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Sample records for 30-cm mercury ion

  1. Status of 30 cm mercury ion thruster development

    NASA Technical Reports Server (NTRS)

    Sovey, J. S.; King, H. J.

    1974-01-01

    Two engineering model 30-cm ion thrusters were assembled, calibrated, and qualification tested. This paper discusses the thruster design, performance, and power system. Test results include documentation of thrust losses due to doubly charged mercury ions and beam divergence by both direct thrust measurements and beam probes. Diagnostic vibration tests have led to improved designs of the thruster backplate structure, feed system, and harness. Thruster durability is being demonstrated over a thrust range of 97 to 113 mN at a specific impulse of about 2900 seconds. As of August 15, 1974, the thruster has successfully operated for over 4000 hours.

  2. Advanced-technology 30-cm-diameter mercury ion thruster

    NASA Technical Reports Server (NTRS)

    Beattie, J. R.; Kami, S.

    1982-01-01

    An advanced-technology mercury ion thruster designed for operation at high thrust and high thrust-to-power ratio is described. The laboratory-model thruster employs a highly efficient discharge-chamber design that uses high-field-strength samarium-cobalt magnets arranged in a ring-cusp configuration. Ion extraction is achieved using an advanced three-grid ion-optics assembly which utilizes flexible mounts for supporting the screen, accel, and decel electrodes. Performance results are presented for operation at beam currents in the range from 1 to 5 A. The baseline specific discharge power is shown to be about 125 eV/ion, and the acceptable range of net-to-total accelerating-voltage ratio is shown to be in the range of 0.2-0.8 for beam currents in the range of 1-5 A.

  3. Long lifetime hollow cathodes for 30-cm mercury ion thrusters

    NASA Technical Reports Server (NTRS)

    Mirtich, M. J.; Kerslake, W. R.

    1976-01-01

    An experimental investigation of hollow cathodes for 30-cm Hg bombardment thrusters was carried out. Both main and neutralizer cathode configurations were tested with both rolled foil inserts coated with low work function material and impregnated porous tungsten inserts. Temperature measurements of an impregnated insert at various positions in the cathode were made. These, along with the cathode thermal profile are presented. A theory for rolled foil and impregnated insert operation and lifetime in hollow cathodes is developed. Several endurance tests, as long as 18000 hours at emission currents of up to 12 amps were attained with no degradation in performance.

  4. Digital computer control of a 30-cm mercury ion thruster

    NASA Technical Reports Server (NTRS)

    Low, C. A., Jr.

    1975-01-01

    The major objective was to define the exact role of an onboard spacecraft computer in the control of ion thrusters. An initial computer control system with accurate high speed capability was designed, programmed, and tested with the computer as the sole control element for an operating ion thruster. The command functions and a code format for a spacecraft digital control system were established. A second computer control system was constructed to operate with these functions and format. A throttle program sequence was established and tested. A two thruster array was tested with these computer control systems and the results reported.

  5. Digital computer control of a 30 cm mercury ion thruster

    NASA Technical Reports Server (NTRS)

    Low, C. A., Jr.

    1975-01-01

    The major objective of this program was to define the exact role of an on-board spacecraft computer in the control of ion thrusters. An initial computer control system with accurate high speed capability was designed, programmed, and tested with the computer as the sole control element for an operating ion thruster. The command functions and a code format for a spacecraft digital control system were established. A second computer control system was constructed to operate with these functions and format. A throttle program sequence was established and tested. A two thruster array was tested with these computer control systems and the results reported.

  6. Measurement of sputtered efflux from 5-, 8-, and 30-cm diameter mercury ion thrusters

    NASA Technical Reports Server (NTRS)

    Weigand, A. J.; Mirtich, M. J.

    1975-01-01

    A study was undertaken to investigate the sputtered efflux from 5-, 8-, and 30-cm diameter mercury ion thrusters. Quartz crystal microbalances and fused silica samples were used to analyze the sputtered flux. Spectral transmittance measurements and spectrographic analysis of the samples were made after they were exposed to different thruster effluence by operating the thrusters at various conditions and durations of time. These measurements were used to locate the source of the efflux and determine its accumulated effect at various locations near the thruster. Comparisons of in situ and ex situ transmittance measurements of samples exposed to thruster efflux are also presented.

  7. Measurement of sputtered efflux from 5-, 8-, and 30-cm diameter mercury ion thrusters

    NASA Technical Reports Server (NTRS)

    Weigand, A. J.; Mirtich, M. J.

    1975-01-01

    A technique has been developed which uses spectral transmittance of samples exposed to thruster efflux to determine and characterize the effect of the efflux on spacecraft surfaces and optical devices. An investigation of facility backsputter revealed that efflux samples must be protected (e.g., by small shield boxes) from materials from tank walls and targets. The composition of the sputter efflux deposited on the samples was mostly molybdenum with trace amounts of tantalum, iron and/or mercury. The efflux from a 5-cm diameter thruster was deposited on samples located in the plane of the accelerator grid; the 8-cm diameter thruster efflux results showed that the location of ion beam sputtering and efflux deposition equilibrium occurred at 57 deg with respect to the thruster axis; and the 30-cm diameter thruster had an ion beam erosion-efflux deposition equilibrium at 45 deg.

  8. Sensitivity of 30-cm mercury bombardment ion thruster characteristics to accelerator grid design

    NASA Technical Reports Server (NTRS)

    Rawlin, V. K.

    1978-01-01

    The design of ion optics for bombardment thrusters strongly influences overall performance and lifetime. The operation of a 30-cm thruster with accelerator grid open area fractions ranging from 43 to 24 percent, was evaluated and compared with previously published experimental and theoretical results. Ion optics properties measured included the beam current extraction capability, the minimum accelerator grid voltage to prevent backstreaming, ion beamlet diameter as a function of radial position on the grid and accelerator grid hole diameter, and the high energy, high angle ion beam edge location. Discharge chamber properties evaluated were propellant utilization efficiency, minimum discharge power per beam amp, and minimum discharge voltage.

  9. Sensitivity of 30-cm mercury bombardment ion thruster characteristics to accelerator grid design

    NASA Technical Reports Server (NTRS)

    Rawlin, V. K.

    1978-01-01

    The design of ion optics for bombardment thrusters strongly influences overall performance and lifetime. The operation of a 30 cm thruster with accelerator grid open area fractions ranging from 43 to 24 percent, was evaluated and compared with experimental and theoretical results. Ion optics properties measured included the beam current extraction capability, the minimum accelerator grid voltage to prevent backstreaming, ion beamlet diameter as a function of radial position on the grid and accelerator grid hole diameter, and the high energy, high angle ion beam edge location. Discharge chamber properties evaluated were propellant utilization efficiency, minimum discharge power per beam amp, and minimum discharge voltage.

  10. Charged particle measurements on a 30-CM diameter mercury ion engine thrust beam

    NASA Technical Reports Server (NTRS)

    Sellen, J. M., Jr.; Komatsu, G. K.; Hoffmaster, D. K.; Kemp, R. F.

    1974-01-01

    Measurements of both thrust ions and charge exchange ions were made in the beam of a 30 centimeter diameter electron bombardment mercury ion thruster. A qualitative model is presented which describes magnitudes of charge exchange ion formation and motions of these ions in the weak electric field structure of the neutralized thrust beam plasma. Areas of agreement and discrepancy between observed and modeled charge exchange properties are discussed.

  11. Test facility for 6000 hour life test of 30 cm mercury ion thruster

    NASA Technical Reports Server (NTRS)

    Caldwell, J. J.

    1973-01-01

    The environmental and instrumentation requirements for long term testing of electrical propulsion thrusters which impose severe and unusual requirements upon the simulation facility were studied. High speed ions ejected from a mercury thruster erode material from collecting surfaces, which is then scattered and redeposited upon other surfaces, with resultant damage to the chamber and test article. By collecting the thruster plume on a frozen mercury surface damage to the thruster and chamber by back-scattered erosion products was minimized. Provisions for unattended operation, remote data acquisition, personnel safety, and instrumentation for assessing thruster performance are also discussed.

  12. A 30-cm mercury ion thruster performance with a 1 kW capacitor-diode voltage multiplier beam supply

    NASA Technical Reports Server (NTRS)

    Terdan, F. F.; Harrigill, W. T., Jr.

    1978-01-01

    A 1 kW solar array and capacitor-diode voltage multiplier converter (S/A-CDVM) was successfully integrated with a 30 cm diameter mercury ion thruster system to provide ion beam power. Measurements were made to compare steady state and transient response performance of a conventional bridge converter with the S/A-CDVM converter used for the ion beam supply. The ability to recover from screen to accelerator arcs and promptly re-establish stable thruster performance was demonstrated. Solar array transient response to thruster arcing was measured.

  13. A model for predicting the wearout lifetime of the LeRC/Hughes 30-cm mercury ion thruster

    NASA Technical Reports Server (NTRS)

    Beattie, J. R.

    1979-01-01

    An investigation of parameters that affect the erosion rates of 30-cm-diameter mercury-ion-thruster components is described. A sputter-erosion model is formulated in terms of the design, operational, and material characteristics of the thruster. The erosion model is applied to the screen electrode, which is assumed to be the life-limiting component of the 30-cm thruster, resulting in a model of wearout lifetime. Results of short-term erosion-rate tests are presented that illustrate the dependence of component wear rates on variables such as discharge voltage, accelerator-grid open-area fraction, ion energy, electrode material, and the partial pressure of facility residual gases such as nitrogen. Test results are compared with wearout rates predicted by the sputter-erosion model.

  14. An engineering model 30 cm ion thruster

    NASA Technical Reports Server (NTRS)

    Poeschel, R. L.; King, H. J.; Schnelker, D. E.

    1973-01-01

    Thruster development at Hughes Research Laboratories and NASA Lewis Research Center has brought the 30-cm mercury bombardment ion thruster to the state of an engineering model. This thruster has been designed to have sufficient internal strength for direct mounting on gimbals, to weigh 7.3 kg, to operate with a corrected overall efficiency of 71%, and to have 10,000 hours lifetime. Subassemblies, such as the ion optical system, isolators, etc., have been upgraded to meet launch qualification standards. This paper presents a summary of the design specifications and performance characteristics which define the interface between the thruster module and the remainder of the propulsion system.

  15. The 30-cm ion thruster power processor

    NASA Technical Reports Server (NTRS)

    Herron, B. G.; Hopper, D. J.

    1978-01-01

    A power processor unit for powering and controlling the 30 cm Mercury Electron-Bombardment Ion Thruster was designed, fabricated, and tested. The unit uses a unique and highly efficient transistor bridge inverter power stage in its implementation. The system operated from a 200 to 400 V dc input power bus, provides 12 independently controllable and closely regulated dc power outputs, and has an overall power conditioning capacity of 3.5 kW. Protective circuitry was incorporated as an integral part of the design to assure failure-free operation during transient and steady-state load faults. The implemented unit demonstrated an electrical efficiency between 91.5 and 91.9 at its nominal rated load over the 200 to 400 V dc input bus range.

  16. A 30-cm diameter argon ion source

    NASA Technical Reports Server (NTRS)

    Sovey, J. S.

    1976-01-01

    A 30 cm diameter argon ion source was evaluated. Ion source beam currents up to 4a were extracted with ion energies ranging from 0.2 to 1.5 KeV. An ion optics scaling relation was developed for predicting ion beam extraction capability as a function of total extraction voltage, gas type, and screen grid open area. Ignition and emission characteristics of several hollow cathode geometries were assessed for purposes of defining discharge chamber and neutralizer cathodes. Also presented are ion beam profile characteristics which exhibit broad beam capability well suited for ion beam sputtering applications.

  17. NASA 30 Cm Ion Thruster Development Status

    NASA Technical Reports Server (NTRS)

    Patterson, Michael J.; Haag, Thomas W.; Rawlin, Vincent K.; Kussmaul, Michael T.

    1995-01-01

    A 30 cm diameter xenon ion thruster is under development at NASA to provide an ion propulsion option for missions of national interest and it is an element of the NASA Solar Electric Propulsion Technology Applications Readiness (NSTAR) program established to validate ion propulsion for space flight applications. The thruster has been developed to an engineering model level and it incorporates innovations in design, materials, and fabrication techniques compared to those employed to conventional ion thrusters. The performance of both functional and engineering model thrusters has been assessed including thrust stand measurements, over an input power range of 0.5-2.3 kW. Attributes of the engineering model thruster include an overall mass of 6.4 kg, and an efficiency of 65 percent and thrust of 93 mN at 2.3 kW input power. This paper discusses the design, performance, and lifetime expectations of the functional and engineering model thrusters under development at NASA.

  18. Radiated and conducted EMI from a 30-cm ion thruster

    NASA Technical Reports Server (NTRS)

    Whittlesey, A. C.; Peer, W.

    1981-01-01

    In order to properly assess the interaction of a spacecraft with the EMI environment produced by an ion thruster, the EMI environment was characterized. Therefore, radiated and conducted emissions were measured from a 30-cm mercury ion thruster. The ion thruster beam current varied from zero to 2.0 amperes and the emissions were measured from 5 KHz to 200 MHz. Several different types of antennas were used to obtain the measurements. The various measurements that were made included: magnetic field due to neutralizer/beam current loop; radiated electric fields of thruster and plume; and conducted emissions on arc discharge, neutralizer keeper and magnetic baffle lines.

  19. Direct thrust measurement of a 30-cm ion thruster

    NASA Technical Reports Server (NTRS)

    Banks, B.; Rawlin, V.; Weigand, A. J.; Walker, J.

    1975-01-01

    A direct thrust measurement of a 30-cm diameter ion thruster was accomplished by means of a laser interferometer thrust stand. The thruster was supported in a pendulum manner by three 3.65-m long wires. Electrical power was provided by means of 18 mercury filled pots. A movable 23-button planar probe rake was used to determine thrust loss due to ion beam divergence. Values of thrust, thrust loss due to ion beam divergence, and thrust loss due to multiple ionization were measured for ion beam currents ranging from 0.5 A to 2.5 A. Measured thrust values indicate an accuracy of approximately 1% and are in good agreement with thrust values calculated by indirect measurements.

  20. Power processor for a 30cm ion thruster

    NASA Technical Reports Server (NTRS)

    Biess, J. J.; Inouye, L. Y.

    1974-01-01

    A thermal vacuum power processor for the NASA Lewis 30cm Mercury Ion Engine was designed, fabricated and tested to determine compliance with electrical specifications. The power processor breadboard used the silicon controlled rectifier (SCR) series resonant inverter as the basic power stage to process all the power to an ion engine. The power processor includes a digital interface unit to process all input commands and internal telemetry signals so that operation is compatible with a central computer system. The breadboard was tested in a thermal vacuum environment. Integration tests were performed with the ion engine and demonstrate operational compatibility and reliable operation without any component failures. Electromagnetic interference data were also recorded on the design to provide information on the interaction with total spacecraft.

  1. Electric prototype power processor for a 30cm ion thruster

    NASA Technical Reports Server (NTRS)

    Biess, J. J.; Inouye, L. Y.; Schoenfeld, A. D.

    1977-01-01

    An electrical prototype power processor unit was designed, fabricated and tested with a 30 cm mercury ion engine for primary space propulsion. The power processor unit used the thyristor series resonant inverter as the basic power stage for the high power beam and discharge supplies. A transistorized series resonant inverter processed the remaining power for the low power outputs. The power processor included a digital interface unit to process all input commands and internal telemetry signals so that electric propulsion systems could be operated with a central computer system. The electrical prototype unit included design improvement in the power components such as thyristors, transistors, filters and resonant capacitors, and power transformers and inductors in order to reduce component weight, to minimize losses, and to control the component temperature rise. A design analysis for the electrical prototype is also presented on the component weight, losses, part count and reliability estimate. The electrical prototype was tested in a thermal vacuum environment. Integration tests were performed with a 30 cm ion engine and demonstrated operational compatibility. Electromagnetic interference data was also recorded on the design to provide information for spacecraft integration.

  2. Retrofit and acceptance test of 30-cm ion thrusters

    NASA Technical Reports Server (NTRS)

    Poeschel, R. L.

    1981-01-01

    Six 30 cm mercury thrusters were modified to the J-series design and evaluated using standardized test procedures. The thruster performance meets the design objectives (lifetime objective requires verification), and documentation (drawings, etc.) for the design is completed and upgraded. The retrofit modifications are described and the test data for the modifications are presented and discussed.

  3. Ion accelerator systems for high power 30 cm thruster operation

    NASA Technical Reports Server (NTRS)

    Aston, G.

    1982-01-01

    Two and three-grid accelerator systems for high power ion thruster operation were investigated. Two-grid translation tests show that over compensation of the 30 cm thruster SHAG grid set spacing the 30 cm thruster radial plasma density variation and by incorporating grid compensation only sufficient to maintain grid hole axial alignment, it is shown that beam current gains as large as 50% can be realized. Three-grid translation tests performed with a simulated 30 cm thruster discharge chamber show that substantial beamlet steering can be reliably affected by decelerator grid translation only, at net-to-total voltage ratios as low as 0.05.

  4. A mechanical, thermal and electrical packaging design for a prototype power management and control system for the 30 cm mercury ion thruster

    NASA Technical Reports Server (NTRS)

    Sharp, G. R.; Gedeon, L.; Oglebay, J. C.; Shaker, F. S.; Siegert, C. E.

    1978-01-01

    A prototype Electric Power Management and Thruster Control System for a 30 cm ion thruster has been built and is ready to support a first mission application. The system meets all of the requirements necessary to operate a thruster in a fully automatic mode. Power input to the system can vary over a full two to one dynamic range (200 to 400 V) for the solar array or other power source. The Power Management and Control system is designed to protect the thruster, the flight system and itself from arcs and is fully compatible with standard spacecraft electronics. The system is designed to be easily integrated into flight systems which can operate over a thermal environment ranging from 0.3 to 5 AU. The complete Power Management and Control system measures 45.7 cm x 15.2 cm x 114.8 cm and weighs 36.2 kg. At full power the overall efficiency of the system is estimated to be 87.4 percent. Three systems are currently being built and a full schedule of environmental and electrical testing is planned.

  5. A mechanical, thermal and electrical packaging design for a prototype power management and control system for the 30 cm mercury ion thruster

    NASA Technical Reports Server (NTRS)

    Sharp, G. R.; Gedeon, L.; Oglebay, J. C.; Shaker, F. S.; Siegert, C. E.

    1978-01-01

    A prototype electric power management and thruster control system for a 30 cm ion thruster is described. The system meets all of the requirements necessary to operate a thruster in a fully automatic mode. Power input to the system can vary over a full two to one dynamic range (200 to 400 V) for the solar array or other power source. The power management and control system is designed to protect the thruster, the flight system and itself from arcs and is fully compatible with standard spacecraft electronics. The system is easily integrated into flight systems which can operate over a thermal environment ranging from 0.3 to 5 AU. The complete power management and control system measures 45.7 cm (18 in.) x 15.2 cm (6 in.) x 114.8 cm (45.2 in.) and weighs 36.2 kg (79.7 lb). At full power the overall efficiency of the system is estimated to be 87.4 percent. Three systems are currently being built and a full schedule of environmental and electrical testing is planned.

  6. Performance of the NASA 30 cm Ion Thruster

    NASA Technical Reports Server (NTRS)

    Patterson, Michael J.; Haag, Thomas W.; Hovan, Scot A.

    1993-01-01

    A 30 cm diameter xenon ion thruster is under development at NASA to provide an ion propulsion option for missions of national interest, and is being proposed for use on the USAF/TRW Space Surveillance, Tracking and Autonomous Repositioning (SSTAR) platform to validate ion propulsion. The thruster incorporates innovations in design, materials, and fabrication techniques compared to those employed in conventional ion thrusters. Specific development efforts include thruster design optimizations, component life testing and validation, vibration testing, and performance characterizations. Under this test program, the ion thruster will be brought to engineering model development status. This paper discusses the performance and power throttling test data for the NASA 30 cm diameter xenon ion thruster over an input power envelope of 0.7 to 4.9 kW, and corresponding thruster lifetime expectations.

  7. Ion accelerator systems for high power 30-cm thruster operation

    NASA Technical Reports Server (NTRS)

    Aston, G.

    1982-01-01

    An investigation of two- and three-grid accelerator systems for high power ion thruster operation has been performed. Two-grid translation tests show that overcompensation of the 30-cm thruster SHAG (Small Hole Accelerator Grid) leads to a premature impingement limit. By better matching the SHAG grid set spacing to the 30-cm thruster radial plasma density variation and by incorporating grid compensation only sufficient to maintain grid hole axial alignment, it is shown that beam current gains as large as 50% can be realized. Three-grid translation tests performed with a simulated 30-cm thruster discharge chamber show that substantial beamlet steering can be reliably affected by decelerator grid translation only, at net-to-total voltage ratios as low as 0.05.

  8. Control of a 30 cm diameter mercury bombardment thruster

    NASA Technical Reports Server (NTRS)

    Terdan, F. F.; Bechtel, R. T.

    1973-01-01

    Control logic functions were established for three automatic modes of operation of a 30-cm thruster using a power conditioner console with flight-like characteristics. The three modes provide: (1) automatic startup to reach thermal stability, (2) steady-state closed-loop control, and (3) the reliable recycling of the high voltages following an arc breakdown to reestablish normal operation. Power supply impedance characteristics necessary for stable operation and the effect of the magnetic baffle on the reliable recycling was studied.

  9. Control of a 30 cm diameter mercury bombardment thruster

    NASA Technical Reports Server (NTRS)

    Terdan, F. F.; Bechtel, R. T.

    1973-01-01

    Increased thruster performance has made closed-loop automatic control more difficult than previously. Specifically, high perveance optics tend to make reliable recycling more difficult. Control logic functions were established for three automatic modes of operation of a 30-cm thruster using a power conditioner console with flight-like characteristics. The three modes provide (1) automatic startup to reach thermal stability, (2) steady-state closed-loop control, and (3) the reliable recycling of the high voltages following an arc breakdown to reestablish normal operation. Power supply impedance characteristics necessary for stable operation and the effect of the magnetic baffle on the reliable recycling was studied.

  10. Recycle Requirements for NASA's 30 cm Xenon Ion Thruster

    NASA Technical Reports Server (NTRS)

    Pinero, Luis R.; Rawlin, Vincent K.

    1994-01-01

    Electrical breakdowns have been observed during ion thruster operation. These breakdowns, or arcs, can be caused by several conditions. In flight systems, the power processing unit must be designed to handle these faults autonomously. This has a strong impact on power processor requirements and must be understood fully for the power processing unit being designed for the NASA Solar Electric Propulsion Technology Application Readiness program. In this study, fault conditions were investigated using a NASA 30 cm ion thruster and a power console. Power processing unit output specifications were defined based on the breakdown phenomena identified and characterized.

  11. Performance and Vibration of 30 cm Pyrolytic Ion Thruster Optics

    NASA Technical Reports Server (NTRS)

    Haag, Thomas; Soulas, George C.

    2004-01-01

    Carbon has a sputter erosion rate about an order of magnitude less than that of molybdenum, over the voltages typically used in ion thruster applications. To explore its design potential, 30 cm pyrolytic carbon ion thruster optics have been fabricated geometrically similar to the molybdenum ion optics used on NSTAR. They were then installed on an NSTAR Engineering Model thruster, and experimentally evaluated over much of the original operating envelope. Ion beam currents ranged from 0.51 to 1.76 Angstroms, at total voltages up to 1280 V. The perveance, electron back-streaming limit, and screen-grid transparency were plotted for these operating points, and compared with previous data obtained with molybdenum. While thruster performance with pyrolytic carbon was quite similar to that with molybdenum, behavior variations can reasonably be explained by slight geometric differences. Following all performance measurements, the pyrolytic carbon ion optics assembly was subjected to an abbreviated vibration test. The thruster endured 9.2 g(sub rms) of random vibration along the thrust axis, similar to DS 1 acceptance levels. Despite significant grid clashing, there was no observable damage to the ion optics assembly.

  12. Translation Optics for 30 cm Ion Engine Thrust Vector Control

    NASA Technical Reports Server (NTRS)

    Haag, Thomas

    2002-01-01

    Data were obtained from a 30 cm xenon ion thruster in which the accelerator grid was translated in the radial plane. The thruster was operated at three different throttle power levels, and the accelerator grid was incrementally translated in the X, Y, and azimuthal directions. Plume data was obtained downstream from the thruster using a Faraday probe mounted to a positioning system. Successive probe sweeps revealed variations in the plume direction. Thruster perveance, electron backstreaming limit, accelerator current, and plume deflection angle were taken at each power level, and for each accelerator grid position. Results showed that the thruster plume could easily be deflected up to six degrees without a prohibitive increase in accelerator impingement current. Results were similar in both X and Y direction.

  13. Studies of dished accelerator grids for 30-cm ion thrusters

    NASA Technical Reports Server (NTRS)

    Rawlin, V. K.

    1973-01-01

    Eighteen geometrically different sets of dished accelerator grids were tested on five 30-cm thrusters. The geometric variation of the grids included the grid-to-grid spacing, the screen and accelerator hole diameters and thicknesses, the screen and accelerator open area fractions, ratio of dish depth to dish diameter, compensation, and aperture shape. In general, the data taken over a range of beam currents for each grid set included the minimum total accelerating voltage required to extract a given beam current and the minimum accelerator grid voltage required to prevent electron backstreaming.

  14. Performance of 30-cm ion thrusters with dished accelerator grids

    NASA Technical Reports Server (NTRS)

    Rawlin, V. K.

    1973-01-01

    Thirteen sets of dished accelerator grids were treated on five different 30 cm diameter bombardment thrusters to evaluate the effects of grid geometry variations on thruster discharge chamber performance. The dished grid parameters varied were: grid-to-grid spacing, screen and accelerator grid hole diameter, screen and accelerator open area fraction, compensation for beam divergence losses, and accelerator grid thickness. The effects on discharge chamber performance of main magnetic field changes, magnetic baffle current, cathode pole piece length and cathode position were also investigated.

  15. Studies of dished accelerator grids for 30-cm ion thrusters

    NASA Technical Reports Server (NTRS)

    Rawlin, V. K.

    1973-01-01

    Geometrically different sets of dished accelerator grids were tested on five 30-cm thrusters. The geometric variation of the grids included the grid-to-grid spacing, the screen and accelerator hole diameters and thicknesses, the screen and accelerator open area fractions, ratio of dish depth to the dish diameter, compensation, and aperture shape. In general, the data taken over a range of beam currents for each grid set included the minimum total accelerating voltage required to extract a given beam current and the minimum accelerator grid voltage required to prevent electron backstreaming.

  16. Performance of 30-cm ion thrusters with dished accelerator grids

    NASA Technical Reports Server (NTRS)

    Rawlin, V. K.

    1973-01-01

    Thirteen sets of dished accelerator grids were tested on five different 30-cm diameter bombardment thrustors to evaluate the effects of grid geometry variations on thrustor discharge chamber performance. The dished grid parameters varied were: grid-to-grid spacing, screen and accelerator grid hole-diameter, screen and accelerator open area fraction, compensation for beam divergence losses, and accelerator grid thickness. Also investigated were the effects on discharge chamber performance of main magnetic field changes, magnetic baffle current cathode pole piece length and cathode position.

  17. Design, fabrication, and operation of dished accelerator grids on a 30-cm ion thruster.

    NASA Technical Reports Server (NTRS)

    Rawlin, V. K.; Banks, B. A.; Byers, D. C.

    1972-01-01

    Several closely-spaced dished accelerator grid systems have been fabricated and tested on a 30-cm diameter mercury bombardment thruster and they appear to be a solution to the stringent requirements imposed by the near-term, high-thrust, low specific impulse electric propulsion missions. The grids were simultaneously hydroformed and then simultaneously stress relieved. The ion extraction capability and discharge chamber performance were studied as the total accelerating voltage, the ratio of net-to-total voltage, grid spacing, and dish direction were varied.

  18. Design, fabrication, and operation of dished accelerator grids on a 30-cm ion thruster

    NASA Technical Reports Server (NTRS)

    Rawlin, V. K.; Banks, B. A.; Byers, D. C.

    1972-01-01

    Several closely-space dished accelerator grid systems were fabricated and tested on a 30-cm diameter mercury bombardment thruster and they appear to be a solution to the stringent requirements imposed by the near-term, high-thrust, low specific impulse electric propulsion missions. The grids were simultaneously hydroformed and then simultaneously stress relieved. The ion extraction capability and discharge chamber performance were studied as the total accelerating voltage, the ratio of net-to-total voltage, grid spacing, and dish direction were varied.

  19. Sputtering phenomena of discharge chamber components in a 30-cm diameter Hg ion thruster

    NASA Technical Reports Server (NTRS)

    Mantenieks, M. A.; Rawlin, V. K.

    1976-01-01

    Sputtering and deposition rates have been measured for discharge chamber components of a 30-cm diameter mercury ion thruster. It was found that sputtering rates of the screen grid and cathode baffle were strongly affected by geometry of the baffle holder. Sputtering rates of the baffle and screen grid were reduced to 80 and 125 A/hr, respectively, by combination of appropriate geometry and materials selections. Sputtering rates such as these are commensurate with thruster lifetimes of 15,000 hours or more. A semiempirical sputtering model showed good agreement with the measured values.

  20. Sputtering phenomena of discharge chamber components in a 30-cm diameter Hg ion thruster

    NASA Technical Reports Server (NTRS)

    Mantenieks, M. A.; Rawlin, V. K.

    1976-01-01

    Sputtering and deposition rates were measured for discharge chamber components of a 30-cm diameter mercury ion thruster. It was found that sputtering rates of the screen grid and cathode baffle were strongly affected by geometry of the baffle holder. Sputtering rates of the baffle and screen grid were reduced to 80 and 125 A/hr, respectively, by combination of appropriate geometry and materials selections. Sputtering rates such as these are commensurate with thruster lifetimes of 15,000 hours or more. A semiempirical sputtering model showed good agreement with the measured values.

  1. Structural and thermal response of 30 cm diameter ion thruster optics

    NASA Technical Reports Server (NTRS)

    Macrae, G. S.; Zavesky, R. J.; Gooder, S. T.

    1989-01-01

    Tabular and graphical data are presented which are intended for use in calibrating and validating structural and thermal models of ion thruster optics. A 30 cm diameter, two electrode, mercury ion thruster was operated using two different electrode assembly designs. With no beam extraction, the transient and steady state temperature profiles and center electrode gaps were measured for three discharge powers. The data showed that the electrode mount design had little effect on the temperatures, but significantly impacted the motion of the electrode center. Equilibrium electrode gaps increased with one design and decreased with the other. Equilibrium displacements in excess of 0.5 mm and gap changes of 0.08 mm were measured at 450 W discharge power. Variations in equilibrium gaps were also found among assemblies of the same design. The presented data illustrate the necessity for high fidelity ion optics models and development of experimental techniques to allow their validation.

  2. Retrofit and verification test of a 30-cm ion thruster

    NASA Technical Reports Server (NTRS)

    Dulgeroff, C. R.; Poeschel, R. L.

    1980-01-01

    Twenty modifications were found to be necessary and were approved by design review. These design modifications were incorporated in the thruster documents (drawings and procedures) to define the J series thruster. Sixteen of the design revisions were implemented in a 900 series thruster by retrofit modification. A standardized set of test procedures was formulated, and the retrofit J series thruster design was verified by test. Some difficulty was observed with the modification to the ion optics assembly, but the overall effect of the design modification satisfies the design objectives. The thruster was tested over a wide range of operating parameters to demonstrate its capabilities.

  3. Status of structural analysis of 30 cm diameter ion optics

    NASA Technical Reports Server (NTRS)

    Macrae, Gregory S.; Hering, Gary T.

    1990-01-01

    Three structural finite element programs are compared with theory, experimental data, and each other to evaluate their usefulness for modeling the thermomechanical deflection of ion engine electrodes. Two programs, NASTRAN and MARC, used a Cray XMP and the third, Algor, used an IBM compatible personal computer. The shape of the applied temperature gradient greatly affects off-axis displacement, implying that an accurate temperature distribution is required to analyze new designs. The use of bulk material constants to model the perforated electrodes was investigated. The stress and displacement predictions are shown to be sensitive to the temperature gradient and the Young's modulus, and insensitive to number of nodes, above some minimum value, and the Poisson ratio used. The models are shown to be useful tools for evaluating designs. Experimental measurements of temperatures and displacements was identified as the most critical area.

  4. Status of structural analysis of 30 cm diameter ion optics

    NASA Technical Reports Server (NTRS)

    Macrae, Gregory S.; Hering, Gary T.

    1990-01-01

    Three structural finite element programs are compared with theory, experimental data, and each other to evaluate their usefulness for modeling the thermomechanical deflection of ion engine electrodes. Two programs, NASTRAN and MARC, used a Cray XMP and the third, Algor, used an IBM compatible personal computer. The shape of the applied temperature gradient greatly affects off-axis displacement, implying that an accurate temperature distribution is required to analyze new designs. The use of bulk material constants to model the perforated electrodes was investigated. The stress and displacement predictions are shown to be sensitive to the temperature gradient and the Young's modulus, and insensitive to number of nodes, above some minimum value, and the Poisson ratio used. The models are shown to be useful tools for evaluating designs. Experimental measurement of temperatures and displacements was identified as the most critical area for further work.

  5. Extended operating range of the 30-cm ion thruster with simplified power processor requirements

    NASA Technical Reports Server (NTRS)

    Rawlin, V. K.

    1981-01-01

    A two grid 30 cm diameter mercury ion thruster was operated with only six power supplies over the baseline J series thruster power throttle range with negligible impact on thruster performance. An analysis of the functional model power processor showed that the component mass and parts count could be reduced considerably and the electrical efficiency increased slightly by only replacing power supplies with relays. The input power, output thrust, and specific impulse of the thruster were then extended, still using six supplies, from 2660 watts, 0.13 newtons, and 2980 seconds to 9130 watts, 0.37 newtons, and 3820 seconds, respectively. Increases in thrust and power density enable reductions in the number of thrusters and power processors required for most missions. Preliminary assessments of the impact of thruster operation at increased thrust and power density on the discharge characteristics, performance, and lifetime of the thruster were also made.

  6. Electrical Prototype Power Processor for the 30-cm Mercury electric propulsion engine

    NASA Technical Reports Server (NTRS)

    Biess, J. J.; Frye, R. J.

    1978-01-01

    An Electrical Prototpye Power Processor has been designed to the latest electrical and performance requirements for a flight-type 30-cm ion engine and includes all the necessary power, command, telemetry and control interfaces for a typical electric propulsion subsystem. The power processor was configured into seven separate mechanical modules that would allow subassembly fabrication, test and integration into a complete power processor unit assembly. The conceptual mechanical packaging of the electrical prototype power processor unit demonstrated the relative location of power, high voltage and control electronic components to minimize electrical interactions and to provide adequate thermal control in a vacuum environment. Thermal control was accomplished with a heat pipe simulator attached to the base of the modules.

  7. Test-to-Failure of a Two-Grid, 30-cm-dia. Ion Accelerator System

    NASA Technical Reports Server (NTRS)

    Brophy, J. R.; Polk, J. E.; Pless, L. C.

    1993-01-01

    To determine the failure mechanism and erosion characteristics of an ion accelerator system due to erosion by charge-exchange ions a test was performed in which a 30-cm-diameter, 2-grid ion accelerator system was tested to failure. The erosion charcteristics observed in this test, however, imply significantly shorter accelerator grid life times than typically stated in the literature. Finally, the test suggests that structural failure is probably not the most likely first failure mechanism for the accelerator grid.

  8. Reduced power processor requirements for the 30-cm diameter Hg ion thruster

    NASA Technical Reports Server (NTRS)

    Rawlin, V. K.

    1979-01-01

    An evaluation of simplifications for the thruster power processor interface for a 30 cm Hg ion thruster is presented. Tests on the engine, thruster control, and the power supplies are performed. Reduced power processors requirements are defined and the impact on thruster design, performance, and lifetime are assessed.

  9. Evolution and status of the 30-cm engineering model ion thruster

    NASA Technical Reports Server (NTRS)

    Masek, T. D.; Poeschel, R. L.; Collett, C. R.; Schnelker, D. E.

    1976-01-01

    In the past five years the 30-cm ion thruster has developed from infancy to maturity through the joint efforts of the NASA Lewis Research Center (LeRC) and the Hughes Research Laboratories (HRL). The evolution of the 30-cm thruster from the 200-series design to the present 900-series is described. This evolution has included both breadboard and engineering model type thrusters. The evolution description includes functional requirements, design, performance, endurance test results, and major features. The major part of the discussion centers on Hughes-built hardware although NASA LeRC contributions are reflected in the designs.

  10. Characteristics of a 30-cm thruster operated with small hole accelerator grid ion optics

    NASA Technical Reports Server (NTRS)

    Vahrenkamp, R. P.

    1976-01-01

    Small hole accelerator grid ion optical systems have been tested as a possible means of improving 30-cm ion thruster performance. The effects of small hole grids on the critical aspects of thruster operation including discharge chamber performance, doubly-charged ion concentration, effluent beam characteristics, and plasma properties have been evaluated. In general, small hole accelerator grids are beneficial in improving thruster performance while maintaining low double ion ratios. However, extremely small accelerator aperture diameters tend to degrade beam divergence characteristics. A quantitative discussion of these advantages and disadvantages of small hole accelerator grids, as well as resulting variations in thruster operation characteristics, is presented.

  11. Low voltage 30-cm ion thruster development. [including performance and structural integrity (vibration) tests

    NASA Technical Reports Server (NTRS)

    King, H. J.

    1974-01-01

    The basic goal was to advance the development status of the 30-cm electron bombardment ion thruster from a laboratory model to a flight-type engineering model (EM) thruster. This advancement included the more conventional aspects of mechanical design and testing for launch loads, weight reduction, fabrication process development, reliability and quality assurance, and interface definition, as well as a relatively significant improvement in thruster total efficiency. The achievement of this goal was demonstrated by the successful completion of a series of performance and structural integrity (vibration) tests. In the course of the program, essentially every part and feature of the original 30-cm Thruster was critically evaluated. These evaluations, led to new or improved designs for the ion optical system, discharge chamber, cathode isolator vaporizer assembly, main isolator vaporizer assembly, neutralizer assembly, packaging for thermal control, electrical terminations and structure.

  12. Fabrication and Vibration Results of 30-cm Pyrolytic Graphite Ion Optics

    NASA Technical Reports Server (NTRS)

    DePano, Michael K.; Hart, Stephen L.; Hanna, Andrew A.; Schneider, Analyn C.

