result is currently unknown. Our objective was to clarify the issue. Infertile women undergoing selective salpingography were classified into poor, mediocre and good tubal perfusion pressure groups, based on the distribution of tubal perfusion pressures in an unselected infertile population. Of 325 women, 150 (46.1%) were classified in the poor group and underwent guide-wire tubal catheterization. Complete pregnancy and tubal perfusion pressure data were available for 104 (69.4%) subjects. Following tubal catheterization, 29 women (group A) could be classified in the good, 25 (group B) in the mediocre, while 50 women (group C) remained in the poor tubal perfusion pressure group. Survival analysis showed that the pregnancy rate in group A was significantly higher than the rates in groups B and C (P = 0.036 and 0.005 respectively). Reductions of tubal perfusion pressures achieved with transcervical guide-wire tubal catheterization resulted in an improved fertility prognosis for women. Selective salpingography and tubal catheterization might have a wider role in the management of the infertile couple than currently believed.

  15. Iron reduction by the deep-sea bacterium Shewanella profunda LT13a under subsurface pressure and temperature conditions.

    PubMed

    Picard, Aude; Testemale, Denis; Wagenknecht, Laura; Hazael, Rachael; Daniel, Isabelle

    2014-01-01

    Microorganisms influence biogeochemical cycles from the surface down to the depths of the continental rocks and oceanic basaltic crust. Due to the poor recovery of microbial isolates from the deep subsurface, the influence of physical environmental parameters, such as pressure and temperature, on the physiology and metabolic potential of subsurface inhabitants is not well constrained. We evaluated Fe(III) reduction rates (FeRRs) and viability, measured as colony-forming ability, of the deep-sea piezophilic bacterium Shewanella profunda LT13a over a range of pressures (0-125 MPa) and temperatures (4-37∘C) that included the in situ habitat of the bacterium isolated from deep-sea sediments at 4500 m depth below sea level. S. profunda LT13a was active at all temperatures investigated and at pressures up to 120 MPa at 30∘C, suggesting that it is well adapted to deep-sea and deep sedimentary environments. Average initial cellular FeRRs only slightly decreased with increasing pressure until activity stopped, suggesting that the respiratory chain was not immediately affected upon the application of pressure. We hypothesize that, as pressure increases, the increased energy demand for cell maintenance is not fulfilled, thus leading to a decrease in viability. This study opens up perspectives about energy requirements of cells in the deep subsurface.

  16. Iron reduction by the deep-sea bacterium Shewanella profunda LT13a under subsurface pressure and temperature conditions

    PubMed Central

    Picard, Aude; Testemale, Denis; Wagenknecht, Laura; Hazael, Rachael; Daniel, Isabelle

    2015-01-01

    Microorganisms influence biogeochemical cycles from the surface down to the depths of the continental rocks and oceanic basaltic crust. Due to the poor recovery of microbial isolates from the deep subsurface, the influence of physical environmental parameters, such as pressure and temperature, on the physiology and metabolic potential of subsurface inhabitants is not well constrained. We evaluated Fe(III) reduction rates (FeRRs) and viability, measured as colony-forming ability, of the deep-sea piezophilic bacterium Shewanella profunda LT13a over a range of pressures (0–125 MPa) and temperatures (4–37∘C) that included the in situ habitat of the bacterium isolated from deep-sea sediments at 4500 m depth below sea level. S. profunda LT13a was active at all temperatures investigated and at pressures up to 120 MPa at 30∘C, suggesting that it is well adapted to deep-sea and deep sedimentary environments. Average initial cellular FeRRs only slightly decreased with increasing pressure until activity stopped, suggesting that the respiratory chain was not immediately affected upon the application of pressure. We hypothesize that, as pressure increases, the increased energy demand for cell maintenance is not fulfilled, thus leading to a decrease in viability. This study opens up perspectives about energy requirements of cells in the deep subsurface. PMID:25653646

  17. Modification of exercise performance by sharp reduction of blood pressure. A study in patients with uncomplicated hypertension.

    PubMed

    Agostoni, P G; Doria, E; Alimento, M; Riva, S; Muratori, M; Tamborini, G

    1993-12-01

    We evaluated exercise performance in 14 patients with uncomplicated essential hypertension 1 h after the administration of a single dose of placebo, nifedipine (20 mg), captopril (50 mg), and propranolol (80 mg). Drugs were administered at the same time of day following a randomized, double-blind protocol. Mean resting blood pressure (+/- SE) was 135 +/- 3 mm Hg with placebo administration, 118 +/- 4 with captopril, 110 +/- 4 with nifedipine, and 115 +/- 5 with propranolol and increased with exercise to 163 +/- 4, 146 +/- 3, 136 +/- 4, 136 +/- 4, respectively. Oxygen consumption at peak exercise and at ventilatory anaerobic threshold (VAT) was 25.2 +/- 1.1 and 18.1 +/- 1.0 ml/min/kg with placebo. Only propranolol (-2.3 ml/min/kg) decreased peak exercise oxygen consumption. Oxygen consumption at VAT was reduced by nifedipine and propranolol but unaffected by captopril. The effects on exercise capacity of blood pressure reduction in hypertensive patients are dependent on the drug utilized and are not related to the amount of blood pressure reduction. The lowered oxygen consumption at VAT observed with nifedipine and propranolol, and not with captopril, might be due to an excessive downward shift of the muscle perfusion pressure--oxygen consumption relationship which might take place during exercise.

  18. Reduction of fluctuating pressure loads in shock wave turbulent boundary layer interactions

    NASA Technical Reports Server (NTRS)

    Barter, John W.; Dolling, David S.

    1995-01-01

    Fluctuating surface pressure measurements have been made to investigate the effectiveness of boundary layer separators (BLS's) in reducing the fluctuating pressure loads produced by separated shock wave turbulent boundary layer interactions. Measurements have been made under unswept and swept compression corner interactions in a Mach 5 flow. BLS's fix the separation location and eliminate the large-amplitude, low-frequency fluctuating pressure loads upstream of the compression corners. The loads on the unswept compression corner face are reduced by as much as 59%. The BLS's also shift the mean pressure distribution on the unswept corner face in the streamwise direction. Results show that the loads on the corner face vary with the BLS height and the distance between the BLS and the compression corner. Suggestions for the optimum placement and the use of the BLS's are also made.

  19. Postaerobic Exercise Blood Pressure Reduction in Very Old Persons With Hypertension.

    PubMed

    Oliveira, Joana; Mesquita-Bastos, José; Argel de Melo, Cristina; Ribeiro, Fernando

    2016-01-01

    A single bout of aerobic exercise acutely decreases blood pressure, even in older adults with hypertension. Nonetheless, blood pressure responses to aerobic exercise in very old adults with hypertension have not yet been documented. Therefore, this study aimed to assess the effect of a single session of aerobic exercise on postexercise blood pressure in very old adults with hypertension. Eighteen older adults with essential hypertension were randomized into exercise (N = 9, age: 83.4 ± 3.2 years old) or control (N = 9, age: 82.7 ± 2.5 years old) groups. The exercise group performed a session of aerobic exercise constituting 2 periods of 10 minutes of walking at an intensity of 40% to 60% of the heart rate reserve. The control group rested for the same period of time. Anthropometric variables and medication status were evaluated at baseline. Heart rate and systolic and diastolic blood pressures were measured at baseline, after exercise, and at 20 and 40 minutes postexercise. Systolic blood pressure showed a significant interaction for group × time (F3,24 = 6.698; P = .002; ηp(2) = 0.153). In the exercise group, the systolic blood pressure at 20 (127.3 ± 20.9 mm Hg) and 40 minutes (123.7 ± 21.0 mm Hg) postexercise was significantly lower in comparison with baseline (135.6 ± 20.6 mm Hg). Diastolic blood pressure did not change. Heart rate was significantly higher after the exercise session. In the control group, no significant differences were observed. A single session of aerobic exercise acutely reduces blood pressure in very old adults with hypertension and may be considered an important nonpharmacological strategy to control hypertension in this age group.

  20. Relative systolic blood pressure reduction and clinical outcomes in hyperacute intracerebral hemorrhage: the SAMURAI-ICH observational study.

    PubMed

    Sakamoto, Yuki; Koga, Masatoshi; Todo, Kenichi; Okuda, Satoshi; Okada, Yasushi; Kimura, Kazumi; Shiokawa, Yoshiaki; Kamiyama, Kenji; Furui, Eisuke; Hasegawa, Yasuhiro; Kario, Kazuomi; Okata, Takuya; Kobayashi, Junpei; Tanaka, Eijirou; Yamagami, Hiroshi; Nagatsuka, Kazuyuki; Minematsu, Kazuo; Toyoda, Kazunori

    2015-05-01

    Blood pressure lowering is often performed as a part of general acute management in acute intracerebral hemorrhage (ICH) patients. The relationship between relative blood pressure reduction and clinical outcomes is not fully known. Hyperacute (<3 h from onset) ICH patients with initial SBP more than 180 mmHg were included in the observational study. All patients received intravenous antihypertensive treatment based on a predefined protocol to lower and maintain SBP between 120 and 160 mmHg. The relative SBP reduction was defined as the ratio of SBP reduction to the admission SBP in the first 24 h, and associations between the relative SBP reduction and neurological deterioration (≥2 points decrease in the Glasgow Coma Scale score or ≥4 increase in the National Institutes of Health Stroke Scale score), hematoma expansion (>33% increase), and unfavorable outcome (modified Rankin scale score 4-6 at 3 months) were assessed with multivariate logistic regression analyses. Of the 211 patients [81 women, median age 65 (interquartile range 58-74) years, and median initial National Institutes of Health Stroke Scale score 13 (8-17)] enrolled, 17 (8%) showed neurological deterioration, 36 (17%) showed hematoma expansion, and 87 (41%) had an unfavorable outcome. On multivariate regression analyses, relative SBP reduction was independently and inversely associated with neurological deterioration (odds ratio 0.053, 95% confidence interval 0.011-0.254 per 10% increment), hematoma expansion (0.289, 0.099-0.841), and unfavorable outcome (0.254, 0.095-0.680) after adjusting for known predictive factors. Insufficient relative SBP reduction after standardized antihypertensive therapy in hyperacute ICH was independently associated with poor clinical outcomes. Aggressive antihypertensive treatment may improve clinical outcomes.

  1. Lens Position Parameters as Predictors of Intraocular Pressure Reduction After Cataract Surgery in Glaucomatous Versus Nonglaucomatous Eyes

    PubMed Central

    Coh, Paul; Moghimi, Sasan; Chen, Rebecca I.; Hsu, Chi-Hsin; Masís Solano, Marissé; Porco, Travis; Lin, Shan C.

    2016-01-01

    Purpose To evaluate the relationship between lens position parameters and intraocular pressure (IOP) reduction after cataract surgery in patients with primary open-angle glaucoma (POAG) and in nonglaucomatous patients. Methods The main outcomes of this prospective study were percent and absolute IOP change, which were calculated using the preoperative IOP and the IOP 4 months after cataract surgery in POAG and nonglaucomatous eyes. Lens position (LP), defined as anterior chamber depth (ACD) + one-half lens thickness (LT), was assessed preoperatively using parameters from optical biometry. Preoperative IOP, axial length (AL), ACD, LT, relative lens position (RLP), and the ratio of preoperative IOP to ACD (PD ratio) were also evaluated as potential predictors of IOP change. Results Four months postoperatively, the average IOP reduction was 2.80 ± 3.83 mm Hg (15.79%) from the preoperative mean of 14.73 ± 2.89 mm Hg for nonglaucomatous eyes. The average IOP reduction was 2.66 ± 2.07 mm Hg (16.98%) from the preoperative mean of 14.86 ± 2.97 mm Hg for POAG eyes. Preoperative IOP, sex, AL, ACD, PD ratio, and LP predicted IOP change in nonglaucomatous eyes. Preoperative IOP and PD ratio predicted IOP change in POAG eyes. Conclusions Intraocular pressure reduction after phacoemulsification cataract surgery in nonglaucomatous eyes is significantly greater in more anteriorly positioned lenses. Though it did not reach statistical significance in patients with glaucoma, the association of LP with IOP reduction is in the same direction as in nonglaucomatous patients where smaller LP appears to predict greater IOP reduction. Lens position is a simple, easily calculable, accurate, and widely available parameter, which clinicians can potentially utilize in managing glaucoma. PMID:27163773

  2. Automatic versus manual pressure support reduction in the weaning of post-operative patients: a randomised controlled trial

    PubMed Central

    Taniguchi, Corinne; Eid, Raquel C; Saghabi, Cilene; Souza, Rogério; Silva, Eliezer; Knobel, Elias; Paes, Ângela T; Barbas, Carmen S

    2009-01-01

    Introduction Reduction of automatic pressure support based on a target respiratory frequency or mandatory rate ventilation (MRV) is available in the Taema-Horus ventilator for the weaning process in the intensive care unit (ICU) setting. We hypothesised that MRV is as effective as manual weaning in post-operative ICU patients. Methods There were 106 patients selected in the post-operative period in a prospective, randomised, controlled protocol. When the patients arrived at the ICU after surgery, they were randomly assigned to either: traditional weaning, consisting of the manual reduction of pressure support every 30 minutes, keeping the respiratory rate/tidal volume (RR/TV) below 80 L until 5 to 7 cmH2O of pressure support ventilation (PSV); or automatic weaning, referring to MRV set with a respiratory frequency target of 15 breaths per minute (the ventilator automatically decreased the PSV level by 1 cmH2O every four respiratory cycles, if the patient's RR was less than 15 per minute). The primary endpoint of the study was the duration of the weaning process. Secondary endpoints were levels of pressure support, RR, TV (mL), RR/TV, positive end expiratory pressure levels, FiO2 and SpO2 required during the weaning process, the need for reintubation and the need for non-invasive ventilation in the 48 hours after extubation. Results In the intention to treat analysis there were no statistically significant differences between the 53 patients selected for each group regarding gender (p = 0.541), age (p = 0.585) and type of surgery (p = 0.172). Nineteen patients presented complications during the trial (4 in the PSV manual group and 15 in the MRV automatic group, p < 0.05). Nine patients in the automatic group did not adapt to the MRV mode. The mean ± sd (standard deviation) duration of the weaning process was 221 ± 192 for the manual group, and 271 ± 369 minutes for the automatic group (p = 0.375). PSV levels were significantly higher in MRV compared with that of

  3. Reduction of plantar pressures in leprosy patients by using custom made shoes and total contact insoles.

    PubMed

    Tang, Simon Fuk-Tan; Chen, Carl P C; Lin, Shih-Cherng; Wu, Chih-Kuan; Chen, Chih-Kuang; Cheng, Shun-Ping

    2015-02-01

    The purpose of this study was to observe whether our custom made shoes and total contact insoles can effectively increase the plantar contact areas and reduce peak pressures in patients with leprosy. In the rehabilitation laboratory of a tertiary medical center. Six male and two female leprosy patients were recruited in this study. In this study, parameters related to foot pressures were compared between these patients wearing commercial available soft-lining kung-fu shoes and our custom made shoes with total contact insoles. The custom made shoes were made with larger toe box and were able to accommodate both the foot and the insoles. Custom made total contact insoles were made with the subtalar joints under neutral and non-weight-bearing positions. The insole force measurement system of Novel Pedar-X (Novel, Munich, Germany) was used to measure the plantar forces. The parameters of contact area (cm(2)), peak plantar pressures (kPa), contact time (s), and pressure time integral (kPa s) were measured. There were significant contact area increases in the right and left foot heel areas, left medial arch, and second to fifth toes after wearing the custom made shoes and insoles. There were significant decreases in peak plantar pressures in bilateral heels, left lateral midfoot, bilateral second to fourth metatarsal areas, and left fifth metatarsal head after wearing the custom made shoes and insoles (p<0.05). Plantar ulceration is a common serious disability in leprosy patients. As a result, footwear and measures able to reduce plantar pressures may be beneficial in preventing plantar ulcers from occurring in these patients. Our custom made shoes and total contact insoles were proven to be effective in increasing contact areas and decreasing peak pressures in plantar surfaces, and may therefore be a feasible treatment option in preventing leprosy patients from developing plantar ulcers. © 2015 Elsevier B.V. All rights reserved.

  4. Selective Heart Rate Reduction With Ivabradine Increases Central Blood Pressure in Stable Coronary Artery Disease.

    PubMed

    Rimoldi, Stefano F; Messerli, Franz H; Cerny, David; Gloekler, Steffen; Traupe, Tobias; Laurent, Stéphane; Seiler, Christian

    2016-06-01

    Heart rate (HR) lowering by β-blockade was shown to be beneficial after myocardial infarction. In contrast, HR lowering with ivabradine was found to confer no benefits in 2 prospective randomized trials in patients with coronary artery disease. We hypothesized that this inefficacy could be in part related to ivabradine's effect on central (aortic) pressure. Our study included 46 patients with chronic stable coronary artery disease who were randomly allocated to placebo (n=23) or ivabradine (n=23) in a single-blinded fashion for 6 months. Concomitant baseline medication was continued unchanged throughout the study except for β-blockers, which were stopped during the study period. Central blood pressure and stroke volume were measured directly by left heart catheterization at baseline and after 6 months. For the determination of resting HR at baseline and at follow-up, 24-hour ECG monitoring was performed. Patients on ivabradine showed an increase of 11 mm Hg in central systolic pressure from 129±22 mm Hg to 140±26 mm Hg (P=0.02) and in stroke volume by 86±21.8 to 107.2±30.0 mL (P=0.002). In the placebo group, central systolic pressure and stroke volume remained unchanged. Estimates of myocardial oxygen consumption (HR×systolic pressure and time-tension index) remained unchanged with ivabradine.The decrease in HR from baseline to follow-up correlated with the concomitant increase in central systolic pressure (r=-0.41, P=0.009) and in stroke volume (r=-0.61, P<0.001). In conclusion, the decrease in HR with ivabradine was associated with an increase in central systolic pressure, which may have antagonized possible benefits of HR lowering in coronary artery disease patients. CLINICAL TRIALSURL: http://www.clinicaltrials.gov. Unique identifier NCT01039389. © 2016 American Heart Association, Inc.

  5. Increase of stagnation pressure and enthalpy in shock tunnels

    NASA Technical Reports Server (NTRS)

    Bogdanoff, David W.; Cambier, Jean-Luc

    1992-01-01

    High stagnation pressures and enthalpies are required for the testing of aerospace vehicles such as aerospace planes, aeroassist vehicles, and reentry vehicles. Among the most useful ground test facilities for performing such tests are shock tunnels. With a given driver gas condition, the enthalpy and pressure in the driven tube nozzle reservoir condition can be varied by changing the driven tube geometry and initial gas fill pressure. Reducing the driven tube diameter yields only very modest increases in reservoir pressure and enthalpy. Reducing the driven tube initial gas fill pressure can increase the reservoir enthalpy significantly, but at the cost of reduced reservoir pressure and useful test time. A new technique, the insertion of a converging section in the driven tube is found to produce substantial increases in both reservoir pressure and enthalpy. Using a one-dimensional inviscid full kinetics code, a number of different locations and shapes for the converging driven tube section were studied and the best cases found. For these best cases, for driven tube diameter reductions of factors of 2 and 3, the reservoir pressure can be increased by factors of 2.1 and 3.2, respectively and the enthalpy can be increased by factors of 1.5 and 2.1, respectively.

  6. Hydromechanics of Reservoir Induced Seismicity

    NASA Astrophysics Data System (ADS)

    Dura-Gomez, Inmaculada

    Data from five reservoirs were analyzed to investigate the various factors and possible pore pressure thresholds associated with Reservoir Induced Seismicity (RIS). Data was obtained from the following reservoirs: Koyna and Warna Reservoirs in India, Itoiz Reservoir in the western Pyrenees, Spain, and Jocassee and Monticello Reservoirs in South Carolina, U.S.A. Koyna Reservoir is one out of four reservoirs in the world where M≥6.0 induced earthquakes have occurred, whereas Warna Reservoir accounts for one out of ten cases with 5.0≤M≤5.9 induced earthquakes. Induced seismicity in the Koyna-Warna region is associated with annual filling cycles in the two reservoirs, large water level changes (30 to 45 m) and the presence of regional scale fractures. The Koyna-Warna case includes 19 M≥5.0 earthquakes at non-repeating hypocenters. The calculation of excess pore pressures associated with these earthquakes suggests values >300 kPa or >600 kPa, before or after 1993 respectively. The need for larger pore pressures from 1993 suggests that M≥5 earthquakes were induced on stronger faults in the region. The exceedance of the previous water level maxima (stress memory) is the most important, although not determining factor in inducing these M≥5.0 earthquakes. Itoiz Reservoir is one of twenty nine reservoirs with 4.0≤M≤4.9 induced earthquakes. The analysis of the RIS associated with the Itoiz Reservoir impoundment, between January 2004 and the end of 2008, shows that that pore pressures diffuse away from Itoiz Reservoir through the carbonate megabreccia systems of the Early to Middle Eocene Hecho Group, and a series of near-vertical thrust faults above the gently dipping Gavarnie thrust. Excess diffused pore pressures destabilize saturated critically stressed seismogenic fractures where RIS takes place. In particular, M≥3.0 earthquakes in the region are associated with excess pore pressures of the order of 100 to 200 kPa. Jocassee and Monticello Reservoirs in

  7. Fluid transients in pipes. Reduction and control of pressure surges in liquids

    NASA Astrophysics Data System (ADS)

    1984-11-01

    ESDU 84013 provides a simplified graphical method for predicting maximum pressure changes in liquid filled pipework systems that may be treated as one-line systems. The method applies to pressures induced by partial or total valve closure, covering all common valve types, or pump trips. Data are also given for the estimation of the size of air vessel, situated just downstream of a pump, to protect against excessive upsurge and downsurge pressure changes following pump trip. A computer program is included to analyze transients in one-line systems and does not use the simplifying assumptions necessary for the graphical data. Practical worked examples, illustrating the use of the methods, are included and guidance is given on the data required for a full fluid transients analysis going beyond the scope of ESDU 84013.

  8. Association between postexercise hypotension and long-term training-induced blood pressure reduction: a pilot study.

    PubMed

    Hecksteden, Anne; Grütters, Teresa; Meyer, Tim

    2013-01-01

    The interindividual variability in the efficacy of regular endurance exercise to lower blood pressure is high. Therefore, to optimize training prescriptions, predictors would be desirable. The main hypothesis of the present study was an association between postexercise hypotension after an exhaustive exercise test and chronic blood pressure reductions in response to an endurance training program. Uncontrolled prospective training study. University department. Healthy untrained subjects were recruited by flyers. Inclusion criteria were age 30 to 60 years, body mass index 25 to 35 kg/m(2), untrained status (<1 hour/week regular activity; V[Combining Dot Above]O(2max) < 45 mL·min(-1)·kg(-1)), blood pressure 150/95 mm Hg, nonsmoker; 14 subjects were included, 12 could be analyzed. Walking/running 4 times per week at 60% heart rate reserve for 4 weeks. Difference in blood pressure from the initial resting value to 1 and 24 hours after the initial test (acute) and the resting value before the final test (chronic), respectively. Initial resting systolic blood pressure was 134 ± 18 mm Hg. Values were significantly reduced at all time points thereafter (1 hour: 125 ± 13 mm Hg; 24 hours: 128 ± 12 mm Hg; final: 125 ± 18 mm Hg). Acute and chronic changes correlated significantly (1 hour: P = 0.003; r = 0.77; 24 hours: P = 0.017; r = 0.67). Results for diastolic blood pressure were comparable yet less pronounced. The magnitude of postexercise hypotension is a promising candidate for the prediction of individual blood pressure-related training efficacy. Easily determined, it might be used to improve training prescriptions. However, further studies are needed to assess predictive accuracy.

  9. Reduction of hip joint reaction force via medio-lateral foot center of pressure manipulation in bilateral hip osteoarthritis patients.

    PubMed

    Solomonow-Avnon, Deborah; Haim, Amir; Levin, Daniel; Elboim-Gabyzon, Michal; Rozen, Nimrod; Peled, Eli; Wolf, Alon

    2016-10-01

    Loading/excessive loading of the hip joint has been linked to onset and progression of hip osteoarthritis. Footwear-generated biomechanical manipulation in the frontal plane has been previously shown in a cohort of healthy subjects to cause a specific gait adaption when the foot center of pressure trajectory was shifted medially, which thereby significantly reduced hip joint reaction force. The objective of the present study was to validate these results in a cohort of female bilateral hip osteoarthritis patients. Sixteen patients underwent gait analysis while using a footworn biomechanical device, allowing controlled foot center of pressure manipulation, in three para-sagittal configurations: medial, lateral, and neutral. Hip osteoarthritis patients exhibited similar results to those observed in healthy subjects in that a medial center of pressure led to an increase in inter-maleolar distance while step width (i.e., distance between right and left foot center of pressure) remained constant. This adaptation, which we speculate subjects adopt to maintain base of support, was associated with significantly greater hip abduction, significantly decreased hip adduction moment, and significantly reduced joint reaction force compared to the neutral and lateral configurations. Recommendations for treatment of hip osteoarthritis emphasize reduction of loads on the pathological joint(s) during daily activities and especially in gait. Our results show that a medially deviated center of pressure causes a reduction in hip joint reaction force. The present study does not prove, but rather suggests, clinical significance, and further investigation is required to assess clinical implications. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 34:1762-1771, 2016. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc.

  10. Advanced Oil Recovery Technologies for Improved Recovery from Slope Basin Clastic Reservoirs, Nash Draw Brushy Canyon Pool, Eddy County, NM

    SciTech Connect

    Murphy, Mark B.

    1999-02-24

    The Nash Draw Brushy Canyon Pool in Eddy County New Mexico is a cost-shared field demonstration project in the US Department of Energy Class II Program. A major goal of the Class III Program is to stimulate the use of advanced technologies to increase ultimate recovery from slope-basin clastic reservoirs. Advanced characterization techniques are being used at the Nash Draw project to develop reservoir management strategies for optimizing oil recovery from this Delaware reservoir. Analysis, interpretation, and integration of recently acquired geologic, geophysical, and engineering data revealed that the initial reservoir characterization was too simplistic to capture the critical features of this complex formation. Contrary to the initial characterization, a new reservoir description evolved that provided sufficient detail regarding the complexity of the Brushy Canyon interval at Nash Draw. This new reservoir description is being used as a risk reduction tool to identify ''sweet spots'' for a development drilling program as well as to evaluate pressure maintenance strategies. The reservoir characterization, geological modeling, 3-D seismic interpretation, and simulation studies have provided a detailed model of the Brushy Canyon zones. This model was used to predict the success of different reservoir management scenarios and to aid in determining the most favorable combination of targeted drilling, pressure maintenance, well simulation, and well spacing to improve recovery from this reservoir.

  11. Non-invasive assessment of negative pressure wound therapy using high frequency diagnostic ultrasound: oedema reduction and new tissue accumulation.

    PubMed

    Young, Stephen R; Hampton, Sylvie; Martin, Robin

    2013-08-01

    Tissue oedema plays an important role in the pathology of chronic and traumatic wounds. Negative pressure wound therapy (NPWT) is thought to contribute to active oedema reduction, yet few studies have showed this effect. In this study, high frequency diagnostic ultrasound at 20 MHz with an axial resolution of 60 µm was used to assess the effect of NPWT at - 80 mmHg on pressure ulcers and the surrounding tissue. Wounds were monitored in four patients over a 3-month period during which changes in oedema and wound bed thickness (granulation tissue) were measured non-invasively. The results showed a rapid reduction of periwound tissue oedema in all patients with levels falling by a mean of 43% after 4 days of therapy. A 20% increase in the thickness of the wound bed was observed after 7 days due to new granulation tissue formation. Ultrasound scans through the in situ gauze NPWT filler also revealed the existence of macrodeformation in the tissue produced by the negative pressure. These preliminary studies suggest that non-invasive assessment using high frequency diagnostic ultrasound could be a valuable tool in clinical studies of NPWT. © 2012 The Authors. International Wound Journal © 2012 John Wiley & Sons Ltd and Medicalhelplines.com Inc.

  12. Effect of high pressure processing on reduction of Listeria monocytogenes in packaged Queso Fresco

    USDA-ARS?s Scientific Manuscript database

    The effect of high hydrostatic pressure processing (HPP) on the survival of a five-strain rifampicin-resistant cocktail of Listeria monocytogenes in Queso Fresco (QF) was evaluated as a post-packaging intervention. QF was made using pasteurized, homogenized milk, was starter-free and was not pressed...

  13. Control and reduction of unsteady pressure loads in separated shock wave turbulent boundary layer interaction

    NASA Technical Reports Server (NTRS)

    Dolling, David S.; Barter, John W.

    1995-01-01

    The focus was on developing means of controlling and reducing unsteady pressure loads in separated shock wave turbulent boundary layer interactions. Section 1 describes how vortex generators can be used to effectively reduce loads in compression ramp interaction, while Section 2 focuses on the effects of 'boundary-layer separators' on the same interaction.

  14. Impact of Stress Reduction Interventions on Hostility and Ambulatory Systolic Blood Pressure in African American Adolescents

    ERIC Educational Resources Information Center

    Wright, Lynda Brown; Gregoski, Mathew J.; Tingen, Martha S.; Barnes, Vernon A.; Treiber, Frank A.

    2011-01-01

    This study examined the impact of breathing awareness meditation (BAM), life skills (LS) training, and health education (HE) interventions on self-reported hostility and 24-hour ambulatory blood pressure (ABP) in 121 African American (AA) ninth graders at increased risk for development of essential hypertension. They were randomly assigned to BAM,…

  15. Impact of Stress Reduction Interventions on Hostility and Ambulatory Systolic Blood Pressure in African American Adolescents

    ERIC Educational Resources Information Center

    Wright, Lynda Brown; Gregoski, Mathew J.; Tingen, Martha S.; Barnes, Vernon A.; Treiber, Frank A.

    2011-01-01

    This study examined the impact of breathing awareness meditation (BAM), life skills (LS) training, and health education (HE) interventions on self-reported hostility and 24-hour ambulatory blood pressure (ABP) in 121 African American (AA) ninth graders at increased risk for development of essential hypertension. They were randomly assigned to BAM,…

  16. Exploring the effects of data quality, data worth, and redundancy of CO2 gas pressure and saturation data on reservoir characterization through PEST Inversion

    SciTech Connect

    Fang, Zhufeng; Hou, Zhangshuan; Lin, Guang; Engel, David W.; Fang, Yilin; Eslinger, Paul W.

