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Sample records for mercury loaded solid

  1. Improved estimates of filtered total mercury loadings and total mercury concentrations of solids from potential sources to Sinclair Inlet, Kitsap County, Washington

    USGS Publications Warehouse

    Paulson, Anthony J.; Conn, Kathleen E.; DeWild, John F.

    2013-01-01

    Previous investigations examined sources and sinks of mercury to Sinclair Inlet based on historic and new data. This included an evaluation of mercury concentrations from various sources and mercury loadings from industrial discharges and groundwater flowing from the Bremerton naval complex to Sinclair Inlet. This report provides new data from four potential sources of mercury to Sinclair Inlet: (1) filtered and particulate total mercury concentrations of creek water during the wet season, (2) filtered and particulate total mercury releases from the Navy steam plant following changes in the water softening process and discharge operations, (3) release of mercury from soils to groundwater in two landfill areas at the Bremerton naval complex, and (4) total mercury concentrations of solids in dry dock sumps that were not affected by bias from sequential sampling. The previous estimate of the loading of filtered total mercury from Sinclair Inlet creeks was based solely on dry season samples. Concentrations of filtered total mercury in creek samples collected during wet weather were significantly higher than dry weather concentrations, which increased the estimated loading of filtered total mercury from creek basins from 27.1 to 78.1 grams per year. Changes in the concentrations and loading of filtered and particulate total mercury in the effluent of the steam plant were investigated after the water softening process was changed from ion-exchange to reverse osmosis and the discharge of stack blow-down wash began to be diverted to the municipal water-treatment plant. These changes reduced the concentrations of filtered and particulate total mercury from the steam plant of the Bremerton naval complex, which resulted in reduced loadings of filtered total mercury from 5.9 to 0.15 grams per year. Previous investigations identified three fill areas on the Bremerton naval complex, of which the western fill area is thought to be the largest source of mercury on the base

  2. Improved estimates of filtered total mercury loadings and total mercury concentrations of solids from potential sources to Sinclair Inlet, Kitsap County, Washington

    USGS Publications Warehouse

    Paulson, Anthony J.; Conn, Kathleen E.; DeWild, John F.

    2013-01-01

    Previous investigations examined sources and sinks of mercury to Sinclair Inlet based on historic and new data. This included an evaluation of mercury concentrations from various sources and mercury loadings from industrial discharges and groundwater flowing from the Bremerton naval complex to Sinclair Inlet. This report provides new data from four potential sources of mercury to Sinclair Inlet: (1) filtered and particulate total mercury concentrations of creek water during the wet season, (2) filtered and particulate total mercury releases from the Navy steam plant following changes in the water softening process and discharge operations, (3) release of mercury from soils to groundwater in two landfill areas at the Bremerton naval complex, and (4) total mercury concentrations of solids in dry dock sumps that were not affected by bias from sequential sampling. The previous estimate of the loading of filtered total mercury from Sinclair Inlet creeks was based solely on dry season samples. Concentrations of filtered total mercury in creek samples collected during wet weather were significantly higher than dry weather concentrations, which increased the estimated loading of filtered total mercury from creek basins from 27.1 to 78.1 grams per year. Changes in the concentrations and loading of filtered and particulate total mercury in the effluent of the steam plant were investigated after the water softening process was changed from ion-exchange to reverse osmosis and the discharge of stack blow-down wash began to be diverted to the municipal water-treatment plant. These changes reduced the concentrations of filtered and particulate total mercury from the steam plant of the Bremerton naval complex, which resulted in reduced loadings of filtered total mercury from 5.9 to 0.15 grams per year. Previous investigations identified three fill areas on the Bremerton naval complex, of which the western fill area is thought to be the largest source of mercury on the base

  3. Mercury emissions from municipal solid waste combustors

    SciTech Connect

    Not Available

    1993-05-01

    This report examines emissions of mercury (Hg) from municipal solid waste (MSW) combustion in the United States (US). It is projected that total annual nationwide MSW combustor emissions of mercury could decrease from about 97 tonnes (1989 baseline uncontrolled emissions) to less than about 4 tonnes in the year 2000. This represents approximately a 95 percent reduction in the amount of mercury emitted from combusted MSW compared to the 1989 mercury emissions baseline. The likelihood that routinely achievable mercury emissions removal efficiencies of about 80 percent or more can be assured; it is estimated that MSW combustors in the US could prove to be a comparatively minor source of mercury emissions after about 1995. This forecast assumes that diligent measures to control mercury emissions, such as via use of supplemental control technologies (e.g., carbon adsorption), are generally employed at that time. However, no present consensus was found that such emissions control measures can be implemented industry-wide in the US within this time frame. Although the availability of technology is apparently not a limiting factor, practical implementation of necessary control technology may be limited by administrative constraints and other considerations (e.g., planning, budgeting, regulatory compliance requirements, etc.). These projections assume that: (a) about 80 percent mercury emissions reduction control efficiency is achieved with air pollution control equipment likely to be employed by that time; (b) most cylinder-shaped mercury-zinc (CSMZ) batteries used in hospital applications can be prevented from being disposed into the MSW stream or are replaced with alternative batteries that do not contain mercury; and (c) either the amount of mercury used in fluorescent lamps is decreased to an industry-wide average of about 27 milligrams of mercury per lamp or extensive diversion from the MSW stream of fluorescent lamps that contain mercury is accomplished.

  4. Ecosystem Responses to Changed Atmospheric Mercury Load: Results from Seven Years of Mercury Loading to Lake 658

    NASA Astrophysics Data System (ADS)

    Gilmour, C.; Harris, R.; Kelly, C.; Rudd, J.; Amyot, M.; Hurley, J.; Babiarz, C.; Paterson, M.; Blanchfield, P.; Beaty, K.; Sandilands, K.; Hintelmann, H.; Krabbenhoft, D.; Tate, M.; Lindberg, S.; Southworth, G.; St. Louis, V.; Graydon, J.

    2009-05-01

    The response of fish methylmercury concentrations to changes in mercury deposition has been difficult to establish because sediments/soils contain large pools of historical contamination, and many factors in addition to deposition affect fish mercury. To test directly the response of fish contamination to changing mercury deposition, we are conducting the METAALICUS study, a whole-ecosystem experiment, increasing the mercury load to a lake and its watershed by the addition of enriched stable mercury isotopes. The isotopes allowed us to distinguish between experimentally applied mercury and mercury already present in the ecosystem and to examine bioaccumulation of mercury deposited to different parts of the watershed. Loading began in 2001 and ended in 2007. In this paper we will present mercury and methylmercury budgets for the study lake for the entire 7 year loading period. Overall, we increased the total Hg load to L658 and its watershed by roughly a factor of 3. However, we only increased the Hg load the lake itself by about 2X, since, during the seven years of addition, almost none of the Hg spike deposited to the watershed was transported all the way to the lake. Spike Hg concentrations in lake water rose each year during the open-water loading period and declined rapidly each winter. Methylmercury production in the lake responded rapidly to changes in mercury load during the first year of addition. After about 3 years, the increase in MeHg in lake water and in surface sediments slowed, suggesting that MeHg production was approaching a new level, or different rate, in response to the increased Hg load. We will discuss major input and loss terms for newly deposited Hg, the timing and proportionality of response, the timing and locations of MeHg production within the lake.

  5. Mercury(II) and methyl mercury speciation on Streptococcus pyogenes loaded Dowex Optipore SD-2.

    PubMed

    Tuzen, Mustafa; Uluozlu, Ozgur Dogan; Karaman, Isa; Soylak, Mustafa

    2009-09-30

    A solid phase extraction procedure based on speciation of mercury(II) and methyl mercury on Streptococcus pyogenes immobilized on Dowex Optipore SD-2 has been established. Selective and sequential elution with 0.1 mol L(-1) HCl for methyl mercury and 2 mol L(-1) HCl for mercury(II) were performed at pH 8. The determination of mercury levels was performed by cold vapour atomic absorption spectrometry (CVAAS). Optimal analytical conditions including pH, amounts of biosorbent, sample volumes, etc., were investigated. The influences of the some alkaline and earth alkaline ions and some transition metals on the recoveries were also investigated. The capacity of biosorbent for mercury(II) and methyl mercury was 4.8 and 3.4 mg g(-1). The detection limit (3 sigma) of the reagent blank for mercury(II) and methyl mercury was 2.1 and 1.5 ng L(-1). Preconcentration factor was calculated as 25. The relative standard deviations of the procedure were below 7%. The validation of the presented procedure is performed by the analysis of standard reference material (NRCC-DORM 2 Dogfish Muscle). The procedure was successfully applied to the speciation of mercury(II) and methyl mercury in natural water and environmental samples.

  6. Mercury in municipal solid wastes and New Jersey mercury prevention and reduction program

    SciTech Connect

    Erdogan, H.; Stevenson, E.

    1994-12-31

    Mercury is a very toxic heavy metal which accumulates in the brain causing neurological damages involving psychasthenic and vegetative syndrome. At high exposure levels it causes behavioral and personality changes, loss of memory and insomnia. Long-term exposure or exposure during pregnancy to mercury or mercury compounds can permanently damage the kidney and fetus. In addition to potential effects on human health, mercury poisoning can also affect other living organisms. Mercury is different than other heavy metals. It consistently biomagnifies and bioaccumulates within the aquatic food chain. Global sources of mercury release are both natural and anthropogenic. Natural sources include volatilization of gaseous-mercury iron soils ana rocks, volcanic releases, evaporation from the ocean and other water bodies. Anthropogenic sources are fuel and coal combustion, mining, smelting, manufacturing activities, disposal of sludge, pesticides, animal and food waste, and incineration of municipal solid waste. Worldwide combustion of municipal solid waste is the second largest source of atmospheric emission of mercury. In New Jersey, incineration of solid waste is the largest source of atmospheric emission of mercury. The New Jersey Department of Environmental Protection and Energy (NJDEPE) has developed a comprehensive program to control and prevent emission of mercury resulting from combustion municipal solid waste.

  7. MERCURY MEASUREMENTS FOR SOLIDS MADE RAPIDLY, SIMPLY, AND INEXPENSIVELY

    EPA Science Inventory

    While traditional methods for determining mercury in solid samples involve the use of aggressive chemicals to dissolve the matrix and the use of other chemicals to properly reduce the mercury to the volatile elemental form, pyrolysis-based analyzers can be used by directly weighi...

  8. Sources and sinks of filtered total mercury and concentrations of total mercury of solids and of filtered methylmercury, Sinclair Inlet, Kitsap County, Washington, 2007-10

    USGS Publications Warehouse

    Paulson, Anthony J.; Dinicola, Richard S.; Noble, Marlene A.; Wagner, Richard J.; Huffman, Raegan L.; Moran, Patrick W.; DeWild, John F.

    2012-01-01

    The majority of filtered total mercury in the marine water of Sinclair Inlet originates from salt water flowing from Puget Sound. About 420 grams of filtered total mercury are added to Sinclair Inlet each year from atmospheric, terrestrial, and sedimentary sources, which has increased filtered total mercury concentrations in Sinclair Inlet (0.33 nanograms per liter) to concentrations greater than those of the Puget Sound (0.2 nanograms per liter). The category with the largest loading of filtered total mercury to Sinclair Inlet included diffusion of porewaters from marine sediment to the water column of Sinclair Inlet and discharge through the largest stormwater drain on the Bremerton naval complex, Bremerton, Washington. However, few data are available to estimate porewater and stormwater releases with any certainty. The release from the stormwater drain does not originate from overland flow of stormwater. Rather total mercury on soils is extracted by the chloride ions in seawater as the stormwater is drained and adjacent soils are flushed with seawater by tidal pumping. Filtered total mercury released by an unknown freshwater mechanism also was observed in the stormwater flowing through this drain. Direct atmospheric deposition on the Sinclair Inlet, freshwater discharge from creek and stormwater basins draining into Sinclair Inlet, and saline discharges from the dry dock sumps of the naval complex are included in the next largest loading category of sources of filtered total mercury. Individual discharges from a municipal wastewater treatment plant and from the industrial steam plant of the naval complex constituted the loading category with the third largest loadings. Stormwater discharge from the shipyard portion of the naval complex and groundwater discharge from the base are included in the loading category with the smallest loading of filtered total mercury. Presently, the origins of the solids depositing to the sediment of Sinclair Inlet are uncertain, and

  9. Consequences of a solid inner core on Mercury's spin configuration

    NASA Astrophysics Data System (ADS)

    Peale, Stanton J.; Margot, Jean-Luc; Hauck, Steven A.; Solomon, Sean C.

    2016-01-01

    The pressure torque by a liquid core that drove Mercury to the nominal Cassini state of rotation is dominated by the torque from the solid inner core. The gravitational torque exerted on Mercury's mantle from an asymmetric solid inner core increases the equilibrium obliquity of the mantle spin axis. Since the observed obliquity of the mantle must be compatible with the presence of a solid inner core, the moment of inertia inferred from the occupancy of the Cassini state must be reduced to compensate the torque from the inner core and bring Mercury's spin axis to the observed position. The unknown size and shape of the inner core means that the moment of inertia is more uncertain than previously inferred.

  10. Mercury loads into the sea associated with extreme flood.

    PubMed

    Saniewska, Dominika; Bełdowska, Magdalena; Bełdowski, Jacek; Jędruch, Agnieszka; Saniewski, Michał; Falkowska, Lucyna

    2014-08-01

    Floods are an important factor determining riverine pollution loads, including toxic mercury (Hg). The impact of the Vistula River flood in 2010, which was the biggest one recorded in 160 years and its influence on marine environment was studied. Mercury concentration was analyzed in river and sea water, suspended matter, phytoplankton and sea surface sediment. Flood and gulf water contained several times higher concentration of Hg (exceeded reference values safe for aquatic organisms) than before or after the flood. In 2010 the Vistula introduced into the Baltic ca. 1576 kg of Hg, of which 75% can be attributed to the flood water. Increase of water temperature, decrease of oxygen content contended increasing of dissolved mercury concentration, which was transported far into the Baltic. This phenomenon led to an increase of Hg concentration in phytoplankton and during many months in surface sediments. It is a potential threat to marine organisms.

  11. Response of a macrotidal estuary to changes in anthropogenic mercury loading between 1850 and 2000

    USGS Publications Warehouse

    Sunderl, E.M.; Dalziel, J.; Heyes, A.; Branfireun, B.A.; Krabbenhoft, D.P.; Gobas, F.A.P.C.

    2010-01-01

    Methylmercury (MeHg) bioaccumulation in marine food webs poses risks to fish-consuming populations and wildlife. Here we develop and test an estuarine mercury cycling model for a coastal embayment of the Bay of Fundy, Canada. Mass budget calculations reveal that MeHg fluxes into sediments from settling solids exceed losses from sediment-to-water diffusion and resuspension. Although measured methylation rates in benthic sediments are high, rapid demethylation results in negligible net in situ production of MeHg. These results suggest that inflowing fluvial and tidal waters, rather than coastal sediments, are the dominant MeHg sources for pelagic marine food webs in this region. Model simulations show water column MeHg concentrations peaked in the 1960s and declined by almost40% by the year 2000. Water column MeHg concentrations respond rapidly to changes in mercury inputs, reaching 95% of steady state in approximately 2 months. Thus, MeHg concentrations in pelagic organisms can be expected to respond rapidly to mercury loading reductions achieved through regulatory controls. In contrast MeHg concentrations in sediments have steadily increased since the onset of industrialization despite recent decreases in total mercury loading. Benthic food web MeHg concentrations are likely to continue to increase over the next several decades at present-day mercury emissions levels because the deep active sediment layer in this system contains a large amount of legacy mercury and requires hundreds of years to reach steady state with inputs. ?? 2010 American Chemical Society.

  12. CHARACTERIZING SPATIAL AND TEMPORAL DYNAMICS: DEVELOPMENT OF A GRID-BASED WATERSHED MERCURY LOADING MODEL

    EPA Science Inventory

    A distributed grid-based watershed mercury loading model has been developed to characterize spatial and temporal dynamics of mercury from both point and non-point sources. The model simulates flow, sediment transport, and mercury dynamics on a daily time step across a diverse lan...

  13. Solid-loaded flows: applications in technology

    SciTech Connect

    Molerus, O.

    1983-01-01

    The evaluation of experiments and the representation of the resulting data by nondimensional groups defined ad hoc largely governs the treatment of problems arising with solid-loaded flows in practice. Without doubt, this is a result of the very complex nature of solid-loaded flows and, consequently, empiricism tends to prevail, more or less. To overcome this situation, two sets of nondimensional groups, which take into consideration the translatory, as well as the rotary, motion of particles suspended in a fluid, are derived from the equations of motion of a solid body. The intuitive meaning of these nondimensional groups arises from their derivation. With respect to applications in engineering, the influence of the rotary motion of a particle on the motion of its center of gravity can thus be taken into account. As such, a common basis for the representation of the different phenomena observed with solid-loaded flows is established. The application of the above concepts to fluidization and hydraulic and pneumatic conveying proves their usefulness. New insights into well-known facts as well as new results demonstrate that taking the real nature of solid particles (i.e., those of finite dimensions) into consideration will provide a common and profound basis for the representation of different phenomena observed with solid-loaded flows in practice.

  14. Methods for the preparation and analysis of solids and suspended solids for total mercury

    USGS Publications Warehouse

    Olund, Shane D.; DeWild, John F.; Olson, Mark L.; Tate, Michael T.

    2004-01-01

    The methods documented in this report are utilized by the Wisconsin District Mercury Lab for analysis of total mercury in solids (soils and sediments) and suspended solids (isolated on filters). Separate procedures are required for the different sample types. For solids, samples are prepared by room-temperature acid digestion and oxidation with aqua regia. The samples are brought up to volume with a 5 percent bromine monochloride solution to ensure complete oxidation and heated at 50?C in an oven overnight. Samples are then analyzed with an automated flow injection system incorporating a cold vapor atomic fluorescence spectrometer. A method detection limit of 0.3 ng of mercury per digestion bomb was established using multiple analyses of an environmental sample. Based on the range of masses processed, the minimum sample reporting limit varies from 0.6 ng/g to 6 ng/g. Suspended solids samples are oxidized with a 5 percent bromine monochloride solution and held at 50?C in an oven for 5 days. The samples are then analyzed with an automated flow injection system incorporating a cold vapor atomic fluorescence spectrometer. Using a certified reference material as a surrogate for an environmental sample, a method detection limit of 0.059 ng of mercury per filter was established. The minimum sample reporting limit varies from 0.059 ng/L to 1.18 ng/L, depending on the volume of water filtered.

  15. A tool for assessing mercury loadings from restored tidal systems

    USGS Publications Warehouse

    Fleck, J.A.; Bergamaschi, B.A.; Downing, B.D.; Lionberger, M.A.; Schoellhamer, D.H.; Boss, E.; Stephenson, M.

    2006-01-01

    Accurately quantifying net loads in tidal systems is difficult owing to the high variability in constituent concentrations over the vastly different time scales present in these systems. Perhaps most difficult is the measurement of fluxed over the tidal time scale. On this scale, the net export of the constituent is orders of magnitude less than the bulk exchange in either direction because of the vast quantities of water that are exchanged. Therefore, numerous measurements are required in a brief amount of time to accurately quantify constituent fluxes between a tidal wetland and its surrounding waters. These complications with sampling are exacerbated for mercury species because of the difficulties is to develop surrogates that may be measured in situ and which may be used for interpolating and extrapolating from discrete measurements over a number of tidal cycles and a range of conditions.  

  16. Climate driven release of carbon and mercury from permafrost mires increases mercury loading to sub-arctic lakes.

    PubMed

    Rydberg, Johan; Klaminder, Jonatan; Rosén, Peter; Bindler, Richard

    2010-09-15

    In sub-arctic and arctic regions mercury is an element of concern for both wildlife and humans. Over thousands of years large amounts of atmospherically deposited mercury, both from natural and anthropogenic sources, have been sequestered together with carbon in northern peatlands. Many of these peatlands are currently underlain by permafrost, which controls mire stability and hydrology. With the ongoing climate change there is concern that permafrost thawing will turn large areas of these northern peatlands from carbon/mercury-sinks into much wetter carbon/mercury-sources. Here we can show that such a change in mire structure in the sub-arctic Stordalen mire in northern Sweden actually is responsible for an increased export of mercury to the adjacent lake Inre Harrsjön. We also show that sediment mercury accumulation rates during a warm period in the pre-industrial past were higher than in the 1970s when atmospheric input peaked, indicating that in areas with permafrost, climate can have an effect on mercury loading to lakes as large as anthropogenic emissions. Thawing of permafrost and the subsequent export of carbon is a widespread phenomenon, and the projection is that it will increase even more in the near future. Together with our observations from Stordalen, this makes northern peatlands into a substantial source of mercury, at risk of being released into sensitive arctic freshwater and marine systems.

  17. Mercury in municipal solid waste in China and its control: a review.

    PubMed

    Cheng, Hefa; Hu, Yuanan

    2012-01-17

    Although a potentially significant and preventable source of environmental pollution, mercury in municipal solid waste (MSW) has not received adequate attention in China. Discarded mercury-containing products, if not recycled, ultimately release mercury to air, soil, and groundwater, even after being properly collected and disposed of in MSW management facilities. This review presents an overview on mercury in MSW and describes the emissions associated with landfilling, incineration, and composting in China. Besides end-of-pipe technologies for controlling mercury emissions from MSW management, strategies for controlling mercury in MSW are also discussed, focusing on mercury source reduction and recycling. Batteries and fluorescent lamps contribute to approximately three-quarters of mercury in MSW, and are expected to remain as significant sources of mercury in the near future. Reducing or eliminating the mercury contents in household products, particularly batteries and fluorescent lamps, should be the top priority in controlling mercury in MSW, while it is also important to set mercury contents in consumer products at acceptable and achievable levels based on a life-cycle approach. Meanwhile, cost-effective recycling programs should be developed targeting products containing elemental mercury, such as medical thermometers and sphygmomanometers, and waste products with high mercury contents (e.g., button cells) as well. PMID:22136661

  18. Forest harvest contribution to Boreal freshwater methyl mercury load

    NASA Astrophysics Data System (ADS)

    Kronberg, Rose-Marie; Drott, Andreas; Jiskra, Martin; Wiederhold, Jan G.; Björn, Erik; Skyllberg, Ulf

    2016-06-01

    Effects of Boreal forest harvest on mercury (Hg) and methyl mercury (MeHg) soil pools and export by stream runoff were quantified by comparing 10 reference watersheds (REFs) covered by >80 year old Norway spruce (Picea abies Karst.) forests with 10 similar watersheds subjected to clear-cutting (CCs). While total Hg soil storage did not change, MeHg pools increased seven times (p = 0.006) in the organic topsoil 2 years after clear-cutting. In undulating terrain, situated above the postglacial marine limit (ML) of the ancient Baltic Sea, the mass ratio between flux-weighted MeHg and dissolved organic carbon (MeHg/DOC) in stream runoff increased 1.8 times (p < 0.004) as a consequence of forest harvest. When recalculated to 100% clear-cutting of the watershed, the annual MeHg stream export increased 3.8 times (p = 0.047). Below the ML, where the terrain was flatter, neither the MeHg/DOC ratio nor the annual export of MeHg differed between REFs and CCs, likely because of the larger contribution of MeHg exported from peaty soils and small wetlands. The most robust measure, MeHg/DOC, was used to calculate MeHg loadings to Boreal headwaters. If the forest harvest effect lasts 10 years, clear-cutting increases MeHg runoff by 12-20% in Sweden and 2% in the Boreal zone as a whole. In Sweden, having intensely managed forests, 37% and 56% of MeHg are exported from peatlands and forest soils, respectively, and forest clear-cutting is adding another 6.6%. In the Boreal zone as a whole peatlands and forests soils contribute with 53% and 46%, respectively, and clear-cutting is estimated to add another 1.0%. An expected rapid increase in Boreal forest harvest and disturbance urge for inclusion of land use effects in mercury biogeochemical cycling models at different scales.

  19. Mercury

    SciTech Connect

    Vilas, F.; Chapman, C.R.; Matthews, M.S.

    1988-01-01

    Papers are presented on future observations of and missions to Mercury, the photometry and polarimetry of Mercury, the surface composition of Mercury from reflectance spectrophotometry, the Goldstone radar observations of Mercury, the radar observations of Mercury, the stratigraphy and geologic history of Mercury, the geomorphology of impact craters on Mercury, and the cratering record on Mercury and the origin of impacting objects. Consideration is also given to the tectonics of Mercury, the tectonic history of Mercury, Mercury's thermal history and the generation of its magnetic field, the rotational dynamics of Mercury and the state of its core, Mercury's magnetic field and interior, the magnetosphere of Mercury, and the Mercury atmosphere. Other papers are on the present bounds on the bulk composition of Mercury and the implications for planetary formation processes, the building stones of the planets, the origin and composition of Mercury, the formation of Mercury from planetesimals, and theoretical considerations on the strange density of Mercury.

  20. Estimation of a Historic Mercury Load Function for Lake Michigan using Dated Sediment Cores

    EPA Science Inventory

    Box cores collected between 1994 and 1996 were used to estimate historic mercury loads to Lake Michigan. Based on a kriging spatial interpolation of 54 Pb-210 dated cores, 228 metric tons of mercury are stored in the lake’s sediments (excluding Green Bay). To estimate the time ...

  1. Sustained release Curcumin loaded Solid Lipid Nanoparticles

    PubMed Central

    Jourghanian, Parisa; Ghaffari, Solmaz; Ardjmand, Mehdi; Haghighat, Setareh; Mohammadnejad, Mahdieh

    2016-01-01

    Purpose: curcumin is poorly water soluble drug with low bioavailability. Use of lipid systems in lipophilic substances increases solubility and bioavailability of poorly soluble drugs. The aim of this study was to prepare curcumin loaded Solid Lipid Nanoparticles (SLNs) with high loading efficiency, small particle size and prolonged release profile with enhanced antibacterial efficacy. Methods: to synthesize stable SLNs, freeze- Drying was done using mannitol as cryoprotectant. Cholesterol was used as carrier because of good tolerability and biocompatibility. SLNs were prepared using high pressure homogenization method. Results: optimized SLNs had 112 and 163 nm particle size before and after freeze drying, respectively. The prepared SLNs had 71% loading efficiency. 90% of loaded curcumin was released after 48 hours. Morphologic study for formulation was done by taking SEM pictures of curcumin SLNs. Results show the spherical shape of curcumin SLNs. DSC studies were performed to determine prolonged release mechanism. Antimicrobial studies were done to compare the antimicrobial efficacy of curcumin SLNs with free curcumin. DSC studies showed probability of formation of hydrogen bonds between cholesterol and curcumin which resulted in prolonged release of curcumin. Lipid structure of cholesterol could cause enhanced permeability in studied bacteria to increase antibacterial characteristics of curcumin. Conclusion: the designed curcumin SLNs could be candidate for formulation of different dosage forms or cosmeceutical products. PMID:27123413

  2. Mercury air-borne emissions from 5 municipal solid waste landfills in Guiyang and Wuhan, China

    NASA Astrophysics Data System (ADS)

    Li, Z. G.; Feng, X.; Li, P.; Liang, L.; Tang, S. L.; Wang, S. F.; Fu, X. W.; Qiu, G. L.; Shang, L. H.

    2010-01-01

    A detailed study on atmospheric mercury emissions from municipal solid waste (MSW) landfills in China is necessary to understand mercury behavior in this source category, simply because China disposes of bulk MSW by landfilling and a large quantity of mercury enters into landfills. Between 2003 and 2006, mercury airborne emissions through different pathways, as well as mercury speciation in landfill gas (LFG) were measured at 5 MSW landfills in Guiyang and Wuhan, China. The results showed that mercury content in the substrate fundamentally affected the magnitude of mercury emissions, resulting in the highest emission rate (as high as 57 651 ng Hg m-2 h-1) at the working face and in un-covered waste areas, and the lowest measured at soil covers and vegetation areas (less than 20 ng Hg m-2 h-1). Meteorological parameters, especially solar radiation, influenced the diurnal pattern of mercury surface-air emissions. Total gaseous mercury (TGM) in LFG varied from 2.0 to 1406.0 ng m-3, monomethyl mercury (MMHg) and dimethyl mercury (DMHg) in LFG averaged at 1.93 and 9.21 ng m-3, and accounted for 0.51% and 1.79% of the TGM in the LFG, respectively. Total mercury emitted from the five landfills ranged from 17 to 3285 g yr-1, with the highest from the working face, then soil covering, and finally the vent pipes.

  3. Mercury

    MedlinePlus

    ... of the lungs Medicine to remove mercury and heavy metals from the body INORGANIC MERCURY For inorganic mercury ... Baum CR. Mercury: Heavy metals and inorganic agents. In: Shannon MW, ... Haddad and Winchester's Clinical Management of Poisoning and ...

  4. Can a solid FeS layer help explain Mercury's unique magnetic field?

    NASA Astrophysics Data System (ADS)

    Vilim, R.; Stanley, S.

    2014-12-01

    The origin of Mercury's weak magnetic field and displaced magnetic equator remains poorly understood. While the field is likely generated by a planetary dynamo in the iron core of Mercury, producing a weak dipolar magnetic field with a displaced magnetic equator has proven to be a challenge for dynamo modelers. Recent gravity measurements from the MESSENGER probe allow for a solid, dense layer at the base of Mercury's mantle. The authors of this study have suggested that this could be a solid layer of FeS. This solid FeS could reduce the observed field strength due to the electromagnetic skin effect. It may also affect the character of the dynamo by coupling to the fluid flow via the Lorenz force. We use a numerical dynamo model with an electrically conducting, solid mantle layer to determine whether this solid layer can help produce the strength and morphology of Mercury's magnetic field.

  5. PRESENTED 04/05/2006: MERCURY MEASUREMENTS FOR SOLIDS MADE RAPIDLY, SIMPLY, AND INEXPENSIVELY

    EPA Science Inventory

    While traditional methods for determining mercury in solid samples involve the use of aggressive chemicals to dissolve the matrix and the use of other chemicals to properly reduce the mercury to the volatile elemental form, pyrolysis-based analyzers can be used by directly weighi...

  6. TELEPHONIC PRESENTATION: MERCURY MEASUREMENTS FOR SOLIDS MADE RAPIDLY, SIMPLY, AND INEXPENSIVELY

    EPA Science Inventory

    While traditional methods for determining mercury in solid samples involve the use of aggressive chemicals to dissolve the matrix and the use of other chemicals to properly reduce the mercury to the volatile elemental form, pyrolysis-based analyzers can be used by directly weighi...

  7. PRESENTED MAY 10, 2005, MERCURY MEASUREMENTS FOR SOLIDS MADE RAPIDLY, SIMPLY, AND INEXPENSIVELY

    EPA Science Inventory

    While traditional methods for determining mercury in solid samples involve the use of aggressive chemicals to dissolve the matrix and the use of other chemicals to properly reduce the mercury to the volatile elemental form, pyrolysis-based analyzers can be used by directly weighi...

  8. FGD Additives to Segregate and Sequester Mercury in Solid Byproducts - Final Report

    SciTech Connect

    Searcy, K; Bltyhe, G M; Steen, W A

    2012-02-28

    Many mercury control strategies for U.S. coal-fired power generating plants involve co-benefit capture of oxidized mercury from flue gases treated by wet flue gas desulfurization (FGD) systems. For these processes to be effective at overall mercury control, the captured mercury must not be re-emitted to the atmosphere or into surface or ground water. The project sought to identify scrubber additives and FGD operating conditions under which mercury re-emissions would decrease and mercury would remain in the liquor and be blown down from the system in the chloride purge stream. After exiting the FGD system, mercury would react with precipitating agents to form stable solid byproducts and would be removed in a dewatering step. The FGD gypsum solids, free of most of the mercury, could then be disposed or processed for reuse as wallboard or in other beneficial reuse. The project comprised extensive bench-scale FGD scrubber tests in Phases I and II. During Phase II, the approaches developed at the bench scale were tested at the pilot scale. Laboratory wastewater treatment tests measured the performance of precipitating agents in removing mercury from the chloride purge stream. Finally, the economic viability of the approaches tested was evaluated.

  9. Total mercury loadings in sediment from gold mining and conservation areas in Guyana.

    PubMed

    Howard, Joniqua; Trotz, Maya A; Thomas, Ken; Omisca, Erlande; Chiu, Hong Ting; Halfhide, Trina; Akiwumi, Fenda; Michael, Ryan; Stuart, Amy L

    2011-08-01

    The Low Carbon Development Strategy proposed in June 2009 by the government of Guyana in response to the Reducing Emissions from Deforestation and Forest Degradation in Developing Countries program has triggered evaluation of forest-related activities, thereby acting as a catalyst for improvements in Guyana's small- to medium-scale gold mining industry. This has also shed light on areas committed to conservation, something that has also been handled by Non Governmental Organizations. This paper compares water quality and mercury concentrations in sediment from four main areas in Guyana, two that are heavily mined for gold using mercury amalgamation methods (Arakaka and Mahdia) and two that are considered conservation areas (Iwokrama and Konashen). Fifty-three sediment and soil mercury loadings ranged from 29 to 1,200 ng/g and averaged 215 ± 187 ng/g for all sites with similar averages in conservation and mining areas. Sediment loadings are within the range seen in French Guiana and Suriname, but conservation area samples had higher loadings than the corresponding uncontaminated baselines. Type of ore and location in the mining process seemed to influence mercury loadings. Mercury sediment loadings were slightly positively correlated with pH (correlation coefficient = 0.2; p value < 0.001) whereas no significant correlations were found with dissolved oxygen or turbidity.

  10. Mercury and methylmercury concentrations and loads in the Cache Creek watershed, California.

    PubMed

    Domagalski, Joseph L; Alpers, Charles N; Slotton, Darell G; Suchanek, Thomas H; Ayers, Shaun M

    2004-07-01

    Concentrations and loads of total mercury and methylmercury were measured in streams draining abandoned mercury mines and in the proximity of geothermal discharge in the Cache Creek watershed of California during a 17-month period from January 2000 through May 2001. Rainfall and runoff were lower than long-term averages during the study period. The greatest loading of mercury and methylmercury from upstream sources to downstream receiving waters, such as San Francisco Bay, generally occurred during or after winter rainfall events. During the study period, loads of mercury and methylmercury from geothermal sources tended to be greater than those from abandoned mining areas, a pattern attributable to the lack of large precipitation events capable of mobilizing significant amounts of either mercury-laden sediment or dissolved mercury and methylmercury from mine waste. Streambed sediments of Cache Creek are a significant source of mercury and methylmercury to downstream receiving bodies of water. Much of the mercury in these sediments is the result of deposition over the last 100-150 years by either storm-water runoff, from abandoned mines, or continuous discharges from geothermal areas. Several geochemical constituents were useful as natural tracers for mining and geothermal areas, including the aqueous concentrations of boron, chloride, lithium and sulfate, and the stable isotopes of hydrogen and oxygen in water. Stable isotopes of water in areas draining geothermal discharges showed a distinct trend toward enrichment of (18)O compared with meteoric waters, whereas much of the runoff from abandoned mines indicated a stable isotopic pattern more consistent with local meteoric water.

  11. Mercury and methylmercury concentrations and loads in the Cache Creek watershed, California

    USGS Publications Warehouse

    Domagalski, J.L.; Alpers, C.N.; Slotton, D.G.; Suchanek, T.H.; Ayers, S.M.

    2004-01-01

    Concentrations and loads of total mercury and methylmercury were measured in streams draining abandoned mercury mines and in the proximity of geothermal discharge in the Cache Creek watershed of California during a 17-month period from January 2000 through May 2001. Rainfall and runoff were lower than long-term averages during the study period. The greatest loading of mercury and methylmercury from upstream sources to downstream receiving waters, such as San Francisco Bay, generally occurred during or after winter rainfall events. During the study period, loads of mercury and methylmercury from geothermal sources tended to be greater than those from abandoned mining areas, a pattern attributable to the lack of large precipitation events capable of mobilizing significant amounts of either mercury-laden sediment or dissolved mercury and methylmercury from mine waste. Streambed sediments of Cache Creek are a significant source of mercury and methylmercury to downstream receiving bodies of water. Much of the mercury in these sediments is the result of deposition over the last 100-150 years by either storm-water runoff, from abandoned mines, or continuous discharges from geothermal areas. Several geochemical constituents were useful as natural tracers for mining and geothermal areas, including the aqueous concentrations of boron, chloride, lithium and sulfate, and the stable isotopes of hydrogen and oxygen in water. Stable isotopes of water in areas draining geothermal discharges showed a distinct trend toward enrichment of 18O compared with meteoric waters, whereas much of the runoff from abandoned mines indicated a stable isotopic pattern more consistent with local meteoric water. ?? 2004 Elsevier B.V. All rights reserved.

  12. Sampling for mercury at subnanogram per litre concentrations for load estimation in rivers

    USGS Publications Warehouse

    Colman, J.A.; Breault, R.F.

    2000-01-01

    Estimation of constituent loads in streams requires collection of stream samples that are representative of constituent concentrations, that is, composites of isokinetic multiple verticals collected along a stream transect. An all-Teflon isokinetic sampler (DH-81) cleaned in 75??C, 4 N HCl was tested using blank, split, and replicate samples to assess systematic and random sample contamination by mercury species. Mean mercury concentrations in field-equipment blanks were low: 0.135 ng??L-1 for total mercury (??Hg) and 0.0086 ng??L-1 for monomethyl mercury (MeHg). Mean square errors (MSE) for ??Hg and MeHg duplicate samples collected at eight sampling stations were not statistically different from MSE of samples split in the laboratory, which represent the analytical and splitting error. Low fieldblank concentrations and statistically equal duplicate- and split-sample MSE values indicate that no measurable contamination was occurring during sampling. Standard deviations associated with example mercury load estimations were four to five times larger, on a relative basis, than standard deviations calculated from duplicate samples, indicating that error of the load determination was primarily a function of the loading model used, not of sampling or analytical methods.

  13. The removal of mercury from solid mixed waste using chemical leaching processes

    SciTech Connect

    Gates, D.D.; Chao, K.K.; Cameron, P.A.

    1995-07-01

    The focus of this research was to evaluate chemical leaching as a technique to treat soils, sediments, and glass contaminated with either elemental mercury or a combination of several mercury species. Potassium iodide/iodine solutions were investigated as chemical leaching agents for contaminated soils and sediments. Clean, synthetic soil material and surrogate storm sewer sediments contaminated with mercury were treated with KI/I{sub 2} solutions. It was observed that these leaching solutions could reduce the mercury concentration in soil and sediments by 99.8%. Evaluation of selected posttreatment sediment samples revealed that leachable mercury levels in the treated solids exceeded RCRA requirements. The results of these studies suggest that KI/I{sub 2} leaching is a treatment process that can be used to remove large quantities of mercury from contaminated soils and sediments and may be the only treatment required if treatment goals are established on Hg residual concentrations in solid matrices. Fluorescent bulbs were used to simulate mercury contaminated glass mixed waste. To achieve mercury contamination levels similar to those found in larger bulbs such as those used in DOE facilities a small amount of Hg was added to the crushed bulbs. The most effective agents for leaching mercury from the crushed fluorescent bulbs were KI/I{sub 2}, NaOCl, and NaBr + acid. Radionuclide surrogates were added to both the EPA synthetic soil material and the crushed fluorescent bulbs to determine the fate of radionuclides following chemical leaching with the leaching agents determined to be the most promising. These experiments revealed that although over 98% of the dosed mercury solubilized and was found in the leaching solution, no Cerium was measured in the posttreatment leaching solution. This finding suggest that Uranium, for which Ce was used as a surrogate, would not solubilize during leaching of mercury contaminated soil or glass.

  14. [Mercury pollution investigation in predominant plants surrounding Shenzhen Qingshuihe municipal solid waste incineration plant].

    PubMed

    Zhao, Hong-Wei; Zhong, Xiu-Ping; Liu, Yang-Sheng; Wang, Jun-Jian; Hong, Yuan; Zhao, Kang-Sai; Zeng, Hui

    2009-09-15

    In order to investigate the effects of mercury emission from municipal solid waste incineration (MSWI) on the surrounding plants and soils, the mercury concentrations were examined in the plant samples including leaves and stems and the soil samples around Shenzhen Qingshuihe MSWI Plant. Results show that, these plants are significantly polluted by mercury, the mercury concentrations of the plant leaves are 0.030 9-0.246 7 mg x kg(-1), with the mean value 0.094 8 mg x kg(-1), among the local prominent plants, the mercury concentrations in the leaves are in the order of: Acacia confuse > Litsea rotundifolia > Acacia mangium > Acacia auriculaeformis > Schima superb > Ilex asprella. The mercury concentrations of the plant stems are 0.007 4-0.119 6 mg x kg(-1), with the mean value 0.041 7 mg x kg(-1). For the same plant, the mercury concentration in its leaf correlates positively with that in its stem, but presents little correlation with that in the soil where it grows. Under the direction of the dominant wind, the concentration of smoke diffusion is often influenced by the distance from the stack and the difference of terrain. The mercury concentrations of the plant leaves and stems vary almost in accordance with spatial heterogeneity patterns of smoke diffusion. These results demonstrate that the interaction of the smoke and plant leaves play the leading role in the mercury exchange between plants and environment.

  15. Terrestrial Loads of Mercury in a River Catchment Impacted by Former Mercury Mining Activity - GIS Approach

    NASA Astrophysics Data System (ADS)

    Kocman, D.; Horvat, M.

    2010-12-01

    Mercury (Hg) mining activities in Idrija, Slovenia, have resulted in significant contamination to surrounding local environments. Due to the abundant precipitation, steep slopes and highly erodible underlying lithology, this region is especially prone to erosion. Hence, even today, due to the lack of proper remediation actions, Hg contaminated soils, Hg-laden material and tailings continue to supply Hg to the local river system and consequently to the Gulf of Trieste in N Adriatic. In addition, significant amounts of elemental Hg from these areas are emitted to the atmosphere. In this contribution, environmental modeling of mercury in the Idrijca River catchment (640 km2) as a tool for sound remediation planning will be discussed. Based on the experimental results, a mass-balance model of sources, sinks and mercury transport process on the catchment scale was developed within the GIS environment. The model is based upon mercury mass-balance calculations as a combination of different approaches (WCS mercury tool and Erosion Potential Model coupled with newly developed GIS emission model) adopted for site specific conditions. In this way, accounting for Hg entering and leaving the catchment, its mass flows, flux rates, and turnover times were identified. Moreover, spatial distribution and significance of most polluted sites that need to be properly managed were assessed. The developed model can be used as an efficient tool for remediation interventions planning as well as to check the effects of management choices which would minimize the uncertainties in the process of decision making.

  16. Mercury

    MedlinePlus

    Mercury is an element that is found in air, water and soil. It has several forms. Metallic mercury is a shiny, silver-white, odorless liquid. If ... with other elements to form powders or crystals. Mercury is in many products. Metallic mercury is used ...

  17. MESSENGER observations of extreme loading and unloading of Mercury's magnetic tail.

    PubMed

    Slavin, James A; Anderson, Brian J; Baker, Daniel N; Benna, Mehdi; Boardsen, Scott A; Gloeckler, George; Gold, Robert E; Ho, George C; Korth, Haje; Krimigis, Stamatios M; McNutt, Ralph L; Nittler, Larry R; Raines, Jim M; Sarantos, Menelaos; Schriver, David; Solomon, Sean C; Starr, Richard D; Trávnícek, Pavel M; Zurbuchen, Thomas H

    2010-08-01

    During MESSENGER's third flyby of Mercury, the magnetic field in the planet's magnetic tail increased by factors of 2 to 3.5 over intervals of 2 to 3 minutes. Magnetospheric substorms at Earth are powered by similar tail loading, but the amplitude is lower by a factor of approximately 10 and typical durations are approximately 1 hour. The extreme tail loading observed at Mercury implies that the relative intensity of substorms must be much larger than at Earth. The correspondence between the duration of tail field enhancements and the characteristic time for the Dungey cycle, which describes plasma circulation through Mercury's magnetosphere, suggests that such circulation determines the substorm time scale. A key aspect of tail unloading during terrestrial substorms is the acceleration of energetic charged particles, but no acceleration signatures were seen during the MESSENGER flyby. PMID:20647422

  18. MESSENGER Observations of Extreme Loading and Unloading of Mercury's Magnetic Tail

    NASA Technical Reports Server (NTRS)

    Slavin, James A.; Anderson, Brian J.; Baker, Daniel N.; Benna, Mehdi; Boardsen, Scott A.; Gloeckler, George; Gold, Robert E.; Ho, George C.; Korth, Haje; Krimigis, Stamatios M.; McNutt, Ralph L.; Nittler, Larry R.; Raines, Jim M.; Sarantos, Menelaos; Schriver, David; Solomon, Sean C.; Starr, Richard D.; Travnicek, Pavel M.; Zurbuchen, Thomas H.

    2010-01-01

    During MESSENGER's third flyby of Mercury, a series of 2-3 minute long enhancements of the magnetic field in the planet's magnetotail were observed. Magnetospheric substorms at Earth are powered by similar tail loading, but the amplitude is approximately 10 times less and the durations are 1 hr. These observations of extreme loading imply that the relative intensity of substorms at Mercury must be much larger than at Earth. The correspondence between the duration of tail enhancements and the calculated approximately 2 min Dungey cycle, which describes plasma circulation through Mercury's magnetosphere, suggests that such circulation determines substorm timescale. A key aspect of tail unloading during terrestrial substorms is the acceleration of energetic charged particles. Such signatures are puzzlingly absent from the MESSENGER flyby measurements.

  19. MESSENGER Observations of Extreme Loading and Unloading of Mercury's Magnetic Tail

    NASA Technical Reports Server (NTRS)

    Slavin, James A.; Anderson, Brian J.; Baker, Daniel N.; Benna, Mehdi; Boardsen, Scott A.; Gloeckler, George; Gold, Robert E.; Ho, George C.; Korth, Haje; Krimigis, Stamatios M.; McNutt, Ralph L., Jr.; Nittler, Larry R.; Raines, Jim M.; Sarantos, Menelaos; Schriver, David; Solomon, Sean C.; Starr, Richard D.; Travnicek, Pavel M.; Zurbuchen, Thomas H.

    2010-01-01

    During MESSENGER's third flyby of Mercury, the magnetic field in the planet's magnetotail increased by factors of 2 to 3.5 over intervals of 2 to 3 min. Magnetospheric substorms at Earth are powered by similar tail loading, but the amplitude is approx.10 times less and typical durations are approx.1 hour. The extreme tail loading observed at Mercury implies that the relative intensity of sub storms must be much larger than at Earth. The correspondence between the duration of tail field enhancements and the characteristic time for the Dungey cycle, which describes plasma circulation through Mercury's magnetosphere. suggests that such circulation determines substorm timescale. A key aspect of tail unloading during terrestrial substorms is the acceleration of energetic charged particles, but no acceleration signatures were seen during the MESSENGER flyby.

  20. Mercury and Methylmercury concentrations and loads in Cache Creek Basin, California, January 2000 through May 2001

    USGS Publications Warehouse

    Domagalski, Joseph L.; Alpers, Charles N.; Slotton, Darrell G.; Suchanek, Thomas H.; Ayers, Shaun M.

    2004-01-01

    Concentrations and mass loads of total mercury and methylmercury in streams draining abandoned mercury mines and near geothermal discharge in Cache Creek Basin, California, were measured during a 17-month period from January 2000 through May 2001. Rainfall and runoff averages during the study period were lower than long-term averages. Mass loads of mercury and methylmercury from upstream sources to downstream receiving waters, such as San Francisco Bay, were generally the highest during or after winter rainfall events. During the study period, mass loads of mercury and methylmercury from geothermal sources tended to be greater than those from abandoned mining areas because of a lack of large precipitation events capable of mobilizing significant amounts of either mercury-laden sediment or dissolved mercury and methylmercury from mine waste. Streambed sediments of Cache Creek are a source of mercury and methylmercury to downstream receiving bodies of water such as the Delta of the San Joaquin and Sacramento Rivers. Much of the mercury in these sediments was deposited over the last 150 years by erosion and stream discharge from abandoned mines or by continuous discharges from geothermal areas. Several geochemical constituents were useful as natural tracers for mining and geothermal areas. These constituents included aqueous concentrations of boron, chloride, lithium, and sulfate, and the stable isotopes of hydrogen and oxygen in water. Stable isotopes of water in areas draining geothermal discharges were enriched with more oxygen-18 relative to oxygen-16 than meteoric waters, whereas the enrichment by stable isotopes of water from much of the runoff from abandoned mines was similar to that of meteoric water. Geochemical signatures from stable isotopes and trace-element concentrations may be useful as tracers of total mercury or methylmercury from specific locations; however, mercury and methylmercury are not conservatively transported. A distinct mixing trend of

  1. Fate of elemental mercury in the Arctic during atmospheric mercury depletion episodes and the load of atmospheric mercury to the Arctic.

    PubMed

    Skov, Henrik; Christensen, Jesper H; Goodsite, Michael E; Heidam, Niels Z; Jensen, Bjarne; Wåhlin, Peter; Geernaert, Gerald

    2004-04-15

    calculations were performed with and without AMDEs. For the area north of the Polar Circle, the mercury deposition increases from 89 tons/year for calculations without an AMDE to 208 tons/year with the AMDE. The 208 tons/year represent an upper limit for the mercury load to the Artic.

  2. Mercury speciation in seawater by liquid chromatography-inductively coupled plasma-mass spectrometry following solid phase extraction pre-concentration by using an ionic imprinted polymer based on methyl-mercury-phenobarbital interaction.

    PubMed

    Rodríguez-Reino, María Pilar; Rodríguez-Fernández, Roi; Peña-Vázquez, Elena; Domínguez-González, Raquel; Bermejo-Barrera, Pilar; Moreda-Piñeiro, Antonio

    2015-04-24

    Trace levels of inorganic mercury, methyl-mercury and ethyl-mercury have been assessed in seawater by high performance liquid chromatography (HPLC) hyphenated with inductively coupled plasma-mass spectrometry (ICP-MS) after solid phase extraction (SPE) pre-concentration with a novel synthesized ionic imprinted polymer. The adsorbent material was prepared by trapping a non-vinylated chelating ligand (phenobarbital) via imprinting of a ternary mixed ligand complex of the non-vinylated chelating agent, the template (methyl-mercury), and the vinyl ligand (metacrylic acid, MAA). Ethylene dimetacrylate (EDMA) and 2,2'-azobisisobutyronitrile (AIBN) were used as cross-linker and initiator reagents, respectively; and the precipitation polymerization technique was used in a porogen of acetonitrile/water (4:1). The best retention properties for methyl-mercury, inorganic mercury and ethyl-mercury species from seawater were obtained when loading 200 mL of sample adjusted to pH 8.0 and at a flow rate of 2.0 mL min(-1) on a column-packed with 200mg of the material. Quantitative mercury species recoveries were obtained using 4 mL of an eluting solution consisting of 0.8% (v/v) 2-mercaptoethanol and 20% (v/v) methanol (pH adjusted to 4.5) pumped at a flow rate of 2.0 mL min(-1). Mercury species separation was achieved on a Kinetex C18 column working under isocratic conditions (0.4% (v/v) 2-mercaptoethanol, 10% (v/v) methanol, pH 2.5, flow rate 0.7 mL min(-1)). ICP-MS detection was performed by monitoring the mercury mass to charge ratio of 202. The limits of quantification of the method were 11, 6.7, and 12 ng L(-1), for inorganic mercury, methyl-mercury and ethyl-mercury, respectively (pre-concentration factor of 50); whereas, analytical recoveries ranged from 96 to 106%. The developed method was successfully applied to several seawater samples from unpolluted areas.

  3. Spatial and temporal trends of mercury loadings to Michigan inland lakes

    SciTech Connect

    Matthew J. Parsons; David T. Long; Sharon S. Yohn; John P. Giesy

    2007-08-15

    Several studies of chronologies of mercury (Hg) in inland lake sediments have demonstrated that Hg accumulation decreased in recent decades. However, episodic mercury accumulation events were recorded in some of these lakes, but not investigated in detail. Recent decreases had been attributed to the reduction of regional Hg consumption and secondary removal during process waste treatment. In addition to regional sources, local sources, including watershed disturbance, might significantly contribute to Hg loading. Here, mercury chronologies of Hg loadings based on dated sediment cores are presented for 26 inland Michigan lakes. Although spatial trends of anthropogenic inventories suggest a regional pattern dominated by human activities, sub-regional to local scale sources are also found to be significant. Temporal trends show episodic Hg accumulation events superimposed on a more general, long-term trend. Episodic increases common to lakes suggest a common source or processes common to lakes. Episodic increases unique to a lake indicate a more local scale source. Similar Hg profiles from lakes that are geographically proximal provide evidence for sub-regional to regional scale sources. Local sources and pathways for mercury to inland lakes need to be more fully understood to effectively reduce Hg loading to the environment. 48 refs., 7 figs.

  4. MESSENGER Observations of Extreme Magnetic Tail Loading and Unloading During its Third Flyby of Mercury: Substorms?

    NASA Technical Reports Server (NTRS)

    Slavin, James A.; Anderson, Brian J.; Baker, Daniel N.; Benna, Mehdi; Gloeckler, George; Krimigis, Stamatios M.; McNutt, Ralph L., Jr.; Schriver, David; Solomon, Sean C.; Zurbuchen, Thomas H.

    2010-01-01

    During MESSENGER's third flyby of Mercury on September 29, 2009, a variable interplanetary magnetic field produced a series of several minute enhancements of the tail magnetic field hy factors of approx. 2 to 3.5. The magnetic field flaring during these intervals indicates that they result from loading of the tail with magnetic flux transferred from the dayside magnetosphere. The unloading intervals were associated with plasmoids and traveling compression regions, signatures of tail reconnection. The peak tail magnetic flux during the smallest loading events equaled 30% of the magnetic flux emanating from Mercury, and may have reached 100% for the largest event. In this case the dayside magnetic shielding is reduced and solar wind flux impacting the surface may be greatly enhanced. Despite the intensity of these events and their similarity to terrestrial substorm magnetic flux dynamics, no energetic charged particles with energies greater than 36 keV were observed.

  5. Application of thermal desorption for the identification of mercury species in solids derived from coal utilization.

    PubMed

    Rumayor, M; Diaz-Somoano, M; Lopez-Anton, M A; Martinez-Tarazona, M R

    2015-01-01

    The speciation of mercury is currently attracting widespread interest because the emission, transport, deposition and behaviour of toxic mercury species depend on its chemical form. The identification of these species in low concentrations is no easy task and it is even more complex in coal combustion products due to the fact that these products contain organic and mineral matter that give rise to broad peaks and make it difficult to carry out qualitative and quantitative analysis. In this work, a solution to this problem is proposed using a method based on thermal desorption. A sequential extraction procedure was employed for the comparison and validation of the method developed. Samples of fly ashes and soils were analyzed by both of these methods, and thermal desorption was found to be an appropriate technique for mercury speciation. Even in the case of low mercury contents, recovery percentages were close to 100%. The main mercury species identified in the samples studied were HgS and, to a lesser extent, HgO and HgSO4. In addition, although the presence of mercury complexes cannot be demonstrated, the desorption behaviour and sequential extraction results suggest that this element might be associated with the mineral matrix or with carbon particles in some of the solids.

  6. Mercury(II) and methyl mercury determinations in water and fish samples by using solid phase extraction and cold vapour atomic absorption spectrometry combination.

    PubMed

    Tuzen, Mustafa; Karaman, Isa; Citak, Demirhan; Soylak, Mustafa

    2009-07-01

    A method has been developed for mercury(II) and methyl mercury speciation on Staphylococcus aureus loaded Dowex Optipore V-493 micro-column in the presented work, by using cold vapour atomic absorption spectrometry. Selective and sequential elution with 0.1 molL(-1) HCl for methyl mercury and 2 molL(-1) HCl for mercury(II) were performed at the pH range of 2-6. Optimal analytical conditions including pH, amounts of biosorbent, sample volumes were investigated. The detection limits of the analytes were 2.5 ngL(-1) for Hg(II) and 1.7 ngL(-1) for methyl mercury. The capacity of biosorbent for mercury(II) and methyl mercury was 6.5 and 5.4 mgg(-1), respectively. The validation of the presented procedure is performed by the analysis of standard reference material. The speciation procedure established was successfully applied to the speciation of mercury(II) and methyl mercury in natural water and microwave digested fish samples.

  7. Emissions of air-borne mercury from five municipal solid waste landfills in Guiyang and Wuhan, China

    NASA Astrophysics Data System (ADS)

    Li, Z.-G.; Feng, X.; Li, P.; Liang, L.; Tang, S.-L.; Wang, S.-F.; Fu, X.-W.; Qiu, G.-L.; Shang, L.-H.

    2010-04-01

    China disposes of bulk Municipal Solid Waste (MSW) by landfilling, resulting in a large quantity of mercury that enters landfills through waste. A detailed study on atmospheric mercury emissions from MSW landfills in China is necessary to understand mercury behavior from this source. Between 2003 and 2006, mercury airborne emissions through different pathways, as well as mercury speciation in Landfill Gas (LFG) were measured at 5 MSW landfills in Guiyang and Wuhan, China. The results showed that mercury content in the substrate increased the magnitude of mercury emissions, with the highest emission rate measured at the working face and in uncovered waste areas, and the lowest measured near soil covers and vegetated areas. Meteorological parameters, especially solar radiation, influenced the diurnal pattern of mercury surface-air emissions. Total Gaseous Mercury (TGM) in LFG varied from 2.0 to 1406.0 ng m-3, Monomethyl Mercury (MMHg) and Dimethyl Mercury (DMHg) in LFG averaged at 1.93 and 9.21 ng m-3, and accounted for 0.51% and 1.79% of the TGM in the LFG, respectively. Total mercury emitted from the five landfills ranged from 17 to 3300 g yr-1, with the highest from the working face, then soil covering, and finally the vent pipes.

  8. Time-dependent dielectric breakdown measurements of porous organosilicate glass using mercury and solid metal probes

    SciTech Connect

    Pei, Dongfei; Nichols, Michael T.; Shohet, J. Leon; King, Sean W.; Clarke, James S.; Nishi, Yoshio

    2014-09-01

    Time-dependent dielectric breakdown (TDDB) is one of the major concerns for low-k dielectric materials. During plasma processing, low-k dielectrics are subjected to vacuum ultraviolet photon radiation and charged-particle bombardment. To examine the change of TDDB properties, time-to-breakdown measurements are made to porous SiCOH before and after plasma exposure. Significant discrepancies between mercury and solid-metal probes are observed and have been shown to be attributed to mercury diffusion into the dielectric porosities.

  9. Possibilities of mercury removal in the dry flue gas cleaning lines of solid waste incineration units.

    PubMed

    Svoboda, Karel; Hartman, Miloslav; Šyc, Michal; Pohořelý, Michael; Kameníková, Petra; Jeremiáš, Michal; Durda, Tomáš

    2016-01-15

    Dry methods of the flue gas cleaning (for HCl and SO2 removal) are useful particularly in smaller solid waste incineration units. The amount and forms of mercury emissions depend on waste (fuel) composition, content of mercury and chlorine and on the entire process of the flue gas cleaning. In the case of high HCl/total Hg molar ratio in the flue gas, the majority (usually 70-90%) of mercury is present in the form of HgCl2 and a smaller amount in the form of mercury vapors at higher temperatures. Removal of both main forms of mercury from the flue gas is dependent on chemical reactions and sorption processes at the temperatures below approx. 340 °C. Significant part of HgCl2 and a small part of elemental Hg vapors can be adsorbed on fly ash and solid particle in the air pollution control (APC) processes, which are removed in dust filters. Injection of non-impregnated active carbon (AC) or activated lignite coke particles is able to remove mainly the oxidized Hg(2+) compounds. Vapors of metallic Hg(o) are adsorbed relatively weakly. Much better chemisorption of Hg(o) together with higher sorbent capacity is achieved by AC-based sorbents impregnated with sulfur, alkali poly-sulfides, ferric chloride, etc. Inorganic sorbents with the same or similar chemical impregnation are also applicable for deeper Hg(o) removal (over 85%). SCR catalysts convert part of Hg(o) into oxidized compounds (HgO, HgCl2, etc.) contributing to more efficient Hg removal, but excess of NH3 has a negative effect. Both forms, elemental Hg(o) and HgCl2, can be converted into HgS particles by reacting with droplets/aerosol of poly-sulfides solutions/solids in flue gas. Mercury captured in the form of water insoluble HgS is more advantageous in the disposal of solid waste from APC processes. Four selected options of the dry flue gas cleaning with mercury removal are analyzed, assessed and compared (in terms of efficiency of Hg-emission reduction and costs) with wet methods and retrofits for more

  10. Possibilities of mercury removal in the dry flue gas cleaning lines of solid waste incineration units.

    PubMed

    Svoboda, Karel; Hartman, Miloslav; Šyc, Michal; Pohořelý, Michael; Kameníková, Petra; Jeremiáš, Michal; Durda, Tomáš

    2016-01-15

    Dry methods of the flue gas cleaning (for HCl and SO2 removal) are useful particularly in smaller solid waste incineration units. The amount and forms of mercury emissions depend on waste (fuel) composition, content of mercury and chlorine and on the entire process of the flue gas cleaning. In the case of high HCl/total Hg molar ratio in the flue gas, the majority (usually 70-90%) of mercury is present in the form of HgCl2 and a smaller amount in the form of mercury vapors at higher temperatures. Removal of both main forms of mercury from the flue gas is dependent on chemical reactions and sorption processes at the temperatures below approx. 340 °C. Significant part of HgCl2 and a small part of elemental Hg vapors can be adsorbed on fly ash and solid particle in the air pollution control (APC) processes, which are removed in dust filters. Injection of non-impregnated active carbon (AC) or activated lignite coke particles is able to remove mainly the oxidized Hg(2+) compounds. Vapors of metallic Hg(o) are adsorbed relatively weakly. Much better chemisorption of Hg(o) together with higher sorbent capacity is achieved by AC-based sorbents impregnated with sulfur, alkali poly-sulfides, ferric chloride, etc. Inorganic sorbents with the same or similar chemical impregnation are also applicable for deeper Hg(o) removal (over 85%). SCR catalysts convert part of Hg(o) into oxidized compounds (HgO, HgCl2, etc.) contributing to more efficient Hg removal, but excess of NH3 has a negative effect. Both forms, elemental Hg(o) and HgCl2, can be converted into HgS particles by reacting with droplets/aerosol of poly-sulfides solutions/solids in flue gas. Mercury captured in the form of water insoluble HgS is more advantageous in the disposal of solid waste from APC processes. Four selected options of the dry flue gas cleaning with mercury removal are analyzed, assessed and compared (in terms of efficiency of Hg-emission reduction and costs) with wet methods and retrofits for more

  11. Stabilizing agents for calibration in the determination of mercury using solid sampling electrothermal atomic absorption spectrometry.

    PubMed

    Zelinková, Hana; Červenka, Rostislav; Komárek, Josef

    2012-01-01

    Tetramethylene dithiocarbamate (TMDTC), diethyldithiocarbamate (DEDTC), and thiourea were investigated as stabilizing agents for calibration purposes in the determination of mercury using solid sampling electrothermal atomic absorption spectrometry (SS-ETAAS). These agents were used for complexation of mercury in calibration solutions and its thermal stabilization in a solid sampling platform. The calibration solutions had the form of methyl isobutyl ketone (MIBK) extracts or MIBK-methanol solutions with the TMDTC and DEDTC chelates and aqueous solutions with thiourea complexes. The best results were obtained for MIBK-methanol solutions in the presence of 2.5 g L(-1) TMDTC. The surface of graphite platforms for solid sampling was modified with palladium or rhenium by using electrodeposition from a drop of solutions. The Re modifier is preferable due to a higher lifetime of platform coating. A new SS-ETAAS procedure using the direct sampling of solid samples into a platform with an Re modified graphite surface and the calibration against MIBK-methanol solutions in the presence of TMDTC is proposed for the determination of mercury content in solid environmental samples, such as soil and plants.

  12. Mercury Loads in the South River and Simulation of Mercury Total Maximum Daily Loads (TMDLs) for the South River, South Fork Shenandoah River, and Shenandoah River: Shenandoah Valley, Virginia

    USGS Publications Warehouse

    Eggleston, Jack

    2009-01-01

    Due to elevated levels of methylmercury in fish, three streams in the Shenandoah Valley of Virginia have been placed on the State's 303d list of contaminated waters. These streams, the South River, the South Fork Shenandoah River, and parts of the Shenandoah River, are downstream from the city of Waynesboro, where mercury waste was discharged from 1929-1950 at an industrial site. To evaluate mercury contamination in fish, this total maximum daily load (TMDL) study was performed in a cooperative effort between the U.S. Geological Survey, the Virginia Department of Environmental Quality, and the U.S. Environmental Protection Agency. The investigation focused on the South River watershed, a headwater of the South Fork Shenandoah River, and extrapolated findings to the other affected downstream rivers. A numerical model of the watershed, based on Hydrological Simulation Program-FORTRAN (HSPF) software, was developed to simulate flows of water, sediment, and total mercury. Results from the investigation and numerical model indicate that contaminated flood-plain soils along the riverbank are the largest source of mercury to the river. Mercury associated with sediment accounts for 96 percent of the annual downstream mercury load (181 of 189 kilograms per year) at the mouth of the South River. Atmospherically deposited mercury contributes a smaller load (less than 1 percent) as do point sources, including current discharge from the historic industrial source area. In order to determine how reductions of mercury loading to the stream could reduce methylmercury concentrations in fish tissue below the U.S. Environmental Protection Agency criterion of 0.3 milligrams per kilogram, multiple scenarios were simulated. Bioaccumulation of mercury was expressed with a site-specific exponential relation between aqueous total mercury and methylmercury in smallmouth bass, the indicator fish species. Simulations indicate that if mercury loading were to decrease by 98.9 percent from 189

  13. MERCURY REMOVAL FROM DOE SOLID MIXED WASTE USING THE GEMEP(sm) TECHNOLOGY

    SciTech Connect

    1999-03-01

    Under the sponsorship of the Federal Energy Technology Center (FETC), Metcalf and Eddy (M and E), in association with General Electric Corporate Research and Development Center (GE-CRD), Colorado Minerals Research Institute (CMRI), and Oak Ridge National Laboratory (ORNL), conducted laboratory-scale and bench-scale tests of the General Electric Mercury Extraction Process technology on two mercury-contaminated mixed solid wastes from U. S. Department of Energy sites: sediment from the East Fork of Poplar Creek, Oak Ridge (samples supplied by Oak Ridge National Laboratory), and drummed soils from Idaho National Environmental and Engineering Laboratory (INEEL). Fluorescent lamps provided by GE-CRD were also studied. The GEMEP technology, invented and patented by the General Electric Company, uses an extraction solution composed of aqueous potassium iodide plus iodine to remove mercury from soils and other wastes. The extraction solution is regenerated by chemical oxidation and reused, after the solubilized mercury is removed from solution by reducing it to the metallic state. The results of the laboratory- and bench-scale testing conducted for this project included: (1) GEMEP extraction tests to optimize extraction conditions and determine the extent of co-extraction of radionuclides; (2) pre-screening (pre-segregation) tests to determine if initial separation steps could be used effectively to reduce the volume of material needing GEMEP extraction; and (3) demonstration of the complete extraction, mercury recovery, and iodine recovery and regeneration process (known as locked-cycle testing).

  14. High solids loading for water-based tape casting

    NASA Astrophysics Data System (ADS)

    Suwannasiri, Thitima

    Tape Casting is a low cost process for making large-area, thin, flat ceramics, which traditionally utilizes organic solvents to allow fast drying.sp{1-4} However, some of the volatile organic compounds (VOC), such as toluene, methylethyl ketone (MEK), and cyclohexanone, are hazardous air pollutants, and their emissions need to be regulated. Therefore, using water as a solvent is desirable to avoid the need of trapping VOCs. Although water is of low cost, nonflammable and safe to the environment, its heat of vaporization is high, 540 kca/g, compared to that of toluene, 74 kca/g.sp7 This makes the drying slow when water is used. The use of water in a tape casting formulation has previously been practical just for applications which require very thin tape, 100-200 mum. A high solids loading of above 50 vol% is an alternative approach to obtain sufficiently rapid drying for a thicker tape (up to 0.8 mm) since the water content is originally minimized. In order to obtain a high solids loading, the dispersants and binder systems were carefully tailored during the present research project. Low molecular weight polyelectrolytes, such as polyacrylic acid PAA (M.W. 1800) and citric acid, were found to be effective for high solids loading of Alsb2Osb3 (A-16SG), for which the electrosteric stabilization played an important role to the stability of the suspension. The viscosity and flow behavior of the suspension strongly depended on pH and the amount of polyelectrolyte, which could be related to the configuration of the polyelectrolyte molecules on the powder surface. The high solids loading of 64.5 vol% could be obtained for the fine A-16SG powder which had a surface area of 9.3 msp2/g. For the coarser powder, A-152SG, the dilatancy was a major problem that obstructed a further rise in solids loading. The dilatancy could be minimized by modifying the size distribution with A-152SG plus A-16SG and using a proper pH and amount of dispersants. An extremely high solids loading of

  15. Biogeochemical transformations of mercury in solid waste landfills and pathways for release.

    PubMed

    Lee, Sung-Woo; Lowry, Gregory V; Hsu-Kim, Heileen

    2016-02-01

    Mercury (Hg) is present in a variety of solid wastes including industrial wastes, household products, consumer electronics, and medical wastes, some of which can be disposed in conventional landfills. The presence of this neurotoxic metal in landfills is a concern due to the potential for it to leach or volatilize from the landfill and impact local ecosystems. The objective of this review is to describe general practices for the disposal of mercury-bearing solid wastes, summarize previous studies on the release of mercury from landfills, and delineate the expected transformations of Hg within landfill environments that would influence transport of Hg via landfill gas and leachate. A few studies have documented the emissions of Hg as landfill gas, primarily as gaseous elemental Hg(0) and smaller amounts as methylated Hg species. Much less is known regarding the release of Hg in leachate. Landfill conditions are unique from other subsurface environments in that they can contain water with very high conductivity and organic carbon concentration. Landfills also experience large changes in redox potential (and the associated microbial community) that greatly influence Hg speciation, transformations, and mobilization potential. Generally, Hg is not likely to persist in large quantities as dissolved species, since Hg(0) tends to evolve in the gas phase and divalent Hg(ii) sorbs strongly to particulate phases including organic carbon and sulfides. However, Hg(ii) has the potential to associate with or form colloidal particles that can be mobilized in porous media under high organic carbon conditions. Moreover, the anaerobic conditions within landfills can foster the growth of microorganisms that produced monomethyl- and dimethyl-Hg species, the forms of mercury with high potential for bioaccumulation. Much advancement has recently been made in the mercury biogeochemistry research field, and this study seeks to incorporate these findings for landfill settings.

  16. Biogeochemical transformations of mercury in solid waste landfills and pathways for release.

    PubMed

    Lee, Sung-Woo; Lowry, Gregory V; Hsu-Kim, Heileen

    2016-02-01

    Mercury (Hg) is present in a variety of solid wastes including industrial wastes, household products, consumer electronics, and medical wastes, some of which can be disposed in conventional landfills. The presence of this neurotoxic metal in landfills is a concern due to the potential for it to leach or volatilize from the landfill and impact local ecosystems. The objective of this review is to describe general practices for the disposal of mercury-bearing solid wastes, summarize previous studies on the release of mercury from landfills, and delineate the expected transformations of Hg within landfill environments that would influence transport of Hg via landfill gas and leachate. A few studies have documented the emissions of Hg as landfill gas, primarily as gaseous elemental Hg(0) and smaller amounts as methylated Hg species. Much less is known regarding the release of Hg in leachate. Landfill conditions are unique from other subsurface environments in that they can contain water with very high conductivity and organic carbon concentration. Landfills also experience large changes in redox potential (and the associated microbial community) that greatly influence Hg speciation, transformations, and mobilization potential. Generally, Hg is not likely to persist in large quantities as dissolved species, since Hg(0) tends to evolve in the gas phase and divalent Hg(ii) sorbs strongly to particulate phases including organic carbon and sulfides. However, Hg(ii) has the potential to associate with or form colloidal particles that can be mobilized in porous media under high organic carbon conditions. Moreover, the anaerobic conditions within landfills can foster the growth of microorganisms that produced monomethyl- and dimethyl-Hg species, the forms of mercury with high potential for bioaccumulation. Much advancement has recently been made in the mercury biogeochemistry research field, and this study seeks to incorporate these findings for landfill settings. PMID:26745831

  17. Evaluating the potential efficacy of mercury total maximum daily loads on aqueous methylmercury levels in four coastal watersheds.

    PubMed

    Rothenberg, Sarah E; Ambrose, Richard F; Jay, Jennifer A

    2008-08-01

    Of the approximately 780 U.S. EPA approved mercury total maximum daily loads (TMDLs), most specify a reduction in total mercury (Hg(T)) loads to reduce methylmercury levels in fish tissue, assuming a 1:1 correspondence. However, mercury methylation is more complex, and therefore, proposed load reductions may not be adequate. Using multiple regression with microlevel and macrolevel variables, the potential efficacy of mercury TMDLs on decreasing aqueous methylmercury levels was investigated in four coastal watersheds: Mugu Lagoon (CA), San Francisco Bay Estuary, Long Island Sound, and south Florida. Hg(T) and methylmercury levels were positively correlated in all watersheds except in Long Island Sound, where spatial differences explained over 40% of the variability in methylmercury levels. A mercury TMDL would be least effective in Long Island Sound due to spatial heterogeneity but most effective in south Florida, where the ratio between aqueous Hg(T) and methylmercury levels was close to 1 and the 95% confidence interval was narrow, indicating a probable reduction in aqueous methylmercury levels if Hg(T) loads were reduced.

  18. Statistical estimate of mercury removal efficiencies for air pollution control devices of municipal solid waste incinerators.

    PubMed

    Takahashi, Fumitake; Kida, Akiko; Shimaoka, Takayuki

    2010-10-15

    Although representative removal efficiencies of gaseous mercury for air pollution control devices (APCDs) are important to prepare more reliable atmospheric emission inventories of mercury, they have been still uncertain because they depend sensitively on many factors like the type of APCDs, gas temperature, and mercury speciation. In this study, representative removal efficiencies of gaseous mercury for several types of APCDs of municipal solid waste incineration (MSWI) were offered using a statistical method. 534 data of mercury removal efficiencies for APCDs used in MSWI were collected. APCDs were categorized as fixed-bed absorber (FA), wet scrubber (WS), electrostatic precipitator (ESP), and fabric filter (FF), and their hybrid systems. Data series of all APCD types had Gaussian log-normality. The average removal efficiency with a 95% confidence interval for each APCD was estimated. The FA, WS, and FF with carbon and/or dry sorbent injection systems had 75% to 82% average removal efficiencies. On the other hand, the ESP with/without dry sorbent injection had lower removal efficiencies of up to 22%. The type of dry sorbent injection in the FF system, dry or semi-dry, did not make more than 1% difference to the removal efficiency. The injection of activated carbon and carbon-containing fly ash in the FF system made less than 3% difference. Estimation errors of removal efficiency were especially high for the ESP. The national average of removal efficiency of APCDs in Japanese MSWI plants was estimated on the basis of incineration capacity. Owing to the replacement of old APCDs for dioxin control, the national average removal efficiency increased from 34.5% in 1991 to 92.5% in 2003. This resulted in an additional reduction of about 0.86Mg emission in 2003. Further study using the methodology in this study to other important emission sources like coal-fired power plants will contribute to better emission inventories.

  19. Mercury speciation and emission from municipal solid waste incinerators in the Pearl River Delta, South China.

    PubMed

    Chen, Laiguo; Liu, Ming; Fan, Ruifang; Ma, Shexia; Xu, Zhencheng; Ren, Mingzhong; He, Qiusheng

    2013-03-01

    The potential for Hg release during municipal solid waste incineration (MSWI) is attracting increased attention due to high volume of municipal waste being treated by incineration in China. Emission amounts have been estimated using emission factors developed for other countries. To fine tune our emission estimate total mercury (THg) and mercury speciation were measured using isokinetic sampling in eight plants, of which six used grate furnace combustor (GFC) and two circulation fluidized bed combustors (CFBCs). Results showed that average THg concentration (19.5 ± 13.6 μg/Nm) in flue gas at the facilities that used CFBC was significantly lower than that at those using GFC (51.4 ± 28.3 μg/Nm, p=0.002). Gaseous oxidized mercury (GOM), gaseous elemental mercury (GEM, Hg), and particulate mercury (Hg) represented 95.5 ± 3.8%, 4.1 ± 3.9% and 0.4 ± 0.3% in GFC, and 63.8 ± 8.6%, 33.6 ± 10.5% and 2.6 ± 1.9% in CFBC, respectively. The measured average THg emission factor for the 8 MSWI plants was 208 ± 130 mg/t in the Pearl River Delta (PRD) region, with 217 ± 158 mg/t and 188 ± 17.7 mg/t were from GFC and CFBC, respectively. Using the average emission factor the estimated total mercury emissions from MSWI were 4.67 ± 2.91 t in China, and 770 ± 65.5 kg in the PRD region in 2010. Of these, 4240 ± 210 kg, 408 ± 231 kg and 14.8 ± 14.1 kg, and 688 ± 37 kg, 78.9 ± 40.6 kg and 3.2 ± 3.0 kg were GOM, Hg, and Hg, respectively. Mercury emissions will continue to increase as the amounts of MSW being incinerated increases. PMID:23410861

  20. Calculating mercury loading to the tidal Hudson River, New York, using rating curve and surrogate methodologies

    USGS Publications Warehouse

    Wall, G.R.; Ingleston, H.H.; Litten, S.