    2004-01-01

    Boeing Electron Dynamic Devices, Inc. is currently developing pyrolytic graphite (PG) grids designed to operate on 30-cm NSTAR-type thrusters for the Carbon Based Ion Optics (CBIO) program. The PG technology effort of the CBIO program aims to research PG as a flightworthy material for use in dished ion optics by designing, fabricating, and performance testing 30-cm PG grids. As such, PG grid fabrication results will be discussed as will PG design considerations and how they must differ from the NSTAR molybdenum grid design. Surface characteristics and surface processing of PG will be explored relative to effects on voltage breakdown. Part of the CBIO program objectives is to understand the erosion of PG due to Xenon ion bombardment. Discussion of PG and CC sputter yields will be presented relative to molybdenum. These sputter yields will be utilized in the life modeling of carbon-based grids. Finally, vibration results of 30-cm PG grids will be presented and compared to a first-order model generated at Boeing EDD. Performance testing results of the PG grids will not be discussed in this paper as it has yet to be completed.

  13. Performance Characterization and Vibration Testing of 30-cm Carbon-Carbon Ion Optics

    NASA Technical Reports Server (NTRS)

    Steven Snyder, John; Brophy, John R.

    2004-01-01

    Carbon-based ion optics have the potential to significantly increase the operable life and power ranges of ion thrusters because of reduced erosion rates compared to molybdenum optics. The development of 15-cm and larger diameter grids has encountered many problems, however, not the least of which is the ability to pass vibration testing. JPL has recently developed a new generation of 30-cm carbon-carbon ion optics in order to address these problems and demonstrate the viability of the technology. Perveance, electron backstreaming, and screen grid transparency data are presented for two sets of optics. Vibration testing was successfully performed on two different sets of ion optics with no damage and the results of those tests are compared to models of grid vibrational behavior. It will be shown that the vibration model is a conservative predictor of grid response and can accurately describe test results. There was no change in grid alignment as a result of vibration testing and a slight improvement, if any change at all, in optics performance.

  14. Effect of facility background gases on internal erosion of the 30-cm Hg ion thruster

    NASA Technical Reports Server (NTRS)

    Rawlin, V. K.; Mantenieks, M. A.

    1978-01-01

    Sputtering erosion of the upstream side of the molybdenum screen grid by discharge chamber ions in mercury bombardment thrusters was considered. Data which revealed that the screen grid erosion was very sensitive to the partial pressure of certain background gases in the space simulation vacuum facility were presented along with results of tests conducted to evaluate this effect. It is shown from estimates of the screen grid erosion in space that adequate lifetime for proposed missions exists.

  15. Development Status of the NASA 30-cm Ion Thruster and Power Processor

    NASA Technical Reports Server (NTRS)

    Sovey, James S.; Haag, Thomas W.; Hamley, John A.; Mantenieks, Maris A.; Patterson, Michael J.; Pinero, Luis R.; Rawlin, Vincent K.; Kussmaul, Michael T.; Manzella, David H.; Myers, Roger M.

    1994-01-01

    Xenon ion propulsion systems are being developed by NASA Lewis Research Center and the Jet Propulsion Laboratory to provide flight qualification and validation for planetary and earth-orbital missions. In the ground-test element of this program, light-weight (less than 7 kg), 30 cm diameter ion thrusters have been fabricated, and preliminary design verification tests have been conducted. At 2.3 kW, the thrust, specific impulse, and efficiency were 91 mN, 3300 s, and 0.65, respectively. An engineering model thruster is now undergoing a 2000 h wear-test. A breadboard power processor is being developed to operate from an 80 V to 120 V power bus with inverter switching frequencies of 50 kHz. The power processor design is a pathfinder and uses only three power supplies. The projected specific mass of a flight unit is about 5 kg/kW with an efficiency of 0.92 at the full-power of 2.5 kW. Preliminary integration tests of the neutralizer power supply and the ion thruster have been completed. Fabrication and test of the discharge and beam/accelerator power stages are underway.

  16. Discharge Chamber Plasma Structure of a 30-cm NSTAR-Type Ion Engine

    NASA Technical Reports Server (NTRS)

    Herman, Daniel A.; Gallimore, Alec D.

    2006-01-01

    Single Langmuir probe measurements are presented over a two-dimensional array of locations in the near Discharge Cathode Assembly (DCA) region of a 30-cm diameter ring cusp ion thruster over a range of thruster operating conditions encompassing the high-power half of the NASA throttling table. The Langmuir probe data were analyzed with two separate methods. All data were analyzed initially assuming an electron population consisting of Maxwellian electrons only. The on-axis data were then analyzed assuming both Maxwellian and primary electrons. Discharge plasma data taken with beam extraction exhibit a broadening of the higher electron temperature plume boundary compared to similar discharge conditions without beam extraction. The opposite effect is evident with the electron/ion number density as the data without began, extraction appears to be more collimated than the corresponding data with beam extraction. Primary electron energy and number densities are presented for one operating condition giving an order of magnitude of their value and the error associated with this calculation.

  17. Performance Evaluation of Titanium Ion Optics for the NASA 30 cm Ion Thruster

    NASA Technical Reports Server (NTRS)

    Soulas, George C.

    2001-01-01

    The results of performance tests with titanium ion optics were presented and compared to those of molybdenum ion optics. Both titanium and molybdenum ion optics were initially operated until ion optics performance parameters achieved steady state values. Afterwards, performance characterizations were conducted. This permitted proper performance comparisons of titanium and molybdenum ion optics. Ion optics' performance A,as characterized over a broad thruster input power range of 0.5 to 3.0 kW. All performance parameters for titanium ion optics of achieved steady state values after processing 1200 gm of propellant. Molybdenum ion optics exhibited no burn-in. Impingement-limited total voltages for titanium ion optics where up to 55 V greater than those for molybdenum ion optics. Comparisons of electron backstreaming limits as a function of peak beam current density for molybdenum and titanium ion optics demonstrated that titanium ion optics operated with a higher electron backstreaming limit than molybdenum ion optics for a given peak beam current density. Screen grid ion transparencies for titanium ion optics were as much as 3.8 percent lower than those for molybdenum ion optics. Beam divergence half-angles that enclosed 95 percent of the total beam current for titanium ion optics were within 1 to 3 deg. of those for molybdenum ion optics. All beam divergence thrust correction factors for titanium ion optics were within 1 percent of those with molybdenum ion optics.

  18. Performance of Titanium Optics on a NASA 30 Cm Ion Thruster

    NASA Technical Reports Server (NTRS)

    Soulas, George C.; Foster, John E.; Patterson, Michael J.

    2000-01-01

    The results of performance tests with two titanium optics sets are presented and compared to those of molybdenum optics. All tests were conducted on a 30 cm ion thruster that was nearly identical to the NASA Solar Electric Propulsion Technology Application Readiness (NSTAR) thruster design. Optics performance tests were conducted over a thruster input power range of 0.5 to 4.6 kW. Optics performance including impingement-limited total voltages, electron backstreaming limits, screen grid ion transparencies, near-field beam current density profiles, beam divergence angles, and beam divergence thrust correction factors were determined throughout this power range. The impingement-limited total voltages for titanium optics were within 10 to 55 V of those for molybdenum optics. Electron backstreaming limit magnitude as a function of peak beam current density for both molybdenum and titanium optics were within a few volts of each other, indicating similar hot grid gaps for these two grid materials during steady-state operation. Beam divergence half-angles at 90 percent of the total beam current and thrust correction factors for both titanium optics sets were within one degree and one percent, respectively, of those for molybdenum optics. When thruster power was increased to 2.3 kW immediately following discharge ignition, the titanium screen grid came into contact with the accelerator grid within five minutes of ignition. Relative to molybdenum, titanium's larger thermal expansion and smaller thermal conductivity likely caused the screen grid to thermally expand more relative to the accelerator grid during startup.

  19. Fabrication and verification testing of ETM 30 cm diameter ion thrusters

    NASA Technical Reports Server (NTRS)

    Collett, C.

    1977-01-01

    Engineering model designs and acceptance tests are described for the 800 and 900 series 30 cm electron bombardment thrustors. Modifications to the test console for a 1000 hr verification test were made. The 10,000 hr endurance test of the S/N 701 thruster is described, and post test analysis results are included.

  20. A structural and thermal packaging approach for power processing units for 30-cm ion thrusters

    NASA Technical Reports Server (NTRS)

    Maloy, J. E.; Sharp, G. R.

    1975-01-01

    Solar Electric Propulsion (SEP) is currently being studied for possible use in a number of near earth and planetary missions. The thruster subsystem for these missions would consist of 30 centimeter ion thrusters with Power Processor Units (PPU) clustered in assemblies of from two to ten units. A preliminary design study of the electronic packaging of the PPU has been completed at Lewis Research Center of NASA. This study evaluates designs meeting the competing requirements of low system weight and overall mission flexibility. These requirements are evaluated regarding structural and thermal design, electrical efficiency, and integration of the electrical circuits into a functional PPU layout.

  1. Mercury ion thruster technology

    NASA Technical Reports Server (NTRS)

    Beattie, J. R.; Matossian, J. N.

    1989-01-01

    The Mercury Ion Thruster Technology program was an investigation for improving the understanding of state-of-the-art mercury ion thrusters. Emphasis was placed on optimizing the performance and simplifying the design of the 30 cm diameter ring-cusp discharge chamber. Thruster performance was improved considerably; the baseline beam-ion production cost of the optimized configuration was reduced to Epsilon (sub i) perspective to 130 eV/ion. At a discharge propellant-utilization efficiency of 95 percent, the beam-ion production cost was reduced to about 155 eV/ion, representing a reduction of about 40 eV/ion over the corresponding value for the 30 cm diameter J-series thruster. Comprehensive Langmuir-probe surveys were obtained and compared with similar measurements for a J-series thruster. A successful volume-averaging scheme was developed to correlate thruster performance with the dominant plasma processes that prevail in the two thruster designs. The average Maxwellian electron temperature in the optimized ring-cusp design is as much as 1 eV higher than it is in the J-series thruster. Advances in ion-extraction electrode fabrication technology were made by improving materials selection criteria, hydroforming and stress-relieving tooling, and fabrications procedures. An ion-extraction performance study was conducted to assess the effect of screen aperture size on ion-optics performance and to verify the effectiveness of a beam-vectoring model for three-grid ion optics. An assessment of the technology readiness of the J-series thruster was completed, and operation of an 8 cm IAPS thruster using a simplified power processor was demonstrated.

  2. Near Discharge Cathode Assembly Plasma Potential Measurements in a 30-cm NSTAR Type Ion Engine During Beam Extraction

    NASA Technical Reports Server (NTRS)

    Herman, Daniel A.; Gallimore, Alec D.

    2006-01-01

    Floating emissive probe plasma potential data are presented over a two-dimensional array of locations in the near Discharge Cathode Assembly (DCA) region of a 30-cm diameter ring-cusp ion thruster. Discharge plasma data are presented with beam extraction at throttling conditions comparable to the NASA TH Levels 8, 12, and 15. The operating conditions of the Extended Life Test (ELT) of the Deep Space One (DS1) flight spare ion engine, where anomalous discharge keeper erosion occurred, were TH 8 and TH 12 consequently they are of specific interest in investigating discharge keeper erosion phenomena. The data do not validate the presence of a potential hill plasma structure downstream of the DCA, which has been proposed as a possible erosion mechanism. The data are comparable in magnitude to data taken by other researchers in ring-cusp electron-bombardment ion thrusters. The plasma potential structures are insensitive to thruster throttling level with a minimum as low as 14 V measured at the DCA exit plane and increasing gradually in the axial direction. A sharp increase in plasma potential to the bulk discharge value of 26 to 28 volts, roughly 10 mm radially from DCA centerline, was observed. Plasma potential measurements indicate a low-potential plume structure that is roughly 20 mm in diameter emanating from the discharge cathode that may be attributed to a free-standing plasma double layer.

  3. Ion accelerator system mounting design and operating characteristics for a 5 kW 30-cm xenon ion engine

    NASA Technical Reports Server (NTRS)

    Aston, Graeme; Brophy, John R.

    1987-01-01

    Results from a series of experiments to determine the effect of accelerator grid mount geometry on the performance of the J-series ion optics assembly are described. Three mounting schemes, two flexible and one rigid, are compared for their relative ion extraction capability over a range of total accelerating voltages. The largest ion beam current, for the maximum total voltage investigated, is shown to occur using one of the flexible grid mounting geometries. However, at lower total voltages and reduced engine input power levels, the original rigid J-series ion optics accelerator grid mounts result in marginally better grid system performance at the same cold interelectrode gap.

  4. The Use of Laser-Induced Fluorescence to Characterize Discharge Cathode Erosion in a 30 cm Ring-Cusp Ion Thruster

    NASA Technical Reports Server (NTRS)

    Sovey, James S. (Technical Monitor); Williams, George J., Jr.

    2004-01-01

    Relative erosion rates and impingement ion production mechanisms have been identified for the discharge cathode of a 30 cm ion engine using laser-induced fluorescence (LIF). Mo and W erosion products as well as neutral and singly ionized xenon were interrogated. The erosion increased with both discharge current and voltage and spatially resolved measurements agreed with observed erosion patters. Ion velocity mapping identified back-flowing ions near the regions of erosion with energies potentially sufficient to generate the level of observed erosion. Ion production regions downstream of the cathode were indicated and were suggested as possible sources of the erosion causing ions.

  5. The effects of exposure to LN2 temperatures and 2.5 suns solar radiation on 30-cm ion thruster performance

    NASA Technical Reports Server (NTRS)

    Mirtich, M. J.

    1975-01-01

    An experimental test program was developed to demonstrate all 30 cm Hg-ion bombardment thruster functions over the thermal environment of several proposed missions. A 30 cm thruster with grids dished 1.25 cm and instrumented with 31 thermocouples, was placed in a vacuum tank equipped with minus 196 C walls. Cold storage of a thruster was simulated and temperatures as low as minus 100 C were attained on the thruster. The thruster started successfully from these cold conditions. The thruster operating at both half and full beam power was exposed to 2.5 suns on axis solar simulation. Various thruster thermal configurations, used to simulate multiple thruster operation, were tested at the above conditions. The results of these tests are reported herein.

  6. The effects of exposure to LN2 temperatures and 2.5 suns solar radiation on 30-cm ion thruster performance

    NASA Technical Reports Server (NTRS)

    Mirtich, M. J.

    1975-01-01

    An experimental test program was developed to demonstrate all 30 cm Hg-ion bombardment thruster functions over the thermal environment of several proposed missions. A 30 cm thruster with grids dished 1.25 cm and instrumented with 31 thermocouples, was placed in a vacuum tank equipped with -196 C walls. Cold storage of a thruster was simulated and temperatures as low as -100 C were attained on the thruster. The thruster started successfully from these cold conditions. The thruster operating at both half and full beam power was exposed to 2.5 suns on axis solar simulation. Various thruster thermal configurations, used to simulate multiple thruster operation, were tested at the above conditions. The results of these tests are reported herein.

  7. Endurance testing of a 30-cm Kaufman thruster

    NASA Technical Reports Server (NTRS)

    Collett, C. R.

    1973-01-01

    Results of a program to demonstrate lifetime capability of a 30-cm Kaufman ion thruster with a 6000 hour endurance test are described. Included in the program are (1) thruster fabrication, (2) design and construction of a test console containing a transistorized high frequency power processor, and control circuits which provide unattended automatic operation of the thruster, and (3) modification of a vacuum facility to incorporate a frozen mercury collector and permit unattended operation. Four tests ranging in duration from 100 to 1100 hours have been completed. These tests and the resulting thruster modifications are described. The status of the endurance test is also presented.

  8. Status of 30-centimeter-diameter mercury ion thruster isolator development

    NASA Technical Reports Server (NTRS)

    Mantenieks, M. A.

    1976-01-01

    Results are presented of several 30 cm diameter mercury ion thruster isolator life tests that show that the onset and exponential increase of leakage current problems observed in earlier thruster operations and isolator tests have been solved. A 10,006 hour life test of a main isolator vaporizer operated with no mercury flow at 320 C and 1500 volts was found to have no onset of leakage current during the test. A cathode-isolator vaporizer operated with a mercury discharge at 340 to 360 C and 1200 volts for 18,000 hours, was found to have a small increase of leakage current with time. A 10,000 hour thruster life test exhibited no increase of leakage current during the life test. Isolators have been developed which will satisfy 30 cm mercury ion thruster mission requirements.

  9. 30-cm electron cyclotron plasma generator

    NASA Technical Reports Server (NTRS)

    Goede, Hank

    1987-01-01

    Experimental results on the development of a 30-cm-diam electron cyclotron resonance plasma generator are presented. This plasma source utilizes samarium-cobalt magnets and microwave power at a frequency of 4.9 GHz to produce a uniform plasma with densities of up to 3 x 10 to the 11th/cu cm in a continuous fashion. The plasma generator contains no internal structures, and is thus inherently simple in construction and operation and inherently durable. The generator was operated with two different magnetic geometries. One used the rare-earth magnets arranged in an axial line cusp configuration, which directly showed plasma production taking place near the walls of the generator where the electron temperature was highest but with the plasma density peaking in the central low B-field regions. The second configuration had magnets arranged to form azimuthal line cusps with approximately closed electron drift surfaces; this configuration showed an improved electrical efficiency of about 135 eV/ion.

  10. Ion trajectories in Mercury's magnetosphere

    NASA Astrophysics Data System (ADS)

    Sarantos, M.; Reiff, P.; Killen, R.

    2003-04-01

    The atmosphere of Mercury is eroded quickly by photoionization and electron impact ionization. Resulting ions are affected by both magnetic and electric field forces due to their small energy. The escape flux of these ions from Mercury's magnetosphere is believed to respond to the degree of solar wind - Hermean magnetosphere interaction. We present the structure of the Hermean magnetosphere obtained by the Toffoletto-Hill (JGR 98, 1339, 1993) model of an open magnetosphere, and supplement it with the Ding et al. (Phys. Space Plasmas, 1996) potential solver to represent the convection electric field. We follow thousands of Na and K ions in a tight grid of magnetic and electric fields at Mercury. Ions are created with a spatial distribution given from the neutral distribution to cover the entire dayside, and are launched at the surface, with an isotropic angular distribution. The initial energy is taken to be ˜1eV. We calculate the loci of points where the ions reimpact the planetary surface. We conclude that the dawn-dusk asymmetry and high-latitude enhancements in the sodium atmosphere are perpetuated by the pattern of ion redistribution due to a predominant dawn to dusk electric field. The solar wind ion sputtering effect will further amplify atmospheric patchiness.

  11. Ion Trajectories In Mercury's Magnetosphere

    NASA Astrophysics Data System (ADS)

    Sarantos, M.; Killen, R.

    The atmosphere of Mercury is eroded quickly by photoionization and electron impact ionization. Resulting ions are affected by both magnetic and electric field forces due to their small energy. The escape flux of these ions from Mercury's magnetosphere is believed to respond to the degree of solar wind - Hermean magnetosphere interaction. We present the structure of the Hermean magnetosphere obtained by the Toffoletto- Hill (JGR 98, 1339, 1993) model of an open magnetosphere, and supplement it with the Ding et al. (Phys. Space Plasmas, 1996) potential solver to represent the convection electric field. We calculate the fractional escape rate of sodium, potassium and argon ions as a function of the interplanetary magnetic field (IMF) direction and magnitude.

  12. A trapped mercury 199 ion frequency standard

    NASA Technical Reports Server (NTRS)

    Cutler, L. S.; Giffard, R. P.; Mcguire, M. D.

    1982-01-01

    Mercury 199 ions confined in an RF quadrupole trap and optically pumped by mercury 202 ion resonance light are investigated as the basis for a high performance frequency standard with commercial possibilities. Results achieved and estimates of the potential performance of such a standard are given.

  13. Performance mapping of a 30 cm engineering model thruster

    NASA Technical Reports Server (NTRS)

    Poeschel, R. L.; Vahrenkamp, R. P.

    1975-01-01

    A 30 cm thruster representative of the engineering model design has been tested over a wide range of operating parameters to document performance characteristics such as electrical and propellant efficiencies, double ion and beam divergence thrust loss, component equilibrium temperatures, operational stability, etc. Data obtained show that optimum power throttling, in terms of maximum thruster efficiency, is not highly sensitive to parameter selection. Consequently, considerations of stability, discharge chamber erosion, thrust losses, etc. can be made the determining factors for parameter selection in power throttling operations. Options in parameter selection based on these considerations are discussed.

  14. Performance documentation of the engineering model 30-cm diameter thruster

    NASA Technical Reports Server (NTRS)

    Bechtel, R. T.; Rawlin, V. K.

    1976-01-01

    The results of extensive testing of two 30-cm ion thrusters which are virtually identical to the 900 series Engineering Model Thruster in an ongoing 15,000-hour life test are presented. Performance data for the nominal fullpower (2650 W) operating point; performance sensitivities to discharge voltage, discharge losses, accelerator voltage, and magnetic baffle current; and several power throttling techniques (maximum Isp, maximum thrust/power ratio, and two cases in between are included). Criteria for throttling are specified in terms of the screen power supply envelope, thruster operating limits, and control stability. In addition, reduced requirements for successful high voltage recycles are presented.

  15. Trapped-Mercury-Ion Frequency Standard

    NASA Technical Reports Server (NTRS)

    Prestage, John D.; Dick, G. John; Maleki, Lutfollah

    1991-01-01

    Report describes principle of operation, design, and results of initial measurements on trapped-mercury-ion frequency-standard apparatus at NASA's Jet Propulsion Laboratory. New frequency standard being developed. Based on linear ion trap described in (NPO-17758). Expected to show much better short-term frequency stability because of increased ion-storage capacity.

  16. The trapped mercury ion frequency standard

    NASA Technical Reports Server (NTRS)

    Mcguire, M. D.

    1977-01-01

    Singly ionized mercury atoms have a structure similar to neutral alkali atoms. They can be maintained as ions for very long times in an RF quadrupole ion trap. Thus, their ground state hyperfine structure can be used to make a frequency standard using optical pumping techniques similar to the well-known rubidium standard. The mass 199 isotope of mercury has an ionic hyperfine structure of 40.5 GHz. In a trap system a linewidth of 10 Hz has been measured. An expression is presented for the short-term stability of a proposed mercury standard as set by the achieved signal to noise ratio. There is prospect of further improvement. Long-term stability is affected by second order doppler effect, and by pressure, light, and Stark shifts. However, these appear either sufficiently small or sufficiently controlable that the proposed mercury ion standard would be competitive with existing standards.

  17. Ion trajectories in Mercury s magnetosphere

    NASA Astrophysics Data System (ADS)

    Sarantos, M.; Killen, R.; Reiff, P.

    The atmosphere of Mercury is eroded quickly by photoionization and electron impact ionization. Resulting ions are affected by both magnetic and electric field forces due to their small energy. The escape flux of these ions from Mercury's magnetosphere is believed to respond to the degree of solar wind - Hermean magnetosphere interaction. We present the structure of the Hermean magnetosphere obtained by the Toffoletto-Hill (JGR 98, 1339, 1993) model of an open magnetosphere, and supplement it with the Ding et al. (Phys. Space Plasmas, 1996) potential solver to represent the convection electric field. We calculate the fractional escape ratio of Na and K ions as a function of IMF direction and magnitude. We also provide evidence for the role that the IMF may play in generating ions at Mercury by quantitatively predicting the solar wind particle flux that directly impinges upon the Hermean surface as w e regulate the IMF environment.

  18. Comparison of thermal analytic model with experimental test results for 30-sentimeter-diameter engineering model mercury ion thruster

    NASA Technical Reports Server (NTRS)

    Oglebay, J. C.

    1977-01-01

    A thermal analytic model for a 30-cm engineering model mercury-ion thruster was developed and calibrated using the experimental test results of tests of a pre-engineering model 30-cm thruster. A series of tests, performed later, simulated a wide range of thermal environments on an operating 30-cm engineering model thruster, which was instrumented to measure the temperature distribution within it. The modified analytic model is described and analytic and experimental results compared for various operating conditions. Based on the comparisons, it is concluded that the analytic model can be used as a preliminary design tool to predict thruster steady-state temperature distributions for stage and mission studies and to define the thermal interface bewteen the thruster and other elements of a spacecraft.

  19. Optical properties of mercury ion thruster exhausts and implications for science instruments

    NASA Technical Reports Server (NTRS)

    Monahan, K. M.; Goldstein, R.

    1974-01-01

    Emission from the exhaust plume of a 30 cm mercury ion thruster was measured from 160 to 600 nm as a function of axial and radial distance from the thruster discharge chamber. The spectrally dispersed absolute intensities were used to construct an empirical volume rate function. The function was integrated along a typical instrument field of view, and the resulting apparent brightness was compared with instrument sensitivities to evaluate the extent of optical interference. Most of the emitted radiation came from UV lines of excited mercury atoms and ions, with no observable continuum emission. The intensity levels degraded rapidly with distance from the thruster so that optical interference was negligible for fields of view not intercepting the beam axis. The operation of only one instrument, a zodiacal photopolarimeter, was considered incompatible with simultaneous thruster operation.

  20. Ion observations at Mercury's Magnetospheric Cusp

    NASA Astrophysics Data System (ADS)

    Jasinski, Jamie; Raines, Jim; Slavin, James

    2016-04-01

    The magnetospheric cusp is a region of direct entry for solar wind mass, energy and momentum into a planetary magnetosphere. Dayside magnetic reconnection between the interplanetary magnetic field and the planetary field allows shocked solar wind plasma to flow down open magnetospheric field lines. Whilst this is occurring these magnetic field lines convect poleward. For a spacecraft travelling through the high latitudes, this causes a velocity filter effect to be observed in the ion data, whereby higher energy ions are observed at lower latitudes. Here we present the ion observations from the MESSENGER spacecraft at Mercury's cusp, specifically focusing on ions latitudinally dispersed in energy. From these dispersions, the distance to the reconnection site is calculated and used to better understand the process of reconnection at Mercury's dayside magnetopause.

  1. Characteristics of 30-centimeter mercury ion thrusters

    NASA Technical Reports Server (NTRS)

    Maloy, J. E.; Poeschel, R. L.; Dugeroff, C. R.

    1981-01-01

    The technology development of the 30 centimeter J series mercury ion thruster for prime propulsion application in solar electric propulsion systems is described. Thruster design is reviewed. A standardized set of test and data recording procedures formulated to allow for the characterization of the J series thruster is described. Characteristics measured are the magnetic baffle characterization, the neutralizer characterization, perveance, the minimum eV/ion measurement, and the electrical and propellant utilization efficiency measurements. Test results are presented.

  2. Mercury ion thruster research, 1977. [plasma acceleration

    NASA Technical Reports Server (NTRS)

    Wilbur, P. J.

    1977-01-01

    The measured ion beam divergence characteristics of two and three-grid, multiaperture accelerator systems are presented. The effects of perveance, geometry, net-to-total accelerating voltage, discharge voltage and propellant are examined. The applicability of a model describing doubly-charged ion densities in mercury thrusters is demonstrated for an 8-cm diameter thruster. The results of detailed Langmuir probing of the interior of an operating cathode are given and used to determine the ionization fraction as a function of position upstream of the cathode orifice. A mathematical model of discharge chamber electron diffusion and collection processes is presented along with scaling laws useful in estimating performance of large diameter and/or high specific impluse thrusters. A model describing the production of ionized molecular nitrogen in ion thrusters is included.

  3. Centrifugally Stimulated Exospheric Ion Escape at Mercury

    NASA Technical Reports Server (NTRS)

    Delcourt, Dominique; Seki, K.; Terada, N.; Moore, Thomas E.

    2012-01-01

    We investigate the transport of ions in the low-altitude magnetosphere magnetosphere of Mercury. We show that, because of small spatial scales, the centrifugal effect due to curvature of the E B drift paths can lead to significant particle energization in the parallel direction. We demonstrate that because of this effect, ions with initial speed smaller than the escape speed such as those produced via thermal desorption can overcome gravity and escape into the magnetosphere. The escape route of this low-energy exosphere originating material is largely controlled by the magnetospheric convection rate. This escape route spreads over a narrower range of altitudes when the convection rate increases. Bulk transport of low-energy planetary material thus occurs within a limited region of space once moderate magnetospheric convection is established. These results suggest that, via release of material otherwise gravitationally trapped, the E B related centrifugal acceleration is an important mechanism for the net supply of plasma to the magnetosphere of Mercury.

  4. The 8-CM ion thruster characterization. [mercury ion engine

    NASA Technical Reports Server (NTRS)

    Wessel, F. J.; Williamson, W. S.

    1983-01-01

    The performance capabilities of the 8 cm diameter mercury ion thruster were increased by modifying the thruster operating parameters and component hardware. The initial performance levels, representative of the Hughes/NASA Lewis Research Center Ion Auxiliary Propulsion Subsystem (IAPS) thruster, were raised from the baseline values of thrust, T = 5 mN, and specific impulse, I sub sp = 2,900s, to thrust, T = 25 mN and specific impulse, I sub sp = 4,300 s. Performance characteristics including estmates of the erosion rates of various component surfaces are presented.

  5. The JPL trapped mercury ion frequency standard

    NASA Technical Reports Server (NTRS)

    Prestage, J. D.; Dick, G. J.; Maleki, L.

    1988-01-01

    In order to provide frequency standards for the Deep Space Network (DSN) which are more stable than present-day hydrogen masers, a research task was established under the Advanced Systems Program of the TDA to develop a Hg-199(+) trapped ion frequency standard. The first closed-loop operation of this kind is described. Mercury-199 ions are confined in an RF trap and are state-selected through the use of optical pumping with 194 nm UV light from a Hg-202 discharge lamp. Absorption of microwave radiation at the hyperfine frequency (40.5 GHz) is signaled by atomic fluorescence of the UV light. The frequency of a 40.5 GHz oscillator is locked to a 1.6 Hz wide atomic absorption line of the trapped ions. The measured Allan variance of this locked oscillator is currently gamma sub y (pi) = 4.4 x 10 to the minus 12th/square root of pi for 20 is less than pi is less than 320 seconds, which is better stability than the best commercial cesium standards by almost a factor of 2. This initial result was achieved without magnetic shielding and without regulation of ion number.

  6. A multiple thruster array for 30-cm thrusters

    NASA Technical Reports Server (NTRS)

    Rawlin, V. K.; Mantenieks, M. A.

    1975-01-01

    The 3.0-m diameter chamber of the 7.6-m diameter by 21.4-m long vacuum tank at NASA LeRC was modified to permit testing of an array of up to six 30-cm thrusters with a variety of laboratory and thermal vacuum bread-board power systems. A primary objective of the Multiple Thruster Array (MTA) program is to assess the impact of multiple thruster operation on individual thruster and power processor requirements. The areas of thruster startup, steady-state operation, throttling, high voltage recycle, thrust vectoring, and shutdown are of special concern. The results of initial tests are reported.

  7. Fulvic acid-sulfide ion competition for mercury ion binding in the Florida everglades

    USGS Publications Warehouse

    Reddy, M.M.; Aiken, G.R.

    2001-01-01

    Negatively charged functional groups of fulvic acid compete with inorganic sulfide ion for mercury ion binding. This competition is evaluated here by using a discrete site-electrostatic model to calculate mercury solution speciation in the presence of fulvic acid. Model calculated species distributions are used to estimate a mercury-fulvic acid apparent binding constant to quantify fulvic acid and sulfide ion competition for dissolved inorganic mercury (Hg(II)) ion binding. Speciation calculations done with PHREEQC, modified to use the estimated mercury-fulvic acid apparent binding constant, suggest that mercury-fulvic acid and mercury-sulfide complex concentrations are equivalent for very low sulfide ion concentrations (about 10-11 M) in Everglades' surface water. Where measurable total sulfide concentration (about 10-7 M or greater) is present in Everglades' surface water, mercury-sulfide complexes should dominate dissolved inorganic mercury solution speciation. In the absence of sulfide ion (for example, in oxygenated Everglades' surface water), fulvic acid binding should dominate Everglades' dissolved inorganic mercury speciation.

  8. MESSENGER Observations of the Distribution of Planetary Ions Near Mercury

    NASA Astrophysics Data System (ADS)

    Zurbuchen, T.; Raines, J. M.; Slavin, J. A.; Gershman, D. J.; Gilbert, J. A.; Gloeckler, G.; Anderson, B. J.; Baker, D. N.; Korth, H.; Krimigis, S. M.; Sarantos, M.; Schriver, D.; McNutt, R. L.; Solomon, S. C.

    2011-12-01

    We report global observations of the ionized exosphere of Mercury measured by the Fast Imaging Plasma Spectrometer (FIPS) on MESSENGER during the spacecraft's first months in orbit since March 18, 2011. We observe considerable variability, presumably due to changes in the solar wind and heliospheric magnetic field near Mercury, but some large-scale properties were persistent throughout the observation period. Global maps of heavy ion fluxes at Mercury are clearly peaked in the northern cusp region, pointing to the importance of the polar regions as sources of Mercury's ionized exosphere. On the nightside, plasma is regularly observed near equatorial regions. The observed fluxes of He ions are more evenly distributed, indicating a spatially more uniform source of neutral He in Mercury's environment. The observed ion distributions suggest either rapid energization in the inner magnetosphere, to energies greater than 10 keV within only 0.2 Mercury radii, or that ions energized in the magnetosheath or other regions are transported to lower latitudes. We derive densities and temperatures of key constituents using a model-based technique to account for observation geometry and effects of limited field of view. Although, on average, protons dominate by number density, the pressure of Na ions can exceed that of protons in the cusp and nightside equatorial regions. This initial survey of Mercury's plasma ion environment indicates that the mass loading and thermal pressure effects of the heavier planetary ions, especially the oxygen and sodium groups, will be very important, and perhaps even dominant, in determining magnetospheric structure and dynamics.

  9. Ion Transport in Mercury's Magnetosphere during the MESSENGER Flyby

    NASA Astrophysics Data System (ADS)

    Schriver, David; Travnicek, Pavel; Paral, Jan; Slavin, James A.; Sarantos, Menelaos; Anderson, Brian J.; Korth, Haje; Zurbuchen, Thomas H.; Baker, Daniel N.; Killen, Rosemary M.

    2008-09-01

    Abstract Heavy ions including sodium (Na+) are known to populate Mercury's magnetosphere and were observed in situ during the first MESSENGER flyby on January 14, 2008 [1]. A study has been undertaken to examine the transport, distribution, and energization of ions during solar wind conditions corresponding approximately to those that occurred during the MESSENGER flyby. Three-dimensional global hybrid simulations of Mercury's magnetosphere, which provide a realistic self-consistent electric and magnetic field configuration at the time of the flyby [2], are used to trace heavy-ion particle trajectories throughout the system. Because electrons are included only as a massless fluid in the hybrid simulations, electron transport can be examined as well using this technique. To examine solar-wind sputtering as a source for ion ejection from the planet, heavy ions are launched outward from regions near the planet where hybrid simulations show strong particle precipitation, and their trajectories are followed until they either hit the planet or are picked up by the solar wind and lost downstream. The heavy ions can be transported throughout the magnetosphere of Mercury and become accelerated by non-adiabatic processes in the magnetotail current sheet, as well as near reconnection regions. Ions will also be launched from the magnetosheath and other regions to model planetary ion sources as a result of photon-stimulated desorption from the dayside surface of Mercury. The simulated heavy-ion distribution and the energy profile of such ions in Mercury's magnetosphere provide a basis for comparison with MESSENGER flyby data. References [1] Zurbuchen T. H. et al. (2008) Science, in press. [2] Travnicek P. et al. (2007), Geophys. Res. Lett., 34, L05104, doi:10.1029/2006GL028518.

  10. Ion time-of-flight determinations of doubly to singly ionized mercury ion ratios from a mercury electron bombardment discharge

    NASA Technical Reports Server (NTRS)

    Sellen, J. M., Jr.; Kemp, R. F.; Hall, D. F.

    1973-01-01

    Doubly to singly charged mercury ion ratios in electron bombardment ion thruster exhaust beams have been determined as functions of bombardment discharge potential, thrust beam current, thrust beam radial position, acceleration-deceleration voltage ratio, and propellant utilization fraction. A mathematical model for two-step ionization processes has been derived, and calculated ion ratios are compared to observed ratios. Production of Hg(++) appears to result primarily from sequential ionization of Hg(+) in the discharge. Experimental and analytical results are presented, and design, construction, and operation features of an electrostatic deflection ion time-of-flight analyzer for the determination of the above-mentioned ratios are reviewed.

  11. Thermal-environmental testing of a 30-cm engineering model thruster

    NASA Technical Reports Server (NTRS)

    Mirtich, M. J.

    1976-01-01

    An experimental test program was carried out to document all 30-cm electron bombardment Hg ion bombardment thruster functions and characteristics over the thermal environment of several proposed missions. An engineering model thruster was placed in a thermal test facility equipped with -196 C walls and solar simulation. The thruster was cold soaked and exposed to simulated eclipses lasting in duration from 17 to 72 minutes. The thruster was operated at quarter, to full beam power in various thermal configurations which simulated multiple thruster operation, and was also exposed to 1 and 2 suns solar simulation. Thruster control characteristics and constraints; performance, including thrust magnitude and direction; and structural integrity were evaluated over the range of thermal environments tested.

  12. The 15 cm mercury ion thruster research 1975

    NASA Technical Reports Server (NTRS)

    Wilbur, P. J.

    1975-01-01

    Doubly charged ion current measurements in the beam of a SERT II thruster are shown to introduce corrections which bring its calculated thrust into close agreement with that measured during flight testing. A theoretical model of doubly charged ion production and loss in mercury electron bombardment thrusters is discussed and is shown to yield doubly-to-singly charged ion density ratios that agree with experimental measurements obtained on a 15 cm diameter thruster over a range of operating conditions. Single cusp magnetic field thruster operation is discussed and measured ion beam profiles, performance data, doubly charged ion densities, and discharge plasma characteristics are presented for a range of operating conditions and thruster geometries. Variations in the characteristics of this thruster are compared to those observed in the divergent field thruster and the cusped field thruster is shown to yield flatter ion beam profiles at about the same discharge power and propellant utilization operating point. An ion optics test program is described and the measured effects of grid system dimensions on ion beamlet half angle and diameter are examined. The effectiveness of hollow cathode startup using a thermionically emitting filament within the cathode is examined over a range of mercury flow rates and compared to results obtained with a high voltage tickler startup technique. Results of cathode plasma property measurement tests conducted within the cathode are presented.