    2014-04-01

    This study examined the impacts of reservoir properties on CO2 migration after subsurface injection and evaluated the possibility of characterizing reservoir properties using CO2 monitoring data such as saturation distribution. The injection reservoir was assumed to be located 1400-1500 m below the ground surface such that CO2 remained in the supercritical state. The reservoir was assumed to contain layers with alternating conductive and resistive properties, which is analogous to actual geological formations such as the Mount Simon Sandstone unit. The CO2 injection simulation used a cylindrical grid setting in which the injection well was situated at the center of the domain, which extended up to 8000 m from the injection well. The CO2 migration was simulated using the PNNL-developed simulator STOMP-CO2e (the water-salt-CO2 module). We adopted a nonlinear parameter estimation and optimization modeling software package, PEST, for automated reservoir parameter estimation. We explored the effects of data quality, data worth, and data redundancy on the detectability of reservoir parameters using CO2 saturation monitoring data, by comparing PEST inversion results using data with different levels of noises, various numbers of monitoring wells and locations, and different data collection spacing and temporal sampling intervals. This study yielded insight into the use of CO2 saturation monitoring data for reservoir characterization and how to design the monitoring system to optimize data worth and reduce data redundancy.

  17. Carbonate petroleum reservoirs

    SciTech Connect

    Roehl, P.O.; Choquette, P.W.

    1985-01-01

    This book presents papers on the geology of petroleum deposits. Topics considered include diagenesis, porosity, dolomite reservoirs, deposition, reservoir rock, reefs, morphology, fracture-controlled production, Cenozoic reservoirs, Mesozoic reservoirs, and Paleozoic reservoirs.

  18. Numerical simulation of the environmental impact of hydraulic fracturing of tight/shale gas reservoirs on near-surface groundwater: Background, base cases, shallow reservoirs, short-term gas, and water transport.

    PubMed

    Reagan, Matthew T; Moridis, George J; Keen, Noel D; Johnson, Jeffrey N

    2015-04-01

    Hydrocarbon production from unconventional resources and the use of reservoir stimulation techniques, such as hydraulic fracturing, has grown explosively over the last decade. However, concerns have arisen that reservoir stimulation creates significant environmental threats through the creation of permeable pathways connecting the stimulated reservoir with shallower freshwater aquifers, thus resulting in the contamination of potable groundwater by escaping hydrocarbons or other reservoir fluids. This study investigates, by numerical simulation, gas and water transport between a shallow tight-gas reservoir and a shallower overlying freshwater aquifer following hydraulic fracturing operations, if such a connecting pathway has been created. We focus on two general failure scenarios: (1) communication between the reservoir and aquifer via a connecting fracture or fault and (2) communication via a deteriorated, preexisting nearby well. We conclude that the key factors driving short-term transport of gas include high permeability for the connecting pathway and the overall volume of the connecting feature. Production from the reservoir is likely to mitigate release through reduction of available free gas and lowering of reservoir pressure, and not producing may increase the potential for release. We also find that hydrostatic tight-gas reservoirs are unlikely to act as a continuing source of migrating gas, as gas contained within the newly formed hydraulic fracture is the primary source for potential contamination. Such incidents of gas escape are likely to be limited in duration and scope for hydrostatic reservoirs. Reliable field and laboratory data must be acquired to constrain the factors and determine the likelihood of these outcomes.

  19. Numerical simulation of the environmental impact of hydraulic fracturing of tight/shale gas reservoirs on near-surface groundwater: Background, base cases, shallow reservoirs, short-term gas, and water transport

    NASA Astrophysics Data System (ADS)

    Reagan, Matthew T.; Moridis, George J.; Keen, Noel D.; Johnson, Jeffrey N.

    2015-04-01

    Hydrocarbon production from unconventional resources and the use of reservoir stimulation techniques, such as hydraulic fracturing, has grown explosively over the last decade. However, concerns have arisen that reservoir stimulation creates significant environmental threats through the creation of permeable pathways connecting the stimulated reservoir with shallower freshwater aquifers, thus resulting in the contamination of potable groundwater by escaping hydrocarbons or other reservoir fluids. This study investigates, by numerical simulation, gas and water transport between a shallow tight-gas reservoir and a shallower overlying freshwater aquifer following hydraulic fracturing operations, if such a connecting pathway has been created. We focus on two general failure scenarios: (1) communication between the reservoir and aquifer via a connecting fracture or fault and (2) communication via a deteriorated, preexisting nearby well. We conclude that the key factors driving short-term transport of gas include high permeability for the connecting pathway and the overall volume of the connecting feature. Production from the reservoir is likely to mitigate release through reduction of available free gas and lowering of reservoir pressure, and not producing may increase the potential for release. We also find that hydrostatic tight-gas reservoirs are unlikely to act as a continuing source of migrating gas, as gas contained within the newly formed hydraulic fracture is the primary source for potential contamination. Such incidents of gas escape are likely to be limited in duration and scope for hydrostatic reservoirs. Reliable field and laboratory data must be acquired to constrain the factors and determine the likelihood of these outcomes.

  20. Stepping Up the Pressure: Arousal Can Be Associated with a Reduction in Male Aggression

    PubMed Central

    Ward, Andrew; Mann, Traci; Westling, Erika H.; Creswell, J. David; Ebert, Jeffrey P.; Wallaert, Matthew

    2009-01-01

    The attentional myopia model of behavioral control (Mann & Ward, 2007) was tested in an experiment investigating the relationship between physiological arousal and aggression. Drawing on previous work linking arousal and narrowed attentional focus, the model predicts that arousal will lead to behavior that is relatively disinhibited in situations in which promoting pressures to aggress are highly salient. In situations in which inhibitory pressures are more salient, the model predicts behavior that is relatively restrained. In the experiment, 81 male undergraduates delivered noise-blasts against a provoking confederate while experiencing either high or low levels of physiological arousal and, at the same time, being exposed to cues that served either to promote or inhibit aggression. In addition to supporting the predictions of the model, this experiment provided some of the first evidence for enhanced control of aggression under conditions of heightened physiological arousal. Implications for interventions designed to reduce aggression are discussed. PMID:18561301

  1. Stepping up the pressure: arousal can be associated with a reduction in male aggression.

    PubMed

    Ward, Andrew; Mann, Traci; Westling, Erika H; David Creswell, J; Ebert, Jeffrey P; Wallaert, Matthew

    2008-01-01

    The attentional myopia model of behavioral control [Mann and Ward, 2007] was tested in an experiment investigating the relationship between physiological arousal and aggression. Drawing on previous work linking arousal and narrowed attentional focus, the model predicts that arousal will lead to behavior that is relatively disinhibited in situations in which promoting pressures to aggress are highly salient. In situations in which inhibitory pressures are more salient, the model predicts behavior that is relatively restrained. In the experiment, 81 male undergraduates delivered noise-blasts against a provoking confederate while experiencing either high or low levels of physiological arousal and, at the same time, being exposed to cues that served either to promote or inhibit aggression. In addition to supporting the predictions of the model, this experiment provided some of the first evidence for enhanced control of aggression under conditions of heightened physiological arousal. Implications for interventions designed to reduce aggression are discussed. 2008 Wiley-Liss, Inc.

  2. Long-Term Reduction of High Blood Pressure by Angiotensin II DNA Vaccine in Spontaneously Hypertensive Rats.

    PubMed

    Koriyama, Hiroshi; Nakagami, Hironori; Nakagami, Futoshi; Osako, Mariana Kiomy; Kyutoku, Mariko; Shimamura, Munehisa; Kurinami, Hitomi; Katsuya, Tomohiro; Rakugi, Hiromi; Morishita, Ryuichi

    2015-07-01

    Recent research on vaccination has extended its scope from infectious diseases to chronic diseases, including Alzheimer disease, dyslipidemia, and hypertension. The aim of this study was to design DNA vaccines for high blood pressure and eventually develop human vaccine therapy to treat hypertension. Plasmid vector encoding hepatitis B core-angiotensin II (Ang II) fusion protein was injected into spontaneously hypertensive rats using needleless injection system. Anti-Ang II antibody was successfully produced in hepatitis B core-Ang II group, and antibody response against Ang II was sustained for at least 6 months. Systolic blood pressure was consistently lower in hepatitis B core-Ang II group after immunization, whereas blood pressure reduction was continued for at least 6 months. Perivascular fibrosis in heart tissue was also significantly decreased in hepatitis B core-Ang II group. Survival rate was significantly improved in hepatitis B core-Ang II group. This study demonstrated that Ang II DNA vaccine to spontaneously hypertensive rats significantly lowered high blood pressure for at least 6 months. In addition, Ang II DNA vaccines induced an adequate humoral immune response while avoiding the activation of self-reactive T cells, assessed by ELISPOT assay. Future development of DNA vaccine to treat hypertension may provide a new therapeutic option to treat hypertension.

  3. Fluid shifts, vasodilatation and ambulatory blood pressure reduction during long duration spaceflight

    PubMed Central

    Norsk, Peter; Asmar, Ali; Damgaard, Morten; Christensen, Niels Juel

    2015-01-01

    Acute weightlessness in space induces a fluid shift leading to central volume expansion. Simultaneously, blood pressure is either unchanged or decreased slightly. Whether these effects persist for months in space is unclear. Twenty-four hour ambulatory brachial arterial pressures were automatically recorded at 1–2 h intervals with portable equipment in eight male astronauts: once before launch, once between 85 and 192 days in space on the International Space Station and, finally, once at least 2 months after flight. During the same 24 h, cardiac output (rebreathing method) was measured two to five times (on the ground seated), and venous blood was sampled once (also seated on the ground) for determination of plasma catecholamine concentrations. The 24 h average systolic, diastolic and mean arterial pressures (mean ± se) in space were reduced by 8 ± 2 mmHg (P = 0.01; ANOVA), 9 ± 2 mmHg (P < 0.001) and 10 ± 3 mmHg (P = 0.006), respectively. The nightly blood pressure dip of 8 ± 3 mmHg (P = 0.015) was maintained. Cardiac stroke volume and output increased by 35 ± 10% and 41 ± 9% (P < 0.001); heart rate and catecholamine concentrations were unchanged; and systemic vascular resistance was reduced by 39 ± 4% (P < 0.001). The increase in cardiac stroke volume and output is more than previously observed during short duration flights and might be a precipitator for some of the vision problems encountered by the astronauts. The spaceflight vasodilatation mechanism needs to be explored further. PMID:25774397

  4. Effect of continuous smoking reduction and abstinence on blood pressure and heart rate in smokers switching to electronic cigarettes.

    PubMed

    Farsalinos, Konstantinos; Cibella, Fabio; Caponnetto, Pasquale; Campagna, Davide; Morjaria, Jaymin Bhagwanji; Battaglia, Eliana; Caruso, Massimo; Russo, Cristina; Polosa, Riccardo

    2016-02-01

    We present prospective blood pressure (BP) and hear rate (HR) changes in smokers invited to switch to e-cigarettes in the ECLAT study. BP and HR changes were compared among (1) different study groups (users of high, low, and zero nicotine products) and (2) pooled continuous smoking phenotype classification (same phenotype from week 12 to -52), with participants classified as quitters (completely quit smoking), reducers (≥50% reduction in smoking consumption) and failures (<50% or no reduction in smoking consumption). Additionally, the latter comparison was repeated in a subgroup of participants with elevated BP at baseline. No significant changes were observed among study groups for systolic BP, diastolic BP, and HR. In 145 subjects with a continuous smoking phenotype, we observed lower systolic BP at week 52 compared to baseline but no effect of smoking phenotype classification. When the same analysis was repeated in 66 subjects with elevated BP at baseline, a substantial reduction in systolic BP was observed at week 52 compared to baseline (132.4 ± 12.0 vs. 141.2 ± 10.5 mmHg, p < 0.001), with a significant effect found for smoking phenotype classification. After adjusting for weight change, gender and age, reduction in systolic BP from baseline at week 52 remains associated significantly with both smoking reduction and smoking abstinence. In conclusion, smokers who reduce or quit smoking by switching to e-cigarettes may lower their systolic BP in the long term, and this reduction is apparent in smokers with elevated BP. The current study adds to the evidence that quitting smoking with the use of e-cigarettes does not lead to higher BP values, and this is independently observed whether e-cigarettes are regularly used or not.

  5. Comparison of Clevidipine and Nicardipine for Acute Blood Pressure Reduction in Patients With Stroke.

    PubMed

    Allison, Teresa A; Bowman, Stephanie; Gulbis, Brian; Hartman, Heather; Schepcoff, Sara; Lee, Kiwon

    2017-01-01

    The aim of this study was to determine whether clevidipine (CLEV) achieved faster blood pressure control compared to nicardipine (NIC) in patients presenting with either an acute ischemic stroke (AIS) or a spontaneous intracerebral hemorrhage (ICH). This was a retrospective, observational, cohort study conducted in patients with AIS or ICH admitted to the emergency department of a Comprehensive Stroke Center from November 2011 to June 2013 who received CLEV or NIC continuous infusion for acute blood pressure management. The study included 210 patients: 70 in the CLEV group and 140 in the NIC group. There was no difference in mean time (standard deviation [SD]) from initiation of the infusion to goal systolic blood pressure (SBP), CLEV: 50 (83) minutes versus NIC: 74 (103) minutes, P = .101. Comparison of the 2 agents within diagnosis showed no difference. Hypotension developed in 5 (7.1%) CLEV patients versus 14 (10%) NIC patients ( P = .003). There was no difference in the percentage change at 2 hours; CLEV: -20% (16%) versus NIC: -16% (16%), P = .058. Mean (SD) time to alteplase administration from admission was 56 (22) minutes in the CLEV group versus 59 (25) minutes in the NIC group ( P = .684). There was no difference in the mean time from initiation of the infusion to the SBP goal between agents or in the secondary outcomes. Due to the lack of differences observed, each agent should be considered based on the patient care needs of the institution.

  6. Contact-pressure reduction of pyramidal optical probe array on corrugated aluminium/silicon nitride membranes

    NASA Astrophysics Data System (ADS)

    Jang, Jinhee; Oh, Seonghyeon; Hahn, Jae W.

    2017-04-01

    In this study, we develop an optical contact probe array for scanning near-field lithography. We fabricate the optical probes with a pyramidal tip array on an aluminium/silicon nitride composite membrane. Here, we reduce the contact pressure using the corrugations on the silicon nitride membrane and the flattened surface on top of the tip. After fabricating the 5  ×  5 probes in the array, we evaluate the contact pressure using the force–distance curve obtained by an atomic force microscope. The spring constants of the corrugated membranes are 10  ±  0.6 N m‑1. The contact pressure on a flattened 295 nm in-radius is calculated to be approximately 33 MPa for a 300 nm deflection. This value is 22 times smaller than that of a sharp pyramidal tip of 20 nm in-radius on a flat membrane.

  7. Environmental pressure reduction with a new method of noble metal recovery

    NASA Astrophysics Data System (ADS)

    Filippova, EV

    2017-02-01

    Discoveries in the area of hydrometallurgy of noble metals can be of use in metal recovery from low-grade solutions and slurries, including liquid tailings. Efficiency of noble metal recovery and reduction in mining waste is gained owing to utilization of two forms of ion-exchange sorbent, including OH- for recovery of cyanic compounds of gold and cyanides, which allows abating burden on natural systems.

  8. 49 CFR 393.50 - Reservoirs required.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    .... Each service reservoir system on a motor vehicle shall be protected against a loss of air pressure or vacuum due to a failure or leakage in the system between the service reservoir and the source of air... pressure or vacuum below 70 percent of that indicated by the air or vacuum gauge immediately before the...

  9. Exercise performance in patients with uncomplicated essential hypertension. Effects of nifedipine-induced acute blood pressure reduction.

    PubMed

    Agostoni, P; Doria, E; Berti, M; Alimento, M; Tamborini, G; Fiorentini, C

    1992-06-01

    In untreated patients with uncomplicated essential hypertension, exercise induces an abnormal increase in blood pressure; the influences of this increase on exercise were evaluated by a cardiopulmonary exercise test (CPX) performed in control conditions (step 1) and during acute blood pressure reduction (step 2). Patients were classified as (1) normotensive (resting diastolic blood pressure [BPd] less than 90 mm Hg; n = 14), (2) mildly hypertensive (BPd of 90 to 104 mm Hg; n = 9), and (3) moderately to severely hypertensive (BPd greater than or equal to 105 mm Hg; n = 16). For the three groups, peak mean blood pressure during exercise was 125 +/- 5 mm Hg (mean +/- SEM), 144 +/- 3 mm Hg (p less than 0.01 vs normotensive), and 161 +/- 4 mm Hg (p less than 0.01 vs normotensive and p less than 0.01 vs mild hypertension), respectively. Oxygen consumption (VO2) at peak exercise and at ventilatory anaerobic threshold was 26.1 +/- 1.1 and 17.2 +/- 0.5 ml/min/kg, 25.4 +/- 1.1 and 16.9 +/- 0.8 ml/min/kg, and 26.4 +/- 1.3 and 17.5 +/- 1.2 ml/min/kg in normotensive subjects, those with mild hypertension, and those with moderate to severe hypertension, respectively. Fourteen normotensive subjects, six with mild hypertension, and nine with moderate to severe hypertension participated to step 2 (nifedipine vs placebo, double-blind crossover). Nifedipine reduced blood pressure at rest and at peak exercise in those with hypertension. Peak exercise VO2 was unaffected by nifedipine in both normotensive subjects and those with hypertension. With nifedipine, ventilatory anaerobic threshold occurred earlier and at a lower VO2 in mild and in moderate to severe hypertension (delta VO2 = -1.9 and -2.4 ml/min/kg, respectively). These findings might be due to nifedipine-induced redistribution of blood flow during exercise and might be the reason for the complaint of weakness after blood pressure reduction in hypertensive subjects.

  10. a Review of the Hydrogen Reduction of Ruby at Megabar Pressure

    NASA Astrophysics Data System (ADS)

    Ruoff, Arthur L.

    It is shown that the available optical data on composites of hydrogen and Al2O3 are an indirect proof of the presence of metallic Al formed in the reaction Al2O3 + 0.75 H2 = 1.5 AlOOH + 0.5 Al at 177 GPa. The AlOOH (diaspore) Raman peak for the OH stretching mode is not strong and is very broad. This unfortunately eliminates one direct method of showing that the reaction proceeds. It is shown that recent arguments attempting to show that Al does not form at high pressure are invalid.

  11. Magnitude of blood pressure reduction in the placebo arms of modern hypertension trials: implications for trials of renal denervation.

    PubMed

    Patel, Hitesh C; Hayward, Carl; Ozdemir, Baris Ata; Rosen, Stuart D; Krum, Henry; Lyon, Alexander R; Francis, Darrel P; di Mario, Carlo

    2015-02-01

    Early phase studies of novel interventions for hypertension, such as renal sympathetic denervation, are sometimes single-armed (uncontrolled). We explored the wisdom of this by quantifying the blood pressure fall in the placebo arms of contemporary trials of hypertension. We searched Medline up to June 2014 and identified blinded, randomized trials of hypertension therapy in which the control arm received placebo medication or a sham (placebo) procedure. For nonresistant hypertension, we have identified all such trials of drugs licensed by the US Food and Drug Administration since 2000 (5 drugs). This US Food and Drug Administration-related restriction was not applied to resistant hypertension trials. This produced 7451 patients, who were allocated to a blinded control from 52 trials of nonresistant hypertension and 694 patients from 8 trials of resistant hypertension (3 drugs and 2 interventions). Systolic blood pressure fell by 5.92 mm Hg (95% confidence interval, 5.14-6.71; P<0.0001) in the nonresistant cohort and by 8.76 mm Hg (95% confidence interval, 4.83-12.70; P<0.0001) in the resistant cohort. Using metaregression, the falls were larger in trials that did not use ambulatory blood pressure monitoring as an inclusion criterion (z=2.84; P=0.0045), in those with higher baseline blood pressures (z=-0.3; P=0.0001), and in those where the patients were prescribed a continuous background of antihypertensives (z=-2.72; P=0.0065). The nontrivial magnitude of these apparent blood pressure reductions with perfectly ineffective intervention (placebo) illustrates that efficacy explorations of novel therapies for hypertension, once safety is established, should be performed with a randomized, appropriately controlled, and blinded design.

  12. The comparison of intraocular pressure reductions after isometric and isokinetic exercises in normal individuals.

    PubMed

    Avunduk, A M; Yilmaz, B; Sahin, N; Kapicioglu, Z; Dayanir, V

    1999-01-01

    The lowering effect of physical exercise on intraocular pressure (IOP) has been reported both in healthy people and those with glaucoma, but a comparison of the lowering effect of isometric and isokinetic exercises on IOP has not been conducted in any study. Our aims were to investigate the relationship between intensity of exercise and IOP, and whether a significant difference in IOP lowering effect existed between isometric and isokinetic exercises. Sixty-seven patients with an age range of 23-40 who had no ocular disease were randomly divided into two groups. While 31 patients in the first group, group A, performed isokinetic exercise with the Cybex 6000 dynamometer, 32 patients in the second group, group B, had isometric exercises with the same machine. IOP was measured in the right eye of patients with Shiotz tonometer just before and 10 min following exercise. Exercise intensity and total energy consumption were determined by the machine for each patient. While IOP values measured before exercise, the degree of exercise applied, and total energy consumption did not differ significantly between groups, both isometric and isotonic exercises lowered IOP significantly. As a result, isometric and isokinetic exercises lowered IOP in ophthalmologically normal subjects with direct relationship to exercise intensity and total energy consumption. Since the pressure lowering effect of isokinetic exercise was more significant, it might prove useful to glaucomatous patients.

  13. Ambulatory blood pressure reduction following high-intensity interval exercise performed in water or dryland condition.

    PubMed

    Sosner, Philippe; Gayda, Mathieu; Dupuy, Olivier; Garzon, Mauricio; Lemasson, Christopher; Gremeaux, Vincent; Lalongé, Julie; Gonzales, Mariel; Hayami, Douglas; Juneau, Martin; Nigam, Anil; Bosquet, Laurent

    2016-05-01

    We aimed to compare blood pressure (BP) responses following moderate-intensity continuous exercise (MICE), high-intensity interval exercise (HIIE) in dry land or HIIE in immersed condition, using 24-hour ambulatory BP monitoring. Forty-two individuals (65 ± 7 years, 52% men) with a baseline BP ≥ 130/85 mm Hg (systolic/diastolic blood pressures [SBP/DBP]) were randomly assigned to perform one of the three following exercises on a stationary cycle: MICE (24 minutes at 50% peak power output) or HIIE in dry land (two sets of 10 minutes with phases of 15 seconds 100% peak power output interspersed by 15 seconds of passive recovery) or HIIE in up-to-the-chest immersed condition. While MICE modified none of the 24-hour average hemodynamic variables, dryland HIIE induced a 24-hour BP decrease (SBP: -3.6 ± 5.7/DBP: -2.8 ± 3.0 mm Hg, P < .05) and, to a much greater extent, immersed HIIE (SBP: -6.8 ± 9.5/DBP: -3.0 ± 4.5 mm Hg, P < .05). The one condition that modified 24-hour pulse-wave velocity was immersed HIIE (-0.21 ± 0.30 m/s, P < .05).

  14. Lens Position Parameters as Predictors of Intraocular Pressure Reduction After Cataract Surgery in Nonglaucomatous Patients With Open Angles

    PubMed Central

    Hsu, Chi-Hsin; Kakigi, Caitlin L.; Lin, Shuai-Chun; Wang, Yuan-Hung; Porco, Travis; Lin, Shan C.

    2015-01-01

    Purpose To evaluate the relationship between lens position parameters and intraocular pressure (IOP) reduction after cataract surgery in nonglaucomatous eyes with open angles. Methods The main outcome of the prospective study was percentage of IOP change, which was calculated using the preoperative IOP and the IOP 4 months after cataract surgery in nonglaucomatous eyes with open angles. Lens position (LP), defined as anterior chamber depth (ACD) + 1/2 lens thickness (LT), was assessed preoperatively using parameters from optical biometry. Preoperative IOP, central corneal thickness, ACD, LT, axial length (AXL), and the ratio of preoperative IOP to ACD (PD ratio) were also evaluated as potential predictors of percentage of IOP change. The predictive values of the parameters we found to be associated with the primary outcome were compared. Results Four months after cataract surgery, the average IOP reduction was 2.03 ± 2.42 mm Hg, a 12.74% reduction from the preoperative mean of 14.5 ± 3.05 mm Hg. Lens position was correlated with IOP reduction percentage after adjusting for confounders (P = 0.002). Higher preoperative IOP, shallower ACD, shorter AXL, and thicker LT were significantly associated with percentage of IOP decrease. Although not statistically significant, LP was a better predictor of percentage of IOP change compared to PD ratio, preoperative IOP, and ACD. Conclusions The percentage of IOP reduction after cataract surgery in nonglaucomatous eyes with open angles is greater in more anteriorly positioned lenses. Lens position, which is convenient to compute by basic ocular biometric data, is an accessible predictor with considerable predictive value for postoperative IOP change. PMID:26650901

  15. Hypersensitivity of mesenteric veins to 5-hydroxytryptamine- and ketanserin-induced reduction of portal pressure in portal hypertensive rats.

    PubMed Central

    Cummings, S. A.; Groszmann, R. J.; Kaumann, A. J.

    1986-01-01

    Isolated superior mesenteric veins from portal hypertensive rats were 3 to 10 times more sensitive to 5-hydroxytryptamine (5-HT) and 3 times less sensitive to (-)-noradrenaline than veins from sham-operated rats. The sensitivity to vasopressin did not differ in the 2 groups. Ketanserin competitively antagonized the effects of 5-HT in superior mesenteric veins and portal veins with high affinity (KB values 0.1-0.3 nM), as expected for 5-HT2-receptors. The affinity of ketanserin for 5-HT2-receptors was similar in veins from normal, sham-operated or portal-hypertensive rats. Intraportal injections of low doses of 5-HT caused increases in portal pressure which were more pronounced in portal hypertensive rats than in sham-operated rats and were blocked by 0.3 mg kg-1 ketanserin in both groups. Ketanserin 0.3 mg kg-1 did not block the portal pressor response to (-)-noradrenaline in either group of rats. In portal hypertensive rats but not in sham-operated rats, 0.3 mg kg-1 ketanserin caused decreases in portal pressure, portal flow and cardiac output, as estimated by radioactive microspheres. The reduction in portal pressure caused by ketanserin was due mainly to a decrease in portal venous inflow secondary to a decreased cardiac output. The reduction in cardiac output, which was observed only in the portal hypertensive rats but not in sham-operated rats, is consistent with venous dilatation and pooling of blood in the portal venous system. The venous pooling could be secondary to the blockade of 5-HT2-receptors in the portal venous system. It is proposed that ketanserin should be explored for the treatment of patients with portal hypertension. PMID:3801785

  16. Antihypertensive combination therapy: optimizing blood pressure control and cardiovascular risk reduction.

    PubMed

    Nesbitt, Shawna D

    2007-11-01

    Treating hypertension reduces the rates of myocardial infarction, stroke, and renal disease; however, clinical trial experience suggests that monotherapy is not likely to be successful for achieving goal blood pressure (BP) levels in many hypertensive patients. In multiple recent clinical trials including various subsets of hypertensive patients, the achievement of BP goal has typically required the combination of 2 or more medications, particularly in patients with BP levels>160/100 mm Hg. When initiating combination therapy for hypertension, careful consideration must be given to the choice of medication. Clinical trial evidence has shown the efficacy of various combinations of angiotensin-converting enzyme inhibitors, angiotensin II receptor blockers, calcium channel blockers, and diuretics in reducing BP and cardiovascular risk. Ongoing trials should provide additional guidance on the optimal choice of combination regimens in specific clinical settings.

  17. Efficacy of combined cataract extraction and endoscopic cyclophotocoagulation for the reduction of intraocular pressure and medication burden

    PubMed Central

    Roberts, Sammie J.; Mulvahill, Matthew; SooHoo, Jeffrey R.; Pantcheva, Mina B.; Kahook, Malik Y.; Seibold, Leonard K.

    2016-01-01

    AIM To report on the efficacy of combined endoscopic cyclophotocoagulation (ECP) and phacoemulsification cataract extraction (PCE) with intraocular lens placement for reduction of intraocular pressure (IOP) and medication burden in glaucoma. METHODS A retrospective case review of 91 eyes (73 patients) with glaucoma and cataract that underwent combined PCE/ECP surgery was performed. Baseline demographic and ocular characteristics were recorded, as well as intraocular pressure, number of glaucoma medications, and visual acuity postoperatively with 12-month follow-up. Treatment failure was defined as less than 20% reduction in IOP from baseline on two consecutive visits (at 1, 3, 6, or 12mo postoperatively), IOP ≥21 mm Hg or ≤5 mm Hg on two consecutive visits, or additional glaucoma surgery performed within 12mo after PCE/ECP. RESULTS Overall, mean medicated IOP was reduced from 16.65 mm Hg at baseline to 13.38 mm Hg at 12mo (P<0.0001). Mean number of glaucoma medications was reduced from 1.88 medications at baseline to 1.48 medications at 12mo (P=0.0003). At 3mo postoperatively, the success rate was 73.6% (95%CI: 63.3, 81.5), 57.1% at 6mo (95% CI: 46.3, 66.6), and 49.7% at 12mo (95%CI: 38.9, 59.6). Patient demographic characteristics were not associated with treatment success. The only ocular characteristic associated with treatment success was a higher baseline IOP. CONCLUSION Combined PCE/ECP surgery is an effective surgical option for the reduction of IOP and medication burden in glaucoma patients. Patients with higher baseline IOP levels are most likely to benefit from this procedure. PMID:27275423

  18. AUTOMATED TECHNIQUE FOR FLOW MEASUREMENTS FROM MARIOTTE RESERVOIRS.

    USGS Publications Warehouse

    Constantz, Jim; Murphy, Fred

    1987-01-01

    The mariotte reservoir supplies water at a constant hydraulic pressure by self-regulation of its internal gas pressure. Automated outflow measurements from mariotte reservoirs are generally difficult because of the reservoir's self-regulation mechanism. This paper describes an automated flow meter specifically designed for use with mariotte reservoirs. The flow meter monitors changes in the mariotte reservoir's gas pressure during outflow to determine changes in the reservoir's water level. The flow measurement is performed by attaching a pressure transducer to the top of a mariotte reservoir and monitoring gas pressure changes during outflow with a programmable data logger. The advantages of the new automated flow measurement techniques include: (i) the ability to rapidly record a large range of fluxes without restricting outflow, and (ii) the ability to accurately average the pulsing flow, which commonly occurs during outflow from the mariotte reservoir.