    2005-01-01

    Total mercury (THg) load in rivers is often calculated from a site-specific "rating-curve" based on the relation between THg concentration and river discharge along with a continuous record of river discharge. However, there is no physical explanation as to why river discharge should consistently predict THg or any other suspended analyte. THg loads calculated by the rating-curve method were compared with those calculated by a "continuous surrogate concentration" (CSC) method in which a relation between THg concentration and suspended-sediment concentration (SSC) is constructed; THg loads then can be calculated from the continuous record of SSC and river discharge. The rating-curve and CSC methods, respectively, indicated annual THg loads of 46.4 and 75.1 kg for the Mohawk River, and 52.9 and 33.1 kg for the upper Hudson River. Differences between the results of the two methods are attributed to the inability of the rating-curve method to adequately characterize atypical high flows such as an ice-dam release, or to account for hysteresis, which typically degrades the strength of the relation between stream discharge and concentration of material in suspension. ?? Springer 2005.

  1. Macro-loading Effects in Inductively Coupled Plasma Etched Mercury Cadmium Telluride

    NASA Astrophysics Data System (ADS)

    Apte, Palash; Rybnicek, Kimon; Stoltz, Andrew

    2016-09-01

    This paper reports the effect of macro-loading on mercury cadmium telluride (Hg1- x Cd x Te) and Photoresist (PR) etched in an inductively coupled plasma (ICP). A significant macro-loading effect is observed, which affects the etch rates of both PR and Hg1- x Cd x Te. It is observed that the exposed silicon area has a significant effect on the PR etch rate, but not on the Hg1- x Cd x Te etch rate. It is also observed that the exposed Hg1- x Cd x Te area has a significant effect on the etch rate of the PR, but the exposed PR area does not seem to have an effect on the Hg1- x Cd x Te etch rate. Further, the exposed Hg1- x Cd x Te area is shown to affect the etch rate of the Hg1- x Cd x Te, but there does not seem to be a similar effect for the exposed PR area on the etch rate of the PR. Since the macro-loading affects the selectivity significantly, this effect can cause significant problems in the etching of deep trenches. A few techniques to reduce the effect of macro-loading on the etch rates of the PR and Hg1- x Cd x Te are listed, herein.

  2. Mercury

    NASA Technical Reports Server (NTRS)

    Gault, D. E.; Burns, J. A.; Cassen, P.; Strom, R. G.

    1977-01-01

    Prior to the flight of the Mariner 10 spacecraft, Mercury was the least investigated and most poorly known terrestrial planet (Kuiper 1970, Devine 1972). Observational difficulties caused by its proximity to the Sun as viewed from Earth caused the planet to remain a small, vague disk exhibiting little surface contrast or details, an object for which only three major facts were known: 1. its bulk density is similar to that of Venus and Earth, much greater than that of Mars and the Moon; 2. its surface reflects electromagnetic radiation at all wavelengths in the same manner as the Moon (taking into account differences in their solar distances); and 3. its rotation period is in 2/3 resonance with its orbital period. Images obtained during the flyby by Mariner 10 on 29 March 1974 (and the two subsequent flybys on 21 September 1974 and 16 March 1975) revealed Mercury's surface in detail equivalent to that available for the Moon during the early 1960's from Earth-based telescopic views. Additionally, however, information was obtained on the planet's mass and size, atmospheric composition and density, charged-particle environment, and infrared thermal radiation from the surface, and most significantly of all, the existence of a planetary magnetic field that is probably intrinsic to Mercury was established. In the following, this new information is summarized together with results from theoretical studies and ground-based observations. In the quantum jumps of knowledge that have been characteristic of "space-age" exploration, the previously obscure body of Mercury has suddenly come into sharp focus. It is very likely a differentiated body, probably contains a large Earth-like iron-rich core, and displays a surface remarkably similar to that of the Moon, which suggests a similar evolutionary history.

  3. Implications of Dynamic Loading and Changing Climate on Mercury Bioaccumulation in a Planktivorous Fish (Orthodon microlepidotus)

    NASA Astrophysics Data System (ADS)

    Carroll, R. W. H.; Flickinger, A.; Warwick, J. J.; Schumer, R.

    2015-12-01

    A bioenergetic and mercury (Hg) mass balance (BioHg) model is developed for the Sacramento blackfish (Orthodon microlepidotus), a filter feeding cyprinid found in northern California and Nevada. Attention focuses on the Lahontan Reservoir in northern Nevada, which receives a strong temporally varying load of dissolved methylmercury (DMeHg) from the Carson River. Hg loads are the result of contaminated bank erosion during high flows and diffusion from bottom sediments during low flows. Coupling of dynamic reservoir loading with periods of maximum plankton growth and maximum fish consumption rates are required to explain the largest body burdens observed in the planktivore. In contrast, the large body burdens cannot be achieved using average water column concentrations. The United States Bureau of Reclamation has produced future streamflow estimates for 2000-2099 using 112 CMIP3 climate projections and the Variable Infiltration Capacity (VIC) model. These are used to drive a fully dynamic Hg transport model to assess changes in contaminant loading to the reservoir and implications on planktivorous bioaccumulation. Model results suggest the future loads of DMeHg entering the Lahontan Reservoir will decrease most significantly in the spring and summer due to channel width increases and depth decreases in the Carson River which reduce bank erosion over the century. The modeled concentrations of DMeHg in the reservoir are expected to increase during the summer due to a decrease in reservoir volume affecting the concentrations more than the decrease in loads, and the model results show that bioaccumulation levels may increase in the upstream sections of the reservoir while maintaining contamination levels above the federal action limit for human consumption in the lower reservoir.

  4. Removal of mercury from solids using the potassium iodide/iodine leaching process

    SciTech Connect

    Klasson, K.T.; Koran, L.J. Jr.; Gates, D.D.; Cameron, P.A.

    1997-12-01

    Potassium iodide (KI) and iodine (I{sub 2}) leaching solutions have been evaluated for use in a process for removing mercury from contaminated mixed waste solids. Most of the experimental work was completed using surrogate waste. During the last quarter of fiscal year 1995, this process was evaluated using an actual mixed waste (storm sewer sediment from the Oak Ridge Y-12 Site). The mercury content of the storm sewer sediment was measured and determined to be approximately 35,000 mg/kg. A solution consisting of 0.2 M I{sub 2} and 0.4 M KI proved to be the most effective leachant used in the experiments when applied for 2 to 4 h at ambient temperature. Over 98% of the mercury was removed from the storm sewer sediment using this solution. Iodine recovery and recycle of the leaching agent were also accomplished successfully. Mathematical model was used to predict the amount of secondary waste in the process. Both surrogate waste and actual waste were used to study the fate of radionuclides (uranium) in the leaching process.

  5. Solid Rocket Booster Hydraulic Pump Port Cap Joint Load Testing

    NASA Technical Reports Server (NTRS)

    Gamwell, W. R.; Murphy, N. C.

    2004-01-01

    The solid rocket booster uses hydraulic pumps fabricated from cast C355 aluminum alloy, with 17-4 PH stainless steel pump port caps. Corrosion-resistant steel, MS51830 CA204L self-locking screw thread inserts are installed into C355 pump housings, with A286 stainless steel fasteners installed into the insert to secure the pump port cap to the housing. In the past, pump port cap fasteners were installed to a torque of 33 Nm (300 in-lb). However, the structural analyses used a significantly higher nut factor than indicated during tests conducted by Boeing Space Systems. When the torque values were reassessed using Boeing's nut factor, the fastener preload had a factor of safety of less than 1, with potential for overloading the joint. This paper describes how behavior was determined for a preloaded joint with a steel bolt threaded into steel inserts in aluminum parts. Finite element models were compared with test results. For all initial bolt preloads, bolt loads increased as external applied loads increased. For higher initial bolt preloads, less load was transferred into the bolt, due to external applied loading. Lower torque limits were established for pump port cap fasteners and additional limits were placed on insert axial deformation under operating conditions after seating the insert with an initial preload.

  6. Tributary loading of mercury to Lake Michigan: Importance of seasonal events and phase partitioning

    USGS Publications Warehouse

    Hurley, J.P.; Cowell, S.E.; Shafer, M.M.; Hughes, P.E.

    1998-01-01

    As a component of a lakewide mass balance study for Lake Michigan, we measured total mercury (Hg(T)) concentrations and fluxes in 11 selected tributaries. Unfiltered Hg(T) concentrations ranged from 0.56 ng l-61 at the Pete Marquette River to 182 ng l-1 at the Fox River. Highest mean Hg(T) concentrations were observed in the Fox R., Indiana Harbor Ship Canal, Grand R. and the Kalamazoo R. Mean particulate matter Hg(T) content ranged from about 0.1 to 1.5 ??g g-1, with highest levels from the industrialized basins of the Indiana Harbor and Fox River. Highest tributary loading rates (g day-1) were observed from the Fox, Grand, Kalamazoo and St. Joseph Rivers. Increased loading rates during spring melt and summer/fall storm events in these tributaries were generally associated with particulate loading from either sediment resuspension or erosional processes. In contrast, filtered Hg(T) represented 80% of the Hg(T) flux in the Manistique R., whose watershed is comprised almost entirely of wetlands and forest.

  7. Comparison of mercury mass loading in streams to atmospheric deposition in watersheds of Western North America: Evidence for non-atmospheric mercury sources.

    PubMed

    Domagalski, Joseph; Majewski, Michael S; Alpers, Charles N; Eckley, Chris S; Eagles-Smith, Collin A; Schenk, Liam; Wherry, Susan

    2016-10-15

    Annual stream loads of mercury (Hg) and inputs of wet and dry atmospheric Hg deposition to the landscape were investigated in watersheds of the Western United States and the Canadian-Alaskan Arctic. Mercury concentration and discharge data from flow gauging stations were used to compute annual mass loads with regression models. Measured wet and modeled dry deposition were compared to annual stream loads to compute ratios of Hg stream load to total Hg atmospheric deposition. Watershed land uses or cover included mining, undeveloped, urbanized, and mixed. Of 27 watersheds that were investigated, 15 had some degree of mining, either of Hg or precious metals (gold or silver), where Hg was used in the amalgamation process. Stream loads in excess of annual Hg atmospheric deposition (ratio>1) were observed in watersheds containing Hg mines and in relatively small and medium-sized watersheds with gold or silver mines, however, larger watersheds containing gold or silver mines, some of which also contain large dams that trap sediment, were sometimes associated with lower load ratios (<0.2). In the non-Arctic regions, watersheds with natural vegetation tended to have low ratios of stream load to Hg deposition (<0.1), whereas urbanized areas had higher ratios (0.34-1.0) because of impervious surfaces. This indicated that, in ecosystems with natural vegetation, Hg is retained in the soil and may be transported subsequently to streams as a result of erosion or in association with dissolved organic carbon. Arctic watersheds (Mackenzie and Yukon Rivers) had a relatively elevated ratio of stream load to atmospheric deposition (0.27 and 0.74), possibly because of melting glaciers or permafrost releasing previously stored Hg to the streams. Overall, our research highlights the important role of watershed characteristics in determining whether a landscape is a net source of Hg or a net sink of atmospheric Hg. PMID:27015962

  8. Comparison of mercury mass loading in streams to atmospheric deposition in watersheds of Western North America: Evidence for non-atmospheric mercury sources.

    PubMed

    Domagalski, Joseph; Majewski, Michael S; Alpers, Charles N; Eckley, Chris S; Eagles-Smith, Collin A; Schenk, Liam; Wherry, Susan

    2016-10-15

    Annual stream loads of mercury (Hg) and inputs of wet and dry atmospheric Hg deposition to the landscape were investigated in watersheds of the Western United States and the Canadian-Alaskan Arctic. Mercury concentration and discharge data from flow gauging stations were used to compute annual mass loads with regression models. Measured wet and modeled dry deposition were compared to annual stream loads to compute ratios of Hg stream load to total Hg atmospheric deposition. Watershed land uses or cover included mining, undeveloped, urbanized, and mixed. Of 27 watersheds that were investigated, 15 had some degree of mining, either of Hg or precious metals (gold or silver), where Hg was used in the amalgamation process. Stream loads in excess of annual Hg atmospheric deposition (ratio>1) were observed in watersheds containing Hg mines and in relatively small and medium-sized watersheds with gold or silver mines, however, larger watersheds containing gold or silver mines, some of which also contain large dams that trap sediment, were sometimes associated with lower load ratios (<0.2). In the non-Arctic regions, watersheds with natural vegetation tended to have low ratios of stream load to Hg deposition (<0.1), whereas urbanized areas had higher ratios (0.34-1.0) because of impervious surfaces. This indicated that, in ecosystems with natural vegetation, Hg is retained in the soil and may be transported subsequently to streams as a result of erosion or in association with dissolved organic carbon. Arctic watersheds (Mackenzie and Yukon Rivers) had a relatively elevated ratio of stream load to atmospheric deposition (0.27 and 0.74), possibly because of melting glaciers or permafrost releasing previously stored Hg to the streams. Overall, our research highlights the important role of watershed characteristics in determining whether a landscape is a net source of Hg or a net sink of atmospheric Hg.

  9. Modeling Watershed Mercury Response to Atmospheric Loadings: Response Time and Challenges

    EPA Science Inventory

    The relationship between sources of mercury to watersheds and its fate in surface waters is invariably complex. Large scale monitoring studies, such as the METAALICUS project, have advanced current understanding of the links between atmospheric deposition of mercury and accumulat...

  10. Nonlinear wave propagation in constrained solids subjected to thermal loads

    NASA Astrophysics Data System (ADS)

    Nucera, Claudio; Lanza di Scalea, Francesco

    2014-01-01

    The classical mathematical treatment governing nonlinear wave propagation in solids relies on finite strain theory. In this scenario, a system of nonlinear partial differential equations can be derived to mathematically describe nonlinear phenomena such as acoustoelasticity (wave speed dependency on quasi-static stress), wave interaction, wave distortion, and higher-harmonic generation. The present work expands the topic of nonlinear wave propagation to the case of a constrained solid subjected to thermal loads. The origin of nonlinear effects in this case is explained on the basis of the anharmonicity of interatomic potentials, and the absorption of the potential energy corresponding to the (prevented) thermal expansion. Such "residual" energy is, at least, cubic as a function of strain, hence leading to a nonlinear wave equation and higher-harmonic generation. Closed-form solutions are given for the longitudinal wave speed and the second-harmonic nonlinear parameter as a function of interatomic potential parameters and temperature increase. The model predicts a decrease in longitudinal wave speed and a corresponding increase in nonlinear parameter with increasing temperature, as a result of the thermal stresses caused by the prevented thermal expansion of the solid. Experimental measurements of the ultrasonic nonlinear parameter on a steel block under constrained thermal expansion confirm this trend. These results suggest the potential of a nonlinear ultrasonic measurement to quantify thermal stresses from prevented thermal expansion. This knowledge can be extremely useful to prevent thermal buckling of various structures, such as continuous-welded rails in hot weather.

  11. DIRECT MERCURY ANALYSIS IN ENVIRONMENTAL SOLIDS BY ICPMS WITH ON-LINE SAMPLE ASHING AND MERCURY PRE-CONCENTRATION USING THE DIRECT MERCURY ANALYZER

    EPA Science Inventory



    A Direct Mercury Analyzer based on sample combustion and mercury concentration by gold amalgamation, followed by atomic absorption determination, was interfaced with a quadrupole and a magnet sector ICPMS. In this paper, we discuss design and operating parameters and eval...

  12. Comparison of Mercury Mass Loading in Streams to Wet and Dry Atmospheric Deposition in Watersheds of the Western US: Evidence for Non-Atmospheric Mercury Sources

    NASA Astrophysics Data System (ADS)

    Domagalski, J. L.; Majewski, M. S.; Alpers, C. N.; Eckley, C.

    2015-12-01

    Many streams in the western United States (US) are listed as impaired by mercury (Hg), and it is important to understand the magnitudes of the various sources in order to implement management strategies. Atmospheric deposition of Hg and can be a major source of aquatic contamination, along with mine wastes, and other sources. Prior studies in the eastern US have shown that streams deliver less than 50% of the atmospherically deposited Hg on an annual basis. In this study, we compared annual stream Hg loads for 20 watersheds in the western US to measured wet and modeled dry deposition. Land use varies from undisturbed to mixed (agricultural, urban, forested, mining). Data from the Mercury Deposition Network was used to estimate Hg input from precipitation. Dry deposition was not directly measured, but can be modeled using the Community Multi-scale Air Quality model. At an undeveloped watershed in the Rocky Mountains, the ratio of stream Hg load to atmospheric deposition was 0.2 during a year of average precipitation. In contrast, at the Carson River in Nevada, with known Hg contamination from historical silver mining with Hg amalgamation, stream export exceeded atmospheric deposition by a factor of 60, and at a small Sierran watershed with gold mining, the ratio was 70. Larger watersheds with mixed land uses, tend to have lower ratios of stream export relative to atmospheric deposition suggesting storage of Hg. The Sacramento River was the largest watershed for which Hg riverine loads were available with an average ratio of stream Hg export to atmospheric deposition of 0.10. Although Hg was used in upstream historical mining operations, the downstream river Hg load is partially mitigated by reservoirs, which trap sediment. This study represents the first compilation of riverine Hg loads in comparison to atmospheric deposition on a regional scale; the approach may be useful in assessing the relative importance of atmospheric and non-atmospheric Hg sources.

  13. Concentrations and estimated loads of nutrients, mercury, and polychlorinated biphenyls in selected tributaries to Lake Michigan, 2005-6

    USGS Publications Warehouse

    Westenbroek, Stephen M.

    2010-01-01

    The Lake Michigan Mass Balance Project (LMMBP) measured and modeled the concentrations of environmentally persistent contaminants in air, river and lake water, sediment, and fish and bird tissues in and around Lake Michigan for an 18-month period spanning 1994-95. Tributary loads were calculated as part of the LMMBP. The work described in this report was designed to provide updated concentration data and load estimates for 5 nutrients, total mercury, and total polychlorinated biphenyl (PCB) at 5 of the original 11 LMMBP sampling sites. Samples were collected at five Lake Michigan tributary monitoring sites during 2005 and 2006. Annual loads calculated for the 2005-6 sampling period are as much as 50 percent lower relative to the 1994-95 time period. Differences between the loads calculated for the two time periods are likely related to a combination of (1) biases introduced by a reduced level of sampling effort, (2) differences in hydrological characteristics, and (3) actual environmental change. Estimated annual total mercury loads during 2005-6 ranged from 51 kilograms per year (kg/yr) in the Fox River to 2.2 kg/yr in the Indiana Harbor and Ship Canal. Estimated annual total PCB loads during 2005-6 ranged from 132 kg/yr in the Fox River to 6.2 kg/yr in the Grand River.

  14. Heat Loads at High Temperature Protection Diodes for a Mercury Mission

    NASA Astrophysics Data System (ADS)

    Reul, S.; Zimmermann, W.; Strobl, G. F. X.; La Roche, G.; Baur, C.

    2008-09-01

    In the frame of the BepiColombo project (see Fig. 1) the solar generators have to withstand the environment near Mercury. Thus all components must withstand an solar irradiation of 10 solar constants or 13.67 kW/m2;. Due to manoeuvres it can happen, that e.g. solar cells will be shadowed or all cell interconnections can fail. To prevent the solar cells from operating in reverse a high temperature protection shunt diode is foreseen for each GaInP/GaInAs/Ge solar cell. This paper reports about first computations of the temperature distributions for different load cases with useful assumptions for the generator structure, sizes/shapes, etc. Also the main temperature influencing parameter and some useful consequences for a high temperature design of a solar generator and Si-diodes will be discussed. The work is part of the ESA contract 19739/06/NL/JD. The Si-diode layout is proposed by AZUR SPACE solar power, Heilbronn.

  15. Economic impact of total solids loading on enzymatic hydrolysis of dilute acid pretreated corn stover.

    PubMed

    Humbird, David; Mohagheghi, Ali; Dowe, Nancy; Schell, Daniel J

    2010-01-01

    In process integration studies of the biomass-to-ethanol conversion process, it is necessary to understand how cellulose conversion yields vary as a function of solids and enzyme loading and other key operating variables. The impact of solids loading on enzymatic cellulose hydrolysis of dilute acid pretreated corn stover slurry was determined using an experimental response surface design methodology. From the experimental work, an empirical correlation was obtained that expresses monomeric glucose yield from enzymatic cellulose hydrolysis as a function of solids loading, enzyme loading, and temperature. This correlation was used in a technoeconomic model to study the impact of solids loading on ethanol production economics. The empirical correlation was used to provide a more realistic assessment of process cost by accounting for changes in cellulose conversion yields at different solids and enzyme loadings as well as enzyme cost. As long as enzymatic cellulose conversion drops off at higher total solids loading (due to end-product inhibition or other factors), there is an optimum value for the total solids loading that minimizes the ethanol production cost. The optimum total solids loading shifts to higher values as enzyme cost decreases.

  16. Protocol to Reconstruct Historical Contaminant Loading to Large Lakes: The Lake Michigan Sediment Record of Mercury

    EPA Science Inventory

    Samples of opportunity from Pb-210 dated sediment cores collected from Lake Michigan between 1994 and 1996 were analyzed for mercury. The storage of both anthropogenic and total (post-1850) mercury in the lake was calculated to be 186 and 228 metric tons, respectively. By setti...

  17. Crack instability of ferroelectric solids under alternative electric loading

    NASA Astrophysics Data System (ADS)

    Chen, Hao-Sen; Wang, He-Ling; Pei, Yong-Mao; Wei, Yu-Jie; Liu, Bin; Fang, Dai-Ning

    2015-08-01

    The low fracture toughness of the widely used piezoelectric and ferroelectric materials in technological applications raises a big concern about their durability and safety. Up to now, the mechanisms of electric-field induced fatigue crack growth in those materials are not fully understood. Here we report experimental observations that alternative electric loading at high frequency or large amplitude gives rise to dramatic temperature rise at the crack tip of a ferroelectric solid. The temperature rise subsequently lowers the energy barrier of materials for domain switch in the vicinity of the crack tip, increases the stress intensity factor and leads to unstable crack propagation finally. In contrast, at low frequency or small amplitude, crack tip temperature increases mildly and saturates quickly, no crack growth is observed. Together with our theoretical analysis on the non-linear heat transfer at the crack tip, we constructed a safe operating area curve with respect to the frequency and amplitude of the electric field, and validated the safety map by experiments. The revealed mechanisms about how electro-thermal-mechanical coupling influences fracture can be directly used to guide the design and safety assessment of piezoelectric and ferroelectric devices.

  18. Methylation and Release of Mercury From the Solid Phase. What Comes First?

    NASA Astrophysics Data System (ADS)

    Regnell, O.

    2004-05-01

    It is a well-known fact that methylation leads to a dramatic increase in the bioavailability of mercury (Hg). All recent observations support the notion that Hg methylation is almost exclusively an anaerobic process. According to the reigning paradigm, methylation of Hg takes place in the cytoplasm of anaerobic bacteria, notably sulfate-reducing bacteria. It is believed that certain forms of inorganic divalent Hg (Hg(II)), can readily diffuse across the cell membrane. In addition, a recent study suggested that active uptake may occur when Hg is bound to low weight organic molecules. In the cytoplasm, cobalamin-dependent biochemical pathways, designed to methylate substrates other than Hg(II), are held responsible for the methylation of Hg(II). However, recent results from studies in a Swedish wetland (within the project "Svartsjoprojektet", aiming at understanding Hg dynamics in a Hg-polluted river-lake system) have led us to question whether Hg methylation does occur exclusively within cells. A provocative interpretation of our results is that methylation preceded the release of Hg from the solid phase, e.g. that Hg(II) sorbed to solid surfaces was methylated and subsequently released as methyl Hg to the sulfidic water. I will discuss this possibility in light of existing evidence that Hg methylation is an intra cellular process.

  19. Watershed and discharge influences on the phase distribution and tributary loading of total mercury and methylmercury into Lake Superior.

    PubMed

    Babiarz, Christopher; Hoffmann, Stephen; Wieben, Ann; Hurley, James; Andren, Anders; Shafer, Martin; Armstrong, David

    2012-02-01

    Knowledge of the partitioning and sources of mercury are important to understanding the human impact on mercury levels in Lake Superior wildlife. Fluvial fluxes of total mercury (Hg(T)) and methylmercury (MeHg) were compared to discharge and partitioning trends in 20 sub-basins having contrasting land uses and geological substrates. The annual tributary yield was correlated with watershed characteristics and scaled up to estimate the basin-wide loading. Tributaries with clay sediments and agricultural land use had the largest daily yields with maxima observed near the peak in water discharge. Roughly 42% of Hg(T) and 57% of MeHg was delivered in the colloidal phase. Tributary inputs, which are confined to near-shore zones of the lake, may be more important to the food-web than atmospheric sources. The annual basin-wide loading from tributaries was estimated to be 277 kg yr(-1) Hg(T) and 3.4 kg yr(-1) MeHg (5.5 and 0.07 mg km(-2) d(-1), respectively).

  20. Quantifying Nutrient and Mercury Concentrations and Loads in Lake Tahoe Snowpack

    NASA Astrophysics Data System (ADS)

    Pearson, C.; Obrist, D.; Schumer, R.

    2012-12-01

    Recent climate models predict a large decrease in Sierra Nevada snowpack over the next fifty years as a result of climate change. This decrease will not only affect the hydrologic balance but also change inputs of nutrients and pollutants through atmospheric deposition. In the Lake Tahoe basin, winter precipitation dominates and snowfall provides approximately 70 percent of the annual water input. From the first snowfall until the end of melting, snowpack acts as a temporary storage for atmospheric deposition that accumulates throughout winter and spring. Through melt and runoff processes, these nutrients and pollutants can enter the aquatic ecosystem where they can have detrimental effects on lake clarity and health. Most previous studies in this basin have focused on direct atmospheric deposition loads to the lake surface, and little temporal and spatial information is available on the dynamics of atmospheric deposition in the basin's snowpack. We here present nitrogen (N), phosphorus (P), and mercury (Hg) concentrations and pool sizes in snowpack along two elevational transects in the Tahoe Basin from January to April of 2012. Total N and P concentrations in the snowpack ranged from 0.07 mg/L to 0.38 mg/L and 0.003 mg/L to 0.109 mg/L, respectively. P concentrations showed strong increases from the west-side to the east-side of the basin which we attribute to local (e.g., urban or road-dust), in-basin sources that are distributed along the dominant west-wind patterns. N species, on the other hand, generally showed little spatial trends, indicating that its sources were more diffuse and possibly from out-of- basin. Hg concentrations ranged from 0.81 ppt to 6.25 ppt and showed similar spatial patterns as N. Hg, however, also showed significant snowpack concentration decreases during storm-free periods which we attribute to gaseous losses of Hg back to the atmosphere from photochemical reduction. These emissions are further supported by lower Hg concentrations in

  1. DIRECT MERCURY ANALYSIS IN ENVIRONMENTAL SOLIDS BY ICPMS WITH ON-LINE SAMPLE ASHING AND MERCURY PRECONCENTRATION USING A DIRECT MERCURY ANALYZER

    EPA Science Inventory

    Mercury is a persistent, mobile, and highly toxic pollutant. It's biogeochemistry is probably the most complex of any metal. For these reasons, the U.S. Environmental Protection Agency (EPA), through its Office of Research and Development (ORD), has developed a comprehensive res...

  2. A MODELLING FRAMEWORK FOR MERCURY CYCLING IN LAKE MICHIGAN

    EPA Science Inventory

    A time dependent mercury model was developed to describe mercury cycling in Lake Michigan. The model addresses dynamic relationships between net mercury loadings and the resulting concentrations of mercury species in the water and sediment. The transformations among three mercury...

  3. Physicochemical characterization and in vivo evaluation of flurbiprofen-loaded solid dispersion without crystalline change.

    PubMed

    Oh, Dong Hoon; Park, Young-Joon; Kang, Jun Heok; Yong, Chul Soon; Choi, Han-Gon

    2011-01-01

    To develop a novel flurbiprofen-loaded solid dispersion without crystalline change, various flurbiprofen-loaded solid dispersions were prepared with water, sodium carboxylmethyl cellulose (Na-CMC), and Tween 80. The effect of Na-CMC and Tween 80 on aqueous solubility of flurbiprofen was investigated. The physicochemical properties of solid dispersions were investigated using SEM, DSC, and X-ray diffraction. The dissolution and bioavailability in rats were evaluated compared to commercial product. Unlike conventional solid dispersion systems, the flurbiprofen-loaded solid dispersion gave a relatively rough surface and changed no crystalline form of drug. These solid dispersions were formed by attaching hydrophilic carriers to the surface of drug without crystal change, resulting in changing the hydrophobic drug to hydrophilic form. Furthermore, the flurbiprofen-loaded solid dispersion at the weight ratio of flurbiprofen/Na-CMC/Tween 80 of 6/2.5/0.5 improved ~60-fold drug solubility. It gave higher AUC, T(max), and C(max) compared to commercial product. The solid dispersion improved almost 1.5-fold bioavailability of drug compared to commercial product in rats. Thus, the flurbiprofen-loaded solid dispersion would be useful to deliver poorly water-soluble flurbiprofen with enhanced bioavailability without crystalline change.

  4. Mercury emissions from municipal solid waste combustors. An assessment of the current situation in the United States and forecast of future emissions

    SciTech Connect

    1993-05-01

    This report examines emissions of mercury (Hg) from municipal solid waste (MSW) combustion in the United States (US). It is projected that total annual nationwide MSW combustor emissions of mercury could decrease from about 97 tonnes (1989 baseline uncontrolled emissions) to less than about 4 tonnes in the year 2000. This represents approximately a 95 percent reduction in the amount of mercury emitted from combusted MSW compared to the 1989 mercury emissions baseline. The likelihood that routinely achievable mercury emissions removal efficiencies of about 80 percent or more can be assured; it is estimated that MSW combustors in the US could prove to be a comparatively minor source of mercury emissions after about 1995. This forecast assumes that diligent measures to control mercury emissions, such as via use of supplemental control technologies (e.g., carbon adsorption), are generally employed at that time. However, no present consensus was found that such emissions control measures can be implemented industry-wide in the US within this time frame. Although the availability of technology is apparently not a limiting factor, practical implementation of necessary control technology may be limited by administrative constraints and other considerations (e.g., planning, budgeting, regulatory compliance requirements, etc.). These projections assume that: (a) about 80 percent mercury emissions reduction control efficiency is achieved with air pollution control equipment likely to be employed by that time; (b) most cylinder-shaped mercury-zinc (CSMZ) batteries used in hospital applications can be prevented from being disposed into the MSW stream or are replaced with alternative batteries that do not contain mercury; and (c) either the amount of mercury used in fluorescent lamps is decreased to an industry-wide average of about 27 milligrams of mercury per lamp or extensive diversion from the MSW stream of fluorescent lamps that contain mercury is accomplished.

  5. Solid-phase extraction and spectrophotometric determination of mercury with 6-mercaptopurine in environmental samples.

    PubMed

    Saber-Tehrani, Mohammad; Hashemi-Moghaddam, Hamid; Husain, S Waqif; Zare, Karim

    2007-08-01

    A highly selective, sensitive and rapid method for the determination of trace amounts of inorganic mercury based on the reaction of Hg (II) with 6-mercaptopurine and the solid phase extraction of the complex on C18 membrane disks was developed. The 6-mercaptopurine selectively reacts with Hg (II) to form a complex in the pH range of 5-8. This complex was preconcentrated by solid phase extraction with C18 disks. An enrichment factor of 100 was achieved. The molar absorptivity of the complex is 0.26 x 10(-6) L. mol(-1) cm(-1) measured at 315 nm. The Beer's law is obeyed in the concentration range of 0.002-0.048 microg mL(-1). The relative standard deviation for eleven-replicated measurement of 0.04 microg mL(-1) is 1.5 %. The detection limit is 0.001 microg mL(-1) in the water samples. The advantage of the method is that the determination of Hg (II) is free from interference of almost all the cations and anions found in environment and wastewater samples. The determination of Hg (II) in water samples of different origins and marine sediment were carried out by the present method and cold vapor atomic absorption spectrometry (CVAAS). Also the method's accuracy was investigated by using SRM 2709. The obtained results by the present procedure were in good agreement with those of the CVAAS and certified value, so that the applicability of the proposed method was confirmed for the real samples.

  6. Mercury Adsorption and Oxidation over Cobalt Oxide Loaded Magnetospheres Catalyst from Fly Ash in Oxyfuel Combustion Flue Gas.

    PubMed

    Yang, Jianping; Zhao, Yongchun; Chang, Lin; Zhang, Junying; Zheng, Chuguang

    2015-07-01

    Cobalt oxide loaded magnetospheres catalyst from fly ash (Co-MF catalyst) showed good mercury removal capacity and recyclability under air combustion flue gas in our previous study. In this work, the Hg(0) removal behaviors as well as the involved reactions mechanism were investigated in oxyfuel combustion conditions. Further, the recyclability of Co-MF catalyst in oxyfuel combustion atmosphere was also evaluated. The results showed that the Hg(0) removal efficiency in oxyfuel combustion conditions was relative high compared to that in air combustion conditions. The presence of enriched CO2 (70%) in oxyfuel combustion atmosphere assisted the mercury oxidation due to the oxidation of function group of C-O formed from CO2. Under both atmospheres, the mercury removal efficiency decreased with the addition of SO2, NO, and H2O. However, the enriched CO2 in oxyfuel combustion atmosphere could somewhat weaken the inhibition of SO2, NO, and H2O. The multiple capture-regeneration cycles demonstrated that the Co-MF catalyst also present good regeneration performance in oxyfuel combustion atmosphere.

  7. Mercury Adsorption and Oxidation over Cobalt Oxide Loaded Magnetospheres Catalyst from Fly Ash in Oxyfuel Combustion Flue Gas.

    PubMed

    Yang, Jianping; Zhao, Yongchun; Chang, Lin; Zhang, Junying; Zheng, Chuguang

    2015-07-01

    Cobalt oxide loaded magnetospheres catalyst from fly ash (Co-MF catalyst) showed good mercury removal capacity and recyclability under air combustion flue gas in our previous study. In this work, the Hg(0) removal behaviors as well as the involved reactions mechanism were investigated in oxyfuel combustion conditions. Further, the recyclability of Co-MF catalyst in oxyfuel combustion atmosphere was also evaluated. The results showed that the Hg(0) removal efficiency in oxyfuel combustion conditions was relative high compared to that in air combustion conditions. The presence of enriched CO2 (70%) in oxyfuel combustion atmosphere assisted the mercury oxidation due to the oxidation of function group of C-O formed from CO2. Under both atmospheres, the mercury removal efficiency decreased with the addition of SO2, NO, and H2O. However, the enriched CO2 in oxyfuel combustion atmosphere could somewhat weaken the inhibition of SO2, NO, and H2O. The multiple capture-regeneration cycles demonstrated that the Co-MF catalyst also present good regeneration performance in oxyfuel combustion atmosphere. PMID:26024429

  8. Dynamic versus static ultrasonic sample treatment for the solid-liquid pre-concentration of mercury from human urine.

    PubMed

    Patricio, A; Fernandez, C; Mota, A M; Capelo, J L

    2006-05-15

    Dynamic and static ultrasonic procedures involving ultrasonic bath and tandem focused ultrasound (i.e. two probes were used in the same sample treatment) have been assessed in order to implement a reliable solid-liquid back extraction of mercury from commercial resins (dowex and chelex-100), previously used to concentrate Hg(II) from treated urine. The urine had been previously treated with an advanced oxidation process provided by the conjunction of potassium permanganate, hydrochloric acid and high intensity focused ultrasound, which allowed that organic matter degradation was achieved in less than 3min. 95+/-10% of mercury in the certified urine and 97+/-6% of the spiked methyl-mercury was recovered with the dowex resin plus the static ultrasonic procedure, whilst 96+/-11% of the spiked mercury was recovered with the dowex resin plus the dynamic procedure, for which ultrasonication was not necessary. The Hg pre-concentration factor used in this work was 8 (20mL of urine to 2.5mL of acid), but different volume ratios can be used in order to increase this factor.

  9. AN UPDATE ON MERCURY LOADINGS, TRANSPORT, AND FATE IN LAKE MICHIGAN

    EPA Science Inventory

    Mr. Rygwelski will present the results of a screening model to address the sources, transport, and fate of mercury from the Lake Michigan Mass Balance Study. The Lake Michigan Mass Balance Study is being spearheaded by the USEPA Great Lakes National Program Office, Region V, and ...

  10. Solid phase microextraction capillary gas chromatography combined with furnace atomization plasma emission spectrometry for speciation of mercury in fish tissues

    NASA Astrophysics Data System (ADS)

    Grinberg, Patricia; Campos, Reinaldo C.; Mester, Zoltan; Sturgeon, Ralph E.

    2003-03-01

    The use of solid phase microextraction in conjunction with tandem gas chromatography-furnace atomization plasma emission spectrometry (SPME-GC-FAPES) was evaluated for the determination of methylmercury and inorganic mercury in fish tissue. Samples were digested with methanolic potassium hydroxide, derivatized with sodium tetraethylborate and extracted by SPME. After the SPME extraction, species were separated by GC and detected by FAPES. All experimental parameters were optimized for best separation and analytical response. A repeatability precision of typically 2% can be achieved with long-term (3 months) reproducibility precision of 4.3%. Certified Reference Materials DORM-2, DOLT-2 and TORT-2 from the National Research Council of Canada were analyzed to verify the accuracy of this technique. Detection limits of 1.5 ng g -1 for methylmercury and 0.7 ng g -1 for inorganic mercury in biological tissues were obtained.

  11. Insentropic compression of solid using pulsed magnetic loading

    SciTech Connect

    HALL,CLINT A.; ASAY,JAMES R.; STYGAR,WILLIAM A.; SPIELMAN,RICK B.; ROSENTHAL,STEPHEN E.; KNUDSON,MARCUS D.; REISMAN,D.; TOOR,A.; CAUBLE,R.; HAYES,D.B.

    2000-04-18

    Shock loading techniques are often used to determine material response along a specific pressure loading curve referred to as the Hugoniot. However, many technological and scientific applications require accurate determination of dynamic material response that is off-Hugoniot, covering large regions of the equation-of-state surface. Unloading measurements from the shocked state provide off-Hugoniot information, but experimental techniques for measuring compressive off-Hugoniot response have been limited. A new pulsed magnetic loading technique is presented which provides previously unavailable information on isentropic loading of materials to pressures of several hundred kbar. This smoothly increasing pressure loading provides a good approximation to the high-pressure material isentrope centered at ambient conditions. The approach uses high current densities to create ramped magnetic loading to a few hundred kbar over time intervals of 100--200 ns. The method has successfully determined the isentropic mechanical response of copper to about 200 kbar and has been used to evaluate the kinetics of the alpha-epsilon phase transition occurring in iron at 130 kbar. With refinements in progress, the method shows promise for performing isentropic compression experiments to multi-Mbar pressures.

  12. Effect of high dry solids loading on enzymatic hydrolysis of acid bisulfite pretreated Eastern redcedar.

    PubMed

    Ramachandriya, Karthikeyan D; Wilkins, Mark; Atiyeh, Hasan K; Dunford, Nurhan T; Hiziroglu, Salim

    2013-11-01

    This study investigates hydrolysis of cellulose from Eastern redcedar to glucose at high solids loading. Enzymatic hydrolysis of pretreated redcedar was performed with 0.5 ml Accelerase® 1500/g glucan (46 FPU/g glucan) using dry solids loading from 2% to 20% (w/w). Rheological challenges observed at high solids loading were overcome by adding stainless steel balls to shake flask reactors. The highest glucose concentration, 126 g/L (84% glucan-to-glucose yield), was obtained using 20% solids loading with stainless steel balls as a mixing aid. This enzymatic hydrolyzate was fermented into ethanol using Saccharomyces cerevisiae D5A to produce 52 g/L of ethanol (corresponding to 166 L/dry Mg of redcedar). Reducing enzyme dosage at 16% solids loading from 46 to 11.5 FPU/g glucan reduced glucan-to-glucose yields. This study has demonstrated the possibility of extracting sugars from the invasive species of Eastern redcedar with high solid loadings and their conversion into ethanol.

  13. Dissolved-solids loads discharged from irrigated areas near Manila, Utah, May 2007-October 2012, and relation of loads to selected variables

    USGS Publications Warehouse

    Thiros, Susan A.; Gerner, Steven J.

    2015-01-01

    Irrigation improvements began to be implemented in 2007 to reduce dissolved-solids loads discharged from the MWSP area. The theoretical annual net dissolved-solids load where the cumulative NRCS calculated dissolved-solids load reduction is added to the net MWSP dissolved-solids load is what would be expected if there was no irrigation improvement in the area associated with the MWSP. The theoretical data points lie very near the baseline representing the pre-MWSP dissolved-solids load to canal streamflow relation. The proximity of the theoretical data points to the baseline shows that the NRCS calculations of reduction in dissolved-solids load are generally supported by the data collected during this study.

  14. DMPS (DIMAVAL) as a challenge test to assess the mercury and arsenic body/kidney load in humans and as a treatment of mercury toxicity

    SciTech Connect

    Aposhian, H.V.; Maiorino, R.M.; Aposhian, M.M.; Hurlbut, K.M.

    1996-12-31

    Mercury is an element which, with its compounds, is hazardous and is found in hazardous wastes. In Order to develop suitable diagnostic and therapeutic agents for mercury exposure, we have sought alternative test systems. We have used the chelating agent 2,3-dimercaptopropane-1-sulfonate (DMPS, DIMAVAL{reg_sign}) for estimating the body burden of mercury in normal humans and in dental personnel in a developing country, and for detoxifying humans with mercurous chloride exposure. Use of the DMPS-mercury challenge test has shown that two-thirds of the mercury excreted in the urine of volunteers with dental amalgams appears to be derived from the mercury vapor released from their amalgams. The DMPS challenge test (300 mg, by mouth, after an 11 hr fast) was useful for monitoring dental personnel for mercury vapor exposure. The DMPS challenge test was given to 11 factory workers who make a skin lotion that contains mercurous chloride, 8 users of the skin lotion, and 9 controls. The increases in urinary Hg resulting from the DMPS challenge were 45, 87, and 38-fold, respectively. The results demonstrate that in humans exposed to mercurous chloride, the DMPS-mercury challenge test is of value for a more realistic estimation of mobilizable Hg. DMPS should be considered for use to determine mercury body burdens and to treat humans exposed to mercury and its compounds via exposure to hazardous wastes. 42 refs., 2 figs., 5 tabs.

  15. High strain rate loading of polymeric foams and solid plastics

    NASA Astrophysics Data System (ADS)

    Dick, Richard D.; Chang, Peter C.; Fourney, William L.

    2000-04-01

    The split-Hopkinson pressure bar (SHPB) provided a technique to determine the high strain rate response for low density foams and solid ABS and polypropylene plastics. These materials are used in the interior safety panels of automobiles and crash test dummies. Because the foams have a very low impedance, polycarbonate bars were used to acquire the strain rate data in the 100 to 1600 l/s range. An aluminum SPHB setup was used to obtain the solid plastics data which covered strain rates of 1000 to 4000 l/s. The curves for peak strain rate versus peak stress for the foams over the test range studied indicates only a slight strain rate dependence. Peak strain rate versus peak stress curves for polypropylene shows a strain rate dependence up to about 1500 l/s. At that rate the solid poly propylene indicates no strain rate dependence. The ABS plastics are strain rate dependent up to 3500 l/s and then are independent at larger strain rates.

  16. A Comparative Electrochemical Behaviour Study and Analytical Detection of the p-Nitrophenol Using Silver Solid Amalgam, Mercury, and Silver Electrodes

    PubMed Central

    De Souza, Djenaine; Mascaro, Lucia H.; Fatibello-Filho, Orlando

    2011-01-01

    This work reports a comparative electrochemical behaviour study and p-nitrophenol analytical detection using silver solid amalgam, hanging dropping mercury, and silver electrodes. For this, square wave voltammetry was employed, where the analytical responses and the redox mechanisms could be compared for reduction processes of 4-nitrophenol by analysis of the voltammetric responses. The analytical performance of the electrode was evaluated and detection and quantification limits, recovery percentages, repeatability, and reproducibility for the silver solid amalgam and hanging dropping mercury electrodes presented similar values; the results presented for the silver electrode indicated worse analytical parameters than the other electrodes. The results indicate that the silver solid amalgam electrode can be considered a suitable tool and an interesting alternative for the analytical determination of 4-nitrophenol, as well as for the determination of other biological and environmentally interesting compounds that present analytical responses on mercury surfaces. PMID:21647286

  17. The use of high-solids loadings in biomass pretreatment--a review.

    PubMed

    Modenbach, Alicia A; Nokes, Sue E

    2012-06-01

    The use of high-solids loadings (≥ 15% solids, w/w) in the unit operations of lignocellulose conversion processes potentially offers many advantages over lower-solids loadings, including increased sugar and ethanol concentrations and decreased production and capital costs. Since the term lignocellulosic materials refers to a wide range of feedstocks (agricultural and forestry residues, distillery by-products, and dedicated energy crops like grasses), the term "solids loading" here is defined by the amount of dry material that enters the process divided by the total mass of material and water added to the material. The goal of this study is to provide a consolidated review of studies using a high-solids pretreatment step in the conversion process. Included in this review is a brief discussion of the limitations, such as the lack of available water to promote mass transfer, increased substrate viscosity, and increased concentration of inhibitors produced affecting pretreatment, as well as descriptions and findings of pretreatment studies performed at high solids, the latest reactor designs developed for pretreatment at bench- and pilot-scales to address some of the limitations, and high-solids pretreatment operations that have been scaled-up and incorporated into demonstration facilities.

  18. Dissolved-solids sources, loads, yields, and concentrations in streams of the conterminous United States

    USGS Publications Warehouse

    Anning, David W.; Flynn, Marilyn E.

    2014-01-01

    Results from the trend analysis and from the SPARROW model indicate that, compared to monitoring stations with no trends or decreasing trends, stations with increasing trends are associated with a smaller percentage of the predicted dissolved-solids load originating from geologic sources, and a larger percentage originating from urban lands and road deicers. Conversely, compared to stations with increasing trends or no trends, stations with decreasing trends have a larger percentage of the predicted dissolved-solids load originating from geologic sources and a smaller percentage originating from urban lands and road deicers. Stations with decreasing trends also have larger percentages of predicted dissolved-solids load originating from cultivated lands and pasture lands, compared to stations with increasing trends or no trends.

  19. Mercury speciation analysis in sea water by solid phase microextraction?gas chromatography?inductively coupled plasma mass spectrometry using ethyl and propyl derivatization. Matrix effects evaluation

    NASA Astrophysics Data System (ADS)

    Bravo-Sánchez, Luis R.; Ruiz Encinar, Jorge; Fidalgo Martínez, José I.; Sanz-Medel, Alfredo

    2004-01-01

    An approach to the speciation analysis of mercury in sea-water samples at sub-ppt levels by means of the hyphenation of solid phase microextraction to gas chromatography-inductively coupled plasma mass spectrometry was developed. Blank values turned out to be the limiting factor for lower detection limits of inorganic mercury. Thus, all the reagents were thoroughly cleaned using laboratory made microcolumns packed with 8-hydroxyquinoline on TSK gel. Sodium tetrapropylborate (NaBPr 4) synthesized for the purpose of derivatization of the mercury species resulted in better analytical performances of the method, probably due to lower mercury contamination, than commercial sodium tetraethylborate (NaBEt 4). Detection limits down to a few picogram per liter for both mercury and methylmercury were obtained using NaBPr 4. The high salt content of sea-water samples was responsible for strong matrix effects, which were overcome by using standards additions to the samples. The validation of the methodology was carried out by direct comparison of the results for inorganic mercury with those obtained using a flow injection system followed by preconcentration/trapping of the species and its detection by atomic absorption spectrometry. The proposed method was applied to the determination of mercury and methylmercury in coastal sea-water samples from Gijón (Asturias, Spain) and results obtained are discussed in the light of the butyltin levels previously determined in the same area.

  20. Characterization of suspended solids and total phosphorus loadings from small watersheds in Wisconsin

    USGS Publications Warehouse

    Danz, Mari E.; Corsi, Steven R.; Graczyk, David J.; Bannerman, Roger T.

    2010-01-01

    Knowledge of the daily, monthly, and yearly distribution of contaminant loadings and streamflow can be critical for the successful implementation and evaluation of water-quality management practices. Loading data for solids (suspended sediment and total suspended solids) and total phosphorus and streamflow data for 23 watersheds were summarized for four ecoregions of Wisconsin: the Driftless Area Ecoregion, the Northern Lakes and Forests Ecoregion, the North Central Hardwoods Ecoregion, and the Southeastern Wisconsin Till Plains Ecoregion. The Northern Lakes and Forests and the North Central Hardwoods Ecoregions were combined into one region for analysis due to a lack of sufficient data in each region. Urban watersheds, all located in the Southeastern Wisconsin Till Plains, were analyzed separately from rural watersheds as the Rural Southeastern Wisconsin Till Plains region and the Urban Southeastern Wisconsin Till Plains region. Results provide information on the distribution of loadings and streamflow between base flow and stormflow, the timing of loadings and streamflow throughout the year, and information regarding the number of days in which the majority of the annual loading is transported. The average contribution to annual solids loading from stormflow periods for the Driftless Area Ecoregion was 84 percent, the Northern Lakes and Forests/North Central Hardwoods region was 71 percent, the Rural Southeastern Wisconsin Till Plains region was 70 percent, and the Urban Southeastern Wisconsin Till Plains region was 90 percent. The average contributions to annual total phosphorus loading from stormflow periods were 72, 49, 61, and 76 percent for each of the respective regions. The average contributions to annual streamflow from stormflow periods are 20, 23, 31, and 50 percent for each of the respective regions. In all regions, the most substantial loading contributions for solids were in the late winter (February through March), spring (April through May), and

  1. Buparvaquone loaded solid lipid nanoparticles for targeted delivery in theleriosis

    PubMed Central

    Soni, Maheshkumar P.; Shelkar, Nilakash; Gaikwad, Rajiv V.; Vanage, Geeta R.; Samad, Abdul; Devarajan, Padma V.

    2014-01-01

    Background: Buparvaquone (BPQ), a hydroxynaphthoquinone derivative, has been investigated for the treatment of many infections and is recommended as the gold standard for the treatment of theileriosis. Theileriosis, an intramacrophage infection is localized mainly in reticuloendotheileial system (RES) organs. The present study investigates development of solid lipid nanoparticles (SLN) of BPQ for targeted delivery to the RES. Materials and Methods: BPQ SLN was prepared using melt method by adding a molten mixture into aqueous Lutrol F68 solution (80°C). Larger batches were prepared up to 6 g of BPQ with GMS: BPQ, 2:1. SLN of designed size were obtained using ultraturrax and high pressure homogenizer. A freeze and thaw study was used to optimize type and concentration of cryoprotectant with Sf: Mean particle size, Si: Initial particle size <1.3. Differential scanning calorimetry (DSC), powder X-ray diffraction (XRD) and scanning electron microscope (SEM) study was performed on optimized formulation. Formulation was investigated for in vitro serum stability, hemolysis and cell uptake study. Pharmacokinetic and biodistribution study was performed in Holtzman rat. Results: Based on solubility in lipid; glyceryl monostearate (GMS) was selected for preparation of BPQ SLN. Batches of BPQ SLN were optimized for average particle size and entrapment efficiency at <100 mg solid content. A combination of Solutol HS-15 and Lutrol F68 at 2% w/v and greater enabled the desired Sf/Si < 1.3. Differential scanning calorimetry and powder X-ray diffraction revealed decrease in crystallinity of BPQ in BPQ SLN while, scanning electron microscope revealed spherical morphology. BPQ SLN revealed good stability at 4°C and 25°C. Low hemolytic potential (<8%) and in vitro serum stability up to 5 h was observed. Cytotoxicity of SLN to the U937 cell was low. The macrophage cell line revealed high (52%) uptake of BPQ SLN in 1 h suggesting the potential to RES uptake. SLN revealed longer

  2. Ultrasensitive Speciation Analysis of Mercury in Rice by Headspace Solid Phase Microextraction Using Porous Carbons and Gas Chromatography-Dielectric Barrier Discharge Optical Emission Spectrometry.

    PubMed

    Lin, Yao; Yang, Yuan; Li, Yuxuan; Yang, Lu; Hou, Xiandeng; Feng, Xinbin; Zheng, Chengbin

    2016-03-01

    Rice consumption is a primary pathway for human methylmercury (MeHg) exposure in inland mercury mining areas of Asia. In addition, the use of iodomethane, a common fumigant that significantly accelerates the methylation of mercury in soil under sunlight, could increase the MeHg exposure from rice. Conventional hyphenated techniques used for mercury speciation analysis are usually too costly for most developing countries. Consequently, there is an increased interest in the development of sensitive and inexpensive methods for the speciation of mercury in rice. In this work, gas chromatography (GC) coupled to dielectric barrier discharge optical emission spectrometry (DBD-OES) was developed for the speciation analysis of mercury in rice. Prior to GC-DBD-OES analysis, mercury species were derivatized to their volatile species with NaBPh4 and preconcentrated by headspace solid phase microextraction using porous carbons. Limits of detection of 0.5 μg kg(-1) (0.16 ng), 0.75 μg kg(-1) (0.24 ng), and 1.0 μg kg(-1) (0.34 ng) were obtained for Hg(2+), CH3Hg(+), and CH3CH2Hg(+), respectively, with relative standard deviations (RSDs) better than 5.2% and 6.8% for one fiber or fiber-to-fiber mode, respectively. Recoveries of 90-105% were obtained for the rice samples, demonstrating the applicability of the proposed technique. Owing to the small size, low power, and low gas consumption of DBD-OES as well as efficient extraction of mercury species by porous carbons headspace solid phase micro-extraction, the proposed technique provides several advantages including compactness, cost-effectiveness, and potential to couple with miniature GC to accomplish the field speciation of mercury in rice compared to conventional hyphenated techniques.

  3. Mass loads of dissolved and particulate mercury and other trace elements in the Mt. Amiata mining district, Southern Tuscany (Italy).

    PubMed

    Rimondi, V; Costagliola, P; Gray, J E; Lattanzi, P; Nannucci, M; Paolieri, M; Salvadori, A

    2014-04-01

    Total dissolved and particulate mercury (Hg), arsenic (As), and antimony (Sb) mass loads were estimated in different seasons (March and September 2011 and March 2012) in the Paglia River basin (PRB) (central Italy). The Paglia River drains the Mt. Amiata Hg district, one of the largest Hg-rich regions worldwide. Quantification of Hg, As, and Sb mass loads in this watershed allowed (1) identification of the contamination sources, (2) evaluation of the effects of Hg on the environment, and (3) determination of processes affecting Hg transport. The dominant source of Hg in the Paglia River is runoff from Hg mines in the Mt. Amiata region. The maximum Hg mass load was found to be related to runoff from the inactive Abbadia San Salvatore Mine (ASSM), and up to 30 g day(-1) of Hg, dominantly in the particulate form, was transported both in high and low flow conditions in 2011. In addition, enrichment factors (EFs) calculated for suspended particulate matter (SPM) were similar in different seasons indicating that water discharge controls the quantities of Hg transported in the PRB, and considerable Hg was transported in all seasons studied. Overall, as much as 11 kg of Hg are discharged annually in the PRB and this Hg is transported downstream to the Tiber River, and eventually to the Mediterranean Sea. Similar to Hg, maximum mass loads for As and Sb were found in March 2011, when as much as 190 g day(-1) each of As and Sb were measured from sites downstream from the ASSM. Therefore, the Paglia River represents a significant source of Hg, Sb, and As to the Mediterranean Sea. PMID:24414225

  4. Mass loads of dissolved and particulate mercury and other trace elements in the Mt. Amiata mining district, Southern Tuscany (Italy)

    USGS Publications Warehouse

    Rimondi, V.; Costagliola, P.; Gray, J.E.; Lattanzi, P.; Nannucci, M.; Paolieri, M.; Salvadori, A.

    2014-01-01

    Total dissolved and particulate mercury (Hg), arsenic (As), and antimony (Sb) mass loads were estimated in different seasons (March and September 2011 and March 2012) in the Paglia River basin (PRB) (central Italy). The Paglia River drains the Mt. Amiata Hg district, one of the largest Hg-rich regions worldwide. Quantification of Hg, As, and Sb mass loads in this watershed allowed (1) identification of the contamination sources, (2) evaluation of the effects of Hg on the environment, and (3) determination of processes affecting Hg transport. The dominant source of Hg in the Paglia River is runoff from Hg mines in the Mt. Amiata region. The maximum Hg mass load was found to be related to runoff from the inactive Abbadia San Salvatore Mine (ASSM), and up to 30 g day−1 of Hg, dominantly in the particulate form, was transported both in high and low flow conditions in 2011. In addition, enrichment factors (EFs) calculated for suspended particulate matter (SPM) were similar in different seasons indicating that water discharge controls the quantities of Hg transported in the PRB, and considerable Hg was transported in all seasons studied. Overall, as much as 11 kg of Hg are discharged annually in the PRB and this Hg is transported downstream to the Tiber River, and eventually to the Mediterranean Sea. Similar to Hg, maximum mass loads for As and Sb were found in March 2011, when as much as 190 g day−1 each of As and Sb were measured from sites downstream from the ASSM. Therefore, the Paglia River represents a significant source of Hg, Sb, and As to the Mediterranean Sea.

  5. Formulation and Evaluation of Morin-Loaded Solid Lipid Nanoparticles.

    PubMed

    Ikeuchi-Takahashi, Yuri; Ishihara, Chizuko; Onishi, Hiraku

    2016-09-01

    In this study, solid lipid nanoparticle (SLN) suspensions were prepared using a base of hard fat with or without ethylcellulose (EC) and polyvinyl alcohols (PVA) and polysorbate (Tween) 60 surfactants. Commercially available PVAs vary in their degree of saponification and polymerization, and the appropriate PVAs to form SLNs from hard fat with or without EC were investigated. A relatively low-saponification-degree PVA was required to reproducibly form SLN suspensions without EC and relatively high-saponification-degree PVAs were suitable for SLNs with EC. The release of morin from SLNs with EC was more sustained than that from SLNs without EC. The maximum plasma concentration (Cmax) of SLNs with and without EC were almost the same, and both were higher than that of a morin suspension. The area under the curve for 0 to 360 min (AUC0-360) of SLNs with EC was increased compared with those of a morin suspension and SLNs without EC. The median diameter of SLNs with EC and a very low-saponification-degree PVA was decreased compared to other formulation, and morin release was more sustained for this formulation. SLNs with EC and a very low-saponification-degree PVA showed higher Cmax and AUC0-360 than SLNs with EC lacking a very low-saponification-degree PVA. The optimized SLNs with EC and a very low-saponification-degree PVA improved bioavailability via increased accessibility to the enterocyte surface by decreased particle size and increased permeation of SLN encapsulated morin through the intestinal membrane by sustained release properties.

  6. Regenerable cobalt oxide loaded magnetosphere catalyst from fly ash for mercury removal in coal combustion flue gas.

    PubMed

    Yang, Jianping; Zhao, Yongchun; Zhang, Junying; Zheng, Chuguang

    2014-12-16

    To remove Hg(0) in coal combustion flue gas and eliminate secondary mercury pollution of the spent catalyst, a new regenerable magnetic catalyst based on cobalt oxide loaded magnetospheres from fly ash (Co-MF) was developed. The catalyst, with an optimal loading of 5.8% cobalt species, attained approximately 95% Hg(0) removal efficiency at 150 °C under simulated flue gas atmosphere. O2 could enhance the Hg(0) removal activity of magnetospheres catalyst via the Mars-Maessen mechanism. SO2 displayed an inhibitive effect on Hg(0) removal capacity. NO with lower concentration could promote the Hg(0) removal efficiency. However, when increasing the NO concentration to 300 ppm, a slightly inhibitive effect of NO was observed. In the presence of 10 ppm of HCl, greater than 95.5% Hg(0) removal efficiency was attained, which was attributed to the formation of active chlorine species on the surface. H2O presented a seriously inhibitive effect on Hg(0) removal efficiency. Repeated oxidation-regeneration cycles demonstrated that the spent Co-MF catalyst could be regenerated effectively via thermally treated at 400 °C for 2 h.

  7. Regenerable cobalt oxide loaded magnetosphere catalyst from fly ash for mercury removal in coal combustion flue gas.

    PubMed

    Yang, Jianping; Zhao, Yongchun; Zhang, Junying; Zheng, Chuguang

    2014-12-16

    To remove Hg(0) in coal combustion flue gas and eliminate secondary mercury pollution of the spent catalyst, a new regenerable magnetic catalyst based on cobalt oxide loaded magnetospheres from fly ash (Co-MF) was developed. The catalyst, with an optimal loading of 5.8% cobalt species, attained approximately 95% Hg(0) removal efficiency at 150 °C under simulated flue gas atmosphere. O2 could enhance the Hg(0) removal activity of magnetospheres catalyst via the Mars-Maessen mechanism. SO2 displayed an inhibitive effect on Hg(0) removal capacity. NO with lower concentration could promote the Hg(0) removal efficiency. However, when increasing the NO concentration to 300 ppm, a slightly inhibitive effect of NO was observed. In the presence of 10 ppm of HCl, greater than 95.5% Hg(0) removal efficiency was attained, which was attributed to the formation of active chlorine species on the surface. H2O presented a seriously inhibitive effect on Hg(0) removal efficiency. Repeated oxidation-regeneration cycles demonstrated that the spent Co-MF catalyst could be regenerated effectively via thermally treated at 400 °C for 2 h. PMID:25403026

  8. Mercury loading and methylmercury production and cycling in high-altitude lakes from the Western United States

    USGS Publications Warehouse

    Krabbenhoft, David P.; Olson, Mark L.; DeWild, John F.; Clow, David W.; Striegl, Rob; Dornblaser, Mark M.; Van Metre, Peter C.

    2002-01-01

    Studies worldwide have shown that mercury (Hg) is a ubiquitous contaminant, reaching even the most remote environments such as high-altitude lakes via atmospheric pathways. However, very few studies have been conducted to assess Hg contamination levels of these systems. We sampled 90 mid-latitude, high-altitude lakes from seven national parks in the western United States during a four-week period in September 1999. In addition to the synoptic survey, routine monitoring and experimental studies were conducted at one of the lakes (Mills Lake) to quantify MeHg fluxrates and important process rates such as photo-demethylation. Results show that overall, high-altitude lakes have low total mercury (HgT) and methylmercury (MeHg) levels (1.07 and 0.05 ng L-1, respectively), but a very good correlation of Hg to MeHg (r2= 0.82) suggests inorganic Hg(II) loading is a primary controlling factor of MeHg levels in dilute mountain lakes. Positive correlations were also observed for dissolved organic carbon (DOC) and both Hg and MeHg, although to a much lesser degree. Levels of MeHg were similar among the seven national parks, with the exception of Glacier National Park where lowerconcentrations were observed (0.02 ng L-1), and appear to be related to naturally elevated pH values there. Measured rates ofMeHg photo-degradation at Mills Lake were quite fast, and this process was of equal importance to sedimentation and stream flow for removing MeHg. Enhanced rates of photo-demethylation are likely an important reason why high-altitude lakes, with typically high water clarity and sunlight exposure, are low in MeHg.

  9. A mercury transport and fate model (LM2-mercury) for mass budget assessment of mercury cycling in Lake Michigan

    EPA Science Inventory

    LM2-Mercury, a mercury mass balance model, was developed to simulate and evaluate the transport, fate, and biogeochemical transformations of mercury in Lake Michigan. The model simulates total suspended solids (TSS), disolved organic carbon (DOC), and total, elemental, divalent, ...

  10. Mercury and cadmium trigger expression of the copper importer Ctr1B, which enables Drosophila to thrive on heavy metal-loaded food.

    PubMed

    Balamurugan, Kuppusamy; Hua, Haiqing; Georgiev, Oleg; Schaffner, Walter

    2009-02-01

    Organisms from insects to mammals respond to heavy metal load (copper, zinc, cadmium, and mercury) by activating the metal-responsive transcription factor 1 (MTF-1). MTF-1 binds to short DNA sequence motifs, termed metal response elements, and boosts transcription of a number of genes, notably those for metallothioneins. In Drosophila, MTF-1 somewhat counter-intuitively also activates transcription of a copper importer gene (Ctr1B) in response to copper starvation. Here, we report that mutant flies lacking Ctr1B are extremely sensitive to cadmium and mercury treatment, but can be rescued by excess copper in the food. We thus propose that copper, by competing for binding sites on cellular proteins, alleviates the toxic effects of mercury and cadmium. Such a scenario also explains a seemingly fortuitous metal response, namely, that cadmium and mercury strongly induce the expression of a Ctr1B reporter gene. Thus, the transcription enhancer/promoter region of the Ctr1B copper importer gene is subject to three modes of regulation. All of them depend on MTF-1 and all make biological sense, namely, (i) induction by copper starvation, (ii) repression by copper abundance, and (iii), as shown here, induction by cadmium or mercury at normal copper supply.

  11. Sugar loss and enzyme inhibition due to oligosaccharides accumulation during high solids-loading enzymatic hydrolysis

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Oligosaccharide accumulation occurs during high solid loading enzymatic hydrolysis of corn stover (CS) irrespective of using different pretreated corn stover (dilute acid: DA, ionic liquids: IL, ammonia fiber expansion: AFEX and extractive ammonia: EA). The methodology for large-scale separation of ...

  12. Development and evaluation of alginate-chitosan gastric floating beads loading with oxymatrine solid dispersion.

    PubMed

    Liu, Yanhua; Chen, Lihong; Zhou, Chengming; Yang, Jianhong; Hou, Yanhui; Wang, Wenping

    2016-01-01

    Oxymatrine (OM) can be metabolized to matrine in gastrointestinal ileocecal valve after oral administration, which affects pharmacological activity and reduce bioavailability of OM. A type of multiple-unit alginate-chitosan (Alg-Cs) floating beads was prepared by the ionotropic gelation method for gastroretention delivery of OM. A solid dispersion technique was applied and incorporated into beads to enhance the OM encapsulation efficiency (EE) and sustain the drug release. The surface morphology and internal hollow structure of beads were evaluated using optical microscopy and scanning electron microscopy (SEM). The developed Alg-Cs beads were spherical in shape with hollow internal structure and had particle size of 3.49 ± 0.09 mm and 1.33 ± 0.09 mm for wet and dried beads. Over 84% of the optimized OM solid dispersion-loaded Alg-Cs beads were able to continuously float over the simulated gastric fluid for 12 h in vitro. The OM solid dispersion-loaded Alg-Cs beads showed drug EE of 67.07%, which was much higher than that of beads loading with pure OM. Compared with the immediate release of OM capsules and pure OM-loaded beads, the release of OM from solid dispersion-loaded Alg-Cs beads was in a sustained-release manner for 12 h. Prolonged gastric retention time of over 8.5 h was achieved for OM solid dispersion-loaded Alg-Cs floating beads in healthy rabbit in in vivo floating ability evaluated by X-ray imaging. The developed Alg-Cs beads loading with OM solid dispersion displayed excellent performance features characterized by excellent gastric floating ability, high drug EE and sustained-release pattern. The study illustrated the potential use of Alg-Cs floating beads combined with the solid dispersion technique for prolonging gastric retention and sustaining release of OM, which could provide a promising drug delivery system for gastric-specific delivery of OM for bioavailability enhancement.

  13. Recent advances in solid polymer electrolyte fuel cell technology with low platinum loading electrodes

    NASA Technical Reports Server (NTRS)

    Srinivasan, Supramaniam; Manko, David J.; Koch, Hermann; Enayetullah, Mohammad A.; Appleby, A. John

    1989-01-01

    Of all the fuel cell systems only alkaline and solid polymer electrolyte fuel cells are capable of achieving high power densities (greater than 1 W/sq cm) required for terrestrial and extraterrestrial applications. Electrode kinetic criteria for attaining such high power densities are discussed. Attainment of high power densities in solid polymer electrolyte fuel cells has been demonstrated earlier by different groups using high platinum loading electrodes (4 mg/sq cm). Recent works at Los Alamos National Laboratory and at Texas A and M University (TAMU) demonstrated similar performance for solid polymer electrolyte fuel cells with ten times lower platinum loading (0.45 mg/sq cm) in the electrodes. Some of the results obtained are discussed in terms of the effects of type and thickness of membrane and of the methods platinum localization in the electrodes on the performance of a single cell.

  14. Characterizing shallow secondary clarifier performance where conventional flux theory over-estimates allowable solids loading rate.

    PubMed

    Daigger, Glen T; Siczka, John S; Smith, Thomas F; Frank, David A; McCorquodale, J A

    2016-01-01

    The performance characteristics of relatively shallow (3.3 and 3.7 m sidewater depth in 30.5 m diameter) activated sludge secondary clarifiers were extensively evaluated during a 2-year testing program at the City of Akron Water Reclamation Facility (WRF), Ohio, USA. Testing included hydraulic and solids loading stress tests, and measurement of sludge characteristics (zone settling velocity (ZSV), dispersed and flocculated total suspended solids), and the results were used to calibrate computational fluid dynamic (CFD) models of the various clarifiers tested. The results demonstrated that good performance could be sustained at surface overflow rates in excess of 3 m/h, as long as the clarifier influent mixed liquor suspended solids (MLSS) concentration was controlled to below critical values. The limiting solids loading rate (SLR) was significantly lower than the value predicted by conventional solids flux analysis based on the measured ZSV/MLSS relationship. CFD analysis suggested that this resulted because mixed liquor entering the clarifier was being directed into the settled sludge blanket, diluting it and also creating a 'thin' concentration sludge blanket that overlays the thicker concentration sludge blanket typically expected. These results indicate the need to determine the allowable SLR for shallow clarifiers using approaches other than traditional solids flux analysis. A combination of actual testing and CFD analyses are demonstrated here to be effective in doing so.

  15. Characterizing shallow secondary clarifier performance where conventional flux theory over-estimates allowable solids loading rate.

    PubMed

    Daigger, Glen T; Siczka, John S; Smith, Thomas F; Frank, David A; McCorquodale, J A

    2016-01-01

    The performance characteristics of relatively shallow (3.3 and 3.7 m sidewater depth in 30.5 m diameter) activated sludge secondary clarifiers were extensively evaluated during a 2-year testing program at the City of Akron Water Reclamation Facility (WRF), Ohio, USA. Testing included hydraulic and solids loading stress tests, and measurement of sludge characteristics (zone settling velocity (ZSV), dispersed and flocculated total suspended solids), and the results were used to calibrate computational fluid dynamic (CFD) models of the various clarifiers tested. The results demonstrated that good performance could be sustained at surface overflow rates in excess of 3 m/h, as long as the clarifier influent mixed liquor suspended solids (MLSS) concentration was controlled to below critical values. The limiting solids loading rate (SLR) was significantly lower than the value predicted by conventional solids flux analysis based on the measured ZSV/MLSS relationship. CFD analysis suggested that this resulted because mixed liquor entering the clarifier was being directed into the settled sludge blanket, diluting it and also creating a 'thin' concentration sludge blanket that overlays the thicker concentration sludge blanket typically expected. These results indicate the need to determine the allowable SLR for shallow clarifiers using approaches other than traditional solids flux analysis. A combination of actual testing and CFD analyses are demonstrated here to be effective in doing so. PMID:27438236

  16. Method development for the control determination of mercury in seafood by solid-sampling thermal decomposition amalgamation atomic absorption spectrometry (TDA AAS).

    PubMed

    Torres, D P; Martins-Teixeira, M B; Silva, E F; Queiroz, H M

    2012-01-01

    A very simple and rapid method for the determination of total mercury in fish samples using the Direct Mercury Analyser DMA-80 was developed. In this system, a previously weighted portion of fresh fish is combusted and the released mercury is selectively trapped in a gold amalgamator. Upon heating, mercury is desorbed from the amalgamator, an atomic absorption measurement is performed and the mercury concentration is calculated. Some experimental parameters have been studied and optimised. In this study the sample mass was about 100.0 mg. The relative standard deviation was lower than 8.0% for all measurements of solid samples. Two calibration curves against aqueous standard solutions were prepared through the low linear range from 2.5 to 20.0 ng of Hg, and the high linear range from 25.0 to 200.0 ng of Hg, for which a correlation coefficient better than 0.997 was achieved, as well as a normal distribution of the residuals. Mercury reference solutions were prepared in 5.0% v/v nitric acid medium. Lyophilised fish tissues were also analysed; however, the additional procedure had no advantage over the direct analysis of the fresh fish, and additionally increased the total analytical process time. A fish tissue reference material, IAEA-407, was analysed and the mercury concentration was in agreement with the certified value, according to the t-test at a 95% confidence level. The limit of quantification (LOQ), based on a mercury-free sample, was 3.0 µg kg(-1). This LOQ is in accordance with performance criteria required by the Commission Regulation No. 333/2007. Simplicity and high efficiency, without the need for any sample preparation procedure, are some of the qualities of the proposed method.

  17. Preparation and pharmaceutical evaluation of new tacrolimus-loaded solid self-emulsifying drug delivery system.

    PubMed

    Seo, Youn Gee; Kim, Dong-Wuk; Cho, Kwan Hyung; Yousaf, Abid Mehmood; Kim, Dong Shik; Kim, Jeong Hoon; Kim, Jong Oh; Yong, Chul Soon; Choi, Han-Gon

    2015-02-01

    The purpose of this study was to develop a novel tacrolimus-loaded solid self-emulsifying drug delivery system (SEDDS) using Labrafac as an oil phase. The ternary phase diagram was plotted with Labrafac, Labrasol and Lauroglycol used as an oil, surfactant and co-surfactant, respectively. The liquid SEDDS formulated with Labrasol, Lauroglycol and Labrafac (70:15:15, volume ratio) furnished the smallest emulsion globule size. The solid SEDDS was obtained by spray-drying the liquid mixture containing the liquid SEDDS with 5 % tacrolimus and silicon dioxide. Furthermore, dissolution of tacrolimus from the solid SEDDS and pharmacokinetics in rats was studied compared to the commercial product. The solid SEDDS produced relatively larger emulsion globule size than that exhibited by the corresponding liquid SEDDS. However, this size variation was not significantly different. The solid SEDDS with approximately 280 nm emulsion droplet size improved the dissolution of the drug compared to drug power and the commercial product. It resulted in significantly higher plasma concentration, AUC and Cmax, and shorter Tmax values than did the commercial product (p < 0.05). The enormously enhanced oral bioavailability of tacrolimus in rats was attributed to relatively faster absorption due to accelerated dissolution of the drug from the solid SEDDS. Therefore, this novel solid SEDDS prepared with Labrafac as an oil phase is an excellent way to achieve better bioavailability of tacrolimus given via the oral route.

  18. A comparison of load estimates using total suspended solids and suspended-sediment concentration data

    USGS Publications Warehouse

    Glysson, G.D.; Gray, J.R.; Schwarz, G.E.

    2001-01-01

    This paper presents the results to-date from a continuing investigation into the differences between total suspended solids (TSS) and suspended-sediment concentration (SSC) data and the ramifications of using each type of data to estimate sediment loads. It compares estimates of annual suspended-sediment loads that were made using regression equations developed from paired TSS and SSC data, to annual loads computed by the U.S. Geological Survey (USGS) using traditional techniques and SSC data. Load estimates were compared for 10 stations where sufficient TSS and SSC paired data were available to develop sediment-transport curves for the same time period that daily suspended-sediment records were available. Results of these analyses indicate that as the time frame over which the estimates were made increases, the overall errors associated with the estimates decreases with respect to loads computed using traditional USGS techniques. Using SSC data to compute loads tends to produce estimates closer to those computed by traditional techniques than those computed from TSS data. Loads computed from TSS data tend to be negatively biased with respect to those computed by traditional USGS techniques.

  19. Dissolved-Solids Load in Henrys Fork Upstream from the Confluence with Antelope Wash, Wyoming, Water Years 1970-2009

    USGS Publications Warehouse

    Foster, Katharine; Kenney, Terry A.

    2010-01-01

    Annual dissolved-solids load at the mouth of Henrys Fork was estimated by using data from U.S. Geological Survey streamflow-gaging station 09229500, Henrys Fork near Manila, Utah. The annual dissolved-solids load for water years 1970-2009 ranged from 18,300 tons in 1977 to 123,300 tons in 1983. Annual streamflows for this period ranged from 14,100 acre-feet in 1977 to 197,500 acre-feet in 1983. The 25-percent trimmed mean dissolved-solids load for water years 1970-2009 was 44,300 tons per year at Henrys Fork near Manila, Utah. Previous simulations using a SPAtially Referenced Regression On Watershed attributes (SPARROW) model for dissolved solids specific to water year 1991 conditions in the Upper Colorado River Basin predicted an annual dissolved-solids load of 25,000 tons for the Henrys Fork Basin upstream from Antelope Wash. On the basis of computed dissolved-solids load data from Henrys Fork near Manila, Utah, together with estimated annual dissolved-solids load from Antelope Wash and Peoples Canal, this prediction was adjusted to 37,200 tons. As determined by simulations with the Upper Colorado River Basin SPARROW model, approximately 56 percent (14,000 tons per year) of the dissolved-solids load at Henrys Fork upstream from Antelope Wash is associated with the 21,500 acres of irrigated agricultural lands in the upper Henrys Fork Basin.

