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Sample records for dissolved gas supersaturation

  1. Experimental study on total dissolved gas supersaturation in water

    Directory of Open Access Journals (Sweden)

    Lu Qu

    2011-12-01

    Full Text Available More and more high dams have been constructed and operated in China. The total dissolved gas (TDG supersaturation caused by dam discharge leads to gas bubble disease or even death of fish. Through a series of experiments, the conditions and requirements of supersaturated TDG generation were examined in this study. The results show that pressure (water depth, aeration, and bubble dissolution time are required for supersaturated TDG generation, and the air-water contact area and turbulence intensity are the main factors that affect the generation rate of supersaturated TDG. The TDG supersaturation levels can be reduced by discharging water to shallow shoals downstream of the dam or using negative pressure pipelines. Furthermore, the TDG supersaturation levels in stilling basins have no direct relationship with those in reservoirs. These results are of great importance for further research on the prediction of supersaturated TDG generation caused by dam discharge and aquatic protection.

  2. Cumulative effects of cascade hydropower stations on total dissolved gas supersaturation.

    Science.gov (United States)

    Ma, Qian; Li, Ran; Feng, Jingjie; Lu, Jingying; Zhou, Qin

    2018-03-01

    Elevated levels of total dissolved gas (TDG) may occur downstream of dams during the spill process. These high levels would increase the incidence of gas bubble disease in fish and cause severe environmental impacts. With increasing numbers of cascade hydropower stations being built or planned, the cumulative effects of TDG supersaturation are becoming increasingly prominent. The TDG saturation distribution in the downstream reaches of the Jinsha River was studied to investigate the cumulative effects of TDG supersaturation resulting from the cascade hydropower stations. A comparison of the effects of the joint operation and the single operation of two hydropower stations (XLD and XJB) was performed to analyze the risk degree to fish posed by TDG supersaturation. The results showed that water with supersaturated TDG generated at the upstream cascade can be transported to the downstream power station, leading to cumulative TDG supersaturation effects. Compared with the single operation of XJB, the joint operation of both stations produced a much higher TDG saturation downstream of XJB, especially during the non-flood discharge period. Moreover, the duration of high TDG saturation and the lengths of the lethal and sub-lethal areas were much higher in the joint operation scenario, posing a greater threat to fish and severely damaging the environment. This work provides a scientific basis for strategies to reduce TDG supersaturation to the permissible level and minimize the potential risk of supersaturated TDG.

  3. Laboratory Studies of the Effects of Pressure and Dissolved Gas Supersaturation on Turbine-Passed Fish

    Energy Technology Data Exchange (ETDEWEB)

    Neitzel, Duane A.

    2009-09-14

    Migratory and resident fish in the Columbia River Basin are exposed to stresses associated with hydroelectric power production, including changes in pressure as they pass through turbines and dissolved gas supersaturation (resulting from the release of water from the spillway). To examine pressure changes as a source of turbine-passage injury and mortality, Pacific Northwest National Laboratory scientists conducted specific tests using a hyperbaric chamber. Tests were designed to simulate Kaplan turbine passage conditions and to quantify the response of fish to rapid pressure changes, with and without the complication of fish being acclimated to gas-supersaturated water.

  4. Laboratory Studies of the Effects of Pressure and Dissolved Gas Supersaturation on Turbine-Passed Fish

    International Nuclear Information System (INIS)

    Abernethy, Cary S; Amidan, Brett G

    2001-01-01

    The objective of this study was to examine the relative importance of pressure changes as a source of turbine-passage injury and mortality. Specific tests were designed to quantify the response of fish to rapid pressure changes typical of turbine passage, with and without the complication of the fish being acclimated to gas supersaturated water. We investigated the responses of rainbow trout (Oncorhynchus mykiss), chinook salmon (O. tshawytscha), and bluegill sunfish (Lepomis macrochirus) to these two stresses, both singly and in combination

  5. Supersaturation of dissolved H(2) and CO (2) during fermentative hydrogen production with N(2) sparging.

    Science.gov (United States)

    Kraemer, Jeremy T; Bagley, David M

    2006-09-01

    Dissolved H(2) and CO(2) were measured by an improved manual headspace-gas chromatographic method during fermentative H(2) production with N(2) sparging. Sparging increased the yield from 1.3 to 1.8 mol H(2)/mol glucose converted, although H(2) and CO(2) were still supersaturated regardless of sparging. The common assumption that sparging increases the H(2) yield because of lower dissolved H(2) concentrations may be incorrect, because H(2) was not lowered into the range necessary to affect the relevant enzymes. More likely, N(2) sparging decreased the rate of H(2) consumption via lower substrate concentrations.

  6. Improved arterial blood oxygenation following intravenous infusion of cold supersaturated dissolved oxygen solution.

    Science.gov (United States)

    Grady, Daniel J; Gentile, Michael A; Riggs, John H; Cheifetz, Ira M

    2014-01-01

    One of the primary goals of critical care medicine is to support adequate gas exchange without iatrogenic sequelae. An emerging method of delivering supplemental oxygen is intravenously rather than via the traditional inhalation route. The objective of this study was to evaluate the gas-exchange effects of infusing cold intravenous (IV) fluids containing very high partial pressures of dissolved oxygen (>760 mm Hg) in a porcine model. Juvenile swines were anesthetized and mechanically ventilated. Each animal received an infusion of cold (13 °C) Ringer's lactate solution (30 mL/kg/hour), which had been supersaturated with dissolved oxygen gas (39.7 mg/L dissolved oxygen, 992 mm Hg, 30.5 mL/L). Arterial blood gases and physiologic measurements were repeated at 15-minute intervals during a 60-minute IV infusion of the supersaturated dissolved oxygen solution. Each animal served as its own control. Five swines (12.9 ± 0.9 kg) were studied. Following the 60-minute infusion, there were significant increases in PaO2 and SaO2 (P < 0.05) and a significant decrease in PaCO2 (P < 0.05), with a corresponding normalization in arterial blood pH. Additionally, there was a significant decrease in core body temperature (P < 0.05) when compared to the baseline preinfusion state. A cold, supersaturated dissolved oxygen solution may be intravenously administered to improve arterial blood oxygenation and ventilation parameters and induce a mild therapeutic hypothermia in a porcine model.

  7. Gasometer: An inexpensive device for continuous monitoring of dissolved gases and supersaturation

    Science.gov (United States)

    Bouck, G.R.

    1982-01-01

    The “gasometer” is a device that measures differential dissolved-gas pressures (δP) in water relative to barometric pressure (as does the “Weiss saturometer”), but operates continuously without human attention. The gasometer can be plumbed into a water-supply system and requires 8 liters/minute of water or more at 60 kilopascals. The gasometer's surfaces are nontoxic, and flow-through water can be used for fish culture. The gasometer may be connected to a small submersible pump and operated as a portable unit. The gasometer can activate an alarm system and thus protect fish from hyperbaric (supersaturation) or hypobaric gas pressures (usually due to low dissolved oxygen). Instructions are included for calculating and reporting data including the pressure and saturation of individual gases. Construction and performance standards are given for the gasometer. Occasional cleaning is required to remove biofouling from the gas-permeable tubing.PDF

  8. Investigation of changes to the operation of Keenleyside Dam to reduce supersaturation of dissolved gases downstream

    International Nuclear Information System (INIS)

    Nunn, J.O.H.; Fidler, L.E.; Northcott, P.

    1993-01-01

    Keenlyside Dam is located on the Columbia River in southeast British Columbia. It impounds Arrow Lakes Reservoir, which has a live storage of 8.8 billion m 3 . The dam is used for flood control and to increase power generation in the USA. Recent field measurements have shown that the current operation of the dam often creates high levels of total gas pressure (TGP) downstream of the dam, with supersaturation levels occasionally reaching as high as 140%. It appeared that these increased levels were associated with the use of the spillway. High levels of dissolved gases may have adverse effects on aquatic life. Therefore, a comprehensive study was initiated to investigate ways of reducing TGP levels. The discharge facilities at the dam are described, along with the effects of dissolved gas supersaturation on fish. Current studies include measurement of field TGP levels, development of a model to predict TGP levels for different modes of operation of the discharge facilities, assessing the effects of TGP on different fish species at different life stages, field testing of the discharge facilities, and assessment of long-term impacts of various operating alternatives on the dam structures and equipment. Preliminary results indicate that the north low-level ports of the spillway increase the TGP level significantly less than the other two components of the discharge facilities. Current operating practice therefore maximizes use of the north ports within current operating limits. 9 refs., 4 figs

  9. Nutrient digestibility and growth in rainbow trout (Oncorhynchus mykiss) are impaired by short term exposure to moderate supersaturation in total gas pressure

    DEFF Research Database (Denmark)

    Skov, Peter Vilhelm; Pedersen, Lars-Flemming; Pedersen, Per Bovbjerg

    2013-01-01

    Excess levels of dissolved nitrogen gas (N2) may occur in recirculating aquaculture systems, as a result of aeration efforts, localized occurrences of denitrification, or from insufficient degassing of makeup water. If levels of dissolved N2 are sufficiently high, or if oxygen (O2) is also...... maintained at or above saturation, this leads to a supersaturation in total gas pressure (TGP). Depending on severity, total gas pressures above saturation may lead to gas bubble trauma, evident by visual inspection of the fish. Physiological effects of subclinical levels of TGP are not well known and have...... not been investigated for rainbow trout. The present study examined the effects of N2 supersaturation, with or without simultaneous excess TGP. Supersaturation with N2 (ΔP 22mmHg) without total gas supersaturation (ΔTGP −6mmHg) did not have any significant effects on feed intake, feed conversion or growth...

  10. Review of Current Literature and Research on Gas Supersaturation and Gas Bubble Trauma: Special Publication Number 1, 1986.

    Energy Technology Data Exchange (ETDEWEB)

    Colt, John; Bouck, Gerald R.; Fidler, Larry

    1986-12-01

    This report presents recently published information and on-going research on the various areas of gas supersaturation. Growing interest in the effects of chronic gas supersaturation on aquatic animals has been due primarily to heavy mortality of salmonid species under hatchery conditions. Extensive examination of affected animals has failed to consistently identify pathogenic organisms. Water quality sampling has shown that chronic levels of gas supersaturation are commonly present during a significant period of the year. Small marine fish larvae are significantly more sensitive to gas supersaturation than salmonids. Present water quality criteria for gas supersaturation are not adequate for the protection of either salmonids under chronic exposure or marine fish larvae, especially in aquaria or hatcheries. To increase communication between interested parties in the field of gas supersaturation research and control, addresses and telephone numbers of all people responding to the questionnaire are included. 102 refs.

  11. Toward the development of erosion-free ultrasonic cavitation cleaning with gas-supersaturated water

    Science.gov (United States)

    Yamashita, Tatsuya; Ando, Keita

    2015-11-01

    In ultrasonic cleaning, contaminant particles attached at target surfaces are removed by liquid flow or acoustic waves that are induced by acoustic cavitation bubbles. However, the inertial collapse of such bubbles often involve strong shock emission or water hammer by re-entrant jets, thereby giving rise to material erosion. Here, we aim at developing an erosion-free ultrasonic cleaning technique with the aid of gas-supersaturated water. The key idea is that (gaseous) cavitation is triggered easily even with low-intensity sonication in water where gases are dissolved beyond Henry's saturation limit, allowing us to buffer violent bubble collapse. In this presentation, we report on observations of the removal of micron/submicron-sized particles attached at glass surfaces by the action of gaseous cavitation bubbles under low-intensity sonication.

  12. Bubble coalescence dynamics and supersaturation in electrolytic gas evolution

    Energy Technology Data Exchange (ETDEWEB)

    Stover, R.L. [Univ. of California, Berkeley, CA (United States). Dept. of Chemical Engineering]|[Lawrence Berkeley National Lab., CA (United States). Energy and Environment Div.

    1996-08-01

    The apparatus and procedures developed in this research permit the observation of electrolytic bubble coalescence, which heretofore has not been possible. The influence of bubble size, electrolyte viscosity, surface tension, gas type, and pH on bubble coalescence was examined. The Navier-Stokes equations with free surface boundary conditions were solved numerically for the full range of experimental variables that were examined. Based on this study, the following mechanism for bubble coalescence emerges: when two gas bubbles coalesce, the surface energy decreases as the curvature and surface area of the resultant bubble decrease, and the energy is imparted into the surrounding liquid. The initial motion is driven by the surface tension and slowed by the inertia and viscosity of the surrounding fluid. The initial velocity of the interface is approximately proportional to the square root of the surface tension and inversely proportional to the square root of the bubble radius. Fluid inertia sustains the oblate/prolate oscillations of the resultant bubble. The period of the oscillations varies with the bubble radius raised to the 3/2 power and inversely with the square root of the surface tension. Viscous resistance dampens the oscillations at a rate proportional to the viscosity and inversely proportional to the square of the bubble radius. The numerical simulations were consistent with most of the experimental results. The differences between the computed and measured saddle point decelerations and periods suggest that the surface tension in the experiments may have changed during each run. By adjusting the surface tension in the simulation, a good fit was obtained for the 150-{micro}m diameter bubbles. The simulations fit the experiments on larger bubbles with very little adjustment of surface tension. A more focused analysis should be done to elucidate the phenomena that occur in the receding liquid film immediately following rupture.

  13. Millstone 3 condensate dissolved gas monitoring

    International Nuclear Information System (INIS)

    Burns, T.F.; Grondahl, E.E.; Snyder, D.T.

    1988-01-01

    Condensate dissolved oxygen problems at Millstone Point Unit 3 (MP3) were investigated using the Dissolved Gas Monitoring System developed by Radiological and Chemical Technology, Inc. under EPRI sponsorship. Argon was injected into the turbine exhaust basket tips to perform a dissolved gas transport analysis and determine steam jet air ejector gas removal efficiency. The operating configuration of the steam jet air ejector system was varied to determine the effect on gas removal efficiency. Following circulating water chlorination, the gas removal efficiency was determined to evaluate the effect of condenser tube fouling on steam jet air ejector performance

  14. Total dissolved gas, barometric pressure, and water temperature data, lower Columbia River, Oregon and Washington, 1996

    Science.gov (United States)

    Tanner, Dwight Q.; Harrison, Howard E.; McKenzie, Stuart W.

    1996-01-01

    Increased levels of total dissolved gas pressure can cause gas-bubble trauma in fish downstream from dams on the Columbia River. In cooperation with the U.S. Army Corps of Engineers, the U.S. Geological Survey collected data on total dissolved gas pressure, barometric pressure, water temperature, and dissolved oxygen pressure at 11 stations on the lower Columbia River from the John Day forebay (river mile 215.6) to Wauna Mill (river mile 41.9) from March to September 1996. Methods of data collection, review, and processing are described in this report. Summaries of daily minimum, maximum, and mean hourly values are presented for total dissolved gas pressure, barometric pressure, and water temperature. Hourly values for these parameters are presented graphically. Dissolved oxygen data are not presented in this report because the quality-control data show that the data have poor precision and high bias. Suggested changes to monitoring procedures for future studies include (1) improved calibration procedures for total dissolved gas and dissolved oxygen to better define accuracy at elevated levels of supersaturation and (2) equipping dissolved oxygen sensors with stirrers because river velocities at the shoreline monitoring stations probably cannot maintain an adequate flow of water across the membrane surface of the dissolved oxygen sensor.

  15. Decoupling of bilayer leaflets under gas supersaturation: nitrogen nanobubbles in a membrane and their implication in decompression sickness

    Science.gov (United States)

    Li, Jing; Zhang, Xianren; Cao, Dapeng

    2018-05-01

    Decompression sickness (also known as diver’s sickness) is a disease that arises from the formation of a bubble inside the body caused by rapid decompression from high atmospheric pressures. However, the nature of pre-existing micronuclei that are proposed for interpreting the formation and growth of the bubble, as well as their very existence, is still highly controversial. In this work, atomistic molecular dynamics simulations are employed to investigate the nucleation of gas bubbles under the condition of nitrogen supersaturation, in the presence of a lipid bilayer and lipid micelle representing other macromolecules with a smaller hydrophobic region. Our simulation results demonstrate that by crossing a small energy barrier, excess nitrogen molecules can enter the lipid bilayer nearly spontaneously, for which the hydrophobic core serves as a potential well for gas enrichment. At a rather low nitrogen supersaturation, gas molecules in the membrane are dispersed in the hydrophobic region of the bilayer, with a slight increase in membrane thickness. But as the level of gas supersaturation reaches a threshold, the accumulation of N2 molecules in the bilayer center causes the two leaflets to be decoupled and the formation of nanobubbles. Therefore, we propose a nucleation mechanism for bubble formation in a supersaturated solution of inert gas: a cell membrane acts as a potential well for gas enrichment, being an ideal location for forming nanobubbles that induce membrane damage at a high level of gas supersaturation. As opposed to previous models, the new mechanism involves forming gas nuclei in a very low-tension hydrophobic environment, and thus a rather low energy barrier is required and pre-existing bubble micronuclei are not needed.

  16. Dissolved atmospheric gas in xylem sap measured with membrane inlet mass spectrometry.

    Science.gov (United States)

    Schenk, H Jochen; Espino, Susana; Visser, Ate; Esser, Bradley K

    2016-04-01

    A new method is described for measuring dissolved gas concentrations in small volumes of xylem sap using membrane inlet mass spectrometry. The technique can be used to determine concentrations of atmospheric gases, such as argon, as reported here, or for any dissolved gases and their isotopes for a variety of applications, such as rapid detection of trace gases from groundwater only hours after they were taken up by trees and rooting depth estimation. Atmospheric gas content in xylem sap directly affects the conditions and mechanisms that allow for gas removal from xylem embolisms, because gas can dissolve into saturated or supersaturated sap only under gas pressure that is above atmospheric pressure. The method was tested for red trumpet vine, Distictis buccinatoria (Bignoniaceae), by measuring atmospheric gas concentrations in sap collected at times of minimum and maximum daily temperature and during temperature increase and decline. Mean argon concentration in xylem sap did not differ significantly from saturation levels for the temperature and pressure conditions at any time of collection, but more than 40% of all samples were supersaturated, especially during the warm parts of day. There was no significant diurnal pattern, due to high variability between samples. © 2015 John Wiley & Sons Ltd.

  17. Recovery of krypton-85 from dissolver off-gas streams

    International Nuclear Information System (INIS)

    Law, J.P.; Lamb, K.M.

    1988-01-01

    The Rare Gas Plant at the Idaho Chemical Processing Plant Recovers fission product krypton and xenon from dissolver off gas streams. Recently the system was upgraded to allow processing of hydrogen rich dissolver off-gas streams. A trickle bed hydrogen recombiner was installed and tested. The Rare Gas Plant can now safely process gas streams containing up to 80% hydrogen

  18. PREDICTION OF TOTAL DISSOLVED GAS EXCHANGE AT HYDROPOWER DAMS

    Energy Technology Data Exchange (ETDEWEB)

    Hadjerioua, Boualem [ORNL; Pasha, MD Fayzul K [ORNL; Stewart, Kevin M [ORNL; Bender, Merlynn [Bureau of Reclamation; Schneider, Michael L. [U.S. Army Corps of Engineers

    2012-07-01

    Total dissolved gas (TDG) supersaturation in waters released at hydropower dams can cause gas bubble trauma in fisheries resulting in physical injuries and eyeball protrusion that can lead to mortality. Elevated TDG pressures in hydropower releases are generally caused by the entrainment of air in spillway releases and the subsequent exchange of atmospheric gasses into solution during passage through the stilling basin. The network of dams throughout the Columbia River Basin (CRB) are managed for irrigation, hydropower production, flood control, navigation, and fish passage that frequently result in both voluntary and involuntary spillway releases. These dam operations are constrained by state and federal water quality standards for TDG saturation which balance the benefits of spillway operations designed for Endangered Species Act (ESA)-listed fisheries versus the degradation to water quality as defined by TDG saturation. In the 1970s, the United States Environmental Protection Agency (USEPA), under the federal Clean Water Act (Section 303(d)), established a criterion not to exceed the TDG saturation level of 110% in order to protect freshwater and marine aquatic life. The states of Washington and Oregon have adopted special water quality standards for TDG saturation in the tailrace and forebays of hydropower facilities on the Columbia and Snake Rivers where spillway operations support fish passage objectives. The physical processes that affect TDG exchange at hydropower facilities have been studied throughout the CRB in site-specific studies and routine water quality monitoring programs. These data have been used to quantify the relationship between project operations, structural properties, and TDG exchange. These data have also been used to develop predictive models of TDG exchange to support real-time TDG management decisions. These empirically based predictive models have been developed for specific projects and account for both the fate of spillway and

  19. Total Dissolved Gas Monitoring in Chum Salmon Spawning Gravels Below Bonneville Dam

    Energy Technology Data Exchange (ETDEWEB)

    Arntzen, Evan V.; Geist, David R.; Panther, Jennifer L.; Dawley, Earl

    2007-01-30

    At the request of the U.S. Army Corps of Engineers (Portland District), Pacific Northwest National Laboratory (PNNL) conducted research to determine whether total dissolved gas concentrations are elevated in chum salmon redds during spring spill operations at Bonneville Dam. The study involved monitoring the total dissolved gas levels at egg pocket depth and in the river at two chum salmon spawning locations downstream from Bonneville Dam. Dissolved atmospheric gas supersaturation generated by spill from Bonneville Dam may diminish survival of chum (Oncorhynchus keta) salmon when sac fry are still present in the gravel downstream from Bonneville Dam. However, no previous work has been conducted to determine whether total dissolved gas (TDG) levels are elevated during spring spill operations within incubation habitats. The guidance used by hydropower system managers to provide protection for pre-emergent chum salmon fry has been to limit TDG to 105% after allowing for depth compensation. A previous literature review completed in early 2006 shows that TDG levels as low as 103% have been documented to cause mortality in sac fry. Our study measured TDG in the incubation environment to evaluate whether these levels were exceeded during spring spill operations. Total dissolved gas levels were measured within chum salmon spawning areas near Ives Island and Multnomah Falls on the Columbia River. Water quality sensors screened at egg pocket depth and to the river were installed at both sites. At each location, we also measured dissolved oxygen, temperature, specific conductance, and water depth to assist with the interpretation of TDG results. Total dissolved gas was depth-compensated to determine when levels were high enough to potentially affect sac fry. This report provides detailed descriptions of the two study sites downstream of Bonneville Dam, as well as the equipment and procedures employed to monitor the TDG levels at the study sites. Results of the monitoring at

  20. Dissolved gas concentrations of the geothermal fluids in Taiwan

    Science.gov (United States)

    Chen, Ai-Ti; Yang, Tsanyao Frank

    2010-05-01

    Taiwan, a geologically active island, is located on the boundary of the Philippine Sea Plate and the Eurasian Plate. High heat flow and geothermal gradient generated by the complex collision and orogeny, warm up the meteoric water and/or the ground water. The heated water becomes geothermal fluids. In previous studies, researchers tried to categorize hot springs based on the appearance, chemical compositions and lithological areas. Because of the chemical inertness, the concentrations and isotopic composition of dissolved noble gases are good indicators of the mantle degassing, geothermal conditions, and so on. In this study, 55 hot springs were collected from different tectonic units. It is the first time to systematically study the hot springs in Taiwan in terms of dissolved gases. Hot spring water is sampled and stored in pre-evacuated glass bottles for analyzing gas compositions. The abundances of noble gases were determined by a quadrupole mass spectrometer based on the isotope dilution technique. Samples with glass vials are introduced to RAD 7 and GC for dissolved Rn and major dissolved gases analyses. Furthermore, helium isotopic ratios and helium-neon ratios are measured on a conventional noble gas mass spectrometer. For hydrochemistry analysis, water samples are analyzed by IC, ICP-MS and titration. We can classify the hot springs samples into three major groups from main anion concentration data; and then, subdivide them into nine minor groups by cation concentration data. Moreover, according to major dissolved gases compositions, three major gas components: CH4, N2 and CO2, are identified. Dissolved noble gases provided more detailed clues about hot springs sources in Taiwan, such as the degree of mixing between meteoric water and deep-source water, which will be further discussed in this study.

  1. Measuring and understanding total dissolved gas pressure in groundwater

    Science.gov (United States)

    Ryan, C.; Roy, J. W.; Randell, J.; Castellon, L.

    2009-05-01

    Since dissolved gases are important to a number of aspects of groundwater (e.g. age dating, active or passive bioremediation, greenhouse gas fluxes, understanding biogeochemical processes involving gases, assessing potential impacts of coal bed methane activities), accurate concentration measurements, and understanding of their subsurface behaviour are important. Researchers have recently begun using total dissolved gas pressure (TGP) sensor measurements, more commonly applied for surface water monitoring, in concert with gas composition analyses to estimate more accurate groundwater gas concentrations in wells. We have used hydraulic packers to isolate the well screens where TDP is being measured, and pump tests to indicate that in-well degassing may reduce TDG below background groundwater levels. Thus, in gas-charged groundwater zones, TGPs can be considerably underestimated in the absence of pumping or screen isolation. We have also observed transient decreased TGPs during pumping that are thought to result from ebullition induced when the water table or water level in the well is lowered below a critical hydrostatic pressure.

  2. Gas Supersaturation May Reduce the Survival of Yearling Chinook Salmon in the Lower Columbia River and Ocean Plume

    Science.gov (United States)

    Brosnan, Ian; Welch, David; Scott, Melinda Jacobs

    2015-01-01

    Unusually high flows in the Columbia River in 2011 raised total dissolved gas (TDG) levels in the river above the 120 percent legal limit imposed to prevent harmful impacts to aquatic organisms. This provided a unique opportunity to evaluate the effect on smolt survival. In-river (IR) migrating juvenile yearling Chinook released at Bonneville Dam with acoustic tags during periods when TDG exceeded 120 percent received estimated maximum exposures of 134 TDG. Subsequent daily survival rates in the lower river and plume were reduced by 0.06 per day (SE equals 0.01) and 0.15 per day (SE equals 0.05) relative to IR migrant fish released when TDG was less than 120 percent. Transported smolts (T) released 10-13 kilometers below Bonneville Dam had lower maximum exposure levels (126 percent) and experienced no difference in daily survival rates relative to unexposed smolts. River temperature levels and trends in turbidity and disease prevalence between releases of high and low exposure smolts were not consistent with the observed effects on survival rates. We conclude that smolts may suffer from chronic effects of elevated TDG exposure while migrating through the Columbia River and plume. Consideration should be given to measuring these survival losses in an explicit experimental framework that isolates possible confounding factors.

  3. Do lagoons near concentrated animal feeding operations promote nitrous oxide supersaturation?

    International Nuclear Information System (INIS)

    Makris, Konstantinos C.; Sarkar, Dibyendu; Andra, Syam S.; Bach, Stephan B.H.; Datta, Rupali

    2009-01-01

    Animal wastewater lagoons nearby concentrated animal feeding operations (CAFOs) represent the latest tendency in global animal farming, severely impacting the magnitude of greenhouse gas emissions, including nitrous oxide (N 2 O). We hypothesized that lagoon wastewater could be supersaturated with N 2 O as part of incomplete microbial nitrification/denitrification processes, thereby regulating the N 2 O partitioning in the gaseous phase. The objectives of this study were: (i) to investigate the magnitude of dissolved N 2 O concentrations in the lagoon; and (ii) to determine the extent to which supersaturation of N 2 O occurs in wastewater lagoons. Dissolved N 2 O concentrations in the wastewater samples were high, ranging from 0.4 to 40.5 μg N 2 O mL -1 . Calculated dissolved N 2 O concentrations from the experimentally measured partition coefficients were much greater than those typically expected in aquatic systems ( 2 O mL -1 ). Knowledge of the factors controlling the magnitude of N 2 O supersaturation could potentially bridge mass balance differences between in situ measurements and global N 2 O models. - Supersaturation of nitrous oxide may occur in lagoons near concentrated animal feeding operations.

  4. Total Dissolved Gas Effects on Incubating Chum Salmon Below Bonneville Dam

    Energy Technology Data Exchange (ETDEWEB)

    Arntzen, Evan V.; Hand, Kristine D.; Carter, Kathleen M.; Geist, David R.; Murray, Katherine J.; Dawley, Earl M.; Cullinan, Valerie I.; Elston, Ralph A.; Vavrinec, John

    2009-01-29

    At the request of the U.S. Army Corps of Engineers (USACE; Portland District), Pacific Northwest National Laboratory (PNNL) undertook a project in 2006 to look further into issues of total dissolved gas (TDG) supersaturation in the lower Columbia River downstream of Bonneville Dam. In FY 2008, the third year of the project, PNNL conducted field monitoring and laboratory toxicity testing to both verify results from 2007 and answer some additional questions about how salmonid sac fry respond to elevated TDG in the field and the laboratory. For FY 2008, three objectives were 1) to repeat the 2006-2007 field effort to collect empirical data on TDG from the Ives Island and Multnomah Falls study sites; 2) to repeat the static laboratory toxicity tests on hatchery chum salmon fry to verify 2007 results and to expose wild chum salmon fry to incremental increases in TDG, above those of the static test, until external symptoms of gas bubble disease were clearly present; and 3) to assess physiological responses to TDG levels in wild chum salmon sac fry incubating below Bonneville Dam during spill operations. This report summarizes the tasks conducted and results obtained in pursuit of the three objectives. Chapter 1 discusses the field monitoring, Chapter 2 reports the findings of the laboratory toxicity tests, and Chapter 3 describes the field-sampling task. Each chapter contains an objective-specific introduction, description of the study site and methods, results of research, and discussion of findings. Literature cited throughout this report is listed in Chapter 4. Additional details on the monitoring methodology and results are provided in Appendices A and B included on the compact disc bound inside the back cover of the printed version of this report.

  5. Supersaturating drug delivery systems

    DEFF Research Database (Denmark)

    Laitinen, Riikka; Löbmann, Korbinian; Grohganz, Holger

    2017-01-01

    of the bioavailability of poorly water-soluble drugs by increasing the driving force for drug absorption. However, ASDs often require a high weight percentage of carrier (usually a hydrophilic polymer) to ensure molecular mixing of the drug in the carrier and stabilization of the supersaturated state, often leading......Amorphous solid dispersions (ASDs) are probably the most common and important supersaturating drug delivery systems for the formulation of poorly water-soluble compounds. These delivery systems are able to achieve and maintain a sustained drug supersaturation which enables improvement...... strategy for poorly-soluble drugs. While the current research on co-amorphous formulations is focused on preparation and characterization of these systems, more detailed research on their supersaturation and precipitation behavior and the effect of co-formers on nucleation and crystal growth inhibition...

  6. Separation of krypton from dissolver off-gas of a reprocessing plant using preparative gas chromatography

    International Nuclear Information System (INIS)

    Matoni, M.

    1984-02-01

    Kr-85 can be separated from the pre-purified purge air in the final processing step of the purification phase for dissolver off-gases of a reprocessing plant with the aid of preparative gas chromatography. Activated carbon adsorbers in combination with helium as carrier gas permits maximum gas mixture through-flow. A separation temperature of 30 0 C is considered optimal. An adsorbent volume of 40 dm 3 is necessary for processing the residual gas flow of 2.5 Nm 3 /h; the adsorbent is divided between 2 columns linked in series each of which are 2 m long with an internal diameter of 100 mm. The helium flow required is five times greater than the off-gas flow. The degree of purity for krypton is greater than 90% for a decontamination factor of greater than 1000. (orig./HP) [de

  7. Fish Individual-based Numerical Simulator (FINS): A particle-based model of juvenile salmonid movement and dissolved gas exposure history in the Columbia River Basin

    International Nuclear Information System (INIS)

    Scheibe, Timothy D.; Richmond, Marshall C.

    2002-01-01

    This paper describes a numerical model of juvenile salmonid migration in the Columbia and Snake Rivers. The model, called the Fish Individual-based Numerical Simulator or FINS, employs a discrete, particle-based approach to simulate the migration and history of exposure to dissolved gases of individual fish. FINS is linked to a two-dimensional (vertically-averaged) hydrodynamic simulator that quantifies local water velocity, temperature, and dissolved gas levels as a function of river flow rates and dam operations. Simulated gas exposure histories can be input to biological mortality models to predict the effects of various river configurations on fish injury and mortality due to dissolved gas supersaturation. Therefore, FINS serves as a critical linkage between hydrodynamic models of the river system and models of biological impacts. FINS was parameterized and validated based on observations of individual fish movements collected using radiotelemetry methods during 1997 and 1998 . A quasi-inverse approach was used to decouple fish swimming movements from advection with the local water velocity, allowing inference of time series of non-advective displacements of individual fish from the radiotelemetry data. Statistical analyses of these displacements are presented, and confirm that strong temporal correlation of fish swimming behavior persists in some cases over several hours. A correlated random-walk model was employed to simulate the observed migration behavior, and parameters of the model were estimated that lead to close correspondence between predictions and observations

  8. Effect of Dissolved gas on bubble behavior of subcooled boiling in narrow channel

    International Nuclear Information System (INIS)

    Li Shaodan; Tan Sichao; Xu Chao; Gao Puzhen; Xu Jianjun

    2013-01-01

    An experimental investigation was performed to study the effect of dissolved gas on bubble behavior in narrow rectangular channel under subcooled boiling condition. A high-speed digital video camera was applied to capture the dynamics of the bubble with or without dissolved gas in a narrow rectangular channel. It is found that the dissolved gas has great influence on bubble behavior in subcooled boiling condition. The dissolved gas slows down the rate of bubble growth and condensation and makes the variation of the bubble diameter present some oscillation characteristics. This phenomenon was discussed in the view of the vapor evaporation and condensation. The existence of the dissolved gas can facilitate the survival of the bubble and promote the aggregation of bubbles, and enhence heat transfer enhancement in some ways. (authors)

  9. Use of a dissolved-gas measurement system for reducing the dissolved oxygen at St. Lucie Unit 2

    International Nuclear Information System (INIS)

    Snyder, D.T.; Coit, R.L.

    1993-02-01

    When the dissolved oxygen in the condensate at St. Lucie Unit 2 could not be reduced below the administrative limit of 10 ppB, EPRI cooperated with Florida Power and Light to find the cause and develop remedies. Two problems were identified with the assistance of a dissolved gas measurement system (DGMS) that can detect leaks into condensate when used with argon blanketing. Drain piping from the air ejection system had flooded which decreased its performance, and leaks were found at a strainer flange and a couple expansion joints. Initially the dissolved oxygen content was reduced to about 9 ppB; owever, the dissolved oxygen from Condenser A was consistently higher than that from condenser B. Injection of about 0.4 cubic per minute (CFM) of argon above the hotwell considerably improved the ventilation of Condenser A, reducing the dissolved oxygen about 30% to about 6 ppB. The use of nitrogen was equally effective. While inert gas injection is helpful, it may be better to have separate air ejectors for each condenser. Several recommendations for improving oxygen removal are given

  10. Suitability of selected free-gas and dissolved-gas sampling containers for carbon isotopic analysis.

    Science.gov (United States)

    Eby, P; Gibson, J J; Yi, Y

    2015-07-15

    Storage trials were conducted for 2 to 3 months using a hydrocarbon and carbon dioxide gas mixture with known carbon isotopic composition to simulate typical hold times for gas samples prior to isotopic analysis. A range of containers (both pierced and unpierced) was periodically sampled to test for δ(13)C isotopic fractionation. Seventeen containers were tested for free-gas storage (20°C, 1 atm pressure) and 7 containers were tested for dissolved-gas storage, the latter prepared by bubbling free gas through tap water until saturated (20°C, 1 atm) and then preserved to avoid biological activity by acidifying to pH 2 with phosphoric acid and stored in the dark at 5°C. Samples were extracted using valves or by piercing septa, and then introduced into an isotope ratio mass spectrometer for compound-specific δ(13)C measurements. For free gas, stainless steel canisters and crimp-top glass serum bottles with butyl septa were most effective at preventing isotopic fractionation (pierced and unpierced), whereas silicone and PTFE-butyl septa allowed significant isotopic fractionation. FlexFoil and Tedlar bags were found to be effective only for storage of up to 1 month. For dissolved gas, crimp-top glass serum bottles with butyl septa were again effective, whereas silicone and PTFE-butyl were not. FlexFoil bags were reliable for up to 2 months. Our results suggest a range of preferred containers as well as several that did not perform very well for isotopic analysis. Overall, the results help establish better QA/QC procedures to avoid isotopic fractionation when storing environmental gas samples. Recommended containers for air transportation include steel canisters and glass serum bottles with butyl septa (pierced and unpierced). Copyright © 2015 John Wiley & Sons, Ltd.

  11. Subcooled boiling heat transfer correlation to calculate the effects of dissolved gas in a liquid

    International Nuclear Information System (INIS)

    Zarkasi, Amin S.; Chao, W.W.; Kunze, Jay F.

    2004-01-01

    The water coolant in most operating power reactor systems is kept free of dissolved gas, so as to minimize corrosion. However, in most research reactors, which operate at temperatures below 70 deg. C, and between 1 and 5 atm. pressure, the dissolved gas remains present in the water coolant system during operation. This dissolved gas can have a significant effect during accident conditions (i.e. a LOCA), when the fluid quickly reaches boiling, coincident with flow stagnation and subsequent flow reversal. A benchmark experiment was conducted, with an electrically heated, closed loop channel, modeling a research reactor fuel coolant channels (2 mm thick). The results showed 'boiling (bubble) noise' occurring before wall temperatures reached saturation, and a significant increase (up to 50%) in the heat transfer coefficient in the subcooled boiling region when in the presence of dissolved gas, compared to degassed water. Since power reactors do not involve dissolved gas, the RELAP safety analysis code does not include any provisions for the effect of dissolved gas on heat transfer. In this work, the effects of the dissolved gas are evaluated for inclusion in the RELAP code, including provision for initiating 'nucleate boiling' at a lower temperature, and a provision for enhancing the heat transfer coefficient during the subcooled boiling region. Instead of relying on Chen's correlation alone, a modification of the superposition method of Bjorge was adopted. (author)

  12. Laser Calorimetry Spectroscopy for ppm-level Dissolved Gas Detection and Analysis.

    Science.gov (United States)

    K S, Nagapriya; Sinha, Shashank; R, Prashanth; Poonacha, Samhitha; Chaudhry, Gunaranjan; Bhattacharya, Anandaroop; Choudhury, Niloy; Mahalik, Saroj; Maity, Sandip

    2017-02-20

    In this paper we report a newly developed technique - laser calorimetry spectroscopy (LCS), which is a combination of laser absorption spectroscopy and calorimetry - for the detection of gases dissolved in liquids. The technique involves determination of concentration of a dissolved gas by irradiating the liquid with light of a wavelength where the gas absorbs, and measuring the temperature change caused by the absorbance. Conventionally, detection of dissolved gases with sufficient sensitivity and specificity was done by first extracting the gases from the liquid and then analyzing the gases using techniques such as gas chromatography. Using LCS, we have been able to detect ppm levels of dissolved gases without extracting them from the liquid. In this paper, we show the detection of dissolved acetylene in transformer oil in the mid infrared (MIR) wavelength (3021 nm) region.

  13. Total dissolved gas prediction and optimization in RiverWare

    Energy Technology Data Exchange (ETDEWEB)

    Stewart, Kevin M. [Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States); Witt, Adam M. [Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States); Hadjerioua, Boualem [Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)

    2015-09-01

    Management and operation of dams within the Columbia River Basin (CRB) provides the region with irrigation, hydropower production, flood control, navigation, and fish passage. These various system-wide demands can require unique dam operations that may result in both voluntary and involuntary spill, thereby increasing tailrace levels of total dissolved gas (TDG) which can be fatal to fish. Appropriately managing TDG levels within the context of the systematic demands requires a predictive framework robust enough to capture the operationally related effects on TDG levels. Development of the TDG predictive methodology herein attempts to capture the different modes of hydro operation, thereby making it a viable tool to be used in conjunction with a real-time scheduling model such as RiverWare. The end result of the effort will allow hydro operators to minimize system-wide TDG while meeting hydropower operational targets and constraints. The physical parameters such as spill and hydropower flow proportions, accompanied by the characteristics of the dam such as plant head levels and tailrace depths, are used to develop the empirically-based prediction model. In the broader study, two different models are developed a simplified and comprehensive model. The latter model incorporates more specific bubble physics parameters for the prediction of tailrace TDG levels. The former model is presented herein and utilizes an empirically based approach to predict downstream TDG levels based on local saturation depth, spillway and powerhouse flow proportions, and entrainment effects. Representative data collected from each of the hydro projects is used to calibrate and validate model performance and the accuracy of predicted TDG uptake. ORNL, in conjunction with IIHR - Hydroscience & Engineering, The University of Iowa, carried out model adjustments to adequately capture TDG levels with respect to each plant while maintaining a generalized model configuration. Validation results

  14. Fabrication of ATALANTE Dissolver Off-Gas Sorbent-Based Capture System

    Energy Technology Data Exchange (ETDEWEB)

    Walker, Jr., Joseph Franklin [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Jubin, Robert Thomas [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2015-04-30

    A small sorbent-based capture system was designed that could be placed in the off-gas line from the fuel dissolver in the ATALANTE hot cells with minimal modifications to the ATALANTE dissolver off-gas system. Discussions with personnel from the ATALANTE facility provided guidance that was used for the design. All components for this system have been specified, procured, and received on site at Oak Ridge National Laboratory (ORNL), meeting the April 30, 2015, milestone for completing the fabrication of the ATALANTE dissolver off-gas capture system. This system will be tested at ORNL to verify operation and to ensure that all design requirements for ATALANTE are met. Modifications to the system will be made, as indicated by the testing, before the system is shipped to ATALANTE for installation in the hot cell facility.

  15. Novel Apparatus for the Real-Time Quantification of Dissolved Gas Concentrations and Isotope Ratios

    Science.gov (United States)

    Gupta, M.; Leen, J.; Baer, D. S.; Owano, T. G.; Liem, J.

    2013-12-01

    Measurements of dissolved gases and their isotopic composition are critical in studying a variety of phenomena, including underwater greenhouse gas generation, air-surface exchange, and pollution migration. These studies typically involve obtaining water samples from streams, lakes, or ocean water and transporting them to a laboratory, where they are degased. The gases obtained are then generally measured using gas chromatography and isotope ratio mass spectrometry for concentrations and isotope ratios, respectively. This conventional, off-line methodology is time consuming, significantly limits the number of the samples that can be measured and thus severely inhibits detailed spatial and temporal mapping of gas concentrations and isotope ratios. In this work, we describe the development of a new membrane-based degassing device that interfaces directly to Los Gatos Research (cavity enhanced laser absorption or Off-Axis ICOS) gas analyzers (cavity enhanced laser absorption or Off-Axis ICOS analyzers) to create an autonomous system that can continuously and quickly measure concentrations and isotope ratios of dissolved gases in real time in the field. By accurately controlling the water flow rate through the membrane degasser, gas pressure on the outside of the membrane, and water pressure on the inside of the membrane, the system is able to generate precise and highly reproducible results. Moreover, by accurately measuring the gas flow rates in and out of the degasser, the gas-phase concentrations (ppm) could be converted into dissolved gas concentrations (nM). We will present detailed laboratory test data that quantifies the linearity, precision, and dynamic range of the system for the concentrations and isotope ratios of dissolved methane, carbon dioxide, and nitrous oxide. By interfacing the degassing device to a novel cavity-enhanced spectrometer (developed by LGR), preliminary data will also be presented for dissolved volatile organics (VOC) and other

  16. Adsorptive separation of NOsub(x) from dissolver off-gas

    International Nuclear Information System (INIS)

    Ringel, H.

    1984-06-01

    After precleaning the dissolver off-gas contains, besides the noble gases Xe and Kr, about 0.5 vol.% each of NOsub(x) and H 2 O. For the removal of these NOsub(x) and H 2 O residues to below 1 ppm, an adsorptive gas cleaning process has been developed and tested on a lab-scale. For the process, an acid resistant molecular sieve was selected and its properties investigated with respect to application; e.g. the dependence of the adsorption capacity on temperature, gas composition and face velocity. By the operation of a lab-scale facility with 400 Nl/h continuous off-gas throughput the suitability of the adsorption process has been demonstrated for off-gas cleaning and recycling of the separated NO 2 and H 2 O to the dissolver. (orig.) [de

  17. Measurement of dissolved hydrogen and hydrogen gas transfer in a hydrogen-producing reactor

    Energy Technology Data Exchange (ETDEWEB)

    Shizas, I.; Bagley, D.M. [Toronto Univ., ON (Canada). Dept. of Civil Engineering

    2004-07-01

    This paper presents a simple method to measure dissolved hydrogen concentrations in the laboratory using standard equipment and a series of hydrogen gas transfer tests. The method was validated by measuring hydrogen gas transfer parameters for an anaerobic reactor system that was purged with 10 per cent carbon dioxide and 90 per cent nitrogen using a coarse bubble diffuser stone. Liquid samples from the reactor were injected into vials and hydrogen was allowed to partition between the liquid and gaseous phases. The concentration of dissolved hydrogen was determined by comparing the headspace injections onto a gas chromatograph and a standard curve. The detection limit was 1.0 x 10{sup -5} mol/L of dissolved hydrogen. The gas transfer rate for hydrogen in basal medium and anaerobic digester sludge was used to validate the method. Results were compared with gas transfer models. In addition to monitoring dissolved hydrogen in reactor systems, this method can help improve hydrogen production potential. 1 ref., 4 figs.

  18. Prediction of Dissolved Gas Concentrations in Transformer Oil Based on the KPCA-FFOA-GRNN Model

    Directory of Open Access Journals (Sweden)

    Jun Lin

    2018-01-01

    Full Text Available The purpose of analyzing the dissolved gas in transformer oil is to determine the transformer’s operating status and is an important basis for fault diagnosis. Accurate prediction of the concentration of dissolved gas in oil can provide an important reference for the evaluation of the state of the transformer. A combined predicting model is proposed based on kernel principal component analysis (KPCA and a generalized regression neural network (GRNN using an improved fruit fly optimization algorithm (FFOA to select the smooth factor. Firstly, based on the idea of using the dissolved gas ratio of oil to diagnose the transformer fault, gas concentration ratios are also used as characteristic parameters. Secondly, the main parameters are selected from the feature parameters using the KPCA method, and the GRNN is then used to predict the gas concentration in the transformer oil. In the training process of the network, the FFOA is used to select the smooth factor of the neural network. Through a concrete example, it is shown that the method proposed in this paper has better data fitting ability and more accurate prediction ability compared with the support vector machine (SVM and gray model (GM methods.

  19. Burner and dissolver off-gas treatment in HTR fuel reprocessing

    International Nuclear Information System (INIS)

    Barnert-Wiemer, H.; Heidendael, M.; Kirchner, H.; Merz, E.; Schroeder, G.; Vygen, H.

    1979-01-01

    In the reprocessing of HTR fuel, essentially all of the gaseous fission products are released during the heat-end tratment, which includes burning of the graphite matrix and dissolving of the heavy metallic residues in THOREX reagent. Three facilities for off-gas cleaning are described, the status of the facility development and test results are reported. Hot tests with a continuous dissolver for HTR-type fuel (throughput 2 kg HM/d) with a closed helium purge loop have been carried out. Preliminary results of these experiments are reported

  20. On-line fast response device and method for measuring dissolved gas in a fluid

    Science.gov (United States)

    Tutu, Narinder Kumar [Manorville, NY

    2011-01-11

    A method and device for the measurement of dissolved gas within a fluid. The fluid, substantially a liquid, is pumped into a pipe. The flow of the fluid is temporally restricted, creating one or more low pressure regions. A measurement indicative of trapped air is taken before and after the restriction. The amount of dissolved air is calculated from the difference between the first and second measurements. Preferably measurements indicative of trapped air is obtained from one or more pressure transducers, capacitance transducers, or combinations thereof. In the alternative, other methods such as those utilizing x-rays or gamma rays may also be used to detect trapped air. Preferably, the fluid is a hydraulic fluid, whereby dissolved air in the fluid is detected.

  1. Ice Harbor Spillway Dissolved Gas Field Studies: Before and After Spillway Deflectors

    Science.gov (United States)

    2016-07-01

    Steven C. Wilhelms Coastal And Hydraulics Laboratory U.S. Army Engineer Research and Development Center 3909 Halls Ferry Road Vicksburg, Mississippi...Harbor as a measure to reduce the total dissolved gas (TDG) production during spill operations. Three field studies were conducted at the Ice Harbor...significantly reduced for nearly all spill operations with deflectors in place. TDG near the stilling basin was reduced from approximately 150% to

  2. Studies in the dissolver off-gas system for a spent FBR fuel reprocessing plant

    International Nuclear Information System (INIS)

    Heinrich, E.; Huefner, R.; Weirich, F.

    1982-01-01

    Investigations of possible modifications of the process steps of a dissolver off-gas (DOG) system for a spent FBR fuel reprocessing plant are reported. The following operations are discussed: iodine removal from the fuel solution; behaviour of NOsub(x) and iodine in nitric acid off-gas scrubbers at different temperatures and nitric acid concentrations; iodine desorption from the scrub acid; selective absorption of noble gases in refrigerant-12; cold traps. The combination of suitable procedures to produce a total DOG system is described. (U.K.)

  3. Studying the propensity of compounds to supersaturate

    DEFF Research Database (Denmark)

    Palmelund, Henrik; Madsen, Cecilie Maria; Christensen, Jakob Plum

    2016-01-01

    Supersaturating drug delivery systems can enhance the oral bioavailability of poorly soluble drug compounds. Supersaturation of such compounds has been studied in many different ways; however, a more standardized method is required. The rationale of choosing suitable concentrations of supersatura......Supersaturating drug delivery systems can enhance the oral bioavailability of poorly soluble drug compounds. Supersaturation of such compounds has been studied in many different ways; however, a more standardized method is required. The rationale of choosing suitable concentrations...... of supersaturation to study has previously been very inconsistent. This makes comparisons between studies and compounds difficult, as the propensity of compounds to supersaturate varies greatly. This study presents a standardized method to study the supersaturation of drug compounds. The method allows, both......, for a ranking of compounds according to their supersaturation propensity and the effectiveness of precipitation inhibitors. The time-concentration profile of supersaturation and precipitation was studied in situ for 4 different concentrations for 6 model compounds (albendazole, aprepitant, danazol, felodipine...

  4. Dissolved gas geochemical signatures of the ground waters related to the 2011 El Hierro magmatic reactivation

    Science.gov (United States)

    Rodríguez, F.; Hernández, P. A.; Padrón, E.; Pérez, N. M.; Sumino, H.; Melián, G. V.; Padilla, G. D.; Barrancos, J.; Dionis, S.; Nolasco, D.; Calvo, D.; Hernández, I.; Peraza, M. D.

    2012-04-01

    El Hierro Island is the south westernmost and the youngest island of the Canary archipelago (Restinga village (at the southernmost part of El Hierro island), suggesting the existence of a submarine eruption. Since October 12, frequent episodes of, turbulent gas emission and foaming, and the appearance of steamy lava fragments has been observed on the sea surface. Instituto Volcanologico de Canarias (INVOLCAN) started a hydrogeochemical program on August 2011 in order to evaluate the temporal evolution of dissolved gases on four different observation points (vertical and horizontal wells) of El Hierro. Three wells are located on the north of the island (where the seismic activity occurred at the beginning of the volcano-seismic unrest) and one horizontal well (gallery) in the south. At each observation point the concentration of dissolved helium, CO2, N2, O2 and Ar and the isotopic composition of He, C-CO2 and Ar have been measured three times per week. Significant increases on the dissolved gases content, mainly on CO2 and He/CO2 ratio, have been measured at all the observation points prior to the increasing of released seismic energy. Isotopic composition of dissolved helium, measured as 3He/4He ratio, showed an significant increase (from 1-3 RA up to 7.2 RA, being RA the isotopic 3He/4He ratio on air) at all the observation points 20 days before the occurrence of the submarine eruption and these relatively high 3He/4He values have been maintained along the volcanic unrest period. The isotopic composition of CO2 has showed also significant changes in relation to the release of seismic energy. The results observed on this dissolved gases study have been tremendously beneficial on the volcanic surveillance tools to study and forecast the evolution of the seismic-volcanic crisis.

  5. Effect of pulsed corona discharge voltage and feed gas flow rate on dissolved ozone concentration

    Energy Technology Data Exchange (ETDEWEB)

    Prasetyaningrum, A., E-mail: ajiprasetyaningrum@gmail.com; Ratnawati,; Jos, B. [Department of Chemical Engineering, Faculty of Engineering, Diponegoro University Jl. Prof. H. Soedarto Tembalang, Semarang, Central Java, Indonesia, 50276 (Indonesia)

    2015-12-29

    Ozonization is one of the methods extensively used for water purification and degradation of organic materials. Ozone (O{sub 3}) is recognized as a powerful oxidizing agent. Due to its strong oxidability and better environmental friendless, ozone increasing being used in domestic and industrial applications. Current technology in ozone production utilizes several techniques (corona discharge, ultra violet radiation and electrolysis). This experiment aimed to evaluating effect of voltage and gas flow rate on ozone production with corona discharge. The system consists of two net-type stainless steel electrode placed in a dielectric barrier. Three pulsed voltage (20, 30, 40 KV) and flow rate (5, 10, 15 L/min) were prepare for operation variable at high frequency (3.7 kHz) with AC pulsed power supply. The dissolved ozone concentration depends on the applied high-voltage level, gas flow rate and the discharge exposure duration. The ozone concentration increases with decreasing gas flow rate. Dissolved ozone concentrations greater than 200 ppm can be obtained with a minimum voltage 40 kV.

  6. Effect of pulsed corona discharge voltage and feed gas flow rate on dissolved ozone concentration

    International Nuclear Information System (INIS)

    Prasetyaningrum, A.; Ratnawati,; Jos, B.

    2015-01-01

    Ozonization is one of the methods extensively used for water purification and degradation of organic materials. Ozone (O 3 ) is recognized as a powerful oxidizing agent. Due to its strong oxidability and better environmental friendless, ozone increasing being used in domestic and industrial applications. Current technology in ozone production utilizes several techniques (corona discharge, ultra violet radiation and electrolysis). This experiment aimed to evaluating effect of voltage and gas flow rate on ozone production with corona discharge. The system consists of two net-type stainless steel electrode placed in a dielectric barrier. Three pulsed voltage (20, 30, 40 KV) and flow rate (5, 10, 15 L/min) were prepare for operation variable at high frequency (3.7 kHz) with AC pulsed power supply. The dissolved ozone concentration depends on the applied high-voltage level, gas flow rate and the discharge exposure duration. The ozone concentration increases with decreasing gas flow rate. Dissolved ozone concentrations greater than 200 ppm can be obtained with a minimum voltage 40 kV

  7. Effect of pulsed corona discharge voltage and feed gas flow rate on dissolved ozone concentration

    Science.gov (United States)

    Prasetyaningrum, A.; Ratnawati, Jos, B.

    2015-12-01

    Ozonization is one of the methods extensively used for water purification and degradation of organic materials. Ozone (O3) is recognized as a powerful oxidizing agent. Due to its strong oxidability and better environmental friendless, ozone increasing being used in domestic and industrial applications. Current technology in ozone production utilizes several techniques (corona discharge, ultra violet radiation and electrolysis). This experiment aimed to evaluating effect of voltage and gas flow rate on ozone production with corona discharge. The system consists of two net-type stainless steel electrode placed in a dielectric barrier. Three pulsed voltage (20, 30, 40 KV) and flow rate (5, 10, 15 L/min) were prepare for operation variable at high frequency (3.7 kHz) with AC pulsed power supply. The dissolved ozone concentration depends on the applied high-voltage level, gas flow rate and the discharge exposure duration. The ozone concentration increases with decreasing gas flow rate. Dissolved ozone concentrations greater than 200 ppm can be obtained with a minimum voltage 40 kV.

  8. Design, Fabrication, and Shakeout Testing of ATALANTE Dissolver Off-Gas Sorbent-Based Capture System

    International Nuclear Information System (INIS)

    Walker Jr, Joseph Franklin; Jubin, Robert Thomas; Jordan, Jacob A.; Bruffey, Stephanie H.

    2015-01-01

    A sorbent-based capture system designed for integration into the existing dissolver off-gas (DOG) treatment system at the ATelier Alpha et Laboratoires pour ANalyses, Transuraniens et Etudes de retraitement (ATALANTE) facility has been successfully designed and fabricated and has undergone shakeout testing. Discussions with personnel from the ATALANTE facility provided guidance that was used for the design. All components for this system were specified, procured, and received on site at Oak Ridge National Laboratory (ORNL). The system was then fabricated and tested at ORNL to verify operation. Shakeout testing resulted in a simplified system. This system should be easily installed into the existing facility and should be straightforward to operate during future experimental testing. All parts were selected to be compatible with ATALANTE power supplies, space requirements, and the existing DOG treatment system. Additionally, the system was demonstrated to meet all of four design requirements. These include (1) a dissolver off-gas flow rate of ?100 L/h (1.67 L/min), (2) an external temperature of ?50°C for all system components placed in the hot cell, (3) a sorbent bed temperature of ~150°C, and (4) a gas temperature of ~150°C upon entry into the sorbent bed. The system will be ready for shipment and installation in the existing DOG treatment system at ATALANTE in FY 2016.

  9. Water and dissolved gas geochemistry of the monomictic Paterno sinkhole (central Italy

    Directory of Open Access Journals (Sweden)

    Matteo Nocentini

    2012-07-01

    Full Text Available This paper describes the chemical and isotope features of water and dissolved gases from lake Paterno (max. depth 54 m, a sinkhole located in the NE sector of the S. Vittorino plain (Rieti, Central Italy, where evidences of past and present hydrothermal activity exists. In winter (February 2011 lake Paterno waters were almost completely mixed, whereas in summer time (July 2011 thermal and chemical stratifications established. During the stratification period, water and dissolved gas chemistry along the vertical water column were mainly controlled by biological processes, such as methanogenesis, sulfate-reduction, calcite precipitation, denitrification, and NH4 and H2 production. Reducing conditions at the interface between the bottom sediments and the anoxic waters are responsible for the relatively high concentrations of dissolved iron (Fe and manganese (Mn, likely present in their reduced oxidation state. Minerogenic and biogenic products were recognized at the lake bottom even during the winter sampling. At relatively shallow depth the distribution of CH4 and CO2 was controlled by methanotrophic bacteria and photosynthesis, respectively. The carbon isotope signature of CO2 indicates a significant contribution of deep-originated inorganic CO2 that is related to the hydrothermal system feeding the CO2-rich mineralized springs discharging in the surrounding areas of lake Paterno. The seasonal lake stratification likely controls the vertical and horizontal distribution of fish populations in the different periods of the year.

  10. Gas-Liquid Precipitation of water dissolved heavy metal ions using hydrogen sulfide gas

    NARCIS (Netherlands)

    Al Tarazi, M.Y.M.

    2004-01-01

    Precipitation of solids promoted by gas-liquid reactions is applied in many industrial processes such as the production of ammonium phosphate, ammonium sulphate, barium carbonate, calcium carbonate, calcium fluoride, ypsum (calcium sulphate), goethite, sodium bicarbonate, strontium carbonate and

  11. Homogeneous bubble nucleation in binary systems of liquid solvent and dissolved gas

    Czech Academy of Sciences Publication Activity Database

    Němec, Tomáš

    2016-01-01

    Roč. 467, March (2016), s. 26-37 ISSN 0301-0104 R&D Projects: GA ČR GAP101/10/1819; GA ČR GA13-23550S Institutional support: RVO:61388998 Keywords : bubble nucleation * binary nucleation theory * dissolved gas Subject RIV: BJ - Thermodynamics Impact factor: 1.767, year: 2016 http://ac.els-cdn.com/S0301010416000124/1-s2.0-S0301010416000124-main.pdf?_tid=7797c8a0-fb13-11e5-ba55-00000aab0f6c&acdnat=1459849853_b9a5413fefc3e9199e844a9ccc97f514

  12. Dissolved stable noble gas measurements from primary water of Paks NPP

    International Nuclear Information System (INIS)

    Palcsu, L.; Molnar, M.; Szanto, Zs.; Svingor, E.; Futo, I.; Pinter, T.

    2001-01-01

    A sampling and measuring method of noble gases from the primary water circuit of a VVER type NPP was developed to provide relevant information about the kilter of heating rods and detailed additional information about some working parameters. The helium concentrations and 3 He/ 4 He ratios was used to estimate the content of tritium and alpha emitting isotopes of the primary water. By argon content measurements the air penetration and the required hydrazine amount for the oxygen absorption could be estimated with high accuracy. Continuous monitoring of the concentration and isotope ratios of Xe and Kr in the dissolved gas is proved to be a good tool for high sensitivity detection of small leakage of fuel elements. In case of block-3 xenon surplus was detected. The results indicate possible leakage of fuel rods.(author)

  13. The source and behavior of iodine dissolving in groundwater in the Mobara gas field, Japan

    Energy Technology Data Exchange (ETDEWEB)

    Kamei, Gento [Japan Nuclear Cycle Development Inst., Tokai, Ibaraki (Japan). Tokai Works

    2002-06-01

    The groundwater of the Mobara gas-field in Boso peninsula, eastern Japan, contains considerable amount, around 100 mg/L, of iodine besides dissolved methane. Twelve groundwater samples from gas-producing wells to the aquifer within the Kazusa Group in Mobara and Naruto districts have been analyzed for iodine, pH, Eh, HCO{sub 3}{sup -}, NH{sub 4}{sup +}, SiO{sub 2}(aq), {delta}D, {delta}{sup 18}O, {delta}{sup 13}C{sub CH4} and seventeen elements. There is a good correlation between the concentrations of the dissolved elements to those in marine algae. The principal source of the iodine is believed to be algae buried in the sediments and the iodine has been discharged to the porefluid during decomposition of the tissue. The molar ratio of I{sup -}/Cl{sup -} in the groundwater increases from 1.0 x 10{sup 3} to 2.2 x 10{sup 3} with changing the depth from 2000 to 1000 meters below the surface and turns to decrease from 2.2 x 10{sup 3} to 1.8 x 10{sup 3} with going up from 1000 to 500 meters. This tendency may be caused by the variation of buried organisms due to changing the sedimentary environment. The observed variation in the ratio indicates that the iodine discharged in the pore fluid did not migrate significantly after the deposition of the formation. This paper can be regarded as an English version of Japanese article written by Kamei, which was published on the 'Shigen Chishitsu (Resource Geology)' 51(2)145-151(2000). (author)

  14. Direct NMR Monitoring of Phase Separation Behavior of Highly Supersaturated Nifedipine Solution Stabilized with Hypromellose Derivatives.

    Science.gov (United States)

    Ueda, Keisuke; Higashi, Kenjirou; Moribe, Kunikazu

    2017-07-03

    We investigated the phase separation behavior and maintenance mechanism of the supersaturated state of poorly water-soluble nifedipine (NIF) in hypromellose (HPMC) derivative solutions. Highly supersaturated NIF formed NIF-rich nanodroplets through phase separation from aqueous solution containing HPMC derivative. Dissolvable NIF concentration in the bulk water phase was limited by the phase separation of NIF from the aqueous solution. HPMC derivatives stabilized the NIF-rich nanodroplets and maintained the NIF supersaturation with phase-separated NIF for several hours. The size of the NIF-rich phase was different depending on the HPMC derivatives dissolved in aqueous solution, although the droplet size had no correlation with the time for which NIF supersaturation was maintained without NIF crystallization. HPMC acetate and HPMC acetate succinate (HPMC-AS) effectively maintained the NIF supersaturation containing phase-separated NIF compared with HPMC. Furthermore, HPMC-AS stabilized NIF supersaturation more effectively in acidic conditions. Solution 1 H NMR measurements of NIF-supersaturated solution revealed that HPMC derivatives distributed into the NIF-rich phase during the phase separation of NIF from the aqueous solution. The hydrophobicity of HPMC derivative strongly affected its distribution into the NIF-rich phase. Moreover, the distribution of HPMC-AS into the NIF-rich phase was promoted at lower pH due to the lower aqueous solubility of HPMC-AS. The distribution of a large amount of HPMC derivatives into NIF-rich phase induced the strong inhibition of NIF crystallization from the NIF-rich phase. Polymer distribution into the drug-rich phase directly monitored by solution NMR technique can be a useful index for the stabilization efficiency of drug-supersaturated solution containing a drug-rich phase.

  15. Enhancement of organic matter degradation and methane gas production of anaerobic granular sludge by degasification of dissolved hydrogen gas.

    Science.gov (United States)

    Satoh, Hisashi; Bandara, Wasala M K R T W; Sasakawa, Manabu; Nakahara, Yoshihito; Takahashi, Masahiro; Okabe, Satoshi

    2017-11-01

    A hollow fiber degassing membrane (DM) was applied to enhance organic matter degradation and methane gas production of anaerobic granular sludge process by reducing the dissolved hydrogen gas (D-H 2 ) concentration in the liquid phase. DM was installed in the bench-scale anaerobic granular sludge reactors and D-H 2 was removed through DM using a vacuum pump. Degasification improved the organic matter degradation efficiency to 79% while the efficiency was 62% without degasification at 12,000mgL -1 of the influent T-COD concentration. Measurement of D-H 2 concentrations in the liquid phase confirmed that D-H 2 was removed by degasification. Furthermore, the effect of acetate concentrations on the organic matter degradation efficiency was investigated. At acetate concentrations above 3gL -1 , organic matter degradation deteriorated. Degasification enhanced the propionate and acetate degradation. These results suggest that degasification reduced D-H 2 concentration and volatile fatty acids concentrations, prevented pH drop, and subsequent enhanced organic matter degradation. Copyright © 2017 Elsevier Ltd. All rights reserved.

  16. Effects of Total Dissolved Gas on Chum Salmon Fry Incubating in the Lower Columbia River

    Energy Technology Data Exchange (ETDEWEB)

    Arntzen, Evan V.; Hand, Kristine D.; Geist, David R.; Murray, Katherine J.; Panther, Jenny; Cullinan, Valerie I.; Dawley, Earl M.; Elston, Ralph A.

    2008-01-30

    This report describes research conducted by Pacific Northwest National Laboratory in FY 2007 for the U.S. Army Corps of Engineers, Portland District, to characterize the effects of total dissolved gas (TDG) on the incubating fry of chum salmon (Onchorhynchus keta) in the lower Columbia River. The tasks conducted and results obtained in pursuit of three objectives are summarized: * to conduct a field monitoring program at the Ives Island and Multnomah Falls study sites, collecting empirical data on TDG to obtain a more thorough understanding of TDG levels during different river stage scenarios (i.e., high-water year versus low-water year) * to conduct laboratory toxicity tests on hatchery chum salmon fry at gas levels likely to occur downstream from Bonneville Dam * to sample chum salmon sac fry during Bonneville Dam spill operations to determine if there is a physiological response to TDG levels. Chapter 1 discusses the field monitoring, Chapter 2 reports the findings of the laboratory toxicity tests, and Chapter 3 describes the field-sampling task. Each chapter contains an objective-specific introduction, description of the study site and methods, results of research, and discussion of findings. Literature cited throughout this report is listed in Chapter 4. Additional details on the study methdology and results are provided in Appendixes A through D.

  17. U.S. Geological Survey Noble Gas Laboratory’s standard operating procedures for the measurement of dissolved gas in water samples

    Science.gov (United States)

    Hunt, Andrew G.

    2015-08-12

    This report addresses the standard operating procedures used by the U.S. Geological Survey’s Noble Gas Laboratory in Denver, Colorado, U.S.A., for the measurement of dissolved gases (methane, nitrogen, oxygen, and carbon dioxide) and noble gas isotopes (helium-3, helium-4, neon-20, neon-21, neon-22, argon-36, argon-38, argon-40, kryton-84, krypton-86, xenon-103, and xenon-132) dissolved in water. A synopsis of the instrumentation used, procedures followed, calibration practices, standards used, and a quality assurance and quality control program is presented. The report outlines the day-to-day operation of the Residual Gas Analyzer Model 200, Mass Analyzer Products Model 215–50, and ultralow vacuum extraction line along with the sample handling procedures, noble gas extraction and purification, instrument measurement procedures, instrumental data acquisition, and calculations for the conversion of raw data from the mass spectrometer into noble gas concentrations per unit mass of water analyzed. Techniques for the preparation of artificial dissolved gas standards are detailed and coupled to a quality assurance and quality control program to present the accuracy of the procedures used in the laboratory.

  18. Bubble growth as a means to measure dissolved nitrogen concentration in aerated water

    Science.gov (United States)

    Ando, Keita; Yamashita, Tatsuya

    2017-11-01

    Controlling the amount of dissolved gases in water is important, for example, to food processing; it is essential to quantitatively evaluate dissolved gas concentration. The concentration of dissolved oxygen (DO) can be measured by commercial DO meters, but that of dissolved nitrogen (DN) cannot be obtained easily. Here, we propose a means to measure DN concentration based on Epstein-Plesset-type analysis of bubble growth under dissolved gas supersaturation. DO supersaturation in water is produced by oxygen microbubble aeration. The diffusion-driven growth of bubbles nucleated at glass surfaces in contact with the aerated water is first observed. The observed growth is then compared to the extended Epstein-Plesset theory that considers Fick's mass transfer of both DO and DN across bubble interfaces; in this comparison, the unknown DN concentration is treated as a fitting parameter. Comparisons between the experiment and the theory suggest, as expected, that DN can be effectively purged by oxygen microbubble aeration. This study was supported in part by the Mizuho Foundation for the Promotion of Science and by a MEXT Grant-in-Aid for the Program for Leading Graduate Schools.

  19. Probing the regional distribution of pulmonary gas exchange through single-breath gas- and dissolved-phase 129Xe MR imaging.

    Science.gov (United States)

    Kaushik, S Sivaram; Freeman, Matthew S; Cleveland, Zackary I; Davies, John; Stiles, Jane; Virgincar, Rohan S; Robertson, Scott H; He, Mu; Kelly, Kevin T; Foster, W Michael; McAdams, H Page; Driehuys, Bastiaan

    2013-09-01

    Although some central aspects of pulmonary function (ventilation and perfusion) are known to be heterogeneous, the distribution of diffusive gas exchange remains poorly characterized. A solution is offered by hyperpolarized 129Xe magnetic resonance (MR) imaging, because this gas can be separately detected in the lung's air spaces and dissolved in its tissues. Early dissolved-phase 129Xe images exhibited intensity gradients that favored the dependent lung. To quantitatively corroborate this finding, we developed an interleaved, three-dimensional radial sequence to image the gaseous and dissolved 129Xe distributions in the same breath. These images were normalized and divided to calculate "129Xe gas-transfer" maps. We hypothesized that, for healthy volunteers, 129Xe gas-transfer maps would retain the previously observed posture-dependent gradients. This was tested in nine subjects: when the subjects were supine, 129Xe gas transfer exhibited a posterior-anterior gradient of -2.00 ± 0.74%/cm; when the subjects were prone, the gradient reversed to 1.94 ± 1.14%/cm (P exchange caused by differences in lung inflation and posture.

  20. Aerosol and iodine removal system for the dissolver off-gas in a large fuel reprocessing plant

    International Nuclear Information System (INIS)

    Furrer, J.; Wilhelm, J.G.; Jannakos, K.

    1979-01-01

    A newly developed filter combination for the dissolver off-gas in a reprocessing plant with a throughput of 1400 t/y of heavy metal is presented and single filter components are described. The design principle chosen provides for remote handling and direct disposal in waste drums of 200 l volume. The optimization of housings and filter units is studied on true scale components in the simulated dissolver off-gas of a test facility named PASSAT. This facility will be described. PASSAT will be also used for final testing of the SORPTEX process which is under development. Its concept is included in the paper. The design and function of the new multiway sorption filter providing for complete loading of the iodine sorption material and maintaining continuously high decontamznation factors will also be given. Removal efficiencies measured for aerosols and iodine in an existing reprocessing plant are indicated

  1. ANALYSIS OF DISSOLVED METHANE, ETHANE, AND ETHYLENE IN GROUND WATER BY A STANDARD GAS CHROMATOGRAPHIC TECHNIQUE

    Science.gov (United States)

    The measurement of dissolved gases such as methane, ethane, and ethylene in ground water is important in determining whether intrinsic bioremediation is occurring in a fuel- or solvent-contaminated aquifer. A simple procedure is described for the collection and subsequent analys...