  13. Response to mercury (II) ions in Methylococcus capsulatus (Bath).

    PubMed

    Boden, Rich; Murrell, J Colin

    2011-11-01

    The mercury (II) ion is toxic and is usually detoxified in Bacteria by reduction to elemental mercury, which is less toxic. This is catalysed by an NAD(P)H-dependent mercuric reductase (EC 1.16.1.1). Here, we present strong evidence that Methylococcus capsulatus (Bath) - a methanotrophic member of the Gammaproteobacteria - uses this enzyme to detoxify mercury. In radiorespirometry studies, it was found that cells exposed to mercury dissimilated 100% of [(14) C]-methane provided to generate reducing equivalents to fuel mercury (II) reduction, rather than the mix of assimilation and dissimilation found in control incubations. The detoxification system is constitutively expressed with a specific activity of 352 (±18) nmol NADH oxidized min(-1) (mg protein)(-1) . Putative mercuric reductase genes were predicted in the M. capsulatus (Bath) genome and found in mRNA microarray studies. The MerA-derived polypeptide showed high identity (> 80%) with MerA sequences from the Betaproteobacteria. PMID:22092810

  14. Scaling relationships for mercury and gaseous propellant ion thrusters

    NASA Technical Reports Server (NTRS)

    Wilbur, P. J.; Kaufman, H. R.

    1978-01-01

    A model describing the doubly charged ion densities in argon and xenon ion thrusters is presented. Doubly charged ions are shown to be produced in significant numbers from both the neutral and singly ionized states. Doubly-to-singly charged ion density ratios calculated using this model are compared to experimental values of this ratio measured in the 15 cm multipole thruster using both propellants. Agreement between theory and experiment is shown to be good. Using this doubly charged ion model, and a similar one obtained previously for mercury, together with the constant neutral loss rate theory, Child's current density law and accelerator grid fabrication limitations, a set of scaling relationships are developed. These relationships show the propellant utilizations, thrust densities and discharge power levels that can be expected as thruster diameter and/or specific impulse are increased and doubly charged ion densities are held at acceptably low values.

  15. 8-cm mercury ion thruster system technology

    NASA Technical Reports Server (NTRS)

    1974-01-01

    The technology status of 8-cm diameter electron bombardment ion thrusters is presented. Much of the technology resulting from the 5-cm diameter thruster has been adapted and improved upon to increase the reliability, durability, and efficiency of the 8-cm thruster. Technology discussed includes: dependence of neutralizer tip erosion upon neutralizer flow rate; impregnated and rolled-foil insert cathode performance and life testing; neutralizer position studies; thruster ion beam profile measurements; high voltage pulse ignition; high utilization ion machined accelerator grids; deposition internal and external to the thruster; thruster vectoring systems; thruster cycling life testing and thruster system weights for typical mission applications.

  16. Thermo-mechanical design aspects of mercury bombardment ion thrusters.

    NASA Technical Reports Server (NTRS)

    Schnelker, D. E.; Kami, S.

    1972-01-01

    The mechanical design criteria are presented as background considerations for solving problems associated with the thermomechanical design of mercury ion bombardment thrusters. Various analytical procedures are used to aid in the development of thruster subassemblies and components in the fields of heat transfer, vibration, and stress analysis. Examples of these techniques which provide computer solutions to predict and control stress levels encountered during launch and operation of thruster systems are discussed. Computer models of specific examples are presented.

  17. Evolution of the 1-mlb mercury ion thruster subsystem

    NASA Technical Reports Server (NTRS)

    Kerslake, W. R.; Banks, B. A.

    1978-01-01

    The developmental history, performance, and major lifetests of each component of the present 1-mlb (4.5 mN) thruster system are traced over the past 10 years. The 1-mlb thruster subsystem consists of an 8 cm diameter ion thruster mounted on 2 axis gimbals, a mercury propellant tank, a power electronics unit, a controller/digital interface unit, and necessary electrical harnesses plus propellant tankage and feed lines.

  18. Ion-scale structure in Mercury's magnetopause reconnection diffusion region

    NASA Astrophysics Data System (ADS)

    Gershman, Daniel J.; Dorelli, John C.; DiBraccio, Gina A.; Raines, Jim M.; Slavin, James A.; Poh, Gangkai; Zurbuchen, Thomas H.

    2016-06-01

    The strength and time dependence of the electric field in a magnetopause diffusion region relate to the rate of magnetic reconnection between the solar wind and a planetary magnetic field. Here we use ~150 ms measurements of energetic electrons from the Mercury Surface, Space Environment, GEochemistry, and Ranging (MESSENGER) spacecraft observed over Mercury's dayside polar cap boundary (PCB) to infer such small-scale changes in magnetic topology and reconnection rates. We provide the first direct measurement of open magnetic topology in flux transfer events at Mercury, structures thought to account for a significant portion of the open magnetic flux transport throughout the magnetosphere. In addition, variations in PCB latitude likely correspond to intermittent bursts of ~0.3-3 mV/m reconnection electric fields separated by ~5-10 s, resulting in average and peak normalized dayside reconnection rates of ~0.02 and ~0.2, respectively. These data demonstrate that structure in the magnetopause diffusion region at Mercury occurs at the smallest ion scales relevant to reconnection physics.

  19. Buffer Gas Experiments in Mercury (Hg+) Ion Clock

    NASA Technical Reports Server (NTRS)

    Chung, Sang K.; Prestage, John D.; Tjoelker, Robert L.; Maleki, Lute

    2004-01-01

    We describe the results of the frequency shifts measured from various buffer gases that might be used as a buffer gas to increase the loading efficiency and cooling of ions trapped in a small mercury ion clock. The small mass, volume and power requirement of space clock precludes the use of turbo pumps. Hence, a hermetically sealed vacuum system, incorporating a suitable getter material with a fixed amount of inert buffer gas may be a practical alternative to the groundbased system. The collision shifts of 40,507,347.996xx Hz clock transition for helium, neon and argon buffer gases were measured in the ambient earth magnetic field. In addition to the above non-getterable inert gases we also measured the frequency shifts due to getterable, molecular hydrogen and nitrogen gases which may be used as buffer gases when incorporated with a miniature ion pump. We also examined the frequency shift due to the low methane gas partial pressure in a fixed higher pressure neon buffer gas environment. Methane gas interacted with mercury ions in a peculiar way as to preserve the ion number but to relax the population difference in the two hyperfine clock states and thereby reducing the clock resonance signal. The same population relaxation was also observed for other molecular buffer gases (N H,) but at much reduced rate.

  20. Development of mercury (II) ion biosensors based on mercury-specific oligonucleotide probes.

    PubMed

    Li, Lanying; Wen, Yanli; Xu, Li; Xu, Qin; Song, Shiping; Zuo, Xiaolei; Yan, Juan; Zhang, Weijia; Liu, Gang

    2016-01-15

    Mercury (II) ion (Hg(2+)) contamination can be accumulated along the food chain and cause serious threat to the public health. Plenty of research effort thus has been devoted to the development of fast, sensitive and selective biosensors for monitoring Hg(2+). Thymine was demonstrated to specifically combine with Hg(2+) and form a thymine-Hg(2+)-thymine (T-Hg(2+)-T) structure, with binding constant even higher than T-A Watson-Crick pair in DNA duplex. Recently, various novel Hg(2+) biosensors have been developed based on T-rich Mercury-Specific Oligonucleotide (MSO) probes, and exhibited advanced selectivity and excellent sensitivity for Hg(2+) detection. In this review, we explained recent development of MSO-based Hg(2+) biosensors mainly in 3 groups: fluorescent biosensors, colorimetric biosensors and electrochemical biosensors. PMID:26356764

  1. Prediction of plasma properties in mercury ion thrusters

    NASA Technical Reports Server (NTRS)

    Longhurst, G. R.

    1978-01-01

    A simplified theoretical model was developed which obtains to first order the plasma properties in the discharge chamber of a mercury ion thruster from basic thruster design and controllable operating parameters. The basic operation and design of ion thrusters is discussed, and the important processes which influence the plasma properties are described in terms of the design and control parameters. The conservation for mass, charge and energy were applied to the ion production region, which was defined as the region of the discharge chamber having as its outer boundary the surface of revolution of the innermost field line to intersect the anode. Mass conservation and the equations describing the various processes involved with mass addition and removal from the ion production region are satisfied by a Maxwellian electron density spatial distribution in that region.

  2. Physical phenomena in mercury ion thrusters

    NASA Technical Reports Server (NTRS)

    Wilbur, P. J.

    1979-01-01

    Experimental tests results demonstrating that reductions in screen grid thickness enhance the performance of ion thruster grids are presented. Shaping of the screen hole cross section is shown on the other hand not to affect performance substantially. The effect of the magnetic field in the vicinity of the hollow cathode on cathode performance is studied and test results are presented that show reductions in keeper voltages of a few volts can be realized by judicious applications of fields on the order of 100 gauss. The plasma downstream of a SERT 2 thruster operating without high voltage is studied. A model describing electron escape from the thruster under these conditions is discussed. A model defining the performance of the baffle aperture of an ion thruster is refined and experimental verification of the model is undertaken.

  3. Note: Production of a mercury beam with an electron cyclotron resonance ion source

    SciTech Connect

    Vondrasek, R.; Pardo, R.; Scott, R.

    2013-11-15

    An electron cyclotron resonance ion source has been utilized to produce mercury beams with intensities of 4.5 eμA of {sup 202}Hg{sup 29+} and 3.0 eμA of {sup 202}Hg{sup 31+} from natural abundance mercury metal. The production technique relies on the evaporation of liquid mercury into the source plasma vacuum region and utilizes elemental mercury instead of a volatile organic compound as the neutral feed material.

  4. Stimulation of erythrocyte phosphatidylserine exposure by mercury ions

    SciTech Connect

    Eisele, Kerstin; Lang, Philipp A.; Kempe, Daniela S.; Klarl, Barbara A.; Niemoeller, Olivier; Wieder, Thomas; Huber, Stephan M.; Duranton, Christophe; Lang, Florian . E-mail: florian.lang@uni-tuebingen.de

    2006-01-15

    The sequelae of mercury intoxication include induction of apoptosis. In nucleated cells, Hg{sup 2+}-induced apoptosis involves mitochondrial damage. The present study has been performed to elucidate effects of Hg{sup 2+} in erythrocytes which lack mitochondria but are able to undergo apoptosis-like alterations of the cell membrane. Previous studies have documented that activation of a Ca{sup 2+}-sensitive erythrocyte scramblase leads to exposure of phosphatidylserine at the erythrocyte surface, a typical feature of apoptotic cells. The erythrocyte scramblase is activated by osmotic shock, oxidative stress and/or energy depletion which increase cytosolic Ca{sup 2+} activity and/or activate a sphingomyelinase leading to formation of ceramide. Ceramide sensitizes the scramblase to Ca{sup 2+}. The present experiments explored the effect of Hg{sup 2+} ions on erythrocytes. Phosphatidylserine exposure after mercury treatment was estimated from annexin binding as determined in FACS analysis. Exposure to Hg{sup 2+} (1 {mu}M) indeed significantly increased annexin binding from 2.3 {+-} 0.5% (control condition) to 23 {+-} 6% (n = 6). This effect was paralleled by activation of a clotrimazole-sensitive K{sup +}-selective conductance as measured by patch-clamp recordings and by transient cell shrinkage. Further experiments revealed also an increase of ceramide formation by {approx}66% (n = 7) after challenge with mercury (1 {mu}M). In conclusion, mercury ions activate a clotrimazole-sensitive K{sup +}-selective conductance leading to transient cell shrinkage. Moreover, Hg{sup 2+} increases ceramide formation. The observed mechanisms could similarly participate in the triggering of apoptosis in nucleated cells by Hg{sup 2+}.

  5. Mercury Ion Clock for a NASA Technology Demonstration Mission.

    PubMed

    Tjoelker, Robert L; Prestage, John D; Burt, Eric A; Chen, Pin; Chong, Yong J; Chung, Sang K; Diener, William; Ely, Todd; Enzer, Daphna G; Mojaradi, Hadi; Okino, Clay; Pauken, Mike; Robison, David; Swenson, Bradford L; Tucker, Blake; Wang, Rabi

    2016-07-01

    There are many different atomic frequency standard technologies but only few meet the demanding performance, reliability, size, mass, and power constraints required for space operation. The Jet Propulsion Laboratory is developing a linear ion-trap-based mercury ion clock, referred to as DSAC (Deep-Space Atomic Clock) under NASA's Technology Demonstration Mission program. This clock is expected to provide a new capability with broad application to space-based navigation and science. A one-year flight demonstration is planned as a hosted payload following an early 2017 launch. This first-generation mercury ion clock for space demonstration has a volume, mass, and power of 17 L, 16 kg, and 47 W, respectively, with further reductions planned for follow-on applications. Clock performance with a signal-to-noise ratio (SNR)*Q limited stability of 1.5E-13/τ(1/2) has been observed and a fractional frequency stability of 2E-15 at one day measured (no drift removed). Such a space-based stability enables autonomous timekeeping of with a technology capable of even higher stability, if desired. To date, the demonstration clock has been successfully subjected to mechanical vibration testing at the 14 grms level, thermal-vacuum operation over a range of 42(°)C, and electromagnetic susceptibility tests. PMID:27019481

  6. A dual-mode turn-on fluorescent BODIPY-based probe for visualization of mercury ions in living cells.

    PubMed

    Wang, Yue; Pan, Fuchao; Zhang, Yuanlin; Peng, Fangfang; Huang, Zhentao; Zhang, Weijuan; Zhao, Weili

    2016-08-01

    A novel turn-on fluorescent 8-amino BODIPY-based probe carrying a thiourea unit as the mercury ion recognition unit has been developed. Due to the cascade reaction processes, consecutive color changes reflecting the electronic absorption and emission responses were observed upon addition of increased concentrations of mercury(ii) ions. The likely sensing mechanism was proposed as mercury ion-promoted cyclization and subsequent hydrolysis. The probe displayed a selective response to mercury ions over other metal ions. Additionally, experiments with living Human Hepatoma SMMC-7721 cells to visualize intracellular mercury ions in biological systems were carried out with the probe. PMID:27251011

  7. Recent developments and proposed schemes for trapped ion frequency standards. [trapped mercury ions for microwave and optical frequency standards

    NASA Technical Reports Server (NTRS)

    Maleki, L.

    1982-01-01

    Ion traps are exciting candidates as future precision frequency sources. Recent developments demonstrate that mercury ion frequency standards are capable of a stability performance comparable to commercial cesium standards. There is, however, considerable room for improvement with regard to the signal to noise problem. The 40 GHz microwave frequency implies that a careful design should be implemented to ensure the elimination of the unwanted side bands in the microwave pump signal. A long life, high performance light source to be used in a trapped mercury ion microwave standard must be developed and the long term performance of a trapped mercury ion microwave standard must be investigated. While newly proposed two photon pumping schemes in conjuction with mercury ions promise exciting developments for both microwave and optical frequency standards, other ions that may be potential candidates should be evaluated for their usefulness.

  8. Cycle Time Reduction in Trapped Mercury Ion Atomic Frequency Standards

    NASA Technical Reports Server (NTRS)

    Burt, Eric A.; Tjoelker, Robert L.; Taghavi, Shervin

    2011-01-01

    The use of the mercury ion isotope (201)Hg(+) was examined for an atomic clock. Taking advantage of the faster optical pumping time in (201)Hg(+) reduces both the state preparation and the state readout times, thereby decreasing the overall cycle time of the clock and reducing the impact of medium-term LO noise on the performance of the frequency standard. The spectral overlap between the plasma discharge lamp used for (201)Hg(+) state preparation and readout is much larger than that of the lamp used for the more conventional (199)Hg(+). There has been little study of (201)Hg(+) for clock applications (in fact, all trapped ion clock work in mercury has been with (199)Hg(+); however, recently the optical pumping time in (201)Hg(+) has been measured and found to be 0.45 second, or about three times faster than in (199)Hg(+) due largely to the better spectral overlap. This can be used to reduce the overall clock cycle time by over 2 seconds, or up to a factor of 2 improvement. The use of the (201)Hg(+) for an atomic clock is totally new. Most attempts to reduce the impact of LO noise have focused on reducing the interrogation time. In the trapped ion frequency standards built so far at JPL, the optical pumping time is already at its minimum so that no enhancement can be had by shortening it. However, by using (201)Hg(+), this is no longer the case. Furthermore, integrity monitoring, the mechanism that determines whether the clock is functioning normally, cannot happen faster than the clock cycle time. Therefore, a shorter cycle time will enable quicker detection of failure modes and recovery from them.

  9. Ion beam plume and efflux measurements of an 8-cm mercury ion thruster

    NASA Technical Reports Server (NTRS)

    Komatsu, G. K.; Sellen, J. M., Jr.; Zafran, S.

    1978-01-01

    Measurements of the ion beam plume and efflux constituents of an 8-cm mercury ion thruster have been carried out in the TRW 5 x 10 foot testing chamber. Charged components (ion beam plume) were measured with an array of movable position Faraday cups and retarding potential analyzers yielding both current density and particle energy determinations. Neutral components (ion beam efflux) were determined with a movable position ionization gauge. Measurements of the ion beam plume were performed for a thruster both with and without a sputter shield. Analysis of data in terms of normalized effluxes has been carried out and has been applied to an example calculation of efflux compatibility with a communications spacecraft.

  10. Mercury

    MedlinePlus

    ... button batteries. Mercury salts may be used in skin creams and ointments. It's also used in many industries. Mercury in the air settles into water. It can pass through the food chain and build up in ...

  11. Ultrasensitive quantum dot fluorescence quenching assay for selective detection of mercury ions in drinking water.

    PubMed

    Ke, Jun; Li, Xinyong; Zhao, Qidong; Hou, Yang; Chen, Junhong

    2014-01-01

    Mercury is one of the most acutely toxic substances at trace level to human health and living thing. Developing a rapid, cheap and water soluble metal sensor for detecting mercury ions at ppb level remains a challenge. Herein, a metal sensor consisting of MPA coated Mn doped ZnSe/ZnS colloidal nanoparticles was utilized to ultrasensitively and selectively detect Hg(2+) ions with a low detection limit (0.1 nM) over a dynamic range from 0 to 20 nM. According to strong interaction between thiol(s) and mercury ions, mercaptopropionic acid (MPA) was used as a highly unique acceptor for mercury ions in the as-obtained ultrasensitive sensor. In the presence of mercury ions, colloidal nanoparticles rapidly agglomerated due to changes of surface chemical properties, which results in severe quenching of fluorescent intensity. Meanwhile, we find that the original ligands are separated from the surface of colloidal nanoparticles involving strongly chelation between mercury ion and thiol(s) proved by controlled IR analysis. The result shows that the QD-based metal ions sensor possesses satisfactory precision, high sensitivity and selectivity, and could be applied for the quantification analysis of real samples. PMID:25005836

  12. Ultrasensitive Quantum Dot Fluorescence quenching Assay for Selective Detection of Mercury Ions in Drinking Water

    PubMed Central

    Ke, Jun; Li, Xinyong; Zhao, Qidong; Hou, Yang; Chen, Junhong

    2014-01-01

    Mercury is one of the most acutely toxic substances at trace level to human health and living thing. Developing a rapid, cheap and water soluble metal sensor for detecting mercury ions at ppb level remains a challenge. Herein, a metal sensor consisting of MPA coated Mn doped ZnSe/ZnS colloidal nanoparticles was utilized to ultrasensitively and selectively detect Hg2+ ions with a low detection limit (0.1 nM) over a dynamic range from 0 to 20 nM. According to strong interaction between thiol(s) and mercury ions, mercaptopropionic acid (MPA) was used as a highly unique acceptor for mercury ions in the as-obtained ultrasensitive sensor. In the presence of mercury ions, colloidal nanoparticles rapidly agglomerated due to changes of surface chemical properties, which results in severe quenching of fluorescent intensity. Meanwhile, we find that the original ligands are separated from the surface of colloidal nanoparticles involving strongly chelation between mercury ion and thiol(s) proved by controlled IR analysis. The result shows that the QD-based metal ions sensor possesses satisfactory precision, high sensitivity and selectivity, and could be applied for the quantification analysis of real samples. PMID:25005836

  13. Ultrasensitive Quantum Dot Fluorescence quenching Assay for Selective Detection of Mercury Ions in Drinking Water

    NASA Astrophysics Data System (ADS)

    Ke, Jun; Li, Xinyong; Zhao, Qidong; Hou, Yang; Chen, Junhong

    2014-07-01

    Mercury is one of the most acutely toxic substances at trace level to human health and living thing. Developing a rapid, cheap and water soluble metal sensor for detecting mercury ions at ppb level remains a challenge. Herein, a metal sensor consisting of MPA coated Mn doped ZnSe/ZnS colloidal nanoparticles was utilized to ultrasensitively and selectively detect Hg2+ ions with a low detection limit (0.1 nM) over a dynamic range from 0 to 20 nM. According to strong interaction between thiol(s) and mercury ions, mercaptopropionic acid (MPA) was used as a highly unique acceptor for mercury ions in the as-obtained ultrasensitive sensor. In the presence of mercury ions, colloidal nanoparticles rapidly agglomerated due to changes of surface chemical properties, which results in severe quenching of fluorescent intensity. Meanwhile, we find that the original ligands are separated from the surface of colloidal nanoparticles involving strongly chelation between mercury ion and thiol(s) proved by controlled IR analysis. The result shows that the QD-based metal ions sensor possesses satisfactory precision, high sensitivity and selectivity, and could be applied for the quantification analysis of real samples.

  14. 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, ... colorless, odorless gas. It also combines with other elements to form powders or crystals. Mercury is in ...

  15. Thermal Characterization of a NASA 30-cm Ion Thruster Operated up to 5 kW

    NASA Technical Reports Server (NTRS)

    SarverVerhey, Timothy R.; Domonkos, Matthew T.; Patterson, Michael J.

    2001-01-01

    A preliminary thermal characterization of a newly-fabricated NSTAR-derived test-bed thruster has recently been performed. The temperature behavior of the rare-earth magnets are reported because of their critical impact on thruster operation. The results obtained to date showed that the magnet temperatures did not exceed the stabilization Emit during thruster operation up to 4.6 kW. Magnet temperature data were also obtained for two earlier NSTAR Engineering Model Thrusters and are discussed in this report. Comparison between these thrusters suggests that the test-bed engine in its present condition is able to operate safely at higher power because of the lower discharge losses over the entire operating power range of this engine. However, because of the 'burn-in' behavior of the NSTAR thruster, magnet temperatures are expected to increase as discharge losses increase with accumulated thruster operation. Consequently, a new engineering solution may be required to achieve 5-kW operation with acceptable margin.

  16. Evaluation of Selective Ion Exchange Resins for Removal of Mercury from the H-Area Water Treatment Unit

    SciTech Connect

    Serkiz, S.M.

    2000-09-05

    This study investigated the ability of seven ion exchange (IX) resins, some of which were mercury specific, to remove mercury in H-Area WTU waters from three sources (Reverse Osmosis (RO) Feed, RO Permeate from Train A, and a mercury ''hot spot'' extraction well HEX 18). Seven ion exchange resins, including ResinTech CG8 and Dowex 21K (the cation and anion exchange resins currently used at the H-Area WTU) were screened against five alternative ion exchange materials plus an experimental blank. Mercury decontamination factors (DFs), mercury breakthrough, and post-test contaminant concentrations of IX resins were determined for each IX material tested.

  17. Design, fabrication and testing of porous tungsten vaporizers for mercury ion thrusters

    NASA Technical Reports Server (NTRS)

    Zavesky, R.; Kroeger, E.; Kami, S.

    1983-01-01

    The dispersions in the characteristics, performance and reliability of vaporizers for early model 30-cm thrusters were investigated. The purpose of the paper is to explore the findings and to discuss the approaches that were taken to reduce the observed dispersion and present the results of a program which validated those approaches. The information that is presented includes porous tungsten materials specifications, a discussion of assembly procedures, and a description of a test program which screens both material and fabrication processes. There are five appendices providing additional detail in the areas of vaporizer contamination, nitrogen flow testing, bubble testing, porosimeter testing, and mercury purity. Four neutralizers, seven cathodes and five main vaporizers were successfully fabricated, tested, and operated on thrusters. Performance data from those devices is presented and indicates extremely repeatable results from using the design and fabrication procedures.

  18. Results of the mission profile life test. [for J-series mercury ion engines

    NASA Technical Reports Server (NTRS)

    Bechtel, R. T.; Trump, G. E.; James, E. L.

    1982-01-01

    Seven J series 30-cm diameter thrusters have been tested in segments of up to 5,070 hr, for 14,541 hr in the Mission Profile Life Test facility. Test results have indicated the basic thruster design to be consistent with the lifetime goal of 15,000 hr at 2-A beam. The only areas of concern identified which appear to require additional verification testing involve contamination of mercury propellant isolators, which may be due to facility constituents, and the ability of specially covered surfaces to contain sputtered material and prevent flake formation. The ability of the SCR, series resonant inverter power processor to operate the J series thruster and autonomous computer control of the thruster/processor system were demonstrated.

  19. MESSENGER Observations of the Spatial Distribution of Planetary Ions Near Mercury

    NASA Technical Reports Server (NTRS)

    Zurbuchen, Thomas H.; Raines, Jim M.; Slavin, James A.; Gershman, Daniel J.; Gilbert, Jason A.; Gloeckler, George; Anderson, Brian J.; Baker, Daniel N.; Korth, Haje; Krimigis, Stamatios M.; Sarantos, Menelaos; Schriver, David; McNutt, Ralph L., Jr.; Solomon, Sean C.

    2011-01-01

    Global measurements by MESSENGER of the fluxes of heavy ions at Mercury, particularly sodium (Na(+)) and oxygen (O(+)), exhibit distinct maxima in the northern magnetic-cusp region, indicating that polar regions are important sources of Mercury's ionized exosphere, presumably through solar-wind sputtering near the poles. The observed fluxes of helium (He(+)) are more evenly distributed, indicating a more uniform source such as that expected from evaporation from a helium-saturated surface. In some regions near Mercury, especially the nightside equatorial region, the Na(+) pressure can be a substantial fraction of the proton pressure.

  20. Mercury Loss, Annealing and Ion Implantation in Mercury-Cadmium - Telluride.

    NASA Astrophysics Data System (ADS)

    Dimiduk, Kathryn Conway

    Mercury Cadmium Telluride (HG(,1-x)Cd(,x)Te) is a variable bandgap semiconductor that has important applications as an infrared detector. However, its processing is hampered by defect doping and Hg loss at low temperatures. This work reports studies of the HG loss and applies the information to annealing of epitaxial Hg(,1-x)Cd(,x)Te. Samples of Hg(,1-x)Cd(,x)Te of various compositions were heated to 250-430(DEGREES)C for times of 3-500 seconds in a thermal pulse annealing system. Rutherford backscattering spectrometry (RBS) with MeV He ions can resolve near surface Hg atoms from Cd and Te atoms. The Hg lost from these anneals can therefore be quantified by taking the difference of RBS spectra obtained before and after heating. An empirical fit to the equation Hg atoms lost/cm('2)-sec = A exp ( -(DELTA)E/kT) was found, where A and (DELTA)E depend on composition and surface preparation and k and T are Boltzmann's constant and temperature respectively. Various models for Hg loss are discussed and the binding energy of Hg in Hg(,1-x)Cd(,x)Te is computed. The above measurements provide the basis for determining the temperature-time trade off in Hg loss when annealing uncapped HgCdTe. The thermal pulse annealing system has permitted access to a regime intermediate between that of furnaces and lasers. Anneals at 260(DEGREES)C for 7 -8 seconds were found to improve the crystal quality of as grown epitaxial Hg(,.64)Cd(,.36)Te as observed by MeV He ion channeling. Similar anneals also repaired the crystal damage caused by a 250 keV 10('15)/cm('2) ('11)B implant into epitaxial HgCdTe held at LN(,2) temperatures. Van der Pauw Hall measurements showed type conversion following implantation, and increased mobility and carrier concentrations following annealing. A diode fabricated in this material exhibited a very sharp I-V curve with reverse breakdown occurring at 12 V and an R(,0)A of (GREATERTHEQ) 10('7) (OMEGA) cm('2) at 77K. Preliminary results obtained using SnO(,2) and Cd

  1. Trace mercury ion determination based on the highly selective redox reaction between stannous ion and mercury ion enhanced by gold nanoparticles

    NASA Astrophysics Data System (ADS)

    Zhang, Pingping; Chen, Shu; Kang, Yangfang; Long, Yunfei

    2012-12-01

    A novel resonance light scattering (RLS) spectrometric method for mercury ions (Hg2+) determination has been established in this article. Mercury (Hg) nanoparticle formed from the highly selective redox reaction between citrate-stabilized stannous ions (Sn2+) and Hg2+. As a result, the RLS intensities of the system can be enhanced and it can be sensitized in the presence of very little amount of gold nanoparticles (AuNPs). According to this phenomenon, trace Hg2+ in real water sample has been determined directly by RLS spectrometry. It has been found that the enhanced RLS intensities (ΔIRLS) characterized at 395 nm are proportional to the concentration of Hg2+ in the range of 0.1-30 μmol L-1 with a detection limit (3σ) of 0.051 μmol L-1. The method described herein has good sensitivity, selectivity, and without complicated sample pretreatment. Moreover, the feasibility for the analysis of Hg2+ in a wastewater sample was identified with a good recovery (100.2-106.3%).

  2. Mercury

    MedlinePlus

    ... be found in: Batteries Chemistry labs Some disinfectants Folk remedies Red cinnabar mineral Organic mercury can be ... heart tracing Fluids through a vein (by IV) Medicine to treat symptoms The type of exposure will ...

  3. Biocrusts serve as biomarkers for the upper 30 cm soil water content

    NASA Astrophysics Data System (ADS)

    Kidron, Giora J.; Benenson, Itzhak

    2014-02-01

    Knowledge regarding the spatial distribution of moisture in soil is of great importance especially in arid regions where water is scarce. Following a previous research that showed a significant relationship between daylight surface wetness duration and the average chlorophyll content of 5 biocrusts in the Negev Desert (Israel), and the resultant outcome that pointed to the possible use of biocrusts as biomarkers for surface wetness duration, we hypothesize that biocrusts may also serve as biomarkers for the moisture content of the upper soil layer. Toward this end, daylight surface wetness duration was measured at 5 crust types following rain events during 1993-1995 along with periodical soil sampling of the upper 30 cm (at 5 cm intervals) of the soil profiles underlying these biocrusts. The findings showed a positive linear relationship between daylight surface wetness duration and the chlorophyll content of the crusts (r2 = 0.96-0.97). High correlations were also found between daylight surface wetness duration and the available water content (r2 = 0.96) and duration (r2 = 0.85-0.88) of the upper 30 cm soil and between the chlorophyll content of the crust and the available water content (r2 = 0.93-0.96) and duration (r2 = 0.78-0.84). Topography-induced shading and slope position (which determined additional water either by runoff or subsurface flow) are seen responsible for the clear link between subsurface moisture content, daylight surface wetness duration and chlorophyll content of the crust. This link points to the possible use of biocrusts as biomarkers for subsurface water content and highlights the importance of crust typology and mapping for the study of the spatial distribution of water and their potential use for the study of ecosystem structure and function.

  4. Mercury

    NASA Astrophysics Data System (ADS)

    Taylor, G. J.; Scott, E. R. D.

    2003-12-01

    Mercury is an important part of the solar system puzzle, yet we know less about it than any other planet, except Pluto. Mercury is the smallest of the terrestrial planets (0.05 Earth masses) and the closest to the Sun. Its relatively high density (5.4 g cm -3) indicates that it has a large metallic core (˜3/4 of the planet's radius) compared to its silicate mantle and crust. The existence of a magnetic field implies that the metallic core is still partly molten. The surface is heavily cratered like the highlands of the Moon, but some areas are smooth and less cratered, possibly like the lunar maria (but not as dark). Its surface composition, as explained in the next section, appears to be low in FeO (only ˜3 wt.%), which implies that either its crust is anorthositic (Jeanloz et al., 1995) or its mantle is similarly low in FeO ( Robinson and Taylor, 2001).The proximity of Mercury to the Sun is particularly important. In one somewhat outmoded view of how the solar system formed, Mercury was assembled in the hottest region close to the Sun so that virtually all of the iron was in the metallic state, rather than oxidized to FeO (e.g., Lewis, 1972, 1974). If correct, Mercury ought to have relatively a low content of FeO. This hypothesis also predicts that Mercury should have high concentrations of refractory elements, such as calcium, aluminum, and thorium, and low concentrations of volatile elements, such as sodium and potassium, compared to the other terrestrial planets.Alternative hypotheses tell a much more nomadic and dramatic story of Mercury's birth. In one alternative view, wandering planetesimals that might have come from as far away as Mars or the inner asteroid belt accreted to form Mercury (Wetherill, 1994). This model predicts higher FeO and volatile elements than does the high-temperature model, and similar compositions among the terrestrial planets. The accretion process might have been accompanied by a monumental impact that stripped away much of the

  5. Complexation of mercury(II) ions with humic acids in tundra soils

    NASA Astrophysics Data System (ADS)

    Vasilevich, R. S.; Beznosikov, V. A.; Lodygin, E. D.; Kondratenok, B. M.

    2014-03-01

    The interaction mechanisms of mercury(II) ions with preparations of humic acids (HAs) isolated from organic horizons of surface-gleyed soils (Haplic Stagnosol (Gelic, Siltic)) of shrub tundra and hydromorphic peat gley soils (Histic Cryosol (Reductaquic, Siltic)) of moss-lichen tundra have been studied. The particular features of the interactions between the mercury(II) ions and the HAs are related to the molecular structure of the HAs, the mercury concentration range, and the environmental parameters. The fixation of mercury(II) ions into stable coordination compounds is most efficient in the pH range of 2.5-3.5. At the element concentrations below 0.50 μmol/dm3, the main complexing sites of HAs are their peripheral aminoacid functional groups. Pyrocatechol, salicylate, and phenolic groups from the nuclear moiety of molecules interact in the concentration range of 0.0005-0.50 mmol/dm3; the physical sorption of mercury hydroxo complexes by the surface of HAs is the main process occurring in the system.

  6. How to Directly Image a Habitable Planet Around Alpha Centauri with a 30cm Space Telescope.

    NASA Astrophysics Data System (ADS)

    Belikov, R.; Bendek, E.; Thomas, S.; Black, D.

    2014-12-01

    More than 1,700 exoplanets have been discovered to date, including a handful of potentially habitable ones. There is on average more than one planet per star, and estimates of occurrence rates for potentially habitable planets (eta_Earth) from the Kepler mission range between 5 and 50%. Several mission concepts have been studied to directly image planets around nearby stars. Direct imaging enables spectroscopic detection of biomarkers such as atmospheric oxygen and methane, which would be highly suggestive of extraterrestrial life. It is commonly thought that directly imaging a potentially habitable exoplanet requires telescopes with apertures of at least 1m, costing at least $1B, and launching no earlier than the 2020s. A notable exception to this is Alpha Centauri. The system contains two Sun-like stars with a wide separation that allows dynamically stable habitable zones around either star. Habitable zones span about 0.5-1" in stellocentric angle, 3x wider than around any other FGKM star. A 30cm visible light space telescope is sufficient to resolve the habitable zone and detect a potentially habitable planet in minutes with ideal components, or days with realistic ones. We are developing a mission concept called ACEND (Alpha Centauri Direct Imager) consisting of a 30cm primary, a Phase-Induced Amplitude Apodization coronagraph, and a wavefront control system. It is designed to suppress the light leak from both stars and directly image their planetary systems in 3 color channels, including the capability to detect potentially habitable planets. Color imaging is sufficient to differentiate Venus-like, Earth-like, and Mars-like planets from each other and establish the presence of Earth-pressure atmosphere through Rayleigh scattering. Two factors make it possible to realize the requirements of ACEND (most notably 10^10 contrast) on a small budget and fast schedule: (a) ACEND will collect a long continuous sequence of images on Alpha Centauri A and B for 2 years

  7. Diagnostic system design for the Ion Auxiliary Propulsion System (IAPS). Flight tests of two 8 cm mercury ion

    NASA Technical Reports Server (NTRS)

    Hurst, E. B.; Thomas, G. Z.

    1981-01-01

    The mechanical, thermal, electrical design and the ground test results of four types of detectors are explained. The DSS is designed to measure the thruster efflux material deposition and S/C potential relative to the local plasma in the vicinity of two 8 cm mercury ion thrusters. The DSS consists of two quartz crystal microbalance (QCM) detectors, one potential probe, nine solar cell arrays, seven ion collectors and two electronic packages.

  8. Detection of mercury ions based on mercury-induced switching of enzyme-like activity of platinum/gold nanoparticles.

    PubMed

    Tseng, Chao-Wei; Chang, Hsiang-Yu; Chang, Jia-Yaw; Huang, Chih-Ching

    2012-11-01

    In this study, bimetallic platinum/gold nanoparticles (Pt/Au NPs) were found to exhibit peroxidase-like activity, and the deposition of mercury was found to switch the enzymatic activity to a catalase-like activity. Based on this phenomenon, we developed a new method for detecting mercury ions through their deposition on bimetallic Pt/Au NPs to switch the catalytic activity of Pt/Au NPs. Pt/Au NPs could be easily prepared through reduction of Au(3+) and Pt(4+) by sodium citrate in a one-pot synthesis. The peroxidase catalytic activity of the Pt/Au NPs was controlled by varying the ratios of Pt to Au. The Pt(0.1)/Au NPs (prepared with a [Au(3+)]/[Pt(4+)] molar ratio of 9.0/1.0) showed excellent oxidation catalysis for H(2)O(2)-mediated oxidation of Amplex® Red (AR) to resorufin. The oxidized product of AR, resorufin, fluoresces more strongly (excitation/emission wavelength maxima ca. 570/585 nm) than AR alone. The peroxidase catalytic activity of Pt(0.1)/Au NPs was switched to catalase-like activity in the presence of mercury ions in a 5.0 mM tris(hydroxymethyl)aminomethane (Tris)-borate solution (pH 7.0) through the deposition of Hg on the particle surfaces owing to the strong Hg-Au metallic bond. The catalytic activity of Hg-Pt(0.1)/Au NPs is superior (by at least 5-fold) to that of natural catalase (from bovine liver). Under optimal solution conditions [5.0 mM Tris-borate (pH 7.0), H(2)O(2) (50 mM), and AR (10 μM)] and in the presence of the masking agents polyacrylic acid and tellurium nanowires, the Pt(0.1)/Au NPs allowed the selective detection of inorganic mercury (Hg(2+)) and methylmercury ions (MeHg(+)) at concentrations as low as several nanomolar. This simple, fast, and cost-effective system enabled selective determination of the spiked concentrations of Hg(2+) and MeHg(+) in tap, pond, and stream waters. PMID:23011048

  9. TADPOLE satellite. [low cost synchronous orbit satellite to evaluate small mercury bombardment ion thruster applications

    NASA Technical Reports Server (NTRS)

    1974-01-01

    A low cost synchronous orbit satellite to evaluate small mercury bombardment ion thruster applications is described. The ion thrusters provide the satellite with precise north-south and east-west stationkeeping capabilities. In addition, the thrusters are used to unload the reaction wheels used for attitude control and for other purposes described in the report. The proposed satellite is named TADPOLE. (Technology Application Demonstration Program of Low Energy).