  19. Acidic Electrolyzed Water as a Novel Transmitting Medium for High Hydrostatic Pressure Reduction of Bacterial Loads on Shelled Fresh Shrimp

    PubMed Central

    Du, Suping; Zhang, Zhaohuan; Xiao, Lili; Lou, Yang; Pan, Yingjie; Zhao, Yong

    2016-01-01

    Acidic electrolyzed water (AEW), a novel non-thermal sterilization technology, is widely used in the food industry. In this study, we firstly investigated the effect of AEW as a new pressure transmitting medium for high hydrostatic pressure (AEW-HHP) processing on microorganisms inactivation on shelled fresh shrimp. The optimal conditions of AEW-HHP for Vibrio parahaemolyticus inactivation on sterile shelled fresh shrimp were obtained using response surface methodology: NaCl concentration to electrolysis 1.5 g/L, treatment pressure 400 MPa, treatment time 10 min. Under the optimal conditions mentioned above, AEW dramatically enhanced the efficiency of HHP for inactivating V. parahaemolyticus and Listeria monocytogenes on artificially contaminated shelled fresh shrimp, and the log reductions were up to 6.08 and 5.71 log10 CFU/g respectively, while the common HHP could only inactivate the two pathogens up to 4.74 and 4.31 log10 CFU/g respectively. Meanwhile, scanning electron microscopy (SEM) showed the same phenomenon. For the naturally contaminated shelled fresh shrimp, AEW-HHP could also significantly reduce the micro flora when examined using plate count and PCR-DGGE. There were also no significant changes, histologically, in the muscle tissues of shrimps undergoing the AEW-HHP treatment. In summary, using AEW as a new transmitting medium for HHP processing is an innovative non thermal technology for improving the food safety of shrimp and other aquatic products. PMID:27014228

  20. Reduction of salt in pork sausages by the addition of carrot fibre or potato starch and high pressure treatment.

    PubMed

    Grossi, Alberto; Søltoft-Jensen, Jakob; Knudsen, Jes Christian; Christensen, Mette; Orlien, Vibeke

    2012-12-01

    The combined effect of high pressure processing (HPP) (400, 600 and 800 MPa) and carrot fibre (CF) and potato starch (PS) on low salt (1.2%) pork sausages was investigated and compared with high (1.8%) salt sausages. Sausages had a marked increase in whitening with increasing content of fibre or starch, pressure level, and process temperature. The degree of redness was mainly affected by pressure level and heat treatment. An important finding regarding salt reduction was that the use of starch or fibre had more impact on textural properties than the level of salt since Young's modulus and strain at fracture were mainly affected by formulation and HPP. Water binding capacity of low salt sausages was improved to the same level as high salt sausages with HPP and addition of CF or PS particularly by the addition of PS which produced sausages with better sensory properties than CF. The sensory analysis showed that this approach is promising for producing low salt sausages.

  1. Acidic Electrolyzed Water as a Novel Transmitting Medium for High Hydrostatic Pressure Reduction of Bacterial Loads on Shelled Fresh Shrimp.

    PubMed

    Du, Suping; Zhang, Zhaohuan; Xiao, Lili; Lou, Yang; Pan, Yingjie; Zhao, Yong

    2016-01-01

    Acidic electrolyzed water (AEW), a novel non-thermal sterilization technology, is widely used in the food industry. In this study, we firstly investigated the effect of AEW as a new pressure transmitting medium for high hydrostatic pressure (AEW-HHP) processing on microorganisms inactivation on shelled fresh shrimp. The optimal conditions of AEW-HHP for Vibrio parahaemolyticus inactivation on sterile shelled fresh shrimp were obtained using response surface methodology: NaCl concentration to electrolysis 1.5 g/L, treatment pressure 400 MPa, treatment time 10 min. Under the optimal conditions mentioned above, AEW dramatically enhanced the efficiency of HHP for inactivating V. parahaemolyticus and Listeria monocytogenes on artificially contaminated shelled fresh shrimp, and the log reductions were up to 6.08 and 5.71 log10 CFU/g respectively, while the common HHP could only inactivate the two pathogens up to 4.74 and 4.31 log10 CFU/g respectively. Meanwhile, scanning electron microscopy (SEM) showed the same phenomenon. For the naturally contaminated shelled fresh shrimp, AEW-HHP could also significantly reduce the micro flora when examined using plate count and PCR-DGGE. There were also no significant changes, histologically, in the muscle tissues of shrimps undergoing the AEW-HHP treatment. In summary, using AEW as a new transmitting medium for HHP processing is an innovative non thermal technology for improving the food safety of shrimp and other aquatic products.

  2. Effect of high-pressure processing on reduction of Listeria monocytogenes in packaged Queso Fresco.

    PubMed

    Tomasula, P M; Renye, J A; Van Hekken, D L; Tunick, M H; Kwoczak, R; Toht, M; Leggett, L N; Luchansky, J B; Porto-Fett, A C S; Phillips, J G

    2014-03-01

    The effect of high-hydrostatic-pressure processing (HPP) on the survival of a 5-strain rifampicin-resistant cocktail of Listeria monocytogenes in Queso Fresco (QF) was evaluated as a postpackaging intervention. Queso Fresco was made using pasteurized, homogenized milk, and was starter-free and not pressed. In phase 1, QF slices (12.7 × 7.6 × 1 cm), weighing from 52 to 66 g, were surface inoculated with L. monocytogenes (ca. 5.0 log10 cfu/g) and individually double vacuum packaged. The slices were then warmed to either 20 or 40°C and HPP treated at 200, 400, and 600 MPa for hold times of 5, 10, 15, or 20 min. Treatment at 600 MPa was most effective in reducing L. monocytogenes to below the detection level of 0.91 log10 cfu/g at all hold times and temperatures. High-hydrostatic-pressure processing at 40°C, 400 MPa, and hold time ≥ 15 min was effective but resulted in wheying-off and textural changes. In phase 2, L. monocytogenes was inoculated either on the slices (ca. 5.0 log10 cfu/g; ON) or in the curds (ca. 7.0 log10 cfu/g; IN) before the cheese block was formed and sliced. The slices were treated at 20°C and 600 MPa at hold times of 3, 10, and 20 min, and then stored at 4 and 10°C for 60 d. For both treatments, L. monocytogenes became less resistant to pressure as hold time increased, with greater percentages of injured cells at 3 and 10 min than at 20 min, at which the lethality of the process increased. For the IN treatment, with hold times of 3 and 10 min, growth of L. monocytogenes increased the first week of storage, but was delayed for 1 wk, with a hold time of 20 min. Longer lag times in growth of L. monocytogenes during storage at 4°C were observed for the ON treatment at hold times of 10 and 20 min, indicating that the IN treatment may have provided a more protective environment with less injury to the cells than the ON treatment. Similarly, HPP treatment for 10 min followed by storage at 4°C was the best method for suppressing the growth of

  3. EFFECTS OF DIETARY SODIUM REDUCTION ON BLOOD PRESSURE IN SUBJECTS WITH RESISTANT HYPERTENSION: RESULTS FROM A RANDOMIZED TRIAL

    PubMed Central

    Pimenta, Eduardo; Gaddam, Krishna K.; Oparil, Suzanne; Aban, Inmaculada; Husain, Saima; Dell’Italia, Louis J.; Calhoun, David A.

    2009-01-01

    Observational studies indicate a significant relation between dietary sodium and level of blood pressure. However, the role of salt sensitivity in the development of resistant hypertension is unknown. The present study examined the effects of dietary salt restriction on office and 24-hr ambulatory blood pressure in subjects with resistant hypertension. Twelve subjects with resistant hypertension entered into a randomized, cross-over evaluation of low (50 mmol/24-hr × 7 days) and high sodium diets (250 mmol/24-hr × 7 days) separated by a 2-week washout period. Brain natriuretic peptide; plasma renin activity; 24-hr urinary aldosterone, sodium, and potassium; 24-hr ambulatory blood pressure monitoring; aortic pulse wave velocity; and augmentation index were compared between dietary treatment periods. At baseline, subjects were on an average of 3.4±0.5 antihypertensive medications with a mean office BP of 145.8±10.8/83.9±11.2 mm Hg. Mean urinary sodium excretion was 46.1±26.8 vs. 252.2±64.6 mmol/24-hr during low- vs. high-salt intake. Low- compared to high-salt diet decreased office systolic and diastolic blood pressure by 22.7 and 9.1 mm Hg, respectively. Plasma renin activity increased while brain natriuretic peptide and creatinine clearance decreased during low-salt intake, indicative of intravascular volume reduction. These results indicate that excessive dietary sodium ingestion contributes importantly to resistance to antihypertensive treatment. Strategies to substantially reduce dietary salt intake should be part of the overall treatment of resistant hypertension. PMID:19620517

  4. Resetting of 24-h sodium and water balance during 4 days of servo-controlled reduction of renal perfusion pressure.

    PubMed

    Reinhardt, H W; Corea, M; Boemke, W; Pettker, R; Rothermund, L; Scholz, A; Schwietzer, G; Persson, P B

    1994-02-01

    This study examines whether an increase in renal perfusion pressure (RPP) is necessary to escape endogenously stimulated Na- and water-retaining mechanisms. In seven dogs stimulation was accomplished by a servo-controlled reduction of RPP (rRPP) below the threshold for pressure-dependent renin release for 4 days. Oral intake was standardized. Plasma renin activity (PRA) rose from 2.5 in controls to approximately 5 ng ANG I.ml-1 x h-1 during rRPP days. Plasma aldosterone concentration (PAC) increased by approximately 50% only on day 1 of rRPP but fell at or below control levels thereafter. The PAC-to-PRA ratio decreased during rRPP days. Atrial natriuretic factor (ANF) rose to values three times higher than in controls. Mean systemic blood pressure (MABP) rose from 111 +/- 12 in controls to 142 +/- 14 mmHg on day 4 of rRPP. On day 1 of rRPP 60% of the Na and 24% of the water intake were retained. However, after 2-3 days the input-output balance was restored but on a higher level of total body Na and total body water (new "set point"). Because elevated systemic MABP could not exert direct pressure effects on the kidneys due to servo control of rRPP, there must be other factors, e.g., fall in PAC, increase in ANF, and changes in intrarenal hemodynamics and physical factors that may have contributed to the resetting of input-output balances during rRPP.

  5. Effects of dietary sodium reduction on blood pressure in subjects with resistant hypertension: results from a randomized trial.

    PubMed

    Pimenta, Eduardo; Gaddam, Krishna K; Oparil, Suzanne; Aban, Inmaculada; Husain, Saima; Dell'Italia, Louis J; Calhoun, David A

    2009-09-01

    Observational studies indicate a significant relation between dietary sodium and level of blood pressure. However, the role of salt sensitivity in the development of resistant hypertension is unknown. The present study examined the effects of dietary salt restriction on office and 24-hour ambulatory blood pressure in subjects with resistant hypertension. Twelve subjects with resistant hypertension entered into a randomized crossover evaluation of low (50 mmol/24 hours x 7 days) and high sodium diets (250 mmol/24 hours x 7 days) separated by a 2-week washout period. Brain natriuretic peptide; plasma renin activity; 24-hour urinary aldosterone, sodium, and potassium; 24-hour ambulatory blood pressure monitoring; aortic pulse wave velocity; and augmentation index were compared between dietary treatment periods. At baseline, subjects were on an average of 3.4+/-0.5 antihypertensive medications with a mean office BP of 145.8+/-10.8/83.9+/-11.2 mm Hg. Mean urinary sodium excretion was 46.1+/-26.8 versus 252.2+/-64.6 mmol/24 hours during low- versus high-salt intake. Low- compared to high-salt diet decreased office systolic and diastolic blood pressure by 22.7 and 9.1 mm Hg, respectively. Plasma renin activity increased whereas brain natriuretic peptide and creatinine clearance decreased during low-salt intake, indicative of intravascular volume reduction. These results indicate that excessive dietary sodium ingestion contributes importantly to resistance to antihypertensive treatment. Strategies to substantially reduce dietary salt intake should be part of the overall treatment of resistant hypertension.

  6. Blood pressure control and the reduction of left atrial overload is essential for controlling atrial fibrillation.

    PubMed

    Tanabe, Yasuko; Kawamura, Yuichiro; Sakamoto, Naka; Sato, Nobuyuki; Kikuchi, Kenjiro; Hasebe, Naoyuki

    2009-07-01

    The purpose of this study was to investigate whether the ideal control of atrial fibrillation (AF) associated with hypertensive patients depends on the usage of renin-angiotensin system (RAS) inhibitors or whether it occurs regardless of the kind of antihypertensive agents used. The control of AF was compared in 112 outpatients between 1) those with or without the administration of RAS inhibitors, and 2) those with an ideal or poor control of the blood pressure (BP) regardless of the kind of antihypertensive therapy used. The therapies with or without RAS inhibitors did not yield any significant difference in the AF control states, even though RAS inhibitors had been administered to the patient group with a high proportion of organic heart disease. The ideal BP control group exhibited a significantly better AF control in comparison to the poor BP control group. The former group had a significantly smaller left atrial diameter determined by ultrasonic echocardiography. BP control itself may essentially be important for preventing AF in the general patient population. Poor BP control seemed to have an affect on worsening AF possibly via left ventricular diastolic dysfunction, followed by left atrial overload.

  7. Reservoir microseismicity at the Ekofisk Oil Field

    SciTech Connect

    Rutledge, J.T.; Fairbanks, T.D.; Albright, J.N.; Boade, R.R.; Dangerfield, J.; Landa, G.H.

    1994-07-01

    A triaxial, downhole geophone was deployed within the Ekofisk oil reservoir for monitoring ambient microseismicity as a test to determine if microearthquake signals generated from discrete shear failure of the reservoir rock could be detected. The results of the test were positive. During 104 hours of monitoring, 572 discrete events were recorded which have been identified as shear-failure microearthquakes. Reservoir microseismicity was detected at large distances (1000 m) from the monitor borehole and at rates (> 5 events per hour) which may allow practical characterization of the reservoir rock and overburden deformation induced by reservoir pressure changes.

  8. Coarsened Exact Matching of Phaco-Trabectome to Trabectome in Phakic Patients: Lack of Additional Pressure Reduction from Phacoemulsification

    PubMed Central

    Parikh, Hardik A.; Bussel, Igor I.; Schuman, Joel S.; Brown, Eric N.; Loewen, Nils A.

    2016-01-01

    Purpose To compare intraocular pressure (IOP) after trabectome-mediated ab interno trabeculectomy surgery in phakic patients (T) and trabectome with same session phacoemulsification (PT) using Coarsened Exact Matching. Although phacoemulsification is associated with IOP reduction when performed on its own, it is not known how much it contributes in PT. Methods Subjects were divided into phakic T and PT. Exclusion criteria were follow-up for <12 months and additional glaucoma surgery. Demographics were compared by the Mann-Whitney U test and chi-squared test for continuous and categorical variables, respectively. Multiple imputation was utilized to avoid eliminating data with missing values. Groups were then matched using Coarsened Exact Matching based on age, race, type of glaucoma, baseline IOP, and number of preoperative glaucoma medications. Univariate linear regression was used to examine IOP reduction after surgery; those variables that were statistically significant were included in the final multivariate regression model. Results A total of 753 cases were included (T: 255, PT: 498). When all variables except for age were kept constant, there was an additional IOP reduction of 0.05±0.01 mmHg conferred for every yearly increment in age. Every 1 mmHg increase in baseline IOP correlated to an additional IOP reduction of 0.80±0.02 mmHg. Phacoemulsification was not found to be a statistically significant contributor to IOP when comparing T and PT (p≥0.05). T had a 21% IOP reduction to 15.9±3.5 mmHg (p<0.01) while PT had an 18% reduction to 15.5±3.6 mmHg (p<0.01). Number of medications decreased (p<0.01) in both groups from 2.4±1.2 to 1.9±1.3 and from 2.3±1.1 to 1.7±1.3, respectively. Conclusion Phacoemulsification does not make a significant contribution to postoperative IOP or number of medications when combined with trabectome surgery in phakic patients. PMID:26895293

  9. Intensive Blood Pressure Reduction and Spot Sign in Intracerebral Hemorrhage: A Secondary Analysis of a Randomized Clinical Trial.

    PubMed

    Morotti, Andrea; Brouwers, H Bart; Romero, Javier M; Jessel, Michael J; Vashkevich, Anastasia; Schwab, Kristin; Afzal, Mohammad Rauf; Cassarly, Christy; Greenberg, Steven M; Martin, Renee Hebert; Qureshi, Adnan I; Rosand, Jonathan; Goldstein, Joshua N

    2017-08-01

    The computed tomographic angiography (CTA) spot sign is associated with intracerebral hemorrhage (ICH) expansion and may mark those patients most likely to benefit from intensive blood pressure (BP) reduction. To investigate whether the spot sign is associated with ICH expansion across a wide range of centers and whether intensive BP reduction decreases hematoma expansion and improves outcome in patients with ICH and a spot sign. SCORE-IT (Spot Sign Score in Restricting ICH Growth) is a preplanned prospective observational study nested in the Antihypertensive Treatment of Acute Cerebral Hemorrhage II (ATACH-II) randomized clinical trial. Participants included consecutive patients with primary ICH who underwent a CTA within 8 hours from onset at 59 sites from May 15, 2011, through December 19, 2015. Data were analyzed for the present study from July 1 to August 31, 2016. Patients in ATACH-II were randomized to intensive (systolic BP target, <140 mm Hg) vs standard (systolic BP target, <180 mm Hg) BP reduction within 4.5 hours from onset. Expansion of ICH was defined as hematoma growth of greater than 33%, and an unfavorable outcome was defined as a 90-day modified Rankin Scale score of 4 or greater (range, 0-6). The association among BP reduction, ICH expansion, and outcome was investigated with multivariable logistic regression. A total of 133 patients (83 men [62.4%] and 50 women [37.6%]; mean [SD] age, 61.9 [13.1] years) were included. Of these, 53 (39.8%) had a spot sign, and 24 of 123 without missing data (19.5%) experienced ICH expansion. The spot sign was associated with expansion with sensitivity of 0.54 (95% CI, 0.34-0.74) and specificity of 0.63 (95% CI, 0.53-0.72). After adjustment for potential confounders, intensive BP treatment was not associated with a significant reduction of ICH expansion (relative risk, 0.83; 95% CI, 0.27-2.51; P = .74) or improved outcome (relative risk of 90-day modified Rankin Scale score ≥4, 1.24; 95% CI, 0.53-2.91; P

  10. Feasibility of aqueous shunts for reduction of intraocular pressure in horses.

    PubMed

    Townsend, W M; Langohr, I M; Mouney, M C; Moore, G E

    2014-03-01

    Based on the current literature, neither medical, surgical nor combination therapy adequately controls equine glaucoma for many horses. Aqueous shunts have been useful in other species to control glaucoma. To determine whether aqueous shunts in normal equine eyes significantly reduce intraocular pressure (IOP) without causing vision threatening complications. Prospective experimental trial. Aqueous shunts were placed in 7 normal eyes of 4 horses. The shunts were placed dorsotemporally. Examinations were initially performed daily for 7 days and after that every 3 days through 4 weeks after implantation. Horses were then subjected to euthanasia and globes enucleated for routine histological examination. The IOPs for each day post operatively were compared to the preoperative value (Day -1) using a Wilcoxon signed ranks test. Significance was set at P<0.05. The mean IOP preoperatively (20.7 ± 3.0 mmHg) was significantly higher than on any post operative day (P values ranged from 0.018 to 0.048). The aqueous shunts remained in situ for the entire study. Two eyes developed corneal ulcers that resolved. Shallow anterior chambers were noted in 2 eyes after shunt placement, which normalised after placement of full eye cup masks. Histologically, 7/7 eyes had fibrosis surrounding the implant. Minimal peripheral neovascularisation and neutrophilic keratitis were noted in 5/7 eyes. Corneal damage was scored as none in 3/7, mild in 2/7, moderate in 1/7 and marked in 1/7 eyes. After placement of aqueous shunts, a significant decrease in IOP was noted from preoperatively (Day -1) to Day 28 despite fibrosis surrounding the implants. No vision threatening complications were noted. Aqueous shunts may represent a feasible therapeutic option for equine glaucoma. The results of this study suggest that further studies in glaucomatous horses would be warranted. © 2013 EVJ Ltd.

  11. Weight loss and blood pressure reduction in obese subjects in response to nutritional guidance using information communication technology.

    PubMed

    Ueki, Kanako; Sakurai, Nozomi; Tochikubo, Osamu

    2009-05-01

    The metabolic syndrome caused by visceral-fat obesity is a major risk factor for atherosclerosis. This study used a new information communication technology (ICT) to investigate body weight (BW) and blood pressure (BP) changes in response to nutritional guidance. Obese subjects with hypertension, hyperlipidemia, or impaired glucose tolerance received guidance with the ICT method (n = 13) or face-to-face according to conventional methods (n = 39). The effects of the methods were compared. After 12 weeks, significant weight loss and BP reduction were observed in the ICT group. Also, significant higher improvements were observed in total cholesterol (TC), low-density lipoprotein (LDL) cholesterol, and HbA(1c) in the ICT-group compared with those groups using the conventional method. The effectiveness of the ICT method in reducing BW, BP, total and LDL cholesterol, and HbA(1c) was demonstrated.

  12. Reservoir depletion at The Geysers geothermal area, California, shown by four-dimensional seismic tomography

    USGS Publications Warehouse

    Gunasekera, R.C.; Foulger, G.R.; Julian, B.R.

    2003-01-01

    Intensive geothermal exploitation at The Geysers geothermal area, California, induces myriads of small-magnitude earthquakes that are monitored by a dense, permanent, local seismometer network. Using this network, tomographic inversions were performed for the three-dimensional Vp and Vp/Vs structure of the reservoir for April 1991, February 1993, December 1994, October 1996, and August 1998. The extensive low-Vp/Vs anomaly that occupies the reservoir grew in strength from a maximum of 9% to a maximum of 13.4% during the 7-year study period. This is attributed to depletion of pore liquid water in the reservoir and replacement with steam. This decreases Vp by increasing compressibility, and increases Vs because of reduction in pore pressure and the drying of argillaceous minerals, e.g., illite, which increase the shear modulus. These effects serendipitously combine to lower Vp/Vs, resulting in a strong overall effect that provides a convenient tool for monitoring reservoir depletion. Variations in the Vp and Vs fields indicate that water depletion is the dominant process in the central part of the exploited reservoir, and pressure reduction and mineral drying in the northwest and southeast parts of the reservoir. The rate at which the Vp/Vs anomaly grew in strength in the period 1991-1998 suggests most of the original anomaly was caused by exploitation. Continuous monitoring of Vp, Vs, and Vp/Vs is an effective geothermal reservoir depletion monitoring tool and can potentially provide information about depletion in parts of the reservoir that have not been drilled.

  13. Rapid reduction of serum cholesterol and blood pressure by a twelve-day, very low fat, strictly vegetarian diet.

    PubMed

    McDougall, J; Litzau, K; Haver, E; Saunders, V; Spiller, G A

    1995-10-01

    This study was conducted to demonstrate the effectiveness of a strictly vegetarian, very low-fat diet on cardiac risk factor modification. Five hundred men and women, participants in an intensive 12-day live-in program, were studied. The program focused on dietary modification, moderate exercise, and stress management at a hospital-based health-center. During this short time period, cardiac risk factors improved: there was an average reduction of total serum cholesterol of 11% (p < 0.001), of blood pressure of 6% (p < 0.001) and a weight loss of 2.5 kg for men and 1 kg for women. Serum triglycerides did not increase except for two subgroups: females age > or = 65 years with serum cholesterol < 6.5 mmol/L and for females 50 to 64 years with baseline serum cholesterol between 5.2-6.5 mmol/L. High-density lipoprotein cholesterol measured on 66 subjects decreased by 19%. A strict, very low-fat vegetarian diet free from all animal products combined with lifestyle changes that include exercise and weight loss is an effective way to lower serum cholesterol and blood pressure.

  14. Aquatic exercise is as effective as dry land training to blood pressure reduction in postmenopausal hypertensive women.

    PubMed

    Arca, Eduardo Aguilar; Martinelli, Bruno; Martin, Luis Cuadrado; Waisberg, César Becalel; Franco, Roberto Jorge da Silva

    2014-06-01

    The evidence of the benefits from regular physical activity to hypertensives is based on dry land training studies. Therefore, the aim of this study is to compare the effect of aquatic exercise with dry land training on hypertensive women. This is a randomized controlled study with 52 post-menopausal hypertensive women. The patients were randomly allocated in three groups: water aerobic training group (n = 19), dry land aerobic training group (n = 19) and a non-intervention control group (n = 14). The training protocol was performed by 12 weeks. There were no differences among the three groups concerning basal blood pressure (BP) and biochemical variables. In water group, there was a statistically significant reduction of systolic BP from 136 ± 16 mm Hg at zero week to 124 ± 18 mm Hg at 11th week and 124 ± 15 mm Hg at 12th week. In dry land training group, there was a statistically significant reduction of systolic BP from 138 ± 15 mm Hg at zero week to 125 ± 10 mm Hg at 7th week, 127 ± 10 mm Hg at 10th week and 126 ± 9 mm Hg at 12th week. The control group presented no change in any of the assessed variables. No changes were carried out in any antihypertensive medications during study. This is a randomized controlled study that demonstrates the antihypertensive efficacy of aerobic aquatic exercise. © 2013 John Wiley & Sons, Ltd.

  15. Feasibility study of sustained-release travoprost punctum plug for intraocular pressure reduction in an Asian population

    PubMed Central

    Perera, Shamira A; Ting, Daniel SW; Nongpiur, Monisha E; Chew, Paul T; Aquino, Maria Cecilia D; Sng, Chelvin CA; Ho, Sue-Wei; Aung, Tin

    2016-01-01

    Purpose To investigate the efficacy and safety of a punctum plug-based sustained drug release system for a prostaglandin analog, travoprost (OTX-TP), for intraocular pressure (IOP) reduction in an Asian population. Methods This is an initial feasibility, prospective, single-arm study involving 26 eyes and a bioresorbable punctum plug containing OTX-TP. An OTX-TP was placed in the vertical portion of the superior or inferior canaliculus of patients with primary open-angle glaucoma or ocular hypertension. The main outcome measure was the IOP-lowering efficacy of OTX-TP at 3 (8 am) and 10, 20, and 30 days (8 am, 10 am, and 4 pm), compared to baseline. Results A total of 26 OTX-TP were inserted for 17 subjects. The mean (standard deviation) age was 57.2 (13.8) years. At 10 days, all plugs were still present, and the IOP reduction from baseline was 6.2 (23%), 5.4 (21%), and 7.5 mmHg (28%) at 8 am, 10 am, and 4 pm, respectively. At 10 days, the mean IOP (standard error of mean) was 21.2 (1.2), 20.4 (0.8), and 19.7 (1.0) at 8 am, 10 am, and 4 pm, respectively, showing no discernible IOP trend during the course of the day. At 30 days, plug retention had declined to 42%, and the overall IOP reduction had decreased to 16%. Conclusion The sustained-release OTX-TP is able to reduce IOP by 24% (day 10) and 15.6% (day 30), respectively. It is a potentially well-tolerable ocular hypotensive for glaucoma patients with a history of poor compliance. PMID:27175058

  16. [Expiratory pressure reduction (C-Flex Method) versus fix CPAP in the therapy for obstructive sleep apnoea].

    PubMed

    Wenzel, M; Kerl, J; Dellweg, D; Barchfeld, T; Wenzel, G; Köhler, D

    2007-11-01

    The REM star C-Flex (Fa. Respironics) was introduced in 2003. In contrast to the conventionel fix CPAP mode, the C-Flex mode is characterised by a pressure reduction at the beginning of expiration. In a randomised cross-over design, we investigated if this C-Flex-mode has advantages compared to the fix CPAP mode in terms of treatment quality and patient satisfaction. In this prospective randomised single-blinded cross-over study we investigated 20 patients with obstructive sleep apnoea treated with fix CPAP versus treatment with the C-Flex mode (level 2) for 6 weeks, respectively. We compared the polysomnographically measured quality of treatment and the subjective satisfaction of either form of therapy. Additionally, we measured long-term compliance of the C-Flex therapy in a 3-year follow-up with the integrated counter of the C-Flex devices. The mean levels of pressure of the fix CPAP and the C-Flex therapies were 8.4 +/- 2.9 mbar in both groups. There was an identical quality of treatment in terms of respiratory events, arousal index, slow wave sleep and Epworth sleepiness scale. The compliance of nocturnal use of the C-Flex and the fix CPAP was identical (6.0 +/- 0.67 C-Flex use vs. 5.8 +/- 0.98 CPAP use [h/night]). The subjective satisfaction was higher in the C-Flex mode at the end of the study since 18 of 20 patients (90%) subjectively prefered the C-Flex mode because of the easier expiration. 19 patients received a C-Flex device for long-term therapy. The 3-year-follow-up showed a regular utilisation of the C-Flex by 16 of 19 (84.2%) of these patients (mean nocturnal use 6.0 +/- 0.9 h/night). 3 of the 19 patients (15.8%) did not use their C-Flex regulary. None of the patients has terminated therapy completely. C-Flex mode and the conventional fix CPAP therapies show an equivalent treatment quality according to polysomnographic data. The expiratory pressure reduction compared to conventional CPAP was felt to be more comfortable by 90% of patients. The long

  17. Application of low pressure capacitively coupled rf hydrogen plasma for low temperature reduction of iron clusters in structure of fe-pillared materials

    NASA Astrophysics Data System (ADS)

    Starshinova, V. L.; Gorelysheva, V. E.; Shinka Jr., A. A., rev; Gnevashev, S. G.; Kulevtsov, G. N.; Shinkarev, A. A.

    2017-01-01

    The unique properties of pillared materials determine their use in catalysis, purification and separation. The paper studies the reduction of composite catalysts, Fe-pillared materials. The authors compare their reduction in low temperature capacitively coupled RF hydrogen discharge of low pressure to their conventional direct hydrogen reduction in a tubular muffle furnace. X-ray diffraction analysis was used to characterize the iron-bearing phases. The results show that the reduction of iron hydro/oxide clusters associated with an aluminosilicate matrix to metallic iron is very challenging due to the degree of the pore space availability for hydrogen.

  18. Reduction in blood pressure and serum lipids by lycosome formulation of dark chocolate and lycopene in prehypertension.

    PubMed

    Petyaev, Ivan M; Dovgalevsky, Pavel Y; Chalyk, Natalia E; Klochkov, Victor; Kyle, Nigel H

    2014-11-01

    Twenty-nine healthy volunteers aged 47-69 years old were randomly assigned to a 28-day oral intake of different dark chocolate (DC) formulations. The main group received daily 30 g of proprietary lycopene-containing (L-tug) lycosome formulation of DC with enhanced bioavailability of cocoa flavanols. Two control groups daily consumed either 30 g of regular DC alone or along with 7 mg of lycopene, which corresponds to the amount of lycopene ingested with L-tug formulation. It was found that L-tug was more efficient in reducing diastolic blood pressure (mean value of -6.22 mmHg, 95% CI: 5.00, 8.00) when compared with the regular DC group (-3.00 mmHg, P < 0.05) or the group which ingested the DC and lycopene as two separate formulations (mean reduction of -4 mmHg, 95% CI: 2.47, 6.00, P = 0.0262). Only marginal superiority for L-tug formulation in the reduction in systolic blood pressure was seen. However, the L-tug formulation was the only formulation of DC which affected serum lipids. There was a reduction in total cholesterol (from median 228.00 mg/dL [95% CI: 206.2, 242.5] to 187.00 mg/dL [95% CI: 166.2, 202.2, P < 0.05]) with corresponding decline of low-density lipoprotein (LDL) cholesterol (from a median of 166.00 mg/dL [95% CI: 130.8, 177.0] to 151.00 mg/dL [95% CI: 122.8, 167.4; P < 0.05]) at the end of the intervention period. Similar decline was seen in serum triglycerides (P < 0.05). Serum high-density lipoprotein (HDL) cholesterol, glucose levels, and C-reactive protein (CRP) values remained statistically unchanged in all study groups throughout the intervention period. A superior biological activity of the L-tug lycosome formulation of DC extending beyond its antihypertensive effect to lipid-lowering ability opens up new possibilities for the use of DC for health purposes helping to reduce daily caloric intake without compromising on the health benefits of DC consumption.