  2. Raman spectroscopy measurement of CH4 gas and CH4 dissolved in water for laser remote sensing in water

    Science.gov (United States)

    Somekawa, Toshihiro; Fujita, Masayuki

    2018-04-01

    We examined the applicability of Raman spectroscopy as a laser remote sensing tool for monitoring CH4 in water. The Raman technique has already been used successfully for measurements of CO2 gas in water. In this paper, considering the spectral transmittance of water, third harmonics of Q-switched Nd:YAG laser at 355 nm (UV region) was used for detection of CH4 Raman signals. The Raman signal at 2892 cm-1 from CH4 dissolved in water was detected at a tail of water Raman signal.

  3. Codissolution of calcium hydrogenphosphate and sodium hydrogencitrate in water. Spontaneous supersaturation of calcium citrate increasing calcium bioavailability

    DEFF Research Database (Denmark)

    Hedegaard, Martina Vavrusova; Danielsen, Bente Pia; Garcia, André Castilho

    2018-01-01

    The sparingly soluble calcium hydrogenphosphate dihydrate, co-dissolving in water during dissolution of freely soluble sodium hydrogencitrate sesquihydrate as caused by proton transfer from hydrogencitrate to hydrogenphosphate, was found to form homogenous solutions supersaturated by a factor up...... to 8 in calcium citrate tetrahydrate. A critical hydrogencitrate concentration for formation of homogeneous solutions was found to depend linearly on dissolved calcium hydrogenphosphate: [HCitr2-] = 14[CaHPO4] - 0.05 at 25 °C. The lag phase for precipitation of calcium citrate tetrahydrate......, as identified from FT-IR spectra, from these spontaneously formed supersaturated solutions was several hours, and the time to reach solubility equilibrium was several days. Initial calcium ion activity was found to be almost independent of the degree of supersaturation as determined electrochemically...

  4. Disposal of Kr-85 separated from the dissolver off-gas of a reprocessing plant for LWR fuels

    International Nuclear Information System (INIS)

    Nommensen, O.

    1981-08-01

    The principle of the radiation protection to keep the radiation load of the population as low as possible requires the development of methods for retaining the radionuclide Krypton 85 seperated off the dissolver waste gas of future reprocessing plants for LWR-nuclear fuel elements. In a recommendation of the RSK the long-termed storage of the Kr-85 in a pressure gas bottle and the marine disposal we considered to be disposal methods low in risk. The present work develops a concept for both of the disposal methods and demonstrates their technical feasibility. The comparison of the cost estimations effected for both of the disposal methods shows that the costs related with the marine disposal of the pressure gas bottles amounting to 1.90 DM/kg of reprocessed U fall by the factor 10 below the costs that result from the surface storage of the bottles. In both cases was referred to a reprocessing capacity of 1400 t U/a corresponding to 50 GW installed nuclear power, thereby accumulating approximately 629 PBq (17 MCi) Kr-85 per year. Both concepts project the seperated radioactive inert gas to be filled in pressure gas bottles in a low temperature rectification plant. Each of the 85 bottles to be filled per year contains 7.4 PBq (200 kCi) Kr-85. (orig./HP) [de

  5. Earthworms change the quantity and composition of dissolved organic carbon and reduce greenhouse gas emissions during composting.

    Science.gov (United States)

    Nigussie, Abebe; Bruun, Sander; de Neergaard, Andreas; Kuyper, Thomas W

    2017-04-01

    Dissolved organic carbon (DOC) has recently been proposed as an indicator of compost stability. We assessed the earthworms' effect on DOC content and composition during composting, and linked compost stability to greenhouse gas emissions and feeding ratio. Earthworms reduced total DOC content, indicating larger stability of vermicompost than of thermophilic compost. The concentrations of humic acid and fulvic acid were reduced by earthworms, whereas there was no significant effect on hydrophobic neutrals and hydrophilics. The humic acid fraction was depleted more quickly than the other compounds, indicating humic acid degradation during composting. The optimum feeding ratio decreased DOC content compared to the high feeding ratio. The lowest N 2 O emissions were also observed at the optimum feeding ratio. Our study confirmed the use of DOC content and composition as an indicator of compost stability and suggested that feeding ratio should be considered when assessing the earthworms' effect on stabilisation and greenhouse gas emissions. Copyright © 2017 Elsevier Ltd. All rights reserved.

  6. Rapid analysis of dissolved methane, ethylene, acetylene and ethane using partition coefficients and headspace-gas chromatography.

    Science.gov (United States)

    Lomond, Jasmine S; Tong, Anthony Z

    2011-01-01

    Analysis of dissolved methane, ethylene, acetylene, and ethane in water is crucial in evaluating anaerobic activity and investigating the sources of hydrocarbon contamination in aquatic environments. A rapid chromatographic method based on phase equilibrium between water and its headspace is developed for these analytes. The new method requires minimal sample preparation and no special apparatus except those associated with gas chromatography. Instead of Henry's Law used in similar previous studies, partition coefficients are used for the first time to calculate concentrations of dissolved hydrocarbon gases, which considerably simplifies the calculation involved. Partition coefficients are determined to be 128, 27.9, 1.28, and 96.3 at 30°C for methane, ethylene, acetylene, and ethane, respectively. It was discovered that the volume ratio of gas-to-liquid phase is critical to the accuracy of the measurements. The method performance can be readily improved by reducing the volume ratio of the two phases. Method validation shows less than 6% variation in accuracy and precision except at low levels of methane where interferences occur in ambient air. Method detection limits are determined to be in the low ng/L range for all analytes. The performance of the method is further tested using environmental samples collected from various sites in Nova Scotia.

  7. The isotopic chemical and dissolved gas concentrations in groundwater near Venterstad, Cape Province

    International Nuclear Information System (INIS)

    Vogel, J.C.; Talma, A.S.; Heaton, T.H.E.

    1980-01-01

    Groundwater was collected for a multi parameter investigation from 27 boreholes within a radius of 120 km from Venterstad (Cape Province). The samples were analysed for the isotopes carbon-14, carbon-13, oxygen-18, tritium and radon-222, for the dissolved gases nitrogen, oxygen, argon, methane and helium and for the major ionic species. These data, with those collected during previous investigations of the flooding of the Orange Fish tunnel, are used to discuss the geohydrology of the area. Three water types of different origin were delineated

  8. Nucleation and droplet growth from supersaturated vapor at temperatures below the triple point temperature

    DEFF Research Database (Denmark)

    Toxværd, Søren

    2016-01-01

    temperature Ttr.p. crystallizes via a liquid droplet is an example of Ostwald's step rule. The homogeneous nucleation in the supersaturated gas is not to a crystal, but to a liquid-like critical nucleus. We have for the first time performed constant energy (NVE) Molecular Dynamics (MD) of homogeneous...... nucleation without the use of a thermostat. The simulations of homogeneous nucleation in a Lennard-Jones system from supersaturated vapor at temperatures below Ttr.p. reveals that the nucleation to a liquid-like critical nucleus is initiated by a small cold cluster [S. Toxvaerd, J. Chem. Phys. \\textbf{143...

  9. Separation of the fission product noble gases krypton and xenon from dissolver off-gas in reprocessing HTGR-fuel

    Energy Technology Data Exchange (ETDEWEB)

    Bohnenstingl, J.; Djoa, S. H.; Laser, M.; Mastera, S.; Merz, E.; Morschl, P.

    1976-04-15

    This paper describes a process developed for the retainment and separation of volatile (3H, 129 +131I) and gaseous (85Kr, Xe) fission products from the off-gas produced during dissolution of HTGR-fuel. To prevent unnecessary dilution of liberated noble gases by surrounding atmosphere, a helium purge-gas cycle is applied to enable a coarse fractionating of krypton and xenon by cold-trapping at about 80 deg K after precleaning the gas stream. The process consists of the following steps: deposition of droplets and solid aerosols; chemisorption of iodine on silver impregnated silica gel; catalytic removal of nitrogen oxides and oxygen; drying of the process gas stream; final filtering of abraded solids; deposition of xenon in solid form at 80 deg K and low subpressure; deposition of krypton in solid form at 80 deg K after compression to about 6 bar; decontamination of 85krypton-containing xenon by batch distillation for eventual industrial utilization; and removal of nitrogen and argon enrichment during continuous operation in the purge-gas stream by inleaking air with charcoal. A continuously operating dissolver vessel, closed to the surrounding atmosphere, yields a very high content of noble gases, e.g., 0.35 vol % krypton and 2.0 vol % xenon. The presented off-gas treatment unit is operated in cold runs with 1/3 of the full capacity and can treat about 1 m3 STP/h helium, corresponding to a quantity of about 10,000 MW(e) HTGR-fuel reprocessing plant.

  10. Separation of the fission product noble gases krypton and xenon from dissolver off-gas in reprocessing HTGR-fuel

    International Nuclear Information System (INIS)

    Bohnenstingl, J.; Djoa, S.H.; Laser, M.; Mastera, S.; Merz, E.; Morschl, P.

    1976-01-01

    This paper describes a process developed for the retainment and separation of volatile ( 3 H, 129+131 I) and gaseous ( 85 Kr, Xe) fission products from the off-gas produced during dissolution of HTGR-fuel. To prevent unnecessary dilution of liberated noble gases by surrounding atmosphere, a helium purge-gas cycle is applied to enable a coarse fractionating of krypton and xenon by cold-trapping at about 80 0 K after precleaning the gas stream. The process consists of the following steps: deposition of droplets and solid aerosols; chemisorption of iodine on silver impregnated silica gel; catalytic removal of nitrogen oxides and oxygen; drying of the process gas stream; final filtering of abraded solids; deposition of xenon in solid form at 80 0 K and low subpressure; deposition of krypton in solid form at 80 0 K after compression to about 6 bar; decontamination of 85 Kr-containing xenon by batch distillation for eventual industrial utilization; and removal of nitrogen and argon enrichment during continuous operation in the purge-gas stream by inleaking air with charcoal. A continuously operating dissolver vessel, closed to the surrounding atmosphere, yields a very high content of noble gases, i.e., 0.35 vol % krypton and 2.0 vol % xenon. The presented off-gas treatment unit is operated in cold runs with 1 / 3 of the full capacity and can treat about 1 m 3 STP/h helium, corresponding to a quantity of about 10,000 MW/sub e/ HTGR-fuel reprocessing plant

  11. Pilot plant development for adsorptive krypton separation from dissolver off-gas

    International Nuclear Information System (INIS)

    Ringel, H.; Printz, R.

    1987-01-01

    In view of hot cell application a separation process was investigated for the retention of Kr-85 from gaseous effluents. In the flow sheet only adsorption beds are applied. The most efficient process scheme is adsorption of the noble gas on activated charcoal and thereafter separation of the coadsorbed gas species like N 2 , O 2 , Xe and CO 2 from the krypton by gas chromatography. Adsorption is at normal pressure and low temperatures of up to -160 0 C, whereas desorption is at elevated temperatures and under helium purge. Influences on the process operation like off-gas composition, adsorption temperatures and adsorbent are experimentally investigated, as well as the behavior of trace impurities in the adsorption columns. On the basis of pilot plant operation the main components for a full scale facility are being designed

  12. Gas transport below artificial recharge ponds: insights from dissolved noble gases and a dual gas (SF6 and 3He) tracer experiment.

    Science.gov (United States)

    Clark, Jordan F; Hudson, G Bryant; Avisar, Dror

    2005-06-01

    A dual gas tracer experiment using sulfur hexafluoride (SF6) and an isotope of helium (3He) and measurements of dissolved noble gases was performed at the El Rio spreading grounds to examine gas transport and trapped air below an artificial recharge pond with a very high recharge rate (approximately 4 m day(-1)). Noble gas concentrations in the groundwater were greater than in surface water due to excess air formation showing that trapped air exists below the pond. Breakthrough curves of SF6 and 3He at two nearby production wells were very similar and suggest that nonequilibrium gas transfer was occurring between the percolating water and the trapped air. At one well screened between 50 and 90 m below ground, both tracers were detected after 5 days and reached a maximum at approximately 24 days. Despite the potential dilution caused by mixing within the production well, the maximum concentration was approximately 25% of the mean pond concentration. More than 50% of the SF6 recharged was recovered by the production wells during the 18 month long experiment. Our results demonstrate that at artificial recharge sites with high infiltration rates and moderately deep water tables, transport times between recharge locations and wells determined with gas tracer experiments are reliable.

  13. Cryogenic separation of krypton and xenon from dissolver off-gas

    Energy Technology Data Exchange (ETDEWEB)

    Bohnenstingl, J.; Heidendael, M.; Laser, M.; Mastera, S.; Merz, E.

    1976-03-15

    Although the release of fission product noble gas Kr-85 has not posed a health problem to date, a process is being developed for the removal and storage of fission product noble gases from dissolution process stream of fuel reprocessing. The separation process described for noble gas in air being proved in semi-technical scale includes cryogenic distillation and consists of the following steps: (1) removal of 129 +131iodine on silver-coated silica gel; (2) deposition of particulate materials by HEPA-filters; (3) elimination of O2 and NOx by catalytic conversion with H2/ to N2 and H2O; (4) drying of the gas stream with molecular sieve; (5) deposition of xenon in solid form at about 80 K, while the remaining gas components are liquified; (6) enrichment of Kr by low temperature distillation of liquid-gas mixture; (7) withdrawal of the highly enriched Kr-fraction at the bottom of the still to be bottled in pressurized steel cylinders for final disposal; and (8) purification of Kr-85 contaminated Xe for further industrial reuse by batch distillation.

  14. Modular design of a reprocessing plant dissolver off-gas system. Variations, flexibility and stage of development

    International Nuclear Information System (INIS)

    Henrich, E.; Huefner, R.

    1984-01-01

    Simple and economic control of the volatile radionuclides in a reprocessing plant requires two equally important prerequisites: suitable processing in the plant head-end and reliable operation of the dissolver off-gas (DOG) purification system. A small number of DOG purification modules was selected from various alternatives. The major selection criteria are removal efficiency, simplicity, convenient operating conditions and flexibility that provide compatibility with other off-gas treatment steps, subsequent waste treatment and different processing modes in the head-end. The behaviour of noxious materials was investigated in nitric acid off-gas scrubbers of different design and for a wide range of operating modes and conditions. A concentration range of nitric acid from very dilute to hyperazeotropic concentrations and a temperature range from -55 deg. C to above room temperature as well as the use of hydrogen peroxide were studied on an engineering scale. Nitrous gases and iodine can be removed to the trace level at special operating modes. Aerosol and iodine filters are discussed briefly. A selective absorption process using CF 2 Cl 2 solvent for noble gas and 14 C removal was developed on a laboratory scale. It operates at low temperatures and atmospheric pressure. Xe and Kr were separated using two absorption columns. Pilot-plant scale noble gas scrubbers are under construction and are being integrated into the existing test facility. A series of process steps has been chosen for integrated process demonstration runs on an engineering scale. The integrated DOG system consists of several scrubbers and filters operating at atmospheric pressure. The temperature decreases stepwise, without producing large changes in the opposite direction, providing compatibility within the process train

  15. Influence of dissolved gas and temperature on the light yield of new liquid scintillators

    CERN Document Server

    Buontempo, S; Golovkin, S V; Martellotti, G; Medvedkov, A M; Penso, G; Soloviev, A S; Vasilchenko, V G

    1999-01-01

    Sixteen new liquid scintillators, emitting green light, were studied. They are based on four solvents combined with four dopants. The influence of different gas atmospheres was studied. In particular it was shown that by keeping these liquid scintillators in vacuum or in a neutral gas, the light yield increases up to 32~\\% at 20 $^{\\circ}$C and for the best solvent-dopant combinations. The dependance of the light yield on temperature was also studied for these scintillators. In the 20--60 $^{\\circ}$C interval, some exhibit a light yield variation of $\\sim$ 3 \\% which is smaller than that of the NE 102A plastic scintillator.

  16. Earthworms change the quantity and composition of dissolved organic carbon and reduce greenhouse gas emissions during composting

    DEFF Research Database (Denmark)

    Nigatu, Abebe Nigussie; Bruun, Sander; de Neergaard, Andreas

    2017-01-01

    Dissolved organic carbon (DOC) has recently been proposed as an indicator of compost stability. We assessed the earthworms' effect on DOC content and composition during composting, and linked compost stability to greenhouse gas emissions and feeding ratio. Earthworms reduced total DOC content......, indicating larger stability of vermicompost than of thermophilic compost. The concentrations of humic acid and fulvic acid were reduced by earthworms, whereas there was no significant effect on hydrophobic neutrals and hydrophilics. The humic acid fraction was depleted more quickly than the other compounds......, indicating humic acid degradation during composting. The optimum feeding ratio decreased DOC content compared to the high feeding ratio. The lowest N2O emissions were also observed at the optimum feeding ratio. Our study confirmed the use of DOC content and composition as an indicator of compost stability...

  17. Feasibility study for evaluating cumulative exposure of downstream migrant juvenile salmonids to total dissolved gas. Final report

    International Nuclear Information System (INIS)

    Abernethy, C.S.; Dauble, D.D.; Johnson, R.L.

    1997-11-01

    A feasibility study was initiated to determine if downstream migrant salmonids could be monitored to determine potential relationships between total dissolved gas (TDG) exposure and signs of gas bubble trauma (GBT). The primary objectives were to: (1) establish logistical requirements for in-river monitoring of TDG exposure, including net pen design, deployment, and navigation constraints; (2) resolve uncertainties associated with effects of the net pen on fish behavior; (3) test the accuracy and precision of in-river monitoring equipment used to measure fish distribution and water quality; and (4) determine the application of hydrologic/flow models to predictions of TDG exposure. In-river measurements included water velocity, boat position, and selected water quality parameters (temperature, dissolved oxygen, pH, depth, conductivity). Fish distribution within the net pen was monitored using scanning sonar, and a split-beam echo sounder was used to evaluate vertical distribution of fish m in the river adjacent to the net pen. Three test drifts were conducted from late July through late August. The studies demonstrated that it was feasible to assemble and deploy a large net pen for mobile monitoring of TDG exposure. Accurate monitoring of vertical and lateral distribution of smolts was performed, and diel differences in behavior were documented. Further, the fish sounded in response to researcher activity on the perimeter platform. Thus, in-transit monitoring for GBT or mortality would affect fish depth distribution and exposure to TDG. Principal recommendations for future studies are directed at improving maneuverability of the net pen in adverse weather conditions and applying new acoustics technology to simultaneously collect fish distribution data from within and outside of the pen. 6 refs., 17 figs., 2 tabs

  18. Investigation of sulphide in core drilled boreholes KLX06, KAS03 and KAS09 at Laxemar and Aespoe Chemical-, microbiological- and dissolved gas data from groundwater in four borehole sections

    Energy Technology Data Exchange (ETDEWEB)

    Rosdahl, Anette (Geosigma AB (Sweden)); Pedersen, Karsten; Hallbeck, Lotta (Microbial Analytics Sweden AB (Sweden)); Wallin, Bill (Geokema AB (Sweden))

    2011-01-15

    This report describes a study performed during 2009 which focused on the production of sulphide (microbial sulphate reduction) in deep groundwater that was implemented in the core drilled boreholes KLX06, -475 to 482 meter above sea level, m a s l, KAS03,-97 to 241 and -613 to 984 m a s l, and KAS09, -96 to -125 m a s l, at Laxemar and Aspo. The study aimed to increase knowledge of background groundwater levels of sulphide and its variations in time and space through the analysis of sulphide and parameters related to sulphide production. Sampling of groundwater was conducted in three core drilled boreholes of varying age as time series with continuous pumping and as single samples. The analysis program covered chemical parameters (pH, chloride, sulphate, iron, and organic carbon), dissolved gas composition, stable isotopes in groundwater (delta2H, delta18O, delta34S, delta13C), stable isotopes of gaseous compounds (delta2H, delta13C, delta18O), microbiological parameters (sulphate- and iron reducing bacteria, SRB and IRB), phthalates and low molecular mass organic acids (LMMOA). The sampling in KLX06 was carried out as time series with a 9 week pause in pumping. When the water volume discharged was about 150 times that of the packer-isolated borehole section, sulphides decreased from 7 mg L-1 to 0.05 mg L-1 and the salinity increased from 740 to 1,480 mg L-1. After a 9 weeks pause in pumping, the sulphide concentration and salinity again approached the original values, i.e. 7 mg L-1 of sulphide and 450 mg L-1 of chloride. The SRB and IRB showed high concentrations that were reduced during pumping in the borehole. The water in the standpipe which has a different water composition than the groundwater, also showed similar high concentrations of sulphide and SRB. The standpipe is a plastic pipe in the wider upper part of the borehole; connected with the tube from the packer of the borehole section and used to accommodate a filter and a groundwater pump when collecting

  19. Investigation of sulphide in core drilled boreholes KLX06, KAS03 and KAS09 at Laxemar and Aespoe: Chemical-, microbiological- and dissolved gas data from groundwater in four borehole sections

    International Nuclear Information System (INIS)

    Rosdahl, Anette; Pedersen, Karsten; Hallbeck, Lotta; Wallin, Bill

    2011-01-01

    This report describes a study performed during 2009 which focused on the production of sulphide (microbial sulphate reduction) in deep groundwater that was implemented in the core drilled boreholes KLX06, -475 to 482 meter above sea level, m a s l, KAS03,-97 to 241 and -613 to 984 m a s l, and KAS09, -96 to -125 m a s l, at Laxemar and Aspo. The study aimed to increase knowledge of background groundwater levels of sulphide and its variations in time and space through the analysis of sulphide and parameters related to sulphide production. Sampling of groundwater was conducted in three core drilled boreholes of varying age as time series with continuous pumping and as single samples. The analysis program covered chemical parameters (pH, chloride, sulphate, iron, and organic carbon), dissolved gas composition, stable isotopes in groundwater (δ 2 H, δ 18 O, δ 34 S, δ 13 C), stable isotopes of gaseous compounds (δ 2 H, δ 13 C, δ 18 O), microbiological parameters (sulphate- and iron reducing bacteria, SRB and IRB), phthalates and low molecular mass organic acids (LMMOA). The sampling in KLX06 was carried out as time series with a 9 week pause in pumping. When the water volume discharged was about 150 times that of the packer-isolated borehole section, sulphides decreased from 7 mg L -1 to 0.05 mg L -1 and the salinity increased from 740 to 1,480 mg L -1 . After a 9 weeks pause in pumping, the sulphide concentration and salinity again approached the original values, i.e. 7 mg L -1 of sulphide and 450 mg L -1 of chloride. The SRB and IRB showed high concentrations that were reduced during pumping in the borehole. The water in the standpipe which has a different water composition than the groundwater, also showed similar high concentrations of sulphide and SRB. The standpipe is a plastic pipe in the wider upper part of the borehole; connected with the tube from the packer of the borehole section and used to accommodate a filter and a groundwater pump when collecting

  20. Hydrogeochemical processes controlling water and dissolved gas chemistry at the Accesa sinkhole (southern Tuscany, central Italy

    Directory of Open Access Journals (Sweden)

    Franco Tassi

    2014-05-01

    Full Text Available The 38.5 m deep Lake Accesa is a sinkhole located in southern Tuscany (Italy that shows a peculiar water composition, being characterized by relatively high total dissolved solids (TDS values (2 g L-1 and a Ca(Mg-SO4 geochemical facies. The presence of significant amounts of extra-atmospheric gases (CO2 and CH4, which increase their concentrations with depth, is also recognized. These chemical features, mimicking those commonly shown by volcanic lakes fed by hydrothermal-magmatic reservoirs, are consistent with those of mineral springs emerging in the study area whose chemistry is produced by the interaction of meteoric-derived waters with Mesozoic carbonates and Triassic evaporites. Although the lake has a pronounced thermocline, water chemistry does not show significant changes along the vertical profile. Lake water balance calculations demonstrate that Lake Accesa has >90% of its water supply from sublacustrine springs whose subterranean pathways are controlled by the local structural assessment that likely determined the sinking event, the resulting funnel-shape being then filled by the Accesa waters. Such a huge water inflow from the lake bottom (~9·106 m3 yr-1 feeds the lake effluent (Bruna River and promotes the formation of water currents, which are able to prevent the establishment of a vertical density gradient. Consequently, a continuous mixing along the whole vertical water column is established. Changes of the drainage system by the deep-originated waters in the nearby former mining district have strongly affected the outflow rates of the local mineral springs; thus, future intervention associated with the ongoing remediation activities should carefully be evaluated to preserve the peculiar chemical features of Lake Accesa.

  1. A Gas Chromatographic Method for the Determination of Bicarbonate and Dissolved Gases

    Directory of Open Access Journals (Sweden)

    John H. Loughrin

    2017-11-01

    Full Text Available A gas chromatographic method for the rapid determination of aqueous carbon dioxide and its speciation into solvated carbon dioxide and bicarbonate is presented. One-half mL samples are injected through a rubber septum into 20-mL vials that are filled with 9.5 mL of 0.1 N HCl. A one mL portion of the headspace is withdrawn and injected onto a gas chromatograph equipped with a thermal conductivity detector. Using the dimensionless Henry's constant for carbon dioxide and an adaptation of the Henderson-Hasselbalch equation, carbon dioxide in the samples can be categorized among solvated, bicarbonate, and carbonate forms. Natural water samples as well as wastewater from a municipal sewage treatment plant and a swine rearing operation were analyzed by this method and the results compared favorably to those obtained by titration. Samples stored for up to 5 weeks showed no significant changes in carbon dioxide concentrations. In addition, using flame ionization and electron capture detectors, methane and nitrous oxide concentrations in the samples were also measured.

  2. Air-sea gas transfer in a shallow, flowing and coastal environment estimated by dissolved inorganic carbon and dissolved oxygen analyses

    Digital Repository Service at National Institute of Oceanography (India)

    Abe, O.; Watanabe, A.; Sarma, V.V.S.S.; Matsu, Y.; Yamano, H.; Yoshida, N.; Saino, T.

    crest and an outflow through a prominent 8 channel, whereas southern wind conditions this pattern is weakened or disturbed 9 (Yamano et al., 1998). Thus, during northern to northeastern winds, metabolic activities 10 with respect to primary production...). Dissolved oxygen was almost less than saturation during the observation period, 16 except on 8 March (Fig. 3f), when the daytime concentration exceeded saturation level 17 due to the increase of net productivity associated with solar radiation. DIC and DO...

  3. Geopressured-geothermal test of the EDNA Delcambre No. 1 well, Tigre Lagoon Field, Vermilion Parish, Louisiana: Analysis of water and dissolved natural gas: Final report

    Energy Technology Data Exchange (ETDEWEB)

    Hankind, B.E.; Karkalits, O.C.

    1978-09-01

    The presence of large volumes of hot water (250-425 F) containing dissolved natural gas in the Gulf of Mexico coastal areas at depths of 5,000 to 25,000 feet (the geopressured zone) has been known for several years. Because natural gas and oil from conventional production methods were relatively inexpensive prior to 1973, and because foreign oil was readily available, no economic incentive existed for developing this resource. With the oil embargo and the resulting rapid escalation in prices of oil and gas since 1973, a new urgency exists for examining the economic potential of the geopressured-geothermal resource. The main objective of the research reported here was to determine the volume of gas dissolved in the geopressured water, as well as the qualitative and quantitative composition of the water and the dissolved gas. A further objective was to use an existing shut-in gas well so that drilling time and the attendant costs could be avoided.

  4. Continuous high-frequency dissolved O2/Ar measurements by equilibrator inlet mass spectrometry.

    Science.gov (United States)

    Cassar, Nicolas; Barnett, Bruce A; Bender, Michael L; Kaiser, Jan; Hamme, Roberta C; Tilbrook, Bronte

    2009-03-01

    The oxygen (O(2)) concentration in the surface ocean is influenced by biological and physical processes. With concurrent measurements of argon (Ar), which has similar solubility properties as oxygen, we can remove the physical contribution to O(2) supersaturation and determine the biological oxygen supersaturation. Biological O(2) supersaturation in the surface ocean reflects the net metabolic balance between photosynthesis and respiration, i.e., the net community productivity (NCP). We present a new method for continuous shipboard measurements of O(2)/Ar by equilibrator inlet mass spectrometry (EIMS). From these measurements and an appropriate gas exchange parametrization, NCP can be estimated at high spatial and temporal resolution. In the EIMS configuration, seawater from the ship's continuous intake flows through a cartridge enclosing a gas-permeable microporous membrane contactor. Gases in the headspace of the cartridge equilibrate with dissolved gases in the flowing seawater. A fused-silica capillary continuously samples headspace gases, and the O(2)/Ar ratio is measured by mass spectrometry. The ion current measurements on the mass spectrometer reflect the partial pressures of dissolved gases in the water flowing through the equilibrator. Calibration of the O(2)/Ar ion current ratio (32/40) is performed automatically every 2 h by sampling ambient air through a second capillary. A conceptual model demonstrates that the ratio of gases reaching the mass spectrometer is dependent on several parameters, such as the differences in molecular diffusivities and solubilities of the gases. Laboratory experiments and field observations performed by EIMS are discussed. We also present preliminary evidence that other gas measurements, such as N(2)/Ar and pCO(2) measurements, may potentially be performed with EIMS. Finally, we compare the characteristics of the EIMS with the previously described membrane inlet mass spectrometry (MIMS) approach.

  5. Time-dependent analysis of dissolver off-gas cleaning installations in a reprocessing plant

    International Nuclear Information System (INIS)

    Nagel, K.; Furrer, J.; Becker, G.; Obrowski, W.; Seghal, Y.P.; Weymann, J.

    1983-01-01

    The iodine- and aerosol-filtering test facility PASSAT of the Nuclear Research Centre in Karlsruhe has been investigated using a method which allows time-dependent analyses under accident conditions. This method which is closely related to fault-tree analysis needs subdivision in barriers of the system, and their logical combination in a tree. The barriers have binary states: defect and intact. The defect state will be described by a fault tree, whereas the intact state includes dependences of a barrier operation on physical parameters. The intact state enables time-dependent calculations. Calculations have been done for iodine filtering, because the best known entrance data are given. Results demonstrate clearly that the amount of iodine released increases only if both heaters failed, which heat the off-gas from 30 0 C to 80 0 C and then to 130 0 C. Additionally the integrated amount of iodine released depends on time period between the failures of the heaters

  6. Organic iodine removal from simulated dissolver off-gas systems utilizing silver-exchanged mordenite

    International Nuclear Information System (INIS)

    Jubin, R.T.

    1981-01-01

    The removal of methyl iodide by adsorption onto silver mordenite was studied using a simulated off-gas from the fuel dissolution step of a nuclear fuel reprocessing plant. The adsorption of methyl iodide on silver mordenite was examined for the effect of NO/sub x/, humidity, iodine concentration, filter temperature, silver loadings and filter pretreatment. The highest iodine loading achieved in these tests was 142 mg CH 3 I per g of substrate on fully exchanged zeolite, approximately the same as elemental iodine loadings. A filter using fully exchanged silver mordenite operating at 200 0 C obtained higher iodine loadings than a similar filter operating at 150 0 C. Pretreatment of the sorbent bed with hydrogen rather than dry air, at a temperature of 200 0 C, also improved the loading. Variations in the methyl iodide concentration had minimal effects on the overall loading. Filters exposed to moist air streams attained higher loadings than those in contact with dry air. Partially exchanged silver mordenite achieved higher silver utilizations than the fully exchanged material. The partially exchanged mordenite also achieved higher loadings at 200 0 C than at 250 0 C. The iodine loaded onto these beds was not stripped at 500 0 C by either 4.5% hydrogen or 100% hydrogen; however, the iodine could be removed by air at 500 0 C, and the bed could be reloaded. A study of the regeneration characteristics of fully exchanged silver mordenite indicates limited adsorbent capacity after complete removal of the iodine with 4.5% hydrogen in the regeneration gas stream at 500 0 C. The loss of adsorbent capacity is much higher for silver mordenite regenerated in a stainless steel filter housing than in a glass filter housing

  7. pH-Induced precipitation behavior of weakly basic compounds: determination of extent and duration of supersaturation using potentiometric titration and correlation to solid state properties.

    Science.gov (United States)

    Hsieh, Yi-Ling; Ilevbare, Grace A; Van Eerdenbrugh, Bernard; Box, Karl J; Sanchez-Felix, Manuel Vincente; Taylor, Lynne S

    2012-10-01

    To examine the precipitation and supersaturation behavior of ten weak bases in terms of the relationship between pH-concentration-time profiles and the solid state properties of the precipitated material. Initially the compound was dissolved at low pH, followed by titration with base to induce precipitation. Upon precipitation, small aliquots of acid or base were added to induce slight subsaturation and supersaturation respectively and the resultant pH gradient was determined. The concentration of the unionized species was calculated as a function of time and pH using mass and charge balance equations. Two patterns of behavior were observed in terms of the extent and duration of supersaturation arising following an increase in pH and this behavior could be rationalized based on the crystallization tendency of the compound. For compounds that did not readily crystallize, an amorphous precipitate was formed and a prolonged duration of supersaturation was observed. For compounds that precipitated to crystalline forms, the observed supersaturation was short-lived. This study showed that supersaturation behavior has significant correlation with the solid-state properties of the precipitate and that pH-metric titration methods can be utilized to evaluate the supersaturation behavior.

  8. Inhibition of crystal nucleation and growth by water-soluble polymers and its impact on the supersaturation profiles of amorphous drugs.

    Science.gov (United States)

    Ozaki, Shunsuke; Kushida, Ikuo; Yamashita, Taro; Hasebe, Takashi; Shirai, Osamu; Kano, Kenji

    2013-07-01

    The impact of water-soluble polymers on drug supersaturation behavior was investigated to elucidate the role of water-soluble polymers in enhancing the supersaturation levels of amorphous pharmaceuticals. Hydroxypropyl methylcellulose (HPMC), polyvinylpyrrolidone (PVP), and Eudragit L-100 (Eudragit) were used as representative polymers, and griseofulvin and danazol were used as model drugs. Supersaturation profiles of amorphous drugs were measured in biorelevant dissolution tests. Crystal growth rate was measured from the decrease in dissolved drug concentration in the presence of seed crystals. Nucleation kinetics was evaluated by measuring the induction time for nucleation. All experiments were performed in the presence and absence of polymers. The degree of supersaturation of the amorphous model drugs increased with an increase in the inhibitory efficiency of polymers against crystal nucleation and growth (HPMC > PVP > Eudragit). In the presence of HPMC, the addition of seed crystals diminished the supersaturation ratio dramatically for griseofulvin and moderately for danazol. The results demonstrated that the polymers contributed to drug supersaturation by inhibiting both nucleation and growth. The effect of the polymers was drug dependent. The detailed characterization of polymers would allow selection of appropriate crystallization inhibitors and a planned quality control strategy for the development of supersaturable formulations. Copyright © 2013 Wiley Periodicals, Inc.

  9. Using dissolved gas analysis to investigate the performance of an organic carbon permeable reactive barrier for the treatment of mine drainage

    Science.gov (United States)

    Williams, R.L.; Mayer, K.U.; Amos, R.T.; Blowes, D.W.; Ptacek, C.J.; Bain, J.G.

    2007-01-01

    The strongly reducing nature of permeable reactive barrier (PRB) treatment materials can lead to gas production, potentially resulting in the formation of gas bubbles and ebullition. Degassing in organic C based PRB systems due to the production of gases (primarily CO2 and CH4) is investigated using the depletion of naturally occurring non-reactive gases Ar and N2, to identify, confirm, and quantify chemical and physical processes. Sampling and analysis of dissolved gases were performed at the Nickel Rim Mine Organic Carbon PRB, which was designed for the treatment of groundwater contaminated by low quality mine drainage characterized by slightly acidic pH, and elevated Fe(II) and SO4 concentrations. A simple 4-gas degassing model was used to analyze the dissolved gas data, and the results indicate that SO4 reduction is by far the dominant process of organic C consumption within the barrier. The data provided additional information to delineate rates of microbially mediated SO4 reduction and confirm the presence of slow and fast flow zones within the barrier. Degassing was incorporated into multicomponent reactive transport simulations for the barrier and the simulations were successful in reproducing observed dissolved gas trends.

  10. Technical Note: Precise quantitative measurements of total dissolved inorganic carbon from small amounts of seawater using a gas chromatographic system

    Directory of Open Access Journals (Sweden)

    T. Hansen

    2013-10-01

    Full Text Available Total dissolved inorganic carbon (CT is one of the most frequently measured parameters used to calculate the partial pressure of carbon dioxide in seawater. Its determination has become increasingly important because of the rising interest in the biological effects of ocean acidification. Coulometric and infrared detection methods are currently favored in order to precisely quantify CT. These methods however are not sufficiently validated for CT measurements of biological experiments manipulating seawater carbonate chemistry with an extended CT measurement range (~1250–2400 μmol kg–1 compared to natural open ocean seawater (~1950–2200 μmol kg−1. The requirement of total sample amounts between 0.1–1 L seawater in the coulometric- and infrared detection methods potentially exclude their use for experiments working with much smaller volumes. Additionally, precise CT analytics become difficult with high amounts of biomass (e.g., phytoplankton cultures or even impossible in the presence of planktonic calcifiers without sample pre-filtration. Filtration however, can alter CT concentration through gas exchange induced by high pressure. Addressing these problems, we present precise quantification of CT using a small, basic and inexpensive gas chromatograph as a CT analyzer. Our technique is able to provide a repeatability of ±3.1 μmol kg−1, given by the pooled standard deviation over a CT range typically applied in acidification experiments. 200 μL of sample is required to perform the actual CT measurement. The total sample amount needed is 12 mL. Moreover, we show that sample filtration is applicable with only minor alteration of the CT. The method is simple, reliable and with low cumulative material costs. Hence, it is potentially attractive for all researchers experimentally manipulating the seawater carbonate system.

  11. Identification of transformer fault based on dissolved gas analysis using hybrid support vector machine-modified evolutionary particle swarm optimisation

    Science.gov (United States)

    2018-01-01

    Early detection of power transformer fault is important because it can reduce the maintenance cost of the transformer and it can ensure continuous electricity supply in power systems. Dissolved Gas Analysis (DGA) technique is commonly used to identify oil-filled power transformer fault type but utilisation of artificial intelligence method with optimisation methods has shown convincing results. In this work, a hybrid support vector machine (SVM) with modified evolutionary particle swarm optimisation (EPSO) algorithm was proposed to determine the transformer fault type. The superiority of the modified PSO technique with SVM was evaluated by comparing the results with the actual fault diagnosis, unoptimised SVM and previous reported works. Data reduction was also applied using stepwise regression prior to the training process of SVM to reduce the training time. It was found that the proposed hybrid SVM-Modified EPSO (MEPSO)-Time Varying Acceleration Coefficient (TVAC) technique results in the highest correct identification percentage of faults in a power transformer compared to other PSO algorithms. Thus, the proposed technique can be one of the potential solutions to identify the transformer fault type based on DGA data on site. PMID:29370230

  12. Identification of transformer fault based on dissolved gas analysis using hybrid support vector machine-modified evolutionary particle swarm optimisation.

    Directory of Open Access Journals (Sweden)

    Hazlee Azil Illias

    Full Text Available Early detection of power transformer fault is important because it can reduce the maintenance cost of the transformer and it can ensure continuous electricity supply in power systems. Dissolved Gas Analysis (DGA technique is commonly used to identify oil-filled power transformer fault type but utilisation of artificial intelligence method with optimisation methods has shown convincing results. In this work, a hybrid support vector machine (SVM with modified evolutionary particle swarm optimisation (EPSO algorithm was proposed to determine the transformer fault type. The superiority of the modified PSO technique with SVM was evaluated by comparing the results with the actual fault diagnosis, unoptimised SVM and previous reported works. Data reduction was also applied using stepwise regression prior to the training process of SVM to reduce the training time. It was found that the proposed hybrid SVM-Modified EPSO (MEPSO-Time Varying Acceleration Coefficient (TVAC technique results in the highest correct identification percentage of faults in a power transformer compared to other PSO algorithms. Thus, the proposed technique can be one of the potential solutions to identify the transformer fault type based on DGA data on site.

  13. Identification of transformer fault based on dissolved gas analysis using hybrid support vector machine-modified evolutionary particle swarm optimisation.

    Science.gov (United States)

    Illias, Hazlee Azil; Zhao Liang, Wee

    2018-01-01

    Early detection of power transformer fault is important because it can reduce the maintenance cost of the transformer and it can ensure continuous electricity supply in power systems. Dissolved Gas Analysis (DGA) technique is commonly used to identify oil-filled power transformer fault type but utilisation of artificial intelligence method with optimisation methods has shown convincing results. In this work, a hybrid support vector machine (SVM) with modified evolutionary particle swarm optimisation (EPSO) algorithm was proposed to determine the transformer fault type. The superiority of the modified PSO technique with SVM was evaluated by comparing the results with the actual fault diagnosis, unoptimised SVM and previous reported works. Data reduction was also applied using stepwise regression prior to the training process of SVM to reduce the training time. It was found that the proposed hybrid SVM-Modified EPSO (MEPSO)-Time Varying Acceleration Coefficient (TVAC) technique results in the highest correct identification percentage of faults in a power transformer compared to other PSO algorithms. Thus, the proposed technique can be one of the potential solutions to identify the transformer fault type based on DGA data on site.

  14. Supersaturated calcium carbonate solutions are classical

    Energy Technology Data Exchange (ETDEWEB)

    Henzler, Katja; Fetisov, Evgenii O.; Galib, Mirza; Baer, Marcel D.; Legg, Benjamin A.; Borca, Camelia; Xto, Jacinta M.; Pin, Sonia; Fulton, John L.; Schenter, Gregory K.; Govind, Niranjan; Siepmann, J. Ilja; Mundy, Christopher J.; Huthwelker, Thomas; De Yoreo, James J.

    2018-01-01

    We will present a description of nucleation phenomena in the condensed phase that takes into account non-ideal solution effects associated with cluster-cluster interaction. To do this we employ aggregation-volume bias Monte Carlo simulation, making the estimation of free-energy of large pre-critical clusters of sizes 10-20 tractable. We will compare and contrast empirical potential and electronic structure (e.g. Density functional theory) based descriptions of molecular interaction associated with the nucleation of CaCO3, highlighting free-energy trends and qualitative differences in populations of pre-critical clusters as a function of supersaturation. The influence of how the precise local interaction influences the non-ideal solution behavior on the nucleation and growth processes will be highlighted. This research was supported by the US Department of Energy, Office of Science, Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences, and Biosciences.

  15. Combined Effects of Supersaturation Rates and Doses on the Kinetic-Solubility Profiles of Amorphous Solid Dispersions Based on Water-Insoluble Poly(2-hydroxyethyl methacrylate) Hydrogels.

    Science.gov (United States)

    Schver, Giovanna C R M; Lee, Ping I

    2018-05-07

    Under nonsink dissolution conditions, the kinetic-solubility profiles of amorphous solid dispersions (ASDs) based on soluble carriers typically exhibit so-called "spring-and-parachute" concentration-time behaviors. However, the kinetic-solubility profiles of ASDs based on insoluble carriers (including hydrogels) are known to show sustained supersaturation during nonsink dissolution through a matrix-regulated diffusion mechanism by which the supersaturation of the drug is built up gradually and sustained over an extended period without any dissolved polymers acting as crystallization inhibitors. Despite previous findings demonstrating the interplay between supersaturation rates and total doses on the kinetic-solubility profiles of soluble amorphous systems (including ASDs based on dissolution-regulated releases from soluble polymer carriers), the combined effects of supersaturation rates and doses on the kinetic-solubility profiles of ASDs based on diffusion-regulated releases from water-insoluble carriers have not been investigated previously. Thus, the objective of this study is to examine the impacts of total doses and supersaturation-generation rates on the resulting kinetic-solubility profiles of ASDs based on insoluble hydrogel carriers. We employed a previously established ASD-carrier system based on water-insoluble-cross-linked-poly(2-hydroxyethyl methacrylate) (PHEMA)-hydrogel beads and two poorly water soluble model drugs: the weakly acidic indomethacin (IND) and the weakly basic posaconazole (PCZ). Our results show clearly for the first time that by using the smallest-particle-size fraction and a high dose (i.e., above the critical dose), it is indeed possible to significantly shorten the duration of sustained supersaturation in the kinetic-solubility profile of an ASD based on a water-insoluble hydrogel carrier, such that it resembles the spring-and-parachute dissolution profiles normally associated with ASDs based on soluble carriers. This generates

  16. Carbon diffusion in carbon-supersaturated ferrite and austenite

    Czech Academy of Sciences Publication Activity Database

    Čermák, Jiří; Král, Lubomír

    2014-01-01

    Roč. 586, FEB (2014), s. 129-135 ISSN 0925-8388 R&D Projects: GA ČR(CZ) GAP108/11/0148; GA MŠk(CZ) ED1.1.00/02.0068 Institutional support: RVO:68081723 Keywords : carbon diffusion * Carbon supersaturation * Carbon supersaturation * Ferrite * Austenite Subject RIV: BJ - Thermodynamics Impact factor: 2.999, year: 2014

  17. Effectiveness of supersaturation promoting excipients on albendazole concentrations in upper gastrointestinal lumen of fasted healthy adults.

    Science.gov (United States)

    Kourentas, Alexandros; Vertzoni, Maria; Symillides, Mira; Goumas, Konstantinos; Gibbon, Robert; Butler, James; Reppas, Christos

    2016-08-25

    To evaluate the impact of dosage form relevant levels of a polymeric precipitation inhibitor and of lipid excipients on supersaturation of upper gastrointestinal contents with albendazole, a lipophilic weak base. Albendazole concentrations in stomach and in duodenum were evaluated after administration of 1) a suspension in water (Susp-Control), 2) a suspension in water in which hydroxyprolylmethylcellulose E5 (HPMC E5) had been pre-dissolved (Susp-HPMC), and 3) and 4) two contrasting designs of lipid based suspensions dispersed in water (Susp-IIIA and Susp-IV), on a cross-over basis to fasted healthy adults. Limited, but statistically significant supersaturation of duodenal contents was observed after Susp-HPMC, Susp-IIIA, and Susp-IV; supersaturation was more consistent after Susp-HPMC administration. Based on total albendazole amount per volume, gastric secretions did not significantly alter volumes of bulk gastric contents during the first 40min post administration of a glass of non-caloric water-based fluid. Αlbendazole gastric concentrations were higher than in the administered suspensions, but similar for all four formulations. Gastric emptying of albendazole after administration of Susp-Control or Susp-HPMC was slower than after administration of Susp-IIIA or Susp-IV. Small amounts of HPMC E5 were as effective as lipid excipients in achieving supersaturation of duodenal contents with albendazole, a fast precipitating weak base, in fasted adults. However, compared with the effect of HPMC E5 the effect of lipid excipients was delayed and variable. Copyright © 2016 Elsevier B.V. All rights reserved.

  18. Iodine and NOx behavior in the dissolver off-gas and IODOX [Iodine Oxidation] systems in the Oak Ridge National Laboratory Integrated Equipment Test facility

    International Nuclear Information System (INIS)

    Birdwell, J.F.

    1990-01-01

    This paper describes the most recent in a series of experiments evaluating the behavior of iodine and NO x in the Integrated Equipment Test (IET) Dissolver Off-Gas (DOG) System. This work was performed as part of a joint collaborative program between the US Department of Energy and the Power and Nuclear Fuel Development Corporation of Japan. The DOG system consists of two shell-and-tube heat exchangers in which water and nitric acid are removed from the dissolver off-gas by condensation, followed by a packed tower in which NO x is removed by absorption into a dilute nitric acid solution. The paper also describes the results of the operation of the Iodine Oxidation (IODOX) System. This system serves to remove iodine from the DOG system effluent by absorption into hyperazeotropic nitric acid. 7 refs., 11 figs., 10 tabs

  19. Significance of dissolved methane in effluents of anaerobically ...

    Science.gov (United States)

    The need for energy efficient Domestic Wastewater (DWW) treatment is increasing annually with population growth and expanding global energy demand. Anaerobic treatment of low strength DWW produces methane which can be used to as an energy product. Temperature sensitivity, low removal efficiencies (Chemical Oxygen Demand (COD), Suspended Solids (SS), and Nutrients), alkalinity demand, and potential greenhouse gas (GHG) emissions have limited its application to warmer climates. Although well designed anaerobic Membrane Bioreactors (AnMBRs) are able to effectively treat DWW at psychrophilic temperatures (10–30 °C), lower temperatures increase methane solubility leading to increased energy losses in the form of dissolved methane in the effluent. Estimates of dissolved methane losses are typically based on concentrations calculated using Henry's Law but advection limitations can lead to supersaturation of methane between 1.34 and 6.9 times equilibrium concentrations and 11–100% of generated methane being lost in the effluent. In well mixed systems such as AnMBRs which use biogas sparging to control membrane fouling, actual concentrations approach equilibrium values. Non-porous membranes have been used to recover up to 92.6% of dissolved methane and well suited for degassing effluents of Upflow Anaerobic Sludge Blanket (UASB) reactors which have considerable solids and organic contents and can cause pore wetting and clogging in microporous membrane modules. Micro

  20. Using Noble Gas Measurements to Derive Air-Sea Process Information and Predict Physical Gas Saturations

    Science.gov (United States)

    Hamme, Roberta C.; Emerson, Steven R.; Severinghaus, Jeffrey P.; Long, Matthew C.; Yashayaev, Igor

    2017-10-01

    Dissolved gas distributions are important because they influence oceanic habitats and Earth's climate, yet competing controls by biology and physics make gas distributions challenging to predict. Bubble-mediated gas exchange, temperature change, and varying atmospheric pressure all push gases away from equilibrium. Here we use new noble gas measurements from the Labrador Sea to demonstrate a technique to quantify physical processes. Our analysis shows that water-mass formation can be represented by a quasi steady state in which bubble fluxes and cooling push gases away from equilibrium balanced by diffusive gas exchange forcing gases toward equilibrium. We quantify the rates of these physical processes from our measurements, allowing direct comparison to gas exchange parameterizations, and predict the physically driven saturation of other gases. This technique produces predictions that reasonably match N2/Ar observations and demonstrates that physical processes should force SF6 to be ˜6% more supersaturated than CFC-11 and CFC-12, impacting ventilation age calculations.

  1. Gas bubble disease monitoring and research of juvenile salmonids

    International Nuclear Information System (INIS)

    Maule, A.G.; Beeman, J.; Hans, K.M.; Mesa, M.G.; Haner, P.; Warren, J.J.

    1997-10-01

    This document describes the project activities 1996--1997 contract year. This report is composed of three chapters which contain data and analyses of the three main elements of the project: field research to determine the vertical distribution of migrating juvenile salmonids, monitoring of juvenile migrants at dams on the Snake and Columbia rivers, and laboratory experiments to describe the progression of gas bubble disease signs leading to mortality. The major findings described in this report are: A miniature pressure-sensitive radio transmitter was found to be accurate and precise and, after compensation for water temperature, can be used to determine the depth of tagged-fish to within 0.32 m of the true depth (Chapter 1). Preliminary data from very few fish suggest that depth protects migrating juvenile steelhead from total dissolved gas supersaturation (Chapter 1). As in 1995, few fish had any signs of gas bubble disease, but it appeared that prevalence and severity increased as fish migrated downstream and in response to changing gas supersaturation (Chapter 2). It appeared to gas bubble disease was not a threat to migrating juvenile salmonids when total dissolved gas supersaturation was < 120% (Chapter 2). Laboratory studies suggest that external examinations are appropriate for determining the severity of gas bubble disease in juvenile salmonids (Chapter 3). The authors developed a new method for examining gill arches for intravascular bubbles by clamping the ventral aorta to reduce bleeding when arches were removed (Chapter 3). Despite an outbreak of bacterial kidney disease in the experimental fish, the data indicate that gas bubble disease is a progressive trauma that can be monitored (Chapter 3)

  2. The use of supersaturation for the vaginal application of microbicides

    DEFF Research Database (Denmark)

    Grammen, Carolien; Plum, Jakob; Van Den Brande, Jeroen

    2014-01-01

    In this study, we investigated the potential of supersaturation for the formulation of the poorly water-soluble microbicide dapivirine (DPV) in an aqueous vaginal gel in order to enhance its vaginal tissue uptake. Different excipients such as hydroxypropylmethylcellulose, polyethylene glycol 1000....... The best performing supersaturated gel containing 500 μM DPV (supersaturation degree of 4) in the presence of sulfobutyl ether-beta-cyclodextrin (2.5%) appeared to be stable for at least 3 months. In addition, the gel generated a significant increase in vaginal drug uptake in rabbits as compared...... with suspension gels. We conclude that supersaturation is a possible strategy to enhance the vaginal concentration of hydrophobic microbicides, thereby increasing permeation into the vaginal submucosa....

  3. Effect of phytoremediation on concentrations of benzene, toluene, naphthalene, and dissolved oxygen in groundwater at a former manufactured gas plant site, Charleston, South Carolina, USA, 1998–2014

    Science.gov (United States)

    Landmeyer, James E.; Effinger, Thomas N.

    2016-01-01

    Concentrations of benzene, toluene, naphthalene, and dissolved oxygen in groundwater at a former manufactured gas plant site near Charleston, South Carolina, USA, have been monitored since the installation of a phytoremediation system of hybrid poplar trees in 1998. Between 2000 and 2014, the concentrations of benzene, toluene, and naphthalene (BT&N) in groundwater in the planted area have decreased. For example, in the monitoring well containing the highest concentrations of BT&N, benzene concentrations decreased from 10,200 µg/L to less than 4000 µg/L, toluene concentrations decreased from 2420 µg/L to less than 20 µg/L, and naphthalene concentrations decreased from 6840 µg/L to less than 3000 µg/L. Concentrations of BT&N in groundwater in all wells were observed to be lower during the summer months relative to the winter months of a particular year during the first few years after installing the phytoremediation system, most likely due to increased transpiration and contaminant uptake by the hybrid poplar trees during the warm summer months; this pathway of uptake by trees was confirmed by the detection of benzene, toluene, and naphthalene in trees during sampling events in 2002, and later in the study in 2012. These data suggest that the phytoremediation system affects the groundwater contaminants on a seasonal basis and, over multiple years, has resulted in a cumulative decrease in dissolved-phase contaminant concentrations in groundwater. The removal of dissolved organic contaminants from the aquifer has resulted in a lower demand on dissolved oxygen supplied by recharge and, as a result, the redox status of the groundwater has changed from anoxic to oxic conditions. This study provides much needed information for water managers and other scientists on the viability of the long-term effectiveness of phytoremediation in decreasing groundwater contaminants and increasing dissolved oxygen at sites contaminated by benzene, toluene, and naphthalene.

  4. Dissolved gases

    International Nuclear Information System (INIS)

    Heaton, T.H.E.

    1981-01-01

    The concentrations of gaseous nitrogen, argon, oxygen and helium dissolved in groundwater are often different from their concentrations in rain and surface waters. These differences reflect changes in the gas content occurring after rain or surface water, having infiltrated into the ground, become isolated from equilibrium contact with the atmosphere. A study of these changes can give insight into the origin and subsequent subsurface history of groundwater. Nitrogen and argon concentrations for many groundwaters in southern Africa indicate that excess air is added to water during infiltration. The amount of excess air is believed to reflect the physical structure of the unsaturated zone and the climate of the recharge area. Since nitrogen and argon are essentially conservative in many aquifer environments in South Africa, their concentrations can be used in distinguishing grondwaters of different recharge origins. In some areas the high helium content of the groundwater suggests that much of the helium is derived through migration from a source outside (e.g. below) the aquifer itself. Radiogenic helium concentrations nevertheless show, in two artesian aquifers, a close linear relationship to the radiocarbon age of the groundwater. This indicates a uniformity in the factors responsible for the accumulation of helium, and suggests that in these circumstances helium data can be used to give information on the age of very old groundwater. In some groundwater dissolved oxygen concentrations are found to decrease with increasing groundwater age. Whilst the rate of decrease may be very different for different aquifers, the field measurement of oxygen may be useful in preliminary surveys directed toward the location of recharge areas

  5. AN APPLICATION OF FLOW INJECTION ANALYSIS WITH GAS DIFFUSION AND SPECTROPHOTOMETRIC DETECTION FOR THE MONITORING OF DISSOLVED SULPHIDE CONCENTRATION IN ENVIRONMENTAL SAMPLES

    Directory of Open Access Journals (Sweden)

    Malwina Cykowska

    2014-10-01

    Full Text Available The monitoring of the concentration of sulphide is very important from the environment point of view because of high toxicity of hydrogen sulphide. What is more hydrogen sulphide is an important pollution indicator. In many cases the determination of sulphide is very difficult due to complicated matrix of some environmental samples, which causes that most analytical methods cannot be used. Flow injection analysis allows to avoid matrix problem what makes it suitable for a wide range of applications in analytical laboratories. In this paper determination of dissolved sulphide in environmental samples by gas-diffusion flow injection analysis with spectrophotometric detection was presented. Used gas-diffusion separation ensures the elimination of interferences caused by sample matrix and gives the ability of determination of sulphides in coloured and turbid samples. Studies to optimize the measurement conditions and to determine the value of the validation parameters (e.g. limit of detection, limit of quantification, precision, accuracy were carried out. Obtained results confirm the usefulness of the method for monitoring the concentration of dissolved sulphides in water and waste water. Full automation and work in a closed system greatly reduces time of analysis, minimizes consumption of sample and reagents and increases safety of analyst’s work.

  6. UV-vis Imaging of Piroxicam Supersaturation, Precipitation, and Dissolution in a Flow-Through Setup.

    Science.gov (United States)

    Sun, Yu; Chapman, Alex; Larsen, Susan W; Jensen, Henrik; Petersen, Nickolaj J; Goodall, David M; Østergaard, Jesper

    2018-06-05

    Evaluation of drug precipitation is important in order to address challenges regarding low and variable bioavailability of poorly water-soluble drugs, to assess potential risk of patient safety with infusion therapy, and to explore injectable in situ suspension-forming drug delivery systems. Generally, drug precipitation is assessed in vitro through solution concentration analysis methods. Dual-wavelength UV-vis imaging is a novel imaging technique that may provide an opportunity for simultaneously monitoring changes in both solution and solid phases during precipitation. In the present study, a multimodal approach integrating UV-vis imaging, light microscopy, and Raman spectroscopy was developed for characterization of piroxicam supersaturation, precipitation, and dissolution in a flow-through setup. A solution of piroxicam dissolved in 1-methyl-2-pyrrolidinone was injected into a flowing aqueous environment (pH 7.4), causing piroxicam to precipitate. Imaging at 405 and 280 nm monitored piroxicam concentration distributions during precipitation and revealed different supersaturation levels dependent on the initial concentration of the piroxicam solution. The combination with imaging at 525 nm, light microscopy, and Raman spectroscopy measurements demonstrated concentration-dependent precipitation and the formation, growth, and dissolution of individual particles. Results emphasize the importance of the specific hydrodynamic conditions on the piroxicam precipitation. The approach used may facilitate comprehensive understanding of drug precipitation and dissolution processes and may be developed further into a basic tool for formulation screening and development.

  7. Geopressured-geothermal test of the EDNA Delcambre No. 1 well, Tigre Lagoon Field, Vermilion Parish, Louisiana: analysis of water an dissolved natural gas. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Hankins, B.E.; Karkalits, O.C.

    1978-09-01

    The Edna Delcambre et al. No. 1 gas well, shut-in since June 1975, was made available for the project. Two geopressured sand-bed aquifers were tested: sand No. 3 at a depth of 12,900 feet and sand No. 1 at a depth of 12,600 feet. Each aquifer was subjected to flow tests which lasted approximately three weeks in each case. Water samples were obtained during flow testing of the two geopressured aquifers. The water contained 11.3 to 13.3% dissolved solids. Several radioactive species were measured. Radium-226 was found to be approximately 10 times more concentrated than the average amount observed in surface waters. No appreciable amount of heavy metals was detected. Recombination studies at bottom-hole conditions indicate the solubility of natural gas per barrel of water to be about 24 SCF. The methane content was 93 to 95%, and the gas had a heating value in the range of 1020 to 1070 Btu/cu.ft. During the flow tests, the gas/water ratio at the well-head was observed to be 45 to 88 SCF/Bbl water produced. (MHR)

  8. Evaluation technology for burnup and generated amount of plutonium by measurement of Xenon isotopic ratio in dissolver off-gas at reprocessing facility (Joint research)

    International Nuclear Information System (INIS)

    Okano, Masanori; Kuno, Takehiko; Shirouzu, Hidetomo; Yamada, Keiji; Sakai, Toshio; Takahashi, Ichiro; Charlton, William S.; Wells, Cyndi A.; Hemberger, Philip H.

    2006-12-01

    The amount of Pu in the spent fuel was evaluated from Xe isotopic ratio in off-gas in reprocessing facility, is related to burnup. Six batches of dissolver off-gas (DOG) at spent fuel dissolution process were sampled from the main stack in Tokai Reprocessing Plant (TRP) during BWR fuel (approx. 30GWD/MTU) reprocessing campaign. Xenon isotopic ratio was determined with Gas Chromatography/Mass Spectrometry. Burnup and generated amount of Pu were evaluated with Noble Gas Environmental Monitoring Application code (NOVA), developed by Los Alamos National Laboratory. Inferred burnup evaluated by Xe isotopic measurements and NOVA were in good agreement with those of the declared burnup in the range from -3.8% to 7.1%. Also, the inferred amount of Pu in spent fuel was in good agreed with those of the declared amount of Pu calculated by ORIGEN code in the range from -0.9% to 4.7%. The evaluation technique is applicable for both burnup credit to achieve efficient criticality safety control and a new measurement method for safeguards inspection. (author)

  9. Aqueous aerosol may build up large upper tropospheric ice supersaturation

    Science.gov (United States)

    Bogdan, Anatoli; Molina, Mario J.

    2010-05-01

    Keywords: ice supersaturation, upper tropospheric cirrus clouds, freezing of aqueous aerosol. Observations often reveal enhanced and persistent upper tropospheric (UT) ice supersaturation, Si up to 100%, independently of whether cirrus ice clouds are present or not (Krämer et al., 2009; Lawson et al., 2008). However, a water activity criterion (WAC) (Koop et al., 2000) does not allow the formation of Si > ~67% by the homogeneous freezing of aqueous droplets even at the lowest atmospheric temperature of ~185 K. For aqueous aerosol the WAC predicts the existence of a so called homogeneous ice nucleation threshold which, being expressed as Si, is between ~52 and 67% in the temperature range of ~220 - 185 K. The nature of the formation of large Si remains unclear. Since water vapor is the dominant greenhouse gas it is important to know the nature of the accumulation and persistence of water vapor in the UT. We studied the freezing behavior of micrometer-scaled 3-, 4-, and 5-component droplets, which contain different weight fractions of H2O, H2SO4, HNO3, (NH4)2SO4, (NH4)HSO4, NH4NO3, and (NH4)3H(SO4)2. The study was performed between 133 and 278 K at cooling rates of 3, 0.1, and 0.05 K/min using differential scanning calorimetry (DSC) (Bogdan and Molina, 2010). The cooling rates of 0.1 and 0.05 K/min (6 and 3 K/h) are similar to the smallest reported synoptic temperature change of ~2 K/h (Carslaw et al., 1998). Using the measured freezing temperature of ice, Ti, and the thermodynamic E-AIM model of the system of H+ - NH4+ - SO42-- NO3-- H2O (Clegg et al., 1998), we calculated the corresponding clear-sky Si which would be built up immediately prior to the formation of ice cirrus clouds by the homogeneous freezing of aqueous aerosol of similar composition. We found that our calculated values of Si are both larger and smaller than the homogeneous ice nucleation threshold. For example, for the droplets of compositions of 15/10 and 20/10 wt % (NH4)3H(SO4)2/H2SO4, which

  10. Zn-Ni sulfide selective precipitation: The role of supersaturation

    NARCIS (Netherlands)

    Sampaio, R.M.M.; Timmers, R.A.; Kocks, N.; Andre, V.; Duarte, M.T.; Hullebusch, van E.D.; Farges, F.; Lens, P.N.L.

    2010-01-01

    The selective removal of Zn with Na2S from a mixture of Zn and Ni was studied in a continuously stirred tank reactor. At pH 5 and pS 18 the selectivity was improved from 61% to 99% by reducing the supersaturation at the dosing points by means of the reduction of the influent concentrations. The

  11. A simple and rapid gas chromatographic method for the determination of dissolved deuterium and nitrogen in heavy water coolant of a nuclear reactor

    International Nuclear Information System (INIS)

    Nair, B.K.S.

    1976-01-01

    A known volume of a heavy water sample is equilibrated with a known volume of pure helium gas at atmospheric pressure in a sample tube. The dissolved gases evolve into the helium and distribute themselves between the gaseous and liquid phases according to their equilibrium partial pressures. These partial pressures of the gases in the equilibrium gas mixture are determined by analysing it gas-chromatographically. From these analytical data and the absorption coefficients of deuterium and nitrogen, their original concentrations in heavy water are calculated. Corrections for the increase in the total pressure of the gaseous phase owing to evolved gases are calculated and found to be negligible. Air contamination during sampling and analysis can be detected by the presence of the oxygen peak in the chromatogram and corrected for. The calculation is facilitated by programming it on an electronic calculator. The method is much simpler and faster than the vacuum method usually applied for this analysis. One determination can be completed in about an hour. The average deviation and standard deviation have been estimated at 0.19 ml/litre heavy water and 0.25 ml/litre heavy water respectively in deuterium, and 0.36 and 0.68 ml/litre in nitrogen. (author)

  12. A continuous flow isotope ratio mass spectrometry method for high precision determination of dissolved gas ratios and isotopic composition

    DEFF Research Database (Denmark)

    Charoenpong, C. N.; Bristow, L. A.; Altabet, M. A.

    2014-01-01

    ratio mass spectrometer (IRMS). A continuous flow of He carrier gas completely degasses the sample, and passes through the preparation and purification system before entering the IRMS for analysis. The use of this continuous He carrier permits short analysis times (less than 8 min per sample......) as compared with current high-precision methods. In addition to reference gases, calibration is achieved using air-equilibrated water standards of known temperature and salinity. Assessment of reference gas injections, air equilibrated standards, as well as samples collected in the field shows the accuracy...

  13. Dissolved radon and uranium in groundwater in a potential coal seam gas development region (Richmond River Catchment, Australia).

    Science.gov (United States)

    Atkins, Marnie L; Santos, Isaac R; Perkins, Anita; Maher, Damien T

    2016-04-01

    The extraction of unconventional gas resources such as shale and coal seam gas (CSG) is rapidly expanding globally and often prevents the opportunity for comprehensive baseline groundwater investigations prior to drilling. Unconventional gas extraction often targets geological layers with high naturally occurring radioactive materials (NORM) and extraction practices may possibly mobilise radionuclides into regional and local drinking water resources. Here, we establish baseline groundwater radon and uranium levels in shallow aquifers overlying a potential CSG target formation in the Richmond River Catchment, Australia. A total of 91 groundwater samples from six different geological units showed highly variable radon activities (0.14-20.33 Bq/L) and uranium levels (0.001-2.77 μg/L) which were well below the Australian Drinking Water Guideline values (radon; 100 Bq/L and uranium; 17 μg/L). Therefore, from a radon and uranium perspective, the regional groundwater does not pose health risks to consumers. Uranium could not explain the distribution of radon in groundwater. Relatively high radon activities (7.88 ± 0.83 Bq/L) in the fractured Lismore Basalt aquifer coincided with very low uranium concentrations (0.04 ± 0.02 μg/L). In the Quaternary Sediments aquifers, a positive correlation between U and HCO3(-) (r(2) = 0.49, p uranium was present as uranyl-carbonate complexes. Since NORM are often enriched in target geological formations containing unconventional gas, establishing radon and uranium concentrations in overlying aquifers comprises an important component of baseline groundwater investigations. Copyright © 2016 Elsevier Ltd. All rights reserved.

  14. I-129, Kr-85, C-14 and NO/sub x/ removal from spent fuel dissolver off-gas at atmospheric pressure and at reduced off-gas flow

    International Nuclear Information System (INIS)

    Henrich, E.; Huefner, R.

    1981-01-01

    A dissolver off-gas (DOG) system suitable for a LWR, FBR or HTR spent fuel reprocessing plant is described, incorporating the following features: (1) the DOG flow is reduced to a reasonably small volume, using fumeless dissolution conditions, by maintaining high concentrations, the retention procedures are simplified and accompanied by an economic reduction of the equipment size; (2) all process operations are conducted at atmospheric or subatmospheric pressure, including noble gas removal by selective absorption, without using high temperature processes; (3) all processes, except HEPA filtering, are continuous and do not accumulate large amounts of waste nuclides, the DOG process sequence is mutually compatible with itself and with processing in the headend, showing on-line redundancy for the removal of the most radiotoxic nuclides; and (4) the DOG system only deviates slightly from proven technology. The stage of development and relevant results are given both for a lab. scale and a pilot plant scale

  15. High Resolution CH4 Emissions and Dissolved CH4 Measurements Elucidate Surface Gas Exchange Processes in Toolik Lake, Arctic Alaska

    Science.gov (United States)

    Del Sontro, T.; Sollberger, S.; Kling, G. W.; Shaver, G. R.; Eugster, W.

    2013-12-01

    Approximately 14% of the Alaskan North Slope is covered in lakes of various sizes and depths. Diffusive carbon emissions (CH4 and CO2) from these lakes offset the tundra sink by ~20 %, but the offset would substantially increase if ebullitive CH4 emissions were also considered. Ultimately, arctic lake CH4 emissions are not insignificant in the global CH4 budget and their contribution is bound to increase due to impacts from climate change. Here we present high resolution CH4 emission data as measured via eddy covariance and a Los Gatos gas analyzer during the ice free period from Toolik Lake, a deep (20 m) Arctic lake located on the Alaskan North Slope, over the last few summers. Emissions are relatively low (Gatos gas analyzer. Thus, having both the flux and the CH4 gradient across the air-water interface measured directly, we can calculate k and investigate the processes influencing CH4 gas exchange in this lake. Preliminary results indicate that there are two regimes in wind speed that impact k - one at low wind speeds up to ~5 m s-1 and another at higher wind speeds (max ~10 m s-1). The differential wind speeds during night and day may compound the effect of convective mixing and cause the diurnal variation in observed fluxes.

  16. Pressure waves in a supersaturated bubbly magma

    Science.gov (United States)

    Kurzon, I.; Lyakhovsky, V.; Navon, O.; Chouet, B.

    2011-01-01

    We study the interaction of acoustic pressure waves with an expanding bubbly magma. The expansion of magma is the result of bubble growth during or following magma decompression and leads to two competing processes that affect pressure waves. On the one hand, growth in vesicularity leads to increased damping and decreased wave amplitudes, and on the other hand, a decrease in the effective bulk modulus of the bubbly mixture reduces wave velocity, which in turn, reduces damping and may lead to wave amplification. The additional acoustic energy originates from the chemical energy released during bubble growth. We examine this phenomenon analytically to identify conditions under which amplification of pressure waves is possible. These conditions are further examined numerically to shed light on the frequency and phase dependencies in relation to the interaction of waves and growing bubbles. Amplification is possible at low frequencies and when the growth rate of bubbles reaches an optimum value for which the wave velocity decreases sufficiently to overcome the increased damping of the vesicular material. We examine two amplification phase-dependent effects: (1) a tensile-phase effect in which the inserted wave adds to the process of bubble growth, utilizing the energy associated with the gas overpressure in the bubble and therefore converting a large proportion of this energy into additional acoustic energy, and (2) a compressive-phase effect in which the pressure wave works against the growing bubbles and a large amount of its acoustic energy is dissipated during the first cycle, but later enough energy is gained to amplify the second cycle. These two effects provide additional new possible mechanisms for the amplification phase seen in Long-Period (LP) and Very-Long-Period (VLP) seismic signals originating in magma-filled cracks.