  10. D-penicillamine-templated copper nanoparticles via ascorbic acid reduction as a mercury ion sensor.

    PubMed

    Lin, Shu Min; Geng, Shuo; Li, Na; Li, Nian Bing; Luo, Hong Qun

    2016-05-01

    Mercury ion is one of the most hazardous metal pollutants that can cause deleterious effects on human health and the environment even at low concentrations. It is necessary to develop new mercury detection methods with high sensitivity, specificity and rapidity. In this study, a novel and green strategy for synthesizing D-penicillamine-capped copper nanoparticles (DPA-CuNPs) was successfully established by a chemical reduction method, in which D-penicillamine and ascorbic acid were used as stabilizing agent and reducing agent, respectively. The as-prepared DPA-CuNPs showed strong red fluorescence and had a large Stoke's shift (270nm). Scanning electron microscopy, transmission electron microscopy, Fourier-transform infrared spectroscopy, fluorescence spectroscopy, and ultraviolet-visible spectrophotometry were utilized to elucidate the possible fluorescence mechanism, which could be aggregation-induced emission effect. Based on the phenomenon that trace mercury ion can disperse the aggregated DPA-CuNPs, resulting in great fluorescence quench of the system, a sensitive and selective assay for mercury ion in aqueous solution with the DPA-CuNPs was developed. Under optimum conditions, this assay can be applied to the quantification of Hg(2+) in the 1.0-30μM concentration range and the detection limit (3σ/slope) is 32nM. The method was successfully applied to determine Hg(2+) in real water samples. PMID:26946016

  11. 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.

  12. Detection of mercury ions based on mercury-induced switching of enzyme-like activity of platinum/gold nanoparticles

    NASA Astrophysics Data System (ADS)

    Tseng, Chao-Wei; Chang, Hsiang-Yu; Chang, Jia-Yaw; Huang, Chih-Ching

    2012-10-01

    In this study, bimetallic platinum/gold nanoparticles (Pt/Au NPs) were found to exhibit peroxidase-like activity, and the deposition of mercury was found to switch the enzymatic activity to a catalase-like activity. Based on this phenomenon, we developed a new method for detecting mercury ions through their deposition on bimetallic Pt/Au NPs to switch the catalytic activity of Pt/Au NPs. Pt/Au NPs could be easily prepared through reduction of Au3+ and Pt4+ by sodium citrate in a one-pot synthesis. The peroxidase catalytic activity of the Pt/Au NPs was controlled by varying the ratios of Pt to Au. The Pt0.1/Au NPs (prepared with a [Au3+]/[Pt4+] molar ratio of 9.0/1.0) showed excellent oxidation catalysis for H2O2-mediated oxidation of Amplex® Red (AR) to resorufin. The oxidized product of AR, resorufin, fluoresces more strongly (excitation/emission wavelength maxima ca. 570/585 nm) than AR alone. The peroxidase catalytic activity of Pt0.1/Au NPs was switched to catalase-like activity in the presence of mercury ions in a 5.0 mM tris(hydroxymethyl)aminomethane (Tris)-borate solution (pH 7.0) through the deposition of Hg on the particle surfaces owing to the strong Hg-Au metallic bond. The catalytic activity of Hg-Pt0.1/Au NPs is superior (by at least 5-fold) to that of natural catalase (from bovine liver). Under optimal solution conditions [5.0 mM Tris-borate (pH 7.0), H2O2 (50 mM), and AR (10 μM)] and in the presence of the masking agents polyacrylic acid and tellurium nanowires, the Pt0.1/Au NPs allowed the selective detection of inorganic mercury (Hg2+) and methylmercury ions (MeHg+) at concentrations as low as several nanomolar. This simple, fast, and cost-effective system enabled selective determination of the spiked concentrations of Hg2+ and MeHg+ in tap, pond, and stream waters.In this study, bimetallic platinum/gold nanoparticles (Pt/Au NPs) were found to exhibit peroxidase-like activity, and the deposition of mercury was found to switch the enzymatic

  13. Small Mercury Ion Clock for On-board Spacecraft Navigation

    NASA Technical Reports Server (NTRS)

    Prestage, John D.; Chung, Sang; Le, Thanh; Hamell, R.; Maleki, Lute; Tjoelker, Robert

    2004-01-01

    I.Small Ion Clock Approach and Heritage: a) No lasers, uwave cavities, cryogenics, atomic beams, etc. b) Ions are electrically shuttled between separate optical and microwave traps. II. Each trap is optimized for its task: quadrupole for optical state selection; multi-pole for microwave clock. a) Very good stability shown in USNO. Timescale running "open loop." III. "Open loop" operation means no self-measurements of frequency offsets: (Zeeman, ion temperature,... etc.) a) Fewer parts and procedures, produces stable output continuously. IV. Ion clock is not so sensitive to temperature fluctuations a) Measured u:nshielded temperature coefficient of few 10(exp -15) per C. b) No bulky temperature isolation needed.

  14. A Proposed Apparatus to Study the Impact of Solar Wind Ions on the Surfaces of Mercury, the Moon, and Asteroids

    NASA Astrophysics Data System (ADS)

    Savin, D. W.; Domingue, D. L.; Miller, K. A.

    2015-11-01

    We propose to construct a unique instrument to study the effects of solar wind ion irradiation on the regolith surfaces of Mercury, the Moon, and asteroids. Our approach will overcome many of the limitations of past work.

  15. Integrating a DNA Strand Displacement Reaction with a Whispering Gallery Mode Sensor for Label-Free Mercury (II) Ion Detection.

    PubMed

    Wu, Fengchi; Wu, Yuqiang; Niu, Zhongwei; Vollmer, Frank

    2016-01-01

    Mercury is an extremely toxic chemical pollutant of our environment. It has attracted the world's attention due to its high mobility and the ease with which it accumulates in organisms. Sensitive devices and methods specific for detecting mercury ions are, hence, in great need. Here, we have integrated a DNA strand displacement reaction with a whispering gallery mode (WGM) sensor for demonstrating the detection of Hg(2+) ions. Our approach relies on the displacement of a DNA hairpin structure, which forms after the binding of mercury ions to an aptamer DNA sequence. The strand displacement reaction of the DNA aptamer provides highly specific and quantitative means for determining the mercury ion concentration on a label-free WGM sensor platform. Our approach also shows the possibility for manipulating the kinetics of a strand displacement reaction with specific ionic species. PMID:27483277

  16. Compact Microwave Mercury Ion Clock for Space Applications

    NASA Technical Reports Server (NTRS)

    Prestage, John D.; Tu, Meirong; Chung, Sang K.; MacNeal, Paul

    2007-01-01

    We review progress in developing a small Hg ion clock for space operation based on breadboard ion-clock physics package where Hg ions are shuttled between a quadrupole and a 16-pole rf trap. With this architecture we have demonstrated short-term stability approx.1-2x10(exp -13) at 1 second, averaging to 10-15 at 1 day. This development shows that H-maser quality stabilities can be produced in a small clock package, comparable in size to an ultra-stable quartz oscillator required or holding 1-2x10(exp -13) at 1 second. We have completed an ion clock physics package designed to withstand vibration of launch and are currently building a approx. 1 kg engineering model for test. We also discuss frequency steering software algorithms that simultaneously measure ion signal size and lamp light output, useful for long term operation and self-optimization of microwave power and return engineering data.

  17. Accelerated life test of sputtering and anode deposit spalling in a small mercury ion thruster

    NASA Technical Reports Server (NTRS)

    Power, J. L.

    1975-01-01

    Tantalum and molybdenum sputtered from discharge chamber components during operation of a 5 centimeter diameter mercury ion thruster adhered much more strongly to coarsely grit blasted anode surfaces than to standard surfaces. Spalling of the sputtered coating did occur from a coarse screen anode surface but only in flakes less than a mesh unit long. The results were obtained in a 200 hour accelerated life test conducted at an elevated discharge potential of 64.6 volts. The test approximately reproduced the major sputter erosion and deposition effects that occur under normal operation but at approximately 75 times the normal rate. No discharge chamber component suffered sufficient erosion in the test to threaten its structural integrity or further serviceability. The test indicated that the use of tantalum-surfaced discharge chamber components in conjunction with a fine wire screen anode surface should cure the problems of sputter erosion and sputtered deposits spalling in long term operation of small mercury ion thrusters.

  18. A rhodamine B-based fluorescent sensor toward highly selective mercury (II) ions detection.

    PubMed

    Jiao, Yang; Zhang, Lei; Zhou, Peng

    2016-04-01

    This work presented the design, syntheses and photophysical properties of a rhodamine B-based fluorescence probe, which exhibited a sensitive and selective recognition towards mercury (II). The chemosensor RA (Rhodamine- amide- derivative) contained a 5-aminoisophthalic acid diethyl ester and a rhodamine group, and the property of spirolactone of this chemosensor RA was detected by X-ray crystal structure analyses. Chemosensor RA afforded turn-on fluorescence enhancement and displayed high brightness for Hg(2+), which leaded to the opening of the spirolactone ring and consequently caused the appearance of strong absorption at visible range, moreover, the obvious and characteristic color changed from colorless to pink was observed. We envisioned that the chemosensor RA exhibited a considerable specificity with two mercury (II) ions which was attributed to the open of spirolactone over other interference metal ions. PMID:26838376

  19. Neon as a Buffer Gas for a Mercury-Ion Clock

    NASA Technical Reports Server (NTRS)

    Prestage, John; Chung, Sang

    2008-01-01

    A developmental miniature mercury-ion clock has stability comparable to that of a hydrogen-maser clock. The ion-handling components are housed in a sealed vacuum tube, wherein a getter pump is used to maintain the partial vacuum, and the evacuated tube is backfilled with mercury vapor in a buffer gas. Neon was determined to be the best choice for the buffer gas: The pressure-induced frequency pulling by neon was found to be only about two-fifths of that of helium. Furthermore, because neon diffuses through solids much more slowly than does helium, the operational lifetime of a tube backfilled with neon could be considerably longer than that of a tube backfilled with helium.

  20. Eight-cm mercury ion thruster system technology

    NASA Technical Reports Server (NTRS)

    1974-01-01

    The technology status of 8 cm diameter electron bombardment ion thrusters is presented. Much of the technology resulting from the 5 cm diameter thruster has been adapted and improved upon to increase the reliability, durability, and efficiency of the 8 cm thruster. Technology discussed includes: dependence of neutralizer tip erosion upon neutralizer flow rate; impregnated and rolled-foil insert cathode performance and life testing; neutralizer position studies; thruster ion beam profile measurements; high voltage pulse ignition; high utilization ion machined accelerator grids; deposition internal and external to the thruster; thruster vectoring systems; thruster cycling life testing and thruster system weights for typical mission applications.

  1. Optical frequency standards based on mercury and aluminum ions

    NASA Astrophysics Data System (ADS)

    Itano, W. M.; Bergquist, J. C.; Brusch, A.; Diddams, S. A.; Fortier, T. M.; Heavner, T. P.; Hollberg, L.; Hume, D. B.; Jefferts, S. R.; Lorini, L.; Parker, T. E.; Rosenband, T.; Stalnaker, J. E.

    2007-09-01

    Single-trapped-ion frequency standards based on a 282 nm transition in 199Hg+ and on a 267 nm transition in 27Al + have been developed at NIST over the past several years. Their frequencies are measured relative to each other and to the NIST primary frequency standard, the NIST-F1 cesium fountain, by means of a self-referenced femtosecond laser frequency comb. Both ion standards have demonstrated instabilities and inaccuracies of less than 1 × 10 -16.

  2. Double ion production in mercury thrusters. M.S. Thesis

    NASA Technical Reports Server (NTRS)

    Peters, R. R.

    1976-01-01

    The development of a model which predicts doubly charged ion density is discussed. The accuracy of the model is shown to be good for two different thruster sizes and a total of 11 different cases. The model indicates that in most cases more than 80% of the doubly charged ions are produced from singly charged ions. This result can be used to develop a much simpler model which, along with correlations of the average plasma properties, can be used to determine the doubly charged ion density in ion thrusters with acceptable accuracy. Two different techniques which can be used to reduce the doubly charged ion density while maintaining good thruster operation, are identified as a result of an examination of the simple model. First, the electron density can be reduced and the thruster size then increased to maintain the same propellant utilization. Second, at a fixed thruster size, the plasma density, temperature and energy can be reduced and then to maintain a constant propellant utilization the open area of the grids to neutral propellant loss can be reduced through the use of a small hole accelerator grid.

  3. A 7700 hour endurance test of a 30-cm Kaufman thruster

    NASA Technical Reports Server (NTRS)

    Collett, C. R.

    1975-01-01

    This paper describes an ongoing endurance test of the ion thruster which is expected to form the basis of future prime propulsion systems. The purpose of the test is to demonstrate the lifetime capability of such critical components as cathodes, vaporizers, isolators, and optics. The endurance test was preceded by development of an ion engine life test system and several intermediate duration tests. The elements of the test system are briefly described and the thruster modifications which resulted from the intermediate tests are evaluated in terms of the endurance test results. Thruster performance during the endurance test is described as well as the conclusions that can be drawn from the 8600 hours that have been completed as of March 6, 1975.

  4. A FRET based aptasensor coupled with non-enzymatic signal amplification for mercury (II) ion detection.

    PubMed

    Chu-Mong, Ketsarin; Thammakhet, Chongdee; Thavarungkul, Panote; Kanatharana, Proespichaya; Buranachai, Chittanon

    2016-08-01

    In this work, the idea of incorporating a non-enzymatic signal amplification with a regular aptasensor was tested. In this proof of principle, the sensor was designed for the detection of mercury (II) ions (Hg(2+)) based on the Förster Resonance Energy Transfer (FRET), and the catalyzed hairpin assembly (CHA) technique that was used as the signal amplification method. This sensor comprised a mercury aptamer-catalyst complex (Apt-C) and two types of hairpin DNA: H1 labeled with fluorescein and H2 labeled with tetramethylrhodamine. In the presence of Hg(2+), two facing thymine bases in the mercury aptamer strand were coordinated with one mercury ion. This caused the release of the catalyst for the catalyzed hairpin assembly (CHA) reaction that turned H1 and H2 hairpins into H1-H2 hybrids. FRET was then used to report the hairpin-duplex transformation. The sensor showed excellent specificity towards Hg(2+) over other possible interfering cations present at even a 100 fold greater concentrations. It had a linear range of 10.0-200.0nM, and a good detection limit of 7.03±0.18nM, which is lower than the regulatory mercury limit for drinking water (10nM or 2ppb). The sensor was used to detect spiked Hg(2+) in nine real surface water samples collected from three different areas. Acceptable recoveries and small standard deviations indicated that the sensor was practically applicable, and the proposed idea to incorporate a CHA amplification in a regular aptasensor was not only feasible but beneficial. The same principles can be applied to develop sensors for various different targets. PMID:27216687

  5. Sputter erosion and deposition in the discharge chamber of a small mercury ion thruster

    NASA Technical Reports Server (NTRS)

    Power, J. L.

    1973-01-01

    A 5-cm diameter mercury ion thruster similar to one tested for 9715 hours was operated approximately 400 hrs each at discharge voltages of 36.6, 39.6, and 42.6 V, with corresponding discharge propellant utilizations of 58, 68, and 70 percent. The observed sputter erosion rates of the internal thruster parts and the anode weight gain rate all rose rapidly with discharge voltage and were roughly in the ratio of 1:3:5 for the three voltages. The combined weight loss of the internal thruster parts nearly balanced the anode weight gain. Hg+2 ions apparently caused most of the observed erosion.

  6. Sputter erosion and deposition in the discharge chamber of a small mercury ion thruster

    NASA Technical Reports Server (NTRS)

    Power, J. L.

    1973-01-01

    A 5 cm diameter mercury ion thruster similar to one tested for 9715 hours was operated approximately 400 hrs each at discharge voltages of 36.6, 39.6, and 42.6 V, with corresponding discharge propellant utilizations of 58, 68, and 70 percent. The observed sputter erosion rates of the internal thruster parts and the anode weight gain rate all rose rapidly with discharge voltage and were roughly in the ratio of 1:3:5 for the three voltages. The combined weight loss of the internal thruster parts nearly balanced the anode weight gain. Hg(+2) ion apparently caused most of the observed erosion.

  7. Cusped magnetic field mercury ion thruster. Ph.D. Thesis

    NASA Technical Reports Server (NTRS)

    Beattie, J. R.

    1976-01-01

    The importance of a uniform current density profile in the exhaust beam of an electrostatic ion thruster is discussed in terms of thrust level and accelerator system lifetime. A residence time approach is used to explain the nonuniform beam current density profile of the divergent magnetic field thruster. Mathematical expressions are derived which relate the thruster discharge power loss, propellant utilization, and double to single ion density ratio to the geometry and plasma properties of the discharge chamber. These relationships are applied to a cylindrical discharge chamber model of the thruster. Experimental results are presented for a wide range of the discharge chamber length. The thruster designed for this investigation was operated with a cusped magnetic field as well as a divergent field geometry, and the cusped field geometry is shown to be superior from the standpoint of beam profile uniformity, performance, and double ion population.

  8. Aluminum, boron, and mercury measurement via ion-exchange direct current argon plasma (DCAP) spectrometry

    SciTech Connect

    Maxwell, S.L. III

    1985-01-01

    The accurate measurement of aluminum, boron, and mercury in process dissolver solutions at the Savannah River Plant (SRP) is important. Costs for the processing of non-SRP uranium fuels are based in part on the measured aluminum content of the fuel. Boron is a nuclear safety control in some dissolutions and mercury(II) is a catalyst in the dissolution of uranium-plutonium oxide fuels. In analyses, ion exchange is used for selective separations and for removing high activity constituents in dissolver solutions prior to measurement via direct current argon plasma (DCAP) spectrometry. Aluminum is separated via anion exchange using oxalate-hydrochloric acid mixtures, boron is separated via cation exchange using 0.05 M nitric acid, and mercury(II) is separated via cation exchange using 40% ethanol-0.2 M hydrochloric acid. The aluminum content is measured with a precision of better than +-1.0% (RSD) using gravimetric dilutions and sample measurements bracketted by standard measurements. Boron and mercury are measured with a precision of better than +-3.0% (RSD) using volumetric dilutions. 4 refs., 4 tabs.

  9. Compact Microwave Mercury Ion Clock for Space Applications

    NASA Technical Reports Server (NTRS)

    Prestage, John D.; Tu, Meirong; Chung, Sang K.; MacNeal, Paul

    2008-01-01

    We have recently completed a breadboard ion-clock physics package based on Hg ions shuttled between a quadrupole and a 16-pole rf trap. With this architecture we have demonstrated short-term stability approximately 1 - 2 x 10(exp -13) at 1 second, averaging to 10(exp -15) at 1 day. This development shows that H-maser quality stabilities can be produced in a small clock package, comparable in size to an ultra-stable quartz oscillator required for holding 1 - 2 x 10(exp -13) at 1 second. This performance was obtained in a sealed vacuum configuration where only a getter pump was used to maintain vacuum. The vacuum tube containing the traps has now been under sealed vacuum conditions for nearly three years with no measurable degradation of ion trapping lifetimes or clock short-term performance. We have fabricated the vacuum tube, ion trap and UV windows from materials that will allow an approximately 400 C bake-out to prepare for tube seal-off. This approach to the vacuum follows the methods used in flight vacuum tube electronics, such as flight TWTA's where tube operation lifetime and shelf life of up to 15 years is achieved.

  10. Progress on Small Mercury Ion Clock for Space Applications

    NASA Technical Reports Server (NTRS)

    Prestage, John D.; Chung, Sang K.; Thompson, Robert J.; MacNeal, Paul

    2009-01-01

    We have recently completed a breadboard ion-clock physics package based on Hg ions shuttled between a quadrupole and a 16-pole rf trap. With this architecture we have demonstrated short-term stability approx.1-2x10-(sup 1)(sup 3) at 1 second, averaging to 10-(sup 1)? at 1 day. This development shows that H-maser quality stabilities can be produced in a small clock package, comparable in size to an ultra-stable quartz oscillator required for holding 1-2x10-(sup 1)(sup 3) at 1 second. This performance was obtained in a sealed vacuum configuration where only a getter pump was used to maintain vacuum. The vacuum tube containing the traps has now been under sealed vacuum conditions for over three years with no measurable degradation of ion trapping lifetimes or clock short-term performance. We have fabricated the vacuum tube, ion trap and UV windows from materials that will allow approx. 400 deg C bake-out to prepare for tube seal-off. This approach to the vacuum follows the methods used in flight vacuum tube electronics, such as flight TWTA's where tube operation lifetime and shelf life of up to 15 years is achieved.

  11. Compact Microwave Mercury Ion Clock for Deep-Space Applications

    NASA Technical Reports Server (NTRS)

    Prestage, John D.; Chung, Sang K.; Lim, Lawrence; Matevosian, Annond

    2007-01-01

    We have recently completed a breadboard ion-dock physics package based on Kg ions shuttled between a quadrupole and a 16-pole rf trap. With this architecture we have demonstrated short-term stability -1-2xl0-13 at 1 second, averaging to 10-15 at 1 day. This development shows that 8- maser quality stabilities can be produced in a small clock package, comparable in size to an oItra-stable quartz oscillator required for holding 1-2xl0-13 at 1 second. This performance was obtained in a sealed vacuum configuration where only agetter pump was used to maintain vacuum. The vacuum tube containing the traps has now been onder sealed vacuum conditions for nearly two years with no measurable degradation of ion trapping lifetimes or clock short-term performance. We have fabricated the vacuum tube, ion trap and UV windows from materials that will allow a - 400 C tube bake-out to prepare for tube sealoff. This approach to the vacuum follows the methods used in mght vacuum tube electronics, such as flight TWTA's where tube operation lifetime and shelf life of up to 15 years is achieved. We use neon as a buffer gas with 2-3 times less pressure induced frequency pulling than helium and, being heavier, negligable diffusion losses will occur over the operation lifetime.

  12. Mercury(II) ion-selective electrodes based on p-tert-butyl calix[4]crowns with imine units.

    PubMed

    Mahajan, Rakesh Kumar; Kaur, Ravneet; Kaur, Inderpreet; Sharma, Vandana; Kumar, Manoj

    2004-05-01

    A PVC membrane incorporating p-tert-butyl calix[4]crown with imine units as an ionophore was prepared and used in an ion-selective electrode for the determination of mercury(II) ions. An electrode based on this ionophore showed a good potentiometric response for mercury(II) ions over a wide concentration range of 5.0 x 10(-5) - 1.0 x 10(-1) M with a near-Nernstian slope of 27.3 mV per decade. The detection limit of the electrode was 2.24 x 10(-5) M and the electrode worked well in the pH range of 1.3 - 4.0. The electrode showed a short response time of less than 20 s. The electrode also showed better selectivity for mercury(II) ions over many of the alkali (Na+, -1.69; K+, -1.54), alkaline-earth (Ca2+, -3.30; Ba2+, -3.32), and heavy metal ions (Co2+, -3.67; Ni2+, -3.43; Pb2+, -3.31; Fe3+, -1.82). Ag+ ion was found to be the strongest interfering ion. Also, sharp end points were obtained when the sensor was used as an indicator electrode for the potentiometric titration of mercury(II) ions with iodide and dichromate ions. PMID:15171285

  13. Evolution of the 1-mlb mercury ion thruster subsystem

    NASA Technical Reports Server (NTRS)

    Kerslake, W. R.; Banks, B. A.

    1978-01-01

    A general description and review of the auxiliary Electric Propulsion program, which led to the present 1-mlb (4.5 mN) thruster system, is presented. The developmental history, performance, and major lifetests of each component of the system are traced over the past 10 years. Major components include the 8-cm diameter ion thruster, the power processor, and the propellant reservoir and distribution system.

  14. Miniaturized Mercury Ion Clock for Ultrastable Deep Space Applications

    NASA Technical Reports Server (NTRS)

    Prestage, John D.; Chung, Sang; Lim, Lawrence; Le, Thanh

    2006-01-01

    We have recently completed a prototype ion-clock physics package based on Hg ions shuttled between a quadrupole and a 16-pole rf trap. With this architecture we have demonstrated short-term stability 2-3x10-13 at 1 second, averaging to 10-15 at 1 day. This development shows that H-maser quality stabilities can be produced in a small clock package, comparable in size to an ultra-stable quartz oscillator required for holding 1-2x10-13 at 1 second. This performance was obtained in a sealed vacuum configuration where only a getter pump was used to maintain vacuum. The vacuum tube containing the traps has now been under sealed vacuum conditions for nearly 1.5 years with no measurable degradation of ion trapping lifetimes or clock short-term performance. Because the tube is sealed, the Hg source and Neon buffer gas are held indefinitely, for the life of the tube. There is no consumption of Hg in this system unlike in a Cs beam tube where lifetime is often limited by Cs depletion.

  15. Characterization through global hybrid simulations of solar wind ions impacting the dayside of Mercury

    NASA Astrophysics Data System (ADS)

    Chanteur, Gérard M.; Modolo, Ronan; Hess, Sébastien; Leblanc, François; Richer, Emilie

    2014-05-01

    It has long been suspected since Mariner-10 observations that solar wind ions could reach the surface of Mercury: Kallio & Janhunen (2003) and Travnicek et al (2010) have presented simulated maps of precipitating proton fluxes. Attempts to refine estimations of precipitating fluxes of solar wind ions are important as these precipitations create additional sources of exospheric and possibly magnetospheric populations, and as their space-weathering effects modify the properties of the regolith. We run the global hybrid model used by Richer et al. (2012) which takes self-consistently into account the alpha particles of the solar wind to estimate fluxes of solar wind protons and alphas impacting the surface of Mercury under different IMF conditions. The internal source of the Hermean magnetic field is axisymmetric and is the superposition of a dipole and a quadrupole consistent with MESSENGER observations (Anderson et al., 2011) as in Richer et al. (2012). Results are briefly compared to predictions made with the offset dipole model of the planetary field. New simulations, made with an improved spatial resolution of 40km, reveal important differences between proton and alpha fluxes and show large variations with interplanetary conditions. In a first step we investigate the properties of solar wind ions impacting the dayside of the planet, precipitations on the night side will be examined later in a second step. References Anderson et al., Science, 333 , 1859, (2011) Kallio, E., and P. Janhunen, Solar wind and magnetospheric ion impact on Mercury's surface, Geophys. Res. Lett., 30(17), 1877, doi:10.1029/2003GL017842, 2003. Travnicek, P.M., D. Schriver, P. Hellinger, D. Hercik, B.J. Anderson, M. Sarantos, and J.A.Slavin, Mercury's magnetosphere-solar wind interaction for northward and southward interplanetary magnetic field: Hybrid simulation results, Icarus, doi:10.1016/j.icarus.2010.01.008, 2010 Richer, E., R. Modolo, G. M. Chanteur, S. Hess, and F. Leblanc (2012), A

  16. Pulse ignition characterization of mercury ion thruster hollow cathode using an improved pulse ignitor

    NASA Technical Reports Server (NTRS)

    Wintucky, E. G.; Gruber, R. P.

    1978-01-01

    An investigation of the high voltage pulse ignition characteristics of the 8-cm mercury ion thruster neutralizer cathode identified a low rate of voltage rise and long pulse duration as desirable factors for reliable cathode starting. Cathode starting breakdown voltages were measured over a range of mercury flow rates and tip heater powers for pulses with five different rates of voltage rise. Breakdown voltage requirements for the fastest rising pulse (2.5 to 3.0 kV/microsec) were substantially higher (2 kV or more) than for the slowest rising pulse (0.3 to 0.5 kV/microsec) for the same starting conditions. The paper also describes an improved, low impedance pulse ignitor circuit which reduces power losses and eliminates problems with control and packaging associated with earlier designs.

  17. Pulse ignition characterization of mercury ion thruster hollow cathode using an improved pulse ignitor

    NASA Technical Reports Server (NTRS)

    Wintucky, E. G.; Gruber, R. P.

    1978-01-01

    An investigation of the high voltage pulse ignition characteristics of the 8 cm mercury ion thruster neutralizer cathode identified a low rate of voltage rise and long pulse duration as desirable factors for reliable cathode starting. Cathode starting breakdown voltages were measured over a range of mercury flow rates and tip heater powers for pulses with five different rates of voltage rise. Breakdown voltage requirements for the fastest rising pulse (2.5 to 3.0 kV/micro sec) were substantially higher (2 kV or more) than for the slowest rising pulse (0.3 to 0.5 kV/micro sec) for the same starting conditions. Also described is an improved, low impedance pulse ignitor circuit which reduces power losses and eliminates problems with control and packaging associated with earlier designs.

  18. On the Effect of IMF Turning on Ion Dynamics at Mercury

    NASA Technical Reports Server (NTRS)

    Delcourt, D. C.; Moore, T. E.; Fok, M.-C. H.

    2011-01-01

    We investigate the effect of a rotation of the Interplanetary Magnetic Field (IMF) on the transport of magnetospheric ion populations at Mercury. We focus on ions of planetary origin and investigate their large-scale circulation using three-dimensional single-particle simulations. We show that a nonzero Bx component of the IMF leads to a pronounced asymmetry in the overall circulation pattern . In particular, we demonstrate that the centrifugal acceleration due to curvature of the E x B drift paths is more pronounced in one hemisphere than the other, leading to filling of the magnetospheric lobes and plasma sheet with more or less energetic material depending upon the hemisphere of origin. Using a time-varying electric and magnetic field model, we investigate the response of ions to rapid (a few tens of seconds) re-orientation of the IMF. We show that, for ions with gyroperiods comparable to the field variation time scale, the inductive electric field should lead to significant nonadiabatic energization, up to several hundreds of eVs or a few keVs. It thus appears that IMP turning at Mercury should lead to localized loading of the magnetosphere with energetic material of planetary origin (e.g., Na+).

  19. Shedding light on the mercury mass discrepancy by weighing Hg 52+ ions in a Penning trap

    NASA Astrophysics Data System (ADS)

    Fritioff, T.; Bluhme, H.; Schuch, R.; Bergström, I.; Björkhage, M.

    2003-07-01

    In their nuclear tables Audi and Wapstra have pointed out a serious mass discrepancy between their extrapolated values for the mercury isotopes and those from a direct measurement by the Manitoba group. The values deviate by as much as 85 ppb from each other with claimed uncertainties of about 16 and 7 ppb, respectively. In order to decide which values are correct the masses of the 198Hg and 204Hg isotopes have been measured in the Stockholm Penning trap mass spectrometer SMILETRAP using 52+ ions. This charge state corresponds to a filled Ni electron configuration for which the electron binding energy can be accurately calculated. The mass values obtained are 197.966 768 44(43) u for 198Hg and 203.973 494 10(39) u for 204Hg. These values agree with those measured by the Manitoba group, with a 3 times lower uncertainty. This measurement was made possible through the implementation of a cooling technique of the highly charged mercury ions during charge breeding in the electron beam ion source used for producing the Hg 52+ ions.

  20. Cycle life testing of 8-cm mercury ion thruster cathodes

    NASA Technical Reports Server (NTRS)

    Wintucky, E. G.

    1976-01-01

    Two main cathodes have successfully completed 2800 and 1980 cycles and three neutralizers, 3928, 3050, and 2850 cycles in ongoing cycle life tests of flight-type cathode-isolator-vaporizer and neutralizer-isolator-vaporizer assemblies for the 4.45 mN 8-cm Hg ion thruster system. Each cycle included one hour of cathode operation. Starting and operating conditions simulated those expected in a typical auxiliary propulsion mission duty cycle. The cycle life test results are presented along with results of an insert comparison test which led to the selection of a rolled foil insert type for the 8-cm Engineering Model Thruster cathodes.

  1. Reversible photoswitching specifically responds to mercury(II) ions: the gated photochromism of bis(dithiazole)ethene.

    PubMed

    Wu, Yue; Zhu, Weihong; Wan, Wei; Xie, Yongshu; Tian, He; Li, Alexander D Q

    2014-11-25

    Photoswitching of bis(dithiazole)ethene can be regulated by Hg(II) ions and EDTA in a "lock-and-unlock" manner. The molecular photoswitch provides an enzyme-like binding pocket that selectively binds specifically to mercury ions, thus modulating the degree of photoswitching in its presence. PMID:25283709

  2. Coulometric generation of hydrogen ions by oxidation of mercury in methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone.

    PubMed

    Mihajlović, R P; Joksimović, V M; Mihajlović, Lj V

    2003-11-01

    Mercury(II)-chloride reacts with anhydrous methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone in a precise stoichiometry ratio (1:2), and weakly ionized compounds of mercury with ketones are formed and equivalent quantity of HCl is released. The application of a mercury anode for the quantitative generation of H(+) ions in 0.25 M sodium perchlorate in anhydrous methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone has been investigated. Current/potentials curves for the solvents, titrated bases, indicator and mercury showed that in these solvents mercury is oxidized at potentials much more negative than those for the titrated bases and other components present in the solution. The protons generated in this way have been used for the titration of some organic bases, with either visual or potentiometric end-point detection. The oxidation of mercury in methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone and the reaction of mercury ions with these solvents have been found to proceed with 100% current efficiency. PMID:18969192

  3. [The coagulation characteristics of human oxyhemoglobin in the presence of a mercury (II) ion in a neutral phosphate buffer].

    PubMed

    Bogdanova, L D; Myshkin, A E

    1990-01-01

    The kinetics of human oxyhemoglobin coagulation in neutral phosphate buffer in the presence of mercury acetate at 20 degrees has been studied using turbidimetric methods. The addition of small amounts of concentrated Hg2+ solution leads to rapid local protein coagulation with subsequent dissolution of the formed coagulate. Coagulation can be inhibited by addition of Tris that binds to mercury ions. The pattern of oxyhemoglobin coagulation is determined by molar Hg2+/protein ration rather than by total Hg2+ concentration. PMID:2362035

  4. Planned flight test of a mercury ion auxiliary propulsion system. II - Integration with host spacecraft

    NASA Technical Reports Server (NTRS)

    Knight, R. M.

    1978-01-01

    This is part II of a three-part paper describing the approved flight test of a mercury ion auxiliary propulsion system. The objectives of the flight test are summarized with reference to user application. The approach to accomplishment is presented as it applies to integrating the propulsion system with the host spacecraft, USAF's STP P80-1. A number of known interface design considerations which affect the propulsion system and the spacecraft are discussed. Finally, analogies are drawn comparing the relationship of the organizations involved with this flight test with those anticipated for future operational missions. Attention is given to the viewpoint of the project office

  5. Ratiometric fluorescence chemosensor based on tyrosine derivatives for monitoring mercury ions in aqueous solutions.

    PubMed

    Thirupathi, Ponnaboina; Saritha née Gudelli, Ponnaboina; Lee, Keun-Hyeung

    2014-09-28

    Ratiometric fluorescent chemosensors 1 and 2 were synthesized based on tyrosine amino acid derivatives with a pyrene fluorophore. 1 and 2 showed high selectivity for Hg(II) ions among 13 metal ions in aqueous solutions. Both 1 and 2 sensitively detected Hg(II) ions in aqueous solutions by ratiometric response without interference of any of the other tested metal ions including Cu(II), Cd(II), Pb(II), and Ag(I) ions. 1 and 2 had tight binding affinities (5.72 × 10(13) M(−2), 1.15 × 10(13) M(−2)) for Hg(II) with nano-molar detection limits. The binding mode was characterized with the help of organic spectroscopic data, which revealed that the methoxyphenyl moieties of 1 and 2 played a vital role in the coordination of Hg(II). The deprotonation of the sulfonamide group is not a critical process for the binding of mercury ions. The methoxyphenyl moiety, sulfonamide group, and the C-terminal amide moiety of 1 and 2 as ligands for Hg(II) played crucial roles in the stabilization of the 2:1 complexes. PMID:25092444

  6. Structure and dynamics of Mercury's magnetospheric cusp: MESSENGER measurements of protons and planetary ions

    NASA Astrophysics Data System (ADS)

    Raines, Jim M.; Gershman, Daniel J.; Slavin, James A.; Zurbuchen, Thomas H.; Korth, Haje; Anderson, Brian J.; Solomon, Sean C.