  19. Reduction in blood pressure and serum lipids by lycosome formulation of dark chocolate and lycopene in prehypertension

    PubMed Central

    Petyaev, Ivan M; Dovgalevsky, Pavel Y; Chalyk, Natalia E; Klochkov, Victor; Kyle, Nigel H

    2014-01-01

    Twenty-nine healthy volunteers aged 47–69 years old were randomly assigned to a 28-day oral intake of different dark chocolate (DC) formulations. The main group received daily 30 g of proprietary lycopene-containing (L-tug) lycosome formulation of DC with enhanced bioavailability of cocoa flavanols. Two control groups daily consumed either 30 g of regular DC alone or along with 7 mg of lycopene, which corresponds to the amount of lycopene ingested with L-tug formulation. It was found that L-tug was more efficient in reducing diastolic blood pressure (mean value of −6.22 mmHg, 95% CI: 5.00, 8.00) when compared with the regular DC group (−3.00 mmHg, P < 0.05) or the group which ingested the DC and lycopene as two separate formulations (mean reduction of −4 mmHg, 95% CI: 2.47, 6.00, P = 0.0262). Only marginal superiority for L-tug formulation in the reduction in systolic blood pressure was seen. However, the L-tug formulation was the only formulation of DC which affected serum lipids. There was a reduction in total cholesterol (from median 228.00 mg/dL [95% CI: 206.2, 242.5] to 187.00 mg/dL [95% CI: 166.2, 202.2, P < 0.05]) with corresponding decline of low-density lipoprotein (LDL) cholesterol (from a median of 166.00 mg/dL [95% CI: 130.8, 177.0] to 151.00 mg/dL [95% CI: 122.8, 167.4; P < 0.05]) at the end of the intervention period. Similar decline was seen in serum triglycerides (P < 0.05). Serum high-density lipoprotein (HDL) cholesterol, glucose levels, and C-reactive protein (CRP) values remained statistically unchanged in all study groups throughout the intervention period. A superior biological activity of the L-tug lycosome formulation of DC extending beyond its antihypertensive effect to lipid-lowering ability opens up new possibilities for the use of DC for health purposes helping to reduce daily caloric intake without compromising on the health benefits of DC consumption. PMID:25493193

  20. Daily potassium intake and sodium-to-potassium ratio in the reduction of blood pressure: a meta-analysis of randomized controlled trials.

    PubMed

    Binia, Aristea; Jaeger, Jonathan; Hu, Youyou; Singh, Anurag; Zimmermann, Diane

    2015-08-01

    To evaluate the efficacy of daily potassium intake on decreasing blood pressure in non-medicated normotensive or hypertensive patients, and to determine the relationship between potassium intake, sodium-to-potassium ratio and reduction in blood pressure. Mixed-effect meta-analyses and meta-regression models. Medline and the references of previous meta-analyses. Randomized controlled trials with potassium supplementation, with blood pressure as the primary outcome, in non-medicated patients. Fifteen randomized controlled trials of potassium supplementation in patients without antihypertensive medication were selected for the meta-analyses (917 patients). Potassium supplementation resulted in reduction of SBP by 4.7 mmHg [95% confidence interval (CI) 2.4-7.0] and DBP by 3.5 mmHg (95% CI 1.3-5.7) in all patients. The effect was found to be greater in hypertensive patients, with a reduction of SBP by 6.8 mmHg (95% CI 4.3-9.3) and DBP by 4.6 mmHg (95% CI 1.8-7.5). Meta-regression analysis showed that both increased daily potassium excretion and decreased sodium-to-potassium ratio were associated with blood pressure reduction (P < 0.05). Increased total daily potassium urinary excretion from 60 to 100 mmol/day and decrease of sodium-to-potassium ratio were shown to be necessary to explain the estimated effect. Potassium supplementation is associated with reduction of blood pressure in patients who are not on antihypertensive medication, and the effect is significant in hypertensive patients. The reduction in blood pressure significantly correlates with decreased daily urinary sodium-to-potassium ratio and increased urinary potassium. Patients with elevated blood pressure may benefit from increased potassium intake along with controlled or decreased sodium intake.

  1. An experimental study of relative permeability hysteresis, capillary trapping characteristics, and capillary pressure of CO2/brine systems at reservoir conditions

    NASA Astrophysics Data System (ADS)

    Austin Suthanthiraraj, Pearlson Prashanth

    We present the results of an extensive experimental study on the effects of hysteresis on permanent capillary trapping and relative permeability of CO2/brine and supercritical (sc)CO2+SO2/brine systems. We performed numerous unsteady- and steady-state drainage and imbibition full-recirculation flow experiments in three different sandstone rock samples, i.e., low and high-permeability Berea, Nugget sandstones, and Madison limestone carbonate rock sample. A state-of-the-art reservoir conditions core-flooding system was used to perform the tests. The core-flooding apparatus included a medical CT scanner to measure in-situ saturations. The scanner was rotated to the horizontal orientation allowing flow tests through vertically-placed core samples with about 3.8 cm diameter and 15 cm length. Both scCO2 /brine and gaseous CO2 (gCO2)/brine fluid systems were studied. The gaseous and supercritical CO2/brine experiments were carried out at 3.46 and 11 MPa back pressures and 20 and 55°C temperatures, respectively. Under the above-mentioned conditions, the gCO2 and scCO2 have 0.081 and 0.393 gr/cm3 densities, respectively. During unsteady-state tests, the samples were first saturated with brine and then flooded with CO2 (drainage) at different maximum flow rates. The drainage process was then followed by a low flow rate (0.375 cm 3/min) imbibition until residual CO2 saturation was achieved. Wide flow rate ranges of 0.25 to 20 cm3/min for scCO2 and 0.125 to 120 cm3min for gCO2 were used to investigate the variation of initial brine saturation (Swi) with maximum CO2 flow rate and variation of trapped CO2 saturation (SCO2r) with Swi. For a given Swi, the trapped scCO2 saturation was less than that of gCO2 in the same sample. This was attributed to brine being less wetting in the presence of scCO2 than in the presence of gCO 2. During the steady-state experiments, after providing of fully-brine saturated core, scCO2 was injected along with brine to find the drainage curve and as

  2. Individual susceptibility to hypoperfusion and reductions in exercise performance when perfusion pressure is reduced: evidence for vasodilator phenotypes

    PubMed Central

    Bentley, Robert F.; Kellawan, J. Mikhail; Moynes, Jackie S.; Poitras, Veronica J.; Walsh, Jeremy J.

    2014-01-01

    The primary objective of this study was to determine whether cardiovascular compensatory response phenotypes exist in the face of a reduced perfusion pressure challenge to exercising muscle oxygen delivery (O2D), and whether these responses might be exercise intensity (EI) dependent. Ten healthy men (19.5 ± 0.4 yr) completed two trials of progressive forearm isometric handgrip exercise to exhaustion (24.5 N increments every 3.5 min) in each of forearm above and below heart level [forearm arterial perfusion pressure (FAPP) difference of 29.5 ± 0.97 mmHg]. At the end of each EI, measurements of forearm blood flow (FBF; ml/min) via brachial artery Doppler and echo ultrasound, mean arterial blood pressure (MAP; mmHg) via finger photoplethysmography, and exercising forearm venous effluent via antecubital vein catheter revealed distinct cardiovascular response groups: n = 6 with compensatory vasodilation vs. n = 4 without compensatory vasodilation. Compensatory vasodilators were able to blunt the perfusion pressure-evoked reduction in submaximal O2D in the arm-above-heart condition, whereas nonvasodilators did not (−22.5 ± 13.6 vs. −65.4 ± 14.1 ml O2/min; P < 0.05), and in combination with being able to increase O2 extraction, nonvasodilators defended submaximal V̇o2 and experienced less of an accumulated submaximal O2D deficit (−80.7 ± 24.7 vs. −219.1 ± 36.0 ml O2/min; P < 0.05). As a result, the compensatory vasodilators experienced less of a compromise to peak EI than nonvasodilators (−24.5 ± 3.5 N vs. −52.1 ± 8.9 N; P < 0.05). In conclusion, in the forearm exercise model studied, vasodilatory response phenotypes exist that determine individual susceptibility to hypoperfusion and the degree to which aerobic metabolism and exercise performance are compromised. PMID:24970851

  3. Individual susceptibility to hypoperfusion and reductions in exercise performance when perfusion pressure is reduced: evidence for vasodilator phenotypes.

    PubMed

    Bentley, Robert F; Kellawan, J Mikhail; Moynes, Jackie S; Poitras, Veronica J; Walsh, Jeremy J; Tschakovsky, Michael E

    2014-08-15

    The primary objective of this study was to determine whether cardiovascular compensatory response phenotypes exist in the face of a reduced perfusion pressure challenge to exercising muscle oxygen delivery (O2D), and whether these responses might be exercise intensity (EI) dependent. Ten healthy men (19.5 ± 0.4 yr) completed two trials of progressive forearm isometric handgrip exercise to exhaustion (24.5 N increments every 3.5 min) in each of forearm above and below heart level [forearm arterial perfusion pressure (FAPP) difference of 29.5 ± 0.97 mmHg]. At the end of each EI, measurements of forearm blood flow (FBF; ml/min) via brachial artery Doppler and echo ultrasound, mean arterial blood pressure (MAP; mmHg) via finger photoplethysmography, and exercising forearm venous effluent via antecubital vein catheter revealed distinct cardiovascular response groups: n = 6 with compensatory vasodilation vs. n = 4 without compensatory vasodilation. Compensatory vasodilators were able to blunt the perfusion pressure-evoked reduction in submaximal O2D in the arm-above-heart condition, whereas nonvasodilators did not (-22.5 ± 13.6 vs. -65.4 ± 14.1 ml O2/min; P < 0.05), and in combination with being able to increase O2 extraction, nonvasodilators defended submaximal V̇o2 and experienced less of an accumulated submaximal O2D deficit (-80.7 ± 24.7 vs. -219.1 ± 36.0 ml O2/min; P < 0.05). As a result, the compensatory vasodilators experienced less of a compromise to peak EI than nonvasodilators (-24.5 ± 3.5 N vs. -52.1 ± 8.9 N; P < 0.05). In conclusion, in the forearm exercise model studied, vasodilatory response phenotypes exist that determine individual susceptibility to hypoperfusion and the degree to which aerobic metabolism and exercise performance are compromised. Copyright © 2014 the American Physiological Society.

  4. TRITIUM RESERVOIR STRUCTURAL PERFORMANCE PREDICTION

    SciTech Connect

    Lam, P.S.; Morgan, M.J

    2005-11-10

    The burst test is used to assess the material performance of tritium reservoirs in the surveillance program in which reservoirs have been in service for extended periods of time. A materials system model and finite element procedure were developed under a Savannah River Site Plant-Directed Research and Development (PDRD) program to predict the structural response under a full range of loading and aged material conditions of the reservoir. The results show that the predicted burst pressure and volume ductility are in good agreement with the actual burst test results for the unexposed units. The material tensile properties used in the calculations were obtained from a curved tensile specimen harvested from a companion reservoir by Electric Discharge Machining (EDM). In the absence of exposed and aged material tensile data, literature data were used for demonstrating the methodology in terms of the helium-3 concentration in the metal and the depth of penetration in the reservoir sidewall. It can be shown that the volume ductility decreases significantly with the presence of tritium and its decay product, helium-3, in the metal, as was observed in the laboratory-controlled burst tests. The model and analytical procedure provides a predictive tool for reservoir structural integrity under aging conditions. It is recommended that benchmark tests and analysis for aged materials be performed. The methodology can be augmented to predict performance for reservoir with flaws.

  5. INVESTIGATION OF EFFICIENCY IMPROVEMENTS DURING CO2 INJECTION IN HYDRAULICALLY AND NATURALLY FRACTURED RESERVOIRS

    SciTech Connect

    David S. Schechter

    2002-04-01

    For many years many efforts have been performed in the laboratory experiments to duplicate the reservoir conditions. In this study, we will investigate the permeability change at different overburden conditions. The reduction in permeability with overburden pressure has been well known. Fatt and Davis (1952) presented the changes in permeability with pressure at range 0 to 15,000 psig and found that overburden pressure caused a reduction in permeability of the consolidated oil-bearing sandstone samples by as much as 50% at 10,000 psig. Wyble (1958) performed similar experiments on three different sandstone samples to determine the changes in conductivity, porosity and permeability at pressure range 0 to 5,000 psig. His results were consistent with the observation by Fatt and Davis (1952). During the experiments, different overburden pressures (radial force) were applied only to the cylinder core while the axial direction was kept at constant atmospheric pressure. Gray et al. (1963) enhanced the previous experiments by applying axial force and combining with overburden pressure (radial force) to measure the anisotropy permeability changes at more representative reservoir stress-state condition. They showed that permeability reduction subjected to overburden pressure as a function of the ratio of radial to axial stress and the permeability reduction under non-uniform stress (radial pressure {ne} axial pressure) is less than that under uniform stress. Although extensive work has been established on the effect of overburden pressure and stress-state on matrix permeability but there are some very interesting details of fractured rock behavior under stress that have not been investigated. In this study we will show the effect of fracture aperture and fracture permeability on the fluid flow under different overburden pressure. This study is a precursor to investigating fracture apertures under different stress-state conditions (confining stress, hydrostatic stress and

  6. Major element composition of an Early Enriched Reservoir: constraints from 142Nd/144Nd isotope systematics in the early Earth and high-pressure melting experiments of a primitive peridotite

    NASA Astrophysics Data System (ADS)

    Kondo, Nozomi; Yoshino, Takashi; Matsukage, Kyoko N.; Kogiso, Tetsu

    2016-12-01

    The Accessible Silicate Earth (ASE) has a higher 142Nd/144Nd ratio than most chondrites. Thus, if the Earth is assumed to have formed from these chondrites, a complement low-142Nd/144Nd reservoir is needed. Such a low-142Nd/144Nd reservoir is believed to have been derived from a melt in the early Earth and is called the Early Enriched Reservoir (EER). Although the major element composition of the EER is crucial for estimating its chemical and physical properties (e.g., density) and is also essential for understanding the origin and fate of the EER, which are both major factors that determine the present composition of the Earth, it has not yet been robustly established. In order to determine the major element composition of the EER, we estimated the age and pressure-temperature conditions to form the EER that would best explain its Nd isotopic characteristics, based on Sm-Nd partitioning and its dependence on pressure, temperature, and melting phase relations. Our estimate indicates that the EER formed within 33.5 Myr of Solar System formation and at near-solidus temperatures and shallow upper-mantle pressures. We then performed high-pressure melting experiments on primitive peridotite to determine the major element composition of the EER at estimated temperature at 7 GPa and calculated the density of the EER. The result of our experiments indicates that the near-solidus melt is iron-rich komatiite. The estimated density of the near-solidus melt is lower than that of the primitive peridotite, suggesting that the EER melt would have ascended in the mantle to form an early crust. Given that high mantle potential temperatures are assumed to have existed in the Hadean, it follows that the EER melt was generated at high pressure and, therefore, its composition would have been picritic to komatiitic. As the formation age of the EER estimated in our study precedes the last giant, lunar-forming impact, the picritic to komatiitic crust (EER) would most likely have been

  7. Prediction of slug-to-annular flow pattern transition (STA) for reducing the risk of gas-lift instabilities and effective gas/liquid transport from low-pressure reservoirs

    SciTech Connect

    Toma, P.R.; Vargas, E.; Kuru, E.

    2007-08-15

    Flow-pattern instabilities have frequently been observed in both conventional gas-lifting and unloading operations of water and oil in low-pressure gas and coalbed reservoirs. This paper identifies the slug-to-annular flow-pattern transition (STA) during upward gas/liquid transportation as a potential cause of flow instability in these operations. It is recommended that the slug-flow pattern be used mainly to minimize the pressure drop and gas compression work associated with gas-lifting large volumes of oil and water. Conversely, the annular flow pattern should be used during the unloading operation to produce gas with relatively small amounts of water and condensate. New and efficient artificial lifting strategies are required to transport the liquid out of the depleted gas or coalbed reservoir level to the surface. This paper presents held data and laboratory measurements supporting the hypothesis that STA significantly contributes to flow instabilities and should therefore be avoided in upward gas/liquid transportation operations. Laboratory high-speed measurements of flow-pressure components under a broad range of gas-injection rates including STA have also been included to illustrate the onset of large STA-related flow-pressure oscillations. The latter body of data provides important insights into gas deliquification mechanisms and identifies potential solutions for improved gas-lifting and unloading procedures. A comparison of laboratory data with existing STA models was performed first. Selected models were then numerically tested in field situations. Effective field strategies for avoiding STA occurrence in marginal and new (offshore) field applications (i.e.. through the use of a slug or annular flow pattern regimen from the bottomhole to wellhead levels) are discussed.

  8. Persistence of mortality reduction after the end of randomized therapy in clinical trials of blood pressure-lowering medications.

    PubMed

    Kostis, William J; Thijs, Lutgarde; Richart, Tom; Kostis, John B; Staessen, Jan A

    2010-12-01

    Long-term follow-up of clinical trials of blood pressure-lowering medications has suggested a continuation of event reduction after study completion. We evaluated the persistence of mortality benefit of these agents after the end of clinical trials, when all of the patients were advised to take the same open-label therapy. We performed a meta-analysis of randomized clinical trials using blood pressure-lowering medications, used in patients with hypertension, myocardial infarction, or left ventricular systolic dysfunction, (n=18; 132 854 patients; 11 988 deaths) when a second report describing results after the end of the trial was available. During the randomized (first) phase, 80% (interquartile range: 75% to 83%) of the patients randomized to receive active therapy actually received it compared with 16% (interquartile range: 7% to 22%) of those randomized to control. In this phase, mortality was lower in the intervention group (odds ratio: 0.84 [95% CI: 0.79 to 0.90]; P<0.0001). Mortality was also lower during the open-label follow-up (second) phase (odds ratio: 0.85 [95% CI: 0.79 to 0.91]; P<0.0001), when all of the patients were advised to take the same therapy, and rates of receiving active therapy were similar in the 2 groups (59% [interquartile range: 46% to 77%], among those originally randomized to active, and 43% [interquartile range: 20% to 68%], in the control). Several sensitivity analyses indicated stability of the effects. In studies of antihypertensive medications, a decrease in overall mortality persists after the end of trial phase, when most patients in both the intervention and control groups receive active therapy. These analyses imply that earlier intervention would result in better clinical outcomes.

  9. Sleep-time blood pressure as a therapeutic target for cardiovascular risk reduction in type 2 diabetes.

    PubMed

    Hermida, Ramón C; Ayala, Diana E; Mojón, Artemio; Fernández, José R

    2012-03-01

    Independent studies have found that elevated sleep-time blood pressure (BP) is a better predictor of cardiovascular risk than the awake or 24-h BP means in patients without as well as with diabetes. However, the impact of the alteration over time of ambulatory BP on cardiovascular risk has never been investigated. We evaluated in a subgroup cohort of MAPEC (Monitorización Ambulatoria para Predicción de Eventos Cardiovasculares, i.e., ambulatory blood pressure monitoring for prediction of cardiovascular events) with diabetes whether reduced cardiovascular risk is more related to the progressive decrease of awake vs. asleep BP. We studied 607 patients with type 2 diabetes during a median 5.4 years follow-up. Those with hypertension at baseline (74%) were randomized to ingest all their prescribed hypertension medications upon awakening or ≥1 of them at bedtime. BP was measured for 48 h at baseline, and again annually in all patients, or more frequently (quarterly) after adjustments in treatment. Using baseline data, when asleep BP was adjusted by awake mean, only the former was a significant predictor of outcome in a Cox proportional-hazard model adjusted for sex, age, anemia, and chronic kidney disease. Analyses of changes in BP during follow-up revealed a 20% cardiovascular risk reduction for each 5 mm Hg decrease in asleep systolic BP mean (P < 0.001), independently of changes in clinic or any other ambulatory BP parameter. Sleep-time BP is the most significant independent prognostic marker of cardiovascular events in diabetes. Most important, decreasing sleep-time BP, a novel therapeutic target requiring proper patient evaluation by ambulatory monitoring, was the most significant independent predictor of event-free survival in diabetes. © 2012 American Journal of Hypertension, Ltd.

  10. The pressure reduction coefficient: A new parameter to assess aneurysmal blood stasis induced by flow diverters/disruptors.

    PubMed

    Gascou, Gregory; Ferrara, Riccardo; Ambard, Dominique; Sanchez, Mathieu; Lobotesis, Kyriakos; Jourdan, Franck; Costalat, Vincent

    2017-02-01

    Background and purpose Pore density (PD), surface metal coverage (SMC) and the number of wires are all different parameters which can influence the efficacy of a flow disruptor/diverter. Nevertheless, the relative importance of a parameter to induce intra-aneurysmal blood stasis is still poorly evaluated. Therefore, comparison between devices based on a unique value is not reliable. The aim of this study was to propose a new bench top parameter (the pressure reduction coefficient (PRC; ξ)) in order to assess the global haemodynamic effect of each flow diverter/disruptor to slow flow. Methods Eight devices were tested in vitro during three different flow conditions. For the eight devices, the PRC was computed at different volumetric flow rates to characterise flow reduction. Comparison was made with SMC, PD and the number of wires. Results The PRC obtained for flow disruptors was on average 1.5 times more efficient in reducing flow compared to flow diverters. PD (mm(2)) ranged from 24 to 38 for flow diverters and did not independently correlate with the PRC. The SMC of flow diverters ranged from 25% to 70%, and ranged from 20% to 100% for flow disruptors, without independent correlation to the PRC. The number of wires ranged from 48 to 96 for the flow diverters and did not correlate independently to the PRC. Conclusion There were no direct correlations between individual device characteristics and the PRC, suggesting a multifaceted and interrelating association of the overall design of each implant. Hence, the PRC could be used as a simple, reliable parameter to assess the overall capacity of flow disruptors/diverters to induce intra-aneurysmal blood stasis.

  11. TiO2 Processed by pressurized hot solvents as a novel photocatalyst for photocatalytic reduction of carbon dioxide

    NASA Astrophysics Data System (ADS)

    Reli, Martin; Kobielusz, Marcin; Matějová, Lenka; Daniš, Stanislav; Macyk, Wojciech; Obalová, Lucie; Kuśtrowski, Piotr; Rokicińska, Anna; Kočí, Kamila

    2017-01-01

    Anatase-brookite TiO2 photocatalysts were prepared by the sol-gel process controlled within reverse micelles and processing by pressurized hot solvents-water/methanol/water (TiO2(M)) and water/ethanol/water (TiO2(E)), as an unconventional alternative to common calcination. The main goal of this work was to prepare anatase-brookite mixtures by processing by two different alcohols (methanol and ethanol) and evaluate the influence of the alcohol on the photocatalytic activity. Prepared photocatalysts were characterized by organic elemental analysis, nitrogen physisorption, XRD, UV-vis, photoelectrochemical and spectroelectrochemical measurements and XPS. The prepared photocatalysts efficiency was tested on the photocatalytic reduction of carbon dioxide and compared with commercial TiO2 Evonik P25. Both prepared nanocomposites were more efficient towards methane production but Evonik P25 was the most efficient towards hydrogen generated through water splitting. The higher performance of anatase-brookite mixture towards methane production can be explained by (i) a higher photocatalytic activity of brookite than rutile; (ii) a large surface area of anatase-brookite composites enabling better carbon dioxide adsorption; (iii) the photoinduced electron transfer from the brookite conduction band to the anatase conduction band. On the other hand, a higher production of hydrogen in the presence of Evonik P25 is caused by a better charge separation in anatase-rutile than anatase-brookite phase compositions. TiO2(M) appeared more active than TiO2(E) in the photocatalytic reduction of carbon dioxide due to a lower density of defects created in the crystal lattice.

  12. Improvement of sleep-disordered breathing in children is associated with a reduction in overnight blood pressure.

    PubMed

    Vlahandonis, Anna; Nixon, Gillian M; Davey, Margot J; Walter, Lisa M; Horne, Rosemary S C

    2013-12-01

    Childhood sleep-disordered breathing (SDB) is associated with elevated blood pressure (BP); however, little is known about the long-term outcomes in this population. We aimed to assess long-term changes in overnight BP in children with SDB. Forty children with previously diagnosed SDB and 20 nonsnoring control participants underwent repeat overnight polysomnography (PSG) with continuous BP measurement 4years after the original diagnosis. At follow-up, children aged 11-16years were categorized into 2 groups of resolved (absence of snoring and obstructive apnea-hypopnea index [OAHI]⩽1) or unresolved (continued to snore or had an OAHI >1) SDB. There were no group differences in age, sex, or body mass index (BMI) z score. OAHI was lower at follow-up (P<.05) in both the resolved (n=18) and unresolved (n=22) groups. BP was elevated during wake and sleep in both SDB groups compared to the control group at baseline (P<.01 for all), but it decreased by 5-15mmHg at follow-up during sleep for both SDB groups (P<.05 for all). BP during wake was unchanged in the SDB groups at follow-up but increased in the control group (P<.05). At follow-up, BP did not differ between the control group and the SDB groups during wake or sleep. Improved oxygen saturation (SpO2) during sleep was a significant predictor of a reduction in BP. SDB improved over the 4-year follow-up and both resolved and unresolved groups exhibited a significant reduction in BP during sleep, with levels similar to the control group. Our study highlights the fact that even small improvements can improve the cardiovascular effects of SDB. Crown Copyright © 2013. Published by Elsevier B.V. All rights reserved.

  13. Reductions in non-point source pollution through different management practices for an agricultural watershed in the Three Gorges Reservoir Area.

    PubMed

    Tian, Yaowu; Huang, Zhilin; Xiao, Wenfa

    2010-01-01

    Non-point source water pollution generated by agricultural production is considered a major environmental issue in the Three Gorges Reservoir Area (TGRA) of China. The Annualised Agricultural Non-Point Source Pollution (AnnAGNPS) model was selected to assess the impact of the application of various management treats, including seven crops, five fertilizer levels and three-group management practice scenarios, on water quality from Heigou River Watershed in TGRA. The scenario subsets include conservation tillage practice (CTP), conservation reserve program (CRP) and conversion of cropland into forestland program (CCFP). Results indicated that tea can not be replaced by other crops because comparatively tea resulted in a higher sediment yield. CTP with no-tillage was more effective to reduce sediment yield, but could increased nutrient loss. CRP reduced sediment yield significantly, but slightly benefited on nutrient loss. CCFP reduced not only sediment yield but also the nutrient loss significantly. The conversion of cropland with a slope greater than 10 degrees into forestland was found to be the best scenario as the sediment yield export is less than 5 tons/ha and nutrient loss is within the permissible limit.

  14. Comparison of hydrogen and acetate as substrates for the reductive immobilization of uranium under in-situ pressure

    NASA Astrophysics Data System (ADS)

    Heuston, Daniel Jon

    Complete baseline restoration at in-situ recovery (ISR) uranium (U) mining sites has proven difficult through conventional methods. Bioremediation by means of reductive immobilization of soluble U(VI) to insoluble U(IV) is currently being investigated as a secondary restoration method. Various organic substrates have been used in many U bioremediation studies and applications. However, the oxidation of organic substrates increases total inorganic carbon concentrations (TIC) due to the respiration of heterotrophic bacteria. It is widely accepted that U forms stable complexes with carbonate that in turn lower the thermodynamic redox potential at which the U(VI)/U(IV) couple takes place. In this study, it was hypothesized that greater U reductive immobilization would be achieved with hydrogen (H2) as an electron donor compared to that with acetate (Ac) because H2 would select for autotrophic bacteria that would decrease TIC. The hypothesis was tested by supplying H 2 and Ac at the same reductive capacity to continuous-flow sediment-columns. Unlike previous studies, the columns were operated at pressures representative of the in-situ conditions at ISR mining sites. The experimental results indicated that effluent TIC and U concentrations were both significantly lower for the H2-supplied column than for the Ac-supplied column. Comparison of the experimental data to theoretical speciation indicated by a pE-versus-pH diagram revealed that the benefit of U solubility decreasing at lower TIC is only gained when the pH is held constant. However, a lower TIC and a constant pH were not realized in the H2 column due to the dynamics of the pH/alkalinity/total carbonate/CaCO 3 system. Nevertheless, based on prevailing theory, it was speculated that the superior U removal in the H2-supplied column may have been attributed to the presence of kinetically-limited Fe(OH)3 under the prevailing pE and pH conditions of the respective H2 and Ac columns. However, in the absence of sediment

  15. APFBC repowering could help meet Kyoto Protocol CO{sub 2} reduction goals[Advanced Pressurized Fluidized Bed Combustion

    SciTech Connect

    Weinstein, R.E.; Tonnemacher, G.C.

    1999-07-01

    The Clinton Administration signed the 1997 Kyoto Protocol agreement that would limit US greenhouse gas emissions, of which carbon dioxide (CO{sub 2}) is the most significant. While the Kyoto Protocol has not yet been submitted to the Senate for ratification, in the past, there have been few proposed environmental actions that had continued and wide-spread attention of the press and environmental activists that did not eventually lead to regulation. Since the Kyoto Protocol might lead to future regulation, its implications need investigation by the power industry. Limiting CO{sub 2} emissions affects the ability of the US to generate reliable, low cost electricity, and has tremendous potential impact on electric generating companies with a significant investment in coal-fired generation, and on their customers. This paper explores the implications of reducing coal plant CO{sub 2} by various amounts. The amount of reduction for the US that is proposed in the Kyoto Protocol is huge. The Kyoto Protocol would commit the US to reduce its CO{sub 2} emissions to 7% below 1990 levels. Since 1990, there has been significant growth in US population and the US economy driving carbon emissions 34% higher by year 2010. That means CO{sub 2} would have to be reduced by 30.9%, which is extremely difficult to accomplish. The paper tells why. There are, however, coal-based technologies that should be available in time to make significant reductions in coal-plant CO{sub 2} emissions. Th paper focuses on one plant repowering method that can reduce CO{sub 2} per kWh by 25%, advanced circulating pressurized fluidized bed combustion combined cycle (APFBC) technology, based on results from a recent APFBC repowering concept evaluation of the Carolina Power and Light Company's (CP and L) L.V. Sutton steam station. The replacement of the existing 50-year base of power generating units needed to meet proposed Kyoto Protocol CO{sub 2} reduction commitments would be a massive undertaking. It is

  16. 49 CFR 229.49 - Main reservoir system.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... inch above the maximum working air pressure fixed by the chief mechanical officer of the carrier... reservoir of air under pressure to be used for operating those power controls. The reservoir shall be provided with means to automatically prevent the loss of pressure in the event of a failure of main air...