  17. THE SEARCH FOR SUPER-SATURATION IN CHROMOSPHERIC EMISSION

    International Nuclear Information System (INIS)

    Christian, Damian J.; Arias, Tersi; Mathioudakis, Mihalis; Jess, David B.; Jardine, Moira

    2011-01-01

    We investigate if the super-saturation phenomenon observed at X-ray wavelengths for the corona exists in the chromosphere for rapidly rotating late-type stars. Moderate resolution optical spectra of fast-rotating EUV- and X-ray-selected late-type stars were obtained. Stars in α Per were observed in the northern hemisphere with the Isaac Newton 2.5 m telescope and Intermediate Dispersion Spectrograph. Selected objects from IC 2391 and IC 2602 were observed in the southern hemisphere with the Blanco 4 m telescope and R-C spectrograph at CTIO. Ca II H and K fluxes were measured for all stars in our sample. We find the saturation level for Ca II K at log (L CaK /L bol ) = -4.08. The Ca II K flux does not show a decrease as a function of increased rotational velocity or smaller Rossby number as observed in the X-ray. This lack of 'super-saturation' supports the idea of coronal stripping as the cause of saturation and super-saturation in stellar chromospheres and coronae, but the detailed underlying mechanism is still under investigation.

  18. Vanadium supersaturated silicon system: a theoretical and experimental approach

    Science.gov (United States)

    Garcia-Hemme, Eric; García, Gregorio; Palacios, Pablo; Montero, Daniel; García-Hernansanz, Rodrigo; Gonzalez-Diaz, Germán; Wahnon, Perla

    2017-12-01

    The effect of high dose vanadium ion implantation and pulsed laser annealing on the crystal structure and sub-bandgap optical absorption features of V-supersaturated silicon samples has been studied through the combination of experimental and theoretical approaches. Interest in V-supersaturated Si focusses on its potential as a material having a new band within the Si bandgap. Rutherford backscattering spectrometry measurements and formation energies computed through quantum calculations provide evidence that V atoms are mainly located at interstitial positions. The response of sub-bandgap spectral photoconductance is extended far into the infrared region of the spectrum. Theoretical simulations (based on density functional theory and many-body perturbation in GW approximation) bring to light that, in addition to V atoms at interstitial positions, Si defects should also be taken into account in explaining the experimental profile of the spectral photoconductance. The combination of experimental and theoretical methods provides evidence that the improved spectral photoconductance up to 6.2 µm (0.2 eV) is due to new sub-bandgap transitions, for which the new band due to V atoms within the Si bandgap plays an essential role. This enables the use of V-supersaturated silicon in the third generation of photovoltaic devices.

  19. Phase stability in wear-induced supersaturated Al-Ti solid solution

    Energy Technology Data Exchange (ETDEWEB)

    Watanabe, Y.; Yokoyama, K. [Dept. of Functional Machinery Mechanics Shinshu Univ., Ueda (Japan); Hosoda, H. [Precision and Intelligence Lab., Tokyo Inst. of Tech., Nagatsuta, Midori-ku, Yokohama (Japan)

    2002-07-01

    Al-Ti supersaturated solid solutions were introduced by wear testing and the rapid quenching of an Al/Al{sub 3}Ti composite (part of an Al/Al{sub 3}Ti functionally graded material) that was fabricated using the centrifugal method. The phase stability of the supersaturated solid solution was studied through systematic annealing of the supersaturated solid solution. It was found that the Al-Ti supersaturated solid solution decomposed into Al and Al{sub 3}Ti intermetallic compound phases during the heat treatment. The Al-Ti supersaturated solid solutions fabricated were, therefore, not an equilibrium phase, and thus decomposed into the equilibrium phases during heat treatment. It was also found that heat treatment leads to a significant hardness increase for the Al-Ti supersaturated solid solution. Finally, it was concluded that formation of the wear-induced supersaturated solid solution layer was a result of severe plastic deformation. (orig.)

  20. Molecular-level elucidation of saccharin-assisted rapid dissolution and high supersaturation level of drug from Eudragit® E solid dispersion.

    Science.gov (United States)

    Ueda, Keisuke; Kanaya, Harunobu; Higashi, Kenjirou; Yamamoto, Keiji; Moribe, Kunikazu

    2018-03-01

    In this work, the effect of saccharin (SAC) addition on the dissolution and supersaturation level of phenytoin (PHT)/Eudragit® E (EUD-E) solid dispersion (SD) at neutral pH was examined. The PHT/EUD-E SD showed a much slower dissolution of PHT compared to the PHT/EUD-E/SAC SD. EUD-E formed a gel layer after the dispersion of the PHT/EUD-E SD into an aqueous medium, resulting in a slow dissolution of PHT. Pre-dissolving SAC in the aqueous medium significantly improved the dissolution of the PHT/EUD-E SD. Solid-state 13 C NMR measurements showed an ionic interaction between the tertiary amino group of EUD-E and the amide group of SAC in the EUD-E gel layer. Consequently, the ionized EUD-E could easily dissolve from the gel layer, promoting PHT dissolution. Solution-state 1 H NMR measurements revealed the presence of ionic interactions between SAC and the amino group of EUD-E in the PHT/EUD-E/SAC solution. In contrast, interactions between PHT and the hydrophobic group of EUD-E strongly inhibited the crystallization of the former from its supersaturated solution. The PHT supersaturated solution was formed from the PHT/EUD-E/SAC SD by the fast dissolution of PHT and the strong crystallization inhibition effect of EUD-E after aqueous dissolution. Copyright © 2018 Elsevier B.V. All rights reserved.

  1. Influence of dissolved product gas on organism retention in biogas tower reactors; Der Einfluss geloester Produktgase auf den Organismenrueckhalt in Biogas-Turmreaktoren

    Energy Technology Data Exchange (ETDEWEB)

    Pietsch, T.; Maerkl, H. [Technische Univ. Hamburg-Harburg, Hamburg (Germany). Arbeitsbereich Bioprozess- und Bioverfahrenstechnik

    1999-07-01

    In biogas tower reactors, considerable oversaturations of CO{sub 2} dissolved in molecular form in the liquid phase can occur, compared to the thermodynamic steady state with the gas phase. In buildings of low height, upflow designs cause biological CO{sub 2} production along the reactor to saturate the liquid phase with carbonic acid, and also cause the pH value increasing from acid degradation to bind CO{sub 2} in the form of hydrogen carbonate HCO{sup -}{sub 3}. Where buildings are very high, the liquid phase becomes degassed through a decrease in CO{sub 2} partial pressure because of decreasing hydrostatic pressure along the length of the reactor. Rising gas bubbles in the liquid phase as well as enclosed gas bubbles in biomass particles slow down their sedimentation considerably and can result in flotation of biomass particles owing to gas expansion from declining hydrostatic pressure. A sedimentation characteristics for biomass under decreasing hydrostatic pressure is given. Conditions critical to biomass retention are energy input into CO{sub 2}-oversaturated liquids as well as dynamically rapid drops in pH value owing to associated CO{sub 2} degassing. (orig.) [German] In Biogas-Turmreaktoren koennen erhebliche Uebersaettigungen von molekular geloestem CO{sub 2} in der Fluessigphase gegenueber dem thermodynamischen Gleichgewichtszustand mit der Gasphase auftreten. Bei geringer Bauhoehe fuehrt bei upflow-Konzepten die biologische CO{sub 2}-Produktion entlang des Reaktors zu einer Aufsaettigung der Fluessigphase mit Kohlensaeure und der durch Saeureabbau ansteigende pH-Wert zu einer Bindung des CO{sub 2} in Form des Hydrogencarbonats HCO{sub 3}{sup -}. Sehr grosse Bauhoehen fuehren zu einer Entgasung der Fluessigphase durch Abnahme des CO{sub 2}-Partialdruckes aufgrund des abnehmenden hydrostatischen Druckes entlang der Reaktorhoehe. Aufsteigende Gasblasen in der Fluessigphase sowie eingeschlossene Gasblasen in Biomassepartikeln mindern deren

  2. Hydrogen sulfide measurement by headspace-gas chromatography-mass spectrometry (HS-GC-MS): application to gaseous samples and gas dissolved in muscle.

    Science.gov (United States)

    Varlet, Vincent; Giuliani, Nicole; Palmiere, Cristian; Maujean, Géraldine; Augsburger, Marc

    2015-01-01

    The aim of our study was to present a new headspace-gas chromatography-mass spectrometry (HS-GC-MS) method applicable to the routine determination of hydrogen sulfide (H(2)S) concentrations in biological and gaseous samples. The primary analytical drawback of the GC/MS methods for H(2)S measurement discussed in the literature was the absence of a specific H(2)S internal standard required to perform quantification. Although a deuterated hydrogen sulfide (D(2)S) standard is currently available, this standard is not often used because this standard is expensive and is only available in the gas phase. As an alternative approach, D(2)S can be generated in situ by reacting deuterated chloride with sodium sulfide; however, this technique can lead to low recovery yield and potential isotopic fractionation. Therefore, N(2)O was chosen for use as an internal standard. This method allows precise measurements of H(2)S concentrations in biological and gaseous samples. Therefore, a full validation using accuracy profile based on the β-expectation tolerance interval is presented. Finally, this method was applied to quantify H(2)S in an actual case of H(2)S fatal intoxication. © The Author 2014. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  3. Dissolved Gas Analysis Principle-Based Intelligent Approaches to Fault Diagnosis and Decision Making for Large Oil-Immersed Power Transformers: A Survey

    Directory of Open Access Journals (Sweden)

    Lefeng Cheng

    2018-04-01

    Full Text Available Compared with conventional methods of fault diagnosis for power transformers, which have defects such as imperfect encoding and too absolute encoding boundaries, this paper systematically discusses various intelligent approaches applied in fault diagnosis and decision making for large oil-immersed power transformers based on dissolved gas analysis (DGA, including expert system (EPS, artificial neural network (ANN, fuzzy theory, rough sets theory (RST, grey system theory (GST, swarm intelligence (SI algorithms, data mining technology, machine learning (ML, and other intelligent diagnosis tools, and summarizes existing problems and solutions. From this survey, it is found that a single intelligent approach for fault diagnosis can only reflect operation status of the transformer in one particular aspect, causing various degrees of shortcomings that cannot be resolved effectively. Combined with the current research status in this field, the problems that must be addressed in DGA-based transformer fault diagnosis are identified, and the prospects for future development trends and research directions are outlined. This contribution presents a detailed and systematic survey on various intelligent approaches to faults diagnosing and decisions making of the power transformer, in which their merits and demerits are thoroughly investigated, as well as their improvement schemes and future development trends are proposed. Moreover, this paper concludes that a variety of intelligent algorithms should be combined for mutual complementation to form a hybrid fault diagnosis network, such that avoiding these algorithms falling into a local optimum. Moreover, it is necessary to improve the detection instruments so as to acquire reasonable characteristic gas data samples. The research summary, empirical generalization and analysis of predicament in this paper provide some thoughts and suggestions for the research of complex power grid in the new environment, as

  4. Tracking changes in composition and amount of dissolved organic matter throughout drinking water treatment plants by comprehensive two-dimensional gas chromatography-quadrupole mass spectrometry.

    Science.gov (United States)

    Li, Chunmei; Wang, Donghong; Xu, Xiong; Xu, Meijia; Wang, Zijian; Xiao, Ruiyang

    2017-12-31

    Dissolved organic matter (DOM) can affect the performance of water treatment processes and produce undesirable disinfection by-products during disinfection. Several studies have been undertaken on the structural characterization of DOM, but its fate during drinking water treatment processes is still not fully understood. In this work, the nontargeted screening method of comprehensive two-dimensional gas chromatography-quadrupole mass spectrometry (GC×GC-qMS) was used to reveal the detailed changes of different chemical classes of compounds in DOM during conventional and advanced drinking water treatment processes at three drinking water treatment plants in China. The results showed that when the dissolved organic carbon removal was low, shifts in the DOM composition could not be detected with the specific ultraviolet absorbance at 254nm, but the changes were clear in the three-dimensional fluorescence excitation-emission matrix or GC×GC-qMS analyses. Coagulation-sedimentation processes selectively removed 37-59% of the nitrogenous compounds, alcohols and aromatic hydrocarbons but increased the concentrations of halogen-containing compounds by 17-26% because of the contact time with chlorine in this step. Filtration was less efficient at removing DOM but preferentially removed 21-60% of the acids. However, other organic matter would be released from the filter (e.g., nitrogenous compounds, acids, and aromatic hydrocarbons). Biological activated carbon (BAC) treatment removed most of the compounds produced from ozonation, particularly ketones, alcohols, halogen-containing compounds and acids. However, it should be noted that certain highly polar or high molecular weight compounds not identified in this study might be released from the BAC bed. After the whole treatment processes, the concentrations of nitrogenous compounds, alcohols, alkenes, aromatic hydrocarbons and ketones were decreased more by the advanced treatment processes than by the conventional treatment

  5. California GAMA Special Study: An isotopic and dissolved gas investigation of nitrate source and transport to a public supply well in California's Central Valley

    Energy Technology Data Exchange (ETDEWEB)

    Singleton, M J; Moran, J E; Esser, B K; Roberts, S K; Hillegonds, D J

    2010-04-14

    This study investigates nitrate contamination of a deep municipal drinking water production well in Ripon, CA to demonstrate the utility of natural groundwater tracers in constraining the sources and transport of nitrate to deep aquifers in the Central Valley. The goal of the study was to investigate the origin (source) of elevated nitrate and the potential for the deep aquifer to attenuate anthropogenic nitrate. The site is ideal for such an investigation. The production well is screened from 165-325 feet below ground surface and a number of nearby shallow and deep monitoring wells were available for sampling. Furthermore, potential sources of nitrate contamination to the well had been identified, including a fertilizer supply plant located approximately 1000 feet to the east and local almond groves. A variety of natural isotopic and dissolved gas tracers including {sup 3}H-{sup 3}He groundwater age and the isotopic composition of nitrate are applied to identify nitrate sources and to characterize nitrate transport. An advanced method for sampling production wells is employed to help identify contaminant contributions from specific screen intervals. Nitrate transport: Groundwater nitrate at this field site is not being actively denitrified. Groundwater parameters indicate oxic conditions, the dissolved gas data shows no evidence for excess nitrogen as the result of denitrification, and nitrate-N and -O isotope compositions do not display patterns typical of denitrification. Contaminant nitrate source: The ambient nitrate concentration in shallow groundwater at the Ripon site ({approx}12 mg/L as nitrate) is typical of shallow groundwaters affected by recharge from agricultural and urban areas. Nitrate concentrations in Ripon City Well 12 (50-58 mg/L as nitrate) are significantly higher than these ambient concentrations, indicating an additional source of anthropogenic nitrate is affecting groundwater in the capture zone of this municipal drinking water well. This

  6. Buffer gas cooling and mixture analysis

    Science.gov (United States)

    Patterson, David S.; Doyle, John M.

    2018-03-06

    An apparatus for spectroscopy of a gas mixture is described. Such an apparatus includes a gas mixing system configured to mix a hot analyte gas that includes at least one analyte species in a gas phase into a cold buffer gas, thereby forming a supersaturated mixture to be provided for spectroscopic analysis.

  7. Gas Hydrate Occurrence Inferred from Dissolved Cl− Concentrations and δ18O Values of Pore Water and Dissolved Sulfate in the Shallow Sediments of the Pockmark Field in Southwestern Xisha Uplift, Northern South China Sea

    Directory of Open Access Journals (Sweden)

    Min Luo

    2014-06-01

    Full Text Available Deep-water pockmarks are frequently accompanied by the occurrence of massive gas hydrates in shallow sediments. A decline in pore-water Cl− concentration and rise in δ18O value provide compelling evidence for the gas hydrate dissociation. Mega-pockmarks are widely scattered in the southwestern Xisha Uplift, northern South China Sea (SCS. Pore water collected from a gravity-core inside of a mega-pockmark exhibits a downward Cl− concentration decrease concomitant with an increase in δ18O value at the interval of 5.7–6.7 mbsf. Concentrations of Cl−, Na+, and K+ mainly cluster along the seawater freshening line without distinct Na+ enrichment and K+ depletion. Thus, we infer that the pore water anomalies of Cl− concentrations and δ18O values are attributed to gas hydrate dissociation instead of clay mineral dehydration. Moreover, the lower δ18O values of sulfate in the target core (C14 than those in the reference core (C9 may be associated with the equilibrium oxygen fractionation during sulfate reduction between sulfate and the relatively 18O-depleted ambient water resulting from gas hydrate formation. The gas hydrate contents are estimated to be 6%–10% and 7%–15%, respectively, according to the offset of Cl− concentrations and δ18O values from the baselines. This pockmark field in southwestern Xisha Uplift is likely to be a good prospective area for the occurrence of gas hydrate in shallow sediments.

  8. In vivo analysis of supersaturation/precipitation/absorption behavior after oral administration of pioglitazone hydrochloride salt; determinant site of oral absorption.

    Science.gov (United States)

    Tanaka, Yusuke; Sugihara, Masahisa; Kawakami, Ayaka; Imai, So; Itou, Takafumi; Murase, Hirokazu; Saiki, Kazunori; Kasaoka, Satoshi; Yoshikawa, Hiroshi

    2017-08-30

    The purpose of this study was to evaluate in vivo supersaturation/precipitation/absorption behavior in the gastrointestinal (GI) tract based on the luminal concentration-time profiles after oral administration of pioglitazone (PG, a highly permeable lipophilic base) and its hydrochloride salt (PG-HCl) to rats. In the in vitro precipitation experiment in the classic closed system, while the supersaturation was stable in the simulated gastric condition, PG drastically precipitated in the simulated intestinal condition, particularly at a higher initial degree of supersaturation. Nonetheless, a drastic and moderate improvement in absorption was observed in vivo at a low and high dose of PG-HCl, respectively. Analysis based on the luminal concentration of PG after oral administration of PG-HCl at a low dose revealed that most of the dissolved PG emptied from the stomach was rapidly absorbed before its precipitation in the duodenum. At a high dose of PG-HCl, PG partly precipitated in the duodenum but was absorbed to some extent. Therefore, the extent of the absorption was mainly dependent on the duodenal precipitation behavior. Furthermore, a higher-than expected absorption after oral administration of PG-HCl from in vitro precipitation study may be due to the absorption process in the small intestine, which suppresses the precipitation by removal of the drug. This study successfully clarify the impact of the absorption process on the supersaturation/precipitation/absorption behavior and key absorption site for a salt formulation of a highly permeable lipophilic base based on the direct observation of in vivo luminal concentration. Our findings may be beneficial in developing an ideal physiologically based pharmacokinetic model and in vitro predictive dissolution tools and/or translating the in silico and in vitro data to the in vivo outcome. Copyright © 2017 Elsevier B.V. All rights reserved.

  9. Effect of voids-controlled vacancy supersaturations on B diffusion

    International Nuclear Information System (INIS)

    Marcelot, O.; Claverie, A.; Cristiano, F.; Cayrel, F.; Alquier, D.; Lerch, W.; Paul, S.; Rubin, L.; Jaouen, H.; Armand, C.

    2007-01-01

    We present here preliminary results on boron diffusion in presence of pre-formed voids of different characteristics. The voids were fabricated by helium implantation followed by annealing allowing the desorption of He prior to boron implantation. We show that under such conditions boron diffusion is always largely reduced and can even be suppressed in some cases. Boron diffusion suppression can be observed in samples not containing nanovoids in the boron-rich region. It is suggested that direct trapping of Si(int)s by the voids is not the mechanism responsible for the reduction of boron diffusion in such layers. Alternatively, our experimental results suggest that this reduction of diffusivity is more probably due to the competition between two Ostwald ripening phenomena taking place at the same time: in the boron-rich region, the competitive growth of extrinsic defects at the origin of TED and, in the void region, the Ostwald ripening of the voids which involves large supersaturations of Vs

  10. Effect of voids-controlled vacancy supersaturations on B diffusion

    Energy Technology Data Exchange (ETDEWEB)

    Marcelot, O. [CEMES/CNRS, 29 rue Jeanne Marvig, 31055 Toulouse (France)]. E-mail: marcelot@cemes.fr; Claverie, A. [CEMES/CNRS, 29 rue Jeanne Marvig, 31055 Toulouse (France); Cristiano, F. [LAAS/CNRS, 7 av. du Col. Roche, 31077 Toulouse (France); Cayrel, F. [LMP, Universite de Tours, 16 rue Pierre et Marie Curie, BP 7155, 37071 Tours (France); Alquier, D. [LMP, Universite de Tours, 16 rue Pierre et Marie Curie, BP 7155, 37071 Tours (France); Lerch, W. [Mattson Thermal Products GmbH, Daimlerstr. 10, D-89160 Dornstadt (Germany); Paul, S. [Mattson Thermal Products GmbH, Daimlerstr. 10, D-89160 Dornstadt (Germany); Rubin, L. [Axcelis Technologies, 108 Cherry Hill Drive, Beverly MA 01915 (United States); Jaouen, H. [STMicroelectronics, 850 rue Jean Monnet, 38926 Crolles (France); Armand, C. [LNMO/INSA, Service analyseur ionique, 135 av. de Rangueil, 31077 Toulouse (France)

    2007-04-15

    We present here preliminary results on boron diffusion in presence of pre-formed voids of different characteristics. The voids were fabricated by helium implantation followed by annealing allowing the desorption of He prior to boron implantation. We show that under such conditions boron diffusion is always largely reduced and can even be suppressed in some cases. Boron diffusion suppression can be observed in samples not containing nanovoids in the boron-rich region. It is suggested that direct trapping of Si(int)s by the voids is not the mechanism responsible for the reduction of boron diffusion in such layers. Alternatively, our experimental results suggest that this reduction of diffusivity is more probably due to the competition between two Ostwald ripening phenomena taking place at the same time: in the boron-rich region, the competitive growth of extrinsic defects at the origin of TED and, in the void region, the Ostwald ripening of the voids which involves large supersaturations of Vs.

  11. In-line bulk supersaturation measurement by electrical conductometry in KDP crystal growth from aqueous solution

    Science.gov (United States)

    Bordui, P. F.; Loiacono, G. M.

    1984-07-01

    A method is presented for in-line bulk supersaturation measurement in crystal growth from aqueous solution. The method is based on a computer-controlled concentration measurement exploiting an experimentally predetermined cross-correlation between the concentration, electrical conductivity, and temperature of the growth solution. The method was applied to Holden crystallization of potassium dihydrogen phosphate (KDP). An extensive conductivity-temperature-concentration data base was generated for this system over a temperature range of 31 to 41°C. The method yielded continous, automated bulk supersaturation output accurate to within ±0.05 g KDP100 g water (±0.15% relative supersaturation).

  12. Supersaturation of zafirlukast in fasted and fed state intestinal media with and without precipitation inhibitors

    DEFF Research Database (Denmark)

    Madsen, Cecilie Maria; Boyd, Ben; Rades, Thomas

    2016-01-01

    by 40%. The aim of this study was to investigate the effect of simulated fasted and fed state intestinal media as well as the effect of HPMC and PVP on the supersaturation and precipitation of ZA in vitro. Supersaturation of aZA was studied in vitro in a small scale setup using the μDiss Profiler......™. Several media were used for this study: One medium simulating the fasted state intestinal fluids and three media simulating different fed state intestinal fluids. Solid state changes of the drug were investigated by small angle x-ray scattering. The duration wherein aZA was maintained at a supersaturated...... simulated intestinal media, but the concentration during supersaturation was higher. It was thus not possible to predict any positive or negative food effects from the dissolution/precipitation curves from different media. Lipolysis products in the fed state simulated media seemed to cause both a negative...

  13. The use of supersaturation for the vaginal application of microbicides: a case study with dapivirine.

    Science.gov (United States)

    Grammen, Carolien; Plum, Jakob; Van Den Brande, Jeroen; Darville, Nicolas; Augustyns, Koen; Augustijns, Patrick; Brouwers, Joachim

    2014-11-01

    In this study, we investigated the potential of supersaturation for the formulation of the poorly water-soluble microbicide dapivirine (DPV) in an aqueous vaginal gel in order to enhance its vaginal tissue uptake. Different excipients such as hydroxypropylmethylcellulose, polyethylene glycol 1000, and cyclodextrins were evaluated for their ability to inhibit precipitation of supersaturated DPV in the formulation vehicle as such as well as in biorelevant media. In vitro permeation assessment across HEC-1A cell layers demonstrated an enhanced DPV flux from supersaturated gels compared with suspension gels. The best performing supersaturated gel containing 500 μM DPV (supersaturation degree of 4) in the presence of sulfobutyl ether-beta-cyclodextrin (2.5%) appeared to be stable for at least 3 months. In addition, the gel generated a significant increase in vaginal drug uptake in rabbits as compared with suspension gels. We conclude that supersaturation is a possible strategy to enhance the vaginal concentration of hydrophobic microbicides, thereby increasing permeation into the vaginal submucosa. © 2014 Wiley Periodicals, Inc. and the American Pharmacists Association.

  14. In Situ Raman Spectroscopic Observations of Gas-Saturated Rising Oil droplets: Simulation with Decane as an Oil-Equivalent Substitute

    Science.gov (United States)

    Peltzer, E. T.; Walz, P. M.; Brewer, P. G.

    2016-02-01

    Oil droplets rising from the sea floor, whether from seeps or well leakage, contain very large quantities of dissolved gas that profoundly affects their density and critical oil-water interfacial characteristics. The primary dissolved gas is methane which may be up to 30% of the molar volume. This can create a hydrate skin as the methane gas is shed from the oil as it rises through the water column, thus decreasing in pressure and increasing in temperature, and steadily changing the rising droplet buoyancy. We have explored this phenomenon by executing controlled ROV based experiments with a "bubble cup" technique in which a small volume of gas saturated decane (saturated with pure methane, a mix of methane and nitrogen , or a mix of methane and CO2) is interrogated by laser Raman spectroscopy. The use of decane as an oil "substitute" is required since natural oil samples are highly fluorescent due to the presence of polycyclic aromatic hydrocarbons. We have devised Matlab techniques for extracting the spectroscopic dissolved methane signal from the thicket of decane peaks that surround it. We have directly observed the rate at which gases are lost from the "oil" per unit area at depths in the water column that are both within and outside the hydrate forming phase boundary. We have compared the behavior of both a non-hydrate forming dissolved gas (nitrogen) with CO2 where the hydrate phase boundary is at significantly shallower depth. The results indicate complex interfacial behavior and physical chemistry. We did not observe direct gas bubble formation on the decane outer surface but did observe gas bubble formation within the oil droplets as they rose through the water column. Because there are significant energy barriers for homogeneous bubble formation within the decane phase, we took this as evidence of significant gas super-saturation within the oil droplet. The gas loss rates increased significantly in all cases when the hydrate phase boundary was crossed.

  15. Characterisation of dissolved organic compounds in hydrothermal fluids by stir bar sorptive extraction - gas chomatography - mass spectrometry. Case study: the Rainbow field (36°N, Mid-Atlantic Ridge

    Directory of Open Access Journals (Sweden)

    Konn Cecile

    2012-11-01

    Full Text Available Abstract The analysis of the dissolved organic fraction of hydrothermal fluids has been considered a real challenge due to sampling difficulties, complexity of the matrix, numerous interferences and the assumed ppb concentration levels. The present study shows, in a qualitative approach, that Stir Bar Sorptive Extraction (SBSE followed by Thermal Desorption – Gas Chromatography – Mass Spectrometry (TD-GC-MS is suitable for extraction of small sample volumes and detection of a wide range of volatile and semivolatile organic compounds dissolved in hydrothermal fluids. In a case study, the technique was successfully applied to fluids from the Rainbow ultramafic-hosted hydrothermal field located at 36°14’N on the Mid-Atlantic Ridge (MAR. We show that n-alkanes, mono- and poly- aromatic hydrocarbons as well as fatty acids can be easily identified and their retention times determined. Our results demonstrate the excellent repeatability of the method as well as the possibility of storing stir bars for at least three years without significant changes in the composition of the recovered organic matter. A preliminary comparative investigation of the organic composition of the Rainbow fluids showed the great potential of the method to be used for assessing intrafield variations and carrying out time series studies. All together our results demonstrate that SBSE-TD-GC-MS analyses of hydrothermal fluids will make important contributions to the understanding of geochemical processes, geomicrobiological interactions and formation of mineral deposits.

  16. Coexistence effect of UVA absorbers to increase their solubility and stability of supersaturation.

    Science.gov (United States)

    Endo, M; Mukawa, T; Sato, N; Maezawa, D; Ohtsu, Y; Kuroda, A; Wakabayashi, M; Asakura, K

    2014-12-01

    Sunscreens containing UVA absorbers in high concentrations are expected to be developed, since recent studies have suggested the possibility of involvement of UVA ray in skin cancer and early skin aging. Solubility and stability of supersaturation of UVA absorbers in UVB absorber were determined in the absence and the presence of cosmetic oil. Coexistence effect of UVA absorbers was analyzed to dissolve them in high concentrations. Two UVA absorbers, diethylamino hydroxybenzoyl hexyl benzoate (DHHB) and butyl methoxydibenzoylmethane (BMDM), a UVB absorber, 2-ethylhexyl methoxycinnamate (EHMC), and a cosmetic oil, 2-ethylhexyl ester of oligomer of hydroxystearic acid (EH-O-HSA), were used. Their solutions were prepared at 80°C and cooled to 5°C. The solid DHHB and/or BMDM were added to it, and the time evolution of concentrations of the UVA absorbers in the solution phase was monitored. At the saturation in the absence of EH-O-HSA at 5°C, weight ratio of DHHB and BMDM to EHMC was 0.39/1.00 and 0.22/1.00, respectively. Addition of EH-O-HSA slightly changed the solubility of DHHB and BMDM. When the weight ratio of EH-O-HSA to EHMC was 0.20/1.00, weight ratio of DHHB and BMDM to EHMC was 0.35/1.00 and 0.25/1.00, respectively at the saturation at 5°C. In the presence of EH-O-HSA, a strong coexistence effect of DHHB and BMDM was found on their solubility. A thermodynamically stable saturated solution at 5°C having the composition that DHHB: BMDM: EHMC: EH-O-HSA = 0.47: 0.46: 1.00: 0.20 was obtained by the simultaneous addition of solid DHHB and BMDM into the initial solution. The solution type composite having the highest concentrations of DHHB and BMDM prepared in this study exhibited critical wavelength at 368 nm that was just below the border for sunscreens being qualified as 'Broad Spectrum' protection under the new rule launched by US FDA. © 2014 Society of Cosmetic Scientists and the Société Française de Cosmétologie.

  17. Modifying the dissolved-in-water type natural gas field simulation model based on the distribution of estimated Young's modulus for the Kujukuri region, Japan

    Directory of Open Access Journals (Sweden)

    T. Nakagawa

    2015-11-01

    Full Text Available A simulation model, which covers the part of Southern-Kanto natural gas field in Chiba prefecture, was developed to perform studies and make predictions of land subsidence. However, because large differences between simulated and measured subsidence occurred in the northern modeled area of the gas field, the model was modified with an estimated Young's modulus distribution. This distribution was estimated by the yield value distribution and the correlation of yield value with Young's modulus. Consequently, the simulated subsidence in the north area was improved to some extent.

  18. Formation of gas bubbles in gas superheated water

    International Nuclear Information System (INIS)

    Finkelstein, Y.

    1984-05-01

    The phenomenon of bubbles formation in supersaturated solutions of gases in water is a transport process, the final result of which is a separation of phases. In spite of its widespread appearance in industry and in nature, no model exists that can explain it and predict the degree of supersaturation which a gas-water solution can tolerate before bubbles are formed. The objective of this study was to fill this gap, and indeed, an extensive experimental work was carried out, a model was established and simple but accurate means were developed for predicting the tolerable degree of supersaturation of gas-water solutions. The model is also capable of predicting quite accurately the activation phenomenon in water. Superheating and supercooling phenomena were also examined in the light of the new model. (author)

  19. First report of the successful operation of a side stream supersaturation hypolimnetic oxygenation system in a eutrophic, shallow reservoir.

    Science.gov (United States)

    Gerling, Alexandra B; Browne, Richard G; Gantzer, Paul A; Mobley, Mark H; Little, John C; Carey, Cayelan C

    2014-12-15

    Controlling hypolimnetic hypoxia is a key goal of water quality management. Hypoxic conditions can trigger the release of reduced metals and nutrients from lake sediments, resulting in taste and odor problems as well as nuisance algal blooms. In deep lakes and reservoirs, hypolimnetic oxygenation has emerged as a viable solution for combating hypoxia. In shallow lakes, however, it is difficult to add oxygen into the hypolimnion efficiently, and a poorly designed hypolimnetic oxygenation system could potentially result in higher turbidity, weakened thermal stratification, and warming of the sediments. As a result, little is known about the viability of hypolimnetic oxygenation in shallow bodies of water. Here, we present the results from recent successful tests of side stream supersaturation (SSS), a type of hypolimnetic oxygenation system, in a shallow reservoir and compare it to previous side stream deployments. We investigated the sensitivity of Falling Creek Reservoir, a shallow (Zmax = 9.3 m) drinking water reservoir located in Vinton, Virginia, USA, to SSS operation. We found that the SSS system increased hypolimnetic dissolved oxygen concentrations at a rate of ∼1 mg/L/week without weakening stratification or warming the sediments. Moreover, the SSS system suppressed the release of reduced iron and manganese, and likely phosphorus, from the sediments. In summary, SSS systems hold great promise for controlling hypolimnetic oxygen conditions in shallow lakes and reservoirs. Copyright © 2014 Elsevier Ltd. All rights reserved.

  20. Dissolving method for nuclear fuel oxide

    International Nuclear Information System (INIS)

    Tomiyasu, Hiroshi; Kataoka, Makoto; Asano, Yuichiro; Hasegawa, Shin-ichi; Takashima, Yoichi; Ikeda, Yasuhisa.

    1996-01-01

    In a method of dissolving oxides of nuclear fuels in an aqueous acid solution, the oxides of the nuclear fuels are dissolved in a state where an oxidizing agent other than the acid is present together in the aqueous acid solution. If chlorate ions (ClO 3 - ) are present together in the aqueous acid solution, the chlorate ions act as a strong oxidizing agent and dissolve nuclear fuels such as UO 2 by oxidation. In addition, a Ce compound which generates Ce(IV) by oxidation is added to the aqueous acid solution, and an ozone (O 3 ) gas is blown thereto to dissolve the oxides of nuclear fuels. Further, the oxides of nuclear fuels are oxidized in a state where ClO 2 is present together in the aqueous acid solution to dissolve the oxides of nuclear fuels. Since oxides of the nuclear fuels are dissolved in a state where the oxidizing agent is present together as described above, the oxides of nuclear fuels can be dissolved even at a room temperature, thereby enabling to use a material such as polytetrafluoroethylene and to dissolve the oxides of nuclear fuels at a reduced cost for dissolution. (T.M.)

  1. Enhanced diffusion of dopants in vacancy supersaturation produced by MeV implantation

    International Nuclear Information System (INIS)

    Venezia, V.C.; Univ. of North Texas, Denton, TX; Haynes, T.E.; Agarwal, A.; Lucent Technologies, Murray Hill, NJ; Gossmann, H.J.; Eaglesham, D.J.

    1997-04-01

    The diffusion of Sb and B markers has been studied in vacancy supersaturations produced by MeV Si implantation in float zone (FZ) silicon and bonded etch-back silicon-on-insulator (BESOI) substrates. MeV Si implantation produces a vacancy supersaturated near-surface region and an interstitial-rich region at the projected ion range. Transient enhanced diffusion (TED) of Sb in the near surface layer was observed as a result of a 2 MeV Si + , 1 x 10 16 /cm 2 , implant. A 4x larger TED of Sb was observed in BESOI than in FZ silicon, demonstrating that the vacancy supersaturation persists longer in BESOI than in FZ. B markers in samples with MeV Si implant showed a factor of 10x smaller diffusion relative to markers without the MeV Si + implant. This data demonstrates that a 2 MeV Si + implant injects vacancies into the near surface region

  2. Cooling Crystallization of Indomethacin: Effect of Supersaturation, Temperature and Seeding on Polymorphism and Crystal Size Distribution

    DEFF Research Database (Denmark)

    Malwade, Chandrakant Ramkrishna; Qu, Haiyan

    2018-01-01

    In this work, effect of crystallization parameters i.e., supersaturation, seeding, and temperature on polymorphism and crystal size of a non-steroidal anti-inflammatory drug, indomethacin (IMC), was investigated. Firstly, several crystallization solvents (ethanol, methanol, ethyl acetate, acetone...... of IMC from ethanol confirmed that the supersaturation, operating temperature and seeding does affect the polymorphism as well as crystal size distribution of IMC. Fine needle shaped crystals of metastable α-IMC were obtained at 5 °C with high supersaturation even in presence of γ-IMC seeds, while...... rhombic plates like crystals of thermodynamically stable γ-IMC were obtained in remaining experiments. The amount of seed loading only marginally influenced the crystal growth rate and median particle diameter (d50). Particle size analysis of crystals obtained showed bimodal distribution in all...

  3. Impact of curcumin supersaturation in antibacterial photodynamic therapy-effect of cyclodextrin type and amount

    DEFF Research Database (Denmark)

    Hegge, A.B.; Nielsen, T.T.; Larsen, Kim Lambertsen

    2012-01-01

    Curcumin has been investigated as a potential photosensitizer (PS) in antimicrobial photodynamic therapy (aPDT). The phototoxic effect of curcumin is dependent on proper formulations of the compound because of the lipophilic nature of the molecule and the extremely low water solubility...... at physiological conditions. In the present study, the combination of curcumin with either a methylated β-cyclodextrin (CD) or polyethylene glycol-based β-CD or γ-CD polymers was investigated in aPDT using Escherichia coli (E. coli) and Enterococcus faecalis as model bacteria. Solutions with various...... supersaturation ratios of curcumin were prepared with the selected CD or CD polymers. The concept of supersaturation was then investigated as a mean to enhance the phototoxic effect of curcumin, especially toward the gram-negative bacteria E. coli. A high supersaturation ratio corresponded with high phototoxicity...

  4. Structure and Supersaturation of Highly Concentrated Solutions of Buckyball in 1-Butyl-3-Methylimidazolium Tetrafluoroborate

    DEFF Research Database (Denmark)

    Fileti, E. E.; Chaban, V. V.

    2014-01-01

    Solubilization of fullerenes is of high interest because of their wide usage in both fundamental research and numerous applications. This paper reports molecular dynamics (MD) simulations of saturated and supersaturated solutions of C-60 in 1-butyl-3-methylimidazolium tetrafluoroborate, [C4C1IM......-long real-time dynamics. The ion-molecular structure patterns in saturated and supersaturated solutions are distinguished in terms of radial distribution functions and cluster analysis of the solute particles. The cation separated solute pair is found to be a common structure in both saturated......][BF4], room-temperature ionic liquid (RTIL). The simulations cover a wide range of temperatures between 280 and 500 K at ambient pressure. Unlike in simpler solvents, C-60 in [C4C1IM][BF4] forms highly supersaturated solutions, whose internal arrangement remains unaltered during nearly a microsecond...

  5. Investigation of the Intra- and Interlaboratory Reproducibility of a Small Scale Standardized Supersaturation and Precipitation Method

    DEFF Research Database (Denmark)

    Plum, Jakob; Madsen, Cecilie M; Teleki, Alexandra

    2017-01-01

    order for the three model compounds using the SSPM (aprepitant > felodipine ≈ fenofibrate). The α-value is dependent on the experimental setup and can be used as a parameter to evaluate the uniformity of the data set. This study indicated that the SSPM was able to obtain the same rank order of the β...... compound available for absorption. However, due to the stochastic nature of nucleation, supersaturating drug delivery systems may lead to inter- and intrapersonal variability. The ability to define a feasible range with respect to the supersaturation level is a crucial factor for a successful formulation...... reproducibility study of felodipine was conducted, after which seven partners contributed with data for three model compounds; aprepitant, felodipine, and fenofibrate, to determine the interlaboratory reproducibility of the SSPM. The first part of the SSPM determines the apparent degrees of supersaturation (a...

  6. Effect of supersaturation on L-glutamic acid polymorphs under droplet-based microchannels

    Science.gov (United States)

    Jiang, Nan; Wang, Zhanzhong; Dang, Leping; Wei, Hongyuan

    2016-07-01

    Supersaturation is an important controlling factor for crystallization process and polymorphism. Droplet-based microchannels and conventional crystallization were used to investigate polymorphs of L-gluatamic acid in this work. The results illustrate that it is easy to realize the accurate and rapid control of the crystallization temperature in the droplets, which is especially beneficial to heat and mass transfer during crystallization. It is also noted that higher degree of supersaturation favors the nucleation of α crystal form, while lower degree of supersaturation favors the nucleation of β crystal form under droplet-based microchannels for L-gluatamic acid. In addition, there is a different nucleation behavior to be found under droplet-based microchannels both for the β form and α form of L-glutamic acid. This new finding can provide important insight into the development and design of investigation meanings for drug polymorph.

  7. Riverine CO2 supersaturation and outgassing in a subtropical monsoonal mountainous area (Three Gorges Reservoir Region) of China

    Science.gov (United States)

    Li, Siyue; Ni, Maofei; Mao, Rong; Bush, Richard T.

    2018-03-01

    Rivers are an important source of CO2 to the atmosphere, however, mountainous rivers and streams with high emission rates are not well studied particularly in China. We report the first detailed investigation on monsoonal mountainous rivers in the Three Gorges Reservoir (TGR) region, with a focus on the riverine CO2 partial pressure (pCO2), CO2 degassing and their potential controls. The pCO2 levels ranged from 50 to 6019 μatm with averages of 1573 (SD. ±1060) in dry Autumn and 1276 (SD. ±1166) μatm in wet Summer seasons. 94% of samples were supersaturated with CO2 with respect to the atmospheric equilibrium (410 μatm). Monsoonal precipitation controlled pCO2 seasonality, with both the maximal and minimal levels occurring in the wet season, and showing the overall effects of dilution. Riverine pCO2 could be predicted better in the dry season using pH, DO% and DTP, whereas pH and DOC were better predictors in the wet season. We conclude that in-situ respiration of allochthonous organic carbon, rather than photosynthesis, resulted in negative relationships between pCO2 and DO and pH, and thus CO2 supersaturation. Photosynthetic primary production was effectively limited by rapid flow velocity and short residence time. The estimated water-to-air CO2 emission rate in the TGR rivers was 350 ± 319 in the Autumn and lower, yet more variable at 326 ± 439 mmol/m2/d in Summer. Our calculated CO2 areal fluxes were in the upper-level magnitude of published data, demonstrating the importance of mountainous rivers and streams as a global greenhouse gas source, and urgency for more detailed studies on CO2 degassing, to address a global data gap for these environments.

  8. Decomposition features of a supersaturated solid solution in the Mg-3.3 wt. % Yb alloy

    International Nuclear Information System (INIS)

    Dobromyslov, A.V.; Kajgorodova, L.I.; Sukhanov, V.D.; Dobatkina, T.V.

    2007-01-01

    Methods of electron microscopy, hardness measuring and X-ray diffraction analysis are applied to study decomposition kinetics for a supersaturated solid solution in a Mg-3.3 mas. % alloy on aging within a temperature range of 150-225 deg C. The mechanism of supersaturation solid solution decomposition is revealed along with the nature of phases precipitated at various stages of aging: on incomplete and extended aging as well as at maximum hardness. The types of structural constituents responsible for changes of hardness on aging are determined [ru

  9. Effects of the rate of supersaturation generation on polymorphic crystallization of m-hydroxybenzoic acid and o-aminobenzoic acid

    Science.gov (United States)

    He, Guangwen; Wong, Annie B. H.; Chow, Pui Shan; Tan, Reginald B. H.

    2011-01-01

    Effects of the rate of supersaturation generation on polymorphic crystallization have been investigated through evaporation and cooling crystallization experiments of m-hydroxybenzoic acid (m-HBA) in methanol, acetone and ethyl acetate, and o-aminobenzoic acid (o-ABA) in ethanol. The rate of supersaturation generation has been altered by systematically changing either the cooling rate or the evaporation rate of solvent using a jacketed crystallizer and a microfluidic evaporation device, respectively. The results have revealed that the rate of supersaturation generation and the tendency of the formation of the less stable polymorph are positively correlated. Kinetic effects are dominant when the rate of supersaturation generation is high, thereby producing the metastable polymorphs (orthorhombic m-HBA; Form II of o-ABA); on the contrary, more stable polymorphs (monoclinic m-HBA; Forms III and I of o-ABA) are formed when the rate of supersaturation generation is low and the thermodynamic effects are prevailing.

  10. Water quality and processes affecting dissolved oxygen concentrations in the Blackwater River, Canaan Valley, West Virginia

    Science.gov (United States)

    Waldron, M.C.; Wiley, J.B.

    1996-01-01

    The water quality and environmental processes affecting dissolved oxygen were determined for the Blackwater River in Canaan Valley, West Virginia. Canaan Valley is oval-shaped (14 miles by 5 miles) and is located in the Allegheny Mountains at an average elevation of 3,200 feet above sea level. Tourism, population, and real estate development have increased in the past two decades. Most streams in Canaan Valley are a dilute calcium magnesium bicarbonate-type water. Streamwater typicaly was soft and low in alkalinity and dissolved solids. Maximum values for specific conductance, hardness, alkalinity, and dissolved solids occurred during low-flow periods when streamflow was at or near baseflow. Dissolved oxygen concentrations are most sensitive to processes affecting the rate of reaeration. The reaeration is affected by solubility (atmospheric pressure, water temperature, humidity, and cloud cover) and processes that determine stream turbulence (stream depth, width, velocity, and roughness). In the headwaters, photosynthetic dissolved oxygen production by benthic algae can result in supersaturated dissolved oxygen concentrations. In beaver pools, dissolved oxygen consumption from sediment oxygen demand and carbonaceous biochemical oxygen demand can result in dissolved oxygen deficits.

  11. Gas

    International Nuclear Information System (INIS)

    1996-01-01

    The French government has decided to modify the conditions of extension of local natural gas authorities to neighbouring districts. The European Union is studying the conditions of internal gas market with the objective of more open markets although considering public service requirements

  12. On the influence of atmospheric super-saturation layer on China's heavy haze-fog events

    Science.gov (United States)

    Wang, Jizhi; Yang, Yuanqin; Zhang, Xiaoye; Liu, Hua; Che, Huizheng; Shen, Xiaojing; Wang, Yaqiang

    2017-12-01

    With the background of global change, the air quality in Earth's atmosphere has significantly decreased. The North China Plain (NCP), Yangtze River Delta (YRD), Pearl River Delta (PRD) and Si-Chuan Basin (SCB) are the major areas suffering the decreasing air quality and frequent pollution events in recent years. Studying the effect of meteorological conditions on the concentration of pollution aerosols in these pollution sensitive regions is a hot focus now. This paper analyses the characteristics of atmospheric super-saturation and the corresponding H_PMLs (height of supersaturated pollution mixing layer), investigating their contribution to the frequently-seen heavy haze-fog weather. The results suggest that: (1) in the above-mentioned pollution sensitive regions in China, super-saturated layers repeatedly appear in the low altitude and the peak value of supersaturation S can reach 6-10%, which makes pollution particles into the wet adiabatic uplift process in the stable-static atmosphere. After low-level atmosphere reaches the super-saturation state below the H_PMLs, meteorological condition contributes to humidification and condensation of pollution particles. (2) Caculation of condensation function Fc, one of PLAM sensetive parameter, indicates that super-saturation state helps promote condensation, beneficial to the formation of Condensational Kink (CK) in the pollution sensitive areas. This favors the formation of new aerosol particles and intensities the cumulative growth of aerosol concentration. (3) By calculating the convective inhibition energy on average │CIN│ > 1.0 × 104 J kg-1, we found the value is about 100 times higher than the stable critical value. The uplifting diffusion of the particles is inhibited by the ambient airflow. So, this is the important reason for the aggravation and persistence of aerosol pollutants in local areas. (4) H_PMLs is negatively correlated to the pollution meteorological condition index PLAM which can describe the

  13. An Effective Continuum Model for the Gas Evolution in Internal Steam Drives

    Energy Technology Data Exchange (ETDEWEB)

    Tsimpanogiannis, Ioannis N.; Yortsos, Yanis C.

    2002-06-11

    This report examines the gas phase growth from a supersaturated, slightly compressible, liquid in a porous medium, driven by heat transfer and controlled by the application of a constant-rate decline of the system pressure.

  14. Lecithin hydrophobicity modulates the process of cholesterol crystal nucleation and growth in supersaturated model bile systems.

    OpenAIRE

    Ochi, H; Tazuma, S; Kajiyama, G

    1996-01-01

    The present study was performed to determine whether the degree of lecithin hydrophobicity regulates bile metastability and, therefore, affects the process of cholesterol crystallization. Supersaturated model bile (MB) solutions were prepared with an identical composition on a molar basis (taurocholate/lecithin/cholesterol, 73:19.5:7.5; total lipid concentration 9 g/dl) except for the lecithin species; egg yolk phosphatidylcholine, soybean phosphatidylcholine, 1-palmitoyl-2-linoleoyl-sn-phosp...

  15. Influence of Isovalent Impurity Ge on Nucleation and Morphology of Supersaturated Oxygen Precipitate in CZSi

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The effects of Ge in CZSi on the density and the rate of nucleation of supersaturated oxygen precipitation at lower annealing temperatures were examined.It is discovered that rod-like precipitation was suppressed when annealing at 700℃,but Ge has no effect on the morphology and the growth of oxygen precipitation at annealing temperatures more than 900℃.The results indicated that Ge neither acted as center of nucleation nor was involved in oxygen precipitation and its defect.

  16. Extremely slow carbon diffusion in carbon-supersaturated surface of ferrite

    Czech Academy of Sciences Publication Activity Database

    Čermák, Jiří; Král, Lubomír

    2014-01-01

    Roč. 52, č. 3 (2014), s. 125-133 ISSN 0023-432X R&D Projects: GA ČR(CZ) GAP108/11/0148; GA MŠk(CZ) ED1.1.00/02.0068 Institutional support: RVO:68081723 Keywords : carbon diffusion * carbon supersaturation * diffusion barrier * ferrite * P91 Subject RIV: BJ - Thermodynamics Impact factor: 0.406, year: 2014

  17. Experimental Precipitation of Carbonate Minerals: Effect of pH, Supersaturation and Substrate

    OpenAIRE

    Tetteh, Abednego

    2012-01-01

    Understanding the controlling factors and elucidating the requirements and conditions necessary for carbon dioxide (CO2) storage by mineral trapping (or carbonation) is of paramount interest for any technical application as a means for carbon dioxide capture and storage (CCS). The effect of pH, supersaturation and substrate has been studied using non-stirred batch reactors at initial constant temperature of 150 oC. These conditions are relevant for mineral trapping. A set of experiments was c...

  18. Decomposition of supersaturated solid solutions Mg-Ho and Mg-Gd

    International Nuclear Information System (INIS)

    Sukhanov, V.D.; Dobromyslov, A.V.; Rokhlin, L.L.; Dobatkina, T.V.

    2002-01-01

    Methods of electron microscopy and X-ray diffraction analysis are applied to study ageing magnesium base alloys with holmium and gadolinium. It is shown that the precipitation of supersaturated Mg base solid solutions goes through several subsequent stages and is accompanied by a considerable precipitation hardening effect at the stage of metastable phase precipitation. The influence of aging time and temperature on precipitation kinetics is established [ru

  19. In Silico Modeling Approach for the Evaluation of Gastrointestinal Dissolution, Supersaturation, and Precipitation of Posaconazole.

    Science.gov (United States)

    Hens, Bart; Pathak, Shriram M; Mitra, Amitava; Patel, Nikunjkumar; Liu, Bo; Patel, Sanjaykumar; Jamei, Masoud; Brouwers, Joachim; Augustijns, Patrick; Turner, David B

    2017-12-04

    The aim of this study was to evaluate gastrointestinal (GI) dissolution, supersaturation, and precipitation of posaconazole, formulated as an acidified (pH 1.6) and neutral (pH 7.1) suspension. A physiologically based pharmacokinetic (PBPK) modeling and simulation tool was applied to simulate GI and systemic concentration-time profiles of posaconazole, which were directly compared with intraluminal and systemic data measured in humans. The Advanced Dissolution Absorption and Metabolism (ADAM) model of the Simcyp Simulator correctly simulated incomplete gastric dissolution and saturated duodenal concentrations of posaconazole in the duodenal fluids following administration of the neutral suspension. In contrast, gastric dissolution was approximately 2-fold higher after administration of the acidified suspension, which resulted in supersaturated concentrations of posaconazole upon transfer to the upper small intestine. The precipitation kinetics of posaconazole were described by two precipitation rate constants, extracted by semimechanistic modeling of a two-stage medium change in vitro dissolution test. The 2-fold difference in exposure in the duodenal compartment for the two formulations corresponded with a 2-fold difference in systemic exposure. This study demonstrated for the first time predictive in silico simulations of GI dissolution, supersaturation, and precipitation for a weakly basic compound in part informed by modeling of in vitro dissolution experiments and validated via clinical measurements in both GI fluids and plasma. Sensitivity analysis with the PBPK model indicated that the critical supersaturation ratio (CSR) and second precipitation rate constant (sPRC) are important parameters of the model. Due to the limitations of the two-stage medium change experiment the CSR was extracted directly from the clinical data. However, in vitro experiments with the BioGIT transfer system performed after completion of the in silico modeling provided an almost

  20. Transport and transformation of soil-derived CO2, CH4 and DOC sustain CO2 supersaturation in small boreal streams.

    Science.gov (United States)

    Rasilo, Terhi; Hutchins, Ryan H S; Ruiz-González, Clara; Del Giorgio, Paul A

    2017-02-01

    Streams are typically supersaturated in carbon dioxide (CO 2 ) and methane (CH 4 ), and are recognized as important components of regional carbon (C) emissions in northern landscapes. Whereas there is consensus that in most of the systems the CO 2 emitted by streams represents C fixed in the terrestrial ecosystem, the pathways delivering this C to streams are still not well understood. We assessed the contribution of direct soil CO 2 injection versus the oxidation of soil-derived dissolved organic C (DOC) and CH 4 in supporting CO 2 supersaturation in boreal streams in Québec. We measured the concentrations of CO 2 , CH 4 and DOC in 43 streams and adjacent soil waters during summer base-flow period. A mass balance approach revealed that all three pathways are significant, and that the mineralization of soil-derived DOC and CH 4 accounted for most of the estimated stream CO 2 emissions (average 75% and 10%, respectively), and that these estimated contributions did not change significantly between the studied low order (≤3) streams. Whereas some of these transformations take place in the channel proper, our results suggest that they mainly occur in the hyporheic zones of the streams. Our results further show that stream CH 4 emissions can be fully explained by soil CH 4 inputs. This study confirms that these boreal streams, and in particular their hyporheic zones, are extremely active processors of soil derived DOC and CH 4 , not just vents for soil produced CO 2 . Copyright © 2016 Elsevier B.V. All rights reserved.

  1. Multiscale description of carbon-supersaturated ferrite in severely drawn pearlitic wires

    International Nuclear Information System (INIS)

    Nematollahi, Gh. Ali; Grabowski, Blazej; Raabe, Dierk; Neugebauer, Jörg

    2016-01-01

    A multiscale simulation approach based on atomistic calculations and a discrete diffusion model is developed and applied to carbon-supersaturated ferrite, as experimentally observed in severely deformed pearlitic steel. We employ the embedded atom method and the nudged elastic band technique to determine the energetic profile of a carbon atom around a screw dislocation in bcc iron. The results clearly indicate a special region in the proximity of the dislocation core where C atoms are strongly bound, but where they can nevertheless diffuse easily due to low barriers. Our analysis suggests that the previously proposed pipe mechanism for the case of a screw dislocation is unlikely. Instead, our atomistic as well as the diffusion model results support the so-called drag mechanism, by which a mobile screw dislocation is able to transport C atoms along its glide plane. Combining the C-dislocation interaction energies with density-functional-theory calculations of the strain dependent C formation energy allows us to investigate the C supersaturation of the ferrite phase under wire drawing conditions. Corresponding results for local and total C concentrations agree well with previous atom probe tomography measurements indicating that a significant contribution to the supersaturation during wire drawing is due to dislocations.

  2. Study of supersaturation of defects under neutron irradiation by Zener relaxation

    International Nuclear Information System (INIS)

    Gonzalez, Hector C.; Justus, Francisco J.W.

    2004-01-01

    Vacancy supersaturation in dynamic equilibrium under fast neutron irradiation could be determined by anelastic relaxation. This phenomenon is particularly noticeable in some substitutional binary alloys. Relaxation is due to the reordering of atoms pairs under a stress, being a local reordering at the atomic scale. Relaxation time (τ) is inversely proportional to the vacancy concentration (Cv) and decreases under irradiation because a dynamical equilibrium of vacancy concentration, higher than thermodynamic equilibrium, is established. Theoretical models allow estimating the magnitude of that supersaturation. Determinations of τ at different temperatures, with and without fast neutron irradiations, were made with an 'in situ' device placed in the high temperature loop in the RA1 CAC-CNEA reactor. An alloy Au-30% Ni was used, since it presents an appreciable Zener effect. The measurements were performed in a spring-shaped specimen in order to minimize temperature and flux gradients. An Arrhenius plot of τ was obtained, and it was observed that for temperatures lower than 220 C degrees a vacancy supersaturation exists. The lowest temperature of our experiments was 190 C degrees. A value of τ at this temperature was three times lower under irradiations. A plot of τ vs. fast neutron fluence (φ f t) at the irradiation temperature T= 203 C degrees was obtained. An increase of τ was observed. After an annealing at T = 280 C degrees, the value of τ recovers the value corresponding to the unirradiated case. This fact suggests that the loops produced by irradiation act as defect sinks. (author) [es

  3. Energy Levels of Defects Created in Silicon Supersaturated with Transition Metals

    Science.gov (United States)

    García, H.; Castán, H.; Dueñas, S.; García-Hemme, E.; García-Hernansaz, R.; Montero, D.; González-Díaz, G.

    2018-03-01

    Intermediate-band semiconductors have attracted much attention for use in silicon-based solar cells and infrared detectors. In this work, n-Si substrates have been implanted with very high doses (1013 cm-2 and 1014 cm-2) of vanadium, which gives rise to a supersaturated layer inside the semiconductor. However, the Mott limit was not exceeded. The energy levels created in the supersaturated silicon were studied in detail by means of thermal admittance spectroscopy. We found a single deep center at energy near E C - 200 meV. This value agrees with one of the levels found for vanadium in silicon. The capture cross-section values of the deep levels were also calculated, and we found a relationship between the capture cross-section and the energy position of the deep levels which follows the Meyer-Neldel rule. This process usually appears in processes involving multiple excitations. The Meyer-Neldel energy values agree with those previously obtained for silicon supersaturated with titanium and for silicon contaminated with iron.

  4. Unprecedented Al supersaturation in single-phase rock salt structure VAlN films by Al+ subplantation

    Science.gov (United States)

    Greczynski, G.; Mráz, S.; Hans, M.; Primetzhofer, D.; Lu, J.; Hultman, L.; Schneider, J. M.

    2017-05-01

    Modern applications of refractory ceramic thin films, predominantly as wear-protective coatings on cutting tools and on components utilized in automotive engines, require a combination of excellent mechanical properties, thermal stability, and oxidation resistance. Conventional design approaches for transition metal nitride coatings with improved thermal and chemical stability are based on alloying with Al. It is well known that the solubility of Al in NaCl-structure transition metal nitrides is limited. Hence, the great challenge is to increase the Al concentration substantially while avoiding precipitation of the thermodynamically favored wurtzite-AlN phase, which is detrimental to mechanical properties. Here, we use VAlN as a model system to illustrate a new concept for the synthesis of metastable single-phase NaCl-structure thin films with the Al content far beyond solubility limits obtained with conventional plasma processes. This supersaturation is achieved by separating the film-forming species in time and energy domains through synchronization of the 70-μs-long pulsed substrate bias with intense periodic fluxes of energetic Al+ metal ions during reactive hybrid high power impulse magnetron sputtering of the Al target and direct current magnetron sputtering of the V target in the Ar/N2 gas mixture. Hereby, Al is subplanted into the cubic VN grains formed by the continuous flux of low-energy V neutrals. We show that Al subplantation enables an unprecedented 42% increase in metastable Al solubility limit in V1-xAlxN, from x = 0.52 obtained with the conventional method to 0.75. The elastic modulus is 325 ± 5 GPa, in excellent agreement with density functional theory calculations, and approximately 50% higher than for corresponding films grown by dc magnetron sputtering. The extension of the presented strategy to other Al-ion-assisted vapor deposition methods or materials systems is straightforward, which opens up the way for producing supersaturated single

  5. Seasonal and interannual variability of dissolved oxygen around the Balearic Islands from hydrographic data

    Science.gov (United States)

    Balbín, R.; López-Jurado, J. L.; Aparicio-González, A.; Serra, M.

    2014-10-01

    Oceanographic data obtained between 2001 and 2011 by the Spanish Institute of Oceanography (IEO, Spain) have been used to characterise the spatial distribution and the temporal variability of the dissolved oxygen around the Balearic Islands (Mediterranean Sea). The study area includes most of the Western Mediterranean Sea, from the Alboran Sea to Cape Creus, at the border between France and Spain. Dissolved oxygen (DO) at the water surface is found to be in a state of equilibrium exchange with the atmosphere. In the spring and summer a subsurface oxygen supersaturation is observed due to the biological activity, above the subsurface fluorescence maximum. Minimum observed values of dissolved oxygen are related to the Levantine Intermediate Waters (LIW). An unusual minimum of dissolved oxygen concentrations was also recorded in the Alboran Sea Oxygen Minimum Zone. The Western Mediterranean Deep Waters (WMDW) and the Western Intermediate Waters (WIW) show higher values of dissolved oxygen than the Levantine Intermediate Waters due to their more recent formation. Using these dissolved oxygen concentrations it is possible to show that the Western Intermediate Waters move southwards across the Ibiza Channel and the deep water circulates around the Balearic Islands. It has also been possible to characterise the seasonal evolution of the different water masses and their dissolved oxygen content in a station in the Algerian sub-basin.

  6. Supersaturation induced by Itraconazole/Soluplus® micelles provided high GI absorption in vivo

    Directory of Open Access Journals (Sweden)

    Yue Zhong

    2016-04-01

    Full Text Available To investigate the effect of supersaturation induced by micelle formation during dissolution on the bioavailability of itraconazole (ITZ/Soluplus® solid dispersion. Solid dispersions prepared by hot melt extrusion (HME were compressed into tablets directly with other excipients. Dissolution behavior of ITZ tablets was studied by dissolution testing and the morphology of micelles in dissolution media was studied using transmission electron microscopy (TEM. Drug transferring from stomach into intestine was simulated to obtain a supersaturated drug solution. Bioavailability studies were performed on the ITZ tablets and Sporanox® in beagle dogs. The morphology of micelles in the dissolution media was observed to be spherical in shape, with an average size smaller than 100 nm. The supersaturated solutions formed by Soluplus® micelles were stable and no precipitation took place over a period of 180 min. Compared with Sporanox®, ITZ tablets exhibited a 2.50-fold increase in the AUC(0–96 of ITZ and a 1.95-fold increase in its active metabolite hydroxyitraconazole (OH-ITZ in the plasma of beagle dogs. The results obtained provided clear evidence that not only the increase in the dissolution rate in the stomach, but also the supersaturation produced by micelles in the small intestine may be of great assistance in the successful development of poorly water-soluble drugs. The micelles formed by Soluplus® enwrapped the molecular ITZ inside the core which promoted the amount of free drug in the intestinal cavity and carried ITZ through the aqueous boundary layer (ABL, resulting in high absorption by passive transportation across biological membranes. The uptake of intact micelles through pinocytosis together with the inhibition of P-glycoprotein-mediated drug efflux in intestinal epithelia contributed to the absorption of ITZ in the gastrointestinal tract. These results indicate that HME with Soluplus®, which can induce supersaturation by micelle

  7. BLM Colorado Oil & Gas Geophysical Permits (Dissolved)

    Data.gov (United States)

    Department of the Interior — KMZ File Format –This data is one feature type that is a part of a set consisting of six shapefiles pertaining to energy development and production in Colorado. The...

  8. BLM Colorado Oil and Gas Leases (Dissolved)

    Data.gov (United States)

    Department of the Interior — KMZ File Format –This data is one feature type that is a part of a set consisting of six shapefiles pertaining to energy development and production in Colorado. The...

  9. BLM Colorado Oil & Gas Geophysical Permits (Dissolved)

    Data.gov (United States)

    Department of the Interior — Shapefile Format –This data is one feature type that is a part of a set consisting of six shapefiles pertaining to energy development and production in Colorado. The...

  10. BLM Colorado Oil and Gas Units (Dissolve)

    Data.gov (United States)

    Department of the Interior — KMZ File Format –This data is one feature type that is a part of a set consisting of six shapefiles pertaining to energy development and production in Colorado. The...

  11. BLM Colorado Oil and Gas Leases (Dissolved)

    Data.gov (United States)

    Department of the Interior — Shapefile Format –This data is one feature type that is a part of a set consisting of six shapefiles pertaining to energy development and production in Colorado. The...

  12. BLM Colorado Oil and Gas Units (Dissolve)

    Data.gov (United States)

    Department of the Interior — Shapefile Format –This data is one feature type that is a part of a set consisting of six shapefiles pertaining to energy development and production in Colorado. The...

  13. Maintaining Supersaturation of Nimodipine by PVP with or without the Presence of Sodium Lauryl Sulfate and Sodium Taurocholate.

    Science.gov (United States)

    Pui, Yipshu; Chen, Yuejie; Chen, Huijun; Wang, Shan; Liu, Chengyu; Tonnis, Wouter; Chen, Linc; Serno, Peter; Bracht, Stefan; Qian, Feng

    2018-05-30

    Amorphous solid dispersion (ASD) is one of the most versatile supersaturating drug delivery systems to improve the dissolution rate and oral bioavailability of poorly water-soluble drugs. PVP based ASD formulation of nimodipine (NMD) has been marketed and effectively used in clinic for nearly 30 years, yet the mechanism by which PVP maintains the supersaturation and subsequently improves the bioavailability of NMD was rarely investigated. In this research, we first studied the molecular interactions between NMD and PVP by solution NMR, using CDCl 3 as the solvent, and the drug-polymer Flory-Huggins interaction parameter. No strong specific interaction between PVP and NMD was detected in the nonaqueous state. However, we observed that aqueous supersaturation of NMD could be significantly maintained by PVP, presumably due to the hydrophobic interactions between the hydrophobic moieties of PVP and NMD in aqueous medium. This hypothesis was supported by dynamic light scattering (DLS) and supersaturation experiments in the presence of different surfactants. DLS revealed the formation of NMD/PVP aggregates when NMD was supersaturated, suggesting the formation of hydrophobic interactions between the drug and polymer. The addition of surfactants, sodium lauryl sulfate (SLS) or sodium taurocholate (NaTC), into PVP maintained that NMD supersaturation demonstrated different effects: SLS could only improve NMD supersaturation with concentration above its critical aggregation concentration (CAC) value while not with lower concentration. Nevertheless, NaTC could prolong NMD supersaturation independent of concentration, with lower concentration outperformed higher concentration. We attribute these observations to PVP-surfactant interactions and the formation of PVP/surfactant complexes. In summary, despite the lack of specific interactions in the nonaqueous state, NMD aqueous supersaturation in the presence of PVP was attained by hydrophobic interactions between the hydrophobic

  14. Decompression sickness in breath-hold diving, and its probable connection to the growth and dissolution of small arterial gas emboli.

    Science.gov (United States)

    Goldman, Saul; Solano-Altamirano, J M

    2015-04-01

    We solved the Laplace equation for the radius of an arterial gas embolism (AGE), during and after breath-hold diving. We used a simple three-region diffusion model for the AGE, and applied our results to two types of breath-hold dives: single, very deep competitive-level dives and repetitive shallower breath-hold dives similar to those carried out by indigenous commercial pearl divers in the South Pacific. Because of the effect of surface tension, AGEs tend to dissolve in arterial blood when arteries remote from supersaturated tissue. However if, before fully dissolving, they reach the capillary beds that perfuse the brain and the inner ear, they may become inflated with inert gas that is transferred into them from these contiguous temporarily supersaturated tissues. By using simple kinetic models of cerebral and inner ear tissue, the nitrogen tissue partial pressures during and after the dive(s) were determined. These were used to theoretically calculate AGE growth and dissolution curves for AGEs lodged in capillaries of the brain and inner ear. From these curves it was found that both cerebral and inner ear decompression sickness are expected to occur occasionally in single competitive-level dives. It was also determined from these curves that for the commercial repetitive dives considered, the duration of the surface interval (the time interval separating individual repetitive dives from one another) was a key determinant, as to whether inner ear and/or cerebral decompression sickness arose. Our predictions both for single competitive-level and repetitive commercial breath-hold diving were consistent with what is known about the incidence of cerebral and inner ear decompression sickness in these forms of diving. Copyright © 2015 Elsevier Inc. All rights reserved.

  15. Raman spectroscopic studies on single supersaturated droplets of sodium and magnesium acetate.

    Science.gov (United States)

    Wang, Liang-Yu; Zhang, Yun-Hong; Zhao, Li-Jun

    2005-02-03

    Raman spectroscopy was used to study structural changes, in particular, the formation of contact-ion pairs in supersaturated aqueous NaCH(3)COO and Mg(CH(3)COO)(2) droplets at ambient temperatures. The single droplets levitated in an electrodynamic balance (EDB), lost water, and became supersaturated when the relative humidity (RH) decreased. For NaCH(3)COO droplet the water-to-solute molar ratio (WSR) was 3.87 without solidification when water molecules were not enough to fill in the first hydration layer of Na(+), in favor of the formation of contact-ion pairs. However, the symmetric stretching vibration band (nu(3) mode) of free -COO(-) constantly appeared at 1416 cm(-1), and no spectroscopic information related to monodentate, bidentate, or bridge bidentate contact-ion pairs was observed due to the weak interactions between the Na(+) and acetate ion. On the other hand, the band of methyl deformation blue shifted from 1352 to 1370 cm(-1) (at RH = 34.2%, WSR = 2.43), corresponding to the solidification process of a novel metastable phase in the highly supersaturated solutions. With further decreasing RH, a small amount of supersaturated solution still existed and was proposed to be hermetically covered by the metastable phase of the particle. In contrast, the interaction between Mg(2+) and acetate ion is much stronger. When WSR decreased from 21.67 to 2.58 for the Mg(CH(3)COO)(2) droplet, the band of C-C-symmetric stretching (nu(4) mode) had a blue shift from 936 to 947 cm(-1). The intensity of the two new shoulders (approximately 1456 and approximately 1443 cm(-1)) of the nu(3) band of free -COO(-) at 1420 cm(-1) increased with the decrease of WSR. These changes were attributed to the formation of contact-ion pairs with bidentate structures. In particular, the small frequency difference between the shoulder at approximately 1443 cm(-1) and the nu(3) band of the free -COO(-) group (approximately 1420 cm(-1)) was proposed to be related to the formation of a chain

  16. Detection of hydrogen dissolved in acrylonitrile butadiene rubber by 1H nuclear magnetic resonance

    Science.gov (United States)

    Nishimura, Shin; Fujiwara, Hirotada

    2012-01-01

    Rubber materials, which are used for hydrogen gas seal, can dissolve hydrogen during exposure in high-pressure hydrogen gas. Dissolved hydrogen molecules were detected by solid state 1H NMR of the unfilled vulcanized acrylonitrile butadiene rubber. Two signals were observed at 4.5 ppm and 4.8 ppm, which were assignable to dissolved hydrogen, in the 1H NMR spectrum of NBR after being exposed 100 MPa hydrogen gas for 24 h at room temperature. These signals were shifted from that of gaseous hydrogen molecules. Assignment of the signals was confirmed by quantitative estimation of dissolved hydrogen and peak area of the signals.