  20. MODELING MERCURY FLUXES AND CONCENTRATIONS IN A GEORGIA WATERSHED RECEIVING ATMOSPHERIC DEPOSITION LOAD FROM DIRECT AND INDIRECT SOURCES

    EPA Science Inventory

    This paper presents a modeling analysis of airborne mercury deposited onto the Ochlockonee River watershed located in Georgia, USA. Atmospheric deposition monitoring and source attribution data were used along with simulation models to calculate mercury build-up in the subwatersh...

  1. A Mercury Transport and Fate Model for Mass Budget Assessment of Mercury Cycling in Lake Michigan

    EPA Science Inventory

    A mercury mass balance model was developed to describe and evaluate the fate, transport, and biogeochemical transformations of mercury in Lake Michigan. Coupling with total suspendable solids (TSS) and dissolved organic carbon (DOC), the mercury transport and fate model simulates...

  2. A new approach to solid-state on-load tap changers

    SciTech Connect

    Demirci, O.; Torrey, D.A.; Degeneff, R.C.; Schaeffer, F.K.; Frazer, R.H.

    1996-11-01

    This paper presents a new approach for constructing solid-state on-load tap changers. Through a judicious choice of the tap changer topology and a novel use of the control, the system is able to offer up to 48 steps in place of the 16 steps associated with mechanical tap changers. Further, it is able to do this with fewer physical transformer tap windings. The tap changer concept has been experimentally verified in the laboratory. An example for a 34.5 kV 30 MVA transformer is presented to illustrate the economic benefit of this concept. The approach presented can be 20--50% less expensive than previous efforts to realize solid-state on-load tap changers.

  3. Enzymatic hydrolysis of pelletized AFEX™-treated corn stover at high solid loadings.

    PubMed

    Bals, Bryan D; Gunawan, Christa; Moore, Janette; Teymouri, Farzaneh; Dale, Bruce E

    2014-02-01

    Ammonia fiber expansion (AFEX™) pretreatment can be performed at small depots, and the pretreated biomass can then be pelletized and shipped to a centralized refinery. To determine the feasibility of this approach, pelletized AFEX-treated corn stover was hydrolyzed at high (18-36%) solid loadings. Water absorption and retention by the pellets was low compared to unpelletized stover, which allowed enzymatic hydrolysis slurries to remain well mixed without the need for fed-batch addition. Glucose yields of 68% and xylose yields of 65% were obtained with 20 mg enzyme/g glucan and 18% solid loading after 72 h, compared to 61% and 59% for unpelletized corn stover. Pelletization also slightly increased the initial rate of hydrolysis compared to unpelletized biomass. The ease of mixing and high yields obtained suggests that pelletization after AFEX pretreatment could have additional advantages beyond improved logistical handling of biomass.

  4. Chip-Based Magnetic Solid-Phase Microextraction Online Coupled with MicroHPLC-ICPMS for the Determination of Mercury Species in Cells.

    PubMed

    Wang, Han; Chen, Beibei; Zhu, Siqi; Yu, Xiaoxiao; He, Man; Hu, Bin

    2016-01-01

    Trace mercury speciation in cells is critical to understand its cytotoxicity and cell protection mechanism. In this work, we fabricated a chip-based magnetic solid-phase microextraction (MSPME) system, integrating a cell lysis unit as well as a sample extraction unit, and online combined it with micro high-performance liquid chromatography (microHPLC)-inductively coupled plasma mass spectrometry (ICPMS) for the speciation of mercury in HepG2 cells. Magnetic nanoparticles with sulfhydryl functional group were synthesized and self-assembled in the microchannels for the preconcentration of mercury species in cells under an external magnetic field. The enrichment factors are ca. 10-fold, and the recoveries for the spiked samples are in the range of 98.3-106.5%. The developed method was used to analyze target mercury species in Hg(2+) or MeHg(+) incubated HepG2 cells. The results demonstrated that MeHg(+) entered into the HepG2 cells more easily than Hg(2+), and part of the MeHg(+) might demethylate into Hg(2+) in HepG2 cells. Besides, comprehensive speciation of mercury in incubated cells revealed different detoxification mechanisms of Hg(2+) and MeHg(+) in Hg(2+) or MeHg(+) incubated HepG2 cells.

  5. Determination of total mercury for marine environmental monitoring studies by solid sampling continuum source high resolution atomic absorption spectrometry

    NASA Astrophysics Data System (ADS)

    Mandjukov, Petko; Orani, Anna Maria; Han, Eunmi; Vassileva, Emilia

    2015-01-01

    The most critical step in almost all commonly used analytical procedures for Hg determination is the sample preparation due to its extreme volatility. One of the possible solutions of this problem is the application of methods for direct analysis of solid samples. The possibilities for solid sampling high resolution continuum source atomic absorption spectrometry (HR CS AAS) determination of total mercury in various marine environmental samples e.g. sediments and biota are object of the present study. The instrumental parameters were optimized in order to obtain reproducible and interference free analytical signal. A calibration technique based on the use of solid standard certified reference materials similar to the nature of the analyzed sample was developed and applied to various CRMs and real samples. This technique allows simple and reliable evaluation of the uncertainty of the result and the metrological characteristics of the method. A validation approach in line with the requirements of ISO 17025 standard and Eurachem guidelines was followed. With this in mind, selectivity, working range (0.06 to 25 ng for biota and 0.025 to 4 ng for sediment samples, expressed as total Hg) linearity (confirmed by Student's t-test), bias (1.6-4.3%), repeatability (4-9%), reproducibility (9-11%), and absolute limit of detection (0.025 ng for sediment, 0.096 ng for marine biota) were systematically assessed using solid CRMs. The relative expanded uncertainty was estimated at 15% for sediment sample and 8.5% for marine biota sample (k = 2). Demonstration of traceability of measurement results is also presented. The potential of the proposed analytical procedure, based on solid sampling HR CS AAS technique was demonstrated by direct analysis of sea sediments form the Caribbean region and various CRMs. Overall, the use of solid sampling HR CS AAS permits obtaining significant advantages for the determination of this complex analyte in marine samples, such as straightforward

  6. River loads of suspended solids, nitrogen, phosphorus and herbicides delivered to the Great Barrier Reef lagoon.

    PubMed

    Kroon, Frederieke J; Kuhnert, Petra M; Henderson, Brent L; Wilkinson, Scott N; Kinsey-Henderson, Anne; Abbott, Brett; Brodie, Jon E; Turner, Ryan D R

    2012-01-01

    Degradation of coastal ecosystems in the Great Barrier Reef (GBR) lagoon, Australia, has been linked with increased land-based runoff of suspended solids, nutrients and pesticides since European settlement. This study estimated the increase in river loads for all 35 GBR basins, using the best available estimates of pre-European and current loads derived from catchment modelling and monitoring. The mean-annual load to the GBR lagoon for (i) total suspended solids has increased by 5.5 times to 17,000ktonnes/year, (ii) total nitrogen by 5.7 times to 80,000tonnes/year, (iii) total phosphorus by 8.9 times to 16,000tonnes/year, and (iv) PSII herbicides is 30,000kg/year. The increases in river loads differ across the 10 pollutants and 35 basins examined, reflecting differences in surface runoff, urbanisation, deforestation, agricultural practices, mining and retention by reservoirs. These estimates will facilitate target setting for water quality and desired ecosystem states, and enable prioritisation of critical sources for management. PMID:22154273

  7. Silymarin-loaded solid nanoparticles provide excellent hepatic protection: physicochemical characterization and in vivo evaluation

    PubMed Central

    Yang, Kwan Yeol; Hwang, Du Hyeong; Yousaf, Abid Mehmood; Kim, Dong Wuk; Shin, Young-Jun; Bae, Ok-Nam; Kim, Yong-II; Kim, Jong Oh; Yong, Chul Soon; Choi, Han-Gon

    2013-01-01

    Background The purpose of this study was to develop a novel silymarin-loaded solid nanoparticle system with enhanced oral bioavailability and an ability to provide excellent hepatic protection for poorly water-soluble drugs using Shirasu porous glass (SPG) membrane emulsification and a spray-drying technique. Methods A silymarin-loaded liquid nanoemulsion was formulated by applying the SPG membrane emulsification technique. This was further converted into solid state nanosized particles by the spray-drying technique. The physicochemical characteristics of these nanoparticles were determined by scanning electron microscopy, differential scanning calorimetry, and powder X-ray diffraction. Their dissolution, bioavailability, and hepatoprotective activity in rats were assessed by comparison with a commercially available silymarin-loaded product. Results Formulation of a silymarin-loaded nanoemulsion, comprising silymarin, castor oil, polyvinylpyrrolidone, Transcutol HP, Tween 80, and water at a weight ratio of 5/3/3/1.25/1.25/100 was accomplished using an SPG membrane emulsification technique at an agitator speed of 700 rpm, a feed pressure of 15 kPa, and a continuous phase temperature of 25°C. This resulted in generation of comparatively uniform emulsion globules with a narrow size distribution. Moreover, the silymarin-loaded solid nanoparticles, containing silymarin/castor oil/polyvinylpyrrolidone/Transcutol HP/Tween 80 at a weight ratio of 5/3/3/1.25/1.25, improved about 1,300-fold drug solubility and retained a mean size of about 210 nm. Silymarin was located in unaltered crystalline form in the nanoparticles. The drug dissolved rapidly from the nanoparticles, reaching nearly 80% within 15 minutes, indicating three-fold better dissolution than that of the commercial product. Further, the nanoparticles showed a considerably shorter time to peak concentration, a greater area under the concentration-time curve, and a higher maximum concentration of silymarin compared

  8. Variability of solid load in the proglacial Fagge River, Tyrol (Austria)

    NASA Astrophysics Data System (ADS)

    Baewert, Henning; Weber, Martin; Faust, Matthias; Morche, David

    2016-04-01

    Glaciers can strongly affect sediment dynamics in high-mountain basins. They receive clastic material from rock walls by gravitational processes of various magnitudes (rock slides to rockfalls) or by subglacial erosion and transport sediments downvalley like a conveyor belt. At the glacier tongue the meltwater with its accompanying river load enters the proglacial system. Fine material is moving in suspension leading to turbid meltwater. The coarse fraction of the meltwater load is rolling or sliding as bedload on the proglacial channel bed. As glaciers are vulnerable to and thus indicators of climate change the sediment transfer systems in Alpine glacier basins will respond as well. Since the end of the Little Ice Age (LIA) around 1850 glacier in the European Alps have been melting down and their front lines have been retreating. Where the glacier ice is gone large amounts unconsolidated sediments are deposited (moraines, glaciofluvial deposits) and can easily be reworked during subsequent rain storms or snowmelt. As a consequence it is of great concern whether more solid load (higher sediment availability) or less solid load (trapping effect of proglacial lakes) is transported in proglacial rivers in the near future. Due to glacier retreat the amount of unconsolidated, sparsely vegetated sediments, which are prone to rapid remobilization, is increasing. Because more of these sediments are available for fluvial sediment transport, it is generally assumed that glacier retreat leads to an increase in sediment discharge from proglacial zones. The main objective of this study is to present a budget of the fluvial sediment transport within the proglacial Fagge River for the observation period 2012 - 2014. This quantification of solid sediment transport is needed for further investigations on the way to a holistic sediment budget for the whole glaciated catchment of the Gepatschferner in Tyrol/Austria.

  9. Treatability study for removal of leachable mercury in crushed fluorescent lamps

    SciTech Connect

    Bostick, W.D.; Beck, D.E.; Bowser, K.T.

    1996-02-01

    Nonserviceable fluorescent lamps removed from radiological control areas at the Oak Ridge Department of Energy facilities have been crushed and are currently managed as mixed waste (hazardous and radiologically contaminated). We present proposed treatment flowsheets and supporting treatability study data for conditioning this solid waste residue so that it can qualify for disposal in a sanitary landfill. Mercury in spent fluorescent lamps occurs primarily as condensate on high-surface-area phosphor material. It can be solubilized with excess oxidants (e.g., hypochlorite solution) and stabilized by complexation with halide ions. Soluble mercury in dechlorinated saline solution is effectively removed by cementation with zero-valent iron in the form of steel wool. In packed column dynamic flow testing, soluble mercury was reduced to mercury metal and insoluble calomel, loading > 1.2 g of mercury per grain of steel wool before an appreciable breakthrough of soluble mercury in the effluent.

  10. Nanogold-Decorated Silica Monoliths as Highly Efficient Solid-Phase Adsorbent for Ultratrace Mercury Analysis in Natural Waters.

    PubMed

    Huber, Jessica; Heimbürger, Lars-Eric; Sonke, Jeroen E; Ziller, Sebastian; Lindén, Mika; Leopold, Kerstin

    2015-11-01

    We propose a novel analytical method for mercury (Hg) trace determination based on direct Hg preconcentration from aqueous solution onto a gold nanoparticle-decorated silica monolith (AuNP@SiO2). Detection of Hg is performed after thermal desorption by means of atomic fluorescence spectrometry. This new methodology benefits from reagent-free, time- and cost-saving procedure, due to most efficient solid-phase adsorbent and results in high sensitive quantification. The excellent analytical performance of the whole procedure is demonstrated by a limit of detection as low as 1.31 ng L(-1) for only one-min accumulation duration. A good reproducibility with standard deviations ≤5.4% is given. The feasibility of the approach in natural waters was confirmed by a recovery experiment in spiked seawater with a recovery rate of 101%. Moreover, the presented method was validated through reference analysis of a submarine groundwater discharge sample by cold vapor-atomic fluorescence spectrometry resulting in a very good agreement of the found values. Hence the novel method is a very promising new tool for low-level Hg monitoring in natural waters providing easy-handling on-site preconcentration, reagent-free stabilization as well as reagent-free, highly sensitive detection.

  11. Detoxification of a highly toxic lead-loaded industrial solid waste by stabilization using apatites.

    PubMed

    Ioannidis, T A; Zouboulis, A I

    2003-02-28

    Apatites are known for their properties to immobilize lead contained in aqueous solutions or contaminated soils. In this study, apatites were examined as stabilization additives for lead-loaded industrial solid toxic wastes. The specific waste was the residue, obtained after thermal treatment of sludges (incineration), which was derived from tetraethyl lead fuel storage tanks. It was found to contain around 30 wt.% lead and 33 wt.% iron. Standard leaching tests (according to DIN 38414 S-4) were applied for the determination of leachability of metals from the ash and, thus, of chemical toxicity; the proposed leaching tests examined both initial and stabilized products in order to evaluate the effectiveness of the applied additives. The results obtained demonstrate the fact that lead concentrations in leachates, after the application of the proposed leaching tests using apatites as additives and with a ratio of 50% solid waste-50 wt.% apatite, could be reduced to the range of 1mg/l.

  12. Problems of Solid-Phase Synthesis in Cylindrical Ampoules under Explosive Loading

    NASA Astrophysics Data System (ADS)

    Zelepugin, S. A.; Ivanova, O. V.; Yunoshev, A. S.; Zelepugin, A. S.

    2016-04-01

    The peculiarities of solid-phase synthesis are studied experimentally and numerically in the aluminum-fluoroplastic and aluminum-sulfur mixtures in cylindrical ampoules under explosive loading. The experimental results show that the use of a mixture capable of ultrafast exothermic reactions leads to the destruction of a cylindrical ampoule under explosive loading. When the transient shock wave is reflected from the bottom lid of the ampoule as a compression wave, there is a sharp increase in pressure in the lower part of the ampoule, which is accompanied by the increase in rate of the chemical reaction. The high rate of heat release during the chemical reaction in the lower part of the ampoule causes the formation of a gas phase, which leads to a further increase in pressure and destruction of the ampoule.

  13. Origin of compression-induced failure in brittle solids under shock loading

    NASA Astrophysics Data System (ADS)

    Huang, J. Y.; Li, Y.; Liu, Q. C.; Zhou, X. M.; Liu, L. W.; Liu, C. L.; Zhu, M. H.; Luo, S. N.

    2015-10-01

    The origin of compression-induced failure in brittle solids has been a subject of debate. Using in situ, high-speed, strain field mapping of a representative material, polymethylmethacrylate, we reveal that shock loading leads to heterogeneity in a compressive strain field, which in turn gives rise to localized lateral tension and shear through Poisson's effects, and, subsequently, localized microdamage. A failure wave nucleates from the impact surface and its propagation into the microdamage zone is self-sustained, triggering interior failure. Its velocity increases with increasing shock strength and eventually approaches the shock velocity. The seemingly puzzling phenomena observed in previous experiments, including incubation time, failure wave velocity variations, and surface roughness effects, can all be explained consistently with the nucleation and growth of the microdamage, and the effects of loading strength and preexisting defects.

  14. Amsacrine analog-loaded solid lipid nanoparticle to resolve insolubility for injection delivery: characterization and pharmacokinetics

    PubMed Central

    Fang, Yi-Ping; Chuang, Chih-Hung; Wu, Pao-Chu; Huang, Yaw-Bin; Tzeng, Cherng-Chyi; Chen, Yeh-Long; Liu, Ya-Ting; Tsai, Yi-Hung; Tsai, Ming-Jun

    2016-01-01

    Amsacrine analog is a novel chemotherapeutic agent that provides potentially broad antitumor activity when compared to traditional amsacrine. However, the major limitation of amsacrine analog is that it is highly lipophilic, making it nonconductive to intravenous administration. The aim of this study was to utilize solid lipid nanoparticles (SLN) to resolve the delivery problem and to investigate the biodistribution of amsacrine analog-loaded SLN. Physicochemical characterizations of SLN, including particle size, zeta potential, entrapment efficiency, and stability, were evaluated. In vitro release behavior was also measured by the dialysis method. In vivo pharmacokinetics and biodistribution behavior of amsacrine analog were investigated and incorporated with a non invasion in vivo imaging system to confirm the localization of SLN. The results showed that amsacrine analog-loaded SLN was 36.7 nm in particle size, 0.37 in polydispersity index, and 34.5±0.047 mV in zeta potential. More than 99% of amsacrine analog was successfully entrapped in the SLN. There were no significant differences in the physicochemical properties after storage at room temperature (25°C) for 1 month. Amsacrine analog-loaded SLN maintained good stability. An in vitro release study showed that amsacrine analog-loaded SLN sustained a release pattern and followed the zero equation. An in vivo pharmacokinetics study showed that amsacrine analog was rapidly distributed from the central compartment to the tissue compartments after intravenous delivery of amsacrine analog-loaded SLN. The biodistribution behavior demonstrated that amsacrine analog mainly accumulated in the lungs. Noninvasion in vivo imaging system images also confirmed that the drug distribution was predominantly localized in the lungs when IR-780-loaded SLN was used. PMID:27019595

  15. Sugar loss and enzyme inhibition due to oligosaccharide accumulation during high solids-loading enzymatic hydrolysis

    DOE PAGES

    Xue, Saisi; Uppugundla, Nirmal; Bowman, Michael J.; Cavalier, David; Da Costa Sousa, Leonardo; Dale, Bruce E.; Balan, Venkatesh

    2015-11-26

    Accumulation of recalcitrant oligosaccharides during high-solids loading enzymatic hydrolysis of cellulosic biomass reduces biofuel yields and increases processing costs for a cellulosic biorefinery. Recalcitrant oligosaccharides in AFEX-pretreated corn stover hydrolysate accumulate to the extent of about 18–25 % of the total soluble sugars in the hydrolysate and 12–18 % of the total polysaccharides in the inlet biomass (untreated), equivalent to a yield loss of about 7–9 kg of monomeric sugars per 100 kg of inlet dry biomass (untreated). These oligosaccharides represent a yield loss and also inhibit commercial hydrolytic enzymes, with both being serious bottlenecks for economical biofuel production frommore » cellulosic biomass. Very little is understood about the nature of these oligomers and why they are recalcitrant to commercial enzymes. This work presents a robust method for separating recalcitrant oligosaccharides from high solid loading hydrolysate in gramme quantities. Composition analysis, recalcitrance study and enzyme inhibition study were performed to understand their chemical nature. Results indicate that, oligosaccharide accumulation occurs during high solid loading enzymatic hydrolysis of corn stover (CS) irrespective of using different pretreated corn stover (dilute acid: DA, ionic liquids: IL, and ammonia fibre expansion: AFEX). The methodology for large-scale separation of recalcitrant oligosaccharides from 25 % solids-loading AFEXcorn stover hydrolysate using charcoal fractionation and size exclusion chromatography is reported for the first time. Oligosaccharides with higher degree of polymerization (DP) were recalcitrant towards commercial enzyme mixtures [Ctec2, Htec2 and Multifect pectinase (MP)] compared to lower DP oligosaccharides. Enzyme inhibition studies using processed substrates (Avicel and xylan) showed that low DP oligosaccharides also inhibit commercial enzymes. Addition of monomeric sugars to oligosaccharides increases the

  16. Sugar loss and enzyme inhibition due to oligosaccharide accumulation during high solids-loading enzymatic hydrolysis

    SciTech Connect

    Xue, Saisi; Uppugundla, Nirmal; Bowman, Michael J.; Cavalier, David; Da Costa Sousa, Leonardo; Dale, Bruce E.; Balan, Venkatesh

    2015-11-26

    Accumulation of recalcitrant oligosaccharides during high-solids loading enzymatic hydrolysis of cellulosic biomass reduces biofuel yields and increases processing costs for a cellulosic biorefinery. Recalcitrant oligosaccharides in AFEX-pretreated corn stover hydrolysate accumulate to the extent of about 18–25 % of the total soluble sugars in the hydrolysate and 12–18 % of the total polysaccharides in the inlet biomass (untreated), equivalent to a yield loss of about 7–9 kg of monomeric sugars per 100 kg of inlet dry biomass (untreated). These oligosaccharides represent a yield loss and also inhibit commercial hydrolytic enzymes, with both being serious bottlenecks for economical biofuel production from cellulosic biomass. Very little is understood about the nature of these oligomers and why they are recalcitrant to commercial enzymes. This work presents a robust method for separating recalcitrant oligosaccharides from high solid loading hydrolysate in gramme quantities. Composition analysis, recalcitrance study and enzyme inhibition study were performed to understand their chemical nature. Results indicate that, oligosaccharide accumulation occurs during high solid loading enzymatic hydrolysis of corn stover (CS) irrespective of using different pretreated corn stover (dilute acid: DA, ionic liquids: IL, and ammonia fibre expansion: AFEX). The methodology for large-scale separation of recalcitrant oligosaccharides from 25 % solids-loading AFEXcorn stover hydrolysate using charcoal fractionation and size exclusion chromatography is reported for the first time. Oligosaccharides with higher degree of polymerization (DP) were recalcitrant towards commercial enzyme mixtures [Ctec2, Htec2 and Multifect pectinase (MP)] compared to lower DP oligosaccharides. Enzyme inhibition studies using processed substrates (Avicel and xylan) showed that low DP oligosaccharides also inhibit commercial enzymes. Addition of monomeric sugars to oligosaccharides increases the

  17. A nonlinear solid shell element formulation for analysis of composite panels under blast wave pressure loading

    NASA Astrophysics Data System (ADS)

    Park, Hun

    A comprehensive methodology to accurately predict the dynamic response of composite panels under blast wave pressure loading has been successfully developed for the first time. It includes the modeling of geometrically nonlinear dynamic effect, progressive failure and strain-rate effect on constitutive equation and strength. For dynamic analysis, a nonlinear solid shell element formulation is combined with the trapezoidal rule for numerical integration in time. The progressive damage incorporates the effect of the material failure, such as fiber failure, matrix cracking and fiber-matrix shearing failure on the stiffness and strength. Material degradation models based on the rule of mixtures are proposed for each failure mode. To implement the strain-rate effect on the constitutive equation of the material, a viscoplastic model is adopted. In this model, three material parameters are determined by conducting uniaxial tension tests on off-axis specimen. The effect of strain rates on material strength is implemented via the linear least square fit of the test data. A key ingredient of the analysis is a geometrically nonlinear solid shell element based on the assumed strain formulation to alleviate element locking. In this approach, the composite shell is treated as a three-dimensional solid. Accordingly, the change of shell thickness is allowed and the kinematics of deformation is described by six vector components at a point on the shell midsurface. The mass matrix always remains constant during the analysis. Example problems under static and dynamic loadings are solved to investigate the behavior of composite panels undergoing large deformation while experiencing material damage. The analysis results are compared with the test data available. Results of the numerical analysis show that the effect of the progressive failure and strain-rates on structural responses are considerable. For a composite plate under static pressure loadings, maximum displacement and

  18. Subtask 2.7 -- Mercury capture on solid surfaces and aerosols. Semi-annual report, July 1--December 31, 1996

    SciTech Connect

    Schultz, R.L.

    1997-08-01

    Determining the fly ash properties responsible for the capture of mercury in coal-fired power generation systems is key to understanding and controlling mercury emissions in these systems. Several capture mechanisms and interactions may be possible, such as condensation, chemical adsorption, physical adsorption, chemical bonding, and amalgamation. The chemical nature of the exposed surfaces and the amount of surface area are likely to affect the amount of mercury capture, so both of these parameters must be explored. Since much of the fly ash surface area is concentrated on submicron particles, the interaction of mercury with submicron particles needs to be evaluated. Another possible explanation of mercury capture on fly ash is the formation of amalgams with other metal species that may be present in the fly ash; if this is true, amalgamation may be a viable control technology. The project objectives are to relate mercury capture by fly ash to chemical and physical properties of the fly ash, determine mercury associations with submicron aerosols, evaluate mercury capture on metal sorbents, and relate experimental results to predictions based on state-of-the-art models. Results to date on these activities are described.

  19. Consolidated bioprocessing (CBP) of AFEX™-pretreated corn stover for ethanol production using Clostridium phytofermentans at a high solids loading.

    PubMed

    Jin, Mingjie; Gunawan, Christa; Balan, Venkatesh; Dale, Bruce E

    2012-08-01

    Consolidated bioprocessing (CBP) using Clostridium phytofermentans (ATCC 700394) on ammonia fiber expansion (AFEX™)-treated corn stover (AFEX™-CS) at a low solids loading showed promising results [Jin et al. (2011) Biotechnol Bioeng 108(6): 1290-1297]. However, industrial relevant process requires high solids loading. Therefore, we studied high solids loading CBP performance on AFEX™-CS. The factors potentially affecting the performance including solids loading, CBP products acetate and ethanol, and degradation products resulting from pretreatment were investigated. At 4% (w/w) glucan loading, C. phytofermentans performed well on AFEX™-CS with no nutrients supplementation and reached similar sugar conversions as a fermentation with nutrients supplementation. A glucan conversion of 48.9% and a xylan conversion of 77.9% were achieved after 264 h with 7.0 g/L ethanol and 8.8 g/L acetate produced. Relatively high concentrations of acetate produced at high solids loading was found to be the major factor limiting the CBP performance. Degradation products in AFEX™-CS helped enhance ethanol production.

  20. Preparation and characterization of catalase-loaded solid lipid nanoparticles protecting enzyme against proteolysis.

    PubMed

    Qi, Ce; Chen, Yan; Jing, Qing-Zhe; Wang, Xing-Guo

    2011-01-01

    Catalase-loaded solid lipid nanoparticles (SLNs) were prepared by the double emulsion method (w/o/w) and solvent evaporation techniques, using acetone/methylene chloride (1:1) as an organic solvent, lecithin and triglyceride as oil phase and Poloxmer 188 as a surfactant. The optimized SLN was prepared by lecithin: triglyceride ratio (5%), 20-second + 30-second sonication, and 2% Poloxmer 188. The mean particle size of SLN was 296.0 ± 7.0 nm, polydispersity index range and zeta potential were 0.322-0.354 and -36.4 ± 0.6, respectively, and the encapsulation efficiency reached its maximum of 77.9 ± 1.56. Catalase distributed between the solid lipid and inner aqueous phase and gradually released from Poloxmer coated SLNs up to 20% within 20 h. Catalase-loaded SLN remained at 30% of H(2)O(2)-degrading activity after being incubated with Proteinase K for 24 h, while free catalase lost activity within 1 h.

  1. Metal-solid interactions controlling the bioavailability of mercury from sediments to clams and sipunculans.

    PubMed

    Zhong, Huan; Wang, Wen-Xiong

    2006-06-15

    The bioavailability of sedimentary Hg(II) and methylmercury (MeHg) was quantified by measuring the assimilation efficiency (AE) in the clam Ruditapes philippinarum and the extraction of the gut juices from the sipunculan Sipunculus nudus. Three factors (Hg concentration in sediment, Hg sediment contact time, and organic content of sediments) were modified to examine metal-solid interactions in controlling Hg bioavailability. The Hg AEs in the clams were strongly correlated with the extraction from the sipunculan gut juices for both Hg species. The bioavailability of both Hg(II) and MeHg generally increased with increased sediment Hg concentration but decreased with sedimentmetal contact time and increasing organic content (except that MeHg was not influenced by organic content). Hg(II) speciation in sediments, quantified by sequential chemical extraction (SCE), was dependent on geochemical conditions and greatly controlled the mobility and bioavailability of Hg(II) in sediments. Most bioavailable Hg(II) originated from the strongly complexed phase (e.g., Hg bound up in Fe/Mn oxide, amorphous organosulfur, or mineral lattice), whereas Hg bound with the organocomplexed phase (Hg humic and Hg2Cl2) was not bioavailable. Hg bound with the other geochemical phases (water soluble, HgO, HgSO4, and HgS) contributed very little to the bioavailable Hg due to their low partitionings. Further, the amount of bioavailable Hg was inversely related to the particle reactivity of Hg with the sediments. Detailed analyses of metal-solid interactions provide a better understanding of how Hg in sediments can predict Hg concentration and therefore bioavailability in benthic invertebrates.

  2. Solid Lipid Nanoparticles Loaded with Retinoic Acid and Lauric Acid as an Alternative for Topical Treatment of Acne Vulgaris.

    PubMed

    Silva, Elton Luiz; Carneiro, Guilherme; De Araújo, Lidiane Advíncula; Trindade, Mariana de Jesus Vaz; Yoshida, Maria Irene; Oréfice, Rodrigo Lambert; Farias, Luis de Macêdo; De Carvalho, Maria Auxiliadora Roque; Dos Santos, Simone Gonçalves; Goulart, Gisele Assis Castro; Alves, Ricardo José; Ferreira, Lucas Antônio Miranda

    2015-01-01

    Topical therapy is the first choice for the treatment of mild to moderate acne and all-trans retinoic acid is one of the most used drugs. The combination of retinoids and antimicrobials is an innovative approach for acne therapy. Recently, lauric acid, a saturated fatty acid, has shown strong antimicrobial activity against Propionibacterium acnes. However, topical application of retinoic acid is followed by high incidence of side-effects, including erythema and irritation. Solid lipid nanoparticles represent an alternative to overcome these side-effects. This work aims to develop solid lipid nanoparticles loaded with retinoic acid and lauric acid and evaluate their antibacterial activity. The influence of lipophilic stearylamine on the characteristics of solid lipid nanoparticles was investigated. Solid lipid nanoparticles were characterized for size, zeta potential, encapsulation efficiency, differential scanning calorimetry and X-ray diffraction. The in vitro inhibitory activity of retinoic acid-lauric acid-loaded solid lipid nanoparticles was evaluated against Propionibacterium acnes, Staphylococcus aureus and Staphylococcus epidermidis. High encapsulation efficiency was obtained at initial time (94 ± 7% and 100 ± 4% for retinoic acid and lauric acid, respectively) and it was demonstrated that lauric acid-loaded-solid lipid nanoparticles provided the incorporation of retinoic acid. However, the presence of stearylamine is necessary to ensure stability of encapsulation. Moreover, retinoic acid-lauric acid-loaded solid lipid nanoparticles showed growth inhibitory activity against Staphylococcus epidermidis, Propionibacterium acnes and Staphylococcus aureus, representing an interesting alternative for the topical therapy of acne vulgaris. PMID:26328443

  3. Time series Of suspended-solids concentration, salinity, temperature, and total mercury concentration in San Francisco Bay during water year 1996

    USGS Publications Warehouse

    Schoellhamer, David H.

    1998-01-01

    Many physical processes affect how constituents within San Francisco Bay vary. Processes and their associated time scales include turbulence (seconds), semidiurnal and diurnal tides (hours), the spring-neap tidal cycle (days), freshwater flow (weeks), seasonal winds (months), ecological and climatic changes (years), and geologic changes (thousands of years). The effect and relative importance of physical processes on the Bay can be determined from continuous time series of suspended-solids concentration (SSC), salinity, and water temperature. SSC time series and Regional Monitoring Program (RMP) waterquality data can be used to calculate time series of some trace-element concentrations (Schoellhamer, 1997). The purpose of this chapter is to qualitatively describe time series of SSC, salinity, water temperature, and mercury during water year 1996 (October 1995 through September 1996). In addition, a calculated time series of mercury will be used to evaluate the accuracy of using instantaneous water samples to evaluate a 4-day average water-quality objective.

  4. Simultaneous saccharification and fermentation of Kanlow switchgrass by thermotolerant Kluyveromyces marxianus IMB3: the effect of enzyme loading, temperature and higher solid loadings.

    PubMed

    Pessani, Naveen K; Atiyeh, Hasan K; Wilkins, Mark R; Bellmer, Danielle D; Banat, Ibrahim M

    2011-11-01

    Switchgrass (Panicum virgatum) was subjected to hydrothermolysis pretreatment and then used to study the effect of enzyme loading and temperature in a simultaneous saccharification and fermentation (SSF) with the thermotolerant yeast strain Kluyveromyces marxianus IMB3 at 8% solid loading. Various loadings of Accellerase 1500 between 0.1 and 1.1 mL g(-1) glucan were tested in SSF at 45 °C (activity of enzyme was 82.2 FPU mL(-1)). The optimum enzyme loading was 0.7 mL g(-1) glucan based on the six different enzyme loadings tested. SSFs were performed at 37, 41 and 45 °C with an enzyme loading of 0.7 mL g(-1) glucan. The highest ethanol concentration of 22.5 g L(-1) was obtained after 168 h with SSF at 45 °C, which was equivalent to 86% yield. Four different batch and fed-batch strategies were evaluated using a total solid loading of 12% (dry basis). About 32 g L(-1) ethanol was produced with the four strategies, which was equivalent to 82% yield.

  5. Solid State Reaction of Thin Metal Films with MERCURY(1-X)CADMIUM(X)TELLURIDE.

    NASA Astrophysics Data System (ADS)

    Ehsani, Hassan

    The solid state reactions of both e-beam evaporation and sputter deposition of thin layers of Cu, Co, and Ni onto CdTe and Hg_{0.8}Cd _{0.2}Te have been investigated using Transmission Electron Microscopy and Auger Electron Spectroscopy. For a Cu overlayer deposited by either method on CdTe(111) and Hg_{0.8}Cd _{0.2}Te substrates, we observed formation of a relatively thick region of Cu _{rm 2-x}Te (superlattice structure), even though the heat of reactions ( DeltaH_{rm R} ) are positive as calculated using bulk parameters. Deposition of Co onto Hg_{0.8 }Cd_{0.2}Te substrates reacted to form the gamma -phase (Co_3Te_4) at room temperature in the case of deposition by sputtering, and at 150^circC annealing temperature in the case of deposition by e-beam evaporation. This compound was stable at room and elevated temperatures (100 ^circC, 200^ circC, 300^circC, and 400^circC). On the other hand Co did not react with CdTe (at temperature less than 300^circC) instead, generation of Te was observed. The Te generated in the case of sputter deposition and fast deposition (8-10A) e-beam evaporation was polycrystalline whereas, in the case of slow deposition (0.3-0.5A) e-beam evaporation it was amorphous. Auger depth profile indicated that the amount of excess Te in the case of sputter deposition was larger in compared with deposition by e-beam evaporation. The excess Te was distributed throughout the Co film. The results of Ni deposited onto Hg_ {0.8}Cd_{0.2} Te or CdTe substrate were somewhat similar to the Co cases. Ni reacted with Hg_{0.8 }Cd_{0.2}Te at room temperature in either deposition system to form the delta-phase (NiTe-Ni _2Te). From the results of this work it is clear that the solid produced as a result of either e-beam or sputter deposition has a higher free energy than that of a metal layer on contact with the substrate. This result indicates importance of kinetics in the formation of the interface structure of metals deposited on Hg_{0.8 }Cd_{0.2}Te

  6. Advances in solid polymer electrolyte fuel cell technology with low-platinum-loading electrodes

    NASA Technical Reports Server (NTRS)

    Srinivasan, Supramaniam; Ticianelli, E. A.; Derouin, C. R.; Redondo, A.

    1987-01-01

    The Gemini Space program demonstrated the first major application of fuel cell systems. Solid polymer electrolyte fuel cells were used as auxiliary power sources in the spacecraft. There has been considerable progress in this technology since then, particularly with the substitution of Nafion for the polystyrene sulfonate membrane as the electrolyte. Until recently the performance was good only with high platinum loading (4 mg/sq cm) electrodes. Methods are presented to advance the technology by (1) use of low platinum loading (0.35 mg/sq cm) electrodes; (2) optimization of anode/membrane/cathode interfaces by hot pressing; (3) pressurization of reactant gases, which is most important when air is used as cathodic reactant; and (4) adequate humidification of reactant gases to overcome the water management problem. The high performance of the fuel cell with the low loading of platinum appears to be due to the extension of the three dimensional reaction zone by introduction of a proton conductor, Nafion. This was confirmed by cyclic voltammetry.

  7. α-Tocopherol succinate improves encapsulation and anticancer activity of doxorubicin loaded in solid lipid nanoparticles.

    PubMed

    Oliveira, Mariana S; Mussi, Samuel V; Gomes, Dawidson A; Yoshida, Maria Irene; Frezard, Frederic; Carregal, Virgínia M; Ferreira, Lucas A M

    2016-04-01

    This work aimed to develop solid lipid nanoparticles (SLN) co-loaded with doxorubicin and α-tocopheryl succinate (TS), a succinic acid ester of α-tocopherol that exhibits anticancer actions, evaluating the influence of TS on drug encapsulation efficiency. The SLN were characterized for size, zeta potential, entrapment efficiency (EE), and drug release. Studies of in vitro anticancer activity were also conducted. The EE was significantly improved from 30 ± 1% to 96 ± 2% for SLN without and with TS at 0.4%, respectively. In contrast, a reduction in particle size from 298 ± 1 to 79 ± 1 nm was observed for SLN without and with TS respectively. The doxorubicin release data show that SLN provide a controlled drug release. The in vitro studies showed higher cytotoxicity for doxorubicin-TS-loaded SLN than for free doxorubicin in breast cancer cells. These findings suggest that TS-doxorubicin-loaded SLN is a promising alternative for the treatment of cancer. PMID:26764108

  8. Method for removal and stabilization of mercury in mercury-containing gas streams

    DOEpatents

    Broderick, Thomas E.

    2005-09-13

    The present invention is directed to a process and apparatus for removing and stabilizing mercury from mercury-containing gas streams. A gas stream containing vapor phase elemental and/or speciated mercury is contacted with reagent, such as an oxygen-containing oxidant, in a liquid environment to form a mercury-containing precipitate. The mercury-containing precipitate is kept or placed in solution and reacts with one or more additional reagents to form a solid, stable mercury-containing compound.

  9. Lyophilized sponges loaded with curcumin solid lipid nanoparticles for buccal delivery: Development and characterization.

    PubMed

    Hazzah, Heba A; Farid, Ragwa M; Nasra, Maha M A; El-Massik, Magda A; Abdallah, Ossama Y

    2015-08-15

    This study aimed to prepare and evaluate mucoadhesive sponges as dosage forms for delivering solid lipid nanoparticles. For this purpose curcumin (Cur) was formulated as solid nanoparticles (SLN) using Gelucire 50/13, and polaxomer 407. The prepared CurSLN dispersion was thickened with different mucoadhesive polymers. Different concentrations of glycerol, and mannitol of range (0.25-20%), and (0-1%), respectively were also examined. The formed gel was poured into oblong molds and freeze dried to form mucoadhesive sponge to be applied to the buccal mucosa. The prepared sponges were evaluated for their, in-vivo residence time, in-vitro and in-vivo drug release, and hydration capacity. Surface morphology for the different sponges were examined using SEM. TEM was also carried out for sponge fragments previously dispersed into water. Infrared spectroscopy was conducted to investigate interaction between used ingredients. The results showed that the CurSLN loaded HPMC, and Polycarbophil sponges showed 4, and 15 h in-vivo residence time, respectively, providing a considerable amount of curcumin into saliva. The incorporation of glycerol and mannitol at concentration of 1% provided elegant and flexible sponges. The SEM showed that the deposition of CurSLN differed according to the type of polymer used. TEM confirmed the integrity of liberated CurSLN from sponges. IR spectra showed an interaction between HPMC and poloxamer 407, which affected its behavior as a gelling agent. The obtained results provide an efficient approach for delivering solid lipid nanoparticles in a solid dosage form keeping the nanoparticle characters and integrity.

  10. Mercury speciation in sea food by flow injection cold vapor atomic absorption spectrometry using selective solid phase extraction.

    PubMed

    Vereda Alonso, E; Siles Cordero, M T; García de Torres, A; Cañada Rudner, P; Cano Pavón, J M

    2008-10-19

    An on-line inorganic and organomercury species separation, preconcentration and determination system consisting of cold vapor atomic absorption spectrometry (CV-AAS or CV-ETAAS) coupled to a flow injection (FI) method was studied. The inorganic mercury species was retained on a column (i.d., 3 mm; length 3 cm) packed to a height of 0.7 cm with a chelating resin aminopropyl-controlled pore glass (550 A) functionalized with [1,5-bis (2 pyridyl)-3-sulphophenyl methylene thiocarbonohydrazyde] placed in the injection valve of a simple flow manifold. Methylmercury is not directly determined. Previous oxidation of the organomercurial species permitted the determination of total mercury. The separation of mercury species was obtained by the selective retention of inorganic mercury on the chelating resin. The difference between total and inorganic mercury determined the organomercury content in the sample. The inorganic mercury was removed on-line from the microcolumn with 6% (m/v) thiourea. The mercury cold vapor generation was performed on-line with 0.2% (m/v) sodium tethrahydroborate and 0.05% (m/v) sodium hydroxide as reducing solution. The determination was performed using CV-AAS and CV-ETAAS, both approaches have been used and compared for the speciation of mercury in sea food. A detection limit of 10 and 6 ng l(-1) was achieved for CV-AAS and CV-ETAAS, respectively. The precision for 10 replicate determinations at the 1 microg l(-1) Hg level was 3.5% relative standard deviation (R.S.D.), calculated from the peak heights obtained. Both approaches were validated with the use of two certified reference materials and by spiking experiments. By analyzing the two biological certified materials, it was evident that the difference between the total mercury and inorganic mercury corresponds to methylmercury. The concentrations obtained by both techniques were in agreement with the certified values or with differences of the certified values for total Hg(2+) and CH(3)Hg

  11. Formulation and optimization of raloxifene-loaded solid lipid nanoparticles to enhance oral bioavailability.

    PubMed

    Tran, Tuan Hiep; Ramasamy, Thiruganesh; Cho, Hyuk Jun; Kim, Yong Il; Poudel, Bijay Kumar; Choi, Han-Gon; Yong, Chul Soon; Kim, Jong Oh

    2014-07-01

    The main aim of this study was to improve the oral bioavailability of raloxifene (RXF), a selective estrogen receptor modulator, by incorporation into solid lipid nanoparticles (SLN). RXF-loaded SLN was prepared by homogenization-sonication technique and characterized through physicochemical, pharmacokinetic, and cytotoxicity studies. The optimized SLN formulation exhibited a spherical shape with average size around 140 nm, easing its transport across the lymphatic system. Augmentation in the profiles of C(max) (308%) and AUC (270%) indicated a significant enhancement in the rate and extent of bioavailability by SLN formulations compared to free drug. In vitro cytotoxicity study performed in NIH-3T3 cells revealed that RXF-SLN was cytocompatible, and SLN remained unchanged during the freeze-drying process. Furthermore, the optimized formulation was quite stable at room temperature for more than two months, exemplifying its superior performance. In conclusion, SLN provides a promising platform for the pronounced enhancement of RXF bioavailability. PMID:24757949

  12. Effect of hydroxypropylcellulose and Tween 80 on physicochemical properties and bioavailability of ezetimibe-loaded solid dispersion.

    PubMed

    Rashid, Rehmana; Kim, Dong Wuk; Din, Fakhar Ud; Mustapha, Omer; Yousaf, Abid Mehmood; Park, Jong Hyuck; Kim, Jong Oh; Yong, Chul Soon; Choi, Han-Gon

    2015-10-01

    The purpose of this research was to evaluate the effect of the HPC (hydroxypropylcellulose) and Tween 80 on the physicochemical properties and oral bioavailability of ezetimibe-loaded solid dispersions. The binary solid dispersions were prepared with drug and various amounts of HPC. Likewise, ternary solid dispersions were prepared with different ratios of drug, HPC and Tween 80. Both types of solid dispersions were prepared using the solvent evaporation method. Their aqueous solubility, physicochemical properties, dissolution and oral bioavailability were investigated in comparison with the drug powder. All the solid dispersions significantly improved the drug solubility and dissolution. As the amount of HPC increased in the binary solid dispersions to 10-fold, the drug solubility and dissolution were increased accordingly. However, further increase in HPC did not result in significant differences among them. Similarly, up to 0.1-fold, Tween 80 increased the drug solubility in the ternary solid dispersions followed by no significant change. However, Tween 80 hardly affected the drug dissolution. The physicochemical analysis proved that the drug in binary and ternary solid dispersion was existed in the amorphous form. The particle-size measurements of these formulations were also not significantly different from each other, which showed that Tween 80 had no impact on physicochemical properties. The ezetimibe-loaded binary and ternary solid dispersions gave 1.6- and 1.8-fold increased oral bioavailability in rats, respectively, as compared to the drug powder; however, these values were not significantly different from each other. Thus, HPC greatly affected the solubility, dissolution and oral bioavailability of drug, but Tween 80 hardly did. Furthermore, this ezetimibe-loaded binary solid dispersion prepared only with HPC would be suggested as a potential formulation for oral administration of ezetimibe.

  13. Laser-ablated loading of solid target through foams of overcritical density

    SciTech Connect

    De Angelis, R. Consoli, F.; Andreoli, P.; Cristofari, G.; Di Giorgio, G.; Gus'kov, S. Yu.; Rupasov, A. A.

    2015-07-15

    The main objective of the work is to study the conversion of the laser pulse energy into the energy of the hydrodynamic motion of matter in a solid target following the initial absorption of laser radiation in a layer of porous material. Results of experiments on plane massive aluminum targets, coated with a layer of porous plastic with density greater than the critical density of the plasma created, are presented. Experiments were carried out on the laser installation ABC of the Research Center ENEA-Frascati; the targets were irradiated by a beam of the fundamental harmonic of Nd-laser radiation with an energy of about 50 kJ, intensity of 10{sup 13 }W/cm{sup 2}, and 3 ns duration. The experimental method consisted in measuring the volume of the craters created on the aluminum surface behind various thicknesses and densities of the porous absorber of laser radiation. On the basis of these measurements and of an advanced analytical model, quantitative conclusions are made on how the efficiency of laser energy transfer to the solid part of the target (laser-ablated loading) depends on thickness and density of the porous absorber.

  14. Laser-ablated loading of solid target through foams of overcritical density

    NASA Astrophysics Data System (ADS)

    De Angelis, R.; Consoli, F.; Gus'kov, S. Yu.; Rupasov, A. A.; Andreoli, P.; Cristofari, G.; Di Giorgio, G.

    2015-07-01

    The main objective of the work is to study the conversion of the laser pulse energy into the energy of the hydrodynamic motion of matter in a solid target following the initial absorption of laser radiation in a layer of porous material. Results of experiments on plane massive aluminum targets, coated with a layer of porous plastic with density greater than the critical density of the plasma created, are presented. Experiments were carried out on the laser installation ABC of the Research Center ENEA-Frascati; the targets were irradiated by a beam of the fundamental harmonic of Nd-laser radiation with an energy of about 50 kJ, intensity of 1013 W/cm2, and 3 ns duration. The experimental method consisted in measuring the volume of the craters created on the aluminum surface behind various thicknesses and densities of the porous absorber of laser radiation. On the basis of these measurements and of an advanced analytical model, quantitative conclusions are made on how the efficiency of laser energy transfer to the solid part of the target (laser-ablated loading) depends on thickness and density of the porous absorber.

  15. SN-38-loaded nanofiber matrices for local control of pediatric solid tumors after subtotal resection surgery.

    PubMed

    Monterrubio, Carles; Pascual-Pasto, Guillem; Cano, Francisco; Vila-Ubach, Monica; Manzanares, Alejandro; Schaiquevich, Paula; Tornero, Jose A; Sosnik, Alejandro; Mora, Jaume; Carcaboso, Angel M

    2016-02-01

    In addition to surgery, local tumor control in pediatric oncology requires new treatments as an alternative to radiotherapy. SN-38 is an anticancer drug with proved activity against several pediatric solid tumors including neuroblastoma, rhabdomyosarcoma and Ewing sarcoma. Taking advantage of the extremely low aqueous solubility of SN-38, we have developed a novel drug delivery system (DDS) consisting of matrices made of poly(lactic acid) electrospun polymer nanofibers loaded with SN-38 microcrystals for local release in difficult-to-treat pediatric solid tumors. To model the clinical scenario, we conducted extensive preclinical experiments to characterize the biodistribution of the released SN-38 using microdialysis sampling in vivo. We observed that the drug achieves high concentrations in the virtual space of the surgical bed and penetrates a maximum distance of 2 mm within the tumor bulk. Subsequently, we developed a model of subtotal tumor resection in clinically relevant pediatric patient-derived xenografts and used such models to provide evidence of the activity of the SN-38 DDS to inhibit tumor regrowth. We propose that this novel DDS could represent a potential future strategy to avoid harmful radiation therapy as a primary tumor control together with surgery.

  16. Solid lipid nanoparticles loaded with lipoyl-memantine codrug: preparation and characterization.

    PubMed

    Laserra, Sara; Basit, Abdul; Sozio, Piera; Marinelli, Lisa; Fornasari, Erika; Cacciatore, Ivana; Ciulla, Michele; Türkez, Hasan; Geyikoglu, Fatime; Di Stefano, Antonio

    2015-05-15

    Solid lipid nanoparticles (SLNs) are considered very attractive drug-delivery systems (DDS) able to enhance the efficacy of some therapeutic agents in several pathologies difficult to treat in a conventional way. Starting from these evidences, this study describes the preparation, physicochemical characterization, release, and in vitro cytotoxicity of stealth SLNs as innovative approach to improve solubility and absorption through the gastrointestinal tract of lipoyl-memantine (LA-MEM), a potential anti-Alzheimer codrug. Physico-chemical properties of LA-MEM loaded SLNs have been intensively investigated. Differential scanning calorimetry (DSC) was used to clarify the state and crystalline structure of the formulation. The results obtained from particles size analysis, polydispersity (PDI), and zeta potential measurements allowed the identification of the optimized formulation, which was characterized by a drug-lipid ratio 1:5, an average intensity diameter of 170nm, a PDI of 0.072, a zeta potential of -33.8mV, and an entrapment efficiency of 88%. Moreover, in vitro stability and release studies in both simulated gastric fluid (SGF) and simulated intestinal fluid (SIF), and preliminary in vitro cytotoxicity studies revealed that LA-MEM loaded SLNs could represent potential candidate for an in vivo investigation as DDS for the brain since it resulted devoid of citotoxicity and able to release the free codrug.

  17. Solid lipid nanoparticles loaded with lipoyl-memantine codrug: preparation and characterization.

    PubMed

    Laserra, Sara; Basit, Abdul; Sozio, Piera; Marinelli, Lisa; Fornasari, Erika; Cacciatore, Ivana; Ciulla, Michele; Türkez, Hasan; Geyikoglu, Fatime; Di Stefano, Antonio

    2015-05-15

    Solid lipid nanoparticles (SLNs) are considered very attractive drug-delivery systems (DDS) able to enhance the efficacy of some therapeutic agents in several pathologies difficult to treat in a conventional way. Starting from these evidences, this study describes the preparation, physicochemical characterization, release, and in vitro cytotoxicity of stealth SLNs as innovative approach to improve solubility and absorption through the gastrointestinal tract of lipoyl-memantine (LA-MEM), a potential anti-Alzheimer codrug. Physico-chemical properties of LA-MEM loaded SLNs have been intensively investigated. Differential scanning calorimetry (DSC) was used to clarify the state and crystalline structure of the formulation. The results obtained from particles size analysis, polydispersity (PDI), and zeta potential measurements allowed the identification of the optimized formulation, which was characterized by a drug-lipid ratio 1:5, an average intensity diameter of 170nm, a PDI of 0.072, a zeta potential of -33.8mV, and an entrapment efficiency of 88%. Moreover, in vitro stability and release studies in both simulated gastric fluid (SGF) and simulated intestinal fluid (SIF), and preliminary in vitro cytotoxicity studies revealed that LA-MEM loaded SLNs could represent potential candidate for an in vivo investigation as DDS for the brain since it resulted devoid of citotoxicity and able to release the free codrug. PMID:25747452

  18. Preparation, characterization, and optimization of primaquine-loaded solid lipid nanoparticles.

    PubMed

    Omwoyo, Wesley Nyaigoti; Ogutu, Bernhards; Oloo, Florence; Swai, Hulda; Kalombo, Lonji; Melariri, Paula; Mahanga, Geoffrey Maroa; Gathirwa, Jeremiah Waweru

    2014-01-01

    Primaquine (PQ) is one of the most widely used antimalarial drugs and is the only available drug that combats the relapsing form of malaria. PQ use in higher doses is limited by severe tissue toxicity including hematological- and gastrointestinal-related side effects. Nanoformulation of drugs in an appropriate drug carrier system has been extensively studied and shown to have the potential to improve bioavailability, thereby enhancing activity, reducing dose frequency, and subsequently reducing toxicity. The aim of this work was to design, synthesize, and characterize PQ-loaded solid lipid nanoparticles (SLNs) (PQ-SLNs) as a potential drug-delivery system. SLNs were prepared by a modified solvent emulsification evaporation method based on a water-in-oil-in-water (w/o/w) double emulsion. The mean particle size, zeta potential, drug loading, and encapsulation efficiency of the PQ-SLNs were 236 nm, +23 mV, 14%, and 75%, respectively. The zeta potential of the SLNs changed dramatically, from -6.54 mV to +23.0 mV, by binding positively charged chitosan as surface modifier. A spherical morphology of PQ-SLNs was seen by scanning electron microscope. In vitro, release profile depicted a steady drug release over 72 hours. Differential scanning calorimeter thermograms demonstrated presence of drug in drug-loaded nanoparticles along with disappearance of decomposition exotherms, suggesting increased physical stability of drug in prepared formulations. Negligible changes in characteristic peaks of drug in Fourier transform infrared spectra indicated absence of any interaction among the various components entrapped in the nanoparticle formulation. The nanoformulated PQ was 20% more effective as compared with conventional oral dose when tested in Plasmodium berghei-infected Swiss albino mice. This study demonstrated an efficient method of forming a nanomedicine delivery system for antimalarial drugs.

  19. Preparation, characterization, and optimization of primaquine-loaded solid lipid nanoparticles

    PubMed Central

    Omwoyo, Wesley Nyaigoti; Ogutu, Bernhards; Oloo, Florence; Swai, Hulda; Kalombo, Lonji; Melariri, Paula; Mahanga, Geoffrey Maroa; Gathirwa, Jeremiah Waweru

    2014-01-01

    Primaquine (PQ) is one of the most widely used antimalarial drugs and is the only available drug that combats the relapsing form of malaria. PQ use in higher doses is limited by severe tissue toxicity including hematological- and gastrointestinal-related side effects. Nanoformulation of drugs in an appropriate drug carrier system has been extensively studied and shown to have the potential to improve bioavailability, thereby enhancing activity, reducing dose frequency, and subsequently reducing toxicity. The aim of this work was to design, synthesize, and characterize PQ-loaded solid lipid nanoparticles (SLNs) (PQ-SLNs) as a potential drug-delivery system. SLNs were prepared by a modified solvent emulsification evaporation method based on a water-in-oil-in-water (w/o/w) double emulsion. The mean particle size, zeta potential, drug loading, and encapsulation efficiency of the PQ-SLNs were 236 nm, +23 mV, 14%, and 75%, respectively. The zeta potential of the SLNs changed dramatically, from −6.54 mV to +23.0 mV, by binding positively charged chitosan as surface modifier. A spherical morphology of PQ-SLNs was seen by scanning electron microscope. In vitro, release profile depicted a steady drug release over 72 hours. Differential scanning calorimeter thermograms demonstrated presence of drug in drug-loaded nanoparticles along with disappearance of decomposition exotherms, suggesting increased physical stability of drug in prepared formulations. Negligible changes in characteristic peaks of drug in Fourier transform infrared spectra indicated absence of any interaction among the various components entrapped in the nanoparticle formulation. The nanoformulated PQ was 20% more effective as compared with conventional oral dose when tested in Plasmodium berghei-infected Swiss albino mice. This study demonstrated an efficient method of forming a nanomedicine delivery system for antimalarial drugs. PMID:25143734

  20. Optimization of methazolamide-loaded solid lipid nanoparticles for ophthalmic delivery using Box-Behnken design.

    PubMed

    Wang, Fengzhen; Chen, Li; Jiang, Sunmin; He, Jun; Zhang, Xiumei; Peng, Jin; Xu, Qunwei; Li, Rui

    2014-09-01

    The purpose of the present study was to optimize methazolamide (MTZ)-loaded solid lipid nanoparticles (SLNs) which were used as topical eye drops by evaluating the relationship between design factors and experimental data. A three factor, three-level Box-Behnken design (BBD) was used for the optimization procedure, choosing the amount of GMS, the amount of phospholipid, the concentration of surfactant as the independent variables. The chosen dependent variables were entrapment efficiency, dosage loading, and particle size. The generated polynomial equations and response surface plots were used to relate the dependent and independent variables. The optimal nanoparticles were formulated with 100 mg GMS, 150 mg phospholipid, and 1% Tween80 and PEG 400 (1:1, w/v). A new formulation was prepared according to these levels. The observed responses were close to the predicted values of the optimized formulation. The particle size was 197.8 ± 4.9 nm. The polydispersity index of particle size was 0.239 ± 0.01 and the zeta potential was 32.7 ± 2.6 mV. The entrapment efficiency and dosage loading were about 68.39% and 2.49%, respectively. Fourier transform infrared spectroscopy (FT-IR) study indicated that the drug was entrapped in nanoparticles. The optimized formulation showed a sustained release followed the Peppas model. MTZ-SLNs showed significant prolonged decreasing intraocular pressure effect comparing with MTZ solution in vivo pharmacodynamics studies. The results of acute eye irritation study indicated that MTZ-SLNs and AZOPT both had no eye irritation. Furthermore, the MTZ-SLNs were suitable to be stored at low temperature (4 °C).

  1. Method validation for control determination of mercury in fresh fish and shrimp samples by solid sampling thermal decomposition/amalgamation atomic absorption spectrometry.

    PubMed

    Torres, Daiane Placido; Martins-Teixeira, Maristela Braga; Cadore, Solange; Queiroz, Helena Müller

    2015-01-01

    A method for the determination of total mercury in fresh fish and shrimp samples by solid sampling thermal decomposition/amalgamation atomic absorption spectrometry (TDA AAS) has been validated following international foodstuff protocols in order to fulfill the Brazilian National Residue Control Plan. The experimental parameters have been previously studied and optimized according to specific legislation on validation and inorganic contaminants in foodstuff. Linearity, sensitivity, specificity, detection and quantification limits, precision (repeatability and within-laboratory reproducibility), robustness as well as accuracy of the method have been evaluated. Linearity of response was satisfactory for the two range concentrations available on the TDA AAS equipment, between approximately 25.0 and 200.0 μg kg(-1) (square regression) and 250.0 and 2000.0 μg kg(-1) (linear regression) of mercury. The residues for both ranges were homoscedastic and independent, with normal distribution. Correlation coefficients obtained for these ranges were higher than 0.995. Limits of quantification (LOQ) and of detection of the method (LDM), based on signal standard deviation (SD) for a low-in-mercury sample, were 3.0 and 1.0 μg kg(-1), respectively. Repeatability of the method was better than 4%. Within-laboratory reproducibility achieved a relative SD better than 6%. Robustness of the current method was evaluated and pointed sample mass as a significant factor. Accuracy (assessed as the analyte recovery) was calculated on basis of the repeatability, and ranged from 89% to 99%. The obtained results showed the suitability of the present method for direct mercury measurement in fresh fish and shrimp samples and the importance of monitoring the analysis conditions for food control purposes. Additionally, the competence of this method was recognized by accreditation under the standard ISO/IEC 17025. PMID:25996815

  2. Wildfires threaten mercury stocks in northern soils

    USGS Publications Warehouse

    Turetsky, M.R.; Harden, J.W.; Friedli, H.R.; Flannigan, M.; Payne, N.; Crock, J.; Radke, L.

    2006-01-01

    With climate change rapidly affecting northern forests and wetlands, mercury reserves once protected in cold, wet soils are being exposed to burning, likely triggering large releases of mercury to the atmosphere. We quantify organic soil mercury stocks and burn areas across western, boreal Canada for use in fire emission models that explore controls of burn area, consumption severity, and fuel loading on atmospheric mercury emissions. Though renowned as hotspots for the accumulation of mercury and its transformation to the toxic methylmercury, boreal wetlands might soon transition to hotspots for atmospheric mercury emissions. Estimates of circumboreal mercury emissions from this study are 15-fold greater than estimates that do not account for mercury stored in peat soils. Ongoing and projected increases in boreal wildfire activity due to climate change will increase atmospheric mercury emissions, contributing to the anthropogenic alteration of the global mercury cycle and exacerbating mercury toxicities for northern food chains. Copyright 2006 by the American Geophysical Union.

  3. Polymer-supported ionic liquid solid phase extraction for trace inorganic and organic mercury determination in water samples by flow injection-cold vapor atomic absorption spectrometry.

    PubMed

    Escudero, Leticia B; Olsina, Roberto A; Wuilloud, Rodolfo G

    2013-11-15

    A simple and green technique named polymer-supported ionic liquid solid phase extraction (PSIL-SPE) was developed for mercury (Hg) species determination. Inorganic Hg (InHg) species was complexed with chloride ions followed by its introduction into a flow injection on-line system to quantitatively retain the anionic chlorocomplex (HgCl4(2-)) in a column packed with CYPHOS(®) IL 101-impregnated resin. The trapped InHg was then reduced with stannous chloride (SnCl2) and eluted with the same flow of reducing agent followed by cold vapor atomic absorption spectrometry (CV-AAS) detection. Organic mercury species (OrgHg) did not interact with the impregnated resin and were not retained into the column. Total concentration of OrgHg was evaluated by difference between total Hg and InHg concentration. A 95% extraction efficiency was achieved for InHg when the procedure was developed under optimal experimental conditions. The limit of detection obtained for preconcentration of 40 mL of sample was 2.4 ng L(-1) InHg. The relative standard deviation (RSD) was 2.7% (at 1 µg L(-1) InHg and n=10) calculated from the peak height of absorbance signals (Gaussian-shape and reproducible peaks). This work reports the first polymer-supported IL solid phase extraction approach implemented in a flow injection on-line system for determination of Hg species in mineral, tap and river water samples.

  4. Determination of copper, nickel, cobalt, silver, lead, cadmium, and mercury ions in water by solid-phase extraction and the RP-HPLC with UV-Vis detection.

    PubMed

    Hu, Qiufen; Yang, Guangyu; Zhao, Yiyun; Yin, Jiayuan

    2003-03-01

    A new method for the simultaneous determination of seven heavy metal ions in water by solid-phase extraction and reversed-phase high-performance liquid chromatography (RP-HPLC) was developed. The copper, nickel, cobalt, silver, lead, cadmium, and mercury ions were pre-column derivatized with tetra( m-aminophenyl)porphyrin (T m-APP) to form colored chelates. The metal-T m-APP chelates in 100 mL of sample were preconcentrated to 1 mL by solid-phase extraction with a C(18 )cartridge; an enrichment factor of 100 was achieved. The chelates were separated on a Waters Xterra()RP(18) column by gradient elution with methanol (containing 0.05 mol L(-1) pyrrolidine-acetic acid buffer salt, pH 10.0) and acetone (containing 0.05 mol L(-1) pyrrolidine-acetic acid buffer salt, pH 10.0) as mobile phase at a flow rate of 1.0 mL min(-1) and detected with a photodiode array detector. The detection limits of copper, cobalt, nickel, silver, lead, cadmium, and mercury are 2, 2, 3, 4, 3, 3, and 3 ng L(-1), respectively, in the original sample. The method was also applied to the determination of these metals in water with good results. PMID:12664186

  5. Simultaneous saccharification and co-fermentation for improving the xylose utilization of steam exploded corn stover at high solid loading.

    PubMed

    Liu, Zhi-Hua; Chen, Hong-Zhang

    2016-02-01

    Simultaneous saccharification and co-fermentation (SSCF) of steam exploded corn stover (SECS) was investigated at 5-25% solid loadings compared with other conversion processes. SECS was washed with a 15-fold excess of deionized water to remove inhibitors of hydrolysis and fermentation. The concentration, yield, and productivity of ethanol was 34.3g/L, 90.0%, 2.61g/L/h in the co-fermentation of 60g/L glucose and 10g/L xylose by Saccharomyces cerevisiae IPE003. Ethanol concentration and productivity increased with increasing solid loading while ethanol yield decreased in all conversion processes of SECS. Glucan and xylan conversion was 82.0% and 82.1% in SSCF at 20% solid loading, respectively, while the concentration, yield and productivity of ethanol was 60.8g/L, 75.3% and 0.63g/L/h. The feeding strategy of SECS addition within 24h improved the SSCF performance. Therefore, SSCF increased ethanol productivity and was an effective conversion process for ethanol production at high solid loading. PMID:26615497

  6. Recent Approaches to Modeling Transport of Mercury in Surface Water and Groundwater - Case Study in Upper East Fork Poplar Creek, Oak Ridge, TN - 13349

    SciTech Connect

    Bostick, Kent; Daniel, Anamary; Tachiev, Georgio; Malek-Mohammadi, Siamak

    2013-07-01

    In this case study, groundwater/surface water modeling was used to determine efficacy of stabilization in place with hydrologic isolation for remediation of mercury contaminated areas in the Upper East Fork Poplar Creek (UEFPC) Watershed in Oak Ridge, TN. The modeling simulates the potential for mercury in soil to contaminate groundwater above industrial use risk standards and to contribute to surface water contamination. The modeling approach is unique in that it couples watershed hydrology with the total mercury transport and provides a tool for analysis of changes in mercury load related to daily precipitation, evaporation, and runoff from storms. The model also allows for simulation of colloidal transport of total mercury in surface water. Previous models for the watershed only simulated average yearly conditions and dissolved concentrations that are not sufficient for predicting mercury flux under variable flow conditions that control colloidal transport of mercury in the watershed. The transport of mercury from groundwater to surface water from mercury sources identified from information in the Oak Ridge Environmental Information System was simulated using a watershed scale model calibrated to match observed daily creek flow, total suspended solids and mercury fluxes. Mercury sources at the former Building 81-10 area, where mercury was previously retorted, were modeled using a telescopic refined mesh with boundary conditions extracted from the watershed model. Modeling on a watershed scale indicated that only source excavation for soils/sediment in the vicinity of UEFPC had any effect on mercury flux in surface water. The simulations showed that colloidal transport contributed 85 percent of the total mercury flux leaving the UEFPC watershed under high flow conditions. Simulation of dissolved mercury transport from liquid elemental mercury and adsorbed sources in soil at former Building 81-10 indicated that dissolved concentrations are orders of magnitude

  7. Solid and liquid lipid-based binary solid lipid nanoparticles of diacerein: in vitro evaluation of sustained release, simultaneous loading of gold nanoparticles, and potential thermoresponsive behavior

    PubMed Central

    Rehman, Mubashar; Madni, Asadullah; Ihsan, Ayesha; Khan, Waheed Samraiz; Khan, Muhammad Imran; Mahmood, Muhammad Ahmad; Ashfaq, Muhammad; Bajwa, Sadia Zafar; Shakir, Imran

    2015-01-01

    Binary fatty acid mixture-based solid lipid nanoparticles (SLNs) were prepared for delivery of diacerein, a novel disease-modifying osteoarthritis drug, with and without simultaneously loaded gold nanoparticles (GNPs). In order to optimize SLNs for temperature-responsive release, lipid mixtures were prepared using different ratios of solid (stearic acid or lauric acid) and liquid (oleic acid) fatty acids. SLNs were prepared by microemulsification (53 nm), hot melt encapsulation (10.4 nm), and a solvent emulsification-evaporation technique (7.8 nm). The physicochemical characteristics of SLNs were studied by Zetasizer, Fourier transform infrared, and X-ray diffraction analysis. High encapsulation of diacerein was achieved with diacerein-loaded and simultaneously GNP-diacerein-loaded SLNs. In vitro dissolution studies revealed a sustained release pattern for diacerein over 72 hours for diacerein-loaded SLNs and 12 hours for GNP-diacerein-loaded SLNs. An increase in diacerein payload increased the release time of diacerein while GNPs decreased it. In addition, rapid release of diacerein over 4 hours was observed at 40°C (melting point of optimized fatty acid mixture), demonstrating that these binary SLNs could be used for thermoresponsive drug delivery. Kinetic modeling indicated that drug release followed zero order and Higuchi diffusion models (R10>0.9), while the Korsmeyer-Peppas model predicted a diffusion release mechanism (n<0.5). PMID:25897224

  8. Solid and liquid lipid-based binary solid lipid nanoparticles of diacerein: in vitro evaluation of sustained release, simultaneous loading of gold nanoparticles, and potential thermoresponsive behavior.

    PubMed

    Rehman, Mubashar; Madni, Asadullah; Ihsan, Ayesha; Khan, Waheed Samraiz; Khan, Muhammad Imran; Mahmood, Muhammad Ahmad; Ashfaq, Muhammad; Bajwa, Sadia Zafar; Shakir, Imran

    2015-01-01

    Binary fatty acid mixture-based solid lipid nanoparticles (SLNs) were prepared for delivery of diacerein, a novel disease-modifying osteoarthritis drug, with and without simultaneously loaded gold nanoparticles (GNPs). In order to optimize SLNs for temperature-responsive release, lipid mixtures were prepared using different ratios of solid (stearic acid or lauric acid) and liquid (oleic acid) fatty acids. SLNs were prepared by microemulsification (53 nm), hot melt encapsulation (10.4 nm), and a solvent emulsification-evaporation technique (7.8 nm). The physicochemical characteristics of SLNs were studied by Zetasizer, Fourier transform infrared, and X-ray diffraction analysis. High encapsulation of diacerein was achieved with diacerein-loaded and simultaneously GNP-diacerein-loaded SLNs. In vitro dissolution studies revealed a sustained release pattern for diacerein over 72 hours for diacerein-loaded SLNs and 12 hours for GNP-diacerein-loaded SLNs. An increase in diacerein payload increased the release time of diacerein while GNPs decreased it. In addition, rapid release of diacerein over 4 hours was observed at 40°C (melting point of optimized fatty acid mixture), demonstrating that these binary SLNs could be used for thermoresponsive drug delivery. Kinetic modeling indicated that drug release followed zero order and Higuchi diffusion models (R(2)>0.9), while the Korsmeyer-Peppas model predicted a diffusion release mechanism (n<0.5).

  9. Characterization and evaluation of metformin-loaded solid lipid nanoparticles for celluar and mitochondrial uptake.

    PubMed

    Xu, Qiang; Zhu, Tao; Yi, Chaoli; Shen, Qi

    2016-01-01

    Considered a popular drug for diabetes in recent years, metformin was determined to have a moderate anti-tumor effect, particularly in breast cancer. In this study, the anticancer mechanism of metformin was verified by preparing solid lipid nanoparticles (SLNs) and chitosan-modified solid lipid nanoparticles (CSLNs) containing metformin and then estimating the potential of these SLNs for uptake in cells and mitochondria. Metformin-SLNs were prepared using an emulsification and low-temperature solidification method. The mean particle size, zeta potential, entrapment efficiency, and loading efficiency of metformin-SLNs and metformin chitosan-modified SLNs were 102.3 ± 4.16 and 200.1 ± 17.69 nm, -21.25 ± 4.89 and 50.6 ± 4.09 mv, 26.25 ± 2.59% and 33.6 ± 2.21%, and 1.74 ± 0.16% and 1.46 ± 0.10%, respectively. TEM images showed that both the nanoparticles had spherical morphologies with no aggregation. Results of cellular and mitochondrial uptake showed that the metformin-SLNs were easier to uptake in cells and mitochondria than the pure drug group (that was the control group without SLN structure modification). The findings of this research provide a basis for conducting further studies on the anticancer mechanism of metformin. PMID:26288997

  10. Docetaxel-loaded solid lipid nanoparticles suppress breast cancer cells growth with reduced myelosuppression toxicity

    PubMed Central

    Yuan, Qing; Han, Jing; Cong, Wenshu; Ge, Ying; Ma, Dandan; Dai, Zhaoxia; Li, Yaping; Bi, Xiaolin

    2014-01-01

    Docetaxel is an adjuvant chemotherapy drug widely used to treat multiple solid tumors; however, its toxicity and side effects limit its clinical efficacy. Herein, docetaxel-loaded solid lipid nanoparticles (DSNs) were developed to reduce systemic toxicity of docetaxel while still keeping its anticancer activity. To evaluate its anticancer activity and toxicity, and to understand the molecular mechanisms of DSNs, different cellular, molecular, and whole genome transcription analysis approaches were utilized. The DSNs showed lower cytotoxicity compared with the commercial formulation of docetaxel (Taxotere®) and induced more apoptosis at 24 hours after treatment in vitro. DSNs can cause the treated cancer cells to arrest in the G2/M phase in a dose-dependent manner similar to Taxotere. They can also suppress tumor growth very effectively in a mice model with human xenograft breast cancer. Systemic analysis of gene expression profiles by microarray and subsequent verification experiments suggested that both DSNs and Taxotere regulate gene expression and gene function, including DNA replication, DNA damage response, cell proliferation, apoptosis, and cell cycle regulation. Some of these genes expressed differentially at the protein level although their messenger RNA expression level was similar under Taxotere and DSN treatment. Moreover, DSNs improved the main side effect of Taxotere by greatly lowering myelosuppression toxicity to bone marrow cells from mice. Taken together, these results expound the antitumor efficacy and the potential working mechanisms of DSNs in its anticancer activity and toxicity, which provide a theoretical foundation to develop and apply a more efficient docetaxel formulation to treat cancer patients. PMID:25378924

  11. Optimization of the production of solid Witepsol nanoparticles loaded with rosmarinic acid.

    PubMed

    Campos, Débora A; Madureira, Ana Raquel; Gomes, Ana Maria; Sarmento, Bruno; Pintado, Maria Manuela

    2014-03-01

    During the last decade there has been a growing interest in the formulation of new food and nutraceutical products containing compounds with antioxidant activity. Unfortunately, due to their structure, certain compounds such as polyphenols, in particular rosmarinic acid (RA) are not stable and may interact easily with matrices in which they are incorporated. To overcome such limitations, the formulation of loaded polyphenols nanoparticles can offer an efficient solution to protect such compounds. Based on this rationale, the aim of this study was to prepare solid lipid nanoparticles (SLNs) loaded with RA using a hot melt ultrasonication method, where Witepsol H15 was used as lipid and Polysorbate 80 (Tween 80) as surfactant, following a 3(2) fractional factorial design, resulting in the use of 3 different percentages of surfactant (viz. 1, 2 and 3%, v/v) and lipid (0.5, 1.0 and 1.5%, w/v). The stability of the nanoparticles systems were tested during 28 d in aqueous solution stored at refrigeration temperature (ca. 5 °C), tracking the mean particle size of different formulations by photon correlation spectroscopy. To confirm RA entrapment, thermal analyses of the nanoparticles by DSC and FTIR were performed. The association efficiencies percentages (AE%) were determined using HPLC to quantitatively assess the RA in supernatants. Results showed that Witepsol H15 produced nanoparticles with initial mean diameters between 270 and 1000 nm, yet over time, a slight increase occurred, but without occurrence of aggregation. The AE% showed a high percentage of encapsulation (ca. 99%), which reveals low polyphenol releases from SLNs throughout storage time. In general, results showed a successful production of SLNs with properties that can be used to food applications. PMID:24413308

  12. Formulation and Physicochemical Characterization of Lycopene-Loaded Solid Lipid Nanoparticles

    PubMed Central

    Nazemiyeh, Elham; Eskandani, Morteza; Sheikhloie, Hossein; Nazemiyeh, Hossein

    2016-01-01

    Purpose: Lycopene belongs to the carotenoids that shows good pharmacological properties including antioxidant, anti-inflammatory and anticancer. However, as a result of very low aqueous solubility, it has a limited systemic absorption, following oral administration. Methods: Here, we prepared a stable lycopene-loaded solid lipid nanoparticles using Precirol® ATO5, Compritol 888 ATO and myristic acid by hot homogenization method with some modification. The size and morphological characteristics of nanoparticles were evaluated using Scanning Electron Microscopy (SEM). Moreover, zeta potential and dispersity index (DI) were measured using zeta sizer. In addition, encapsulation efficiency (EE%), drug loading (DL) and cumulative drug release were quantified. Results: The results showed that the size and DI of particles was generally smaller in the case of SLNs prepared with precirol when compared to SLNs prepared with compritol. Scanning electron microscopy (SEM) and particle size analyses showed spherical SLNs (125 ± 3.89 nm), monodispersed distribution, and zeta potential of −10.06 ± 0.08 mV. High EE (98.4 ± 0.5 %) and DL (44.8 ± 0.46 mg/g) were achieved in the case of nanoparticles prepared by precirol. The stability study of the lycopene-SLNs in aqueous medium (4 °C) was showed that after 2 months there is no significant differences seen in size and DI compared with the fresh formulation. Conclusion: Conclusively, in this investigation we prepared a stable lycopene-SLNs with good physicochemical characteristic which candidate it for the future in vivo trials in nutraceutical industries. PMID:27478786

  13. Activation of the mercury laser: a diode-pumped solid-state laser driver for inertial fusion

    SciTech Connect

    Bayramian, A J; Bibeau, C; Beach, R J; Ebbers, C A; Kanz, K; Nakano, H; Orth, C D; Payne, S A; Powell, H T; Schaffers, K I; Seppala, L; Skulina, K; Smith, L K; Sutton, S B; Zapata, L E

    2000-09-19

    Initial measurements are reported for the Mercury laser system, a scalable driver for rep-rated high energy density physics research. The performance goals include 10% electrical efficiency at 10 Hz and 100 J with a 2-10 ns pulse length.