  17. Novel atmospheric pressure plasma device releasing atomic hydrogen: reduction of microbial-contaminants and OH radicals in the air

    NASA Astrophysics Data System (ADS)

    Nojima, Hideo; Park, Rae-Eun; Kwon, Jun-Hyoun; Suh, Inseon; Jeon, Junsang; Ha, Eunju; On, Hyeon-Ki; Kim, Hye-Ryung; Choi, Kyoung Hui; Lee, Kwang-Hee; Seong, Baik-Lin; Jung, Hoon; Kang, Shin Jung; Namba, Shinichi; Takiyama, Ken

    2007-01-01

    A novel atmospheric pressure plasma device releasing atomic hydrogen has been developed. This device has specific properties such as (1) deactivation of airborne microbial-contaminants, (2) neutralization of indoor OH radicals and (3) being harmless to the human body. It consists of a ceramic plate as a positive ion generation electrode and a needle-shaped electrode as an electron emission electrode. Release of atomic hydrogen from the device has been investigated by the spectroscopic method. Optical emission of atomic hydrogen probably due to recombination of positive ions, H+(H2O)n, generated from the ceramic plate electrode and electrons emitted from the needle-shaped electrode have been clearly observed in the He gas (including water vapour) environment. The efficacy of the device to reduce airborne concentrations of influenza virus, bacteria, mould fungi and allergens has been evaluated. 99.6% of airborne influenza virus has been deactivated with the operation of the device compared with the control test in a 1 m3 chamber after 60 min. The neutralization of the OH radical has been investigated by spectroscopic and biological methods. A remarkable reduction of the OH radical in the air by operation of the device has been observed by laser-induced fluorescence spectroscopy. The cell protection effects of the device against OH radicals in the air have been observed. Furthermore, the side effects have been checked by animal experiments. The harmlessness of the device has been confirmed.

  18. SMALL, GEOLOGICALLY COMPLEX RESERVOIRS CAN BENEFIT FROM RESERVOIR SIMULATION

    SciTech Connect

    Richard E. Bennett

    2002-06-24

    The Cascade Sand zone of the Mission-Visco Lease in the Cascade Oil field of Los Angeles County, California, has been under water flood since 1970. Increasing water injection to increase oil production rates was being considered as an opportunity to improve oil recovery. However, a secondary gas cap had formed in the up-dip portion of the reservoir with very low gas cap pressures, creating concern that oil could be displaced into the gas cap resulting in the loss of recoverable oil. Therefore, injecting gas into the gas cap to keep the gas cap pressurized and restrict the influx of oil during water injection was also being considered. Further, it was recognized that the reservoir geology in the gas cap area is very complex with numerous folding and faulting and thus there are potential pressure barriers in several locations throughout the reservoir. With these conditions in mind, there were concerns regarding well to well continuity in the gas cap, which could interfere with the intended repressurization impact. Concerns about the pattern of gas flow from well to well, the possibilities of cycling gas without the desired increased pressure, and the possible loss of oil displaced into the gas cap resulted in the decision to conduct a gas tracer survey in an attempt to better define inter-well communication. Following the gas tracer survey, a reservoir model would be developed to integrate the findings of the gas tracer survey, known geologic and reservoir data, and historic production data. The reservoir model would be used to better define the reservoir characteristics and provide information that could help optimize the waterflood-gas injection project under consideration for efficient water and gas injection management to increase oil production. However, due to inadequate gas sampling procedures in the field and insufficiently developed laboratory analytical techniques, the laboratory was unable to detect the tracer in the gas samples taken. At that point, focus

  19. Increase in stagnation pressure and enthalpy in shock tunnels

    NASA Technical Reports Server (NTRS)

    Bogdanoff, David W.; Cambier, Jean-Luc

    1993-01-01

    A new technique based on the insertion of a converging section in the driven tube is described which is capable of producing substantial increases in both reservoir pressure and enthalpy. A 1D inviscid full kinetics code is used to study a number of different locations and shapes for the converging driven tube section. For driven tube diameter reductions of factors of 2 and 3, the reservoir pressure is found to increase by factors of 2.1 and 3.2, respectively, and the enthalpy is found to simultaneously increase by factors of 1.5 and 2.1, respectively.

  20. Depletion performance of layered reservoirs without crossflow

    SciTech Connect

    Fetkovich, M.J.; Works, A.M.; Thrasher, T.S. ); Bradley, M.D. )

    1990-09-01

    This paper presents a study of the rate/time and pressure/cumulative-production depletion performance of a two-layered gas reservoir producing without crossflow. The gas reservoir has produced for more than 20 years at an effectively constant wellbore pressure, thus giving continuously declining rate/time and pressure/cumulative-production data for analysis. The field data demonstrates that Arps depletion-decline exponents between 0.5 and 1 can be obtained with a no-crossflow, layered reservoir description. Rate-vs.-time and pressure-vs.-cumulative-production predictions were developed from both 2D numerical and simplified tank models of a two layered, no-crossflow system. These results demonstrate the effects of changes in reservoir layer volumes, permeability, and skin on the depletion performance.

  1. Numerical simulation of the environmental impact of hydraulic fracturing of tight/shale gas reservoirs on near-surface groundwater: Background, base cases, shallow reservoirs, short-term gas, and water transport

    PubMed Central

    Reagan, Matthew T; Moridis, George J; Keen, Noel D; Johnson, Jeffrey N

    2015-01-01

    Hydrocarbon production from unconventional resources and the use of reservoir stimulation techniques, such as hydraulic fracturing, has grown explosively over the last decade. However, concerns have arisen that reservoir stimulation creates significant environmental threats through the creation of permeable pathways connecting the stimulated reservoir with shallower freshwater aquifers, thus resulting in the contamination of potable groundwater by escaping hydrocarbons or other reservoir fluids. This study investigates, by numerical simulation, gas and water transport between a shallow tight-gas reservoir and a shallower overlying freshwater aquifer following hydraulic fracturing operations, if such a connecting pathway has been created. We focus on two general failure scenarios: (1) communication between the reservoir and aquifer via a connecting fracture or fault and (2) communication via a deteriorated, preexisting nearby well. We conclude that the key factors driving short-term transport of gas include high permeability for the connecting pathway and the overall volume of the connecting feature. Production from the reservoir is likely to mitigate release through reduction of available free gas and lowering of reservoir pressure, and not producing may increase the potential for release. We also find that hydrostatic tight-gas reservoirs are unlikely to act as a continuing source of migrating gas, as gas contained within the newly formed hydraulic fracture is the primary source for potential contamination. Such incidents of gas escape are likely to be limited in duration and scope for hydrostatic reservoirs. Reliable field and laboratory data must be acquired to constrain the factors and determine the likelihood of these outcomes. Key Points: Short-term leakage fractured reservoirs requires high-permeability pathways Production strategy affects the likelihood and magnitude of gas release Gas release is likely short-term, without additional driving forces PMID

  2. Substrate-specific pressure-dependence of microbial sulfate reduction in deep-sea cold seep sediments of the Japan Trench.

    PubMed

    Vossmeyer, Antje; Deusner, Christian; Kato, Chiaki; Inagaki, Fumio; Ferdelman, Timothy G

    2012-01-01

    The influence of hydrostatic pressure on microbial sulfate reduction (SR) was studied using sediments obtained at cold seep sites from 5500 to 6200 m water depth of the Japan Trench. Sediment samples were stored under anoxic conditions for 17 months in slurries at 4°C and at in situ pressure (50 MPa), at atmospheric pressure (0.1 MPa), or under methanic conditions with a methane partial pressure of 0.2 MPa. Samples without methane amendment stored at in situ pressure retained higher levels of sulfate reducing activity than samples stored at 0.1 MPa. Piezophilic SR showed distinct substrate specificity after hydrogen and acetate addition. SR activity in samples stored under methanic conditions was one order of magnitude higher than in non-amended samples. Methanic samples stored under low hydrostatic pressure exhibited no increased SR activity at high pressure even with the amendment of methane. These new insights into the effects of pressure on substrate specific sulfate reducing activity in anaerobic environmental samples indicate that hydrostatic pressure must be considered to be a relevant parameter in ecological studies of anaerobic deep-sea microbial processes and long-term storage of environmental samples.

  3. Substrate-specific pressure-dependence of microbial sulfate reduction in deep-sea cold seep sediments of the Japan Trench

    PubMed Central

    Vossmeyer, Antje; Deusner, Christian; Kato, Chiaki; Inagaki, Fumio; Ferdelman, Timothy G.

    2012-01-01

    The influence of hydrostatic pressure on microbial sulfate reduction (SR) was studied using sediments obtained at cold seep sites from 5500 to 6200 m water depth of the Japan Trench. Sediment samples were stored under anoxic conditions for 17 months in slurries at 4°C and at in situ pressure (50 MPa), at atmospheric pressure (0.1 MPa), or under methanic conditions with a methane partial pressure of 0.2 MPa. Samples without methane amendment stored at in situ pressure retained higher levels of sulfate reducing activity than samples stored at 0.1 MPa. Piezophilic SR showed distinct substrate specificity after hydrogen and acetate addition. SR activity in samples stored under methanic conditions was one order of magnitude higher than in non-amended samples. Methanic samples stored under low hydrostatic pressure exhibited no increased SR activity at high pressure even with the amendment of methane. These new insights into the effects of pressure on substrate specific sulfate reducing activity in anaerobic environmental samples indicate that hydrostatic pressure must be considered to be a relevant parameter in ecological studies of anaerobic deep-sea microbial processes and long-term storage of environmental samples. PMID:22822404

  4. Development planning and reservoir management in the Duri steam flood

    SciTech Connect

    Gael, B.T.; Gross, S.J.; McNaboe, G.J.

    1995-12-31

    The overall objective of reservoir management and development planning for the Duri field is to maximize project value. Key elements of Duri`s reservoir management practices include: injecting steam in new patterns at rates up to about 1.2 BCWEPD/NAF or the maximum rates achievable below fracture pressure; distributing the steam into reservoir layers in proportion to their h{phi}S{sub o}; maintaining these rates until steam breakthrough occurs in multiple wells in a pattern; then performing injector wellwork to shift steam out of the breakthrough layers while continuing initial rates into the non-breakthrough layers. The area-wide rate reduction schedule caused by these shifts resembles a heat balance (Vogel) rate reduction schedule. The steam that is shifted out of an old steamflood development area becomes the supply of steam for the start up of a new area. Key elements of Duri`s development planning practices include: obtaining sufficient reservoir information to be able to predict performance of all areas in the field; dividing the undeveloped parts of the field into steamflood areas that are logical and will fit the steam availability and construction scheduling constraints of the project; ranking the new projects by their profitability; and installing them at a schedule that matches the steam shifts out of the old areas with the ramp up of the new area so that steam plant capacity is fully utilized. This paper discusses the interrelationships between reservoir management practices, development planning, and the maximization of overall DSF project value.

  5. Reduction of peak plantar pressure in people with diabetes-related peripheral neuropathy: an evaluation of the DH Pressure Relief Shoe™

    PubMed Central

    2012-01-01

    Background Offloading plantar pressure is a key strategy for the prevention or healing of neuropathic plantar ulcers in diabetes. Non-removable walking casts, such as total contact casts, are currently considered the gold-standard for offloading this type of wound. However, alternative methods for offloading that are more cost effective and easier to use are continually being sought. The aim of this study was to evaluate the capacity of the DH Pressure Relief Shoe™ to offload high pressure areas under the neuropathic foot in diabetes. Methods A within-subjects, repeated measures design was used. Sixteen participants with diabetic peripheral neuropathy were recruited and three footwear conditions were evaluated in a randomised order: a canvas shoe (the control), the participants’ own standard shoe, and the DH Pressure Relief Shoe™. The primary outcome was peak plantar pressure, measured using the pedar-X® mobile in-shoe system between the three conditions. Results Data analysis was conducted on 14 out of the 16 participants because two participants could not complete data collection. The mean peak pressure values in kPa (±SD) for each condition were: control shoe 315.9 (±140.7), participants’ standard shoe 273.0 (±127.1) and DH Pressure Relief Shoe™ 155.4 (±89.9). There was a statistically significant difference in peak plantar pressure between the DH Pressure Relief Shoe™ compared to both the control shoe (p = 0.002) and participants’ standard shoe (p = 0.001). The DH Pressure Relief Shoe™ decreased plantar pressures by 51% compared to the control shoe and by 43% compared to participants’ standard shoe. Importantly, for a couple of study participants, the DH Pressure Relief Shoe™ appeared unsuitable for day-to-day wearing. Conclusions The DH Pressure Relief Shoe™ reduced plantar pressures more than the other two shoe conditions. The DH Pressure Relief Shoe™ may be a useful alternative to current offloading modalities used in

  6. Effects of confining pressure, pore pressure and temperature on absolute permeability. SUPRI TR-27

    SciTech Connect

    Gobran, B.D.; Ramey, H.J. Jr.; Brigham, W.E.

    1981-10-01

    This study investigates absolute permeability of consolidated sandstone and unconsolidated sand cores to distilled water as a function of the confining pressure on the core, the pore pressure of the flowing fluid and the temperature of the system. Since permeability measurements are usually made in the laboratory under conditions very different from those in the reservoir, it is important to know the effect of various parameters on the measured value of permeability. All studies on the effect of confining pressure on absolute permeability have found that when the confining pressure is increased, the permeability is reduced. The studies on the effect of temperature have shown much less consistency. This work contradicts the past Stanford studies by finding no effect of temperature on the absolute permeability of unconsolidated sand or sandstones to distilled water. The probable causes of the past errors are discussed. It has been found that inaccurate measurement of temperature at ambient conditions and non-equilibrium of temperature in the core can lead to a fictitious permeability reduction with temperature increase. The results of this study on the effect of confining pressure and pore pressure support the theory that as confining pressure is increased or pore pressure decreased, the permeability is reduced. The effects of confining pressure and pore pressure changes on absolute permeability are given explicitly so that measurements made under one set of confining pressure/pore pressure conditions in the laboratory can be extrapolated to conditions more representative of the reservoir.

  7. Comparison study of intraocular pressure reduction efficacy and safety between latanoprost and tafluprost in Japanese with normal-tension glaucoma

    PubMed Central

    Ikeda, Yoko; Mori, Kazuhiko; Tada, Kaori; Ueno, Morio; Kinoshita, Shigeru; Sotozono, Chie

    2016-01-01

    Purpose To evaluate and compare the intraocular pressure (IOP) reduction efficacy and safety between the ophthalmic solutions 0.005% latanoprost (Lat) and 0.0015% tafluprost (Taf) in Japanese patients with normal-tension glaucoma (NTG). Methods In this randomized nonmasked study, we prospectively enrolled 30 Japanese NTG patients who had used Lat monotherapy for more than 4 weeks, and randomly divided them into the following two groups: 1) Lat-to-Taf group (LT group) and 2) Taf-to-Lat group (TL group). At the beginning of the study, both groups were switched from initial Lat to Lat or Taf for 12 weeks, and then switched over to the other drug (crossover) for 12 additional weeks. At 0, 4, 12, 16, and 24 weeks, we evaluated each patient’s IOP, conjunctival injection, and corneal epitheliopathy score, and at 0, 12, and 24 weeks, we evaluated their eyelash changes and pigmentation of the eyelids and irises. Results The mean IOP of the LT group (15 eyes) was 10.5, 10.6, and 11.1 mmHg, at 0, 12, and 24 weeks, respectively, whereas that of the TL group (15 eyes) was 11.7, 11.1, and 10.5 mmHg at 0, 12, and 24 weeks, respectively. No significant differences were found between the two groups and in the intragroup comparisons. Moreover, no significant differences were found between Lat and Taf in regard to the conjunctival injection score and corneal epitheliopathy score. Eyelash changes and eyelid and iris pigmentation were similar in both groups. Conclusion The findings of this study show that Lat and Taf have equivalent efficacy and safety in Japanese patients with NTG. PMID:27601879

  8. Possible involvement of nitric oxide in morphine-induced miosis and reduction of intraocular pressure in rabbits.

    PubMed

    Bonfiglio, Vincenza; Bucolo, Claudio; Camillieri, Giovanni; Drago, Filippo

    2006-03-18

    The role of mu3 opioid receptors in morphine-induced intraocular pressure (IOP) lowering effect and miosis was evaluated in conscious, dark-adapted New Zealand white (NZW) rabbits using a masked-design study. IOP and pupil diameter (PD) measurements were taken at just before and 0.5, 1, 2, 4, 6 h after monolateral instillation of morphine (10, 50 and 100 microg/30 microl) as compared to vehicle administered in the contralateral eye. Morphine-induced ocular effects were challenged by a pre-treatment with the non-selective opioid receptor antagonist, naloxone (100 microg/30 microl), the nitric oxide synthase inhibitor, N(omega)-nitro-L-arginine methyl ester (L-NAME, 1%, 30 microl), or the non-selective mu3 opioid receptor inhibitor, reduced L-glutathione (GSH, 1%, 30 microl). Morphine induced a dose-dependent decrease in IOP and PD. Pre-treatment with naloxone totally prevented morphine-induced decrease in IOP and miosis. Ocular administration of L-NAME or GSH alone failed to affect IOP or PD of NZW rabbits. However, pre-treatment with either drugs significantly reduced, but not totally prevented ocular effects of morphine. These results suggest that biochemical mechanisms related to nitric oxide release are involved, at least in part, in morphine effects on the eye. Since the mu3 opioid receptor subtype is able to release nitric oxide and is sensitive to inactivation by GSH, it may be possible that mu3 opioid receptors are involved in morphine-induced miosis and reduction in IOP.

  9. Significance of Hematoma Shape and Density in Intracerebral Hemorrhage: The Intensive Blood Pressure Reduction in Acute Intracerebral Hemorrhage Trial Study.

    PubMed

    Delcourt, Candice; Zhang, Shihong; Arima, Hisatomi; Sato, Shoichiro; Al-Shahi Salman, Rustam; Wang, Xia; Davies, Leo; Stapf, Christian; Robinson, Thompson; Lavados, Pablo M; Chalmers, John; Heeley, Emma; Liu, Ming; Lindley, Richard I; Anderson, Craig S

    2016-05-01

    In patients with acute intracerebral hemorrhage (ICH), the shape and density of the hematoma are associated with its subsequent growth, but the impact of these parameters on clinical outcome is uncertain. Baseline computed tomographic scans and clinical data were obtained in the Intensive Blood Pressure Reduction in Acute Intracerebral Hemorrhage Trial (INTERACT2). Three independent neurologists blind to clinical data assessed ICH for shape and density using a previously described scale. Shape was defined as irregular when the ICH had ≥2 extra lesions added to the ellipsoid-shaped ICH. Density was heterogeneous when there were ≥3 low-density lesions within the ICH. Outcome measures were death and major disability (modified Rankin scale score of 3-5), combined and separate at 90-day postrandomization. Multivariable logistic regression models were used to determine the significance of hematoma characteristics on outcome. There were 2066 patient computed tomographic scans included in the analysis, with 46% and 38% having irregular and heterogeneous ICH, respectively. Irregular shape was independently associated with death/major disability (adjusted odds ratio, 1.60; 95% confidence interval [CI], 1.29-1.98) and major disability alone (adjusted odds ratio, 1.60; 95% CI, 1.31-1.95), but not with death alone (adjusted odds ratio, 0.97; 95% CI, 0.68-1.39). Heterogeneous density was not associated with clinical outcomes (adjusted odds ratio, 1.06; 95% CI, 0.85-1.33), 1.04 (95% CI, 0.73-1.48), and 1.14 (95% CI, 0.93-1.39), respectively, for death/major disability, death alone, and disability alone). Irregular shape, but not heterogeneous density, is independently associated with poor outcome after ICH. URL: http://www.clinicaltrials.gov. Unique identifier: NCT00716079. © 2016 American Heart Association, Inc.

  10. A new case of reservoir triggered seismicity: Govind Ballav Pant reservoir (Rihand dam), central India

    NASA Astrophysics Data System (ADS)

    Gahalaut, Kalpna; Gahalaut, V. K.; Pandey, M. R.

    2007-07-01

    We report here that seismicity near Govind Ballav Pant reservoir is strongly influenced by the reservoir operations. It is the second largest reservoir in India, which is built on Rihand river in the failed rift region of central India. Most of the earthquakes occurred during the high water stand in the reservoir with a time lag of about 1 month. We use the concept of coulomb stress change and use Green's function based approach to estimate stresses and pore pressure due to the reservoir load. We find that the reservoir increases coulomb stress on the nearby faults of the region that are favourably oriented for failure in predominantly reverse slip manner under the NNE-SSW compression and thus promotes failure. The above two factors make it an obvious, yet so far unreported case of reservoir triggered seismicity.

  11. Surrogate Reservoir Model

    NASA Astrophysics Data System (ADS)

    Mohaghegh, Shahab

    2010-05-01

    reservoir modeling becomes more pronounced. SRM is developed using the state of the art in neural computing and fuzzy pattern recognition to address the ever growing need in the oil and gas industry to perform accurate, but high speed simulation and modeling. Unlike conventional geo-statistical approaches (response surfaces, proxy models …) that require hundreds of simulation runs for development, SRM is developed only with a few (from 10 to 30 runs) simulation runs. SRM can be developed regularly (as new versions of the full field model become available) off-line and can be put online for real-time processing to guide important decisions. SRM has proven its value in the field. An SRM was developed for a giant oil field in the Middle East. The model included about one million grid blocks with more than 165 horizontal wells and took ten hours for a single run on 12 parallel CPUs. Using only 10 simulation runs, an SRM was developed that was able to accurately mimic the behavior of the reservoir simulation model. Performing a comprehensive reservoir analysis that included making millions of SRM runs, wells in the field were divided into five clusters. It was predicted that wells in cluster one & two are best candidates for rate relaxation with minimal, long term water production while wells in clusters four and five are susceptive to high water cuts. Two and a half years and 20 wells later, rate relaxation results from the field proved that all the predictions made by the SRM analysis were correct. While incremental oil production increased in all wells (wells in clusters 1 produced the most followed by wells in cluster 2, 3 …) the percent change in average monthly water cut for wells in each cluster clearly demonstrated the analytic power of SRM. As it was correctly predicted, wells in clusters 1 and 2 actually experience a reduction in water cut while a substantial increase in water cut was observed in wells classified into clusters 4 and 5. Performing these analyses

  12. Innovative techniques for the description of reservoir heterogeneity using tracers

    SciTech Connect

    Pope, G.; Sepehrnoori, K.

    1991-09-01

    The objective of this research is to develop an advanced, innovative technique for the description of reservoir heterogeneity. This proposed method consists of using tracers in single-well backflow tests. The general idea is to make use of fluid drift in the reservoir either due to naturally occurring pressure gradients in the reservoir, or by deliberately imposed pressure gradients using adjacent injection and production wells in the same reservoir. The analytical tool that will be used to design and interpret these tests is a compositional reservoir simulator with special features added and tested specifically for this purpose. 2 refs., 5 figs.

  13. Experimental Investigation on Oil Enhancement Mechanism of Hot Water Injection in tight reservoirs

    NASA Astrophysics Data System (ADS)

    Yongmao, Hao; Mingjing, Lu; Chengshun, Dong; Jianpeng, Jia; Yuliang, Su; Guanglong, Sheng

    2016-01-01

    Aimed at enhancing the oil recovery of tight reservoirs, the mechanism of hot water flooding was studied in this paper. Experiments were conducted to investigate the influence of hot water injection on oil properties, and the interaction between rock and fluid, petrophysical property of the reservoirs. Results show that with the injected water temperature increasing, the oil/water viscosity ratio falls slightly in a tight reservoir which has little effect on oil recovery. Further it shows that the volume factor of oil increases significantly which can increase the formation energy and thus raise the formation pressure. At the same time, oil/water interfacial tension decreases slightly which has a positive effect on production though the reduction is not obvious. Meanwhile, the irreducible water saturation and the residual oil saturation are both reduced, the common percolation area of two phases is widened and the general shape of the curve improves. The threshold pressure gradient that crude oil starts to flow also decreases. It relates the power function to the temperature, which means it will be easier for oil production and water injection. Further the pore characteristics of reservoir rocks improves which leads to better water displacement. Based on the experimental results and influence of temperature on different aspects of hot water injection, the flow velocity expression of two-phase of oil and water after hot water injection in tight reservoirs is obtained.

  14. Association between respiratory muscle strength and reduction of arterial blood pressure levels after aerobic training in hypertensive subjects

    PubMed Central

    Galdino, Giovane; Silva, Andreia Maria; Bogão, José Angelo; Braz de Oliveira, Marcos Paulo; Araújo, Hayslenne Andressa Gonçalves de Oliveira; Oliveira, Maísa Sodoco; Maldonado, Ana Clara Desiderio; Ulisses de Oliveira, Herick; Borges, Juliana Bassalobre Carvalho

    2016-01-01

    [Purpose] The purpose of present study was associate the increase of respiratory muscle strength with blood pressure levels in hypertensive subjects who underwent an aerobic exercise program. [Subjects and Methods] 90 hypertensive subjects were divided in two groups: intervention and control. All participants had an interview with a physiotherapist and were evaluated by 6-minute walk test, maximal inspiratory pressure, maximal expiratory pressure, heart rate, systolic blood pressure and diastolic blood pressure, before and after the 8 weeks. In the intervention group, the subjects underwent aerobic exercise program, 2 times a week for 8 weeks [Results] After the program, the levels of blood pressure were significantly reduced and the distance walked in the 6-minute walk test and the respiratory muscle strength were increased, compared to pre intervention and control group values. However, there was no correlation between the results provided by 6-minute walk test, maximal inspiratory pressure and maximal expiratory pressure with systolic arterial blood pressure levels. Nonetheless, the distance walked correlated with respiratory muscle strength values, in the intervention group. [Conclusion] The present study demonstrated that the aerobic training was effective in reducing the arterial blood pressure in hypertensive subjects associated with an improvement of physical conditioning and respiratory muscle strength. PMID:28174465

  15. Sulfur isotope analysis of bitumen and pyrite associated with thermal sulfate reduction in reservoir carbonates at the Big Piney-La Barge production complex

    NASA Astrophysics Data System (ADS)

    King, Hubert E.; Walters, Clifford C.; Horn, William C.; Zimmer, Mindy; Heines, Maureen M.; Lamberti, William A.; Kliewer, Christine; Pottorf, Robert J.; Macleod, Gordon

    2014-06-01

    Sulfur isotopes of solid bitumen and associated pyrite from the Madison Limestone in the Big Piney-La Barge production complex were measured using a Secondary Ion Mass Spectrometry (SIMS) method. The solid bitumens, a product of thermochemical sulfate reduction, yielded δ34S values of +18.9 ± 3.9 that are consistent with inferred values for native Mississippian sulfate. In contrast, coarse and fine grain pyrite grains were found to be 34S depleted, with values similar to that of the produced H2S (δ34S ∼ +10‰). We interpret these results to indicate that two different sources of sulfate were involved with TSR within the Madison Limestone-autochthonous anhydrite, which is now completely replaced with calcite, and Permian age sulfate dissolved in the aquifer. While checking for inclusions within the bitumen that could lead to erroneous measurement, we found the bitumen possesses a ∼5 μm rim and internal “worm-like” features enriched in organic sulfur. We hypothesize that the rim is the result of back reaction of the late forming H2S with the solid bitumen and that the <1 μm diameter wormy features may result from liquid-liquid immiscibility occurring at the high temperatures of formation.

  16. Impact of comprehensive cardiovascular risk reduction programme on risk factor clustering associated with elevated blood pressure in an Indian industrial population.

    PubMed

    Jeemon, Panniyammakal; Prabhakaran, Dorairaj; Goenka, Shifalika; Ramakrishnan, Lakshmy; Padmanabhan, Sandosh; Huffman, Mark; Joshi, Prashant; Sivasankaran, Sivasubramonian; Mohan, B V M; Ahmed, F; Ramanathan, Meera; Ahuja, R; Sinha, Nakul; Thankappan, K R; Reddy, K S

    2012-04-01

    Cardiovascular risk factors clustering associated with blood pressure (BP) has not been studied in the Indian population. This study was aimed at assessing the clustering effect of cardiovascular risk factors with suboptimal BP in Indian population as also the impact of risk reduction interventions. Data from 10543 individuals collected in a nation-wide surveillance programme in India were analysed. The burden of risk factors clustering with blood pressure and coronary heart disease (CHD) was assessed. The impact of a risk reduction programmme on risk factors clustering was prospectively studied in a sub-group. Mean age of participants was 40.9 ± 11.0 yr. A significant linear increase in number of risk factors with increasing blood pressure, irrespective of stratifying using different risk factor thresholds was observed. While hypertension occurred in isolation in 2.6 per cent of the total population, co-existence of hypertension and >3 risk factors was observed in 12.3 per cent population. A comprehensive risk reduction programme significantly reduced the mean number of additional risk factors in the intervention population across the blood pressure groups, while it continued to be high in the control arm without interventions (both within group and between group P<0.001). The proportion of 'low risk phenotype' increased from 13.4 to 19.9 per cent in the intervention population and it was decreased from 27.8 to 10.6 per cent in the control population (P<0.001). The proportion of individuals with hypertension and three more risk factors decreased from 10.6 to 4.7 per cent in the intervention arm while it was increased from 13.3 to 17.8 per cent in the control arm (P<0.001). Our findings showed that cardiovascular risk factors clustered together with elevated blood pressure and a risk reduction programme significantly reduced the risk factors burden.

  17. Impact of comprehensive cardiovascular risk reduction programme on risk factor clustering associated with elevated blood pressure in an Indian industrial population

    PubMed Central

    Jeemon, Panniyammakal; Prabhakaran, Dorairaj; Goenka, Shifalika; Ramakrishnan, Lakshmy; Padmanabhan, Sandosh; Huffman, Mark; Joshi, Prashant; Sivasankaran, Sivasubramonian; Mohan, B.V.M.; Ahmed, F.; Ramanathan, Meera; Ahuja, R.; Sinha, Nakul; Thankappan, K.R.; Reddy, K.S.