  17. Method to Estimate the Dissolved Air Content in Hydraulic Fluid

    Science.gov (United States)

    Hauser, Daniel M.

    2011-01-01

    In order to verify the air content in hydraulic fluid, an instrument was needed to measure the dissolved air content before the fluid was loaded into the system. The instrument also needed to measure the dissolved air content in situ and in real time during the de-aeration process. The current methods used to measure the dissolved air content require the fluid to be drawn from the hydraulic system, and additional offline laboratory processing time is involved. During laboratory processing, there is a potential for contamination to occur, especially when subsaturated fluid is to be analyzed. A new method measures the amount of dissolved air in hydraulic fluid through the use of a dissolved oxygen meter. The device measures the dissolved air content through an in situ, real-time process that requires no additional offline laboratory processing time. The method utilizes an instrument that measures the partial pressure of oxygen in the hydraulic fluid. By using a standardized calculation procedure that relates the oxygen partial pressure to the volume of dissolved air in solution, the dissolved air content is estimated. The technique employs luminescent quenching technology to determine the partial pressure of oxygen in the hydraulic fluid. An estimated Henry s law coefficient for oxygen and nitrogen in hydraulic fluid is calculated using a standard method to estimate the solubility of gases in lubricants. The amount of dissolved oxygen in the hydraulic fluid is estimated using the Henry s solubility coefficient and the measured partial pressure of oxygen in solution. The amount of dissolved nitrogen that is in solution is estimated by assuming that the ratio of dissolved nitrogen to dissolved oxygen is equal to the ratio of the gas solubility of nitrogen to oxygen at atmospheric pressure and temperature. The technique was performed at atmospheric pressure and room temperature. The technique could be theoretically carried out at higher pressures and elevated

  18. "Supersaturated" self-assembled charge-selective interfacial layers for organic solar cells.

    Science.gov (United States)

    Song, Charles Kiseok; Luck, Kyle A; Zhou, Nanjia; Zeng, Li; Heitzer, Henry M; Manley, Eric F; Goldman, Samuel; Chen, Lin X; Ratner, Mark A; Bedzyk, Michael J; Chang, Robert P H; Hersam, Mark C; Marks, Tobin J

    2014-12-24

    To achieve densely packed charge-selective organosilane-based interfacial layers (IFLs) on the tin-doped indium oxide (ITO) anodes of organic photovoltaic (OPV) cells, a series of Ar2N-(CH2)n-SiCl3 precursors with Ar = 3,4-difluorophenyl, n = 3, 6, 10, and 18, was synthesized, characterized, and chemisorbed on OPV anodes to serve as IFLs. To minimize lateral nonbonded -NAr2···Ar2N- repulsions which likely limit IFL packing densities in the resulting self-assembled monolayers (SAMs), precursor mixtures having both small and large n values are simultaneously deposited. These "heterogeneous" SAMs are characterized by a battery of techniques: contact angle measurements, X-ray reflectivity, X-ray photoelectron spectroscopy, ultraviolet photoelectron spectroscopy (UPS), cyclic voltammetry, and DFT computation. It is found that the headgroup densities of these "supersaturated" heterogeneous SAMs (SHSAMs) are enhanced by as much as 17% versus their homogeneous counterparts. Supersaturation significantly modifies the IFL properties including the work function (as much as 16%) and areal dipole moment (as much as 49%). Bulk-heterojunction OPV devices are fabricated with these SHSAMs: ITO/IFL/poly[[4,8-bis[(2-ethylhexyl)oxy]benzo[1,2-b:4,5-b']dithiophene-2,6-diyl][2-[[(2-ethylhexyl)oxy]carbonyl]-3-fluorothieno[3,4-b]thiophenediyl

  19. A comparative study of vitamin E TPGS/HPMC supersaturated system and other solubilizer/polymer combinations to enhance the permeability of a poorly soluble drug through the skin.

    Science.gov (United States)

    Ghosh, Indrajit; Michniak-Kohn, Bozena

    2012-11-01

    In transdermal drug delivery systems (TDDS), it is a challenge to achieve stable and prolonged high permeation rates across skin, because the concentration of the drug dissolved in the matrix has to be high in order to maintain zero order release kinetics of the drug. In case of poorly soluble drugs, due to thermodynamic challenges, there is a high tendency for the drug to nucleate immediately after formulating or even during storage. The present study focuses on the efficiency of vitamin E TPGS/HPMC supersaturated solution and other solubilizer/polymer systems to improve the solubility of the drug and inhibit crystal growth in the transdermal formulation. Effect of several solubilizers, for example, Pluronic F-127, vitamin E TPGS and co-solvent, for example, propylene glycol (PG) were studied on the supersaturated systems of ibuprofen as model drug. Various stabilizers such as hydroxylpropyl methylcellulose (HPMC 3 cps) and polyvinylpyrrolidone (PVP K-30) were examined to evaluate their crystal inhibitory effects. Different analytical tools were used in this study to detect the growth of crystals in the systems. Vitamin E TPGS and HPMC 3 cps formulation produced the highest permeation rate of the drug as compared to other systems. In addition, the onset of crystallization time was shown to be longer with this formulation as compared to other solubilizer/polymer combinations.

  20. Characterizing Dissolved Gases in Cryogenic Liquid Fuels

    Science.gov (United States)

    Richardson, Ian A.

    Pressure-Density-Temperature-Composition (PrhoT-x) measurements of cryogenic fuel mixtures are a historical challenge due to the difficulties of maintaining cryogenic temperatures and precision isolation of a mixture sample. For decades NASA has used helium to pressurize liquid hydrogen propellant tanks to maintain tank pressure and reduce boil off. This process causes helium gas to dissolve into liquid hydrogen creating a cryogenic mixture with thermodynamic properties that vary from pure liquid hydrogen. This can lead to inefficiencies in fuel storage and instabilities in fluid flow. As NASA plans for longer missions to Mars and beyond, small inefficiencies such as dissolved helium in liquid propellant become significant. Traditional NASA models are unable to account for dissolved helium due to a lack of fundamental property measurements necessary for the development of a mixture Equation Of State (EOS). The first PrhoT-x measurements of helium-hydrogen mixtures using a retrofitted single-sinker densimeter, magnetic suspension microbalance, and calibrated gas chromatograph are presented in this research. These measurements were used to develop the first multi-phase EOS for helium-hydrogen mixtures which was implemented into NASA's Generalized Fluid System Simulation Program (GFSSP) to determine the significance of mixture non-idealities. It was revealed that having dissolved helium in the propellant does not have a significant effect on the tank pressurization rate but does affect the rate at which the propellant temperature rises. PrhoT-x measurements are conducted on methane-ethane mixtures with dissolved nitrogen gas to simulate the conditions of the hydrocarbon seas of Saturn's moon Titan. Titan is the only known celestial body in the solar system besides Earth with stable liquid seas accessible on the surface. The PrhoT-x measurements are used to develop solubility models to aid in the design of the Titan Submarine. NASA is currently designing the submarine

  1. Release of dissolved 85Kr by standing

    International Nuclear Information System (INIS)

    Ootsuka, Norikatsu; Yamamoto, Tadatoshi; Tsukui, Kohei

    1986-01-01

    The experiments on the release of dissolved 85 Kr by standing at room temperature were carried out to examine the influence of liquid level in a sampler and properties of solvent on the release efficiency. Six kinds of organic solvents as well as water were taken as solvents. The half-life period in case of the decrease in concentration of the dissolved 85 Kr which was used as an index of release efficiency, was proportional to the liquid level in the sampler and was inversely proportional to the diffusion coefficient of Kr gas in solvent. For organic solvents belonging to homologous series, the half-life period became longer with increasing the carbon number of solvent molecule. From the relationship between the half-life period and the carbon number, the release efficiency in the dissolved 85 Kr can be predicted for any commonly used solvent as a practical application. This method was found to be an effective means of removing the dissolved 85 Kr of low level though it takes rather long time. (author)

  2. Subcooled boiling effect on dissolved gases behaviour

    International Nuclear Information System (INIS)

    Zmitko, M.; Sinkule, J.; Linek, V.

    1999-01-01

    A model describing dissolved gasses (hydrogen, nitrogen) and ammonia behaviour in subcooled boiling conditions of WWERs was developed. Main objective of the study was to analyse conditions and mechanisms leading to formation of a zone with different concentration of dissolved gases, eg. a zone depleted in dissolved hydrogen in relation to the bulk of coolant. Both, an equilibrium and dynamic approaches were used to describe a depletion of the liquid surrounding a steam bubble in the gas components. The obtained results show that locally different water chemistry conditions can be met in the subcooled boiling conditions, especially, in the developed subcooled boiling regime. For example, a 70% hydrogen depletion in relation to the bulk of coolant takes about 1 ms and concerns a liquid layer of 1 μn surrounding the steam bubble. The locally different concentration of dissolved gases can influence physic-chemical and radiolytic processes in the reactor system, eg. Zr cladding corrosion, radioactivity transport and determination of the critical hydrogen concentration. (author)

  3. Kinetics of a new phase formation in supersaturated solid solutions. 1. Dilute one-component systems

    International Nuclear Information System (INIS)

    Dubinko, V.I.

    1991-07-01

    A complete set of kinetic equations describing the diffusion decay of supersaturated solutions, as well as the formation of new-phase fluctuations in equilibrium systems, is derived. A novel method of determining forward and backward reaction rates entering the master equation is proposed which does not require the use of any reference cluster size distribution, either the constrained or the true equilibrium one, employed in all modifications of the classical nucleation theory. Instead, this reference distribution can be obtained as an equilibrium solution of the present master equation. The main advantage of this method is the possibility to take into account various factors affecting the diffusion decay, such as the reaction kinetics at the precipitate surfaces and the diffusion kinetics in the mother phase with account of elastic interaction between nucleating species and their clusters. The latter is of a key importance in the irradiation environment considered in the forthcoming second part of the article. (author). 3 refs

  4. Morphology evolution of hierarchical ZnO nanostructures modulated by supersaturation and growth temperature

    Science.gov (United States)

    Yan, Youguo; Zhou, Lixia; Yu, Lianqing; Zhang, Ye

    2008-07-01

    Three kinds of ZnO hierarchical structures, nanocombs with tube- and needle-shaped teeth and hierarchical nanorod arrays, were successfully synthesized through the chemical vapor deposition method. Combining the experimental parameters, the microcosmic growing conditions (growth temperature and supersaturation) along the flux was discussed at length, and, based on the conclusions, three reasonable growth processes were proposed. The results and discussions were beneficial to further realize the relation between the growing behavior of the nanomaterial and microcosmic conditions, and the hierarchical nanostructures obtained were also expected to have potential applications as functional blocks in future nanodevices. Furthermore, the study of photoluminescence further indicated that the physical properties were strongly dependent on the crystal structure.

  5. Double crystal X-ray analysis of phosphorus precipitation in supersaturated Si-P solid solutions

    International Nuclear Information System (INIS)

    Servidori, M.; Zini, Q.; Dal Monte, C.

    1983-01-01

    The physical nature of the electrically inactive phosphorus in silicon is investigated by double crystal X-ray diffraction measurements. This analysis is performed on laser annealed supersaturated samples, doped by ion implantation up to 5 x 10 21 cm -3 . After isothermal heat treatments, these solid solutions show marked reductions in the electrically active phosphorus concentration. In particular, 850 0 C heatings give rise to a carrier concentration which corresponds to the phosphorus solubility in equilibrium with the inactive dopant. This dopant is characterized by means of lattice strain measurements: they are found consistent with the presence of perfectly coherent cubic SiP precipitates. This result is in agreement with the one obtained in preceeding works by electrical measurements and transmission electron microscopy observations and contradicts the hypothesis that the excess dopant atoms are, at least in part, charged point defects (E-centres). (author)

  6. Water uptake of clay and desert dust aerosol particles at sub- and supersaturated water vapor conditions.

    Science.gov (United States)

    Herich, Hanna; Tritscher, Torsten; Wiacek, Aldona; Gysel, Martin; Weingartner, Ernest; Lohmann, Ulrike; Baltensperger, Urs; Cziczo, Daniel J

    2009-09-28

    Airborne mineral dust particles serve as cloud condensation nuclei (CCN), thereby influencing the formation and properties of warm clouds. It is therefore of atmospheric interest how dust aerosols with different mineralogy behave when exposed to high relative humidity (RH) or supersaturation (SS) with respect to liquid water. In this study the subsaturated hygroscopic growth and the supersaturated cloud condensation nucleus activity of pure clays and real desert dust aerosols were determined using a hygroscopicity tandem differential mobility analyzer (HTDMA) and a cloud condensation nuclei counter (CCNC), respectively. Five different illite, montmorillonite and kaolinite clay samples as well as three desert dust samples (Saharan dust (SD), Chinese dust (CD) and Arizona test dust (ATD)) were investigated. Aerosols were generated both with a wet and a dry disperser. The water uptake was parameterized via the hygroscopicity parameter kappa. The hygroscopicity of dry generated dust aerosols was found to be negligible when compared to processed atmospheric aerosols, with CCNC derived kappa values between 0.00 and 0.02 (the latter corresponds to a particle consisting of 96.7% by volume insoluble material and approximately 3.3% ammonium sulfate). Pure clay aerosols were generally found to be less hygroscopic than natural desert dust particles. The illite and montmorillonite samples had kappa approximately 0.003. The kaolinite samples were less hygroscopic and had kappa=0.001. SD (kappa=0.023) was found to be the most hygroscopic dry-generated desert dust followed by CD (kappa=0.007) and ATD (kappa=0.003). Wet-generated dust showed an increased water uptake when compared to dry-generated samples. This is considered to be an artifact introduced by redistribution of soluble material between the particles. Thus, the generation method is critically important when presenting such data. These results indicate any atmospheric processing of a fresh mineral dust particle which

  7. Kinetics of release of a model disperse dye from supersaturated cellulose acetate matrices.

    Science.gov (United States)

    Papadokostaki, K G; Petropoulos, J H

    1998-08-14

    A study has been made of the kinetics of release into water of a model disperse dye (4-aminoazobenzene) from supersaturated solvent-cast cellulose acetate films at room temperature. Excess dye was introduced into the polymer matrix by: (i) sorption from aqueous solution at 100 degrees C; (ii) sorption from the vapour phase at 110 degrees C; or (iii) prior dissolution in the casting solvent. The effect of the method of introduction of the dye, the degree of supersaturation and the rate of agitation of the bath were investigated. Under conditions of strong agitation, the release kinetics from films dyed by method (i) or (iii) were in general accord with the theoretical model which assumes solute in the film in excess of the saturation limit to be in the form of immobile aggregates at equilibrium with mobile dye; although the value of the diffusion coefficient of the solute in the film was found to be substantially higher than that in the unsaturated film. On the other hand, when dyeing had been effected from the vapour phase, Fickian kinetics was followed and the diffusion coefficient was found to be equal to that observed in unsaturated film. It was concluded that under these conditions, the excess dye in the film tends to remain molecularly dispersed. Under conditions of slow agitation, the square root of t kinetics was not attained in many instances. General and early-time approximate expressions based on the Roseman-Higuchi model proved useful for the interpretation of the results in such cases; while the said model was extended to include the effect of significant variation of the partition coefficient of the solute with concentration.

  8. Vacancies supersaturation induced by fast neutron irradiation in FeNi alloys

    International Nuclear Information System (INIS)

    Lucki, G.; Chambron, W.; Watanabe, S.; Verdone, J.

    1975-01-01

    The void formation in metals and alloys during irradiation with high-energy particles is a problem of interest in physics and of paramount importance in nuclear technology. Voids are formed as a consequence of vacancy supersaturation and result in swelling as well as in changes of mechanical, electrical and magnetic properties of materials used in power reactors. Isothermal annealings were performed between 400 and 500 0 C with and without fast-neutron (1 MeV) irradiation. Pure Fe--Ni (50--50 at. percent) was irradiated in the Melousine reactor in Grenoble, and Fe--Ni(Mo) (50--50 at. percent + 50 ppM), in the IEAR-1 reactor at the Instituto de Energia Atomica in Sao Paulo. The toroidal-shaped specimens were fabricated from Johnson Mathey zone-refined ingots, and were initially annealed at 800 0 C during 1 h in hydrogen atmosphere and then slowly cooled (4 h) inside the furnace. Magnetic After Effect measurements (MAE) permitted the evaluation of activation energies during fast-neutron irradiation (1.54 eV) and without irradiation (3.14 eV) for pure Fe--Ni and respectively (1.36 eV) and (2.32 eV) for Fe--Ni(Mo). Since the time constants of the relaxation process are inversely proportional to the vacancy concentration, a quantitative evaluation of vacancy supersaturation was made; it decreases from the value 700 at 410 0 C to the value 40 at 490 0 C for pure Fe--Ni and from 765 to 121 for Fe--Ni(Mo) in the same temperature range. 3 figures, 5 tables

  9. Supersaturation-nucleation behavior of poorly soluble drugs and its impact on the oral absorption of drugs in thermodynamically high-energy forms.

    Science.gov (United States)

    Ozaki, Shunsuke; Minamisono, Takuma; Yamashita, Taro; Kato, Takashi; Kushida, Ikuo

    2012-01-01

    In order to better understand the oral absorption behavior of poorly water-soluble drugs, their supersaturation-nucleation behavior was characterized in fasted state simulated intestinal fluid. The induction time (t(ind)) for nucleation was measured for four model drugs: itraconazole, erlotinib, troglitazone, and PLX4032. Supersaturated solutions were prepared by solvent shift method, and nucleation initiation was monitored by ultraviolet detection. The relationship between t(ind) and degree of supersaturation was analyzed in terms of classical nucleation theory. The defined supersaturation stability proved to be compound specific. Clinical data on oral absorption were investigated for drugs in thermodynamically high-energy forms such as amorphous forms and salts and was compared with in vitro supersaturation-nucleation characteristics. Solubility-limited maximum absorbable dose was proportionate to intestinal effective drug concentrations, which are related to supersaturation stability and thermodynamic solubility. Supersaturation stability was shown to be an important factor in determining the effect of high-energy forms. The characterization of supersaturation-nucleation behavior by the presented method is, therefore, valuable for assessing the potential absorbability of poorly water-soluble drugs. Copyright © 2011 Wiley-Liss, Inc.

  10. Evaluation of water quality by chlorophyll and dissolved oxygen

    International Nuclear Information System (INIS)

    Latif, Z.; Tasneem, M.A.; Javed, T.; Butt, S.; Fazil, M.; Ali, M.; Sajjad, M.I.

    2002-01-01

    This paper focuses on the impact of Chlorophyll and dissolved Oxygen on water quality. Kalar Kahar and Rawal lakes were selected for this research. A Spectrophotometer was used for determination of Chlorophyll a, Chlorophyll b, Chlorophyll c and Pheophytin pigment. Dissolved Oxygen was measured in situ, using dissolved oxygen meter. The gamma O/sup 18/ of dissolved Oxygen, like concentration, is affected primarily by three processes: air water gas exchange, respiration and photosynthesis; gamma O/sup 18/ is analyzed on isotopic ratio mass spectrometer, after extraction of dissolved Oxygen from water samples, followed by purification and conversion into CO/sub 2/. Rawal lake receives most of the water from precipitation during monsoon period and supplemented by light rains in December and January. This water is used throughout the year for drinking purposes in Rawalpindi city. The water samples were collected from 5, 7.5, and 10 meters of depth for seasonal studies of physiochemical and isotopic parameters of water and dissolved Oxygen. Optimum experimental conditions for delta O/sup 18/ analysis of dissolved Oxygen from aqueous samples were determined. Stratification of dissolved Oxygen was observed in Rawal Lake before rainy season in summer. The water quality deteriorates with depth, because the respiration exceeds the photosynthesis and gas exchange. The concentration and delta O/sup 18/ of dissolved Oxygen show no variation with depth in 1998 winter sampling. Kalar Kahar lake gets water from springs, which are recharged by local rains on the nearby mountains. It is a big lake, with shallow and uniform depth of nearly 1.5 meters. A lot of vegetation can be seen on the periphery of the lake. Algae have grown on the floor of the lake Water samples were collected from the corner with large amount of vegetation and from the center of the lake for dissolved Oxygen and Chlorophyll measurements. Chlorophyll result shows that Kalar Kahar Lake falls in Eutrophic category

  11. Use of a screening method to determine excipients which optimize the extent and stability of supersaturated drug solutions and application of this system to solid formulation design.

    Science.gov (United States)

    Vandecruys, Roger; Peeters, Jef; Verreck, Geert; Brewster, Marcus E

    2007-09-05

    Assessing the effect of excipients on the ability to attain and maintain supersaturation of drug-based solution may provide useful information for the design of solid formulations. Judicious selection of materials that affect either the extent or stability of supersaturating drug delivery systems may be enabling for poorly soluble drug candidates or other difficult-to-formulate compounds. The technique suggested herein is aimed at providing a screening protocol to allow preliminary assessment of these factors based on small to moderate amounts of drug substance. A series of excipients were selected that may, by various mechanisms, affect supersaturation including pharmaceutical polymers such as HMPC and PVP, surfactants such as Polysorbate 20, Cremophor RH40 and TPGS and hydrophilic cyclodextrins such as HPbetaCD. Using a co-solvent based method and 25 drug candidates, the data suggested, on the whole, that the surfactants and the selected cyclodextrin seemed to best augment the extent of supersaturation but had variable benefits as stabilizers, while the pharmaceutical polymers had useful effect on supersaturation stability but were less helpful in increasing the extent of supersaturation. Using these data, a group of simple solid dosage forms were prepared and tested in the dog for one of the drug candidates. Excipients that gave the best extent and stability for the formed supersaturated solution in the screening assay also gave the highest oral bioavailability in the dog.

  12. Facet-controlled phase separation in supersaturated Au-Ni nanoparticles upon shape equilibration

    Energy Technology Data Exchange (ETDEWEB)

    Herz, A., E-mail: andreas.herz@tu-ilmenau.de, E-mail: dong.wang@tu-ilmenau.de; Rossberg, D.; Hentschel, M.; Theska, F.; Wang, D., E-mail: andreas.herz@tu-ilmenau.de, E-mail: dong.wang@tu-ilmenau.de; Schaaf, P. [Department of Materials for Electronics and Electrical Engineering, Institute of Materials Science and Engineering and Institute of Micro- and Nanotechnologies MacroNano, TU Ilmenau, D-98693 Ilmenau (Germany); Friák, M. [Institute of Physics of Materials, Academy of Sciences of the Czech Republic, v.v.i., Žižkova 22, CZ-616 62 Brno (Czech Republic); Central European Institute of Technology, CEITEC MU, Masaryk University, Kamenice 5, CZ-625 00 Brno (Czech Republic); Holec, D. [Department of Physical Metallurgy and Materials Testing, Montanuniversität Leoben, A-8700 Leoben (Austria); Šob, M. [Central European Institute of Technology, CEITEC MU, Masaryk University, Kamenice 5, CZ-625 00 Brno (Czech Republic); Institute of Physics of Materials, Academy of Sciences of the Czech Republic, v.v.i., Žižkova 22, CZ-616 62 Brno (Czech Republic); Department of Chemistry, Faculty of Science, Masaryk University, Kotlářská 2, CZ-611 37 Brno (Czech Republic); Schneeweiss, O. [Institute of Physics of Materials, Academy of Sciences of the Czech Republic, v.v.i., Žižkova 22, CZ-616 62 Brno (Czech Republic)

    2015-08-17

    Solid-state dewetting is used to fabricate supersaturated, submicron-sized Au-Ni solid solution particles out of thin Au/Ni bilayers by means of a rapid thermal annealing technique. Phase separation in such particles is studied with respect to their equilibrium crystal (or Wulff) shape by subsequent annealing at elevated temperature. It is found that (100) faceting planes of the equilibrated particles are enriched with Ni and (111) faces with Au. Both phases are considered by quantum-mechanical calculations in combination with an error-reduction scheme that was developed to compensate for a missing exchange-correlation potential that would reliably describe both Au and Ni. The observed phase configuration is then related to the minimization of strongly anisotropic elastic energies of Au- and Ni-rich phases and results in a rather unique nanoparticle composite state that is characterized by nearly uniform value of elastic response to epitaxial strains all over the faceted surface. The same conclusion is yielded also by evaluating bi-axial elastic moduli when employing interpolated experimental elastic constants. This work demonstrates a useful route for studying features of physical metallurgy at the mesoscale.

  13. Manufacture of nanosized apatite coatings on titanium with different surface treatments using a supersaturated calcification solution

    Directory of Open Access Journals (Sweden)

    Adrian Paz Ramos

    Full Text Available The biomimetic method is used for the deposition of calcium phosphate coatings (Ca - P on the surface of different biomaterials. However, the application of this method requires long exposure times in order to obtain a suitable layer thickness for its use in medical devices. In this paper, we present a fast approach to obtain apatite coatings on titanium, using a combination of supersaturated calcification solution (SCS with chemical modification of the titanium surface. Also, it was evaluated the effect of four different surface treatments on the apatite deposition rate. Commercially pure titanium plates were activated by chemical or thermochemical treatments. Then, the activated samples were immersed in a solution with high content of calcium and phosphate ions at 37 ºC for 24 h, mimicking the physiological conditions. The coatings were studied by Fourier transform infrared spectroscopy (FTIR, X-ray diffraction (XRD, scanning electron microscopy (SEM and energy dispersive X-ray spectroscopy (EDX. The use of SCS solutions allowed the formation of crystalline hydroxyapatite coatings within a period of 24 h with a thickness between 1 and 5.3 µm. Besides, precipitates of hydroxyapatite nanoparticles with a globular configuration, forming aggregates with submicrometer size, were found in SCS solutions.

  14. Vacancies supersaturation induced by fast neutronn irradiation in FeNi alloys

    International Nuclear Information System (INIS)

    Lucki, G.; Watanabe, S.; Chambron, W.; Verdoni, J.

    1976-01-01

    Isothermal annealings have been performed between 400 and 555 0 C with and without fast neutron (1 MeV) irradiation. Pure FeNi (50-50 at %) was irradiated in the Melousine reactor in Grenoble and FeNiMO (50-50 at % + 50 ppm.) in the IEAR 1 reactor at the Instituto de Energia Atomica in Sao Paulo. The toroidal shaped specimens were fabricated from Johnson Mathey zone refined ingots and were initially annealed at 800 0 C during 1 h in hydrogen atmosphere and then slowly cooled (4 h) inside the furnace. Magnetic After Effect Measurements (MAE) permitted the evaluation of activation energies during fast neutron irradiation (1.54eV) and without irradiation (3.14eV) for pure FeNi and respectively (1.36eV) and 2.32eV) for FeNiMO. Since the time constants of relaxation process are inversely proportional to the vacancies comcentration a quantitative evaluation of vacancies supersaturation was made it decreases from value 700 at 410 0 C to the value 40 at 190 0 C for pure FeNi and from 765 to 121 for FeNiMO in the same temperature range

  15. Energy levels distribution in supersaturated silicon with titanium for photovoltaic applications

    International Nuclear Information System (INIS)

    Pérez, E.; Castán, H.; García, H.; Dueñas, S.; Bailón, L.; Montero, D.; García-Hernansanz, R.; García-Hemme, E.; González-Díaz, G.; Olea, J.

    2015-01-01

    In the attempt to form an intermediate band in the bandgap of silicon substrates to give it the capability to absorb infrared radiation, we studied the deep levels in supersaturated silicon with titanium. The technique used to characterize the energy levels was the thermal admittance spectroscopy. Our experimental results showed that in samples with titanium concentration just under Mott limit there was a relationship among the activation energy value and the capture cross section value. This relationship obeys to the well known Meyer-Neldel rule, which typically appears in processes involving multiple excitations, like carrier capture/emission in deep levels, and it is generally observed in disordered systems. The obtained characteristic Meyer-Neldel parameters were Tmn = 176 K and kTmn = 15 meV. The energy value could be associated to the typical energy of the phonons in the substrate. The almost perfect adjust of all experimental data to the same straight line provides further evidence of the validity of the Meyer Neldel rule, and may contribute to obtain a deeper insight on the ultimate meaning of this phenomenon

  16. Energy levels distribution in supersaturated silicon with titanium for photovoltaic applications

    Energy Technology Data Exchange (ETDEWEB)

    Pérez, E., E-mail: eduper@ele.uva.es; Castán, H.; García, H.; Dueñas, S.; Bailón, L. [Dept. de Electricidad y Electrónica, Universidad de Valladolid, ETSI Telecomunicación, Paseo de Belén 15, 47011 Valladolid (Spain); Montero, D.; García-Hernansanz, R.; García-Hemme, E.; González-Díaz, G. [Dept. de Física Aplicada III (Electricidad y Electrónica), Univ. Complutense de Madrid, 28040 Madrid (Spain); CEI Campus Moncloa, UCM-UPM, 28040 Madrid (Spain); Olea, J. [CEI Campus Moncloa, UCM-UPM, 28040 Madrid (Spain); Instituto de Energía Solar, E.T.S.I. de Telecomunicación, Univ. Politécnica de Madrid, 28040 Madrid (Spain)

    2015-01-12

    In the attempt to form an intermediate band in the bandgap of silicon substrates to give it the capability to absorb infrared radiation, we studied the deep levels in supersaturated silicon with titanium. The technique used to characterize the energy levels was the thermal admittance spectroscopy. Our experimental results showed that in samples with titanium concentration just under Mott limit there was a relationship among the activation energy value and the capture cross section value. This relationship obeys to the well known Meyer-Neldel rule, which typically appears in processes involving multiple excitations, like carrier capture/emission in deep levels, and it is generally observed in disordered systems. The obtained characteristic Meyer-Neldel parameters were Tmn = 176 K and kTmn = 15 meV. The energy value could be associated to the typical energy of the phonons in the substrate. The almost perfect adjust of all experimental data to the same straight line provides further evidence of the validity of the Meyer Neldel rule, and may contribute to obtain a deeper insight on the ultimate meaning of this phenomenon.

  17. Method of dissolving metal ruthenium

    International Nuclear Information System (INIS)

    Tsuno, Masao; Soda, Yasuhiko; Kuroda, Sadaomi; Koga, Tadaaki.

    1988-01-01

    Purpose: To dissolve and clean metal ruthenium deposited to the inner surface of a dissolving vessel for spent fuel rods. Method: Metal ruthenium is dissolved in a solution of an alkali metal hydroxide to which potassium permanganate is added. As the alkali metal hydroxide used herein there can be mentioned potassium hydroxide, sodium hydroxide and lithium hydroxide can be mentioned, which is used as an aqueous solution from 5 to 20 % concentration in view of the solubility of metal ruthenium and economical merit. Further, potassium permanganate is used by adding to the solution of alkali metal hydroxide at a concentration of 1 to 5 %. (Yoshihara, H.)

  18. The impact of dissolved fluorine on bubble nucleation in hydrous rhyolite melts

    Science.gov (United States)

    Gardner, James E.; Hajimirza, Sahand; Webster, James D.; Gonnermann, Helge M.

    2018-04-01

    Surface tension of hydrous rhyolitic melt is high enough that large degrees of supersaturation are needed to homogeneously nucleate H2O bubbles during eruptive magma ascent. This study examines whether dissolved fluorine lowers surface tension of hydrous rhyolite, and thus lowers the supersaturation required for bubble nucleation. Fluorine was targeted because it, like H2O, changes melt properties and is highly soluble, unlike all other common magmatic volatiles. Rhyolite melts were saturated at Ps = 245 MPa with H2O fluid that contained F, generating rhyolite with 6.7 ± 0.4 wt.% H2O and 1.1-1.3 wt.% F. When these melts were decompressed rapidly to Pf = 149-202 MPa and quenched after 60 s, bubbles nucleated at supersaturations of ΔP = Ps - Pf ≥52 MPa, and reached bubble number densities of NB = 1012-13 m-3 at ΔP = 78-101 MPa. In comparison, rhyolite saturated with 6.34 ± 0.09 wt.% H2O, but only 0.25 wt.% F, did not nucleate bubbles until ΔP ≥ 100-116 MPa, and even then, at significantly lower NB (<1010 m-3). Numerical modeling of bubble nucleation and growth was used to estimate the values of surface tension required to generate the observed values of NB. Slight differences in melt compositions (i.e., alkalinity and H2O content), H2O diffusivity, or melt viscosity cannot explain the observed differences in NB. Instead, surface tension of F-rich rhyolite must be lower by approximately 4% than that of F-poor rhyolite. This difference in surface tension is significant and, for example, exceeds that found between hydrous basaltic andesite and hydrous rhyolite. These results suggest that is likely that surface tension for F-rich magmas, such as topaz rhyolite, is significantly lower than for F-poor magmas.

  19. One year of operation of Mammoth Pacific`s MP1-100 turbine with metastable, supersaturated expansions

    Energy Technology Data Exchange (ETDEWEB)

    Mines, G.L. [Idaho National Engineering Lab., Idaho Falls, ID (United States)

    1997-12-31

    The Idaho National Engineering and Environmental Laboratory`s Heat Cycle Research project is developing a technology base that will increase the use of moderate-temperature hydrothermal resources to generate electrical power. One of the concepts under investigation is the use of a metastable, supersaturated turbine expansion. This expansion process supports a supersaturated vapor. If brought to equilibrium conditions, liquid condensate would be present in the expanding vapor. Analytical studies show that a plant designed to operate with this expansion will have an improvement in the brine effectiveness of up to 8% provided there is no adverse impact on turbine performance. Determining the impact of this expansion on turbine performance is focus of the project investigations being reported.

  20. FACTORS INFLUENCING PHOTOREACTIONS OF DISSOLVED ORGANIC MATTER IN A COASTAL RIVER OF THE SOUTHEASTERN UNITED STATES

    Science.gov (United States)

    Photoreactions of dissolved organic matter can affect the oxidizing capacity, nutrient dynamics, trace gas exchange, and color of surface waters. This study focuses on factors that affect the photoreactions of the colored dissolved organic matter (CDOM) in the Satilla River, a co...

  1. Collisional stabilization efficiencies that control condensation flux rates in supersaturated vapors of n-alcohols and water

    International Nuclear Information System (INIS)

    Bauer, S.H.; Wilcox, C.F. Jr.

    1994-01-01

    Using J(S;T) values, magnitudes for a temperature-dependent stabilization factor, the size-dependent activation energy for evaporation from stabilized clusters, and the size-dependent heats of evaporation are derived. This kinetic derivation is carried out using data from supersaturated water and six n-alcohols obtained with the double-piston expansion technique. 30 refs., 5 figs., 1 tab

  2. METHOD OF DISSOLVING URANIUM METAL

    Science.gov (United States)

    Slotin, L.A.

    1958-02-18

    This patent relates to an economicai means of dissolving metallic uranium. It has been found that the addition of a small amount of perchloric acid to the concentrated nitric acid in which the uranium is being dissolved greatly shortens the time necessary for dissolution of the metal. Thus the use of about 1 or 2 percent of perchioric acid based on the weight of the nitric acid used, reduces the time of dissolution of uranium by a factor of about 100.

  3. Evaluation of surface tension and Tolman length as a function of droplet radius from experimental nucleation rate and supersaturation ratio: metal vapor homogeneous nucleation.

    Science.gov (United States)

    Onischuk, A A; Purtov, P A; Baklanov, A M; Karasev, V V; Vosel, S V

    2006-01-07

    Zinc and silver vapor homogeneous nucleations are studied experimentally at the temperature from 600 to 725 and 870 K, respectively, in a laminar flow diffusion chamber with Ar as a carrier gas at atmospheric pressure. The size, shape, and concentration of aerosol particles outcoming the diffusion chamber are analyzed by a transmission electron microscope and an automatic diffusion battery. The wall deposit is studied by a scanning electron microscope (SEM). Using SEM data the nucleation rate for both Zn and Ag is estimated as 10(10) cm(-3) s(-1). The dependence of critical supersaturation on temperature for Zn and Ag measured in this paper as well as Li, Na, Cs, Ag, Mg, and Hg measured elsewhere is analyzed. To this aim the classical nucleation theory is extended by the dependence of surface tension on the nucleus radius. The preexponent in the formula for the vapor nucleation rate is derived using the formula for the work of formation of noncritical embryo [obtained by Nishioka and Kusaka [J. Chem. Phys. 96, 5370 (1992)] and later by Debenedetti and Reiss [J. Chem. Phys. 108, 5498 (1998)

  4. Constraining the supersaturation density equation of state from core-collapse supernova simulations? Excluded volume extension of the baryons

    International Nuclear Information System (INIS)

    Fischer, Tobias

    2016-01-01

    In this article the role of the supersaturation density equation of state (EOS) is explored in simulations of failed core-collapse supernova explosions. Therefore the nuclear EOS is extended via a one-parameter excluded-volume description for baryons, taking into account their finite and increasing volume with increasing density in excess of saturation density. Parameters are selected such that the resulting supernova EOS represent extreme cases, with high pressure variations at supersaturation density which feature extreme stiff and soft EOS variants of the reference case, i.e. without excluded-volume corrections. Unlike in the interior of neutron stars with central densities in excess of several times saturation density, central densities of core-collapse supernovae reach only slightly above saturation density. Hence, the impact of the supersaturation density EOS on the supernova dynamics as well as the neutrino signal is found to be negligible. It is mainly determined from the low- and intermediate-density domain, which is left unmodified within this generalized excluded volume approach. (orig.)

  5. Effects of initial supersaturation on spontaneous precipitation of calcium carbonate in the presence of charged poly-L-amino acids.

    Science.gov (United States)

    Njegić-Dzakula, Branka; Falini, Giuseppe; Brecević, Ljerka; Skoko, Zeljko; Kralj, Damir

    2010-03-15

    Spontaneous precipitation of calcium carbonate was investigated in two precipitation systems: (1) with initial supersaturation lower than that corresponding to the solubility of amorphous calcium carbonate (ACC), at which vaterite precipitated, and (2) with initial supersaturation higher than that of ACC solubility, at which a mixture of calcite and vaterite was formed. After the addition of an acidic polypeptide, poly-L-glutamic acid (pGlu) or poly-L-aspartic acid (pAsp), into (1) a significant inhibition of nucleation, expressed as an increase in induction time, and growth of vaterite, perceived as a dead zone, was observed. Extent of inhibition decreased in the order: Inh(pAps)>Inh(pGlu)>Inh(pLys). The addition of a polypeptide into (2) caused the inhibition of precipitation and changed the morphology and polymorphic composition of the precipitate; only vaterite appeared at approximately c(pAsp)=3 ppm, c(pGlu)=6 ppm, or c(pLys)=7 ppm. This finding is explained as a consequence of kinetic constraints through the inhibition of calcite nucleation and stronger binding of acidic polypeptide by the calcite surfaces than by the vaterite surfaces. Laboratory precipitation studies using conditions that resemble those in living organism should be run at an initial supersaturation corresponding to the solubility of ACC as a limiting condition. 2009 Elsevier Inc. All rights reserved.

  6. Influence of infection with Renibacterium salmoninarum on susceptibility of juvenile spring chinook salmon to gas bubble trauma

    Science.gov (United States)

    Weiland, L.K.; Mesa, M.G.; Maule, A.G.

    1999-01-01

    During experiments in our laboratory to assess the progression and severity of gas bubble trauma (GBT) in juvenile spring chinook salmon Oncorhynchus tshawytscha, we had the opportunity to assess the influence of Renibacterium salmoninarum (Rs), the causative agent of bacterial kidney disease, on the susceptibility of salmon to GBT. We exposed fish with an established infection of Rs to 120% total dissolved gas (TDG) for 96 h and monitored severity of GBT signs in the fins and gills, Rs infection level in kidneys by using an enzyme-linked immunosorbent assay (ELISA), and mortality. Mortality occurred rapidly after exposure to 120% TDG, with a LT20 (time necessary to kill 20% of the population) of about 37 h, which is at a minimum about 16% earlier than other bioassays we have conducted using fish that had no apparent signs of disease. Fish that died early (from 31 to 36 h and from 49 to 52 h) had significantly higher infection levels (mean ?? SE ELISA absorbance = 1.532 ?? 0.108) than fish that survived for 96h (mean ?? SE ELISA absorbance = 0.828 ?? 0.137). Fish that died early also had a significantly greater number of gill filaments occluded with bubbles than those that survived 96 h. Conversely, fish that survived for 96 h had a significantly higher median fin severity ranking than those that died early. Our results indicate that fish with moderate to high levels of Rs infection are more vulnerable to the effects of dissolved gas supersaturation (DGS) and die sooner than fish with lower levels of Rs infection. However, there is a substantial amount of individual variation in susceptibility to the apparent cumulative effects of DGS and Rs infection. Collectively, our findings have important implications to programs designed to monitor the prevalence and severity of GBT in juvenile salmonids in areas like the Columbia River basin and perhaps elsewhere.

  7. Impact of solute concentration on the electrocatalytic conversion of dissolved gases in buffered solutions

    KAUST Repository

    Shinagawa, Tatsuya; Takanabe, Kazuhiro

    2015-01-01

    . These alterations of the electrolyte properties associated with the solute concentration are universally applicable to other aqueous gas-related electrochemical reactions because the currents are purely determined by mass transfer of the dissolved gases. © 2015

  8. Sulfurization of Dissolved Organic Matter Increases Hg-Sulfide-Dissolved Organic Matter Bioavailability to a Hg-Methylating Bacterium.

    Science.gov (United States)

    Graham, Andrew M; Cameron-Burr, Keaton T; Hajic, Hayley A; Lee, Connie; Msekela, Deborah; Gilmour, Cynthia C

    2017-08-15

    Reactions of dissolved organic matter (DOM) with aqueous sulfide (termed sulfurization) in anoxic environments can substantially increase DOM's reduced sulfur functional group content. Sulfurization may affect DOM-trace metal interactions, including complexation and metal-containing particle precipitation, aggregation, and dissolution. Using a diverse suite of DOM samples, we found that susceptibility to additional sulfur incorporation via reaction with aqueous sulfide increased with increasing DOM aromatic-, carbonyl-, and carboxyl-C content. The role of DOM sulfurization in enhancing Hg bioavailability for microbial methylation was evaluated under conditions typical of Hg methylation environments (μM sulfide concentrations and low Hg-to-DOM molar ratios). Under the conditions of predicted metacinnabar supersaturation, microbial Hg methylation increased with increasing DOM sulfurization, likely reflecting either effective inhibition of metacinnabar growth and aggregation or the formation of Hg(II)-DOM thiol complexes with high bioavailability. Remarkably, Hg methylation efficiencies with the most sulfurized DOM samples were similar (>85% of total Hg methylated) to that observed in the presence of l-cysteine, a ligand facilitating rapid Hg(II) biouptake and methylation. This suggests that complexes of Hg(II) with DOM thiols have similar bioavailability to Hg(II) complexes with low-molecular-weight thiols. Overall, our results are a demonstration of the importance of DOM sulfurization to trace metal and metalloid (especially mercury) fate in the environment. DOM sulfurization likely represents another link between anthropogenic sulfate enrichment and MeHg production in the environment.

  9. Effect of layer thickness on device response of silicon heavily supersaturated with sulfur

    Energy Technology Data Exchange (ETDEWEB)

    Hutchinson, David [Department of Physics, Applied Physics, and Astronomy, Rensselaer Polytechnic Institute, Troy NY 12180 (United States); Department of Physics and Nuclear Engineering, United States Military Academy, West Point NY 10996 (United States); Mathews, Jay [US Army ARDEC – Benét Laboratories, Watervliet NY 12189 (United States); Department of Physics, University of Dayton, Dayton, OH 45469 (United States); Sullivan, Joseph T.; Buonassisi, Tonio [School of Engineering, Massachusetts Institute of Technology, Cambridge MA 02139 (United States); Akey, Austin [School of Engineering, Massachusetts Institute of Technology, Cambridge MA 02139 (United States); Harvard John A. Paulson School of Engineering and Applied Sciences, Cambridge MA 02138 (United States); Aziz, Michael J. [Harvard John A. Paulson School of Engineering and Applied Sciences, Cambridge MA 02138 (United States); Persans, Peter [Department of Physics, Applied Physics, and Astronomy, Rensselaer Polytechnic Institute, Troy NY 12180 (United States); Warrender, Jeffrey M., E-mail: jwarrend@post.harvard.edu [US Army ARDEC – Benét Laboratories, Watervliet NY 12189 (United States)

    2016-05-15

    We report on a simple experiment in which the thickness of a hyperdoped silicon layer, supersaturated with sulfur by ion implantation followed by pulsed laser melting and rapid solidification, is systematically varied at constant average sulfur concentration, by varying the implantation energy, dose, and laser fluence. Contacts are deposited and the external quantum efficiency (EQE) is measured for visible wavelengths. We posit that the sulfur layer primarily absorbs light but contributes negligible photocurrent, and we seek to support this by analyzing the EQE data for the different layer thicknesses in two interlocking ways. In the first, we use the measured concentration depth profiles to obtain the approximate layer thicknesses, and, for each wavelength, fit the EQE vs. layer thickness curve to obtain the absorption coefficient of hyperdoped silicon for that wavelength. Comparison to literature values for the hyperdoped silicon absorption coefficients [S.H. Pan et al. Applied Physics Letters 98, 121913 (2011)] shows good agreement. Next, we essentially run this process in reverse; we fit with Beer’s law the curves of EQE vs. hyperdoped silicon absorption coefficient for those wavelengths that are primarily absorbed in the hyperdoped silicon layer, and find that the layer thicknesses obtained from the fit are in good agreement with the original values obtained from the depth profiles. We conclude that the data support our interpretation of the hyperdoped silicon layer as providing negligible photocurrent at high S concentrations. This work validates the absorption data of Pan et al. [Applied Physics Letters 98, 121913 (2011)], and is consistent with reports of short mobility-lifetime products in hyperdoped layers. It suggests that for optoelectronic devices containing hyperdoped layers, the most important contribution to the above band gap photoresponse may be due to photons absorbed below the hyperdoped layer.

  10. Effect of layer thickness on device response of silicon heavily supersaturated with sulfur

    Directory of Open Access Journals (Sweden)

    David Hutchinson

    2016-05-01

    Full Text Available We report on a simple experiment in which the thickness of a hyperdoped silicon layer, supersaturated with sulfur by ion implantation followed by pulsed laser melting and rapid solidification, is systematically varied at constant average sulfur concentration, by varying the implantation energy, dose, and laser fluence. Contacts are deposited and the external quantum efficiency (EQE is measured for visible wavelengths. We posit that the sulfur layer primarily absorbs light but contributes negligible photocurrent, and we seek to support this by analyzing the EQE data for the different layer thicknesses in two interlocking ways. In the first, we use the measured concentration depth profiles to obtain the approximate layer thicknesses, and, for each wavelength, fit the EQE vs. layer thickness curve to obtain the absorption coefficient of hyperdoped silicon for that wavelength. Comparison to literature values for the hyperdoped silicon absorption coefficients [S.H. Pan et al. Applied Physics Letters 98, 121913 (2011] shows good agreement. Next, we essentially run this process in reverse; we fit with Beer’s law the curves of EQE vs. hyperdoped silicon absorption coefficient for those wavelengths that are primarily absorbed in the hyperdoped silicon layer, and find that the layer thicknesses obtained from the fit are in good agreement with the original values obtained from the depth profiles. We conclude that the data support our interpretation of the hyperdoped silicon layer as providing negligible photocurrent at high S concentrations. This work validates the absorption data of Pan et al. [Applied Physics Letters 98, 121913 (2011], and is consistent with reports of short mobility-lifetime products in hyperdoped layers. It suggests that for optoelectronic devices containing hyperdoped layers, the most important contribution to the above band gap photoresponse may be due to photons absorbed below the hyperdoped layer.

  11. Reducing emissions from uranium dissolving

    International Nuclear Information System (INIS)

    Griffith, W.L.; Compere, A.L.; Huxtable, W.P.; Googin, J.M.

    1992-10-01

    This study was designed to assess the feasibility of decreasing NO x emissions from the current uranium alloy scrap tray dissolving facility. In the current process, uranium scrap is dissolved in boiling nitric acid in shallow stainless-steel trays. As scrap dissolves, more metal and more nitric acid are added to the tray by operating personnel. Safe geometry is assured by keeping liquid level at or below 5 cm, the depth of a safe infinite slab. The accountability batch control system provides additional protection against criticality. Both uranium and uranium alloys are dissolved. Nitric acid is recovered from the vapors for reuse. Metal nitrates are sent to uranium recovery. Brown NO x fumes evolved during dissolving have occasionally resulted in a visible plume from the trays. The fuming is most noticeable during startup and after addition of fresh acid to a tray. Present environmental regulations are expected to require control of brown NO x emissions. A detailed review of the literature, indicated the feasibility of slightly altering process chemistry to favor the production of NO 2 which can be scrubbed and recycled as nitric acid. Methods for controlling the process to manage offgas product distribution and to minimize chemical reaction hazards were also considered

  12. ICPP custom dissolver explosion recovery

    International Nuclear Information System (INIS)

    Demmer, R.; Hawk, R.

    1992-01-01

    This paper discusses the recovery from the February 9, 1991, small scale explosion in a custom processing dissolver at the Idaho Chemical Processing Plant (ICPP) a Department of Energy facility at the Idaho National Engineering Laboratory. The custom processing facility is a limited production area designed to recover unirradiated uranium fuel. A small amount of the nuclear material received and stored at the ICPP is unique and incompatible with the major head end dissolution processes. Custom processing is a small scale dissolution facility for processing these materials in an economical fashion in the CPP-627 hot chemistry laboratory. Two glass dissolvers were contained in a large walk in hood area. Utilities for dissolution and connections to the major ICPP uranium separation facility were provided. The fuel processing operations during this campaign involved dissolving uranium metal, uranium oxides, and uranium/fissium alloy in nitric acid

  13. ICPP custom dissolver explosion recovery

    International Nuclear Information System (INIS)

    Demmer, R.; Hawk, R.

    1992-01-01

    This report discusses the recovery from the February 9, 1991 small scale explosion in a custom processing dissolver at the Idaho Chemical Processing Plant. Custom processing is a small scale dissolution facility which processes nuclear material in an economical fashion. The material dissolved in this facility was uranium metal, uranium oxides, and uranium/fissium alloy in nitric acid. The paper explained the release of fission material, and the decontamination and recovery of the fuel material. The safety and protection procedures were also discussed. Also described was the chemical analysis which was used to speculate the most probable cause of the explosion. (MB)

  14. Method for dissolving ceramic beryllia

    International Nuclear Information System (INIS)

    Sands, A.E.

    1975-01-01

    A process is described for dissolving a nuclear fuel composition consisting of a sintered mass containing beryllia, a nuclear fuel selected from uranium and plutonium and a stabilizing agent, sintered at a temperature of at least 1500 0 C to a density of about 2.7 gs/cc. The process comprises contacting said sintered mass with a stoichiometric excess of lithium oxide dissolved or dispersed in a carrier selected from lithium hydroxide, sodium hydroxide or sodium nitrate at a temperature in the range 750--850 0 C to convert the beryllia to lithium beryllate and thereafter recovering the nuclear fuel content of said mass. (U.S.)

  15. Bubbles as a means for the deaeration of water bodies

    NARCIS (Netherlands)

    Zhang, Yuhang; Zhou, Gedi; Prosperetti, Andrea

    2017-01-01

    Occasional dissolved-air supersaturation - such as may occur, for instance, downstream of dams - is harmful to fish because it causes gas bubble disease. A counterintuitive but effective means of reducing dissolved air content is the injection of bubbles in the supersaturated water. The bubbles

  16. CADDIS Volume 2. Sources, Stressors and Responses: Dissolved Oxygen

    Science.gov (United States)

    Introduction to the dissolved oxygen module, when to list dissolved oxygen as a candidate cause, ways to measure dissolved oxygen, simple and detailed conceptual model diagrams for dissolved oxygen, references for the dissolved oxygen module.

  17. Rationalising polymer selection for supersaturated film forming systems produced by an aerosol spray for the transdermal delivery of methylphenidate.

    Science.gov (United States)

    Edwards, A; Qi, S; Liu, F; Brown, M B; McAuley, W J

    2017-05-01

    Film forming systems offer a number of advantages for topical and transdermal drug delivery, in particular enabling production of a supersaturated state which can greatly improve drug absorption and bioavailability. However the suitability of individual film forming polymers to stabilise the supersaturated state and optimise delivery of drugs is not well understood. This study reports the use of differential scanning calorimetry (DSC) to measure the solubility of methylphenidate both as the free base and as the hydrochloride salt in two polymethacrylate copolymers, Eudragit RS (EuRS) and Eudragit E (EuE) and relates this to the ability of films formed using these polymers to deliver methylphenidate across a model membrane. EuRS provided greater methylphenidate delivery when the drug was formulated as the free base in comparison EuE because the lower solubility of the drug in EuRS provided a higher degree of drug saturation in the polymeric film. In contrast EuE provided greater delivery of methylphenidate hydrochloride as EuRS could not prevent its crystallisation from a supersaturated state. Methylphenidate flux across the membrane could be directly related to degree of saturation of the drug in the film formulation as estimated by the drug solubility in the individual polymers demonstrating the importance of drug solubility in the polymer included in film forming systems for topical/transdermal drug delivery. In addition DSC has been demonstrated to be a useful tool for determining the solubility of drugs in polymers used in film forming systems and the approaches outlined here are likely to be useful for predicting the suitability of polymers for particular drugs in film forming transdermal drug delivery systems. Copyright © 2017. Published by Elsevier B.V.

  18. Enhanced oral bioavailability of valsartan using a polymer-based supersaturable self-microemulsifying drug delivery system

    Directory of Open Access Journals (Sweden)

    Yeom DW

    2017-05-01

    Full Text Available Dong Woo Yeom,1,* Bo Ram Chae,2,* Ho Yong Son,1 Jin Han Kim,1 Jun Soo Chae,1 Seh Hyon Song,2 Dongho Oh,2 Young Wook Choi1 1College of Pharmacy, Chung-Ang University, Seoul, 2Daewon Pharm. Co., Ltd, Seoul, Republic of Korea *These authors contributed equally to this work Abstract: A novel, supersaturable self-microemulsifying drug delivery system (S-SMEDDS was successfully formulated to enhance the dissolution and oral absorption of valsartan (VST, a poorly water-soluble drug, while reducing the total quantity for administration. Poloxamer 407 is a selectable, supersaturating agent for VST-containing SMEDDS composed of 10% Capmul® MCM, 45% Tween® 20, and 45% Transcutol® P. The amounts of SMEDDS and Poloxamer 407 were chosen as formulation variables for a 3-level factorial design. Further optimization was established by weighting different levels of importance on response variables for dissolution and total quantity, resulting in an optimal S-SMEDDS in large quantity (S-SMEDDS_LQ; 352 mg in total and S-SMEDDS in reduced quantity (S-SMEDDS_RQ; 144.6 mg in total. Good agreement was observed between predicted and experimental values for response variables. Consequently, compared with VST powder or suspension and SMEDDS, both S-SMEDDS_LQ and S-SMEDDS_RQ showed excellent in vitro dissolution and in vivo oral bioavailability in rats. The magnitude of dissolution and absorption-enhancing capacities using quantity-based comparisons was in the order S-SMEDDS_RQ > S-SMEDDS_LQ > SMEDDS > VST powder or suspension. Thus, we concluded that, in terms of developing an effective SMEDDS preparation with minimal total quantity, S-SMEDDS_RQ is a promising candidate. Keywords: valsartan, SMEDDS, supersaturation, factorial design, optimization, bio­availability 

  19. Net Community and Gross Photosynthetic Production Rates in the Eastern Tropical South Pacific, as Determined from O2/AR Ratios and Triple Oxygen Isotopic Composition of Dissolved O2

    Science.gov (United States)

    Prokopenko, M. G.; Yeung, L. Y.; Berelson, W.; Fleming, J.; Rollins, N.; Young, E. D.; Haskell, W. Z.; Hammond, D. E.; Capone, D. G.

    2010-12-01

    This study assesses the rates of ocean carbon production and its fate with respect to recycling or export in the Eastern Tropical South Pacific (ETSP). ETSP has been previously identified as a region where N2 fixation and denitrification may be spatially coupled; this is also a region of localized CO2 outgassing. Using an Equilibrated Inlet Mass Spectrometer (EIMS) system, we obtained continuous measurements of the biological O2 supersaturation in the mixed layer along the ship track encompassing a region bounded by 10-20° S and 80-100° W in January - March, 2010. Vertical profiles were also taken at selected stations and analyzed for dissolved O2/Ar ratios on EIMS and triple oxygen isotope composition (17O excess) on a multi-collector IRMS (Isotope Ratio Mass Spectrometer) at UCLA. Gas exchange rates were estimated using two approaches: the Rn-222 deficit method and the wind parameterization method, which utilized wind speeds extracted from ASCAT satellite database. Oxygen Net Community Production (O-NCP) rates calculated based on biological O2 supersaturation ranged from slightly negative to ~ 0.3 - 15 mmol/m2d, with higher rates along the northern part of the transect. Oxygen Gross Community Production (O-GPP) rates calculated from 17O excess were between 50 ± 20 and 200 ± 40 mmol/m2d, with higher rates observed along the northern cruise transect as well. Notably, the NCP/GPP ratios along the northern transect were higher by the factor of 2 to 3 than their southern counterparts. The O2/Ar-based NCP rates were comparable to POC flux measured with floating traps deployed at the southern stations, but exceeded by a factor of 5-10 the trap POC fluxes obtained at the northern stations. A one-dimensional box model has been constructed to quantify the magnitude of oxygen primary production below the mixed layer. The results of this work will be integrated with measurements of 15-N2 uptake that are in progress, to constrain the potential contribution of N2 fixation

  20. Effect of surfactants, gastric emptying, and dosage form on supersaturation of dipyridamole in an in vitro model simulating the stomach and duodenum.

    Science.gov (United States)

    Mitra, A; Fadda, H M

    2014-08-04

    The purpose of this study was to investigate the influence of gastric emptying patterns, surfactants, and dosage form on the supersaturation of a poorly soluble weakly basic drug, dipyridamole, using an in vitro model mimicking the dynamic environment of the upper gastrointestinal tract, and, furthermore, to evaluate the usefulness of this model in establishing correlations to in vivo bioavailability for drugs with solubility/dissolution limited absorption. A simulated stomach duodenum model comprising four compartments was used to assess supersaturation and precipitation kinetics as a function of time. It integrates physiologically relevant fluid volumes, fluid transfer rates, and pH changes of the upper GI tract. Monoexponential gastric emptying patterns simulating the fasted state were compared to linear gastric emptying patterns simulating the fed state. The effect of different surfactants commonly used in oral preparations, specifically, sodium lauryl sulfate (SLS), poloxamer-188, and polysorbate-80, on dipyridamole supersaturation was investigated while maintaining surface tension of the simulated gastric fluids at physiological levels and without obtaining artificial micellar solubilization of the drug. The supersaturation behavior of different dose strengths of dipyridamole was explored. Significant levels of dipyridamole supersaturation were observed in the duodenal compartment under all the different in vivo relevant conditions explored. Dipyridamole supersaturation ratios of up to 11-fold have been observed, and supersaturation has been maintained for up to 120 min. Lower duodenal concentrations of dipyridamole were observed under linear gastric emptying patterns compared to mononexponential gastric emptying. The mean duodenal area under concentration-time curves (AUC60min) for the dipyridamole concentration profile in the duodenal compartment is significantly different for all the surfactants explored (P stomach duodenum model can provide a reliable and

  1. Effect of dissolved air content on single bubble sonoluminescence

    OpenAIRE

    Arakeri, Vijay H

    1993-01-01

    It has been recently demonstrated that a single gas bubble in a liquid medium can be driven hard enough by an acoustic pressure field to make it emit light which is visible to the naked eye in a dark room. This phenomenon termed as single bubble sonoluminescence has shown some extraordinary physical properties. In the present investigation the author has shown that dissolved air content has a significant influence on this phenomenon.

  2. Nanosuspensions of 10-hydroxycamptothecin that can maintain high and extended supersaturation to enhance oral absorption: preparation, characterization and in vitro/in vivo evaluation

    Energy Technology Data Exchange (ETDEWEB)

    Pu, Xiaohui; Sun, Jin, E-mail: sunjin66@21cn.com [Shenyang Pharmaceutical University, Department of Biopharmaceutics, School of Pharmacy (China); Han, Jihong [Keele University, School of Pharmacy and Institute for Science and Technology in Medicine (United Kingdom); Lian, He; Zhang, Peng [Shenyang Pharmaceutical University, Department of Biopharmaceutics, School of Pharmacy (China); Yan, Zhongtian [Nantion Institutes for Food and Drug Control (China); He, Zhonggui, E-mail: hezhgui_student@yahoo.com.cn [Shenyang Pharmaceutical University, Department of Biopharmaceutics, School of Pharmacy (China)

    2013-11-15

    The purpose of the study was to prepare and characterize nanosuspensions that can maintain high and extended supersaturation to improve the dissolution and absorption of poorly soluble 10-hydroxycamptothecin (10-HCPT). 10-HCPT oral nanosuspensions (HCPT-Nanosuspensions) were produced on a laboratory-scale by microprecipitation- high pressure homogenization method. The particle morphology and the physical state were studied using transmission electron microscopy, X-ray powder diffraction (XRPD), and differential scanning calorimetry (DSC). Supersaturated dissolution tests were carried out with the paddle method. Caco-2 cell experiments were performed to imitate the oral absorption. The in vivo pharmacokinetics studies were undertaken in rats following oral administration. The 10-HCPT nanoparticles were 135 nm in dimension before lyophilization and were claviform or lump in shape. XRPD and DSC both confirmed that a portion of 10-HCPT was present in a crystalline state in nanosuspension. Supersaturated dissolution tests showed HCPT-Nanosuspensions could maintain high supersaturated level for an extended period time. The cell experiment on HCPT-Nanosuspensions showed a significantly higher uptake and greater membrane permeability compared with the other formulations. The pharmacokinetic test exhibited HCPT-Nanosuspensions had a similar pharmacokinetic performance with 10-HCPT solution. In conclusion, highly and extendedly supersaturated HCPT-Nanosuspensions have been prepared which could result in high peak concentration (C{sub max}) and great exposure (AUC) after oral administration.

  3. Highly CO2-supersaturated melts in the Pannonian lithospheric mantle - A transient carbon reservoir?

    Science.gov (United States)

    Créon, Laura; Rouchon, Virgile; Youssef, Souhail; Rosenberg, Elisabeth; Delpech, Guillaume; Szabó, Csaba; Remusat, Laurent; Mostefaoui, Smail; Asimow, Paul D.; Antoshechkina, Paula M.; Ghiorso, Mark S.; Boller, Elodie; Guyot, François

    2017-08-01

    determined by Raman spectroscopy and microthermometry (0.1-1.1 GPa). The CO2/silicate melt mass ratios in the metasomatic agent that percolated through the lithospheric mantle below the Pannonian Basin are estimated to be between 9.0 and 25.4 wt.%, values consistent with metasomatism either by (1) silicate melts already supersaturated in CO2 before reaching lithospheric depths or (2) carbonatite melts that interacted with mantle peridotite to generate carbonated silicic melts. Taking the geodynamical context of the Pannonian Basin and our calculations of the CO2/silicate melt mass ratios in the metasomatic agent into account, we suggest that slab-derived melts initially containing up to 25 wt.% of CO2 migrated into the lithospheric mantle and exsolved CO2-rich fluid that became trapped in secondary fluid inclusions upon fracturing of the peridotite mineral matrix. We propose a first-order estimate of 2000 ppm as the minimal bulk CO2 concentration in the lithospheric mantle below the Pannonian Basin. This transient carbon reservoir is believed to be degassed through the Pannonian Basin due to volcanism and tectonic events, mostly focused along the lithospheric-scale regional Mid-Hungarian shear Zone.

  4. Disintegration mediated controlled release supersaturating solid dispersion formulation of an insoluble drug: design, development, optimization, and in vitro evaluation.

    Science.gov (United States)

    Verma, Sanjay; Rudraraju, Varma S

    2015-02-01

    The objective of this study was to develop a solid dispersion based controlled release system for drug substances that are poorly soluble in water. A wax-based disintegration mediated controlled release system was designed based on the fact that an amorphous drug can crystallize out from hydrophilic matrices. For this study, cilostazol (CIL) was selected as the model drug, as it exhibits poor aqueous solubility. An amorphous solid dispersion was prepared to assist the drug to attain a supersaturated state. Povidone was used as carrier for solid dispersion (spray drying technique), hydrogenated vegetable oil (HVO) as wax matrix former, and sodium carboxymethyl cellulose (NaCMC) as a disintegrant. The extreme vertices mixture design (EVMD) was applied to optimize the designed and developed composition. The optimized formulation provided a dissolution pattern which was equivalent to the predicted curve, ascertaining that the optimal formulation could be accomplished with EVMD. The release profile of CIL was described by the Higuchi's model better than zero-order, first-order, and Hixson-Crowell's model, which indicated that the supersaturation state of CIL dominated to allow drug release by diffusion rather than disintegration regulated release as is generally observed by Hixson-Crowell's model. The optimized composition was evaluated for disintegration, dissolution, XRD, and stability studies. It was found that the amorphous state as well as the dissolution profile of CIL was maintained under the accelerated conditions of 40°C/75% RH for 6 months.

  5. Hygroscopic growth and critical supersaturations for mixed aerosol particles of inorganic and organic compounds of atmospheric relevance

    Directory of Open Access Journals (Sweden)

    B. Svenningsson

    2006-01-01

    Full Text Available The organic fraction of atmospheric aerosols contains a multitude of compounds and usually only a small fraction can be identified and quantified. However, a limited number of representative organic compounds can be used to describe the water-soluble organic fraction. In this work, initiated within the EU 5FP project SMOCC, four mixtures containing various amounts of inorganic salts (ammonium sulfate, ammonium nitrate, and sodium chloride and three model organic compounds (levoglucosan, succinic acid and fulvic acid were studied. The interaction between water vapor and aerosol particles was studied at different relative humidities: at subsaturation using a hygroscopic tandem differential mobility analyzer (H-TDMA and at supersaturation using a cloud condensation nuclei spectrometer (CCN spectrometer. Surface tensions as a function of carbon concentrations were measured using a bubble tensiometer. Parameterizations of water activity as a function of molality, based on hygroscopic growth, are given for the pure organic compounds and for the mixtures, indicating van't Hoff factors around 1 for the organics. The Zdanovskii-Stokes-Robinson (ZSR mixing rule was tested on the hygroscopic growth of the mixtures and it was found to adequately explain the hygroscopic growth for 3 out of 4 mixtures, when the limited solubility of succinic acid is taken into account. One mixture containing sodium chloride was studied and showed a pronounced deviation from the ZSR mixing rule. Critical supersaturations calculated using the parameterizations of water activity and the measured surface tensions were compared with those determined experimentally.

  6. Gas bubble trauma monitoring and research of juvenile salmonids. 1995 Annual report

    International Nuclear Information System (INIS)

    Maule, A.G.; Mesa, M.G.; Hans, K.M.

    1997-07-01

    This report describes laboratory and field monitoring studies of gas bubble trauma (GBT) in migrating juvenile salmonids in the Snake and Columbia rivers. The first chapter describes laboratory studies of the progression of GBT signs leading to mortality and the use of the signs for GBT assessment. The progression and severity of GBT signs in juvenile salmonids exposed to different levels of total dissolved gas (TDG) and temperatures was assessed and quantified. Next, the prevalence, severity, and individual variation of GBT signs was evaluated to attempt to relate them to mortality. Finally, methods for gill examination in fish exposed to high TDG were developed and evaluated. Primary findings were: (1) no single sign of GBT was clearly correlated with mortality, but many GBT signs progressively worsened; (2) both prevalence and severity of GBT signs in several tissues is necessary; (3) bubbles in the lateral line were the earliest sign of GBT, showed progressive worsening, and had low individual variation but may develop poorly during chronic exposures; (4) fin bubbles had high prevalence, progressively worsened, and may be a persistent sign of GBT; and (5) gill bubbles appear to be the proximate cause of death but may only be relevant at high TDG levels and are difficult to examine. Chapter Two describes monitoring results of juvenile salmonids for signs of GBT. Emigrating fish were collected and examined for bubbles in fins and lateral lines. Preliminary findings were: (1) few fish had signs of GBT, but prevalence and severity appeared to increase as fish migrated downstream; (2) there was no apparent correlation between GBT signs in the fins, lateral line, or gills; (3) prevalence and severity of GBT was suggestive of long-term, non-lethal exposure to relatively low level gas supersaturated water; and (4) it appeared that GBT was not a threat to migrating juvenile salmonids. 24 refs., 26 figs., 3 tabs

  7. A new device for continuous monitoring the CO2 dissolved in water

    Science.gov (United States)

    de Gregorio, S.; Camarda, M.; Cappuzzo, S.; Giudice, G.; Gurrieri, S.; Longo, M.

    2009-04-01

    The measurements of dissolved CO2 in water are common elements of industrial processes and scientific research. In order to perform gas dissolved measurements is required to separate the dissolved gaseous phase from water. We developed a new device able to separate the gases phase directly in situ and well suitable for continuous measuring the CO2 dissolved in water. The device is made by a probe of a polytetrafluorethylene (PTFE) tube connected to an I.R. spectrophotometer (I.R.) and a pump. The PTFE is a polymeric semi-permeable membrane and allows the permeation of gas in the system. Hence, this part of the device is dipped in water in order to equilibrate the probe headspace with the dissolved gases. The partial pressure of the gas i in the headspace at equilibrium (Pi) follows the Henry's law: Pi=Hi•Ci, where Hi is the Henry's constant and Ci is the dissolved concentration of gas i. After the equilibrium is achieved, the partial pressure of CO2 inside the tube is equal to the partial pressure of dissolved CO2. The concentration of CO2 is measured by the I.R. connected to the tube. The gas is moved from the tube headspace to the I.R. by using the pump. In order to test the device and assess the best operating condition, several experimental were performed in laboratory. All the test were executed in a special apparatus where was feasible to create controlled atmospheres. Afterward the device has been placed in a draining tunnel sited in the Mt. Etna Volcano edifice (Italy). The monitored groundwater intercepts the Pernicana Fault, along which degassing phenomena are often observed. The values recorded by the station result in agreement with monthly directly measurements of dissolved CO2 partial pressure.

  8. Why the free floating macrophyte Stratiotes aloides mainly grows in highly CO2-supersaturated waters

    DEFF Research Database (Denmark)

    Nielsen, Lasse Tor; Borum, Jens

    2008-01-01

    consistently supersaturated CO2 conditions to grow and complete its life cycle. Submerged rosettes formed from over-wintering turions had typical traits of submerged plants with high specific leaf area and low chlorophyll a concentrations. Emergent leaf parts of mature, floating specimens had typical...... estimated at CO2 concentrations corresponding to air equilibrium were not sufficiently high to support any noticeable growth except for rosettes, in which bicarbonate utilization combined with high CO2 affinity resulted in photosynthetic rates corresponding to almost 34% of maximum rates at high free CO2....... We conclude that S. aloides requires consistently high CO2-supersaturation to support high growth and to complete its life cycle, and we infer that this requirement explains why S. aloides mainly grows in ponds, ditches and reed zones that are characterized by strong CO2-supersaturation....