    2014-08-01

    The MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft has observed the northern magnetospheric cusp of Mercury regularly since the probe was inserted into orbit about the innermost planet in March 2011. Observations from the Fast Imaging Plasma Spectrometer (FIPS) made at altitudes < 400 km in the planet's cusp have shown average proton densities (>10 cm-3) that are exceeded only by those observed in the magnetosheath. These high plasma densities are also associated with strong diamagnetic depressions observed by MESSENGER's Magnetometer. Plasma in the cusp may originate from several sources: (1) Direct inflow from the magnetosheath, (2) locally produced planetary photoions and ions sputtered off the surface from solar wind impact and then accelerated upward, and (3) flow of magnetosheath and magnetospheric plasma accelerated from dayside reconnection X-lines. We surveyed 518 cusp passes by MESSENGER, focusing on the spatial distribution, energy spectra, and pitch-angle distributions of protons and Na+-group ions. Of those, we selected 77 cusp passes during which substantial Na+-group ion populations were present for a more detailed analysis. We find that Mercury's cusp is a highly dynamic region, both in spatial extent and plasma composition and energies. From the three-dimensional plasma distributions observed by FIPS, protons with mean energies of 1 keV were found flowing down into the cusp (i.e., source (1) above). The distribution of pitch angles of these protons showed a depletion in the direction away from the surface, indicating that ions within 40° of the magnetic field direction are in the loss cone, lost to the surface rather than being reflected by the magnetic field. In contrast, Na+-group ions show two distinct behaviors depending on their energy. Low-energy (100-300 eV) ions appear to be streaming out of the cusp, showing pitch-angle distributions with a strong component antiparallel to the magnetic field (away

  7. A biphasic mercury-ion sensor: exploiting microfluidics to make simple anilines competitive ligands.

    PubMed

    Petzoldt, Martin; Eschenbaum, Carsten; Schwaebel, S Thimon; Broedner, Kerstin; Lemmer, Uli; Hamburger, Manuel; Bunz, Uwe H F

    2015-10-01

    Combining the molecular wire effect with a biphasic sensing approach (analyte in water, sensor-dye in 2-methyltetrahydrofuran) and a microfluidic flow setup leads to the construction of a mercury-sensitive module. We so instantaneously detect Hg(2+) ions in water at a 500 μM concentration. The sensor, conjugated non-water soluble polymer 1 (XFPF), merely supports dibutylaniline substituents as binding units. Yet, selective and sensitive detection of Hg(2+) -ions is achieved in water. The enhancement in sensory response, when comparing the reference compound 2 to that of 1 in a biphasic system in a microfluidic chip is >10(3) . By manipulation of the structure of 1, further powerful sensor systems should be easily achieved. PMID:26387876

  8. Indirect Determination of Mercury Ion by Inhibition of a Glucose Biosensor Based on ZnO Nanorods

    PubMed Central

    Chey, Chan Oeurn; Ibupoto, Zafar Hussain; Khun, Kimleang; Nur, Omer; Willander, Magnus

    2012-01-01

    A potentiometric glucose biosensor based on immobilization of glucose oxidase (GOD) on ZnO nanorods (ZnO-NRs) has been developed for the indirect determination of environmental mercury ions. The ZnO-NRs were grown on a gold coated glass substrate by using the low temperature aqueous chemical growth (ACG) approach. Glucose oxidase in conjunction with a chitosan membrane and a glutaraldehyde (GA) were immobilized on the surface of the ZnO-NRs using a simple physical adsorption method and then used as a potentiometric working electrode. The potential response of the biosensor between the working electrode and an Ag/AgCl reference electrode was measured in a 1mM phosphate buffer solution (PBS). The detection limit of the mercury ion sensor was found to be 0.5 nM. The experimental results provide two linear ranges of the inhibition from 0.5 × 10−6 mM to 0.5 × 10−4 mM, and from 0.5 × 10−4 mM to 20 mM of mercury ion for fixed 1 mM of glucose concentration in the solution. The linear range of the inhibition from 10−3 mM to 6 mM of mercury ion was also acquired for a fixed 10 mM of glucose concentration. The working electrode can be reactivated by more than 70% after inhibition by simply dipping the used electrode in a 10 mM PBS solution for 7 min. The electrodes retained their original enzyme activity by about 90% for more than three weeks. The response to mercury ions was highly sensitive, selective, stable, reproducible, and interference resistant, and exhibits a fast response time. The developed glucose biosensor has a great potential for detection of mercury with several advantages such as being inexpensive, requiring minimum hardware and being suitable for unskilled users. PMID:23202200

  9. Indirect determination of mercury ion by inhibition of a glucose biosensor based on ZnO nanorods.

    PubMed

    Chey, Chan Oeurn; Ibupoto, Zafar Hussain; Khun, Kimleang; Nur, Omer; Willander, Magnus

    2012-01-01

    A potentiometric glucose biosensor based on immobilization of glucose oxidase (GOD) on ZnO nanorods (ZnO-NRs) has been developed for the indirect determination of environmental mercury ions. The ZnO-NRs were grown on a gold coated glass substrate by using the low temperature aqueous chemical growth (ACG) approach. Glucose oxidase in conjunction with a chitosan membrane and a glutaraldehyde (GA) were immobilized on the surface of the ZnO-NRs using a simple physical adsorption method and then used as a potentiometric working electrode. The potential response of the biosensor between the working electrode and an Ag/AgCl reference electrode was measured in a 1mM phosphate buffer solution (PBS). The detection limit of the mercury ion sensor was found to be 0.5 nM. The experimental results provide two linear ranges of the inhibition from 0.5 × 10(-6) mM to 0.5 × 10(-4) mM, and from 0.5 × 10(-4) mM to 20 mM of mercury ion for fixed 1 mM of glucose concentration in the solution. The linear range of the inhibition from 10(-3) mM to 6 mM of mercury ion was also acquired for a fixed 10 mM of glucose concentration. The working electrode can be reactivated by more than 70% after inhibition by simply dipping the used electrode in a 10 mM PBS solution for 7 min. The electrodes retained their original enzyme activity by about 90% for more than three weeks. The response to mercury ions was highly sensitive, selective, stable, reproducible, and interference resistant, and exhibits a fast response time. The developed glucose biosensor has a great potential for detection of mercury with several advantages such as being inexpensive, requiring minimum hardware and being suitable for unskilled users. PMID:23202200

  10. Surface Plasmon Resonance Sensing Detection of Mercury and Lead Ions Based on Conducting Polymer Composite

    PubMed Central

    Abdi, Mahnaz M.; Abdullah, Luqman Chuah; Sadrolhosseini, Amir R.; Mat Yunus, Wan Mahmood; Moksin, Mohd Maarof; Tahir, Paridah Md.

    2011-01-01

    A new sensing area for a sensor based on surface plasmon resonance (SPR) was fabricated to detect trace amounts of mercury and lead ions. The gold surface used for SPR measurements were modified with polypyrrole-chitosan (PPy-CHI) conducting polymer composite. The polymer layer was deposited on the gold surface by electrodeposition. This optical sensor was used for monitoring toxic metal ions with and without sensitivity enhancement by chitosan in water samples. The higher amounts of resonance angle unit (ΔRU) were obtained for PPy-CHI film due to a specific binding of chitosan with Pb2+ and Hg2+ ions. The Pb2+ ion bind to the polymer films most strongly, and the sensor was more sensitive to Pb2+ compared to Hg2+. The concentrations of ions in the parts per million range produced the changes in the SPR angle minimum in the region of 0.03 to 0.07. Data analysis was done by Matlab software using Fresnel formula for multilayer system. PMID:21931763

  11. Selective Detection of Mercury (II) Ion Using Nonlinear Optical Properties of Gold Nanoparticles

    PubMed Central

    Darbha, Gopala Krishna; Singh, Anant Kumar; Rai, Uma Shanker; Yu, Eugene; Yu, Hongtao

    2013-01-01

    Contamination of the environment with heavy metal ions has been an important concern throughout the world for decades. Driven by the need to detect trace amounts of mercury in environmental samples, this article demonstrates for the first time that nonlinear optical (NLO) properties of MPA–HCys–PDCA-modified gold nanoparticles can be used for rapid, easy and reliable screening of Hg(II) ions in aqueous solution, with high sensitivity (5 ppb) and selectivity over competing analytes. The hyper Rayleigh scattering (HRS) intensity increases 10 times after the addition of 20 ppm Hg2+ ions to modified gold nanoparticle solution. The mechanism for HRS intensity change has been discussed in detail using particle size-dependent NLO properties as well as a two-state model. Our results show that the HRS assay for monitoring Hg(II) ions using MPA–HCys–PDCA-modified gold nanoparticles has excellent selectivity over alkali, alkaline earth (Li+, Na+, K+, Mg2+, Ca2+), and transition heavy metal ions (Pb2+, Pb+, Mn2+, Fe2+, Cu2+, Ni2+, Zn2+, Cd2+). PMID:18517205

  12. Specific spacecraft evaluation: Special report. [charged particle transport from a mercury ion thruster to spacecraft surfaces

    NASA Technical Reports Server (NTRS)

    Sellen, J. M., Jr.

    1978-01-01

    Charged and neutral particle transport from an 8 cm mercury ion thruster to the surfaces of the P 80-1 spacecraft and to the Teal Ruby sensor and the ECOM-501 sensor of that spacecraft were investigated. Laboratory measurements and analyses were used to examine line-of-sight and nonline-of sight particle transport modes. The recirculation of Hg(+) ions in the magnetic field of the earth was analyzed for spacecraft velocity and Earth magnetic field vector configurations which are expected to occur in near Earth, circular, high inclination orbits. For these magnetic field and orbit conditions and for expected ion release distribution functions, in both angles and energies, the recirculation/re-interception of ions on spacecraft surfaces was evaluated. The refraction of weakly energetic ions in the electric fields of the thruster plasma plume and in the electric fields between this plasma plume and the material boundaries of the thruster, the thruster sputter shield, and the various spacecraft surfaces were examined. The neutral particle transport modes of interest were identified as sputtered metal atoms from the thruster beam shield. Results, conclusions, and future considerations are presented.

  13. Fluorescence Sensing of Zinc and Mercury Ions with Hydrophilic 1,2,3-Triazolyl Fluorene Probes

    PubMed Central

    Nguyen, Dao M.; Frazer, Andrew; Rodriguez, Luis

    2010-01-01

    The ability to rapidly detect biologically and environmentally significant metal ions such as zinc and mercury is important to study a number of important cellular and environmental processes. Hydrophilic bis(1,2,3-triazolyl)fluorene-based derivatives, containing a 1,2,3-triazole-based recognition moiety, were synthesized through Click chemistry and characterized by UV-vis absorption, fluorescence emission, and two-photon absorption as new fluorescence sensing probes, selective for Zn2+ and Hg2+ ions. The UV-vis absorption and fluorescence emission spectra of the complexes exhibited blue-shifted absorption and emission spectra upon chelation to Zn2+ and Hg2+ ions, resulting in ca. two-fold enhancement in fluorescence. Fluorometric titration revealed that 1:2 and 1:3 ligand to metal complexes formed with binding constants of 108 and 1016 for Zn2+ and Hg2+, respectively. The two-photon absorption cross sections for the probes and probe-metal ion complexes ranged from 200-350 GM at 800 nm. These novel fluorescent compounds may have potential as new metal ion sensors to probe cellular and biological environments. PMID:20577581

  14. Diagnostic system design for the Ion Auxiliary Propulsion System /IAPS/ - Flight test of two 8 cm mercury ion thrusters

    NASA Technical Reports Server (NTRS)

    Hurst, E. B.; Thomas, G. Z.

    1981-01-01

    The experimental design of a Diagnostic Subsystem (DSS) as part of an Ion Auxiliary Propulsion System (IAPS) to be flown on P80-1 spacecraft in May 1983, is discussed. The DSS is composed of several detectors measuring thruster efflux, material deposition and spacecraft potential relative to the local space plasma in the vicinity of two 8 cm mercury ion thrusters. The detectors consist of two QCM units measuring frequency in the range of two to 65 KHz. Nine solar cell arrays have the capability of measuring current and voltage from 0-600 mA and 0-0.9 V. Seven ion collectors can measure ion currents with bias voltages of 0, 25, 55 and 96 V. The potential probe can measure current at 16 different commandible levels varying from one to 5 K microamperes within a voltage range of -25 to 175 V. The analysis of the ground-based data indicates that the hardware is qualified for flight, with the detectors and electronic units having passed all functional and environmental tests. Block diagrams are given and the functional parameters of the different design configurations are described.

  15. Sensitive detection of mercury and copper ions by fluorescent DNA/Ag nanoclusters in guanine-rich DNA hybridization.

    PubMed

    Peng, Jun; Ling, Jian; Zhang, Xiu-Qing; Bai, Hui-Ping; Zheng, Liyan; Cao, Qiu-E; Ding, Zhong-Tao

    2015-02-25

    In this work, we designed a new fluorescent oligonucleotides-stabilized silver nanoclusters (DNA/AgNCs) probe for sensitive detection of mercury and copper ions. This probe contains two tailored DNA sequence. One is a signal probe contains a cytosine-rich sequence template for AgNCs synthesis and link sequence at both ends. The other is a guanine-rich sequence for signal enhancement and link sequence complementary to the link sequence of the signal probe. After hybridization, the fluorescence of hybridized double-strand DNA/AgNCs is 200-fold enhanced based on the fluorescence enhancement effect of DNA/AgNCs in proximity of guanine-rich DNA sequence. The double-strand DNA/AgNCs probe is brighter and stable than that of single-strand DNA/AgNCs, and more importantly, can be used as novel fluorescent probes for detecting mercury and copper ions. Mercury and copper ions in the range of 6.0-160.0 and 6-240 nM, can be linearly detected with the detection limits of 2.1 and 3.4 nM, respectively. Our results indicated that the analytical parameters of the method for mercury and copper ions detection are much better than which using a single-strand DNA/AgNCs. PMID:25305618

  16. Sensitive detection of mercury and copper ions by fluorescent DNA/Ag nanoclusters in guanine-rich DNA hybridization

    NASA Astrophysics Data System (ADS)

    Peng, Jun; Ling, Jian; Zhang, Xiu-Qing; Bai, Hui-Ping; Zheng, Liyan; Cao, Qiu-E.; Ding, Zhong-Tao

    2015-02-01

    In this work, we designed a new fluorescent oligonucleotides-stabilized silver nanoclusters (DNA/AgNCs) probe for sensitive detection of mercury and copper ions. This probe contains two tailored DNA sequence. One is a signal probe contains a cytosine-rich sequence template for AgNCs synthesis and link sequence at both ends. The other is a guanine-rich sequence for signal enhancement and link sequence complementary to the link sequence of the signal probe. After hybridization, the fluorescence of hybridized double-strand DNA/AgNCs is 200-fold enhanced based on the fluorescence enhancement effect of DNA/AgNCs in proximity of guanine-rich DNA sequence. The double-strand DNA/AgNCs probe is brighter and stable than that of single-strand DNA/AgNCs, and more importantly, can be used as novel fluorescent probes for detecting mercury and copper ions. Mercury and copper ions in the range of 6.0-160.0 and 6-240 nM, can be linearly detected with the detection limits of 2.1 and 3.4 nM, respectively. Our results indicated that the analytical parameters of the method for mercury and copper ions detection are much better than which using a single-strand DNA/AgNCs.

  17. Facility produced charge-exchange ions

    NASA Technical Reports Server (NTRS)

    Carruth, M. R., Jr.

    1981-01-01

    These facility produced ions are created by charge-exchange collisions between neutral atoms and energetic thruster beam ions. The result of the electron transfer is an energetic neutral atom and an ion of only thermal energy. There are true charge-exchange ions produced by collisions with neutrals escaping from the ion thruster and being charge-exchange ionized before the neutral intercepts the tank wall. The facility produced charge-exchange ions will not exist in space and therefore, represent a source of error where measurements involving ion thruster plasmas and their density are involved. The quantity of facility produced ions in a test chamber with a 30 cm mercury ion thruster was determined.

  18. Solutions for discharge chamber sputtering and anode deposit spalling in small mercury ion thrusters

    NASA Technical Reports Server (NTRS)

    Power, J. L.; Hiznay, D. J.

    1975-01-01

    Proposed solutions to the problems of sputter erosion and sputtered material spalling in the discharge chamber of small mercury ion thrusters are presented. The accelerated life test evaluated three such proposed solutions: (1) the use of tantalum as a single low sputter yield material for the exposed surfaces of the discharge chamber components subject to sputtering, (2) the use of a severely roughened anode surface to improve the adhesion of the sputter-deposited coating, and (3) the use of a wire cloth anode surface in order to limit the size of any coating flakes which might spall from it. Because of the promising results obtained in the accelerated life test with anode surfaces roughened by grit-blasting, experiments were carried out to optimize the grit-blasting procedure. The experimental results and an optimal grit-blasting procedure are presented.

  19. Ion-Exchangeable Molybdenum Sulfide Porous Chalcogel: Gas Adsorption and Capture of Iodine and Mercury.

    PubMed

    Subrahmanyam, Kota S; Malliakas, Christos D; Sarma, Debajit; Armatas, Gerasimos S; Wu, Jinsong; Kanatzidis, Mercouri G

    2015-11-01

    We report the synthesis of ion-exchangeable molybdenum sulfide chalcogel through an oxidative coupling process, using (NH4)2MoS4 and iodine. After supercritical drying, the MoS(x) amorphous aerogel shows a large surface area up to 370 m(2)/g with a broad range of pore sizes. X-ray photoelectron spectroscopic and pair distribution function analyses reveal that Mo(6+) species undergo reduction during network assembly to produce Mo(4+)-containing species where the chalcogel network consists of [Mo3S13] building blocks comprising triangular Mo metal clusters and S2(2-) units. The optical band gap of the brown-black chalcogel is ∼1.36 eV. The ammonium sites present in the molybdenum sulfide chalcogel network are ion-exchangeable with K(+) and Cs(+) ions. The molybdenum sulfide aerogel exhibits high adsorption selectivities for CO2 and C2H6 over H2 and CH4. The aerogel also possesses high affinity for iodine and mercury. PMID:26456071

  20. A molecular-gap device for specific determination of mercury ions

    NASA Astrophysics Data System (ADS)

    Guo, Zheng; Liu, Zhong-Gang; Yao, Xian-Zhi; Zhang, Kai-Sheng; Chen, Xing; Liu, Jin-Huai; Huang, Xing-Jiu

    2013-11-01

    Specific determination/monitoring of trace mercury ions (Hg2+) in environmental water is of significant importance for drinking safety. Complementarily to conventional inductively coupled plasma mass spectrometry and atomic emission/absorption spectroscopy, several methods, i.e., electrochemical, fluorescent, colorimetric, and surface enhanced Raman scattering approaches, have been developed recently. Despite great success, many inevitably encounter the interferences from other metal ions besides the complicated procedures and sophisticated equipments. Here we present a molecular-gap device for specific determination of trace Hg2+ in both standardized solutions and environmental samples based on conductivity-modulated glutathione dimer. Through a self-assembling technique, a thin film of glutathione monolayer capped Au nanoparticles is introduced into 2.5 μm-gap-electrodes, forming numerous double molecular layer gaps. Notably, the fabricated molecular-gap device shows a specific response toward Hg2+ with a low detection limit actually measured down to 1 nM. Theoretical calculations demonstrate that the specific sensing mechanism greatly depends on the electron transport ability of glutathione dimer bridged by heavy metal ions, which is determined by its frontier molecular orbital, not the binding energy.

  1. Charge-exchange plasma environment for an ion drive spacecraft. [a model for describing mercury ion engines and its effect on spacecraft subsystems

    NASA Technical Reports Server (NTRS)

    Kaufman, H. R.; Carruth, M. R., Jr.

    1979-01-01

    The charge exchange plasma environment around a spacecraft that uses mercury ion thrusters for propulsion is described. The interactions between the plasma environment and the spacecraft are determined and a model which describes the propagation of the mercury charge exchange plasma is discussed. The model is extended to describe the flow of the molybdenum component of the charge exchange plasma. The uncertainties in the models for various conditions are discussed and current drain to the solar array, charge exchange plasma material deposition, and the effects of space plasma on the charge exchange plasma propagation are addressed.

  2. Counting sulfhydryls and disulfide bonds in peptides and proteins using mercurial ions as an MS-tag.

    PubMed

    Guo, Yifei; Chen, Liqin; Yang, Limin; Wang, Qiuquan

    2008-08-01

    Organic mercurial compounds are the most specific and sensitive reagents for reaction with the sulfhydryl groups (SHs) in peptides and proteins because of the strong mercury-sulfur affinity. Using the monofunctional organic mercury ion RHg(+) as a mass spectrometry (MS)-tag has the advantages of reacting with one sulfhydryl group, offering definite mass shift, and especially stable and characteristic nonradioactive isotopic distribution. Mass spectrometric analysis of derivatized sulfhydryls in peptides/proteins is thus an alternative for precisely counting the number of sulfhydryl groups and disulfide bonds (SS). Here the tags used include monomethylmercury chloride, monoethylmercury chloride, and 4-(hydroxymercuri) benzoic acid. The feasibility of this strategy is demonstrated using HPLC/ESI-MS to count SHs and SS in model peptides/proteins, i.e., glutathione, phytochelatins, lysozyme and beta-lactoglobulin, which contain increasing SHs and various SS linkages. PMID:18524619

  3. A highly selective voltammetric sensor for nanomolar detection of mercury ions using a carbon ionic liquid paste electrode impregnated with novel ion imprinted polymeric nanobeads.

    PubMed

    Bahrami, Azam; Besharati-Seidani, Abbas; Abbaspour, Abdolkarim; Shamsipur, Mojtaba

    2015-03-01

    This work reports the preparation of a voltammetric sensor for selective recognition and sensitive determination of mercury ions using a carbon ionic liquid paste electrode (CILE) impregnated with novel Hg(2+)-ion imprinted polymeric nanobeads (IIP) based on dithizone, as a suitable ligand for complex formation with Hg(2+) ions. The differential pulse anodic stripping voltammetric technique was employed to investigate the performance of the prepared IIP-CILE for determination of hazardous mercury ions. The designed modified electrode revealed linear responses in the ranges of 0.5nM-10nM and 0.08μM-2μM with a limit of detection of 0.1nM (S/N=3). It was found that the peak currents of the modified electrode for Hg(2+) ions were at a maximum value in phosphate buffer of pH4.5. The optimized preconcentration potential and accumulation time were to be -0.9V and 35s, respectively. The applicability of the proposed sensor to mercury determination in waste water samples is reported. PMID:25579915

  4. Mercury displacement detection for the determination of picogram amounts of sulfite ion or sulfur dioxide by atomic spectrometry

    SciTech Connect

    Marshall, G.; Midgley, D.

    1981-10-01

    An analytical method has been developed that can determine picogram amounts of sulfite in aqueous solution or sulfur dioxide in solution. The technique is based on the reaction of sulfite ion in solution with mercury(I) ion to promote its disproportionation to metallic mercury and mercury(II) ions. By monitoring the Hg/sup 0/ released it is possible to determine the concentration of sulfite added. The method gives a linear calibration over the range tested (0 to 5 ng of sulfite) and the within-batch cefficients of variation for the determination of 0.5, 1.0, 2.0, and 5.0 ng of sulfite are 4, 3, 2.5, and 1.8%, respectively. Fifteen analyses can be carried out each hour. The limit of detection is 30 pg of sulfite, which is several orders of magnitude lower than can be obtained by other manual methods of sulfite determination. The method is very selective. Sulfate ion does not interfere, which is especially important in the determination of atmospheric sulfur dioxide.

  5. Successful completion of a cyclic ground test of a mercury Ion Auxiliary Propulsion System

    NASA Technical Reports Server (NTRS)

    Francisco, David R.; Low, Charles A., Jr.; Power, John L.

    1988-01-01

    An engineering model Ion Auxiliary Propulsion System (IAPS) 8-cm thruster (S/N 905) has completed a life test at NASA Lewis Research Center. The mercury ion thruster successfully completed and exceeded the test goals of 2557 on/off cycles and 7057 hr of operation at full thrust. The final 1200 cycles and 3600 hr of the life test were conducted using an engineering model of the IAPS power electronics unit (PEU) and breadboard digital controller and interface unit (DCIU). This portion of the test is described in this paper with a charted history of thruster operating parameters and off-normal events. Performance and operating characteristics were constant throughout the test with only minor variations. The engineering model power electronics unit operated without malfunction; the flight software in the digital controller and interface unit was exercised and verified. Post-test inspection of the thruster revealed facility enhanced accelerator grid erosion but overall the thruster was in good condition. It was concluded that the thruster performance was not drastically degraded by time or cycles. Additional cyclic testing is currently under consideration.

  6. Successful completion of a cyclic ground test of a mercury ion auxiliary propulsion system

    NASA Technical Reports Server (NTRS)

    Francisco, David R.; Low, Charles A., Jr.; Power, John L.

    1988-01-01

    An engineering model Ion Auxiliary Propulsion System (IAPS) 8-cm thruster (S/N 905) has completed a life test at NASA Lewis Research Center. The mercury ion thruster successfully completed and exceeded the test goals of 2557 on/off cycles and 7057 hr of operation at full thrust. The final 1200 cycles and 3600 hr of the life test were conducted using an engineering model of the IAPS power electronics unit (PEU) and breadboard digital controller and interface unit (DCIU). This portion of the test is described in this paper with a charted history of thruster operating parameters and off-normal events. Performance and operating characteristics were constant throughout the test with only minor variations. The engineering model power electronics unit operated without malfunction; the flight software in the digital controller and interface unit was exercised and verified. Post-test inspection of the thruster revealed facility enhanced accelerator grid erosion but overall the thruster was in good condition. It was concluded that the thruster performance was not drastically degraded by time or cycles. Additional cyclic testing is currently under consideration.

  7. X-ray rocking curve analysis of ion implanted mercury cadmium telluride

    NASA Astrophysics Data System (ADS)

    Williams, B. L.; Robinson, H. G.; Helms, C. R.; Zhu, N.

    1997-06-01

    Junction formation by ion implantation is a critical step in producing high quality infrared focal plane arrays in mercury cadmium telluride (MCT). We have analyzed the structural properties of MCT implanted with B at doses of 1014 and 1015 cm-2 using double and triple crystal x-ray diffraction (DCD and TCD) to monitor the disorder and strain of the implanted region as a function of processing conditions. TCD (333) reflections show that a distinct tensile peak is produced by the high dose implant while the low dose implant shows only a low angle shoulder on the substrate peak. A preliminary association of the low angle shoulder with point defects has been made since no extended defects have been observed in the low dose range. For the high dose implant, extended defect formation has been reported and may be responsible for the tensile peak. After annealing, the low angle shoulder on the low dose implant has disappeared, while the high dose implant exhibits an increase in the tensile strain from 6.5 × 10-4 to 9.3 × 10-4 after 24 h of annealing and then decreases in tensile strain to 7.3 × 10-4 after 48 h of annealing. It is believed the changes in strain are associated with the Oswald ripening and dissolution of extended defects, which has been observed during annealing of ion implanted Si.

  8. Using L-arginine-functionalized gold nanorods for visible detection of mercury(II) ions.

    PubMed

    Guan, Jiehao; Wang, Yi-Cheng; Gunasekaran, Sundaram

    2015-04-01

    A rapid and simple approach for visible determination of mercury ions (Hg(2+) ) in aqueous solutions was developed based on surface plasmon resonance phenomenon using L-arginine-functionalized gold nanorods (AuNRs). At pH greater than 9, the deprotonated amine group of L-arginine on the AuNRs bound with Hg(2+) leading to the side-by-side assembly of AuNRs, which was verified by transmission electron microscopy images. Thus, when Hg(2+) was present in the test solution, a blue shift of the typical longitudinal plasmon band of the AuNRs was observed in the ultra violet-visible-near infrared (UV-Vis-NIR) spectra, along with a change in the color of the solution, which occurred within 5 min. After carefully optimizing the potential factors affecting the performance, the L-arginine/AuNRs sensing system was found to be highly sensitive to Hg(2+) , with the limit of detection of 5 nM (S/N = 3); it is also very selective and free of interference from 10 other metal ions (Ba(2+) , Ca(2+) , Cd(2+) , Co(2+) , Cs(+) , Cu(2+) , K(+) , Li(+) , Ni(2+) , Pb(2+) ). The result suggests that the L-arginine-functionalized AuNRs can potentially serve as a rapid, sensitive, and easy-to-use colorimetric biosensor useful for determining Hg(2+) in food and environmental samples. PMID:25754066

  9. Nanometer fabrication in mercury cadmium telluride by electron cyclotron resonance microwave plasma reactive ion etching

    NASA Astrophysics Data System (ADS)

    Eddy, C. R.; Hoffman, C. A.; Meyer, J. R.; Dobisz, E. A.

    1993-08-01

    It has been recently reported (J.R. Meyer, F.J. Bartoli, C.A. Hoffman, and L.R. Ram-Mohan, Phys. Rev. Lett. 64, 1963 [1990]) that novel electronic and optical effects are anticipated in nanometer scale features of narrow band gap semiconductors such as mercury cadmium telluride (MCT). These efforts could lead to the creation of non-linear optical switches, high efficiency infrared lasers, and unique nanoelectronic devices. This work reports on the first realization of MCT nanostructures through the application of e-beam lithography and reactive ion etching with an electron cyclotron resonance (ECR) microwave plasma source. It is shown that the low energy ions produced by an ECR system can etch MCT with good selectivity over an e-beam resist mask and with high resolution. Using these fabrication methods, 40 70 nm features with aspect ratios of 3 5∶1 and sidewall angles greater than 88° have been demonstrated. Qualitative investigations of some of the etch mechanisms of this technique are made, and results suggest a desorption limited process.

  10. Influence of anions on methylpyridinium ion adsorption on the mercury electrode in aqueous solutions

    SciTech Connect

    Gerovich, V.M.; Damaskin, B.B.; Ermolin, V.B.

    1987-02-01

    The adsorption behavior of aromatic and heterocyclic cations is known to be determined by image forces on one hand and by pi-electron interaction on the other. The first factor is effective at the negatively charged surface of the mercury electrode whereas the second factor is effective at the positively charged surface where the forces of pi-electron interaction are in opposition to the electrostatic repulsion forces of the cations. The authors of this paper study the adsorption of methylpyridinium as the aromatic cation in combination with persulfate, chlorine, bromine, and iodine as the anions. The potential range studied was limited on the anodic side by a potential of -0.1 eV, since the values of interfacial tension were poorly reproducible at more positive potentials, and on the cathodic side by a potential of -1.1 eV, since methylpyridinium is reduced at more negative potentials. It is found that the halide ions, owing to the possible formation of charge transfer complexes, have an even stronger effect on the adsorption behavior of organic cations than that observed previously for tetraalkylammonium ions.

  11. Logic control of enzyme-like gold nanoparticles for selective detection of lead and mercury ions.

    PubMed

    Lien, Chia-Wen; Tseng, Yu-Ting; Huang, Chih-Ching; Chang, Huan-Tsung

    2014-02-18

    Functional logic gates based on lead ions (Pb(2+)) and mercury ions (Hg(2+)) that induce peroxidase-like activities in gold nanoparticles (Au NPs) in the presence of platinum (Pt(4+)) and bismuth ions (Bi(3+)) are presented. The "AND" logic gate is constructed using Pt(4+)/Pb(2+) as the input and the peroxidase-like activity of the Au NPs as the output; this logic gate is denoted as "Pt(4+)/Pb(2+)(AND)-Au NPPOX". When Pt(4+) and Pb(2+) coexist, strong metallophilic interactions (between Pt and Pb atoms/ions) and aurophilic interactions (between Au and Pb/Pt atoms/ions) result in significant increases in the deposition of Pt and Pb atoms/ions onto the Au NPs, leading to enhanced peroxidase-like activity. The "INHIBIT" logic gate is fabricated by using Bi(3+) and Hg(2+) as the input and the peroxidase-like activity of the Au NPs as the output; this logic gate is denoted as "Bi(3+)/Hg(2+)(INHIBIT)-Au NPPOX". High peroxidase-like activity of Au NPs in the presence of Bi(3+) is a result of the various valence (oxidation) states of Bi(3+) and Au (Au(+)/Au(0)) atoms on the nanoparticle's surface. When Bi(3+) and Hg(2+) coexist, strong Hg-Au amalgamation results in a large decrease in the peroxidase-like activity of the Au NPs. These two probes (Pt(4+)/Pb(2+)(AND)-Au NPPOX and Bi(3+)/Hg(2+)(INHIBIT)-Au NPPOX) allow selective detection of Pb(2+) and Hg(2+) down to nanomolar quantities. The practicality of these two probes has been validated by analysis of Pb(2+) and Hg(2+) in environmental water samples (tap water, river water, and lake water). In addition, an integrated logic circuit based on the color change (formation of reddish resorufin product) and generation of O2 bubbles from these two probes has been constructed, allowing visual detection of Pb(2+) and Hg(2+) in aqueous solution. PMID:24451013

  12. Rhodamine functionalized magnetic core-shell nanocomposite: an emission "Off-On" sensing system for mercury ion detection and extraction.

    PubMed

    Shen, Lei; Wu, Yan; Ma, Wuze

    2015-03-01

    This paper reported a core-shell structured composite with superparamagnetic ferroferric oxide as the inner core and silica molecular sieve as the outer shell. A rhodamine based sensing dye was covalently grafted into the highly ordered tunnels of silica molecular sieve, so that mercury ion sensing and extraction could be achieved from this composite. This probe loaded core-shell structure was characterized by electron microscopy images, X-ray diffraction patterns, infrared spectra, thermogravimetry and N2 adsorption/desorption measurement. This composite showed increased emission with increasing mercury ion concentration, along with high sensitivity and good selectivity. Linear response and good regenerating performance were also observed from this composite. PMID:25506652

  13. Measuring the spacecraft and environmental interactions of the 8-cm mercury ion thrusters on the P80-1 mission

    NASA Technical Reports Server (NTRS)

    Power, J. L.

    1981-01-01

    The subject interface measurements are described for the Ion Auxiliary Propulsion System (IAPS) flight test of two 8-cm thrusters. The diagnostic devices and the effects to be measured include: 1) quartz crystal microbalances to detect nonvolatile deposition due to thruster operation; 2) warm and cold solar cell monitors for nonvolatile and volatile (mercury) deposition; 3) retarding potential ion collectors to characterize the low energy thruster ionic efflux; and 4) a probe to measure the spacecraft potential and thruster generated electron currents to biased spacecraft surfaces. The diagnostics will also assess space environmental interactions of the spacecraft and thrusters. The diagnostic data will characterize mercury thruster interfaces and provide data useful for future applications.

  14. Calix[4]pyrrole derivative: recognition of fluoride and mercury ions and extracting properties of the receptor-based new material.

    PubMed

    de Namor, Angela F Danil; Khalife, Rasha

    2008-12-11

    A calix[4]pyrrole derivative, namely, meso-tetramethyl tetrakis (4-phenoxy methyl ketone) calix[4]pyrrole, 1, was synthesized and structurally (1H NMR) and thermodynamically characterized. The complexing properties of this receptor with a wide variety of anions and cations in dipolar aprotic media (acetonitrile, propylene carbonate, and dimethyl sulfoxide) were investigated through 1H NMR and conductance studies. The former technique was used to assess whether or not complexation occurs and if so to identify the active sites of interaction of 1 with ions. The composition of the complexes was established by conductance measurements. It was found that in dipolar aprotic solvents, 1 interacts only with two polluting ions (fluoride and mercury). The complexation thermodynamics of 1 and these ions in these solvents is reported. The medium effect on the binding process involving the fluoride ion is discussed taking into account the solvation properties of reactants and the product. Complexes of moderate stability are found. Given that this is an important factor to consider for the recycling of the loaded material in extraction processes, 1 was treated with formaldehyde in basic medium leading to the production of a calix[4]pyrrole based material able to extract fluoride and mercury (II) ions from water. Thus the optimum conditions for the extraction of these ions from aqueous solutions were established. The material is easily recyclable using an organic acid. Final conclusions are given. PMID:19053691

  15. Femtomole level photoelectrochemical aptasensing for mercury ions using quercetin-copper(II) complex as the DNA intercalator.

    PubMed

    Li, Hongbo; Xue, Yan; Wang, Wei

    2014-04-15

    An ultrasensitive and selective photoelectrochemical (PEC) aptasensor for mercury ions was first fabricated based on perylene-3, 4, 9, 10-tetracarboxylic acid/graphene oxide (PTCA/GO) heterojunction using quercetin-copper(II) complex intercalated into the poly(dT)-poly(dA) duplexes. Both the PTCA/GO heterojunction and the quercetin-copper(II) complex are in favor of the sensitivity for the fabricated PEC aptasensor due to band alignment and strong reduction capability, respectively. And they efficiently promote the separation of photoexcited carriers and enhance the photocurrent. The formation of thymine-Hg(2+)-thymine coordination chemistry resulted in the dehybridization of poly(dT)-poly(dA) duplexes and then the intercalator quercetin-copper(II) complex broke away from the surface of the PEC aptasensor. As the concentration of mercury ions increased, the photocurrent gradually decreased. The electrode response for mercury ions detection was in the linear range from 0.01 pmol L(-1) to 1.00 pmol L(-1) with the detection limit of 3.33 fmol L(-1). The label-free PEC aptasensor has excellent performances with ultrasensitivity and good selectivity besides the advantage of economic and facile fabrication. The strategy of quercetin-copper(II) complex as a novel DNA intercalator paves a new way to improve the performances for PEC sensors. PMID:24291750

  16. MWCNTs based high sensitive lateral flow strip biosensor for rapid determination of aqueous mercury ions.

    PubMed

    Yao, Li; Teng, Jun; Zhu, Mengya; Zheng, Lei; Zhong, Youhao; Liu, Guodong; Xue, Feng; Chen, Wei

    2016-11-15

    Here, we describe a disposable multi-walled carbon nanotubes (MWCNTs) labeled nucleic acid lateral flow strip biosensor for rapid and sensitive detection of aqueous mercury ions (Hg(2+)). Unlike the conventional colloidal gold nanoparticle based strip biosensors, the carboxylated MWCNTs were selected as the labeling substrate because of its high specific surface area for immobilization of recognition probes, improved stability and enhanced detection sensitivity of the strip biosensor. Combining the sandwich-type of T-Hg(2+)-T recognition mechanism with the optical properties of MWCNTs on lateral flow strip, optical black bands were observed on the lateral flow strips. Parameters (such as membrane category, the MWCNTs concentration, the amount of MWCNT-DNA probe, and the volume of the test probe) that govern the sensitivity and reproducibility of the sensor were optimized. The response of the optimized biosensor was highly linear over the range of 0.05-1ppb target Hg(2+), and the detection threshold was estimated at 0.05 ppb within a 15-min assay time. The sensitivity was 10-fold higher than the conventional colloidal gold based strip biosensor. More importantly, the stability of the sensor was also greatly improved with the usage of MWCNTs as the labeling. PMID:27183284

  17. Generation of continuous-wave 194 nm laser for mercury ion optical frequency standard

    NASA Astrophysics Data System (ADS)

    Zou, Hongxin; Wu, Yue; Chen, Guozhu; Shen, Yong; Liu, Qu; Precision measurement; atomic clock Team

    2015-05-01

    194 nm continuous-wave (CW) laser is an essential part in mercury ion optical frequency standard. The continuous-wave tunable radiation sources in the deep ultraviolet (DUV) region of the spectrum is also serviceable in high-resolution spectroscopy with many atomic and molecular lines. We introduce a scheme to generate continuous-wave 194 nm radiation with SFM in a Beta Barium Borate (BBO) crystal here. The two source beams are at 718 nm and 266 nm, respectively. Due to the property of BBO, critical phase matching (CPM) is implemented. One bow-tie cavity is used to resonantly enhance the 718 nm beam while the 266 nm makes a single pass, which makes the configuration easy to implement. Considering the walk-off effect in CPM, the cavity mode is designed to be elliptical so that the conversion efficiency can be promoted. Since the 266 nm radiation is generated by a 532 nm laser through SHG in a BBO crystal with a large walk-off angle, the output mode is quite non-Gaussian. To improve mode matching, we shaped the 266 nm beam into Gaussian modes with a cylindrical lens and iris diaphragm. As a result, 2.05 mW 194 nm radiation can be generated. As we know, this is the highest power for 194 nm CW laser using SFM in BBO with just single resonance. The work is supported by the National Natural Science Foundation of China (Grant No. 91436103 and No. 11204374).