  14. MERCURY REACTIONS IN THE PRESENCE OF CHLORINE SPECIES: HOMOGENOUS GAS PHASE AND HETEROGENOUS GAS-SOLID PHASE

    EPA Science Inventory

    The kinetics of mercury chlorination (with HC1) were studied using a flow reactor system with an on-line Hg analyzer and spciation sampling using a set of impingers. Kinetic parameters, such as reaction order (a), activation energy (Eu) and the overall rate constant (k') were es...

  15. Preparation and in Vivo Evaluation of a Dutasteride-Loaded Solid-Supersaturatable Self-Microemulsifying Drug Delivery System

    PubMed Central

    Kim, Min-Soo; Ha, Eun-Sol; Choo, Gwang-Ho; Baek, In-Hwan

    2015-01-01

    The purpose of this study was to prepare a dutasteride-loaded solid-supersaturatable self-microemulsifying drug delivery system (SMEDDS) using hydrophilic additives with high oral bioavailability, and to determine if there was a correlation between the in vitro dissolution data and the in vivo pharmacokinetic parameters of this delivery system in rats. A dutasteride-loaded solid-supersaturatable SMEDDS was generated by adsorption of liquid SMEDDS onto Aerosil 200 colloidal silica using a spray drying process. The dissolution and oral absorption of dutasteride from solid SMEDDS significantly increased after the addition of hydroxypropylmethyl cellulose (HPMC) or Soluplus. Solid SMEDDS/Aerosil 200/Soluplus microparticles had higher oral bioavailability with 6.8- and 5.0-fold higher peak plasma concentration (Cmax) and area under the concentration-time curve (AUC) values, respectively, than that of the equivalent physical mixture. A linear correlation between in vitro dissolution efficiency and in vivo pharmacokinetic parameters was demonstrated for both AUC and Cmax values. Therefore, the preparation of a solid-supersaturatable SMEDDS with HPMC or Soluplus could be a promising formulation strategy to develop novel solid dosage forms of dutasteride. PMID:25984604

  16. Preparation and in vivo evaluation of a dutasteride-loaded solid-supersaturatable self-microemulsifying drug delivery system.

    PubMed

    Kim, Min-Soo; Ha, Eun-Sol; Choo, Gwang-Ho; Baek, In-Hwan

    2015-01-01

    The purpose of this study was to prepare a dutasteride-loaded solid-supersaturatable self-microemulsifying drug delivery system (SMEDDS) using hydrophilic additives with high oral bioavailability, and to determine if there was a correlation between the in vitro dissolution data and the in vivo pharmacokinetic parameters of this delivery system in rats. A dutasteride-loaded solid-supersaturatable SMEDDS was generated by adsorption of liquid SMEDDS onto Aerosil 200 colloidal silica using a spray drying process. The dissolution and oral absorption of dutasteride from solid SMEDDS significantly increased after the addition of hydroxypropylmethyl cellulose (HPMC) or Soluplus. Solid SMEDDS/Aerosil 200/Soluplus microparticles had higher oral bioavailability with 6.8- and 5.0-fold higher peak plasma concentration (Cmax) and area under the concentration-time curve (AUC) values, respectively, than that of the equivalent physical mixture. A linear correlation between in vitro dissolution efficiency and in vivo pharmacokinetic parameters was demonstrated for both AUC and Cmax values. Therefore, the preparation of a solid-supersaturatable SMEDDS with HPMC or Soluplus could be a promising formulation strategy to develop novel solid dosage forms of dutasteride. PMID:25984604

  17. Sesamol-loaded solid lipid nanoparticles for treatment of skin cancer.

    PubMed

    Geetha, T; Kapila, Meenakshi; Prakash, Om; Deol, Parneet Kaur; Kakkar, Vandita; Kaur, Indu Pal

    2015-02-01

    Abstract Role of reactive oxygen species (ROS) in skin carcinogenesis is well documented. Natural molecules, like sesamol, with marked antioxidant potential can be useful in combating skin cancers. In vitro antiproliferative (using MTT assay) and DNA fragmentation studies in HL 60 cell lines, confirmed the apoptotic nature of sesamol. However, it showed a significant flux across the mice skin upon topical application, such that its local availability in skin is limited. Former is attributed mainly to its properties like small size, low molecular weight (138.28), and a sufficient lipid and water solubility (log P 1.29; solubility 38.8 mg/ml). To achieve its maximum epicutaneous delivery, packaging it into a suitable carrier system is thus indicated. Sesamol-loaded solid lipid nanoparticles (S-SLN) were thus prepared with particle size of 127.9 nm (PI: 0.256) and entrapment efficiency of 88.21%. Topical application of S-SLN in a cream base indicated significant retention in the skin with minimal flux across skin as confirmed by the in-vivo skin retention and ex-vivo skin permeation studies. In vivo anticancer studies performed on TPA-induced and benzo(a)pyrene initiated tumour production (ROS mediated) in mouse epidermis showed the normalization (in histology studies) of skin cancers post their induction, upon treatment with S-SLN. PMID:25268273

  18. Bevacizumab loaded solid lipid nanoparticles prepared by the coacervation technique: preliminary in vitro studies

    NASA Astrophysics Data System (ADS)

    Battaglia, Luigi; Gallarate, Marina; Peira, Elena; Chirio, Daniela; Solazzi, Ilaria; Giordano, Susanna Marzia Adele; Gigliotti, Casimiro Luca; Riganti, Chiara; Dianzani, Chiara

    2015-06-01

    Glioblastoma, the most common primary brain tumor in adults, has an inauspicious prognosis, given that overcoming the blood-brain barrier is the major obstacle to the pharmacological treatment of brain tumors. As neoangiogenesis plays a key role in glioblastoma growth, the US Food and Drug Administration approved bevacizumab (BVZ), an antivascular endothelial growth factor antibody for the treatment of recurrent glioblastoma in patients whose the initial therapy has failed. In this experimental work, BVZ was entrapped in solid lipid nanoparticles (SLNs) prepared by the fatty-acid coacervation technique, thanks to the formation of a hydrophobic ion pair. BVZ activity, which was evaluated by means of four different in vitro tests on HUVEC cells, increased by 100- to 200-fold when delivered in SLNs. Moreover, SLNs can enhance the permeation of fluorescently labelled BVZ through an hCMEC/D3 cell monolayer—an in vitro model of the blood brain barrier. These results are promising, even if further in vivo studies are required to evaluate the effective potential of BVZ-loaded SLNs in glioblastoma treatment.

  19. Preparation, characterisation and antibacterial activity of a florfenicol-loaded solid lipid nanoparticle suspension.

    PubMed

    Wang, Ting; Chen, Xiaojin; Lu, Mengmeng; Li, Xihe; Zhou, WenZhong

    2015-12-01

    A florfenicol-loaded solid lipid nanoparticle (FFC-SLN) suspension was prepared by hot homogenisation and ultrasonic technique. The suspension was characterised for its release profile, stability, toxicity, and the physicochemical properties of the nanoparticles. Antibacterial activity of the suspension was evaluated in vitro and in vivo. The results showed that the mean diameter, polydispersity index and zeta potential of the nanoparticles were 253 ± 3 nm, 0.409 ± 0.022 and 47.5 ± 0.21 mV, respectively. In vitro release profile showed the FFC-SLN suspension had sustained release effect. The minimum inhibition concentration values of the FFC-SLN suspension were 6 and 3 µg/mL against Staphylococcus aureus and Escherichia coli respectively, compared with 3.5 and 2 µg/mL of native florfenicol. The suspension was relatively stable at 4°C and less stable at room temperature during 9 months storage. Although the nanoparticle carriers exhibited cytotoxicity in cell cultures, the LD50 of the lyophilised dry power of the suspension was higher than 5 g/kg body weight. Mortality protection against E. coli lethal infection in mice showed that the nanoparticle suspension had much better efficacy (6/10) than native drug (1/10). These results indicate that FFC-SLN suspension could be a promising formulation in veterinary medicine. PMID:26647811

  20. Indomethacin-Loaded Solid Lipid Nanoparticles for Ocular Delivery: Development, Characterization, and In Vitro Evaluation

    PubMed Central

    Hippalgaonkar, Ketan; Adelli, Goutham R.; Hippalgaonkar, Kanchan; Repka, Michael A.

    2013-01-01

    Abstract Purpose The goal of this study was to develop and characterize indomethacin-loaded solid lipid nanoparticles (IN-SLNs; 0.1% w/v) for ocular delivery. Methods Various lipids, homogenization pressures/cycles, Tween 80 fraction in the mixture of surfactants (Poloxamer 188 and Tween 80; total surfactant concentration at 1% w/v), and pH were investigated in the preparation of the IN-SLNs. Compritol® 888 ATO was selected as the lipid phase for the IN-SLNs, as indomethacin exhibited a highest distribution coefficient and solubility in this phase. Results Homogenization at 15,000 psi for 6 cycles resulted in the smallest particle size. Increase in the Poloxamer 188 fraction resulted in decrease in the entrapment efficiency (EE). The mean particle size, polydispersity index, zeta-potential, and EE of the optimized formulation were 140 nm, 0.16, −21 mV, and 72.0%, respectively. IN-SLNs were physically stable post-sterilization and on storage for a period of 1 month (last timepoint tested). A dramatic increase in the chemical stability and in vitro corneal permeability of indomethacin was observed with the IN-SLN formulation in comparison to the indomethacin solution- (0.1% w/v) and indomethacin hydroxypropyl-beta-cyclodextrin-based formulations (0.1% w/v). Conclusion Results from this study suggest that topical IN-SLNs could significantly improve ocular bioavailability of indomethacin. PMID:23421502

  1. Sesamol-loaded solid lipid nanoparticles for treatment of skin cancer.

    PubMed

    Geetha, T; Kapila, Meenakshi; Prakash, Om; Deol, Parneet Kaur; Kakkar, Vandita; Kaur, Indu Pal

    2015-02-01

    Abstract Role of reactive oxygen species (ROS) in skin carcinogenesis is well documented. Natural molecules, like sesamol, with marked antioxidant potential can be useful in combating skin cancers. In vitro antiproliferative (using MTT assay) and DNA fragmentation studies in HL 60 cell lines, confirmed the apoptotic nature of sesamol. However, it showed a significant flux across the mice skin upon topical application, such that its local availability in skin is limited. Former is attributed mainly to its properties like small size, low molecular weight (138.28), and a sufficient lipid and water solubility (log P 1.29; solubility 38.8 mg/ml). To achieve its maximum epicutaneous delivery, packaging it into a suitable carrier system is thus indicated. Sesamol-loaded solid lipid nanoparticles (S-SLN) were thus prepared with particle size of 127.9 nm (PI: 0.256) and entrapment efficiency of 88.21%. Topical application of S-SLN in a cream base indicated significant retention in the skin with minimal flux across skin as confirmed by the in-vivo skin retention and ex-vivo skin permeation studies. In vivo anticancer studies performed on TPA-induced and benzo(a)pyrene initiated tumour production (ROS mediated) in mouse epidermis showed the normalization (in histology studies) of skin cancers post their induction, upon treatment with S-SLN.

  2. Enzymatic hydrolysis of steam-exploded sugarcane bagasse using high total solids and low enzyme loadings.

    PubMed

    Ramos, Luiz Pereira; da Silva, Larissa; Ballem, Annielly Comelli; Pitarelo, Ana Paula; Chiarello, Luana Marcele; Silveira, Marcos Henrique Luciano

    2015-01-01

    Hydrolysis of phosphoric acid-impregnated steam-treated sugarcane bagasse was pre-optimized using a face-centered central composite design in which the process variables were the substrate total solids (TS, %), agitation intensity (AI, rpm) and enzyme loading (EL, gg(-1)). Pretreatment was carried out at 180°C for 10min using cane bagasse with 50wt% moisture content containing 9.5mg of H3PO4 per gram of dry biomass. Hydrolyses were performed for 96h at 50°C using Cellic CTec2® and water-washed steam-treated substrates. The highest amount of fermentable sugars was obtained with 20wt% TS, producing 76.8gL(-1) of glucose equivalents, which corresponded to a total glucan conversion of 69.2wt% and to a theoretical net increase of 39% in ethanol production from the same sugarcane tonnage without considering the use of leaves, tops and the additional yields from C5 sugars.

  3. Preparation, characterisation and antibacterial activity of a florfenicol-loaded solid lipid nanoparticle suspension.

    PubMed

    Wang, Ting; Chen, Xiaojin; Lu, Mengmeng; Li, Xihe; Zhou, WenZhong

    2015-12-01

    A florfenicol-loaded solid lipid nanoparticle (FFC-SLN) suspension was prepared by hot homogenisation and ultrasonic technique. The suspension was characterised for its release profile, stability, toxicity, and the physicochemical properties of the nanoparticles. Antibacterial activity of the suspension was evaluated in vitro and in vivo. The results showed that the mean diameter, polydispersity index and zeta potential of the nanoparticles were 253 ± 3 nm, 0.409 ± 0.022 and 47.5 ± 0.21 mV, respectively. In vitro release profile showed the FFC-SLN suspension had sustained release effect. The minimum inhibition concentration values of the FFC-SLN suspension were 6 and 3 µg/mL against Staphylococcus aureus and Escherichia coli respectively, compared with 3.5 and 2 µg/mL of native florfenicol. The suspension was relatively stable at 4°C and less stable at room temperature during 9 months storage. Although the nanoparticle carriers exhibited cytotoxicity in cell cultures, the LD50 of the lyophilised dry power of the suspension was higher than 5 g/kg body weight. Mortality protection against E. coli lethal infection in mice showed that the nanoparticle suspension had much better efficacy (6/10) than native drug (1/10). These results indicate that FFC-SLN suspension could be a promising formulation in veterinary medicine.

  4. Mercury Sources and Cycling in the Great Lakes: Dramatic Changes Resulting from Altered Atmospheric Loads and the Near-Shore Shunt

    NASA Astrophysics Data System (ADS)

    Krabbenhoft, D. P.; DeWild, J. F.; Maglio, M. M.; Tate, M. T.; Ogorek, J. M.; Hurley, J. P.; Lepak, R.

    2013-12-01

    Mercury (Hg) contamination of the aquatic food webs across the Great Lakes remains a significant environmental issue. However, our ability to prescribe corrective actions has been significantly hampered by a scarcity of data, particularly for methylmercury (MeHg) the most toxic and bioaccumulative form of mercury in freshwater ecosystems. As part of the Great Lakes Restoration Initiative initiated in 2010, a joint effort was undertaken by the U.S. Geological Survey (USGS) and U.S. Environmental Protection Agency (USEPA) to improve our understanding of total Hg and MeHg concentrations and distributions in the Great Lakes. Since 2010, sampling surveys have been conducted at about 15-20 stations twice annually (April and August) at 15-20 stations per lake to collect data from both cold and warm water conditions. All sampling was conducted using trace-metal free protocols using a sampling rosette equipped with 12 Teflon-lined Niskin. Water samples were collected at predetermined depths: mid-epilimnion, mid-thermocline, deep chlorophyll layer, mid-hypolimnion, and about 2 meters above the bottom. Seston samples were collected from the top 20 meters using plankton nets, while bottom sediments and benthos samples were acquired using a ponar sampler. Water, biota, and sediment samples were all analyzed for Hg and MeHg concentration at the USGS Mercury Research Laboratory in Middleton, Wisconsin. Several important trends are apparent from the water column samples. First, most stations reveal a strong top-to-bottom declining trend total Hg concentration, underscoring the importance of atmospheric deposition to the Great Lakes. Methylmercury profiles, show maximal concentrations at the thermocline or deep chlorophyll layer, suggesting in situ water-column MeHg production. Calculations suggest this in-lake MeHg source is similar in magnitude to tributary loading of MeHg, which heretofore was thought to be the dominant MeHg source. Aqueous total Hg results also suggest that

  5. Pressure-driven mesofluidic platform integrating automated on-chip renewable micro-solid-phase extraction for ultrasensitive determination of waterborne inorganic mercury.

    PubMed

    Portugal, Lindomar A; Laglera, Luis M; Anthemidis, Aristidis N; Ferreira, Sérgio L C; Miró, Manuel

    2013-06-15

    A dedicated pressure-driven mesofluidic platform incorporating on-chip sample clean-up and analyte preconcentration is herein reported for expedient determination of trace level concentrations of waterborne inorganic mercury. Capitalizing upon the Lab-on-a-Valve (LOV) concept, the mesofluidic device integrates on-chip micro-solid phase extraction (μSPE) in automatic disposable mode followed by chemical vapor generation and gas-liquid separation prior to in-line atomic fluorescence spectrometric detection. In contrast to prevailing chelating sorbents for Hg(II), bare poly(divinylbenzene-N-vinylpyrrolidone) copolymer sorptive beads were resorted to efficient uptake of Hg(II) in hydrochloric acid milieu (pH=2.3) without the need for metal derivatization nor pH adjustment of prior acidified water samples for preservation to near-neutral conditions. Experimental variables influencing the sorptive uptake and retrieval of target species and the evolvement of elemental mercury within the miniaturized integrated reaction chamber/gas-liquid separator were investigated in detail. Using merely <10 mg of sorbent, the limits of detection and quantification at the 3s(blank) and 10s(blank) levels, respectively, for a sample volume of 3 mL were 12 and 42 ng L(-1) Hg(II) with a dynamic range extending up to 5.0 μg L(-1). The proposed mesofluidic platform copes with the requirements of regulatory bodies (US-EPA, WHO, EU-Commission) for drinking water quality and surface waters that endorse maximum allowed concentrations of mercury spanning from 0.07 to 6.0 μg L(-1). Demonstrated with the analysis of aqueous samples of varying matrix complexity, the LOV approach afforded reliable results with relative recoveries of 86-107% and intermediate precision down to 9% in the renewable μSPE format.

  6. Regional Scale Photochemical Model Evaluation of Total Mercury Wet Deposition and Speciated Ambient Mercury

    EPA Science Inventory

    Methylmercury is a known neurotoxin with deleterious health effects on humans and wildlife. Atmospheric deposition is the largest source of mercury loading to most terrestrial and aquatic ecosystems. Regional scale air quality models are needed to quantify mercury deposition resu...

  7. Solid phase extraction of inorganic mercury using 5-phenylazo-8-hydroxyquinoline and determination by cold vapor atomic fluorescence spectroscopy in natural water samples.

    PubMed

    Daye, Mirna; Ouddane, Baghdad; Halwani, Jalal; Hamzeh, Mariam

    2013-01-01

    8-Hydroxyquinoline (8-HQ) was chosen as a powerful ligand for Hg solid phase extraction. Among several chelating resins based on 8-HQ, 5-phenylazo-8-hydroxyquinoline (5Ph8HQ) is used for mercury extraction in which the adsorption dynamics were fully studied. It has been shown that Hg(II) is totally absorbed by 5Ph8HQ within the first 30 minutes of contact time with t 1/2 5 minutes, following Langmuir adsorption model. At pH 4, the affinity of mercury is unchallenged by other metals except, for Cu(II), which have shown higher Kd value. With these latter characteristics, 5Ph8HQ was examined for the preconcentration of trace levels of Hg(II). The developed method showed quantitative recoveries of Hg(II) with LOD = 0.21 pg mL(-1) and RSD = 3-6% using cold vapor atomic fluorescence spectroscopy (CV-AFS) with a preconcentration factor greater than 250.

  8. Solid Phase Extraction of Inorganic Mercury Using 5-Phenylazo-8-hydroxyquinoline and Determination by Cold Vapor Atomic Fluorescence Spectroscopy in Natural Water Samples

    PubMed Central

    Daye, Mirna; Halwani, Jalal; Hamzeh, Mariam

    2013-01-01

    8-Hydroxyquinoline (8-HQ) was chosen as a powerful ligand for Hg solid phase extraction. Among several chelating resins based on 8-HQ, 5-phenylazo-8-hydroxyquinoline (5Ph8HQ) is used for mercury extraction in which the adsorption dynamics were fully studied. It has been shown that Hg(II) is totally absorbed by 5Ph8HQ within the first 30 minutes of contact time with t1/2 5 minutes, following Langmuir adsorption model. At pH 4, the affinity of mercury is unchallenged by other metals except, for Cu(II), which have shown higher Kd value. With these latter characteristics, 5Ph8HQ was examined for the preconcentration of trace levels of Hg(II). The developed method showed quantitative recoveries of Hg(II) with LOD = 0.21 pg mL−1 and RSD = 3–6% using cold vapor atomic fluorescence spectroscopy (CV-AFS) with a preconcentration factor greater than 250. PMID:24459417

  9. Recent advances in solid polymer electrolyte fuel cell technology with low platinum loading electrodes

    NASA Technical Reports Server (NTRS)

    Srinivasan, Supramaniam; Manko, David J.; Enayatullah, Mohammad; Appleby, A. John

    1989-01-01

    High power density fuel cell systems for defense and civilian applications are being developed. Taking into consideration the main causes for efficiency losses (activation, mass transport and ohmic overpotentials) the only fuel cell systems capable of achieving high power densities are the ones with alkaline and solid polymer electrolyte. High power densities (0.8 W/sq cm at 0.8 V and 1 A/sq cm with H2 and O2 as reactants), were already used in NASA's Apollo and Space Shuttle flights as auxiliary power sources. Even higher power densities (4 W/sq cm - i.e., 8 A sq cm at 0.5 V) were reported by the USAF/International Fuel Cells in advanced versions of the alkaline system. High power densities (approximately 1 watt/sq cm) in solid polymer electrolyte fuel cells with ten times lower platinum loading in the electrodes (i.e., 0.4 mg/sq cm) were attained. It is now possible to reach a cell potential of 0.620 V at a current density of 2 A/sq cm and at a temperature of 95 C and pressure of 4/5 atm with H2/O2 as reactants. The slope of the linear region of the potential-current density plot for this case is 0.15 ohm-sq cm. With H2/air as reactants and under the same operating conditions, mass transport limitations are encountered at current densities above 1.4 A/sq cm. Thus, the cell potential at 1 A/sq cm with H2/air as reactants is less than that with H2/O2 as reactants by 40 mV, which is the expected value based on electrode kinetics of the oxygen reduction reaction, and at 2 A/sq cm with H2/air as reactant is less than the corresponding value with H2/O2 as reactants by 250 mV, which is due to the considerably greater mass transport limitations in the former case.

  10. Influence of selected variables on fabrication of Triamcinolone acetonide loaded solid lipid nanoparticles for topical treatment of dermal disorders.

    PubMed

    Pradhan, Madhulika; Singh, Deependra; Singh, Manju Rawat

    2016-01-01

    Aim of the study was to develop solid lipid nanoparticles (SLN) of triamcinolone acetonide (TA) and to study the effect of various process variables in order to optimize the formulation for effective delivery. Drug loaded SLNs were successfully prepared and characterized by TEM, XRD and DSC study. Process variables like surfactant concentration, drug concentration, lipid concentration etc. showed significant effect on the particle size and entrapment efficiency. SLNs exhibited prolonged drug release following Higuchi release kinetics (R(2) = 0.9909). In vitro skin distribution study demonstrated systemic escape of drug from TA loaded SLNs which might eliminate side effects associated with systemic exposure.

  11. Pharmacokinetics study of arteether loaded solid lipid nanoparticles: an improved oral bioavailability in rats.

    PubMed

    Dwivedi, Pankaj; Khatik, Renuka; Khandelwal, Kiran; Taneja, Isha; Raju, Kanumuri Siva Rama; Wahajuddin; Paliwal, Sarvesh Kumar; Dwivedi, Anil Kumar; Mishra, Prabhat Ranjan

    2014-05-15

    Arteether (ART), an artemisinin derivative, is a life saving drug for multiple drug resistant malaria. It has a deliverance effect in Falciparum malaria and cerebral malaria. We have prepared solid lipid nanoparticles (SLN) by high pressure homogenization (HPH) technique. ART-loaded SLN (ART-SLN) has been produced reproducibly with homogeneous particle size. ART-SLN was characterized for their size measured by Zetasizer Nano-ZS, Malvern, UK and by high resolution transmission electron microscopy (HR-TEM) and which was found to be 100 ± 11.2 nm. The maximum percentage entrapment efficiency (%EE) determined with the high-performance liquid chromatography (HPLC) has been found to be 69 ± 4.2% in ART-SLN-3. The release pattern from ART-SLN revealed that the release of ART is slow but time-dependent manner, which is desirable as it will help to protect the acid degradation of ART in stomach. The percentage cytotoxicity of blank SLN has been found within the acceptable range. The pharmacokinetics results indicated that ART-SLN-3 absorption has been significantly enhanced in comparison to ART in aqueous suspension and ART in ground nut oil (GNO) in rats. The % relative bioavailability (RB%) of ART-SLN to the ART in GNO and ART in aqueous suspension in rats was 169.99% and 7461%, respectively which was found to be significantly high in both the cases. From the results, it can be concluded that ART-SLN offers a new approach to improve the oral bioavailability of ART.

  12. Solid Lipid Nanoparticles Loaded with Edaravone for Inner Ear Protection After Noise Exposure

    PubMed Central

    Gao, Gang; Liu, Ya; Zhou, Chang-Hua; Jiang, Ping; Sun, Jian-Jun

    2015-01-01

    Background: Antioxidants and the duration of treatment after noise exposure on hearing recovery are important. We investigated the protective effects of an antioxidant substance, edaravone, and its slow-release dosage form, edaravone solid lipid nanoparticles (SLNs), in steady noise-exposed guinea pigs. Methods: SLNs loaded with edaravone were produced by an ultrasound technique. Edaravone solution or edaravone SLNs were administered by intratympanic or intravenous injection after the 1st day of noise exposure. Guinea pigs were exposed to 110 dB sound pressure level (SPL) noise, centered at 0.25–4.0 kHz, for 4 days at 2 h/d. After noise exposure, the guinea pigs underwent auditory brainstem response (ABR) threshold measurements, reactive oxygen species (ROS) were detected in their cochleas with electron spin resonance (ESR), and outer hair cells (OHCs) were counted with silvernitrate (AgNO3) staining at 1, 4, and 6 days. Results: The ultrasound technique was able to prepare adequate edaravone SLNs with a mean particle size of 93.6 nm and entrapment efficiency of 76.7%. Acoustic stress-induced ROS formation and edaravone exerted a protective effect on the cochlea. Comparisons of hearing thresholds and ROS changes in different animal groups showed that the threshold shift and ROS generation were significantly lower in treated animals than in those without treatment, especially in the edaravone SLN intratympanic injection group. Conclusions: Edaravone SLNs show noticeable slow-release effects and have certain protective effects against noise-induced hearing loss (NIHL). PMID:25591563

  13. Formulation optimization and in vitro skin penetration of spironolactone loaded solid lipid nanoparticles.

    PubMed

    Kelidari, H R; Saeedi, M; Akbari, J; Morteza-Semnani, K; Gill, P; Valizadeh, H; Nokhodchi, A

    2015-04-01

    The aim of the current investigation was to prepare and evaluate the potential use of solid lipid nanoparticles for the dermal delivery of spironolactone (SP). The spironolactone loaded SLN (SP-SLN) was prepared by emulsion-solvent evaporation method followed by ultrasonication. The properties of obtained SLNs were characterized by photon correlation spectroscopy (PCS), scanning tunneling microscopy (STM) and differential scanning calorimetry. FT-IR was also used to investigate any interaction between SP and excipients in the molecular level during the preparation of SLNs. The performance of the formulations was investigated in terms of drug release, skin permeation and also the retention of drug by the skin. The SP-SLNs presented spherical shape with the mean diameter, zeta potential and entrapment efficiency of 88.9 nm, -23.9 mV and 59.86%, respectively. DSC study showed that SP alone encapsulated in SLNs was in the amorphous form. FT-IR analysis revealed that there were hydrogen bond interactions between the SP alone and SLN components. The dissolution results revealed that the drug release from SP-SLNs was at least 4.9 times faster than original SP within the first 30 min. The cumulative amount of SP penetrated through rat skin from SP-SLNs was almost twofold that of the SP alone in 24h after the administration. In vitro permeation studies indicated that SP-SLN may be a promising vector for use in the topical treatment. It can be concluded that SLNs provide good skin permeation for SP and may be a promising carrier for topical delivery of spironolactone offering the biphasic release pattern that might be interesting for topical application resulting in an effective treatment for skin disorders such as acne.

  14. Determination of copper and mercury in phosphate fertilizers employing direct solid sampling analysis and high resolution continuum source graphite furnace atomic absorption spectrometry

    NASA Astrophysics Data System (ADS)

    de Oliveira Souza, Sidnei; François, Luciane Luiza; Borges, Aline Rocha; Vale, Maria Goreti Rodrigues; Araujo, Rennan Geovanny Oliveira

    2015-12-01

    The present study proposes the determination of copper and mercury in phosphate fertilizers by direct solid sampling analysis (SS) employing high resolution continuum source graphite furnace atomic absorption spectrometry (HR-CS GF AAS). For Cu determination, two analytical lines were used: 327.3960 nm and 249.2146 nm. Hg determination was carried out on the line 253.6521 nm and 100 μg KMnO4 was used as chemical modifier. The optimal pyrolysis temperature for Cu determination was 1300 °C. Atomization temperatures for Cu and Hg were 2400 and 1100 °C, respectively. External calibration with aqueous standard solutions was adopted for both elements. The limits of quantification (LoQs) and characteristic mass (m0) obtained for Cu determination were 0.4 μg g- 1 and 1.12 ng, respectively, on line 249.2146 nm, and 64 μg g- 1 and 25 pg on 327.3960 nm. For mercury, LoQ and m0 were 4.8 ng g- 1 and 39 pg, respectively. The accuracy of the proposed methods was confirmed by the analysis of standard reference material (SRM) of Trace Elements in Multi-Nutrient Fertilizer (SRM NIST 695). The precision expressed as relative standard deviation (RSD), was better than 8.2% for Hg and 7.7% for the Cu (n = 5), considered satisfactory for microanalysis in solid sample. Four fertilizer samples acquired in commercial establishments in the city of Salvador, Bahia, Brazil, were analyzed. The optimized analytical methods were simple, fast, accurate, precise and free of spectral interferences for the determination of Cu and Hg in phosphate fertilizer samples by SS-HR-CS GF AAS, avoiding the dissolution of the sample, the use of harmful reagents and the generation of residues.

  15. Mercury's Interior Structure and Geodesy

    NASA Astrophysics Data System (ADS)

    van Hoolst, T.

    2004-12-01

    Interior structure models of Mercury have been calculated with particular focus on the core. Mercury has a very large core, compared to the other terrestrial planets, thought to consist mainly of iron and an unknown amount of sulfur. Thermal evolution models, high pressure data on iron alloys, and the magnetic measurements of Mariner 10 point to a core structure as for the Earth, with a solid inner core and a liquid outer core. We have considered a plausible range in sulfur concentration for the core and constructed Mercury models in different phases of its core evolution, from entirely liquid to entirely solid cores. Data on core material relevant for the pressures and temperatures in Mercury's core is used, and we investigate the effects of sulfur dissolving in the solid inner core. Several geodesy experiments have the potential of providing insight into Mercury's deep interior. Precise measurements of Mercury's obliquity and libration in longitude, along with the harmonic degree 2 gravitational field coefficients will determine both the polar principal moment of inertia of the entire planet and of the mantle, C and Cm, respectively. On the other hand, Mercury's solid body tides, which are the largest of the solar system planets, are very sensitive to the core properties, and will be observed by the MESSENGER and BepiColombo missions. We calculated the moments of inertia C and Cm and the tidal reaction of our Mercury models, and studied their sensitivity to several core parameters.

  16. Spatially Referenced Statistical Assessment of Dissolved-Solids Load Sources and Transport in Streams of the Upper Colorado River Basin

    USGS Publications Warehouse

    Kenney, Terry A.; Gerner, Steven J.; Buto, Susan G.; Spangler, Lawrence E.

    2009-01-01

    The Upper Colorado River Basin (UCRB) discharges more than 6 million tons of dissolved solids annually, about 40 to 45 percent of which are attributed to agricultural activities. The U.S. Department of the Interior estimates economic damages related to salinity in excess of $330 million annually in the Colorado River Basin. Salinity in the UCRB, as measured by dissolved-solids load and concentration, has been studied extensively during the past century. Over this period, a solid conceptual understanding of the sources and transport mechanisms of dissolved solids in the basin has been developed. This conceptual understanding was incorporated into the U.S. Geological Survey Spatially Referenced Regressions on Watershed Attributes (SPARROW) surface-water quality model to examine statistically the dissolved-solids supply and transport within the UCRB. Geologic and agricultural sources of dissolved solids in the UCRB were defined and represented in the model. On the basis of climatic and hydrologic conditions along with data availability, water year 1991 was selected for examination with SPARROW. Dissolved-solids loads for 218 monitoring sites were used to calibrate a dissolved-solids SPARROW model for the UCRB. The calibrated model generally captures the transport mechanisms that deliver dissolved solids to streams of the UCRB as evidenced by R2 and yield R2 values of 0.98 and 0.71, respectively. Model prediction error is approximated at 51 percent. Model results indicate that of the seven geologic source groups, the high-yield sedimentary Mesozoic rocks have the largest yield of dissolved solids, about 41.9 tons per square mile (tons/mi2). Irrigated sedimentary-clastic Mesozoic lands have an estimated yield of 1,180 tons/mi2, and irrigated sedimentary-clastic Tertiary lands have an estimated yield of 662 tons/mi2. Coefficients estimated for the seven landscape transport characteristics seem to agree well with the conceptual understanding of the role they play in the

  17. A practical synthesis of a high-loading solid-supported IBX amide for the oxidation of alcohols.

    PubMed

    Lecarpentier, Patrick; Crosignani, Stefano; Linclau, Bruno

    2005-01-01

    A straightforward three-step synthesis of a solid-supported IBX amide resin was achieved using inexpensive and commercially available 2-iodobenzoic acid chloride and Merrifield resin. A high apparent loading of 0.63 mmol g(-1) was obtained. Oxidation of a range of alcohols to the corresponding carbonyl compounds proved very straightforward using 1.2 equiv of the resin. Recycling of the resin was also possible with minimal loss of activity after two reoxidations.

  18. Improved In Vitro Antileukemic Activity of All-Trans Retinoic Acid Loaded in Cholesteryl Butyrate Solid Lipid Nanoparticles.

    PubMed

    Silva, Elton Luiz; Lima, Flávia Alves; Carneiro, Guilherme; Ramos Jonas Periera; Gomes, Dawidson Assis; de Souza-Fagundes, Elaine Maria; Ferreira, Lucas Antônio Miranda

    2016-02-01

    All-trans retinoic acid, a hydrophobic drug, has become one of the most successful examples of differentiation agents used for treatment of acute promyelocytic leukemia. On the other hand, histone deacetylase inhibitors, such as cholesteryl butyrate, present differentiating activity and.can potentiate action of drugs such as all-trans retinoic acid. Solid lipid nanoparticles represent a promising alternative for administration of hydrophobic drugs such as ATRA. This study aimed to develop, characterize, and evaluate the cytotoxicity of all-trans retinoic acid-loaded solid lipid nanoparticles for leukemia treatment. The influence of in situ formation of an ion pairing between all-trans retinoic acid and lipophilic amines on the characteristics of the particles (size, zeta potential, encapsulation efficiency) was evaluated. Cholesteryl butyrate, a butyric acid donor, was used as a component of the lipid matrix. In vitro activity on cell viability and distribution of cell cycle phases were evaluated for HL-60, Jurkat, and THP-1 cell lines. The encapsulation efficiency of all-trans retinoic acid in cholesteryl butyrate-solid lipid nanoparticles was significantly increased by the presence of the amine. Inhibition of cell viability by all-trans retinoic acid-loaded solid lipid nanoparticles was more pronounced than the free drug. Analysis of the distribution of cell cycle phases also showed increased activity for all-trans retinoic acid-loaded cholesteryl butyrate-solid lipid nanoparticles, with a clear increase in subdiploid DNA content. The ion pair formation in SLN containing cholesteryl butyrate can be explored as a simple and inexpensive strategy to improve the efficacy and bioavail-ability of ATRA in the treatment of the cancer and metabolic diseases in which this retinoid plays an important role. PMID:27433579

  19. Galantamine-loaded solid-lipid nanoparticles for enhanced brain delivery: preparation, characterization, in vitro and in vivo evaluations.

    PubMed

    Misra, Shubham; Chopra, Kanwaljit; Sinha, V R; Medhi, Bikash

    2016-05-01

    Galantamine hydrobromide, a promising acetylcholinesterase inhibitor is reported to be associated with cholinergic side effects. Its poor brain penetration results in lower bioavailability to the target site. With an aim to overcome these limitations, solid-lipid nanoparticulate formulation of galantamine hydrobromide was developed employing biodegradable and biocompatible components. The selected galantamine hydrobromide-loaded solid-lipid nanoparticles offered nanocolloidal with size lower than 100 nm and maximum drug entrapment 83.42 ± 0.63%. In vitro drug release from these spherical drug-loaded nanoparticles was observed to be greater than 90% for a period of 24 h in controlled manner. In vivo evaluations demonstrated significant memory restoration capability in cognitive deficit rats in comparison with naive drug. The developed carriers offered approximately twice bioavailability to that of plain drug. Hence, the galantamine hydrobromide-loaded solid-lipid nanoparticles can be a promising vehicle for safe and effective delivery especially in disease like Alzheimer's. PMID:26405825

  20. Mercury contamination study for flight system safety

    NASA Technical Reports Server (NTRS)

    Gorzynski, C. S., Jr.; Maycock, J. N.

    1972-01-01

    The effects and prevention of possible mercury pollution from the failure of solar electric propulsion spacecraft using mercury propellant were studied from tankage loading of post launch trajector injection. During preflight operations and initial flight mode there is little danger of mercury pollution if proper safety precautions are taken. Any spillage on the loading, mating, transportation, or launch pad areas is obvious and can be removed by vacuum cleaning soil and chemical fixing. Mercury spilled on Cape Kennedy ground soil will be chemically complexed and retained by the sandstone subsoil. A cover layer of sand or gravel on spilled mercury which has settled to the bottom of a water body adjacent to the system operation will control and eliminate the formation of toxic organic mercurials. Mercury released into the earth's atmosphere through leakage of a fireball will be diffused to low concentration levels. However, gas phase reactions of mercury with ozone could cause a local ozone depletion and result in serious ecological hazards.

  1. Activation of the Mercury Laser: A Diode-Pumped Solid-State Laser Driver for Inertial Fusion

    SciTech Connect

    Bayramian, A J; Bibeau, C; Beach, R J; Chanteloup, J C; Ebbers, C A; Kanz, K; Nakano, H; Payne, S A; Powell, H T; Schaffers, K I; Seppala, L; Skulina, K; Smith, L K; Sutton, S B; Zapata, L E

    2001-03-07

    Initial measurements are reported for the Mercury laser system, a scalable driver for rep-rated high energy density physics research. The performance goals include 10% electrical efficiency at 10 Hz and 100 J with a 2-10 ns pulse length. This laser is an angularly multiplexed 4-pass gas-cooled amplifier system based on image relaying to minimize wavefront distortion and optical damage risk at the 10 Hz operating point. The efficiency requirements are fulfilled using diode laser pumping of ytterbium doped strontium fluorapatite crystals.

  2. Combined process for ethanol fermentation at high-solids loading and biogas digestion from unwashed steam-exploded corn stover.

    PubMed

    Wang, Zhen; Lv, Zhe; Du, Jiliang; Mo, Chunling; Yang, Xiushan; Tian, Shen

    2014-08-01

    A combined process was designed for the co-production of ethanol and methane from unwashed steam-exploded corn stover. A terminal ethanol titer of 69.8 g/kg mass weight (72.5%) was achieved when the fed-batch mode was performed at a final solids loading of 35.5% (w/w) dry matter (DM) content. The whole stillage from high-solids ethanol fermentation was directly transferred in a 3-L anaerobic digester. During 52-day single-stage digester operation, the methane productivity was 320 mL CH₄/g volatile solids (VS) with a maximum VS reduction efficiency of 55.3%. The calculated overall product yield was 197 g ethanol + 96 g methane/kg corn stover. This indicated that the combined process was able to improve overall content utilization and extract a greater yield of lignocellulosic biomass compared to ethanol fermentation alone.

  3. Characterization of Solid Polymers, Ceramic Gap Filler, and Closed-Cell Polymer Foam Using Low-Load Test Methods

    NASA Technical Reports Server (NTRS)

    Herring, Helen M.

    2008-01-01

    Various solid polymers, polymer-based composites, and closed-cell polymer foam are being characterized to determine their mechanical properties, using low-load test methods. The residual mechanical properties of these materials after environmental exposure or extreme usage conditions determines their value in aerospace structural applications. In this experimental study, four separate polymers were evaluated to measure their individual mechanical responses after thermal aging and moisture exposure by dynamic mechanical analysis. A ceramic gap filler, used in the gaps between the tiles on the Space Shuttle, was also tested, using dynamic mechanical analysis to determine material property limits during flight. Closed-cell polymer foam, used for the Space Shuttle External Tank insulation, was tested under low load levels to evaluate how the foam's mechanical properties are affected by various loading and unloading scenarios.

  4. A MODELLING FRAMEWORK FOR MERCURY CYCLING IN LAKE MICHIGAN

    EPA Science Inventory

    A time-dependent mercury model was developed to describe mercury cycling in Lake Michigan. The model addresses dynamic relationships between net mercury loadings and the resulting concentrations of mercury species in the water and sediment. The simplified predictive modeling fram...

  5. Naringenin-loaded solid lipid nanoparticles: preparation, controlled delivery, cellular uptake, and pulmonary pharmacokinetics

    PubMed Central

    Ji, Peng; Yu, Tong; Liu, Ying; Jiang, Jie; Xu, Jie; Zhao, Ying; Hao, Yanna; Qiu, Yang; Zhao, Wenming; Wu, Chao

    2016-01-01

    Naringenin (NRG), a flavonoid compound, had been reported to exhibit extensive pharmacological effects, but its water solubility and oral bioavailability are only~46±6 µg/mL and 5.8%, respectively. The purpose of this study is to design and develop NRG-loaded solid lipid nanoparticles (NRG-SLNs) to provide prolonged and sustained drug release, with improved stability, involving nontoxic nanocarriers, and increase the bioavailability by means of pulmonary administration. Initially, a group contribution method was used to screen the best solid lipid matrix for the preparation of SLNs. NRG-SLNs were prepared by an emulsification and low-temperature solidification method and optimized using an orthogonal experiment approach. The morphology was examined by transmission electron microscopy, and the particle size and zeta potential were determined by photon correlation spectroscopy. The total drug content of NRG-SLNs was measured by high-performance liquid chromatography, and the encapsulation efficiency (EE) was determined by Sephadex gel-50 chromatography and high-performance liquid chromatography. The in vitro NRG release studies were carried out using a dialysis bag. The best cryoprotectant to prepare NRG-SLN lyophilized powder for future structural characterization was selected using differential scanning calorimetry, powder X-ray diffraction, and Fourier transform infrared spectroscopy. The short-term stability, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide (MTT) assay, cellular uptake, and pharmacokinetics in rats were studied after pulmonary administration of NRG-SLN lyophilized powder. Glycerol monostearate was selected to prepare SLNs, and the optimal formulation of NRG-SLNs was spherical in shape, with a particle size of 98 nm, a polydispersity index of 0.258, a zeta potential of −31.4 mV, a total drug content of 9.76 mg, an EE of 79.11%, and a cumulative drug release of 80% in 48 hours with a sustained profile. In addition, 5% mannitol (w

  6. Naringenin-loaded solid lipid nanoparticles: preparation, controlled delivery, cellular uptake, and pulmonary pharmacokinetics.

    PubMed

    Ji, Peng; Yu, Tong; Liu, Ying; Jiang, Jie; Xu, Jie; Zhao, Ying; Hao, Yanna; Qiu, Yang; Zhao, Wenming; Wu, Chao

    2016-01-01

    Naringenin (NRG), a flavonoid compound, had been reported to exhibit extensive pharmacological effects, but its water solubility and oral bioavailability are only~46±6 µg/mL and 5.8%, respectively. The purpose of this study is to design and develop NRG-loaded solid lipid nanoparticles (NRG-SLNs) to provide prolonged and sustained drug release, with improved stability, involving nontoxic nanocarriers, and increase the bioavailability by means of pulmonary administration. Initially, a group contribution method was used to screen the best solid lipid matrix for the preparation of SLNs. NRG-SLNs were prepared by an emulsification and low-temperature solidification method and optimized using an orthogonal experiment approach. The morphology was examined by transmission electron microscopy, and the particle size and zeta potential were determined by photon correlation spectroscopy. The total drug content of NRG-SLNs was measured by high-performance liquid chromatography, and the encapsulation efficiency (EE) was determined by Sephadex gel-50 chromatography and high-performance liquid chromatography. The in vitro NRG release studies were carried out using a dialysis bag. The best cryoprotectant to prepare NRG-SLN lyophilized powder for future structural characterization was selected using differential scanning calorimetry, powder X-ray diffraction, and Fourier transform infrared spectroscopy. The short-term stability, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide (MTT) assay, cellular uptake, and pharmacokinetics in rats were studied after pulmonary administration of NRG-SLN lyophilized powder. Glycerol monostearate was selected to prepare SLNs, and the optimal formulation of NRG-SLNs was spherical in shape, with a particle size of 98 nm, a polydispersity index of 0.258, a zeta potential of -31.4 mV, a total drug content of 9.76 mg, an EE of 79.11%, and a cumulative drug release of 80% in 48 hours with a sustained profile. In addition, 5% mannitol (w

  7. High solids loading of aluminum nitride powder in epoxy resin: Dispersion and thermal conductivity

    NASA Astrophysics Data System (ADS)

    Lee, Eunsung

    Most semiconductor devices are now packaged in an epoxy polymer composite, which includes a silica powder filler for reducing the thermal expansion coefficient. However, increased heat output from near-future semiconductors will require higher thermal conductivity fillers such as aluminum nitride powder, instead of silica. This thesis research is intended to apply improved dispersant chemistry, in order to achieve a high volume percentage of AlN powder in epoxy, increasing the thermal conductivity of the composite without causing excessive viscosity before the epoxy monomer is crosslinked. In initial experiments, the dispersibility of aluminum oxide in epoxy monomer resin was better than that of AlN, because of the weaker basicity of oxide surfaces compared with nitride. To improve the dispersibility of AlN, its surface was modified by pretreatment with silane coupling agents. Silane molecules with different head groups were investigated. In those experiments, methylsilane gave lower viscosities than chloro- or methoxysilane, while pretreatments using organic acids increased the viscosity of the AlN dispersion. The viscosity changes and FTIR peak intensity trends suggested that the silane molecules could be adsorbed on AlN surfaces in the form of a monolayer during optimization experiments, and the best silane monolayer coverage on the AlN powder surfaces was achieved with 2 wt% amounts in a 3 hour treatment. A particular phosphate ester was a good second layer dispersant for the AlN-plus-epoxy system. When that dispersant was added onto the silane-treated filler surfaces, the degree of viscosity reduction was dependent on the types of silane coupling agent functional groups. In the optimized results, silane pretreatment followed by dispersant addition was better than either alone. High solids loading, up to 57 vol.%, was achieved with a wide particle size distribution of powder, and the viscosity of that dispersion was 60,000 to 90,000 cps, which easily flowed by

  8. Mercury mass balance in Lake Michigan--the knowns and unknowns

    EPA Science Inventory

    LM2-Mercury, a mercury mass balance model, was developed to simulate and evaluate the transport, fate, and biogeochemical transformations of mercury in Lake Michigan. The model simulates total suspended solids (TSS), disolved organic carbon (DOC), and total, elemental, divalent, ...

  9. Safety profile of solid lipid nanoparticles loaded with rosmarinic acid for oral use: in vitro and animal approaches.

    PubMed

    Madureira, Ana Raquel; Nunes, Sara; Campos, Débora A; Fernandes, João C; Marques, Cláudia; Zuzarte, Monica; Gullón, Beatriz; Rodríguez-Alcalá, Luís M; Calhau, Conceição; Sarmento, Bruno; Gomes, Ana Maria; Pintado, Maria Manuela; Reis, Flávio

    2016-01-01

    Rosmarinic acid (RA) possesses several protective bioactivities that have attracted increasing interest by nutraceutical/pharmaceutical industries. Considering the reduced bioavailability after oral use, effective (and safe) delivery systems are crucial to protect RA from gastrointestinal degradation. This study aims to characterize the safety profile of solid lipid nanoparticles produced with Witepsol and Carnauba waxes and loaded with RA, using in vitro and in vivo approaches, focused on genotoxicity and cytotoxicity assays, redox status markers, hematological and biochemical profile, liver and kidney function, gut bacterial microbiota, and fecal fatty acids composition. Free RA and sage extract, empty nanoparticles, or nanoparticles loaded with RA or sage extract (0.15 and 1.5 mg/mL) were evaluated for cell (lymphocytes) viability, necrosis and apoptosis, and antioxidant/prooxidant effects upon DNA. Wistar rats were orally treated for 14 days with vehicle (control) and with Witepsol or Carnauba nanoparticles loaded with RA at 1 and 10 mg/kg body weight/d. Blood, urine, feces, and several tissues were collected for analysis. Free and loaded RA, at 0.15 mg/mL, presented a safe profile, while genotoxic potential was found for the higher dose (1.5 mg/mL), mainly by necrosis. Our data suggest that both types of nanoparticles are safe when loaded with moderate concentrations of RA, without in vitro genotoxicity and cytotoxicity and with an in vivo safety profile in rats orally treated, thus opening new avenues for use in nutraceutical applications. PMID:27536103

  10. Safety profile of solid lipid nanoparticles loaded with rosmarinic acid for oral use: in vitro and animal approaches

    PubMed Central

    Madureira, Ana Raquel; Nunes, Sara; Campos, Débora A; Fernandes, João C; Marques, Cláudia; Zuzarte, Monica; Gullón, Beatriz; Rodríguez-Alcalá, Luís M; Calhau, Conceição; Sarmento, Bruno; Gomes, Ana Maria; Pintado, Maria Manuela; Reis, Flávio

    2016-01-01

    Rosmarinic acid (RA) possesses several protective bioactivities that have attracted increasing interest by nutraceutical/pharmaceutical industries. Considering the reduced bioavailability after oral use, effective (and safe) delivery systems are crucial to protect RA from gastrointestinal degradation. This study aims to characterize the safety profile of solid lipid nanoparticles produced with Witepsol and Carnauba waxes and loaded with RA, using in vitro and in vivo approaches, focused on genotoxicity and cytotoxicity assays, redox status markers, hematological and biochemical profile, liver and kidney function, gut bacterial microbiota, and fecal fatty acids composition. Free RA and sage extract, empty nanoparticles, or nanoparticles loaded with RA or sage extract (0.15 and 1.5 mg/mL) were evaluated for cell (lymphocytes) viability, necrosis and apoptosis, and antioxidant/prooxidant effects upon DNA. Wistar rats were orally treated for 14 days with vehicle (control) and with Witepsol or Carnauba nanoparticles loaded with RA at 1 and 10 mg/kg body weight/d. Blood, urine, feces, and several tissues were collected for analysis. Free and loaded RA, at 0.15 mg/mL, presented a safe profile, while genotoxic potential was found for the higher dose (1.5 mg/mL), mainly by necrosis. Our data suggest that both types of nanoparticles are safe when loaded with moderate concentrations of RA, without in vitro genotoxicity and cytotoxicity and with an in vivo safety profile in rats orally treated, thus opening new avenues for use in nutraceutical applications. PMID:27536103

  11. Mercury and Your Health

    MedlinePlus

    ... the Risk of Exposure to Mercury Learn About Mercury What is Mercury What is Metallic mercury? Toxicological Profile ToxFAQs Mercury Resources CDC’s National Biomonitoring Program Factsheet on Mercury ...

  12. Analysis of annual dissolved-solids loading from selected natural and irrigated catchments in the Upper Colorado River Basin, 1974-2003

    USGS Publications Warehouse

    Kenney, Terry A.; Gerner, Steven J.; Buto, Susan G.

    2012-01-01

    Dissolved-solids loading from 17 natural catchments and 14 irrigated catchments in the Upper Colorado River Basin was examined for the period from 1974 through 2003. In general, dissolved-solids loading increased and decreased concurrently in natural and irrigated catchments but at different magnitudes. Annually, the magnitude of loading in natural catchments changed about 10 percent more, on average, than in irrigated catchments. Measures of variability, or spread, indicate that natural catchments had 35 percent greater annual variability in loading than irrigated catchments. Precipitation and dissolved-solids loads were positively correlated in natural catchments, and a weak positive correlation was determined for irrigated catchments. A weak negative correlation between temperature and dissolved-solids load was determined for both natural and irrigated catchments. In irrigated catchments, the dissolved-solids load response to an above-average precipitation period from 1982 through 1987 generally lagged behind that in the natural catchments. On average, irrigated catchments with reservoir storage had the largest normalized maximum annual loads during the wet period.

  13. Activation of theMercury Laser System: A Diode-Pumped Solid-State Laser Driver for Inertial Fusion

    SciTech Connect

    Bayramian, A J; Beach, R J; Bibeau, C; Ebbers, C A; Freitas, B L; Kanz, V K; Payne, S A; Schaffers, K I; Skulina, K M; Smith, L K; Tassano, J B

    2001-09-10

    Initial measurements are reported for the Mercury laser system, a scalable driver for rep-rated inertial fusion energy. The performance goals include 10% electrical efficiency at 10 Hz and 100 J with a 2-10 ns pulse length. We report on the first Yb:S-FAP crystals grown to sufficient size for fabricating full size (4 x 6 cm) amplifier slabs. The first of four 160 kW (peak power) diode arrays and pump delivery systems were completed and tested with the following results: 5.5% power droop over a 0.75 ms pulse, 3.95 nm spectral linewidth, far field divergence of 14.0 mrad and 149.5 mrad in the microlensed and unmicrolensed directions respectively, and 83% optical-to-optical transfer efficiency through the pump delivery system.

  14. Magnetic solid phase extraction coupled with inductively coupled plasma mass spectrometry for the speciation of mercury in environmental water and human hair samples.

    PubMed

    Ma, Shishuai; He, Man; Chen, Beibei; Deng, Wenchao; Zheng, Qi; Hu, Bin

    2016-01-01

    In this work, γ-mercaptopropyltrimethoxysilane (γ-MPTS) modified Fe3O4@SiO2 magnetic nanoparticles (MNPs) was successfully prepared, and characterized by Fourier transform infrared spectrometer (FT-IR), Transmission electron microscope (TEM) and Vibrating sample magnetometer (VSM). The sorption performance of the prepared Fe3O4@SiO2@γ-MPTS MNPs towards methylmercury (CH3Hg(+)) and inorganic mercury (Hg(2+)) was investigated. It was found that CH3Hg(+) and Hg(2+) could be simultaneously retained on the prepared Fe3O4@SiO2@γ-MPTS MNPs, and the quantitative elution of CH3Hg(+) and total mercury (THg) was achieved by using 1.5 mol L(-1) HCl containing 0.01% and 3% thiourea (m/v), respectively. And the levels of Hg(2+) were obtained by subtracting CH3Hg(+) from THg. Based on the above facts, a method of magnetic solid phase extraction (MSPE) combined with inductively coupled plasma mass spectrometry (ICP-MS) was developed for the speciation of CH3Hg(+) and Hg(2+). Various experimental parameters affecting MSPE of CH3Hg(+) and Hg(2+) such as pH, eluent, sample volume, and co-existing ions have been studied. Under the optimized conditions, the limits of detection (LODs) for CH3Hg(+) and THg were 1.6 and 1.9 ng L(-1), respectively. The accuracy of the proposed method was validated by analysis of a Certified Reference Material NRCC DORM-2 dogfish muscle, and the determined values are in good agreement with the certified values. The proposed method has also been successfully applied for the speciation of CH3Hg(+) and Hg(2+) in environmental water and human hair samples.

  15. Formulation and characterization of hydrophilic drug diclofenac sodium-loaded solid lipid nanoparticles based on phospholipid complexes technology.

    PubMed

    Liu, Dongfei; Chen, Li; Jiang, Sunmin; Zhu, Shuning; Qian, Yong; Wang, Fengzhen; Li, Rui; Xu, Qunwei

    2014-03-01

    To successfully prepare the diclofenac sodium (DS)-loaded solid lipid nanoparticles (SLNs), phospholipid complexes (PCs) technology was applied here to improve the liposolubility of DS. Solid lipid nanoparticles (SLNs) loaded with phospholipid complexes (PCs) were prepared by the modified emulsion/solvent evaporation method. DS could be solubilized effectively in the organic solvents with the existence of phospholipid and apparent partition coefficient of DS in PCs increased significantly. X-ray diffraction analysis suggested that DS in PCs was either molecularly dispersed or in an amorphous form. However, no significant difference was observed between the Fourier transform infrared spectroscopy (FT-IR) spectra of physical mixture and that of PCs. Particles with small sizes, narrow polydispersity indexes and high entrapment efficiencies could be obtained with the addition of PCs. Furthermore, according to the transmission electron microscopy, a core-shell structure was likely to be formed. The presence of PCs caused the change of zeta potential and retarded the drug release of SLNs, which indicated that phospholipid formed multilayers around the solid lipid core of SLNs. Both FT-IR and differential scanning calorimetry analysis also illustrated that some weak interactions between DS and lipid materials might take place during the preparation of SLNs. In conclusion, the model hydrophilic drug-DS can be formulated into the SLNs with the help of PCs. PMID:24236407

  16. [Mercury poisoning].

    PubMed

    Bensefa-Colas, L; Andujar, P; Descatha, A

    2011-07-01

    Mercury is a widespread heavy metal with potential severe impacts on human health. Exposure conditions to mercury and profile of toxicity among humans depend on the chemical forms of the mercury: elemental or metallic mercury, inorganic or organic mercury compounds. This article aims to reviewing and synthesizing the main knowledge of the mercury toxicity and its organic compounds that clinicians should know. Acute inhalation of metallic or inorganic mercury vapours mainly induces pulmonary diseases, whereas chronic inhalation rather induces neurological or renal disorders (encephalopathy and interstitial or glomerular nephritis). Methylmercury poisonings from intoxicated food occurred among some populations resulting in neurological disorders and developmental troubles for children exposed in utero. Treatment using chelating agents is recommended in case of symptomatic acute mercury intoxication; sometimes it improves the clinical effects of chronic mercury poisoning. Although it is currently rare to encounter situations of severe intoxication, efforts remain necessary to decrease the mercury concentration in the environment and to reduce risk on human health due to low level exposure (dental amalgam, fish contamination by organic mercury compounds…). In case of occupational exposure to mercury and its compounds, some disorders could be compensated in France. Clinicians should work with toxicologists for the diagnosis and treatment of mercury intoxication.

  17. Solid state characterisation of silver sulfadiazine loaded on montmorillonite/chitosan nanocomposite for wound healing.

    PubMed

    Aguzzi, Carola; Sandri, Giuseppina; Bonferoni, Cristina; Cerezo, Pilar; Rossi, Silvia; Ferrari, Franca; Caramella, Carla; Viseras, César

    2014-01-01

    Biopolymer chitosan/montmorillonite nanocomposites loaded with silver sulfadiazine for wound healing purposes were prepared via intercalation solution technique. Structure and morphology of loaded nanocomposites were studied and compared with pure components and unloaded nanocomposites. X-ray diffraction, Fourier transformed infrared spectroscopy, high resolution transmission electron microscopy coupled with energy-dispersion X-ray analysis, thermal and elemental analysis were employed for the characterisation. The results confirmed that the drug was effectively loaded in the three-dimensional nanocomposite structures, in which chitosan chains were adsorbed in monolayers into the clay mineral interlayer spaces.

  18. Mercury in the Pelagic Food Web of Lake Champlain

    PubMed Central

    Chen, Celia; Kamman, Neil; Shanley, James; Chalmers, Ann; Jackson, Brian; Taylor, Vivien; Smeltzer, Eric; Stangel, Pete; Shambaugh, Angela

    2013-01-01

    Lake Champlain continues to experience mercury contamination resulting in public advisories to limit human consumption of top trophic level fish such as walleye. Prior research suggested that mercury levels in biota could be modified by differences in ecosystem productivity as well as mercury loadings. We investigated relationships between mercury in different trophic levels in Lake Champlain. We measured inorganic and methyl mercury in water, seston, and two size fractions of zooplankton from 13 sites representing a range of nutrient loading conditions and productivity. Biomass varied significantly across lake segments in all measured ecosystem compartments in response to significant differences in nutrient levels. Local environmental factors such as alkalinity influenced the partitioning of mercury between water and seston. Mercury incorporation into biota was influenced by the biomass and mercury content of different ecosystem strata. Pelagic fish tissue mercury was a function of fish length and the size of the mercury pool associated with large zooplankton. We used these observations to parameterize a model of mercury transfers in the Lake Champlain food web that accounts for ecosystem productivity effects. Simulations using the mercury trophic transfer model suggest that reductions of 25 to 75% in summertime dissolved eplimnetic total mercury will likely allow fish tissue mercury concentrations to drop to the target level of 0.3 µg g−1 in a 40-cm fish in all lake segments. Changes in nutrient loading and ecosystem productivity in eutrophic segments may delay any response to reduced dissolved mercury and may result in increases in fish tissue mercury. PMID:22193540

  19. Mercury in the pelagic food web of Lake Champlain.

    PubMed

    Miller, Eric K; Chen, Celia; Kamman, Neil; Shanley, James; Chalmers, Ann; Jackson, Brian; Taylor, Vivien; Smeltzer, Eric; Stangel, Pete; Shambaugh, Angela

    2012-04-01

    Lake Champlain continues to experience mercury contamination resulting in public advisories to limit human consumption of top trophic level fish such as walleye. Prior research suggested that mercury levels in biota could be modified by differences in ecosystem productivity as well as mercury loadings. We investigated relationships between mercury in different trophic levels in Lake Champlain. We measured inorganic and methyl mercury in water, seston, and two size fractions of zooplankton from 13 sites representing a range of nutrient loading conditions and productivity. Biomass varied significantly across lake segments in all measured ecosystem compartments in response to significant differences in nutrient levels. Local environmental factors such as alkalinity influenced the partitioning of mercury between water and seston. Mercury incorporation into biota was influenced by the biomass and mercury content of different ecosystem strata. Pelagic fish tissue mercury was a function of fish length and the size of the mercury pool associated with large zooplankton. We used these observations to parameterize a model of mercury transfers in the Lake Champlain food web that accounts for ecosystem productivity effects. Simulations using the mercury trophic transfer model suggest that reductions of 25-75% in summertime dissolved eplimnetic total mercury will likely allow fish tissue mercury concentrations to drop to the target level of 0.3 μg g(-1) in a 40-cm fish in all lake segments. Changes in nutrient loading and ecosystem productivity in eutrophic segments may delay any response to reduced dissolved mercury and may result in increases in fish tissue mercury.

  20. Global and regional contributions to total mercury concentrations in Lake Michigan water

    EPA Science Inventory

    A calibrated mercury component mass balance model, LM2-Mercury, was applied to Lake Michigan to predict mercury concentrations in the lake under different mercury loadings, mercury air concentrations, and management scenarios. Although post-audit data are few, model predictions (...

  1. MODELING MERCURY FATE IN SEVEN GEORGIA WATERSHEDS

    EPA Science Inventory

    Field and modeling studies were conducted in support of total maximum daily loads (TMDLs)for mercury in six south Georgia rivers and the Savannah River. Mercury is introduced to these rivers primarily by atmospheric deposition, with minor point source loadings. To produce mercu...

  2. Effect of sterilization on the physical stability of brimonidine-loaded solid lipid nanoparticles and nanostructured lipid carriers.

    PubMed

    El-Salamouni, Noha S; Farid, Ragwa M; El-Kamel, Amal H; El-Gamal, Safaa S

    2015-12-30

    Nanoparticulate delivery systems have recently been under consideration for topical ophthalmic drug delivery. Brimonidine base-loaded solid lipid nanoparticles and nanostructured lipid carrier formulations were prepared using glyceryl monostearate as solid lipid and were evaluated for their physical stability following sterilization by autoclaving at 121°C for 15min. The objective of this work was to evaluate the effect of autoclaving on the physical appearance, particle size, polydispersity index, zeta potential, entrapment efficiency and particle morphology of the prepared formulations, compared to non-autoclaved ones. Results showed that, autoclaving at 121°C for 15min allowed the production of physically stable formulations in nanometric range, below 500nm suitable for ophthalmic application. Moreover, the autoclaved samples appeared to be superior to non-autoclaved ones, due to their increased zeta potential values, indicating a better physical stability. As well as, increased amount of brimonidine base entrapped in the tested formulations.

  3. Some aspects of the damage kinetics at static loading of a heterogeneous solid under the conditions of constrained deformation

    NASA Astrophysics Data System (ADS)

    Leksovskii, A. M.; Baskin, B. L.; Yakushev, P. N.

    2015-12-01

    The damaging kinetics of a composite system subjected to static loading, which simulates an inhomogeneous body with microductility, and of D16T-B(43%) composite simulating a quasi-brittle solid is analyzed with the acoustic emission method. By using laser interferometry, it is shown on a model sample that mesocracking may cause a short-term change in the plastic strain rate, which two or more orders of magnitude exceeds the change in the creep rate during the usual supramolecular structure reconfiguration. Whether the object will remain functional or acquire damage of the next scale after being subjected to such local "impact" loading depends on the ability of its immediate environment to absorb released energy.

  4. Sulfur polymer stabilization/solidification (SPSS) treatment of mixed waste mercury recovered from environmental restoration activities at BNL

    SciTech Connect

    Kalb, P.; Adams, J.; Milian, L.

    2001-01-29

    Over 1,140 yd{sup 3} of radioactively contaminated soil containing toxic mercury (Hg) and several liters of mixed-waste elemental mercury were generated during a Comprehensive Environmental Response, Compensation and Liability Act (CERCLA) removal action at Brookhaven National Laboratory (BNL). The US Department of Energy's (DOE) Office of Science and Technology Mixed Waste Focus Area (DOE MWFA) is sponsoring a comparison of several technologies that may be used to treat these wastes and similar wastes at BNL and other sites across the DOE complex. This report describes work conducted at BNL on the application and pilot-scale demonstration of the newly developed Sulfur Polymer Stabilization/Solidification (SPSS) process for treatment of contaminated mixed-waste soils containing high concentrations ({approximately} 5,000 mg/L) of mercury and liquid elemental mercury. BNL's SPSS (patent pending) process chemically stabilizes the mercury to reduce vapor pressure and leachability and physically encapsulates the waste in a solid matrix to eliminate dispersion and provide long-term durability. Two 55-gallon drums of mixed-waste soil containing high concentrations of mercury and about 62 kg of radioactive contaminated elemental mercury were successfully treated. Waste loadings of 60 wt% soil were achieved without resulting in any increase in waste volume, while elemental mercury was solidified at a waste loading of 33 wt% mercury. Toxicity Characteristic Leaching Procedure (TCLP) analyses indicate the final waste form products pass current Environmental Protection Agency (EPA) allowable TCLP concentrations as well as the more stringent proposed Universal Treatment Standards. Mass balance measurements show that 99.7% of the mercury treated was successfully retained within the waste form, while only 0.3% was captured in the off gas system.

  5. Studies on thio-substituted polyurethane foam (T-PUF) as a new efficient separation medium for the removal of inorganic/organic mercury from industrial effluents and solid wastes.

    PubMed

    Anjaneyulu, Y; Marayya, R; Rao, T H

    1993-01-01

    Novel thio-substituted flexible polyurethane foam (T-PUF) was synthesised by addition polymerisation of mercaptan with the precursors of an open-cell polyurethane foam, which can be used as a highly selective sorbent for inorganic and organic mercury from complex matrices. The percentage extraction of inorganic mercury was studied at different flow-rates, over a wide pH range at different concentrations ranging from 1 ppm, to 100 ppm. The break-through capacity and total capacity of unmodified and thio-foams were determined for inorganic and organic mercurials. The absorption efficiency of thio-foam was far superior to other sorbent media, such as activated carbon, polymeric ion-exchange resins and reagent-loaded polyurethane foams. It was observed that even at the 1000 ppm level, divalent ions like Cu, Mg, Ca, Zn do not appreciably influence the per cent extraction of inorganic mercury at the 10 ppm level. These matrix levels are the most concentrated ones which are likely to occur, both in local sewage and effluent waters. Further, the efficiency of this foam was sufficiently high at 10-100 ppm levels of Hg, even from 5-10 litres of effluent volumes using 50 g of thio-foam packed into different columns in series. Thio-foams were found to possess excellent abilities to remove and recover mercury even at low levels from industrial effluents and brine mud of chlor-alkali industry after pre-acid extraction. This makes it a highly efficient sorbent for possible application in effluent treatment. Model schemes for the removal and recovery of mercury from industrial effluents and municipal sewage (100-1000 litre) by a dynamic method are proposed and the costs incurred in a full-scale application method are indicated to show that the use of thio-foam could be commercially attractive.

  6. Got Mercury?

    NASA Technical Reports Server (NTRS)

    Meyers, Valerie E.; McCoy, J. Torin; Garcia, Hector D.; James, John T.

    2009-01-01

    Many of the operational and payload lighting units used in various spacecraft contain elemental mercury. If these devices were damaged on-orbit, elemental mercury could be released into the cabin. Although there are plans to replace operational units with alternate light sources, such as LEDs, that do not contain mercury, mercury-containing lamps efficiently produce high quality illumination and may never be completely replaced on orbit. Therefore, exposure to elemental mercury during spaceflight will remain possible and represents a toxicological hazard. Elemental mercury is a liquid metal that vaporizes slowly at room temperature. However, it may be completely vaporized at the elevated operating temperatures of lamps. Although liquid mercury is not readily absorbed through the skin or digestive tract, mercury vapors are efficiently absorbed through the respiratory tract. Therefore, the amount of mercury in the vapor form must be estimated. For mercury releases from lamps that are not being operated, we utilized a study conducted by the New Jersey Department of Environmental Quality to calculate the amount of mercury vapor expected to form over a 2-week period. For longer missions and for mercury releases occurring when lamps are operating, we conservatively assumed complete volatilization of the available mercury. Because current spacecraft environmental control systems are unable to remove mercury vapors, both short-term and long-term exposures to mercury vapors are possible. Acute exposure to high concentrations of mercury vapors can cause irritation of the respiratory tract and behavioral symptoms, such as irritability and hyperactivity. Chronic exposure can result in damage to the nervous system (tremors, memory loss, insomnia, etc.) and kidneys (proteinurea). Therefore, the JSC Toxicology Group recommends that stringent safety controls and verifications (vibrational testing, etc.) be applied to any hardware that contains elemental mercury that could yield

  7. Dual drugs (microRNA-34a and paclitaxel)-loaded functional solid lipid nanoparticles for synergistic cancer cell suppression.

    PubMed

    Shi, Sanjun; Han, Lu; Deng, Li; Zhang, Yanling; Shen, Hongxin; Gong, Tao; Zhang, Zhirong; Sun, Xun

    2014-11-28

    A co-delivery system that can transport cancer related microRNAs and chemotherapeutics to their distinct targets in the tumors is an attractive strategy to eliminate tumor relapse in lung cancer therapy. In this study, we developed a dual-drug delivery system for an endogenous microRNA (miR-34a) and paclitaxel (PTX) for synergistic cancer therapy. PTX (a meiotic inhibitor) and miR-34a were loaded into cationic solid lipid nanoparticles (miSLNs-34a/PTX) which were used to treat murine B16F10-CD44(+) melanoma metastasized to the lungs of mice. This nanoparticle system demonstrated good protection for miR-34a and PTX from degradation in the serum, and had an average size of approximately 220 nm by photon correlation spectroscopy (PCS). In vitro, the parallel activity of PTX and miR-34a show synergistic anticancer efficacy. In vivo, miSLNs-34a/PTX showed passive targetability to the tumor-bearing lung tissues, and was demonstrated to be much more potent in inhibition of B16F10-bearing tumor growth and elimination of cancer cell populations in the lung than single drug-loaded solid lipid nanoparticles. It has been shown that such co-delivery of miR-34a and PTX is promising for enhanced cancer therapy to reduce tumor relapse.

  8. [Process strategy for ethanol production from lignocellulose feedstock under extremely low water usage and high solids loading conditions].

    PubMed

    Zhang, Jian; Chu, Deqiang; Yu, Zhanchun; Zhang, Xiaoxi; Deng, Hongbo; Wang, Xiusheng; Zhu, Zhinan; Zhang, Huaiqing; Dai, Gance; Bao, Jie

    2010-07-01

    The massive water and steam are consumed in the production of cellulose ethanol, which correspondingly results in the significant increase of energy cost, waster water discharge and production cost as well. In this study, the process strategy under extremely low water usage and high solids loading of corn stover was investigated experimentally and computationally. The novel pretreatment technology with zero waste water discharge was developed; in which a unique biodetoxification method using a kerosene fungus strain Amorphotheca resinae ZN1 to degrade the lignocellulose derived inhibitors was applied. With high solids loading of pretreated corn stover, high ethanol titer was achieved in the simultaneous saccharification and fermentation process, and the scale-up principles were studied. Furthermore, the flowsheet simulation of the whole process was carried out with the Aspen plus based physical database, and the integrated process developed was tested in the biorefinery mini-plant. Finally, the core technologies were applied in the cellulose ethanol demonstration plant, which paved a way for the establishment of an energy saving and environment friendly technology of lignocellulose biotransformation with industry application potential.

  9. Time Resolved X-Ray Diffraction of Reactive Solids Under Dynamic Loadings

    NASA Astrophysics Data System (ADS)

    Yoo, Choong-Shik

    2015-06-01

    We present novel time-resolved (TR) x-ray diffraction and TR Raman spectroscopy capable of probing structural and chemical evolutions of solids undergoing chemical and phase transformations. These methods are applicable to a wide range of dynamic experiments to study both single event phenomena of solids under thermal, electric or mechanical impact conditions and non-single event phenomena under dynamic-diamond anvil cell (d-DAC) and high frequency pulse (or ramp) laser-heated DAC. In this talk, relevant technology developments are described with several examples of our recent studies on reactive metals and dense molecular systems, which are synergistic to many proposed activities to develop dynamic synchrotron x-ray diffraction capabilities centered at advanced third and fourth generation light sources.

  10. Novel formulation and evaluation of a Q10-loaded solid lipid nanoparticle cream: in vitro and in vivo studies.

    PubMed

    Farboud, Effat Sadat; Nasrollahi, Saman Ahmad; Tabbakhi, Zahra

    2011-01-01

    Solid lipid nanoparticles (SLNs) of coenzyme Q10 (CoQ10) were formulated by a high-pressure homogenization method. The best formulation of SLN dispersion consisted of 13% lipid (cetyl palmitate or stearic acid), 8% surfactant (Tween 80 or Tego Care 450), and water. Stability tests, particle size analysis, differential scanning calorimetry, transmission electron microscopy, and release study were conducted to find the best formulation. A simple cream of CoQ10 and a cream containing CoQ10-loaded SLNs were prepared and compared on volunteers aged 20-30 years. SLNs with particle size between 50 nm and100 nm exhibited the most suitable stability. In vitro release profiles of CoQ10 from simple cream, SLN alone, and CoQ10-loaded SLN cream showed prolonged release for SLNs compared with the simple cream, whereas there was no significant difference between SLN alone and SLN in cream. In vitro release studies also demonstrated that CoQ10-loaded SLN and SLN cream possessed a biphasic release pattern in comparison with simple cream. In vivo skin hydration and elasticity studies on 25 volunteers suggested good dermal penetration and useful activity of Q10 on skin as a hydratant and antiwrinkle cream.

  11. In vitro characterization of 6-Coumarin loaded solid lipid nanoparticles and their uptake by immunocompetent fish cells.