  9. Gas Enrichment at Liquid-Wall Interfaces

    NARCIS (Netherlands)

    Dammer, S.M.; Lohse, Detlef

    2006-01-01

    Molecular dynamics simulations of Lennard-Jones systems are performed to study the effects of dissolved gas on liquid-wall and liquid-gas interfaces. Gas enrichment at walls, which for hydrophobic walls can exceed more than 2 orders of magnitude when compared to the gas density in the bulk liquid,

  10. A case study on the formation and evolution of ice supersaturation in the vicinity of a warm conveyor belt's outflow region

    Directory of Open Access Journals (Sweden)

    P. Spichtinger

    2005-01-01

    Full Text Available A case study is presented on the formation and evolution of an ice-supersaturated region (ISSR that was detected by a radiosonde in NE Germany at 06:00 UTC 29 November 2000. The ISSR was situated in the vicinity of the outflow region of a warm conveyor belt associated with an intense event of cyclogenesis in the eastern North Atlantic. Using ECMWF analyses and trajectory calculations it is determined when the air parcels became supersaturated and later subsaturated again. In the case considered, the state of air parcel supersaturation can last for longer than 24h. The ISSR was unusually thick: while the mean vertical extension of ISSRs in NE Germany is about 500m, the one investigated here reached 3km. The ice-supersaturated region investigated was bordered both vertically and horizontally by strongly subsaturated air. Near the path of the radiosonde the ISSR was probably cloud free, as inferred from METEOSAT infrared images. However, at other locations within the ISSR it is probable that there were cirrus clouds. Relative humidity measurements obtained by the Lindenberg radiosonde are used to correct the negative bias of the ECMWF humidity and to construct two-dimensional maps of ice supersaturation over Europe during the considered period. A systematic backward trajectory analysis for the ISSRs on these maps shows that the ISSR air masses themselves experienced only a moderate upward motion during the previous days, whereas parts of the ISSRs were located just above strongly ascending air masses from the boundary layer. This indicates qualitatively that warm conveyor belts associated with mid-latitude cyclogenesis are disturbances that can induce the formation of ISSRs in the upper troposphere. The ISSR maps also lead us to a new perception of ISSRs as large dynamic regions of supersaturated air where cirrus clouds can be embedded at some locations while there is clear air at others.

  11. Water uptake by biomass burning aerosol at sub- and supersaturated conditions: closure studies and implications for the role of organics

    Directory of Open Access Journals (Sweden)

    U. Dusek

    2011-09-01

    Full Text Available We investigate the CCN activity of freshly emitted biomass burning particles and their hygroscopic growth at a relative humidity (RH of 85%. The particles were produced in the Mainz combustion laboratory by controlled burning of various wood types. The water uptake at sub- and supersaturations is parameterized by the hygroscopicity parameter, κ (c.f. Petters and Kreidenweis, 2007. For the wood burns, κ is low, generally around 0.06. The main emphasis of this study is a comparison of κ derived from measurements at sub- and supersaturated conditions (κG and κCCN, in order to see whether the water uptake at 85% RH can predict the CCN properties of the biomass burning particles. Differences in κGand κCCN can arise through solution non-idealities, the presence of slightly soluble or surface active compounds, or non-spherical particle shape. We find that κG and κCCN agree within experimental uncertainties (of around 30% for particle sizes of 100 and 150 nm; only for 50 nm particles is κCCN larger than κG by a factor of 2. The magnitude of this difference and its dependence on particle size is consistent with the presence of surface active organic compounds. These compounds mainly facilitate the CCN activation of small particles, which form the most concentrated solution droplets at the point of activation. The 50 nm particles, however, are only activated at supersaturations higher than 1% and are therefore of minor importance as CCN in ambient clouds. By comparison with the actual chemical composition of the biomass burning particles, we estimate that the hygroscopicity of the water-soluble organic carbon (WSOC fraction can be represented by a κWSOC value of approximately 0.2. The effective hygroscopicity of a typical wood burning particle can therefore be represented by a linear mixture of an inorganic component with κ ≅ 0.6, a WSOC

  12. US crude oil, natural gas, and natural gas liquids reserves

    International Nuclear Information System (INIS)

    1992-01-01

    This report presents estimates of proved reserves of crude oil, natural gas, and natural gas liquids as of December 31, 1991, as well as production volumes for the United States, and selected States and State subdivisions for the year 1991. Estimates are presented for the following four categories of natural gas: total gas (wet after lease separation), its two major components (nonassociated and associated-dissolved gas), and total dry gas (wet gas adjusted for the removal of liquids at natural gas processing plants). In addition, two components of natural gas liquids, lease condensate and natural gas plant liquids, have their reserves and production data presented. Also included is information on indicated additional crude oil reserves and crude oil, natural gas, and lease condensate reserves in nonproducing reservoirs. A discussion of notable oil and gas exploration and development activities during 1991 is also presented

  13. Visualization of gas dissolution following upward gas migration in porous media: Technique and implications for stray gas

    Science.gov (United States)

    Van De Ven, C. J. C.; Mumford, Kevin G.

    2018-05-01

    The study of gas-water mass transfer in porous media is important in many applications, including unconventional resource extraction, carbon storage, deep geological waste storage, and remediation of contaminated groundwater, all of which rely on an understanding of the fate and transport of free and dissolved gas. The novel visual technique developed in this study provided both quantitative and qualitative observations of gas-water mass transfer. Findings included interaction between free gas architecture and dissolved plume migration, plume geometry and longevity. The technique was applied to the injection of CO2 in source patterns expected for stray gas originating from oil and gas operations to measure dissolved phase concentrations of CO2 at high spatial and temporal resolutions. The data set is the first of its kind to provide high resolution quantification of gas-water dissolution, and will facilitate an improved understanding of the fundamental processes of gas movement and fate in these complex systems.

  14. Regional-scale controls on dissolved nitrous oxide in the Upper Mississippi River

    Science.gov (United States)

    Turner, P.A.; Griffis, T.J.; Baker, J.M.; Lee, X.; Crawford, John T.; Loken, Luke C.; Venterea, R.T.

    2016-01-01

    The U.S. Corn Belt is one of the most intensive agricultural regions of the world and is drained by the Upper Mississippi River (UMR), which forms one of the largest drainage basins in the U.S. While the effects of agricultural nitrate (NO3-) on water quality in the UMR have been well documented, its impact on the production of nitrous oxide (N2O) has not been reported. Using a novel equilibration technique, we present the largest data set of freshwater dissolved N2O concentrations (0.7 to 6 times saturation) and examine the controls on its variability over a 350 km reach of the UMR. Driven by a supersaturated water column, the UMR was an important atmospheric N2O source (+68 mg N2ONm-2 yr-1) that varies nonlinearly with the NO3-concentration. Our analyses indicated that a projected doubling of the NO3-concentration by 2050 would cause dissolved N2O concentrations and emissions to increase by about 40%.

  15. PROCESS OF DISSOLVING ZIRCONIUM ALLOYS

    Science.gov (United States)

    Shor, R.S.; Vogler, S.

    1958-01-21

    A process is described for dissolving binary zirconium-uranium alloys where the uranium content is about 2%. In prior dissolution procedures for these alloys, an oxidizing agent was added to prevent the precipitation of uranium tetrafluoride. In the present method complete dissolution is accomplished without the use of the oxidizing agent by using only the stoichiometric amount or slight excess of HF required by the zirconium. The concentration of the acid may range from 2M to 10M and the dissolution is advatageously carried out at a temperature of 80 deg C.

  16. Homogeneous nucleation in supersaturated vapors of methane, ethane, and carbon dioxide predicted by brute force molecular dynamics.

    Science.gov (United States)

    Horsch, Martin; Vrabec, Jadran; Bernreuther, Martin; Grottel, Sebastian; Reina, Guido; Wix, Andrea; Schaber, Karlheinz; Hasse, Hans

    2008-04-28

    Molecular dynamics (MD) simulation is applied to the condensation process of supersaturated vapors of methane, ethane, and carbon dioxide. Simulations of systems with up to a 10(6) particles were conducted with a massively parallel MD program. This leads to reliable statistics and makes nucleation rates down to the order of 10(30) m(-3) s(-1) accessible to the direct simulation approach. Simulation results are compared to the classical nucleation theory (CNT) as well as the modification of Laaksonen, Ford, and Kulmala (LFK) which introduces a size dependence of the specific surface energy. CNT describes the nucleation of ethane and carbon dioxide excellently over the entire studied temperature range, whereas LFK provides a better approach to methane at low temperatures.

  17. Observation of enhanced infrared absorption in silicon supersaturated with gold by pulsed laser melting of nanometer-thick gold films

    Science.gov (United States)

    Chow, Philippe K.; Yang, Wenjie; Hudspeth, Quentin; Lim, Shao Qi; Williams, Jim S.; Warrender, Jeffrey M.

    2018-04-01

    We demonstrate that pulsed laser melting (PLM) of thin 1, 5, and 10 nm-thick vapor-deposited gold layers on silicon enhances its room-temperature sub-band gap infrared absorption, as in the case of ion-implanted and PLM-treated silicon. The former approach offers reduced fabrication complexity and avoids implantation-induced lattice damage compared to ion implantation and pulsed laser melting, while exhibiting comparable optical absorptance. We additionally observed strong broadband absorptance enhancement in PLM samples made using 5- and 10-nm-thick gold layers. Raman spectroscopy and Rutherford backscattering analysis indicate that such an enhancement could be explained by absorption by a metastable, disordered and gold-rich surface layer. The sheet resistance and the diode electrical characteristics further elucidate the role of gold-supersaturation in silicon, revealing the promise for future silicon-based infrared device applications.

  18. A simple headspace equilibration method for measuring dissolved methane

    Science.gov (United States)

    Magen, C; Lapham, L.L.; Pohlman, John W.; Marshall, Kristin N.; Bosman, S.; Casso, Michael; Chanton, J.P.

    2014-01-01

    Dissolved methane concentrations in the ocean are close to equilibrium with the atmosphere. Because methane is only sparingly soluble in seawater, measuring it without contamination is challenging for samples collected and processed in the presence of air. Several methods for analyzing dissolved methane are described in the literature, yet none has conducted a thorough assessment of the method yield, contamination issues during collection, transport and storage, and the effect of temperature changes and preservative. Previous extraction methods transfer methane from water to gas by either a "sparge and trap" or a "headspace equilibration" technique. The gas is then analyzed for methane by gas chromatography. Here, we revisit the headspace equilibration technique and describe a simple, inexpensive, and reliable method to measure methane in fresh and seawater, regardless of concentration. Within the range of concentrations typically found in surface seawaters (2-1000 nmol L-1), the yield of the method nears 100% of what is expected from solubility calculation following the addition of known amount of methane. In addition to being sensitive (detection limit of 0.1 ppmv, or 0.74 nmol L-1), this method requires less than 10 min per sample, and does not use highly toxic chemicals. It can be conducted with minimum materials and does not require the use of a gas chromatograph at the collection site. It can therefore be used in various remote working environments and conditions.

  19. Cost-effective alternative to nano-encapsulation: Amorphous curcumin-chitosan nanoparticle complex exhibiting high payload and supersaturation generation.

    Science.gov (United States)

    Nguyen, Minh Hiep; Yu, Hong; Kiew, Tie Yi; Hadinoto, Kunn

    2015-10-01

    While the wide-ranging therapeutic activities of curcumin have been well established, its successful delivery to realize its true therapeutic potentials faces a major challenge due to its low oral bioavailability. Even though nano-encapsulation has been widely demonstrated to be effective in enhancing the bioavailability of curcumin, it is not without drawbacks (i.e. low payload and costly preparation). Herein we present a cost-effective bioavailability enhancement strategy of curcumin in the form of amorphous curcumin-chitosan nanoparticle complex (or curcumin nanoplex in short) exhibiting a high payload (>80%). The curcumin nanoplex was prepared by a simple yet highly efficient drug-polysaccharide complexation method that required only mixing of the curcumin and chitosan solutions under ambient condition. The effects of (1) pH and (2) charge ratio of chitosan to curcumin on the (i) physical characteristics of the nanoplex (i.e. size, colloidal stability and payload), (ii) complexation efficiency, and (iii) production yield were investigated from which the optimal preparation condition was determined. The nanoplex formation was found to favor low acidic pH and charge ratio below unity. At the optimal condition (i.e. pH 4.4. and charge ratio=0.8), stable curcumin nanoplex (≈260nm) was prepared at >90% complexation efficiency and ≈50% production yield. The amorphous state stability, colloidal stability, and in vitro non-cytotoxicity of the nanoplex were successfully established. The curcumin nanoplex produced prolonged supersaturation (3h) in the presence of hydroxypropyl methylcellulose (HPMC) at five times of the saturation solubility of curcumin. In addition, curcumin released from the nanoplex exhibited improved chemical stability owed to the presence of chitosan. Both results (i.e. high supersaturation and improved chemical stability) bode well for the ability of the curcumin nanoplex to enhance the bioavailability of curcumin clinically. Copyright © 2015

  20. Effects of tablet formulation and subsequent film coating on the supersaturated dissolution behavior of amorphous solid dispersions.

    Science.gov (United States)

    Sakai, Toshiro; Hirai, Daiki; Kimura, Shin-Ichiro; Iwao, Yasunori; Itai, Shigeru

    2018-04-05

    The effects of tablet preparation and subsequent film coating with amorphous solid dispersion (ASD) particles that were composed of a drug with poor water solubility and hydrophilic polymers were investigated. ASD particles were prepared with a drug and vinylpyrrolidone-vinyl acetate copolymer (PVPVA) or polyvinylpyrrolidone (PVP) at a weight ratio of 1:1 or 1:2 using a melt extrusion technique. Tablets were prepared by conventional direct compression followed by pan coating. A mathematical model based on the Noyes-Whitney equation assuming that stable crystals precipitated at the changeable surface area of the solid-liquid interface used to estimate drug dissolution kinetics in a non-sink dissolution condition. All the ASD particles showed a maximum dissolution concentration approximately ten times higher than that of the crystalline drug. The ASD particles with PVPVA showed higher precipitation rate with lower polymer ratio, while PVP did not precipitate within 960 min regardless of the polymer ratio, suggesting the ASD particles of 1:1 drug:PVPVA (ASD-1) were the most unstable among the ASD particles considered. The dissolution of a core tablet with ASD-1 showed less supersaturation and a much higher precipitation rate than those of ASD-1 particles. However, a film-coated tablet or core tablet with a trace amount of hydroxypropylmethylcellulose (HPMC) showed a similar dissolution profile to that of the ASD-1 particles, indicating HPMC had a remarkable precipitation inhibition effect. Overall, these results suggest that tablet preparation with ASD may adversely affect the maintenance of supersaturation; however, this effect can be mitigated by adding an appropriate precipitation inhibitor to the formulation. Copyright © 2018 Elsevier B.V. All rights reserved.

  1. Role of Molecular Interactions for Synergistic Precipitation Inhibition of Poorly Soluble Drug in Supersaturated Drug-Polymer-Polymer Ternary Solution.

    Science.gov (United States)

    Prasad, Dev; Chauhan, Harsh; Atef, Eman

    2016-03-07

    We are reporting a synergistic effect of combined Eudragit E100 and PVP K90 in precipitation inhibition of indomethacin (IND) in solutions at low polymer concentration, a phenomenon that has significant implications on the usefulness of developing novel ternary solid dispersion of poorly soluble drugs. The IND supersaturation was created by cosolvent technique, and the precipitation studies were performed in the absence and the presence of individual and combined PVP K90 and Eudragit E100. The studies were also done with PEG 8000 as a noninteracting control polymer. A continuous UV recording of the IND absorption was used to observe changes in the drug concentration over time. The polymorphic form and morphology of precipitated IND were characterized by Raman spectroscopy and scanning electron microscopy. The change in the chemical shift in solution (1)H NMR was used as novel approach to probe IND-polymer interactions. Molecular modeling was used for calculating binding energy between IND-polymer as another indication of IND-polymer interaction. Spontaneous IND precipitation was observed in the absence of polymers. Eudragit E100 showed significant inhibitory effect on nuclei formation due to stronger interaction as reflected in higher binding energy and greater change in chemical shift by NMR. PVP K90 led to significant crystal growth inhibition due to adsorption on growing IND crystals as confirmed by modified crystal habit of precipitate in the presence of PVP K90. Combination of polymers resulted in a synergistic precipitation inhibition and extended supersaturation. The NMR confirmed interaction between IND-Eudragit E100 and IND-PVP K90 in solution. The combination of polymers showed similar peak shift albeit using lower polymer concentration indicating stronger interactions. The results established the significant synergistic precipitation inhibition effect upon combining Eudragit E100 and PVP K90 due to drug-polymer interaction.

  2. Dissolved oxygen mapping: A powerful tool for site assessments and ground water monitoring

    International Nuclear Information System (INIS)

    Newman, W.A.; Kimball, G.

    1992-01-01

    Dissolved oxygen concentration profiles often provide an excellent indication of the natural biological activity of microorganisms in ground water. The analysis of dissolved oxygen in ground water also provides a rapid, inexpensive method for determining the areal extent of contaminant plumes containing aerobically degraded compounds such as petroleum hydrocarbons. Indigenous hydrocarbon degrading organisms are present at most petroleum product spills giving this technique an almost universal application for dissolved hydrocarbons in ground water. Data from several sites will be presented to demonstrate the relationship between oxygen and dissolved contaminant concentrations. The inverse relationship between oxygen concentrations and dissolved contaminants can be used in many ways. During the initial site assessment, rapid on-site testing of ground water can provide real time data to direct drilling by identification of potentially contaminated locations. Several analytical techniques are available that allow field analysis to be performed in less than five minutes. Dissolved oxygen testing also provides an inexpensive way to monitor hydrocarbon migration without expensive gas chromatography. Often a plume of oxygen depleted ground water extends farther downgradient than the dissolved hydrocarbon plume. The depletion of oxygen in a well can provide an early warning system that detects upgradient contamination before the well is impacted by detectable levels of contaminants. Another application is the measurement of the natural degradation potential for aerobic remediation. If an aerobic in-situ remediation is used, dissolved oxygen monitoring provides an inexpensive method to monitor the progress of the remediation

  3. High-Frequency Observations of Temperature and Dissolved Oxygen Reveal Under-Ice Convection in a Large Lake

    Science.gov (United States)

    Yang, Bernard; Young, Joelle; Brown, Laura; Wells, Mathew

    2017-12-01

    Detailed observations of thermal structure over an entire winter in a large lake reveal the presence of large (10-20 m) overturns under the ice, driven by diurnal solar heating. Convection can occur in the early winter, but the most vigorous convection occurred near the end of winter. Both periods are when our lake ice model suggest thinner ice that would have been transparent. This under-ice convection led to a deepening of the mixed layer over time, consistent with previous short-term studies. During periods of vigorous convection under the ice at the end of winter, the dissolved oxygen had become supersaturated from the surface to 23 m below the surface, suggesting abundant algal growth. Analysis of our high-frequency observations over the entire winter of 2015 using the Thorpe-scale method quantified the scale of mixing. Furthermore, it revealed that changes in oxygen concentrations are closely related to the intensity of mixing.

  4. The impact of supersaturation level for oral absorption of BCS class IIb drugs, dipyridamole and ketoconazole, using in vivo predictive dissolution system: Gastrointestinal Simulator (GIS).

    Science.gov (United States)

    Tsume, Yasuhiro; Matsui, Kazuki; Searls, Amanda L; Takeuchi, Susumu; Amidon, Gregory E; Sun, Duxin; Amidon, Gordon L

    2017-05-01

    The development of formulations and the assessment of oral drug absorption for Biopharmaceutical Classification System (BCS) class IIb drugs is often a difficult issue due to the potential for supersaturation and precipitation in the gastrointestinal (GI) tract. The physiological environment in the GI tract largely influences in vivo drug dissolution rates of those drugs. Thus, those physiological factors should be incorporated into the in vitro system to better assess in vivo performance of BCS class IIb drugs. In order to predict oral bioperformance, an in vitro dissolution system with multiple compartments incorporating physiologically relevant factors would be expected to more accurately predict in vivo phenomena than a one-compartment dissolution system like USP Apparatus 2 because, for example, the pH change occurring in the human GI tract can be better replicated in a multi-compartmental platform. The Gastrointestinal Simulator (GIS) consists of three compartments, the gastric, duodenal and jejunal chambers, and is a practical in vitro dissolution apparatus to predict in vivo dissolution for oral dosage forms. This system can demonstrate supersaturation and precipitation and, therefore, has the potential to predict in vivo bioperformance of oral dosage forms where this phenomenon may occur. In this report, in vitro studies were performed with dipyridamole and ketoconazole to evaluate the precipitation rates and the relationship between the supersaturation levels and oral absorption of BCS class II weak base drugs. To evaluate the impact of observed supersaturation levels on oral absorption, a study utilizing the GIS in combination with mouse intestinal infusion was conducted. Supersaturation levels observed in the GIS enhanced dipyridamole and ketoconazole absorption in mouse, and a good correlation between their supersaturation levels and their concentration in plasma was observed. The GIS, therefore, appears to represent in vivo dissolution phenomena and

  5. Statistical analysis of dimer formation in supersaturated metal vapor based on molecular dynamics simulation

    Science.gov (United States)

    Korenchenko, Anna E.; Vorontsov, Alexander G.; Gelchinski, Boris R.; Sannikov, Grigorii P.

    2018-04-01

    We discuss the problem of dimer formation during the homogeneous nucleation of atomic metal vapor in an inert gas environment. We simulated nucleation with molecular dynamics and carried out the statistical analysis of double- and triple-atomic collisions as the two ways of long-lived diatomic complex formation. Close pair of atoms with lifetime greater than the mean time interval between atom-atom collisions is called a long-lived diatomic complex. We found that double- and triple-atomic collisions gave approximately the same probabilities of long-lived diatomic complex formation, but internal energy of the resulted state was essentially lower in the second case. Some diatomic complexes formed in three-particle collisions are stable enough to be a critical nucleus.

  6. BLM Colorado Oil and Gas Communitization Agreements (Dissolve)

    Data.gov (United States)

    Department of the Interior — Shapefile Format –This data is one feature type that is a part of a set consisting of six shapefiles pertaining to energy development and production in Colorado. The...

  7. BLM Colorado Oil and Gas Storage Agreements (Dissolve)

    Data.gov (United States)

    Department of the Interior — Shapefile Format –This data is one feature type that is a part of a set consisting of six shapefiles pertaining to energy development and production in Colorado. The...

  8. Dissolved Gas Analysis of Insulating Transformer Oil Using Optical Fiber

    OpenAIRE

    Overby, Alan Bland

    2014-01-01

    The power industry relies on high voltage transformers as the backbone of power distribution networks. High voltage transformers are designed to handle immense electrical loads in hostile environments. Long term placement is desired, however by being under constant heavy load transformers face mechanical, thermal, and electrical stresses which lead to failures of the protection systems in place. The service life of a transformer is often limited by the life time of its insulati...

  9. BLM Colorado Oil and Gas Storage Agreements (Dissolve)

    Data.gov (United States)

    Department of the Interior — KMZ File Format –This data is one feature type that is a part of a set consisting of six shapefiles pertaining to energy development and production in Colorado. The...

  10. BLM Colorado Oil and Gas Communitization Agreements (Dissolve)

    Data.gov (United States)

    Department of the Interior — KMZ File Format –This data is one feature type that is a part of a set consisting of six shapefiles pertaining to energy development and production in Colorado. The...

  11. The origin and isotopic composition of dissolved sulfide in groundwater from carbonate aquifers in Florida and Texas

    International Nuclear Information System (INIS)

    Rye, R.O.; Back, W.; Hanshaw, B.B.; Rightmire, C.T.; Pearson, F.J. Jr.

    1981-01-01

    The delta 34 S values of dissolved sulfide and the sulfur isotope fractionations between dissolved sulfide and sulfate species in Floridan ground water generally correlate with dissolved sulfate concentrations which are related to flow patterns and residence time within the aquifer. The dissolved sulfide derives from the slow in situ biogenic reduction of sulfate dissolved from sedimentary gypsum in the aquifer. In areas where the water is oldest, the dissolved sulfide has apparently attained isotopic equilibrium with the dissolved sulfate at the temperature of the system. This approach to equilibrium reflects an extremely slow reduction rate of the dissolved sulfate by bacteria; this slow rate probably results from very low concentrations of organic matter in the aquifer. In the reducing part of the Edwards aquifer, Texas, there is a general down-gradient increase in both dissolved sulfide and sulfate concentrations, but neither the delta 34 S values of sulfide nor the sulfide-sulfate isotope fractionation correlates with the ground-water flow pattern. The dissolved sulfide species appear to be derived primarily from biogenic reduction of sulfate ions whose source is gypsum dissolution although upgradient diffusion of H 2 S gas from deeper oil field brines may be important in places. (author)

  12. The Carrier Gas Pressure Effect in a Laminar Flow Diffusion Chamber, Homogeneous Nucleation of n-Butanol in Helium

    Czech Academy of Sciences Publication Activity Database

    Hyvärinen, A-P.; Brus, David; Ždímal, Vladimír; Smolík, Jiří; Kulmala, M.; Viisanen, V.; Lihavainen, H.

    2006-01-01

    Roč. 124, č. 22 (2006), Art. No. 224304 ISSN 0021-9606 R&D Projects: GA AV ČR(CZ) IAA2076203 Institutional research plan: CEZ:AV0Z40720504 Keywords : supersaturated vapor * cloud chamber * background gas es Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.166, year: 2006

  13. The effect of dissolved oxygen on water radiolysis behaviour

    International Nuclear Information System (INIS)

    Yakabuskie, P.A.; Joseph, J.M.; Wren, J.C.; Stuart, C.R.

    2012-09-01

    A quantitative understanding of the chemical or redox environments generated in water by ionizing radiation is important for material selection, development of maintenance programs, and safety assessments for water-cooled nuclear power reactors. The highly reactive radicals (·OH, ·H, ·e aq - , ·HO 2 , and ·O 2 - ) and molecular species (H 2 and H 2 O 2 ) generated by water radiolysis can compete in reactions with other dissolved compounds and impose changes to the system chemistry by altering the steady-state concentrations of water radiolysis products, which could impact the degradation of materials in contact with the aqueous phase. Understanding in detail how a given chemical additive changes the long-term radiolysis kinetics can help us to determine what chemistry control steps may be required to return the system to an optimal redox condition, and in turn, enhance the lifetime of reactor components. This study outlines the effect of dissolved oxygen gas, which could be introduced due to air ingress, on long-term water radiolysis behaviour. The effects of solution pH and initial dissolved O 2 concentration on the radiolytic production of molecular H 2 and H 2 O 2 have been investigated by performing experiments with three different O 2 concentrations at pH 6.0 and 10.6 under steady-state radiolysis conditions. The aqueous and gas phase analyses were performed using UV-Vis spectrophotometry and gas-chromatography equipped with electron capture and thermal conductivity detectors. The experimental results were compared with kinetic model calculations of steady-state radiolysis and were found to be in good agreement. The concentrations of water radiolysis products, H 2 O 2 and H 2 , were found to increase in the presence of dissolved oxygen, but the degree of increase was shown to depend on the solution pH. Furthermore, the steady-state concentration of H 2 did not increase as greatly as that of H 2 O 2 at either pH studied. The kinetic analyses have shown

  14. Enhancement of the droplet nucleation in a dense supersaturated Lennard-Jones vapor

    Energy Technology Data Exchange (ETDEWEB)

    Zhukhovitskii, D. I., E-mail: dmr@ihed.ras.ru [Joint Institute of High Temperatures, Russian Academy of Sciences, Izhorskaya 13, Bd. 2, 125412 Moscow (Russian Federation)

    2016-05-14

    The vapor–liquid nucleation in a dense Lennard-Jones system is studied analytically and numerically. A solution of the nucleation kinetic equations, which includes the elementary processes of condensation/evaporation involving the lightest clusters, is obtained, and the nucleation rate is calculated. Based on the equation of state for the cluster vapor, the pre-exponential factor is obtained. The latter diverges as a spinodal is reached, which results in the nucleation enhancement. The work of critical cluster formation is calculated using the previously developed two-parameter model (TPM) of small clusters. A simple expression for the nucleation rate is deduced and it is shown that the work of cluster formation is reduced for a dense vapor. This results in the nucleation enhancement as well. To verify the TPM, a simulation is performed that mimics a steady-state nucleation experiments in the thermal diffusion cloud chamber. The nucleating vapor with and without a carrier gas is simulated using two different thermostats for the monomers and clusters. The TPM proves to match the simulation results of this work and of other studies.

  15. Theoretical and experimental investigation of drug-polymer interaction and miscibility and its impact on drug supersaturation in aqueous medium.

    Science.gov (United States)

    Baghel, Shrawan; Cathcart, Helen; O'Reilly, Niall J

    2016-10-01

    Amorphous solid dispersions (ASDs) have the potential to offer higher apparent solubility and bioavailability of BCS class II drugs. Knowledge of the solid state drug-polymer solubility/miscibility and their mutual interaction are fundamental requirements for the effective design and development of such systems. To this end, we have carried out a comprehensive investigation of various ASD systems of dipyridamole and cinnarizine in polyvinylpyrrolidone (PVP) and polyacrylic acid (PAA) at different drug loadings. Theoretical and experimental examinations (by implementing binary and ternary Flory-Huggins (F-H) theory) related to drug-polymer interaction/miscibility including solubility parameter approach, melting point depression method, phase diagram, drug-polymer interaction in the presence of moisture and the effect of drug loading on interaction parameter were performed. The information obtained from this study was used to predict the stability of ASDs at different drug loadings and under different thermal and moisture conditions. Thermal and moisture sorption analysis not only provided the composition-dependent interaction parameter but also predicted the composition dependent miscibility. DPM-PVP, DPM-PAA and CNZ-PAA systems have shown molecular level mixing over the complete range of drug loading. For CNZ-PVP, the presence of a single Tg at lower drug loadings (10, 20 and 35%w/w) indicates the formation of solid solution. However, drug recrystallization was observed for samples with higher drug weight fractions (50 and 65%w/w). Finally, the role of polymer in maintaining drug supersaturation has also been explored. It has been found that drug-polymer combinations capable of hydrogen-bonding in the solution state (DPM-PVP, DPM-PAA and CNZ-PAA) are more effective in preventing drug crystallization compared to the drug-polymer systems without such interaction (CNZ-PVP). The DPM-PAA system outperformed all other ASDs in various stability conditions (dry-state, in

  16. Assessing dissolved methane patterns in central New York groundwater

    Directory of Open Access Journals (Sweden)

    Lauren E. McPhillips

    2014-07-01

    New hydrological insights for this region: There was no significant difference between methane concentrations in valleys versus upslope locations, in water wells less than or greater than 1 km from a conventional gas well, and across different geohydrologic units. Methane concentrations were significantly higher in groundwater dominated by sodium chloride or sodium bicarbonate compared with groundwater dominated by calcium bicarbonate, indicating bedrock interactions and lengthy residence times as controls. A multivariate regression model of dissolved methane using only three variables (sodium, hardness, and barium explained 77% of methane variability, further emphasizing the dominance of geochemistry and hydrogeology as controls on baseline methane patterns.

  17. Cycling downwards - dissolved organic matter in soils

    NARCIS (Netherlands)

    Kaiser, K.; Kalbitz, K.

    2012-01-01

    Dissolved organic matter has been recognized as mobile, thus crucial to translocation of metals, pollutants but also of nutrients in soil. We present a conceptual model of the vertical movement of dissolved organic matter with soil water, which deviates from the view of a chromatographic stripping

  18. Measurement and interpretation of low levels of dissolved oxygen in ground water

    Science.gov (United States)

    White, A.F.; Peterson, M.L.; Solbau, R.D.

    1990-01-01

    A Rhodazine-D colorimetric technique was adapted to measure low-level dissolved oxygen concentrations in ground water. Prepared samples containing between 0 and 8.0 ??moles L-1 dissolved oxygen in equilibrium with known gas mixtures produced linear spectrophotometric absorbance with a lower detection limit of 0.2 ??moles L-1. Excellent reproducibility was found for solutions ranging in composition from deionized water to sea water with chemical interferences detected only for easily reduced metal species such as ferric ion, cupric ion, and hexavalent chromium. Such effects were correctable based on parallel reaction stoichiometries relative to oxygen. The technique, coupled with a downhole wire line tool, permitted low-level monitoring of dissolved oxygen in wells at the selenium-contaminated Kesterson Reservoir in California. Results indicated a close association between low but measurable dissolved oxygen concentrations and mobility of oxidized forms of selenium. -from Authors

  19. Dissolved air flotation and me.

    Science.gov (United States)

    Edzwald, James K

    2010-04-01

    This paper is mainly a critical review of the literature and an assessment of what we know about dissolved air flotation (DAF). A few remarks are made at the outset about the author's personal journey in DAF research, his start and its progression. DAF has been used for several decades in drinking water treatment as an alternative clarification method to sedimentation. DAF is particularly effective in treating reservoir water supplies; those supplies containing algae, natural color or natural organic matter; and those with low mineral turbidity. It is more efficient than sedimentation in removing turbidity and particles for these type supplies. Furthermore, it is more efficient in removing Giardia cysts and Cryptosporidium oocysts. In the last 20 years, fundamental models were developed that provide a basis for understanding the process, optimizing it, and integrating it into water treatment plants. The theories were tested through laboratory and pilot-plant studies. Consequently, there have been trends in which DAF pretreatment has been optimized resulting in better coagulation and a decrease in the size of flocculation tanks. In addition, the hydraulic loading rates have increased reducing the size of DAF processes. While DAF has been used mainly in conventional type water plants, there is now interest in the technology as a pretreatment step in ultrafiltration membrane plants and in desalination reverse osmosis plants. Copyright (c) 2009 Elsevier Ltd. All rights reserved.

  20. Solid formulation of a supersaturable self-microemulsifying drug delivery system for valsartan with improved dissolution and bioavailability.

    Science.gov (United States)

    Yeom, Dong Woo; Chae, Bo Ram; Kim, Jin Han; Chae, Jun Soo; Shin, Dong Jun; Kim, Chang Hyun; Kim, Sung Rae; Choi, Ji Ho; Song, Seh Hyon; Oh, Dongho; Sohn, Se Il; Choi, Young Wook

    2017-11-07

    In order to improve the dissolution and oral bioavailability of valsartan (VST), and reduce the required volume for treatment, we previously formulated a supersaturable self-microemulsifying drug delivery system (SuSMEDDS) composed of VST (80 mg), Capmul ® MCM (13.2 mg), Tween ® 80 (59.2 mg), Transcutol ® P (59.2 mg), and Poloxamer 407 (13.2 mg). In the present study, by using Florite ® PS-10 (119.1 mg) and Vivapur ® 105 (105.6 mg) as solid carriers, VST-loaded solidified SuSMEDDS (S-SuSMEDDS) granules were successfully developed, which possessed good flow properties and rapid drug dissolution. By introducing croscarmellose sodium (31 mg) as a superdisintegrant, S-SuSMEDDS tablets were also successfully formulated, which showed fast disintegration and high dissolution efficiency. Preparation of granules and tablets was successfully optimized using D-optimal mixture design and 3-level factorial design, respectively, resulting in percentage prediction errors of <10%. In pharmacokinetic studies in rats, the relative bioavailability of the optimized granules was 107% and 222% of values obtained for SuSMEDDS and Diovan ® powder, respectively. Therefore, we conclude that novel S-SuSMEDDS formulations offer great potential for developing solid dosage forms of a liquefied formulation such as SuSMEDDS, while improving oral absorption of drugs with poor water solubility.

  1. Local solid phase growth of few-layer graphene on silicon carbide from nickel silicide supersaturated with carbon

    International Nuclear Information System (INIS)

    Escobedo-Cousin, Enrique; Vassilevski, Konstantin; Hopf, Toby; Wright, Nick; O'Neill, Anthony; Horsfall, Alton; Goss, Jonathan; Cumpson, Peter

    2013-01-01

    Patterned few-layer graphene (FLG) films were obtained by local solid phase growth from nickel silicide supersaturated with carbon, following a fabrication scheme, which allows the formation of self-aligned ohmic contacts on FLG and is compatible with conventional SiC device processing methods. The process was realised by the deposition and patterning of thin Ni films on semi-insulating 6H-SiC wafers followed by annealing and the selective removal of the resulting nickel silicide by wet chemistry. Raman spectroscopy and X-ray photoelectron spectroscopy (XPS) were used to confirm both the formation and subsequent removal of nickel silicide. The impact of process parameters such as the thickness of the initial Ni layer, annealing temperature, and cooling rates on the FLG films was assessed by Raman spectroscopy, XPS, and atomic force microscopy. The thickness of the final FLG film estimated from the Raman spectra varied from 1 to 4 monolayers for initial Ni layers between 3 and 20 nm thick. Self-aligned contacts were formed on these patterned films by contact photolithography and wet etching of nickel silicide, which enabled the fabrication of test structures to measure the carrier concentration and mobility in the FLG films. A simple model of diffusion-driven solid phase chemical reaction was used to explain formation of the FLG film at the interface between nickel silicide and silicon carbide.

  2. Occurrence and behaviour of dissolved, nano-particulate and micro-particulate iron in waste waters and treatment systems: new insights from electrochemical analysis.

    Science.gov (United States)

    Matthies, R; Aplin, A C; Horrocks, B R; Mudashiru, L K

    2012-04-01

    Cyclic-, Differential Pulse- and Steady-state Microdisc Voltammetry (CV, DPV, SMV) techniques have been used to quantify the occurrence and fate of dissolved Fe(ii)/Fe(iii), nano-particulate and micro-particulate iron over a 12 month period in a series of net-acidic and net-alkaline coal mine drainages and passive treatment systems. Total iron in the mine waters is typically 10-100 mg L(-1), with values up to 2100 mg L(-1). Between 30 and 80% of the total iron occurs as solid phase, of which 20 to 80% is nano-particulate. Nano-particulate iron comprises 20 to 70% of the nominally "dissolved" (i.e. sedimentation are the only processes required to remove solid phase iron, these data have important implications for the generation or consumption of acidity during water treatment. In most waters, the majority of truly dissolved iron occurs as Fe(ii) (average 64 ± 22%). Activities of Fe(ii) do not correlate with pH and geochemical modelling shows that no Fe(ii) mineral is supersaturated. Removal of Fe(ii) must proceed via oxidation and hydrolysis. Except in waters with pH waters are generally supersaturated with respect to ferrihydrite and schwertmannite, and are not at redox equilibrium, indicating the key role of oxidation and hydrolysis kinetics on water treatment. Typically 70-100% of iron is retained in the treatment systems. Oxidation, hydrolysis, precipitation, coagulation and sedimentation occur in all treatment systems and - independent of water chemistry and the type of treatment system - hydroxides and oxyhydroxysulfates are the main iron sinks. The electrochemical data thus reveal the rationale for incomplete iron retention in individual systems and can thus inform future design criteria. The successful application of this low cost and rapid electrochemical method demonstrates its significant potential for real-time, on-site monitoring of iron-enriched waters and may in future substitute traditional analytical methods.

  3. The suitability of using dissolved gases to determine groundwater discharge to high gradient streams

    Science.gov (United States)

    Gleeson, Tom; Manning, Andrew H.; Popp, Andrea; Zane, Mathew; Clark, Jordan F.

    2018-01-01

    Determining groundwater discharge to streams using dissolved gases is known to be useful over a wide range of streamflow rates but the suitability of dissolved gas methods to determine discharge rates in high gradient mountain streams has not been sufficiently tested, even though headwater streams are critical as ecological habitats and water resources. The aim of this study is to test the suitability of using dissolved gases to determine groundwater discharge rates to high gradient streams by field experiments in a well-characterized, high gradient mountain stream and a literature review. At a reach scale (550 m) we combined stream and groundwater radon activity measurements with an in-stream SF6 tracer test. By means of numerical modeling we determined gas exchange velocities and derived very low groundwater discharge rates (∼15% of streamflow). These groundwater discharge rates are below the uncertainty range of physical streamflow measurements and consistent with temperature, specific conductance and streamflow measured at multiple locations along the reach. At a watershed-scale (4 km), we measured CFC-12 and δ18O concentrations and determined gas exchange velocities and groundwater discharge rates with the same numerical model. The groundwater discharge rates along the 4 km stream reach were highly variable, but were consistent with the values derived in the detailed study reach. Additionally, we synthesized literature values of gas exchange velocities for different stream gradients which show an empirical relationship that will be valuable in planning future dissolved gas studies on streams with various gradients. In sum, we show that multiple dissolved gas tracers can be used to determine groundwater discharge to high gradient mountain streams from reach to watershed scales.

  4. The suitability of using dissolved gases to determine groundwater discharge to high gradient streams

    Science.gov (United States)

    Gleeson, Tom; Manning, Andrew H.; Popp, Andrea; Zane, Matthew; Clark, Jordan F.

    2018-02-01

    Determining groundwater discharge to streams using dissolved gases is known to be useful over a wide range of streamflow rates but the suitability of dissolved gas methods to determine discharge rates in high gradient mountain streams has not been sufficiently tested, even though headwater streams are critical as ecological habitats and water resources. The aim of this study is to test the suitability of using dissolved gases to determine groundwater discharge rates to high gradient streams by field experiments in a well-characterized, high gradient mountain stream and a literature review. At a reach scale (550 m) we combined stream and groundwater radon activity measurements with an in-stream SF6 tracer test. By means of numerical modeling we determined gas exchange velocities and derived very low groundwater discharge rates (∼15% of streamflow). These groundwater discharge rates are below the uncertainty range of physical streamflow measurements and consistent with temperature, specific conductance and streamflow measured at multiple locations along the reach. At a watershed-scale (4 km), we measured CFC-12 and δ18O concentrations and determined gas exchange velocities and groundwater discharge rates with the same numerical model. The groundwater discharge rates along the 4 km stream reach were highly variable, but were consistent with the values derived in the detailed study reach. Additionally, we synthesized literature values of gas exchange velocities for different stream gradients which show an empirical relationship that will be valuable in planning future dissolved gas studies on streams with various gradients. In sum, we show that multiple dissolved gas tracers can be used to determine groundwater discharge to high gradient mountain streams from reach to watershed scales.

  5. Preliminary simulation of degassing of natural gases dissolved in groundwater during shaft excavation in Horonobe underground research project

    International Nuclear Information System (INIS)

    Yamamoto, Hajime; Shimo, Michito; Kunimaru, Takanori; Kurikami, Hiroshi

    2007-01-01

    In Neogene-Quaternary sedimentary basins, natural gases such as methane are often dissolved in groundwater significantly. In this paper, two-phase flow simulations incorporating the degassing of methane, and carbon dioxide, were performed for the shaft excavation in Horonobe underground research project. The results drawn from the simulations are summarized as follows. 1) As depth increases, degassing and gas inflow occurs significantly. 2) Degassing increases the compressibility of pore fluids, resulting in slow changes in groundwater pressures. 3) Although the occurrence of gas phase decreases water mobility, the influence of the dissolved gas on the groundwater inflow rate to the shaft was small. (author)

  6. Air supersaturation, release of wooden fibres and upstream migration of Atlantic salmon at Rygene power plant in the River Nidelva, Aust Agder county

    International Nuclear Information System (INIS)

    Thorstad, Eva B.; Kroglund, Frode; Oekland, Finn; Heggberget, Tor G.

    1997-01-01

    Incidents of dead fish have been reported in connection with a power plant at Rygene on the River Nidelva in the Aust-Agder county, Norway. Air supersaturation has been used in a bypass construction of the power plant tunnel system. In addition, wooden fibres from a fabric have been released into the water of the tunnel. Results from relevant studies concerning air saturation, wooden fibres and upstream migration are summarised in this report. 148 refs., 4 figs., 2 tabs

  7. The electro-oxidation of lignin in Sappi Saiccor dissolving pulp mill ...

    African Journals Online (AJOL)

    Log in or Register to get access to full text downloads. ... obtained from Sappi Saiccor (formerly South African Industrial Cellulose Corporation) dissolving pulp mill ... were identified in the electro-oxidised reaction mixtures using gas chromatography-mass spectrometry ... EMAIL FREE FULL TEXT EMAIL FREE FULL TEXT

  8. The free energy of the metastable supersaturated vapor via restricted ensemble simulations. III. An extension to the Corti and Debenedetti subcell constraint algorithm

    International Nuclear Information System (INIS)

    Nie, Chu; Geng, Jun; Marlow, William H.

    2016-01-01

    In order to improve the sampling of restricted microstates in our previous work [C. Nie, J. Geng, and W. H. Marlow, J. Chem. Phys. 127, 154505 (2007); 128, 234310 (2008)] and quantitatively predict thermal properties of supersaturated vapors, an extension is made to the Corti and Debenedetti subcell constraint algorithm [D. S. Corti and P. Debenedetti, Chem. Eng. Sci. 49, 2717 (1994)], which restricts the maximum allowed local density at any point in a simulation box. The maximum allowed local density at a point in a simulation box is defined by the maximum number of particles N m allowed to appear inside a sphere of radius R, with this point as the center of the sphere. Both N m and R serve as extra thermodynamic variables for maintaining a certain degree of spatial homogeneity in a supersaturated system. In a restricted canonical ensemble, at a given temperature and an overall density, series of local minima on the Helmholtz free energy surface F(N m , R) are found subject to different (N m , R) pairs. The true equilibrium metastable state is identified through the analysis of the formation free energies of Stillinger clusters of various sizes obtained from these restricted states. The simulation results of a supersaturated Lennard-Jones vapor at reduced temperature 0.7 including the vapor pressure isotherm, formation free energies of critical nuclei, and chemical potential differences are presented and analyzed. In addition, with slight modifications, the current algorithm can be applied to computing thermal properties of superheated liquids.

  9. Thermodynamics of Highly Supersaturated Aqueous Solutions of Poorly Water-Soluble Drugs-Impact of a Second Drug on the Solution Phase Behavior and Implications for Combination Products.

    Science.gov (United States)

    Trasi, Niraj S; Taylor, Lynne S

    2015-08-01

    There is increasing interest in formulating combination products that contain two or more drugs. Furthermore, it is also common for different drug products to be taken simultaneously. This raises the possibility of interactions between different drugs that may impact formulation performance. For poorly water-soluble compounds, the supersaturation behavior may be a critical factor in determining the extent of oral absorption. The goal of the current study was to evaluate the maximum achievable supersaturation for several poorly water-soluble compounds alone, and in combination. Model compounds included ritonavir, lopinavir, paclitaxel, felodipine, and diclofenac. The "amorphous solubility" for the pure drugs was determined using different techniques and the change in this solubility was then measured in the presence of differing amounts of a second drug. The results showed that "amorphous solubility" of each component in aqueous solution is substantially decreased by the second component, as long as the two drugs are miscible in the amorphous state. A simple thermodynamic model could be used to predict the changes in solubility as a function of composition. This information is of great value when developing co-amorphous or other supersaturating formulations and should contribute to a broader understanding of drug-drug physicochemical interactions in in vitro assays as well as in the gastrointestinal tract. © 2015 Wiley Periodicals, Inc. and the American Pharmacists Association.

  10. Sampling of dissolved gases in deep groundwater pumped to the surface

    International Nuclear Information System (INIS)

    Lahdenperae, J.

    2006-08-01

    The aim of this study was to develop method for sampling dissolved gases in groundwater pumped out from borehole. In this report the developed method called Simple gas collector (YKK) and the first results gained are described. Samples were collected from five sampling sections. First test samplings were made from multipackered deep borehole (OL-KR1/523,2-528,2 m). The rest of samples were sampled during prepumping of PAVE-samplings. All samples were analysed with mass spectrometer. Gas composition results were very reproducible but gas concentration results varied in some sampling sections. Achieved results were compared with gas results of groundwater samples taken with PAVE-equipment. YKK-results were mainly comparable to PAVE-results, although differences were observed in both gas composition and concentration results. When gas concentration is small ( 2 O) gas compositions are very comparable and when concentration is high compositions differs between YKK- and PAVE-results. Gas concentration values were very comparable when the groundwater samples contained gases a lot, but the differences were relatively higher, when the gas amount in the groundwater sample was small. According to the survey you can get comparable information of dissolved gases in groundwater with YKK-method. The limit of using this method is that pumped groundwater must be oversaturated with gases in sampling conditions. (orig.)

  11. Natural gas hydrate formation and inhibition in gas/crude oil/aqueous systems

    DEFF Research Database (Denmark)

    Daraboina, Nagu; Pachitsas, Stylianos; von Solms, Nicolas

    2015-01-01

    Gas hydrate formation in multi phase mixtures containing an aqueous phase (with dissolved salts), reservoir fluid (crude oil) and natural gas phase was investigated by using a standard rocking cell (RC-5) apparatus. The hydrate formation temperature was reduced in the presence of crude oils...... can contribute to the safe operation of sub sea pipelines in the oil and gas industry....

  12. Enhanced Supersaturation and Oral Absorption of Sirolimus Using an Amorphous Solid Dispersion Based on Eudragit® E

    Directory of Open Access Journals (Sweden)

    Youngseok Cho

    2015-05-01

    Full Text Available The present study aimed to investigate the effect of Eudragit® E/HCl (E-SD on the degradation of sirolimus in simulated gastric fluid (pH 1.2 and to develop a new oral formulation of sirolimus using E-SD solid dispersions to enhance oral bioavailability. Sirolimus-loaded solid dispersions were fabricated by a spray drying process. A kinetic solubility test demonstrated that the sirolimus/E-SD/TPGS (1/8/1 solid dispersion had a maximum solubility of 196.7 μg/mL within 0.5 h that gradually decreased to 173.4 μg/mL after 12 h. According to the dissolution study, the most suitable formulation was the sirolimus/E-SD/TPGS (1/8/1 solid dispersion in simulated gastric fluid (pH 1.2, owing to enhanced stability and degree of supersaturation of E-SD and TPGS. Furthermore, pharmacokinetic studies in rats indicated that compared to the physical mixture and sirolimus/HPMC/TPGS (1/8/1 solid dispersion, the sirolimus/E-SD/TPGS (1/8/1 solid dispersion significantly improved oral absorption of sirolimus. E-SD significantly inhibited the degradation of sirolimus in a dose-dependent manner. E-SD also significantly inhibited the precipitation of sirolimus compared to hydroxypropylmethyl cellulose (HPMC. Therefore, the results from the present study suggest that the sirolimus-loaded E-SD/TPGS solid dispersion has great potential in clinical applications.

  13. Gas and Gas Pains

    Science.gov (United States)

    ... to produce gas. Often, relatively simple changes in eating habits can lessen bothersome gas. Certain digestive system disorders, ... such as soda and beer, increase stomach gas. Eating habits, such as eating too quickly, drinking through a ...

  14. Formation of submarine gas hydrates

    Energy Technology Data Exchange (ETDEWEB)

    Soloviev, V.; Ginsburg, G.D. (Reserch Institute of Geology and Mineral Resources of the Ocean ' ' VNII Okeangeologia' ' , St. Petersburg (Russian Federation))

    1994-03-01

    Submarine gas hydrates have been discoverd in the course of deep-sea drilling (DSDP and ODP) and bottom sampling in many offshore regions. This paper reports on expeditions carried out in the Black, Caspian and Okhotsk Seas. Gas hydrate accumulations were discovered and investigated in all these areas. The data and an analysis of the results of the deep-sea drilling programme suggest that the infiltration of gas-bearing fluids is a necessary condition for gas hydrate accumulation. This is confirmed by geological observations at three scale levels. Firstly, hydrates in cores are usually associated with comparatively coarse-grained, permeable sediments as well as voids and fractures. Secondly, hydrate accumulations are controlled by permeable geological structures, i.e. faults, diapirs, mud volcanos as well as layered sequences. Thirdly, in the worldwide scale, hydrate accumulations are characteristic of continental slopes and rises and intra-continental seas where submarine seepages also are widespread. Both biogenic and catagenic gas may occur, and the gas sources may be located at various distances from the accumulation. Gas hydrates presumably originate from water-dissolved gas. The possibility of a transition from dissolved gas into hydrate is confirmed by experimental data. Shallow gas hydrate accumulations associated with gas-bearing fluid plumes are the most convenient features for the study of submarine hydrate formation in general. These accumulations are known from the Black, Caspian and Okhotsk Seas, the Gulf of Mexico and off northern California. (au) (24 refs.)

  15. Dissolving microneedle patches for dermal vaccination

    OpenAIRE

    Leone, M.; Monkare, J.T.; Bouwstra, J.A.; Kersten, G.F.A.

    2017-01-01

    The dermal route is an attractive route for vaccine delivery due to the easy skin accessibility and a dense network of immune cells in the skin. The development of microneedles is crucial to take advantage of the skin immunization and simultaneously to overcome problems related to vaccination by conventional needles (e.g. pain, needle-stick injuries or needle re-use). This review focuses on dissolving microneedles that after penetration into the skin dissolve releasing the encapsulated antige...

  16. Plan for radionuclide tracer studies of the residence time distribution in the Wilsonville dissolver and preheater

    International Nuclear Information System (INIS)

    Jolley, R.L.; Begovich, J.M.; Brashear, H.R.

    1983-12-01

    Stimulus-response measurements using radiotracers to measure residence time distribution (RTD) and hydrodynamic parameters for the preheaters and dissolvers at the Ft. Lewis Solvent Refined Coal (SRC) and the Exxon Donor Solvent (EDS) coal conversion pilot plants are reviewed. A plan is also presented for a series of radioactive tracer studies proposed for the Advanced Coal Liquefaction Facility at Wilsonville, Alabama, to measure the RTD for the preheater and dissolvers in the SRC-I mode. The tracer for the gas phase will be 133 Xe, and 198 Au (on carbonized resin or as an aqueous colloidal suspension) will be used as the slurry tracer. Four experimental phases are recommended for the RTD tracer studies: (1) preheater; (2) dissolver with 100% takeoff; (3) dissolver with 100% takeoff and solids withdrawal; and (4) dissolver with 50% takeoff. Eighteen gas-tracer and 22 liquid-tracer injections are projected to accomplish the four experimental phases. Two to four tracer injections are projected for preliminary tests to ensure the capability of safe injection of the radiotracers and the collection of statistically significant data. A complete projected cost and time schedule is provided, including procurement of necessary components, preparation of the radiotracers, assembly and testing of tracer injection apparatus and detection systems, onsite work and tracer injections, laboratory experimentation, data analysis, and report writing

  17. Toward the establishment of standardized in vitro tests for lipid-based formulations, part 3: understanding supersaturation versus precipitation potential during the in vitro digestion of type I, II, IIIA, IIIB and IV lipid-based formulations.

    Science.gov (United States)

    Williams, Hywel D; Sassene, Philip; Kleberg, Karen; Calderone, Marilyn; Igonin, Annabel; Jule, Eduardo; Vertommen, Jan; Blundell, Ross; Benameur, Hassan; Müllertz, Anette; Pouton, Colin W; Porter, Christopher J H

    2013-12-01

    Recent studies have shown that digestion of lipid-based formulations (LBFs) can stimulate both supersaturation and precipitation. The current study has evaluated the drug, formulation and dose-dependence of the supersaturation - precipitation balance for a range of LBFs. Type I, II, IIIA/B LBFs containing medium-chain (MC) or long-chain (LC) lipids, and lipid-free Type IV LBF incorporating different doses of fenofibrate or tolfenamic acid were digested in vitro in a simulated intestinal medium. The degree of supersaturation was assessed through comparison of drug concentrations in aqueous digestion phases (APDIGEST) during LBF digestion and the equilibrium drug solubility in the same phases. Increasing fenofibrate or tolfenamic acid drug loads (i.e., dose) had negligible effects on LC LBF performance during digestion, but promoted drug crystallization (confirmed by XRPD) from MC and Type IV LBF. Drug crystallization was only evident in instances when the calculated maximum supersaturation ratio (SR(M)) was >3. This threshold SR(M) value was remarkably consistent across all LBF and was also consistent with previous studies with danazol. The maximum supersaturation ratio (SR(M)) provides an indication of the supersaturation 'pressure' exerted by formulation digestion and is strongly predictive of the likelihood of drug precipitation in vitro. This may also prove effective in discriminating the in vivo performance of LBFs.

  18. U.S. crude oil, natural gas, and natural gas liquids reserves 1997 annual report

    Energy Technology Data Exchange (ETDEWEB)

    Wood, John H.; Grape, Steven G.; Green, Rhonda S.

    1998-12-01

    This report presents estimates of proved reserves of crude oil, natural gas, and natural gas liquids as of December 31, 1997, as well as production volumes for the US and selected States and State subdivisions for the year 1997. Estimates are presented for the following four categories of natural gas: total gas (wet after lease separation), nonassociated gas and associated-dissolved gas (which are the two major types of wet natural gas), and total dry gas (wet gas adjusted for the removal of liquids at natural gas processing plants). In addition, reserve estimates for two types of natural gas liquids, lease condensate and natural gas plant liquids, are presented. Also included is information on indicated additional crude oil reserves and crude oil, natural gas, and lease condensate reserves in nonproducing reservoirs. A discussion of notable oil and gas exploration and development activities during 1997 is provided. 21 figs., 16 tabs.

  19. The protective role of dissolved carbon dioxide against wine oxidation: a simple and rational approach

    Directory of Open Access Journals (Sweden)

    Audrey Devatine

    2011-09-01

    Significance and impact of the study: The physical understanding of this phenomenon can be found in the fact that as soon as a gaseous air or pure oxygen phase is in contact with a carbon dioxide saturated liquid, the dissolved carbon dioxide, which is not at equilibrium with the gaseous phase, tends to escape into this gaseous phase. This study points out the complexity of the gas-liquid equilibrium when two dissolved gases are simultaneously present in a liquid and its implication in the winemaking process.

  20. Fuel-coolant interactions: preliminary experiments on the effect of gases dissolved in the 'coolant'

    International Nuclear Information System (INIS)

    Asher, R.C.; Davies, D.; Jones, P.G.

    1976-12-01

    A simple apparatus has been used to study fuel-coolant interactions under reasonably well controlled conditions. Preliminary experiments have used water as the 'coolant' and molten tin at 800 0 C as the 'fuel' and have investigated how the violence of the interaction is affected by dissolving gases (oxygen, nitrogen, carbon dioxide and nitrous oxide) in the water. It was found that saturating the water with carbon dioxide or nitrous oxide completely suppresses the violent interaction. Experiments in which the concentrations of these gases were varied showed that a certain critical concentration was needed; below this concentration the dissolved gas has no significant effect but above it the suppression is

  1. Dissolving Microneedle Patches for Dermal Vaccination.

    Science.gov (United States)

    Leone, M; Mönkäre, J; Bouwstra, J A; Kersten, G

    2017-11-01

    The dermal route is an attractive route for vaccine delivery due to the easy skin accessibility and a dense network of immune cells in the skin. The development of microneedles is crucial to take advantage of the skin immunization and simultaneously to overcome problems related to vaccination by conventional needles (e.g. pain, needle-stick injuries or needle re-use). This review focuses on dissolving microneedles that after penetration into the skin dissolve releasing the encapsulated antigen. The microneedle patch fabrication techniques and their challenges are discussed as well as the microneedle characterization methods and antigen stability aspects. The immunogenicity of antigens formulated in dissolving microneedles are addressed. Finally, the early clinical development is discussed.

  2. Understanding the generation and maintenance of supersaturation during the dissolution of amorphous solid dispersions using modulated DSC and 1H NMR.

    Science.gov (United States)

    Baghel, Shrawan; Cathcart, Helen; O'Reilly, Niall J

    2018-01-30

    In this study, the dissolution behaviour of dipyridamole (DPM) and cinnarizine (CNZ) spray-dried amorphous solid dispersions (ASDs) using polyvinyl pyrrolidone (PVP) and polyacrylic acid (PAA) as a carrier matrix were evaluated and compared. The drug concentrations achieved from the dissolution of PVP and PAA solid dispersions were significantly greater than the equilibrium solubility of crystalline DPM and CNZ in phosphate buffer pH 6.8 (PBS 6.8). The maximum drug concentration achieved by dissolution of PVP and PAA solid dispersions did not exceed the theoretically calculated apparent solubility of amorphous DPM and CNZ. However, the degree of supersaturation of DPM and CNZ increased considerably as the polymer weight fraction within the solid dispersion increased. In addition, the supersaturation profile of DPM and CNZ were studied in the presence and absence of the polymers. PAA was found to maintain a higher level of supersaturation compared to PVP. The enhanced drug solution concentration following dissolution of ASDs can be attributed to the reduced crystal growth rates of DPM and CNZ at an equivalent supersaturation. We have also shown that, for drugs having high crystallization tendency and weak drug-polymer interaction, the feasible way to increase dissolution might be increase the polymer weight fraction in the ASD. Solution 1 H NMR spectra were used to understand dissolution mechanism and to identify drug-polymer interaction. The change in electron densities of proton attached to different groups in DPM and CNZ suggested drug-polymer interaction in solution. The relative intensities of peak shift and nature of interaction between drug and polymer in different systems are different. These different effects suggest that DPM and CNZ interacts in a different way with PVP and PAA in solution which goes some way towards explaining the different polymeric effect, particularly in terms of inhibition of drug recrystallization and dissolution of DPM and CNZ ASDs

  3. A Ni-Doped Carbon Nanotube Sensor for Detecting Oil-Dissolved Gases in Transformers

    Directory of Open Access Journals (Sweden)

    Jia Lu

    2015-06-01

    Full Text Available C2H2, C2H4, and C2H6 are important oil-dissolved gases in power transformers. Detection of the composition and content of oil-dissolved gases in transformers is very significant in the diagnosis and assessment of the state of transformer operations. The commonly used oil-gas analysis methods have many disadvantages, so this paper proposes a Ni-doped carbon nanotube (Ni-CNT gas sensor to effectively detect oil-dissolved gases in a transformer. The gas-sensing properties of the sensor to C2H2, C2H4, and C2H6 were studied using the test device. Based on the density functional theory (DFT the adsorption behaviors of the three gases on intrinsic carbon nanotubes (CNTs and Ni-CNTs were calculated. The adsorption energy, charge transfer, and molecular frontier orbital of the adsorption system were also analyzed. Results showed that the sensitivity of the CNT sensor to the three kinds of gases was in the following order: C2H2 > C2H4 > C2H6. Moreover, the doped Ni improved the sensor response, and the sensor response and gas concentration have a good linear relationship.

  4. A Ni-Doped Carbon Nanotube Sensor for Detecting Oil-Dissolved Gases in Transformers.

    Science.gov (United States)

    Lu, Jia; Zhang, Xiaoxing; Wu, Xiaoqing; Dai, Ziqiang; Zhang, Jinbin

    2015-06-09

    C2H2, C2H4, and C2H6 are important oil-dissolved gases in power transformers. Detection of the composition and content of oil-dissolved gases in transformers is very significant in the diagnosis and assessment of the state of transformer operations. The commonly used oil-gas analysis methods have many disadvantages, so this paper proposes a Ni-doped carbon nanotube (Ni-CNT) gas sensor to effectively detect oil-dissolved gases in a transformer. The gas-sensing properties of the sensor to C2H2, C2H4, and C2H6 were studied using the test device. Based on the density functional theory (DFT) the adsorption behaviors of the three gases on intrinsic carbon nanotubes (CNTs) and Ni-CNTs were calculated. The adsorption energy, charge transfer, and molecular frontier orbital of the adsorption system were also analyzed. Results showed that the sensitivity of the CNT sensor to the three kinds of gases was in the following order: C2H2 > C2H4 > C2H6. Moreover, the doped Ni improved the sensor response, and the sensor response and gas concentration have a good linear relationship.

  5. Dissolved methane in New York groundwater, 1999-2011

    Science.gov (United States)

    Kappel, William M.; Nystrom, Elizabeth A.

    2012-01-01

    New York State is underlain by numerous bedrock formations of Cambrian to Devonian age that produce natural gas and to a lesser extent oil. The first commercial gas well in the United States was dug in the early 1820s in Fredonia, south of Buffalo, New York, and produced methane from Devonian-age black shale. Methane naturally discharges to the land surface at some locations in New York. At Chestnut Ridge County Park in Erie County, just south of Buffalo, N.Y., several surface seeps of natural gas occur from Devonian black shale, including one behind a waterfall. Methane occurs locally in the groundwater of New York; as a result, it may be present in drinking-water wells, in the water produced from those wells, and in the associated water-supply systems (Eltschlager and others, 2001). The natural gas in low-permeability bedrock formations has not been accessible by traditional extraction techniques, which have been used to tap more permeable sandstone and carbonate bedrock reservoirs. However, newly developed techniques involving horizontal drilling and high-volume hydraulic fracturing have made it possible to extract previously inaccessible natural gas from low-permeability bedrock such as the Marcellus and Utica Shales. The use of hydraulic fracturing to release natural gas from these shale formations has raised concerns with water-well owners and water-resource managers across the Marcellus and Utica Shale region (West Virginia, Pennsylvania, New York and parts of several other adjoining States). Molofsky and others (2011) documented the widespread natural occurrence of methane in drinking-water wells in Susquehanna County, Pennsylvania. In the same county, Osborn and others (2011) identified elevated methane concentrations in selected drinking-water wells in the vicinity of Marcellus gas-development activities, although pre-development samples were not available for comparison. In order to manage water resources in areas of gas-well drilling and hydraulic

  6. CADDIS Volume 2. Sources, Stressors and Responses: Dissolved Oxygen - Detailed Conceptual Diagram

    Science.gov (United States)

    Introduction to the dissolved oxygen module, when to list dissolved oxygen as a candidate cause, ways to measure dissolved oxygen, simple and detailed conceptual model diagrams for dissolved oxygen, references for the dissolved oxygen module.

  7. CADDIS Volume 2. Sources, Stressors and Responses: Dissolved Oxygen - Simple Conceptual Diagram

    Science.gov (United States)

    Introduction to the dissolved oxygen module, when to list dissolved oxygen as a candidate cause, ways to measure dissolved oxygen, simple and detailed conceptual model diagrams for dissolved oxygen, references for the dissolved oxygen module.

  8. Gas-evolution oscillators. 10. A model based on a delay equation

    Energy Technology Data Exchange (ETDEWEB)

    Bar-Eli, K.; Noyes, R.M. [Univ. of Oregon, Eugene, OR (United States)

    1992-09-17

    This paper develops a simplified method to model the behavior of a gas-evolution oscillator with two differential delay equations in two unknowns consisting of the population of dissolved molecules in solution and the pressure of the gas.

  9. Gas-evolution oscillators. 10. A model based on a delay equation

    International Nuclear Information System (INIS)

    Bar-Eli, K.; Noyes, R.M.

    1992-01-01

    This paper develops a simplified method to model the behavior of a gas-evolution oscillator with two differential delay equations in two unknowns consisting of the population of dissolved molecules in solution and the pressure of the gas

  10. Dissolved petroleum hydrocarbons in the Andaman Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Topgi, R.S.; Noronha, R.J.; Fondekar, S.P.

    Mean dissolved petroleum hydrocarbons, measured using UV-spectrophotometry, at 0 and 10m were 51 plus or minus 1 and 55 plus or minus 1.2 mu g/litre respectively; range of variation being between 28 and 83 mu g/litre. Very little difference...

  11. Dissolved carbohydrate in the central Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Dhople, V.M.; Bhosle, N.B.

    with chlorophyll a (P 0.001) and phaeopigments (P 0.001) suggesting its release from the former and zooplankton grazing in the latter. Inverse correlations with dissolved oxygen, phosphate and nitrate indicated the possibility of the release of carbohydrate from...

  12. Modeling Fish Growth in Low Dissolved Oxygen

    Science.gov (United States)

    Neilan, Rachael Miller

    2013-01-01

    This article describes a computational project designed for undergraduate students as an introduction to mathematical modeling. Students use an ordinary differential equation to describe fish weight and assume the instantaneous growth rate depends on the concentration of dissolved oxygen. Published laboratory experiments suggest that continuous…

  13. Total dissolved carbohydrate in Mahi river estuary

    Digital Repository Service at National Institute of Oceanography (India)

    Bhosle, N.B.; Rokade, M.A.; Zingde, M.D.

    Total dissolved carbohydrate varied from 4.37-15 mg l-1 and 3.71-15.95 mg l-1 in the surface and bottom samples respectively. Highest concentration of carbohydrate was observed at station 1 which decreased downward upto Station 6 which showed...

  14. Radiocarbon in marine dissolved organic carbon (DOC)

    NARCIS (Netherlands)

    Clercq, M. le; Plicht, J. van der; Meijer, H.A.J.; Baar, H.J.W. de

    Dissolved Organic Carbon (DOC) plays an important role in the ecology and carbon cycle in the ocean. Analytical problems with concentration and isotope ratio measurements have hindered its study. We have constructed a new analytical method based on supercritical oxidation for the determination of

  15. US crude oil, natural gas, and natural gas liquids reserves, 1992 annual report

    Energy Technology Data Exchange (ETDEWEB)

    1993-10-18

    This report presents estimates of proved reserves of crude oil, natural gas, and natural gas liquids as of December 31, 1992, as well as production volumes for the United States, and selected States and State subdivisions for the year 1992. Estimates are presented for the following four categories of natural gas: total gas (wet after lease separation), its two major components (nonassociated and associated-dissolved gas), and total dry gas (wet gas adjusted for the removal of liquids at natural gas processing plants). In addition, two components of natural gas liquids, lease condensate and natural gas plant liquids, have their reserves and production data presented. Also included is information on indicated additional crude oil reserves and crude oil, natural gas, and lease condensate reserves in nonproducing reservoirs. A discussion of notable oil and gas exploration and development activities during 1992 is provided.

  16. US crude oil, natural gas, and natural gas liquids reserves, 1992 annual report

    International Nuclear Information System (INIS)

    1993-01-01

    This report presents estimates of proved reserves of crude oil, natural gas, and natural gas liquids as of December 31, 1992, as well as production volumes for the United States, and selected States and State subdivisions for the year 1992. Estimates are presented for the following four categories of natural gas: total gas (wet after lease separation), its two major components (nonassociated and associated-dissolved gas), and total dry gas (wet gas adjusted for the removal of liquids at natural gas processing plants). In addition, two components of natural gas liquids, lease condensate and natural gas plant liquids, have their reserves and production data presented. Also included is information on indicated additional crude oil reserves and crude oil, natural gas, and lease condensate reserves in nonproducing reservoirs. A discussion of notable oil and gas exploration and development activities during 1992 is provided

  17. The growth of oscillating bubbles in an ultrasound field

    Science.gov (United States)

    Yamauchi, Risa; Yamashita, Tatsuya; Ando, Keita

    2017-11-01

    From our recent experiments to test particle removal by underwater ultrasound, dissolved gas supersaturation is found to play an important role in physical cleaning; cavitation bubble nucleation can be triggered easily by weak ultrasound under the supersaturation and mild motion of the bubbles contributes to efficient cleaning without erosion. The state of gas bubble nuclei in water is critical to the determination of a cavitation inception threshold. Under ultrasound forcing, the size of bubble nuclei is varied by the transfer of dissolved gas (i.e., rectified diffusion); the growth rate will be promoted by the supersaturation and is thus expected to contribute to cavitation activity enhancement. In the present work, we experimentally study rectified diffusion for bubbles attached at glass surfaces in an ultrasound field. We will present the evolution of bubble nuclei sizes with varying parameters such as dissolved oxygen supersaturation, and ultrasound intensity and frequency. the Research Grant of Keio Leading-edge Laboratory of Science & Technology.

  18. Removal of organic compounds from shale gas flowback water

    NARCIS (Netherlands)

    Butkovskyi, Andrii; Faber, Ann-Hélène; Wang, Yue; Grolle, Katja; Hofman-Caris, Roberta; Bruning, Harry; Van Wezel, Annemarie P.; Rijnaarts, Huub H M

    2018-01-01

    Ozonation, sorption to granular activated carbon and aerobic degradation were compared as potential treatment methods for removal of dissolved organic carbon (DOC) fractions and selected organic compounds from shale gas flowback water after pre-treatment in dissolved air flotation unit. Flowback

  19. Air-water Gas Exchange Rates on a Large Impounded River Measured Using Floating Domes (Poster)

    Science.gov (United States)

    Mass balance models of dissolved gases in rivers typically serve as the basis for whole-system estimates of greenhouse gas emission rates. An important component of these models is the exchange of dissolved gases between air and water. Controls on gas exchange rates (K) have be...