    2012-01-01

    Background & objectives: Cardiovascular risk factors clustering associated with blood pressure (BP) has not been studied in the Indian population. This study was aimed at assessing the clustering effect of cardiovascular risk factors with suboptimal BP in Indian population as also the impact of risk reduction interventions. Methods: Data from 10543 individuals collected in a nation-wide surveillance programme in India were analysed. The burden of risk factors clustering with blood pressure and coronary heart disease (CHD) was assessed. The impact of a risk reduction programmme on risk factors clustering was prospectively studied in a sub-group. Results: Mean age of participants was 40.9 ± 11.0 yr. A significant linear increase in number of risk factors with increasing blood pressure, irrespective of stratifying using different risk factor thresholds was observed. While hypertension occurred in isolation in 2.6 per cent of the total population, co-existence of hypertension and >3 risk factors was observed in 12.3 per cent population. A comprehensive risk reduction programme significantly reduced the mean number of additional risk factors in the intervention population across the blood pressure groups, while it continued to be high in the control arm without interventions (both within group and between group P<0.001). The proportion of ‘low risk phenotype’ increased from 13.4 to 19.9 per cent in the intervention population and it was decreased from 27.8 to 10.6 per cent in the control population (P<0.001). The proportion of individuals with hypertension and three more risk factors decreased from 10.6 to 4.7 per cent in the intervention arm while it was increased from 13.3 to 17.8 per cent in the control arm (P<0.001). Interpretation & conclusions: Our findings showed that cardiovascular risk factors clustered together with elevated blood pressure and a risk reduction programme significantly reduced the risk factors burden. PMID:22664495

  18. Reservoir response to tidal and barometric effects

    SciTech Connect

    Hanson, J.M.

    1980-05-29

    Solid earth tidal strain and surface loading due to fluctuations in barometric pressure have the effect, although extremely minute, of dilating or contracting the effective pore volume in a porous reservoir. If a well intersects the formation, the change in pore pressure can be measured with sensitive quartz pressure gauges. Mathematical models of the relevant fluid dynamics of the well-reservoir system have been generated and tested against conventional well pumping results or core data at the Salton Sea Geothermal Field (SSGF), California and at the Raft River, Geothermal Field (RRGF), Idaho. Porosity-total compressibility product evaluation based on tidal strain response compares favorably with results based on conventional pumping techniques. Analysis of reservoir response to barometric loading using Auto Regressive Integrated Moving Average (ARIMA) stochastic modeling appears also to have potential use for the evaluation of reservoir parameters.

  19. Self-Calibrating Pressure Transducer

    NASA Technical Reports Server (NTRS)

    Lueck, Dale E. (Inventor)

    2006-01-01

    A self-calibrating pressure transducer is disclosed. The device uses an embedded zirconia membrane which pumps a determined quantity of oxygen into the device. The associated pressure can be determined, and thus, the transducer pressure readings can be calibrated. The zirconia membrane obtains oxygen .from the surrounding environment when possible. Otherwise, an oxygen reservoir or other source is utilized. In another embodiment, a reversible fuel cell assembly is used to pump oxygen and hydrogen into the system. Since a known amount of gas is pumped across the cell, the pressure produced can be determined, and thus, the device can be calibrated. An isolation valve system is used to allow the device to be calibrated in situ. Calibration is optionally automated so that calibration can be continuously monitored. The device is preferably a fully integrated MEMS device. Since the device can be calibrated without removing it from the process, reductions in costs and down time are realized.

  20. Simulation of irreversible rock compaction effects on geopressured reservoir response: Topical report

    SciTech Connect

    Riney, T.D.

    1986-12-01

    A series of calculations are presented which quantitatively demonstrate the effects of nonlinear stress-deformation properties on the behavior of geopressured reservoirs. The range of stress-deformation parameters considered is based on information available from laboratory rock mechanics tests performed at the University of Texas at Austin and at Terra Tek, Inc. on cores recovered from geopressured wells. The effects of irreversible formation rock compaction, associated permeability reduction, and repetitive load/unload cycling are considered. The formation rock and geopressured brine properties are incorporated into an existing reservoir simulator using a bilinear model for the irreversible compaction process. Pressure drawdown and buildup testing of a well producing from the geopressured formation is simulated for a suite of calculations covering the range of formation parameters. The results are presented and discussed in terms of the inference (e.g., permeability and reservoir volume) that would be drawn from the simulated test data by an analyst using conventional methods.

  1. Effect of modest salt reduction on blood pressure, urinary albumin, and pulse wave velocity in white, black, and Asian mild hypertensives.

    PubMed

    He, Feng J; Marciniak, Maciej; Visagie, Elisabeth; Markandu, Nirmala D; Anand, Vidya; Dalton, R Neil; MacGregor, Graham A

    2009-09-01

    A reduction in salt intake lowers blood pressure. However, most previous trials were in whites with few in blacks and Asians. Salt reduction may also reduce other cardiovascular risk factors (eg, urinary albumin excretion, arterial stiffness). However, few well-controlled trials have studied these effects. We carried out a randomized double-blind crossover trial of salt restriction with slow sodium or placebo, each for 6 weeks, in 71 whites, 69 blacks, and 29 Asians with untreated mildly raised blood pressure. From slow sodium to placebo, urinary sodium was reduced from 165+/-58 (+/-SD) to 110+/-49 mmol/24 hours (9.7 to 6.5 g/d salt). With this reduction in salt intake, there was a significant decrease in blood pressure from 146+/-13/91+/-8 to 141+/-12/88+/-9 mm Hg (P<0.001), urinary albumin from 10.2 (IQR: 6.8 to 18.9) to 9.1 (6.6 to 14.0) mg/24 hours (P<0.001), albumin/creatinine ratio from 0.81 (0.47 to 1.43) to 0.66 (0.44 to 1.22) mg/mmol (P<0.001), and carotid-femoral pulse wave velocity from 11.5+/-2.3 to 11.1+/-1.9 m/s (P<0.01). Subgroup analysis showed that the reductions in blood pressure and urinary albumin/creatinine ratio were significant in all groups, and the decrease in pulse wave velocity was significant in blacks only. These results demonstrate that a modest reduction in salt intake, approximately the amount of the current public health recommendations, causes significant falls in blood pressure in all 3 ethnic groups. Furthermore, it reduces urinary albumin and improves large artery compliance. Although both could be attributable to the falls in blood pressure, they may carry additional benefits on reducing cardiovascular disease above that obtained from the blood pressure falls alone.

  2. Effect of antihypertensive agents on blood pressure variability: the Natrilix SR versus candesartan and amlodipine in the reduction of systolic blood pressure in hypertensive patients (X-CELLENT) study.

    PubMed

    Zhang, Yi; Agnoletti, Davide; Safar, Michel E; Blacher, Jacques

    2011-08-01

    To investigate the effect of different antihypertensive agents on blood pressure (BP) variability (BPV) and the underlying mechanism, we analyzed the ambulatory BP monitoring data of 577 patients before and after 3-month antihypertensive treatment, in the Natrilix SR Versus Candesartan and Amlodipine in the Reduction of Systolic Blood Pressure in Hypertensive Patients (X-CELLENT) Study, a multicenter, multinational, randomized, double-blind, placebo-controlled study with 4 parallel treatment arms (placebo, candesartan, indapamide sustained release, and amlodipine). Within-subject mean and SD of 24-hour BP, weighted by time interval between consecutive readings, were calculated in 3 time frames (daytime, nighttime, and 24 hours) to evaluate BP and BPV. The mean 24-hour heart rate (HR) and HR variability were calculated with the same algorithms. We found that the 3 antihypertensive drugs had a similar BP-lowering effect (P<0.001 for all), but amlodipine (P<0.007) and indapamide sustained release (P<0.04) were the only agents associated with a significantly decreased BPV after 3-month treatment. On the other hand, the major determinants of BPV at baseline were age, mean BP, and the corresponding HR variability. However, the reduction in BPV by amlodipine was significantly associated with the reduction in BP (P<0.006) and the reduction in HR variability (P<0.02), whereas the corresponding reduction by indapamide sustained release was only associated with the reduction in HR variability at night (P=0.004). In summary, 3-month amlodipine or indapamide sustained release treatment was associated with a significant reduction in BPV, and the mechanism of those reductions was possibly attributable to lowering BP or ameliorating the autonomic nervous system regulation or both. The combination of the 2 agents might help to optimize such properties.

  3. Numerical simulation of the environmental impact of hydraulic fracturing of tight/shale gas reservoirs on near-surface groundwater: Background, base cases, shallow reservoirs, short-term gas, and water transport

    DOE PAGES

    Reagan, Matthew T.; Moridis, George J.; Keen, Noel D.; ...

    2015-04-18

    Hydrocarbon production from unconventional resources and the use of reservoir stimulation techniques, such as hydraulic fracturing, has grown explosively over the last decade. However, concerns have arisen that reservoir stimulation creates significant environmental threats through the creation of permeable pathways connecting the stimulated reservoir with shallower freshwater aquifers, thus resulting in the contamination of potable groundwater by escaping hydrocarbons or other reservoir fluids. This study investigates, by numerical simulation, gas and water transport between a shallow tight-gas reservoir and a shallower overlying freshwater aquifer following hydraulic fracturing operations, if such a connecting pathway has been created. We focus on twomore » general failure scenarios: (1) communication between the reservoir and aquifer via a connecting fracture or fault and (2) communication via a deteriorated, preexisting nearby well. We conclude that the key factors driving short-term transport of gas include high permeability for the connecting pathway and the overall volume of the connecting feature. Production from the reservoir is likely to mitigate release through reduction of available free gas and lowering of reservoir pressure, and not producing may increase the potential for release. We also find that hydrostatic tight-gas reservoirs are unlikely to act as a continuing source of migrating gas, as gas contained within the newly formed hydraulic fracture is the primary source for potential contamination. Such incidents of gas escape are likely to be limited in duration and scope for hydrostatic reservoirs. Reliable field and laboratory data must be acquired to constrain the factors and determine the likelihood of these outcomes.« less

  4. Sleep-time blood pressure: prognostic value and relevance as a therapeutic target for cardiovascular risk reduction.

    PubMed

    Hermida, Ramón C; Ayala, Diana E; Fernández, José R; Mojón, Artemio

    2013-03-01

    Correlation between blood pressure (BP) level and target organ damage, cardiovascular disease (CVD) risk, and long-term prognosis is greater for ambulatory BP monitoring (ABPM) than clinical BP measurements. Nevertheless, the latter continue to be the "gold standard" to diagnose hypertension, assess CVD risk, and evaluate hypertension treatment. Independent ABPM studies have found that elevated sleep-time BP is a better predictor of CVD risk than either the awake or 24-h BP mean. A major limitation of all previous ABPM-based prognostic studies is the reliance only upon a single baseline profile from each participant at the time of inclusion, without accounting for potential changes in the level and pattern of ambulatory BP thereafter during follow-up. Accordingly, impact of the alteration over time, i.e., during long-term follow-up, of specific features of the 24-h BP variation on CVD risk has never been properly investigated. We evaluated the comparative prognostic value of (i) clinic and ambulatory BP; (ii) different ABPM-derived characteristics, e.g., asleep or awake BP mean; and (iii) specific changes in ABPM characteristic during follow-up, mainly whether reduced CVD risk is more related to the progressive decrease of asleep or awake BP. We prospectively studied 3344 subjects (1718 men/1626 women), 52.6 ± 14.5 (mean ± SD) yrs of age, during a median follow-up of 5.6 yrs. Those with hypertension at baseline were randomized to ingest all their prescribed hypertension medications upon awakening or ≥1 of them at bedtime. At baseline, BP was measured at 20-min intervals from 07:00 to 23:00 h and at 30-min intervals at night for 48-h, and physical activity was simultaneously monitored every min by wrist actigraphy to accurately derive awake and asleep BP means. Identical assessment was scheduled annually and more frequently (quarterly) if treatment adjustment was required. Data collected either at baseline or the last ABPM evaluation per participant

  5. High pressure pyrolyzed non-precious metal oxygen reduction catalysts for alkaline polymer electrolyte membrane fuel cells.

    PubMed

    Sanetuntikul, Jakkid; Shanmugam, Sangaraju

    2015-05-07

    Non-precious metal catalysts, such as metal-coordinated to nitrogen doped-carbon, have shown reasonable oxygen reduction reaction (ORR) performances in alkaline fuel cells. In this report, we present the development of a highly active, stable and low-cost non-precious metal ORR catalyst by direct synthesis under autogenic-pressure conditions. Transmission electron microscopy studies show highly porous Fe-N-C and Co-N-C structures, which were further confirmed by Brunauer-Emmett-Teller surface area measurements. The surface areas of the Fe-N-C and Co-N-C catalysts were found to be 377.5 and 369.3 m(2) g(-1), respectively. XPS results show the possible existence of N-C and M-Nx structures, which are generally proposed to be the active sites in non-precious metal catalysts. The Fe-N-C electrocatalyst exhibits an ORR half-wave potential 20 mV higher than the reference Pt/C catalyst. The cycling durability test for Fe-N-C over 5000 cycles shows that the half-wave potential lost only 4 mV, whereas the half-wave potential of the Pt/C catalyst lost about 50 mV. The Fe-N-C catalyst exhibited an improved activity and stability compared to the reference Pt/C catalyst and it possesses a direct 4-electron transfer pathway for the ORR process. Further, the Fe-N-C catalyst produces extremely low HO2(-) content, as confirmed by the rotating ring-disk electrode measurements. In the alkaline fuel single cell tests, maximum power densities of 75 and 80 mW cm(-2) were observed for the Fe-N-C and Pt/C cathodes, respectively. Durability studies (100 h) showed that decay of the fuel cell current was more prominent for the Pt/C cathode catalyst compared to the Fe-N-C cathode catalyst. Therefore, the Fe-N-C catalyst appears to be a promising new class of non-precious metal catalysts prepared by an autogenic synthetic method.

  6. Reduction of Listeria Innocua Contamination in Vacuum-Packaged Dry-Cured Italian Pork Products After High Hydrostatic Pressure Treatment.

    PubMed

    Merialdi, Giuseppe; Ramini, Mattia; Ravanetti, Emanuela; Gherri, Giorgio; Bonilauri, Paolo

    2015-05-28

    The present work aims to present the results of the application of a treatment with high hydrostatic pressure (HHP) on Italian fermented and dry-cured pork products. The products used in this study were portioned cured ham, portioned bacon and salami, vacuumpackaged and produced by a single processing company. Two studies were conducted on a single batch of the three products by means of an artificial contamination with Listeria innocua as a surrogate of L. monocytogenes. In the first trial a superficial contamination was obtained by immersion for 3 min in the culture broth with a concentration of approximately 9 log cfu/mL. At the end of the inoculum step, the pieces were dred at room temperature and vacuum packaged. In the second trial 50 kg of minced pork meat were contaminated before production of salami. In both cases the inoculum contained 5 strains of L. innocua. Subsequently, in both trials, 10 samples were randomly divided into two groups of 5 pieces each: i) TH group, samples treated with HHP; ii) group C, control samples, not subjected to any treatment. All samples were stored at refrigeration temperature at the end of HHP treatments (if applied), and analyzed for the determination of the surface (1st trial) and deep (2nd trial) quantitative contamination of L. innocua. pH and aW were also determined on 3 pieces of each products belonging to group C. The difference between the medians of the log cfu/cm2 or g established between controls and treated were compared using the non-parametric test (Kruskal-Wallis test) with P<0.01. In all products and in both trials the level of contamination detected in treatment groups was always significantly lower than in controls (P<0.01). In particular, in vacuum-packaged ham, bacon and salami viability logarithmic viability reductions equal to -2.29, -2.54 and -2.51 were observed, respectively. This study aimed to evaluate a not-thermal treatment on Italian cured or fermented pork products. The results of this study

  7. Pore-by-pore capillary pressure measurements using X-ray microtomography at reservoir conditions: Curvature, snap-off, and remobilization of residual CO2

    NASA Astrophysics Data System (ADS)

    Andrew, Matthew; Bijeljic, Branko; Blunt, Martin J.

    2014-11-01

    X-ray microtomography was used to image the shape and size of residual ganglia of supercritical CO2 at resolutions of 3.5 and 2 μm and at representative subsurface conditions of temperature and pressure. The capillary pressure for each ganglion was found by measuring the curvature of the CO2-brine interface, while the pore structure was parameterized using distance maps of the pore space. The formation of the residual clusters by snap-off was examined by comparing the ganglion capillary pressure to local pore topography. The capillary pressure was found to be inversely proportional to the radius of the largest restriction (throat) surrounding the ganglion, which validates the imbibition mechanisms used in pore-network modeling. The potential mobilization of residual ganglia was assessed using a reformulation of both the capillary (Ncmacro) and Bond numbers (Nbmacro), rigorously based on a balance of pore-scale forces, with the majority of ganglia remobilized at Ncmacro around 1. Buoyancy forces were found to be small in this system (Nbmacro << 1), meaning the gravitational remobilization of CO2 after residual trapping would be extremely difficult.

  8. Numerical Simulation of Subsurface Transport and Groundwater Impacts from Hydraulic Fracturing of Tight/Shale Gas Reservoirs

    NASA Astrophysics Data System (ADS)

    Reagan, M. T.; Moridis, G. J.; Keen, N. D.

    2014-12-01

    The use of reservoir stimulation techniques, such as hydraulic fracturing, has grown tremendously over the last decade, and concerns have arisen that reservoir stimulation creates environmental threats through the creation of permeable pathways that could connect the stimulated reservoir to shallower groundwater aquifers. This study investigates, by numerical simulation, gas and water transport between a deeper tight-gas reservoir and a shallower overlying groundwater aquifer following hydraulic fracturing operations, assuming that the formation of a connecting pathway has already occurred. We focus on two general transport scenarios: 1) communication between the reservoir and aquifer via a connecting fracture or fault and 2) communication via a deteriorated, preexisting nearby well. The simulations explore a range of permeabilities and geometries over time scales, and evaluate the mechanisms and factors that could lead to the escape of gas or reservoir fluid and the contamination of groundwater resources. We also examine the effects of overpressured reservoirs, and explore long-term transport processes as part of a continuing study. We conclude that the key factors driving short-term transport of gas include high permeability for the connecting pathway and the overall volume of the connecting feature. Gas production from the reservoir via a horizontal well is likely to mitigate release through the reduction of available free gas and the lowering of reservoir pressure. We also find that fractured tight-gas reservoirs are unlikely to act as a continuing source of large volumes of migrating gas, and incidents of gas escape are likely to be limited in duration and scope. Reliable field and laboratory data must be acquired to constrain the factors and determine the likelihood of these outcomes.

  9. Seismicity around Brazilian dam reservoirs

    SciTech Connect

    Coelho, P.E.F.P. )

    1987-01-01

    More than 30 cases of seismicity associated with dam reservoir sites are known throughout the world. Despite the lack of data in some areas, where seismicity occurred after reservoir impounding, there have been distinct seismic patterns observed in seismic areas after dam projects implantation. This has demonstrated that reservoir loading can trigger earthquakes. A mechanism of earthquake generation by reservoir impounding is proposed here with particular application to the Brazilian cases and to areas subject to low confining stress conditions in stable regions. Six artificial lakes are described and the associated earthquake sources are discussed in terms of natural or induced seismicity. Earthquake monitoring in Brazil up to 1967, when Brasilia's seismological station started operation, was mainly based in personal communications to the media. Therefore, there is a general lack of seismic records in relatively uninhabited areas, making it difficult to establish a seismic risk classification for the territory and to distinguish natural from induced seismicity. Despite this, cases reported here have shown an alteration of the original seismic stability in dam sites after reservoir loading, as observed by the inhabitants or records from Brasilia's seismological station. All cases appear to be related to an increase in pore pressure in permeable rocks or fracture zones which are confined between impermeable rock slabs or more competent rock. It is apparent that some cases show some participation of high residual stress conditions in the area.

  10. High pressure pyrolyzed non-precious metal oxygen reduction catalysts for alkaline polymer electrolyte membrane fuel cells

    NASA Astrophysics Data System (ADS)

    Sanetuntikul, Jakkid; Shanmugam, Sangaraju

    2015-04-01

    Non-precious metal catalysts, such as metal-coordinated to nitrogen doped-carbon, have shown reasonable oxygen reduction reaction (ORR) performances in alkaline fuel cells. In this report, we present the development of a highly active, stable and low-cost non-precious metal ORR catalyst by direct synthesis under autogenic-pressure conditions. Transmission electron microscopy studies show highly porous Fe-N-C and Co-N-C structures, which were further confirmed by Brunauer-Emmett-Teller surface area measurements. The surface areas of the Fe-N-C and Co-N-C catalysts were found to be 377.5 and 369.3 m2 g-1, respectively. XPS results show the possible existence of N-C and M-Nx structures, which are generally proposed to be the active sites in non-precious metal catalysts. The Fe-N-C electrocatalyst exhibits an ORR half-wave potential 20 mV higher than the reference Pt/C catalyst. The cycling durability test for Fe-N-C over 5000 cycles shows that the half-wave potential lost only 4 mV, whereas the half-wave potential of the Pt/C catalyst lost about 50 mV. The Fe-N-C catalyst exhibited an improved activity and stability compared to the reference Pt/C catalyst and it possesses a direct 4-electron transfer pathway for the ORR process. Further, the Fe-N-C catalyst produces extremely low HO2- content, as confirmed by the rotating ring-disk electrode measurements. In the alkaline fuel single cell tests, maximum power densities of 75 and 80 mW cm-2 were observed for the Fe-N-C and Pt/C cathodes, respectively. Durability studies (100 h) showed that decay of the fuel cell current was more prominent for the Pt/C cathode catalyst compared to the Fe-N-C cathode catalyst. Therefore, the Fe-N-C catalyst appears to be a promising new class of non-precious metal catalysts prepared by an autogenic synthetic method.Non-precious metal catalysts, such as metal-coordinated to nitrogen doped-carbon, have shown reasonable oxygen reduction reaction (ORR) performances in alkaline fuel cells. In

  11. Numerical Simulation for Natural State of Two-Phase Liquid Dominated Geothermal Reservoir with Steam Cap Underlying Brine Reservoir

    NASA Astrophysics Data System (ADS)

    Pratama, Heru Berian; Miryani Saptadji, Nenny

    2016-09-01

    Hydrothermal reservoir which liquid-dominated hydrothermal reservoir is a type of geothermal reservoir that most widely used for power plant. The exploitation of mass and heat from the geothermal fluid will decrease the pressure in the reservoir over time. Therefore the pressure drop in the reservoir will have an impact on the formation of boiling zones or boiling will increase. The impacts are an increase in the fraction of steam, dryness, in the reservoir and with good vertical permeability will form a steam cap underlying the brine reservoir. The two- phase liquid dominated reservoir is sensitive to the porosity and difficult to assign average properties of the entire reservoir when there is boiling zone in some area of the reservoir. These paper showed successful development of two-phase liquid dominated geothermal reservoir and discussed the formation of steam cap above brine reservoir through numerical simulation for state natural conditions. The natural state modeling in steam cap shows a match with the conceptual model of the vapor-dominated developed. These paper also proofed the presence of transition zone, boiling zone, between steam cap and brine reservoir.

  12. 49 CFR 229.49 - Main reservoir system.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... locomotive that has a pneumatically actuated system of power controls shall be equipped with a separate reservoir of air under pressure to be used for operating those power controls. The reservoir shall be... pressure, have storage capacity for not less than three complete operating cycles of control equipment and...

  13. 49 CFR 229.49 - Main reservoir system.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... locomotive that has a pneumatically actuated system of power controls shall be equipped with a separate reservoir of air under pressure to be used for operating those power controls. The reservoir shall be... pressure, have storage capacity for not less than three complete operating cycles of control equipment and...

  14. Quantitative Discomanometry: Correlation of Intradiscal Pressure Values to Pain Reduction in Patients With Intervertebral Disc Herniation Treated With Percutaneous, Minimally Invasive, Image-Guided Techniques

    SciTech Connect

    Filippiadis, Dimitrios K. Mazioti, A. Papakonstantinou, O. Brountzos, E.; Gouliamos, A.; Kelekis, N. Kelekis, A.

    2012-10-15

    Purpose: To illustrate quantitative discomanometry's (QD) diagnostic efficacy and predictive value in discogenic-pain evaluation in a prospective study correlating intradiscal pressure values with pain reduction after percutaneous image-guided technique (i.e., percutaneous decompression, PD). Materials and Methods: During the last 3 years, 36 patients [21 male and 15 female (mean age 36 {+-} 5.8 years)] with intervertebral disc hernia underwent QD before PD. Under absolute sterilization and fluoroscopy, a mixture of contrast medium and normal saline (3:1 ratio) was injected. A discmonitor performed a constant rate injection and recorded pressure and volume values, thus producing the relative pressure-volume curve. PD was then performed. Pain reduction and improved mobility were recorded at 3, 12, and 24 months after PD using clinical evaluation and a numeric visual scale (NVS; 0 to 10 units). Results: Mean pain values of 7.5 {+-} 1.9 (range 4 to 8) NVS units were recorded before PD; these decreased to 2.9 {+-} 2.44 at 3 months, 1.0 {+-} 1.9 at 12 months, and 1.0 {+-} 1.9 NVS units at 24 months after PD. Recorded correlations (pressure, volume, significant pain-reduction values) with bilateral statistical significance included a maximum injected volume of 2.4 ml (p = 0.045), P{sub o} < 14 psi [initial pressure required to inject 0.1 ml of the mixture inside the disc (p = 0.05)], P{sub max} {<=} 65 psi [greatest pressure value on the curve (p = 0.018)], and P{sub max} - P{sub o} {<=} 47 psi (p = 0.038). Patients meeting these pressure or volume cut-off points, either independently or as a total, had significant pain reduction (>4 NVS units) after PD. No complications were noted. Conclusions: QD is an efficient technique that may have predictive value for discogenic pain evaluation. It might serve as a useful tool for patient selection for intervertebral disc therapies.

  15. Right ventricular pressure changes during induced ventricular tachycardias predict clinical symptoms of cerebral hypoperfusion: implications for a reduction of unnecessary, painful ICD shocks.

    PubMed

    Petrucci, Ettore; Sarzi Braga, Simona; Balian, Vruyr; Pedretti, Roberto F E

    2009-03-01

    ICD shocks occurring in conscious patients (as in the case of well-tolerated arrhythmias, electromagnetic interference, or oversensing) have a deleterious impact on the quality of life. We evaluated if a hemodynamic parameter, calculated from the right ventricular pressure (RVP) or systemic arterial pressure (AP) signals, could predict early clinical symptoms of cerebral hypoperfusion during induced ventricular tachycardias (VTs). We analyzed 42 tolerated (no symptoms) and 30 untolerated (syncope or severe symptoms within 30 seconds from the onset) VTs, induced during electrophysiological study. The cycle length (CL) and the hemodynamic data (mean AP and RVP, arterial pulse pressure and RV pulse pressure, and maximum AP and RVP dP/dT) were automatically sampled in two VT epochs: the "detection" window, from beat 24 to 32, and the "preintervention" window, immediately before the first therapeutic attempt. Although the CL and all the hemodynamic parameters (expressed as % change versus pre-VT values) were significantly lower in untolerated versus tolerated VTs both at detection and preintervention (with the exception of the mean RVP which progressively increased in both groups), ROC analysis demonstrated that only the preintervention RV pulse pressure showed no overlap between groups, providing 100% sensitivity and positive predictive value. The reduction of the RV pulse pressure is a better predictor of early cerebral symptoms than CL or other hemodynamic indexes during induced VTs. Since long-term RVP monitoring is feasible, this parameter could be incorporated into ICDs decisional path, in the perspective of reducing unnecessary, painful shocks.

  16. Computational and experimental investigation of the drag reduction and the components of pressure drop in horizontal slug flow using liquids of different viscosities

    SciTech Connect

    Daas, Mutaz; Bleyle, Derek

    2006-03-01

    Computational and experimental investigation in 10-cm ID horizontal pipes have been carried out utilizing carbon dioxide as the gas phase and two types of oil with different viscosities; namely 0.0025Pas and 0.05Pas, as the liquid phase. The influence of oil viscosity on the magnitude of total pressure drop and each of its components as well as the effectiveness of a drag reducing additive (DRA, CDR WS 500M flow improver) in decreasing the pressure loss was investigated in two-phase oil-gas slug flow. The effects of changing oil viscosity on the contribution of frictional and accelerational components to total pressure drop in slug flow were also examined and analyzed. Computations of accelerational and frictional components of pressure drop were performed. The accelerational component of pressure drop was dominant in the 0.0025Pas oil while the frictional component had significant contributions in the 0.05Pas oil. Despite the fact that the magnitude of drag reduction was higher in the 0.05Pas oil, the DRA was more effective in reducing the total pressure drop and its components in the 0.0025Pas oil. (author)

  17. Isotactic poly(4-methyl-1-pentene) melt as a porous liquid: Reduction of compressibility due to penetration of pressure medium

    NASA Astrophysics Data System (ADS)

    Chiba, Ayano; Inui, Masanori; Kajihara, Yukio; Fuchizaki, Kazuhiro; Akiyama, Ryo

    2017-05-01

    A pressure-induced structural change of a polymer isotactic poly(4-methyl-1-pentene) (P4MP1) in the melted state at 270 °C has been investigated by high-pressure in situ x-ray diffraction, where high pressures up to 1.8 kbar were applied using helium gas. The first sharp diffraction peak (FSDP) position of the melt shows a less pressure dependence than that of the normal compression using a solid pressure transmitting medium. The contraction using helium gas was about 10% at 2 kbar, smaller than about 20% at the same pressure using a solid medium. The result indicates that helium entered the interstitial space between the main chains. The helium/monomer molar ratio was estimated to be 0.3 at 2 kbar from the FSDP positions. These results suggest that the compressibility of the P4MP1 melt can be largely dependent on the pressure transmitting media. As the pore size is reversibly and continuously controllable by compression, we suggest that the P4MP1 melt can be an ideal porous liquid for investigating a novel mechanical response of the pores in a non-crystalline substance.

  18. Isotactic poly(4-methyl-1-pentene) melt as a porous liquid: Reduction of compressibility due to penetration of pressure medium.

    PubMed

    Chiba, Ayano; Inui, Masanori; Kajihara, Yukio; Fuchizaki, Kazuhiro; Akiyama, Ryo

    2017-05-21

    A pressure-induced structural change of a polymer isotactic poly(4-methyl-1-pentene) (P4MP1) in the melted state at 270 °C has been investigated by high-pressure in situ x-ray diffraction, where high pressures up to 1.8 kbar were applied using helium gas. The first sharp diffraction peak (FSDP) position of the melt shows a less pressure dependence than that of the normal compression using a solid pressure transmitting medium. The contraction using helium gas was about 10% at 2 kbar, smaller than about 20% at the same pressure using a solid medium. The result indicates that helium entered the interstitial space between the main chains. The helium/monomer molar ratio was estimated to be 0.3 at 2 kbar from the FSDP positions. These results suggest that the compressibility of the P4MP1 melt can be largely dependent on the pressure transmitting media. As the pore size is reversibly and continuously controllable by compression, we suggest that the P4MP1 melt can be an ideal porous liquid for investigating a novel mechanical response of the pores in a non-crystalline substance.