    PubMed

    Trapani, Adriana; Mandracchia, Delia; Di Franco, Cinzia; Cordero, Héctor; Morcillo, Patricia; Comparelli, Roberto; Cuesta, Alberto; Esteban, Maria Angeles

    2015-03-01

    The primary aim of the present work was to evaluate the in vitro uptake of 6-Coumarin (6COUM) loaded solid lipid nanoparticles (SLN) by two gilthead seabream (Sparus aurata L.) cell types: an established cell line (SAF-1 cells) and the primary cultures of head-kidney (HK)-the main haemopoietic organ in fish, equivalent to mammalian bone marrow-leucocytes. For this purpose, after the physicochemical characterization of SLN, the uptake by those immunocompetent fish cells was evaluated using flow cytometry and confocal microscopy. Concomitantly, the uptake of 6-COUM loaded SLN was compared with that achieved with 6-COUM loaded pectin microparticles (MPs), which were selected as a competitor of the delivery carriers. After SLN and MP physicochemical characterization, the results demonstrated that SAF-1 cells were able to internalize high percentages of 6-COUM SLNs when incubated for 4, 8 and 24h, with the highest SLN concentration tested (10 μg/ml). The ability of HK leucocytes to internalize SLN was also found to vary depending on both incubation time and SLN concentration. The highest values of HK leucocytes internalizing SLN particles (around 16%) were detected at the maximum SLN concentration (20 μg/ml) at incubation times of 4 or 8h. Conversely, HK leucocytes were unable to internalize MPs at any tested concentration and incubation time. A possible mechanism explaining the uptake into cells is proposed. The present work constitutes the first approximation to consider SLN as nanocarriers for delivering biologically active substances to fish.

  12. Active Targeting of Sorafenib: Preparation, Characterization, and In Vitro Testing of Drug-Loaded Magnetic Solid Lipid Nanoparticles.

    PubMed

    Grillone, Agostina; Riva, Eugenio Redolfi; Mondini, Alessio; Forte, Claudia; Calucci, Lucia; Innocenti, Claudia; de Julian Fernandez, Cesar; Cappello, Valentina; Gemmi, Mauro; Moscato, Stefania; Ronca, Francesca; Sacco, Rodolfo; Mattoli, Virgilio; Ciofani, Gianni

    2015-08-01

    Sorafenib is an anticancer drug approved by the Food and Drug Administration for the treatment of hepatocellular and advanced renal carcinoma. The clinical application of sorafenib is promising, yet limited by its severe toxic side effects. The aim of this study is to develop sorafenib-loaded magnetic nanovectors able to enhance the drug delivery to the disease site with the help of a remote magnetic field, thus enabling cancer treatment while limiting negative effects on healthy tissues. Sorafenib and superparamagnetic iron oxide nanoparticles are encapsulated in solid lipid nanoparticles by a hot homogenization technique using cetyl palmitate as lipid matrix. The obtained nanoparticles (Sor-Mag-SLNs) have a sorafenib loading efficiency of about 90% and are found to be very stable in an aqueous environment. Plain Mag-SLNs exhibit good cytocompatibility, whereas an antiproliferative effect against tumor cells (human hepatocarcinoma HepG2) is observed for drug-loaded Sor-Mag-SLNs. The obtained results show that it is possible to prepare stable Sor-Mag-SLNs able to inhibit cancer cell proliferation through the sorafenib cytotoxic action, and to enhance/localize this effect in a desired area thanks to a magnetically driven accumulation of the drug. Moreover, the relaxivity properties observed in water suspensions hold promise for Sor-Mag-SLN tracking through clinical magnetic resonance imaging.

  13. Active Targeting of Sorafenib: Preparation, Characterization, and In Vitro Testing of Drug-Loaded Magnetic Solid Lipid Nanoparticles.

    PubMed

    Grillone, Agostina; Riva, Eugenio Redolfi; Mondini, Alessio; Forte, Claudia; Calucci, Lucia; Innocenti, Claudia; de Julian Fernandez, Cesar; Cappello, Valentina; Gemmi, Mauro; Moscato, Stefania; Ronca, Francesca; Sacco, Rodolfo; Mattoli, Virgilio; Ciofani, Gianni

    2015-08-01

    Sorafenib is an anticancer drug approved by the Food and Drug Administration for the treatment of hepatocellular and advanced renal carcinoma. The clinical application of sorafenib is promising, yet limited by its severe toxic side effects. The aim of this study is to develop sorafenib-loaded magnetic nanovectors able to enhance the drug delivery to the disease site with the help of a remote magnetic field, thus enabling cancer treatment while limiting negative effects on healthy tissues. Sorafenib and superparamagnetic iron oxide nanoparticles are encapsulated in solid lipid nanoparticles by a hot homogenization technique using cetyl palmitate as lipid matrix. The obtained nanoparticles (Sor-Mag-SLNs) have a sorafenib loading efficiency of about 90% and are found to be very stable in an aqueous environment. Plain Mag-SLNs exhibit good cytocompatibility, whereas an antiproliferative effect against tumor cells (human hepatocarcinoma HepG2) is observed for drug-loaded Sor-Mag-SLNs. The obtained results show that it is possible to prepare stable Sor-Mag-SLNs able to inhibit cancer cell proliferation through the sorafenib cytotoxic action, and to enhance/localize this effect in a desired area thanks to a magnetically driven accumulation of the drug. Moreover, the relaxivity properties observed in water suspensions hold promise for Sor-Mag-SLN tracking through clinical magnetic resonance imaging. PMID:26039933

  14. Comparison of solvent-wetted and kneaded l-sulpiride-loaded solid dispersions: Powder characterization and in vivo evaluation.

    PubMed

    Kim, Dong Shik; Choi, Jong Seo; Kim, Dong Wuk; Kim, Kyeong Soo; Seo, Youn Gee; Cho, Kwan Hyung; Kim, Jong Oh; Yong, Chul Soon; Youn, Yu Seok; Lim, Soo-Jeong; Jin, Sung Giu; Choi, Han-Gon

    2016-09-10

    The purpose of this study was to compare the powder properties, solubility, dissolution and oral absorption of solvent-wetted (SWSD) and kneaded (KNSD) l-sulpiride-loaded solid dispersions. The SWSD and KNSD were prepared with silicon dioxide, sodium laurylsulfate and D-α-tocopheryl polyethylene glycol 1000 succinate (TPGS) using a spray dryer and high shear mixer, respectively. Their powder properties, solubility, dissolution and oral absorption were assessed compared to l-sulpiride powder. The drug in SWSD was in the amorphous state; however, in KNSD, it existed in the crystalline state. The SWSD with a drug/sodium laurylsulphate/TPGS/silicon dioxide ratio of 5/1/2/12 gave the higher drug solubility and dissolution compared to the KNSD with the same composition. The oral absorption of drug in the SWSD was 1.4 fold higher than the KNSD and 3.0 fold higher than the l-sulpiride powder (p<0.05) owing to better solubility and reduced crystallinity. Furthermore, the SWSD at the half dose was bioequivalent of commercial l-sulpiride-loaded product in rats. Thus, the SWSD with more improved oral absorption would be recommended as an alternative for the l-sulpiride-loaded oral administration. PMID:27397868

  15. Skin Delivery and in Vitro Biological Evaluation of Trans-Resveratrol-Loaded Solid Lipid Nanoparticles for Skin Disorder Therapies.

    PubMed

    Rigon, Roberta B; Fachinetti, Naiara; Severino, Patrícia; Santana, Maria H A; Chorilli, Marlus

    2016-01-20

    The aim of this study was to evaluate the skin delivery and in vitro biological activity of trans-resveratrol (RES)-loaded solid lipid nanoparticles (SLNs). The SLNs were composed of stearic acid, poloxamer 407, soy phosphatidylcholine (SPC), an aqueous phase and 0.1% RES. The particle size, polydispersity index (PdI) and zeta potential were analyzed by dynamic light scattering (DLS). The SLNs were analyzed by scanning electron microscopy (SEM-FEG) and differential scanning calorimetry (DSC). In vitro RES-SLN skin permeation/retention assays were conducted, and their tyrosinase inhibitory activity was evaluated. An MTT reduction assay was performed on HaCat keratinocytes to determine in vitro cytotoxicity. The formulations had average diameter lower than 200 nm, the addition of SPC promoted increases in PdI in the RES-SLNs, but decreases PdI in the RES-free SLNs and the formulations exhibited zeta potentials smaller than -3 mV. The DSC analysis of the SLNs showed no endothermic peak attributable to RES. Microscopic analysis suggests that the materials formed had nanometric size distribution. Up to 45% of the RES permeated through the skin after 24 h. The RES-loaded SLNs were more effective than kojic acid at inhibiting tyrosinase and proved to be non-toxic in HaCat keratinocytes. The results suggest that the investigated RES-loaded SLNs have potential use in skin disorder therapies.

  16. Solid lipid nanoparticles loaded with iron to overcome barriers for treatment of iron deficiency anemia

    PubMed Central

    Hosny, Khaled Mohamed; Banjar, Zainy Mohammed; Hariri, Amani H; Hassan, Ali Habiballah

    2015-01-01

    According to the World Health Organization, 46% of the world’s children suffer from anemia, which is usually treated with iron supplements such as ferrous sulfate. The aim of this study was to prepare iron as solid lipid nanoparticles, in order to find an innovative way for alleviating the disadvantages associated with commercially available tablets. These limitations include adverse effects on the digestive system resulting in constipation and blood in the stool. The second drawback is the high variability in the absorption of iron and thus in its bioavailability. Iron solid lipid nanoparticles (Fe-SLNs) were prepared by hot homogenization/ultrasonication. Solubility of ferrous sulfate in different solid lipids was measured, and effects of process variables such as the surfactant type and concentration, homogenization and ultrasonication times, and charge-inducing agent on the particle size, zeta potential, and encapsulation efficiency were determined. Furthermore, in vitro drug release and in vivo pharmacokinetics were studied in rabbits. Results indicated that Fe-SLNs consisted of 3% Compritol 888 ATO, 1% Lecithin, 3% Poloxamer 188, and 0.2% dicetylphosphate, with an average particle size of 25 nm with 92.3% entrapment efficiency. In vivo pharmacokinetic study revealed more than fourfold enhanced bioavailability. In conclusion, Fe-SLNs could be a promising carrier for iron with enhanced oral bioavailability. PMID:25609917

  17. Airborne concentrations of metals and total dust during solid catalyst loading and unloading operations at a petroleum refinery.

    PubMed

    Lewis, Ryan C; Gaffney, Shannon H; Le, Matthew H; Unice, Ken M; Paustenbach, Dennis J

    2012-09-01

    Workers handle catalysts extensively at petroleum refineries throughout the world each year; however, little information is available regarding the airborne concentrations and plausible exposures during this type of work. In this paper, we evaluated the airborne concentrations of 15 metals and total dust generated during solid catalyst loading and unloading operations at one of the largest petroleum refineries in the world using historical industrial hygiene samples collected between 1989 and 2006. The total dust and metals, which included aluminum, cadmium, chromium, cobalt, copper, iron, lead, manganese, molybdenum, nickel, platinum, silicon, silver, vanadium, and zinc, were evaluated in relation to the handling of four different types of solid catalysts associated with three major types of catalytic processes. Consideration was given to the known components of the solid catalysts and any metals that were likely deposited onto them during use. A total of 180 analytical results were included in this analysis, representing 13 personal and 54 area samples. Of the long-term personal samples, airborne concentrations of metals ranged from <0.001 to 2.9mg/m(3), and, in all but one case, resulted in concentrations below the current U.S. Occupational Safety and Health Administration's Permissible Exposure Limits and the American Conference of Governmental Industrial Hygienists' Threshold Limit Values. The arithmetic mean total dust concentration resulting from long-term personal samples was 0.31mg/m(3). The data presented here are the most complete set of its kind in the open literature, and are useful for understanding the potential exposures during solid catalyst handling activities at this petroleum refinery and perhaps other modern refineries during the timeframe examined. PMID:22177528

  18. Airborne concentrations of metals and total dust during solid catalyst loading and unloading operations at a petroleum refinery.

    PubMed

    Lewis, Ryan C; Gaffney, Shannon H; Le, Matthew H; Unice, Ken M; Paustenbach, Dennis J

    2012-09-01

    Workers handle catalysts extensively at petroleum refineries throughout the world each year; however, little information is available regarding the airborne concentrations and plausible exposures during this type of work. In this paper, we evaluated the airborne concentrations of 15 metals and total dust generated during solid catalyst loading and unloading operations at one of the largest petroleum refineries in the world using historical industrial hygiene samples collected between 1989 and 2006. The total dust and metals, which included aluminum, cadmium, chromium, cobalt, copper, iron, lead, manganese, molybdenum, nickel, platinum, silicon, silver, vanadium, and zinc, were evaluated in relation to the handling of four different types of solid catalysts associated with three major types of catalytic processes. Consideration was given to the known components of the solid catalysts and any metals that were likely deposited onto them during use. A total of 180 analytical results were included in this analysis, representing 13 personal and 54 area samples. Of the long-term personal samples, airborne concentrations of metals ranged from <0.001 to 2.9mg/m(3), and, in all but one case, resulted in concentrations below the current U.S. Occupational Safety and Health Administration's Permissible Exposure Limits and the American Conference of Governmental Industrial Hygienists' Threshold Limit Values. The arithmetic mean total dust concentration resulting from long-term personal samples was 0.31mg/m(3). The data presented here are the most complete set of its kind in the open literature, and are useful for understanding the potential exposures during solid catalyst handling activities at this petroleum refinery and perhaps other modern refineries during the timeframe examined.

  19. Got Mercury?

    NASA Astrophysics Data System (ADS)

    Meyers, Valerie E.; McCoy, Torin J.; Garcia, Hector D.; James, John T.

    2010-09-01

    Many lamps used in various spacecraft contain elemental mercury, which is efficiently absorbed by the lungs as a vapor. The liquid metal vaporizes slowly at room temperature, but may vaporize completely when lamps are operating. Because current spacecraft environmental control systems are unable to remove mercury vapors, we considered short-term and long-term exposures. We estimated mercury vapor releases from stowed lamps during missions lasting ≤ 30 days, whereas we conservatively assumed complete vaporization from stowed lamps during missions lasting > 30 days and from operating lamps regardless of mission duration. The toxicity of mercury and its lack of removal have led Johnson Space Center’s Toxicology Group to recommend stringent safety controls and verifications for hardware containing elemental mercury that could yield airborne mercury vapor concentrations > 0.1 mg/m3 in the total spacecraft atmosphere for exposures lasting ≤ 30 days, or concentrations > 0.01 mg/m3 for exposures lasting > 30 days.

  20. Assessment of dissolved-solids loading to the Colorado River in the Paradox Basin between the Dolores River and Gypsum Canyon, Utah

    USGS Publications Warehouse

    Shope, Christopher L.; Gerner, Steven J.

    2014-01-01

    Salinity loads throughout the Colorado River Basin have been a concern over recent decades due to adverse impacts on population, natural resources, and regional economics. With substantial financial resources and various reclamation projects, the salt loading to Lake Powell and associated total dissolved-solids concentrations in the Lower Colorado River Basin have been substantially reduced. The Colorado River between its confluence with the Dolores River and Lake Powell traverses a physiographic area where saline sedimentary formations and evaporite deposits are prevalent. However, the dissolved-solids loading in this area is poorly understood due to the paucity of water-quality data. From 2003 to 2011, the U.S. Geological Survey in cooperation with the U.S. Bureau of Reclamation conducted four synoptic sampling events to quantify the salinity loading throughout the study reach and evaluate the occurrence and impacts of both natural and anthropogenic sources. The results from this study indicate that under late-summer base-flow conditions, dissolved-solids loading in the reach is negligible with the exception of the Green River, and that variations in calculated loads between synoptic sampling events are within measurement and analytical uncertainties. The Green River contributed approximately 22 percent of the Colorado River dissolved-solids load, based on samples collected at the lower end of the study reach. These conclusions are supported by water-quality analyses for chloride and bromide, and the results of analyses for the stable isotopes of oxygen and deuterium. Overall, no significant sources of dissolved-solids loading from tributaries or directly by groundwater discharge, with the exception of the Green River, were identified in the study area.

  1. In Vitro and In Vivo Trypanocidal Activity of H2bdtc-Loaded Solid Lipid Nanoparticles

    PubMed Central

    Carneiro, Zumira A.; da S. Maia, Pedro I.; Sesti-Costa, Renata; Lopes, Carla D.; Pereira, Tatiana A.; Milanezi, Cristiane M.; da Silva, Marcelo A. Pereira.; Lopez, Renata F. V.; Silva, João S.; Deflon, Victor M.

    2014-01-01

    The parasite Trypanosoma cruzi causes Chagas disease, which remains a serious public health concern and continues to victimize thousands of people, primarily in the poorest regions of Latin America. In the search for new therapeutic drugs against T. cruzi, here we have evaluated both the in vitro and the in vivo activity of 5-hydroxy-3-methyl-5-phenyl-pyrazoline-1-(S-benzyl dithiocarbazate) (H2bdtc) as a free compound or encapsulated into solid lipid nanoparticles (SLN); we compared the results with those achieved by using the currently employed drug, benznidazole. H2bdtc encapsulated into solid lipid nanoparticles (a) effectively reduced parasitemia in mice at concentrations 100 times lower than that normally employed for benznidazole (clinically applied at a concentration of 400 µmol kg−1 day−1); (b) diminished inflammation and lesions of the liver and heart; and (c) resulted in 100% survival of mice infected with T. cruzi. Therefore, H2bdtc is a potent trypanocidal agent. PMID:24810753

  2. Preparation and characterization of solid lipid nanoparticles loaded with frankincense and myrrh oil.

    PubMed

    Shi, Feng; Zhao, Ji-Hui; Liu, Ying; Wang, Zhi; Zhang, Yong-Tai; Feng, Nian-Ping

    2012-01-01

    The aim of the present study was to prepare solid lipid nanoparticles (SLNs) for the oral delivery of frankincense and myrrh essential oils (FMO). Aqueous dispersions of SLNs were successfully prepared by a high-pressure homogenization method using Compritol 888 ATO as the solid lipid and soybean lecithin and Tween 80 as the surfactants. The properties of the SLNs such as particle size, zeta potential (ZP), and drug encapsulation efficiency (EE) were investigated. The morphology of SLNs was observed by transmission electron microscopy (TEM). The crystallinity of the formulation was analyzed by differential scanning calorimetry (DSC) and X-ray diffraction (XRD). In addition, drug evaporation release and antitumor activity were also studied. Round SLNs with a mean size of 113.3 ± 3.6 nm, a ZP of -16.8 ± 0.4 mV, and an EE of 80.60% ± 1.11% were obtained. DSC and XRD measurements revealed that less ordered structures were formed in the inner cores of the SLN particles. Evaporation loss of the active components in FMO could be reduced in the SLNs. Furthermore, the SLN formulation increased the antitumor efficacy of FMO in H22-bearing Kunming mice. Hence, the presented SLNs can be used as drug carriers for hydrophobic oil drugs extracted from traditional Chinese medicines. PMID:22619540

  3. Preparation and characterization of solid lipid nanoparticles loaded with frankincense and myrrh oil

    PubMed Central

    Shi, Feng; Zhao, Ji-Hui; Liu, Ying; Wang, Zhi; Zhang, Yong-Tai; Feng, Nian-Ping

    2012-01-01

    The aim of the present study was to prepare solid lipid nanoparticles (SLNs) for the oral delivery of frankincense and myrrh essential oils (FMO). Aqueous dispersions of SLNs were successfully prepared by a high-pressure homogenization method using Compritol 888 ATO as the solid lipid and soybean lecithin and Tween 80 as the surfactants. The properties of the SLNs such as particle size, zeta potential (ZP), and drug encapsulation efficiency (EE) were investigated. The morphology of SLNs was observed by transmission electron microscopy (TEM). The crystallinity of the formulation was analyzed by differential scanning calorimetry (DSC) and X-ray diffraction (XRD). In addition, drug evaporation release and antitumor activity were also studied. Round SLNs with a mean size of 113.3 ± 3.6 nm, a ZP of −16.8 ± 0.4 mV, and an EE of 80.60% ± 1.11% were obtained. DSC and XRD measurements revealed that less ordered structures were formed in the inner cores of the SLN particles. Evaporation loss of the active components in FMO could be reduced in the SLNs. Furthermore, the SLN formulation increased the antitumor efficacy of FMO in H22-bearing Kunming mice. Hence, the presented SLNs can be used as drug carriers for hydrophobic oil drugs extracted from traditional Chinese medicines. PMID:22619540

  4. Augmented finite-element method for arbitrary cracking and crack interaction in solids under thermo-mechanical loadings.

    PubMed

    Jung, J; Do, B C; Yang, Q D

    2016-07-13

    In this paper, a thermal-mechanical augmented finite-element method (TM-AFEM) has been proposed, implemented and validated for steady-state and transient, coupled thermal-mechanical analyses of complex materials with explicit consideration of arbitrary evolving cracks. The method permits the derivation of explicit, fully condensed thermal-mechanical equilibrium equations which are of mathematical exactness in the piece-wise linear sense. The method has been implemented with a 4-node quadrilateral two-dimensional (2D) element and a 4-node tetrahedron three-dimensional (3D) element. It has been demonstrated, through several numerical examples that the new TM-AFEM can provide significantly improved numerical accuracy and efficiency when dealing with crack propagation problems in 2D and 3D solids under coupled thermal-mechanical loading conditions. This article is part of the themed issue 'Multiscale modelling of the structural integrity of composite materials'. PMID:27242303

  5. Methods for data reduction and loads analysis of Space Shuttle Solid Rocket Booster model water impact tests

    NASA Technical Reports Server (NTRS)

    1976-01-01

    The methodology used to predict full scale space shuttle solid rocket booster (SRB) water impact loads from scale model test data is described. Tests conducted included 12.5 inch and 120 inch diameter models of the SRB. Geometry and mass characteristics of the models were varied in each test series to reflect the current SRB baseline configuration. Nose first and tail first water entry modes were investigated with full-scale initial impact vertical velocities of 40 to 120 ft/sec, horizontal velocities of 0 to 60 ft/sec., and off-vertical angles of 0 to plus or minus 30 degrees. The test program included a series of tests with scaled atmospheric pressure.

  6. Wide-range simulation of elastoplastic wave fronts and failure of solids under high-speed loading

    SciTech Connect

    Saveleva, Natalia Bayandin, Yuriy Naimark, Oleg

    2015-10-27

    The aim of this paper is numerical study of deformation processes and failure of vanadium under shock-wave loading. According developed statistical theory of solid with mesoscopic defects the constitutive equations were proposed in terms of two structural variables characterizing behavior of defects ensembles: defect density tensor and structural scaling parameter. On the basis of wide-range constitutive equations the mathematical model of deformation behavior and failure of vanadium was developed taking into account the bond relaxation mechanisms, multistage of fracture and nonlinearity kinetic of defects. Results of numerical simulation allow the description of the major effects of shock wave propagation (elastic precursor decay, grow of spall strength under grow strain rate)

  7. Support of long-wavelength topography on Mercury inferred from MESSENGER measurements of gravity and topography

    NASA Astrophysics Data System (ADS)

    James, Peter B.; Zuber, Maria T.; Phillips, Roger J.; Solomon, Sean C.

    2015-02-01

    To explore the mechanisms of support of surface topography on Mercury, we have determined the admittances and correlations of topography and gravity in Mercury's northern hemisphere from measurements obtained by NASA's MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft. These admittances and correlations can be interpreted in the context of a number of theoretical scenarios, including flexural loading and dynamic flow. We find that long-wavelength (spherical harmonic degree l < 15) surface topography on Mercury is primarily supported through a combination of crustal thickness variations and deep mass anomalies. The deep mass anomalies may be interpreted either as lateral variations in mantle density or as relief on compositional interfaces. Domical topographic swells are associated with high admittances and are compensated at 300-400 km depth in the lower reaches of Mercury's mantle. Quasi-linear topographic rises are primarily associated with shallow crustal compensation and are weakly correlated with positive mass anomalies in the mantle. The center of the Caloris basin features some of the thinnest crust on the planet, and the basin is underlain by a large negative mass anomaly. We also explore models of dynamic flow in the presence of compositional stratification above the liquid core. If there is substantial compositional stratification in Mercury's solid outer shell, relaxation of perturbed compositional interfaces may be capable of creating and sustaining long-wavelength topography.

  8. Mercury's core evolution

    NASA Astrophysics Data System (ADS)

    Deproost, Marie-Hélène; Rivoldini, Attilio; Van Hoolst, Tim

    2016-10-01

    Remote sensing data of Mercury's surface by MESSENGER indicate that Mercury formed under reducing conditions. As a consequence, silicon is likely the main light element in the core together with a possible small fraction of sulfur. Compared to sulfur, which does almost not partition into solid iron at Mercury's core conditions and strongly decreases the melting temperature, silicon partitions almost equally well between solid and liquid iron and is not very effective at reducing the melting temperature of iron. Silicon as the major light element constituent instead of sulfur therefore implies a significantly higher core liquidus temperature and a decrease in the vigor of compositional convection generated by the release of light elements upon inner core formation.Due to the immiscibility in liquid Fe-Si-S at low pressure (below 15 GPa), the core might also not be homogeneous and consist of an inner S-poor Fe-Si core below a thinner Si-poor Fe-S layer. Here, we study the consequences of a silicon-rich core and the effect of the blanketing Fe-S layer on the thermal evolution of Mercury's core and on the generation of a magnetic field.

  9. Combination of high solids loading pretreatment and ethanol fermentation of whole slurry of pretreated rice straw to obtain high ethanol titers and yields.

    PubMed

    Jung, Young Hoon; Park, Hyun Min; Kim, Dong Hyun; Park, Yong-Cheol; Seo, Jin-Ho; Kim, Kyoung Heon

    2015-12-01

    In cellulosic ethanol production using lignocellulose, an increase in biomass solids loading during the pretreatment process significantly affects the final ethanol titer and the production cost. In this study, pretreatment using rice straw at high solids loading (20% (w/v)) was evaluated, using maleic acid as a catalyst. After pretreatment at optimal conditions of 190°C, 20 min, and 0.2% or 5% (w/v) maleic acid, the highest enzymatic digestibility obtained was over 80%. Simultaneous saccharification and fermentation (SSF) of the whole slurry of pretreated rice straw in the presence of activated carbon to separate inhibitory compounds generated a high ethanol yield of 62.8%, based on the initial glucan in unpretreated rice straw. These findings suggest that high solids loading pretreatment using maleic acid and SSF of the whole slurry of pretreated rice straw can be combined to improve the process economics of ethanol production.

  10. Combination of high solids loading pretreatment and ethanol fermentation of whole slurry of pretreated rice straw to obtain high ethanol titers and yields.

    PubMed

    Jung, Young Hoon; Park, Hyun Min; Kim, Dong Hyun; Park, Yong-Cheol; Seo, Jin-Ho; Kim, Kyoung Heon

    2015-12-01

    In cellulosic ethanol production using lignocellulose, an increase in biomass solids loading during the pretreatment process significantly affects the final ethanol titer and the production cost. In this study, pretreatment using rice straw at high solids loading (20% (w/v)) was evaluated, using maleic acid as a catalyst. After pretreatment at optimal conditions of 190°C, 20 min, and 0.2% or 5% (w/v) maleic acid, the highest enzymatic digestibility obtained was over 80%. Simultaneous saccharification and fermentation (SSF) of the whole slurry of pretreated rice straw in the presence of activated carbon to separate inhibitory compounds generated a high ethanol yield of 62.8%, based on the initial glucan in unpretreated rice straw. These findings suggest that high solids loading pretreatment using maleic acid and SSF of the whole slurry of pretreated rice straw can be combined to improve the process economics of ethanol production. PMID:26461793

  11. Enhanced oxygen reduction activity and solid oxide fuel cell performance with a nanoparticles-loaded cathode.

    PubMed

    Zhang, Xiaomin; Liu, Li; Zhao, Zhe; Tu, Baofeng; Ou, Dingrong; Cui, Daan; Wei, Xuming; Chen, Xiaobo; Cheng, Mojie

    2015-03-11

    Reluctant oxygen-reduction-reaction (ORR) activity has been a long-standing challenge limiting cell performance for solid oxide fuel cells (SOFCs) in both centralized and distributed power applications. We report here that this challenge has been tackled with coloading of (La,Sr)MnO3 (LSM) and Y2O3 stabilized zirconia (YSZ) nanoparticles within a porous YSZ framework. This design dramatically improves ORR activity, enhances fuel cell output (200-300% power improvement), and enables superior stability (no observed degradation within 500 h of operation) from 600 to 800 °C. The improved performance is attributed to the intimate contacts between nanoparticulate YSZ and LSM particles in the three-phase boundaries in the cathode.

  12. Preparation and characterization of solid lipid nanoparticles loaded with total flavones of Hippophae rhamnoides (TFH).

    PubMed

    Wang, Dongkai; Zhao, Peng; Cuia, Fude; Li, Xiang

    2007-01-01

    Solid lipid nanoparticles (SLNs) containing total flavones of Hippophae rhamnoides (TFH) were prepared by high-pressure homogenization (HPH), by both hot HPH and cold HPH. The influence of process parameters (lipid matrix, lipid concentration, carbohydrate type and its concentration) on the SLN size distribution, zeta potential, entrapment efficiency, crystal form, and in vitro release profile was investigated. The highest entrapment efficiency for TFH, at around 93%, was found for SLNs composed of TFH/Compritol 888 ATO in a 1:30 molar ratio and made by cold HPH. The advantages of TFH SLNs are the improved oral bioavailability of TFH and the prolonged mean retention time and drug release time. PMID:17479719

  13. The addition of accessory enzymes enhances the hydrolytic performance of cellulase enzymes at high solid loadings.

    PubMed

    Hu, Jinguang; Chandra, Richard; Arantes, Valdeir; Gourlay, Keith; van Dyk, J Susan; Saddler, Jack N

    2015-06-01

    The pretreatment process used and the nature of the biomass feedstock will influence the role that accessory enzymes can play in synergistically interacting with cellulases to effectively deconstruct the substrate. The work reported here assessed the possible boosting effects of the xylanase and lytic polysaccharide monooxygenase (AA9, formerly known as GH61) on the hydrolytic potential of cellulase enzyme mixtures during hydrolysis of steam pretreated poplar and corn stover at high (10-20% w/v) substrate concentrations. A higher proportion of xylanase was required when the substrate had a relatively high xylan content and at high substrate concentrations. In contrast, a relatively small amount of AA9 (about 2 mg/g cellulose) was enough, regardless of the nature or concentration of the substrate. The overall protein loading required to achieve effective hydrolysis of high concentrations of pretreated biomass substrates could be substantially reduced by optimizing the ratio of enzymes in the "cellulase" mixture.

  14. Translocation of mercury and microbial adaptation in a model aquatic system

    SciTech Connect

    Titus, J.A.; Parsons, J.E.; Pfister, R.M.

    1980-09-01

    Higher levels of mercury-resistant bacteria have been found in mercury-contaminated sediments than in sediments containing low levels of mercury. The work described in this report was undertaken to investigate the movement of mercury (initially as Hg/sup 0/) through components of an aquarium model aquatic system. Changes in mercury-resistant levels of bacterial populations were followed with increasing sediment mercury load.

  15. Miconazole-loaded solid lipid nanoparticles: formulation and evaluation of a novel formula with high bioavailability and antifungal activity

    PubMed Central

    Aljaeid, Bader Mubarak; Hosny, Khaled Mohamed

    2016-01-01

    Background and objective Miconazole is a broad-spectrum antifungal drug that has poor aqueous solubility (<1 µg/mL); as a result, a reduction in its therapeutic efficacy has been reported. The aim of this study was to formulate and evaluate miconazole-loaded solid lipid nanoparticles (MN-SLNs) for oral administration to find an innovative way to alleviate the disadvantages associated with commercially available capsules. Methods MN-SLNs were prepared by hot homogenization/ultrasonication. The solubility of miconazole in different solid lipids was measured. The effect of process variables, such as surfactant types, homogenization and ultrasonication times, and the charge-inducing agent on the particle size, zeta potential, and encapsulation efficiency were determined. Furthermore, in vitro drug release, antifungal activity against Candida albicans, and in vivo pharmacokinetics were studied in rabbits. Results The MN-SLN, consisting of 1.5% miconazole, 2% Precirol ATO5, 2.5% Cremophor RH40, 0.5% Lecinol, and 0.1% Dicetylphosphate, had an average diameter of 23 nm with a 90.2% entrapment efficiency. Furthermore, the formulation of MN-SLNs enhanced the antifungal activity compared with miconazole capsules. An in vivo pharmacokinetic study revealed that the bioavailability was enhanced by >2.5-fold. Conclusion MN-SLN was more efficient in the treatment of candidiasis with enhanced oral bioavailability and could be a promising carrier for the oral delivery of miconazole. PMID:26869787

  16. Stability of paclitaxel-loaded solid lipid nanoparticles in the presence of 2-hydoxypropyl-β-cyclodextrin.

    PubMed

    Baek, Jong-Suep; Kim, Bo-Sik; Puri, Anu; Kumar, K; Cho, Cheong-Weon

    2016-06-01

    Paclitaxel (PTX)-loaded solid lipid nanoparticles without hydroxyl-β-cyclodextrin (PS) or with hydroxypropyl-β-cyclodextrin (PSC) were prepared by hot-melted sonication. Biocompatible and biodegradable stearic acid was used to produce the solid matrix. The stability of PS and PSC was assessed at different temperatures. Drug stability, as assessed by encapsulation efficiency (EE; %), particle size, and the polydispersity index (PDI), was examined and in vitro release of PTX from PS or PSC for up to 180 days was assessed. After 180 days of storage at 25 °C, no significant change in particle size, PDI, or EE of PS or PSC was observed. PS and PSC displayed similar sustained PTX release patterns. The particle size, PDI, EE, PTX release profile, and cytotoxicity of PS changed significantly with increasing incubation time, whereas those of PSC showed no significant change, when samples were stored at 40 ± 2 °C. PSC was more stable than PS in plasma with regard to particle size and PDI. These results demonstrate that PSC could be a promising formulation to increase drug stability. PMID:27146520

  17. Deformation Behavior Immediately After Indentation Load Change in Ultrafine-Grained Al-Mg Solid Solution Alloys

    NASA Astrophysics Data System (ADS)

    Takagi, Hidenari; Fujiwara, Masami

    2016-06-01

    Instrumented indentation tests were performed to study how grain boundaries and solute atoms affect creep and instantaneous plastic deformation in ultrafine-grained (UFG) Al-Mg solid solution alloys with average grain size d = 0.3 - 1.0 μm at T = 373 K. In the results for Al-1.0 mol% Mg, the degree of instantaneous plastic displacement generated with a rapid increase in the load was smaller when the grain diameter was smaller. On the other hand, creep occurs more readily in materials with a smaller grain diameter. When the load was rapidly decreased during creep, the indenter displacement gradually decreased over time. The degree of reverse creep that occurs is greater when the grain diameter is smaller. In light of these test results and reports in the related literature, reverse creep is thought to occur because of inverted movement of piled-up dislocations near the grain boundaries. For the case of Al- xMg ( x = 0.5, 1.0, 2.0 mol%), the results show that as the solute concentration increases, the occurrence of instantaneous plastic deformation, creep, and reverse creep becomes less likely. Overall, the results indicate that the plastic deformation behavior obtained by the testing conditions of present study for UFG Al-Mg alloys could be explained based on understanding of the behavior of course-grained materials.

  18. Effect of liquid-to-solid lipid ratio on characterizations of flurbiprofen-loaded solid lipid nanoparticles (SLNs) and nanostructured lipid carriers (NLCs) for transdermal administration.

    PubMed

    Song, Aihua; Zhang, Xiaoshu; Li, Yanting; Mao, Xinjuan; Han, Fei

    2016-08-01

    The aim of this study is to evaluate the effect of liquid-to-solid lipid ratio on properties of flurbiprofen-loaded solid lipid nanoparticles (SLNs) and nanostructured lipid carriers (NLCs), and to clarify the superiority of NLCs over SLNs for transdermal administration. Particle size, zeta potential, drug encapsulation efficiency, in vitro occlusion factor, differential scanning calorimetry, X-ray diffractometry, in vitro percutaneous permeation profile, and stability of SLNs and NLCs were compared. Particle size, zeta potential, drug encapsulation efficiency, in vitro occlusion factor, and in vitro percutaneous permeation amount of the developed NLCs were all <200 nm, < -20 mV, >78%, >35, and >240 μg/cm(2), respectively, however, for SLNs were 280 nm, -29.11 mV, 63.2%, 32.54, and 225.9 μg/cm(2), respectively. After 3 months storage at 4 °C and 25 °C, almost no significant differences between the evaluated parameters of NLCs were observed. However, for SLNs, particle size was increased to higher than 300 nm (4 °C and 25 °C), drug encapsulation efficiency was decreased to 51.2 (25 °C), in vitro occlusion factor was also decreased to lower than 25 (4 °C and 25 °C), and the cumulative amount was decreased to 148.9 μg/cm(2) (25 °C) and 184.4 μg/cm(2) (4 °C), respectively. And DSC and XRD studies indicated that not only the crystalline peaks of the encapsulated flurbiprofen disappeared but also obvious difference between samples and bulk Compritol® ATO 888 was seen. It could be concluded that liquid-to-solid lipid ratio has significant impact on the properties of SLNs and NLCs, and NLCs showed better stability than SLNs. Therefore, NLCs might be a better option than SLNs for transdermal administration.

  19. Effect of the Paradox Valley Unit on the dissolved-solids load of the Dolores River near Bedrock, Colorado, 1988-2001

    USGS Publications Warehouse

    Chafin, Daniel T.

    2003-01-01

    Discharge of brine with an average dissolved-solids concentration of about 256,000 milligrams per liter from alluvium in Paradox Valley, a collapsed salt anticline, substantially increases the dissolved-solids load of the Dolores River. In 1996, the Bureau of Reclamation began operation of the Paradox Valley Unit, a series of brine-withdrawal wells completed in alluvium along the Dolores River and a deep-injection well for the brine, to decrease flow of brine into the river. This report presents the findings of a study to determine the effectiveness of the Paradox Valley Unit from 1988 through September 2001. Differences in dissolved-solids load of the Dolores River between two gaging stations, one upstream and one downstream from the Paradox Valley Unit, indicate that an average dissolved-solids load of about 313 tons per day (an annual average of about 115,000 tons) was contributed by brine inflow to the Dolores River before operation of the Paradox Valley Unit began in July 1996. By September 30, 2001, the dissolved-solids load contributed by brine had declined to an average of about 29 tons per day? a decrease of about 90 percent. This decrease might have been facilitated by a decrease in precipitation and streamflow into the Paradox Valley during the last few years of the assessed period.

  20. EP-toxicity testing of mercury removal resin grout

    SciTech Connect

    Mersman, K.E.

    1984-07-18

    To determine which category a waste will fit into, the EPA requires a classification test. The test, EP-toxicity, consists of a physical integrity test followed by an extraction. For the case of the mercury removal resin grout, the mercury concentration in the extract cannot exceed 0.2 mg/L if the waste is to be classified as ``solid waste.`` Otherwise, the waste is classified as ``hazardous.`` Simulated process solutions were used to load the mercury removal resin. The resin was solidified with the addition of cement and water using a formulation based on grout formulations typically used to solidify power reactor ion exchange resins. Envirodyne Engineers of St. Louis, Missouri, an EPA sanctioned laboratory, performed the EP-toxicity test for the two samples. One sample was a blank which was made with unloaded resin. For the formulation tested, the EP-toxicity test results showed that the mercury removal resin grout does not fit into the ``hazardous waste`` category.

  1. A Spectral Finite Element Approach to Modeling Soft Solids Excited with High-Frequency Harmonic Loads

    PubMed Central

    Brigham, John C.; Aquino, Wilkins; Aguilo, Miguel A.; Diamessis, Peter J.

    2010-01-01

    An approach for efficient and accurate finite element analysis of harmonically excited soft solids using high-order spectral finite elements is presented and evaluated. The Helmholtz-type equations used to model such systems suffer from additional numerical error known as pollution when excitation frequency becomes high relative to stiffness (i.e. high wave number), which is the case, for example, for soft tissues subject to ultrasound excitations. The use of high-order polynomial elements allows for a reduction in this pollution error, but requires additional consideration to counteract Runge's phenomenon and/or poor linear system conditioning, which has led to the use of spectral element approaches. This work examines in detail the computational benefits and practical applicability of high-order spectral elements for such problems. The spectral elements examined are tensor product elements (i.e. quad or brick elements) of high-order Lagrangian polynomials with non-uniformly distributed Gauss-Lobatto-Legendre nodal points. A shear plane wave example is presented to show the dependence of the accuracy and computational expense of high-order elements on wave number. Then, a convergence study for a viscoelastic acoustic-structure interaction finite element model of an actual ultrasound driven vibroacoustic experiment is shown. The number of degrees of freedom required for a given accuracy level was found to consistently decrease with increasing element order. However, the computationally optimal element order was found to strongly depend on the wave number. PMID:21461402

  2. Cefuroxime axetil loaded solid lipid nanoparticles for enhanced activity against S. aureus biofilm.

    PubMed

    Singh, Bhupender; Vuddanda, Parameswara Rao; M R, Vijayakumar; Kumar, Vinod; Saxena, Preeti S; Singh, Sanjay

    2014-09-01

    The present research work is focused on the development of solid lipid nanoparticles of cefuroxime axetil (CA-SLN) for its enhanced inhibitory activity against Staphylococcus aureus produced biofilm. CA-SLN was prepared by solvent emulsification/evaporation method using single lipid (stearic acid (SA)) and binary lipids (SA and tristearin (TS)). Process variables such as volume of dispersion medium, concentration of surfactant, homogenization speed and time were optimized. The prepared SLN were characterized for encapsulation efficiency, drug polymer interaction studies (DSC and FT-IR), shape and surface morphology (SEM and AFM), in vitro drug release, stability studies and in vitro anti biofilm activity against S. aureus biofilm. Among the process variables, increased volume of dispersion medium, homogenization speed and time led to increase in particle size whereas increase in surfactant concentration decreased the particle size. SLN prepared using binary lipids exhibited higher entrapment efficiency than the single lipid. DSC and FT-IR studies showed no incompatible interaction between drug and excipients. CA-SLN showed two folds higher anti-biofilm activity in vitro than pristine CA against S. aureus biofilm.

  3. Net biomass production under complete solids retention in high organic load activated sludge process.

    PubMed

    Amanatidou, Elisavet; Samiotis, Georgios; Bellos, Dimitrios; Pekridis, George; Trikoilidou, Eleni

    2015-04-01

    The effect of complete solids retention on net biomass production, at a slaughterhouse's activated sludge wastewater treatment process, was studied for 425 days. The process reached equilibrium after 150 days. In equilibrium phase, and until the end of the study, relative constant MLVSS to MLSS ratio, low food to microorganisms ratio (F/M), low substrate utilization rate (SUR) and negligible observed sludge yield (Y obs) were measured. Y obs fluctuated between positive and negative values (± 0.03 gVSS gCOD(-1)), tending zero mean values, and leading to the conclusion that zero net sludge growth can be achieved. The high BOD ultimate/COD ratio and the zero sludge accumulation, leads to the conclusion that all fractions of organic matter, including cell debris, are biodegradable. The results were verified by comparing the measured Y obs values and those predicted using a conventional activated sludge model (ASM) and a modified ASM that incorporates the slow hydrolysis concept of the unbiodegradable compounds.

  4. Safranal-loaded solid lipid nanoparticles: evaluation of sunscreen and moisturizing potential for topical applications

    PubMed Central

    Khameneh, Bahman; Halimi, Vahid; Jaafari, Mahmoud Reza; Golmohammadzadeh, Shiva

    2015-01-01

    Objective(s): In the current study, sunscreen and moisturizing properties of solid lipid nanoparticle (SLN)-safranal formulations were evaluated. Materials and Methods: Series of SLN were prepared using glyceryl monostearate, Tween 80 and different amounts of safranal by high shear homogenization, and ultrasound and high-pressure homogenization (HPH) methods. SLN formulations were characterized for size, zeta potential, morphology, thermal properties, and encapsulation efficacy. The Sun Protection Factor (SPF) of the products was determined in vitro using transpore tape. The moisturizing activity of the products was also evaluated by corneometer. Results: The SPF of SLN-safranal formulations was increased when the amount of safranal increased. Mean particle size for all formulas was approximately 106 nm by probe sonication and 233 nm using HPH method. The encapsulation efficiency of safranal was around 70% for all SLN-safranal formulations. Conclusion: The results conclude that SLN-safranal formulations were found to be effective for topical delivery of safranal and succeeded in providing appropriate sunscreen properties. PMID:25810877

  5. Design and Evaluation of Voriconazole Loaded Solid Lipid Nanoparticles for Ophthalmic Application.

    PubMed

    Khare, Anubha; Singh, Inderbir; Pawar, Pravin; Grover, Kanchan

    2016-01-01

    Voriconazole is a second-generation antifungal agent with excellent broad spectrum of antifungal activity commercially available for oral and intravenous administration. Systemic administration of voriconazole is associated with side effects including visual and hepatic abnormalities. This study assessed the feasibility of using solid lipid nanoparticles for ocular delivery of voriconazole adopting stearic acid as lipidic material, tween 80 as a stabilizer, and Carbopol 934 as controlled release agent and for increasing the precorneal residence time in eye. The systems were prepared using two different methods, that is, ultrasonication method and microemulsion technique. The results indicated that the larger particle size of SLNs was found with microemulsion technique (308 ± 3.52 nm to 343 ± 3.51) compared to SLN prepared with ultrasonication method (234 ± 3.52 nm to 288 ± 4.58 nm). The polydispersity index values were less than 0.3 for all formulations and zeta potential of the prepared formulations by these two methods varied from -22.71 ± 0.63 mV to -28.86 ± 0.58 mV. Powder X-ray diffraction and differential scanning calorimetry indicated decrease in crystallinity of drug. The in vitro release study and the SLN formulations prepared with ultrasonication method demonstrated sustained release up to 12 hours. This study demonstrated that SLN prepared by ultrasonication method is more suitable than microemulsion technique without causing any significant effect on corneal hydration level. PMID:27293896

  6. Formulation of Tenofovir-Loaded Functionalized Solid Lipid Nanoparticles Intended for HIV Prevention

    PubMed Central

    ALUKDA, DIMA; STURGIS, TIMOTHY; YOUAN, BI-BOTTI C.

    2011-01-01

    The objective of this study is to engineer polylysine–heparin functionalized solid lipid nanoparticles (fSLNs) for the use of a vaginal microbicide delivery template for HIV prevention. The fSLNs are prepared using a modified phase-inversion technique followed by a layer-by-layer deposition method. The Box–Behnken experimental design is used to analyze the influence of three factors (X1 = bovine serum albumin concentration, X2 = pH of the aqueous phase, and X3 = lipid amount) on the particle mean diameter (PMD) measured by dynamic light scattering (DLS). Tenofovir is used as a model anti-HIV microbicide. The SLNs are also characterized for morphology, zeta potential (ζ), percent drug encapsulation efficiency (EE%), and cytotoxicity on a human vaginal epithelial cell line by electron microscopy, DLS, ultraviolet, and fluorescence spectroscopy, respectively. The statistical model predicts particle size (Y) with 90% confidence and the Y values are significantly affected by X1 and X2. The produced fSLNs appear noncytotoxic and exhibit a platelet-like shape with respective PMD, EE%, and ζ value of 153 nm, 8.3%, and −51mV. These fSLNs intended to be administered topically have the potential to enhance cellular uptake of hydrophobic microbicides and outdistance the virus during the HIV/AIDS infection process, possibly leading to more effective prevention of the disease transmission. PMID:21437910

  7. Physical Stability Studies of Semi-Solid Formulations from Natural Compounds Loaded with Chitosan Microspheres

    PubMed Central

    Acosta, Niuris; Sánchez, Elisa; Calderón, Laura; Cordoba-Diaz, Manuel; Cordoba-Diaz, Damián; Dom, Senne; Heras, Ángeles

    2015-01-01

    A chitosan-based hydrophilic system containing an olive leaf extract was designed and its antioxidant capacity was evaluated. Encapsulation of olive leaf extract in chitosan microspheres was carried out by a spray-drying process. The particles obtained with this technique were found to be spherical and had a positive surface charge, which is an indicator of mucoadhesiveness. FTIR and X-ray diffraction results showed that there are not specific interactions of polyphenolic compounds in olive leaf extract with the chitosan matrix. Stability and release studies of chitosan microspheres loaded with olive leaf extract before and after the incorporation into a moisturizer base were performed. The resulting data showed that the developed formulations were stable up to three months. The encapsulation efficiency was around 44% and the release properties of polyphenols from the microspheres were found to be pH dependent. At pH 7.4, polyphenols release was complete after 6 h; whereas the amount of polyphenols released was 40% after the same time at pH 5.5. PMID:26389926

  8. Method for mercury refinement

    DOEpatents

    Grossman, Mark W.; Speer, Richard; George, William A.

    1991-01-01

    The effluent from mercury collected during the photochemical separation of the .sup.196 Hg isotope is often contaminated with particulate mercurous chloride, Hg.sub.2 Cl.sub.2. The use of mechanical filtering via thin glass tubes, ultrasonic rinsing with acetone (dimethyl ketone) and a specially designed cold trap have been found effective in removing the particulate (i.e., solid) Hg.sub.2 Cl.sub.2 contaminant. The present invention is particularly directed to such filtering.

  9. Apparatus for mercury refinement

    DOEpatents

    Grossman, Mark W.; Speer, Richard; George, William A.

    1991-01-01

    The effluent from mercury collected during the photochemical separation of the .sup.196 Hg isotope is often contaminated with particulate mercurous chloride, Hg.sub.2 Cl.sub.2. The use of mechanical filtering via thin glass tubes, ultrasonic rinsing with acetone (dimethyl ketone) and a specially designed cold trap have been found effective in removing the particulate (i.e., solid) Hg.sub.2 Cl.sub.2 contaminant. The present invention is particularly directed to such filtering.

  10. Method for mercury refinement

    DOEpatents

    Grossman, M.W.; Speer, R.; George, W.A.

    1991-04-09

    The effluent from mercury collected during the photochemical separation of the [sup 196]Hg isotope is often contaminated with particulate mercurous chloride, Hg[sub 2]Cl[sub 2]. The use of mechanical filtering via thin glass tubes, ultrasonic rinsing with acetone (dimethyl ketone) and a specially designed cold trap have been found effective in removing the particulate (i.e., solid) Hg[sub 2]Cl[sub 2] contaminant. The present invention is particularly directed to such filtering. 5 figures.

  11. Apparatus for mercury refinement

    DOEpatents

    Grossman, M.W.; Speer, R.; George, W.A.

    1991-07-16

    The effluent from mercury collected during the photochemical separation of the [sup 196]Hg isotope is often contaminated with particulate mercurous chloride, Hg[sub 2]Cl[sub 2]. The use of mechanical filtering via thin glass tubes, ultrasonic rinsing with acetone (dimethyl ketone) and a specially designed cold trap have been found effective in removing the particulate (i.e., solid) Hg[sub 2]Cl[sub 2] contaminant. The present invention is particularly directed to such filtering. 5 figures.

  12. Design and Evaluation of Voriconazole Loaded Solid Lipid Nanoparticles for Ophthalmic Application

    PubMed Central

    Khare, Anubha; Singh, Inderbir; Pawar, Pravin; Grover, Kanchan

    2016-01-01

    Voriconazole is a second-generation antifungal agent with excellent broad spectrum of antifungal activity commercially available for oral and intravenous administration. Systemic administration of voriconazole is associated with side effects including visual and hepatic abnormalities. This study assessed the feasibility of using solid lipid nanoparticles for ocular delivery of voriconazole adopting stearic acid as lipidic material, tween 80 as a stabilizer, and Carbopol 934 as controlled release agent and for increasing the precorneal residence time in eye. The systems were prepared using two different methods, that is, ultrasonication method and microemulsion technique. The results indicated that the larger particle size of SLNs was found with microemulsion technique (308 ± 3.52 nm to 343 ± 3.51) compared to SLN prepared with ultrasonication method (234 ± 3.52 nm to 288 ± 4.58 nm). The polydispersity index values were less than 0.3 for all formulations and zeta potential of the prepared formulations by these two methods varied from −22.71 ± 0.63 mV to −28.86 ± 0.58 mV. Powder X-ray diffraction and differential scanning calorimetry indicated decrease in crystallinity of drug. The in vitro release study and the SLN formulations prepared with ultrasonication method demonstrated sustained release up to 12 hours. This study demonstrated that SLN prepared by ultrasonication method is more suitable than microemulsion technique without causing any significant effect on corneal hydration level. PMID:27293896

  13. DEVELOPMENT OF A WATERSHED-BASED MERCURY POLLUTION CHARACTERIZATION SYSTEM

    EPA Science Inventory

    To investigate total mercury loadings to streams in a watershed, we have developed a watershed-based source quantification model ? Watershed Mercury Characterization System. The system uses the grid-based GIS modeling technology to calculate total soil mercury concentrations and ...

  14. Quality of water and bottom sediments, and nutrient and dissolved-solids loads in the Apopka-Beauclair Canal, Lake County, Florida, 1986-90

    USGS Publications Warehouse

    Schiffer, D.M.

    1994-01-01

    Nutrient-rich water enters Lake Beauclair and other lakes downstream from Lake Apopka in the Ocklawaha River chain of lakes in central Florida. Two sources of the nutrient-rich water are Lake Apopka outflow and drainage from farming operations adjacent to the Apopka-Beauclair Canal. Two flow and water- quality monitoring sites were established to measure nutrient and dissolved-solids loads at the outflow from lake Apopka and at a control structure on the Apopka-Beauclair Canal downstream from farming activities. Samples were collected biweekly for analysis of nutrients and monthly for analysis of major ions for 4 years. Most of the nutrient load transported through the lock and dam on the Apopka-Beauclair Canal was transported during periods of high discharge. In April 1987, when discharges were as high as 589 cubic feet per second, loads transported through the lock and dam accounted for 59 percent of the ammonia-plus- organic nitrogen load, 61 percent of the total nitrogen load, and 59 percent of the phosphorus load transported during the 1987 water year. Constituent concentrations in annual bottom sediment samples from the canal indicated that most of the constituent load is not being transported down- stream. An alternative approach was derived for determining the relative constituent load from farm input along the canal: Load computations using this approach indicated that, with the exception of phosphorus, nutrient and dissolved-solids loads due to farm activity along the canal account for 10 percent or less of the total load at the Apopka-Beauclair canal lock and dam. (USGS)

  15. Effect of enzyme supplementation at moderate cellulase loadings on initial glucose and xylose release from corn stover solids pretreated by leading technologies.

    PubMed

    Kumar, Rajeev; Wyman, C E

    2009-02-01

    Moderate loadings of cellulase enzyme supplemented with beta-glucosidase were applied to solids produced by ammonia fiber expansion (AFEX), ammonia recycle (ARP), controlled pH, dilute sulfuric acid, lime, and sulfur dioxide pretreatments to better understand factors that control glucose and xylose release following 24, 48, and 72 h of hydrolysis and define promising routes to reducing enzyme demands. Glucose removal was higher from all pretreatments than from Avicel cellulose at lower enzyme loadings, but sugar release was a bit lower for solids prepared by dilute sulfuric acid in the Sunds system and by controlled pH pretreatment than from Avicel at higher protein loadings. Inhibition by cellobiose was observed to depend on the type of substrate and pretreatment and hydrolysis times, with a corresponding impact of beta-glucosidase supplementation. Furthermore, for the first time, xylobiose and higher xylooligomers were shown to inhibit enzymatic hydrolysis of pure glucan, pure xylan, and pretreated corn stover, and xylose, xylobiose, and xylotriose were shown to have progressively greater effects on hydrolysis rates. Consistent with this, addition of xylanase and beta-xylosidase improved performance significantly. For a combined mass loading of cellulase and beta-glucosidase of 16.1 mg/g original glucan (about 7.5 FPU/g), glucose release from pretreated solids ranged from 50% to75% of the theoretical maximum and was greater for all pretreatments at all protein loadings compared to pure Avicel cellulose except for solids from controlled pH pretreatment and from dilute acid pretreatment by the Sunds pilot unit. The fraction of xylose released from pretreated solids was always less than for glucose, with the upper limit being about 60% of the maximum for ARP and the Sunds dilute acid pretreatments at a very high protein mass loading of 116 mg/g glucan (about 60 FPU).

  16. Using Wet-FGD systems for mercury removal.

    PubMed

    Díaz-Somoano, Mercedes; Unterberger, Sven; Hein, Klaus R G

    2005-09-01

    A plan to control mercury emissions to the atmosphere and to establish mercury emission limits has recently been elaborated by the European Commission, making it necessary to devise an efficient and cost effective mercury removal technology. Towards this end wet flue gas desulfurization units appear as a promising option for multi-pollutant control. However, more investigation on mercury removal and a greater mercury removal efficiency are required to achieve this objective. In the present work scrubber chemistry and the application of various solid additives to enhance mercury removal in wet scrubbers is evaluated. The results obtained show a significant correlation between mercury removal efficiency and the pH of the scrubber slurry and SO2 concentration. A weaker correlation was observed between oxygen or slurry concentration and removal efficiency. Finally several solid oxides were found to be effective additives for enhancing mercury capture in wet scrubbers.

  17. Using Wet-FGD systems for mercury removal.

    PubMed

    Díaz-Somoano, Mercedes; Unterberger, Sven; Hein, Klaus R G

    2005-09-01

    A plan to control mercury emissions to the atmosphere and to establish mercury emission limits has recently been elaborated by the European Commission, making it necessary to devise an efficient and cost effective mercury removal technology. Towards this end wet flue gas desulfurization units appear as a promising option for multi-pollutant control. However, more investigation on mercury removal and a greater mercury removal efficiency are required to achieve this objective. In the present work scrubber chemistry and the application of various solid additives to enhance mercury removal in wet scrubbers is evaluated. The results obtained show a significant correlation between mercury removal efficiency and the pH of the scrubber slurry and SO2 concentration. A weaker correlation was observed between oxygen or slurry concentration and removal efficiency. Finally several solid oxides were found to be effective additives for enhancing mercury capture in wet scrubbers. PMID:16121271

  18. Solid phase extraction of ultra traces mercury (II) using octadecyl silica membrane disks modified by 1,3-bis(2-ethoxyphenyl)triazene (EPT) ligand and determination by cold vapor atomic absorption spectrometry.

    PubMed

    Rofouei, Mohammad Kazem; Sabouri, Alireza; Ahmadalinezhad, Asieh; Ferdowsi, Hadis

    2011-09-15

    A facile and highly efficient method was developed for the preconcentration of the ultra trace amounts of mercury (II) ions. Octadecyl silica membrane disk was modified by the recently synthesized triazene ligand, 1,3-bis(2-ethoxyphenyl)triazene (EPT), and cold vapor atomic absorption spectrometry was used to determine the resultant preconcentrated Hg(II) ions. Solution studies with EPT and a series of metal ions were done in advance, and the results showed a strong affinity of EPT to the mercury ions. To perform solid phase extraction, various parameters such as pH of the sample, flow rates and the amount of the ligand were optimized. A linear calibration curve was obtained in the range of 0.02-1.90 μg L(-1) with r(2) = 0.9990 (n = 8), and the limit of detection (LOD) based on three times the standard deviation of the blank was 10.6 ng L(-1). The relative standard deviation (RSD) for the determination of 0.1 μg L(-1) Hg(II) found to be 2.9% while a RSD value of 1.1% was obtained for the determination of 1.0 μg L(-1) Hg(II) (n = 8). The preconcentration and improvement factors were 380 and 74, respectively. The newly developed method was successfully applied to the determination of mercury ions in real water samples.

  19. Solid phase extraction of trace amounts of silver, cadmium, copper, mercury, and lead in various food samples based on ethylene glycol bis-mercaptoacetate modified 3-(trimethoxysilyl)-1-propanethiol coated Fe3O4 nanoparticles.

    PubMed

    Mashhadizadeh, Mohammad Hossein; Amoli-Diva, Mitra; Shapouri, Mahmoud Reza; Afruzi, Hossein

    2014-05-15

    Extraction, pre-concentration, and determination of trace amounts of silver, cadmium, copper, mercury, and lead from some food samples were investigated by magnetic solid phase extraction using Fe3O4 nanoparticles coated with 3-(trimethoxysilyl)-1-propanethiol and modified with ethylene glycol bis-mercaptoacetate as a new adsorbent. SEM, X-ray diffraction, and FT-IR were used to characterise the adsorbent. Metal ions were measured using ICP-OES, except for mercury, which was determined by CV-AAS method. Various factors affecting the extraction and desorption of target metal ions were investigated. 1 mL of 1 mol/L HCl and 5% thiourea was used as eluent. The detection limits of 0.07, 0.06, 0.09, 0.01, and 0.08 ng/mL were obtained for silver, cadmium, copper, mercury, and lead with enrichment factors of 240, 294, 297, 291, and 236, respectively. The method was used for determination of target metal ions in rice, canned tuna fish, and tea leaves. PMID:24423536

  20. Solid phase extraction of ultra traces mercury (II) using octadecyl silica membrane disks modified by 1,3-bis(2-ethoxyphenyl)triazene (EPT) ligand and determination by cold vapor atomic absorption spectrometry.

    PubMed

    Rofouei, Mohammad Kazem; Sabouri, Alireza; Ahmadalinezhad, Asieh; Ferdowsi, Hadis

    2011-09-15

    A facile and highly efficient method was developed for the preconcentration of the ultra trace amounts of mercury (II) ions. Octadecyl silica membrane disk was modified by the recently synthesized triazene ligand, 1,3-bis(2-ethoxyphenyl)triazene (EPT), and cold vapor atomic absorption spectrometry was used to determine the resultant preconcentrated Hg(II) ions. Solution studies with EPT and a series of metal ions were done in advance, and the results showed a strong affinity of EPT to the mercury ions. To perform solid phase extraction, various parameters such as pH of the sample, flow rates and the amount of the ligand were optimized. A linear calibration curve was obtained in the range of 0.02-1.90 μg L(-1) with r(2) = 0.9990 (n = 8), and the limit of detection (LOD) based on three times the standard deviation of the blank was 10.6 ng L(-1). The relative standard deviation (RSD) for the determination of 0.1 μg L(-1) Hg(II) found to be 2.9% while a RSD value of 1.1% was obtained for the determination of 1.0 μg L(-1) Hg(II) (n = 8). The preconcentration and improvement factors were 380 and 74, respectively. The newly developed method was successfully applied to the determination of mercury ions in real water samples. PMID:21782328

  1. Updated estimates of long-term average dissolved-solids loading in streams and rivers of the Upper Colorado River Basin

    USGS Publications Warehouse

    Tillman, Fred D; Anning, David W.

    2014-01-01

    The Colorado River and its tributaries supply water to more than 35 million people in the United States and 3 million people in Mexico, irrigating over 4.5 million acres of farmland, and annually generating about 12 billion kilowatt hours of hydroelectric power. The Upper Colorado River Basin, part of the Colorado River Basin, encompasses more than 110,000 mi2 and is the source of much of more than 9 million tons of dissolved solids that annually flows past the Hoover Dam. High dissolved-solids concentrations in the river are the cause of substantial economic damages to users, primarily in reduced agricultural crop yields and corrosion, with damages estimated to be greater than 300 million dollars annually. In 1974, the Colorado River Basin Salinity Control Act created the Colorado River Basin Salinity Control Program to investigate and implement a broad range of salinity control measures. A 2009 study by the U.S. Geological Survey, supported by the Salinity Control Program, used the Spatially Referenced Regressions on Watershed Attributes surface-water quality model to examine dissolved-solids supply and transport within the Upper Colorado River Basin. Dissolved-solids loads developed for 218 monitoring sites were used to calibrate the 2009 Upper Colorado River Basin Spatially Referenced Regressions on Watershed Attributes dissolved-solids model. This study updates and develops new dissolved-solids loading estimates for 323 Upper Colorado River Basin monitoring sites using streamflow and dissolved-solids concentration data through 2012, to support a planned Spatially Referenced Regressions on Watershed Attributes modeling effort that will investigate the contributions to dissolved-solids loads from irrigation and rangeland practices.

  2. Load maximization of a liquid-solid circulating fluidized bed bioreactor for nitrogen removal from synthetic municipal wastewater.

    PubMed

    Chowdhury, Nabin; Nakhla, George; Zhu, Jesse

    2008-03-01

    A novel liquid-solid circulating fluidized bed bioreactor (LSCFB) configured with anoxic and aerobic columns and lava rock as the biofilm carrier was used to treat synthetic municipal wastewater. Four different empty bed contact times (EBCTs) of 0.82, 0.65, 0.55, and 0.44 h were examined to optimize nutrient removal capability of the system. The LSCFB demonstrated tertiary effluent quality organic and nitrogen removal efficiencies. Effluent characteristics of the LSCFB were soluble biological oxygen demand (SBOD)10 mg l(-1) and total nitrogen (TN)<10 mg l(-1) at organic loading rate (OLR) of 5.3 kg m(-3)d(-1) and nitrogen loading rate of 0.54 kg Nm(-3)d(-1). Remarkably low yields of 0.14, 0.17, 0.19, and 0.21 g VSS g(-1)COD were observed at OLR of 2.6, 3.2, 4.1 and 5.3 kg COD m(-3)d(-1), where increment of biomass growth and detachment rate were also experienced with increasing OLR. However the system demonstrated only 30% phosphorus removal, and mass balances along the anoxic and aerobic columns showed biological phosphorus removal in the system. Organic mass balance showed that approximately 40% of the influent COD was utilized in the anoxic column and the remaining COD was oxidized in the aerobic column. The system is very efficient in nitrification-denitrification, with more than 90% nitrification of ammonium and overall nitrogen removal in the LSCFB was 70+/-11% even at an EBCT of 0.44 h. PMID:18262217

  3. Mercury Flow Through the Mercury-Containing Lamp Sector of the Economy of the United States

    USGS Publications Warehouse

    Goonan, Thomas G.

    2006-01-01

    Introduction: This Scientific Investigations Report examines the flow of mercury through the mercury-containing lamp sector of the U.S. economy in 2001 from lamp manufacture through disposal or recycling. Mercury-containing lamps illuminate commercial and industrial buildings, outdoor areas, and residences. Mercury is an essential component in fluorescent lamps and high-intensity discharge lamps (high-pressure sodium, mercury-vapor, and metal halide). A typical fluorescent lamp is composed of a phosphor-coated glass tube with electrodes located at either end. Only a very small amount of the mercury is in vapor form. The remainder of the mercury is in the form of either liquid mercury metal or solid mercury oxide (mercury oxidizes over the life of the lamp). When voltage is applied, the electrodes energize the mercury vapor and cause it to emit ultraviolet energy. The phosphor coating absorbs the ultraviolet energy, which causes the phosphor to fluoresce and emit visible light. Mercury-containing lamps provide more lumens per watt than incandescent lamps and, as a result, require from three to four times less energy to operate. Mercury is persistent and toxic within the environment. Mercury-containing lamps are of environmental concern because they are widely distributed throughout the environment and are easily broken in handling. The magnitude of lamp sector mercury emissions, estimated to be 2.9 metric tons per year (t/yr), is small compared with the estimated mercury losses of the U.S. coal-burning and chlor-alkali industries, which are about 70 t/yr and about 90 t/yr, respectively.

  4. Effect of Degeneration on Fluid–Solid Interaction within Intervertebral Disk Under Cyclic Loading – A Meta-Model Analysis of Finite Element Simulations

    PubMed Central

    Nikkhoo, Mohammad; Khalaf, Kinda; Kuo, Ya-Wen; Hsu, Yu-Chun; Haghpanahi, Mohammad; Parnianpour, Mohamad; Wang, Jaw-Lin

    2015-01-01

    The risk of low back pain resulted from cyclic loadings is greater than that resulted from prolonged static postures. Disk degeneration results in degradation of disk solid structures and decrease of water contents, which is caused by activation of matrix digestive enzymes. The mechanical responses resulted from internal solid–fluid interactions of degenerative disks to cyclic loadings are not well studied yet. The fluid–solid interactions in disks can be evaluated by mathematical models, especially the poroelastic finite element (FE) models. We developed a robust disk poroelastic FE model to analyze the effect of degeneration on solid–fluid interactions within disk subjected to cyclic loadings at different loading frequencies. A backward analysis combined with in vitro experiments was used to find the elastic modulus and hydraulic permeability of intact and enzyme-induced degenerated porcine disks. The results showed that the averaged peak-to-peak disk deformations during the in vitro cyclic tests were well fitted with limited FE simulations and a quadratic response surface regression for both disk groups. The results showed that higher loading frequency increased the intradiscal pressure, decreased the total fluid loss, and slightly increased the maximum axial stress within solid matrix. Enzyme-induced degeneration decreased the intradiscal pressure and total fluid loss, and barely changed the maximum axial stress within solid matrix. The increase of intradiscal pressure and total fluid loss with loading frequency was less sensitive after the frequency elevated to 0.1 Hz for the enzyme-induced degenerated disk. Based on this study, it is found that enzyme-induced degeneration decreases energy attenuation capability of disk, but less change the strength of disk. PMID:25674562

  5. Preparation and evaluation of raloxifene-loaded solid dispersion nanoparticle by spray-drying technique without an organic solvent.

    PubMed

    Tran, Tuan Hiep; Poudel, Bijay K; Marasini, Nirmal; Chi, Sang-Cheol; Choi, Han-Gon; Yong, Chul Soon; Kim, Jong Oh

    2013-02-25

    The aim of this study was to improve the physicochemical properties and bioavailability of a poorly water-soluble drug, raloxifene by solid dispersion (SD) nanoparticles using the spray-drying technique. These spray-dried SD nanoparticles were prepared with raloxifene (RXF), polyvinylpyrrolidone (PVP) and Tween 20 in water. Reconstitution of optimized RXF-loaded SD nanoparticles in pH 1.2 medium showed a mean particle size of approximately 180 nm. X-ray diffraction and differential scanning calorimetry indicated that RXF existed in an amorphous form within spray-dried nanoparticles. The optimized formulation showed an enhanced dissolution rate of RXF at pH 1.2, 4.0, 6.8 and distilled water as compared to pure RXF powder. The improved dissolution of raloxifene from spray-dried SD nanoparticles appeared to be well correlated with enhanced oral bioavailability of raloxifene in rats. Furthermore, the pharmacokinetic parameters of the spray-dried SD nanoparticles showed increased AUC(0-∞) and C(max) of RXF by approximately 3.3-fold and 2.3-fold, respectively. These results suggest that the preparation of RXF-SD nanoparticles using the spray drying technique without organic solvents might be a promising approach for improving the oral bioavailability of RXF. PMID:23318367

  6. Berberine-loaded solid lipid nanoparticles are concentrated in the liver and ameliorate hepatosteatosis in db/db mice

    PubMed Central

    Xue, Mei; Zhang, Liang; Yang, Ming-xing; Zhang, Wei; Li, Xiu-min; Ou, Zhi-min; Li, Zhi-peng; Liu, Su-huan; Li, Xue-jun; Yang, Shu-yu

    2015-01-01

    Berberine (BBR) shows very low plasma levels after oral administration due to its poor absorption by the gastrointestinal tract. We have previously demonstrated that BBR showed increased gastrointestinal absorption and enhanced antidiabetic effects in db/db mice after being entrapped into solid lipid nanoparticles (SLNs). However, whether BBR-loaded SLNs (BBR-SLNs) also have beneficial effects on hepatosteatosis is not clear. We investigated the effects of BBR-SLNs on lipid metabolism in the liver using histological staining and reverse transcription polymerase chain reaction analysis. The results showed that oral administration of BBR-SLNs inhibited the increase of body weight and decreased liver weight in parallel with the reduction of serum alanine transaminase and liver triglyceride levels in db/db mice. The maximum drug concentration in the liver was 20-fold higher than that in the blood. BBR-SLNs reduced fat accumulation and lipid droplet sizes significantly in the liver, as indicated by hematoxylin and eosin and Oil Red O staining. The expression of lipogenic genes, including fatty acid synthase (FAS), stearoyl-CoA desaturase (SCD1), and sterol regulatory element-binding protein 1c (SREBP1c) were downregulated, while lipolytic gene carnitine palmitoyltransferase-1 (CPT1) was upregulated in BBR-SLN-treated livers. In summary, we have uncovered an unexpected effect of BBR-SLNs on hepatosteatosis treatment through the inhibition of lipogenesis and the induction of lipolysis in the liver of db/db mice. PMID:26346310

  7. Vitamin A loaded solid lipid nanoparticles for topical use: occlusive properties and drug targeting to the upper skin.

    PubMed

    Jenning, V; Gysler, A; Schäfer-Korting, M; Gohla, S H

    2000-05-01

    To evaluate the potential use of solid lipid nanoparticles (SLN) in dermatology and cosmetics, glyceryl behenate SLN loaded with vitamin A (retinol and retinyl palmitate) and incorporated in a hydrogel and o/w-cream were tested with respect to their influence on drug penetration into porcine skin. Conventional formulations served for comparison. Excised full thickness skin was mounted in Franz diffusion cells and the formulations were applied for 6 and 24 h, respectively. Vitamin A concentrations in the skin tissue suggested a certain drug localizing effect. High retinol concentrations were found in the upper skin layers following SLN preparations, whereas the deeper regions showed only very low vitamin A levels. Because of a polymorphic transition of the lipid carrier with subsequent drug expulsion following the application to the skin, the drug localizing action appears to be limited for 6-24 h. Best results were obtained with retinol SLN incorporated in the oil-in-water (o/w) cream retarding drug expulsion. The penetration of the occlusion sensitive drug retinyl palmitate was even more influenced by SLN incorporation. Transepidermal water loss (TEWL) and the influence of drug free SLN on retinyl palmitate uptake exclude pronounced occlusive effects. Therefore enhanced retinyl palmitate uptake should derive from specific SLN effects and is not due to non-specific occlusive properties.

  8. Preparation of oridonin-loaded solid lipid nanoparticles and studies on them in vitro and in vivo

    NASA Astrophysics Data System (ADS)

    Zhang, Dianrui; Tan, Tianwei; Gao, Lei

    2006-12-01

    Oridonin, a lipophilic Chinese medicine, has very low oral bioavailability due to its poor solubility. Solid lipid nanoparticle (SLN) delivery systems of oridonin have been formed using stearic acid, soybean lecithin and pluronic F68 in our studies to overcome this problem. Emulsion evaporation-solidification at low temperature was used to prepare SLN dispersions. The particle size and morphology were examined by transmission electron microscopy (TEM), and the zeta potential was measured by a television micro-electrophoresis apparatus. Process and formulation variables have been studied and optimized on the basis of entrapment efficiency. Differential scanning calorimetry (DSC) and powder x-ray diffraction (PXRD) studies were performed to characterize the state of the drug. In vitro release studies were performed in phosphate-buffer solution (PBS) (pH 7.4). The tissue distribution in mice and the pharmacokinetics in rabbits were studied to evaluate the tissue targeted property of SLNs. Stable SLN formulations of oridonin having a mean size range of 15-35 nm and mean zeta potential -45.07 mV were developed. More than 40% oridonin was entrapped in SLNs. DSC and PXRD analysis showed that oridonin is dispersed in SLNs in an amorphous state. The release pattern of the drug was analysed and found to follow the Higuchi equations. In vivo studies demonstrated that oridonin-loaded SLNs obviously increased the concentration of oridonin in liver, lung and spleen, while its distribution in heart and kidney decreased.

  9. DEVELOPMENT AND TEST APPLICATION A SCREENING-LEVEL MERCURY FATE MODEL AND TOOL FOR EVALUATING WILDLIFE EXPOSURE RISK FOR SURFACE WATERS WITH MERCURY-CONTAMINATED SEDIMENTS (SERAFM)

    EPA Science Inventory

    Complex chemical cycling of mercury in aquatic ecosystems means that tracing the linkage between anthropogenic and natural loadings of mercury to watersheds and water bodies and associated concentrations in the environment are difficult to establish without the assistance of nume...

  10. Got Mercury?

    NASA Technical Reports Server (NTRS)

    Meyers, Valerie; James, John T.; McCoy, Torin; Garcia, Hector

    2010-01-01

    Many lamps used in various spacecraft contain elemental mercury, which is efficiently absorbed through the lungs as a vapor. The liquid metal vaporizes slowly at room temperature, but may be completely vaporized when lamps are operating. Because current spacecraft environmental control systems are unable to remove mercury vapors, we considered short-term and long-term exposures. Using an existing study, we estimated mercury vapor releases from lamps that are not in operation during missions lasting less than or equal to 30 days; whereas we conservatively assumed complete vaporization from lamps that are operating or being used during missions lasing more than 30 days. Based on mercury toxicity, the Johnson Space Center's Toxicology Group recommends stringent safety controls and verifications for any hardware containing elemental mercury that could yield airborne mercury vapor concentrations greater than 0.1 mg/m3 in the total spacecraft atmosphere for exposures lasting less than or equal to 30 days, or concentrations greater than 0.01 mg/m3 for exposures lasting more than 30 days.

  11. Mercury Emission Measurement at a CFB Plant

    SciTech Connect

    John Pavlish; Jeffrey Thompson; Lucinda Hamre

    2009-02-28

    In response to pending regulation to control mercury emissions in the United States and Canada, several projects have been conducted to perform accurate mass balances at pulverized coal (pc)-fired utilities. Part of the mercury mass balance always includes total gaseous mercury as well as a determination of the speciation of the mercury emissions and a concentration bound to the particulate matter. This information then becomes useful in applying mercury control strategies, since the elemental mercury has traditionally been difficult to control by most technologies. In this instance, oxidation technologies have proven most beneficial for increased capture. Despite many years of mercury measurement and control projects at pc-fired units, far less work has been done on circulating fluidized-bed (CFB) units, which are able to combust a variety of feedstocks, including cofiring coal with biomass. Indeed, these units have proven to be more problematic because it is very difficult to obtain a reliable mercury mass balance. These units tend to have very different temperature profiles than pc-fired utility boilers. The flexibility of CFB units also tends to be an issue when a mercury balance is determined, since the mercury inputs to the system come from the bed material and a variety of fuels, which can have quite variable chemistry, especially for mercury. In addition, as an integral part of the CFB operation, the system employs a feedback loop to circulate the bed material through the combustor and the solids collection system (the primary cyclone), thereby subjecting particulate-bound metals to higher temperatures again. Despite these issues, CFB boilers generally emit very little mercury and show good native capture. The Energy & Environmental Research Center is carrying out this project for Metso Power in order to characterize the fate of mercury across the unit at Rosebud Plant, an industrial user of CFB technology from Metso. Appropriate solids were collected, and

  12. Whole-ecosystem study shows rapid fish-mercury response to changes in mercury deposition

    USGS Publications Warehouse

    Harris, R.C.; Rudd, J.W.M.; Amyot, M.; Babiarz, C.L.; Beaty, K.G.; Blanchfield, P.J.; Bodaly, R.A.; Branfireun, B.A.; Gilmour, C.C.; Graydon, J.A.; Heyes, A.; Hintelmann, H.; Hurley, J.P.; Kelly, C.A.; Krabbenhoft, D.P.; Lindberg, S.E.; Mason, R.P.; Paterson, M.J.; Podemski, C.L.; Robinson, A.; Sandilands, K.A.; Southworthn, G.R.; St. Louis, V.L.; Tate, M.T.