  20. Cooling Performance of a Partially-Confined FC-72 Spray: The Effect of Dissolved Air (Postprint)

    Science.gov (United States)

    2007-01-01

    plate FC = FC-72 fluid htr = heater conductive layer int = interface between heater substrate and insulating support post m = measured s = heater... microporous enhanced surface and a plain reference surface, and developed correlations for nucleate boiling and CHF. The results of the experiment...8Rainey, K. N., You, S. M., and Lee, S., “Effect of Pressure, Subcooling, and Dissolved Gas on Pool Boiling Heat Transfer from Microporous Surfaces

  1. Development of a prototype for dissolved CO2 rapid measurement and preliminary tests

    Science.gov (United States)

    Li, Meng; Guo, Jinjia; Zhang, Zhihao; Luo, Zhao; Qin, Chuan; Zheng, Ronger

    2017-10-01

    The measurements of dissolved CO2 in seawater is of great significance for the study of global carbon cycle. At present, the commercial sensors used for dissolved CO2 measurements are mostly equipped with permeable membranes for the purpose of gas-liquid separation, with the advantages of easy operation, low cost, etc.. However, most of these devices measure CO2 after reaching gas equilibrium, so it takes a few minutes to respond, which limited its applications in rapid measurements. In this paper, a set of prototype was developed for the rapid measurements of dissolved CO2. The system was built basing the direct absorption TDLAS. To detect the CO2 absorption line located at 4991.26 cm-1 , a fiber-coupled DFB laser operating at 2004 nm was selected as the light source. A Herriott type multi-pass cavity with an effective optical path length of 10 m and an inner volume of 90 mL was used for absorption measurements. A detection limit of 26 μatm can be obtained with this compact cavity. To realize the rapid measurements of dissolved CO2, a degasser with high degassing rate was necessary. A hollow fiber membrane with a large permeable area used in this paper can achieve degassing rate up to 2.88 kPa/min. Benefitted from the high degassing rate of the degasser and high sensitivity of the compact TDLAS system, a rapid measurement of dissolved CO2 in water can be achieved within 1s time, and the response time of the prototype when the dissolved CO2 concentration changed abruptly in actual measurement was 15 s. To evaluate the performance of the prototype, comparison measurements were carried out with a commercial mass spectrometer. The dissolved CO2 in both seawater and tap-water was measured, and the experimental results showed good consistent trends with R2 of 0.973 and 0.931. The experimental results proved the feasibility of dissolved CO2 rapid measurement. In the near future, more system evaluation experiments will be carried out and the system will be further

  2. In situ spectrophotometric measurement of dissolved inorganic carbon in seawater

    Science.gov (United States)

    Liua, Xuewu; Byrne, Robert H.; Adornato, Lori; Yates, Kimberly K.; Kaltenbacher, Eric; Ding, Xiaoling; Yang, Bo

    2013-01-01

    Autonomous in situ sensors are needed to document the effects of today’s rapid ocean uptake of atmospheric carbon dioxide (e.g., ocean acidification). General environmental conditions (e.g., biofouling, turbidity) and carbon-specific conditions (e.g., wide diel variations) present significant challenges to acquiring long-term measurements of dissolved inorganic carbon (DIC) with satisfactory accuracy and resolution. SEAS-DIC is a new in situ instrument designed to provide calibrated, high-frequency, long-term measurements of DIC in marine and fresh waters. Sample water is first acidified to convert all DIC to carbon dioxide (CO2). The sample and a known reagent solution are then equilibrated across a gas-permeable membrane. Spectrophotometric measurement of reagent pH can thereby determine the sample DIC over a wide dynamic range, with inherent calibration provided by the pH indicator’s molecular characteristics. Field trials indicate that SEAS-DIC performs well in biofouling and turbid waters, with a DIC accuracy and precision of ∼2 μmol kg–1 and a measurement rate of approximately once per minute. The acidic reagent protects the sensor cell from biofouling, and the gas-permeable membrane excludes particulates from the optical path. This instrument, the first spectrophotometric system capable of automated in situ DIC measurements, positions DIC to become a key parameter for in situ CO2-system characterizations.

  3. Determination of dissolved gases in basalt groundwater in the Pasco Basin, Washington

    International Nuclear Information System (INIS)

    Halko, D.J.

    1986-09-01

    The determination of dissolved gases in groundwater is required for complete hydrochemical characterization of the Columbia River Basalt Group beneath the Hanford Site. A gas chromatographic method has been developed for the determination of argon, oxygen, nitrogen, carbon monoxide, carbon dioxide, and methane in groundwater. In addition to a gas chromatograph equipped with thermal conductivity and flame ionization detectors, equipment utilized consists of a purge device that strips these gases from solution for subsequent separation using Molecular Sieve 5A and porous polymer columns. This technique is capable of accommodating pressurized fluid samples collected from the deep aquifers with in situ samplers. The analysis is discussed in detail

  4. BOREAS TGB-5 Dissolved Organic Carbon Data from NSA Beaver Ponds

    Science.gov (United States)

    Bourbonniere, Rick; Hall, Forrest G. (Editor); Conrad, Sara K. (Editor)

    2000-01-01

    The BOReal Ecosystem-Atmosphere Study Trace Gas Biogeochemistry (BOREAS TGB-5) team collected several data sets related to carbon and trace gas fluxes and concentrations in the Northern Study Area (NSA). This data set contains concentrations of dissolved organic and inorganic carbon species from water samples collected at various NSA sites. In particular, this set covers the NSA Tower Beaver Pond Site and the NSA Gillam Road Beaver Pond Site, including data from all visits to open water sampling locations during the BOREAS field campaigns from April to September 1994. The data are provided in tabular ASCII files.

  5. Dissolved oxygen detection by galvanic displacement-induced

    Indian Academy of Sciences (India)

    Dissolved oxygen detection by galvanic displacement-induced graphene/silver nanocomposite ... dissolved oxygen (DO) detection based on a galvanic displacement synthesized reduced graphene oxide–silver nanoparticles ... Current Issue

  6. Effect of Greenhouse Gases Dissolved in Seawater.

    Science.gov (United States)

    Matsunaga, Shigeki

    2015-12-30

    A molecular dynamics simulation has been performed on the greenhouse gases carbon dioxide and methane dissolved in a sodium chloride aqueous solution, as a simple model of seawater. A carbon dioxide molecule is also treated as a hydrogen carbonate ion. The structure, coordination number, diffusion coefficient, shear viscosity, specific heat, and thermal conductivity of the solutions have been discussed. The anomalous behaviors of these properties, especially the negative pressure dependence of thermal conductivity, have been observed in the higher-pressure region.

  7. A degassing instrument for analysing CO2 dissolved in natural water

    Science.gov (United States)

    Durham, Brian; Pfrang, Christian

    2017-04-01

    Arising from our EGU 2017 presentation (http://meetingorganizer.copernicus.org/EGU2016/posters/20564, X2 352), interest has been expressed in its application to the analysis of the hydrocarbonate ion [HCO3-] in atmospheric water. Arising from the historic difficulty in analysing the aqueous [HCO3-] ion ('it is in all our reagents', pers. comm. UK laboratory) the classic determination has been to measure a suite of other anions and cations including [H+] via pH, and to treat the balance of negative charge as a measure of [HCO3-]. From this balance, dissolved CO2 can be inferred via the dissociation constant as published for pure water. CO2 + H2O ⇓♢[HCO3-] + [H+] K1 = 4.2 x 10-7 Our EGU 2016 presentation sought to determine how the ionic environment in 263 UK rain samples can influence the above equilibrium, which is work in progress. In the mean time we have received the following expression of interest from an atmospheric science advisory group. …….. is very interested in the role of H-carbonate in the ion balance of precipitation. They have had some discussions recently about the best approach to infer H-carbonate currently discussing the possibility of sending you samples from other locations for analysis. We have duly offered to use our degassing instrument to corroborate current analyses in a batch of 'blind' samples, and to provide a design for a basic degasser that water quality laboratories could evaluate in house. This paper therefore presents a circuit for degassing CO2 from water samples irrespective of whether in atmospheric equilibrium or supersaturated, including a prototype 4-way distribution and collection valve which it is hoped will make the analysis intuitive and therefore open to automation.

  8. Controls on the Origin and Cycling of Riverine Dissolved Inorganic Carbon in the Brazos River, Texas

    Science.gov (United States)

    Zeng, F.; Masiello, C. A.; Hockaday, W. C.

    2008-12-01

    Rivers are generally supersaturated in CO2 with respect to the atmosphere. However, there is little agreement on the sources and turnover times of excess CO2 in river waters. This is likely due to varying dominant controls on carbon sources (e.g. geologic setting, climate, land use, or human activities). In this study, we measured carbon isotopic signatures (δ13C and Δ14C) of riverine dissolved inorganic carbon (DIC), as well as solid state cross polarization/magic angle spinning (CP/MAS) 13C nuclear magnetic resonance (NMR) of particulate organic carbon (POC), to determine carbon sources fuelling respiration of the Brazos River in Texas. We found that sources of riverine CO2 varied significantly along the length of the Brazos. In the middle Brazos (between Graham and Waco), which is partially underlain by limestone, riverine DIC had average Δ14C of 74 ‰ and δ13C of -7.5 ‰, suggesting that riverine CO2 is derived almost entirely from contemporary carbon (less than 5 years old) with little evidence of carbonate input, probably due to the damming upstream of Waco. In the lower Brazos (downstream of Bryan), riverine DIC was highly depleted in 14C (average Δ14C = -148.5 ‰) and enriched in 13C (average δ13C= -9.32 ‰), indicative of the presence of old carbonate. Since there is no carbonate bedrock in contact with the river in this area, the most likely source of old carbonate is the shell used in road and building construction throughout the 19th century. Our results suggest that the effect of human activities superimposes and even surpasses the effect of natural controls (e.g. geologic setting and climate) on C cycling in the Brazos.

  9. Passive sampling and analyses of common dissolved fixed gases in groundwater

    International Nuclear Information System (INIS)

    Spalding, Brian Patrick; Watson, David B.

    2008-01-01

    An in situ passive sampler and gas chromatographic protocol for analysis of the major and several minor fixed gases in groundwater was developed. A gas-tight syringe, mated to a short length of silicone tubing, was equilibrated with dissolved gases in groundwater by immersing in monitoring wells and was used to transport and to inject a 0.5 mL gas sample into a gas chromatograph. Using Ar carrier gas, a HaySep DB porous polymer phase, and sequential thermal conductivity and reductive gas detectors allowed good sensitivity for He, Ne, H2, N2, O2, CO, CH4, CO2, and N2O. Within 4 days of immersion in groundwater, samplers initially filled with either He or air attained the same and constant gas composition at an Oak Ridge, Tennessee, site heavily impacted by uranium, acidity, and nitrate. Between June 2006 and July 2007, 12 permanent groundwater wells were used to test the passive samplers in groundwater contaminated by a group of four closed radioactive wastewater seepage ponds; over a thousand passive gas samples from these wells averaged 56% CO2, 32.4% N2, 2.5% O2, 2.5% N2O, 0.20% CH4, 0.096% H2, and 0.023% CO with an average recovery of 95 14% of the injected gas volume

  10. Dissolvable microneedle fabrication using piezoelectric dispensing technology.

    Science.gov (United States)

    Allen, Evin A; O'Mahony, Conor; Cronin, Michael; O'Mahony, Thomas; Moore, Anne C; Crean, Abina M

    2016-03-16

    Dissolvable microneedle (DMN) patches are novel dosage forms for the percutaneous delivery of vaccines. DMN are routinely fabricated by dispensing liquid formulations into microneedle-shaped moulds. The liquid formulation within the mould is then dried to create dissolvable vaccine-loaded microneedles. The precision of the dispensing process is critical to the control of formulation volume loaded into each dissolvable microneedle structure. The dispensing process employed must maintain vaccine integrity. Wetting of mould surfaces by the dispensed formulation is also an important consideration for the fabrication of sharp-tipped DMN. Sharp-tipped DMN are essential for ease of percutaneous administration. In this paper, we demonstrate the ability of a piezoelectric dispensing system to dispense picolitre formulation volumes into PDMS moulds enabling the fabrication of bilayer DMN. The influence of formulation components (trehalose and polyvinyl alcohol (PVA) content) and piezoelectric actuation parameters (voltage, frequency and back pressure) on drop formation is described. The biological integrity of a seasonal influenza vaccine following dispensing was investigated and maintained voltage settings of 30 V but undermined at higher settings, 50 and 80 V. The results demonstrate the capability of piezoelectric dispensing technology to precisely fabricate bilayer DMN. They also highlight the importance of identifying formulation and actuation parameters to ensure controlled droplet formulation and vaccine stabilisation. Copyright © 2015 Elsevier B.V. All rights reserved.

  11. Investigation of the effective peak supersaturation for liquid-phase clouds at the high-alpine site Jungfraujoch, Switzerland (3580 m a.s.l.

    Directory of Open Access Journals (Sweden)

    E. Hammer

    2014-01-01

    Full Text Available Aerosols influence the Earth's radiation budget directly through absorption and scattering of solar radiation in the atmosphere but also indirectly by modifying the properties of clouds. However, climate models still suffer from large uncertainties as a result of insufficient understanding of aerosol-cloud interactions. At the high altitude research station Jungfraujoch (JFJ; 3580 m a.s.l., Switzerland cloud condensation nuclei (CCN number concentrations at eight different supersaturations (SS from 0.24% to 1.18% were measured using a CCN counter during Summer 2011. Simultaneously, in-situ aerosol activation properties of the prevailing ambient clouds were investigated by measuring the total and interstitial (non-activated dry particle number size distributions behind two different inlet systems. Combining all experimental data, a new method was developed to retrieve the so-called effective peak supersaturation SSpeak, as a measure of the SS at which ambient clouds are formed. A 17-month CCN climatology was then used to retrieve the SSpeak values also for four earlier summer campaigns (2000, 2002, 2004 and 2010 where no direct CCN data were available. The SSpeak values varied between 0.01% and 2.0% during all campaigns. An overall median SSpeak of 0.35% and dry activation diameter of 87 nm was observed. It was found that the difference in topography between northwest and southeast plays an important role for the effective peak supersaturation in clouds formed in the vicinity of the JFJ, while differences in the number concentration of potential CCN only play a minor role. Results show that air masses coming from the southeast (with the slowly rising terrain of the Aletsch Glacier generally experience lower SSpeak values than air masses coming from the northwest (steep slope. The observed overall median values were 0.41% and 0.22% for northwest and southeast wind conditions, respectively, corresponding to literature values for cumulus clouds and

  12. Fabrication of Nb3Al superconducting wires by utilizing the mechanically alloyed Nb(Al)ss supersaturated solid-solution with low-temperature annealing

    International Nuclear Information System (INIS)

    Pan, X.F.; Yan, G.; Qi, M.; Cui, L.J.; Chen, Y.L.; Zhao, Y.; Li, C.S.; Liu, X.H.; Feng, Y.; Zhang, P.X.; Liu, H.J.

    2014-01-01

    Highlights: • This paper reported superconducting properties of the powder-in-tube Nb 3 Al wires. • The Nb 3 Al wires were made by using Nb(Al) ss supersaturated solid solution powders. • The Cu-matrix Nb 3 Al superconducting wires have been successfully fabricated. • The transport J c of Nb 3 Al wires at 4.2 K, 10 T is up to 12,700 A/cm 2 . - Abstract: High-performance Nb 3 Al superconducting wire is a promising candidate to the application of high-field magnets. However, due to the production problem of km-grade wires that are free from low magnetic field instability, the Nb 3 Al wires made by rapid heating, quenching and transformation (RHQT) are still not available to the large-scale engineering application. In this paper, we reported the properties of the in situ powder-in-tube (PIT) Nb 3 Al superconducting wires, which were made by using the mechanically alloyed Nb(Al) ss supersaturated solid solution, as well as the low temperature heat-treatment at 800 °C for 10 h. The results show that Nb 3 Al superconductors in this method possess very fine grains and well superconducting properties, though a little of Nb 2 Al and Nb impurities still keep being existence at present work. At the Nb 3 Al with a nominal 26 at.% Al content, the onset T c reaches 15.8 K. Furthermore, a series of Nb 3 Al wires and tapes with various sizes have been fabricated; for the 1.0 mm-diameter wire, the J c at 4.2 K, 10 T and 14 T have achieved 12,700 and 6900 A/cm 2 , respectively. This work suggests it is possible to develop high-performance Cu-matrix Nb 3 Al superconducting wires by directly using the Nb(Al) ss supersaturated solid-solution without the complex RHQT heat-treatment process

  13. Fabrication of Nb{sub 3}Al superconducting wires by utilizing the mechanically alloyed Nb(Al){sub ss} supersaturated solid-solution with low-temperature annealing

    Energy Technology Data Exchange (ETDEWEB)

    Pan, X.F. [National Engineering Laboratory for Superconducting Material, Western Superconducting Technologies (WST) Co., Ltd., Xi’an 710018 (China); Superconducting Materials Center, Northwest Institute for Nonferrous Metal Research, Xi’an 710016 (China); Yan, G., E-mail: gyan@c-nin.com [National Engineering Laboratory for Superconducting Material, Western Superconducting Technologies (WST) Co., Ltd., Xi’an 710018 (China); Superconducting Materials Center, Northwest Institute for Nonferrous Metal Research, Xi’an 710016 (China); Qi, M. [Superconducting Materials Center, Northwest Institute for Nonferrous Metal Research, Xi’an 710016 (China); Cui, L.J. [National Engineering Laboratory for Superconducting Material, Western Superconducting Technologies (WST) Co., Ltd., Xi’an 710018 (China); Chen, Y.L.; Zhao, Y. [Key Laboratory of Magnetic Levitation Technologies and Maglev Trains (Ministry of Education of China), Superconductivity and New Energy R and D Center, Southwest Jiaotong University, Chengdu 610031 (China); Li, C.S. [Superconducting Materials Center, Northwest Institute for Nonferrous Metal Research, Xi’an 710016 (China); Liu, X.H. [National Engineering Laboratory for Superconducting Material, Western Superconducting Technologies (WST) Co., Ltd., Xi’an 710018 (China); Feng, Y.; Zhang, P.X. [National Engineering Laboratory for Superconducting Material, Western Superconducting Technologies (WST) Co., Ltd., Xi’an 710018 (China); Key Laboratory of Magnetic Levitation Technologies and Maglev Trains (Ministry of Education of China), Superconductivity and New Energy R and D Center, Southwest Jiaotong University, Chengdu 610031 (China); Liu, H.J. [Institute of Plasma Physics, Chinese Academy of Sciences (CAS), Hefei 230031 (China); and others

    2014-07-15

    Highlights: • This paper reported superconducting properties of the powder-in-tube Nb{sub 3}Al wires. • The Nb{sub 3}Al wires were made by using Nb(Al){sub ss} supersaturated solid solution powders. • The Cu-matrix Nb{sub 3}Al superconducting wires have been successfully fabricated. • The transport J{sub c} of Nb{sub 3}Al wires at 4.2 K, 10 T is up to 12,700 A/cm{sup 2}. - Abstract: High-performance Nb{sub 3}Al superconducting wire is a promising candidate to the application of high-field magnets. However, due to the production problem of km-grade wires that are free from low magnetic field instability, the Nb{sub 3}Al wires made by rapid heating, quenching and transformation (RHQT) are still not available to the large-scale engineering application. In this paper, we reported the properties of the in situ powder-in-tube (PIT) Nb{sub 3}Al superconducting wires, which were made by using the mechanically alloyed Nb(Al){sub ss} supersaturated solid solution, as well as the low temperature heat-treatment at 800 °C for 10 h. The results show that Nb{sub 3}Al superconductors in this method possess very fine grains and well superconducting properties, though a little of Nb{sub 2}Al and Nb impurities still keep being existence at present work. At the Nb{sub 3}Al with a nominal 26 at.% Al content, the onset T{sub c} reaches 15.8 K. Furthermore, a series of Nb{sub 3}Al wires and tapes with various sizes have been fabricated; for the 1.0 mm-diameter wire, the J{sub c} at 4.2 K, 10 T and 14 T have achieved 12,700 and 6900 A/cm{sup 2}, respectively. This work suggests it is possible to develop high-performance Cu-matrix Nb{sub 3}Al superconducting wires by directly using the Nb(Al){sub ss} supersaturated solid-solution without the complex RHQT heat-treatment process.

  14. Tracing Acetylene Dissolved in Transformer Oil by Tunable Diode Laser Absorption Spectrum.

    Science.gov (United States)

    Ma, Guo-Ming; Zhao, Shu-Jing; Jiang, Jun; Song, Hong-Tu; Li, Cheng-Rong; Luo, Ying-Ting; Wu, Hao

    2017-11-02

    Dissolved gas analysis (DGA) is widely used in monitoring and diagnosing of power transformer, since the insulation material in the power transformer decomposes gases under abnormal operation condition. Among the gases, acetylene, as a symbol of low energy spark discharge and high energy electrical faults (arc discharge) of power transformer, is an important monitoring parameter. The current gas detection method used by the online DGA equipment suffers from problems such as cross sensitivity, electromagnetic compatibility and reliability. In this paper, an optical gas detection system based on TDLAS technology is proposed to detect acetylene dissolved in transformer oil. We selected a 1530.370 nm laser in the near infrared wavelength range to correspond to the absorption peak of acetylene, while using the wavelength modulation strategy and Herriott cell to improve the detection precision. Results show that the limit of detection reaches 0.49 ppm. The detection system responds quickly to changes of gas concentration and is easily to maintenance while has no electromagnetic interference, cross-sensitivity, or carrier gas. In addition, a complete detection process of the system takes only 8 minutes, implying a practical prospect of online monitoring technology.

  15. Mathematical modeling of dissolved oxygen in fish ponds ...

    African Journals Online (AJOL)

    Mathematical modeling of dissolved oxygen in fish ponds. WJS Mwegoha, ME Kaseva, SMM Sabai. Abstract. A mathematical model was developed to predict the effects of wind speed, light, pH, Temperature, dissolved carbon dioxide and chemical oxygen demand (COD) on Dissolved Oxygen (DO) in fish ponds. The effects ...

  16. Total dissolved atmospheric nitrogen deposition in the anoxic Cariaco basin

    Science.gov (United States)

    Rasse, R.; Pérez, T.; Giuliante, A.; Donoso, L.

    2018-04-01

    Atmospheric deposition of total dissolved nitrogen (TDN) is an important source of nitrogen for ocean primary productivity that has increased since the industrial revolution. Thus, understanding its role in the ocean nitrogen cycle will help assess recent changes in ocean biogeochemistry. In the anoxic Cariaco basin, the place of the CARIACO Ocean Time-Series Program, the influence of atmospherically-deposited TDN on marine biogeochemistry is unknown. In this study, we measured atmospheric TDN concentrations as dissolved organic (DON) and inorganic (DIN) nitrogen (TDN = DIN + DON) in atmospheric suspended particles and wet deposition samples at the northeast of the basin during periods of the wet (August-September 2008) and dry (March-April 2009) seasons. We evaluated the potential anthropogenic N influences by measuring wind velocity and direction, size-fractionated suspended particles, chemical traces and by performing back trajectories. We found DIN and DON concentration values that ranged between 0.11 and 0.58 μg-N m-3 and 0.11-0.56 μg-N m-3 in total suspended particles samples and between 0.08 and 0.54 mg-N l-1 and 0.02-1.3 mg-N l-1 in wet deposition samples, respectively. Continental air masses increased DON and DIN concentrations in atmospheric suspended particles during the wet season. We estimate an annual TDN atmospheric deposition (wet + particles) of 3.6 × 103 ton-N year-1 and concluded that: 1) Atmospheric supply of TDN plays a key role in the C and N budget of the basin because replaces a fraction of the C (20% by induced primary production) and N (40%) removed by sediment burial, 2) present anthropogenic N could contribute to 30% of TDN atmospheric deposition in the basin, and 3) reduced DON (gas + particles) should be a significant component of bulk N deposition.

  17. Radon gas in oil and natural gas production facilities

    International Nuclear Information System (INIS)

    Chandler, W.P.

    1994-01-01

    Radon gas is a naturally occurring radionuclide that can be found in some oil and natural gas production facilities, either as a contaminant in a natural gas stream or derived from Radium dissolved in formation waters. The gas itself is not normally a health hazard, but it's decay products, which can be concentrated by plate-out or deposition as a scale in process equipment, can be a health hazard for maintenance personnel. To evaluate possible health hazards, it is necessary to monitor for naturally occurring radioactive materials (NORM) in the gas stream and in the formation water. If Radon and/or Radium is found, a monitoring programme should be initiated to comply with National or State requirements. In some instances, it has been found necessary to dispose of silt and scale materials as low level radioactive waste. 8 refs

  18. HB-Line Dissolver Dilution Flows and Dissolution Capability with Dissolver Charge Chute Cover Off

    International Nuclear Information System (INIS)

    Hallman, D.F.

    2003-01-01

    A flow test was performed in Scrap Recovery of HB-Line to document the flow available for hydrogen dilution in the dissolvers when the charge chute covers are removed. Air flow through the dissolver charge chutes, with the covers off, was measured. A conservative estimate of experimental uncertainty was subtracted from the results. After subtraction, the test showed that there is 20 cubic feet per minute (cfm) air flow through the dissolvers during dissolution with a glovebox exhaust fan operating, even with the scrubber not operating. This test also showed there is 6.6 cfm air flow through the dissolvers, after subtraction of experimental uncertainty if the scrubber and the glovebox exhaust fans are not operating. Three H-Canyon exhaust fans provide sufficient motive force to give this 6.6 cfm flow. Material charged to the dissolver will be limited to chemical hydrogen generation rates that will be greater than or equal to 25 percent of the Lower Flammability Limit (LFL) during normal operations. The H-Canyon fans will maintain hydrogen below LFL if electrical power is lost. No modifications are needed in HB-Line Scrap Recovery to ensure hydrogen is maintained less that LFL if the scrubber and glovebox exhaust fans are not operating

  19. Temporal Patterns in Dissolved Organic Carbon Composition in an Urban Lake

    Science.gov (United States)

    Hartnett, H. E.; Palta, M. M.; Grimm, N. B.; Ruhi, A.; van Shaijik, M.

    2017-12-01

    Tempe Town Lake (TTL) is a hydrologically-regulated reservoir in Tempe, Arizona. The lake has high primary production and receives dissolved organic carbon (DOC) from rainfall, storm flow, and upstream river discharge. We applied an ARIMA time-series model to a three-year period for which we have high-frequency chemistry, meteorology, and streamflow data and analyzed external (rainfall, stream flow) and internal (dissolved O2) drivers of DOC content and composition. DOC composition was represented by fluorescence-based indices (fluorescence index, humification index, freshness) related to DOC source (microbially- vs. terrestrially-derived) and reactivity DOC. Patterns in DOC concentration and composition suggest carbon cycling in the lake responds to both meteorological events and to anthropogenic activity. The fluorescence-derived DOC composition is consistent with seasonally-distinct inputs of algal- and terrestrially-derived carbon. For example, Tempe Town Lake is supersaturated in O2 over 70% of the time, suggesting the system is autotrophic and primary productivity (i.e., O2 saturation state) was the strongest driver of DOC concentration. In contrast, external drivers (rainfall pattern, streamflow) were the strongest determinants of DOC composition. Biological processes (e.g., algal growth) generate carbon in the lake during spring and summer, and high Fluorescence Index and Freshness values at this time are indicative of algal-derived material; these parameters generally decrease with rain or flow suggesting algal-derived carbon is diluted by external water inputs. During dry periods, carbon builds up on the land surface and subsequent rainfall events deliver terrestrial carbon to the lake. Further evidence that rain and streamflow deliver land-derived material are increases in the Humification Index (an indicator of terrestrial material) following rain/flow events. Our results indicate that Tempe Town Lake generates autochthonous carbon and has the capacity

  20. Investigation and modeling of Al3(Sc, Zr) precipitation strengthening in the presence of enhanced supersaturation and within Al-Cu binary alloys

    Science.gov (United States)

    Deane, Kyle

    Diffuse Al-Sc and Al-Zr alloys have been demonstrated in literature to be relatively coarsening resistant at higher temperatures when compared with commonly used precipitation strengthening alloys (e.g. 2000 series, 6000 series). However, because of a limited strengthening due to the low solubility of scandium and zirconium in aluminum, and owing to the scarcity and therefore sizeable price tag attached to scandium, little research has been done in the way of optimizing these alloys for commercial applications. With this in mind, this dissertation describes research which aims to tackle several important areas of Al-Sc-Zr research that have been yet unresolved. In Chapter 4, rapid solidification was utilized to enhance the achievable supersaturation of the alloy in an effort to increase the achievable precipitate strengthening. In Chapter 5, Additive Friction Stir processing (AFS), a novel method of mechanically combining materials without melting, was employed in an attempt to pass the benefits of supersaturation from melt spun ribbon into a more structurally useful bulk material. In Chapter 6, a Matlab program written to predict precipitate nucleation, growth, and coarsening with a modified Kampmann and Wagner Numerical (KWN) model, was used to predict heat treatment regimens for more efficient strengthening. Those predictions were then tested experimentally to test the validity of the results. And lastly, in Chapter 7, the effect of zirconium on Al-Cu secondary precipitates was studied in an attempt to increase their thermal stability, as much higher phase fractions of Al-Cu precipitates are achievable than Al-Zr precipitates.

  1. Gas turbine

    International Nuclear Information System (INIS)

    Yang, Ok Ryong

    2004-01-01

    This book introduces gas turbine cycle explaining general thing of gas turbine, full gas turbine cycle, Ericson cycle and Brayton cycle, practical gas turbine cycle without pressure loss, multiaxial type gas turbine cycle and special gas turbine cycle, application of basic theory on a study on suction-cooling gas turbine cycle with turbo-refrigerating machine using the bleed air, and general performance characteristics of the suction-cooling gas turbine cycle combined with absorption-type refrigerating machine.

  2. Dissolve energy obesity by energy diet

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jung Heum [Sunmoon University, Asan (Korea)

    2000-07-01

    Every organism takes needed materials or energy from outside and excretes unessential things to outside. This is called a metabolism or energy metabolism. Calculating the amount of energy consumed by human in the world by converting to the amount of metabolism of an animal to survive, the weight of a human being is corresponding to an animal with a weigh of 40 ton. Human beings can find a solution to dissolve energy obesity or can maintain a massive status by finding a new energy source in the universe.

  3. Effect of Greenhouse Gases Dissolved in Seawater

    Directory of Open Access Journals (Sweden)

    Shigeki Matsunaga

    2015-12-01

    Full Text Available A molecular dynamics simulation has been performed on the greenhouse gases carbon dioxide and methane dissolved in a sodium chloride aqueous solution, as a simple model of seawater. A carbon dioxide molecule is also treated as a hydrogen carbonate ion. The structure, coordination number, diffusion coefficient, shear viscosity, specific heat, and thermal conductivity of the solutions have been discussed. The anomalous behaviors of these properties, especially the negative pressure dependence of thermal conductivity, have been observed in the higher-pressure region.

  4. Photomineralization and photomethanification of dissolved organic matter in Saguenay River surface water

    Science.gov (United States)

    Zhang, Y.; Xie, H.

    2015-11-01

    photobleaching under air saturation but increased exponentially under suboxic conditions. Spectrally, AQYCH4 decreased sequentially from UVB to UVA to VIS, with UVB being more efficient under suboxic conditions than under oxic conditions. On a depth-integrated basis, VIS prevailed over UVB in controlling CH4 photoproduction under air saturation while the opposite held true under O2-deficiency. An addition of micromolar levels of dissolved dimethyl sulfide (DMS) substantially increased CH4 photoproduction, particularly under O2-deficiency; DMS at nanomolar ambient concentrations in surface oceans is, however, unlikely a significant CH4 precursor. Results from this study suggest that CDOM-based CH4 photoproduction only marginally contributes to the CH4 supersaturation in modern surface oceans and to both the modern and Archean atmospheric CH4 budgets, but that the photochemical term can be comparable to microbial CH4 oxidation in modern oxic oceans. Our results also suggest that anoxic microniches in particulate organic matter and phytoplankton cells containing elevated concentrations of precursors of the methyl radical such as DMS may provide potential hotspots for CH4 photoproduction.

  5. Distribution of dissolved carbohydrates and uronic acids in a tropical estuary, India

    Digital Repository Service at National Institute of Oceanography (India)

    Khodse, V.B.; Bhosle, N.B.; Matondkar, S.G.P.

    , concentrations of total dissolved carbohydrate (TCHO), dissolved polysaccharide (PCHO), dissolved monosaccharide (MCHO), and dissolved uronic acid (URA) were measured in the Mandovi estuary, west coast of India during the monsoon and premonsoon seasons...

  6. DISSOLVED CONCENTRATION LIMITS OF RADIOACTIVE ELEMENTS

    Energy Technology Data Exchange (ETDEWEB)

    NA

    2004-11-22

    The purpose of this study is to evaluate dissolved concentration limits (also referred to as solubility limits) of elements with radioactive isotopes under probable repository conditions, based on geochemical modeling calculations using geochemical modeling tools, thermodynamic databases, field measurements, and laboratory experiments. The scope of this modeling activity is to predict dissolved concentrations or solubility limits for 14 elements with radioactive isotopes (actinium, americium, carbon, cesium, iodine, lead, neptunium, plutonium, protactinium, radium, strontium, technetium, thorium, and uranium) important to calculated dose. Model outputs for uranium, plutonium, neptunium, thorium, americium, and protactinium are in the form of tabulated functions with pH and log (line integral) CO{sub 2} as independent variables, plus one or more uncertainty terms. The solubility limits for the remaining elements are either in the form of distributions or single values. The output data from this report are fundamental inputs for Total System Performance Assessment for the License Application (TSPA-LA) to determine the estimated release of these elements from waste packages and the engineered barrier system. Consistent modeling approaches and environmental conditions were used to develop solubility models for all of the actinides. These models cover broad ranges of environmental conditions so that they are applicable to both waste packages and the invert. Uncertainties from thermodynamic data, water chemistry, temperature variation, and activity coefficients have been quantified or otherwise addressed.

  7. Ancient dissolved methane in inland waters at low concentrations revealed by a new collection method for radiocarbon (^{14}C) analysis

    Science.gov (United States)

    Dean, Joshua F.; Billett, Michael F.; Murray, Callum; Garnett, Mark H.

    2017-04-01

    Methane (CH4) is a powerful greenhouse gas and is released to the atmosphere from freshwater systems in numerous biomes globally. Radiocarbon (14C) analysis of methane can provide unique information about its age, source and rate of cycling in natural environments. Methane is often released from aquatic sediments in bubbles (ebullition), but dissolved methane is also present in lakes and streams at lower concentrations, and may not be of the same age or source. Obtaining sufficient non-ebullitive aquatic methane for 14C analysis remains a major technical challenge. Previous studies have shown that freshwater methane, in both dissolved and ebullitive form, can be significantly older than other forms of aquatic carbon (C), and it is therefore important to characterise this part of the terrestrial C balance. We present a novel method to capture sufficient amounts of dissolved methane from freshwater environments for 14C analysis by circulating water across a hydrophobic, gas-permeable membrane and collecting the methane in a large collapsible vessel. The results of laboratory and field tests show that reliable dissolved δ13CH4 and 14CH4 samples can be readily collected over short time periods (˜4 to 24 hours), at relatively low cost and from a variety of surface water types. The initial results further support previous findings that dissolved methane can be significantly older than other forms of aquatic C, especially in organic-rich catchments, and is currently unaccounted for in many terrestrial C balances and models. This method is suitable for use in remote locations, and could potentially be used to detect the leakage of unique 14CH4 signatures from point sources into waterways, e.g. coal seam gas and landfill gas.

  8. Temperature dependence of photodegradation of dissolved organic matter to dissolved inorganic carbon and particulate organic carbon

    Czech Academy of Sciences Publication Activity Database

    Porcal, Petr; Dillon, P. J.; Molot, L. A.

    2015-01-01

    Roč. 10, č. 6 (2015), e0128884 E-ISSN 1932-6203 R&D Projects: GA ČR(CZ) GAP503/12/0781; GA ČR(CZ) GA15-09721S Institutional support: RVO:60077344 Keywords : dissolved organic carbon * particulate organic carbon * photodegradation * temperature Subject RIV: DA - Hydrology ; Limnology Impact factor: 3.057, year: 2015

  9. Exhaust gas clean up process

    Science.gov (United States)

    Walker, R.J.

    1988-06-16

    A method of cleaning an exhaust gas containing particulates, SO/sub 2/ and NO/sub x/ is described. The method involves prescrubbing with water to remove HCl and most of the particulates, scrubbing with an aqueous absorbent containing a metal chelate and dissolved sulfite salt to remove NO/sub x/ and SO/sub 2/, and regenerating the absorbent solution by controlled heating, electrodialysis and carbonate salt addition. The NO/sub x/ is removed as N/sub 2/ gas or nitrogen sulfonate ions and the oxides of sulfur are removed as a valuable sulfate salt. 4 figs.

  10. Determination of dissolved methane in natural waters using headspace analysis with cavity ring-down spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Roberts, Hannah M.; Shiller, Alan M., E-mail: alan.shiller@usm.edu

    2015-01-26

    Highlights: • A method for determining low nanomolar dissolved CH{sub 4} was developed. • The methane detection utilizes cavity ring-down spectroscopy (CRDS). • Use of CRDS requires less time, materials and labor than typical of GC analysis. • Relative standard deviations of ∼4% were achieved at low nM CH{sub 4}. • Applications to seawater and river water are presented. - Abstract: Methane (CH{sub 4}) is the third most abundant greenhouse gas (GHG) but is vastly understudied in comparison to carbon dioxide. Sources and sinks to the atmosphere vary considerably in estimation, including sources such as fresh and marine water systems. A new method to determine dissolved methane concentrations in discrete water samples has been evaluated. By analyzing an equilibrated headspace using laser cavity ring-down spectroscopy (CRDS), low nanomolar dissolved methane concentrations can be determined with high reproducibility (i.e., 0.13 nM detection limit and typical 4% RSD). While CRDS instruments cost roughly twice that of gas chromatographs (GC) usually used for methane determination, the process presented herein is substantially simpler, faster, and requires fewer materials than GC methods. Typically, 70-mL water samples are equilibrated with an equivalent amount of zero air in plastic syringes. The equilibrated headspace is transferred to a clean, dry syringe and then drawn into a Picarro G2301 CRDS analyzer via the instrument’s pump. We demonstrate that this instrument holds a linear calibration into the sub-ppmv methane concentration range and holds a stable calibration for at least two years. Application of the method to shipboard dissolved methane determination in the northern Gulf of Mexico as well as river water is shown. Concentrations spanning nearly six orders of magnitude have been determined with this method.

  11. A flow injection analyser conductometric coupled system for the field analysis of free dissolved CO{sub 2} and total dissolved inorganic carbon in natural waters

    Energy Technology Data Exchange (ETDEWEB)

    Martinotti, Valter; Balordi, Marcella; Ciceri, Giovanni [RSE SpA - Environment and Sustainable Development Department, Milan (Italy)

    2012-05-15

    A flow injection analyser coupled with a gas diffusion membrane and a conductometric microdetector was adapted for the field analysis of natural concentrations of free dissolved CO{sub 2} and dissolved inorganic carbon in natural waters and used in a number of field campaigns for marine water monitoring. The dissolved gaseous CO{sub 2} presents naturally, or that generated by acidification of the sample, is separated by diffusion using a hydrophobic semipermeable gas porous membrane, and the permeating gas is incorporated into a stream of deionised water and measured by means of an electrical conductometric microdetector. In order to make the system suitable and easy to use for in-field measurements aboard oceanographic ships, the single components of the analyser were compacted into a robust and easy to use system. The calibration of the system is carried out by using standard solutions of potassium bicarbonate at two concentration ranges. Calibration and sample measurements are carried out inside a temperature-constant chamber at 25 C and in an inert atmosphere (N{sub 2}). The detection and quantification limits of the method, evaluated as 3 and 10 times the standard deviation of a series of measurements of the matrix solution were 2.9 and 9.6 {mu}mol/kg of CO{sub 2}, respectively. Data quality for dissolved inorganic carbon was checked with replicate measurements of a certified reference material (A. Dickson, Scripps Institution of Oceanography, University of California, San Diego), both accuracy and repeatability were -3.3% and 10%, respectively. Optimization, performance qualification of the system and its application in various natural water samples are reported and discussed. In the future, the calibration step will be operated automatically in order to improve the analytical performance and the applicability will be increased in the course of experimental surveys carried out both in marine and freshwater ecosystems. Considering the present stage of

  12. Mechanism for calcite dissolution and its contribution to development of reservoir porosity and permeability in the Kela 2 gas field,Tarim Basin,China

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    This study is undertaken to understand how calcite precipitation and dissolution contributes to depth-related changes in porosity and permeability of gas-bearing sandstone reservoirs in the Kela 2 gas field of the Tarim Basin, Northwestern China. Sandstone samples and pore water samples are col-lected from well KL201 in the Tarim Basin. Vertical profiles of porosity, permeability, pore water chem-istry, and the relative volume abundance of calcite/dolomite are constructed from 3600 to 4000 m below the ground surface within major oil and gas reservoir rocks. Porosity and permeability values are in-versely correlated with the calcite abundance, indicating that calcite dissolution and precipitation may be controlling porosity and permeability of the reservoir rocks. Pore water chemistry exhibits a sys-tematic variation from the Na2SO4 type at the shallow depth (3600-3630 m), to the NaHCO3 type at the intermediate depth (3630―3695 m),and to the CaCl2 type at the greater depth (3728―3938 m). The geochemical factors that control the calcite solubility include pH, temperature, pressure, Ca2+ concen-tration, the total inorganic carbon concentration (ΣCO2), and the type of pore water. Thermodynamic phase equilibrium and mass conservation laws are applied to calculate the calcite saturation state as a function of a few key parameters. The model calculation illustrates that the calcite solubility is strongly dependent on the chemical composition of pore water, mainly the concentration difference between the total dissolved inorganic carbon and dissolved calcium concentration (i.e., [ΣCO2] -[Ca2+]). In the Na2SO4 water at the shallow depth, this index is close to 0, pore water is near the calcite solubility. Calcite does not dissolve or precipitate in significant quantities. In the NaHCO3 water at the intermedi-ate depth, this index is greater than 0, and pore water is supersaturated with respect to calcite. Massive calcite precipitation was observed at this depth

  13. Effect of dissolved oxygen on SCC of LP turbine steel

    International Nuclear Information System (INIS)

    Maeng, W. Y.; Lee, J. H.; Kim, W. C.

    2002-01-01

    Slow Strain Rate Tests (SSRT) were carried out to investigate the effect of dissolved oxygen on Stress Corrosion Cracking (SCC) susceptibility of 3.5NiCrMoV steels used in discs of Low-Pressure (LP) steam turbines in electric power generating plants. The influence of dissolved oxygen on cracking in water was studied; for this purpose, specimens were strained to fracture at 150 .deg. C in water environments with various amounts of dissolved oxygen. The maximum elongation of the turbine steel decreased with increasing dissolved oxygen. Dissolved oxygen significantly affected the SCC susceptibility of turbine steel in water. The increase of the SCC susceptibility of the turbine steel in a higher dissolved oxygen environment is due to the non protectiveness of the oxide layer of the turbine steel surface and the increase of corrosion current

  14. Gas-liquid nucleation at large metastability: unusual features and a new formalism

    Science.gov (United States)

    Santra, Mantu; Singh, Rakesh S.; Bagchi, Biman

    2011-03-01

    to understand the large numerical discrepancy between simulation predictions and experimental results, we carried out a study of the dependence on the range of intermolecular interactions of both the surface tension of an equilibrium planar gas-liquid interface and the free energy barrier of nucleation. Both are found to depend significantly on the range of interaction for the Lennard-Jones potential, both in two and three dimensions. The value of surface tension and also the free energy difference between the gas and the liquid phase increase significantly and converge only when the range of interaction is extended beyond 6-7 molecular diameters. We find, with the full range of interaction potential, that the surface tension shows only a weak dependence on supersaturation, so the reason for the breakdown of CNT (with simulated values of surface tension and free energy gap) cannot be attributed to the supersaturation dependence of surface tension. This remains an unsettled issue at present because of the use of the value of surface tension obtained at coexistence.

  15. Radiation-chemical disinfection of dissolved impurities and environmental protection

    International Nuclear Information System (INIS)

    Petrukhin, N.V.; Putilov, A.V.

    1986-01-01

    Radiation-chemical neutralization of dissolved toxic impurities formed in the production processes of different materials, while modern plants being in use, is considered. For the first time the processes of deep industrial waste detoxication and due to this peculiarities of practically thorough neutralization of dissolved toxic impurities are considered. Attention is paid to devices and economic factors of neutralization of dissolved toxic impurities. The role of radiation-chemical detoxication for environment protection is considered

  16. Characterization of Urban Runoff Pollution between Dissolved and Particulate Phases

    OpenAIRE

    Wei, Zhang; Simin, Li; Fengbing, Tang

    2013-01-01

    To develop urban stormwater management effectively, characterization of urban runoff pollution between dissolved and particulate phases was studied by 12 rainfall events monitored for five typical urban catchments. The average event mean concentration (AEMC) of runoff pollutants in different phases was evaluated. The AEMC values of runoff pollutants in different phases from urban roads were higher than the ones from urban roofs. The proportions of total dissolved solids, total dissolved nitr...

  17. Coal beneficiation by gas agglomeration

    Science.gov (United States)

    Wheelock, Thomas D.; Meiyu, Shen

    2003-10-14

    Coal beneficiation is achieved by suspending coal fines in a colloidal suspension of microscopic gas bubbles in water under atmospheric conditions to form small agglomerates of the fines adhered by the gas bubbles. The agglomerates are separated, recovered and resuspended in water. Thereafter, the pressure on the suspension is increased above atmospheric to deagglomerate, since the gas bubbles are then re-dissolved in the water. During the deagglomeration step, the mineral matter is dispersed, and when the pressure is released, the coal portion of the deagglomerated gas-saturated water mixture reagglomerates, with the small bubbles now coming out of the solution. The reagglomerate can then be separated to provide purified coal fines without the mineral matter.

  18. Dissolved Concentration Limits of Radioactive Elements

    International Nuclear Information System (INIS)

    Y. Chen; E.R. Thomas; F.J. Pearson; P.L. Cloke; T.L. Steinborn; P.V. Brady

    2003-01-01

    The purpose of this study is to evaluate dissolved concentration limits (also referred to as solubility limits) of radioactive elements under possible repository conditions, based on geochemical modeling calculations using geochemical modeling tools, thermodynamic databases, and measurements made in laboratory experiments and field work. The scope of this modeling activity is to predict dissolved concentrations or solubility limits for 14 radioactive elements (actinium, americium, carbon, cesium, iodine, lead, neptunium, plutonium, protactinium, radium, strontium, technetium, thorium, and uranium), which are important to calculated dose. Model outputs are mainly in the form of look-up tables plus one or more uncertainty terms. The rest are either in the form of distributions or single values. The results of this analysis are fundamental inputs for total system performance assessment to constrain the release of these elements from waste packages and the engineered barrier system. Solubilities of plutonium, neptunium, uranium, americium, actinium, thorium, protactinium, lead, and radium have been re-evaluated using the newly updated thermodynamic database (Data0.ymp.R2). For all of the actinides, identical modeling approaches and consistent environmental conditions were used to develop solubility models in this revision. These models cover broad ranges of environmental conditions so that they are applicable to both waste packages and the invert. Uncertainties from thermodynamic data, water chemistry, temperature variation, activity coefficients, and selection of solubility controlling phase have been quantified or otherwise addressed. Moreover, a new blended plutonium solubility model has been developed in this revision, which gives a mean solubility that is three orders of magnitude lower than the plutonium solubility model used for the Total System Performance Assessment for the Site Recommendation. Two alternative neptunium solubility models have also been

  19. DISSOLVED CONCENTRATION LIMITS OF RADIOACTIVE ELEMENTS

    International Nuclear Information System (INIS)

    P. Bernot

    2005-01-01

    The purpose of this study is to evaluate dissolved concentration limits (also referred to as solubility limits) of elements with radioactive isotopes under probable repository conditions, based on geochemical modeling calculations using geochemical modeling tools, thermodynamic databases, field measurements, and laboratory experiments. The scope of this activity is to predict dissolved concentrations or solubility limits for elements with radioactive isotopes (actinium, americium, carbon, cesium, iodine, lead, neptunium, plutonium, protactinium, radium, strontium, technetium, thorium, and uranium) relevant to calculated dose. Model outputs for uranium, plutonium, neptunium, thorium, americium, and protactinium are provided in the form of tabulated functions with pH and log fCO 2 as independent variables, plus one or more uncertainty terms. The solubility limits for the remaining elements are either in the form of distributions or single values. Even though selection of an appropriate set of radionuclides documented in Radionuclide Screening (BSC 2002 [DIRS 160059]) includes actinium, transport of Ac is not modeled in the total system performance assessment for the license application (TSPA-LA) model because of its extremely short half-life. Actinium dose is calculated in the TSPA-LA by assuming secular equilibrium with 231 Pa (Section 6.10); therefore, Ac is not analyzed in this report. The output data from this report are fundamental inputs for TSPA-LA used to determine the estimated release of these elements from waste packages and the engineered barrier system. Consistent modeling approaches and environmental conditions were used to develop solubility models for the actinides discussed in this report. These models cover broad ranges of environmental conditions so they are applicable to both waste packages and the invert. Uncertainties from thermodynamic data, water chemistry, temperature variation, and activity coefficients have been quantified or otherwise

  20. Dissolved Concentration Limits of Radioactive Elements

    Energy Technology Data Exchange (ETDEWEB)

    Y. Chen; E.R. Thomas; F.J. Pearson; P.L. Cloke; T.L. Steinborn; P.V. Brady

    2003-06-20

    The purpose of this study is to evaluate dissolved concentration limits (also referred to as solubility limits) of radioactive elements under possible repository conditions, based on geochemical modeling calculations using geochemical modeling tools, thermodynamic databases, and measurements made in laboratory experiments and field work. The scope of this modeling activity is to predict dissolved concentrations or solubility limits for 14 radioactive elements (actinium, americium, carbon, cesium, iodine, lead, neptunium, plutonium, protactinium, radium, strontium, technetium, thorium, and uranium), which are important to calculated dose. Model outputs are mainly in the form of look-up tables plus one or more uncertainty terms. The rest are either in the form of distributions or single values. The results of this analysis are fundamental inputs for total system performance assessment to constrain the release of these elements from waste packages and the engineered barrier system. Solubilities of plutonium, neptunium, uranium, americium, actinium, thorium, protactinium, lead, and radium have been re-evaluated using the newly updated thermodynamic database (Data0.ymp.R2). For all of the actinides, identical modeling approaches and consistent environmental conditions were used to develop solubility models in this revision. These models cover broad ranges of environmental conditions so that they are applicable to both waste packages and the invert. Uncertainties from thermodynamic data, water chemistry, temperature variation, activity coefficients, and selection of solubility controlling phase have been quantified or otherwise addressed. Moreover, a new blended plutonium solubility model has been developed in this revision, which gives a mean solubility that is three orders of magnitude lower than the plutonium solubility model used for the Total System Performance Assessment for the Site Recommendation. Two alternative neptunium solubility models have also been

  1. DISSOLVED CONCENTRATION LIMITS OF RADIOACTIVE ELEMENTS

    Energy Technology Data Exchange (ETDEWEB)

    P. Bernot

    2005-07-13

    The purpose of this study is to evaluate dissolved concentration limits (also referred to as solubility limits) of elements with radioactive isotopes under probable repository conditions, based on geochemical modeling calculations using geochemical modeling tools, thermodynamic databases, field measurements, and laboratory experiments. The scope of this activity is to predict dissolved concentrations or solubility limits for elements with radioactive isotopes (actinium, americium, carbon, cesium, iodine, lead, neptunium, plutonium, protactinium, radium, strontium, technetium, thorium, and uranium) relevant to calculated dose. Model outputs for uranium, plutonium, neptunium, thorium, americium, and protactinium are provided in the form of tabulated functions with pH and log fCO{sub 2} as independent variables, plus one or more uncertainty terms. The solubility limits for the remaining elements are either in the form of distributions or single values. Even though selection of an appropriate set of radionuclides documented in Radionuclide Screening (BSC 2002 [DIRS 160059]) includes actinium, transport of Ac is not modeled in the total system performance assessment for the license application (TSPA-LA) model because of its extremely short half-life. Actinium dose is calculated in the TSPA-LA by assuming secular equilibrium with {sup 231}Pa (Section 6.10); therefore, Ac is not analyzed in this report. The output data from this report are fundamental inputs for TSPA-LA used to determine the estimated release of these elements from waste packages and the engineered barrier system. Consistent modeling approaches and environmental conditions were used to develop solubility models for the actinides discussed in this report. These models cover broad ranges of environmental conditions so they are applicable to both waste packages and the invert. Uncertainties from thermodynamic data, water chemistry, temperature variation, and activity coefficients have been quantified or

  2. Dissolved pesticides, dissolved organic carbon, and water-quality characteristics in selected Idaho streams, April--December 2010

    Science.gov (United States)

    Reilly, Timothy J.; Smalling, Kelly L.; Wilson, Emma R.; Battaglin, William A.

    2012-01-01

    Water-quality samples were collected from April through December 2010 from four streams in Idaho and analyzed for a suite of pesticides, including fungicides, by the U.S. Geological Survey. Water samples were collected from two agricultural and two nonagricultural (control) streams approximately biweekly from the beginning of the growing season (April) through the end of the calendar year (December). Samples were analyzed for 90 pesticides using gas chromatography/mass spectrometry. Twenty-three pesticides, including 8 fungicides, 10 herbicides, 3 insecticides, and 2 pesticide degradates, were detected in 45 water samples. The most frequently detected compounds in the two agricultural streams and their detection frequencies were metolachlor, 96 percent; azoxystrobin, 79 percent; boscalid, 79 percent; atrazine, 46 percent; pendimethalin, 33 percent; and trifluralin, 33 percent. Dissolved-pesticide concentrations ranged from below instrumental limits of detection (0.5-1.0 nanograms per liter) to 771 nanograms per liter (hexazinone). The total number of pesticides detected in any given water sample ranged from 0 to 11. Only three pesticides (atrazine, fipronil, and simazine) were detected in samples from the control streams during the sampling period.

  3. The size distribution of dissolved uranium in natural waters

    International Nuclear Information System (INIS)

    Mann, D.K.; Wong, G.T.F.

    1987-01-01

    The size distribution of dissolved uranium in natural waters is poorly known. Some fraction of dissolved uranium is known to associate with organic matter which had a wide range of molecular weights. The presence of inorganic colloidal uranium has not been reported. Ultrafiltration has been used to quantify the size distribution of a number of elements, such as dissolved organic carbon, selenium, and some trace metals, in both the organic and/or the inorganic forms. The authors have applied this technique to dissolved uranium and the data are reported here

  4. Impact of solute concentration on the electrocatalytic conversion of dissolved gases in buffered solutions

    KAUST Repository

    Shinagawa, Tatsuya

    2015-04-24

    To maintain local pH levels near the electrode during electrochemical reactions, the use of buffer solutions is effective. Nevertheless, the critical effects of the buffer concentration on electrocatalytic performances have not been discussed in detail. In this study, two fundamental electrochemical reactions, oxygen reduction reaction (ORR) and hydrogen oxidation reaction (HOR), on a platinum rotating disk electrode are chosen as model gas-related aqueous electrochemical reactions at various phosphate concentrations. Our detailed investigations revealed that the kinetic and limiting diffusion current densities for both the ORR and HOR logarithmically decrease with increasing solute concentration (log|jORR|=-0.39c+0.92,log|jHOR|=-0.35c+0.73). To clarify the physical aspects of this phenomenon, the electrolyte characteristics are addressed: with increasing phosphate concentration, the gas solubility decrease, the kinematic viscosity of the solution increase and the diffusion coefficient of the dissolved gases decrease. The simulated limiting diffusion currents using the aforementioned parameters match the measured ones very well (log|jORR|=-0.43c+0.99,log|jHOR|=-0.40c+0.54), accurately describing the consequences of the electrolyte concentration. These alterations of the electrolyte properties associated with the solute concentration are universally applicable to other aqueous gas-related electrochemical reactions because the currents are purely determined by mass transfer of the dissolved gases. © 2015 The Authors.

  5. Retail promotions and perceptions of R.J. Reynolds' novel dissolvable tobacco in a US test market.

    Science.gov (United States)

    Romito, Laura M; Saxton, M Kim; Coan, Lorinda L; Christen, Arden G

    2011-05-15

    With declining cigarette sales, tobacco manufacturers have been developing and marketing new smokeless products, such as R. J. Reynolds' dissolvable tobacco, Camel Sticks, Strips and Orbs. This study assessed the availability, price and point-of-purchase promotional strategies for Camel Dissolvables, and investigated consumer awareness, interest and perception of these products in the Indiana test market. An exploratory retail audit of point-of-purchase promotions was conducted in a random sample of retailers from 6 store categories (n = 81) in the test market area. Data included: store type, location, product placement, forms/flavors carried, price, types and locations of advertisements and promotions, and ad messages. An Awareness-Attitude-Usage (AAU) survey was used to gauge consumer awareness and knowledge of tobacco products including Camel Dissolvables. Respondents were shown promotional materials from a package onsert and perceptions and interest in the Camel Dissolvables were assessed. An Intended Target Survey (ITS) compared subjects' perceptions of ad targets for several non-tobacco products, as well as Camel Snus, Camel No. 9 and Camel Dissolvables. Respondents were asked to identify each ad's intended target category, perceived targetedness, and purchase intent. The products were carried by 46% of stores, most frequently gas stations (100%) and convenience stores (75%). They were shelved near smokeless tobacco (70%), cigarettes (25%) or candy (5%). Prices ranged from $3.59 -$4.19 per package; most stores carried at least 1 promotional item. Ad messages included: "Dissolvable Tobacco" (60%). "Free Trial" (24%), "Special Price" (24%), "What's Your Style?" (22%). At 14% of stores, free trial packs of Camel Dissolvables were offered with another Camel purchase. Awareness was reported by 42% of respondents (n = 243), and trial by 3%. Consumer interest was very low, but younger respondents ( 40 years, p targeted smokers. Current retail promotional strategies

  6. Retail promotions and perceptions of R.J. Reynolds' novel dissolvable tobacco in a US test market

    Directory of Open Access Journals (Sweden)

    Coan Lorinda L

    2011-05-01

    Full Text Available Abstract Background With declining cigarette sales, tobacco manufacturers have been developing and marketing new smokeless products, such as R. J. Reynolds' dissolvable tobacco, Camel Sticks, Strips and Orbs. This study assessed the availability, price and point-of-purchase promotional strategies for Camel Dissolvables, and investigated consumer awareness, interest and perception of these products in the Indiana test market. Methods An exploratory retail audit of point-of-purchase promotions was conducted in a random sample of retailers from 6 store categories (n = 81 in the test market area. Data included: store type, location, product placement, forms/flavors carried, price, types and locations of advertisements and promotions, and ad messages. An Awareness-Attitude-Usage (AAU survey was used to gauge consumer awareness and knowledge of tobacco products including Camel Dissolvables. Respondents were shown promotional materials from a package onsert and perceptions and interest in the Camel Dissolvables were assessed. An Intended Target Survey (ITS compared subjects' perceptions of ad targets for several non-tobacco products, as well as Camel Snus, Camel No. 9 and Camel Dissolvables. Respondents were asked to identify each ad's intended target category, perceived targetedness, and purchase intent. Results The products were carried by 46% of stores, most frequently gas stations (100% and convenience stores (75%. They were shelved near smokeless tobacco (70%, cigarettes (25% or candy (5%. Prices ranged from $3.59 -$4.19 per package; most stores carried at least 1 promotional item. Ad messages included: "Dissolvable Tobacco" (60%. "Free Trial" (24%, "Special Price" (24%, "What's Your Style?" (22%. At 14% of stores, free trial packs of Camel Dissolvables were offered with another Camel purchase. Awareness was reported by 42% of respondents (n = 243, and trial by 3%. Consumer interest was very low, but younger respondents ( 40 years, p Conclusions

  7. Release of Dissolved CO2 from Water in Laboratory Porous Media Following Rapid Depressurization

    Science.gov (United States)

    Crews, J. B.; Cooper, C. A.

    2011-12-01

    A bench-top laboratory study is undertaken to investigate the effects of seismic shocks on brine aquifers into which carbon dioxide has been injected for permanent storage. Long-term storage in deep saline aquifers has been proposed and studied as one of the most viable near-term options for sequestering fossil fuel-derived carbon dioxide from the atmosphere to curb anthropogenic climate change. Upon injection into the subsurface, it is expected that CO2, as either a gas or supercritical fluid, will mix convectively with the formation water. The possibility exists, however, that dissolved CO2 will come out of solution as a result of an earthquake. The effect is similar to that of slamming an unsealed container of carbonated beverage on a table; previously dissolved CO2 precipitates, forms bubbles, and rises due to buoyancy. In this study, we measure the change in gas-phase CO2 concentration as a function of the magnitude of the shock and the initial concentration of CO2. In addition, we investigate and seek to characterize the nucleation and transport of CO2 bubbles in a porous medium after a seismic shock. Experiments are conducted using a Hele-Shaw cell and a CCD camera to quantify the fraction of dissolved CO2 that comes out of solution as a result of a sharp mechanical impulse. The data are used to identify and constrain the conditions under which CO2 comes out of solution and, further, to understand the end-behavior of the precipitated gas-phase CO2 as it moves through or is immobilized in a porous medium.

  8. Influence of the Al distribution on the structure, elastic properties, and phase stability of supersaturated Ti1-xAlxN

    International Nuclear Information System (INIS)

    Mayrhofer, P. H.; Music, D.; Schneider, J. M.

    2006-01-01

    Ti 1-x Al x N films and/or their alloys are employed in many industrial applications due to their excellent mechanical and thermal properties. Synthesized by plasma-assisted vapor deposition, Ti 1-x Al x N is reported to crystallize in the cubic NaCl (c) structure for AlN mole fractions below 0.4-0.91, whereas at larger Al contents the hexagonal ZnS-wurtzite (w) structure is observed. Here we use ab initio calculations to analyze the effect of composition and Al distribution on the metal sublattice on phase stability, structure, and elastic properties of c-Ti 1-x Al x N and w-Ti 1-x Al x N. We show that the phase stability of supersaturated c-Ti 1-x Al x N not only depends on the chemical composition but also on the Al distribution of the metal sublattice. An increase of the metastable solubility limit of AlN in c-Ti 1-x Al x N from 0.64 to 0.74 is obtained by decreasing the number of Ti-Al bonds. This can be understood by considering the Al distribution induced changes of the electronic structure, bond energy, and configurational entropy. This may in part explain the large variation of the metastable solubility limit reported in the literature

  9. US crude oil, natural gas, and natural gas liquids reserves 1996 annual report

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1997-12-01

    The EIA annual reserves report series is the only source of comprehensive domestic proved reserves estimates. This publication is used by the Congress, Federal and State agencies, industry, and other interested parties to obtain accurate estimates of the Nation`s proved reserves of crude oil, natural gas, and natural gas liquids. These data are essential to the development, implementation, and evaluation of energy policy and legislation. This report presents estimates of proved reserves of crude oil, natural gas, and natural gas liquids as of December 31, 1996, as well as production volumes for the US and selected States and State subdivisions for the year 1996. Estimates are presented for the following four categories of natural gas: total gas (wet after lease separation), nonassociated gas and associated-dissolved gas (which are the two major types of wet natural gas), and total dry gas (wet gas adjusted for the removal of liquids at natural gas processing plants). In addition, reserve estimates for two types of natural gas liquids, lease condensate and natural gas plant liquids, are presented. Also included is information on indicated additional crude oil reserves and crude oil, natural gas, and lease condensate reserves in nonproducing reservoirs. A discussion of notable oil and gas exploration and development activities during 1996 is provided. 21 figs., 16 tabs.

  10. U.S. crude oil, natural gas, and natural gas liquids reserves 1995 annual report

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1996-11-01

    The EIA annual reserves report series is the only source of comprehensive domestic proved reserves estimates. This publication is used by the Congress, Federal and State agencies, industry, and other interested parties to obtain accurate estimates of the Nation`s proved reserves of crude oil, natural gas, and natural gas liquids. These data are essential to the development, implementation, and evaluation of energy policy and legislation. This report presents estimates of proved reserves of crude oil, natural gas, and natural gas liquids as of December 31, 1995, as well as production volumes for the US and selected States and State subdivisions for the year 1995. Estimates are presented for the following four categories of natural gas: total gas (wet after lease separation), nonassociated gas and associated-dissolved gas (which are the two major types of wet natural gas), and total dry gas (wet gas adjusted for the removal of liquids at natural gas processing plants). In addition, reserve estimates for two types of natural gas liquids, lease condensate and natural gas plant liquids, are presented. Also included is information on indicated additional crude oil reserves and crude oil, natural gas, and lease condensate reserves in nonproducing reservoirs. A discussion of notable oil and gas exploration and development activities during 1995 is provided. 21 figs., 16 tabs.

  11. Gas capture and rare gas retention by accreting planets in the solar nebula

    International Nuclear Information System (INIS)

    Mizuno, H.; Nakazawa, K.; Hayashi, C.

    1982-01-01

    In this paper, the physico-chemical effects of the nebula gas on the planets are reviewed from a standpoint of planetary formation in the solar nebula. The proto-Earth growing in the nebula was surrounded by a primordial atmosphere with a solar chemical composition and solar isotopic composition. When the mass of the proto-Earth was greater than 0.3 times the present Earth mass, the surface was molten because of the blanketing effect of the atmosphere. Therefore, the primordial rare gases contained in the primordial atmosphere dissolved into the molten Earth material without fractionation and in particular the dissolved neon is expected to be conserved in the present Earth material. Hence, if dissolved neon with a solar isotopic ratio is discovered in the Earth material, it will indicate that the Earth was formed in the nebula and that the dissolved rare gases were one of the sources which degassed to form the present atmosphere. (author)

  12. CO2 supersaturation and net heterotrophy in a tropical estuary (Cochin, India): Influence of anthropogenic effect - Carbon dynamics in tropical estuary

    Digital Repository Service at National Institute of Oceanography (India)

    Gupta, G.V.M.; Thottathil, S.D.; Balachandran, K.K.; Madhu, N.V.; Madeswaran, P.; Nair, S.

    of pCO sub(2) (up to 6000 mu atm) and CO sub(2) effluxes (up to 274 mmolC m sup(-2) d sup(-1)) especially during monsoon. A first-order estimate of the carbon mass balance shows that net production of dissolved inorganic carbon is an order of magnitude...

  13. Geochemical evidence of water-soluble gas accumulation in the Weiyuan gas field, Sichuan Basin

    Directory of Open Access Journals (Sweden)

    Shengfei Qin

    2016-01-01

    Full Text Available At present, there are several different opinions on the formation process of the Weiyuan gas field in the Sichuan Basin and the source of its natural gas. In view of the fact that the methane carbon isotope of the natural gas in the Weiyuan gas field is abnormally heavy, the geologic characteristics of gas reservoirs and the geochemical characteristics of natural gas were first analyzed. In the Weiyuan gas field, the principal gas reservoirs belong to Sinian Dengying Fm. The natural gas is mainly composed of methane, with slight ethane and trace propane. The gas reservoirs are higher in water saturation, with well preserved primary water. Then, it was discriminated from the relationship of H2S content vs. methane carbon isotope that the heavier methane carbon isotope of natural gas in this area is not caused by thermochemical sulfate reduction (TSR. Based on the comparison of methane carbon isotope in this area with that in adjacent areas, and combined with the tectonic evolution background, it is regarded that the natural gas in the Weiyuan gas field is mainly derived from water-soluble gas rather than be migrated laterally from adjacent areas. Some conclusions are made. First, since methane released from water is carbon isotopically heavier, the water-soluble gas accumulation after degasification results in the heavy methane carbon isotope of the gas produced from Weiyuan gas field. Second, along with Himalayan movement, great uplift occurred in the Weiyuan area and structural traps were formed. Under high temperature and high pressure, the gas dissolved in water experienced decompression precipitation, and the released natural gas accumulated in traps, consequently leading to the formation of Weiyuan gas field. Third, based on calculation, the amount of natural gas released from water which is entrapped in the Weiyuan gas field after the tectonic uplift is basically equal to the proved reserves of this field, confirming the opinion of water

  14. The dependence on temperature and salinity of dissolved

    NARCIS (Netherlands)

    Bakker, Dorothee C.E.; Baar, Hein J.W. de; Jong, Edwin de

    1999-01-01

    Recurring latitudinal patterns of the dissolved inorganic carbon (DIC) content and the fugacity of CO2 (fCO2) were observed in East Atlantic surface waters with strong gradients at hydrographic fronts. The dissolved inorganic carbon chemistry clearly displayed the effects of oceanic circulation and

  15. Radiation-chemical sanitation of dissolved pollutants and environmental protection

    International Nuclear Information System (INIS)

    Petrukhin, N.V.; Putilov, A.V.

    1986-01-01

    Radiation-chemical sanitation of dissolved toxic pollutants resulted from the production processes of different substances and modern equipment operation is considered. The processes of fundamental industrial sewage processing and, as a result, features of practically total disposal of dissolved toxic agents are considered for the first time

  16. Formulation of Fast-Dissolving Tablets of Promethazine Theoclate ...

    African Journals Online (AJOL)

    Purpose: To optimize and formulate promethazine theoclate fast-dissolving tablets that offer a suitable approach to the treatment of nausea and vomiting. Method: The solubility of promethazine theoclate was increased by formulating it as a fast-dissolving tablet containing β-cyclodextrin, crospovidone, and camphor, using ...

  17. Fast Dissolving Tablets of Aloe Vera Gel | Madan | Tropical Journal ...

    African Journals Online (AJOL)

    Purpose: The objective of this work was to prepare and evaluate fast dissolving tablets of the nutraceutical, freeze dried Aloe vera gel. Methods: Fast dissolving tablets of the nutraceutical, freeze-dried Aloe vera gel, were prepared by dry granulation method. The tablets were evaluated for crushing strength, disintegration ...

  18. Natural gas

    Energy Technology Data Exchange (ETDEWEB)

    Fraser, J W

    1967-08-01

    This report on the natural gas industry of Canada includes: composition and uses of natural gas, production statistics, exploration and development, reserve estimates, natural gas processing, transportation, and marketing. For the Canadian natural gas industry, 1966 was a year of moderate expansion in all phases, with a strong demand continuing for sulfur and liquid hydrocarbons produced as by-products of gas processing. Value of natural gas production increased to $199 million and ranked sixth in terms of value of mineral ouput in Canada. Currently, natural gas provides over 70% of Canada's energy requirements. Proved remaining marketable reserves are estimated to be in excess of a 29-yr supply.

  19. Gas Sensor

    KAUST Repository

    Luebke, Ryan

    2015-01-22

    A gas sensor using a metal organic framework material can be fully integrated with related circuitry on a single substrate. In an on-chip application, the gas sensor can result in an area-efficient fully integrated gas sensor solution. In one aspect, a gas sensor can include a first gas sensing region including a first pair of electrodes, and a first gas sensitive material proximate to the first pair of electrodes, wherein the first gas sensitive material includes a first metal organic framework material.

  20. Gas Sensor

    KAUST Repository

    Luebke, Ryan; Eddaoudi, Mohamed; Omran, Hesham; Belmabkhout, Youssef; Shekhah, Osama; Salama, Khaled N.

    2015-01-01

    A gas sensor using a metal organic framework material can be fully integrated with related circuitry on a single substrate. In an on-chip application, the gas sensor can result in an area-efficient fully integrated gas sensor solution. In one aspect, a gas sensor can include a first gas sensing region including a first pair of electrodes, and a first gas sensitive material proximate to the first pair of electrodes, wherein the first gas sensitive material includes a first metal organic framework material.

  1. Planning of in-situ experiment for understanding of gas migration behaviour in sedimentary rock. (1) Setting of gas injection procedure

    International Nuclear Information System (INIS)

    Tanai, Kenji; Fujita, Tomoo; Noda, Masaru; Yamamoto, Shuichi; Shimura, Tomoyuki; Sato, Shin

    2013-01-01

    Japan Atomic Energy Agency has been planning in-situ gas migration test in Horonobe URL, Hokkaido. This paper discusses the optimum gas injection procedure for the test to understand gas migration behaviour in surrounded rock. The stepwise constant gas injection was selected, taking into account domestic and overseas gas related research results. Hydro-mechanical-gas coupling analysis which is able to consider the dissolved methane in Horonobe groundwater was applied to evaluate the gas behaviour. The results have indicated no significant mechanical damages to the rock and have supported the appropriateness of selected gas injection procedure for the test. (author)

  2. Carbon ion pump for removal of carbon dioxide from combustion gas and other gas mixtures

    Energy Technology Data Exchange (ETDEWEB)

    Aines, Roger D.; Bourcier, William L.