  19. Reservoir modles

    SciTech Connect

    Malzahn, Mark

    1987-01-06

    The project to match the pressure response seen at EE-3A during the final shut-in of the ICFT initially began as an attempt to solve a mass-balance equation for an inflated, penny-shaped planar fracture during shut-in. Implicit assumptions include no flow along the fracture, no fracture extension after shut-in, constant fracture length and a homogenous rock mass with constant permeability surrounding the fracture. The resulting expression equates the fluid volume permeating into the rock to the change in volume of the fracture as it deflates during shut-in.

  20. A kinetic pressure effect on the experimental abiotic reduction of aqueous CO2 to methane from 1 to 3.5 kbar at 300 °C

    NASA Astrophysics Data System (ADS)

    Lazar, Codi; Cody, George D.; Davis, Jeffrey M.

    2015-02-01

    Aqueous abiotic methane concentrations in a range of geologic settings are below levels expected for equilibrium with coexisting CO2 and H2, indicating that kinetics can control the speciation of reduced carbon-bearing fluids. Previous studies have suggested that mineral catalysts or gas-phase reactions may increase the rate of methanogenesis. Here, we report on experiments that indicate pressure can also accelerate aqueous reduction of CO2 to CH4. Four series of cold-seal hydrothermal experiments were performed from 1 to 3.5 kbar at 300 °C for two weeks and analyzed using gas chromatography/mass spectrometry. The starting fluids were 10-20-μL solutions of 70-mmolal 13C-labeled formic acid (H13COOH) contained in welded gold capsules. Increasing pressure (P) resulted in a systematic, reproducible log-linear increase in 13CH4 yields. The pressure effect could be quantified the log-linear slope, Δlog[13CH4]/ΔP (log mmolal per kbar). The mean slope was 0.66 ± 0.05 (±1s.e.), indicating that 13CH4 yields increased by an average factor of 40-50 over a P range of 2.5 kbar. Pressure-independent variations in [13CH4] were observed as scatter about the log-linear regressions and as variations in the y-intercepts of the regressions. These variations were attributed to trace amounts of catalytic Fe along the inner capsule wall that remained despite cleaning the Au capsules in nitric acid prior to each experimental series. The mechanism for the pressure-dependent effect was interpreted to result from one or more of the following three processes: reduction of a metastable reaction intermediate such as methanol, formation of Fe-carbonyl complexes in the fluid, and/or heterogeneous catalysis by Fe. The results suggest that pressure may influence aqueous abiotic CH4 yields in certain geological environments, particularly when the relative effects of other kinetic factors such as temperature are diminished, e.g., in cool forearcs or other settings with a steep geothermal

  1. 08FFL-0020Influence of High Fuel Rail Pressure and Urea Selective Catalytic Reduction on PM Formation in an Off-Highway Heavy-Duty Diesel Engine

    SciTech Connect

    Kass, Michael D; Domingo, Norberto; Storey, John Morse; Lewis Sr, Samuel Arthur

    2008-01-01

    The influence of fuel rail pressure (FRP) and urea-selective catalytic reduction (SCR) on particulate matter (PM) formation is investigated in this paper along with notes regarding the NOx and other emissions. Increasing FRP was shown to reduce the overall soot and total PM mass for four operating conditions. These conditions included two high speed conditions (2400 rpm at 540 and 270 Nm of torque) and two moderated speed conditions (1400 rpm at 488 and 325 Nm). The concentrations of CO2 and NOx increased with fuel rail pressure and this is attributed to improved fuel-air mixing. Interestingly, the level of unburned hydrocarbons remained constant (or increased slightly) with increased FRP. PM concentration was measured using an AVL smoke meter and scanning mobility particle sizer (SMPS); and total PM was collected using standard gravimetric techniques. These results showed that the smoke number and particulate concentrations decrease with increasing FRP. However the decrease becomes more gradual as very high rail pressures. Additionally, the total PM decreased with increasing FRP; however, the soluble organic fraction (SOF) reaches a maximum after which it declines with higher rail pressure. The total PM was collected for the two 1400 rpm conditions downstream of the engine, diesel oxidation catalyst, and a urea-SCR catalyst. The results show that significant PM reduction occurs in the SCR catalyst even during high rates of urea dosage. Analysis of the PM indicates that residual SOF is burned up in the SCR catalyst.

  2. Evaluation of blood pressure reduction response and responder characteristics to fixed-dose combination treatment of amlodipine and losartan: a post hoc analysis of pooled clinical trials.

    PubMed

    Unniachan, Sreevalsa; Wu, David; Rajagopalan, Srinivasan; Hanson, Mary E; Fujita, Kenji P

    2014-09-01

    Data from four clinical trials compared reductions in systolic blood pressure (SBP) and diastolic blood pressure (DBP) among patients treated with amlodipine/losartan 5/50 mg vs 5/100 mg and amlodipine/losartan 5/50 mg vs amlodipine 5 mg and 10 mg. Response rate was assessed as reduction in SBP or DBP (>20/10 mm Hg) and proportion of patients achieving SBP <140 mm Hg or DBP <90 mm Hg. Patients were grouped into quartiles based on baseline SBP and DBP. Mean SBP and DBP were reduced in amlodipine/losartan 5/50 mg (n=182) and amlodipine/losartan 5/100 mg (n=95) users across all baseline quartiles. Patients using amlodipine/losartan 5/50 mg had significantly greater SBP and DBP reductions vs amlodipine 5 mg (P=.001 and P=.02, respectively). Amlodipine/losartan 5/50 mg users had significantly greater SBP reduction vs amlodipine 10 mg (SBP P=.02; DBP P=not significant). The odds of responding to therapy were significantly greater with amlodipine/losartan 5/50 mg vs amlodipine 5 mg (odds ratio, 5.33; 95% confidence interval, 1.42-25.5) and were similar vs amlodipine 10 mg (odds ratio, 0.67; 95% confidence interval, 0.017-9.51). These results support the use of combination therapy early in the treatment of hypertension.

  3. Predictors of Nonadherence to Topical Intraocular Pressure Reduction Medications Among Medicare Members: A Claims-Based Retrospective Cohort Study.

    PubMed

    Sheer, Richard; Bunniran, Suvapun; Uribe, Claudia; Fiscella, Richard G; Patel, Vaishali D; Chandwani, Hitesh S

    2016-07-01

    Reported adherence rates with ocular hypotensive medications typically range from 51% to 56% over the first year of therapy. As intraocular pressure (IOP) reduction slows the progression of vision loss from glaucoma, early identification of nonadherent members is crucial to effective disease management. To (a) identify member characteristics and other factors related to nonadherence with topical IOP-lowering medications available in administrative claims data and (b) create a predictive model incorporating these variables. This retrospective cohort study analyzed data from Humana's administrative claims database. The study cohort included members aged 65-89 years enrolled in a Medicare Advantage Prescription Drug plan (MAPD; medical and pharmacy benefits), with > 1 topical IOP-lowering medication claims between January 2011 and September 2012 and a minimum of 24 months of continuous enrollment-12 months before and 12 months after the initial (index) prescription claim for a topical IOP-lowering medication. Adherence was defined as the proportion of days covered (PDC) with drug supply (calculated from the number of drops per bottle and dose) over the first year after the index prescription. Members with PDC > 0.80 were considered adherent, while members with PDC < 0.80 were considered nonadherent. Multivariable stepwise logistic regression with backward elimination was used to construct a predictive model for the likelihood of nonadherence (PDC < 0.80). The model was developed using 28 input variables*#x2013;10 variables were retained in the final model. 73,256 MAPD members were included in this study; most (69%) of these members were continuing topical IOP-lowering medication users. The proportion of patients adherent (PDC > 0.80) to IOP-lowering medications was 51%. The study sample was split, using a 2:1 ratio, into a development sample (n = 48,840 members) and a validation sample (n=24,416 members). The model performed equally well in the development sample and

  4. High-Reynolds-number turbulent-boundary-layer wall pressure fluctuations with skin-friction reduction by air injection.

    PubMed

    Winkel, Eric S; Elbing, Brian R; Ceccio, Steven L; Perlin, Marc; Dowling, David R

    2008-05-01

    The hydrodynamic pressure fluctuations that occur on the solid surface beneath a turbulent boundary layer are a common source of flow noise. This paper reports multipoint surface pressure fluctuation measurements in water beneath a high-Reynolds-number turbulent boundary layer with wall injection of air to reduce skin-friction drag. The experiments were conducted in the U.S. Navy's Large Cavitation Channel on a 12.9-m-long, 3.05-m-wide hydrodynamically smooth flat plate at freestream speeds up to 20 ms and downstream-distance-based Reynolds numbers exceeding 200 x 10(6). Air was injected from one of two spanwise slots through flush-mounted porous stainless steel frits (approximately 40 microm mean pore diameter) at volume flow rates from 17.8 to 142.5 l/s per meter span. The two injectors were located 1.32 and 9.78 m from the model's leading edge and spanned the center 87% of the test model. Surface pressure measurements were made with 16 flush-mounted transducers in an "L-shaped" array located 10.7 m from the plate's leading edge. When compared to no-injection conditions, the observed wall-pressure variance was reduced by as much as 87% with air injection. In addition, air injection altered the inferred convection speed of pressure fluctuation sources and the streamwise coherence of pressure fluctuations.

  5. Using Chemicals to Optimize Conformance Control in Fractured Reservoirs

    SciTech Connect

    Seright, R.S.

    1999-06-08

    This technical progress report describes work performed from October 1, 1998 through December 31, 1998, for the project, ''Using Chemicals to Optimize Conformance in Fractured Reservoirs.'' In our first task area, disproportionate permeability reduction, a literature survey and analysis are underway to identify options for reducing permeability to water much more than that to oil. In our second task area, we are encouraging the use of our recently developed software for sizing gelant treatments in hydraulically fractured production wells. In several field applications, we noted the importance of obtaining accurate values of the static reservoir pressure before using our program. In our third task area, we examined gel properties as they extruded through fractures. We found stable pressure gradients during injection of a large volume of a one-day-old Cr(III)-acetate-HPAM gel into a 0.04-in.-wide, four-ft-long fracture. This finding confirms that gel injection (under our specific circumstances) did not lead to continuously increasing pressure gradients and severely limited gel propagation. Our experiments also provided insights into the mechanism for gel propagation during extrusion through fractures.

  6. Status of Norris Reservoir

    SciTech Connect

    Not Available

    1990-09-01

    This is one in a series of reports prepared by the Tennessee Valley Authority (TVA) for those interested in the conditions of TVA reservoirs. This overview of Norris Reservoir summarizes reservoir and watershed characteristics, reservoir uses, conditions that impair reservoir uses, water quality and aquatic biological conditions, and activities of reservoir management agencies. This information was extracted from the most up-to-date publications and data available, and from interviews with water resource professionals in various federal, state, and local agencies, and in public and private water supply and wastewater treatment facilities. 14 refs., 3 figs.

  7. A general formulation for compositional reservoir simulation

    SciTech Connect

    Rodriguez, F.; Guzman, J.; Galindo-Nava, A. |

    1994-12-31

    In this paper the authors present a general formulation to solve the non-linear difference equations that arise in compositional reservoir simulation. The general approach here presented is based on newton`s method and provides a systematic approach to generate several formulations to solve the compositional problem, each possessing a different degree of implicitness and stability characteristics. The Fully-Implicit method is at the higher end of the implicitness spectrum while the IMPECS method, implicit in pressure-explicit in composition and saturation, is at the lower end. They show that all methods may be obtained as particular cases of the fully-implicit method. Regarding the matrix problem, all methods have a similar matrix structure; the composition of the Jacobian matrix is however unique in each case, being in some instances amenable to reductions for optimal solution of the matrix problem. Based on this, a different approach to derive IMPECS type methods is proposed; in this case, the whole set of 2nc + 6 equations, that apply in each gridblock, is reduced to a single pressure equation through matrix reduction operations; this provides a more stable numerical scheme, compared to other published IMPCS methods, in which the subset of thermodynamic equilibrium equations is arbitrarily decoupled form the set of gridblock equations to perform such reduction. The authors discuss how the general formulation here presented can be used to formulate and construct an adaptive-implicit compositional simulators. They also present results on the numerical performance of FI, IMPSEC and IMPECS methods on some test problems.

  8. Adsorption of water vapor on reservoir rocks

    SciTech Connect

    Not Available

    1993-07-01

    Progress is reported on: adsorption of water vapor on reservoir rocks; theoretical investigation of adsorption; estimation of adsorption parameters from transient experiments; transient adsorption experiment -- salinity and noncondensible gas effects; the physics of injection of water into, transport and storage of fluids within, and production of vapor from geothermal reservoirs; injection optimization at the Geysers Geothermal Field; a model to test multiwell data interpretation for heterogeneous reservoirs; earth tide effects on downhole pressure measurements; and a finite-difference model for free surface gravity drainage well test analysis.

  9. Dispersivity as an oil reservoir rock characteristic

    SciTech Connect

    Menzie, D.E.; Dutta, S.

    1989-12-01

    The main objective of this research project is to establish dispersivity, {alpha}{sub d}, as an oil reservoir rock characteristic and to use this reservoir rock property to enhance crude oil recovery. A second objective is to compare the dispersion coefficient and the dispersivity of various reservoir rocks with other rock characteristics such as: porosity, permeability, capillary pressure, and relative permeability. The dispersivity of a rock was identified by measuring the physical mixing of two miscible fluids, one displacing the other in a porous medium. 119 refs., 27 figs., 12 tabs.

  10. Basic gas storage reservoir operations and analysis

    SciTech Connect

    Nowaczewski, S.F. )

    1994-08-01

    Operation and performance analysis of gas storage reservoirs is described in very basic and general terms. Reservoir selection criteria (capacity, deliverability, location, field type, trap type) are reviewed. Well construction considerations and practices (casing sizing, placement, and cementing) are highlighted with regard to the need for long-lived safe operation. Deliverability estimation and prediction and gas inventory methodologies are described. The benefits of high density, high quality data on gas pressure and composition, production rates and volumes, and geologic information to reservoir performance evaluation and prediction are demonstrated.

  11. The Methane Hydrate Reservoir System

    NASA Astrophysics Data System (ADS)

    Flemings, P. B.; Liu, X.

    2007-12-01

    We use multi phase flow modeling and field examples (Hydrate Ridge, offshore Oregon and Blake Ridge, offshore North Carolina) to demonstrate that the methane hydrate reservoir system links traditional and non- traditional hydrocarbon system components: free gas flow is a fundamental control on this system. As in a traditional hydrocarbon reservoir, gas migrates into the hydrate reservoir as a separate phase (secondary migration) where it is trapped in a gas column beneath the base of the hydrate layer. With sufficient gas supply, buoyancy forces exceed either the capillary entry pressure of the cap rock or the fracture strength of the cap rock, and gas leaks into the hydrate stability zone, or cap rock. When gas enters the hydrate stability zone and forms hydrate, it becomes a very non traditional reservoir. Free gas forms hydrate, depletes water, and elevates salinity until pore water is too saline for further hydrate formation: salinity and hydrate concentration increase upwards from the base of the regional hydrate stability zone (RHSZ) to the seafloor and the base of the hydrate stability zone has significant topography. Gas chimneys couple the free gas zone to the seafloor through high salinity conduits that are maintained at the three-phase boundary by gas flow. As a result, significant amounts of gaseous methane can bypass the RHSZ, which implies a significantly smaller hydrate reservoir than previously envisioned. Hydrate within gas chimneys lie at the three-phase boundary and thus small increases in temperature or decreases in pressure can immediately transport methane into the ocean. This type of hydrate deposit may be the most economical for producing energy because it has very high methane concentrations (Sh > 70%) located near the seafloor, which lie on the three-phase boundary.

  12. Reduction of Mean Arterial Pressure and Proteinuria by the Effect of ACEIs (Lisinopril) in Kurdish Hypertensive Patients in Hawler City

    PubMed Central

    A.I., Muslih

    2012-01-01

    The angiotensin converting enzyme inhibitors (ACEIs) are a group of pharmaceuticals that are used primarily in treatment of hypertension and congestive heart failure, in some cases as the drugs of first choice. The renin-angiotensin system is activated in response to hypotension, decreased sodium concentration in the distal tubule, decreased blood volume and in renal sympathetic nerve stimulation. This study examines the effects of angiotensin converting enzyme inhibitor (Lisinopril) on blood pressure (BP) 131±2.4 and proteinuria 0.198±0.005 in Kurd hypertensive patients, mean arterial blood pressure and proteinuria excretion were measured weekly along the period of 12 weeks. Lisinopril significantly reduced mean arterial blood pressure, and attenuated proteinuria level in patients subjected to this study in lisinopril 10mg dose dependent manner (p<0.05, n=24). In conclusion, lisinopril is of beneficial of renoprotection and in lowering BP PMID:22980373

  13. Reduction of mean arterial pressure and proteinuria by the effect of ACEIs (Lisinopril) in Kurdish hypertensive patients in Hawler City.

    PubMed

    Muslih, A I

    2012-06-30

    The angiotensin converting enzyme inhibitors (ACEIs) are a group of pharmaceuticals that are used primarily in treatment of hypertension and congestive heart failure, in some cases as the drugs of first choice. The renin-angiotensin system is activated in response to hypotension, decreased sodium concentration in the distal tubule, decreased blood volume and in renal sympathetic nerve stimulation. This study examines the effects of angiotensin converting enzyme inhibitor (Lisinopril) on blood pressure (BP) 131 ± 2.4 and proteinuria 0.198 ± 0.005 in Kurd hypertensive patients, mean arterial blood pressure and proteinuria excretion were measured weekly along the period of 12 weeks. Lisinopril significantly reduced mean arterial blood pressure, and attenuated proteinuria level in patients subjected to this study in lisinopril 10mg dose dependent manner (p<0.05, n=24). In conclusion, lisinopril is of beneficial of renoprotection and in lowering BP.

  14. Blood pressure reductions following catheter-based renal denervation are not related to improvements in adherence to antihypertensive drugs measured by urine/plasma toxicological analysis.

    PubMed

    Ewen, Sebastian; Meyer, Markus R; Cremers, Bodo; Laufs, Ulrich; Helfer, Andreas G; Linz, Dominik; Kindermann, Ingrid; Ukena, Christian; Burnier, Michel; Wagenpfeil, Stefan; Maurer, Hans H; Böhm, Michael; Mahfoud, Felix

    2015-12-01

    Renal denervation can reduce blood pressure in patients with uncontrolled hypertension. The adherence to prescribed antihypertensive medication following renal denervation is unknown. This study investigated adherence to prescribed antihypertensive treatment by liquid chromatography-high resolution tandem mass spectrometry in plasma and urine at baseline and 6 months after renal denervation in 100 patients with resistant hypertension, defined as baseline office systolic blood pressure ≥140 mmHg despite treatment with ≥3 antihypertensive agents. At baseline, complete adherence to all prescribed antihypertensive agents was observed in 52 patients, 46 patients were partially adherent, and two patients were completely non-adherent. Baseline office blood pressure was 167/88 ± 19/16 mmHg with a corresponding 24-h blood pressure of 154/86 ± 15/13 mmHg. Renal denervation significantly reduced office and ambulatory blood pressure at 6-month follow-up by 15/5 mmHg (p < 0.001/p < 0.001) and 8/4 mmHg (p < 0.001/p = 0.001), respectively. Mean adherence to prescribed treatment was significantly reduced from 85.0 % at baseline to 80.7 %, 6 months after renal denervation (p = 0.005). The blood pressure decrease was not explained by improvements in adherence following the procedure. Patients not responding to treatment significantly reduced their drug intake following the procedure. Adherence was highest for angiotensin-converting enzyme inhibitors/angiotensin receptor blockers and beta blockers (>90 %) and lowest for vasodilators (21 %). In conclusion, renal denervation can reduce office and ambulatory blood pressure in patients with resistant hypertension despite a significant reduction in adherence to antihypertensive treatment after 6 months.

  15. Ethnic differences in intraocular pressure reduction and changes in anterior segment biometric parameters following cataract surgery by phacoemulsification.

    PubMed

    Lee, Roland Y; Kasuga, Toshimitsu; Cui, Qi N; Huang, Guofu; Wang, Sophia Y; Lin, Shan C

    2013-07-01

    To determine the association between ethnicity and changes in intraocular pressure and anterior segment biometric parameters following cataract surgery by phacoemulsification in nonglaucomatous subjects. Prospective clinical cohort study. Caucasian and Asian subjects. Customized software was used to calculate parameters from anterior segment optical coherence tomography images obtained preoperatively and at 3 months following cataract surgery by phacoemulsification. The percentage changes in intraocular pressure and anterior segment biometric parameters following cataract surgery by phacoemulsification were modelled as a function of ethnicity using linear mixed-effects regression, a likelihood ratio test function that adjusted for age, sex and the use of both eyes in the same subject, to determine the association between ethnicity and postoperative outcomes. Intraocular pressure, angle opening distance, anterior chamber depth, anterior chamber volume, and angle recess area. Fifty Asian and 23 Caucasian nonglaucomatous eyes were analysed. Postoperative decrease in intraocular pressure and increases in angle opening distance, anterior chamber depth, anterior chamber volume and angle recess area were observed within each ethnic group (P < 0.005). The percent changes in intraocular pressure, angle opening distance, anterior chamber depth, anterior chamber volume and angle recess area did not differ between ethnic groups (P > 0.05). In this study, regardless of ethnic classification, subjects who received cataract surgery by phacoemulsification experienced a significant postoperative decrease in intraocular pressure and increases in angle opening distance, anterior chamber depth, anterior chamber volume and angle recess area. The percent changes in postoperative outcomes did not differ significantly by ethnicity. © 2012 The Authors. Clinical and Experimental Ophthalmology © 2012 Royal Australian and New Zealand College of Ophthalmologists.

  16. Acute but not chronic metabolic acidosis potentiates the acetylcholine-induced reduction in blood pressure: an endothelium-dependent effect.

    PubMed

    Celotto, A C; Ferreira, L G; Capellini, V K; Albuquerque, A A S; Rodrigues, A J; Evora, P R B

    2016-02-01

    Metabolic acidosis has profound effects on vascular tone. This study investigated the in vivo effects of acute metabolic acidosis (AMA) and chronic metabolic acidosis (CMA) on hemodynamic parameters and endothelial function. CMA was induced by ad libitum intake of 1% NH4Cl for 7 days, and AMA was induced by a 3-h infusion of 6 M NH4Cl (1 mL/kg, diluted 1:10). Phenylephrine (Phe) and acetylcholine (Ach) dose-response curves were performed by venous infusion with simultaneous venous and arterial blood pressure monitoring. Plasma nitrite/nitrate (NOx) was measured by chemiluminescence. The CMA group had a blood pH of 7.15±0.03, which was associated with reduced bicarbonate (13.8±0.98 mmol/L) and no change in the partial pressure of arterial carbon dioxide (PaCO2). The AMA group had a pH of 7.20±0.01, which was associated with decreases in bicarbonate (10.8±0.54 mmol/L) and PaCO2 (47.8±2.54 to 23.2±0.74 mmHg) and accompanied by hyperventilation. Phe or ACh infusion did not affect arterial or venous blood pressure in the CMA group. However, the ACh infusion decreased the arterial blood pressure (ΔBP: -28.0±2.35 mm Hg [AMA] to -4.5±2.89 mmHg [control]) in the AMA group. Plasma NOx was normal after CMA but increased after AMA (25.3±0.88 to 31.3±0.54 μM). These results indicate that AMA, but not CMA, potentiated the Ach-induced decrease in blood pressure and led to an increase in plasma NOx, reinforcing the effect of pH imbalance on vascular tone and blood pressure control.

  17. Development of a compositional model fully coupled with geomechanics and its application to tight oil reservoir simulation

    NASA Astrophysics Data System (ADS)

    Xiong, Yi

    solutions and results of a commercial simulator before conducting numerical studies. The numerical studies demonstrate the effect of capillary pressure on VLE, and further on production performance. The significant effect of capillary pressure on VLE leads to the suppression of bubble-point pressure and more light components dissolved in the oil phase. Consequently it is observed that there is smaller gas saturation, larger mole fractions of light components, and faster pressure decreasing at reservoir conditions; meanwhile less gas and more oil are produced at surface. The substantial decrease in reservoir pore pressure results in a large increase of effective stress, which induces the changes of rock properties and influences the production performance. The stress-induced degradation of permeability undermines the production performance, and the geomechanical effect on the permeability of natural fractures is mainly responsible for the undermined production performance. The reduction of pore size due to the geomechanical effect could increase the capillary pressure, which enlarges the influence of capillarity on VLE and further suppresses bubble-point pressure. On the other hand, the effect of capillary pressure on VLE influences the fluid flow and therefore influences the effective stress through the flow-stress coupling process. Thus the interaction between pore confinement and rock compaction can be modeled with MSFLOW_COM, and illustrated through numerical studies. This research provides a three-dimensional numerical tool for accurately modeling porous and fractured tight oil reservoirs. The developed simulator is able to assist scientists and engineers to study and understand the complex multiphase, multi-component fluid flow behaviors in tight oil reservoirs.

  18. Intra-aneurysmal hemodynamic alterations by a self-expandable intracranial stent and flow diversion stent: high intra-aneurysmal pressure remains regardless of flow velocity reduction.

    PubMed

    Shobayashi, Yasuhiro; Tateshima, Satoshi; Kakizaki, Ryuichi; Sudo, Ryo; Tanishita, Kazuo; Viñuela, Fernando

    2013-11-01

    Little is known about how much protection a flow diversion stent provides to a non-thrombosed aneurysm without the adjunctive use of coils. A three-dimensional anatomically realistic computation aneurysm model was created from the digital subtraction angiogram of a large internal carotid artery-ophthalmic artery aneurysm which could have been treated with either a neck bridging stent or a flow diversion stent. Three-dimensional computational models of the Neuroform EZ neck bridging stent and Pipeline embolization device were created based on measurements with a stereo-microscope. Each stent was placed in the computational aneurysm model and intra-aneurysmal flow structures were compared before and after placement of the stents. Computational fluid dynamics were performed by numerically solving the continuity and Navier-Stokes momentum equations for a steady blood flow based on the finite volume method. Blood was assumed as an incompressible Newtonian fluid. Vessel walls were assumed to be rigid, and no-slip boundary conditions were applied at the lumens. To estimate the change in the intra-aneurysmal pressures we assumed that, at the inlets, the intra-arterial pressure at peak systole was 120 mm Hg both before and after stent placement Without any stent, the blood flow entered into the aneurysm dome from the mid to proximal neck area and ascended along the distal wall of the aneurysm. The flow then changed its direction anteriorly and moved along the proximal wall of the aneurysm dome. In addition to the primary intra-aneurysmal circulation pattern, a counterclockwise vortex was observed in the aneurysm dome. The placement of a Neuroform EZ stent induced a mean reduction in flow velocity of 14% and a small change in the overall intra-aneurysmal flow pattern. The placement of a Pipeline device induced a mean reduction in flow velocity of 74% and a significant change in flow pattern. Despite the flow velocity changes, Neuroform EZ and Pipeline devices induced

  19. Reservoir Souring - latest developments for application and mitigation.

    PubMed

    Johnson, Richard J; Folwell, Benjamin D; Wirekoh, Alexander; Frenzel, Max; Skovhus, Torben Lund

    2017-04-08

    Sulphate-reducing prokaryotes (SRP) have been identified in oil field fluids since the 1920s. SRP reduce sulphate to sulphide, a toxic and corrosive species that impacts on operational safety, metallurgy and both capital and operational cost. Differences in water cut, temperature, pressure and fluid chemistry can impact on the observed H2S concentration, meaning that an increase in H2S concentration does not always correlate with activity of SRP. However it wasn't until the 1990s that SRP activity was accepted as the leading cause of reservoir souring (i.e. an increase in H2S concentrations) in water flooded fields. The process of sulphate-reduction has been well documented at the genetic, enzymatic and physiological level in pure cultures under laboratory conditions. DNA sequencing has also identified new groups of microorganisms, such as archaea which are capable of contributing to reservoir souring. This has led to some recent advances in microbial control and detection, however, despite this, many of the methods used routinely for microbial control and detection are over a century old. We therefore look towards emerging and novel mitigation technologies that may be used in mitigating against reservoir souring, along with tried and tested methods Modelling and prediction is another important but often under-used tool in managing microbial reservoir souring. To be truly predictive, models need to take into account not only microbial H2S generation but also partitioning and mineral scavenging. The increase in 'big data' available through increased integration of sensors in the digital oil field and the increase in the DNA sequencing capabilities through next-generation sequencing (NGS) therefore offer a unique opportunity to develop and refine microbial reservoir souring models. We therefore review a number of different reservoir souring models and identify how these can be used in the future. With this comprehensive overview of the current and emerging

  20. Modelling the impact of water activity and fat content of dry-cured ham on the reduction of Salmonella enterica by high pressure processing.

    PubMed

    Bover-Cid, S; Belletti, N; Aymerich, T; Garriga, M

    2017-01-01

    This work aimed to quantify the impact of aw and fat content of dry-cured ham on the Log reduction of Salmonella enterica by high pressure (HP). Dry-cured ham with adjusted aw (0.86-0.96) and fat content (10-50%) was inoculated with S. enterica and pressurised (347-852MPa, 5min/15°C), following a Central Composite Design. Polynomial regression indicated a significant impact of pressure and aw on S. enterica HP-lethality. By lowering aw a clear piezoprotection was observed. At low aw (0.88) the S. enterica reduction was little affected by increasing pressure (e.g. 2.3 to 3.2 Logs at 450 to 750MPa, respectively). At the highest aw the estimated inactivation ranged from 3.3 to 8.9 Logs at 450 to 750MPa, respectively. No significant piezoprotective effect on S. enterica was recorded by the fat content. The relevance of food characteristics on the HP-lethality of S. enterica indicate the need to validate the HP effectiveness on the specific product. Copyright © 2016 Elsevier Ltd. All rights reserved.

  1. The Impact of Azilsartan Medoxomil Treatment (Capsule Formulation) at Doses Ranging From 10 to 80 mg: Significant, Rapid Reductions in Clinic Diastolic and Systolic Blood Pressure.