    2007-01-01

    Methylmercury contamination of fisheries from centuries of industrial atmospheric emissions negatively impacts humans and wild-life worldwide. The response of fish methylmercury concentrations to changes in mercury deposition has been difficult to establish because sediments/soils contain large pools of historical contamination, and many factors in addition to deposition affect fish mercury. To test directly the response of fish contamination to changing mercury deposition, we conducted a whole-ecosystem experiment, increasing the mercury load to a lake and its watershed by the addition of enriched stable mercury isotopes. The isotopes allowed us to distinguish between experimentally applied mercury and mercury already present in the ecosystem and to examine bioaccumulation of mercury deposited to different parts of the watershed. Fish methylmercury concentrations responded rapidly to changes in mercury deposition over the first 3 years of study. Essentially all of the increase in fish methylmercury concentrations came from mercury deposited directly to the lake surface. In contrast, <1% of the mercury isotope deposited to the watershed was exported to the lake. Steady state was not reached within 3 years. Lake mercury isotope concentrations were still rising in lake biota, and watershed mercury isotope exports to the lake were increasing slowly. Therefore, we predict that mercury emissions reductions will yield rapid (years) reductions in fish methylmercury concentrations and will yield concomitant reductions in risk. However, a full response will be delayed by the gradual export of mercury stored in watersheds. The rate of response will vary among lakes depending on the relative surface areas of water and watershed. ?? 2007 by The National Academy of Sciences of the USA.

  13. Incorporating uncertainty in watershed management decision-making: A mercury TMDL case study

    USGS Publications Warehouse

    Labiosa, W.; Leckie, J.; Shachter, R.; Freyberg, D.; Rytuba, J.; ,

    2005-01-01

    Water quality impairment due to high mercury fish tissue concentrations and high mercury aqueous concentrations is a widespread problem in several sub-watersheds that are major sources of mercury to the San Francisco Bay. Several mercury Total Maximum Daily Load regulations are currently being developed to address this problem. Decisions about control strategies are being made despite very large uncertainties about current mercury loading behavior, relationships between total mercury loading and methyl mercury formation, and relationships between potential controls and mercury fish tissue levels. To deal with the issues of very large uncertainties, data limitations, knowledge gaps, and very limited State agency resources, this work proposes a decision analytical alternative for mercury TMDL decision support. The proposed probabilistic decision model is Bayesian in nature and is fully compatible with a "learning while doing" adaptive management approach. Strategy evaluation, sensitivity analysis, and information collection prioritization are examples of analyses that can be performed using this approach.

  14. Mercury's Core

    NASA Astrophysics Data System (ADS)

    Peale, S. J.

    2005-05-01

    In determining Mercury's core structure from its rotational properties, the location of Cassini state 1 is crucial. Convincing radar evidence indicates that the mantle rests on a liquid layer (Margot et al. 2005), but there are no empirical constraints on the moment of inertia C/MR2, which constraints must wait for the determination of the gravitational coefficients J2 and C22 from the MESSENGER orbiting spacecraft, and an accurate determination of the obliquity of the Cassini state. Tidal and core-mantle dissipation drive the spin to the Cassini state with a time scale O(105) years, so the spin should occupy the Cassini state and thereby define its obliquity---unless there has been a recent excitation of a free precession of the spin. Another way the spin might be displaced from the Cassini state is if the variations in the orbital elements, which change the position of the Cassini state, cause the spin axis to lag behind as it attempts to follow the state. Fortunately, the solid angle the spin axis encloses as it precesses around the Cassini state is an adiabatic invariant, and it is conserved if the orbital element variations are slow compared to the precession rate. As the precession period is O(1000) years, and the time scales of orbital parameter variations are O(105) years, the spin axis should remain very close to the Cassini state if it were ever close. But how close is close? The increasing precision of the radar and eventual spacecraft measurements warrants a check on the likely proximity of the spin axis to the Cassini state. By numerically following the positions of the spin axis and Cassini state with orbital parameters varying with time scales and amplitudes comparable to the real variations, we show that the spin should remain within 1″ of the Cassini state once dissipative torques bring it there. The current spin axis position should thus define the Cassini state sufficiently to put reasonably tight constraints on the core structure

  15. [Mercury Distribution Characteristics and Atmospheric Mercury Emission Factors of Typical Waste Incineration Plants in Chongqing].

    PubMed

    Duan, Zhen-ya; Su, Hai-tao; Wang, Feng-yang; Zhang, Lei; Wang, Shu-xiao; Yu, Bin

    2016-02-15

    Waste incineration is one of the important atmospheric mercury emission sources. The aim of this article is to explore the atmospheric mercury pollution level of waste incineration industry from Chongqing. This study investigated the mercury emissions from a municipal solid waste incineration plant and a medical waste incineration plant in Chongqing. The exhaust gas samples in these two incineration plants were obtained using USA EPA 30B method. The mercury concentrations in the fly ash and bottom ash samples were analyzed. The results indicated that the mercury concentrations of the municipal solid waste and medical waste incineration plant in Chongqing were (26.4 +/- 22.7) microg x m(-3) and (3.1 +/- 0.8) microg x m(-3) in exhaust gas respectively, (5279.2 +/- 798.0) microg x kg(-1) and (11,709.5 +/- 460.5) microg x kg(-1) in fly ash respectively. Besides, the distribution proportions of the mercury content from municipal solid waste and medical waste in exhaust gas, fly ash, and bottom ash were 34.0%, 65.3%, 0.7% and 32.3%, 67.5%, 0.2% respectively; The mercury removal efficiencies of municipal solid waste and medical waste incineration plants were 66.0% and 67.7% respectively. The atmospheric mercury emission factors of municipal solid waste and medical waste incineration plants were (126.7 +/- 109.0) microg x kg(-1) and (46.5 +/- 12.0) microg x kg(-1) respectively. Compared with domestic municipal solid waste incineration plants in the Pearl River Delta region, the atmospheric mercury emission factor of municipal solid waste incineration plant in Chongqing was lower.

  16. [Mercury Distribution Characteristics and Atmospheric Mercury Emission Factors of Typical Waste Incineration Plants in Chongqing].

    PubMed

    Duan, Zhen-ya; Su, Hai-tao; Wang, Feng-yang; Zhang, Lei; Wang, Shu-xiao; Yu, Bin

    2016-02-15

    Waste incineration is one of the important atmospheric mercury emission sources. The aim of this article is to explore the atmospheric mercury pollution level of waste incineration industry from Chongqing. This study investigated the mercury emissions from a municipal solid waste incineration plant and a medical waste incineration plant in Chongqing. The exhaust gas samples in these two incineration plants were obtained using USA EPA 30B method. The mercury concentrations in the fly ash and bottom ash samples were analyzed. The results indicated that the mercury concentrations of the municipal solid waste and medical waste incineration plant in Chongqing were (26.4 +/- 22.7) microg x m(-3) and (3.1 +/- 0.8) microg x m(-3) in exhaust gas respectively, (5279.2 +/- 798.0) microg x kg(-1) and (11,709.5 +/- 460.5) microg x kg(-1) in fly ash respectively. Besides, the distribution proportions of the mercury content from municipal solid waste and medical waste in exhaust gas, fly ash, and bottom ash were 34.0%, 65.3%, 0.7% and 32.3%, 67.5%, 0.2% respectively; The mercury removal efficiencies of municipal solid waste and medical waste incineration plants were 66.0% and 67.7% respectively. The atmospheric mercury emission factors of municipal solid waste and medical waste incineration plants were (126.7 +/- 109.0) microg x kg(-1) and (46.5 +/- 12.0) microg x kg(-1) respectively. Compared with domestic municipal solid waste incineration plants in the Pearl River Delta region, the atmospheric mercury emission factor of municipal solid waste incineration plant in Chongqing was lower. PMID:27363131

  17. Mercury Contamination

    PubMed Central

    Thompson, Marcella R.

    2013-01-01

    IN BRIEF A residential elemental mercury contamination incident in Rhode Island resulted in the evacuation of an entire apartment complex. To develop recommendations for improved response, all response-related documents were examined; personnel involved in the response were interviewed; policies and procedures were reviewed; and environmental monitoring data were compiled from specific phases of the response for analysis of effect. A significant challenge of responding to residential elemental mercury contamination lies in communicating risk to residents affected py a HazMat spill. An ongoing, open and honest dialogue is emphasized where concerns of the public are heard and addressed, particularly when establishing and/or modifying policies and procedures for responding to residential elemental mercury contamination. PMID:23436951

  18. The Importance of the Solids Loading on Confirming the Dielectric Nanosize Dependence of BaTiO3 Powders by Slurry Method

    PubMed Central

    Zhou, Wei; Nie, Yi Mei; Li, Shu Jing; Liang, Hai Yan

    2013-01-01

    The dielectric nanosize dependence of BaTiO3 powders was investigated by the slurry method, where two series of BaTiO3 slurries with 10 vol% and 30 vol% solids loadings were prepared as model samples. Applying the Bruggeman-Hanai equation, the high-frequency limiting permittivity (εh) of the slurries was extracted from the dielectric spectra. The εh of the 10 vol% slurry showed abnormal size independence in the range from 100 nm to 700 nm, and the εh of the 30 vol% slurry exhibited good agreement with the previous prediction. Through analysing quantitatively the response of εh to the changing permittivity of the powders under different solids loading, it was found that the εh of the slurry with lower solids loading is more inclined to be interfered by the systematic and random errors. Furthermore, a high permittivity value was found in the BaTiO3 powders with 50 nm particle size. PMID:23844376

  19. Increase in mercury in Pacific yellowfin tuna.

    PubMed

    Drevnick, Paul E; Lamborg, Carl H; Horgan, Martin J

    2015-04-01

    Mercury is a toxic trace metal that can accumulate to levels that threaten human and environmental health. Models and empirical data suggest that humans are responsible for a great deal of the mercury actively cycling in the environment at present. Thus, one might predict that the concentration of mercury in fish should have increased dramatically since the Industrial Revolution. Evidence in support of this hypothesis has been hard to find, however, and some studies have suggested that analyses of fish show no change in mercury concentration. By compiling and re-analyzing published reports on yellowfin tuna (Thunnus albacares) caught near Hawaii (USA) over the past half century, the authors found that the concentration of mercury in these fish currently is increasing at a rate of at least 3.8% per year. This rate of increase is consistent with a model of anthropogenic forcing on the mercury cycle in the North Pacific Ocean and suggests that fish mercury concentrations are keeping pace with current loading increases to the ocean. Future increases in mercury in yellowfin tuna and other fishes can be avoided by reductions in atmospheric mercury emissions from point sources.

  20. Increase in mercury in Pacific yellowfin tuna.

    PubMed

    Drevnick, Paul E; Lamborg, Carl H; Horgan, Martin J

    2015-04-01

    Mercury is a toxic trace metal that can accumulate to levels that threaten human and environmental health. Models and empirical data suggest that humans are responsible for a great deal of the mercury actively cycling in the environment at present. Thus, one might predict that the concentration of mercury in fish should have increased dramatically since the Industrial Revolution. Evidence in support of this hypothesis has been hard to find, however, and some studies have suggested that analyses of fish show no change in mercury concentration. By compiling and re-analyzing published reports on yellowfin tuna (Thunnus albacares) caught near Hawaii (USA) over the past half century, the authors found that the concentration of mercury in these fish currently is increasing at a rate of at least 3.8% per year. This rate of increase is consistent with a model of anthropogenic forcing on the mercury cycle in the North Pacific Ocean and suggests that fish mercury concentrations are keeping pace with current loading increases to the ocean. Future increases in mercury in yellowfin tuna and other fishes can be avoided by reductions in atmospheric mercury emissions from point sources. PMID:25645441

  1. [Removal of gaseous elemental mercury over cerium doped low vanadium loading V2O5-WO3/TiO2 in simulated coal-fired flue gas].

    PubMed

    Wan, Qi; Duan, Lei; He, Ke-Bin; Chen, Liang; Li, Jun-Hua

    2011-09-01

    This paper discussed a recent study of mercury removal by gaseous hydrogen chloride over novel Ce doped low vanadium V2O5-WO3/TiO2 catalysts under a bench scale condition. The performances on Hg(0) removal over the catalyst were tested in simulated flue gas with 80-100 microg x m(-3) Hg(0), 8% O2, 10 x10(-6) HCl, 8% H2O, 800 x10(-6) SO2 and balanced with N2. Results showed that about 95% of Hg(0) could be removed. According to the characterization results, BET surface areas had not significant influence on catalytic performance. XPS results indicated that Ce4+ oxide was a mainly form in the catalysts surface, which was beneficial for Hg(0) removal reactions. Water vapor slightly inhibited Hg(0) removal efficiency, due to the competitive adsorption, however, SO2 promoted the oxidation reactions, resulting in higher removal efficiencies.

  2. [Removal of gaseous elemental mercury over cerium doped low vanadium loading V2O5-WO3/TiO2 in simulated coal-fired flue gas].

    PubMed

    Wan, Qi; Duan, Lei; He, Ke-Bin; Chen, Liang; Li, Jun-Hua

    2011-09-01

    This paper discussed a recent study of mercury removal by gaseous hydrogen chloride over novel Ce doped low vanadium V2O5-WO3/TiO2 catalysts under a bench scale condition. The performances on Hg(0) removal over the catalyst were tested in simulated flue gas with 80-100 microg x m(-3) Hg(0), 8% O2, 10 x10(-6) HCl, 8% H2O, 800 x10(-6) SO2 and balanced with N2. Results showed that about 95% of Hg(0) could be removed. According to the characterization results, BET surface areas had not significant influence on catalytic performance. XPS results indicated that Ce4+ oxide was a mainly form in the catalysts surface, which was beneficial for Hg(0) removal reactions. Water vapor slightly inhibited Hg(0) removal efficiency, due to the competitive adsorption, however, SO2 promoted the oxidation reactions, resulting in higher removal efficiencies. PMID:22165254

  3. Apparatus for control of mercury

    DOEpatents

    Downs, William; Bailey, Ralph T.

    2001-01-01

    A method and apparatus for reducing mercury in industrial gases such as the flue gas produced by the combustion of fossil fuels such as coal adds hydrogen sulfide to the flue gas in or just before a scrubber of the industrial process which contains the wet scrubber. The method and apparatus of the present invention is applicable to installations employing either wet or dry scrubber flue gas desulfurization systems. The present invention uses kraft green liquor as a source for hydrogen sulfide and/or the injection of mineral acids into the green liquor to release vaporous hydrogen sulfide in order to form mercury sulfide solids.

  4. Evaluation of in-vitro cytotoxicity and cellular uptake efficiency of zidovudine-loaded solid lipid nanoparticles modified with Aloe Vera in glioma cells.

    PubMed

    K S, Joshy; Sharma, Chandra P; Kalarikkal, Nandakumar; Sandeep, K; Thomas, Sabu; Pothen, Laly A

    2016-09-01

    Zidovudine loaded solid lipid nanoparticles of stearic acid modified with Aloe Vera (AV) have been prepared via simple emulsion solvent evaporation method which showed excellent stability at room temperature and refrigerated condition. The nanoparticles were examined by Fourier transform infrared spectroscopy (FT-IR), which revealed the overlap of the AV absorption peak with the absorption peak of modified stearic acid nanoparticles. The inclusion of AV to stearic acid decreased the crystallinity and improved the hydrophilicity of lipid nanoparticles and thereby improved the drug loading efficacy of lipid nanoparticles. Dynamic light scattering (DLS) and transmission electron microscopy (TEM) imaging revealed that, the average particle size of unmodified (bare) nanoparticles was 45.66±12.22nm and modified solid lipid nanoparticles showed an average size of 265.61±80.44nm. Solid lipid nanoparticles with well-defined morphology were tested in vitro for their possible application in drug delivery. Cell culture studies using C6 glioma cells on the nanoparticles showed enhanced growth and proliferation of cells without exhibiting any toxicity. In addition, normal cell morphology and improved uptake were observed by fluorescence microscopy images of rhodamine labeled modified solid lipid nanoparticles compared with unmodified nanoparticles. The cellular uptake study suggested that these nanoparticles could be a promising drug delivery system to enhance the uptake of antiviral drug by brain cells and it could be a suitable drug carrier system for the treatment of HIV. PMID:27207037

  5. Simultaneous saccharification and fermentation of delignified lignocellulosic biomass at high solid loadings by a newly isolated thermotolerant Kluyveromyces sp. for ethanol production.

    PubMed

    Narra, Madhuri; James, Jisha P; Balasubramanian, Velmurugan

    2015-03-01

    Simultaneous saccharification and fermentation studies were carried out using thermotolerant newly isolated Kluyveromyces sp. with three different delignified lignocellulosic biomass viz. rice straw, wheat straw and sugarcane bagasse at 5-15% solid loading and 6-12 FPU g(-1) substrate enzyme loading for different time intervals 0-72 h at 42°C. Maximum ethanol achieved from rice straw, wheat straw and sugarcane bagasse with in-house crude cellulases from Aspergillus terreus was 23.23, 18.29 and 17.91 mg mL(-1) at 60 h with 10% solid load and 9 FPU g(-1) substrate enzyme loading. Tween 80 1% (v/v) enhanced the ethanol yield by 8.39%, 9.26% and 8.14% in rice straw, wheat straw and sugarcane bagasse, respectively. External supplementation of β-glucosidase to the crude as well commercial cellulases produced maximum theoretical ethanol yield of 71.76%, 63.77%, 57.15% and 84.56%, 72.47%, 70.55% from rice straw, wheat straw and sugarcane bagasse, respectively.

  6. Mercury concentration in coal - Unraveling the puzzle

    USGS Publications Warehouse

    Toole-O'Neil, B.; Tewalt, S.J.; Finkelman, R.B.; Akers, D.J.

    1999-01-01

    Based on data from the US Geological Survey's COALQUAL database, the mean concentration of mercury in coal is approximately 0.2 ??gg-1. Assuming the database reflects in-ground US coal resources, values for conterminous US coal areas range from 0.08 ??gg-1 for coal in the San Juan and Uinta regions to 0.22 ??gg-1 for the Gulf Coast lignites. Recalculating the COALQUAL data to an equal energy basis unadjusted for moisture differences, the Gulf Coast lignites have the highest values (36.4 lb of Hg/1012 Btu) and the Hams Fork region coal has the lowest value (4.8 lb of Hg/1012Btu). Strong indirect geochemical evidence indicates that a substantial proportion of the mercury in coal is associated with pyrite occurrence. This association of mercury and pyrite probably accounts for the removal of mercury with the pyrite by physical coal cleaning procedures. Data from the literature indicate that conventional coal cleaning removes approximately 37% of the mercury on an equal energy basis, with a range of 0% to 78%. When the average mercury reduction value is applied to in-ground mercury values from the COALQUAL database, the resulting 'cleaned' mercury values are very close to mercury in 'as-shipped' coal from the same coal bed in the same county. Applying the reduction fact or for coal cleaning to eastern US bituminous coal, reduces the mercury input load compared to lower-rank non-deaned western US coal. In the absence of analytical data on as-shipped coal, the mercury data in the COALQUAL database, adjusted for deanability where appropriate, may be used as an estimator of mercury contents of as-shipped coal. ?? 1998 Published by Elsevier Science Ltd. All rights reserved.

  7. Mercury, elemental

    Integrated Risk Information System (IRIS)

    Mercury , elemental ; CASRN 7439 - 97 - 6 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarcinoge

  8. Mercury's Messenger

    ERIC Educational Resources Information Center

    Chapman, Clark R.

    2004-01-01

    Forty years after Mariner 2, planetary exploration has still only just begun, and many more missions are on drawing boards, nearing the launch pad, or even en route across interplanetary space to their targets. One of the most challenging missions that will be conducted this decade is sending the MESSENGER spacecraft to orbit the planet Mercury.…

  9. Mercury and methylmercury related to historical mercury mining in three tributaries to Lake Berryessa, Putah Creek Watershed, California

    NASA Astrophysics Data System (ADS)

    Sparks, G. C.; Horner, T.; Cornwell, K.; Izzo, V.; Alpers, C. N.

    2014-12-01

    This study examined the relative contribution of total mercury (THg) and mono-methylmercury (MMHg) from upstream historical mercury-mining districts to Lake Berryessa, a reservoir with impaired water quality because of mercury. The third and fourth largest historical mercury-producing mining districts in California are within Lake Berryessa's three largest tributary watersheds: Pope, (Upper) Putah, and Knoxville-Eticuera Creeks. Downstream of the reservoir, Putah Creek drains into the Yolo Bypass, a major source of THg and MMHg to the Sacramento-San Joaquin Delta. Water samples were collected from October 2012 to May 2014 during 37 non-storm and 8 storm events along Pope, (Upper) Putah, and Knoxville-Eticuera Creeks and analyzed for field parameters (temperature, pH, specific conductance, dissolved oxygen, and turbidity). Additionally, water samples collected during five of the non-storm and storm events were analyzed for unfiltered THg and MMHg and total suspended solids (TSS). Discharge was measured during sampling to calculate instantaneous loads. More than 120 streambed sediment samples were collected to determine the spatial variation of THg and organic carbon content (loss on ignition). Across the watersheds, unfiltered THg (in water) samples ranged from 2.3 to 125 ng/L and unfiltered MMHg (in water) samples from 0.12 to 1.0 ng/L. Concentrations of THg ranged from less than 0.0001 to 122 mg/kg in streambed sediment. Tributary reaches with elevated mercury concentrations ("hot spots") are near or downstream of historical mercury mines and have: (1) strong positive correlations between THg (in water) or MMHg (in water) and TSS (R2> 0.88, n=5); (2) higher instantaneous loads of suspended sediment, THg and MMHg than reaches with low THg and MMHg concentrations; and (3) elevated sediment organic carbon content. Tributary reaches with weaker correlations among THg, MMHg, and TSS in unfiltered water may reflect non-mining sources of dissolved THg and MMHg, such as

  10. Substance Flow Analysis of Mercury in China

    NASA Astrophysics Data System (ADS)

    Hui, L. M.; Wang, S.; Zhang, L.; Wang, F. Y.; Wu, Q. R.

    2015-12-01

    In previous studies, the emission of anthropogenic atmospheric Hg in China as well as single sector have been examined a lot. However, there might have been more Hg released as solid wastes rather than air. Hg stored in solid wastes may be released to air again when the solid wastes experience high temperature process or cause local pollution if the solid wastes are stacked casually for a long time. To trace the fate of Hg in China, this study developed the substance flow of Hg in 2010 covering all the sectors summarized in table 1. Below showed in Figure 1, the total Hg input is 2825t. The unintentional input of Hg, mined Hg, and recycled Hg account for 57%, 32% and 11% respectively. Figure 2 provides the detail information of substance flow of Hg. Byproducts from one sector may be used as raw materials of another, causing cross Hg flow between sectors. The Hg input of cement production is 303 t, of which 34% comes from coal and limestone, 33% comes from non-ferrous smelting, 23% comes from coal combustion, 7% comes from iron and steel production and 3% comes from mercury mining. Hg flowing to recycledHg production is 639 t, mainly from Hg contained in waste active carbon and mercuric chloride catalyst from VCM production and acid sludge from non-ferrous smelting. There are 20 t mercury flowing from spent mercury adding products to incineration. Figure1 and Figure 2 also show that 46% of the output Hg belongs to "Lagged release", which means this part of mercury might be released later. The "Lagged release" Hg includes 809 t Hg contained in stacked byproducts form coal combustion, non-ferrous smelting, iron and steel production, Al production, cement production and mercury mining, 161t Hg stored in the pipeline of VCM producing, 10 t Hg in fluorescent lamps that are in use and 314 t mercury stored in materials waiting to be handled with in recycled mercury plants. There is 112 t Hg stored in landfill and 129 t Hg exported abroad with the export of mercury adding

  11. Revealing Mercury

    NASA Astrophysics Data System (ADS)

    Prockter, L. M.; Solomon, S. C.; Head, J. W.; Watters, T. R.; Murchie, S. L.; Robinson, M. S.; Chapman, C. R.; McNutt, R. L.

    2009-04-01

    The MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft, developed under NASA's Discovery Program, launched in August 2004. En route to insertion into orbit about Mercury in 2011, MESSENGER flies by Mercury three times. The first and second of these encounters were accomplished in January and October of 2008. These flybys viewed portions of Mercury's surface that were not observed by Mariner 10 during its reconnaissance of somewhat less than half of the planet in 1974-1975. All MESSENGER instruments operated during each flyby and returned a wealth of new data. Many of the new observations were focused on the planet's geology, including monochrome imaging at resolutions as high as 100 m/pixel, multispectral imaging in 11 filters at resolutions as high as 500 m/pixel, laser altimetry tracks extending over several thousands of kilometers, and high-resolution spectral measurements of several types of terrain. Here we present an overview of the first inferences on the global geology of Mercury from the MESSENGER observations. Whereas evidence for volcanism was equivocal from Mariner 10 data, the new MESSENGER images and altimetry provide compelling evidence that volcanism was widespread and protracted on Mercury. Color imaging reveals three common spectral units on the surface: a higher-reflectance, relatively red material occurring as a distinct class of smooth plains, typically with distinct embayment relationships interpreted to indicate volcanic emplacement; a lower-reflectance, relatively blue material typically excavated by impact craters and therefore inferred to be more common at depth; and a spectrally intermediate terrain that constitutes much of the uppermost crust. Three more minor spectral units are also seen: fresh crater ejecta, reddish material associated with rimless depressions interpreted to be volcanic centers, and high-reflectance deposits seen in some crater floors. Preliminary measurements of crater size

  12. Mercury's South Polar Region

    NASA Video Gallery

    This animation shows 89 wide-angle camera (WAC) images of Mercury’s south polar region acquired by the Mercury Dual Imaging System (MDIS) over one complete Mercury solar day (176 Earth days). Thi...

  13. Propagated fixed-bed mixed-acid fermentation: effect of volatile solid loading rate and agitation at near-neutral pH.

    PubMed

    Golub, Kristina W; Golub, Stacey R; Meysing, Daniel M; Holtzapple, Mark T

    2012-11-01

    To increase conversion and product concentration, mixed-acid fermentation can use a countercurrent strategy where solids and liquids pass in opposite directions through a series of fermentors. To limit the requirement for moving solids, this study employed a propagated fixed-bed fermentation, where solids were stationary and only liquid was transferred. To evaluate the role of agitation, continuous mixing was compared with periodic mixing. The periodically mixed fermentation had similar conversion, but lower yield and selectivity. Increasing volatile solid loading rate from 1.5 to 5.1g non-acid volatile solids/(L(liq)·d) and increasing liquid retention time decreased yield, conversion, selectivity, but increased product concentrations. Compared to a previous study at high pH (~9), this study achieved higher performance at near neutral pH (~6.5) and optimal C-N ratios. Compared to countercurrent fermentation, propagated fixed-bed fermentations have similar selectivities and produce similar proportions of acetic acid, but have lower yields, conversion, productivities, and acid concentrations. PMID:22995159

  14. Propagated fixed-bed mixed-acid fermentation: effect of volatile solid loading rate and agitation at near-neutral pH.

    PubMed

    Golub, Kristina W; Golub, Stacey R; Meysing, Daniel M; Holtzapple, Mark T

    2012-11-01

    To increase conversion and product concentration, mixed-acid fermentation can use a countercurrent strategy where solids and liquids pass in opposite directions through a series of fermentors. To limit the requirement for moving solids, this study employed a propagated fixed-bed fermentation, where solids were stationary and only liquid was transferred. To evaluate the role of agitation, continuous mixing was compared with periodic mixing. The periodically mixed fermentation had similar conversion, but lower yield and selectivity. Increasing volatile solid loading rate from 1.5 to 5.1g non-acid volatile solids/(L(liq)·d) and increasing liquid retention time decreased yield, conversion, selectivity, but increased product concentrations. Compared to a previous study at high pH (~9), this study achieved higher performance at near neutral pH (~6.5) and optimal C-N ratios. Compared to countercurrent fermentation, propagated fixed-bed fermentations have similar selectivities and produce similar proportions of acetic acid, but have lower yields, conversion, productivities, and acid concentrations.

  15. A novel solid-state NMR method for the investigation of trivalent lanthanide sorption on amorphous silica at low surface loadings.

    PubMed

    Mason, H E; Begg, J D; Maxwell, R S; Kersting, A B; Zavarin, M

    2016-07-13

    The modelling of radionuclide transport in the subsurface depends on a comprehensive understanding of their interactions with mineral surfaces. Spectroscopic techniques provide important insight into these processes directly, but at high concentrations are sometimes hindered by safety concerns and limited solubilities of many radionuclides, especially the actinides. Here we use Eu(iii) as a surrogate for trivalent actinide species, and study Eu(iii) sorption on the silica surface at pH 5 where sorption is fairly limited. We have applied a novel, surface selective solid-state nuclear magnetic resonance (NMR) technique to provide information about Eu binding at the silica surface at estimated surface loadings ranging from 0.1 to 3 nmol m(-2) (<0.1% surface loading). The NMR results show that inner sphere Eu(iii) complexes are evenly distributed across the silica surface at all concentrations, but that at the highest surface loadings there are indications that precipitates may form. These results illustrate that this NMR technique may be applied in solubility-limited systems to differentiate between adsorption and precipitation to better understand the interactions of radionuclides at solid surfaces. PMID:27291345

  16. Effect of organic loading rate on the performance of two-stage anaerobic digestion of the organic fraction of municipal solid waste (OFMSW).

    PubMed

    Rodríguez-Pimentel, Reyna I; Rodríguez-Pérez, Suyen; Monroy-Hermosillo, Oscar; Ramírez-Vives, Florina

    2015-01-01

    Two-stage anaerobic digestion of the organic fraction of municipal solid waste (OFMSW) was carried out: hydrolysis and acidogenesis in a continuous anaerobic hydrolytic leach bed (AHLB) reactor loaded at different rates (Bv = 3.8-7 gVSSL⁻¹d⁻¹) and methanogenesis of leachates, diluted with municipal wastewater in an upflow anaerobic sludge blanket (UASB) reactor at organic loading rates of 6.6-13 gCODLr⁻¹d⁻¹. In the AHLB reactor, 51-76% and 58-71% volatile solids and chemical oxygen demand (COD) removal efficiencies were obtained. During the hydrolysis and acidogenesis phases, the effluents were at pH 4.93, the leachate had a volatile fatty acids concentration of 35 g/L and the biogas was composed only of CO₂. The average methane production in the UASB in the load of 4.4 gVS L⁻¹ d⁻¹ in the AHLB was 3.32 LCH4Lr⁻¹d⁻¹ (yCH4 = 80%), with COD removal efficiency of 95% and methane yield 279 LCH4KgVS⁻¹OFMSW degraded.

  17. Mercury Sorption onto Malt Spent Rootlets

    NASA Astrophysics Data System (ADS)

    Manariotis, I. D.; Anagnostopoulos, V.; Karapanagioti, H. K.; Chrysikopoulos, C.

    2011-12-01

    Mercury is a metal of particular concern due to its toxicity even at relatively low concentrations. The maximum permissible level for mercury in drinking water set by the European Union is 0.001 mg/L. Mercury is released into the environment via four principal pathways: (1) natural processes; i.e. a volcanic eruption, (2) incidental to some other activity; i.e. coal burning power plants, (3) accidentally during the manufacture, breakage or disposal of products that have mercury put into them deliberately, and (4) direct use in industrial settings. The present study focuses on the removal of mercury (II) from aqueous solutions via sorption onto Malt Spent Rootlets (MSR). Batch experiments were conducted employing MSR with size ranging from 0.18 to 1 mm. The effects of pH, mercury concentration, contact time, and solid to liquid ratio on mercury sorption onto MSR were investigated. The highest mercury removal from the aqueous phase, of 41%, was observed at pH of 5.

  18. Characterizing response of total suspended solids and total phosphorus loading to weather and watershed characteristics for rainfall and snowmelt events in agricultural watersheds

    USGS Publications Warehouse

    Danz, Mari E.; Corsi, Steven; Brooks, Wesley R.; Bannerman, Roger T.

    2013-01-01

    Understanding the response of total suspended solids (TSS) and total phosphorus (TP) to influential weather and watershed variables is critical in the development of sediment and nutrient reduction plans. In this study, rainfall and snowmelt event loadings of TSS and TP were analyzed for eight agricultural watersheds in Wisconsin, with areas ranging from 14 to 110 km2 and having four to twelve years of data available. The data showed that a small number of rainfall and snowmelt runoff events accounted for the majority of total event loading. The largest 10% of the loading events for each watershed accounted for 73–97% of the total TSS load and 64–88% of the total TP load. More than half of the total annual TSS load was transported during a single event for each watershed at least one of the monitored years. Rainfall and snowmelt events were both influential contributors of TSS and TP loading. TSS loading contributions were greater from rainfall events at five watersheds, from snowmelt events at two watersheds, and nearly equal at one watershed. The TP loading contributions were greater from rainfall events at three watersheds, from snowmelt events at two watersheds and nearly equal at three watersheds. Stepwise multivariate regression models for TSS and TP event loadings were developed separately for rainfall and snowmelt runoff events for each individual watershed and for all watersheds combined by using a suite of precipitation, melt, temperature, seasonality, and watershed characteristics as predictors. All individual models and the combined model for rainfall events resulted in two common predictors as most influential for TSS and TP. These included rainfall depth and the antecedent baseflow. Using these two predictors alone resulted in an R2 greater than 0.7 in all but three individual models and 0.61 or greater for all individual models. The combined model yielded an R2 of 0.66 for TSS and 0.59 for TP. Neither the individual nor the combined models were

  19. Automated on-line preconcentration of trace aqueous mercury with gold trap focusing for cold vapor atomic absorption spectrometry.

    PubMed

    Puanngam, Mahitti; Dasgupta, Purnendu K; Unob, Fuangfa

    2012-09-15

    A fully automated system for the determination of trace mercury in water by cold vapor atomic absorption spectrometry (CVAAS) is reported. The system uses preconcentration on a novel sorbent followed by liberation of the mercury and focusing by a gold trap. Mercury ions were extracted from water samples by passage through a solid phase sorbent column containing 2-(3-(2-aminoethylthio)propylthio)ethanamine modified silica gel. The captured mercury is released by thiourea and then elemental Hg is liberated by sodium borohydride. The vapor phase Hg is recaptured on a gold-plated tungsten filament. This is liberated as a sharp pulse (half-width<2 s) by directly electrically heating the tungsten filament in a dry argon stream. The mercury is measured by CVAAS; no moisture removal is needed. The effects of chloride and selected interfering ions were studied. The sample loading flow rate and argon flow rates for solution purging and filament sweeping were optimized. An overall 50-fold improvement in the limit of detection was observed relative to direct measurement by CVAAS. With a relatively modest multi-user instrument we attained a limit of detection of 35 ng L(-1) with 12% RSD at 0.20 μg L(-1) Hg level. The method was successfully applied to accurately determine sub-μg L(-1) level Hg in standard reference water samples.

  20. Propagated fixed-bed mixed-acid fermentation: Part I: Effect of volatile solid loading rate and agitation at high pH.

    PubMed

    Golub, Kristina W; Forrest, Andrea K; Mercy, Kevin L; Holtzapple, Mark T

    2011-11-01

    Countercurrent fermentation is a high performing process design for mixed-acid fermentation. However, there are high operating costs associated with moving solids, which is an integral component of this configuration. This study investigated the effect of volatile solid loading rate (VSLR) and agitation in propagated fixed-bed fermentation, a configuration which may be more commercially viable. To evaluate the role of agitation on fixed-bed configuration performance, continuous mixing was compared with periodic mixing. VSLR was also varied and not found to affect acid yields. However, increased VSLR and liquid retention time did result in higher conversions, productivity, acid concentrations, but lower selectivities. Agitation was demonstrated to be important for this fermentor configuration, the periodically-mixed fermentation had the lowest conversion and yields. Operating at a high pH (∼9) contributed to the high selectivity to acetic acid, which might be industrially desirable but at the cost of lower yield compared to a neutral pH.

  1. Mercury's Magnetosphere

    NASA Technical Reports Server (NTRS)

    Slavin, J. A.

    1999-01-01

    Among the major discoveries made by the Mariner 10 mission to the inner planets was the existence of an intrinsic magnetic field at Mercury with a dipole moment of approx. 300 nT R(sup 3, sub M). This magnetic field is sufficient to stand off the solar wind at an altitude of about 1 R(sub M) (i.e. approx. 2439 km). Hence, Mercury possesses a 'magnetosphere' from which the so]ar wind plasma is largely excluded and within which the motion of charged particles is controlled by the planetary magnetic field. Despite its small size relative to the magnetospheres of the other planets, a Mercury orbiter mission is a high priority for the space physics community. The primary reason for this great interest is that Mercury unlike all the other planets visited thus far, lacks a significant atmosphere; only a vestigial exosphere is present. This results in a unique situation where the magnetosphere interacts directly with the outer layer of the planetary crust (i.e. the regolith). At all of the other planets the topmost regions of their atmospheres become ionized by solar radiation to form ionospheres. These planetary ionospheres then couple to electrodynamically to their magnetospheres or, in the case of the weakly magnetized Venus and Mars, directly to the solar wind. This magnetosphere-ionosphere coupling is mediated largely through field-aligned currents (FACs) flowing along the magnetic field lines linking the magnetosphere and the high-latitude ionosphere. Mercury is unique in that it is expected that FACS will be very short lived due to the low electrical conductivity of the regolith. Furthermore, at the earth it has been shown that the outflow of neutral atmospheric species to great altitudes is an important source of magnetospheric plasma (following ionization) whose composition may influence subsequent magnetotail dynamics. However, the dominant source of plasma for most of the terrestrial magnetosphere is the 'leakage'of solar wind across the magnetopause and more

  2. Optimization of process variables of zanamivir-loaded solid lipid nanoparticles and the prediction of their cellular transport in Caco-2 cell model.

    PubMed

    Shi, Li-Li; Cao, Yue; Zhu, Xiao-Yin; Cui, Jing-Hao; Cao, Qing-Ri

    2015-01-15

    The aim of this study was to optimize the process variables of zanamivir-loaded solid lipid nanoparticles (SLNs) and to predict their cellular transport across Caco-2 cell monolayers. Zanamivir-loaded SLNs were prepared by a double emulsion solvent evaporation method. The effects of process variables on the mean particle size and zeta potential of SLNs were investigated and the physicochemical properties of SLNs were characterized. In addition, the cytotoxicity and transport ability of SLNs were also studied in Caco-2 cell model. The mean particle size of drug-loaded SLNs was significantly affected by the process variables. The SLNs were prepared using glyceryl monosterate (1% polyvinyl alcohol (PVA) or 1.5% poloxamer 188 as surfactant) had a regular shape with a relatively lower mean particle size (324.2 and 224.9 nm, respectively), higher encapsulation efficacy (55.7 and 42.4%, respectively) and sustained drug release over 12h. The crystalline form of drug had been partly changed and no physicochemical interaction had occurred between drug and carriers in SLNs. The cell viability was approximately 100% even at a high concentration of blank SLNs. There was no remarkable difference in drug permeation between drug-loaded SLNs and drug solution at 2h, while drug-loaded SLNs showed a significant decrease in drug permeation compared with the drug solution at 4h. The process variables of zanamivir-loaded SLNs were successfully optimized in this study. However, these SLNs significantly reduced the transport ability of zanamivir across Caco-2 cell monolayers. Further studies are needed to fully understand the real absorption mechanism of developed SLNs.

  3. Mercury mine drainage and processes that control its environmental impact

    USGS Publications Warehouse

    Rytuba, J.J.

    2000-01-01

    H range of 3.2-7.1 in streams impacted by mine drainage. The dissolved fraction of both mercury species is depleted and concentrated in iron oxyhydroxide such that the amount of iron oxyhydroxide in the water column reflects the concentration of mercury species. In streams impacted by mine drainage, mercury and methylmercury are transported and adsorbed onto particulate phases. During periods of low stream flow, fine-grained iron hydroxide sediment accumulates in the bed load of the stream and adsorbs mercury and methylmercury such that both forms of mercury become highly enriched in the iron oxyhydroxide sediment. During high-flow events, mercury- and methylmercury-enriched iron hydroxide sediment is transported into larger aquatic systems producing a high flux of bioavailable mercury. (C) 2000 Elsevier Science B.V.

  4. MERCURY RESEARCH STRATEGY.

    EPA Science Inventory

    The USEPA's ORD is pleased to announce the availability of its Mercury Research Strategy. This strategy guides ORD's mercury research program and covers the FY2001-2005 time frame. ORD will use it to prepare a multi-year mercury research implementation plan in 2001. The Mercury R...

  5. Mercury contamination extraction

    DOEpatents

    Fuhrmann, Mark; Heiser, John; Kalb, Paul

    2009-09-15

    Mercury is removed from contaminated waste by firstly applying a sulfur reagent to the waste. Mercury in the waste is then permitted to migrate to the reagent and is stabilized in a mercury sulfide compound. The stable compound may then be removed from the waste which itself remains in situ following mercury removal therefrom.

  6. Is mercury from Hawaiian volcanoes a natural source of pollution.

    NASA Technical Reports Server (NTRS)

    Eshleman, A.; Siegel, S. M.; Siegel, B. Z.

    1971-01-01

    An analysis shows that 98% of mercury from Hawaiian fumaroles is gaseous or solid particles less than 0.3 micron in diameter. It is suggested that both natural and industrial sources may be contributors to mercury pollution of the air in Hawaii.

  7. Mercury and health care.

    PubMed

    Rustagi, Neeti; Singh, Ritesh

    2010-08-01

    Mercury is toxic heavy metal. It has many characteristic features. Health care organizations have used mercury in many forms since time immemorial. The main uses of mercury are in dental amalgam, sphygmomanometers, and thermometers. The mercury once released into the environment can remain for a longer period. Both acute and chronic poisoning can be caused by it. Half of the mercury found in the atmosphere is human generated and health care contributes the substantial part to it. The world has awakened to the harmful effects of mercury. The World Health Organization and United Nations Environmental Programme (UNEP) have issued guidelines for the countries' health care sector to become mercury free. UNEP has formed mercury partnerships between governments and other stakeholders as one approach to reducing risks to human health and the environment from the release of mercury and its compounds to the environment. Many hospitals are mercury free now.

  8. Mercury and health care

    PubMed Central

    Rustagi, Neeti; Singh, Ritesh

    2010-01-01

    Mercury is toxic heavy metal. It has many characteristic features. Health care organizations have used mercury in many forms since time immemorial. The main uses of mercury are in dental amalgam, sphygmomanometers, and thermometers. The mercury once released into the environment can remain for a longer period. Both acute and chronic poisoning can be caused by it. Half of the mercury found in the atmosphere is human generated and health care contributes the substantial part to it. The world has awakened to the harmful effects of mercury. The World Health Organization and United Nations Environmental Programme (UNEP) have issued guidelines for the countries’ health care sector to become mercury free. UNEP has formed mercury partnerships between governments and other stakeholders as one approach to reducing risks to human health and the environment from the release of mercury and its compounds to the environment. Many hospitals are mercury free now. PMID:21120080

  9. Potential hazards of brominated carbon sorbents for mercury emission control.

    PubMed

    Bisson, Teresa M; Xu, Zhenghe

    2015-02-17

    Mercury is a toxic air pollutant, emitted from the combustion of coal. Activated Carbon (AC) or other carbon sorbent (CS) injection into coal combustion flue gases can remove elemental mercury through an adsorption process. Recently, a brominated CS with biomass ash as the carbon source (Br-Ash) was developed as an alternative for costly AC-based sorbent for mercury capture. After mercury capture, these sorbents are disposed in landfill, and the stability of bromine and captured mercury is of paramount importance. The objective of this study is to determine the fate of mercury and bromine from Br-Ash and brominated AC after their service. Mercury and bromine leaching tests were conducted using the standard toxicity characteristic leaching procedure (TCLP). The mercury was found to be stable on both the Br-Ash and commercial brominated AC sorbents, while the bromine leached into the aqueous phase considerably. Mercury pulse injection tests on the sorbent material after leaching indicate that both sorbents retain significant mercury capture capability even after the majority of bromine was removed. Testing of the Br-Ash sorbent over a wider range of pH and liquid:solid ratios resulted in leaching of <5% of mercury adsorbed on the Br-Ash. XPS analysis indicated more organically bound Br and less metal-Br bonds after leaching.

  10. Sodium alginate-cross-linked polymyxin B sulphate-loaded solid lipid nanoparticles: Antibiotic resistance tests and HaCat and NIH/3T3 cell viability studies.

    PubMed

    Severino, Patrícia; Chaud, Marco V; Shimojo, Andrea; Antonini, Danilo; Lancelloti, Marcelo; Santana, Maria Helena A; Souto, Eliana B

    2015-05-01

    Polymyxins are a group of antibiotics with a common structure of a cyclic peptide with a long hydrophobic tail. Polymyxin B sulphate (PLX) has cationic charge, which is an obstacle for the efficient loading into Solid Lipid Nanoparticles (SLN). In the present paper, we describe an innovative method to load PLX into SLN to achieve the sustained release of the drug. PLX was firstly cross-linked with sodium alginate (SA) at different ratios (1:1, 1:2 and 1:3 SA/PLX), and loaded into SLN produced by high pressure homogenization (HPH). Optimized SLN were produced applying 500bar pressure and 5 homogenization cycles. The best results were obtained with SA/PLX (1:1), recording 99.08±1.2% for the association efficiency of the drug with SA, 0.99±10g for the loading capacity and 212.07±5.84% degree of swelling. The rheological profile of aqueous SA solution followed the typical behaviour of concentrated polymeric solutions, whereas aqueous SA/PLX solution exhibited a gel-like dynamic behaviour. Micrographs show that SA/PLX depicted a porous and discontinuous amorphous phase in different ratios. The encapsulation efficiency of SA/PLX (1:1) in SLN, the mean particle diameter, polydispersity index and zeta potential were, respectively, 82.7±5.5%; 439.5±20.42nm, 0.241±0.050 and -34.8±0.55mV. The effect of SLN on cell viability was checked in HaCat and NIH/3T3 cell lines, and the minimal inhibitory concentrations (MIC) were determined in Pseudomonas aeruginosa strains. SA/PLX-loaded SLN were shown to be less toxic than free PLX. Minimal inhibitory concentrations (MIC) showed the presence of the cross-linker polymer-drug complex, and SLN were shown to enhance MIC in the evaluated strains.

  11. Mercury speciation modeling using site specific chemical and redox data from the TNXOD OU

    SciTech Connect

    Kaplan, D.I.

    2000-03-22

    The objective of this study was to evaluate mercury speciation under reducing conditions expected in sediments at the TNX Outfall Delta Operable Unit. These changes in speciation would then be used to infer whether mercury toxicity and mobility would be expected to be significantly altered under reducing conditions. The results from this work suggest that mercury would likely become more strongly retained by the solid phase under reducing conditions than under oxidizing conditions at the TNX Outfall Delta Site. Considering that experimental results indicate that mercury is extremely tightly bound to the solid phase under oxidizing conditions, little mercury mobility would therefore be expected under reducing conditions.

  12. Mercury Quick Facts: Health Effects of Mercury Exposure

    MedlinePlus

    Mercury Quick Facts Health Effects of Mercury Exposure What is Elemental Mercury? Elemental (metallic) mercury is the shiny, silver-gray metal found in thermometers, barometers, and thermostats and other ...

  13. Streamflow and estimated loads of phosphorus and dissolved and suspended solids from selected tributaries to Lake Ontario, New York, water years 2012–14

    USGS Publications Warehouse

    Hayhurst, Brett A.; Fisher, Benjamin N.; Reddy, James E.

    2016-07-20

    This report presents results of the evaluation and interpretation of hydrologic and water-quality data collected as part of a cooperative program between the U.S. Geological Survey and the U.S. Environmental Protection Agency. Streamflow, phosphorus, and solids dissolved and suspended in stream water were the focus of monitoring by the U.S. Geological Survey at 10 sites on 9 selected tributaries to Lake Ontario during the period from October 2011 through September 2014. Streamflow yields (flow per unit area) were the highest from the Salmon River Basin due to sustained yields from the Tug Hill aquifer. The Eighteenmile Creek streamflow yields also were high as a result of sustained base flow contributions from a dam just upstream of the U.S. Geological Survey monitoring station at Burt. The lowest streamflow yields were measured in the Honeoye Creek Basin, which reflects a decrease in flow because of withdrawals from Canadice and Hemlock Lakes for the water supply of the City of Rochester. The Eighteenmile Creek and Oak Orchard Creek Basins had relatively high yields due in part to groundwater contributions from the Niagara Escarpment and seasonal releases from the New York State Barge Canal.Annual constituent yields (load per unit area) of suspended solids, phosphorus, orthophosphate, and dissolved solids were computed to assess the relative contributions and allow direct comparison of loads among the monitored basins. High yields of total suspended solids were attributed to agricultural land use in highly erodible soils at all sites. The Genesee River, Irondequoit Creek, and Honeoye Creek had the highest concentrations and largest mean yields of total suspended solids (165 short tons per square mile [t/mi2], 184 t/mi2, and 89.7 t/mi2, respectively) of the study sites.Samples from Eighteenmile Creek, Oak Orchard Creek at Kenyonville, and Irondequoit Creek had the highest concentrations and largest mean yields of phosphorus (0.27 t/mi2, 0.26 t/mi2, and 0.20 t/mi2

  14. Evolved strains of Scheffersomyces stipitis achieving high ethanol productivity on acid- and base-pretreated biomass hydrolyzate at high solids loading

    DOE PAGES

    Slininger, Patricia J.; Shea-Andersh, Maureen A.; Thompson, Stephanie R.; Dien, Bruce S.; Kurtzman, Cletus P.; Balan, Venkatesh; da Costa Sousa, Leonardo; Uppugundla, Nirmal; Dale, Bruce E; Cotta, Michael A

    2015-04-09

    Lignocellulosic biomass is an abundant, renewable feedstock useful for the production of fuel-grade ethanol via the processing steps of pretreatment, enzyme hydrolysis, and microbial fermentation. Traditional industrial yeasts do not ferment xylose and are not able to grow, survive, or ferment in concentrated hydrolyzates that contain enough sugar to support economical ethanol recovery since they are laden with toxic byproducts generated during pretreatment. Repetitive culturing in two types of concentrated hydrolyzates was applied along with ethanol challenged xylose-fed continuous culture to force targeted evolution of the native pentose fermenting yeast Scheffersomyces (Pichia) stipitis strain NRRL Y-7124 maintained in the ARSmore » Culture Collection, Peoria, IL. Isolates collected from various enriched populations were screened and ranked based on relative xylose uptake rate and ethanol yield. Ranking on hydrolyzates with and without nutritional supplementation was used to identify those isolates with best performance across diverse conditions. Robust S. stipitis strains adapted to perform very well in enzyme hydrolyzates of high solids loading ammonia fiber expansion-pretreated corn stover (18% weight per volume solids) and dilute sulfuric acid-pretreated switchgrass (20% w/v solids) were obtained. Improved features include reduced initial lag phase preceding growth, significantly enhanced fermentation rates, improved ethanol tolerance and yield, reduced diauxic lag during glucose-xylose transition, and ability to accumulate >40 g/L ethanol in <167 h when fermenting hydrolyzate at low initial cell density of 0.5 absorbance units and pH 5 to 6.« less

  15. Novel dual-reverse thermosensitive solid lipid nanoparticle-loaded hydrogel for rectal administration of flurbiprofen with improved bioavailability and reduced initial burst effect.

    PubMed

    Din, Fakhar Ud; Mustapha, Omer; Kim, Dong Wuk; Rashid, Rehmana; Park, Jong Hyuck; Choi, Ju Yeon; Ku, Sae Kwang; Yong, Chul Soon; Kim, Jong Oh; Choi, Han-Gon

    2015-08-01

    The purpose of this study was to develop novel solid lipid nanoparticle (SLN)-loaded dual-reverse thermosensitive hydrogel (DRTH) for rectal administration of flurbiprofen with improved bioavailability and reduced initial burst effect. The flurbiprofen-loaded SLNs were prepared by hot homogenisation technique, after optimising the amounts of lipid mixture (tricaprin and triethanolamine in 8:2 weight ratio), drug and surfactant. The flurbiprofen-loaded thermosensitive SLN composed of drug, lipid mixture and surfactant at a weight ratio of 10/15/1.3 was a solid at room temperature, and changed to liquid form at physiological temperature due to its melting point of about 32°C. This SLN gave the mean particle size of about 190nm and entrapment efficiency of around 90%. The DRTHs were prepared by adding this flurbiprofen-loaded thermosensitive SLN in various poloxamer solutions. Their rheological characterisation, release and stability were investigated while a morphological and pharmacokinetic study was performed after its rectal administration to rats compared with the drug and hydrogel. Poloxamer 188 and SLN decreased the gelation temperature and gelation time, but increased the viscosity at 25°C, gel strength and mucoadhesive force of DRTHs. In particular, the DRTH composed of [SLN/P 407/P 188 (10%/15%/25%)] with the gelation temperature of about 35°C existed as liquid at room temperature, but gelled at 30-36°C, leading to opposite reversible property of SLN. Thus, it was easy to administer rectally, and it gelled rapidly inside the body. This DRTH gave a significantly increased dissolution rate of the drug as compared to the flurbiprofen, but significantly retarded as compared to the hydrogel, including the initial dissolution rate. Moreover, this DRTH gave significantly higher plasma concentration and 7.5-fold AUC values compared to the drug, and lower initial plasma concentration and Cmax value compared to the hydrogel due to reduced initial burst effect. No

  16. Novel dual-reverse thermosensitive solid lipid nanoparticle-loaded hydrogel for rectal administration of flurbiprofen with improved bioavailability and reduced initial burst effect.

    PubMed

    Din, Fakhar Ud; Mustapha, Omer; Kim, Dong Wuk; Rashid, Rehmana; Park, Jong Hyuck; Choi, Ju Yeon; Ku, Sae Kwang; Yong, Chul Soon; Kim, Jong Oh; Choi, Han-Gon

    2015-08-01

    The purpose of this study was to develop novel solid lipid nanoparticle (SLN)-loaded dual-reverse thermosensitive hydrogel (DRTH) for rectal administration of flurbiprofen with improved bioavailability and reduced initial burst effect. The flurbiprofen-loaded SLNs were prepared by hot homogenisation technique, after optimising the amounts of lipid mixture (tricaprin and triethanolamine in 8:2 weight ratio), drug and surfactant. The flurbiprofen-loaded thermosensitive SLN composed of drug, lipid mixture and surfactant at a weight ratio of 10/15/1.3 was a solid at room temperature, and changed to liquid form at physiological temperature due to its melting point of about 32°C. This SLN gave the mean particle size of about 190nm and entrapment efficiency of around 90%. The DRTHs were prepared by adding this flurbiprofen-loaded thermosensitive SLN in various poloxamer solutions. Their rheological characterisation, release and stability were investigated while a morphological and pharmacokinetic study was performed after its rectal administration to rats compared with the drug and hydrogel. Poloxamer 188 and SLN decreased the gelation temperature and gelation time, but increased the viscosity at 25°C, gel strength and mucoadhesive force of DRTHs. In particular, the DRTH composed of [SLN/P 407/P 188 (10%/15%/25%)] with the gelation temperature of about 35°C existed as liquid at room temperature, but gelled at 30-36°C, leading to opposite reversible property of SLN. Thus, it was easy to administer rectally, and it gelled rapidly inside the body. This DRTH gave a significantly increased dissolution rate of the drug as compared to the flurbiprofen, but significantly retarded as compared to the hydrogel, including the initial dissolution rate. Moreover, this DRTH gave significantly higher plasma concentration and 7.5-fold AUC values compared to the drug, and lower initial plasma concentration and Cmax value compared to the hydrogel due to reduced initial burst effect. No

  17. Biogeochemistry of mercury in the Amazonian environment.

    PubMed

    Wasserman, Julio Cesar; Hacon, Sandra; Wasserman, Maria Angélica

    2003-08-01

    In this paper, the processes that affect mercury (Hg) cycling in the Amazonian environment were reviewed, criticized and new directions of research are proposed. The discussion of the origin of the mercury contamination, whether natural or anthropogenic is marked by a lack of fundamented arguments from both sides. Undoubtedly mercury inputs from gold mining have locally increased environmental concentrations, but in the whole Amazon, these loads would be insignificant, considering the high concentrations observed by some authors in remote soils. A reasonable process that should explain these elevated concentrations in soil is that B horizons function as a mercury "sponge" that have been accumulating mercury over a geological time scale, releasing it back to cycling during erosion and forest fires. The environmental degradation of the Amazonian forest due to human activities is probably enhancing the release of that mercury to the cycle. Mercury transformations in reduced, anoxic environments--sediments and waters--are also a key problem for the understanding of the environmental methylation. The studies that have been carried out in the Amazonian environment are too restricted and results permit only circumstantial conclusions. Large efforts must be directed to monitoring programs considering time and space variability.

  18. Messenger Observations of Mercury's Bow Shock and Magnetopause

    NASA Technical Reports Server (NTRS)

    Slavin J. A.; Acuna, M. H.; Anderson, B. J.; Benna, M.; Gloeckler, G.; Krimigis, S. M.; Raines, M.; Schriver, D.; Travnicek, P.; Zurbuchen, T. H.

    2008-01-01

    The MESSENGER spacecraft made the first of three flybys of Mercury on January 14.2008 (1). New observations of solar wind interaction with Mercury were made with MESSENGER'S Magnetometer (MAG) (2.3) and Energetic Particle and Plasma Spectrometer (EPPS) - composed of the Energetic Particle Spectrometer (EPS) and Fast Imaging Plasma Spectrometer (FIPS) (3,4). These MESSENGER observations show that Mercury's magnetosphere has a large-scale structure that is distinctly Earth-like, but it is immersed in a comet-like cloud of planetary ions [5]. Fig. 1 provides a schematic view of the coupled solar wind - magnetosphere - neutral atmosphere - solid planet system at Mercury.

  19. Distribution of a model bioactive within solid lipid nanoparticles and nanostructured lipid carriers influences its loading efficiency and oxidative stability.

    PubMed

    Pan, Yuanjie; Tikekar, Rohan V; Nitin, N

    2016-09-10

    The overall goal of this study was to characterize the distribution of a model bioactive encapsulant in the lipid domain of SLNs and NLCs and its relationship with loading efficiency and reactivity of the model encapsulant with oxidative stress agents. Distribution of a model bioactive (beta-carotene) was compared to that of a fluorescent dye (Nile red) in SLNs, 10% NLC, 30% NLC, 50% NLC, 70% NLC (the number represents the percentage of liquid lipid within the total lipid amount) and emulsions. Fluorescence imaging shows that the distribution of Nile red in the lipid domain of colloidal carriers was similar to that of beta-carotene in all formulations. Based on the combination of imaging observations and loading efficiency measurements, the results demonstrate that beta-carotene was excluded from the lipid domain in both SLNs and NLCs. The extent of exclusion decreased, while uniformity in the distribution of encapsulant in the lipid domain of colloidal carrier increased with an increase in percentage of liquid lipid content of NLCs. Oxidative stability of the encapsulated beta-carotene in SLN and NLCs (at least until 30% liquid lipid composition) was significantly lower compared to that in emulsion. Only for the NLCs with 50 and 70% liquid lipid content, oxidative stability of the encapsulated compound was significantly higher than that in emulsions. Overall, the results demonstrate that differences in loading efficiency and oxidative stability of beta-carotene in SLNs and NLCs may be explained by the differences in the distribution of beta-carotene. PMID:27418566

  20. Formation of Soluble Mercury Oxide Coatings: Transformation of Elemental Mercury in Soils.

    PubMed

    Miller, Carrie L; Watson, David B; Lester, Brian P; Howe, Jane Y; Phillips, Debra H; He, Feng; Liang, Liyuan; Pierce, Eric M

    2015-10-20

    The impact of mercury (Hg) on human and ecological health has been known for decades. Although a treaty signed in 2013 by 147 nations regulates future large-scale mercury emissions, legacy Hg contamination exists worldwide and small-scale releases will continue. The fate of elemental mercury, Hg(0), lost to the subsurface and its potential chemical transformation that can lead to changes in speciation and mobility are poorly understood. Here, we show that Hg(0) beads interact with soil or manganese oxide solids and X-ray spectroscopic analysis indicates that the soluble mercury coatings are HgO. Dissolution studies show that, after reacting with a composite soil, >20 times more Hg is released into water from the coated beads than from a pure liquid mercury bead. An even larger, >700 times, release occurs from coated Hg(0) beads that have been reacted with manganese oxide, suggesting that manganese oxides are involved in the transformation of the Hg(0) beads and creation of the soluble mercury coatings. Although the coatings may inhibit Hg(0) evaporation, the high solubility of the coatings can enhance Hg(II) migration away from the Hg(0)-spill site and result in potential changes in mercury speciation in the soil and increased mercury mobility.

  1. Formation of Soluble Mercury Oxide Coatings: Transformation of Elemental Mercury in Soils.

    PubMed

    Miller, Carrie L; Watson, David B; Lester, Brian P; Howe, Jane Y; Phillips, Debra H; He, Feng; Liang, Liyuan; Pierce, Eric M

    2015-10-20

    The impact of mercury (Hg) on human and ecological health has been known for decades. Although a treaty signed in 2013 by 147 nations regulates future large-scale mercury emissions, legacy Hg contamination exists worldwide and small-scale releases will continue. The fate of elemental mercury, Hg(0), lost to the subsurface and its potential chemical transformation that can lead to changes in speciation and mobility are poorly understood. Here, we show that Hg(0) beads interact with soil or manganese oxide solids and X-ray spectroscopic analysis indicates that the soluble mercury coatings are HgO. Dissolution studies show that, after reacting with a composite soil, >20 times more Hg is released into water from the coated beads than from a pure liquid mercury bead. An even larger, >700 times, release occurs from coated Hg(0) beads that have been reacted with manganese oxide, suggesting that manganese oxides are involved in the transformation of the Hg(0) beads and creation of the soluble mercury coatings. Although the coatings may inhibit Hg(0) evaporation, the high solubility of the coatings can enhance Hg(II) migration away from the Hg(0)-spill site and result in potential changes in mercury speciation in the soil and increased mercury mobility. PMID:26389816

  2. Formation of soluble mercury oxide coatings: Transformation of elemental mercury in soils

    SciTech Connect

    Miller, Carrie L.; Watson, David B.; Lester, Brian P.; Howe, Jane Y.; Phillips, Debra H.; He, Feng; Liang, Liyuan; Pierce, Eric M.

    2015-09-21

    In this study, the impact of mercury (Hg) on human and ecological health has been known for decades. Although a treaty signed in 2013 by 147 nations regulates future large-scale mercury emissions, legacy Hg contamination exists worldwide and small-scale releases will continue. The fate of elemental mercury, Hg(0), lost to the subsurface and its potential chemical transformation that can lead to changes in speciation and mobility are poorly understood. Here, we show that Hg(0) beads interact with soil or manganese oxide solids and X-ray spectroscopic analysis indicates that the soluble mercury coatings are HgO. Dissolution studies show that, after reacting with a composite soil, >20 times more Hg is released into water from the coated beads than from a pure liquid mercury bead. An even larger, >700 times, release occurs from coated Hg(0) beads that have been reacted with manganese oxide, suggesting that manganese oxides are involved in the transformation of the Hg(0) beads and creation of the soluble mercury coatings. Although the coatings may inhibit Hg(0) evaporation, the high solubility of the coatings can enhance Hg(II) migration away from the Hg(0)-spill site and result in potential changes in mercury speciation in the soil and increased mercury mobility.

  3. Formation of soluble mercury oxide coatings: Transformation of elemental mercury in soils

    DOE PAGES

    Miller, Carrie L.; Watson, David B.; Lester, Brian P.; Howe, Jane Y.; Phillips, Debra H.; He, Feng; Liang, Liyuan; Pierce, Eric M.

    2015-09-21

    In this study, the impact of mercury (Hg) on human and ecological health has been known for decades. Although a treaty signed in 2013 by 147 nations regulates future large-scale mercury emissions, legacy Hg contamination exists worldwide and small-scale releases will continue. The fate of elemental mercury, Hg(0), lost to the subsurface and its potential chemical transformation that can lead to changes in speciation and mobility are poorly understood. Here, we show that Hg(0) beads interact with soil or manganese oxide solids and X-ray spectroscopic analysis indicates that the soluble mercury coatings are HgO. Dissolution studies show that, after reactingmore » with a composite soil, >20 times more Hg is released into water from the coated beads than from a pure liquid mercury bead. An even larger, >700 times, release occurs from coated Hg(0) beads that have been reacted with manganese oxide, suggesting that manganese oxides are involved in the transformation of the Hg(0) beads and creation of the soluble mercury coatings. Although the coatings may inhibit Hg(0) evaporation, the high solubility of the coatings can enhance Hg(II) migration away from the Hg(0)-spill site and result in potential changes in mercury speciation in the soil and increased mercury mobility.« less

  4. 9. BUILDING NO. 235, ORDNANCE FACILITY (MERCURY FULMINATE MIXING), LOOKING ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    9. BUILDING NO. 235, ORDNANCE FACILITY (MERCURY FULMINATE MIXING), LOOKING SOUTHEAST BETWEEN BUILDING AND BLAST BARRICADES. - Picatinny Arsenal, 200 Area, Shell Component Loading, State Route 15 near I-80, Dover, Morris County, NJ

  5. Mercury and halogens in coal--Their role in determining mercury emissions from coal combustion

    USGS Publications Warehouse

    Kolker, Allan; Quick, Jeffrey C.; Senior, Connie L.; Belkin, Harvey E.

    2012-01-01

    Mercury is a toxic pollutant. In its elemental form, gaseous mercury has a long residence time in the atmosphere, up to a year, allowing it to be transported long distances from emission sources. Mercury can be emitted from natural sources such as volcanoes, or from anthropogenic sources, such as coal-fired powerplants. In addition, all sources of mercury on the Earth's surface can re-emit it from land and sea back to the atmosphere, from which it is then redeposited. Mercury in the atmosphere is present in such low concentrations that it is not considered harmful. Once mercury enters the aquatic environment, however, it can undergo a series of biochemical transformations that convert a portion of the mercury originally present to methylmercury, a highly toxic organic form of mercury that accumulates in fish and birds. Many factors contribute to creation of methylmercury in aquatic ecosystems, including mercury availability, sediment and nutrient load, bacterial influence, and chemical conditions. In the United States, consumption of fish with high levels of methylmercury is the most common pathway for human exposure to mercury, leading the U.S. Environmental Protection Agency (EPA) to issue fish consumption advisories in every State. The EPA estimates that 50 percent of the mercury entering the atmosphere in the United States is emitted from coal-burning utility powerplants. An EPA rule, known as MATS (for Mercury and Air Toxics Standards), to reduce emissions of mercury and other toxic pollutants from powerplants, was signed in December 2011. The rule, which is currently under review, specifies limits for mercury and other toxic elements, such as arsenic, chromium, and nickel. MATS also places limits on emission of harmful acid gases, such as hydrochloric acid and hydrofluoric acid. These standards are the result of a 2010 detailed nationwide program by the EPA to sample stack emissions and thousands of shipments of coal to coal-burning powerplants. The United

  6. Multi-scale strategy to eradicate Pseudomonas aeruginosa on surfaces using solid lipid nanoparticles loaded with free fatty acids.

    PubMed

    Taylor, Erik N; Kummer, Kim M; Dyondi, Deepti; Webster, Thomas J; Banerjee, Rinti

    2014-01-21

    Infections are both frequent and costly in hospitals around the world, leading to longer hospital stays, overuse of antibiotics, and excessive costs to the healthcare system. Moreover, antibiotic resistant organisms, such as Pseudomonas aeruginosa are increasing in frequency, leading to 1.7 million infections per year in USA hospitals, and 99,000 deaths, both due to the evolution of antibiotic resistance and the formation of biofilms on medical devices. In particular, respiratory infections are costly, deadly to 4.5 million persons per year worldwide, and can spread to the lungs through the placement of endotracheal tubing. In this study, towards a reduction in infections, solid lipid nanoparticles were formulated from free fatty acids, or natural lipophilic constituents found in tissues of the body. A strategy was developed to target infections by producing coatings made of non-toxic chemistries lauric acid and oleic acid delivered by core-shell solid lipid nanoparticles that act against bacteria by multiple mechanisms at the nanoscale, including disruption of bacteria leading to DNA release, and reducing the adhesion of dead bacteria to ~1%. This is the first such study to explore an anti-infection surface relying on these multi-tier strategies at the nanoscale.

  7. Multi-scale strategy to eradicate Pseudomonas aeruginosa on surfaces using solid lipid nanoparticles loaded with free fatty acids

    NASA Astrophysics Data System (ADS)

    Taylor, Erik N.; Kummer, Kim M.; Dyondi, Deepti; Webster, Thomas J.; Banerjee, Rinti

    2013-12-01

    Infections are both frequent and costly in hospitals around the world, leading to longer hospital stays, overuse of antibiotics, and excessive costs to the healthcare system. Moreover, antibiotic resistant organisms, such as Pseudomonas aeruginosa are increasing in frequency, leading to 1.7 million infections per year in USA hospitals, and 99 000 deaths, both due to the evolution of antibiotic resistance and the formation of biofilms on medical devices. In particular, respiratory infections are costly, deadly to 4.5 million persons per year worldwide, and can spread to the lungs through the placement of endotracheal tubing. In this study, towards a reduction in infections, solid lipid nanoparticles were formulated from free fatty acids, or natural lipophilic constituents found in tissues of the body. A strategy was developed to target infections by producing coatings made of non-toxic chemistries lauric acid and oleic acid delivered by core-shell solid lipid nanoparticles that act against bacteria by multiple mechanisms at the nanoscale, including disruption of bacteria leading to DNA release, and reducing the adhesion of dead bacteria to ~1%. This is the first such study to explore an anti-infection surface relying on these multi-tier strategies at the nanoscale.

  8. Effect of load, area of contact, and contact stress on the wear mechanisms of a bonded solid lubricant film

    NASA Technical Reports Server (NTRS)

    Fusaro, R. L.

    1980-01-01

    A pin on disk type of friction and wear apparatus was used to study the effect of load, contact stress and rider area of contact on the friction and wear properties of polyimide bonded graphite fluoride films. Different rider area contacts were obtained by initially generating flats (with areas of 0.0035, 0.0071, 0.0145, and 0.0240 cm) on 0.476-cm radius hemispherically tipped riders. Different projected contact stresses were obtained by applying loads of 2.5- to 58.8-N to the flats. Two film wear mechanisms were observed. The first was found to be a linear function of contact stress and was independent of rider area of contact. The second was found to increase exponentially as the stress increased. The second also appeared to be a function of rider contact area. Wear equations for each mechanism were empirically derived from the experimental data. In general, friction coefficients increased with increasing rider contact area and with sliding duration. This was related to the build up of thick rider transfer films.

  9. Evaluation of Incoherent Interface Strength of Solid-State-Bonded Ti64/Stainless Steel Under Dynamic Impact Loading

    NASA Astrophysics Data System (ADS)

    Verma, Devendra; Singh, Jogender; Varma, Amit H.; Tomar, Vikas

    2015-08-01

    Ti/steel interfaces are produced using field-assisted sintering technology, a technique known to bring about full consolidation of materials using much lower sintering temperatures and durations. The interface thickness is verified using the energy-dispersive x-ray analysis exhibiting the extent of diffusion in interface regions. The interface mechanical strength is characterized using dynamic indentation experiments at strain rates approaching 400 s-1. The experiments were conducted on the interfaces within the spatial error tolerance of less than 3 µm. The measurements of dynamic hardness values, strain rates, and plastic-residual depths were correlated to show the relation of interface mechanical strength with the bulk-phase mechanical strength properties of Ti and steel. The Johnson-Cook model is fitted to the obtained interface normal stress-normal strain data based on the nanoimpact experiments. The coefficient of restitution in the mechanical loading and its dependence on the interface dynamic hardness and interface impact velocity validate the experimental results. The results show that interfacial properties are affected by the rate of loading and are largely dependent upon the interface structural inhomogeneity.

  10. The effect of hydrogen peroxide concentration and solid loading on the fractionation of biomass in formic acid.

    PubMed

    Dussan, K; Girisuta, B; Haverty, D; Leahy, J J; Hayes, M H B

    2014-10-13

    This study investigated the fractionation of biomass using a decomposing mixture of hydrogen peroxide-formic acid as a pretreatment for the biorefining of Miscanthus × giganteus and of sugarcane bagasse. The main parameters investigated were the hydrogen peroxide concentration (2.5, 5.0 and 7.5 wt%) and biomass loading (5.0 and 10.0 wt%). At the highest hydrogen peroxide concentration used (7.5 wt%), the energy released by the decomposition of the H2O2 could heat the reaction mixture up to 180 °C in a short time (6-16 min). As a result, highly delignified pulps, with lignin removal as high as 92 wt%, were obtained. This delignification process also solubilised a significant amount of pentosan (82-98 wt%) from the initial biomass feedstock, and the resulting pulp had a high cellulosic content (92 wt%). The biomass loading only affected the reaction rate of hydrogen peroxide decomposition. Various analytical methods, including Fourier transform infrared spectroscopy, and thermogravimetric and elemental analyses, characterized the lignin obtained.

  11. Influences on mercury bioaccumulation factors for the Savannah River.

    PubMed

    Paller, M H; Bowers, J A; Littrell, J W; Guanlao, A V

    2004-02-01

    Mercury TMDLs (Total Maximum Daily Loads) are a regulatory instrument designed to reduce the amount of mercury entering a water body and ultimately to control the bioaccumulation of mercury in fish. TMDLs are based on a BAF (bioaccumulation factor), which is the ratio of methyl mercury in fish to dissolved methyl mercury in water. Analysis of fish tissue and aqueous methyl mercury samples collected at a number of locations and over several seasons in a 118-km reach of the Savannah River demonstrated that species-specific BAFs varied by factors of three to eight. Factors contributing to BAF variability were location, habitat, and season-related differences in fish muscle tissue mercury levels and seasonal differences in dissolved methyl mercury levels. Overall (all locations, habitats, and seasons) average BAFs were 3.7 x 10(6) for largemouth bass, 1.4 x 10(6) for sunfishes, and 2.5 X 10(6) for white catfish. Determination of representative BAFs for mercury in fish from large rivers necessitates collecting large and approximately equal numbers of fish and aqueous methyl mercury samples over a seasonal cycle from the entire area and all habitats to be represented by the TMDL.

  12. Search for Na+ Pickup Ion Generated Waves at Mercury

    NASA Astrophysics Data System (ADS)

    Boardsen, S. A.; Slavin, J. A.

    2007-05-01

    Telescopic observations by Potter et al. [2002] have discovered that Mercury's Sodium exosphere has a tail extending 10's of Mercury radii. Theory predicts that the shape of and the amount of Sodium [Smyth, 1986, 1995; Ip 1986, 1990] in this exospheric tail is highly dependent upon the true anomaly of Mercury. The exospheric Na that is not reabsorbed on Mercury's surface will be photo-ionized. Computations by Ip [1986] indicated that ionized exospheric Na could significantly mass load the plasma population in Mercury's magnetosphere. These freshly created ions will be rapidly energized by the convection electric field in Mercury's magnetosphere and sheath and should be highly unstable to the generation of plasma waves. These waves could play an important role in the thermalization and retention of the Na+. Because the gyro radii of Na+ can be comparable to the scale sizes in Mercury's geospace there is an open question whether Mercury's geospace can sustain such waves. After a brief review of what was observed in the Mariner 10 magnetometer data, we will present analytic calculations of the expected pickup ion distributions, the expected unstable waves, their frequencies, wavelengths and Doppler shifts, their variation with location in Mercury's geospace and Mercury's true anomaly for both high and low solar wind convection electric fields. We will assess if and when such waves can be generated and sustained.