    2014-08-19

    A novel method and system of separating carbon dioxide from flue gas is introduced. Instead of relying on large temperature or pressure changes to remove carbon dioxide from a solvent used to absorb it from flue gas, the ion pump method, as disclosed herein, dramatically increases the concentration of dissolved carbonate ion in solution. This increases the overlying vapor pressure of carbon dioxide gas, permitting carbon dioxide to be removed from the downstream side of the ion pump as a pure gas. The ion pumping may be obtained from reverse osmosis, electrodialysis, thermal desalination methods, or an ion pump system having an oscillating flow in synchronization with an induced electric field.

  3. Carbon ion pump for removal of carbon dioxide from combustion gas and other gas mixtures

    Science.gov (United States)

    Aines, Roger D.; Bourcier, William L.

    2010-11-09

    A novel method and system of separating carbon dioxide from flue gas is introduced. Instead of relying on large temperature or pressure changes to remove carbon dioxide from a solvent used to absorb it from flue gas, the ion pump method, as disclosed herein, dramatically increases the concentration of dissolved carbonate ion in solution. This increases the overlying vapor pressure of carbon dioxide gas, permitting carbon dioxide to be removed from the downstream side of the ion pump as a pure gas. The ion pumping may be obtained from reverse osmosis, electrodialysis, thermal desalination methods, or an ion pump system having an oscillating flow in synchronization with an induced electric field.

  4. Air supersaturation, release of wooden fibres and upstream migration of Atlantic salmon at Rygene power plant in the River Nidelva, Aust Agder county; Vurdering av luftovermetning, trefiberutslipp og oppvandring av laks ved Rygene kraftverk i Nidelva, Aust-Agder

    Energy Technology Data Exchange (ETDEWEB)

    Thorstad, Eva B.; Kroglund, Frode; Oekland, Finn; Heggberget, Tor G.

    1997-12-31

    Incidents of dead fish have been reported in connection with a power plant at Rygene on the River Nidelva in the Aust-Agder county, Norway. Air supersaturation has been used in a bypass construction of the power plant tunnel system. In addition, wooden fibres from a fabric have been released into the water of the tunnel. Results from relevant studies concerning air saturation, wooden fibres and upstream migration are summarised in this report. 148 refs., 4 figs., 2 tabs.

  5. Gas manufacture

    Energy Technology Data Exchange (ETDEWEB)

    Fell, J W

    1915-05-03

    Retorts for the distillation of shale or coal for the production of oil or illuminating-gas are heated by gas from a generator or a gas-holder, and a portion of the gas from the flue leading to the heating-flues is forced by a steam jet through a by-pass and is injected into the bottom of the retorts. If the gas to be admitted to the retort is cold, it is first heated.

  6. Natural Gas

    OpenAIRE

    Bakar, Wan Azelee Wan Abu; Ali, Rusmidah

    2010-01-01

    Natural gas fuel is a green fuel and becoming very demanding because it is environmental safe and clean. Furthermore, this fuel emits lower levels of potentially harmful by-products into the atmosphere. Most of the explored crude natural gas is of sour gas and yet, very viable and cost effective technology is still need to be developed. Above all, methanation technology is considered a future potential treatment method for converting the sour natural gas to sweet natural gas.

  7. Yucca Mountain Area Saturated Zone Dissolved Organic Carbon Isotopic Data

    International Nuclear Information System (INIS)

    Thomas, James; Decker, David; Patterson, Gary; Peterman, Zell; Mihevc, Todd; Larsen, Jessica; Hershey, Ronald

    2007-01-01

    Groundwater samples in the Yucca Mountain area were collected for chemical and isotopic analyses and measurements of water temperature, pH, specific conductivity, and alkalinity were obtained at the well or spring at the time of sampling. For this project, groundwater samples were analyzed for major-ion chemistry, deuterium, oxygen-18, and carbon isotopes of dissolved inorganic carbon (DIC) and dissolved organic carbon (DOC). The U.S. Geological Survey (USGS) performed all the fieldwork on this project including measurement of water chemistry field parameters and sample collection. The major ions dissolved in the groundwater, deuterium, oxygen-18, and carbon isotopes of dissolved inorganic carbon (DIC) were analyzed by the USGS. All preparation and processing of samples for DOC carbon isotopic analyses and geochemical modeling were performed by the Desert Research Institute (DRI). Analysis of the DOC carbon dioxide gas produced at DRI to obtain carbon-13 and carbon-14 values was conducted at the University of Arizona Accelerator Facility (a NSHE Yucca Mountain project QA qualified contract facility). The major-ion chemistry, deuterium, oxygen-18, and carbon isotopes of DIC were used in geochemical modeling (NETPATH) to determine groundwater sources, f ow paths, mixing, and ages. The carbon isotopes of DOC were used to calculate groundwater ages that are independent of DIC model corrected carbon-14 ages. The DIC model corrected carbon-14 calculated ages were used to evaluate groundwater travel times for mixtures of water including water beneath Yucca Mountain. When possible, groundwater travel times were calculated for groundwater flow from beneath Yucca Mountain to down gradient sample sites. DOC carbon-14 groundwater ages were also calculated for groundwaters in the Yucca Mountain area. When possible, groundwater travel times were estimated for groundwater flow from beneath Yucca Mountain to down gradient groundwater sample sites using the DOC calculated

  8. Concept of off-gas purification in reprocessing plants

    International Nuclear Information System (INIS)

    Henrich, E.; von Ammon, R.

    1986-01-01

    Concepts and individual processes for the off-gas purification in reprocessing plants are described which are suited to achieve a better retention of the gaseous and volatile radionuclides 129 I, 85 Kr, 14 C, and tritium. Improved and new process steps have been developed to the cold pilot plant scale. Essential individual process steps are an efficient iodine desorption from the dissolver solution, improved and new off-gas scrubs with nitric acid, a cryogenic as well as a selective absorption process for rare gas recovery plus the required prepurification steps and a process for the continuous and pressure-free fixation and storage of krypton in a metal matrix. Individual facilities have been selected and combined to investigate integrated dissolver off-gas systems. Advanced concepts based on a process using low flows and loads of all off-gas streams including the cell ventilation off-gas are briefly discussed

  9. Microbial degradation of dissolved proteins in seawater

    International Nuclear Information System (INIS)

    Hollibaugh, J.T.; Azam, F.

    1983-01-01

    An experimental protocol using radiolabeled proteins was developed to investigate the rates and mechanisms whereby dissolved proteins are degraded in natural marine plankton communities. The results of field observations and laboratory experiments indicate that proteins are degraded by a particle-bound, thermolabile system, presumably bacteria-associated enzymes, with an apparent half-saturation constant of ca. 25 μg bovine serum albumin (BSA) per liter. Gel permeation chromatography indicated that peptides of chain length intermediate between BSA and the final products of degradation (MW<700) do not accumulate in the medium. Competition experiments indicate that the system is relatively nonspecific. Turnover rates for the protein pool in samples collected in the Southern California Bight were of the same order of magnitude as the turnover rate of the L-leucine pool and were correlated with primary productivity, chlorophyll a concentrations, bacterial abundance and biomass, and L-leucine turnover rate. These data suggest that amino acids derived from proteins are utilized preferentially and do not completely mix with the amino acids in the bulk phase

  10. Methanex, Hoechst Celanese dissolve methanol partnership

    International Nuclear Information System (INIS)

    Morris, G.D.L.

    1993-01-01

    One of the many joint venture alliances recently announced in the petrochemical sector is ending in divorce. Hoechst Celanese Chemical (Dallas) and Methanex Corp. (Vancouver) are in the process of dissolving the partnership they had formed to restart Hoechst Celanese's methanol plant at Clear Lake, TX. Hoechst Celanese says it is actively seeking replacement partners and has several likely prospects, while Methanex is concentrating on its other ventures. Those include its just-completed acquisition of Fletcher Challenge's (Auckland, NZ) methanol business and a joint venture with American Cyanamid to convert an ammonia plant at Fortier, LA to methanol. Methanex will still be the world's largest producer of methanol. Officially, the negotiations between Methanex and Hoechst Celanese 'just broke down over the last month or so,' says Steve Yurich, operations manager for the Clear Lake plant. Market sources, however, say that Methanex found itself 'with too many irons in the fire' and pulled out before it ran into financial or perhaps even antitrust difficulties

  11. Optimizing dissolved air flotation design system

    Directory of Open Access Journals (Sweden)

    L.A. Féris

    2000-12-01

    Full Text Available Dissolved Air (Pressure Flotation-DAF, is a well-established separation process that employs micro-bubbles as a carrier phase. This work shows results concerning bubble generation at low working pressures in modified DAF-units to improve the collection of fragile coagula by bubbles. DAF of Fe (OH3 (as model was studied as a function of saturation pressure in the absence and presence of surfactants in the saturator. DAF was possible at 2 atm by lowering the air/water surface tension. This fact, which leads to substantial energy savings, was explained in terms of decreasing the "minimum" energy required for bubble nucleation and cavity in the nozzle. More, bubbles-fragile coagula attachment was improved by dividing the recycling water into two: 1 the inclined inlet to the cell (traditional and 2 inside the separation tank through a water flow inlet situated below the floating bed using a "mushroom" type diffuser. Because of the reduction observed in the degree of turbulence in the conventional collection zone, DAF performance improved yielding high precipitate recoveries.

  12. Analysis of a gas absorption system with soluble carrier gas and volatile solvent

    International Nuclear Information System (INIS)

    Kanak, B.E.

    1980-01-01

    The effects of column diameter, carrier gas coabsorption, and solvent vaporization on the performance of a packed gas absorption column are examined. The system investigated employs dichlorodifluoromethane as a solvent to remove krypton from a nitrogen stream and is characterized by substantial nitrogen coabsorption. Three columns with diameters of 2, 3, and 4 inches were constructed and packed with 34.5 inches of Goodloe packing. In addition to the more conventional data, the experimental evaluation of these columns included the use of a radioisotope and a gamma scanning technique which provided direct measurement of the columns' molar krypton profiles. A multicomponent gas absorption model was developed, based on the two-film mass transfer theory, that allows the fluxes of all species to interact. Verification of this model was achieved through comparison of the calculated results with experimental data. With the feed gas flow rate between 6 and 36 lb moles/hr-ft 2 and the solvent feed rate between 40 and 400 lb moles/hr-ft 2 , column diameter was found to have no significant impact on the mass transfer efficiency of this system when carried out in columns with diameters of 2 inches or greater. The absorption of krypton was found to be enhanced and inhibited, respectively, by carrier gas coabsorption and solvent vaporization. An injector system to add gaseous solvent to the feed gas stream prior to its introduction into the packed bed was proposed to eliminate the detrimental effects of solvent vaporization.Using this injector to supersaturate the feed gas stream with solvent enhanced absorber performance in the same manner as carrier gas coabsorption

  13. Evaluating the predictability of the in vitro transfer model and in vivo rat studies as a surrogate to investigate the supersaturation and precipitation behaviour of different Albendazole formulations for humans.

    Science.gov (United States)

    Ruff, Aaron; Holm, René; Kostewicz, Edmund S

    2017-07-15

    The present study investigated the ability of the in vitro transfer model and an in vivo pharmacokinetic study in rats to investigate the supersaturation and precipitation behaviour of albendazole (ABZ) relative to data from a human intestinal aspiration study reported in the literature. Two lipid based formulation systems, a hydroxypropyl-β-cyclodextrin (HPβCD) solution and the addition of a crystallization inhibitor (HPMC-E5) on the behaviour of ABZ was investigated. These formulations were investigated to represent differences in their ability to facilitate supersaturation within the small intestine. Overall, both the in vitro transfer model and the in vivo rat study were able to rank order the formulations (as aqueous suspension±HPMCsupersaturation and precipitation behaviour of ABZ using the different formulation strategies, could be attained. Copyright © 2017 Elsevier B.V. All rights reserved.

  14. Dissolved oxygen removal on radiolysis: studies in context of use of nitrogen atmosphere above PHT storage bag in Indian PHWRs

    International Nuclear Information System (INIS)

    Kumbhar, A.G.; Venkateswaran, G.; Kishore, K.; Kumar, Sangeeta D.; Naik, D.B.

    2008-01-01

    Dissolved oxygen content of the water (N 2 in gas phase) sample on radiolysis was measured and it was observed that up to 2 M Rad dose, oxygen content decreases linearly and at higher doses remains constant. Results are compared with nitrate ion yield in water-N 2 systems determined earlier. In aerated solutions also, nitrate ion yield was measured as function of dose. (author)

  15. Flue gas desulfurization/denitrification using metal-chelate additives

    Science.gov (United States)

    Harkness, J.B.L.; Doctor, R.D.; Wingender, R.J.

    1985-08-05

    A method of simultaneously removing SO/sub 2/ and NO from oxygen-containing flue gases resulting from the combustion of carbonaceous material by contacting the flue gas with an aqueous scrubber solution containing an aqueous sulfur dioxide sorbent and an active metal chelating agent which promotes a reaction between dissolved SO/sub 2/ and dissolved NO to form hydroxylamine N-sulfonates. The hydroxylamine sulfonates are then separated from the scrubber solution which is recycled. 3 figs.

  16. Oxygen sensitive polymeric nanocapsules for optical dissolved oxygen sensors

    Science.gov (United States)

    Sun, Zhijuan; Cai, Chenxin; Guo, Fei; Ye, Changhuai; Luo, Yingwu; Ye, Shuming; Luo, Jianchao; Zhu, Fan; Jiang, Chunyue

    2018-04-01

    Immobilization of the oxygen-sensitive probes (OSPs) in the host matrix greatly impacts the performance and long-term usage of the optical dissolved oxygen (DO) sensors. In this work, fluorescent dyes, as the OSPs, were encapsulated with a crosslinked fluorinated polymer shell by interfacial confined reversible addition fragmentation chain transfer miniemulsion polymerization to fabricate oxygen sensitive polymeric nanocapsules (NCs). The location of fluorescent dyes and the fluorescent properties of the NCs were fully characterized by fourier transform infrared spectrometer, x-ray photoelectron spectrometer and fluorescent spectrum. Dye-encapsulated capacity can be precisely tuned from 0 to 1.3 wt% without self-quenching of the fluorescent dye. The crosslinked fluorinated polymer shell is not only extremely high gas permeability, but also prevents the fluorescent dyes from leakage in aqueous as well as in various organic solvents, such as ethanol, acetone and tetrahydrofuran (THF). An optical DO sensor based on the oxygen sensitive NCs was fabricated, showing high sensitivity, short response time, full reversibility, and long-term operational stability of online monitoring DO. The sensitivity of the optical DO sensor is 7.02 (the ratio of the response value in fully deoxygenated and saturated oxygenated water) in the range 0.96-14.16 mg l-1 and the response time is about 14.3 s. The sensor’s work curve was fit well using the modified Stern-Volmer equation by two-site model, and its response values are hardly affected by pH ranging from 2 to 12 and keep constant during continuous measurement for 3 months. It is believed that the oxygen sensitive polymeric NCs-based optical DO sensor could be particularly useful in long-term online DO monitoring in both aqueous and organic solvent systems.

  17. Dissolved air flotation of polishing wastewater from semiconductor manufacturer.

    Science.gov (United States)

    Liu, J C; Lien, C Y

    2006-01-01

    The feasibility of the dissolved air flotation (DAF) process in treating chemical mechanical polishing (CMP) wastewater was evaluated in this study. Wastewater from a local semiconductor manufacturer was sampled and characterised. Nano-sized silica (77.6 nm) with turbidity of 130 +/- 3 NTU was found in the slightly alkaline wastewater with traces of other pollutants. Experimental results indicated removal efficiency of particles, measured as suspended particle or turbidity, increased with increasing concentration of cationic collector cetyltrimethyl ammonium bromide (CTAB). When CTAB concentration was 30 mg/L, pH of 6.5 +/- 0.1 and recycle ratio of 30%, very effective removal of particles (> 98%) was observed in saturation pressure range of 4 to 6 kg/cm2, and the reaction proceeded faster under higher pressure. Similarly, the reaction was faster under the higher recycle ratio, while final removal efficiency improved slightly as the recycle ratio increased from 20 to 40%. An insignificant effect of pH on treatment efficiency was found as pH varied from 4.5 to 8.5. The presence of activator, Al3+ and Fe3+, enhanced the system performance. It is proposed that CTAB adsorbs on silica particles in polishing wastewater through electrostatic interaction and makes particles more hydrophobic. The increase in hydrophobicity results in more effective bubble-particle collisions. In addition, flocculation of silica particles through bridging effect of collector was found; it is believed that flocculation of particles also contributed to flotation. Better attachment between gas bubble and solid, higher buoyancy and higher air to solid ratio all lead to effective flotation.

  18. Dissolved organic carbon and chromophoric dissolved organic matter properties of rivers in the USA

    Science.gov (United States)

    Spencer, Robert G. M.; Butler, Kenna D.; Aiken, George R.

    2012-09-01

    Dissolved organic carbon (DOC) concentration and chromophoric dissolved organic matter (CDOM) parameters were measured over a range of discharge in 30 U.S. rivers, covering a diverse assortment of fluvial ecosystems in terms of watershed size and landscape drained. Relationships between CDOM absorption at a range of wavelengths (a254, a350, a440) and DOC in the 30 watersheds were found to correlate strongly and positively for the majority of U.S. rivers. However, four rivers (Colorado, Colombia, Rio Grande and St. Lawrence) exhibited statistically weak relationships between CDOM absorption and DOC. These four rivers are atypical, as they either drain from the Great Lakes or experience significant impoundment of water within their watersheds, and they exhibited values for dissolved organic matter (DOM) parameters indicative of autochthonous or anthropogenic sources or photochemically degraded allochthonous DOM and thus a decoupling between CDOM and DOC. CDOM quality parameters in the 30 rivers were found to be strongly correlated to DOM compositional metrics derived via XAD fractionation, highlighting the potential for examining DOM biochemical quality from CDOM measurements. This study establishes the ability to derive DOC concentration from CDOM absorption for the majority of U.S. rivers, describes characteristics of riverine systems where such an approach is not valid, and emphasizes the possibility of examining DOM composition and thus biogeochemical function via CDOM parameters. Therefore, the usefulness of CDOM measurements, both laboratory-based analyses and in situ instrumentation, for improving spatial and temporal resolution of DOC fluxes and DOM dynamics in future studies is considerable in a range of biogeochemical studies.

  19. Dissolved organic carbon and chromophoric dissolved organic matter properties of rivers in the USA

    Science.gov (United States)

    Spencer, Robert G.M.; Butler, Kenna D.; Aiken, George R.

    2012-01-01

    Dissolved organic carbon (DOC) concentration and chromophoric dissolved organic matter (CDOM) parameters were measured over a range of discharge in 30 U.S. rivers, covering a diverse assortment of fluvial ecosystems in terms of watershed size and landscape drained. Relationships between CDOM absorption at a range of wavelengths (a254, a350, a440) and DOC in the 30 watersheds were found to correlate strongly and positively for the majority of U.S. rivers. However, four rivers (Colorado, Colombia, Rio Grande and St. Lawrence) exhibited statistically weak relationships between CDOM absorption and DOC. These four rivers are atypical, as they either drain from the Great Lakes or experience significant impoundment of water within their watersheds, and they exhibited values for dissolved organic matter (DOM) parameters indicative of autochthonous or anthropogenic sources or photochemically degraded allochthonous DOM and thus a decoupling between CDOM and DOC. CDOM quality parameters in the 30 rivers were found to be strongly correlated to DOM compositional metrics derived via XAD fractionation, highlighting the potential for examining DOM biochemical quality from CDOM measurements. This study establishes the ability to derive DOC concentration from CDOM absorption for the majority of U.S. rivers, describes characteristics of riverine systems where such an approach is not valid, and emphasizes the possibility of examining DOM composition and thus biogeochemical function via CDOM parameters. Therefore, the usefulness of CDOM measurements, both laboratory-based analyses and in situ instrumentation, for improving spatial and temporal resolution of DOC fluxes and DOM dynamics in future studies is considerable in a range of biogeochemical studies.

  20. Endogenous gas formation--an in vitro study with relevance to gas microemboli during cardiopulmonary bypass.

    Science.gov (United States)

    Lindholm, Lena; Engström, Karl Gunnar

    2012-09-01

    Gas embolism is an identified problem during cardiopulmonary bypass (CPB). Our aim was to analyze the potential influence from gas solubility based on simple physical laws, here called endogenous gas embolism. Gas solubility decreases at higher temperature and gas bubbles are presumably formed at CPB warming. An experimental model to measure gas release was designed. Medium (water or blood retrieved from mediastinal drains, 14.6 mL) was incubated and equilibrated with gas (air, 100% oxygen, or 5% carbon dioxide in air) at low temperature (10 degrees C or 23 degrees C). At warming to 37 degrees C, gas release was digitally measured. Also, the effect of fluid motion was evaluated. At warming, the medium became oversaturated with dissolved gas. When fluid motion was applied, gas was released to form bubbles. This was exemplified by a gas release of .45% (.31/.54, medians and quartile range, volume percent, p = .007) and 1.26% (1.14/ 1.33, p = .003) when blood was warmed from 23 degrees C or 10 degrees C to 37 degrees C, respectively (carbon dioxide 5% in air). Consistent findings were seen for water and with the other types of gas exposure. The theory of endogenous gas embolization was confirmed with gas being released at warming. The endogenous gas formation demonstrated a dynamic pattern with oversaturation and with rapid gas released at fluid motion. The gas release at warming was substantial, in particular when the results were extrapolated to full-scale CPB conditions. The interference from endogenous gas formation should be considered in parallel to external sources of gas microemboli. cardiopulmonary bypass, gas embolization, microemboli, gas solubility, temperature.

  1. Dissolved Air Flotation of arsenic adsorbent particles

    Directory of Open Access Journals (Sweden)

    Mario Enrique Santander Muñoz

    2015-01-01

    Full Text Available The removal of arsenic from synthetic effluent was studied using the adsorbent particle flotation technique (APF and dissolved air flotation (DAF. A sample of an iron mineral was used as adsorbent particles of arsenic, ferric chloride as coagulant, cationic poly-acrylamide (NALCO 9808 as flocculants, and sodium oleate as collector. Adsorption studies to determine the pH influence, contact time, and adsorbent particles concentration on the adsorption of arsenic were carried out along with flotation studies to determine the removal efficiency of adsorbents particles. The results achieved indicate that the adsorption kinetic of arsenic is very rapid and that in range of pH’s from 2 to 7 the adsorption percentages remain constant. The equilibrium conditions were achieved in 60 minutes and about 95% of arsenic was adsorbed when used an adsorbent concentration of 2 g/L and pH 6.3. The maximum adsorption capacity of adsorbent particles was 4.96 mg/g. The mean free energy of adsorption (E was found to be 2.63 kJ/mol, which suggests physisorption. The results of the flotation studies demonstrated that when synthetic effluents with 8.9 mg/L of arsenic were treated under the following experimental conditions; 2 g/L of adsorbent particles, 120 mg/L of Fe(III, 2 mg/L of Nalco 9808, 20 mg/L of sodium oleate, and 40% of recycle ratio in the DAF, it was possible to reach 98% of arsenic removal and 6.3 NTU of residual turbidity in clarified synthetic effluent.

  2. Convective mass transfer around a dissolving bubble

    Science.gov (United States)

    Duplat, Jerome; Grandemange, Mathieu; Poulain, Cedric

    2017-11-01

    Heat or mass transfer around an evaporating drop or condensing vapor bubble is a complex issue due to the interplay between the substrate properties, diffusion- and convection-driven mass transfer, and Marangoni effects, to mention but a few. In order to disentangle these mechanisms, we focus here mainly on the convective mass transfer contribution in an isothermal mass transfer problem. For this, we study the case of a millimetric carbon dioxide bubble which is suspended under a substrate and dissolved into pure liquid water. The high solubility of CO2 in water makes the liquid denser and promotes a buoyant-driven flow at a high (solutal) Rayleigh number (Ra˜104 ). The alteration of p H allows the concentration field in the liquid to be imaged by laser fluorescence enabling us to measure both the global mass flux (bubble volume, contact angle) and local mass flux around the bubble along time. After a short period of mass diffusion, where the boundary layer thickens like the square root of time, convection starts and the CO2 is carried by a plume falling at constant velocity. The boundary layer thickness then reaches a plateau which depends on the bubble cross section. Meanwhile the plume velocity scales like (dV /d t )1 /2 with V being the volume of the bubble. As for the rate of volume loss, we recover a constant mass flux in the diffusion-driven regime followed by a decrease in the volume V like V2 /3 after convection has started. We present a model which agrees well with the bubble dynamics and discuss our results in the context of droplet evaporation, as well as high Rayleigh convection.

  3. Dynamical Conditions of Ice Supersaturation and Ice Nucleation in Convective Systems: A Comparative Analysis Between in Situ Aircraft Observations and WRF Simulations

    Science.gov (United States)

    D’Alessandro, John J.; Diao, Minghui; Wu, Chenglai; Liu, Xiaohong; Chen, Ming; Morrison, Hugh; Eidhammer, Trude; Jensen, Jorgen B.; Bansemer, Aaron; Zondlo, Mark A.; hide

    2017-01-01

    Occurrence frequency and dynamical conditions of ice supersaturation (ISS, where relative humidity with respect to ice (RHi) greater than 100%) are examined in the upper troposphere around convective activity. Comparisons are conducted between in situ airborne observations and the Weather Research and Forecasting model simulations using four double-moment microphysical schemes at temperatures less than or or equal to -40degdegC. All four schemes capture both clear-sky and in-cloud ISS conditions. However, the clear-sky (in-cloud) ISS conditions are completely (significantly) limited to the RHi thresholds of the Cooper parameterization. In all of the simulations, ISS occurrence frequencies are higher by approximately 3-4 orders of magnitude at higher updraft speeds (greater than 1 m s(exp -1) than those at the lower updraft speeds when ice water content (IWC) greater than 0.01 gm(exp -3), while observations show smaller differences up to approximately 1-2 orders of magnitude. The simulated ISS also occurs less frequently at weaker updrafts and downdrafts than observed. These results indicate that the simulations have a greater dependence on stronger updrafts to maintain/generate ISS at higher IWC. At lower IWC (less than or equal or 0.01 gm(exp -3), simulations unexpectedly show lower ISS frequencies at stronger updrafts. Overall, the Thompson aerosol-aware scheme has the closest magnitudes and frequencies of ISS greater than 20% to the observations, and the modified Morrison has the closest correlations between ISS frequencies and vertical velocity at higher IWC and number density. The Cooper parameterization often generates excessive ice crystals and therefore suppresses the frequency and magnitude of ISS, indicating that it should be initiated at higher ISS (e.g.,lees than or equal to 25%).

  4. The effect of cation:anion ratio in solution on the mechanism of barite growth at constant supersaturation: Role of the desolvation process on the growth kinetics

    Science.gov (United States)

    Kowacz, M.; Putnis, C. V.; Putnis, A.

    2007-11-01

    The mechanism of barite growth has been investigated in a fluid cell of an Atomic Force Microscope by passing solutions of constant supersaturation ( Ω) but variable ion activity ratio ( r=a/a) over a barite substrate.The observed dependence of step-spreading velocity on solution stoichiometry can be explained by considering non-equivalent attachment frequency factors for the cation and anion. We show that the potential for two-dimensional nucleation changes under a constant thermodynamic driving force due to the kinetics of barium integration into the surface, and that the growth mode changes from preexisting step advancement to island spreading as the cation/anion activity ratio increases. Scanning electron microscopy studies of crystals grown in bulk solutions support our findings that matching the ion ratio in the fluid to that of the crystal lattice does not result in maximum growth and nucleation rates. Significantly more rapid rates correspond to solution stoichiometries where [Ba 2+] is in excess with respect to [ SO42-]. Experiments performed in dilute aqueous solutions of methanol show that even 0.02 molar fraction of organic cosolvent in the growth solution significantly accelerates step growth velocity and nucleation rates (while keeping Ω the same as in the reference solution in water). Our observations suggest that the effect of methanol on barite growth results first of all from reduction of the barrier that prevents the Ba 2+ from reaching the surface and corroborate the hypothesis that desolvation of the cation and of the surface is the rate limiting kinetic process for two-dimensional nucleation and for crystal growth.

  5. The precipitation, growth and stability of mercury sulfide nanoparticles formed in the presence of marine dissolved organic matter.

    Science.gov (United States)

    Mazrui, Nashaat M; Seelen, Emily; King'ondu, Cecil K; Thota, Sravan; Awino, Joseph; Rouge, Jessica; Zhao, Jing; Mason, Robert P

    2018-04-25

    The methylation of mercury is known to depend on the chemical forms of mercury (Hg) present in the environment and the methylating bacterial activity. In sulfidic sediments, under conditions of supersaturation with respect to metacinnabar, recent research has shown that mercury precipitates as β-HgS(s) nanoparticles (β-HgS(s)nano). Few studies have examined the precipitation of β-HgS(s)nano in the presence of marine dissolved organic matter (DOM). In this work, we used dynamic light scattering (DLS) coupled with UV-Vis spectroscopy and transmission electron microscopy (TEM) to investigate the formation and fate of β-HgS(s)nano formed in association with marine DOM extracted from the east and west of Long Island Sound, and at the shelf break of the North Atlantic Ocean, as well as with low molecular weight thiols. We found that while the β-HgS(s)nano formed in the presence of oceanic DOM doubled in size after 5 weeks, those forming in solutions with coastal DOM did not grow over time. In addition, when the HgII : DOM ratio was varied, β-HgS(s)nano only rapidly aggregated at high ratios (>41 μmol HgII per mg C) where the concentration of thiol groups was determined to be substantially low relative to HgII. This suggests that functional groups other than thiols could be involved in the stabilization of β-HgS(s)nano. Furthermore, we showed that β-HgS(s)nano forming under anoxic conditions remained stable and could therefore persist in the environment sufficiently to impact the methylation potential. Exposure of β-HgS(s)nano to sunlit and oxic environments, however, caused rapid aggregation and sedimentation of the nanoparticles, suggesting that photo-induced changes or oxidation of organic matter adsorbed on the surface of β-HgS(s)nano affected their stability in surface waters.

  6. Adsorption of Dissolved Gases (CH4, CO2, H2, Noble Gases) by Water-Saturated Smectite Clay Minerals

    Science.gov (United States)

    Bourg, I. C.; Gadikota, G.; Dazas, B.

    2016-12-01

    Adsorption of dissolved gases by water-saturated clay minerals plays important roles in a range of fields. For example, gas adsorption in on clay minerals may significantly impact the formation of CH4 hydrates in fine-grained sediments, the behavior of CH4 in shale, CO2 leakage across caprocks of geologic CO2 sequestration sites, H2 leakage across engineered clay barriers of high-level radioactive waste repositories, and noble gas geochemistry reconstructions of hydrocarbon migration in the subsurface. Despite its importance, the adsorption of gases on clay minerals remains poorly understood. For example, some studies have suggested that clay surfaces promote the formation of CH4 hydrates, whereas others indicate that clay surfaces inhibit the formation of CH4 hydrates. Here, we present molecular dynamics (MD) simulations of the adsorption of a range of gases (CH4, CO2, H2, noble gases) on clay mineral surfaces. Our results indicate that the affinity of dissolved gases for clay mineral surfaces has a non-monotone dependence on the hydrated radius of the gas molecules. This non-monotone dependence arises from a combination of two effects: the polar nature of certain gas molecules (in particular, CO2) and the templating of interfacial water structure by the clay basal surface, which results in the presence of interfacial water "cages" of optimal size for intermediate-size gas molecules (such as Ne or Ar).

  7. Dating base flow in streams using dissolved gases and diurnal temperature changes

    Science.gov (United States)

    Sanford, Ward E.; Casile, Gerolamo C.; Haase, Karl B.

    2015-01-01

    A method is presented for using dissolved CFCs or SF6 to estimate the apparent age of stream base flow by indirectly estimating the mean concentration of the tracer in the inflowing groundwater. The mean value is estimated simultaneously with the mean residence times of the gas and water in the stream by sampling the stream for one or both age tracers, along with dissolved nitrogen and argon at a single location over a period of approximately 12–14 h. The data are fitted to an equation representing the temporal in-stream gas exchange as it responds to the diurnal temperature fluctuation. The efficacy of the method is demonstrated by collecting and analyzing samples at six different stream locations across parts of northern Virginia, USA. The studied streams drain watersheds with areas of between 2 and 122 km2 during periods when the diurnal stream temperature ranged between 2 and 5°C. The method has the advantage of estimating the mean groundwater residence time of discharge from the watershed to the stream without the need for the collection of groundwater infiltrating to streambeds or local groundwater sampled from shallow observation wells near the stream.

  8. Change in lattice parameter of tantalum due to dissolved hydrogen

    Directory of Open Access Journals (Sweden)

    Gyanendra P. Tiwari

    2012-06-01

    Full Text Available The volume expansion of tantalum due to the dissolved hydrogen has been determined using Bragg equation. The hydrogen was dissolved in the pure tantalum metal at constant temperature (360 °C and constant pressure (132 mbar by varying the duration of hydrogen charging. The amount of dissolved hydrogen was within the solid solubility limit. The samples with different hydrogen concentration were analyzed by X-ray diffraction technique. Slight peak shifts as well as peak broadening were observed. The relative changes of lattice parameters plotted against the hydrogen concentration revealed that the lattice parameters varied linearly with the hydrogen concentration.

  9. A robust and fast method of sampling and analysis of delta13C of dissolved inorganic carbon in ground waters.

    Science.gov (United States)

    Spötl, Christoph

    2005-09-01

    The stable carbon isotopic composition of dissolved inorganic carbon (delta13C(DIC)) is traditionally determined using either direct precipitation or gas evolution methods in conjunction with offline gas preparation and measurement in a dual-inlet isotope ratio mass spectrometer. A gas evolution method based on continuous-flow technology is described here, which is easy to use and robust. Water samples (100-1500 microl depending on the carbonate alkalinity) are injected into He-filled autosampler vials in the field and analysed on an automated continuous-flow gas preparation system interfaced to an isotope ratio mass spectrometer. Sample analysis time including online preparation is 10 min and overall precision is 0.1 per thousand. This method is thus fast and can easily be automated for handling large sample batches.

  10. Source limitation of carbon gas emissions in high-elevation mountain streams and lakes

    Science.gov (United States)

    Crawford, John T.; Dornblaser, Mark M.; Stanley, Emily H.; Clow, David W.; Striegl, Robert G.

    2015-01-01

    Inland waters are an important component of the global carbon cycle through transport, storage, and direct emissions of CO2 and CH4 to the atmosphere. Despite predictions of high physical gas exchange rates due to turbulent flows and ubiquitous supersaturation of CO2—and perhaps also CH4—patterns of gas emissions are essentially undocumented for high mountain ecosystems. Much like other headwater networks around the globe, we found that high-elevation streams in Rocky Mountain National Park, USA, were supersaturated with CO2 during the growing season and were net sources to the atmosphere. CO2concentrations in lakes, on the other hand, tended to be less than atmospheric equilibrium during the open water season. CO2 and CH4 emissions from the aquatic conduit were relatively small compared to many parts of the globe. Irrespective of the physical template for high gas exchange (high k), we found evidence of CO2 source limitation to mountain streams during the growing season, which limits overall CO2emissions. Our results suggest a reduced importance of aquatic ecosystems for carbon cycling in high-elevation landscapes having limited soil development and high CO2 consumption via mineral weathering.

  11. Contribution of the bubbles to gas transfer across the ocean-atmosphere interface

    International Nuclear Information System (INIS)

    Memery, Laurent

    1983-05-01

    A first theoretical approach to gas transfer by bubbles is undertaken. Certain parameters which are neglected by smooth air-water interface models are studied. It is found that transfer velocity increases when solubility decreases. Further, bubble overpressure leads to water supersaturation at equilibrium, this supersaturation being more significant for less soluble gases. Although the transfer velocity remains roughly constant for a variable concentration gradient far from equilibrium, its range of variation becomes infinite near equilibrium. Because the notion of transfer velocity is not useful near equilibrium, attention is turned directly to the flux itself: the flux is a linear function of the concentration gradient. At least for tracers the coefficients of this function are entirely defined by the physico-chemical properties of the gas and by the bubble distribution. The dissertation is divided in three parts: - a synthesis which sums up the main experimental and theoretical results of the study of the influence of the bubbles created by breaking waves on gas transfer, - an article published in 'Journal of Geophysical Research', - an article submitted to 'Tellus'. (author) [fr

  12. The effect of CO{sub 2} dissolved in a diesel fuel on the jet flame characteristics

    Energy Technology Data Exchange (ETDEWEB)

    Xiao Jin; Huang Zhen; Qiao Xinqi; Hou Yuchun [Shanghai Jiao Tong University, Shanghai (China). Research Institute of Internal Combustion Engine

    2008-03-15

    This paper is concerned with an experimental study of the jet diffusion flame characteristics of fuel containing CO{sub 2}. Using diesel fuel containing dissolved CO{sub 2} gas, experiments were performed under atmospheric conditions with a diesel hole-type nozzle of 0.19 mm orifice diameter at constant injection pressure. In this study, four different CO{sub 2} mass fraction in diesel fuel such as 3.13%, 7.18%, 12.33% and 17.82% were used to study the effect of CO{sub 2} concentration on the jet flame characteristics. Jet flame characteristics were measured by direct photography, meanwhile the image colorimetry is used to assess the qualitative features of jet flame temperature. Experimental results show that the CO{sub 2} gas dilution effect and the atomization effect have a great influence on the flame structure and average temperature. When the injection pressure of diesel fuel increased from 4 MPa to 6 MPa, the low temperature flame length increased from 18.4 cm to 21.7 cm and the full temperature flame length decreased from 147.6 cm to 134.7 cm. With the increase of CO{sub 2} gas dissolved in the diesel fuel, the jet flame full length decreased for the jet atomization being improved greatly meanwhile the low temperature flame length increased for the CO{sub 2} gas dilution effect; with the increase of CO{sub 2} gas dissolved in the diesel fuel, the average temperature of flame increases firstly and then falls. Experimental results validate that higher injection pressure will improve jet atomization and then increased the flame average temperature. 27 refs., 13 figs.

  13. Preliminary Study: Application of Off-Axis ICOS to Determine Stable Carbon Isotope in Dissolved Inorganic Carbon

    Science.gov (United States)

    Kim, Y. T.; Lee, J. M.; Hwang, J. H.; Piao, J.; Woo, N. C.

    2015-12-01

    CO2 is one of the major causes for global climate change. Because stable carbon isotope ratio is used to trace carbon source, several analytical techniques likes IRMS (Isotope Ratio Mass Spectrometry) and LAS (Laser Absorption Spectrometry) were extensively used. Off-axis ICOS, a kind of LAS, has merits on long-term stability and field application, therefore it is widely being used in CCS (Carbon Capture and Storage) field. The aim of this study is to extend the application scope of OA-ICOS to determine dissolved inorganic carbon (DIC). Because OA-ICOS showed dependence of δ13C on CO2 concentration, data processing is required. We tested CO2 Carbon Isotope Analyzer (CCIA-36-EP, Los Gatos Research) with both reference gas (δ13C= -28.28‰) and aqueous solutions prepared by dissolving sodium bicarbonate standards (δ13C= -12.26‰ and +3.96‰). The differences of δ13C between reference and measurement values are plotted by CO2 concentrations, then compared. At first, we checked the similarity between our curve pattern for reference gas and Guillon's research (δ13C= -43.99‰) by other Analyzer. To analyze aqueous samples, more errors can be caused than gas analysis. The carbon isotope fractionation occurs during dissolving standard reagents and extracting DIC as CO2 gas form. This effect is mixed with CO2 concentration dependence effect, therefore the curve patterns are different with that for reference gas. Our experiments are done for various δ13C values. It could be an important point to use OA-ICOS to analyze DIC, too.

  14. Global effects of agriculture on fluvial dissolved organic matter

    DEFF Research Database (Denmark)

    Graeber, Daniel; Boëchat, Iola; Encina, Francisco

    2015-01-01

    Agricultural land covers approximately 40% of Earth’s land surface and affects hydromorphological, biogeochemical and ecological characteristics of fluvial networks. In the northern temperate region, agriculture also strongly affects the amount and molecular composition of dissolved organic matter...

  15. Remote repair of the dissolvers in Tokai reprocessing plant

    International Nuclear Information System (INIS)

    Otani, Yosikuni

    1985-01-01

    In the Tokai fuel reprocessing plant, there occurred failures (pinholes) in two dissolver tanks successively in 1982 and 1983. These dissolvers are set under high radiation field, not permitting access of the personnel. So, repair works were carried out after development of the remotely operated repair system. For repair of the failed dissolver tanks, after tests and studies, the means was employed of grinding off the wall surface to small depth and then forming over it a corrosion resistant sealing layer by padding welding. The repair system which enabled the repair and the inspection in the cell by remote operation consisted of six devices including polishing, welding, dye penetration test, etc. Repair works on the dissolvers took two months and a half from September 1983. (Mori, K.)

  16. Formulation of Fast-Dissolving Tablets of Promethazine Theoclate

    African Journals Online (AJOL)

    Erah

    tablet containing β-cyclodextrin, crospovidone, and camphor, using direct compression method. A 33 full factorial design ... fast dissolving tablets (FDT) is the use of ... All the raw materials were passed ..... delivery systems: critical review in.

  17. Geographical differences in the relationship between total dissolved ...

    African Journals Online (AJOL)

    on the Department of Water Affairs water quality database. ... Keywords: conversion factors, electrical conductivity, field instruments, rivers, total dissolved solids, water quality ... of a number of TDS:EC ratios in samples where both measure-.

  18. DGT measurement of dissolved aluminum species in waters

    DEFF Research Database (Denmark)

    Panther, Jared G.; Bennett, William W.; Teasdale, Peter R.

    2012-01-01

    Aluminum is acutely toxic, and elevated concentrations of dissolved Al can have detrimental effects on both terrestrial and aquatic ecosystems. Robust analytical methods that can determine environmentally relevant Al fractions accurately and efficiently are required by the environmental monitoring...

  19. Dissolved oxygen (DO) is essential for respiration in aquatic fauna ...

    African Journals Online (AJOL)

    spamer

    more, thermal and salinity stratification inhibits ex- change of ... 2000) and larval densities (Harris and. Cyrus 1999) ...... dissolved oxygen and effects of short-term oxygen stress ... in the shrimp Crangon crangon exposed to hypoxia, anoxia.

  20. Dissolved helium and TDS in groundwater from Bhavnagar in Gujarat

    Indian Academy of Sciences (India)

    R. Narasimhan (Krishtel eMaging) 1461 1996 Oct 15 13:05:22

    2003-01-02

    Jan 2, 2003 ... by enhanced pumping of old groundwater with relatively higher concentration of dissolved helium and salt .... solubility changes due to these (Weiss 1971) can- ... aquifers and relatively low helium concentra- .... permeability.

  1. Removal of both dissolved and particulate iron from groundwater

    OpenAIRE

    H. van Dijk; H. Leijssen; L. Rietveld; A. Abrahamse; K. Teunissen

    2008-01-01

    Iron is the primary source for discolouration problems in the drinking water distribution system. The removal of iron from groundwater is a common treatment step in the production of drinking water. Even when clear water meets the drinking water standards, the water quality in the distribution system can deteriorate due to settling of iron (hydroxide) particles or post-treatment flocculation of dissolved iron. Therefore it is important to remove dissolved and particulate iron to a large exten...

  2. Monte Carlo criticality analysis for dissolvers with neutron poison

    International Nuclear Information System (INIS)

    Yu, Deshun; Dong, Xiufang; Pu, Fuxiang.

    1987-01-01

    Criticality analysis for dissolvers with neutron poison is given on the basis of Monte Carlo method. In Monte Carlo calculations of thermal neutron group parameters for fuel pieces, neutron transport length is determined in terms of maximum cross section approach. A set of related effective multiplication factors (K eff ) are calculated by Monte Carlo method for the three cases. Related numerical results are quite useful for the design and operation of this kind of dissolver in the criticality safety analysis. (author)

  3. Utilizing Colored Dissolved Organic Matter to Derive Dissolved Black Carbon Export by Arctic Rivers

    Science.gov (United States)

    Stubbins, Aron; Spencer, Robert; Mann, Paul; Holmes, R.; McClelland, James; Niggemann, Jutta; Dittmar, Thorsten

    2015-10-01

    Wildfires have produced black carbon (BC) since land plants emerged. Condensed aromatic compounds, a form of BC, have accumulated to become a major component of the soil carbon pool. Condensed aromatics leach from soils into rivers, where they are termed dissolved black carbon (DBC). The transport of DBC by rivers to the sea is a major term in the global carbon and BC cycles. To estimate Arctic river DBC export, 25 samples collected from the six largest Arctic rivers (Kolyma, Lena, Mackenzie, Ob’, Yenisey and Yukon) were analyzed for dissolved organic carbon (DOC), colored dissolved organic matter (CDOM), and DBC. A simple, linear regression between DOC and DBC indicated that DBC accounted for 8.9 ± 0.3% DOC exported by Arctic rivers. To improve upon this estimate, an optical proxy for DBC was developed based upon the linear correlation between DBC concentrations and CDOM light absorption coefficients at 254 nm (a254). Relatively easy to measure a254 values were determined for 410 Arctic river samples between 2004 and 2010. Each of these a254 values was converted to a DBC concentration based upon the linear correlation, providing an extended record of DBC concentration. The extended DBC record was coupled with daily discharge data from the six rivers to estimate riverine DBC loads using the LOADEST modeling program. The six rivers studied cover 53% of the pan-Arctic watershed and exported 1.5 ± 0.1 million tons of DBC per year. Scaling up to the full area of the pan-Arctic watershed, we estimate that Arctic rivers carry 2.8 ± 0.3 million tons of DBC from land to the Arctic Ocean each year. This equates to ~8% of Arctic river DOC export, slightly less than indicated by the simpler DBC vs DOC correlation-based estimate. Riverine discharge is predicted to increase in a warmer Arctic. DBC export was positively correlated with river runoff, suggesting that the export of soil BC to the Arctic Ocean is likely to increase as the Arctic warms.

  4. Utilizing Colored Dissolved Organic Matter to Derive Dissolved Black Carbon Export by Arctic Rivers

    Directory of Open Access Journals (Sweden)

    Aron eStubbins

    2015-10-01

    Full Text Available Wildfires have produced black carbon (BC since land plants emerged. Condensed aromatic compounds, a form of BC, have accumulated to become a major component of the soil carbon pool. Condensed aromatics leach from soils into rivers, where they are termed dissolved black carbon (DBC. The transport of DBC by rivers to the sea is a major term in the global carbon and BC cycles. To estimate Arctic river DBC export, 25 samples collected from the six largest Arctic rivers (Kolyma, Lena, Mackenzie, Ob’, Yenisey and Yukon were analyzed for dissolved organic carbon (DOC, colored dissolved organic matter (CDOM, and DBC. A simple, linear regression between DOC and DBC indicated that DBC accounted for 8.9 ± 0.3% DOC exported by Arctic rivers. To improve upon this estimate, an optical proxy for DBC was developed based upon the linear correlation between DBC concentrations and CDOM light absorption coefficients at 254 nm (a254. Relatively easy to measure a254 values were determined for 410 Arctic river samples between 2004 and 2010. Each of these a254 values was converted to a DBC concentration based upon the linear correlation, providing an extended record of DBC concentration. The extended DBC record was coupled with daily discharge data from the six rivers to estimate riverine DBC loads using the LOADEST modeling program. The six rivers studied cover 53% of the pan-Arctic watershed and exported 1.5 ± 0.1 million tons of DBC per year. Scaling up to the full area of the pan-Arctic watershed, we estimate that Arctic rivers carry 2.8 ± 0.3 million tons of DBC from land to the Arctic Ocean each year. This equates to ~8% of Arctic river DOC export, slightly less than indicated by the simpler DBC vs DOC correlation-based estimate. Riverine discharge is predicted to increase in a warmer Arctic. DBC export was positively correlated with river runoff, suggesting that the export of soil BC to the Arctic Ocean is likely to increase as the Arctic warms.

  5. Dissolved Vanillin as Tracer for Estuarine Lignin Conversion

    Science.gov (United States)

    Edelkraut, F.

    1996-12-01

    Lignin is produced only by vascular plants and therefore can be used as a tracer for terrestrial organic carbon input to the estuarine and marine environments. Lignin measurements have been done by analyses of the oxidation products such as vanillin or 4-hydroxybenzaldehyde. In the Elbe Estuary, free dissolved vanillin was analysed in order to test whether such measurements yield information on terrestrial carbon inputs into the Estuary and on the vanillin derived from lignin oxidation. In the period 1990-1992, concentrations of dissolved vanillin in the Elbe ranged from 0 to 60 μ g l -1(mean: 8 μg l -1). Higher values were found in areas of increased microbial activity such as the turbidity zone and the river mouth where the water chemistry is influenced by large tidal flats. No correlation was found between dissolved vanillin and suspended matter concentrations, although lignin is normally associated with suspended particulate matter, nor was a covariance seen between dissolved vanillin and the terrestrial carbon inputs into the Estuary. Apparently, biological conversion of lignin was faster than the transport processes, and local sources were more dominant for the vanillin concentration than riverine sources. The dissolved vanillin turnover was fast and, consequently, a significant amount of lignin may be converted within an estuary. In sediments from the Estuary, the concentrations of dissolved vanillin were similar to those found in the water phase and showed no clear vertical profile. The sediment is unlikely to be the source for vanillin.

  6. Clarification of dissolved irradiated light-water-reactor fuel

    International Nuclear Information System (INIS)

    Rodrigues, G.C.

    1983-02-01

    Bench-scale studies with actual dissolved irradiated light water reactor (LWR) fuels showed that continuous centrifugation is a practical clarification method for reprocessing. Dissolved irradiated LWR fuel was satisfactorily clarified in a bench-scale, continuous-flow bowl centrifuge. The solids separated were successfully reslurried in water. When the reslurried solids were mixed with clarified centrate, the resulting suspension behaved similar to the original dissolver solution during centrifugation. Settling rates for solids in actual irradiated fuel solutions were measured in a bottle centrifuge. The results indicate that dissolver solutions may be clarified under conditions achievable by available plant-scale centrifuge technology. The effective particle diameter of residual solids was calculated to be 0.064 microns for Oconee-1 fuel and 0.138 microns for Dresden-1 fuel. Filtration was shown unsuitable for clarification of LWR fuel solutions. Conventional filtration with filter aid would unacceptably complicate remote canyon operation and maintenance, might introduce dissolved silica from filter aids, and might irreversibly plug the filter with dissolver solids. Inertial filtration exhibited irreversible pluggage with nonradioactive stand-in suspensions under all conditions tested

  7. Characterization of Urban Runoff Pollution between Dissolved and Particulate Phases

    Science.gov (United States)

    Wei, Zhang; Simin, Li; Fengbing, Tang

    2013-01-01

    To develop urban stormwater management effectively, characterization of urban runoff pollution between dissolved and particulate phases was studied by 12 rainfall events monitored for five typical urban catchments. The average event mean concentration (AEMC) of runoff pollutants in different phases was evaluated. The AEMC values of runoff pollutants in different phases from urban roads were higher than the ones from urban roofs. The proportions of total dissolved solids, total dissolved nitrogen, and total dissolved phosphorus in total ones for all the catchments were 26.19%–30.91%, 83.29%–90.51%, and 61.54–68.09%, respectively. During rainfall events, the pollutant concentration at the initial stage of rainfall was high and then sharply decreased to a low value. Affected by catchments characterization and rainfall distribution, the highest concentration of road pollutants might appear in the later period of rainfall. Strong correlations were also found among runoffs pollutants in different phases. Total suspended solid could be considered as a surrogate for particulate matters in both road and roof runoff, while dissolved chemical oxygen demand could be regarded as a surrogate for dissolved matters in roof runoff. PMID:23935444

  8. Characterization of urban runoff pollution between dissolved and particulate phases.

    Science.gov (United States)

    Wei, Zhang; Simin, Li; Fengbing, Tang

    2013-01-01

    To develop urban stormwater management effectively, characterization of urban runoff pollution between dissolved and particulate phases was studied by 12 rainfall events monitored for five typical urban catchments. The average event mean concentration (AEMC) of runoff pollutants in different phases was evaluated. The AEMC values of runoff pollutants in different phases from urban roads were higher than the ones from urban roofs. The proportions of total dissolved solids, total dissolved nitrogen, and total dissolved phosphorus in total ones for all the catchments were 26.19%-30.91%, 83.29%-90.51%, and 61.54-68.09%, respectively. During rainfall events, the pollutant concentration at the initial stage of rainfall was high and then sharply decreased to a low value. Affected by catchments characterization and rainfall distribution, the highest concentration of road pollutants might appear in the later period of rainfall. Strong correlations were also found among runoffs pollutants in different phases. Total suspended solid could be considered as a surrogate for particulate matters in both road and roof runoff, while dissolved chemical oxygen demand could be regarded as a surrogate for dissolved matters in roof runoff.

  9. On the losses of dissolved CO(2) during champagne serving.

    Science.gov (United States)

    Liger-Belair, Gérard; Bourget, Marielle; Villaume, Sandra; Jeandet, Philippe; Pron, Hervé; Polidori, Guillaume

    2010-08-11

    Pouring champagne into a glass is far from being consequenceless with regard to its dissolved CO(2) concentration. Measurements of losses of dissolved CO(2) during champagne serving were done from a bottled Champagne wine initially holding 11.4 +/- 0.1 g L(-1) of dissolved CO(2). Measurements were done at three champagne temperatures (i.e., 4, 12, and 18 degrees C) and for two different ways of serving (i.e., a champagne-like and a beer-like way of serving). The beer-like way of serving champagne was found to impact its concentration of dissolved CO(2) significantly less. Moreover, the higher the champagne temperature is, the higher its loss of dissolved CO(2) during the pouring process, which finally constitutes the first analytical proof that low temperatures prolong the drink's chill and helps it to retain its effervescence during the pouring process. The diffusion coefficient of CO(2) molecules in champagne and champagne viscosity (both strongly temperature-dependent) are suspected to be the two main parameters responsible for such differences. Besides, a recently developed dynamic-tracking technique using IR thermography was also used in order to visualize the cloud of gaseous CO(2) which flows down from champagne during the pouring process, thus visually confirming the strong influence of champagne temperature on its loss of dissolved CO(2).

  10. Gas-partitioning tracer test to qualify trapped gas during recharge

    Science.gov (United States)

    Heilweil, Victor M.; Kip, Solomon D.; Perkins, Kim S.; Ellett, Kevin M.

    2004-01-01

    Dissolved helium and bromide tracers were used to evaluate trapped gas during an infiltration pond experiment. Dissolved helium preferentially partitioned into trapped gas bubbles, or other pore air, because of its low solubility in water. This produced observed helium retardation factors of as much as 12 relative to bromide. Numerical simulations of helium breakthrough with both equilibrium and kinetically limited advection/dispersion/retardation did not match observed helium concentrations. However, better fits were obtained by including a decay term representing the diffusive loss of helium through interconnected, gas-filled pores. Calculations indicate that 7% to more than 26% of the porosity beneath the pond was filled with gas. Measurements of laboratory hydraulic properties indicate that a 10% decrease in saturation would reduce the hydraulic conductivity by at least one order of magnitude in the well-sorted sandstone, but less in the overlying soils. This is consistent with in situ measurements during the experiment, which show steeper hydraulic gradients in sandstone than in soil. Intrinsic permeability of the soil doubled during the first six months of the experiment, likely caused by a combination of dissolution and thermal contraction of trapped gas. Managers of artificial recharge basins may consider minimizing the amount of trapped gas by using wet, rather than dry, tilling to optimize infiltration rates, particularly in well-sorted porous media in which reintroduced trapped gas may cause substantial reductions in permeability. Trapped gas may also inhibit the amount of focused infiltration that occurs naturally during ephemeral flood events along washes and playas.

  11. Gas-partitioning tracer test to quantify trapped gas during recharge

    Science.gov (United States)

    Heilweil, V.M.; Solomon, D.K.; Perkins, K.S.; Ellett, K.M.

    2004-01-01

    Dissolved helium and bromide tracers were used to evaluate trapped gas during an infiltration pond experiment. Dissolved helium preferentially partitioned into trapped gas bubbles, or other pore air, because of its low solubility in water. This produced observed helium retardation factors of as much as 12 relative to bromide. Numerical simulations of helium breakthrough with both equilibrium and kinetically limited advection/dispersion/retardation did not match observed helium concentrations. However, better fits were obtained by including a decay term representing the diffusive loss of helium through interconnected, gas-filled pores. Calculations indicate that 7% to more than 26% of the porosity beneath the pond was filled with gas. Measurements of laboratory hydraulic properties indicate that a 10% decrease in saturation would reduce the hydraulic conductivity by at least one order of magnitude in the well-sorted sandstone, but less in the overlying soils. This is consistent with in situ measurements during the experiment, which show steeper hydraulic gradients in sandstone than in soil. Intrinsic permeability of the soil doubled during the first six months of the experiment, likely caused by a combination of dissolution and thermal contraction of trapped gas. Managers of artificial recharge basins may consider minimizing the amount of trapped gas by using wet, rather than dry, tilling to optimize infiltration rates, particularly in well-sorted porous media in which reintroduced trapped gas may cause substantial reductions in permeability. Trapped gas may also inhibit the amount of focused infiltration that occurs naturally during ephemeral flood events along washes and playas.

  12. Role of dissolved oxygen on the degradation mechanism of Reactive Green 19 and electricity generation in photocatalytic fuel cell.

    Science.gov (United States)

    Lee, Sin-Li; Ho, Li-Ngee; Ong, Soon-An; Wong, Yee-Shian; Voon, Chun-Hong; Khalik, Wan Fadhilah; Yusoff, Nik Athirah; Nordin, Noradiba

    2018-03-01

    In this study, a membraneless photocatalytic fuel cell with zinc oxide loaded carbon photoanode and platinum loaded carbon cathode was constructed to investigate the impact of dissolved oxygen on the mechanism of dye degradation and electricity generation of photocatalytic fuel cell. The photocatalytic fuel cell with high and low aeration rate, no aeration and nitrogen purged were investigated, respectively. The degradation rate of diazo dye Reactive Green 19 and the electricity generation was enhanced in photocatalytic fuel cell with higher dissolved oxygen concentration. However, the photocatalytic fuel cell was still able to perform 37% of decolorization in a slow rate (k = 0.033 h -1 ) under extremely low dissolved oxygen concentration (approximately 0.2 mg L -1 ) when nitrogen gas was introduced into the fuel cell throughout the 8 h. However, the change of the UV-Vis spectrum indicates that the intermediates of the dye could not be mineralized under insufficient dissolved oxygen level. In the aspect of electricity generation, the maximum short circuit current (0.0041 mA cm -2 ) and power density (0.00028 mW cm -2 ) of the air purged photocatalytic fuel cell was obviously higher than that with nitrogen purging (0.0015 mA cm -2 and 0.00008 mW cm -2 ). Copyright © 2017 Elsevier Ltd. All rights reserved.

  13. Paleotemperatures derived from noble gases dissolved in groundwater and in relation to soil temperature

    International Nuclear Information System (INIS)

    Stute, M.; Sonntag, C.

    1992-01-01

    Measurements of He, Ne, Ar, Kr and Xe dissolved in groundwater at two sites (Bocholt, Germany, and the Great Hungarian Plain) were taken to prove the reliability of noble gas temperatures as indicators of paleotemperatures. Noble gas temperatures of groundwater of Holocene age were found to reflect the annual mean soil temperature in the recharge are with an accuracy close to the precision of measurement (1σ approx. ±0.5 deg. C). Noble gas temperature data demonstrate the influence of vegetation cover on the soil temperature in the infiltration area. Groundwater formed in forests at the Bocholt site shows noble gas temperatures that are 2.2 deg. C lower than the groundwater formed in fields or meadows. The temperature data obtained from groundwater of the Great Hungarian Plain for the last glaciation are ≥ 8.6 deg. C lower than data from recent groundwater for maximum glaciation (approx. 18,000 years ago) and 4.7 ± 1 deg. C lower for the preceding interstadial (approx. 28,000-35,000 years ago). These data permit independent reconstruction of paleoclimatic conditions. (author). 19 refs, 3 figs, 1 tab

  14. Sources and transformations of dissolved lignin phenols and chromophoric dissolved organic matter in Otsuchi Bay, Japan

    Directory of Open Access Journals (Sweden)

    Chia-Jung eLu

    2016-06-01

    Full Text Available Dissolved lignin phenols and optical properties of dissolved organic matter (DOM were measured to investigate the sources and transformations of terrigenous DOM (tDOM in Otsuchi Bay, Japan. Three rivers discharge into the bay, and relatively high values of syringyl:vanillyl phenols (0.73 ± 0.07 and cinnamyl:vanillyl phenols (0.33 ± 0.10 indicated large contributions of non-woody angiosperm tissues to lignin and tDOM. The physical mixing of river and seawater played an important role in controlling the concentrations and distributions of lignin phenols and chromophoric DOM (CDOM optical properties in the bay. Lignin phenol concentrations and the CDOM absorption coefficient at 350 nm, a(350, were strongly correlated in river and bay waters. Measurements of lignin phenols and CDOM in bay waters indicated a variety of photochemical and biological transformations of tDOM, including oxidation reactions, photobleaching and a decrease in molecular weight. Photodegradation and biodegradation of lignin and CDOM were investigated in decomposition experiments with river water and native microbial assemblages exposed to natural sunlight or kept in the dark. There was a rapid and substantial removal of lignin phenols and CDOM during the first few days in the light treatment, indicating transformations of tDOM and CDOM can occur soon after discharge of buoyant river water into the bay. The removal of lignin phenols was slightly greater in the dark (34% than in the light (30% during the remaining 59 days of the incubation. Comparison of the light and dark treatments indicated biodegradation was responsible for 67% of total lignin phenol removal during the 62-day incubation exposed to natural sunlight, indicating biodegradation is a dominant removal process in Otsuchi Bay.

  15. Diffusion Study on Dissolved Hydrogen toward Effective Bioremediation of Chlorinated Ethenes in Aquitards

    Science.gov (United States)

    Yoshikawa, M.; Zhang, M.; Takeuchi, M.; Komai, T.

    2010-12-01

    In Japan, the demand for in-situ remediation of contaminated sediments is expected to increase in the future due to the recent amendment of Soil Contamination Countermeasures Act. The Japanese law requires remediating not only contaminated groundwater but also contaminated sediments including those in aquitards. In-situ remediation of contaminated aquitards has been a challenging issue and bioremediation is considered to be one of the effective techniques. In microbial degradation of chrolinated ethenes such as tetrachloroethene and trichloroethene under anaerobic environments, dissolved hydrogen plays an important role. The dechlorinating microbes utilize hydrogen and chlorinated ethenes as an electron donor and an electron accepter, respectively. The size of hydrogen molecule is extremely small and the diffusion rate of dissolved hydrogen in an aquitard would be the key factor that controls the process of microbial dechlorination. However, the diffusion behavior of dissolved hydrogen in subsurface sediments remains unclear. The purposes of this study are to develop a practically utilizable test apparatus, carry out a series of dissolved hydrogen diffusion tests on representative samples, and illustrate the applicability of bioremediation in aquitards. A completely leak-free apparatus was developed by using aluminum alloy and gas tight rubber. This apparatus is capable of testing specimens with a diameter as large as 100 mm by a length from 5 mm to 10 mm, depending on the maximum grain size within a test specimen. Preliminary tests have been performed with glass beads as an ideal material, commercially available kaolin clay, and core samples taken from a polluted site containing clay minerals. The effective diffusion coefficients of these samples were all on the order of 10E-10 m2/s, though their coefficients of permeability varied between the orders of 10E-2 and 10E-7 cm/s. These results showed that there was no obvious relationship between the effective

  16. A detailed analysis of the energy levels configuration existing in the band gap of supersaturated silicon with titanium for photovoltaic applications

    Energy Technology Data Exchange (ETDEWEB)

    Pérez, E.; Dueñas, S.; Castán, H.; García, H.; Bailón, L. [Dept. de Electricidad y Electrónica, Universidad de Valladolid, Paseo de Belén 15, 47011 Valladolid (Spain); Montero, D.; García-Hernansanz, R.; García-Hemme, E.; González-Díaz, G. [Dept. de Física Aplicada III (Electricidad y Electrónica), Univ. Complutense de Madrid, 28040 Madrid (Spain); CEI Campus Moncloa, UCM-UPM, 28040 Madrid (Spain); Olea, J. [CEI Campus Moncloa, UCM-UPM, 28040 Madrid (Spain); Instituto de Energía Solar, E.T.S.I. de Telecomunicación, Univ. Politécnica de Madrid, 28040 Madrid (Spain)

    2015-12-28

    The energy levels created in supersaturated n-type silicon substrates with titanium implantation in the attempt to create an intermediate band in their band-gap are studied in detail. Two titanium ion implantation doses (10{sup 13 }cm{sup -2} and 10{sup 14 }cm{sup -2}) are studied in this work by conductance transient technique and admittance spectroscopy. Conductance transients have been measured at temperatures of around 100 K. The particular shape of these transients is due to the formation of energy barriers in the conduction band, as a consequence of the band-gap narrowing induced by the high titanium concentration. Moreover, stationary admittance spectroscopy results suggest the existence of different energy level configuration, depending on the local titanium concentration. A continuum energy level band is formed when titanium concentration is over the Mott limit. On the other hand, when titanium concentration is lower than the Mott limit, but much higher than the donor impurity density, a quasi-continuum energy level distribution appears. Finally, a single deep center appears for low titanium concentration. At the n-type substrate, the experimental results obtained by means of thermal admittance spectroscopy at high reverse bias reveal the presence of single levels located at around E{sub c}-425 and E{sub c}-275 meV for implantation doses of 10{sup 13 }cm{sup −2} and 10{sup 14 }cm{sup −2}, respectively. At low reverse bias voltage, quasi-continuously distributed energy levels between the minimum of the conduction bands, E{sub c} and E{sub c}-450 meV, are obtained for both doses. Conductance transients detected at low temperatures reveal that the high impurity concentration induces a band gap narrowing which leads to the formation of a barrier in the conduction band. Besides, the relationship between the activation energy and the capture cross section values of all the energy levels fits very well to the Meyer-Neldel rule. As it is known

  17. Sulfate but not thiosulfate reduces calculated and measured urinary ionized calcium and supersaturation: implications for the treatment of calcium renal stones.

    Directory of Open Access Journals (Sweden)

    Allen Rodgers

    Full Text Available Urinary sulfate (SO4(2- and thiosulfate (S2O3(2- can potentially bind with calcium and decrease kidney stone risk. We modeled the effects of these species on the concentration of ionized calcium (iCa and on supersaturation (SS of calcium oxalate (CaOx and calcium phosphate (CaP, and measured their in vitro effects on iCa and the upper limit of stability (ULM of these salts.Urine data from 4 different types of stone patients were obtained from the Mayo Nephrology Clinic (Model 1. A second data set was obtained from healthy controls and hypercalciuric stone formers in the literature who had been treated with sodium thiosulfate (STS (Model 2. The Joint Expert Speciation System (JESS was used to calculate iCa and SS. In Model 1, these parameters were calculated as a function of sulfate and thiosulfate concentrations. In Model 2, data from pre- and post STS urines were analyzed. ULM and iCa were determined in human urine as a function of sulfate and thiosulfate concentrations.Calculated iCa and SS values for all calcium salts decreased with increasing sulfate concentration. Thiosulfate had no effect on these parameters. In Model 2, calculated iCa and CaOx SS increased after STS treatment, but CaP SS decreased, perhaps due to a decrease in pH after STS treatment. In confirmatory in vitro experiments supplemental sulfate, but not thiosulfate, significantly increased the calcium needed to achieve the ULM of CaP and tended to increase the oxalate needed to reach the ULM of CaOx. Sulfate also significantly decreased iCa in human urine, while thiosulfate had no effect.Increasing urinary sulfate could theoretically reduce CaOx and CaP stone risk. Although STS may reduce CaP stone risk by decreasing urinary pH, it might also paradoxically increase iCa and CaOx SS. As such, STS may not be a viable treatment option for stone disease.

  18. Absorption features of chromophoric dissolved organic matter (CDOM) and tracing implication for dissolved organic carbon (DOC) in Changjiang Estuary, China

    OpenAIRE

    Zhang, X. Y.; Chen, X.; Deng, H.; Du, Y.; Jin, H. Y.

    2013-01-01

    Chromophoric dissolved organic matter (CDOM) represents the light absorbing fraction of dissolved organic carbon (DOC). Studies have shown that the optical properties of CDOM can be used to infer the distribution and diffusion characteristics of DOC in the estuary and coastal zone. The inversion of DOC concentrations from remote sensing has been implemented in certain regions. In this study we investigate the potential of tracing DOC from CDOM by the measure...

  19. Relationships between colored dissolved organic matter and dissolved organic carbon in different coastal gradients of the Baltic Sea

    OpenAIRE

    Harvey, E. Therese; Kratzer, Susanne; Andersson, Agneta

    2015-01-01

    Due to high terrestrial runoff, the Baltic Sea is rich in dissolved organic carbon (DOC), the light-absorbing fraction of which is referred to as colored dissolved organic matter (CDOM). Inputs of DOC and CDOM are predicted to increase with climate change, affecting coastal ecosystems. We found that the relationships between DOC, CDOM, salinity, and Secchi depth all differed between the two coastal areas studied; the W Gulf of Bothnia with high terrestrial input and the NW Baltic Proper with ...

  20. The Effect of Rain on Air-Water Gas Exchange

    Science.gov (United States)

    Ho, David T.; Bliven, Larry F.; Wanninkhof, Rik; Schlosser, Peter

    1997-01-01

    The relationship between gas transfer velocity and rain rate was investigated at NASA's Rain-Sea Interaction Facility (RSIF) using several SF, evasion experiments. During each experiment, a water tank below the rain simulator was supersaturated with SF6, a synthetic gas, and the gas transfer velocities were calculated from the measured decrease in SF6 concentration with time. The results from experiments with IS different rain rates (7 to 10 mm/h) and 1 of 2 drop sizes (2.8 or 4.2 mm diameter) confirm a significant and systematic enhancement of air-water gas exchange by rainfall. The gas transfer velocities derived from our experiment were related to the kinetic energy flux calculated from the rain rate and drop size. The relationship obtained for mono-dropsize rain at the RSIF was extrapolated to natural rain using the kinetic energy flux of natural rain calculated from the Marshall-Palmer raindrop size distribution. Results of laboratory experiments at RSIF were compared to field observations made during a tropical rainstorm in Miami, Florida and show good agreement between laboratory and field data.

  1. Detection of Dissolved Carbon Monoxide in Transformer Oil Using 1.567 μm Diode Laser-Based Photoacoustic Spectroscopy

    Directory of Open Access Journals (Sweden)

    Qu Zhou

    2015-01-01

    Full Text Available Carbon monoxide (CO is one of the most important fault characteristic gases dissolved in power transformer oil. With the advantages of high sensitivity and accuracy, long-term stability, and short detection time, photoacoustic spectroscopy (PAS has been proven to be one promising sensing technology for trace gas recognition. In this investigation, a tunable PAS experimental system based on a distributed-feedback (DFB diode laser was proposed for recognizing dissolved CO in transformer oil. The molecular spectral line of CO gas detection was selected at 1.567 μm in the whole experiment. Relationships between the photoacoustic (PA signal and gas pressure, temperature, laser power, and CO gas concentration were measured and discussed in detail, respectively. Finally, based on the least square regression theory, a novel quantitative identification method for CO gas detection with the PAS experimental system was proposed. And a comparative research about the gas detection performances performed by the PAS system and gas chromatography (GC measurement was presented. All results lay a solid foundation for exploring a portable and tunable CO gas PAS detection device for practical application in future.