  18. MRP2 and the handling of mercuric ions in rats exposed acutely to inorganic and organic species of mercury

    SciTech Connect

    Bridges, Christy C. Joshee, Lucy; Zalups, Rudolfs K.

    2011-02-15

    Mercuric ions accumulate preferentially in renal tubular epithelial cells and bond with intracellular thiols. Certain metal-complexing agents have been shown to promote extraction of mercuric ions via the multidrug resistance-associated protein 2 (MRP2). Following exposure to a non-toxic dose of inorganic mercury (Hg{sup 2+}), in the absence of complexing agents, tubular cells are capable of exporting a small fraction of intracellular Hg{sup 2+} through one or more undetermined mechanisms. We hypothesize that MRP2 plays a role in this export. To test this hypothesis, Wistar (control) and TR{sup -} rats were injected intravenously with a non-nephrotoxic dose of HgCl{sub 2} (0.5 {mu}mol/kg) or CH{sub 3}HgCl (5 mg/kg), containing [{sup 203}Hg], in the presence or absence of cysteine (Cys; 1.25 {mu}mol/kg or 12.5 mg/kg, respectively). Animals were sacrificed 24 h after exposure to mercury and the content of [{sup 203}Hg] in blood, kidneys, liver, urine and feces was determined. In addition, uptake of Cys-S-conjugates of Hg{sup 2+} and methylmercury (CH{sub 3}Hg{sup +}) was measured in inside-out membrane vesicles prepared from either control Sf9 cells or Sf9 cells transfected with human MRP2. The amount of mercury in the total renal mass and liver was significantly greater in TR{sup -} rats than in controls. In contrast, the amount of mercury in urine and feces was significantly lower in TR{sup -} rats than in controls. Data from membrane vesicles indicate that Cys-S-conjugates of Hg{sup 2+} and CH{sub 3}Hg{sup +} are transportable substrates of MRP2. Collectively, these data indicate that MRP2 plays a role in the physiological handling and elimination of mercuric ions from the kidney.

  19. Graphene-Diatom Silica Aerogels for Efficient Removal of Mercury Ions from Water.

    PubMed

    Kabiri, Shervin; Tran, Diana N H; Azari, Sara; Losic, Dusan

    2015-06-10

    A simple synthetic approach for the preparation of graphene-diatom silica composites in the form of self-assembled aerogels with three-dimensional networks from natural graphite and diatomite rocks is demonstrated for the first time. Their adsorption performance for the removal of mercury from water was studied as a function of contact time, solution pH, and mercury concentration to optimize the reaction conditions. The adsorption isotherm of mercury fitted well with the Langmuir model, representing a very high adsorption capacity of >500 mg of mercury/g of adsorbent. The prepared aerogels exhibited outstanding adsorption performance for the removal of mercury from water, which is significant for environmental applications. PMID:25835089

  20. Functionalized gold nanoparticles/reduced graphene oxide nanocomposites for ultrasensitive electrochemical sensing of mercury ions based on thymine-mercury-thymine structure.

    PubMed

    Wang, Nan; Lin, Meng; Dai, Hongxiu; Ma, Houyi

    2016-05-15

    A sensitive, selective and reusable electrochemical biosensor for the determination of mercury ions (Hg(2+)) has been developed based on thymine (T) modified gold nanoparticles/reduced graphene oxide (AuNPs/rGO) nanocomposites. Graphene oxide (GO) was electrochemically reduced on a glassy carbon substrate. Subsequently, AuNPs were deposited onto the surface of rGO by cyclic voltammetry. For functionalization of the electrode, the carboxylic group of the thymine-1-acetic acid was covalently coupled with the amine group of the cysteamine which self-assembled onto AuNPs. The structural features of the T bases functionalized AuNPs/rGO electrode were confirmed by attenuated total reflection infrared (ATR-IR) spectroscopy and scanning electron microscopy (SEM) spectroscopy. Each step of the modification process was characterized by cyclic voltammetry (CV) and electrochemical impedence spectroscopy (EIS). The T bases modified AuNPs/rGO electrode was applied to detect various trace metal ions by differential pulse voltammetry (DPV). The proposed biosensor was found to be highly sensitive to Hg(2+) in the range of 10ng/L-1.0µg/L. The biosensor afforded excellent selectivity for Hg(2+) against other heavy metal ions such as Zn(2+), Cd(2+), Pb(2+), Cu(2+), Ni(2+), and Co(2+). Furthermore, the developed sensor exhibited a high reusability through a simple washing. In addition, the prepared biosensor was successfully applied to assay Hg(2+) in real environmental samples. PMID:26720921

  1. Electrochemical sensor for glutathione detection based on mercury ion triggered hybridization chain reaction signal amplification.

    PubMed

    Wang, Yonghong; Jiang, Lun; Leng, Qinggang; Wu, Yaohui; He, Xiaoxiao; Wang, Kemin

    2016-03-15

    In this work, we design a new simple and highly sensitive strategy for electrochemical detection of glutathione (GSH) via mercury ion (Hg(2+)) triggered hybridization chain reaction (HCR) signal amplification. It is observed that in the absence of GSH, a specific thymine-Hg(2+)-thymine (T-Hg(2+)-T) coordination can fold into hairpin structures. While in the presence of GSH, it thus can be chelated with Hg(2+), resulting in Hg(2+) released from the T-Hg(2+)-T hairpin complex which then forms into ssDNA structure to further hybridize with the surface-immobilized capture DNA probe on the gold electrode with a sticky tail left. The presence of two hairpin helper probes through HCR leads to the formation of extended dsDNA superstructure on the electrode surface, which therefore causes the intercalation of numerous electroactive species ([Ru(NH3)6](3+)) into the dsDNA grooves, followed by a significantly amplified signal output whose intensity is related to the concentration of the GSH. Taking advantage of merits of enzyme-free amplification power of the HCR, the inherent high sensitivity of the electrochemical technique, and label-free detection which utilizes an electroactive species as a signaling molecule that binds to the anionic phosphate backbone of DNA strands via electrostatic force, not only does the proposed strategy enable sensitive detection of GSH, but show high selectivity against other amino acid, making our method a simple and sensitive addition to the amplified GSH detection. PMID:26528805

  2. A Metal-Organic Framework/DNA Hybrid System as a Novel Fluorescent Biosensor for Mercury(II) Ion Detection.

    PubMed

    Wu, Lan-Lan; Wang, Zhuo; Zhao, Shu-Na; Meng, Xing; Song, Xue-Zhi; Feng, Jing; Song, Shu-Yan; Zhang, Hong-Jie

    2016-01-11

    Mercury(II) ions have emerged as a widespread environmental hazard in recent decades. Despite different kinds of detection methods reported to sense Hg(2+) , it still remains a challenging task to develop new sensing molecules to replenish the fluorescence-based apparatus for Hg(2+) detection. This communication demonstrates a novel fluorescent sensor using UiO-66-NH2 and a T-rich FAM-labeled ssDNA as a hybrid system to detect Hg(2+) sensitively and selectively. To the best of our knowledge, it has rarely been reported that a MOF is utilized as the biosensing platform for Hg(2+) assay. PMID:26555340

  3. Application of Polypyrrole Multi-Walled Carbon Nanotube Composite Layer for Detection of Mercury, Lead and Iron Ions Using Surface Plasmon Resonance Technique

    PubMed Central

    Sadrolhosseini, Amir Reza; Noor, A. S. M.; Bahrami, Afarin; Lim, H. N.; Talib, Zainal Abidin; Mahdi, Mohd. Adzir

    2014-01-01

    Polypyrrole multi-walled carbon nanotube composite layers were used to modify the gold layer to measure heavy metal ions using the surface plasmon resonance technique. The new sensor was fabricated to detect trace amounts of mercury (Hg), lead (Pb), and iron (Fe) ions. In the present research, the sensitivity of a polypyrrole multi-walled carbon nanotube composite layer and a polypyrrole layer were compared. The application of polypyrrole multi-walled carbon nanotubes enhanced the sensitivity and accuracy of the sensor for detecting ions in an aqueous solution due to the binding of mercury, lead, and iron ions to the sensing layer. The Hg ion bonded to the sensing layer more strongly than did the Pb and Fe ions. The limitation of the sensor was calculated to be about 0.1 ppm, which produced an angle shift in the region of 0.3° to 0.6°. PMID:24733263

  4. Application of polypyrrole multi-walled carbon nanotube composite layer for detection of mercury, lead and iron ions using surface plasmon resonance technique.

    PubMed

    Sadrolhosseini, Amir Reza; Noor, A S M; Bahrami, Afarin; Lim, H N; Talib, Zainal Abidin; Mahdi, Mohd Adzir

    2014-01-01

    Polypyrrole multi-walled carbon nanotube composite layers were used to modify the gold layer to measure heavy metal ions using the surface plasmon resonance technique. The new sensor was fabricated to detect trace amounts of mercury (Hg), lead (Pb), and iron (Fe) ions. In the present research, the sensitivity of a polypyrrole multi-walled carbon nanotube composite layer and a polypyrrole layer were compared. The application of polypyrrole multi-walled carbon nanotubes enhanced the sensitivity and accuracy of the sensor for detecting ions in an aqueous solution due to the binding of mercury, lead, and iron ions to the sensing layer. The Hg ion bonded to the sensing layer more strongly than did the Pb and Fe ions. The limitation of the sensor was calculated to be about 0.1 ppm, which produced an angle shift in the region of 0.3° to 0.6°. PMID:24733263

  5. Synthesis and evaluation of different thio-modified cellulose resins for the removal of mercury (II) ion from highly acidic aqueous solutions.

    PubMed

    Takagai, Yoshitaka; Shibata, Atsushi; Kiyokawa, Shigemi; Takase, Tsugiko

    2011-01-15

    Seven different types of thio- and/or amine-modified cellulose resin materials were synthesized and their mercury (II) ion adsorption properties determined. All seven resins showed good mercury (II) adsorption capability in the more neutral pH regions. However, the o-benzenedithiol- and o-aminothiophenol-modified cellulosic resins were found to be very effective in removing mercury (II) ions from strongly acidic media. For example, 93.5-100% mercury (II) ion recoveries from very acid aqueous solutions (nitric acid concentration ranged from 0.1 to 2.0 mol/L) were obtained using the o-benzenedithiol-modified resin while recoveries ranged from ca. 50% to 60% for the o-aminothiophenol-modified resin. An adsorption capacity of 23 mg (as Hg atoms) per gram of resin was observed for the o-benzenedithiol-modified cellulose in the presence of 1.0 mol/L nitric acid. This same resin shows very good selectivity for mercury (II) as only ruthenium (II) also somewhat adsorbed onto it out of 14 other metal ions studied (Ag(+), Al(3+), As(3+), Co(2+), Cd(2+), Cr(3+), Cu(2+), Fe(3+), Mn(2+), Ni(2+), Pt(2+), Pb(2+), Ru(2+), and Zn(2+)). PMID:20974469

  6. Aggregation induced emission enhancement from Bathophenanthroline microstructures and its potential use as sensor of mercury ions in water.

    PubMed

    Mazumdar, Prativa; Das, Debasish; Sahoo, Gobinda Prasad; Salgado-Morán, Guillermo; Misra, Ajay

    2014-04-01

    Bathophenanthroline (BA) microstructures of various morphologies have been synthesized using a reprecipitation method. The morphologies of the particles are characterized using optical and scanning electron microscopy (SEM) methods. An aqueous dispersion of BA microstructures shows aggregation induced emission enhancement (AIEE) compared to BA in a good solvent, THF. This luminescent property of aggregated BA hydrosol is used for the selective detection of trace amounts of mercury ion (Hg(2+)) in water. It is observed that Hg(2+) ions can quench the photoluminescence (PL) intensity of BA aggregates even at very low concentrations, compared to other heavy metal ions e.g. nickel (Ni(2+)), manganese (Mn(2+)), cadmium (Cd(2+)), cobalt (Co(2+)), copper (Cu(2+)), ferrous (Fe(2+)) and zinc (Zn(2+)). This strong fluorescence quenching of aggregated BA in the presence of Hg(2+) ions has been explained as a complex interplay between the ground state complexation between BA and Hg(2+) ions and external heavy atom induced perturbation by Hg(2+) ions on the excited states of the fluorophore BA. PMID:24569390

  7. Dithizone derivatives as sensitive water soluble chromogenic reagents for the ion chromatographic determination of inorganic and organo-mercury in aqueous matrices.

    PubMed

    Shaw, Matthew J; Jones, Phil; Haddad, Paul R

    2003-10-01

    Water-soluble sulfonate and the novel carboxylate analogues of dithizone, combined with ion interaction chromatography on a Dionex Acclaim 120 C18 silica column (250 x 4.6 mm id) with an eluent consisting of 10 mM tetrabutylammonium bromide and 60:40 methanol:water, have been developed as highly sensitive chromogenic ligands for the quantitative isocratic determination of inorganic and organo-mercury compounds in aqueous matrices in under 12 min. Using an optimised post column reagent system containing 0.65 mM dye, 0.5% Triton X-100 and 50 mM sodium hydroxide, good linearity (0-7.5 mg L(-1) R2 > 0.999), reproducibility using peak area measurements (RSD 0.69-1.38%, n = 8), and limits of detection (4-12 microg L(-1)) were achieved for methyl mercury, inorganic mercury and phenyl mercury. PMID:14667153

  8. A mercury flow meter for ion thruster testing. [response time, thermal sensitivity

    NASA Technical Reports Server (NTRS)

    Wilbur, P. J.

    1973-01-01

    The theory of operation of the thermal flow meter is presented, and a theoretical model is used to determine design parameters for a device capable of measuring mercury flows in the range of 0 to 5 gm/hr. Flow meter construction is described. Tests performed using a positive displacement mercury pump as well as those performed with the device in the feed line of an operating thruster are discussed. A flow meter response time of about a minute and a sensitivity of about 10 mv/gm/hr are demonstrated. Additional work to relieve a sensitivity of the device to variations in ambient temperature is indicated to improve its quantitative performance.

  9. The impact of a hot sodium ion population on the growth of the Kelvin-Helmholtz instability in Mercury's magnetotail

    NASA Astrophysics Data System (ADS)

    Gingell, P. W.; Sundberg, T.; Burgess, D.

    2015-07-01

    Observations of Mercury's local plasma environment by MErcury Surface, Space ENvironment, GEochemistry, and Ranging have revealed that the planet hosts a strongly asymmetric magnetosphere as a result of an off-axis dipolar or quadrupolar internal field and significant finite Larmor radius effects at the boundary layer between magnetospheric and solar wind plasma environments. One important asymmetry appears in the growth and evolution of Kelvin-Helmholtz (K-H) waves at the dawn and dusk flanks of the magnetopause. Linear analysis and global hybrid simulations support a dusk-dawn asymmetry in the growth rate caused by finite Larmor radius effects, and indeed, K-H waves have been almost exclusively observed at the dusk magnetopause during northward interplanetary magnetic field. Observations of these K-H waves at sodium gyroscales invite investigation into the impact of the hot planetary sodium ion population, itself distributed preferentially on the dusk flank, on the growth of the K-H instability and associated plasma transport. We present local two-dimensional hybrid simulations of the dusk and dawn boundary layers, with varying magnetospheric sodium ion number density, and examine the associated changes in the growth rates of the K-H instability, K-H wave spectra, and cross-boundary particle transport. We show that gyroresonance between growing K-H vortices and sodium ion gyration introduces a strong spectral peak at sodium gyroscales at the dusk magnetopause, that an increase in sodium ion number density increases dawn-dusk asymmetry of K-H growth rates, and that cross-boundary particle transport decreases with sodium number density at the dawn flank.

  10. Reduction of the Algicidal Properties of Copper and Mercury Ions by Chitin and Chitosan.

    ERIC Educational Resources Information Center

    Blair, Hal S.; And Others

    1982-01-01

    When chitin and chitosan were added to growing cultures of Chlorella containing various quantities of toxic metals (copper and mercury), it was found that the presence of these materials reduced the toxic effect of the metals. Background information, procedures, and results are provided for this experiment. (Author/JN)

  11. Magnetic Reconnection Controls Impacts of Solar Wind Ions at Mercury's Surface : Investigation By Global Hybrid Simulations

    NASA Astrophysics Data System (ADS)

    Chanteur, G. M.; Modolo, R.; Leblanc, F.

    2014-12-01

    MESSENGER has revealed the complexity of the Hermean magnetic field which is dominated by dipolar and quadrupolar components (Anderson et al., 2012 and references therein). By contrast to other magnetized planets having large scale dynamo driven magnetic fields Mercury has a quadrupolar field large enough to reinforce the dipolar field at high northern latitudes and to shape the topology of the planetary field in the equatorial region and the southern hemisphere. Magnetic reconnection at Mercury is extremely effective for all IMF orientations [DiBraccio et al., JGR, 2013]. Global hybrid simulations by Richer et al. (2012) have demonstrated the dramatic influence of the quadrupolar field of Mercury on the topology of the Hermean magnetosphere. Then Chanteur et al. (AOGS 2014) have investigated the impacts of solar wind protons and alphas on Mercury's surface with the same hybrid code and have presented a case study to demonstrate the importance of magnetic reconnection between the IMF and the planetary field in this process. We will present a set of different results corresponding to different configurations depending upon the IMF orientation and solar wind parameters. References Anderson, B. J., C. L. Johnson, H. Korth, R. M. Winslow, J. E. Borovsky, M. E. Purucker, J. A. Slavin, S. C. Solomon, M. T. Zuber, and R. L. McNutt Jr. (2012), Low-degree structure in Mercury's planetary magnetic field, J. Geophys. Res., 117, E00L12, doi:10.1029/2012JE004159. DiBraccio, G. A., J. A. Slavin, S. A. Boardsen, B. J. Anderson, H. Korth, T. H. Zurbuchen, J. M. Raines, D. N. Baker, R. L. McNutt Jr., and S. C. Solomon (2013), MESSENGER observations of magnetopause structure and dynamics at Mercury, J. Geophys. Res. Space Phys., 118, 997-1008, doi:10.1002/jgra50123. Richer, E., R. Modolo, G. M. Chanteur, S. Hess, and F. Leblanc (2012), A global hybrid model for Mercury's interaction with the solar wind: Case study of the dipole representation, J. Geophys. Res., 117, A10228, doi:10

  12. Ion plume/S-band carrier interaction study

    NASA Technical Reports Server (NTRS)

    Stanton, P.

    1981-01-01

    A study was performed to determine the effects of a mercury ion thruster plume on an S-band telecommunication carrier. Experiments were carried out on a 30 cm thruster in a JPL test chamber. Results from simple analytical models were compared with the above measurements and major discrepancies were discovered. Modifications to the electron density model provided a qualitative explanation, but further work is necessary for a quantitative answer. The results indicate the effects of the plume, on S and X Band telecommunications will be minor, with the possible exception of critical angle blockage.

  13. Simultaneous determination of arsenic and mercury species in rice by ion-pairing reversed phase chromatography with inductively coupled plasma mass spectrometry.

    PubMed

    Fang, Yong; Pan, Yushi; Li, Peng; Xue, Mei; Pei, Fei; Yang, Wenjian; Ma, Ning; Hu, Qiuhui

    2016-12-15

    An analytical method using reversed phase chromatography-inductively coupled plasma mass spectrometry for arsenic and mercury speciation analysis was described. The effect of ion-pairing reagent on simultaneous separation of four arsenic (arsenite, arsenate, monomethlyarsonate and dimethylarsinate) and three mercury species (inorganic mercury (Hg(II)), methylmecury and ethylmercury) was investigated. Parameters including concentrations and pH of the mobile phase were optimized. The separation and re-equilibration time was attained within 20min. Meanwhile, a sequential extraction method for arsenic and mercury in rice was tested. Subsequently, 1% HNO3 microwave-assisted extraction was chosen. Calibration curves based on peak area measurements were linear with correlation coefficient greater than 0.9958 for each species in the range studied. The detection limits of the species were in the range of 0.84-2.41μg/L for arsenic and 0.01-0.04μg/L for mercury, respectively. The proposed method was then successfully applied for the simultaneous determination of arsenic and mercury species in rice flour standard material and two kinds of rice from local markets. PMID:27451225

  14. A study of the influence of Hg(6(3)P2) population in a low-pressure discharge on mercury ion emission at 194.2 nm

    NASA Technical Reports Server (NTRS)

    Maleki, L.; Blasenheim, B. J.; Janik, G. R.

    1990-01-01

    A low-pressure mercury-argon discharge, similar to the type existing in the mercury lamp for the trapped-ion standard, is probed with a new technique of laser spectroscopy to determine the influence of the Hg(6 3P(sub 2)) population on discharge emission. The discharge is excited with inductively coupled rf power. Variations in the intensity of emission lines in the discharge were examined as lambda = 546.1 nm light from a continuous wave (CW) laser excited the Hg(6 3P(sub 2)) to (7 3S (sub 1)) transition. The spectrum of the discharge viewed in the region of laser irradiation showed increased emission in lambda = 546.1, 435.8, 404.7, 253.7, and 194.2 nm lines. Other lines in Hg I exhibited a decrease in emission. When the discharge was viewed outside the region of laser irradiation, all lines exhibited an increased emission. Based on these results, it is concluded that the dominant mechanism for the excitation of higher lying levels of mercury is the the electron-impact excitation via the 3P(sub 2) level. The depopulation of this metastable is also responsible for the observed increase in the electron temperature when the laser irradiates the discharge. It is also concluded that the 3P(sub 2) metastable level of mercury does not play a significant role in the excitation of the 3P(sub 1/2) level of mercury ion.

  15. Colorimetric Signal Amplification Assay for Mercury Ions Based on the Catalysis of Gold Amalgam.

    PubMed

    Chen, Zhengbo; Zhang, Chenmeng; Gao, Qinggang; Wang, Guo; Tan, Lulu; Liao, Qing

    2015-11-01

    Mercury is a major threat to the environment and to human health. It is highly desirable to develop a user-friendly kit for on-site mercury detection. Such a method must be able to detect mercury below the threshold levels (10 nM) for drinking water defined by the U.S. Environmental Protection Agency. Herein, we for the first time reported catalytically active gold amalgam-based reaction between 4-nitrophenol and NaBH4 with colorimetric sensing function. We take advantage of the correlation between the catalytic properties and the surface area of gold amalgam, which is proportional to the amount of the gold nanoparticle (AuNP)-bound Hg(2+). As the concentration of Hg(2+) increases until the saturation of Hg onto the AuNPs, the catalytic performance of the gold amalgam is much stronger due to the formation of gold amalgam and the increase of the nanoparticle surface area, leading to the decrease of the reduction time of 4-nitrophenol for the color change. This sensing system exhibits excellent selectivity and ultrahigh sensitivity up to the 1.45 nM detection limit. The practical use of this system for Hg(2+) determination in tap water samples is also demonstrated successfully. PMID:26434980

  16. Sub-mm Scale Fiber Guided Deep/Vacuum Ultra-Violet Optical Source for Trapped Mercury Ion Clocks

    NASA Technical Reports Server (NTRS)

    Yi, Lin; Burt, Eric A.; Huang, Shouhua; Tjoelker, Robert L.

    2013-01-01

    We demonstrate the functionality of a mercury capillary lamp with a diameter in the sub-mm range and deep ultraviolet (DUV)/ vacuum ultraviolet (VUV) radiation delivery via an optical fiber integrated with the capillary. DUV spectrum control is observed by varying the fabrication parameters such as buffer gas type and pressure, capillary diameter, electrical resonator design, and temperature. We also show spectroscopic data of the 199Hg+ hyper-fine transition at 40.5GHz when applying the above fiber optical design. We present efforts toward micro-plasma generation in hollow-core photonic crystal fiber with related optical design and theoretical estimations. This new approach towards a more practical DUV optical interface could benefit trapped ion clock developments for future ultra-stable frequency reference and time-keeping applications.

  17. Planned flight test of a mercury ion auxiliary propulsion system. 1: Objectives, systems descriptions, and mission operations

    NASA Technical Reports Server (NTRS)

    Power, J. C.

    1978-01-01

    A planned flight test of an 8 cm diameter, electron-bombardment mercury ion thruster system is described. The primary objective of the test is to flight qualify the 5 mN (1 mlb.) thruster system for auxiliary propulsion applications. A seven year north-south stationkeeping mission was selected as the basis for the flight test operating profile. The flight test, which will employ two thruster systems, will also generate thruster system space performance data, measure thruster-spacecraft interactions, and demonstrate thruster operation in a number of operating modes. The flight test is designated as SAMSO-601 and will be flown aboard the shuttle-launched Air Force space test program P80-1 satellite in 1981. The spacecraft will be 3- axis stabilized in its final 740 km circular orbit, which will have an inclination of approximately greater than 73 degrees. The spacecraft design lifetime is three years.

  18. Mercury-induced fragmentation of n-decane and n-undecane in positive mode ion mobility spectrometry.

    PubMed

    Gunzer, F

    2015-09-21

    Ion mobility spectrometry is a well-known technique for trace gas analysis. Using soft ionization techniques, fragmentation of analytes is normally not observed, with the consequence that analyte spectra of single substances are quite simple, i.e. showing in general only one peak. If the concentration is high enough, an extra cluster peak involving two analyte molecules can often be observed. When investigating n-alkanes, different results regarding the number of peaks in the spectra have been obtained in the past using this spectrometric technique. Here we present results obtained when analyzing n-alkanes (n-hexane to n-undecane) with a pulsed electron source, which show no fragmentation or clustering at all. However, when investigating a mixture of mercury and an n-alkane, a situation quite typical in the oil and gas industry, a strong fragmentation and cluster formation involving these fragments has been observed exclusively for n-decane and n-undecane. PMID:26247063

  19. Planned flight test of a mercury ion auxiliary propulsion system. I - Objectives, systems descriptions, and mission operations

    NASA Technical Reports Server (NTRS)

    Power, J. L.

    1978-01-01

    A planned flight test of an 8-cm diameter, electron-bombardment mercury ion thruster system is described. The primary objective of the test is to flight qualify the 5 mN thruster system for auxiliary propulsion applications. A seven year north-south stationkeeping mission was selected as the basis for the flight test operating profile. The flight test, which will employ two thruster systems, will also generate thruster system space performance data, measure thruster-spacecraft interactions, and demonstrate thruster operation in a number of operating modes. The flight test is designated as SAMSO-601 and will be flown aboard the Shuttle-launched Air Force Space Test Program P80-1 satellite in 1981. The spacecraft will be 3-axis stabilized in its final 740 km circular orbit, which will have an inclination of at least 73 degrees. The spacecraft design lifetime is three years.

  20. Preparation of chitosan-graft-polyacrylamide magnetic composite microspheres for enhanced selective removal of mercury ions from water.

    PubMed

    Li, Kun; Wang, Yawen; Huang, Mu; Yan, Han; Yang, Hu; Xiao, Shoujun; Li, Aimin

    2015-10-01

    A novel magnetic composite microsphere based on polyacrylamide (PAM)-grafted chitosan and silica-coated Fe3O4 nanoparticles (CS-PAM-MCM) was successfully synthesized by a simple method. The molecular structure, surface morphology, and magnetic characteristics of the composite microsphere were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), vibrating-sample magnetometer (VSM), and scanning electron microscopy (SEM). The prepared CS-PAM-MCM was applied as an efficient adsorbent for the removal of copper(II), lead(II), and mercury(II) ions from aqueous solutions in respective single, binary, and ternary metal systems. Compared with chitosan magnetic composite microsphere (CS-MCM) without modification, CS-PAM-MCM showed improved adsorption capacity for each metal ion and highly selective adsorption for Hg from Pb and Cu. This improvement is attributed to the formation of stronger interactions between Hg and the amide groups of PAM branches for chelating effects. The adsorption isotherms of Hg/Cu and Hg/Pb binary metal systems onto CS-PAM-MCM are both well-described by extended and modified Langmuir models, indicating that the removal of the three aforementioned metal ions may follow a similar adsorption manner; that is, through a homogeneous monolayer chemisorption process. Furthermore, these magnetic adsorbents could be easily regenerated in EDTA aqueous solution and reused virtually without any adsorption capacity loss. PMID:26073848

  1. A novel aptasensor based on single-molecule force spectroscopy for highly sensitive detection of mercury ions.

    PubMed

    Li, Qing; Michaelis, Monika; Wei, Gang; Colombi Ciacchi, Lucio

    2015-08-01

    We have developed a novel aptasensor based on single-molecule force spectroscopy (SMFS) capable of detecting mercury ions (Hg(2+)) with sub-nM sensitivity. The single-strand (ss) DNA aptamer used in this work is rich in thymine (T) and readily forms T-Hg(2+)-T complexes in the presence of Hg(2+). The aptamer was conjugated to an atomic force microscope (AFM) probe, and the adhesion force between the probe and a flat graphite surface was measured by single-molecule force spectroscopy (SMFS). The presence of Hg(2+) ions above a concentration threshold corresponding to the affinity constant of the ions for the aptamer (about 5 × 10(9) M(-1)) could be easily detected by a change of the measured adhesion force. With our chosen aptamer, we could reach an Hg(2+) detection limit of 100 pM, which is well below the maximum allowable level of Hg(2+) in drinking water. In addition, this aptasensor presents a very high selectivity for Hg(2+) over other metal cations, such as K(+), Ca(2+), Zn(2+), Fe(2+), and Cd(2+). Furthermore, the effects of the ionic strength and loading rate on the Hg(2+) detection were evaluated. Its simplicity, reproducibility, high selectivity and sensitivity make our SMFS-based aptasensor advantageous with respect to other current Hg(2+) sensing methods. It is expected that our strategy can be exploited for monitoring the pollution of water environments and the safety of potentially contaminated food. PMID:26075518

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. Application of a DNA-based luminescence switch-on method for the detection of mercury(II) ions in water samples from Hong Kong

    NASA Astrophysics Data System (ADS)

    He, Hong-Zhang; Leung, Ka-Ho; Fu, Wai-Chung; Shiu-Hin Chan, Daniel; Leung, Chung-Hang; Ma, Dik-Lung

    2012-12-01

    Mercury is a highly toxic environmental contaminant that damages the endocrine and central nervous systems. In view of the contamination of Hong Kong territorial waters with anthropogenic pollutants such as trace heavy metals, we have investigated the application of our recently developed DNA-based luminescence methodology for the rapid and sensitive detection of mercury(II) ions in real water samples. The assay was applied to water samples from Shing Mun River, Nam Sang Wai and Lamma Island sea water, representing natural river, wetland and sea water media, respectively. The results showed that the system could function effectively in real water samples under conditions of low turbidity and low metal ion concentrations. However, high turbidity and high metal ion concentrations increased the background signal and reduced the performance of this assay.

  8. Germanium-doped carbon dots as a new type of fluorescent probe for visualizing the dynamic invasions of mercury(ii) ions into cancer cells

    NASA Astrophysics Data System (ADS)

    Yuan, Yun Huan; Li, Rong Sheng; Wang, Qiang; Wu, Zhu Lian; Wang, Jian; Liu, Hui; Huang, Cheng Zhi

    2015-10-01

    Carbon dots doped with germanium (GeCDs) were firstly prepared by a new simple 15 min carbonation synthesis route, exhibiting excitation-independent photoluminescence (PL), which could avoid autofluorescence in bioimaging applications. The as-prepared GeCDs have low cell toxicity, good biocompatibility, high intracellular delivery efficiency, stability and could be applied for detection of mercury(ii) ions with excellent selectivity in complicated medium. It is to be noted that the as-prepared GeCDs used as a new type of probe for visualization of dynamic invasions of mercury(ii) ions into Hep-2 cells display greatly different properties from most of the previously reported CDs which are regularly responsive to iron ions. All the results suggest that the GeCDs can be employed for visualization and monitoring of the significant physiological changes of living cells induced by Hg2+.Carbon dots doped with germanium (GeCDs) were firstly prepared by a new simple 15 min carbonation synthesis route, exhibiting excitation-independent photoluminescence (PL), which could avoid autofluorescence in bioimaging applications. The as-prepared GeCDs have low cell toxicity, good biocompatibility, high intracellular delivery efficiency, stability and could be applied for detection of mercury(ii) ions with excellent selectivity in complicated medium. It is to be noted that the as-prepared GeCDs used as a new type of probe for visualization of dynamic invasions of mercury(ii) ions into Hep-2 cells display greatly different properties from most of the previously reported CDs which are regularly responsive to iron ions. All the results suggest that the GeCDs can be employed for visualization and monitoring of the significant physiological changes of living cells induced by Hg2+. Electronic supplementary information (ESI) available: Experimental section and additional figures (Fig. S1-15). See DOI: 10.1039/c5nr05326a

  9. A novel voltammetric sensor for sensitive detection of mercury(II) ions using glassy carbon electrode modified with graphene-based ion imprinted polymer.

    PubMed

    Ghanei-Motlagh, Masoud; Taher, Mohammad Ali; Heydari, Abolfazl; Ghanei-Motlagh, Reza; Gupta, Vinod K

    2016-06-01

    In this paper, a novel strategy was proposed to prepare ion-imprinted polymer (IIP) on the surface of reduced graphene oxide (RGO). Polymerization was performed using methacrylic acid (MAA) as the functional monomer, ethylene glycol dimethacrylate (EGDMA) as the cross-linker, 2,2'-((9E,10E)-1,4-dihydroxyanthracene-9,10-diylidene) bis(hydrazine-1-carbothioamide) (DDBHCT) as the chelating agent and ammonium persulfate (APS) as initiator, via surface imprinted technique. The RGO-IIP was characterized by means of Fourier transform infrared spectroscopy (FT-IR), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM) and thermogravimetric analysis (TGA). The electrochemical procedure was based on the accumulation of Hg(II) ions at the surface of a modified glassy carbon electrode (GCE) with RGO-IIP. The prepared RGO-IIP sensor has higher voltammetric response compared to the non-imprinted polymer (NIP), traditional IIP and RGO. The RGO-IIP modified electrode exhibited a linear relationship toward Hg(II) concentrations ranging from 0.07 to 80 μg L(-1). The limit of detection (LOD) was found to be 0.02 μg L(-1) (S/N=3), below the guideline value from the World Health Organization (WHO). The applicability of the proposed electrochemical sensor to determination of mercury(II) ions in different water samples was reported. PMID:27040231

  10. State-Selective Quantum Interference Observed in the Recombination of Highly Charged Hg{sup 75+{center_dot}}{sup {center_dot}}{sup {center_dot}}{sup 78+} Mercury Ions in an Electron Beam Ion Trap

    SciTech Connect

    Gonzalez Martinez, A.J.; Lopez-Urrutia, J.R. Crespo; Braun, J.; Brenner, G.; Bruhns, H.; Lapierre, A.; Mironov, V.; Soria Orts, R.; Tawara, H.; Trinczek, M.; Ullrich, J.; Scofield, J.H.

    2005-05-27

    We present experimental data on the state-selective quantum interference between different pathways of photorecombination, namely, radiative and dielectronic recombination, in the KLL resonances of highly charged mercury ions. The interference, observed for well resolved electronic states in the Heidelberg electron beam ion trap, manifests itself in the asymmetry of line shapes, characterized by ''Fano factors,'' which have been determined with unprecedented precision, as well as their excitation energies, for several strong dielectronic resonances.

  11. The impact of a hot sodium ion population on the growth of the Kelvin-Helmholtz instability in Mercury's magnetotail

    NASA Astrophysics Data System (ADS)

    Gingell, P.; Sundberg, T.; Burgess, D.

    2014-12-01

    Observations of Mercury's local plasma environment by MESSENGER have revealed that the planet hosts a strongly asymmetric magnetosphere as a result of an off-axis dipolar or quadrupolar internal field, and significant finite Larmor radius effects at the boundary layer between magnetospheric and solar wind plasma environments. One important asymmetry appears in the growth and evolution of Kelvin-Helmholtz (K-H) waves at the dawn and dusk flanks of the magnetopause. Linear analysis and global hybrid simulations support a dusk-dawn asymmetry in the growth rate caused by finite Larmor radius effects, and indeed K-H waves have been exclusively observed at the dusk magnetopause during northward IMF. Observations of these K-H waves at sodium gyro-scales invites investigation into the impact of the hot planetary sodium ion population, itself distributed preferentially on the dusk flank, on the growth of the K-H instability and associated plasma transport. We present local two- and three-dimensional hybrid simulations of the dusk and dawn boundary layers, with varying magnetospheric sodium ion number density, and examine the associated changes in the growth rates of the K-H instability, K-H wave spectra, and cross-boundary particle transport. We show that gyroresonance between growing K-H vortices and sodium ion gyration introduces a strong spectral peak at sodium gyro-scales at the dusk magnetopause, that an increase in sodium ion number density increases dawn-dusk asymmetry of K-H growth rates, and that cross-boundary particle transport increases with sodium number density.

  12. Fifteen cm mercury ion thruster research, 1976. [performance as effected by the use of shag optics at 33 v discharge voltage

    NASA Technical Reports Server (NTRS)

    Wilbur, P. J.

    1976-01-01

    Improvements in 15 cm diameter, SERT II, mercury ion thruster performance effected by the use of SHAG optics at 33 V discharge voltage were discussed. At a 200 eV/ion discharge power, 90 percent propellant utilization and 660 mA beam current condition a doubly-to-singly charged ion current ratio of about 4 percent was measured. Performance of the 15 cm multipole mercury thruster (optimized for length and the point of electron injection) was compared to that of divergent (SERT II) and cusped field designs and found to be comparable. The need for a magnetic baffle in the multipole thruster was identified and the preferred point of electron injection was at the upstream end of the discharge chamber. Results of preliminary tests on the effects of discharge voltage and total accelerating voltage on perveance and beam divergence characteristics of two grid ion optics were examined. Experimental data showing the effect of target temperature on sputtering rates in a mercury discharge environment were presented and a deficiency in the tests procedure was identified.