  13. Global Trends in Mercury Management

    PubMed Central

    Choi, Kyunghee

    2012-01-01

    The United Nations Environmental Program Governing Council has regulated mercury as a global pollutant since 2001 and has been preparing the mercury convention, which will have a strongly binding force through Global Mercury Assessment, Global Mercury Partnership Activities, and establishment of the Open-Ended Working Group on Mercury. The European Union maintains an inclusive strategy on risks and contamination of mercury, and has executed the Mercury Export Ban Act since December in 2010. The US Environmental Protection Agency established the Mercury Action Plan (1998) and the Mercury Roadmap (2006) and has proposed systematic mercury management methods to reduce the health risks posed by mercury exposure. Japan, which experienced Minamata disease, aims vigorously at perfection in mercury management in several ways. In Korea, the Ministry of Environment established the Comprehensive Plan and Countermeasures for Mercury Management to prepare for the mercury convention and to reduce risks of mercury to protect public health. PMID:23230466

  14. Global trends in mercury management.

    PubMed

    Kim, Dae-Seon; Choi, Kyunghee

    2012-11-01

    The United Nations Environmental Program Governing Council has regulated mercury as a global pollutant since 2001 and has been preparing the mercury convention, which will have a strongly binding force through Global Mercury Assessment, Global Mercury Partnership Activities, and establishment of the Open-Ended Working Group on Mercury. The European Union maintains an inclusive strategy on risks and contamination of mercury, and has executed the Mercury Export Ban Act since December in 2010. The US Environmental Protection Agency established the Mercury Action Plan (1998) and the Mercury Roadmap (2006) and has proposed systematic mercury management methods to reduce the health risks posed by mercury exposure. Japan, which experienced Minamata disease, aims vigorously at perfection in mercury management in several ways. In Korea, the Ministry of Environment established the Comprehensive Plan and Countermeasures for Mercury Management to prepare for the mercury convention and to reduce risks of mercury to protect public health. PMID:23230466

  15. Evaluation of a sequential extraction process used for determining mercury binding mechanisms to coal combustion byproducts.

    PubMed

    Noel, James D; Biswas, Pratim; Giammar, Daniel E

    2007-07-01

    Leaching of mercury from coal combustion byproducts is a concern because of the toxicity of mercury. Leachability of mercury can be assessed by using sequential extraction procedures. Sequential extraction procedures are commonly used to determine the speciation and mobility of trace metals in solid samples and are designed to differentiate among metals bound by different mechanisms and to different solid phases. This study evaluated the selectivity and effectiveness of a sequential extraction process used to determine mercury binding mechanisms to various materials. A six-step sequential extraction process was applied to laboratory-synthesized materials with known mercury concentrations and binding mechanisms. These materials were calcite, hematite, goethite, and titanium dioxide. Fly ash from a full-scale power plant was also investigated. The concentrations of mercury were measured using inductively coupled plasma (ICP) mass spectrometry, whereas the major elements were measured by ICP atomic emission spectrometry. The materials were characterized by X-ray powder diffraction and scanning electron microscopy with energy dispersive spectroscopy. The sequential extraction procedure provided information about the solid phases with which mercury was associated in the solid sample. The procedure effectively extracted mercury from the target phases. The procedure was generally selective in extracting mercury. However, some steps in the procedure extracted mercury from nontarget phases, and others resulted in mercury redistribution. Iron from hematite and goethite was only leached in the reducible and residual extraction steps. Some mercury associated with goethite was extracted in the ion exchangeable step, whereas mercury associated with hematite was extracted almost entirely in the residual step. Calcium in calcite and mercury associated with calcite were primarily removed in the acid-soluble extraction step. Titanium in titanium dioxide and mercury adsorbed onto

  16. New Jersey mercury regulations

    SciTech Connect

    Elias, D.F.; Corbin, W.E.

    1996-12-31

    Mercury, or quicksilver, and its major ore cinnabar (HgS) have been known for thousands of years. Health effects from mercury such as dementia were known as early as the late 19th century ({open_quotes}mad as a hatter{close_quotes}). In the 1960`s and 1970`s, reported levels of mercury in tuna reawakened public awareness of mercury pollution. In the 1970`s, major epidemics of acute mercury poisoning were reported in Japan and Iraq. These incidents highlighted the extreme health risks, such as kidney damage, birth defects, and death, associated with severe mercury poisoning. Fetuses and young children are particularly vulnerable since mercury poisoning can damage growing neural tissues. Recently, the perception of mercury as a dangerous pollutant has been on the rise. Advisories warning the public to avoid or reduce the consumption of freshwater fish caught in specific waterbodies due to mercury contamination have been issued in numerous states. The discovery of mercury in {open_quotes}pristine{close_quotes} lakes in the United States, Canada, and Scandinavia, remote from industry and any known mercury sources, has focused attention on atmospheric emissions of mercury as potential significant sources of mercury.

  17. Gas chromatographic determination of polycyclic aromatic hydrocarbons in water and smoked rice samples after solid-phase microextraction using multiwalled carbon nanotube loaded hollow fiber.

    PubMed

    Matin, Amir Abbas; Biparva, Pourya; Gheshlaghi, Mohammad

    2014-12-29

    A novel solid-phase microextraction fiber was prepared based on multiwalled carbon nanotubes (MWCNTs) loaded on hollow fiber membrane pores. Stainless steel wire was used as unbreakable support. The major advantages of the proposed fiber are its (a) high reproducibility due to the uniform structure of the hollow fiber membranes, (b) high extraction capacity related to the porous structure of the hollow fiber and outstanding adsorptive characteristics of MWCNTs. The proposed fiber was applied for the microextraction of five representative polycyclic aromatic hydrocarbons (PAHs) from aqueous media (river and hubble-bubble water) and smoked rice samples followed by gas chromatographic determination. Analytical merits of the method, including high correlation coefficients [(0.9963-0.9992) and (0.9982-0.9999)] and low detection limits [(9.0-13.0ngL(-1)) and (40.0-150.0ngkg(-1))] for water and rice samples, respectively, made the proposed method suitable for the ultra-trace determination of PAHs.

  18. Atmospheric Deposition and Fate of Mercury in High-altitude Watersheds of the Rocky Mountains.

    NASA Astrophysics Data System (ADS)

    Campbell, D. H.; Mast, M. A.; Ingersoll, G. P.; Manthorne, D. J.; Krabbenhoft, D. P.; Taylor, H. E.; Aiken, G. R.; Schuster, P. F.; Reddy, M. M.

    2003-12-01

    Despite the potential for cold high-altitude ecosystems to act as sinks in the global mercury cycle, atmospheric deposition and fate of mercury have not been measured extensively at mountain sites in the Western United States. At Buffalo Pass in northwestern Colorado (the highest site in the national Mercury Deposition Network at 3234 m elevation), mercury in wet deposition was 9 μ gm-2 in 2000, comparable to many sites in the upper Midwestern United States where fish consumption advisories are widespread because of elevated levels of mercury from atmospheric deposition. Similar levels of mercury deposition were measured about 90 km east of Buffalo Pass at Loch Vale in Rocky Mountain National Park (RMNP) during 2002. Concentrations of total mercury in headwater streams in RMNP averaged 2-4 ngL-1 during spring and summer of 2001-2002. Higher concentrations were observed during snowmelt and rainfall events. Dissolved mercury was generally greater than particulate mercury in these clear mountain streams. Mercury and dissolved organic carbon peaked as soils were flushed during early snowmelt and rainy summer periods. Overall, mercury deposition was greater than mercury export, indicating accumulation in alpine/subalpine ecosystems; however, the mercury exported in streamflow may contribute substantially to mercury loading in downstream lakes and reservoirs where fish consumption advisories have increased. Methyl mercury concentrations measured in the streams in 2002 were generally near or less than detection limits, however, extreme drought conditions limited hydrologic flushing of soils and wetlands that may be sources of methyl mercury. In 2003, surface and ground water from various alpine and subalpine landscapes were sampled to determine sources and transport of total and methyl mercury. The elevated levels of mercury in atmospheric deposition indicate a need for better understanding of mercury cycling and transport in high-altitude ecosystems of Western North

  19. Sustained release of isoniazid from polylactide microspheres prepared using solid/oil drug loading method for tuberculosis treatment.

    PubMed

    Zhang, Limei; Li, Ying; Zhang, Yun; Zhu, Chunyan

    2016-07-01

    Polylactide (PLA) microspheres were prepared using the solid-in-oil (S/O) spray-drying method to achieve the sustained release of a hydrophilic drug for the treatment of tuberculosis, via intratracheal instillation. Isoniazid (IN), a low-molecular-weight hydrophilic drug, was used as a model drug. The effects of various sizes of micronized IN powder, different drug/polymer ratios, spray-drying process parameters, and drug-release characteristics were studied to optimize the manufacturing parameters. A high entrapment efficiency (87.3%) was obtained using this method; furthermore, the microspheres were spherical and smooth. They were individually and homogenously distributed, with a mean diameter of 5.6 μm; furthermore, they showed a satisfactory extended sustained-release phase. After administration of the microspheres to rats, pulmonary drug concentrations were maintained at a relatively stable level for up to 4 weeks. PMID:27278371

  20. The tail feathers of osprey nestlings (Pandion haliaetus L.) as indicators of change in mercury load in the environment of southern Sweden (1969-1998): a case study with a note on the simultaneous intake of selenium.

    PubMed

    Odsjö, Tjelvar; Roos, Anna; Johnels, Alf G

    2004-05-01

    The tail feathers of 104 osprey nestlings (Pandion haliaetus) from Lake Asnen, southern Sweden, were analyzed for total mercury and selenium content. Concentrations of mercury in feathers from the western part of the lake fell during the period 1969-1998, when pollution from industrial mercury had decreased and a paper mill upstream of the lake was closed down in 1979. Nestlings from the eastern part of the lake had initially lower levels of mercury, predominantly from atmospheric fallout. The levels did not decrease during the period. The reason for the differences seems to be the limited water flow between the western and the eastern part of the lake. The selenium concentrations were constant over time and approximately the same in both parts of the lake. The total-Hg/Se ratio in the western part of the lake was 2.94, which is somewhat higher than the 1:1 molar ratio constant (2.54). This indicates that the bioaccumulated quantity of selenium which is thought to be protective for the organisms against the toxic effects of mercury, is somewhat insufficient to bind all body mercury. PMID:15151382

  1. Mechanisms of mercury bioremediation.

    PubMed

    Essa, A M M; Macaskie, L E; Brown, N L

    2002-08-01

    Mercury is one of the most toxic heavy metals, and has significant industrial and agricultural uses. These uses have led to severe localized mercury pollution. Mercury volatilization after its reduction to the metallic form by mercury-resistant bacteria has been reported as a mechanism for mercury bioremediation [Brunke, Deckwer, Frischmuth, Horn, Lunsdorf, Rhode, Rohricht, Timmis and Weppen (1993) FEMS Microbiol. Rev. 11, 145-152; von Canstein, Timmis, Deckwer and Wagner-Dobler (1999) Appl. Environ. Microbiol. 65, 5279-5284]. The reduction/volatilization system requires to be studied further, in order to eliminate the escape of the metallic mercury into the environment. Recently we have demonstrated three different mechanisms for mercury detoxification in one organism, Klebsiella pneumoniae M426, which may increase the capture efficiency of mercury.

  2. Mercury and Venus: Observing by Amateurs

    NASA Astrophysics Data System (ADS)

    Steele, R.; Murdin, P.

    2003-04-01

    MERCURY presents a solid surface at low resolution, while VENUS offers only a visually opaque but dynamic upper atmospheric layer for inspection. Past amateur study is largely the story of visual techniques applied with moderate instrumentation in order to build up a pictorial and descriptive record, but now amateurs use sophisticated techniques to monitor a broader spectral range and there is sco...

  3. Propagated fixed-bed mixed-acid fermentation: Part I: Effect of volatile solid loading rate and agitation at high pH.

    PubMed

    Golub, Kristina W; Forrest, Andrea K; Mercy, Kevin L; Holtzapple, Mark T

    2011-11-01

    Countercurrent fermentation is a high performing process design for mixed-acid fermentation. However, there are high operating costs associated with moving solids, which is an integral component of this configuration. This study investigated the effect of volatile solid loading rate (VSLR) and agitation in propagated fixed-bed fermentation, a configuration which may be more commercially viable. To evaluate the role of agitation on fixed-bed configuration performance, continuous mixing was compared with periodic mixing. VSLR was also varied and not found to affect acid yields. However, increased VSLR and liquid retention time did result in higher conversions, productivity, acid concentrations, but lower selectivities. Agitation was demonstrated to be important for this fermentor configuration, the periodically-mixed fermentation had the lowest conversion and yields. Operating at a high pH (∼9) contributed to the high selectivity to acetic acid, which might be industrially desirable but at the cost of lower yield compared to a neutral pH. PMID:21963249

  4. Suspended-sediment concentrations, loads, total suspended solids, turbidity, and particle-size fractions for selected rivers in Minnesota, 2007 through 2011

    USGS Publications Warehouse

    Ellison, Christopher A.; Savage, Brett E.; Johnson, Gregory D.

    2014-01-01

    Sediment-laden rivers and streams pose substantial environmental and economic challenges. Excessive sediment transport in rivers causes problems for flood control, soil conservation, irrigation, aquatic health, and navigation, and transports harmful contaminants like organic chemicals and eutrophication-causing nutrients. In Minnesota, more than 5,800 miles of streams are identified as impaired by the Minnesota Pollution Control Agency (MPCA) due to elevated levels of suspended sediment. The U.S. Geological Survey, in cooperation with the MPCA, established a sediment monitoring network in 2007 and began systematic sampling of suspended-sediment concentrations (SSC), total suspended solids (TSS), and turbidity in rivers across Minnesota to improve the understanding of fluvial sediment transport relations. Suspended-sediment samples collected from 14 sites from 2007 through 2011 indicated that the Zumbro River at Kellogg in the driftless region of southeast Minnesota had the highest mean SSC of 226 milligrams per liter (mg/L) followed by the Minnesota River at Mankato with a mean SSC of 193 mg/L. During the 2011 spring runoff, the single highest SSC of 1,250 mg/L was measured at the Zumbro River. The lowest mean SSC of 21 mg/L was measured at Rice Creek in the northern Minneapolis- St. Paul metropolitan area. Total suspended solids (TSS) have been used as a measure of fluvial sediment by the MPCA since the early 1970s; however, TSS concentrations have been determined to underrepresent the amount of suspended sediment. Because of this, the MPCA was interested in quantifying the differences between SSC and TSS in different parts of the State. Comparisons between concurrently sampled SSC and TSS indicated significant differences at every site, with SSC on average two times larger than TSS concentrations. The largest percent difference between SSC and TSS was measured at the South Branch Buffalo River at Sabin, and the smallest difference was observed at the Des Moines

  5. Extraction and precipitation chemistry for mercury recovery from aqueous wastes

    SciTech Connect

    Fulbright, H.H.; Leaphart, M.; Van Brunt, V.

    1997-01-01

    This paper describes an extraction-precipitation process to recover mercuric chloride from aqueous solutions. The process is a modification of a dicarboxylic acid recovery process that exploits the enhanced solubility of mercuric chloride in organic solvents loaded with water. Mercuric chloride in ethyl acetate has a solubility enhancement of 1.34 moles mercuric chloride per mole of water added to the solvent, consistent with previously reported phase behavior. Solubility enhancement is also reported for formates, in contrast to previously reported results. For example, propyl formate showed 2.91 moles mercuric chloride per mole water enhancement. The modified process described in this paper relies on (1) favorable liquid-liquid equilibrium (mercuric chloride distribution into ethyl acetate or into propyl formate), (2) favorable liquid-solid equilibrium with enhanced solute solubility on addition of a minor constituent (water), and (3) preferential vaporization of the minor constituent from the solid slurry (relative volatility of water in mercuric chloride loaded ethyl acetate is four). Enhanced solubilities for zinc(II) chloride(3.46) and mercury(II) iodide(1.10) in isopentyl acetate indicate a potential application of the process for the recovery of other metal halides from aqueous wastes.

  6. Comparison of SW-846 method 3051 and SW-846 method 7471A for the preparation of solid waste samples for mercury determination

    SciTech Connect

    Giaquinto, J.M.; Essling, A.M.; Keller, J.M.

    1996-08-01

    This report describes experimental studies to evaluate the use of EPA SW-846 method 3051 for preparation and dissolution of solid samples for Hg analysis. The study showed that the method is effective in dissolution of four sample types without significant loss of Hg. Based on results of this study, method 3051 was used for analysis of high radioactive waste samples to obtain results for a number of RCRA regulated metals without the need to utilize a separate sample preparation method (EPA SW-846 method 7471A) specific only for Hg.

  7. Evolved strains of Scheffersomyces stipitis achieving high ethanol productivity on acid- and base-pretreated biomass hydrolyzate at high solids loading

    SciTech Connect

    Slininger, Patricia J.; Shea-Andersh, Maureen A.; Thompson, Stephanie R.; Dien, Bruce S.; Kurtzman, Cletus P.; Balan, Venkatesh; da Costa Sousa, Leonardo; Uppugundla, Nirmal; Dale, Bruce E; Cotta, Michael A

    2015-04-09

    Lignocellulosic biomass is an abundant, renewable feedstock useful for the production of fuel-grade ethanol via the processing steps of pretreatment, enzyme hydrolysis, and microbial fermentation. Traditional industrial yeasts do not ferment xylose and are not able to grow, survive, or ferment in concentrated hydrolyzates that contain enough sugar to support economical ethanol recovery since they are laden with toxic byproducts generated during pretreatment. Repetitive culturing in two types of concentrated hydrolyzates was applied along with ethanol challenged xylose-fed continuous culture to force targeted evolution of the native pentose fermenting yeast Scheffersomyces (Pichia) stipitis strain NRRL Y-7124 maintained in the ARS Culture Collection, Peoria, IL. Isolates collected from various enriched populations were screened and ranked based on relative xylose uptake rate and ethanol yield. Ranking on hydrolyzates with and without nutritional supplementation was used to identify those isolates with best performance across diverse conditions. Robust S. stipitis strains adapted to perform very well in enzyme hydrolyzates of high solids loading ammonia fiber expansion-pretreated corn stover (18% weight per volume solids) and dilute sulfuric acid-pretreated switchgrass (20% w/v solids) were obtained. Improved features include reduced initial lag phase preceding growth, significantly enhanced fermentation rates, improved ethanol tolerance and yield, reduced diauxic lag during glucose-xylose transition, and ability to accumulate >40 g/L ethanol in <167 h when fermenting hydrolyzate at low initial cell density of 0.5 absorbance units and pH 5 to 6.

  8. Doxorubicin-loaded poly(lactic-co-glycolic acid) microspheres prepared using the solid-in-oil-in-water method for the transarterial chemoembolization of a liver tumor.

    PubMed

    Choi, Jin Woo; Park, Ju-Hwan; Baek, Song Yi; Kim, Dae-Duk; Kim, Hyo-Cheol; Cho, Hyun-Jong

    2015-08-01

    Doxorubicin (DOX)-loaded poly(lactic-co-glycolic acid) (PLGA) microspheres (MSs) were fabricated using the solid-in-oil-in-water (S/O/W) emulsification method for transarterial chemoembolization (TACE) of a liver tumor. DOX-loaded PLGA MSs with a mean diameter of 26 μm and a spherical shape were prepared. The biodegradation of PLGA MSs was observed in serum using a scanning electron microscope (SEM). Drug release from the PLGA MSs was accelerated at an acidic pH (pH 5.5) compared to a normal physiological pH (pH 7.4). According to the results of a pharmacokinetic study in rats, the area under the curve (AUC) value of a drug, which indicates the systemic exposure extent of the drug, of the PLGA MSs group was 29.9% of that of a hepatic arterial injection (HAI) group. The DOX concentration ratio for liver tumors compared to normal livers was significantly higher in the PLGA MSs group than that of the HAI group (p<0.05). After the TACE procedure was performed with DOX-PLGA MSs in a rat hepatoma model, the mean size increment of tumor in DOX-PLGA MSs group was found to be lower than that of the HAI group, and the viable portion of the DOX-PLGA MSs group was less than the other groups (p<0.05). All these findings suggested that the developed DOX-loaded PLGA MSs fabricated with the S/O/W method can be used as a promising drug delivery system in TACE for liver tumors.

  9. Dental amalgam and mercury

    SciTech Connect

    Mackert, J.R. Jr. )

    1991-08-01

    This paper looks at the issues of the current amalgam controversy: the daily dose of mercury from amalgam, hypersensitivity to mercury, claims of adverse effects from amalgam mercury and alleged overnight 'cures.' In addition, the toxicity and allergenicity of the proposed alternative materials are examined with the same kind of scrutiny applied by the anti-amalgam group to dental amalgam. 100 references.

  10. Mercury Surveillance Program

    NASA Technical Reports Server (NTRS)

    1993-01-01

    Background on mercury exposure is presented including forms, sources, permissible exposure limits, and physiological effects. The purpose of the Mercury Surveillance Program at LeRC is outlined, and the specifics of the Medical Surveillance Program for Mercury Exposure at LeRC are discussed.

  11. Preservation of solid mercuric dithizonate samples with polyvinyl chloride for determination of mercury(II) in environmental waters by photochromism-induced photoacoustic spectrometry.

    PubMed

    Lai, E P; Wong, B; Vandernoot, V A

    1993-07-01

    A novel sample preparation technique has been developed to preserve solid mercuric dithizonate [Hg(HDz)(2)] in a matrix of polyvinyl chloride (PVC) for analysis by photochromism-induced photoacoustic spectrometry (PCPAS). This technique, which begins with the extraction of Hg(2+) from water with dithizone, allows for the determination of Hg(2+) in environmental samples. Inclusion of Hg(HDz)(2) within the polymer matrix enhances the PCPAS signal amplitude over that from the bare Hg(HDz)(2) film by almost sixfold. The standard calibration graph of PCPAS signal amplitude as a function of Hg(2+) concentration is linear in the concentration range of 5-100 mug/ml. A lower detection limit can be achieved by using a laser of higher power tuned to a wavelength closer to the maximum absorptivity of the excited Hg(HDz)(2) complex. A study, conducted to monitor the change in PCPAS signal amplitude obtained for the same sample over an extended storage period of 19 days, demonstrates that the PVC protects the integrity of the solid Hg(HDz)(2) sample. Hence, it is potentially feasible to collect environmental samples from a remote area for analysis at a later date.

  12. The treatment of solid tumors by alpha emitters released from 224Ra-loaded sources—internal dosimetry analysis

    NASA Astrophysics Data System (ADS)

    Arazi, L.; Cooks, T.; Schmidt, M.; Keisari, Y.; Kelson, I.

    2010-02-01

    Diffusing alpha-emitters radiation therapy (DART) is a proposed new form of brachytherapy, allowing the treatment of solid tumors by alpha particles. DART utilizes implantable sources carrying small activities of radium-224, which continually release into the tumor radon-220, polonium-216 and lead-212 atoms, while radium-224 itself remains fixed to the source. The released atoms disperse inside the tumor by diffusive and convective processes, creating, through their alpha emissions, a high-dose region measuring several mm in diameter about each source. The efficacy of DART has been demonstrated in preclinical studies on mice-borne squamous cell carcinoma and lung tumors and the method is now being developed toward clinical trials. This work studies DART safety with respect to the dose delivered to distant organs as a result of lead-212 leakage from the tumor through the blood, relying on a biokinetic calculation coupled to internal dose assessments. It is found that the dose-limiting organs are the kidneys and red bone marrow. Assuming a typical source spacing of ~5 mm and a typical radium-224 activity density of 0.4-0.8 MBq g-1 of tumor tissue, it is predicted that tumors weighing up to several hundred grams may be treated without reaching the tolerance dose in any organ.

  13. Solid-base loaded WO{sub 3} photocatalyst for decomposition of harmful organics under visible light irradiation

    SciTech Connect

    Kako, Tetsuya; Meng, Xianguang; Ye, Jinhua

    2015-10-01

    Composite of NaBiO{sub 3}-loaded WO{sub 3} with a mixing ratio of 10:100 was prepared for photocatalytic harmful-organic-contaminant decomposition. The composite properties were measured using X-ray diffraction, ultraviolet-visible spectrophotometer (UV-Vis), and valence band-X-ray photoelectron spectroscope (VB-XPS). The results exhibited that the potentials for top of the valence band and bottom of conduction band for NaBiO{sub 3} can be estimated, respectively, as +2.5 V and -0.1 to 0 V. Furthermore, WO{sub 3}, NaBiO{sub 3}, and the composite showed IPA oxidation properties under visible-light irradiation. Results show that the composite exhibited much higher photocatalytic activity about 2-propanol (IPA) decomposition into CO{sub 2} than individual WO{sub 3} or NaBiO{sub 3} because of charge separation promotion and the base effect of NaBiO{sub 3}.

  14. Evaluation of a sequential extraction process used for determining mercury binding mechanisms to coal combustion byproducts

    SciTech Connect

    James D. Noel; Pratim Biswas; Daniel E. Giammar

    2007-07-15

    This study evaluated the selectivity and effectiveness of a sequential extraction process used to determine mercury binding mechanisms to various materials that are present in coal combustion byproducts. A six-step sequential extraction process was applied to laboratory-synthesized materials with known mercury concentrations and binding mechanisms. These materials were calcite, hematite, goethite, and titanium dioxide. Fly ash from a full-scale coal-fired power plant was also investigated. The concentrations of mercury were measured using inductively coupled plasma (ICP) mass spectrometry, whereas the major elements were measured by ICP atomic emission spectrometry. The materials were characterized by X-ray powder diffraction and scanning electron microscopy with energy dispersive spectroscopy. The sequential extraction procedure provided information about the solid phases with which mercury was associated in the solid sample. The procedure effectively extracted mercury from the target phases. The procedure was generally selective in extracting mercury. However, some steps in the procedure extracted mercury from nontarget phases, and others resulted in mercury redistribution. Iron from hematite and goethite was only leached in the reducible and residual extraction steps. Some mercury associated with goethite was extracted in the ion exchangeable step, whereas mercury associated with hematite was extracted almost entirely in the residual step. Calcium in calcite and mercury associated with calcite were primarily removed in the acidsoluble extraction step. Titanium in titanium dioxide and mercury adsorbed onto titanium dioxide were extracted almost entirely in the residual step. 42 refs., 13 figs., 2 tabs.

  15. MESSENGER: Exploring Mercury's Magnetosphere

    NASA Astrophysics Data System (ADS)

    Slavin, James A.; Krimigis, Stamatios M.; Acuña, Mario H.; Anderson, Brian J.; Baker, Daniel N.; Koehn, Patrick L.; Korth, Haje; Livi, Stefano; Mauk, Barry H.; Solomon, Sean C.; Zurbuchen, Thomas H.

    2007-08-01

    The MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) mission to Mercury offers our first opportunity to explore this planet’s miniature magnetosphere since the brief flybys of Mariner 10. Mercury’s magnetosphere is unique in many respects. The magnetosphere of Mercury is among the smallest in the solar system; its magnetic field typically stands off the solar wind only ˜1000 to 2000 km above the surface. For this reason there are no closed drift paths for energetic particles and, hence, no radiation belts. Magnetic reconnection at the dayside magnetopause may erode the subsolar magnetosphere, allowing solar wind ions to impact directly the regolith. Inductive currents in Mercury’s interior may act to modify the solar wind interaction by resisting changes due to solar wind pressure variations. Indeed, observations of these induction effects may be an important source of information on the state of Mercury’s interior. In addition, Mercury’s magnetosphere is the only one with its defining magnetic flux tubes rooted beneath the solid surface as opposed to an atmosphere with a conductive ionospheric layer. This lack of an ionosphere is probably the underlying reason for the brevity of the very intense, but short-lived, ˜1-2 min, substorm-like energetic particle events observed by Mariner 10 during its first traversal of Mercury’s magnetic tail. Because of Mercury’s proximity to the sun, 0.3-0.5 AU, this magnetosphere experiences the most extreme driving forces in the solar system. All of these factors are expected to produce complicated interactions involving the exchange and recycling of neutrals and ions among the solar wind, magnetosphere, and regolith. The electrodynamics of Mercury’s magnetosphere are expected to be equally complex, with strong forcing by the solar wind, magnetic reconnection, and pick-up of planetary ions all playing roles in the generation of field-aligned electric currents. However, these field

  16. Mercury enrichment and its effects on atmospheric emissions in cement plants of China

    NASA Astrophysics Data System (ADS)

    Wang, Fengyang; Wang, Shuxiao; Zhang, Lei; Yang, Hai; Wu, Qingru; Hao, Jiming

    2014-08-01

    The cement industry is one of the most significant anthropogenic sources of atmospheric mercury emissions worldwide. In this study of three typical Chinese cement plants, mercury in kiln flue gas was sampled using the Ontario Hydro Method (OHM), and solid samples were analyzed. Particulate matter recycling, preheating of raw materials, and the use of coal and flue gas desulfurization derived gypsum contributed to emissions of Hg in the air and to accumulation in cement. Over 90% of the mercury input was emitted into the atmosphere. Mercury emission factors were 0.044-0.072 g/t clinker for the test plants. The major species emitted into the atmosphere from cement plants is oxidized mercury, accounting for 61%-91% of the total mercury in flue gas. The results of this study help improve the accuracy of the mercury emission inventory in China and provide useful information for developing mercury controls.

  17. Mercury risk from fluorescent lamps in China: current status and future perspective.

    PubMed

    Hu, Yuanan; Cheng, Hefa

    2012-09-01

    Energy-efficient lighting is one of the key measures for addressing electric power shortages and climate change mitigation, and fluorescent lamps are expected to dominate the lighting market in China over the next several years. This review presents an overview on the emissions and risk of mercury from fluorescent lamps during production and disposal, and discusses measures for reducing the mercury risk through solid waste management and source reduction. Fluorescent lamps produced in China used to contain relatively large amounts of mercury (up to 40 mg per lamp) due to the prevalence of liquid mercury dosing, which also released significant amounts of mercury to the environment. Upgrade of the mercury dosing technologies and manufacturing facilities had significantly reduced the mercury contents in fluorescent lamps, with most of them containing less than 10 or 5mg per lamp now. Occupational hygiene studies showed that mercury emissions occurred during fluorescent lamp production, particularly in the facilities using liquid mercury dosing, which polluted the environmental media at and surrounding the production sites and posed chronic health risk to the workers by causing neuropsychological and motor impairments. It is estimated that spent fluorescent lamps account for approximately 20% of mercury input in the MSW in China. Even though recycling of fluorescent lamps presents an important opportunity to capture the mercury they contain, it is difficult and not cost-effective at reducing the mercury risk under the broader context of mercury pollution control in China. In light of the significant mercury emissions associated with electricity generation in China, we propose that reduction of mercury emissions and risk associated with fluorescent lamps should be achieved primarily through lowering their mercury contents by the manufacturers while recycling programs should focus on elemental mercury-containing waste products instead of fluorescent lamps to recapture

  18. 15d-PGJ2-Loaded Solid Lipid Nanoparticles: Physicochemical Characterization and Evaluation of Pharmacological Effects on Inflammation.

    PubMed

    de Melo, Nathalie Ferreira Silva; de Macedo, Cristina Gomes; Bonfante, Ricardo; Abdalla, Henrique Ballassini; da Silva, Camila Morais Gonçalves; Pasquoto, Tatiane; de Lima, Renata; Fraceto, Leonardo Fernandes; Clemente-Napimoga, Juliana Trindade; Napimoga, Marcelo Henrique

    2016-01-01

    15-deoxy-Δ12,14-prostaglandin J2 (15d-PGJ2), a peroxisome proliferator-activated receptor-γ (PPAR-γ) agonist, has physiological properties including pronounced anti-inflammatory activity, though it binds strongly to serum albumin. The use of solid lipid nanoparticles (SLN) can improve therapeutic properties increasing drug efficiency and availability. 15d-PGJ2-SLN was therefore developed and investigated in terms of its immunomodulatory potential. 15d-PGJ2-SLN and unloaded SLN were physicochemically characterized and experiments in vivo were performed. Animals were pretreated with 15d-PGJ2-SLN at concentrations of 3, 10 or 30 μg·kg-1 before inflammatory stimulus with carrageenan (Cg), lipopolysaccharide (LPS) or mBSA (immune response). Interleukins (IL-1β, IL-10 and IL-17) levels were also evaluated in exudates. The 15d-PGJ2-SLN system showed good colloidal parameters and encapsulation efficiency of 96%. The results showed that the formulation was stable for up to 120 days with low hemolytic effects. The 15d-PGJ2-SLN formulation was able to reduce neutrophil migration in three inflammation models tested using low concentrations of 15d-PGJ2. Additionally, 15d-PGJ2-SLN increased IL-10 levels and reduced IL-1β as well as IL-17 in peritoneal fluid. The new 15d-PGJ2-SLN formulation highlights perspectives of a potent anti-inflammatory system using low concentrations of 15d-PGJ2. PMID:27575486

  19. 15d-PGJ2-Loaded Solid Lipid Nanoparticles: Physicochemical Characterization and Evaluation of Pharmacological Effects on Inflammation

    PubMed Central

    da Silva, Camila Morais Gonçalves; Pasquoto, Tatiane; de Lima, Renata; Fraceto, Leonardo Fernandes

    2016-01-01

    15-deoxy-Δ12,14-prostaglandin J2 (15d-PGJ2), a peroxisome proliferator-activated receptor-γ (PPAR-γ) agonist, has physiological properties including pronounced anti-inflammatory activity, though it binds strongly to serum albumin. The use of solid lipid nanoparticles (SLN) can improve therapeutic properties increasing drug efficiency and availability. 15d-PGJ2-SLN was therefore developed and investigated in terms of its immunomodulatory potential. 15d-PGJ2-SLN and unloaded SLN were physicochemically characterized and experiments in vivo were performed. Animals were pretreated with 15d-PGJ2-SLN at concentrations of 3, 10 or 30 μg·kg-1 before inflammatory stimulus with carrageenan (Cg), lipopolysaccharide (LPS) or mBSA (immune response). Interleukins (IL-1β, IL-10 and IL-17) levels were also evaluated in exudates. The 15d-PGJ2-SLN system showed good colloidal parameters and encapsulation efficiency of 96%. The results showed that the formulation was stable for up to 120 days with low hemolytic effects. The 15d-PGJ2-SLN formulation was able to reduce neutrophil migration in three inflammation models tested using low concentrations of 15d-PGJ2. Additionally, 15d-PGJ2-SLN increased IL-10 levels and reduced IL-1β as well as IL-17 in peritoneal fluid. The new 15d-PGJ2-SLN formulation highlights perspectives of a potent anti-inflammatory system using low concentrations of 15d-PGJ2. PMID:27575486

  20. Mercury pollution in China

    SciTech Connect

    Gui-Bin Jiang; Jian-Bo Shi; Xin-Bin Feng

    2006-06-15

    With a long history of mercury mining and use and a rapidly growing economy that relies heavily on coal for heat and energy, China faces an enormous challenge to reduce pollution from this toxic metal. The authors delineate what is known about the extent of the problem, regulatory steps are being taken to reduce mercury pollution, and next steps for environmental researchers. It addresses issues of mercury pollution from mercury and gold mining, coal combustion and the chemical industry. Data on dietary intake of mercury is also reported. 50 refs., 2 figs., 2 photos.

  1. Distribution of sedimentary mercury off Svalbard, European Arctic.

    PubMed

    Bełdowski, J; Miotk, M; Zaborska, A; Pempkowiak, J

    2015-03-01

    The European Arctic, including the Svalbard archipelago, receives mercury loads due to long range atmospheric transport, local contamination, melting of glaciers and as a result of bedrock weathering. Few studies have been devoted to the contamination history and sources of sedimentary mercury in the Svalbard area. This knowledge gap is addressed in this study. Concentrations of total mercury (10-80ng/g), fractions of mercury differing with affinity to the sediment matrix (88-97% refractory, 3-12% mobile), organic and methyl mercury (100-500pg/g) were measured in surface and subsurface sediments in the Spitsbergen fjords and in the Barents Sea off Svalbard. The atmospheric mercury signal can be observed in the Barents Sea, while in the Svalbard fjords it is strongly modified by supply of mercury from natural sources that may include weathering of rocks and glaciers melting, all modified by organic matter supply. Sedimentary methyl mercury concentrations seem to be dependent on environmental factors affecting mercury methylation rather than on location of sampling stations.

  2. Distribution of sedimentary mercury off Svalbard, European Arctic.

    PubMed

    Bełdowski, J; Miotk, M; Zaborska, A; Pempkowiak, J

    2015-03-01

    The European Arctic, including the Svalbard archipelago, receives mercury loads due to long range atmospheric transport, local contamination, melting of glaciers and as a result of bedrock weathering. Few studies have been devoted to the contamination history and sources of sedimentary mercury in the Svalbard area. This knowledge gap is addressed in this study. Concentrations of total mercury (10-80ng/g), fractions of mercury differing with affinity to the sediment matrix (88-97% refractory, 3-12% mobile), organic and methyl mercury (100-500pg/g) were measured in surface and subsurface sediments in the Spitsbergen fjords and in the Barents Sea off Svalbard. The atmospheric mercury signal can be observed in the Barents Sea, while in the Svalbard fjords it is strongly modified by supply of mercury from natural sources that may include weathering of rocks and glaciers melting, all modified by organic matter supply. Sedimentary methyl mercury concentrations seem to be dependent on environmental factors affecting mercury methylation rather than on location of sampling stations. PMID:25532769

  3. Simultaneous determination of nickel, cobalt and mercury ions in water samples by solid phase extraction using multiwalled carbon nanotubes as adsorbent after chelating with sodium diethyldithiocarbamate prior to high performance liquid chromatography.

    PubMed

    Zhou, Qingxiang; Xing, An; Zhao, Kuifu

    2014-09-19

    Multiwalled carbon nanotubes (MWNTs) have been widely used for the enrichment of trace important pollutants in environment because of its large specific surface area, high extraction efficiency, and easy operation. In this study, a solid phase extraction method was established to determine nickel (Ni(2+)), cobalt (Co(2+)) and mercury (Hg(2+)) ions using MWNTs as the adsorbent and sodium diethyldithiocarbamate (DDTC) as the chelating agent. The final analysis was performed on a high performance liquid chromatography (HPLC). The factors that may influence the extraction efficiency were optimized in detail including the type and volume of elution solvent, sample pH, volume of chelating agent solution, and volume of sample solution, etc. The experimental results indicated that good linear relationship between peak area and the concentration of the ions was achieved in the range of 0.1-100μgL(-1), 0.1-50μgL(-1), and 2.7-300μgL(-1) for Ni(2+), Co(2+), and Hg(2+), respectively. The precision was determined by calculating the relative standard deviation (R.S.D.) values that were in the range of 6.2-11.7% under the optimal conditions. The detection limits of Ni(2+), Co(2+), and Hg(2+) were in the range of 0.04-0.9μgL(-1) (S/N=3). The presented method was applied for the determination of the metal ions mentioned above in real water samples, and satisfied results were achieved. All these indicated that proposed method will be a good alternative tool for monitoring the target ions in environmental samples in the future.

  4. Mercury-impacted scrap metal: Source and nature of the mercury.

    PubMed

    Finster, Molly E; Raymond, Michelle R; Scofield, Marcienne A; Smith, Karen P

    2015-09-15

    The reuse and recycling of industrial solid wastes such as scrap metal is supported and encouraged both internationally and domestically, especially when such wastes can be used as substitutes for raw material. However, scrap metal processing facilities, such as mini-mills, have been identified as a source of mercury (Hg) emissions in the United States. This research aims to better define some of the key issues related to the source and nature of mercury in the scrap metal waste stream. Overall, it is difficult to pinpoint the key mercury sources feeding into scrap metal recycling facilities, quantify their associated mercury concentrations, or determine which chemical forms are most significant. Potential sources of mercury in scrap metal include mercury switches from discarded vehicles, electronic-based scrap from household appliances and related industrial systems, and Hg-impacted scrap metal from the oil and gas industry. The form of mercury associated with scrap metal varies and depends on the source type. The specific amount of mercury that can be adsorbed and retained by steel appears to be a function of both metallurgical and environmental factors. In general, the longer the steel is in contact with a fluid or condensate that contains measurable concentrations of elemental mercury, the greater the potential for mercury accumulation in that steel. Most mercury compounds are thermally unstable at elevated temperatures (i.e., above 350 °C). As such, the mercury associated with impacted scrap is expected to be volatilized out of the metal when it is heated during processing (e.g., shredding or torch cutting) or melted in a furnace. This release of fugitive gas (Hg vapor) and particulates, as well as Hg-impacted bag-house dust and control filters, could potentially pose an occupational exposure risk to workers at a scrap metal processing facility. Thus, identifying and characterizing the key sources of Hg-impacted scrap, and understanding the nature and extent

  5. Mercury-impacted scrap metal: Source and nature of the mercury.

    PubMed

    Finster, Molly E; Raymond, Michelle R; Scofield, Marcienne A; Smith, Karen P

    2015-09-15

    The reuse and recycling of industrial solid wastes such as scrap metal is supported and encouraged both internationally and domestically, especially when such wastes can be used as substitutes for raw material. However, scrap metal processing facilities, such as mini-mills, have been identified as a source of mercury (Hg) emissions in the United States. This research aims to better define some of the key issues related to the source and nature of mercury in the scrap metal waste stream. Overall, it is difficult to pinpoint the key mercury sources feeding into scrap metal recycling facilities, quantify their associated mercury concentrations, or determine which chemical forms are most significant. Potential sources of mercury in scrap metal include mercury switches from discarded vehicles, electronic-based scrap from household appliances and related industrial systems, and Hg-impacted scrap metal from the oil and gas industry. The form of mercury associated with scrap metal varies and depends on the source type. The specific amount of mercury that can be adsorbed and retained by steel appears to be a function of both metallurgical and environmental factors. In general, the longer the steel is in contact with a fluid or condensate that contains measurable concentrations of elemental mercury, the greater the potential for mercury accumulation in that steel. Most mercury compounds are thermally unstable at elevated temperatures (i.e., above 350 °C). As such, the mercury associated with impacted scrap is expected to be volatilized out of the metal when it is heated during processing (e.g., shredding or torch cutting) or melted in a furnace. This release of fugitive gas (Hg vapor) and particulates, as well as Hg-impacted bag-house dust and control filters, could potentially pose an occupational exposure risk to workers at a scrap metal processing facility. Thus, identifying and characterizing the key sources of Hg-impacted scrap, and understanding the nature and extent

  6. Self-Assembled Mercaptan on Mesoporous Silica (SAMMS) technology of mercury removal and stabilization

    SciTech Connect

    Feng, Xiangdong; Liu, Jun; Fryxell, G.E.

    1997-09-01

    This paper explains the technology developed to produce Self-Assembled Mercaptan on Mesoporous Silica (SAMMS) for mercury removal from aqueous wastewater and from organic wastes. The characteristics of SAMMS materials, including physical characteristics and mercury loading, and its application for mercury removal and stabilization are discussed. Binding kinetics and binding speciations are reported. Preliminary cost estimates are provided for producing SAMMS materials and for mercury removal from wastewater. The characteristics of SAMMS in mercury separation were studied at PNNL using simulated aqueous tank wastes and actual tritiated pump oil wastes from Savannah River Site; preliminary results are outlined. 47 refs., 16 figs., 16 tabs.

  7. Patterns of earthquakes and the effect of solid earth and ocean load tides at Mount St. Helens prior to the May 18, 1980, eruption

    SciTech Connect

    McNutt, S.R.; Beavan, R.J.

    1984-05-10

    Seismographs near Mount St. Helens Volcano recorded an earthquake swarm lasting nearly 2 months prior to the May 18, 1980, eruption. The earthquakes are divided into four classes based on station CPW (..delta.. = 116 km) seismogram characteristics: (1) events with Sv:P amplitude ratio > 3 and dominant frequency > 3 Hz; (2) events with Sv:P ratio between 1 and 3 and dominant frequency > 2 Hz; (3) events similar to characteristic 2 but with a strong (probably surface wave) phase just after the S phase; and (4) events with frequencies between 1 and 2 Hz lacking a clear S phase. The seismicity pattern for each of the four classes is unique. Solid earth stress and strain tides were calculated at the average hypocentral depth of 4 km. Stress and strain tides induced by ocean loading were also calculated; their amplitudes are typically 20-40% those of the solid earth tides at the location of Mount St. Helens. A weak but significant correlation exists between the latter two classes of events and the tides for a time interval of about 5 days preceding the first onset of volcanic tremor and about 5 days thereafter. The polarity of the correlation is opposite for the two classes of events. In each case, the phase of the correlation changes systematically with time, the changes coinciding with the onset of tremor on March 31 and with a pronounced decrease in earthquake energy release rate on April 3. There are no significant correlations between the tides and the number of events or energy release of these two classes of earthquakes during any other interval between March 20 and May 18, 1980. The first two classes of events show no evidence of significant tidal correlation at any time during the study period. 20 references, 8 figures, 2 tables.

  8. Development of novel activated carbon-based adsorbents for the control of mercury emissions from coal-fired power plants

    SciTech Connect

    Radisav D. Vidic

    1999-03-01

    In addition to naturally occurring mercury sources, anthropogenic activities increase the mercury loading to the environment. Although not all produced mercury is dissipated directly into the environment, only minor portions of the total production are stocked or recycled, and the rest of the mercury and its compounds is finally released in some way into atmosphere, surface waters and soil, or ends in landfills dumps, and refuse. Since mercury and its compounds are highly toxic, their presence in the environment constitutes potential impact on all living organisms, including man. The first serious consequence of industrial mercury discharges causing neurological disorder even death occurred in Minimata, Japan in 1953. Systematic studies showed that mercury poisoning is mainly found in fish-eating populations. However, various levels of mercury are also found in food other than fish. During the past several decades, research has been conducted on the evaluation of risks due to exposure to mercury and the development of control technologies for mercury emissions. In 1990, the Clean Air Act Amendments listed mercury, along with 10 other metallic species, as a hazardous air pollutant (HAP). This has further stimulated research for mercury control during the past several years. The impact of mercury on humans, sources of mercury in the environment, current mercury control strategies and the objective of this research are discussed in this section.

  9. Design and part-load performance of a hybrid system based on a solid oxide fuel cell reactor and a micro gas turbine

    NASA Astrophysics Data System (ADS)

    Costamagna, P.; Magistri, L.; Massardo, A. F.

    This paper addresses the design and off-design analysis of a hybrid system (HS) based on the coupling of a recuperated micro gas turbine (MGT) with a high temperature solid oxide fuel cell (SOFC) reactor. The SOFC reactor model is presented and discussed, taking into account the influence of the reactor lay-out, the current density, the air utilisation factor, the cell operating temperature, etc. The SOFC design and off-design performance is presented and discussed; the design and off-design models of a recuperated micro-gas turbine are also presented. The operating line, the influence of the micro gas turbine "variable speed" control, and the efficiency behaviour at part load are analysed in depth. Finally, the model of the hybrid system obtained by coupling the MGT and the SOFC reactor, considering the compatibility (technological constraints) of the two systems, is presented. The model allows the evaluation of the design and off-design behaviour of the hybrid system, particularly when the MGT variable speed control system is considered. The thermal efficiency of the hybrid system, taking into account its size (250/300 kW e), is noteworthy: higher than 60% at design point, and also very high at part load conditions. Such a result is mainly due to the simultaneous positive influence of SOFC off-design behaviour and MGT variable speed control. Moreover, it is possible to recover the waste heat from the gas at the MGT recuperator outlet ( Tgas is about 250°C) for cogeneration purposes.

  10. In-Flight Performance of the Mercury Laser Altimeter Laser Transmitter

    NASA Technical Reports Server (NTRS)

    Yu, Anthony W.; Sun, Xiaoli; Li, Steven X.; Cavanaugh, John F.; Neumann, Gregory A.

    2014-01-01

    The Mercury Laser Altimeter (MLA) is one of the payload instruments on the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft, which was launched on August 3, 2004. MLA maps Mercury's shape and topographic landforms and other surface characteristics using a diode-pumped solid-state laser transmitter and a silicon avalanche photodiode receiver that measures the round-trip time of individual laser pulses. The laser transmitter has been operating nominally during planetary flyby measurements and in orbit about Mercury since March 2011. In this paper, we review the MLA laser transmitter telemetry data and evaluate the performance of solid-state lasers under extended operation in a space environment.

  11. Mercury Report-Children's exposure to elemental mercury

    MedlinePlus

    ... PDF - 781KB] En Español [PDF - 6.6MB] What did ATSDR find? For children, most elemental mercury exposures ... that exposed children to elemental mercury. The report did not include a review of mercury exposures from ...

  12. Mercury Calibration System

    SciTech Connect

    John Schabron; Eric Kalberer; Joseph Rovani; Mark Sanderson; Ryan Boysen; William Schuster

    2009-03-11

    U.S. Environmental Protection Agency (EPA) Performance Specification 12 in the Clean Air Mercury Rule (CAMR) states that a mercury CEM must be calibrated with National Institute for Standards and Technology (NIST)-traceable standards. In early 2009, a NIST traceable standard for elemental mercury CEM calibration still does not exist. Despite the vacature of CAMR by a Federal appeals court in early 2008, a NIST traceable standard is still needed for whatever regulation is implemented in the future. Thermo Fisher is a major vendor providing complete integrated mercury continuous emissions monitoring (CEM) systems to the industry. WRI is participating with EPA, EPRI, NIST, and Thermo Fisher towards the development of the criteria that will be used in the traceability protocols to be issued by EPA. An initial draft of an elemental mercury calibration traceability protocol was distributed for comment to the participating research groups and vendors on a limited basis in early May 2007. In August 2007, EPA issued an interim traceability protocol for elemental mercury calibrators. Various working drafts of the new interim traceability protocols were distributed in late 2008 and early 2009 to participants in the Mercury Standards Working Committee project. The protocols include sections on qualification and certification. The qualification section describes in general terms tests that must be conducted by the calibrator vendors to demonstrate that their calibration equipment meets the minimum requirements to be established by EPA for use in CAMR monitoring. Variables to be examined include linearity, ambient temperature, back pressure, ambient pressure, line voltage, and effects of shipping. None of the procedures were described in detail in the draft interim documents; however they describe what EPA would like to eventually develop. WRI is providing the data and results to EPA for use in developing revised experimental procedures and realistic acceptance criteria based on

  13. Mercury: The World Closest to the Sun.

    ERIC Educational Resources Information Center

    Cordell, Bruce M.

    1984-01-01

    Discusses various topics related to the geology of Mercury including the origin of Mercury's magnetism, Mercury's motions, volcanism, scarps, and Mercury's violent birth and early life. Includes a table comparing Mercury's orbital and physical data to that of earth's. (JN)

  14. Process for low mercury coal

    DOEpatents

    Merriam, N.W.; Grimes, R.W.; Tweed, R.E.

    1995-04-04

    A process is described for producing low mercury coal during precombustion procedures by releasing mercury through discriminating mild heating that minimizes other burdensome constituents. Said mercury is recovered from the overhead gases by selective removal. 4 figures.

  15. Process for low mercury coal

    DOEpatents

    Merriam, Norman W.; Grimes, R. William; Tweed, Robert E.

    1995-01-01

    A process for producing low mercury coal during precombustion procedures by releasing mercury through discriminating mild heating that minimizes other burdensome constituents. Said mercury is recovered from the overhead gases by selective removal.

  16. surf3d: A 3-D finite-element program for the analysis of surface and corner cracks in solids subjected to mode-1 loadings

    NASA Technical Reports Server (NTRS)

    Raju, I. S.; Newman, J. C., Jr.

    1993-01-01

    A computer program, surf3d, that uses the 3D finite-element method to calculate the stress-intensity factors for surface, corner, and embedded cracks in finite-thickness plates with and without circular holes, was developed. The cracks are assumed to be either elliptic or part eliptic in shape. The computer program uses eight-noded hexahedral elements to model the solid. The program uses a skyline storage and solver. The stress-intensity factors are evaluated using the force method, the crack-opening displacement method, and the 3-D virtual crack closure methods. In the manual the input to and the output of the surf3d program are described. This manual also demonstrates the use of the program and describes the calculation of the stress-intensity factors. Several examples with sample data files are included with the manual. To facilitate modeling of the user's crack configuration and loading, a companion program (a preprocessor program) that generates the data for the surf3d called gensurf was also developed. The gensurf program is a three dimensional mesh generator program that requires minimal input and that builds a complete data file for surf3d. The program surf3d is operational on Unix machines such as CRAY Y-MP, CRAY-2, and Convex C-220.

  17. Gas chromatographic determination of polycyclic aromatic hydrocarbons in water and smoked rice samples after solid-phase microextraction using multiwalled carbon nanotube loaded hollow fiber.

    PubMed

    Matin, Amir Abbas; Biparva, Pourya; Gheshlaghi, Mohammad

    2014-12-29

    A novel solid-phase microextraction fiber was prepared based on multiwalled carbon nanotubes (MWCNTs) loaded on hollow fiber membrane pores. Stainless steel wire was used as unbreakable support. The major advantages of the proposed fiber are its (a) high reproducibility due to the uniform structure of the hollow fiber membranes, (b) high extraction capacity related to the porous structure of the hollow fiber and outstanding adsorptive characteristics of MWCNTs. The proposed fiber was applied for the microextraction of five representative polycyclic aromatic hydrocarbons (PAHs) from aqueous media (river and hubble-bubble water) and smoked rice samples followed by gas chromatographic determination. Analytical merits of the method, including high correlation coefficients [(0.9963-0.9992) and (0.9982-0.9999)] and low detection limits [(9.0-13.0ngL(-1)) and (40.0-150.0ngkg(-1))] for water and rice samples, respectively, made the proposed method suitable for the ultra-trace determination of PAHs. PMID:25476686

  18. Preparation, optimization and characterization of bovine lactoferrin-loaded liposomes and solid lipid particles modified by hydrophilic polymers using factorial design.

    PubMed

    Yao, Xudong; Bunt, Craig; Cornish, Jillian; Quek, Siew-Young; Wen, Jingyuan

    2014-05-01

    Bioadhesive liposomes and solid lipid particles (SLPs) modified by pectin and chitosan for oral administration of bovine lactoferrin (bLf) were prepared using a 2(4) full-factorial design to identify the key formulation variables influencing particle size and drug entrapment efficiency (EE). Netlike structures of the polymer-particle mixture consisting of a polymeric network in which multiple particles were imbedded were observed by scanning electron microscopy (SEM). Chemical stability of bLf after encapsulation into pectin- and chitosan-modified liposomes and SLPs was confirmed by Fourier transform infrared spectra (FTIR). Bovine lactoferrin was located within phospholipid bilayer, whereas in SLPs bLf was within the matrix. The crystalline nature of bLf after encapsulation was investigated by differential scanning calorimetry (DSC) of drug-loaded particles, indicating amorphous dispersion of bLf in the polymer-lipid matrix of pectin- and chitosan-modified liposomes and SLPs. In vivo pharmacokinetic investigation of bLf in pectin- and chitosan-modified liposomes and SLPs showed prolonged mean residence time (MRT) of bLf in rat blood and increased the relative bioavailability (Fbio %) by 1.95- to 2.69-fold compared with free bLf. The developed carrier systems are considered to be promising vehicles for oral delivery. PMID:24325576

  19. Making Mercury's Core with Light Elements

    NASA Technical Reports Server (NTRS)

    Vander Kaaden, Kathleen E.; McCubbin, Francis M.; Ross, D. Kent

    2016-01-01

    Recent results obtained from the MErcury Surface, Space ENvironment, GEochemistry, and Ranging spacecraft showed the surface of Mercury has low FeO abundances (less than 2 wt%) and high S abundances (approximately 4 wt%), suggesting the oxygen fugacity of Mercury's surface materials is somewhere between 3 to 7 log10 units below the IW buffer. The highly reducing nature of Mercury has resulted in a relatively thin mantle and a large core that has the potential to exhibit an exotic composition in comparison to the other terrestrial planets. This exotic composition may extend to include light elements (e.g., Si, C, S). Furthermore, has argued for a possible primary floatation crust on Mercury composed of graphite, which may require a core that is C-saturated. In order to investigate mercurian core compositions, we conducted piston cylinder experiments at 1 GPa, from 1300 C to 1700 C, using a range of starting compositions consisting of various Si-Fe metal mixtures (Si5Fe95, Si10Fe90, Si22Fe78, and Si35Fe65). All metals were loaded into graphite capsules used to ensure C-saturation during the duration of each experimental run. Our experiments show that Fe-Si metallic alloys exclude carbon relative to more Fe-rich metal. This exclusion of carbon commences within the range of 5 to 10 wt% Si. These results indicate that if Mercury has a Si-rich core (having more than approximately 5 wt% silicon), it would have saturated in carbon at low C abundances allowing for the possible formation of a graphite floatation crust as suggested by. These results have important implications for the thermal and magmatic evolution of Mercury.

  20. Substorms on Mercury?

    NASA Technical Reports Server (NTRS)

    Siscoe, G. L.; Ness, N. F.; Yeates, C. M.

    1974-01-01

    Qualitative similarities between some of the variations in the Mercury encounter data and variations in the corresponding regions of the earth's magnetosphere during substorms are pointed out. The Mariner 10 data on Mercury show a strong interaction between the solar wind and the plant similar to a scaled down version of that for the earth's magnetosphere. Some of the features observed in the night side Mercury magnetosphere suggest time dependent processes occurring there.

  1. Sorption and stability of mercury on activated carbon for emission control.

    PubMed

    Graydon, John W; Zhang, Xinzhi; Kirk, Donald W; Jia, Charles Q

    2009-09-15

    A leading strategy for control of mercury emissions from combustion processes involves removal of elemental mercury from the flue gas by injection of activated carbon sorbent. After particulate capture and disposal in a landfill, it is critical that the captured mercury remains permanently sequestered in the sorbent. The environmental stability of sorbed mercury was determined on two commercial, activated carbons, one impregnated using gaseous sulfur, and on two activated carbons that were impregnated with sulfur by reaction with SO(2). After loading with mercury vapor using a static technique, the stability of the sorbed mercury was characterized by two leaching methods. The standard toxicity characteristic leaching procedure showed leachate concentrations well below the limit of 0.2mg/L for all activated carbons. The nature of the sorbed mercury was further characterized by a sequential extraction scheme that was specifically optimized to distinguish clearly among the highly stable phases of mercury. This analysis revealed that there are two forms in which mercury is sequestered. In the sorbent that was impregnated by gaseous sulfur at a relatively low temperature, the mercury is present predominantly as HgS. In the other three sorbents, including two impregnated using SO(2), the mercury is predominantly present in the elemental form, physisorbed and chemisorbed to thiophene groups on the carbon surface. Both forms of binding are sufficiently stable to provide permanent sequestration of mercury in activated carbon sorbents after disposal.

  2. Peru Mercury Inventory 2006

    USGS Publications Warehouse

    Brooks, William E.; Sandoval, Esteban; Yepez, Miguel A.; Howard, Howell

    2007-01-01

    In 2004, a specific need for data on mercury use in South America was indicated by the United Nations Environmental Programme-Chemicals (UNEP-Chemicals) at a workshop on regional mercury pollution that took place in Buenos Aires, Argentina. Mercury has long been mined and used in South America for artisanal gold mining and imported for chlor-alkali production, dental amalgam, and other uses. The U.S. Geological Survey (USGS) provides information on domestic and international mercury production, trade, prices, sources, and recycling in its annual Minerals Yearbook mercury chapter. Therefore, in response to UNEP-Chemicals, the USGS, in collaboration with the Economic Section of the U.S. Embassy, Lima, has herein compiled data on Peru's exports, imports, and byproduct production of mercury. Peru was selected for this inventory because it has a 2000-year history of mercury production and use, and continues today as an important source of mercury for the global market, as a byproduct from its gold mines. Peru is a regional distributor of imported mercury and user of mercury for artisanal gold mining and chlor-alkali production. Peruvian customs data showed that 22 metric tons (t) of byproduct mercury was exported to the United States in 2006. Transshipped mercury was exported to Brazil (1 t), Colombia (1 t), and Guyana (1 t). Mercury was imported from the United States (54 t), Spain (19 t), and Kyrgyzstan (8 t) in 2006 and was used for artisanal gold mining, chlor-alkali production, dental amalgam, or transshipment to other countries in the region. Site visits and interviews provided information on the use and disposition of mercury for artisanal gold mining and other uses. Peru also imports mercury-containing batteries, electronics and computers, fluorescent lamps, and thermometers. In 2006, Peru imported approximately 1,900 t of a wide variety of fluorescent lamps; however, the mercury contained in these lamps, a minimum of approximately 76 kilograms (kg), and in

  3. Small passenger car transmission test: Mercury Lynx ATX transmission

    NASA Technical Reports Server (NTRS)

    Bujold, M. P.

    1981-01-01

    The testing of a Mercury Lynx automatic transmission is reported. The transmission was tested in accordance with a passenger car automatic transmission test code (SAE J65lb) which required drive performance, coast performance, and no load test conditions. Under these conditions, the transmission attained maximum efficiencies in the mid-ninety percent range both for drive performance test and coast performance tests. The torque, speed, and efficiency curves are presented, which provide the complete performance characteristics for the Mercury Lynx automatic transmission.

  4. Watershed Management and Mercury Biogeochemical Cycling in Lake Zapotlan, Mexico

    NASA Astrophysics Data System (ADS)

    Malczyk, E. A.; Branfireun, B. A.

    2009-05-01

    Lake Zapotlan is an endorheic subtropical eutrophic lake located in Jalisco State, Mexico. The lake supports a small but important local fishery for carp (Cyprinus sp.) and tilapia (Oreochromis sp.) and is an internationally recognized RAMSAR site. Very little research exists in these regions regarding mercury biogeochemical cycling. The lake receives considerable untreated municipal wastewater discharge that is elevated in inorganic total mercury (250-800 ng Hg/L) and organic methylmercury (3-10 ng CH3Hg+/L). The lake is also located on an active fault zone near an active volcano which may cause natural mercury enrichment. To assess a mercury risk to the commercial fishery we investigated the distribution of total inorganic mercury and organic methylmercury in waters, sediments, and fish tissues of the lake, surrounding wetlands, and incoming waters. Although there were high concentrations of inorganic mercury entering the lake in wastewater and seasonal tributary stream flow inputs, average concentrations in lake surface waters (3 ng Hg/L) and sediments (50 ng Hg/gdw) were relatively low. Average concentrations of total inorganic mercury were an order of magnitude higher in water (70 ng Hg/L) and sediment (245 ng Hg/gdw) in wetlands receiving the wastewater discharges. Mercury loading to the main body of the lake is likely reduced by these wetland buffer zones which allow mercury bound to particulate matter to settle out. A similar pattern was seen with respect to methylmercury concentrations. Average concentrations of methylmercury in lake surface water (below detect) and sediment (0.1 ng/gdw) were lower than in impounded wetlands (1 ng CH3Hg+/L, 0.7 ng CH3Hg+/gdw). Mercury concentrations in tilapia (3.5 ng/g) and carp (8 ng/g) from the commercial catch were found to be low in mercury; likely due to a combination of physiological, biogeochemical, and ecological factors.

  5. Mercury removal in utility wet scrubber using a chelating agent

    DOEpatents

    Amrhein, Gerald T.

    2001-01-01

    A method for capturing and reducing the mercury content of an industrial flue gas such as that produced in the combustion of a fossil fuel or solid waste adds a chelating agent, such as ethylenediaminetetraacetic acid (EDTA) or other similar compounds like HEDTA, DTPA and/or NTA, to the flue gas being scrubbed in a wet scrubber used in the industrial process. The chelating agent prevents the reduction of oxidized mercury to elemental mercury, thereby increasing the mercury removal efficiency of the wet scrubber. Exemplary tests on inlet and outlet mercury concentration in an industrial flue gas were performed without and with EDTA addition. Without EDTA, mercury removal totaled 42%. With EDTA, mercury removal increased to 71%. The invention may be readily adapted to known wet scrubber systems and it specifically provides for the removal of unwanted mercury both by supplying S.sup.2- ions to convert Hg.sup.2+ ions into mercuric sulfide (HgS) and by supplying a chelating agent to sequester other ions, including but not limited to Fe.sup.2+ ions, which could otherwise induce the unwanted reduction of Hg.sup.2+ to the form, Hg.sup.0.

  6. Tailoring ultraresins based on the cross-linking of polyethylene imines. Comparative investigation of the chemical composition, the swelling, the mobility, the chemical accessibility, and the performance in solid-phase synthesis of very high loaded resins.

    PubMed

    Barth, Michael; Rademann, Jörg

    2004-01-01

    Ultraresins have been prepared from polyethyleneimines and cross-linking molecules and have been provided with various degrees of cross-linking. The total nitrogen loading and the loading with secondary and with tertiary amines have been determined in all products. Nitrogen loadings of the novel resins were up to 15 mmol/g, reactive secondary amines up to 13.8 mmol/g. In addition to the exceptionally high loading, the novel resins displayed efficient swelling volumes in polar and nonpolar solvents. The mobility of resin-bound species as determined by EPR-spectroscopy, depending on the amount of cross-linker, indicated good flexibility and reactivity of this resin type. The novel, high-loaded resins have been investigated subsequently in solid-phase synthesis. The Rink amide linker and two different hydroxy linkers (hydroxyacetamide, HMPB) have been attached to the resin. Despite the high loadings, the secondary amines were easily accessible and could be functionalized exhaustively. Reactivity of the linker-coupled resins was found to be closely related to the resin composition. Increased resin cross-linking led to reduced swelling, reduced mobility, and reduced reactivity in the synthesis of a medium-sized model peptide. As the result of the systematic investigation of structure-property relations in Ultraresins, a support material was identified that combined high reactivity and a mobility in the range of the extremely flexible Tentagel supports. In the optimized Ultraresin, >95% of all available secondary nitrogens could be coupled with Rink linker or with the small 2-hydroxyacetamide anchor, resulting in loadings from 2.7 to 6.8 mmol/g, respectively. A resin with an attached HMPB linker and spacer delivered analytically pure peptides in solid-phase synthesis, fully exploiting the exceptionally high loadings.

  7. Potassium permanganate for mercury vapor environmental control

    NASA Technical Reports Server (NTRS)

    Kuivinen, D. E.

    1972-01-01

    Potassium permanganate (KMnO4) was evaluated for application in removing mercury vapor from exhaust air systems. The KMnO4 may be used in water solution with a liquid spray scrubber system or as a solid adsorber bed material when impregnated onto a zeolite. Air samples contaminated with as much as 112 mg/cu m of mercury were scrubbed to 0.06mg/cum with the KMnO4-impregnated zeolite (molecular sieve material). The water spray solution of permanganate was also found to be as effective as the impregnated zeolite. The KMnO4-impregnated zeolite was applied as a solid adsorber material to (1) a hardware decontamination system, (2) a model incinerator, and (3) a high vacuum chamber for ion engine testing with mercury as the propellant. A liquid scrubber system was also applied in an incinerator system. Based on the results of these experiments, it is concluded that the use of KMnO4 can be an effective method for controlling noxious mercury vapor.

  8. Mercury Binding Sites in Thiol-Functionalized Mesostructured Silica

    SciTech Connect

    Billinge, Simon J.L.; McKimmey, Emily J.; Shatnawi, Mouath; Kim, HyunJeong; Petkov, Valeri; Wermeille, Didier; Pinnavaia, Thomas J.

    2010-07-13

    Thiol-functionalized mesostructured silica with anhydrous compositions of (SiO{sub 2}){sub 1-x}(LSiO{sub 1.5}){sub x}, where L is a mercaptopropyl group and x is the fraction of functionalized framework silicon centers, are effective trapping agents for the removal of mercuric(II) ions from water. In the present work, we investigate the mercury-binding mechanism for representative thiol-functionalized mesostructures by atomic pair distribution function (PDF) analysis of synchrotron X-ray powder diffraction data and by Raman spectroscopy. The mesostructures with wormhole framework structures and compositions corresponding to x = 0.30 and 0.50 were prepared by direct assembly methods in the presence of a structure-directing amine porogen. PDF analyses of five mercury-loaded compositions with Hg/S ratios of 0.50-1.30 provided evidence for the bridging of thiolate sulfur atoms to two metal ion centers and the formation of chain structures on the pore surfaces. We find no evidence for Hg-O bonds and can rule out oxygen coordination of the mercury at greater than the 10% level. The relative intensities of the PDF peaks corresponding to Hg-S and Hg-Hg atomic pairs indicate that the mercury centers cluster on the functionalized surfaces by virtue of thiolate bridging, regardless of the overall mercury loading. However, the Raman results indicate that the complexation of mercury centers by thiolate depends on the mercury loading. At low mercury loadings (Hg/S {le} 0.5), the dominant species is an electrically neutral complex in which mercury most likely is tetrahedrally coordinated to bridging thiolate ligands, as in Hg(SBu{sup t}){sub 2}. At higher loadings (Hg/S 1.0-1.3), mercury complex cations predominate, as evidenced by the presence of charge-balancing anions (nitrate) on the surface. This cationic form of bound mercury is assigned a linear coordination to two bridging thiolate ligands.

  9. Modeling Mercury in Proteins.

    PubMed

    Parks, J M; Smith, J C

    2016-01-01

    Mercury (Hg) is a naturally occurring element that is released into the biosphere both by natural processes and anthropogenic activities. Although its reduced, elemental form Hg(0) is relatively nontoxic, other forms such as Hg(2+) and, in particular, its methylated form, methylmercury, are toxic, with deleterious effects on both ecosystems and humans. Microorganisms play important roles in the transformation of mercury in the environment. Inorganic Hg(2+) can be methylated by certain bacteria and archaea to form methylmercury. Conversely, bacteria also demethylate methylmercury and reduce Hg(2+) to relatively inert Hg(0). Transformations and toxicity occur as a result of mercury interacting with various proteins. Clearly, then, understanding the toxic effects of mercury and its cycling in the environment requires characterization of these interactions. Computational approaches are ideally suited to studies of mercury in proteins because they can provide a detailed molecular picture and circumvent issues associated with toxicity. Here, we describe computational methods for investigating and characterizing how mercury binds to proteins, how inter- and intraprotein transfer of mercury is orchestrated in biological systems, and how chemical reactions in proteins transform the metal. We describe quantum chemical analyses of aqueous Hg(II), which reveal critical factors that determine ligand-binding propensities. We then provide a perspective on how we used chemical reasoning to discover how microorganisms methylate mercury. We also highlight our combined computational and experimental studies of the proteins and enzymes of the mer operon, a suite of genes that confer mercury resistance in many bacteria. Lastly, we place work on mercury in proteins in the context of what is needed for a comprehensive multiscale model of environmental mercury cycling.

  10. Modeling Mercury in Proteins

    SciTech Connect

    Smith, Jeremy C; Parks, Jerry M

    2016-01-01

    Mercury (Hg) is a naturally occurring element that is released into the biosphere both by natural processes and anthropogenic activities. Although its reduced, elemental form Hg(0) is relatively non-toxic, other forms such as Hg2+ and, in particular, its methylated form, methylmercury, are toxic, with deleterious effects on both ecosystems and humans. Microorganisms play important roles in the transformation of mercury in the environment. Inorganic Hg2+ can be methylated by certain bacteria and archaea to form methylmercury. Conversely, bacteria also demethylate methylmercury and reduce Hg2+ to relatively inert Hg(0). Transformations and toxicity occur as a result of mercury interacting with various proteins. Clearly, then, understanding the toxic effects of mercury and its cycling in the environment requires characterization of these interactions. Computational approaches are ideally suited to studies of mercury in proteins because they can provide a detailed picture and circumvent issues associated with toxicity. Here we describe computational methods for investigating and characterizing how mercury binds to proteins, how inter- and intra-protein transfer of mercury is orchestrated in biological systems, and how chemical reactions in proteins transform the metal. We describe quantum chemical analyses of aqueous Hg(II), which reveal critical factors that determine ligand binding propensities. We then provide a perspective on how we used chemical reasoning to discover how microorganisms methylate mercury. We also highlight our combined computational and experimental studies of the proteins and enzymes of the mer operon, a suite of genes that confers mercury resistance in many bacteria. Lastly, we place work on mercury in proteins in the context of what is needed for a comprehensive multi-scale model of environmental mercury cycling.

  11. Modeling Mercury in Proteins.

    PubMed

    Parks, J M; Smith, J C

    2016-01-01

    Mercury (Hg) is a naturally occurring element that is released into the biosphere both by natural processes and anthropogenic activities. Although its reduced, elemental form Hg(0) is relatively nontoxic, other forms such as Hg(2+) and, in particular, its methylated form, methylmercury, are toxic, with deleterious effects on both ecosystems and humans. Microorganisms play important roles in the transformation of mercury in the environment. Inorganic Hg(2+) can be methylated by certain bacteria and archaea to form methylmercury. Conversely, bacteria also demethylate methylmercury and reduce Hg(2+) to relatively inert Hg(0). Transformations and toxicity occur as a result of mercury interacting with various proteins. Clearly, then, understanding the toxic effects of mercury and its cycling in the environment requires characterization of these interactions. Computational approaches are ideally suited to studies of mercury in proteins because they can provide a detailed molecular picture and circumvent issues associated with toxicity. Here, we describe computational methods for investigating and characterizing how mercury binds to proteins, how inter- and intraprotein transfer of mercury is orchestrated in biological systems, and how chemical reactions in proteins transform the metal. We describe quantum chemical analyses of aqueous Hg(II), which reveal critical factors that determine ligand-binding propensities. We then provide a perspective on how we used chemical reasoning to discover how microorganisms methylate mercury. We also highlight our combined computational and experimental studies of the proteins and enzymes of the mer operon, a suite of genes that confer mercury resistance in many bacteria. Lastly, we place work on mercury in proteins in the context of what is needed for a comprehensive multiscale model of environmental mercury cycling. PMID:27497164

  12. Preparation and Characterization of Loperamide-Loaded Dynasan 114 Solid Lipid Nanoparticles for Increased Oral Absorption In the Treatment of Diarrhea

    PubMed Central

    Wei, Lili; Yang, Yunfang; Shi, Kun; Wu, Jun; Zhao, Wei; Mo, Jingxin

    2016-01-01

    The aim of the project was to assemble two optimum solid lipid nanoparticle (SLN) formulations for oral delivery of loperamide (LPM) to treat different types of diarrhea, and to evaluate their release profiles in vitro and pharmacokinetic properties in vivo. In this work, glyceryl trimyristate (Dynasan 114) nanoparticles containing the drug LPM and sodium cholate as a stabilizer were prepared using a modified solvent evaporation technique. Two LPM-loaded SLNs, namely LPM-SLN-1 (LPM-SLN with a high ratio rate of lipid to drug) and LPM-SLN-2 (LPM-SLN with a low ratio rate of lipid to drug), were prepared by the solvent evaporation method. A change in the lipid concentration affects the characteristics of LPM-SLNs. The average sizes of the LPM-SLNs were 303 ± 18 nm and 519 ± 36 nm, separately, as analyzed by dynamic light scattering. The LPM-SLNs were found to be round with a smooth surface, as observed using a transmission electron microscope and a scanning electron microscope. The average encapsulation efficiencies were 87 ± 3.78% w/w and 84 ± 5.17%, accordingly. In the in vitro release experiments, LPM-SLNs showed a continuous release profile of LPM without any burst release. The oral bioavailability of LPM-SLNs was analyzed using Wistar rats. The relative bioavailabilities of LPM-SLNs were 227 and 153%, respectively, as compared that of the LPM tablet. There was no difference in the Tmax between LPM-SLN-2 and the LPM tablet. In conclusion, LPM-SLN-1 significantly improved the oral bioavailability of LPM, while LPM-SLN-2 having the same swift action as the LPM tablet. These results demonstrate the potential of LPM-SLNs in the oral delivery of LPM to treat different types of diarrhea. PMID:27708583

  13. Methazolamide-loaded solid lipid nanoparticles modified with low-molecular weight chitosan for the treatment of glaucoma: vitro and vivo study.

    PubMed

    Wang, Fengzhen; Chen, Li; Zhang, Dongsheng; Jiang, Sunmin; Shi, Kun; Huang, Yuan; Li, Rui; Xu, Qunwei

    2014-11-01

    The aims of this study were to design and characterize methazolamide (MTZ)-loaded solid lipid nanoparticles (SLN) with and without modification of low molecular weight chitosan (CS) and compare their potentials for ocular drug delivery. Low molecular weight CS was obtained via a modified chemical oxidative degradation method. SLN with CS (CS-SLN-MTZ) and without CS (SLN-MTZ) were prepared according to a modified emulsion-solvent evaporation method. SLN-MTZ and CS-SLN-MTZ were 199.4 ± 2.8 nm and 252.8 ± 4.0 nm in particle size, -21.3 ± 1.9 mV and +31.3 ± 1.7 mV in zeta potential, respectively. Physical stability studies demonstrated that CS-SLN-MTZ remained stable for at least 4 months at 4 °C, while SLN-MTZ no more than 2 months. A prolonged in vitro release profile of MTZ from CS-SLN-MTZ was obtained compared with SLN-MTZ. Furthermore, CS-SLN-MTZ presented a better permeation property in excised rabbit cornea. In vivo studies indicated that the intraocular pressure lowering effect of CS-SLN-MTZ (245.75 ± 18.31 mmHg × h) was significantly better than both SLN-MTZ (126.74 ± 17.73 mmHg × h) and commercial product Brinzolamide Eye Drops AZOPT® (171.17 ± 16.45 mmHg × h). The maximum percentage decrease in IOP of CS-SLN-MTZ (42.78 ± 7.71%) was higher than SLN-MTZ (27.82 ± 4.15%) and was comparable to AZOPT (38.06 ± 1.25%). CS-SLN-MTZ showed no sign of ocular irritancy according to the Draize method and the histological examination.

  14. Sucrose ester stabilized solid lipid nanoparticles and nanostructured lipid carriers: I. Effect of formulation variables on the physicochemical properties, drug release and stability of clotrimazole-loaded nanoparticles

    NASA Astrophysics Data System (ADS)

    Das, Surajit; Kiong Ng, Wai; Tan, Reginald B. H.