    PubMed

    Perez, Alfonso; Cao, Charlie

    2017-03-01

    In this phase 2, multicenter, parallel-group, double-blind, dose-ranging study, hypertensive adults (n=449) were randomized to receive one of five doses of a capsule formulation of azilsartan medoxomil (AZL-M; 5, 10, 20, 40, 80 mg), olmesartan medoxomil (OLM) 20 mg, or placebo once daily. The primary endpoint was change in trough clinic diastolic blood pressure (DBP) at week 8. AZL-M provided rapid statistically and clinically significant reductions in DBP and systolic blood pressure (SBP) vs placebo at all doses except 5 mg. Placebo-subtracted changes were greatest with the 40 mg dose (DBP, -5.7 mm Hg; SBP, -12.3 mm Hg). Clinic changes with AZL-M (all doses) were statistically indistinguishable vs OLM, although there were greater reductions with AZL-M 40 mg using 24-hour ambulatory blood pressure. Adverse event frequency was similar in the AZL-M and placebo groups. Based on these and other findings, subsequent trials investigated the commercial AZL-M tablet in the dose range of 20 to 80 mg/d. ©2016 Wiley Periodicals, Inc.

  2. Biogeochemical mass balances in a turbid tropical reservoir. Field data and modelling approach

    NASA Astrophysics Data System (ADS)

    Phuong Doan, Thuy Kim; Némery, Julien; Gratiot, Nicolas; Schmid, Martin

    2014-05-01

    entire mass balance of nutrients and of the mineralization rates (denitrification and aerobic benthic mineralization) calculated from the model fitted well to the field measurements. Furthermore, this analysis indicates that the benthic mineralizations are the dominant processes involved in the nutrients release. This is the first implementation of a biogeochemical model applied to a highly productive reservoir in the TMVB in order to estimate nutrients release from sediments. It could be used for scenarios of reduction of eutrophication in the reservoir. This study provides a good example of the behavior of a small tropical reservoir under intense human pressure and it will help stakeholders to adopt appropriate strategies for the management of turbid tropical reservoirs.

  3. Understanding Microbial Reservoir Souring and Desouring Processes Using Reactive Transport Modeling

    NASA Astrophysics Data System (ADS)

    Cheng, Y.; Bouskill, N.; Hubbard, C. G.; Hubbard, S. S.; Ajo Franklin, J. B.; Li, L.; Engelbrektson, A. L.; Coates, J. D.; Surasani, V.

    2013-12-01

    Microbial sulfate reduction is the major metabolic process that leads to oil reservoir souring. Souring typically occurs when (sea)water is injected into the oil reservoir to maintain pressure and sweep remnant oil through the reservoir. Because biogenesis of hydrogen sulfide has detrimental impacts on oil production operations and can cause significant environmental and health problems, we strive to develop predictive understanding of reservoir souring and associated mitigation processes. Recent laboratory sediment column experiments have demonstrated the effectiveness of nitrate, chlorate and perchlorate treatments as souring control strategies. In this study, we describe the development of a reactive transport model that is based on the reaction mechanisms and kinetics revealed through the column experimental data. The model was used to simulate the temporal and spatial evolution of the primary chemical species (e.g. sulfate, sulfide, nitrate, chlorate and perchlorate) and the microbial dynamics involved in the souring and desouring processes. The growth and inhibition dynamics of the sulfate reducing bacterial population are explicitly simulated and constrained by energetics. Simulation of the laboratory experimental results show that the model captured the spatio-temporal trend of the chemical species and microbial guilds during both souring and desouring. Ongoing research is focusing on extending the reactive transport model to mechanistically understand, quantify, and predict souring and desouring processes within heterogeneous reservoirs as a step toward optimizing field scale souring control strategies.

  4. Large reservoirs: Chapter 17

    USGS Publications Warehouse

    Miranda, Leandro E.; Bettoli, Phillip William

    2010-01-01

    Large impoundments, defined as those with surface area of 200 ha or greater, are relatively new aquatic ecosystems in the global landscape. They represent important economic and environmental resources that provide benefits such as flood control, hydropower generation, navigation, water supply, commercial and recreational fisheries, and various other recreational and esthetic values. Construction of large impoundments was initially driven by economic needs, and ecological consequences received little consideration. However, in recent decades environmental issues have come to the forefront. In the closing decades of the 20th century societal values began to shift, especially in the developed world. Society is no longer willing to accept environmental damage as an inevitable consequence of human development, and it is now recognized that continued environmental degradation is unsustainable. Consequently, construction of large reservoirs has virtually stopped in North America. Nevertheless, in other parts of the world construction of large reservoirs continues. The emergence of systematic reservoir management in the early 20th century was guided by concepts developed for natural lakes (Miranda 1996). However, we now recognize that reservoirs are different and that reservoirs are not independent aquatic systems inasmuch as they are connected to upstream rivers and streams, the downstream river, other reservoirs in the basin, and the watershed. Reservoir systems exhibit longitudinal patterns both within and among reservoirs. Reservoirs are typically arranged sequentially as elements of an interacting network, filter water collected throughout their watersheds, and form a mosaic of predictable patterns. Traditional approaches to fisheries management such as stocking, regulating harvest, and in-lake habitat management do not always produce desired effects in reservoirs. As a result, managers may expend resources with little benefit to either fish or fishing. Some locally

  5. IMPROVING CO2 EFFICIENCY FOR RECOVERING OIL IN HETEROGENEOUS RESERVOIRS

    SciTech Connect

    Reid B. Grigg

    2003-10-31

    The second annual report of ''Improving CO{sub 2} Efficiency for Recovery Oil in Heterogeneous Reservoirs'' presents results of laboratory studies with related analytical models for improved oil recovery. All studies have been undertaken with the intention to optimize utilization and extend the practice of CO{sub 2} flooding to a wider range of reservoirs. Many items presented in this report are applicable to other interest areas: e.g. gas injection and production, greenhouse gas sequestration, chemical flooding, reservoir damage, etc. Major areas of studies include reduction of CO{sub 2} mobility to improve conformance, determining and understanding injectivity changes in particular injectivity loses, and modeling process mechanisms determined in the first two areas. Interfacial tension (IFT) between a high-pressure, high-temperature CO{sub 2} and brine/surfactant and foam stability are used to assess and screen surfactant systems. In this work the effects of salinity, pressure, temperature, surfactant concentration, and the presence of oil on IFT and CO{sub 2} foam stability were determined on the surfactant (CD1045{trademark}). Temperature, pressure, and surfactant concentration effected both IFT and foam stability while oil destabilized the foam, but did not destroy it. Calcium lignosulfonate (CLS) can be used as a sacrificial and an enhancing agent. This work indicates that on Berea sandstone CLS concentration, brine salinity, and temperature are dominant affects on both adsorption and desorption and that adsorption is not totally reversible. Additionally, CLS adsorption was tested on five minerals common to oil reservoirs; it was found that CLS concentration, salinity, temperature, and mineral type had significant effects on adsorption. The adsorption density from most to least was: bentonite > kaolinite > dolomite > calcite > silica. This work demonstrates the extent of dissolution and precipitation from co-injection of CO{sub 2} and brine in limestone core

  6. Prognostic Significance of Hyponatremia in Acute Intracerebral Hemorrhage: Pooled Analysis of the Intensive Blood Pressure Reduction in Acute Cerebral Hemorrhage Trial Studies.

    PubMed

    Carcel, Cheryl; Sato, Shoichiro; Zheng, Danni; Heeley, Emma; Arima, Hisatomi; Yang, Jie; Wu, Guojun; Chen, Guofang; Zhang, Shihong; Delcourt, Candice; Lavados, Pablo; Robinson, Thompson; Lindley, Richard I; Wang, Xia; Chalmers, John; Anderson, Craig S

    2016-07-01

    To determine the association of hyponatremia at presentation with clinical and imaging outcomes in patients with acute intracerebral hemorrhage. Retrospective pooled analysis of prospectively collected data from 3,243 participants of the pilot and main phases of the Intensive Blood Pressure Reduction in Acute Cerebral Hemorrhage Trials 1 and 2 (international, multicenter, open, blinded endpoint, randomized controlled trials designed to assess the effects of early intensive blood pressure lowering in patients with acute intracerebral hemorrhage). Clinical hospital sites in 21 countries. Patients with predominantly mild-moderate severity of spontaneous intracerebral hemorrhage within 6 hours of onset and elevated systolic blood pressure (150-220 mm Hg) were included in the study. Patients were assigned to receive intensive (target systolic blood pressure, < 140 mm Hg within 1 hr) or guideline-recommended (target systolic blood pressure, < 180 mm Hg) blood pressure-lowering therapy. Presentation hyponatremia was defined as serum sodium less than 135 mEq/L. The primary outcome was death at 90 days. Multivariable logistic regression was used to assess the association of hyponatremia with important clinical events. Of 3,002 patients with available data, 349 (12%) had hyponatremia. Hyponatremia was associated with death (18% vs 11%; multivariable-adjusted odds ratio, 1.81; 95% CI, 1.28-2.57; p < 0.001) and larger baseline intracerebral hemorrhage volume (multivariable adjusted, p = 0.046) but not with baseline perihematomal edema volume nor with growth of intracerebral hemorrhage or perihematomal edema during the initial 24 hours. Hyponatremia at presentation is associated with increased mortality in patients with predominantly deep and modest volume intracerebral hemorrhage through mechanisms that seem independent of growth in intracerebral hemorrhage or perihematomal edema.

  7. Larger Blood Pressure Reduction by Fixed-Dose Compared to Free Dose Combination Therapy of ACE Inhibitor and Calcium Antagonist in Hypertensive Patients.

    PubMed

    Visco, Valeria; Finelli, Rosa; Pascale, Antonietta Valeria; Giannotti, Rocco; Fabbricatore, Davide; Ragosa, Nicola; Ciccarelli, Michele; Iaccarino, Guido

    2017-01-01

    The introduction of fixed combination of ACEi+CCB (Fixed) has significantly increased patients compliance and adherence to therapy. At the moment, however, there are no data suggesting the better control of once-daily fixed (Fixed) over free doses in separate administrations combination therapy in hypertensives. In a population of 39 consecutive outpatient patients referred to the departmental Hypertension clinic of the University Hospital of Salerno Medical School with the first diagnosis of arterial hypertension, we tested the hypothesis that the Fixed achieve a better control of blood pressure than the Free combination. Patients were randomized to either strategy and after 3 months patients underwent a clinical assessment to evaluate the antihypertensive effect. The two groups, matched for anthropometric and clinical parameters, received Amlodipine (5-10 mg/daily) and Perindopril (5-10 mg/daily). Perindopril and Amlodipine doses did not significantly differ between the two groups. After 3 months BP control was improved in both groups and BP targets were similarly reached in both groups (SBP; Fixed: 61.54%; Free 69.23%; n.s. DPB; Fixed: 80.77%; Free 84.62%; n.s.). The reduction in systolic blood pressure was similar in both groups (Fixed:7.64±2.49%; Free: 7.81±4.00%, n.s.), while the reduction of diastolic blood pressure was greater in the Fixed group (Fixed: 14.22±2.03%; Free: 4.92±5.00%, p<0.05). Although both strategies are effective in reducing BP, the use of Fixed dose has an advantage in the reduction of BP. The present study does not allow to identify the mechanisms of this difference, which can be assumed to be due to the pharmacokinetics of the drugs administered in once-daily fixed combination.

  8. COSTING MODELS FOR WATER SUPPLY DISTRIBUTION: PART III- PUMPS, TANKS, AND RESERVOIRS

    EPA Science Inventory

    Distribution systems are generally designed to ensure hydraulic reliability. Storage tanks, reservoirs and pumps are critical in maintaining this reliability. Although storage tanks, reservoirs and pumps are necessary for maintaining adequate pressure, they may also have a negati...

  9. Implementation of pressurized air injection system in a Kaplan prototype for the reduction of vibration caused by tip vortex cavitation

    NASA Astrophysics Data System (ADS)

    Rivetti, A.; Angulo, M.; Lucino, C.; Hene, M.; Capezio, O.; Liscia, S.

    2016-11-01

    Blade tip cavitation is a well-known phenomenon that affects the performance of large-diameter Kaplan turbines and induces structural vibration. Injection of pressurized air has been found to yield promising results in reducing those damaging effects. In this work, the results of an experimental test of air injection on a 9.5-m-diameter Kaplan turbine are reported. Experiments were performed for several load conditions and for two different net heads. Accelerations, pressure pulsation and noise emission were monitored for every tested condition. Results show that, at the expense of a maximum efficiency drop of 0.2%, air injection induces a decrease on the level of vibration from 57% up to 84%, depending on the load condition. Such decrease is seen to be proportional to the air flow rate, in the range from 0.06 to 0.8‰ (respect to the discharge at the best efficiency point).

  10. Defect reduction in photon-accelerated negative bias instability of InGaZnO thin-film transistors by high-pressure water vapor annealing

    NASA Astrophysics Data System (ADS)

    Seung Rim, You; Jeong, Wooho; Du Ahn, Byung; Jae Kim, Hyun

    2013-04-01

    We investigated the effects of high-pressure water vapor annealing (WHPA) under negative bias temperature illumination stress and light incidence on amorphous InGaZnO thin-film transistors. WHPA could improve device reliability and reduce the hump occurrence. It was attributed to the effective reduction and passivation in oxygen vacancies under WHPA. By comparing the experimental and technology computer-aided design simulation, we could confirm that the low-density of deep-donor-like oxygen vacancy (Vo) states near the valance band maximum contributed to the reduction of photo-excited single ionized oxygen vacancies (Vo+) and double ionized oxygen vacancies (Vo2+) as shallow-donor states near the conduction band minimum.

  11. Olive oil-induced reduction of oxidative damage and inflammation promotes wound healing of pressure ulcers in mice.

    PubMed

    Donato-Trancoso, Aline; Monte-Alto-Costa, Andréa; Romana-Souza, Bruna

    2016-07-01

    The overproduction of reactive oxygen species (ROS) and exacerbated inflammatory response are the main events that impair healing of pressure ulcers. Therefore, olive oil may be a good alternative to improve the healing of these chronic lesions due to its anti-inflammatory and antioxidant properties. This study investigated the effect of olive oil administration on wound healing of pressure ulcers in mice. Male Swiss mice were daily treated with olive oil or water until euthanasia. One day after the beginning of treatment, two cycles of ischemia-reperfusion by external application of two magnetic plates were performed in skin to induced pressure ulcer formation. The olive oil administration accelerated ROS and nitric oxide (NO) synthesis and reduced oxidative damage in proteins and lipids when compared to water group. The inflammatory cell infiltration, gene tumor necrosis factor-α (TNF-α) expression and protein neutrophil elastase expression were reduced by olive oil administration when compared to water group. The re-epithelialization and blood vessel number were higher in the olive oil group than in the water group. The olive oil administration accelerated protein expression of TNF-α, active transforming growth factor-β1 and vascular endothelial growth factor-A when compared to water group. The collagen deposition, myofibroblastic differentiation and wound contraction were accelerated by olive oil administration when compared to water group. Olive oil administration improves cutaneous wound healing of pressure ulcers in mice through the acceleration of the ROS and NO synthesis, which reduces oxidative damage and inflammation and promotes dermal reconstruction and wound closure. Copyright © 2016 Japanese Society for Investigative Dermatology. Published by Elsevier Ireland Ltd. All rights reserved.

  12. Stream, Lake, and Reservoir Management.

    PubMed

    Dai, Jingjing; Mei, Ying; Chang, Chein-Chi

    2017-10-01

    This review on stream, lake, and reservoir management covers selected 2016 publications on the focus of the following sections: Stream, lake, and reservoir management • Water quality of stream, lake, and reservoirReservoir operations • Models of stream, lake, and reservoir • Remediation and restoration of stream, lake, and reservoir • Biota of stream, lake, and reservoir • Climate effect of stream, lake, and reservoir.

  13. FRACTURED PETROLEUM RESERVOIRS

    SciTech Connect

    Abbas Firoozabadi

    1999-06-11

    different from that of gas displacement processes. The work is of experimental nature and clarifies several misconceptions in the literature. Based on experimental results, it is established that the main reason for high efficiency of solution gas drive from heavy oil reservoirs is due to low gas mobility. Chapter III presents the concept of the alteration of porous media wettability from liquid-wetting to intermediate gas-wetting. The idea is novel and has not been introduced in the petroleum literature before. There are significant implications from such as proposal. The most direct application of intermediate gas wetting is wettability alteration around the wellbore. Such an alteration can significantly improve well deliverability in gas condensate reservoirs where gas well deliverability decreases below dewpoint pressure. Part I of Chapter III studies the effect of gravity, viscous forces, interfacial tension, and wettability on the critical condensate saturation and relative permeability of gas condensate systems. A simple phenomenological network model is used for this study, The theoretical results reveal that wettability significantly affects both the critical gas saturation and gas relative permeability. Gas relative permeability may increase ten times as contact angle is altered from 0{sup o} (strongly liquid wet) to 85{sup o} (intermediate gas-wetting). The results from the theoretical study motivated the experimental investigation described in Part II. In Part II we demonstrate that the wettability of porous media can be altered from liquid-wetting to gas-wetting. This part describes our attempt to find appropriate chemicals for wettability alteration of various substrates including rock matrix. Chapter IV provides a comprehensive treatment of molecular, pressure, and thermal diffusion and convection in porous media Basic theoretical analysis is presented using irreversible thermodynamics.

  14. Fully coupled analysis of reservoir compaction and subsidence

    SciTech Connect

    Gutierrez, M.; Hansteen, H.

    1994-12-31

    This paper discusses the differences between fully-coupled and uncoupled formulations of models of production and subsidence. For highly compacting hydrocarbon reservoirs, production can cause compaction of the reservoir and subsidence of the overburden, and in turn, compaction and subsidence can affect the productivity of the reservoir by increasing the reservoir pressure. Intuitively, analyses of production and subsidence should be done in a fully-coupled fashion. However, most, if not all, of the analyses done so far on compacting reservoirs are uncoupled where production and subsidence are calculated in a staggered manner. The results of the numerical analyses using an uncoupled reservoir simulation, and a fully-coupled finite element simulation based on Biot`s formulation of a typical compacting reservoir are presented and compared. Different pore pressure response were obtained depending on whether an uncoupled or a fully-coupled analysis was performed, and also depending on whether there is arching of the overburden or not. The results of fully-coupled analyses of compaction and subsidence showed that the generation of additional pore pressure due to compaction cannot be correctly analyzed by simply adjusting the rock compressibilities in reservoir simulation. The most pronounced effect of coupling, obtained from the numerical simulations, is on the possibility of pore pressure increase close to the reservoir flanks even during production. The implications of the differences in the results of fully-coupled and uncoupled simulations are discussed.

  15. Reduction of mosquito biting-pressure: spatial repellents or mosquito traps? A field comparison of seven commercially available products in Israel.

    PubMed

    Revay, Edita E; Kline, Daniel L; Xue, Rui-De; Qualls, Whitney A; Bernier, Ulrich R; Kravchenko, Vasiliy D; Ghattas, Nina; Pstygo, Irina; Müller, Günter C

    2013-07-01

    The present study assessed the personal protection efficiency of seven commercially available mosquito control devices (MCD) under field conditions in Israel. Trials were performed in a high biting-pressure area inhabited by large populations of mosquito and biting midge species, using human volunteers as bait in landing catch experiments. Results show that under minimal air-movement, three spatial repellent based products (ThermaCELL(®) Patio Lantern, OFF!(®) PowerPad lamp, and Terminix(®) ALLCLEAR Tabletop Mosquito Repeller) significantly reduced the biting-pressure (t-test - P<0.01) when positioned at short distances from a volunteer (3, 7.5, and 10ft.), with the ThermaCELL unit being most effective (96.1, 89.9, and 76.66% reduction, respectively). No significant differences were seen between the three aforementioned devices at distances of 3 and 7.5ft., while at a distance of 10ft., only the ThermaCELL patio lantern repelled significantly more mosquitoes then the Terminix ALLCLEAR Tabletop Mosquito Repeller (t-test, P<0.05). In contrast, mosquito traps using attracting cues to bait mosquitoes (Dynatrap(®), Vortex(®) Electronic Insect Trap, Blue Rhino(®) SV3100) either significantly increased or had no effect on the biting-pressure at short distances compared with the unprotected control. Trials conducted over large areas showed that only the Blue Rhino trap was able to significantly reduce the biting-pressure (40.1% reduction), but this was only when operating four units at the corners of an intermediate sized area. Copyright © 2013 Elsevier B.V. All rights reserved.

  16. Quantification of geologic descriptions for reservoir characterization in carbonate reservoirs

    SciTech Connect

    Lucia, F.J.; Vander Stoep, G.W. )

    1990-05-01

    Recognition that a large volume of oil remains in carbonate reservoirs at the end of primary depletion and waterflooding has prompted the reevaluation of the reserve-growth potential of many existing carbonate reservoirs. Types of numerical data required include porosity, absolute permeability, relative permeability, fluid saturation, and capillary pressure, all of which are related to the size and distribution of pore space. Rock fabrics control the size and distribution of pore space and define facies that best characterize carbonate reservoirs. Thus, the link between facies descriptions and numerical engineering data is the relationship between pore-size distribution and present carbonate rock fabric. The most effective way to convert facies descriptions into engineering parameters is by considering three basic rock-fabric categories. The first category is interparticle pore space (both intergranular and intercrystalline pore types) with pore-size distribution controlled primarily by the size and shape of grains or crystals. Grain or crystal size is the key geologic measurement and, along with porosity, provides the basis for converting geologic descriptions into values for permeability, saturation, and capillarity. The second category is separate-vug pore space, such as moldic or intraparticle pore space. Separate-vug pore space adds porosity but little permeability to the reservoir rock. The contribution to saturation and capillarity depends upon the size of the separate-vug pore space. For example, moldic separate vugs will be saturated with oil, whereas microporous grains will be saturated with water. The third category is touching-vug pore space, which is vuggy pore space that is interconnected on a reservoir scale. The engineering parameters for this category are related to three diagenetic and tectonic factors.

  17. Status of Cherokee Reservoir

    SciTech Connect

    Not Available

    1990-08-01

    This is the first in a series of reports prepared by Tennessee Valley Authority (TVA) for those interested in the conditions of TVA reservoirs. This overviews of Cherokee Reservoir summarizes reservoir and watershed characteristics, reservoir uses and use impairments, water quality and aquatic biological conditions, and activities of reservoir management agencies. This information was extracted from the most current reports, publications, and data available, and interviews with water resource professionals in various Federal, state, and local agencies and in public and private water supply and wastewater treatment facilities. 11 refs., 4 figs., 1 tab.

  18. Status of Wheeler Reservoir

    SciTech Connect

    Not Available

    1990-09-01

    This is one in a series of status reports prepared by the Tennessee Valley Authority (TVA) for those interested in the conditions of TVA reservoirs. This overview of Wheeler Reservoir summarizes reservoir purposes and operation, reservoir and watershed characteristics, reservoir uses and use impairments, and water quality and aquatic biological conditions. The information presented here is from the most recent reports, publications, and original data available. If no recent data were available, historical data were summarized. If data were completely lacking, environmental professionals with special knowledge of the resource were interviewed. 12 refs., 2 figs.

  19. [Pressure reduction after selective laser trabeculoplasty with two different laser systems and after argon laser trabeculoplasty--a controlled prospective clinical trial on 284 eyes].

    PubMed

    Best, U-P; Domack, H; Schmidt, V

    2007-03-01

    Selective laser trabeculoplasty (SLT) is a new method to reduce intraocular pressure in eyes with primary open angle glaucoma. The laser parameters of a Q-switched, frequency-doubled Nd:YAG-laser are set to selectively target pigmented trabecular meshwork cells without visible damage to the adjacent non-pigmented tissue. SLT acts non-thermally, the intracellular microdisruptions triggered by the laser are confined to the targeted cells, the laser pulses are so short that heat caused within the targeted cells does not have time to spread to the surrounding tissue. A controlled prospective randomised clinical study was conducted to compare the long-term results, safety and efficacy after SLT with two different laser systems and after ALT in the treatment of ocular hypertension and medically uncontrolled open angle glaucoma. About two years ago the authors performed a selective laser trabeculoplasty in 119 eyes using the SLT laser unit Otello (Glautec AG, ARC, EC), here named as SLT-I, and in 124 eyes using the SLT laser unit Selecta II (Lumenis, Palo Alto, CA), here named as SLT-II. In 41 eyes the authors performed argon laser trabeculoplasties using the argon laser Argus (Aesculap Meditec, EC). Two months after treatment mean IOP reduction from baseline was 1.9 mmHg or, respectively, 8.8 % after SLT with the SLT-System I, 2.0 mmHg or, respectively, 9.5 % after SLT with SLT-System II, and 2.2 mmHg or, respectively, 9.9 % after ALT with the argon laser. Twelve months after LTP mean pressure reductions were 1.7 mmHg (7.9 %) after SLT-I, 1.8 mmHg (8.5 %) after SLT-II, and 2.1 mmHg (9.4 %) after ALT. The response curve of the eyes with SLT-I greatly resembled that of the eyes with SLT-II and those eyes with ALT. Pressure reduction was highest after ALT, followed by SLT-II, in SLT-I reduction was the least, but the differences were not significant. Our findings did not correspond with those of other authors reporting an average IOP reduction of 25 % after SLT and ALT. SLT

  20. Producing Light Oil from a Frozen Reservoir: Reservoir and Fluid Characterization of Umiat Field, National Petroleum Reserve, Alaska

    SciTech Connect

    Hanks, Catherine

    2012-12-31

    compared to theoretical Umiat composition derived using the Pedersen method with original Umiat fluid properties published in the original reports. This comparison allowed estimation of the ‘lost’ light hydrocarbon fractions. An Umiat 'dead' oil sample then could be physically created by adding the lost light ends to the weatherized Umiat dead oil sample. This recreated sample was recombined with solution gas to create a 'pseudo-live' Umiat oil sample which was then used for experimental PVT and phase behavior studies to determine fluid properties over the range of reservoir pressures and temperatures. The phase behavior of the ‘pseudo-live’ oil was also simulated using the Peng- Robinson equations of state (EOS). The EOS model was tuned with measured experimental data to accurately simulate the differential liberation tests in order to obtain the necessary data for reservoir simulation studies, including bubble point pressure and oil viscosity. The bubble point pressure of the reconstructed Umiat oil is 345 psi, suggesting that maintenance of reservoir pressures above that pressure will be important for the any proposed production technique. A major part of predicting how the Umiat reservoir will perform is determining the relative permeability of oil in the presence of ice. Early in the project, UAF work on samples of the Umiat reservoir indicated that there is a significant reduction in the relatively permeability of oil in the presence of ice. However, it was not clear as to why this reduction occurred or where the ice resided. To explore this further, additional experimental and theoretical work was conducted. Core flood experiments were performed on two clean Berea sandstone cores under permafrost conditions to determine the relative permeability to oil (kro) over a temperature range of 23ºC to - 10ºC and for a range of connate water salinities. Both cores showed maximum reduction in relative permeability to oil when saturated with deionized water and less

  1. Reduction Of Chronic Musculoskeletal Pain With Cranial Laser Reflex Technique (CLRT): A Randomized Controlled Trial Using Pressure Algometry

    SciTech Connect

    Wise, Nicholas A. D.C.

    2010-05-31

    Cranial Laser Reflex Technique (CLRT) is a novel method involving a brief low level laser stimulation of specific cranial reflex points to reduce musculoskeletal pain. Objective: The objective of the study was to compare the immediate effects of CLRT with a sham treatment on chronic musculoskeletal pain using pressure algometry in a double-blinded randomized controlled trial. Methods: Fifty-seven (57) volunteers with various musculoskeletal pains gave informed consent and were randomly allocated to either the CLRT treatment or sham group. Painful trigger points and/or tender spinal joints were found in each patient. Using a digital algometer, the pain/pressure threshold (PPT) was determined and a pain rating was given using a numerical pain scale from 0-10. CLRT or a sham treatment was performed with a 50 mW, 840 nm laser, for a maximum of 20 seconds to the each cranial reflex. The initial pressure (PPT) was immediately delivered to the same spot, and the pain rated again. Results: There was a statistically significant difference in pain scores between CLRT and sham groups immediately following treatment. Improvement was reported in 95% of the treatment group, with 59% reporting an improvement of 2 points or greater. The average change in pain scores in the treatment group was 2.6 points (p 0.000) versus negligible change (p= 0.4) for the control group. Conclusion: The results show that CLRT is effective at immediately reducing chronic musculoskeletal pain. Further studies are needed with additional outcome measures to.

  2. Reduction Of Chronic Musculoskeletal Pain With Cranial Laser Reflex Technique (CLRT): A Randomized Controlled Trial Using Pressure Algometry

    NASA Astrophysics Data System (ADS)

    Wise, Nicholas A.

    2010-05-01

    Cranial Laser Reflex Technique (CLRT) is a novel method involving a brief low level laser stimulation of specific cranial reflex points to reduce musculoskeletal pain. Objective: The objective of the study was to compare the immediate effects of CLRT with a sham treatment on chronic musculoskeletal pain using pressure algometry in a double-blinded randomized controlled trial. Methods: Fifty-seven (57) volunteers with various musculoskeletal pains gave informed consent and were randomly allocated to either the CLRT treatment or sham group. Painful trigger points and/or tender spinal joints were found in each patient. Using a digital algometer, the pain/pressure threshold (PPT) was determined and a pain rating was given using a numerical pain scale from 0-10. CLRT or a sham treatment was performed with a 50 mW, 840 nm laser, for a maximum of 20 seconds to the each cranial reflex. The initial pressure (PPT) was immediately delivered to the same spot, and the pain rated again. Results: There was a statistically significant difference in pain scores between CLRT and sham groups immediately following treatment. Improvement was reported in 95% of the treatment group, with 59% reporting an improvement of 2 points or greater. The average change in pain scores in the treatment group was 2.6 points (p = 0.000) versus negligible change (p= 0.4) for the control group. Conclusion: The results show that CLRT is effective at immediately reducing chronic musculoskeletal pain. Further studies are needed with additional outcome measures to.

  3. Effect of a reduction in sodium intake on cold-induced elevation of blood pressure in the rat.

    PubMed

    van Bergen, P; Fregly, M J; Papanek, P E

    1992-09-01

    Chronic exposure of rats to cold (5 degrees C) induces hypertension within 3 weeks. The objective of this study was to determine the effect of treatment with graded levels of dietary NaCl on the induction of hypertension during chronic exposure to cold. Four groups of male rats were used. The first, given a commercial sodium-deficient diet containing 0.30% NaCl, served as the warm-adapted control group. The second, third, and fourth groups were given the same diet containing 0.075%, 0.15%, and 0.30% NaCl, respectively. Because cold-exposed rats ingest approximately twice as much food as warm-adapted controls, this represented half, the same, and twice the amount of NaCl ingested by the control group. The latter three groups were placed in cold air (5 degrees C). All cold-treated groups had an elevation of systolic blood pressure that was proportional to the concentration of NaCl in the diet by the seventeenth week of exposure to cold. Cardiac hypertrophy occurred to the same extent in all cold-exposed groups and was thus unaffected by the NaCl content of the diet or by the extent of elevation of blood pressure. Hence, cardiac hypertrophy during chronic exposure to cold is supported by other factors, possibly by the increased concentration of either norepinephrine or triiodothyronine, or both, which occurs characteristically in rats under these conditions. T