  13. ULF Waves at Mercury

    NASA Astrophysics Data System (ADS)

    Kim, E.-H.; Boardsen, S. A.; Johnson, J. R.; Slavin, J. A.

    2016-02-01

    This chapter provides a brief overview of the observed characteristics of ultra-low-frequency (ULF) waves at Mercury. It shows how field-aligned propagating ULF waves at Mercury can be generated by externally driven fast compressional waves (FWs) via mode conversion at the ion-ion hybrid resonance. Then, the chapter reviews the interpretation that the strong magnetic compressional waves near and its harmonics observed with 20 of Mercury's magnetic equator could be the ion Bernstein wave (IBW) mode. A recent statistical study of ULF waves at Mercury based on MESSENGER data reported the occurrence and polarization of the detected waves. The chapter further introduces the field line resonance and the electromagnetic ion Bernstein waves to explain such waves, and shows that both theories can partially explain the observations.

  14. Modified Mesoporous Silica (SBA–15) with Trithiane as a new effective adsorbent for mercury ions removal from aqueous environment

    PubMed Central

    2014-01-01

    Background Removal of mercury from aqueous environment has been highly regarded in recent years and different methods have been tested for this purpose. One of the most effective ways for mercury ions (Hg+2) removal is the use of modified nano porous compounds. Hence, in this work a new physical modification of mesoporous silica (SBA-15) with 1, 3, 5 (Trithiane) as modifier ligand and its application for the removal of Hg+2 from aqueous environment has been investigated. SBA-15 and Trithiane were synthesized and the presence of ligand in the silica framework was demonstrated by FTIR spectrum. The amounts of Hg+2 in the samples were determined by cold vapor generation high resolution continuum source atomic absorption spectroscopy. Also, the effects of pH, stirring time and weight of modified SBA-15 as three major parameters for effective adsorption of Hg+2 were studied. Results The important parameter for the modification of the adsorbent was Modification ratio between ligand and adsorbent in solution which was 1.5. The results showed that the best Hg+2 removal condition was achieved at pH = 5.0, stirring time 15 min and 15.0 mg of modified adsorbent. Moreover, the maximum percentage removal of Hg+2 and the capacity of adsorbent were 85% and 10.6 mg of Hg+2/g modified SBA-15, respectively. Conclusions To sum up, the present investigation introduced a new modified nano porous compound as an efficient adsorbent for removal of Hg+2 from aqueous environment. PMID:25097760

  15. Nanoporous gold based optical sensor for sub-ppt detection of mercury ions.

    PubMed

    Zhang, Ling; Chang, Haixin; Hirata, Akihiko; Wu, Hongkai; Xue, Qi-Kun; Chen, Mingwei

    2013-05-28

    Precisely probing heavy metal ions in water is important for molecular biology, environmental protection, and healthy monitoring. Although many methods have been reported in the past decade, developing a quantitative approach capable of detecting sub-ppt level heavy metal ions with high selectivity is still challenging. Here we report an extremely sensitive and highly selective nanoporous gold/aptamer based surface enhanced resonance Raman scattering (SERRS) sensor. The optical sensor has an unprecedented detection sensitivity of 1 pM (0.2 ppt) for Hg(2+) ions, the most sensitive Hg(2+) optical sensor known so far. The sensor also exhibits excellent selectivity. Dilute Hg(2+) ions can be identified in an aqueous solution containing 12 metal ions as well as in river water and underground water. Moreover, the SERRS sensor can be reused without an obvious loss of the sensitivity and selectivity even after 10 cycles. PMID:23590120

  16. Diagnostic evaluations of a beam-shielded 8-cm mercury ion thruster

    NASA Technical Reports Server (NTRS)

    Nakanishi, S.

    1978-01-01

    An engineering model thruster fitted with a remotely actuated graphite fiber polyimide composite beam shield was tested in a 3- by 6.5-meter vacuum facility for in-situ assessment of beam shield effects on thruster performance. Accelerator drain current neutralizer floating potential and ion beam floating potential increased slightly when the shield was moved into position. A target exposed to the low density regions of the ion beam was used to map the boundaries of energetic fringe ions capable of sputtering. The particle efflux was evaluated by measurement of film deposits on cold, heated, bare, and enclosed glass slides.

  17. Behavior of mercury, lead, cesium, and uranyl ions on four SRS soils

    SciTech Connect

    Bibler, J.P.; Marson, D.B.

    1992-03-20

    Samples of four Savannah River Site (SRS) soils were tested for sorption behavior with Hg[sup 2+], Pb[sup 2+], UO[sub 2][sup 2+], and Cs[sup +] ions. The purpose of the study was to determine the selectivity of the different soils for these ions alone and in the presence of the competing cations, H[sup +] and Ca[sup 2+]. Distribution constants, Kd's, for the test ions in various solutions have been determined for the four soils. In general, sorption by all of the soils appeared to be more complex than a simple ion exchange or adsorption process. In particular, the presence of organic matter in soil increased the capacity of the soil due to its chelating ability. Similar soils did not react similarly toward each metal cation.

  18. Behavior of mercury, lead, cesium, and uranyl ions on four SRS soils

    SciTech Connect

    Bibler, J.P.; Marson, D.B.

    1992-03-20

    Samples of four Savannah River Site (SRS) soils were tested for sorption behavior with Hg{sup 2+}, Pb{sup 2+}, UO{sub 2}{sup 2+}, and Cs{sup +} ions. The purpose of the study was to determine the selectivity of the different soils for these ions alone and in the presence of the competing cations, H{sup +} and Ca{sup 2+}. Distribution constants, Kd`s, for the test ions in various solutions have been determined for the four soils. In general, sorption by all of the soils appeared to be more complex than a simple ion exchange or adsorption process. In particular, the presence of organic matter in soil increased the capacity of the soil due to its chelating ability. Similar soils did not react similarly toward each metal cation.

  19. Label free and high specific detection of mercury ions based on silver nano-liposome.

    PubMed

    Priyadarshini, Eepsita; Pradhan, Nilotpala; Pradhan, Arun K; Pradhan, Pallavi

    2016-06-15

    Herein, we report an eco-friendly, mild and one-pot approach for synthesis of silver nanoparticles via a lipopeptide biosurfactant - CHBS. The biosurfactant forms liposome vesicles when dispersed in an aqueous medium. The amino acid groups of the biosurfactant assists in the reduction of Ag(+) ions leading to the production of homogeneous silver nanoparticles, encapsulated within the liposome vesicle, as confirmed from TEM analysis. Rate of synthesis and size of particle were greatly dependent on pH and reaction temperature. Kinetic analysis suggests the involvement of an autocatalytic reaction and the observed rate constant (kobs) was found to decrease with temperature, suggesting faster reaction with increasing temperature. Furthermore, the silver nanoparticles served as excellent probes for highly selective and sensitive recognition of Hg(2+) ions. Interaction with Hg(2+) ions results in an immediate change in colour of nanoparticle solution form brownish red to milky white. With increasing Hg(2+) ions concentration, a gradual disappearance of SPR peak was observed. A linear relationship (A420/660) with an R(2) value of 0.97 was observed in the range of 20 to 100ppm Hg(2+) concentration. Hg(2+) ions are reduced to their elemental forms which thereby interact with the vesicles, leading to aggregation and precipitation of particles. The detection method avoids the need of functionalizing ligands and favours Hg(2+) detection in aqueous samples by visible range spectrophotometry and hence can be used for simple and rapid analysis. PMID:27045785

  20. Label free and high specific detection of mercury ions based on silver nano-liposome

    NASA Astrophysics Data System (ADS)

    Priyadarshini, Eepsita; Pradhan, Nilotpala; Pradhan, Arun K.; Pradhan, Pallavi

    2016-06-01

    Herein, we report an eco-friendly, mild and one-pot approach for synthesis of silver nanoparticles via a lipopeptide biosurfactant - CHBS. The biosurfactant forms liposome vesicles when dispersed in an aqueous medium. The amino acid groups of the biosurfactant assists in the reduction of Ag+ ions leading to the production of homogeneous silver nanoparticles, encapsulated within the liposome vesicle, as confirmed from TEM analysis. Rate of synthesis and size of particle were greatly dependent on pH and reaction temperature. Kinetic analysis suggests the involvement of an autocatalytic reaction and the observed rate constant (kobs) was found to decrease with temperature, suggesting faster reaction with increasing temperature. Furthermore, the silver nanoparticles served as excellent probes for highly selective and sensitive recognition of Hg2 + ions. Interaction with Hg2 + ions results in an immediate change in colour of nanoparticle solution form brownish red to milky white. With increasing Hg2 + ions concentration, a gradual disappearance of SPR peak was observed. A linear relationship (A420/660) with an R2 value of 0.97 was observed in the range of 20 to 100 ppm Hg2 + concentration. Hg2 + ions are reduced to their elemental forms which thereby interact with the vesicles, leading to aggregation and precipitation of particles. The detection method avoids the need of functionalizing ligands and favours Hg2 + detection in aqueous samples by visible range spectrophotometry and hence can be used for simple and rapid analysis.

  1. Novel styrylbenzothiazolium dye-based sensor for mercury, cyanide and hydroxide ions

    NASA Astrophysics Data System (ADS)

    Gwon, Seon-Young; Rao, Boddu Ananda; Kim, Hak-Soo; Son, Young-A.; Kim, Sung-Hoon

    2015-06-01

    We report the design and synthesis of a novel styrylbenzothiazolium (3) derivative developed as a fluorescent and colorimetric chemodosimeter with high selectivity toward Hg2+, CN- and OH- ions. An obvious loss of pink color in the presence of Hg2+ and CN- ions could make it a suitable "naked eye" indicator. We propose a sensing mechanism whereby the benzenoid form is changed to a quinoid form upon Hg2+ binding in a 1:1 stoichiometric ratio. More significantly, the styrylbenzothiazolium-Hg2+ and styrylbenzothiazolium-CN- complexes exhibited a dual-channel chromo-fluorogenic response. The sensors exhibit remarkable Hg2+-, CN--, and OH--selective red fluorescence but remain dark-green in the presence of a wide range of tested metal ions and anions.

  2. Cross sections for charge transfer between mercury ions and other metals

    NASA Technical Reports Server (NTRS)

    Vroom, D. A.; Rutherford, J. A.

    1977-01-01

    Cross sections for charge transfer between several ions and metals of interest to the NASA electro propulsion program have been measured. Specifically, the ions considered were Hg(+), Xe(+) and Cs(+) and the metals Mo, Fe, Al, Ti, Ta, and C. Measurements were made in the energy regime from 1 to 5,000 eV. In general, the cross sections for charge transfer were found to be less than 10 to the minus 15 power sq cm for most processes over the total energy range. Exceptions are Hg(+) in collision with Ti and Ta. The results obtained for each reaction are given in both graphical and numerical form in the text. For quick reference, the data at several ion velocities are condensed into one table given in the summary.

  3. Mesosponge Optical Sinks for Multifunctional Mercury Ion Assessment and Recovery from Water Sources.

    PubMed

    El-Safty, Sherif A; Sakai, Masaru; Selim, Mahmoud M; Hendi, Awatif A

    2015-06-24

    Using the newly developed organic-inorganic colorant membrane is an attractive approach for the optical detection, selective screening and removal, and waste management recovery of highly toxic elements, such as Hg(II) ions, from water sources. In the systematic mesosponge optical sinks (MOSs), anchoring organic colorants into 3D, well-defined cage cavities and interconnected tubular pores (10 nm) in the long microscale channels of membrane scaffolds enhances the requirements and intrinsic properties of the hierarchal membrane. This scalable design is the first to allow control of the multifunctional processes of a membrane in a one-step screening procedure, such as the detection/recognition, removal, and filtration of ultratrace Hg(II) ions, even from actual water sources (i.e., tap, underground). The selective recovery, detection, and extraction processes of Hg(II) ions in a heterogeneous mixture with inorganic cations and anions as well as organic molecules and surfactants are mainly dependent on the structure of the colorant agent, the pH conditions, competitive ion-system compositions and concentrations, and Hg-to-colorant binding events. Our result shows that the solid MOS membrane arrays can be repeatedly recycled and retain their hierarchal mesosponge sink character, avoiding fouling via the precipitation of metal salts as a result of the reuse cycle. The Hg(II) ion rejection and the permeation of nonselective elements based on the membrane filtration protocol may be key considerations in water purification and separation requirements. The selective recovery process of Hg(II) ions in actual contaminated samples collected from tap and underground water sources in Saudi Arabia indicates the practical feasibility of our designed MOS membrane arrays. PMID:25965073

  4. Simultaneous removal of acid green 25 and mercury ions from aqueous solutions using glutamine modified chitosan magnetic composite microspheres.

    PubMed

    Tao, Xue; Li, Kun; Yan, Han; Yang, Hu; Li, Aimin

    2016-02-01

    In this current work, the magnetic composite microsphere containing glutamine modified chitosan and silica coated Fe3O4 nanoparticles (CS-Gln-MCM) has been successfully prepared and extensively characterized, which is a kind of biodegradable materials. CS-Gln-MCM shows enhanced removal efficiency for both acid green 25 (AG25), an amphoteric dye, and mercury ions (Hg(2+)) from water in the respective while measured pH range compared with chitosan magnetic composite microsphere (CS-MCM) without modification. It is due to the fact that the grafted amino acid provides a variety of additional adsorption active sites and diverse adsorption mechanisms are involved. In AG25 and Hg(2+) aqueous mixture, the modified adsorbents bear preferential adsorption for AG25 over Hg(2+) in strong acidic solutions ascribed to multiple interactions between AG25 and CS-Gln-MCM, such as hydrogen bonding and electrostatic interactions. While, in weak acidic conditions, an efficient simultaneous removal is observed for different adsorption effects involved in aforementioned two pollutants. Besides, CS-Gln-MCM illuminates not only short equilibrium time for adsorption of each pollutant less than 20.0 min but also rapid magnetic separation from water and efficient regeneration after saturated adsorption. Therefore, CS-Gln-MCM bears great application potentials in water treatment. PMID:26618263

  5. A competitive immunochromatographic assay based on a novel probe for the detection of mercury (II) ions in water samples.

    PubMed

    Zhou, Yu; Zhang, Yuanyuan; Pan, Fengguang; Li, Yansong; Lu, Shiying; Ren, Honglin; Shen, Qingfeng; Li, Zhaohui; Zhang, Junhui; Chen, Qijun; Liu, Zengshan

    2010-07-15

    Mercury ions (Hg(2+)) are one of the most dangerous pollutants. Even at low concentration, it causes serious environmental and health problems. Current methods for the detection of Hg(2+) in environmental samples are tedious and time consuming because they require sophisticated instrumentation and complicated sample pre-treatment processes. In this work, a novel probe with high selectivity towards Hg(2+) was synthesized and a one step competitive immunochromatographic assay based on the probe for the detection of Hg(2+) was developed and applied for water samples. The detection conjugate was immobilized on one end of the nitrocellulose membrane (detection line) and anti-BSA polyclonal antibody was immobilized on the other end of the membrane (control line). Hg(2+) in samples competed with the probe to bind with immobilized detection conjugate. The visual detection limit of Hg(2+) in spiked water samples was found to be about 1 ppb. The qualitative assay can be performed within 15 min. The advantages of the technique are rapidity, low cost and without the need of any equipment and complicated sample preparation. PMID:20444590

  6. Software and system level tests of a test flight mercury ion thruster subsystem

    NASA Technical Reports Server (NTRS)

    Robson, R. R.; Low, C. A., Jr.

    1982-01-01

    A U.S. Air Force technology spacecraft flight is scheduled to carry an Ion Auxiliary Propulsion System (IAPS) as part of its experimental payload. This paper presents the results of the successful flight-software qualification and system-level tests which were performed on IAPS. The software tests were performed with an operating engineering model ion thruster and power processing unit, and failure/off-normal recovery modes, operation with and without temperature telemetry from the thruster vaporizers, and with closed-loop control or fixed setpoint operation of the thruster vaporizers. The system-level tests cover a wide range of thermal and operating conditions with the entire system exposed to a simulated space environment.

  7. Small Mercury Relativity Orbiter

    NASA Technical Reports Server (NTRS)

    Bender, Peter L.; Vincent, Mark A.

    1989-01-01

    The accuracy of solar system tests of gravitational theory could be very much improved by range and Doppler measurements to a Small Mercury Relativity Orbiter. A nearly circular orbit at roughly 2400 km altitude is assumed in order to minimize problems with orbit determination and thermal radiation from the surface. The spacecraft is spin-stabilized and has a 30 cm diameter de-spun antenna. With K-band and X-band ranging systems using a 50 MHz offset sidetone at K-band, a range accuracy of 3 cm appears to be realistically achievable. The estimated spacecraft mass is 50 kg. A consider-covariance analysis was performed to determine how well the Earth-Mercury distance as a function of time could be determined with such a Relativity Orbiter. The minimum data set is assumed to be 40 independent 8-hour arcs of tracking data at selected times during a two year period. The gravity field of Mercury up through degree and order 10 is solved for, along with the initial conditions for each arc and the Earth-Mercury distance at the center of each arc. The considered parameters include the gravity field parameters of degree 11 and 12 plus the tracking station coordinates, the tropospheric delay, and two parameters in a crude radiation pressure model. The conclusion is that the Earth-Mercury distance can be determined to 6 cm accuracy or better. From a modified worst-case analysis, this would lead to roughly 2 orders of magnitude improvement in the knowledge of the precession of perihelion, the relativistic time delay, and the possible change in the gravitational constant with time.

  8. Selective and Quantitative Detection of Trace Amounts of Mercury(II) Ion (Hg²⁺) and Copper(II) Ion (Cu²⁺) Using Surface-Enhanced Raman Scattering (SERS).

    PubMed

    Tang, Wenqiong; Chase, D Bruce; Sparks, Donald L; Rabolt, John F

    2015-07-01

    We report the development of a surface-enhanced Raman scattering (SERS)-based heavy metal ion sensor targeting the detection of mercury(II) ion (Hg(2+)) and copper(II) ion (Cu(2+)) with high sensitivity and selectivity. To achieve the detection of vibrational-spectroscopically silent heavy metal ions, the SERS substrate composed of gold nanorod (AuNR)-polycaprolactone (PCL) nanocomposite fibers was first functionalized using metal ion-binding ligands. Specifically, 2,5-dimercapto-1,3,4-thiadiazole dimer (di-DMT) and trimercaptotriazine (TMT) were attached to the SERS substrates serving as bridging molecules to capture Hg(2+) and Cu(2+), respectively, from solution. Upon heavy metal ion coordination, changes in the vibrational spectra of the bridging molecules, including variations in the peak-intensity ratios and peak shifts were observed and taken as indicators of the capture of the target ions. With rigorous spectral analysis, the coordination mechanism between the heavy metal ion and the corresponding bridging molecule was investigated. Mercury(II) ion primarily interacts with di-DMT through the cleavage of the disulfide bond, whereas Cu(2+) preferentially interacts with the heterocyclic N atoms in TMT. The specificity of the coordination chemistry provided both di-DMT and TMT with excellent selectivity for the detection of Hg(2+) and Cu(2+) in the presence of other interfering metal ion species. In addition, quantitative analysis of the concentration of the heavy metal ions was achieved through the construction of internal calibration curves using the peak-intensity ratios of 287/387 cm(-1) for Hg(2+) and 1234/973 cm(-1) for Cu(2+). PMID:26037773

  9. Assessment of mercury toxicity by the changes in oxygen consumption and ion levels in the freshwater snail, Pila globosa, and the mussel, Lamellidens marginalis

    SciTech Connect

    Sivaramakrishna, B.; Radhakrishnaiah, K.; Suresh, A. )

    1991-06-01

    There are many studies on mercury toxicity in freshwater fishes but very few on freshwater molluscs (Wright 1978) though they serve as bio-indicators of metal pollution. A few reports on marine gastropods and bivalves indicated the importance of these animals in metal toxicity studies. Hence, in the present study, the level of tolerance of the freshwater gastropod Pila globosa and of a freshwater bivalve Lamellidens marginalis mercury at lethal and sublethal levels was determined and compared with the rate of whole animal oxygen consumption and the level of sodium, potassium and calcium ions in the hepatopancreas and the foot of these animals. As the period of exposure is one of the important factors in toxicity studies, the level of tolerance was determined at 120 hours of exposure and the other parameters were analyzed at 1, 3 and 5 days in lethal and at 1, 7 and 15 days in sublethal concentrations.

  10. 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.

  11. Colorimetric detection of mercury ion based on unmodified gold nanoparticles and target-triggered hybridization chain reaction amplification

    NASA Astrophysics Data System (ADS)

    Wang, Qing; Yang, Xiaohan; Yang, Xiaohai; Liu, Pei; Wang, Kemin; Huang, Jin; Liu, Jianbo; Song, Chunxia; Wang, Jingjing

    2015-02-01

    A novel unmodified gold nanoparticles (AuNPs)-based colorimetric strategy for label-free, specific and sensitive mercury ion (Hg2+) detection was demonstrated by using thymine-Hg2+-thymine (T-Hg2+-T) recognition mechanism and hybridization chain reaction (HCR) amplification strategy. In this protocol, a structure-switching probe (H0) was designed to recognize Hg2+ and then propagated a chain reaction of hybridization events between two other hairpin probes (H1 and H2). In the absence of Hg2+, all hairpin probes could stably coexist in solution, the exposed sticky ends of hairpin probes were capable of stabilizing AuNPs. As a result, salt-induced AuNPs aggregation could be effectively prevented. In the presence of Hg2+, thymine bases of H0 could specifically interact with Hg2+ to form stable T-Hg2+-T complex. Consequently, the hairpin structure of H0 probe was changed. As H1/H2 probes were added, the HCR process could be triggered and nicked double-helixes were formed. Since it was difficult for the formed nicked double-helixes to inhibit salt-induced AuNPs aggregation, a red-to-blue color change was observed in the colloid solution as the salt concentration increased. With the elegant amplification effect of HCR, a detection limit of around 30 nM was achieved (S/N = 3), which was about 1-2 orders of magnitudes lower than that of previous unmodified AuNPs-based colorimetric methods. By using the T-Hg2+-T recognition mechanism, high selectivity was also obtained. As an unmodified AuNPs-based colorimetric strategy, the system was simple in design, convenient in operation, and eliminated the requirements of separation processes, chemical modifications, and sophisticated instrumentations.

  12. Removal of mercury(II) ions in aqueous solution using the peel biomass of Pachira aquatica Aubl: kinetics and adsorption equilibrium studies.

    PubMed

    Santana, Andrea J; Dos Santos, Walter N L; Silva, Laiana O B; das Virgens, Cesário F

    2016-05-01

    Mercury is a highly toxic substance that is a health hazard to humans. This study aims to investigate powders obtained from the peel of the fruit of Pachira aquatica Aubl, in its in natura and/or acidified form, as an adsorbent for the removal of mercury ions in aqueous solution. The materials were characterized by Fourier transform infrared spectroscopy and thermogravimetric analysis. The infrared spectra showed bands corresponding to the axial deformation of carbonyls from carboxylic acids, the most important functional group responsible for fixing the metal species to the adsorbent material. The thermograms displayed mass losses related to the decomposition of three major components, i.e., hemicellulose, cellulose, and lignin. The adsorption process was evaluated using cold-vapor atomic fluorescence spectrometry (CV AFS) and cold-vapor atomic absorption spectrometry (CV AAS). Three isotherm models were employed. The adsorption isotherm model, Langmuir-Freundlich, best represented the adsorption process, and the maximum adsorption capacity was predicted to be 0.71 and 0.58 mg g(-1) at 25 °C in nature and acidified, respectively. Adsorption efficiencies were further tested on real aqueous wastewater samples, and removal of Hg(II) was recorded as 69.6 % for biomass acidified and 76.3 % for biomass in nature. Results obtained from sorption experiments on real aqueous wastewater samples revealed that recovery of the target metal ions was very satisfactory. The pseudo-second-order model showed the best correlation to the experimental data. The current findings showed that the investigated materials are potential adsorbents for mercury(II) ion removal in aqueous solution, with acidified P. aquatica Aubl being the most efficient adsorbent. PMID:27084802

  13. A mechanosynthesized, sequential, cyclic fluorescent probe for mercury and iodide ions in aqueous solutions

    NASA Astrophysics Data System (ADS)

    Chen, Shangwen; Wang, Pipi; Jia, Chunmei; Lin, Qiang; Yuan, Wenbing

    2014-12-01

    A fluorescent Hg2+-selective chemosensor, 2,5-dimethoxybenzaldehyde thiosemicarbazone (1), was quantitatively prepared by grinding 2,5-dimethoxybenzaldehyde and thiosemicarbazide together in a ball mill for 15 min. The excitation and emission maxima of compound 1 are 347 and 450 nm, respectively. The reaction of this ligand with Hg2+ was investigated by FT-IR, 1H NMR, and fluorescence titration. Results show that the composition of the resulting Hg complex 1-Hg is 2:1 1:Hg, and that the S and imino N atoms serve as the binding sites of the ligand to the Hg2+ ions. Coordination-assisted fluorescence quenching results show that compound 1 exhibits a highly selective fluorescence response to trace amounts of Hg2+ in water. More importantly, the resulting complex 1-Hg can be used as a turn-on fluorescence probe for I- at a detection limit of 8.4 × 10-8 M. Thus, compound 1 is a relatively stable, sequential, cyclic fluorescent probe for Hg2+ and I-.

  14. A mechanosynthesized, sequential, cyclic fluorescent probe for mercury and iodide ions in aqueous solutions.

    PubMed

    Chen, Shangwen; Wang, Pipi; Jia, Chunmei; Lin, Qiang; Yuan, Wenbing

    2014-12-10

    A fluorescent Hg(2+)-selective chemosensor, 2,5-dimethoxybenzaldehyde thiosemicarbazone (1), was quantitatively prepared by grinding 2,5-dimethoxybenzaldehyde and thiosemicarbazide together in a ball mill for 15min. The excitation and emission maxima of compound 1 are 347 and 450nm, respectively. The reaction of this ligand with Hg(2+) was investigated by FT-IR, (1)H NMR, and fluorescence titration. Results show that the composition of the resulting Hg complex 1-Hg is 2:1 1:Hg, and that the S and imino N atoms serve as the binding sites of the ligand to the Hg(2+) ions. Coordination-assisted fluorescence quenching results show that compound 1 exhibits a highly selective fluorescence response to trace amounts of Hg(2+) in water. More importantly, the resulting complex 1-Hg can be used as a turn-on fluorescence probe for I(-) at a detection limit of 8.4×10(-8)M. Thus, compound 1 is a relatively stable, sequential, cyclic fluorescent probe for Hg(2+) and I(-). PMID:24945863

  15. A FRET-based fluorescent probe for mercury ions in water and living cells.

    PubMed

    Zhang, Bo; Ma, Pinyi; Gao, Dejiang; Wang, Xinghua; Sun, Ying; Song, Daqian; Li, Xuwen

    2016-08-01

    On the basis of fluorescence resonance energy transfer (FRET), a new rhodamine derivative (DRh) was synthesized as a ratiometric fluorescent probe for detecting Hg(2+) in water and living cells samples. The recognition properties of the probe DRh with metal ions had been investigated in H2O/CH3CN (9:1, v/v; Tris-HCl 50mmolL(-1); pH=7.0) solution by the UV-Vis spectrophotometry and the fluorescence spectrophotometry. The results showed that the probe DRh exhibited the selective recognition of Hg(2+). Upon the addition of Hg(2+), the spirolactam ring of probe DRh was opened. The 1:1 stoichiometric structure between DRh and Hg(2+) were supported by Job's plot, MS and DFT theoretical calculations. The linearly fluorescence intensity ratio (I582/I538) is proportional to the concentration of Hg(2+) in the range 0-30μmolL(-1). The limit of detection (LOD) of Hg(2+) is 0.008μmolL(-1) (base on S/N=3). The present probe was applied to the determination of Hg(2+) in neutral water samples and gave recoveries ranging from 104.5 to 107.9%. Furthermore, the fluorescent probe also can be applied as a bioimaging reagent for Hg(2+) detection in HeLa cells. PMID:27111158

  16. A FRET-based fluorescent probe for mercury ions in water and living cells

    NASA Astrophysics Data System (ADS)

    Zhang, Bo; Ma, Pinyi; Gao, Dejiang; Wang, Xinghua; Sun, Ying; Song, Daqian; Li, Xuwen

    2016-08-01

    On the basis of fluorescence resonance energy transfer (FRET), a new rhodamine derivative (DRh) was synthesized as a ratiometric fluorescent probe for detecting Hg2 + in water and living cells samples. The recognition properties of the probe DRh with metal ions had been investigated in H2O/CH3CN (9:1, v/v; Tris-HCl 50 mmol L- 1; pH = 7.0) solution by the UV-Vis spectrophotometry and the fluorescence spectrophotometry. The results showed that the probe DRh exhibited the selective recognition of Hg2 +. Upon the addition of Hg2 +, the spirolactam ring of probe DRh was opened. The 1:1 stoichiometric structure between DRh and Hg2 + were supported by Job's plot, MS and DFT theoretical calculations. The linearly fluorescence intensity ratio (I582/I538) is proportional to the concentration of Hg2 + in the range 0-30 μmol L- 1. The limit of detection (LOD) of Hg2 + is 0.008 μmol L- 1 (base on S/N = 3). The present probe was applied to the determination of Hg2 + in neutral water samples and gave recoveries ranging from 104.5 to 107.9%. Furthermore, the fluorescent probe also can be applied as a bioimaging reagent for Hg2 + detection in HeLa cells.

  17. Ion beam deposited protective films

    NASA Technical Reports Server (NTRS)

    Mirtich, M. J.

    1981-01-01

    Sputter deposition of adherent thin films on complex geometric surfaces by ion beam sources is examined in order to evaluate three different types of protective coatings for die materials. In the first experiment, a 30 cm diameter argon ion source was used to sputter deposit adherent metallic films up to eight microns thick on H-13 steel, and a thermal fatigue test specimen sputter deposited with metallic coatings one micron thick was immersed in liquid aluminum and cooled by water for 15,000 cycles to simulate operational environments. Results show that these materials do protect the steel by reducing thermal fatigue and thereby increasing die lifetime. The second experiment generated diamond-like carbon films using a dual beam ion source system that directed an eight cm argon ion source beam at the substrates. These films are still in the process of being evaluated for crystallinity, hardness and infrared absorption. The third experiment coated a fiber glass beam shield incorporated in the eight-cm diameter mercury ion thruster with molybdenum to ensure proper electrical and thermal properties. The coating maintained its integrity even under acceleration tests.

  18. A compensated multi-pole linear ion trap mercury frequency standard for ultra-stable timekeeping.

    PubMed

    Burt, Eric A; Diener, William A; Tjoelker, Robert L

    2008-12-01

    The multi-pole linear ion trap frequency standard (LITS) being developed at the Jet Propulsion Laboratory (JPL) has demonstrated excellent short- and long-term stability. The technology has now demonstrated long-term field operation providing a new capability for timekeeping standards. Recently implemented enhancements have resulted in a record line Q of 5 x 10(12) for a room temperature microwave atomic transition and a short-term fractional frequency stability of 5 x 10(-14)/tau(1/2). A scheme for compensating the second order Doppler shift has led to a reduction of the combined sensitivity to the primary LITS systematic effects below 5 x 10(-17) fractional frequency. Initial comparisons to JPL's cesium fountain clock show a systematic floor of less than 2 x 10(-16). The compensated multi-pole LITS at JPL was operated continuously and unattended for a 9-mo period from October 2006 to July 2007. During that time it was used as the frequency reference for the JPL geodetic receiver known as JPLT, enabling comparisons to any clock used as a reference for an International GNSS Service (IGS) site. Comparisons with the laser-cooled primary frequency standards that reported to the Bureau International des Poids et Mesures (BIPM) over this period show a frequency deviation less than 2.7 x 10(-17)/day. In the capacity of a stand-alone ultra-stable flywheel, such a standard could be invaluable for long-term timekeeping applications in metrology labs while its methodology and robustness make it ideal for space applications as well. PMID:19126484

  19. 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.

  20. Amperometric determination of cadmium, lead, and mercury metal ions using a novel polymer immobilised horseradish peroxidase biosensor system.

    PubMed

    Silwana, Bongiwe; Van Der Horst, Charlton; Iwuoha, Emmanuel; Somerset, Vernon

    2014-01-01

    This work was undertaken to develop a novel Pt/PANI-co-PDTDA/HRP biosensor system for environmental applications to investigate the inhibition studies by specific heavy metals, to provide data suitable for kinetic studies and further application of the biosensor to environmental samples. The newly constructed biosensor was compared to the data of the well-researched Pt/PANI/HRP biosensor. Optimised experimental conditions, such as the working pH for the biosensor was evaluated. The functionality of the amperometric enzyme sensor system was demonstrated by measuring the oxidation current of hydrogen peroxide followed by the development of an assay for determination of metal concentration in the presence of selected metal ions of Cd(2+), Pb(2+) and Hg(2+). The detection limits were found to be 8 × 10(-4) μg L(-1) for cadmium, 9.38 × 10(-4) μg L(-1) for lead and 7.89 × 10(-4) μg L(-1) for mercury. The World Health Organisation recommended that the maximum safety level of these metals should not exceed 0.005 mg L(-1) of Cd(2+), 0.01 mg L(-1) of Pb(2+) and 0.001 mg L(-1) of Hg(2+.), respectively. The analytical and detection data for the metals investigated were observed to be lower than concentrations recommended by several bodies including World Health Organisation and Environmental Protection Agencies. Therefore the biosensors developed in this study can be used to screen the presence of these metals in water samples because of its low detection limit. The modes of inhibition of horseradish peroxidase by Pb(2+), Cd(2+) and Hg(2+) as analysed using the double reciprocal plots of the Michaelis-Menten equation was found to be reversible and uncompetitive inhibition. Based on the Km(app) and Imax values for both biosensors the results have shown smaller values. These results also proved that the enzyme modified electrode is valuable and can be deployed for the determination or screening of heavy metals. PMID:25137538

  1. 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

  2. Synthesis and application of ion-imprinted polymer nanoparticles for the extraction and preconcentration of mercury in water and food samples employing cold vapor atomic absorption spectrometry.

    PubMed

    Roushani, Mahmoud; Abbasi, Shahryar; Khani, Hossein

    2015-09-01

    We describe a nanosized Hg(II)-imprinted polymer that was prepared from methacrylic acid as functional monomer, ethyleneglycol dimethacrylate as cross-linker, 2,2'-azobisisobutyronitrile (AIBN) as radical initiator, 2, 2'-di pyrydyl amine as a specific ligand, and Hg (II) as the template ions by precipitation polymerization method in methanol as the progeny solvent. Batch adsorption experiments were carried out as a function of pH, Hg (II) imprinted polymer amount, adsorption and desorption time, volume, and concentration of eluent. The synthesized polymer particles were characterized physically and morphologically by using infrared spectroscopy, thermogravimetric analysis, X-ray diffraction, and scanning electron microscopic techniques. The maximum adsorption capacity of the ion-imprinted and non-imprinted sorbent was 27.96 and 7.89 mg g(-1), respectively. Under optimal conditions, the detection limit for mercury was 0.01 μg L(-1) and the relative standard deviation was 3.2 % (n = 6) at the 1.00 μg L(-1). The procedure was applied to determination of mercury in fish and water samples with satisfactory results. PMID:26318321

  3. 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 ...

  4. Electrostatic Propulsion Beam Divergence Effects on Spacecraft Surfaces. Volume 2, Addendum 1: Ion Time-of-flight Determinations of Doubly to Singly Ionized Mercury Ion Ratios from a Mercury Electron Bombardment Discharge

    NASA Technical Reports Server (NTRS)

    Sellen, J. M., Jr.; Kemp, R. F.; Hall, D. F.

    1973-01-01

    The analysis of ion exhaust beam current flow for multiply charged ion species and the application to propellant utilization for the thruster are discussed. The ion engine in use in the experiments is a twenty centimeter diameter electromagnet electron bombardment engine. The experimental technique to determine the multiply charged ion abundance ratios using ion time of flight is described. An analytical treatment of the discharge action in producing various ion species has been carried out.

  5. Target-induced formation of gold amalgamation on DNA-based sensing platform for electrochemical monitoring of mercury ion coupling with cycling signal amplification strategy.

    PubMed

    Chen, Jinfeng; Tang, Juan; Zhou, Jun; Zhang, Lan; Chen, Guonan; Tang, Dianping

    2014-01-31

    Heavy metal ion pollution poses severe risks in human health and environmental pollutant, because of the likelihood of bioaccumulation and toxicity. Driven by the requirement to monitor trace-level mercury ion (Hg(2+)), herein we construct a new DNA-based sensor for sensitive electrochemical monitoring of Hg(2+) by coupling target-induced formation of gold amalgamation on DNA-based sensing platform with gold amalgamation-catalyzed cycling signal amplification strategy. The sensor was simply prepared by covalent conjugation of aminated poly-T(25) oligonucleotide onto the glassy carbon electrode by typical carbodiimide coupling. Upon introduction of target analyte, Hg(2+) ion was intercalated into the DNA polyion complex membrane based on T-Hg(2+)-T coordination chemistry. The chelated Hg(2+) ion could induce the formation of gold amalgamation, which could catalyze the p-nitrophenol with the aid of NaBH4 and Ru(NH3)6(3+) for cycling signal amplification. Experimental results indicated that the electronic signal of our system increased with the increasing Hg(2+) level in the sample, and has a detection limit of 0.02nM with a dynamic range of up to 1000nM Hg(2+). The strategy afforded exquisite selectivity for Hg(2+) against other environmentally related metal ions. In addition, the methodology was evaluated for the analysis of Hg(2+) in spiked tap-water samples, and the recovery was 87.9-113.8%. PMID:24439499

  6. Exploration of Mercury: The MESSENGER Mission

    NASA Astrophysics Data System (ADS)

    McNutt, Ralph

    The MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft, launched in August 2004 under NASA’s Discovery Program, has been collecting orbital observations of Mercury since March 2011. Elemental remote sensing of Mercury’s surface indicates that the moderately volatile elements Na, K, and S are not depleted relative to other terrestrial planets. Orbital images document widespread evidence for ancient volcanic activity ranging from effusive to explosive eruptions. High-resolution images have revealed the presence of irregular rimless depressions or “hollows” likely produced by the loss to diurnal heating or sputtering of some volatile-rich material. Polar deposits in permanently shadowed high-latitude regions are dominated by water ice on the basis of neutron spectrometry, surface reflectance, and thermal modeling with measured topography; in most locations the ice is covered by 10-30 cm of anomalously dark volatile material postulated to consist of complex organic compounds. The tectonic history of Mercury is dominated by greater planetary contraction than previously recognized; long-wavelength changes in topography postdated the emplacement of large expanses of volcanic plains. Gravity and topography measurements indicate that mascons and crustal thinning are associated with some impact basins. Mercury’s internal magnetic field is that of a dipole offset from the planet’s center by ~0.2 Mercury radii, a geometry difficult to reconcile with existing dynamo models. Magnetospheric measurements have revealed a highly time-variable and spatially structured particle environment. Despite complex feedbacks among the exosphere, magnetosphere, and surface, the large-scale structure of the exosphere - dominated by Na, Ca, and Mg - shows seasonal variations in general agreement with those expected from variations in solar flux with Mercury true anomaly but little variation with changing solar conditions. Energetic electron events are

  7. Planet Mercury

    NASA Technical Reports Server (NTRS)

    1974-01-01

    Mariner 10's first image of Mercury acquired on March 24, 1974. During its flight, Mariner 10's trajectory brought it behind the lighted hemisphere of Mercury, where this image was taken, in order to acquire important measurements with other instruments.