    2014-03-01

    The objective of this study was to develop and evaluate solid lipid nanoparticles (SLNs) and nanostructured lipid carriers (NLCs) utilizing sucrose ester as a stabilizer/emulsifier for the controlled release of drug/active. Both SLNs and NLCs were prepared using different sugar esters to screen out the most suitable stabilizer. Clotrimazole was used as a model active/drug. The effect of different formulation variables on the particle size, polydispersity index and drug encapsulation efficiency of SLNs and NLCs was evaluated and compared. SLNs and NLCs were physicochemically characterized and compared using Cryo-SEM, DSC and XRD. Furthermore, a drug release study of SLNs and NLCs was conducted. Finally, physicochemical stability (size, PI, ZP, EE) of the SLNs and NLCs was checked at 25 ± 2 °C and at 2-8 °C. Among the sucrose esters, D-1216 was found to be most suitable for both SLNs and NLCs. Formulation variables exhibited a significant impact on size, PI and EE of the nanoparticles. SLNs with ˜120 nm size, ˜0.23 PI, ˜I26I mV ZP, ˜87% EE and NLCs with ˜160 nm size, 0.15 PI, ˜I26I mV ZP, ˜88% EE were produced. Cryo-SEM revealed spherical particles with a smooth surface but did not exhibit any difference in surface morphology between SLNs and NLCs. DSC and XRD results demonstrated the disappearance of clotrimazole peak(s) in drug-loaded SLNs and NLCs. Faster drug release was observed from SLNs than NLCs. NLCs were found to be more stable than SLNs in terms of size, PI, EE and drug release. The results indicated that both SLNs and NLCs stabilized with sucrose ester D-1216 can be used as controlled release carriers although NLCs have an edge over SLNs.

  15. MESSENGER: Exploring Mercury's Magnetosphere

    NASA Technical Reports Server (NTRS)

    Slavin, James A.

    2008-01-01

    The MESSENGER mission to Mercury offers our first opportunity to explore this planet's miniature magnetosphere since Mariner 10's brief fly-bys in 1974-5. Mercury's magnetosphere is unique in many respects. The magnetosphere of Mercury is the smallest in the solar system with its magnetic field typically standing off the solar wind only - 1000 to 2000 km above the surface. For this reason there are no closed dri-fi paths for energetic particles and, hence, no radiation belts; the characteristic time scales for wave propagation and convective transport are short possibly coupling kinetic and fluid modes; magnetic reconnection at the dayside magnetopause may erode the subsolar magnetosphere allowing solar wind ions to directly impact the dayside regolith; inductive currents in Mercury's interior should act to modify the solar In addition, Mercury's magnetosphere is the only one with its defining magnetic flux tubes rooted in a planetary regolith as opposed to an atmosphere with a conductive ionosphere. This lack of an ionosphere is thought to be the underlying reason for the brevity of the very intense, but short lived, approx. 1-2 min, substorm-like energetic particle events observed by Mariner 10 in Mercury's magnetic tail. In this seminar, we review what we think we know about Mercury's magnetosphere and describe the MESSENGER science team's strategy for obtaining answers to the outstanding science questions surrounding the interaction of the solar wind with Mercury and its small, but dynamic magnetosphere.

  16. Dynamic duo captures mercury

    SciTech Connect

    Senior, C.; Adams, B.

    2006-02-15

    There is strong evidence that the combination of wet flue gas desulphurisation (FGD) scrubbers and selective catalytic reduction (SCR) can prove a viable and formidable combination for knocking out mercury. This article analyzes the capabilities and limitations of the SCR-FGD combination for mercury compliance, including applicability to different types of coal and issues with scrubber by-products. 3 figs.

  17. Mercury in the environment

    SciTech Connect

    Idaho National Laboratory - Mike Abbott

    2008-08-06

    Abbott works for Idaho National Laboratory as an environmental scientist. Using state-of-thescienceequipment, he continuously samples the air, looking for mercury. In turn, he'll analyzethis long-term data and try to figure out the mercury's point of or

  18. Mercury and Pregnancy

    MedlinePlus

    ... made when mercury in the air gets into water. The mercury in the air comes from natural sources (such as volcanoes) and man-made sources (such as burning coal and other pollution). You can get methylmercury in your body by ...

  19. Mercury in the environment

    ScienceCinema

    Idaho National Laboratory - Mike Abbott

    2016-07-12

    Abbott works for Idaho National Laboratory as an environmental scientist. Using state-of-thescienceequipment, he continuously samples the air, looking for mercury. In turn, he'll analyzethis long-term data and try to figure out the mercury's point of or

  20. Mercury poisoning in wildlife

    USGS Publications Warehouse

    Heinz, G.H.; Fairbrother, Anne; Locke, Louis N.; Hoff, Gerald L.

    1996-01-01

    Mercury is an intriguing contaminant because it has complex chemical properties, a wide range of harmful effects, and an infinite persistence in the environment. Die-offs of wildlife due to mercury have occurred in many countries, especially before mercury seed dressings were banned. Today, most mercury problems are associated with aquatic environments. Methylmercury, the most toxic chemical form, attacks many organ systems, but damage to the central nervous system is most severe. Harmful wet-weight concentrations of mercury, as methylmercury, in the tissues of adult birds and mammals range from about 8-30 ppm in the brain, 20-60 ppm in liver, 20-60 ppm in kidney, and 15-30 ppm in muscle. Young animals may be more sensitive.

  1. Gravity field and internal structure of Mercury from MESSENGER.

    PubMed

    Smith, David E; Zuber, Maria T; Phillips, Roger J; Solomon, Sean C; Hauck, Steven A; Lemoine, Frank G; Mazarico, Erwan; Neumann, Gregory A; Peale, Stanton J; Margot, Jean-Luc; Johnson, Catherine L; Torrence, Mark H; Perry, Mark E; Rowlands, David D; Goossens, Sander; Head, James W; Taylor, Anthony H

    2012-04-13

    Radio tracking of the MESSENGER spacecraft has provided a model of Mercury's gravity field. In the northern hemisphere, several large gravity anomalies, including candidate mass concentrations (mascons), exceed 100 milli-Galileos (mgal). Mercury's northern hemisphere crust is thicker at low latitudes and thinner in the polar region and shows evidence for thinning beneath some impact basins. The low-degree gravity field, combined with planetary spin parameters, yields the moment of inertia C/MR(2) = 0.353 ± 0.017, where M and R are Mercury's mass and radius, and a ratio of the moment of inertia of Mercury's solid outer shell to that of the planet of C(m)/C = 0.452 ± 0.035. A model for Mercury's radial density distribution consistent with these results includes a solid silicate crust and mantle overlying a solid iron-sulfide layer and an iron-rich liquid outer core and perhaps a solid inner core. PMID:22438509

  2. Gravity Field and Internal Structure of Mercury from MESSENGER

    NASA Technical Reports Server (NTRS)

    Smith, David E.; Zuber, Maria T.; Phillips, Roger J.; Solomon, Sean C.; Hauck, Steven A., II; Lemoine, Frank G.; Mazarico, Erwan; Neumann, Gregory A.; Peale, Stanton J.; Margot, Jean-Luc; Johnson, Catherine L.; Torrence, Mark H.; Perry, Mark E.; Rowlands, David D.; Goossens, Sander; Head, James W.; Taylor, Anthony H.

    2012-01-01

    Radio tracking of the MESSENGER spacecraft has provided a model of Mercury's gravity field. In the northern hemisphere, several large gravity anomalies, including candidate mass concentrations (mascons), exceed 100 milli-Galileos (mgal). Mercury's northern hemisphere crust is thicker at low latitudes and thinner in the polar region and shows evidence for thinning beneath some impact basins. The low-degree gravity field, combined with planetary spin parameters, yields the moment of inertia C/M(R(exp 2) = 0.353 +/- 0.017, where M and R are Mercury's mass and radius, and a ratio of the moment of inertia of Mercury's solid outer shell to that of the planet of C(sub m)/C = 0.452 +/- 0.035. A model for Mercury s radial density distribution consistent with these results includes a solid silicate crust and mantle overlying a solid iron-sulfide layer and an iron-rich liquid outer core and perhaps a solid inner core.

  3. Mpo - the Bepicolombo Mercury Planetary Orbiter.

    NASA Astrophysics Data System (ADS)

    Benkhoff, J.

    2008-09-01

    so far. BepiColombo will also contribute to the understanding of the history and formation of the inner planets of the Solar System in general, including the Earth. The 'Mercury Planetary Orbiter' (MPO), under ESA's responsibility, will study the surface and the internal composition of the planet at different wavelengths and with different techniques. The Mercury Magnetospheric Orbiter (MMO), under the responsibility of the Japan Aerospace Exploration Agency (ISAS/JAXA), will study the magnetosphere, that is the region of space around the planet that is dominated by its magnetic field. Objectives BepiColombo will study and understand the composition, geophysics, atmosphere, magnetosphere and history of Mercury, the least explored planet in the inner Solar System. In particular, the mission objectives are: • markedly higher than that of all other terrestrial planets, Moon included • to understand if the core of Mercury is liquid or solid, and if the planet is still tectonically active today • to understand why such a small planet possesses an intrinsic magnetic field, while Venus, Mars and the Moon do not have any, and investigate if Mercury's magnetised environment is characterised by features reminiscent of the aurorae, radiation belts and magnetospheric substorms observed at Earth • to understand why spectroscopic observations not reveal the presence of any iron, while this element is supposedly the major constituent of the planet • to investigate if the permanently shadowed craters of the polar regions contain sulphur or water ice • to observe the yet unseen hemisphere of Mercury • to study the production mechanisms of the exosphere and to understand the interaction between planetary magnetic field and the solar wind in the absence of a ionosphere • to obtain new clues about the composition of the primordial solar nebula and about the formation of the solar system • to test general relativity with improved accuracy, taking advantage of the

  4. Getting Mercury out of Schools.

    ERIC Educational Resources Information Center

    1999

    This guide was prepared while working with many Massachusetts schools to remove items that contain mercury and to find suitable alternatives. It contains fact sheets on: mercury in science laboratories and classrooms, mercury in school buildings and maintenance areas, mercury in the medical office and in medical technology classrooms in vocational…

  5. Load and dynamic assessment of B-52B-008 carrier aircraft for finned configuration 1 space shuttle solid rocket booster decelerator subsystem drop test vehicle. Volume 3: Pylon load data method 1

    NASA Technical Reports Server (NTRS)

    Quade, D. A.

    1978-01-01

    The pylon loading at the drop test vehicle and wing interface attach points is presented. The loads shown are determined using a stiffness method, which assumes the side stiffness of the foreward hook guide to be one-fourth of the fore and aft stiffness of each drag pin. The net effect of this assumption is that the forward hook guide reacts approximately 85% of the drop test vehicle yawing moment. For a comparison of these loads to previous X-15 analysis design loadings, see Volume 1 of this document.

  6. Load and dynamic assessment of B-52B-008 carrier aircraft for finned configuration 1 space shuttle solid rocket booster deceleration subsystem drop test vehicle. Volume 4: Pylon load data

    NASA Technical Reports Server (NTRS)

    Quade, D. A.

    1978-01-01

    The pylon loading at the drop test vehicle and wing interface attack points is presented. The loads shown are determined using a stiffness method, which assumes the side stiffness of the forward hook guide and the fore and aft stiffness of each drag pin to be equal. The net effect of this assumption is that the forward hook guide reacts approximately 96% of the drop test vehicle yawing moment. For a comparison of these loads to previous X-15 analysis design loadings, see Volume 1 of this document.

  7. A comparison of the dynamics and bioconcentration of mercury in Oregon reservoirs

    SciTech Connect

    Park, J.; Curtis, L.

    1995-12-31

    The authors assessed the extent of mercury pollution and its bioconcentration effects in fish in two Oregon reservoirs. Cottage Grove and Dorena Reservoirs are located in same ecoregions but distinguished by the history of mercury mining in the formers watershed. Past mercury mining activity deposited up to 271 {micro}g/g mercury and 2.6 mg/g sulfur in soils of near Black Butte Mine, OR. Sediment mercury concentration in the main tributary of Cottage Grove Reservoir, which drains the tailings of the past mercury mine, was ten times higher than in sediment from other tributaries to the reservoir. However there was no significantly difference between mercury concentration in each tributary of Dorena Reservoir, which has no mercury mining history in its watershed. Average mercury concentration in sediment of Cottage Grove Reservoir (0.67 {micro}g/g dw) was higher than of Dorena Reservoir (0.12 {micro}g/g dw). The authors also determined percent volatile solid and grain size effect in sediment. Maximum mercury concentration exceeded the FDA limit 1 {micro}g/g ww for largemouth bass (Micropterus salmoides) and bluegill (Lepomis macrochirus) in Cottage Grove Reservoir. All fish species (largemouth bass, bluegill, crappie (Pomoxis nigromaculatus), catfish (Ictalurus nebulosus)) from Cottage Grove Reservoir had significantly higher levels of mercury than from Dorena Reservoir. Fish weight and age was positively correlated with mercury concentration in both-reservoirs and seasonal variation of mercury concentration in fish was examined. These results indicate that the Black Butte Mine is the main source of mercury and mercury bioconcentration in fish represents a management problem in Cottage Grove Reservoir.

  8. CHARACTERISTICS OF MERCURY DESORPTION FROM SORBENTS AT ELEVATED TEMPERATURES. (R826694C697)

    EPA Science Inventory

    This study investigated the dynamic desorption characteristics of mercury during the thermal treatment of mercury-loaded sorbents at elevated temperatures under fixed-bed operations. Experiments were carried out in a 25.4 mm ID quartz bed enclosed in an electric furnace. ...

  9. CHARACTERISTICS OF MERCURY DESORPTION FROM SORBENTS AT ELEVATED TEMPERATURES. (R822721C697)

    EPA Science Inventory

    This study investigated the dynamic desorption characteristics of mercury during the thermal treatment of mercury-loaded sorbents at elevated temperatures under fixed-bed operations. Experiments were carried out in a 25.4 mm ID quartz bed enclosed in an electric furnace. ...

  10. Mercury speciation analysis in terrestrial animal tissues.

    PubMed

    Berzas Nevado, J J; Rodríguez Martín-Doimeadios, R C; Guzmán Bernardo, F J; Rodríguez Fariñas, N; Patiño Ropero, M J

    2012-09-15

    No previous analytical procedures are available and validated for mercury speciation analysis in terrestrial animal tissues. This analysis is a difficult task both because the expected concentrations are low, since important accumulation process are not likely to occur, and also because there are not commercially available certified reference material. Thus, an analytical methodology has been developed and validated for mercury speciation for the specific case of terrestrial animal tissues. The proposed method is based on the quantitative extraction of the species by closed-vessel microwave assisted heating with an alkaline reagent, followed by ethylation. The ethylated derivatives were then submitted to head-space solid phase microextraction with a 100 μm polidimethylsiloxane-coated fiber, and desorbed onto a gas chromatograph coupled to atomic fluorescence detection via pyrolysis unit (HS-SPME-GC-pyro-AFS). Procedural detection limits were 31.8 ng g(-1) and 52.5 ng g(-1) for CH(3)Hg(+) and Hg(2+), respectively, for liver and 35.3 ng g(-1) and 58.1 ng g(-1) for CH(3)Hg(+) and Hg(2+), respectively, for kidney. These limits of detection are 5.5 and 6 times better than the obtained without solid phase microextraction for CH(3)Hg(+) and Hg(2+), respectively. The methodology was found linear up to 120 μg L(-1) and reproducible from one day to the following. It was validated with certified reference materials NCS ZC 71001 (beef liver) and BCR No 186 (pig kidney) for total mercury, calculated as the sum of species, and with spiked red deer liver and kidney for speciation. Finally, it was applied to the analysis of samples of red deer liver, red deer kidney and wild boar kidney coming from the Almadén's mercury mining area (Ciudad Real, Spain), the longest and largest producer of mercury in the world until its closure in 2002. PMID:22967634

  11. Estimation of Nonpoint-Source Loads of Total Nitrogen, Total Phosphorous, and Total Suspended Solids in the Black, Belle, and Pine River Basins, Michigan, by Use of the PLOAD Model

    USGS Publications Warehouse

    Syed, Atiq U.; Jodoin, Richard S.

    2006-01-01

    The Lake St. Clair Regional Monitoring Project partners planned a 3-year assessment study of the surface water in the Lake St. Clair drainage basins in Michigan. This study included water-quality monitoring and analysis, collection of discrete (grab) and automatic water-quality samples, moni-toring of bacteria, and the creation of a database to store all relevant data collected from past and future field-data-collec-tion programs. In cooperation with the Lake St. Clair Monitoring Project, the U.S. Geological Survey assessed nonpoint-source loads of nutrients and total suspended solids in the Black, Belle, and Pine River basins. The principal tool for the assess-ment study was the USEPA's PLOAD model, a simplified GIS-based numerical program that generates gross estimates of pollutant loads. In this study, annual loads were computed for each watershed using the USEPA's Simple Method, which is based on scientific studies showing a correlation between different land-use types and loading rates. The two land-use data sets used in the study (representing 1992 and 2001) show a maximum of 0.02-percent change in any of the 15 land use categories between the two timeframes. This small change in land use is reflected in the PLOAD results of the study area between the two time periods. PLOAD model results for the 2001 land-use data include total-nitrogen loads from the Black, Belle, and Pine River basins of approximately 495,599 lb/yr, 156,561 lb/yr, and 121,212 lb/yr, respectively; total-phosphorus loads of 80,777 lb/yr, 25,493 lb/yr, and 19,655 lb/yr, respectively; and total-sus-pended-solids loads of 5,613,282 lb/yr, 1,831,045 lb/yr, and 1,480,352 lb/yr, respectively. The subbasins in the Black, Belle, and Pine River basin with comparatively high loads are characterized by comparatively high percentages of industrial, commercial, transportation, or residential land use. The results from the PLOAD model provide useful information about the approximate average annual loading

  12. Formation of nanocolloidal metacinnabar in mercury-DOM-sulfide systems

    USGS Publications Warehouse

    Gerbig, C.A.; Kim, C.S.; Stegemeier, J.P.; Ryan, J.N.; Aiken, G.R.

    2011-01-01

    Direct determination of mercury (Hg) speciation in sulfide-containing environments is confounded by low mercury concentrations and poor analytical sensitivity. Here we report the results of experiments designed to assess mercury speciation at environmentally relevant ratios of mercury to dissolved organic matter (DOM) (i.e., <4 nmol Hg (mg DOM)-1) by combining solid phase extraction using C18 resin with extended X-ray absorption fine structure (EXAFS) spectroscopy. Aqueous Hg(II) and a DOM isolate were equilibrated in the presence and absence of 100 ??M total sulfide. In the absence of sulfide, mercury adsorption to the resin increased as the Hg:DOM ratio decreased and as the strength of Hg-DOM binding increased. EXAFS analysis indicated that in the absence of sulfide, mercury bonds with an average of 2.4 ?? 0.2 sulfur atoms with a bond length typical of mercury-organic thiol ligands (2.35 ??). In the presence of sulfide, mercury showed greater affinity for the C18 resin, and its chromatographic behavior was independent of Hg:DOM ratio. EXAFS analysis showed mercury-sulfur bonds with a longer interatomic distance (2.51-2.53 ??) similar to the mercury-sulfur bond distance in metacinnabar (2.53 ??) regardless of the Hg:DOM ratio. For all samples containing sulfide, the sulfur coordination number was below the ideal four-coordinate structure of metacinnabar. At a low Hg:DOM ratio where strong binding DOM sites may control mercury speciation (1.9 nmol mg -1) mercury was coordinated by 2.3 ?? 0.2 sulfur atoms, and the coordination number rose with increasing Hg:DOM ratio. The less-than-ideal coordination numbers indicate metacinnabar-like species on the nanometer scale, and the positive correlation between Hg:DOM ratio and sulfur coordination number suggests progressively increasing particle size or crystalline order with increasing abundance of mercury with respect to DOM. In DOM-containing sulfidic systems nanocolloidal metacinnabar-like species may form, and these

  13. Fate of mercury collected from air pollution control devices

    SciTech Connect

    Constance L. Senior; Susan Thorneloe; Bernine Khan; David Goss

    2009-07-15

    Mercury that enters a coal-fired power plant originates from the coal that is burned and leaves through the output streams, which include stack emissions and air pollution control (APC) residues (either in solid or liquid form). This article describes recent findings on the fate and environmental stability of mercury in coal combustion residues (CCRs) such as fly ash and solid products from flue gas desulfurization (FGD) scrubbers when either disposed or reused in agricultural, commercial, or engineering applications. 19 refs., 4 figs., 5 tabs.

  14. Mercury in the Grand Calumet River/Indiana Harbor Canal and Lake Michigan, Lake County, Indiana, August 2001 and May 2002

    USGS Publications Warehouse

    Risch, Martin R.

    2005-01-01

    Data from this study have implications for a Total Maximum Daily Load (TMDL) for mercury in the Grand Calumet River/Indiana Harbor Canal. Comparisons of data from this study with historical data do not show substantial changes in the distribution of mercury in the study area from 1994 through 2002. Treated municipal effluent had larger mercury concentrations than industrial effluent and presents a potential for larger mercury loads that could be controlled to achieve a TMDL, based on concentration. Mercury in ground-water discharge may be difficult to control to achieve a TMDL because of its diffuse and widespread distribution.

  15. Mercury in the ecosystem

    SciTech Connect

    Mitra, S.

    1986-01-01

    This treatise on the environmental dispersion of mercury emphasizes the importance of ''mercury-consciousness'' in the present-day world, where rapidly expanding metallurgical, chemical, and other industrial developments are causing widespread contamination of the atmosphere, soil, and water by this metal and its toxic organic derivatives. Concepts concerning the mechanism of mercury dispersion and methyl-mercury formation in the physico-biological ecosystem are discussed in detail and a substantial body of data on the degree and nature of the mercury contamination of various plants, fish, and land animals by industrial and urban effluents is presented. Various analytical methods for the estimation of mercury in inorganic and organic samples are presented. These serve as a ready guide to the selection of the correct method for analyzing environmental samples. This book is reference work in mercury-related studies. It is written to influence industrial policies of governments in their formulation of control measures to avoid the recurrence of human tragedies such as the well-known Minamata case in Japan, and the lesser known cases in Iraq, Pakistan, and Guatamala.

  16. Mercury's Dynamic Magnetic Tail

    NASA Technical Reports Server (NTRS)

    Slavin, James A.

    2010-01-01

    The Mariner 10 and MESSENGER flybys of Mercury have revealed a magnetosphere that is likely the most responsive to upstream interplanetary conditions of any in the solar system. The source of the great dynamic variability observed during these brief passages is due to Mercury's proximity to the Sun and the inverse proportionality between reconnection rate and solar wind Alfven Mach number. However, this planet's lack of an ionosphere and its small physical dimensions also contribute to Mercury's very brief Dungey cycle, approx. 2 min, which governs the time scale for internal plasma circulation. Current observations and understanding of the structure and dynamics of Mercury's magnetotail are summarized and discussed. Special emphasis will be placed upon such questions as: 1) How much access does the solar wind have to this small magnetosphere as a function of upstream conditions? 2) What roles do heavy planetary ions play? 3) Do Earth-like substorms take place at Mercury? 4) How does Mercury's tail respond to extreme solar wind events such coronal mass ejections? Prospects for progress due to advances in the global magnetohydrodynamic and hybrid simulation modeling and the measurements to be taken by MESSENGER after it enters Mercury orbit on March 18, 2011 will be discussed.

  17. Mercury Metadata Toolset

    SciTech Connect

    2009-09-08

    Mercury is a federated metadata harvesting, search and retrieval tool based on both open source software and software developed at Oak Ridge National Laboratory. It was originally developed for NASA, and the Mercury development consortium now includes funding from NASA, USGS, and DOE. A major new version of Mercury (version 3.0) was developed during 2007 and released in early 2008. This Mercury 3.0 version provides orders of magnitude improvements in search speed, support for additional metadata formats, integration with Google Maps for spatial queries, facetted type search, support for RSS delivery of search results, and ready customization to meet the needs of the multiple projects which use Mercury. For the end users, Mercury provides a single portal to very quickly search for data and information contained in disparate data management systems. It collects metadata and key data from contributing project servers distributed around the world and builds a centralized index. The Mercury search interfaces then allow the users to perform simple, fielded, spatial, and temporal searches across these metadata sources. This centralized repository of metadata with distributed data sources provides extremely fast search results to the user, while allowing data providers to advertise the availability of their data and maintain complete control and ownership of that data.

  18. Mercury Metadata Toolset

    2009-09-08

    Mercury is a federated metadata harvesting, search and retrieval tool based on both open source software and software developed at Oak Ridge National Laboratory. It was originally developed for NASA, and the Mercury development consortium now includes funding from NASA, USGS, and DOE. A major new version of Mercury (version 3.0) was developed during 2007 and released in early 2008. This Mercury 3.0 version provides orders of magnitude improvements in search speed, support for additionalmore » metadata formats, integration with Google Maps for spatial queries, facetted type search, support for RSS delivery of search results, and ready customization to meet the needs of the multiple projects which use Mercury. For the end users, Mercury provides a single portal to very quickly search for data and information contained in disparate data management systems. It collects metadata and key data from contributing project servers distributed around the world and builds a centralized index. The Mercury search interfaces then allow the users to perform simple, fielded, spatial, and temporal searches across these metadata sources. This centralized repository of metadata with distributed data sources provides extremely fast search results to the user, while allowing data providers to advertise the availability of their data and maintain complete control and ownership of that data.« less

  19. Fate and aqueous transport of mercury in light of the Clean Air Mercury Rule for coal-fired electric power plants

    NASA Astrophysics Data System (ADS)

    Arzuman, Anry

    Mercury is a hazardous air pollutant emitted to the atmosphere in large amounts. Mercury emissions from electric power generation sources were estimated to be 48 metric tons/year, constituting the single largest anthropogenic source of mercury in the U.S. Settled mercury species are highly toxic contaminants of the environment. The newly issued Federal Clean Air Mercury Rule requires that the electric power plants firing coal meet the new Maximum Achievable Mercury Control Technology limit by 2018. This signifies that all of the air-phase mercury will be concentrated in solid phase which, based on the current state of the Air Pollution Control Technology, will be fly ash. Fly ash is utilized by different industries including construction industry in concrete, its products, road bases, structural fills, monifills, for solidification, stabilization, etc. Since the increase in coal combustion in the U.S. (1.6 percent/year) is much higher than the fly ash demand, large amounts of fly ash containing mercury and other trace elements are expected to accumulate in the next decades. The amount of mercury transferred from one phase to another is not a linear function of coal combustion or ash production, depends on the future states of technology, and is unknown. The amount of aqueous mercury as a function of the future removal, mercury speciation, and coal and aquifer characteristics is also unknown. This paper makes a first attempt to relate mercury concentrations in coal, flue gas, fly ash, and fly ash leachate using a single algorithm. Mercury concentrations in all phases were examined and phase transformation algorithms were derived in a form suitable for probabilistic analyses. Such important parameters used in the transformation algorithms as Soil Cation Exchange Capacity for mercury, soil mercury selectivity sequence, mercury activity coefficient, mercury retardation factor, mercury species soil adsorption ratio, and mercury Freundlich soil adsorption isotherm

  20. Inorganic: the other mercury.

    PubMed

    Risher, John F; De Rosa, Christopher T

    2007-11-01

    There is a broad array of mercury species to which humans may be exposed. While exposure to methylmercury through fish consumption is widely recognized, the public is less aware of the sources and potential toxicity of inorganic forms of mercury. Some oral and laboratory thermometers, barometers, small batteries, thermostats, gas pressure regulators, light switches, dental amalgam fillings, cosmetic products, medications, cultural/religious practices, and gold mining all represent potential sources of exposure to inorganic forms of mercury. The route of exposure, the extent of absorption, the pharmacokinetics, and the effects all vary with the specific form of mercury and the magnitude and duration of exposure. If exposure is suspected, a number of tissue analyses can be conducted to confirm exposure or to determine whether an exposure might reasonably be expected to be biologically significant. By contrast with determination of exposure to methylmercury, for which hair and blood are credible indicators, urine is the preferred biological medium for the determination of exposure to inorganic mercury, including elemental mercury, with blood normally being of value only if exposure is ongoing. Although treatments are available to help rid the body of mercury in cases of extreme exposure, prevention of exposure will make such treatments unnecessary. Knowing the sources of mercury and avoiding unnecessary exposure are the prudent ways of preventing mercury intoxication. When exposure occurs, it should be kept in mind that not all unwanted exposures will result in adverse health consequences. In all cases, elimination of the source of exposure should be the first priority of public health officials.

  1. Inorganic: the other mercury.

    PubMed

    Risher, John F; De Rosa, Christopher T

    2007-11-01

    There is a broad array of mercury species to which humans may be exposed. While exposure to methylmercury through fish consumption is widely recognized, the public is less aware of the sources and potential toxicity of inorganic forms of mercury. Some oral and laboratory thermometers, barometers, small batteries, thermostats, gas pressure regulators, light switches, dental amalgam fillings, cosmetic products, medications, cultural/religious practices, and gold mining all represent potential sources of exposure to inorganic forms of mercury. The route of exposure, the extent of absorption, the pharmacokinetics, and the effects all vary with the specific form of mercury and the magnitude and duration of exposure. If exposure is suspected, a number of tissue analyses can be conducted to confirm exposure or to determine whether an exposure might reasonably be expected to be biologically significant. By contrast with determination of exposure to methylmercury, for which hair and blood are credible indicators, urine is the preferred biological medium for the determination of exposure to inorganic mercury, including elemental mercury, with blood normally being of value only if exposure is ongoing. Although treatments are available to help rid the body of mercury in cases of extreme exposure, prevention of exposure will make such treatments unnecessary. Knowing the sources of mercury and avoiding unnecessary exposure are the prudent ways of preventing mercury intoxication. When exposure occurs, it should be kept in mind that not all unwanted exposures will result in adverse health consequences. In all cases, elimination of the source of exposure should be the first priority of public health officials. PMID:18044248

  2. Effect of the organic loading rate on the performance of anaerobic acidogenic fermentation of two-phase olive mill solid residue.

    PubMed

    Rincón, B; Sánchez, E; Raposo, F; Borja, R; Travieso, L; Martín, M A; Martín, A

    2008-01-01

    A study of the effect of the organic loading rate (OLR) on the anaerobic acidogenic fermentation of two-phase olive mill solid residue (OMSR) derived from fruits with a low ripening index was carried out in a laboratory-scale completely stirred tank reactor at mesophilic temperature (35 degrees C). Eight experimental runs were carried out at OLRs of 3.2, 5.6, 7.4, 9.6, 11.0, 12.9, 14.0 and 15.1g T-COD/ld, which were equivalent to hydraulic retention times of 50.0, 28.8, 21.8, 16.9, 14.7, 12.4, 11.5 and 10.7d, respectively. The experimental results obtained demonstrated that the optimum value of OLR for the acidogenic fermentation process was 12.9 g T-COD/ld, for which a maximum production of acetic acid was achieved. It was found that inhibition of the process occurred at OLRs higher than 12.9 g T-COD/ld. This was characterized by a significant decrease in the acetic acid concentration in the effluent and an increase in the concentration of other volatile acids that may affect the methanogenic step. The process inhibition was also characterized by the plateau in the curves of the effluent substrate concentration versus the OLR applied. It was found that a first-order kinetics satisfactorily described the influence of non-acetic acid soluble organic matter concentration (S-COD( *)) on the rate of soluble organic matter conversion to acetic acid (R(S-COD)( *)), and the influence of acetic acid concentration (AcH) on the rate of acetic acid production (R(AcH)), while a potential equation type adequately described the influence of acetic acid concentration on the volumetric hydrogen production (R(ACH) ). The kinetic constant for soluble organic matter removal was 0.145 d(-1), while the constant for acetic acid formation was found to be 0.075 d(-1).

  3. Global change and mercury

    USGS Publications Warehouse

    Krabbenhoft, David P.; Sunderland, Elsie M.

    2013-01-01

    More than 140 nations recently agreed to a legally binding treaty on reductions in human uses and releases of mercury that will be signed in October of this year. This follows the 2011 rule in the United States that for the first time regulates mercury emissions from electricity-generating utilities. Several decades of scientific research preceded these important regulations. However, the impacts of global change on environmental mercury concentrations and human exposures remain a major uncertainty affecting the potential effectiveness of regulatory activities.

  4. Mercury free microscopy: an opportunity for core facility directors.

    PubMed

    Baird, T Regan; Kaufman, Daniel; Brown, Claire M

    2014-07-01

    Mercury Free Microscopy (MFM) is a new movement that encourages microscope owners to choose modern mercury free light sources to replace more traditional mercury based arc lamps. Microscope performance is enhanced with new solid state technologies because they offer a more stable light intensity output and have a more uniform light output across the visible spectrum. Solid state sources not only eliminate mercury but also eliminate the cost of consumable bulbs (lifetime ∼200 hours), use less energy, reduce the instrument down time when bulbs fail and reduce the staff time required to replace and align bulbs. With lifetimes on the order of tens of thousands of hours, solid state replacements can pay for themselves over their lifetime with the omission of consumable, staff (no need to replace and align bulbs) and energy costs. Solid state sources are also sustainable and comply with institutional and government body mandates to reduce energy consumption, carbon footprints and hazardous waste. MFM can be used as a mechanism to access institutional financial resources for sustainable technology through a variety of stakeholders to defray the cost to microscope owners for the initial purchase of solid state sources or the replacement cost of mercury based sources. Core facility managers can take a lead in this area as "green" ambassadors for their institution by championing a local MFM program that will save their institution money and energy and eliminate mercury from the waste stream. Managers can leverage MFM to increase the visibility of their facility, their impact within the institution, and as a vital educational resource for scientific and administrative consultation. PMID:24982596

  5. MERCURY CONTROL WITH ADVANCED HYBRID PARTICULATE COLLECTOR

    SciTech Connect

    Ye Zhuang; Stanley J. Miller

    2005-05-01

    This project was awarded under U.S. Department of Energy (DOE) National Energy Technology Laboratory (NETL) Program Solicitation DE-PS26-00NT40769 and specifically addressed Technical Topical Area 4-Testing Novel and Less Mature Control Technologies on Actual Flue Gas at the Pilot Scale. The project team included the Energy & Environmental Research Center (EERC) as the main contractor; W.L. Gore & Associates, Inc., as a technical and financial partner; and the Big Stone Power Plant operated by Otter Tail Power Company, host for the field-testing portion of the research. Since 1995, DOE has supported development of a new concept in particulate control called the advanced hybrid particulate collector (AHPC). The AHPC has been licensed to W.L. Gore & Associates, Inc., and has been marketed as the Advanced Hybrid{trademark} filter by Gore. The Advanced Hybrid{trademark} filter combines the best features of electrostatic precipitators (ESPs) and baghouses in a unique configuration, providing major synergism between the two collection methods, both in the particulate collection step and in the transfer of dust to the hopper. The Advanced Hybrid{trademark} filter provides ultrahigh collection efficiency, overcoming the problem of excessive fine-particle emissions with conventional ESPs, and it solves the problem of reentrainment and re-collection of dust in conventional baghouses. The Advanced Hybrid{trademark} filter also appears to have unique advantages for mercury control over baghouses or ESPs as an excellent gas--solid contactor. The objective of the project was to demonstrate 90% total mercury control in the Advanced Hybrid{trademark} filter at a lower cost than current mercury control estimates. The approach included bench-scale batch tests, larger-scale pilot testing with real flue gas on a coal-fired combustion system, and field demonstration at the 2.5-MW (9000-acfm) scale at a utility power plant to prove scale-up and demonstrate longer-term mercury control

  6. Recovery of mercury from mercury compounds via electrolytic methods

    DOEpatents

    Grossman, Mark W.; George, William A.

    1989-01-01

    A process for electrolytically recovering mercury from mercury compounds is provided. In one embodiment, Hg is recovered from Hg.sub.2 Cl.sub.2 employing as the electrolyte solution a mixture of HCl and H.sub.2 O. In another embodiment, Hg is electrolytically recovered from HgO wherein the electrolyte solution is comprised of glacial acetic acid and H.sub.2 O. Also provided is an apparatus for producing isotopically enriched mercury compounds in a reactor and then transporting the dissolved compounds into an electrolytic cell where mercury ions are electrolytically reduced and elemental mercury recovered from the mercury compounds.

  7. Recovery of mercury from mercury compounds via electrolytic methods

    DOEpatents

    Grossman, Mark W.; George, William A.

    1988-01-01

    A process for electrolytically recovering mercury from mercury compounds is provided. In one embodiment, Hg is recovered from Hg.sub.2 Cl.sub.2 employing as the electrolyte solution a mixture of HCl and H.sub.2 O. In another embodiment, Hg is electrolytically recovered from HgO wherein the electrolyte solution is comprised of glacial acetic acid and H.sub.2 O. Also provided is an apparatus for producing isotopically enriched mercury compounds in a reactor and then transporting the dissolved compounds into an electrolytic cell where mercury ions are electrolytically reduced and elemental mercury recovered from the mercury compounds.

  8. Recovery of mercury from mercury compounds via electrolytic methods

    DOEpatents

    Grossman, M.W.; George, W.A.

    1991-06-18

    A process for electrolytically recovering mercury from mercury compounds is provided. In one embodiment, Hg is recovered from Hg[sub 2]Cl[sub 2] employing as the electrolyte solution a mixture of HCl and H[sub 2]O. In another embodiment, Hg is electrolytically recovered from HgO wherein the electrolyte solution is comprised of glacial acetic acid and H[sub 2]O. Also provided is an apparatus for producing isotopically enriched mercury compounds in a reactor and then transporting the dissolved compounds into an electrolytic cell where mercury ions are electrolytically reduced and elemental mercury recovered from the mercury compounds. 3 figures.

  9. Recovery of mercury from mercury compounds via electrolytic methods

    DOEpatents

    Grossman, M.W.; George, W.A.

    1989-11-07

    A process for electrolytically recovering mercury from mercury compounds is provided. In one embodiment, Hg is recovered from Hg[sub 2]Cl[sub 2] employing as the electrolyte solution a mixture of HCl and H[sub 2]O. In another embodiment, Hg is electrolytically recovered from HgO wherein the electrolyte solution is comprised of glacial acetic acid and H[sub 2]O. Also provided is an apparatus for producing isotopically enriched mercury compounds in a reactor and then transporting the dissolved compounds into an electrolytic cell where mercury ions are electrolytically reduced and elemental mercury recovered from the mercury compounds. 3 figs.

  10. Recovery of mercury from mercury compounds via electrolytic methods

    DOEpatents

    Grossman, Mark W.; George, William A.

    1991-01-01

    A process for electrolytically recovering mercury from mercury compounds is provided. In one embodiment, Hg is recovered from Hg.sub.2 Cl.sub.2 employing as the electrolyte solution a mixture of HCl and H.sub.2 O. In another embodiment, Hg is electrolytically recovered from HgO wherein the electrolyte solution is comprised of glacial acetic acid and H.sub.2 O. Also provided is an apparatus for producing isotopically enriched mercury compounds in a reactor and then transporting the dissolved compounds into an electrolytic cell where mercury ions are electrolytically reduced and elemental mercury recovered from the mercury compounds.

  11. Mercury exposure and children's health.

    PubMed

    Bose-O'Reilly, Stephan; McCarty, Kathleen M; Steckling, Nadine; Lettmeier, Beate

    2010-09-01

    Acute or chronic mercury exposure can cause adverse effects during any period of development. Mercury is a highly toxic element; there is no known safe level of exposure. Ideally, neither children nor adults should have any mercury in their bodies because it provides no physiological benefit. Prenatal and postnatal mercury exposures occur frequently in many different ways. Pediatricians, nurses, and other health care providers should understand the scope of mercury exposures and health problems among children and be prepared to handle mercury exposures in medical practice. Prevention is the key to reducing mercury poisoning. Mercury exists in different chemical forms: elemental (or metallic), inorganic, and organic (methylmercury and ethyl mercury). Mercury exposure can cause acute and chronic intoxication at low levels of exposure. Mercury is neuro-, nephro-, and immunotoxic. The development of the child in utero and early in life is at particular risk. Mercury is ubiquitous and persistent. Mercury is a global pollutant, bio-accumulating, mainly through the aquatic food chain, resulting in a serious health hazard for children. This article provides an extensive review of mercury exposure and children's health.

  12. Mercury cycling in terrestrial watersheds

    USGS Publications Warehouse

    Shanley, James B.; Bishop, Kevin; Banks, Michael S.

    2012-01-01

    This chapter discusses mercury cycling in the terrestrial landscape, including inputs from the atmosphere, accumulation in soils and vegetation, outputs in streamflow and volatilization, and effects of land disturbance. Mercury mobility in the terrestrial landscape is strongly controlled by organic matter. About 90% of the atmospheric mercury input is retained in vegetation and organic matter in soils, causing a buildup of legacy mercury. Some mercury is volatilized back to the atmosphere, but most export of mercury from watersheds occurs by streamflow. Stream mercury export is episodic, in association with dissolved and particulate organic carbon, as stormflow and snowmelt flush organic-rich shallow soil horizons. The terrestrial landscape is thus a major source of mercury to downstream aquatic environments, where mercury is methylated and enters the aquatic food web. With ample organic matter and sulfur, methylmercury forms in uplands as well—in wetlands, riparian zones, and other anoxic sites. Watershed features (topography, land cover type, and soil drainage class) are often more important than atmospheric mercury deposition in controlling the amount of stream mercury and methylmercury export. While reductions in atmospheric mercury deposition may rapidly benefit lakes, the terrestrial landscape will respond only over decades, because of the large stock and slow turnover of legacy mercury. We conclude with a discussion of future scenarios and the challenge of managing terrestrial mercury.

  13. Removal of mercury from stack gases by activated carbon

    SciTech Connect

    Vidic, R.D.

    1995-10-01

    On combustion, the trace elements in the incinerator feed stream are partitioned between the bottom ash (slag) stream, and a flue gas stream containing suspended fly ash and vapors of volatile elements or compounds. A further partitioning of the flue gas stream takes place in the particulate emission control devices that efficiently remove larger fly ash particles but are less efficient for vapors and finer particles. Environmental control agencies, researchers, and general public have become increasingly concerned with the mobilization of trace elements to the environment from solid and hazardous waste incinerators. Mercury is the trace element of particular concern since, during combustion, most of the mercury present in the influent stream is transferred into the vapor phase due to its high volatility. There is a considerable evidence in the literature that currently used pollution abatement technologies (flue gas clean-up and particulate control devices) are not capable of controlling gas phase mercury emissions. Activated carbon adsorption is a unit process that offers great promise for achieving high quality air emissions with respect to mercury and other trace elements that might be present in gases emitted from solid and hazardous waste incinerators. This study is designed to evaluate the rate of vapor-phase mercury removal by virgin and sulfur impregnated activated carbons under various process conditions. The specific process conditions that will be evaluated for their effect on the rate and mechanism of mercury uptake include temperature, moisture content, oxygen partial pressure, and presence of other compounds and trace elements in the vapor-phase. Accurate description of the kinetics of mercury removal by activated carbon is an essential component in establishing design procedures that would ensure successful application of this efficient technology for mercury control.

  14. Ecosystem conceptual model- Mercury

    USGS Publications Warehouse

    Alpers, Charles N.; Eagles-Smith, Collin A.; Foe, Chris; Klasing, Susan; Marvin-DiPasquale, Mark C.; Slotton, Darell G.; Windham-Myers, Lisamarie

    2008-01-01

    Mercury has been identified as an important contaminant in the Delta, based on elevated concentrations of methylmercury (a toxic, organic form that readily bioaccumulates) in fish and wildlife. There are health risks associated with human exposure to methylmercury by consumption of sport fish, particularly top predators such as bass species. Original mercury sources were upstream tributaries where historical mining of mercury in the Coast Ranges and gold in the Sierra Nevada and Klamath-Trinity Mountains caused contamination of water and sediment on a regional scale. Remediation of abandoned mine sites may reduce local sources in these watersheds, but much of the mercury contamination occurs in sediments stored in the riverbeds, floodplains, and the Bay- Delta, where scouring of Gold-Rush-era sediment represents an ongoing source.Conversion of inorganic mercury to toxic methylmercury occurs in anaerobic environments including some wetlands. Wetland restoration managers must be cognizant of potential effects on mercury cycling so that the problem is not exacerbated. Recent research suggests that wettingdrying cycles can contribute to mercury methylation. For example, high marshes (inundated only during the highest tides for several days per month) tend to have higher methylmercury concentrations in water, sediment, and biota compared with low marshes, which do not dry out completely during the tidal cycle. Seasonally inundated flood plains are another environment experiencing wetting and drying where methylmercury concentrations are typically elevated. Stream restoration efforts using gravel injection or other reworking of coarse sediment in most watersheds of the Central Valley involve tailings from historical gold mining that are likely to contain elevated mercury in associated fines. Habitat restoration projects, particularly those involving wetlands, may cause increases in methylmercury exposure in the watershed. This possibility should be evaluated.The DRERIP

  15. A Mass Balance for Mercury in the San Francisco Bay Area

    SciTech Connect

    MacLeod, Matthew; McKone, Thomas E.; Mackay, Don

    2005-06-01

    We develop and illustrate a general regional multi-species model that describes the fate and transport of mercury in three forms, elemental, divalent, and methylated, in a generic regional environment including air, soil, vegetation, water and sediment. The objectives of the model are to describe the fate of the three forms of mercury in the environment and determine the dominant physical sinks that remove mercury from the system. Chemical transformations between the three groups of mercury species are modeled by assuming constant ratios of species concentrations in individual environmental media. They illustrate and evaluate the model with an application to describe the fate and transport of mercury in the San Francisco Bay Area of California. The model successfully rationalizes the identified sources with observed concentrations of total mercury and methyl mercury in the San Francisco Bay Estuary. The mass balance provided by the model indicates that continental and global background sources control mercury concentrations in the atmosphere but loadings to water in the San Francisco Bay estuary are dominated by runoff from the Central Valley catchment and re-mobilization of contaminated sediments deposited during past mining activities. The model suggests that the response time of mercury concentrations in the San Francisco Bay estuary to changes in loadings is long, of the order of 50 years.

  16. Mercury CEM Calibration

    SciTech Connect

    John F. Schabron; Joseph F. Rovani; Susan S. Sorini

    2007-03-31

    The Clean Air Mercury Rule (CAMR) which was published in the Federal Register on May 18, 2005, requires that calibration of mercury continuous emissions monitors (CEMs) be performed with NIST-traceable standards. Western Research Institute (WRI) is working closely with the Electric Power Research Institute (EPRI), the National Institute of Standards and Technology (NIST), and the Environmental Protection Agency (EPA) to facilitate the development of the experimental criteria for a NIST traceability protocol for dynamic elemental mercury vapor generators. The traceability protocol will be written by EPA. Traceability will be based on the actual analysis of the output of each calibration unit at several concentration levels ranging from about 2-40 ug/m{sup 3}, and this analysis will be directly traceable to analyses by NIST using isotope dilution inductively coupled plasma/mass spectrometry (ID ICP/MS) through a chain of analyses linking the calibration unit in the power plant to the NIST ID ICP/MS. Prior to this project, NIST did not provide a recommended mercury vapor pressure equation or list mercury vapor pressure in its vapor pressure database. The NIST Physical and Chemical Properties Division in Boulder, Colorado was subcontracted under this project to study the issue in detail and to recommend a mercury vapor pressure equation that the vendors of mercury vapor pressure calibration units can use to calculate the elemental mercury vapor concentration in an equilibrium chamber at a particular temperature. As part of this study, a preliminary evaluation of calibration units from five vendors was made. The work was performed by NIST in Gaithersburg, MD and Joe Rovani from WRI who traveled to NIST as a Visiting Scientist.

  17. To Mercury dynamics

    NASA Astrophysics Data System (ADS)

    Barkin, Yu. V.; Ferrandiz, J. M.

    Present significance of the study of rotation of Mercury considered as a core-mantle system arises from planned Mercury missions. New high accurate data on Mercury's structure and its physical fields are expected from BepiColombo mission (Anselmi et al., 2001). Investigation of resonant rotation of Mercury, begun by Colombo G. (1966), will play here main part. New approaches to the study of Mercury dynamics and the construction of analytical theory of its resonant rotation are suggested. Within these approaches Mercury is considered as a system of two non-spherical interacting bodies: a core and a mantle. The mantle of Mercury is considered as non-spherical, rigid (or elastic) layer. Inner shell is a liquid core, which occupies a large ellipsoidal cavity of Mercury. This Mercury system moves in the gravitational field of the Sun in resonant traslatory-rotary regime of the resonance 3:2. We take into account only the second harmonic of the force function of the Sun and Mercury. For the study of Mercury rotation we have been used specially designed canonical equations of motion in Andoyer and Poincare variables (Barkin, Ferrandiz, 2001), more convenient for the application of mentioned methods. Approximate observational and some theoretical evaluations of the two main coefficients of Mercury gravitational field J_2 and C22 are known. From observational data of Mariner-10 mission were obtained some first evaluations of these coefficients: J_2 =(8± 6)\\cdot 10-5(Esposito et al., 1977); J_2 =(6± 2)\\cdot 10-5and C22 =(1.0± 0.5)\\cdot 10-5(Anderson et al., 1987). Some theoretical evaluation of ratio of these coefficients has been obtained on the base of study of periodic motions of the system of two non-spherical gravitating bodies (Barkin, 1976). Corresponding values of coefficients consist: J_2 =8\\cdot 10-5and C22 =0.33\\cdot 10-5. We have no data about non-sphericity of inner core of Mercury. Planned missions to Mercury (BepiColombo and Messenger) promise to

  18. [Environmental effects of mercury around a large scale MSW incineration plant].

    PubMed

    Tang, Qing-he; Ding, Zhen-hua; Jiang, Jia-hua; Yang, Wen-hua; Cheng, Jin-ping; Wang, Wen-hua

    2005-01-01

    Samples of soil, vegetables, crops and air collected from Yuqiao Incineration Paint, Pudong Shanghai, were analyzed with an AMA-254 liquid/solid mercury analyzer. It is shown that background levels(BLs,2001) of mercury in surface soil is a little higher, mercury content in soils one year after operation(2002) and two year(2003) were both higher than BLs. The levels of mercury in vegetables is higher than Standard levels (GB 2762-94), the content of mercury in Soya and broomcorn sampled in 2003 was 2.3 and 2.7 times than that in 2002. Atmospheric mercury levels were 10.1, 5.0 and 10.6 ng/m3 in up-site,site and down-site.

  19. Method and apparatus for monitoring mercury emissions

    DOEpatents

    Durham, Michael D.; Schlager, Richard J.; Sappey, Andrew D.; Sagan, Francis J.; Marmaro, Roger W.; Wilson, Kevin G.

    1997-01-01

    A mercury monitoring device that continuously monitors the total mercury concentration in a gas. The device uses the same chamber for converting speciated mercury into elemental mercury and for measurement of the mercury in the chamber by radiation absorption techniques. The interior of the chamber is resistant to the absorption of speciated and elemental mercury at the operating temperature of the chamber.

  20. Method and apparatus for monitoring mercury emissions

    DOEpatents

    Durham, M.D.; Schlager, R.J.; Sappey, A.D.; Sagan, F.J.; Marmaro, R.W.; Wilson, K.G.

    1997-10-21

    A mercury monitoring device that continuously monitors the total mercury concentration in a gas. The device uses the same chamber for converting speciated mercury into elemental mercury and for measurement of the mercury in the chamber by radiation absorption techniques. The interior of the chamber is resistant to the absorption of speciated and elemental mercury at the operating temperature of the chamber. 15 figs.

  1. Mercury Exposure Levels in Children with Dental Amalgam Fillings

    PubMed Central

    Miriam Varkey, Indu; Shetty, Rajmohan; Hegde, Amitha

    2014-01-01

    ABSTRACT% Objectives: Mercury combined with other metals to form solid amalgams has long been used in reconstructive dentistry but its use has been controversial since at least the middle of the 19th century. The exposure and body burden of mercury reviews have consistently stated that there is a deficiency of adequate epidemiological studies addressing this issue. Fish and dental amalgam are two major sources of human exposure to organic (MeHg) and inorganic Hg respectively. Materials and methods: A total of 150 subjects aged between 9 and 14 years were divided into two groups of 75 subjects each depending on their diet, i.e. seafood or nonseafood consuming. Each category was subdivided into three groups based on number of restorations. Scalp hair and urine samples were collected at baseline and 3 months later to assess the organic and inorganic levels of mercury respectively by atomic absorption spectrophotometer (AAS). Results: The mean values of urinary mercury (inorganic mercury) in the group of children with restorations were 1.5915 μg/l as compared to 0.0130 μg/l in the groups with no amalgam restorations (p < 0.001) (Wilcoxon sign rank test and paired t-test). The hair mercury levels (organic mercury) varied signi-ficantly between the fsh-eating group and nonfsh-eating group, the average values being 1.03 μg/l and 0.84 μg/l respectively (p < 0.001) (Mann-Whitney U-test and paired t-test). Conclusion and significance: The notion about the mercury being released from the amalgam restorations as a sole exposure source needs to be put to a rest, as environmental factors collectively overpower the exposure levels from restorations alone. How to cite this article: Varkey IM, Shetty R, Hegde A. Mercury Exposure Levels in Children with Dental Amalgam Fillings. Int J Clin Pediatr Dent 2014;7(3):180-185. PMID:25709298

  2. Selective partitioning of mercury from co-extracted actinides in a simulated acidic ICPP waste stream

    SciTech Connect

    Brewer, K.N.; Herbst, R.S.; Tranter, T.J.

    1995-12-01

    The TRUEX process is being evaluated at the Idaho Chemical Processing Plant (ICPP) as a means to partition the actinides from acidic sodium-bearing waste (SBW). The mercury content of this waste averages 1 g/l. Because the chemistry of mercury has not been extensively evaluated in the TRUEX process, mercury was singled out as an element of interest. Radioactive mercury, {sup 203}Hg, was spiked into a simulated solution of SBW containing 1 g/l mercury. Successive extraction batch contacts with the mercury spiked waste simulant and successive scrubbing and stripping batch contacts of the mercury loaded TRUEX solvent (0.2 M CMPO-1.4 M TBP in dodecane) show that mercury will extract into and strip from the solvent. The extraction distribution coefficient for mercury, as HgCl{sub 2} from SBW having a nitric acid concentration of 1.4 M and a chloride concentration of 0.035 M was found to be 3. The stripping distribution coefficient was found to be 0.5 with 5 M HNO{sub 3} and 0.077 with 0.25 M Na{sub 2}CO{sub 3}. An experimental flowsheet was designed from the batch contact tests and tested counter-currently using 5.5 cm centrifugal contactors. Results from the counter-current test show that mercury can be removed from the acidic mixed SBW simulant and recovered separately from the actinides.

  3. Patterns of mercury deposition and concentration in northeastern North America (1996-2002).

    PubMed

    Vanarsdale, Alan; Weiss, Jeri; Keeler, Gerald; Miller, Eric; Boulet, Gille; Brulotte, Raynald; Poissant, Laurier

    2005-03-01

    Data from 13 National Atmospheric Deposition Program Mercury Monitor Network (NADP/ MDN) monitoring stations (1996-2002) and the Underhill (VT) event-based monitoring site (1993-2002) were evaluated for spatial and temporal trends. More precipitation and mercury deposition occurred in the southern and coastal MDN sites, except for the Underhill site, which received more mercury deposition than surrounding sites. Precipitation patterns varied. Regionally, higher concentrations of mercury were recorded during the late spring and summer months. Several sub-regional clusters of MDN sites were evident, based on mercury deposition patterns. In general, more mercury was deposited during the summer months. "Enhanced" weekly deposition (> 250 ng/m2) and distinct seasonal deposition patterns were evident at all MDN sites. Regionally, high depositional periods contributed significantly to annual loads (< 20%- approximately 60%). Southern and coastal sites measured more frequent periods of high deposition than inland sites. Spring and summer "enhanced" deposition may be important contributing factors to mercury bioaccumulation during the growing season. Recent regional reductions of mercury emissions were not reflected in the regional mercury concentration or deposition data. Few sites showed linear relations between the concentration of mercury in precipitation and acid rain co-contaminants (sulfates and nitrates).

  4. GEOCHEMICAL FACTORS GOVERNING METHYL MERCURY PRODUCTION IN MERCURY CONTAMINATED SEDIMENTS

    EPA Science Inventory

    Bench scale experiments were conducted to improve our understanding of aquatic mercury transformation processes (biotic and abiotic), specifically those factors which govern the production of methyl mercury (MeHg) in sedimentary environments. The greatest cause for concern regar...

  5. Mercury transformation and speciation in flue gases from anthropogenic emission sources: a critical review

    NASA Astrophysics Data System (ADS)

    Zhang, L.; Wang, S. X.; Wu, Q. R.; Wang, F. Y.; Lin, C.-J.; Zhang, L. M.; Hui, M. L.; Hao, J. M.

    2015-11-01

    Mercury transformation mechanisms and speciation profiles are reviewed for mercury formed in and released from flue gases of coal-fired boilers, non-ferrous metal smelters, cement plants, iron and steel plants, municipal solid waste incinerators, and biomass burning. Mercury in coal, ores and other raw materials is released to flue gases in the form of Hg0 during combustion or smelting in boilers, kilns or furnaces. Decreasing temperature from over 800 °C to below 300 °C in flue gases leaving boilers, kilns or furnaces promotes homogeneous and heterogeneous oxidation of gaseous elemental mercury (Hg0) to gaseous divalent mercury (Hg2+), with a portion of Hg2+ adsorbed onto fly ash to form particulate-bound mercury (Hgp). Halogen is the primary oxidizer for Hg0 in flue gases, and active components (e.g.,TiO2, Fe2O3, etc.) on fly ash promote heterogeneous oxidation and adsorption processes. In addition to mercury removal, mercury transformation also occurs when passing through air pollution control devices (APCDs), affecting the mercury speciation in flue gases. In coal-fired power plants, selective catalytic reduction (SCR) system promotes mercury oxidation by 34-85 %, electrostatic precipitator (ESP) and fabric filter (FF) remove over 99 % of Hgp, and wet flue gas desulfurization system (WFGD) captures 60-95 % of Hg2+. In non-ferrous metal smelters, most Hg0 is converted to Hg2+ and removed in acid plants (APs). For cement clinker production, mercury cycling and operational conditions promote heterogeneous mercury oxidation and adsorption. The mercury speciation profiles in flue gases emitted to the atmosphere are determined by transformation mechanisms and mercury removal efficiencies by various APCDs. For all the sectors reviewed in this study, Hgp accounts for less than 5 % in flue gases. In China, mercury emission has a higher fraction (66-82 % of total mercury) in flue gases from coal combustion, in contrast to a greater Hg2+ fraction (29-90 %) from non

  6. Mercury pollution in Malaysia.

    PubMed

    Hajeb, Parvaneh; Jinap, S; Ismail, Ahmad; Mahyudin, Nor Ainy

    2012-01-01

    Although several studies have been published on levels of mercury contamination of the environment, and of food and human tissues in Peninsular Malaysia, there is a serious dearth of research that has been performed in East Malaysia (Sabah and Sarawak). Industry is rapidly developing in East Malaysia, and, hence, there is a need for establishing baseline levels of mercury contamination in environmental media in that part of the country by performing monitoring studies. Residues of total mercury and inorganic in food samples have been determined in nearly all previous studies that have been conducted; however, few researchers have analyzed samples for the presence of methlymercury residues. Because methylmercury is the most toxic form of mercury, and because there is a growing public awareness of the risk posed by methylmercury exposure that is associated with fish and seafood consumption, further monitoring studies on methylmercury in food are also essential. From the results of previous studies, it is obvious that the economic development in Malaysia, in recent years, has affected the aquatic environment of the country. Primary areas of environmental concern are centered on the rivers of the west Peninsular Malaysian coast, and the coastal waters of the Straits of Malacca, wherein industrial activities are rapidly expanding. The sources of existing mercury input to both of these areas of Malaysia should be studied and identified. Considering the high levels of mercury that now exists in human tissues, efforts should be continued, and accelerated in the future, if possible, to monitor mercury contamination levels in the coastal states, and particularly along the west Peninsular Malaysian coast. Most studies that have been carried out on mercury residues in environmental samples are dated, having been conducted 20-30 years ago; therefore, the need to collect much more and more current data is urgent. Furthermore, establishing baseline levels of mercury exposure to

  7. Mercury pollution in Malaysia.

    PubMed

    Hajeb, Parvaneh; Jinap, S; Ismail, Ahmad; Mahyudin, Nor Ainy

    2012-01-01

    Although several studies have been published on levels of mercury contamination of the environment, and of food and human tissues in Peninsular Malaysia, there is a serious dearth of research that has been performed in East Malaysia (Sabah and Sarawak). Industry is rapidly developing in East Malaysia, and, hence, there is a need for establishing baseline levels of mercury contamination in environmental media in that part of the country by performing monitoring studies. Residues of total mercury and inorganic in food samples have been determined in nearly all previous studies that have been conducted; however, few researchers have analyzed samples for the presence of methlymercury residues. Because methylmercury is the most toxic form of mercury, and because there is a growing public awareness of the risk posed by methylmercury exposure that is associated with fish and seafood consumption, further monitoring studies on methylmercury in food are also essential. From the results of previous studies, it is obvious that the economic development in Malaysia, in recent years, has affected the aquatic environment of the country. Primary areas of environmental concern are centered on the rivers of the west Peninsular Malaysian coast, and the coastal waters of the Straits of Malacca, wherein industrial activities are rapidly expanding. The sources of existing mercury input to both of these areas of Malaysia should be studied and identified. Considering the high levels of mercury that now exists in human tissues, efforts should be continued, and accelerated in the future, if possible, to monitor mercury contamination levels in the coastal states, and particularly along the west Peninsular Malaysian coast. Most studies that have been carried out on mercury residues in environmental samples are dated, having been conducted 20-30 years ago; therefore, the need to collect much more and more current data is urgent. Furthermore, establishing baseline levels of mercury exposure to

  8. Comparison of a fuel-driven and steam-driven ejector in solid oxide fuel cell systems with anode off-gas recirculation: Part-load behavior

    NASA Astrophysics Data System (ADS)

    Engelbracht, Maximilian; Peters, Roland; Blum, Ludger; Stolten, Detlef

    2015-03-01

    This paper investigates the use of ejectors for recirculating anode off-gas in an SOFC system, focusing on the part-load capability of two different systems. In the first system, recirculation was enabled by a fuel-driven ejector. The part-load threshold of this system was determined by carbon formation and was 77.8% assuming a fuel utilization of 70% and suitable ejector geometry. The second system was based on a steam-driven ejector. The simulation results for this system showed an improved part-load capability of 37.8% as well as a slightly improved electrical efficiency. Here, the minimal part load was determined by the condensation temperature of the condenser used in the system.

  9. Insights into Mercury's interior structure from geodesy measurements

    NASA Astrophysics Data System (ADS)

    Rivoldini, A.; Van Hoolst, T.; Trinh, A.

    2013-09-01

    The measurements of the gravitational field of Mercury by MESSENGER [1] and improved measurements of the spin state of Mercury [2] provide important constraints on the interior structure of Mercury. In particular, these data give strong constraints on the radius and density of Mercury's core and on the core's concentration of sulfur if sulfur is the only light element in the core [3]. Although sulfur is ubiquitously invoked as being the principal candidate light element in terrestrial planet's cores its abundance in the core depends on the redox conditions during planetary formation. MESSENGER data from remote sensing of Mercury's surface [4] indicate a high abundance of sulfur and confirm the low abundance in FeO supporting the hypotheses that Mercury formed under reducing conditions [5]. Therefore, substantial amounts of other light elements like for instance silicon could be present together with sulfur inside Mercury's core. Unlike sulfur, which does almost not partition into solid iron under Mercury's core pressure and temperature conditions, silicon partitions virtually equally between solid and liquid iron. Thus, if silicon is the only light element inside the core, the density jump at the inner-core outer-core boundary is significantly smaller if compared to an Fe - FeS core. If both silicon and sulfur are present inside Mercury's core then as a consequence of a large immiscibility region in liquid Fe - Si - S at Mercury's core conditions and for specific concentrations of light elements [6] a thin layer much enriched in sulfur and depleted in silicon could form at the top of the core. In this study we analyze interior structure models with silicon as the only light element in the core and with both silicon and sulfur in the core. Compared to models with Fe - FeS both settings have different mass distributions within their cores and will likely deform differently due to different elastic properties. Consequently their libration and tides will be different

  10. Everglqades Mercury: Biogeochemistry, Modeling, and Possible Mitigation

    NASA Astrophysics Data System (ADS)

    Orem, W. H.

    2015-12-01

    In the 1980s high levels of methylmercury (MeHg) were found in fish and other biota in the Florida Everglades, prompting fish consumption advisories. As part of Everglades restoration efforts Federal and State Agencies initiated a research program to study the underlying causes of the MeHg contamination. As part of this multi-agency effort, the U.S. Geological Survey developed the ACME (Aquatic Cycling of Mercury in the Everglades) project to examine the underlying biogeochemical factors controlling MeHg production and bioaccumulation in the ecosystem. Field studies by ACME and others identified the many factors impacting MeHg production in the Everglades. Thes factors include: high mercury deposition, large wetland area with organic-rich anaerobic soil, high sulfate loading in surface runoff, circumneutral pH, and high dissolved organic matter (DOM) content. Florida Department of Environmental Protection efforts that reduced local mercury emissions by 90%, produced only a small reduction in mercury deposition on the Everglades, suggesting that most Hg deposited on the ecosystem originates from distant sources, and beyond the reach of regulators. ACME studies demonstrated that high sulfate loading to the Everglades comes from discharge of canal water originating in the Everglades Agricultural Area (EAA). The use of sulfur in agriculture and soil oxidation in the EAA have been shown to be the principal sources of the sulfate loading. Sulfate entering the ecosystem drives microbial sulfate reduction and MeHg production, but inhibition of MeHg production by sulfide (a byproduct of microbial sulfate reduction) makes the biogeochemistry complex. Laboratory microcosm and field mesocosm experiments by ACME helped define the complexity of the sulfur/MeHg biogeochemistry, and demonstrated the key role of dissolved organic matter in MeHg production. A conceptual model was developed that relates MeHg production to sulfate loading, DOM, and soil composition. This conceptual

  11. MESSENGER: Exploring Mercury's Magnetosphere

    NASA Technical Reports Server (NTRS)

    Slavin, James A.; Krimigis, Stamatios M.; Acuna, Mario H.; Anderson, Brian J.; Baker, Daniel N.; Koehn, Patrick L.; Korth, Haje; Levi, Stefano; Mauk, Barry H.; Solomon, Sean C.; Zurbuchen, Thomas H.

    2005-01-01

    The MESSENGER mission to Mercury offers our first opportunity to explore this planet s miniature magnetosphere since the brief flybys of Mariner 10. Mercury s magnetosphere is unique in many respects. The magnetosphere of Mercury is among the smallest in the solar system; its magnetic field typically stands off the solar wind only - 1000 to 2000 km above the surface. For this reason there are no closed drift paths for energetic particles and, hence, no radiation belts. The characteristic time scales for wave propagation and convective transport are short and kinetic and fluid modes may be coupled. Magnetic reconnection at the dayside magnetopause may erode the subsolar magnetosphere allowing solar wind ions to impact directly the regolith. Inductive currents in Mercury s interior may act to modify the solar wind interaction by resisting changes due to solar wind pressure variations. Indeed, observations of these induction effects may be an important source of information on the state of Mercury s interior. In addition, Mercury s magnetosphere is the only one with its defining magnetic flux tubes rooted in a planetary regolith as opposed to an atmosphere with a conductive ionospheric layer. This lack of an ionosphere is probably the underlying reason for the brevity of the very intense, but short-lived, - 1-2 min, substorm-like energetic particle events observed by Mariner 10 during its first traversal of Mercury s magnetic tail. Because of Mercury s proximity to the sun, 0.3 - 0.5 AU, this magnetosphere experiences the most extreme driving forces in the solar system. All of these factors are expected to produce complicated interactions involving the exchange and re-cycling of neutrals and ions between the solar wind, magnetosphere, and regolith. The electrodynamics of Mercury s magnetosphere are expected to be equally complex, with strong forcing by the solar wind, magnetic reconnection at the magnetopause and in the tail, and the pick-up of planetary ions all

  12. Determination of mercurous chloride and total mercury in mercury ores

    USGS Publications Warehouse

    Fahey, J.J.

    1937-01-01

    A method for the determination of mercurous chloride and total mercury on the same sample is described. The mercury minerals are volatilized in a glass tube and brought into intimate contact with granulated sodium carbonate. The chlorine is fixed as sodium chloride, determined with silver nitrate, and computed to mercurous chloride. The mercury is collected on a previously weighed gold coil and weighed.

  13. FUNDAMENTALS OF MERCURY OXIDATION IN FLUE GAS

    SciTech Connect

    JoAnn S. Lighty; Geoffrey Silcox; Andrew Fry; Constance Senior; Joseph Helble

    2004-08-01

    The objective of this project is to understand the importance of and the contribution of gas-phase and solid-phase coal constituents in the mercury oxidation reactions. The project involves two experimental scales and a modeling effort. The team is comprised of University of Utah, Reaction Engineering International, and University of Connecticut. The objective is to determine the experimental parameters of importance in the homogeneous and heterogeneous oxidation reactions; validate models; and, improve existing models. Parameters to be studies include HCl, NOx, and SO{sub 2} concentrations, ash constituents, and temperature. This report summarizes Year 1 results for the experimental and modeling tasks. Experiments in the drop tube are just beginning and a new, speciated mercury analyzer is up and running. A preliminary assessment has been made for the drop tube experiments using the existing model of gas-phase kinetics.

  14. NOVEL OXIDANT FOR ELEMENTAL MERCURY CONTROL FROM FLUE GAS

    EPA Science Inventory

    The primary objective of this study is to develop and test advanced noncarbonaceous solid sorbent materials suitable for removing the elemental form of mercury from power plant emissions. An efficient and cost-effective novel Hg(0) oxidant was evaluated in a lab-scale fixed-bed ...

  15. The fate of mercury collected from air pollution control devices

    EPA Science Inventory

    The mercury that enters a coal-fired power plant, originates from the coal that is burned, and leaves through the output streams that include stack emissions and air pollution control (APC) residues (either in solid or liquid form). This article describes recent fmdings on the fa...

  16. Optimizing fish sampling for fish–mercury bioaccumulation factors

    EPA Science Inventory

    Fish Bioaccumulation Factors (BAFs; ratios of mercury (Hg) in fish (Hgfish) and water (Hgwater)) are used to develop total maximum daily load and water quality criteria for Hg-impaired waters. Both applications require representative Hgfish estimates and, thus, are sensitive to s...

  17. Source identification and mass balance studies of mercury in Lake An-dong, S. Korea

    NASA Astrophysics Data System (ADS)

    Han, J.; Byeon, M.; Yoon, J.; Park, J.; Lee, M.; Huh, I.; Na, E.; Chung, D.; Shin, S.; Kim, Y.

    2009-12-01

    In this study, mercury and methylmercury were measured in atmospheric, tributary, open-lake water column, sediment, planktons and fish samples in the catchments area of Lake An-dong, S. Korea. Lake An-dong, an artificial freshwater lake is located on the upstream of River Nak-dong. It has 51.5 km2 of open surface water and 1.33 year of hydraulic residence time. It is a source of drinking water for 0.3 million S. Koreans. Recently, the possibilities of its mercury contamination became an issue since current studies showed that the lake had much higher mercury level in sediment and certain freshwater fish species than any other lakes in S. Korea. This catchments area has the possibilities of historical mercury pollution by the location of more than 50 abandoned gold mines and Young-poong zinc smelter. The objective of this study was to develop a mercury mass balance and identify possible mercury sources in the lake. The results of this study are thus expected to offer valuable insights for the sources of mercury loading through the watershed. In order to estimate the mercury flux, TGM, RGM and particulate mercury were measured using TEKRAN 2537 at the five sites surrounding Lake An-dong from May, 2009 with wet and dry deposition. The fate and transport of mercury in water body were predicted by using EFDC (Environmental Dynamic Fluid Code) and Mercury module in WASP7 (Water quality analysis program) after subsequent distribution into water body, sediments, followed by bioaccumulation and ultimate uptake by humans. The mercury mass balance in Young-poong zinc smelter was also pre-estimated by measuring mercury content in zinc ores, emission gases, sludge, wastewater and products.

  18. Mercury emissions from coal combustion in Silesia, analysis using geostatistics

    NASA Astrophysics Data System (ADS)

    Zasina, Damian; Zawadzki, Jaroslaw

    2015-04-01

    Data provided by the UNEP's report on mercury [1] shows that solid fuel combustion in significant source of mercury emission to air. Silesia, located in southwestern Poland, is notably affected by mercury emission due to being one of the most industrialized Polish regions: the place of coal mining, production of metals, stone mining, mineral quarrying and chemical industry. Moreover, Silesia is the region with high population density. People are exposed to severe risk of mercury emitted from both: industrial and domestic sources (i.e. small household furnaces). Small sources have significant contribution to total emission of mercury. Official and statistical analysis, including prepared for international purposes [2] did not provide data about spatial distribution of the mercury emitted to air, however number of analysis on Polish public power and energy sector had been prepared so far [3; 4]. The distribution of locations exposed for mercury emission from small domestic sources is interesting matter merging information from various sources: statistical, economical and environmental. This paper presents geostatistical approach to distibution of mercury emission from coal combustion. Analysed data organized in 2 independent levels: individual, bottom-up approach derived from national emission reporting system [5; 6] and top down - regional data calculated basing on official statistics [7]. Analysis, that will be presented, will include comparison of spatial distributions of mercury emission using data derived from sources mentioned above. Investigation will include three voivodeships of Poland: Lower Silesian, Opole (voivodeship) and Silesian using selected geostatistical methodologies including ordinary kriging [8]. References [1] UNEP. Global Mercury Assessment 2013: Sources, Emissions, Releases and Environmental Transport. UNEP Chemicals Branch, Geneva, Switzerland, 2013. [2] NCEM. Poland's Informative Inventory Report 2014. NCEM at the IEP-NRI, 2014. http

  19. Formation of nanocolloidal metacinnabar in mercury-DOM-sulfide systems

    USGS Publications Warehouse

    Gerbig, Chase A.; Kim, Christopher S.; Stegemeier, John P.; Ryan, Joseph N.; Aiken, George R.

    2011-01-01

    Direct determination of mercury (Hg) speciation in sulfide-containing environments is confounded by low mercury concentrations and poor analytical sensitivity. Here we report the results of experiments designed to assess mercury speciation at environmentally relevant ratios of mercury to dissolved organic matter (DOM) (i.e., -1) by combining solid phase extraction using C18 resin with extended X-ray absorption fine structure (EXAFS) spectroscopy. Aqueous Hg(II) and a DOM isolate were equilibrated in the presence and absence of 100 μM total sulfide. In the absence of sulfide, mercury adsorption to the resin increased as the Hg:DOM ratio decreased and as the strength of Hg-DOM binding increased. EXAFS analysis indicated that in the absence of sulfide, mercury bonds with an average of 2.4 ± 0.2 sulfur atoms with a bond length typical of mercury-organic thiol ligands (2.35 Å). In the presence of sulfide, mercury showed greater affinity for the C18 resin, and its chromatographic behavior was independent of Hg:DOM ratio. EXAFS analysis showed mercury–sulfur bonds with a longer interatomic distance (2.51–2.53 Å) similar to the mercury–sulfur bond distance in metacinnabar (2.53 Å) regardless of the Hg:DOM ratio. For all samples containing sulfide, the sulfur coordination number was below the ideal four-coordinate structure of metacinnabar. At a low Hg:DOM ratio where strong binding DOM sites may control mercury speciation (1.9 nmol mg-1) mercury was coordinated by 2.3 ± 0.2 sulfur atoms, and the coordination number rose with increasing Hg:DOM ratio. The less-than-ideal coordination numbers indicate metacinnabar-like species on the nanometer scale, and the positive correlation between Hg:DOM ratio and sulfur coordination number suggests progressively increasing particle size or crystalline order with increasing abundance of mercury with respect to DOM. In DOM-containing sulfidic systems nanocolloidal metacinnabar-like species may form, and these species need to

  20. Solid lipid nanoparticles co-loaded with doxorubicin and α-tocopherol succinate are effective against drug-resistant cancer cells in monolayer and 3-D spheroid cancer cell models.

    PubMed

    Oliveira, Mariana S; Aryasomayajula, Bhawani; Pattni, Bhushan; Mussi, Samuel V; Ferreira, Lucas A M; Torchilin, Vladmir P

    2016-10-15

    This work aimed to develop solid lipid nanoparticles (SLN) co-loaded with doxorubicin and α-tocopherol succinate (TS) and to evaluate its potential to overcome drug resistance and to increase antitumoral effect in MCF-7/Adr and NCI/Adr cancer cell lines. The SLN were prepared by a hot homogenization method and characterized for size, zeta potential, entrapment efficiency (EE), and drug loading (DL). The cytotoxicity of SLN or penetration was evaluated in MCF-7/Adr and NCI/adr as a monolayer or spheroid cancer cell model. The SLN showed a size in the range of 74-80nm, negative zeta potential, EE of 99%, and DL of 67mg/g. The SLN co-loaded with Dox and TS showed a stronger cytotoxicity against MCF-7/Adr and NCI/Adr cells. In the monolayer model, the doxorubicin co-localization as a free and encapsulated form was higher for the encapsulated drug in MCF-7/Adr and NCI/adr, suggesting a bypassing of P-glycoprotein bomb efflux. For cancer cell spheroids, the SLN co-loaded with doxorubicin and TS showed a prominent cytotoxicity and a greater penetration of doxorubicin. PMID:27568499