  2. Continuous in-situ monitoring of dissolved gases for the characterization of the Critical Zone with a MIMS

    Science.gov (United States)

    Chatton, Eliot; Labasque, Thierry; Aquilina, Luc; de la Bernardie, Jérôme; Guihéneuf, Nicolas

    2016-04-01

    In the perspective of a temporal and spatial exploration of the Critical Zone, we developed an in situ monitoring instrument for continuous dissolved gas analysis (N2, O2, CO2, CH4, He, Ne, Ar, Kr, Xe). With a large resolution (5 orders of magnitude) and a capability of high frequency multi-tracer analysis (1 gas every 1.5 seconds), the MIMS (Membrane Inlet Mass Spectrometer) is an innovative tool allowing the investigation of a large panel of physical and biogeochemical processes. First of all, this study presents the results of groundwater tracer tests using dissolved gases in order to evaluate transport properties of a fractured media in Brittany, France (Ploemeur, ORE H+). The tracer test experiment showed that the MIMS is perfectly suitable for field work. The instrument provides precise measurements accurate enough to produce breakthrough curves during groundwater tracer tests. The results derived from 4He data gives transport parameters in good agreement with the results obtained with a fluorescent tracer. Combined with a pump and a multi-parameter probe, the MIMS is also capable to perform accurate dissolved gases well-logs allowing a real-time estimation of recharge conditions (temperature, excess air), aquifer stratification, redox conditions and groundwater residence time by 4He dating. Therefore, the MIMS is a valuable tool for in situ characterization of biogeochemical reactivity in aquatic systems, the determination of aquifer transport properties, the monitoring of groundwater recharge conditions and the characterization of aquifer-river exchanges.

  3. On aerosol hygroscopicity, cloud condensation nuclei (CCN spectra and critical supersaturation measured at two remote islands of Korea between 2006 and 2009

    Directory of Open Access Journals (Sweden)

    J. H. Kim

    2011-12-01

    Full Text Available Aerosol size distribution, total concentration (i.e. condensation nuclei (CN concentration, NCN, cloud condensation nuclei (CCN concentration (NCCN, hygroscopicity at ~90% relative humidity (RH were measured at a background monitoring site at Gosan, Jeju Island, south of the Korean Peninsula in August 2006, April to May 2007 and August to October 2008. Similar measurements took place in August 2009 at another background site (Baengnyeongdo Comprehensive Monitoring Observatory, BCMO on the island of Baengnyeongdo, off the west coast of the Korean Peninsula. Both islands were found to be influenced by continental sources regardless of season and year. Average values for all of the measured NCCN at 0.2, 0.6 and 1.0% supersaturations (S, NCN, and geometric mean diameter (Dg from both islands were in the range of 1043–3051 cm−3, 2076–4360 cm−3, 2713–4694 cm−3, 3890–5117 cm−3 and 81–98 nm, respectively. Although the differences in Dg and NCN were small between Gosan and BCMO, NCCN at various S was much higher at the latter, which is closer to China.

    Most of the aerosols were internally mixed and no notable differences in hygroscopicity were found between the days of strong pollution influence and the non-pollution days for both islands. During the 2008 and 2009 campaigns, critical supersaturation for CCN nucleation (Sc for selected particle sizes was measured. Particles of 100 nm diameters had mean Sc of 0.19 ± 0.02% during 2008 and those of 81 and 110 nm diameters had mean Sc of 0.26 ± 0.07% and 0.17 ± 0.04%, respectively, during 2009. The values of the hygroscopicity parameter (κ, estimated from measured Sc, were mostly higher than the κ values

  4. GAS BEARING

    Science.gov (United States)

    Skarstrom, C.W.

    1960-09-01

    A gas lubricated bearing for a rotating shaft is described. The assembly comprises a stationary collar having an annular member resiliently supported thereon. The collar and annular member are provided with cooperating gas passages arranged for admission of pressurized gas which supports and lubricates a bearing block fixed to the rotatable shaft. The resilient means for the annular member support the latter against movement away from the bearing block when the assembly is in operation.

  5. Requirements for gas quality and gas appliances

    NARCIS (Netherlands)

    Levinsky, Howard; Gersen, Sander; Kiewiet, Bert

    2015-01-01

    Introduction The gas transmission network in the Netherlands transports two different qualities of gas, low-calorific gas known as G-gas or L-gas and, high calorific gas (H-gas). These two gas qualities are transported in separate networks, and are connected by means of five blending and conversion

  6. Gas magnetometer

    Science.gov (United States)

    Walker, Thad Gilbert; Lancor, Brian Robert; Wyllie, Robert

    2016-05-03

    Measurement of a precessional rate of a gas, such as an alkali gas, in a magnetic field is made by promoting a non-uniform precession of the gas in which substantially no net magnetic field affects the gas during a majority of the precession cycle. This allows sensitive gases that would be subject to spin-exchange collision de-phasing to be effectively used for extremely sensitive measurements in the presence of an environmental magnetic field such as the Earth's magnetic field.

  7. Gas separating

    Science.gov (United States)

    Gollan, A.

    1988-03-29

    Feed gas is directed tangentially along the non-skin surface of gas separation membrane modules comprising a cylindrical bundle of parallel contiguous hollow fibers supported to allow feed gas to flow from an inlet at one end of a cylindrical housing through the bores of the bundled fibers to an outlet at the other end while a component of the feed gas permeates through the fibers, each having the skin side on the outside, through a permeate outlet in the cylindrical casing. 3 figs.

  8. DEVELOPMENT OF FUZZY NEURAL NETWORK FOR THE INTERPRETATION OF THE RESULTS OF DISSOLVED IN OIL GASES ANALYSIS

    Directory of Open Access Journals (Sweden)

    V.Е. Bondarenko

    2017-04-01

    Full Text Available Purpose. The purpose of this paper is a diagnosis of power transformers on the basis of the results of the analysis of gases dissolved in oil. Methodology. To solve this problem a fuzzy neural network has been developed, tested and trained. Results. The analysis of neural network to recognize the possibility of developing defects at an early stage of their development, or growth of gas concentrations in the healthy transformers, made after the emergency actions on the part of electric networks is made. It has been established greatest difficulty in making a diagnosis on the criterion of the boundary gas concentrations, are the results of DGA obtained for the healthy transformers in which the concentration of gases dissolved in oil exceed their limit values, as well as defective transformers at an early stage development defects. The analysis showed that the accuracy of recognition of fuzzy neural networks has its limitations, which are determined by the peculiarities of the DGA method, used diagnostic features and the selected decision rule. Originality. Unlike similar studies in the training of the neural network, the membership functions of linguistic terms were chosen taking into account the functions gas concentrations density distribution transformers with various diagnoses, allowing to consider a particular gas content of oils that are typical of a leaky transformer, and the operating conditions of the equipment. Practical value. Developed fuzzy neural network allows to perform diagnostics of power transformers on the basis of the result of the analysis of gases dissolved in oil, with a high level of reliability.

  9. Leaching of dissolved phosphorus from tile-drained agricultural areas.

    Science.gov (United States)

    Andersen, H E; Windolf, J; Kronvang, B

    2016-01-01

    We investigated leaching of dissolved phosphorus (P) from 45 tile-drains representing animal husbandry farms in all regions of Denmark. Leaching of P via tile-drains exhibits a high degree of spatial heterogeneity with a low concentration in the majority of tile-drains and few tile-drains (15% in our investigation) having high to very high concentration of dissolved P. The share of dissolved organic P (DOP) was high (up to 96%). Leaching of DOP has hitherto been a somewhat overlooked P loss pathway in Danish soils and the mechanisms of mobilization and transport of DOP needs more investigation. We found a high correlation between Olsen-P and water extractable P. Water extractable P is regarded as an indicator of risk of loss of dissolved P. Our findings indicate that Olsen-P, which is measured routinely in Danish agricultural soils, may be a useful proxy for the P leaching potential of soils. However, we found no straight-forward correlation between leaching potential of the top soil layer (expressed as either degree of P saturation, Olsen-P or water extractable P) and the measured concentration of dissolved P in the tile-drain. This underlines that not only the source of P but also the P loss pathway must be taken into account when evaluating the risk of P loss.

  10. Monitoring dissolved radioactive cesium in Abukuma River in Fukushima Prefecture

    International Nuclear Information System (INIS)

    Yasutaka, Tetsuo; Kawabe, Yoshishige; Kurosawa, Akihiko; Komai, Takeshi

    2013-01-01

    Radioactive materials were released into the atmosphere and deposited over wide areas of farmland, forests, and cities; elevated levels of "1"3"1I, "1"3"4Cs, and "1"3"7Cs have been detected in these areas due to the accident at the Tokyo Power Fukushima Daiichi Nuclear Power Plant caused by the April 2011 earthquake and tsunami in eastern Japan. Radioactive Cs deposited on farmland and forests gradually leaches into water bodies such as mountain streams and rivers adsorbed onto particles or in a dissolved state. It is important to calrify the level of dissolved and total radioactive Cs in environmental water for forecasting the of discharge of radioactive Cs from forest and watersheds, assessing on the effect of dissolved and total radioactive Cs on not only irrigation water but also rice and other crops, and evaluating the transport of radioactive Cs from rivers to costal areas. Therefore, it is important to monitor their levels in Fukushima Prefecture over time. In this research, we monitored the levels of dissolved and total radioactive Cs in Abukuma River using a conventional evaporative concentration method. By monitoring the river waters since September 2012, it was estimated that the levels of dissolved radioactive Cs were less than 0.128 Bq/L and those of total radioactive Cs were less than 0.274 Bq/L in the main stream and branches of Abukuma River in the low suspended solid condition. (author)

  11. Dissolving Microneedle Patch for Transdermal Delivery of Human Growth Hormone

    Science.gov (United States)

    Lee, Jeong Woo; Choi, Seong-O; Felner, Eric I.

    2014-01-01

    Clinical impact of biotechnology has been constrained by the limitations of traditional hypodermic injection of biopharmaceuticals. Microneedle patches have been proposed as a minimally invasive alternative. In this study, we assess the translation of a dissolving microneedle patch designed for simple, painless self-administration of biopharmacetucials that generates no sharp biohazardous waste. To study pharmacokinetics and safety of this approach, human growth hormone (hGH) was encapsulated in 600 μm long dissolving microneedles composed of carboxymethylcellulose and trehalose using an aqueous, moderate-temperature process that maintained complete hGH activity after encapsulation and retained most activity after storage for up to 15 months at room temperature and humidity. After manual insertion into the skin of hairless rats, hGH pharmacokinetics were similar to conventional subcutaneous injection. After patch removal, the microneedles had almost completely dissolved, leaving behind only blunt stubs. The dissolving microneedle patch was well tolerated, causing only slight, transient erythema. This study suggests that a dissolving microneedle patch can deliver hGH and other biopharmaceuticals in a manner suitable for self-administration without sharp biohazardous waste. PMID:21360810

  12. One-dimensional simulation of stratification and dissolved oxygen in McCook Reservoir, Illinois

    Science.gov (United States)

    Robertson, Dale M.

    2000-01-01

    As part of the Chicagoland Underflow Plan/Tunnel and Reservoir Plan, the U.S. Army Corps of Engineers, Chicago District, plans to build McCook Reservoir.a flood-control reservoir to store combined stormwater and raw sewage (combined sewage). To prevent the combined sewage in the reservoir from becoming anoxic and producing hydrogen sulfide gas, a coarse-bubble aeration system will be designed and installed on the basis of results from CUP 0-D, a zero-dimensional model, and MAC3D, a three-dimensional model. Two inherent assumptions in the application of MAC3D are that density stratification in the simulated water body is minimal or not present and that surface heat transfers are unimportant and, therefore, may be neglected. To test these assumptions, the previously tested, one-dimensional Dynamic Lake Model (DLM) was used to simulate changes in temperature and dissolved oxygen in the reservoir after a 1-in-100-year event. Results from model simulations indicate that the assumptions made in MAC3D application are valid as long as the aeration system, with an air-flow rate of 1.2 cubic meters per second or more, is operated while the combined sewage is stored in the reservoir. Results also indicate that the high biochemical oxygen demand of the combined sewage will quickly consume the dissolved oxygen stored in the reservoir and the dissolved oxygen transferred through the surface of the reservoir; therefore, oxygen must be supplied by either the rising bubbles of the aeration system (a process not incorporated in DLM) or some other technique to prevent anoxia.

  13. Manure gas

    Energy Technology Data Exchange (ETDEWEB)

    Carre, I

    1947-05-01

    A short description of the process is given, with gas yields from various feedstocks, and the composition of the gas. Short descriptions of several batch digester designs are given: Algerian, Salubra, Betur, Baudot-Hardoll and Ofta, and Somagaz. The utilization and the economics of the process are discussed. Two diagrams of Ducellier and Isman designs are included.

  14. Dissolved organic carbon and dissolved organic nitrogen data collected using bottle in a world wide distribution from 02 September 1998 to 02 November 2003 (NODC Accession 0002403)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Dissolved organic carbon (DOC) and dissolved organic nitrogen (DON) data were collected using bottle casts in a world wide distribution. Data were collected from 02...

  15. Landfill gas

    International Nuclear Information System (INIS)

    Hartnell, Gaynor

    2000-01-01

    Following the UK Government's initiative for stimulating renewable energy through the Non-Fossil Fuel Obligation (NFFO), the UK landfill gas industry has more than trebled in size in just 4 years. As a result, UK companies are now in a strong position to offer their skills and services overseas. Ireland, Greece and Spain also resort heavily to disposal to landfill. Particularly rapid growth of the landfill gas market is expected in the OECD-Pacific and NAFTA areas. The article explains that landfill gas is a methane-rich mixture produced by anaerobic decomposition of organic wastes in landfills: under optimum conditions, up to 500 cubic meters of gas can be obtained from 1 tonne of biodegradable waste. Data on the number and capacity of sites in the UK are given. The Landfill Gas Association runs courses to counteract the skills shortage in the UK, and tailored courses for overseas visitors are planned

  16. Dissolved oxygen removal in a column packed with catalyst

    International Nuclear Information System (INIS)

    Lee, Han Soo; Chung, Hong Suk; Cho, Young Hyun; Ahn, Do Hee; Kim, Eun Kee

    1996-01-01

    The dissolved oxygen removed by H 2 -O 2 reaction in column packed with various catalysts was examined. The catalysts employed were the prepared polymeric catalyst, platinum on activated carbon, and Lewatit OC-1045 which is available commercially. The column experiments with the prepared polymeric catalyst showed the dissolved oxygen reduced to 35 ppb which is below the limit in feel water of power plants. This implies the likely application of the prepared catalyst for practical use. The activated carbon required the pre-treatment for the removed of dissolved oxygen, since the surface of activated carbon contains much oxygen adsorbed initially. The Lewatit catalyst exposed the best performance, however, the aged one showed the gradual loss of catalytic activity due to degradation of resin catalyst. 14 refs., 6 figs., 2 tabs. (author)

  17. A low-cost, portable optical sensing system with wireless communication compatible of real-time and remote detection of dissolved ammonia

    Science.gov (United States)

    Deng, Shijie; Doherty, William; McAuliffe, Michael AP; Salaj-Kosla, Urszula; Lewis, Liam; Huyet, Guillaume

    2016-06-01

    A low-cost and portable optical chemical sensor based ammonia sensing system that is capable of detecting dissolved ammonia up to 5 ppm is presented. In the system, an optical chemical sensor is designed and fabricated for sensing dissolved ammonia concentrations. The sensor uses eosin as the fluorescence dye which is immobilized on the glass substrate by a gas-permeable protection layer. A compact module is developed to hold the optical components, and a battery powered micro-controller system is designed to read out and process the data measured. The system operates without the requirement of laboratory instruments that makes it cost effective and highly portable. Moreover, the calculated results in the system can be transmitted to a PC wirelessly, which allows the remote and real-time monitoring of dissolved ammonia.

  18. The hydrodynamics of segmented two-phase flow in a circular tube with rapidly dissolving drops.

    Science.gov (United States)

    Leary, Thomas F; Ramachandran, Arun

    2017-05-03

    This article discusses boundary integral simulations of dissolving drops flowing through a cylindrical tube for large aspect ratio drops. The dynamics of drop dissolution is determined by three dimensionless parameters: λ, the viscosity of the drop fluid relative to the suspending fluid; Ca, the capillary number defining the ratio of the hydrodynamic force to the interfacial tension force; and k, a dissolution constant based on the velocity of dissolution. For a single dissolving drop, the velocity in the upstream region is greater than the downstream region, and for sufficiently large k, the downstream velocity can be completely reversed, particularly at low Ca. The upstream end of the drop travels faster and experiences greater deformation than the downstream end. The film thickness, δ, between the drop and the tube wall is governed by a delicate balance between dissolution and changes in the outer fluid velocity resulting from a fixed pressure drop across the tube and mass continuity. Therefore, δ, and consequently, the drop average velocity, can increase, decrease or be relatively invariant in time. For two drops flowing in succession, while low Ca drops maintain a nearly constant separation distance during dissolution, at sufficiently large Ca, for all values of k, dissolution increases the separation distance between drops. Under these conditions, the liquid segments between two adjacent drops can no longer be considered as constant volume stirred tanks. These results will guide the choices of geometry and operating parameters that will facilitate the characterization of fast gas-liquid reactions via two-phase segmented flows.

  19. Echo-planar MR imaging of dissolved hyperpolarized 129Xe. Potential for M angiography

    International Nuclear Information System (INIS)

    Maansson, S.

    2002-01-01

    Purpose: The feasibility of hyperpolarized 129 Xe for fast MR angiography (MRA) was evaluated using the echo-planar imaging (EPI) technique. Material and Methods: Hyperpolarized Xe gas was dissolved in ethanol; a carrier agent with high solubility for Xe (Ostwald solubility coefficient 2.5) and long relaxation times. The dissolved Xe was injected as a bolus into a flow phantom where the mean flow velocity was 15 cm/s. Ultrafast EPI images with 44 ms scan time were acquired of the flowing bolus and the signal-to-noise ratios (SNR) were measured. Results: The relaxation times of hyperpolarized Xe in ethanol were measured to T1=160±11 s and T2 ≅ 20 s. The resulting images of the flowing liquid were of reasonable quality and had an SNR of about 70. Conclusion: Based on the SNR of the obtained Xe EPI images; it was estimated that rapid in vivo MRA with 129 Xe may be feasible; provided that an efficient; biologically acceptable carrier for Xe can be found and polarization levels of more than 25% can be achieved in isotopically enriched 129 Xe

  20. Relation between the amount of dissolved water and metals dissolved from stainless steel or aluminum plate in safflower oil

    Energy Technology Data Exchange (ETDEWEB)

    Takasago, Masahisa; Takaoka, Kyo

    1986-12-01

    The amount of water dissolved in safflower oil at the frying temperature (180 deg C) was 518 -- 1012 ppM, allowing water to drop continuously (0.035 g/2 min) into the oil for 1 -- 3 h. When the oil was heated with metal plates under the same conditions, the amount of dissolved water in the oil increased more than in the absence of the metal plates. In case of stainless steel, the amount was 1.26 to 1.33 times, and with aluminum plates, 1.06 to 1.13 times the amount without plates. When these metal plates were heated with the oil under the above conditions, the water dissolved the metal of the plates into the oil. In case of stainless steel, iron dissolved from 0.17 to 0.77 ppM, nickel, 0.04 ppM and chromium, from 0.02 to 0.03 ppM. Similarly, the amount of aluminum dissolved from the aluminum plate was from 0.10 to 0.45 ppM.

  1. The relation between the amount of dissolved water and metals dissolved from stainless steel or aluminum plate in safflower oil

    International Nuclear Information System (INIS)

    Takasago, Masahisa; Takaoka, Kyo

    1986-01-01

    The amount of water dissolved in safflower oil at the frying temperature (180 deg C) was 518 ∼ 1012 ppm, allowing water to drop continuously (0.035 g/2 min) into the oil for 1 ∼ 3 h. When the oil was heated with metal plates under the same conditions, the amount of dissolved water in the oil increased more than in the absence of the metal plates. In case of stainless steel, the amount was 1.26 to 1.33 times, and with aluminum plates, 1.06 to 1.13 times the amount without plates. When these metal plates were heated with the oil under the above conditions, the water dissolved the metal of the plates into the oil. In case of stainless steel, iron dissolved from 0.17 to 0.77 ppm, nickel, 0.04 ppm and chromium, from 0.02 to 0.03 ppm. Similarly, the amount of aluminum dissolved from the aluminum plate was from 0.10 to 0.45 ppm. (author)

  2. Effects of dissolved organic matter from a eutrophic lake on the freely dissolved concentrations of emerging organic contaminants.

    Science.gov (United States)

    Xiao, Yi-Hua; Huang, Qing-Hui; Vähätalo, Anssi V; Li, Fei-Peng; Chen, Ling

    2014-08-01

    The authors studied the effects of dissolved organic matter (DOM) on the bioavailability of bisphenol A (BPA) and chloramphenicol by measuring the freely dissolved concentrations of the contaminants in solutions containing DOM that had been isolated from a mesocosm in a eutrophic lake. The abundance and aromaticity of the chromophoric DOM increased over the 25-d mesocosm experiment. The BPA freely dissolved concentration was 72.3% lower and the chloramphenicol freely dissolved concentration was 56.2% lower using DOM collected on day 25 than using DOM collected on day 1 of the mesocosm experiment. The freely dissolved concentrations negatively correlated with the ultraviolent absorption coefficient at 254 nm and positively correlated with the spectral slope of chromophoric DOM, suggesting that the bioavailability of these emerging organic contaminants depends on the characteristics of the DOM present. The DOM-water partition coefficients (log KOC ) for the emerging organic contaminants positively correlated with the aromaticity of the DOM, measured as humic acid-like fluorescent components C1 (excitation/emission=250[313]/412 nm) and C2 (excitation/emission=268[379]/456 nm). The authors conclude that the bioavailability of emerging organic contaminants in eutrophic lakes can be affected by changes in the DOM. © 2014 SETAC.

  3. Photochemical Reactivity of Dissolved Organic Matter in Boreal Lakes

    Science.gov (United States)

    Gu, Y.; Vuorio, K.; Tiirola, M.; Perämäki, S.; Vahatalo, A.

    2016-12-01

    Boreal lakes are rich in dissolved organic matter (DOM) that terrestrially derived from forest soil and wetland, yet little is known about potential for photochemical transformation of aquatic DOM in boreal lakes. Transformation of chromophoric dissolved organic matter (CDOM) can decrease water color and enhance microbial mineralization, affecting primary production and respiration, which both affect the CO2 balance of the lakes. We used laboratory solar radiation exposure experiments with lake water samples collected from 54 lakes located in Finland and Sweden, representing different catchment composition and watershed location to assess photochemical reactivity of DOM. The pH of water samples ranged from 5.4 to 8.3, and the concentrations of dissolved iron (Fe) were between samples received simulated solar radiation corresponding to a daily dose of sunlight, and photomineralization of dissolved organic carbon (DOC) to dissolved inorganic carbon (DIC) was measured for determination of spectral apparent quantum yields (AQY). During irradiation, photobleaching decreased the absorption coefficients of CDOM at 330 nm between 4.9 and 79 m-1 by 0.5 to 11 m-1. Irradiation generated DIC from 2.8 to 79 μmol C L-1. The AQY at 330 nm ranged between 31 and 273 ×10-6 mol C mol photons-1 h-1, which was correlated positively with concentration of dissolved Fe, and negatively with pH. Further statistical analyze indicated that the interaction between pH and Fe may explain much of the photochemical reactivity of DOM in the examined lakes, and land cover concerns main catchment areas also can have impact on the photoreaction process. This study may suggest how environmental conditions regulate DOM photomineralization in boreal lakes.

  4. The dissolver paradox as a coupled fast-thermal reactor

    International Nuclear Information System (INIS)

    Lutz, H.F.; Webb, P.S.

    1993-05-01

    The dissolver paradox is treated as coupled fast-thermal reactors. Each reactor is sub-critical but the coupling is sufficient to form a critical system. The practical importance of the system occurs when the fast system by itself is mass limited and the thermal system by itself is volume limited. Numerous 1D calculations have been made to calculate the neutron multiplication parameters of the separate fast and thermal systems that occur in the dissolver paradox. A model has been developed to describe the coupling between the systems. Monte Carlo calculations using the MCNP code have tested the model

  5. Nano-Enriched and Autonomous Sensing Framework for Dissolved Oxygen

    Directory of Open Access Journals (Sweden)

    Nader Shehata

    2015-08-01

    Full Text Available This paper investigates a nano-enhanced wireless sensing framework for dissolved oxygen (DO. The system integrates a nanosensor that employs cerium oxide (ceria nanoparticles to monitor the concentration of DO in aqueous media via optical fluorescence quenching. We propose a comprehensive sensing framework with the nanosensor equipped with a digital interface where the sensor output is digitized and dispatched wirelessly to a trustworthy data collection and analysis framework for consolidation and information extraction. The proposed system collects and processes the sensor readings to provide clear indications about the current or the anticipated dissolved oxygen levels in the aqueous media.

  6. Nano-Enriched and Autonomous Sensing Framework for Dissolved Oxygen.

    Science.gov (United States)

    Shehata, Nader; Azab, Mohammed; Kandas, Ishac; Meehan, Kathleen

    2015-08-14

    This paper investigates a nano-enhanced wireless sensing framework for dissolved oxygen (DO). The system integrates a nanosensor that employs cerium oxide (ceria) nanoparticles to monitor the concentration of DO in aqueous media via optical fluorescence quenching. We propose a comprehensive sensing framework with the nanosensor equipped with a digital interface where the sensor output is digitized and dispatched wirelessly to a trustworthy data collection and analysis framework for consolidation and information extraction. The proposed system collects and processes the sensor readings to provide clear indications about the current or the anticipated dissolved oxygen levels in the aqueous media.

  7. Highly Polluted Wastewaters Treatment by Improved Dissolved Air Flotation Technology

    Science.gov (United States)

    Moga, I. C.; Covaliu, C. I.; Matache, M. G.; Doroftei, B. I.

    2017-06-01

    Numerous investigations are oriented towards the development of new wastewater treatment technologies, having high efficiencies for removing even low concentrations of pollutants found in water. These efforts were determined by the destroyer impact of the pollutants to the environment and human’s health. For this reason this paper presents our study concerning an improved dissolved air flotation technology for wastewater treatment. There is described a dissolved air flotation (DAF) installation composed by two equipments: pressurized capsule and lamellar settling. Also, there are presented some advantages of using nanoparticles as flotation collectors.

  8. TED of boron in the presence of EOR defects: the use of the theory of Ostwald ripening to calculate Si-interstitial supersaturation in the vicinity of extrinsic defects

    Science.gov (United States)

    Bonafos, C.; Alquier, D.; Martinez, A.; Mathiot, D.; Claverie, A.

    1996-05-01

    When end-of-range defects are located close to or within doping profiles they render diffusion "anomalous" by both enhancing the dopant diffusivity and trapping it, both phenomena decreasing with time. Upon annealing, these defects grow in size and their density is reduced through the emission and capture of Si-interstitial atoms by a coarsening process called Ostwald ripening. In this paper, we report on how, by coupling the Ostwald ripening theory with TEM observations of the time evolution of the dislocation loops upon annealing, quantitative information allowing the enhanced diffusivity to be understood can be extracted. Indeed, during the coarsening process, a supersaturation, {C}/{C e}, of Si self-interstitial atoms is maintained between the loops and decreases with time. The enhanced diffusivity is assumed to be linked to the evolution of this interstitial supersaturation during annealing through the interstitial component of boron diffusion. We show that C drastically decreases during the first second of the anneal to asymptotically reach a value just above the equilibrium concentration Ce. This rapid decay is precisely at the origin of the transient enhanced diffusivity of dopants in the vicinity of the loops.

  9. Treatment of Gas

    Science.gov (United States)

    ... Funding IFFGD Symposium reports Industry Council Contact Us Treatment of Gas You are here: Home Symptoms & Causes Intestinal Gas ... Controlling Intestinal Gas Foods That May Cause Gas Treatment of Gas Tips on Controlling Gas Adapted from IFFGD Publication # ...

  10. Asian gas

    International Nuclear Information System (INIS)

    Masuda, T.

    1990-01-01

    This paper reports on natural gas which now appears ready to take a leading role on the world energy stage. Demand for natural gas, and specifically LNG, will be strong throughout the world, particularly in Asia. Indonesia and Malaysia will become much more dependent on natural gas in the Asian market. In Thailand, where remarkable economic growth has been fueled by imported oil and domestically produced natural gas, LNG may soon have to be imported from neighboring countries. The author sees Thailand's imports of natural gas increasing from 1.5 to 4.5 million tons annually. Similarly, Korea's imports of LNG will rise from 2 to 8 million tons between 1987 and 2000. In Japan, energy demand is expected to increase at an even faster rate in the 1990s. Given the opposition to nuclear power generation and growing concern about the greenhouse effect, it is likely that LNG will satisfy a major portion of Japan's increasing demand for energy. Japanese gas companies are studying the possibility of establishing a national pipeline network to move gas beyond metropolitan areas

  11. Distribution and origin of dissolved methane, ethane and propane in shallow groundwater of Lower Saxony, Germany

    International Nuclear Information System (INIS)

    Schloemer, S.; Elbracht, J.; Blumenberg, M.; Illing, C.J.

    2016-01-01

    More than 90% of Germany's domestic natural gas production and reserves are located in Lower Saxony, North Germany. Recently, research has been intensified with respect to unconventional shale gas, revealing a large additional resource potential in northern Germany. However, many concerns arise within the general public and government/political institutions over potential groundwater contamination from additional gas wells through hydraulic fracturing operations. In order to determine the naturally occurring background methane concentrations, ∼1000 groundwater wells, covering ∼48 000 km 2 , have been sampled and subsequently analyzed for dissolved methane, ethane and propane and the isotopic composition of methane (δ 13 C). Dissolved methane concentrations cover a range of ∼7 orders of magnitude between the limit of quantification at ∼20 nl/l and 60 ml/l. The majority of groundwater wells exhibit low concentrations (<1 μl/l), a small number of samples (65) reveal concentration in the range >10 ml/l. In 27% of all samples ethane and in 8% ethane and propane was detected. The median concentration of both components is generally very low (ethane 50 nl/l, propane 23 nl/l). Concentrations reveal a bimodal distribution of the dissolved gas, which might mirror a regional trend due to different hydrogeological settings. The isotopic composition of methane is normally distributed (mean ∼ −70‰ vs PDB), but shows a large variation between −110‰ and +20‰. Samples with δ 13 C values lower than −55‰ vs PDB (66%) are indicative for methanogenic biogenic processes. 5% of the samples are unusually enriched in 13 C (≥25‰ vs PDB) and can best be explained by microbial methane oxidation. According to a standard diagnostic diagram based on methane δ 13 C values and the ratio of methane over the sum over ethane plus propane (“Bernard”-diagram) less than 4% of the samples plot into the diagnostic field of typical thermogenic natural

  12. Advances in the Control System for a High Precision Dissolved Organic Carbon Analyzer

    Science.gov (United States)

    Liao, M.; Stubbins, A.; Haidekker, M.

    2017-12-01

    Dissolved organic carbon (DOC) is a master variable in aquatic ecosystems. DOC in the ocean is one of the largest carbon stores on earth. Studies of the dynamics of DOC in the ocean and other low DOC systems (e.g. groundwater) are hindered by the lack of high precision (sub-micromolar) analytical techniques. Results are presented from efforts to construct and optimize a flow-through, wet chemical DOC analyzer. This study focused on the design, integration and optimization of high precision components and control systems required for such a system (mass flow controller, syringe pumps, gas extraction, reactor chamber with controlled UV and temperature). Results of the approaches developed are presented.

  13. A simple technique for continuous measurement of time-variable gas transfer in surface waters

    Science.gov (United States)

    Tobias, Craig R.; Bohlke, John Karl; Harvey, Judson W.; Busenberg, Eurybiades

    2009-01-01

    Mass balance models of dissolved gases in streams, lakes, and rivers serve as the basis for estimating wholeecosystem rates for various biogeochemical processes. Rates of gas exchange between water and the atmosphere are important and error-prone components of these models. Here we present a simple and efficient modification of the SF6 gas tracer approach that can be used concurrently while collecting other dissolved gas samples for dissolved gas mass balance studies in streams. It consists of continuously metering SF6-saturated water directly into the stream at a low rate of flow. This approach has advantages over pulse injection of aqueous solutions or bubbling large amounts of SF6 into the stream. By adding the SF6 as a saturated solution, we minimize the possibility that other dissolved gas measurements are affected by sparging and/or bubble injecta. Because the SF6 is added continuously we have a record of changing gas transfer velocity (GTV) that is contemporaneous with the sampling of other nonconservative ambient dissolved gases. Over a single diel period, a 30% variation in GTV was observed in a second-order stream (Sugar Creek, Indiana, USA). The changing GTV could be attributed in part to changes in temperature and windspeed that occurred on hourly to diel timescales.

  14. Gas dusulfurization

    International Nuclear Information System (INIS)

    Powell, B.E.; Bakhshi, V.S.; Randolph, D.A.

    1984-01-01

    A process for adsorbing sulfur dioxide from a gas comprising contacting a gas containing SO 2 , such as a flue gas, with about stoichiometric amounts of a specially prepared calcium oxide so that substantially all of the sulfur dioxide content is reacted throughout the calcium oxide particle to form a calcium sulfate reaction product. The useful calcium oxide particles comprise a highly voided skeletal structure of very large surface area and large pore volume with numerous macro pores. Such particles are obtained by flash calcining sand-size grains of calcium carbonate, such as aragonite, calcite or dolomite

  15. Gas turbines

    Energy Technology Data Exchange (ETDEWEB)

    Farahan, E.; Eudaly, J.P.

    1978-10-01

    This evaluation provides performance and cost data for commercially available simple- and regenerative-cycle gas turbines. Intercooled, reheat, and compound cycles are discussed from theoretical basis only, because actual units are not currently available, except on a special-order basis. Performance characteristics investigated include unit efficiency at full-load and off-design conditions, and at rated capacity. Costs are tabulated for both simple- and regenerative-cycle gas turbines. The output capacity of the gas turbines investigated ranges from 80 to 134,000 hp for simple units and from 12,000 to 50,000 hp for regenerative units.

  16. Dissolved gasesous hydrocarbons in shallow groundwater of Lower Saxony, Germany - Revisited 2016

    Science.gov (United States)

    Schloemer, Stefan; Illing, Christian J.; Blumenberg, Martin; Oest, Johanna; Elbracht, Jörg

    2017-04-01

    Many concerns arise within the public and government/political institutions over potential groundwater contamination from deep drilling operations. For this reason we initiated a baseline study in 2014 on the distribution of dissolved methane, ethane and propane in shallow groundwater ( 1000 groundwater wells, Schloemer et al., 2016) of Lower Saxony, which includes the major petroleum and natural gas provinces in Germany. We observed a variation of dissolved methane concentration over 7 orders of magnitude (20 nl/l to 60 ml/l [v/v]). Methane delta13C compositions ranged from -110‰ to +25‰ vs VPDB, narrowly clustering around -70‰ at high concentrations but being increasingly more variable at lower concentrations (-40‰ to -80‰)). Most of the data are clearly indicative for methanogenic processes, samples unusually enriched in delta13C can best be explained by secondary methane oxidation. Although some general regional trend can be observed, results are highly variable within short lateral distances or within different aquifers/filter depths. Frequently ethane (27% of samples, median 50nl/l) and occasionally propane (8%, median 23nl/l) has been detected. Lacking the carbon isotope composition of these homologues and thus solely based on the extremely low concentrations and atypical ethane/propane ratios, these have been tentatively interpreted as ubiquitous microbial background. From the original 2014 sample set around 100 wells have been selected for consecutive testing through 2015. In spring 2016 a total number of 1100 wells have been sampled, 700 of which had already been part of the initial study, providing us with the unique opportunity to assess long term variations. The overall comparison of these 700 samples revealed only small relative variations in methane concentrations (mostly ± 5‰ in 25% of samples). Minor variations could be related to uncertainties in laboratory analysis (± 10% in concentration, ± 0.5‰ delta13C). To which extent the

  17. The isotopic, chemical and dissolved gas concentrations in groundwater near Beaufort West

    International Nuclear Information System (INIS)

    Vogel, J.C.; Talma, A.S.; Heaton, T.H.E.

    1980-01-01

    Groundwater was collected from fifteen boreholes over an area of 500 sq km to the north-east of Beafort West, Cape Province, South Africa. Six boreholes were sampled at different depths using a pump equipped with inflatable packers. Samples were analysed for their carbon-14, tritium, oxygen-18, carbon-13, helium, nitrogen, argon, oxygen and radon-222 contents, uranium-234/uranium-238 activity ratios, and major ion chemistry. The study was a reconnaisance survey, but demonstrated the usefulness of multi-parameter investigations. The data are used in discussing the geohydrology of the area with emphasis on the recharge sources of groundwater in the pediment and at the foot of the surrounding escarpment

  18. Estimating of gas transfer velocity using triple isotopes of dissolved oxygen.

    Digital Repository Service at National Institute of Oceanography (India)

    Sarma, V.V.S.S.; Abe, O.; Honda, M.; Saino, T.

    variations in oxygen isotopes are found to be higher than the direct estimations at low wind speed (<5 m s sup(-1)) and lower at high wind speeds (>13 m s sup(-1)) and showed significant spatial variability. The method presented here can be used to derive...

  19. Recharge processes and vertical transfer investigated through long-term monitoring of dissolved gases in shallow groundwater

    Science.gov (United States)

    de Montety, V.; Aquilina, L.; Labasque, T.; Chatton, E.; Fovet, O.; Ruiz, L.; Fourré, E.; de Dreuzy, J. R.

    2018-05-01

    We investigated temporal variations and vertical evolution of dissolved gaseous tracers (CFC-11, CFC-12, SF6, and noble gases), as well as 3H/3He ratio to determine groundwater recharge processes of a shallow unconfined, hard-rock aquifer in an agricultural catchment. We sampled dissolved gas concentration at 4 locations along the hillslope of a small experimental watershed, over 6 hydrological years, between 2 and 6 times per years, for a total of 20 field campaigns. We collected groundwater samples in the fluctuation zone and the permanently saturated zone using piezometers from 5 to 20 m deep. The purpose of this work is i) to assess the benefits of using gaseous tracers like CFCs and SF6 to study very young groundwater with flows suspected to be heterogeneous and variable in time, ii) to characterize the processes that control dissolved gas concentrations in groundwater during the recharge of the aquifer, and iii) to understand the evolution of recharge flow processes by repeated measurement campaigns, taking advantage of a long monitoring in a site devoted to recharge processes investigation. Gas tracer profiles are compared at different location of the catchment and for different hydrologic conditions. In addition, we compare results from CFCs and 3H/3He analysis to define the flow model that best explains tracer concentrations. Then we discuss the influence of recharge events on tracer concentrations and residence time and propose a temporal evolution of residence times for the unsaturated zone and the permanently saturated zone. These results are used to gain a better understanding of the conceptual model of the catchment and flow processes especially during recharge events.

  20. Volcanic Gas

    Science.gov (United States)

    ... offensive odor. It is sometimes referred to as sewer gas. Interestingly, the human nose is more sensitive ... the atmosphere where they can potentially cause acid rain. In an ash -producing eruption, ash particles are ...

  1. Gas - flatulence

    Science.gov (United States)

    ... Gas and other symptoms such as stomach pain, rectal pain, heartburn, nausea, vomiting, diarrhea, constipation, fever, or ... Copyright 1997-2018, A.D.A.M., Inc. Duplication for commercial use must be authorized in writing ...

  2. Gas sensor

    International Nuclear Information System (INIS)

    Dorogan, V.; Korotchenkov, Gh.; Vieru, T.; Prodan, I.

    2003-01-01

    The invention relates to the gas sensors on base of metal-oxide films (SnO, InO), which may be used for enviromental control, in the fireextinguishing systema etc. The gas includes an insulating substrate, an active layer, a resistive layer with ohmic contacts. The resistive layer has two or more regions with dofferent resistances , and on the active layer are two or more pairs of ohmic contacts

  3. Dissolved Carbon Dioxide in Tropical East Atlantic Surface Waters

    NARCIS (Netherlands)

    Bakker, D.C.E.; Baar, H.J.W. de; Jong, E. de

    1999-01-01

    Variability of dissolved inorganic carbon (DIC) and the fugacity of carbon dioxide (fCO2) is discussed for tropical East Atlantic surface waters in October–November 1993 and May–June 1994. High precipitation associated with the Intertropical Convergence Zone, river input and equatorial upwelling

  4. Fluorescent dissolved organic matter in the continental shelf waters ...

    Indian Academy of Sciences (India)

    Fluorescent dissolved organic matter (FDOM) of southwestern Bay of Bengal surface water during southwest monsoon consisted five fluorophores, three humic-like and two protein-like. The humification index (HIX) and humic fluorophores, viz., visible (C), marine (M) and UV (A) humic-likes indicated, better than ...

  5. Dissolved iron in the Southern Ocean (Atlantic sector)

    NARCIS (Netherlands)

    Klunder, M. B.; Laan, P.; Middag, R.; De Baar, H. J. W.; van Ooijen, J. C.

    2011-01-01

    We report a comprehensive dataset of dissolved iron (Fe) comprising 482 values at 22 complete vertical profiles along a 1 degrees latitudinal section at the Zero meridian. In addition a shorter high resolution (similar to 00 degrees 09') surface section of the southernmost part of the transect (66

  6. Diffusion coefficients gases, dissolved in fluid of NPPs circulation contours

    International Nuclear Information System (INIS)

    Piontkovskij, A.I.

    2000-01-01

    In article is brought analysis of diverse gases diffusion coefficients computation methods, dissolved in liquid. On the basis of this analysis and treatment of being equalizations for concrete gases and certain parameters offers universal diffusion coefficients determination dependence for diverse gases in wide range of parameters, circulation contours typical for work NPP

  7. Geographical differences in the relationship between total dissolved ...

    African Journals Online (AJOL)

    The practical application of these findings is that users of EC meters should not simply apply a blanket conversion factor, but need to select an applicable factor for the river system in which they are measuring. Keywords: conversion factors, electrical conductivity, field instruments, rivers, total dissolved solids, water quality ...

  8. Dissolved Nutrients from Submarine Groundwater in Flic en Flac ...

    African Journals Online (AJOL)

    through a thin blanket of unconsolidated sediment through a fracture system and is concentrated along the ... The lagoon is subjected to diffuse SGD flows which may contribute to its high dissolved nutrient values. ... coastal zone management and similar tropical volcanic lagoonal systems. INTRODUCTION. Lagoons and ...

  9. Acidity controls on dissolved organic carbon mobility in organic soils

    Czech Academy of Sciences Publication Activity Database

    Evans, Ch. D.; Jones, T.; Burden, A.; Ostle, N.; Zielinski, P.; Cooper, M.; Peacock, M.; Clark, J.; Oulehle, Filip; Cooper, D.; Freeman, Ch.

    2012-01-01

    Roč. 18, č. 11 (2012), s. 3317-3331 ISSN 1354-1013 Institutional support: RVO:67179843 Keywords : acidity * dissolved organic carbon * organic soil * peat * podzol * soil carbon * sulphur Subject RIV: EH - Ecology, Behaviour Impact factor: 6.910, year: 2012

  10. Dissolved nitrogen in drinking water resources of farming ...

    African Journals Online (AJOL)

    Dissolved nitrogen in drinking water resources of farming communities in Ghana. ... African Journal of Environmental Science and Technology ... Concentrations of these potentially toxic substances were below WHO acceptable limits for surface and groundwaters, indicating these water resources appear safe for drinking ...

  11. Hydrogen ion (Ph), ammonia, dissolved oxygen and nitrite ...

    African Journals Online (AJOL)

    Hydrogen ion (pH), dissolved oxygen, ammonia and nitrite concentrations were studied monthly in two systems (re-circulatory and semi-intensive of 3 m2 sizes) each for six months. The systems were each stocked with 200 g of Clarias gariepinus fingerlings. Results showed that all parameters were within acceptable limits ...

  12. The chemical oxidation of lignin found in Sappi Saiccor dissolving ...

    African Journals Online (AJOL)

    Sappi Saiccor (situated in Durban, South Africa) dissolving pulp mill effluent, produced from an acid bisulphite pulping process, uses acacia and eucalyptus hardwoods to produce a unique and different blend of lignin that has not been previously studied. The chemical oxidation of lignin found in Sappi Saiccor's effluent has ...

  13. Inter-relationship between major ions, total dissolved solids and ...

    African Journals Online (AJOL)

    Sulphate and magnesium concentrations were highest in station 7 while other parameters (potassium, chloride, calcium, alkalinity, conductivity and total dissolved solids (T. D. S.)) were highest in station 6. The ponds belong to class 1 of the African waters since they all have electrical conductance of less than 600 s cm-1.

  14. Mathematical model for dissolved oxygen prediction in Cirata ...

    African Journals Online (AJOL)

    This paper presents the implementation and performance of mathematical model to predict theconcentration of dissolved oxygen in Cirata Reservoir, West Java by using Artificial Neural Network (ANN). The simulation program was created using Visual Studio 2012 C# software with ANN model implemented in it. Prediction ...

  15. Mathematical modeling of dissolved oxygen in fish ponds

    African Journals Online (AJOL)

    TUOYO

    A mathematical model was developed to predict the effects of wind speed, light, pH, Temperature, dissolved carbon dioxide .... chlorophyll, the energy obtained splits water, and oxygen ... is a function of temperature T, light L, substrate, and pH as shown in ..... plants and its relation to the concentration of carbon dioxide and.

  16. Degradation of riverine dissolved organic matter by seawater bacteria

    NARCIS (Netherlands)

    Rochelle-Newall, E.J.; Pizay, M-D.; Middelburg, J.J.; Boschker, H.T.S.; Gattuso, J.P.

    2004-01-01

    The functional response of a seawater bacterial community transplanted into freshwater dissolved organic matter (DOM) was investigated together with the response of natural populations of bacteria to size-fractioned natural source water. Seawater bacteria were incubated over a period of 8 d in

  17. Impulsive Laser Induced Alignment of Molecules Dissolved in Helium Nanodroplets

    DEFF Research Database (Denmark)

    Pentlehner, Dominik; H. Nielsen, Jens; Slenczka, Alkwin

    2013-01-01

    We show that a 450 fs nonresonant, moderately intense, linearly polarized laser pulse can induce field-free molecular axis alignment of methyliodide (CH3I) molecules dissolved in a helium nanodroplet. Time-resolved measurements reveal rotational dynamics much slower than that of isolated molecules...

  18. Production of dissolved organic carbon in aquatic sediment suspensions

    NARCIS (Netherlands)

    Koelmans, A.A.; Prevo, L.

    2003-01-01

    In many water quality models production of dissolved organic carbon (DOC) is modelled as mineralisation from particulate organic matter (POM). In this paper it is argued that the DOC production from dessicated sediments by water turbulence may be of similar importance
    In many water quality

  19. Dilution limits dissolved organic carbon utilization in the deep ocean

    NARCIS (Netherlands)

    Arrieta, J.M.; Mayol, E.; Hansman, R.L.; Herndl, G.J.; Dittmar, T.; Duarte, C.M.

    2015-01-01

    Oceanic dissolved organic carbon (DOC) is the second largest reservoir of organic carbon in the biosphere. About 72% of the global DOC inventory is stored in deep oceanic layers for years to centuries, supporting the current view that it consists of materials resistant to microbial degradation. An

  20. Tomorrow, gas

    International Nuclear Information System (INIS)

    Icart, Laura; Jean, Pascale; Georget, Cyrille; Schmill, Rafael

    2017-01-01

    This document contains 12 articles notably addressing the importance of natural gas production and supplies in Europe. The themes of the articles are: the advantages of natural gas in the context of energy and environmental policies, energy diversification, energy supply in the local territories, etc.; the position of GrDF, one of the main French natural gas supplier; LPG (butane, propane), a solution which popularity grows in remote areas; the Gaya project (production of renewable gas from dry biomass); a panorama of gas supply routes in Europe; the situation of gas in Europe's energy supply and consumption; the promotion of LNG fuel for maritime and fluvial ships; why the small scale LNG could be the next revolution; presentation of the new 'Honfleur' ferry (using LNG fuel) that will cross the English Channel by 2019; carbon market and the role of ETS for the energy policy in Europe facing the climatic change challenge; presentation of the French 'Climate Plan' that aims to engage France into a carbon neutrality by 2050; presentation of the French policy against air pollution; economic growth, energy, climate: how to square this circle?

  1. Multi-technical approach to characterize the dissolved organic matter from clay-stone

    International Nuclear Information System (INIS)

    Blanchart, Pascale; Michels, Raymond; Faure, Pierre; Parant, Stephane; Bruggeman, Christophe; De Craen, Mieke

    2012-01-01

    Document available in extended abstract form only. Currently, different clay formations (Boom Clay, Callovo-Oxfordian argilites, Opalinus Clay, Toarcian shales...) are studied as reference host rocks for methodological studies on the geological disposal of high-level and long-lived radioactive waste. While a significant effort is being done on the characterization of the mineral composition and the reactivity of the clays as barriers, the occurrence of organic matter, even in low proportion cannot be neglected. The organic matter appears as gas (C 1 -C 4 as identified in the Bure underground facilities), as solid (kerogen), as hydrocarbon liquids (free hydrocarbons within the kerogen or adsorbed on minerals) as well as in the aqueous phase (Dissolved Organic Matter - DOM). DOM raises specific interest, as it may have complexation properties towards metals and rare earth elements and is potentially mobile. Therefore, it is important to characterize the DOM as part of a study of feasibility of geological disposal. In this study, four host rocks were studied: - The Callovo-Oxfordian shales of Bure Underground Research Laboratory (Meuse, France); - The Opalinus Clay of Mont Terri Underground Research Laboratory (Switzerland); - The Toarcian shales of Tournemire (Aveyron, France); - The Boom Clay formation studied in The HADES Underground Research Laboratory (Mol, Belgium). Organic matter characteristics vary upon formation in terms of (i) origin (mainly marine type II; mixtures of marine type II and higher plants type III organic matter often poorly preserved), (ii) TOC contents, (iii) thermal maturity (for instance, Opalinus Clay and Toarcian shales are more mature and have poor oxygen content compare to Callovo-Oxfordian shales and Boom Clay). These differences in organic matter quality may have an influence on the quantity and the quality of DOM. The DOM of the rocks was isolated by Soxhlet extraction using pure water. A quantitative and qualitative multi

  2. Attractive forces between hydrophobic solid surfaces measured by AFM on the first approach in salt solutions and in the presence of dissolved gases.

    Science.gov (United States)

    Azadi, Mehdi; Nguyen, Anh V; Yakubov, Gleb E

    2015-02-17

    Interfacial gas enrichment of dissolved gases (IGE) has been shown to cover hydrophobic solid surfaces in water. The atomic force microscopy (AFM) data has recently been supported by molecular dynamics simulation. It was demonstrated that IGE is responsible for the unexpected stability and large contact angle of gaseous nanobubbles at the hydrophobic solid-water interface. Here we provide further evidence of the significant effect of IGE on an attractive force between hydrophobic solid surfaces in water. The force in the presence of dissolved gas, i.e., in aerated and nonaerated NaCl solutions (up to 4 M), was measured by the AFM colloidal probe technique. The effect of nanobubble bridging on the attractive force was minimized or eliminated by measuring forces on the first approach of the AFM probe toward the flat hydrophobic surface and by using high salt concentrations to reduce gas solubility. Our results confirm the presence of three types of forces, two of which are long-range attractive forces of capillary bridging origin as caused by either surface nanobubbles or gap-induced cavitation. The third type is a short-range attractive force observed in the absence of interfacial nanobubbles that is attributed to the IGE in the form of a dense gas layer (DGL) at hydrophobic surfaces. Such a force was found to increase with increasing gas saturation and to decrease with decreasing gas solubility.

  3. Slurried solid media for simultaneous water purification and carbon dioxide removal from gas mixtures

    Science.gov (United States)

    Aines, Roger D.; Bourcier, William L.; Viani, Brian

    2013-01-29

    A slurried solid media for simultaneous water purification and carbon dioxide removal from gas mixtures includes the steps of dissolving the gas mixture and carbon dioxide in water providing a gas, carbon dioxide, water mixture; adding a porous solid media to the gas, carbon dioxide, water mixture forming a slurry of gas, carbon dioxide, water, and porous solid media; heating the slurry of gas, carbon dioxide, water, and porous solid media producing steam; and cooling the steam to produce purified water and carbon dioxide.

  4. Air Sparging Versus Gas Saturated Water Injection for Remediation of Volatile LNAPL in the Borden Aquifer

    Science.gov (United States)

    Barker, J.; Nelson, L.; Doughty, C.; Thomson, N.; Lambert, J.

    2009-05-01

    In the shallow, rather homogeneous, unconfined Borden sand aquifer, field trials of air sparging (Tomlinson et al., 2003) and pulsed air sparging (Lambert et al., 2009) have been conducted, the latter to remediate a residual gasoline source emplaced below the water table. As well, a supersaturated (with CO2) water injection (SWI) technology, using the inVentures inFusion system, has been trialed in two phases: 1. in the uncontaminated sand aquifer to evaluate the radius of influence, extent of lateral gas movement and gas saturation below the water table, and 2. in a sheet pile cell in the Borden aquifer to evaluate the recovery of volatile hydrocarbon components (pentane and hexane) of an LNAPL emplaced below the water table (Nelson et al., 2008). The SWI injects water supersaturated with CO2. The supersaturated injected water moves laterally away from the sparge point, releasing CO2 over a wider area than does gas sparging from a single well screen. This presentation compares these two techniques in terms of their potential for remediating volatile NAPL components occurring below the water table in a rather homogeneous sand aquifer. Air sparging created a significantly greater air saturation in the vicinity of the sparge well than did the CO2 system (60 percent versus 16 percent) in the uncontaminated Borden aquifer. However, SWI pushed water, still supersaturated with CO2, up to about 2.5 m from the injection well. This would seem to provide a considerable advantage over air sparging from a point, in that gas bubbles are generated at a much larger radius from the point of injection with SWI and so should involve additional gas pathways through a residual NAPL. Overall, air sparging created a greater area of influence, defined by measurable air saturation in the aquifer, but air sparging also injected about 12 times more gas than was injected in the SWI trials. The pulsed air sparging at Borden (Lambert et al.) removed about 20 percent (4.6 kg) of gasoline

  5. Methodologies for extraction of dissolved inorganic carbon for stable carbon isotope studies : evaluation and alternatives

    Science.gov (United States)

    Hassan, Afifa Afifi

    1982-01-01

    The gas evolution and the strontium carbonate precipitation techniques to extract dissolved inorganic carbon (DIC) for stable carbon isotope analysis were investigated. Theoretical considerations, involving thermodynamic calculations and computer simulation pointed out several possible sources of error in delta carbon-13 measurements of the DIC and demonstrated the need for experimental evaluation of the magnitude of the error. An alternative analytical technique, equilibration with out-gassed vapor phase, is proposed. The experimental studies revealed that delta carbon-13 of the DIC extracted from a 0.01 molar NaHC03 solution by both techniques agreed within 0.1 per mil with the delta carbon-13 of the DIC extracted by the precipitation technique, and an increase of only 0.27 per mil in that extracted by the gas evolution technique. The efficiency of extraction of DIC decreased with sulfate concentration in the precipitation technique but was independent of sulfate concentration in the gas evolution technique. Both the precipitation and gas evolution technique were found to be satisfactory for extraction of DIC from different kinds of natural water for stable carbon isotope analysis, provided appropriate precautions are observed in handling the samples. For example, it was found that diffusion of atmospheric carbon dioxide does alter the delta carbon-13 of the samples contained in polyethylene bottles; filtration and drying in the air change the delta carbon-13 of the samples contained in polyethylene bottles; filtration and drying in the air change the delta carbon-13 of the precipitation technique; hot manganese dioxide purification changes the delta carbon-13 of carbon dioxide. (USGS)

  6. The use of diagnostic imaging for identifying abnormal gas accumulations in cetaceans and pinnipeds.

    Directory of Open Access Journals (Sweden)

    Sophie eDennison

    2012-06-01

    Full Text Available Recent dogma suggested that marine mammals are not at risk of decompression sickness (DCS due to a number of evolutionary adaptations. Several proposed adaptations exist. Lung compression and alveolar collapse that terminate gas exchange before a depth is reached where supersaturation is significant and bradycardia with peripheral vasoconstriction affecting the distribution, and dynamics of blood and tissue nitrogen levels. Published accounts of gas and fat emboli and dysbaric osteonecrosis in marine mammals and theoretical modeling have challenged this view-point, suggesting that decompression-like symptoms may occur under certain circumstances, contrary to common belief. Diagnostic imaging modalities are invaluable tools for the non-invasive examination of animals for evidence of gas and have been used to demonstrate the presence of incidental decompression-related renal gas accumulations in some stranded cetaceans. Diagnostic imaging has also contributed to the recognition of clinically significant gas accumulations in live and dead cetaceans and pinnipeds. Understanding the appropriate application and limitations of the available imaging modalities is important for accurate interpretation of results. The presence of gas may be incidental and must be interpreted cautiously alongside all other available data including clinical examination, clinical laboratory testing, gas analysis, necropsy examination and histology results.

  7. Gas war

    International Nuclear Information System (INIS)

    Shiry, J.

    1992-01-01

    The sale of natural gas to California is one of the most complex and contested trade disputes between the USA and Canada. The background and the issues involved are discussed. An oversupply of Canadian gas, combined with USA subsidies for producing coalbed methane and a general oversupply of gas in the USA, have made spot gas prices decline to unexpectedly low levels. California regulators have responded to this situation by trying to secure the lowest possible prices for consumers, thereby causing them to abandon long-standing trade policies with Canada. The main agent of this change is the California Public Utilities Commission (CPUC), whose actions have reduced the value of Canadian exports and Alberta government revenues by at least $250 million annually. CPUC supported buying from a supply pool (Alberta ampersand Southern Gas) since it provided monopoly purchasing power, and CPUC's policy against pipeline expansion produced the limited access to California that the CPUC now cites as evidence of a producer cartel. CPUC has interfered in contracts with Canadian producers in its pipeline access policies, its capacity brokering decision of 1991, and its reasonableness test for past sales. In its haste to force its own view of market results onto existing contractual relationships, the CPUC is not allowing open negotiations to reshape the relationship, and CPUC actions may be generating countermeasures by Alberta that are inappropriate under deregulation. 3 figs

  8. Gas attack

    Energy Technology Data Exchange (ETDEWEB)

    North, D.

    1977-08-01

    Consumersfirst Ltd. is reacting to deregulation with a massive advertising campaign. The gas utility is owned by Consumers Gas Energy Inc., and is struggling to hold onto its 35 per cent share of Ontario`s two million residential natural gas buyers. An industry analyst pointed out that deregulation could mean that Consumers` Gas has much to lose: customers, market share, control of the assets and control of the process. The Ontario Energy Board (OEB) however, had specified that Consumersfirst is not to proceed with paperwork to sign up new customers until the OEB issues a draft code-of-conduct that would prevent cross-subsidizing between regulated franchise holders. This has now been done, and several heavyweights such as Calgary-based Suncor Energy Inc., Union Gas of Chatham, Ontario, and the US-based Enron Corp. of Houston, have started campaigns to sign up potential consumers. It is predicted that brand loyalty will be a factor, but in the end, like long distance telephone rates, it will all come down to pricing, and a winning formula is not easy to find.

  9. Gas hydrates

    Digital Repository Service at National Institute of Oceanography (India)

    Ramprasad, T.

    , not all of them are white like snow. Some hydrates from the deep Gulf of Mexico are richly colored in shades of yellow, orange, or even red. The ice-like masses are beautiful, and contrast with the dull gray of deep sea muds. Hydrates from the Blake... volcanoes and associated gas hydrates: Marine Geology, v. 167, p. 29-42. Milkov, A.V. and R. Sassen, 2001a, Estimate of gas hydrate resource, northwestern Gulf of Mexico continental slope: Marine Geology, v. 179, pp. 71-83. Milkov, A.V., Sassen, R...

  10. A preliminary assessment of gas diffusion and migration

    Energy Technology Data Exchange (ETDEWEB)

    Tanai, Kenji; Sato, Haruo [Waste Isolation Research Division, Tokai Works, Japan Nuclear Cycle Development Inst., Tokai, Ibaraki (Japan); Murakami, Tomohiro [Toyo Engineering Corp., Tokyo (Japan); Inoue, Masahiro [Kyushu Univ., Fukuoka (Japan)

    1999-11-01

    In the anaerobic environment in the deep underground water, carbon-steel overpack corrodes and generates molecular hydrogen. It is conceivable that this hydrogen either dissolves into the porewater of the buffer and migrates through the buffer. If the rate of aqueous diffusion of hydrogen is too low compared to the rate of hydrogen generation, the concentration of hydrogen at the overpack surface will increase until a solubility limit is attained and a free hydrogen gas phase forms. It is possible that the pressure in this accumulating gas phase will increase, affecting the stability of the buffer or the surrounding rock mass. There is also a concern of possible effects on nuclide migration, as it is also conceivable that the flow of gas could push out radionuclide-bearing porewater in the buffer when it floes through the buffer. As such, experimental and analytical study must be carried out on such phenomenon to evaluate such potential phenomena. (1) Diffusion experiment of dissolved hydrogen. (2) Gas permeability. (3) Evaluation of diffusion of dissolved hydrogen and hydrogen gas migration. (J.P.N.)

  11. Anaerobic biodegradation of dissolved ethanol in a pilot-scale sand aquifer: Variability in plume (redox) biogeochemistry

    Science.gov (United States)

    McLeod, Heather C.; Roy, James W.; Slater, Gregory F.; Smith, James E.

    2018-01-01

    The use of ethanol in alternative fuels has led to contamination of groundwater with high concentrations of this easily biodegradable organic compound. Previous laboratory and field studies have shown vigorous biodegradation of ethanol plumes, with prevalence of reducing conditions and methanogenesis. The objective of this study was to further our understanding of the dynamic biogeochemistry processes, especially dissolved gas production, that may occur in developing and aging plume cores at sites with ethanol or other organic contamination of groundwater. The experiment performed involved highly-detailed spatial and temporal monitoring of ethanol biodegradation in a 2-dimensional (175 cm high × 525 cm long) sand aquifer tank for 330 days, with a vertical shift in plume position and increased nutrient inputs occurring at Day 100. Rapid onset of fermentation, denitrification, sulphate-reduction and iron(III)-reduction occurred following dissolved ethanol addition, with the eventual widespread development of methanogenesis. The detailed observations also demonstrate a redox zonation that supports the plume fringe concept, secondary reactions resulting from a changing/moving plume, and time lags for the various biodegradation processes. Additional highlights include: i) the highest dissolved H2 concentrations yet reported for groundwater, possibly linked to vigorous fermentation in the absence of common terminal electron-acceptors (i.e., dissolved oxygen, nitrate, and sulphate, and iron(III)-minerals) and methanogenesis; ii) evidence of phosphorus nutrient limitation, which stalled ethanol biodegradation and perhaps delayed the onset of methanogenesis; and iii) the occurrence of dissimilatory nitrate reduction to ammonium, which has not been reported for ethanol biodegradation to date.

  12. Effect of isobaric breathing gas shifts from air to heliox mixtures on resolution of air bubbles in lipid and aqueous tissues of recompressed rats

    DEFF Research Database (Denmark)

    Hyldegaard, Ole; Kerem, Dikla; Melamed, Y

    2011-01-01

    Deep tissue isobaric counterdiffusion that may cause unwanted bubble formation or transient bubble growth has been referred to in theoretical models and demonstrated by intravascular gas formation in animals, when changing inert breathing gas from nitrogen to helium after hyperbaric air breathing....... We visually followed the in vivo resolution of extravascular air bubbles injected at 101 kPa into nitrogen supersaturated rat tissues: adipose, spinal white matter, skeletal muscle or tail tendon. Bubbles were observed during isobaric breathing-gas shifts from air to normoxic (80:20) heliox mixture...... breathing. No such bubble growth was observed in spinal white matter, skeletal muscle or tendon. In spinal white matter, an immediate breathing gas shift after the hyperbaric air exposure from air to both (80:20) and (50:50) heliox, coincident with recompression to either 285 or 405 kPa, caused consistent...

  13. Fast Oxidation Processes in a Naturally Reduced Aquifer Zone Caused by Dissolved Oxygen

    Science.gov (United States)

    Davis, J. A.; Jemison, N. E.; Williams, K. H.; Hobson, C.; Bush, R. P.

    2014-12-01

    The occurrence of naturally reduced zones is quite common in alluvial aquifers in the western U.S.A. due to the burial of woody debris in flood plains. The naturally reduced zones are heterogeneously dispersed in such aquifers and are characterized by high concentrations of organic carbon and reduced phases, including iron sulfides and reduced forms of metals, including uranium(IV). The persistence of high concentrations of dissolved uranium(VI) at uranium-contaminated aquifers on the Colorado Plateau has been attributed to slow oxidation of insoluble uranium(IV) mineral phases that are found in association with these natural reducing zones, although there is little understanding of the relative importance of various potential oxidants. Three field experiments were conducted within an alluvial aquifer adjacent to the Colorado River near Rifle, CO wherein groundwater associated with naturally reduced zones was pumped into a gas-impermeable tank, mixed with a conservative tracer (Br-), bubbled with a gas phase composed of 97% O2 and 3% CO2, and then returned to the subsurface in the same well from which it was withdrawn. Within minutes of re-injection of the oxygenated groundwater, dissolved uranium(VI) concentrations increased from less than 1 μM to greater than 2.5 μM, demonstrating that oxygen can be an important oxidant for uranium in these field systems if supplied to the naturally reduced zones. Small concentrations of nitrate were also observed in the previously nitrate-free groundwater, and Fe(II) decreased to the detection limit. These results contrast with other laboratory and field results in which oxygen was introduced to systems containing high concentrations of mackinawite (FeS) rather than the more crystalline iron sulfides found in aged, naturally reduced zones. The flux of oxygen to the naturally reduced zones in the alluvial aquifers occurs mainly through interactions between groundwater and gas phases at the water table, and seasonal variations

  14. Production of fluorescent dissolved organic matter in Arctic Ocean sediments

    Science.gov (United States)

    Chen, Meilian; Kim, Ji-Hoon; Nam, Seung-Il; Niessen, Frank; Hong, Wei-Li; Kang, Moo-Hee; Hur, Jin

    2016-12-01

    Little is known about the production of fluorescent dissolved organic matter (FDOM) in the anoxic oceanic sediments. In this study, sediment pore waters were sampled from four different sites in the Chukchi-East Siberian Seas area to examine the bulk dissolved organic carbon (DOC) and their optical properties. The production of FDOM, coupled with the increase of nutrients, was observed above the sulfate-methane-transition-zone (SMTZ). The presence of FDOM was concurrent with sulfate reduction and increased alkalinity (R2 > 0.96, p  0.95, p CDOM and FDOM to the overlying water column, unearthing a channel of generally bio-refractory and pre-aged DOM to the oceans.

  15. Functional State Modelling of Cultivation Processes: Dissolved Oxygen Limitation State

    Directory of Open Access Journals (Sweden)

    Olympia Roeva

    2015-04-01

    Full Text Available A new functional state, namely dissolved oxygen limitation state for both bacteria Escherichia coli and yeast Saccharomyces cerevisiae fed-batch cultivation processes is presented in this study. Functional state modelling approach is applied to cultivation processes in order to overcome the main disadvantages of using global process model, namely complex model structure and a big number of model parameters. Alongwith the newly introduced dissolved oxygen limitation state, second acetate production state and first acetate production state are recognized during the fed-batch cultivation of E. coli, while mixed oxidative state and first ethanol production state are recognized during the fed-batch cultivation of S. cerevisiae. For all mentioned above functional states both structural and parameter identification is here performed based on experimental data of E. coli and S. cerevisiae fed-batch cultivations.

  16. Isotope correlation verification of analytical measurements for dissolver materials

    International Nuclear Information System (INIS)

    Satkowski, J.

    1988-01-01

    An independent verification of analytical results for accountability measurements of dissolver materials can be performed using the Iosotop Correlation Technique (ICT). ICT is based on the relationships that exist between the initial and final elemental concentration and isotopic abundances of the nuclear fuel. Linear correlation functions between isotopic ratios and plutonium/uranium ratios have been developed for specific reactor fuels. The application of these correlations to already existing analytical data provides a laboratory additional confidence in the reported results. Confirmation is done by a test of consistancy with historical data. ICT is being utilized with dissolver accountability measurements at the Savannah River Plant Laboratory. The application, implementation, and operating experience of this technique are presented

  17. Dissolvable tattoo sensors: from science fiction to a viable technology

    Science.gov (United States)

    Cheng, Huanyu; Yi, Ning

    2017-01-01

    Early surrealistic painting and science fiction movies have envisioned dissolvable tattoo electronic devices. In this paper, we will review the recent advances that transform that vision into a viable technology, with extended capabilities even beyond the early vision. Specifically, we focus on the discussion of a stretchable design for tattoo sensors and degradable materials for dissolvable sensors, in the form of inorganic devices with a performance comparable to modern electronics. Integration of these two technologies as well as the future developments of bio-integrated devices is also discussed. Many of the appealing ideas behind developments of these devices are drawn from nature and especially biological systems. Thus, bio-inspiration is believed to continue playing a key role in future devices for bio-integration and beyond.

  18. Dissolving of Nb and Ti carbonitride precipitates in microalloyed steels

    Institute of Scientific and Technical Information of China (English)

    Wenjin Nie; Shanwu Yang; Shaoqiang Yuan; Xinlai He

    2003-01-01

    The dissolving behaviour of Nb and Ti carbonitride precipitates in microalloyed steels during isothermal holding at 1300℃ was investigated by Transmission electron microscopy (TEM) and energy dispersion x-ray spectrum (EDX). It was found that all precipitates in Nb-Ti microalloyed steel are (Nb, Ti)(C,N). With holding time increasing, the atomic ratio of Nb/Ti in precipitates decrease gradually. These precipitates still existe even after holding for 48 h at 1300℃ while Nb(C,N) precipitates dissolve away in Nb microalloyed steel only after 4 h at the same temperature. These results show that formation and thermostability of precipitates are considerably influenced by interaction between Nb and Ti.

  19. Preparation of encapsulated proteins dissolved in low viscosity fluids

    International Nuclear Information System (INIS)

    Ehrhardt, Mark R.; Flynn, Peter F.; Wand, A. Joshua

    1999-01-01

    The majority of proteins are too large to be comprehensively examined by solution NMR methods, primarily because they tumble too slowly in solution. One potential approach to making the NMR relaxation properties of large proteins amenable to modern solution NMR techniques is to encapsulate them in a reverse micelle which is dissolved in a low viscosity fluid. Unfortunately, promising low viscosity fluids such as the short chain alkanes, supercritical carbon dioxide, and various halocarbon refrigerants all require the application of significant pressure to be kept liquefied at room temperature. Here we describe the design and use of a simple cost effective NMR tube suitable for the preparation of solutions of proteins encapsulated in reverse micelles dissolved in such fluids

  20. Dissolvable tattoo sensors: from science fiction to a viable technology

    International Nuclear Information System (INIS)

    Cheng, Huanyu; Yi, Ning

    2017-01-01

    Early surrealistic painting and science fiction movies have envisioned dissolvable tattoo electronic devices. In this paper, we will review the recent advances that transform that vision into a viable technology, with extended capabilities even beyond the early vision. Specifically, we focus on the discussion of a stretchable design for tattoo sensors and degradable materials for dissolvable sensors, in the form of inorganic devices with a performance comparable to modern electronics. Integration of these two technologies as well as the future developments of bio-integrated devices is also discussed. Many of the appealing ideas behind developments of these devices are drawn from nature and especially biological systems. Thus, bio-inspiration is believed to continue playing a key role in future devices for bio-integration and beyond. (invited comment)