    This picture was acquired from a distance of 3,340,000 miles (5,380,000 km) from the surface of Mercury. The diameter of Mercury (3,031 miles; 4,878 km) is about 1/3 that of Earth.

    Images of Mercury were acquired in two steps, an inbound leg (images acquired before passing into Mercury's shadow) and an outbound leg (after exiting from Mercury's shadow). More than 2300 useful images of Mercury were taken, both moderate resolution (3-20 km/pixel) color and high resolution (better than 1 km/pixel) black and white coverage.

  8. Planet Mercury

    NASA Technical Reports Server (NTRS)

    1974-01-01

    Mariner 10's first image of Mercury acquired on March 24, 1974. During its flight, Mariner 10's trajectory brought it behind the lighted hemisphere of Mercury, where this image was taken, in order to acquire important measurements with other instruments. This picture was acquired from a distance of 3,340,000 miles (5,380,000 km) from the surface of Mercury. The diameter of Mercury (3,031 miles; 4,878 km) is about 1/3 that of Earth. Images of Mercury were acquired in two steps, an inbound leg (images acquired before passing into Mercury's shadow) and an outbound leg (after exiting from Mercury's shadow). More than 2300 useful images of Mercury were taken, both moderate resolution (3-20 km/pixel) color and high resolution (better than 1 km/pixel) black and white coverage.

  9. High-yield synthesis of strong photoluminescent N-doped carbon nanodots derived from hydrosoluble chitosan for mercury ion sensing via smartphone APP.

    PubMed

    Wang, Lei; Li, Baoqiang; Xu, Feng; Shi, Xinyao; Feng, Demeng; Wei, Daqing; Li, Ying; Feng, Yujie; Wang, Yaming; Jia, Dechang; Zhou, Yu

    2016-05-15

    Photoluminescent carbon nanodots (CNDs) have offered considerable potential to be used in biomedical and environmental fields including live cell imaging and heavy metal ion detection due to their superior quantum emission efficiencies, ability to be functionalized using a variety of chemistries and apparent absence of toxicity. However, to date, synthetic yield of CNDs derived from biomass via hydrothermal carbonization is quite low. We report here the synthesis of nitrogen-doped carbon nanodots (N-doped CNDs) derived from hydrosoluble chitosan via hydrothermal carbonization. The synthetic yield could reach 38.4% which is 2.2-320 times increase compared with that from other biomass reported so far. These N-doped CNDs exhibited a high quantum yield (31.8%) as a consequence of nitrogen incorporation coincident with multiple types of functional groups (C=O, O-H, COOH, and NH2). We further demonstrate applications of N-doped CNDs as probes for live cell multicolor imaging and heavy metal ion detection. The N-doped CNDs offered potential as mercury ion sensors with detection limit of 80nM. A smartphone application (APP) based on N-doped CNDs was developed for the first time providing a portable and low cost detection platform for detection of Hg(2+) and alert of heavy metal ions contamination. PMID:26686916

  10. 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

  11. Simultaneous Automatic Electrochemical Detection of Zinc, Cadmium, Copper and Lead Ions in Environmental Samples Using a Thin-Film Mercury Electrode and an Artificial Neural Network

    PubMed Central

    Kudr, Jiri; Nguyen, Hoai Viet; Gumulec, Jaromir; Nejdl, Lukas; Blazkova, Iva; Ruttkay-Nedecky, Branislav; Hynek, David; Kynicky, Jindrich; Adam, Vojtech; Kizek, Rene

    2015-01-01

    In this study a device for automatic electrochemical analysis was designed. A three electrodes detection system was attached to a positioning device, which enabled us to move the electrode system from one well to another of a microtitre plate. Disposable carbon tip electrodes were used for Cd(II), Cu(II) and Pb(II) ion quantification, while Zn(II) did not give signal in this electrode configuration. In order to detect all mentioned heavy metals simultaneously, thin-film mercury electrodes (TFME) were fabricated by electrodeposition of mercury on the surface of carbon tips. In comparison with bare electrodes the TMFEs had lower detection limits and better sensitivity. In addition to pure aqueous heavy metal solutions, the assay was also performed on mineralized rock samples, artificial blood plasma samples and samples of chicken embryo organs treated with cadmium. An artificial neural network was created to evaluate the concentrations of the mentioned heavy metals correctly in mixture samples and an excellent fit was observed (R2 = 0.9933). PMID:25558996

  12. Self-assembly of a metal-ion-bound monolayer of trigonal connectors on mercury: an electrochemical Langmuir trough.

    PubMed

    Varaksa, Natalia; Pospísil, Lubomír; Magnera, Thomas F; Michl, Josef

    2002-04-16

    The adsorption of the trigonal connector, 1,3,5-tris[10-(3-ethylthiopropyl)dimethylsilyl-1,10-dicarba-closo-decaboran-1-yl]benzene (1), from acetonitrile/0.1 M LiClO(4) on the surface of mercury at potentials ranging from +0.3 to -1.4 V (vs. aqueous Ag/AgCl/1 M LiCl) was examined by voltammetry, Langmuir isotherms at controlled potentials, and impedance measurements. No adsorption is observed at potentials more negative than approximately -0.85 V. Physisorption is seen between approximately -0.85 and 0 V. At positive potentials, adsorbate-assisted anodic dissolution of mercury occurs and an organized surface layer is formed. Although the mercury cations are reduced at -0.10 V, the surface layer remains metastable to potentials as negative as -0.85 V. Its surface areas per molecule and per redox center are compatible with a regular structure with the connectors 1 woven into a hexagonal network by RR'S-->Hg(2)(2+)<--SRR' or RR'S-->Hg(2+)<--SRR' bridges. The structure is simulated closely by geometry optimization in the semiempirical AM1 approximation. PMID:11959952

  13. Internal erosion rates of a 10-kW xenon ion thruster

    NASA Technical Reports Server (NTRS)

    Rawlin, Vincent K.

    1988-01-01

    A 30 cm diameter divergent magnetic field ion thruster, developed for mercury operation at 2.7 kW, was modified and operated with xenon propellant at a power level of 10 kW for 567 h to evaluate thruster performance and lifetime. The major differences between this thruster and its baseline configuration were elimination of the three mercury vaporizers, use of a main discharge cathode with a larger orifice, reduction in discharge baffle diameter, and use of an ion accelerating system with larger acceleration grid holes. Grid thickness measurement uncertainties, combined with estimates of the effects of reactive residual facility background gases gave a minimum screen grid lifetime of 7000 h. Discharge cathode orifice erosion rates were measured with three different cathodes with different initial orifice diameters. Three potential problems were identified during the wear test: the upstream side of the discharge baffle eroded at an unacceptable rate; two of the main cathode tubes experienced oxidation, deformation, and failure; and the accelerator grid impingement current was more than an order of magnitude higher than that of the baseline mercury thruster. The charge exchange ion eroison was not quantified in this test. There were no measurable changes in the accelerator grid thickness or the accelerator grid hole diameters.

  14. Internal erosion rates of a 10-kW xenon ion thruster

    NASA Technical Reports Server (NTRS)

    Rawlin, Vincent K.

    1988-01-01

    A 30 cm diameter divergent magnetic field ion thruster, developed for mercury operation at 2.7 kW, was modified and operated with xenon propellant at a power level of 10 kW for 567 h to evaluate thruster performance and lifetime. The major differences between this thruster and its baseline configuration were elimination of the three mercury vaporizers, use of a main discharge cathode with a larger orifice, reduction in discharge baffle diameter, and use of an ion accelerating system with larger acceleration grid holes. Grid thickness measurement uncertainties, combined with estimates of the effects of reactive residual facility background gases gave a minimum screen grid lifetime of 7000 h. Discharge cathode orifice erosion rates were measured with three different cathodes with different initial orifice diameters. Three potential problems were identified during the wear test: the upstream side of the discharge baffle eroded at an unacceptable rate; two of the main cathode tubes experienced oxidation, deformation, and failure; and the accelerator grid impingement current was more than an order of magnitude higher than that of the baseline mercury thruster. The charge exchange ion erosion was not quantified in this test. There were no measurable changes in the accelerator grid thickness or the accelerator grid hole diameters.

  15. Plasmon enhanced photoelectrochemical sensing of mercury (II) ions in human serum based on Au@Ag nanorods modified TiO2 nanosheets film.

    PubMed

    Zhang, Yong; Shoaib, Anwer; Li, Jiaojiao; Ji, Muwei; Liu, Jiajia; Xu, Meng; Tong, Bin; Zhang, Jiatao; Wei, Qin

    2016-05-15

    Taking advantages of the monodisperse TiO2 nanosheets (NSs) with high active crystal face exposure and the tunable localized surface plasmon resonance (LSPR) properties of Au@Ag nanorods (NRs), this study demonstrated that TiO2 NSs film with trace amount of Au@Ag NRs modification possess a strong enhancement of photocurrent response, which was remarkably inhibited with the addition of mercury (II) ions (Hg(2+)). Based on the selective decrease of photocurrent with the addition of Hg(2+), a simple photoelectrochemical (PEC) sensor has been assembled. The PEC sensor exhibits wide linear range (0.01-10nM), low detection limit (2.5pM), satisfying selectivity, reproducibility and acceptable stability for Hg(2+) detection. The feasibility of this method for practical application in human serum has been evaluated and the result was satisfactory. This PEC sensing method would provide a potential application for Hg(2+) detection in clinical diagnosis. PMID:26785311

  16. 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

  17. Effective removal of mercury(II) ions from chlor-alkali industrial wastewater using 2-mercaptobenzamide modified itaconic acid-grafted-magnetite nanocellulose composite.

    PubMed

    Anirudhan, T S; Shainy, F

    2015-10-15

    A novel adsorbent, 2-mercaptobenzamide modified itaconic acid-grafted-magnetite nanocellulose composite [P(MB-IA)-g-MNCC] was synthesized for adsorbing mercury(II) [Hg(II)] ions selectively from aqueous solutions. Fourier transforms infrared spectroscopy, X-ray diffraction, scanning electron microscopy and thermogravimetric studies were performed to characterize the adsorbent. The optimum pH for Hg(II) adsorption was found to be 8.0, and the adsorption attained equilibrium within 60 min. The kinetic data were found to follow pseudo-second-order which assumes the ion exchange followed by complexation mechanism. The temperature dependence indicates an exothermic process. The well agreement of equilibrium data with Freundlich adsorption model confirms the multilayer coverage of Hg(II) onto P(MB-IA)-g-MNCC. The maximum adsorption capacity was found to be 240.0 mg/g. Complete removal of Hg(II) from aqueous solution was possible with an adsorbent dosage of 2.0 g/L. Spent adsorbent was effectively degenerated with 0.1M HCl. The present investigation shows that P(MB-IA)g-MNCC is a promising adsorbent for the removal and recovery of Hg(II) ions from aqueous solutions. PMID:26086434

  18. Planet Mercury Conference, Tucson, AZ, Aug. 6-9, 1986, Proceedings

    SciTech Connect

    Not Available

    1987-09-01

    The present conference discusses the mass, gravity field, and ephemeris of the planet Mercury, the vulcanoid hypothesis for the chronology of Mercury's geological and geophysical evolution, the Mercurian crater-filling classes that constrain the intercrater plains material emplacement process, and the wavelength and longitude dependence of Mercury polarization. Also discussed are an analysis of the Mariner 10 color radio map of Mercury, Mercury's magnetosphere, exosphere, and surface, the dynamics of electrons and heavy ions in the Mercury magnetosphere, electron measurements and substorm time scales in the Mercury and earth magnetospheres, Mercury's sodium variations with solar radiation pressure, and appulses and occultations of SAO stars by Mercury in the 1987-1995 period.

  19. In situ formation of p-n junction: a novel principle for photoelectrochemical sensor and its application for mercury(II) ion detection.

    PubMed

    Wang, Guang-Li; Liu, Kang-Li; Dong, Yu-Ming; Li, Zai-Jun; Zhang, Chi

    2014-05-27

    The discovery and development of photoelectrochemical sensors with novel principles are of great significance to realize sensitive and low-cost detection. In this paper, a new photoelectrochemial sensor based on the in situ formation of p-n junction was designed and used for the accurate determination of mercury(II) ions. Cysteine-capped ZnS quantum dots (QDs) was assembled on the surface of indium tin oxide (ITO) electrode based on the electrostatic interaction between Poly(diallyldimethylammonium chloride) (PDDA) and Cys-capped ZnS QDs. The in situ formation of HgS, a p-type semiconductor, on the surface of ZnS facilitated the charge carrier transport and promoted electron-hole separation, triggered an obviously enhanced anodic photocurrent of Cys-capped ZnS QDs. The formation of p-n junction was confirmed by P-N conductive type discriminator measurements and current-voltage (I-V) curves. The photoelectrochemical method was used for the sensing of trace mercuric (II) ions with a linear concentration of 0.01 to 10.0 µM and a detection limit of 4.6×10(-9)mol/L. It is expected that the present study can serve as a foundation to the application of p-n heterojunction to photoelectrochemical sensors and it might be easily extended to more exciting sensing systems by photoelectrochemistry. PMID:24832992

  20. Process for removing mercury from aqueous solutions

    DOEpatents

    Googin, John M.; Napier, John M.; Makarewicz, Mark A.; Meredith, Paul F.

    1986-01-01

    A process for removing mercury from water to a level not greater than two parts per billion wherein an anion exchange material that is insoluble in water is contacted first with a sulfide containing compound and second with a compound containing a bivalent metal ion forming an insoluble metal sulfide. To this treated exchange material is contacted water containing mercury. The water containing not more than two parts per billion of mercury is separated from the exchange material.

  1. Process for removing mercury from aqueous solutions

    DOEpatents

    Googin, J.M.; Napier, J.M.; Makarewicz, M.A.; Meredith, P.F.

    1985-03-04

    A process for removing mercury from water to a level not greater than two parts per billion wherein an anion exchange material that is insoluble in water is contacted first with a sulfide containing compound and second with a compound containing a bivalent metal ion forming an insoluble metal sulfide. To this treated exchange material is contacted water containing mercury. The water containing not more than two parts per billion of mercury is separated from the exchange material.

  2. Rhodamine based dual probes for selective detection of mercury and fluoride ions in water using two mutually independent sensing pathways.

    PubMed

    Kumari, Namita; Dey, Nilanjan; Bhattacharya, Santanu

    2014-05-21

    New rhodamine based molecules have been designed as dual probes for the ppb-level selective detection of Hg(2+) and F(-) ions in aqueous medium at physiological pH 7.4. The probes have been designed in such a way to utilize both the properties of the metal ion induced 'turn-on' detection mechanism of the spirolactam ring opening of the rhodamine moiety and the reaction based cleavage of the O-silyl bond in presence of the fluoride ion. The probes have been synthesized conveniently by coupling rhodamine hydrazone with O-silyl protected mono- and di-hydroxybenzaldehydes. Both the probes showed a 'turn-on' detection of the fluoride ion due to the cleavage of the O-silyl bond upon treatment with the added F(-) ion. However, the probes showed selective 'turn-on' detection of Hg(2+) ion by opening of the spirolactam ring. The two detection mechanisms worked in isolation and hence the corresponding spectral responses appeared completely independent of each other. The presence of Hg(2+) in solution induced generation of an intense pink color with bright green fluorescence emission. In contrast a deep yellow color with yellow fluorescence was observed upon addition of the fluoride ion to the probe solution. Two different mechanisms of interactions have been proposed on the basis of (1)H-NMR, IR and mass spectrometric studies. Thus, using a single probe the selective sensing of two different ions could be achieved in aqueous medium well below their permitted limit of detection. PMID:24669370

  3. Passivation of carbon steel through mercury implantation

    NASA Technical Reports Server (NTRS)

    Wilbur, P. J.; Robinson, R. S.

    1981-01-01

    An experiment, in which carbon steel samples were implanted with mercury ions from a broad beam ion source and their corrosion characteristics in air were evaluated, is described. Mercury doses of a few mA min/square cm at energies of a few hundred electron volts are shown to effect significant improvements in the corrosion resistance of the treated surfaces. In a warm moist environment the onset of rusting was extended from 15 min. for an untreated sample to approximately 30 hrs. for one implanted at a dose of 33 mA min/square cm with 1000 eV mercury ions.

  4. Kinetics of mercury ions removal from synthetic aqueous solutions using by novel magnetic p(GMA-MMA-EGDMA) beads.

    PubMed

    Bayramoğlu, Gülay; Arica, M Yakup

    2007-06-01

    Poly(glycidylmethacrylate-methylmethacrylate), p(GMA-MMA-EGDMA), magnetic beads were prepared via suspension polymerization in the presence of ferric ions. The epoxy groups of the beads were converted into amino groups via ring opening reaction of the ammonia and, the aminated magnetic beads were used for the removal of Hg(II) ions from aqueous solution in a batch experiment and in a magnetically stabilized fluidized bed reactor (MFB). The magnetic p(GMA-MMA-EGDMA) beads were characterized with scanning electron microscope (SEM), FT-IR and ESR spectrophotometers. The optimum removal of Hg(II) ions was observed at pH 5.5. The maximum adsorption capacity of Hg(II) ions by using the magnetic beads was 124.8+/-2.1 mgg(-1) beads. In the continuous MFB reactor, Hg(II) ions adsorption capacity of the magnetic beads decreased with an increase in the flow-rate. The maximum adsorption capacity of the magnetic beads in the MFB reactor was 139.4+/-1.4 mgg(-1). The results indicate that the magnetic beads are promising for use in MFB for removal of Hg(II) ions from aqueous solution and/or waste water treatment. PMID:17118552

  5. Mercury's sodium exosphere

    NASA Astrophysics Data System (ADS)

    Schmidt, Carl A.

    In this dissertation I examine the properties and origins of the most energetic component of Mercury's atmosphere and how it couples to the planet's magnetosphere and space environment. Mercury' s atmosphere consists of particles liberated from its surface that follow ballistic, collisionless trajectories under the influence of gravity and solar radiation pressure. This tenuous atmosphere can be classified as an exosphere where the exobase boundary is the planet's surface. To explain how this exosphere is sustained, a number of theories have been presented: (1) thermal evaporation from the hot surface; (2) photo-desorption of surface materials by UV solar radiation; (3) sputtering by plasma surface interactions; and (4) vaporization of the surface by micro-meteorite impacts. Using a 3-dimensional numerical model, I determine the role each source has in populating the exosphere. New observations of Mercury's escaping atmosphere are presented using novel imaging techniques in which sodium acts as a tracer to identify atmospheric sources. I discuss the implications of these measurements for our understanding of the physical processes at work in the exosphere, and provide a foundation for modeling such processes. For the first time, this work quantifies the variability in the loss of Mercury's sodium as a seasonal effect. My observations show that atmospheric escape can, at times, exceed 1024 Na atoms/s, nearly twice the highest rate previously reported. By forward modeling Mercury' s atmospheric escape, I place new constraints on the source properties and eliminate the prevailing theory that the escaping tail is sputtered from the surface by solar wind ions. The MESSENGER spacecraft has recently discovered that sodium is distributed unevenly over the surface and that the magnetosphere is offset from the planet's center. Using the first model to include these effects, I demonstrate the magnetosphere's influence upon exospheric sources by simulating asymmetries observed

  6. Industrial ion source technology

    NASA Technical Reports Server (NTRS)

    Kaufman, H. R.

    1976-01-01

    A 30 cm electron bombardment ion source was designed and fabricated for micromachining and sputtering applications. This source has a multipole magnetic field that employs permanent magnets between permeable pole pieces. An average ion current density of 1 ma/sq cm with 500 eV argon ions was selected as a design operating condition. The ion beam at this operating condition was uniform and well collimated, with an average variation of plus or minus 5 percent over the center 20 cm of the beam at distances up to 30 cm from the ion source. A variety of sputtering applications were undertaken with a small 10 cm ion source to better understand the ion source requirements in these applications. The results of these experimental studies are also included.

  7. XAS study of mercury(II) ions trapped in mercaptan-functionalized mesostructured silicate with a wormhole framework structure.

    PubMed

    Chen, Chia-Chen; McKimmy, Emily J; Pinnavaia, Thomas J; Hayes, Kim F

    2004-09-15

    Directly assembled wormhole mesostructures with high level functionalized mercaptan (MP-HMS) have been shown to be effective mercury(II) (Hg2+) trapping agents. Sorption of Hg2+ onto MP-HMS was investigated using X-ray absorption spectroscopy (XAS) to identify the structural coordination of the adsorbed Hg. Samples with different fractions of mercaptan functionalized groups (i.e., x = 0.1 and 0.5) with various Hg/S molar ratios ranging from 0.05 to 1.4 were investigated. XAS analysis indicates that adsorbed Hg first coordination shell is best fitted with an Hg-O path and an Hg-S path. The Hg-S atomic distance (R(Hg-S)) remained relatively constant while the Hg-S coordination numbers (CN) decreased as Hg/S loading increased. For the Hg-O path, both the CN and the R(Hg-O) increased with increasing Hg loading. XAS results suggest that at low Hg loadings, adsorbed Hg2+ forms mostly monodentate sulfur complexes (-S-Hg-OH) with the sulfur functional groups on the MP-HMS surfaces. At high Hg loadings, the Hg coordination environment is consistent with the formation of a double-layer structure of Hg attached to sulfur binding sites (-S-Hg-O-Hg-OH). PMID:15487784

  8. Evaluation of the characteristics of a field emission cathode for use in a Mercury ion trap frequency standard

    NASA Technical Reports Server (NTRS)

    Christman, J. M.

    1988-01-01

    The performance is reported of a field emission array characterized for the purpose of replacing the filament in a trapped ion frequency standard. This dark electron emitter eliminates the need for the interference filter currently used in the trapped ion standard. While reducing the filament's unwanted light, this filter causes a significant reduction in the signal. The magnetic field associated with the filament is also eliminated, thus potentially improving the present stability of the trapped ion standard. The operation of the filament in the present system is described, as well as the associated concerns. The cathode considered for the filament's replacement is then described along with the experimental system. Experimental results, observations, and conclusions are presented.

  9. Investigation into mercury bound to biothiols: structural identification using ESI–ion-trap MS and introduction of a method for their HPLC separation with simultaneous detection by ICP-MS and ESI-MS

    PubMed Central

    Milne, Bruce F.; Mestrot, Adrien; Meharg, Andrew A.; Feldmann, Jörg

    2008-01-01

    Mercury in plants or animal tissue is supposed to occur in the form of complexes formed with biologically relevant thiols (biothiols), rather than as free cation. We describe a technique for the separation and molecular identification of mercury and methylmercury complexes derived from their reactions with cysteine (Cys) and glutathione (GS): Hg(Cys)2, Hg(GS)2, MeHgCys, MeHgGS. Complexes were characterised by electrospray mass spectrometry (MS) equipped with an ion trap and the fragmentation pattern of MeHgCys was explained by using MP2 and B3LYP calculations, showing the importance of mercury–amine interactions in the gas phase. Chromatographic baseline separation was performed within 10 min with formic acid as the mobile phase on a reversed-phase column. Detection was done by online simultaneous coupling of ES-MS and inductively coupled plasma MS. When the mercury complexes were spiked in real samples (plant extracts), no perturbation of the separation and detection conditions was observed, suggesting that this method is capable of detecting mercury biothiol complexes in plants. Figure Separation and structural identification of Hg and MeHg biothiols PMID:18297471

  10. Reference Atmosphere for Mercury

    NASA Technical Reports Server (NTRS)

    Killen, Rosemary M.

    2002-01-01

    The objectives of this three year proposal are: (1) to calculate the likely diffusive flux of Ar and He from the interior of Mercury for representative crustal compositions; (2) compute a reasonable estimate of the fractional escape flux of photoions for the likely range of field conditions; and (3) to calculate the capture rate of solar wind ions into the atmosphere. The morphology of the magnetosphere in response to the solar wind and the IMF is the crucial boundary condition for the flux of ions to the surface. We have tackled problem (1) using a multipath diffusion code, and problems (2) and (3) using a combination of MHD and kinetic plasma dynamics.

  11. A highly selective and simple fluorescent sensor for mercury (II) ion detection based on cysteamine-capped CdTe quantum dots synthesized by the reflux method.

    PubMed

    Ding, Xiaojie; Qu, Lingbo; Yang, Ran; Zhou, Yuchen; Li, Jianjun

    2015-06-01

    Cysteamine (CA)-capped CdTe quantum dots (QDs) (CA-CdTe QDs) were prepared by the reflux method and utilized as an efficient nano-sized fluorescent sensor to detect mercury (II) ions (Hg(2+) ). Under optimum conditions, the fluorescence quenching effect of CA-CdTe QDs was linear at Hg(2+) concentrations in the range of 6.0-450 nmol/L. The detection limit was calculated to be 4.0 nmol/L according to the 3σ IUPAC criteria. The influence of 10-fold Pb(2+) , Cu(2+) and Ag(+) on the determination of Hg(2+) was < 7% (superior to other reports based on crude QDs). Furthermore, the detection sensitivity and selectivity were much improved relative to a sensor based on the CA-CdTe QDs probe, which was prepared using a one-pot synthetic method. This CA-CdTe QDs sensor system represents a new feasibility to improve the detection performance of a QDs sensor by changing the synthesis method. PMID:25263990

  12. Label-free SERS study of galvanic replacement reaction on silver nanorod surface and its application to detect trace mercury ion

    PubMed Central

    Wang, Yaohui; Wen, Guiqing; Ye, Lingling; Liang, Aihui; Jiang, Zhiliang

    2016-01-01

    It is significant to explore a rapid and highly sensitive galvanic replacement reaction (GRR) surface enhanced Raman scattering (SERS) method for detection of trace mercury ions. This article was reported a new GRR SERS analytical platform for detecting Hg(II) with label-free molecular probe Victoria blue B (VBB). In HAc-NaCl-silver nanorod (AgNR) substrate, the molecular probe VBB exhibited a strong SERS peak at 1609 cm−1. Upon addition of Hg(II), the GRR occurred between the AgNR and Hg(II), and formed a weak SERS activity of Hg2Cl2 that deposited on the AgNR surfaces to decrease the SERS intensity at 1609 cm−1. The decreased SERS intensity was linear to Hg(II) concentration in the range of 1.25–125 nmol/L, with a detection limit of 0.2 nmol/L. The GRR was studied by SERS, transmission electron microscopy and other techniques, and the GRR mechanism was discussed. PMID:26792071

  13. 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.

  14. The Plasma Environment at Mercury

    NASA Technical Reports Server (NTRS)

    Raines, James M.; Gershman, Daniel J.; Zurbuchen, Thomas H.; Gloeckler, George; Slavin, James A.; Anderson, Brian J.; Korth, Haje; Krimigis, Stamatios M.; Killen, Rosemary M.; Sarantos, Menalos; Sprague, Anne L.; McNutt, Ralph L., Jr.

    2011-01-01

    Mercury is the least explored terrestrial planet, and the one subjected to the highest flux of solar radiation in the heliosphere. Its highly dynamic, miniature magnetosphere contains ions from the exosphere and solar wind, and at times may allow solar wind ions to directly impact the planet's surface. Together these features create a plasma environment that shares many features with, but is nonetheless very different from, that of Earth. The first in situ measurements of plasma ions in the Mercury space environment were made only recently, by the Fast Imaging Plasma Spectrometer (FIPS) during the MESSENGER spacecraft's three flybys of the planet in 2008-2009 as the probe was en route to insertion into orbit about Mercury earlier this year. Here. we present analysis of flyby and early orbital mission data with novel techniques that address the particular challenges inherent in these measurements. First. spacecraft structures and sensor orientation limit the FIPS field of view and allow only partial sampling of velocity distribution functions. We use a software model of FIPS sampling in velocity space to explore these effects and recover bulk parameters under certain assumptions. Second, the low densities found in the Mercury magnetosphere result in a relatively low signal-to-noise ratio for many ions. To address this issue, we apply a kernel density spread function to guide removal of background counts according to a background-signature probability map. We then assign individual counts to particular ion species with a time-of-flight forward model, taking into account energy losses in the carbon foil and other physical behavior of ions within the instrument. Using these methods, we have derived bulk plasma properties and heavy ion composition and evaluated them in the context of the Mercury magnetosphere.

  15. A 15,000-hour cyclic endurance test of an 8-centimeter-diameter electron bombardment mercury ion thruster

    NASA Technical Reports Server (NTRS)

    Nakanishi, S.

    1976-01-01

    A laboratory model 8 cm thruster with improvements to minimize ion chamber erosion and peeling of sputtered metal was subjected to a cyclic endurance test for 15,040 hours and 460 restarts. A charted history of several thruster operating variables and off-normal events are shown in 600-hour segments at three points in the test. The transient behavior of these variables during a typical start-stop cycle is presented. Finding of the post-test inspection confirmed most of the expected results. Charge exchange ions caused normal accelerator grid erosion. The workability of the various design features was substantiated, and attainable improvements in propellant utilization efficiency should significantly reduce accelerator erosion.

  16. Rapid mercury assays

    SciTech Connect

    Szurdoki, S.; Kido, H.; Hammock, B.D.

    1996-10-01

    We have developed rapid assays with the potential of detecting mercury in environmental samples. our methods combine the simple ELISA-format with the selective, high affinity complexation of mercuric ions by sulfur-containing ligands. The first assay is based on a sandwich chelate formed by a protein-bound ligand immobilized on the wells of a microliter plate, mercuric ion of the analyzed sample, and another ligand conjugated to a reporter enzyme. The second assay involves competition between mercuric ions and an organomercury-conjugate to bind to a chelating conjugate. Several sulfur containing chelators (e.g., dithiocarbamates) and organomercurials linked to macromolecular carriers have been investigated in these assay formats. The assays detect mercuric ions in ppb/high ppt concentrations with high selectivity.

  17. DNA derived fluorescent bio-dots for sensitive detection of mercury and silver ions in aqueous solution

    NASA Astrophysics Data System (ADS)

    Song, Ting; Zhu, Xuefeng; Zhou, Shenghai; Yang, Guang; Gan, Wei; Yuan, Qunhui

    2015-08-01

    Inspired by the high affinity between heavy metal ions and bio-molecules as well as the low toxicity of carbon-based quantum dots, we demonstrated the first application of a DNA derived carbonaceous quantum dots, namely bio-dots, in metal ion sensing. The present DNA-derived bio-dots contain graphitic carbon layers with 0.242 nm lattice fringes, exhibit excellent fluorescence property and can be obtained via a facile hydrothermal preparation procedure. Hg(II) and Ag(I) are prone to be captured by the bio-dots due to the existence of residual thymine (T) and cytosine (C) groups, resulting in a quenched fluorescence while other heavy metal ions would cause negligible changes on the fluorescent signals of the bio-dots. The bio-dots could be used as highly selective toxic-free biosensors, with two detecting linear ranges of 0-0.5 μM and 0.5-6 μM for Hg(II) and one linear range of 0-10 μM for Ag(I). The detection limits (at a signal-to-noise ratio of 3) were estimated to be 48 nM for Hg(II) and 0.31 μM for Ag(I), respectively. The detection of Hg(II) and Ag(I) could also be realized in the real water sample analyses, with satisfying recoveries ranging from 87% to 100%.

  18. Carbon nanoparticle for highly sensitive and selective fluorescent detection of mercury(II) ion in aqueous solution.

    PubMed

    Li, Hailong; Zhai, Junfeng; Tian, Jingqi; Luo, Yonglan; Sun, Xuping

    2011-08-15

    In this article, carbon nanoparticles (CNPs) were used as a novel fluorescent sensing platform for highly sensitive and selective Hg(2+) detection. To the best of our knowledge, this is the first example of CNPs obtained from candle soot used in this type of sensor. The general concept used in this approach is based on that adsorption of the fluorescently labeled single-stranded DNA (ssDNA) probe by CNP via π-π stacking interactions between DNA bases and CNP leads to substantial dye fluorescence quenching; however, in the presence of Hg(2+), T-Hg(2+)-T induced hairpin structure does not adsorb on CNP and thus retains the dye fluorescence. A detection limit as low as 10nM was achieved. The present CNP-based biosensor for Hg(2+) detection exhibits remarkable specificity against other possible metal ions. Furthermore, superior selectivity performance was observed when Hg(2+) detection was carried out in the presence of a large amount of other interference ions. Finally, in order to evaluate its potential practical application, Hg(2+) detection was conducted with the use of lake water other than pure buffer and it is believed that it holds great promise for real sample analysis upon further development. PMID:21719271

  19. BSA-stabilized Pt nanozyme for peroxidase mimetics and its application on colorimetric detection of mercury(II) ions.

    PubMed

    Li, Wei; Chen, Bin; Zhang, Haixiang; Sun, Yanhua; Wang, Jun; Zhang, Jinli; Fu, Yan

    2015-04-15

    Bovine serum albumin (BSA) is chosen as the nucleation templates to synthesize Pt-based peroxidase nanomimetics with the average diameter of 2.0nm. The efficient Pt nanozymes consist of 57% Pt(0) and 43% Pt(2+), which possess highly peroxidase-like activity with the Km values of 0.119mM and 41.8mM toward 3,3',5,5'-tetramethylbenzidine (TMB) and hydrogen peroxide (H2O2), respectively. Interestingly, Hg(2+) is able to down-regulate the enzymatic activity of Pt nanoparticles, mainly through the interactions between Hg(2+) and Pt(0). It is the first report to explore a colorimetric Hg(2+) sensing system on the basis of peroxidase mimicking activities of Pt nanoparticles. One of our most intriguing results is that BSA-stabilized Pt nanozymes demonstrate the ability to sense Hg(2+) ions in aqueous solution without significant interference from other metal ions. The Hg(2+) detection limit of 7.2nM is achieved with a linear response range of 0-120nM, and the developed sensing system is potentially applicable for quantitative determination of Hg(2+) in drinking water. PMID:25437360

  20. Label-free fluorescence detection of mercury ions based on the regulation of the Ag autocatalytic reaction.

    PubMed

    Dai, Haichao; Ni, Pengjuan; Sun, Yujing; Hu, Jingting; Jiang, Shu; Wang, Yilin; Li, Zhuang

    2015-05-21

    In this work, a novel facile nanoparticle autocatalytic sensor based on the inhibition of the Ag autocatalytic reaction for the determination of Hg(2+) was developed. o-Phenylenediamine (OPD) tended to be oxidized into 2,3-diaminophenazine (OPDox) by silver ions (Ag(+)) followed by the formation of silver nanoparticles (AgNPs). Employed as a catalyst, the thus-formed AgNPs would further promote the reaction between OPD and Ag(+). When Hg(2+) was introduced, Hg(2+) adsorbed on the surface of the AgNPs, thus inhibiting the oxidation process mentioned above and achieving weakened fluorescence intensity. A linear relationship between fluorescence intensity and Hg(2+) concentration (within the range from 10 nM to 2500 nM) was obtained and the detection limit reached as low as 8.2 nM. The proposed method was also applied for the determination of Hg(2+) in real water samples with satisfactory results. The protocol showed excellent advantages of sensitivity and selectivity for Hg(2+) over various metal ions and anions. Meanwhile, this method was simpler and more cost-effective compared with many reported nanomaterial- and DNA-based approaches. Furthermore, an "INHIBIT" logic gate based on the Ag(+)-Hg(2+)-OPD system has also been designed. PMID:25859575

  1. "Fastening" porphyrin in highly cross-linked polyphosphazene hybrid nanoparticles: powerful red fluorescent probe for detecting mercury ion.

    PubMed

    Hu, Ying; Meng, Lingjie; Lu, Qinghua

    2014-04-22

    It is a significant issue to overcome the concentration-quenching effect of the small fluorescent probes and maintain the high fluorescent efficiency at high concentration for sensitive and selective fluorescent mark or detection. We developed a new strategy to "isolate" and "fasten" porphyrin moieties in a highly cross-linked poly(tetraphenylporphyrin-co-cyclotriphosphazene) (TPP-PZS) by the polycondensation of hexachlorocyclotriphosphazene (HCCP) and 5,10,15,20-tetrakis(4-hydroxyphenyl)porphyrin (TPP-(OH)4) in a suitable solvent. The resulting TPP-PZS particles were characterized with transmission electron microscopy (TEM), scanning electron microscopy (SEM), Fourier transform infrared (FTIR), (31)P nuclear magnetic resonance (NMR), and ultraviolet and visible (UV-vis) absorption spectra. Remarkably, TPP-PZS particles obtained in acetone emitted a bright red fluorescence both in powder state and in solution because the aggregation of porphyrin moieties in "H-type" (face-to-face) and "J-type" (edge-to-edge) was effectively blocked. The fluorescent TPP-PZS particles also showed superior resistance to photobleaching, and had a high sensitivity and selectivity for the detection of Hg(2+) ions. The TPP-PZS particles were therefore used as an ideal material for preparing test strips to quickly detect/monitor the Hg(2+) ions in a facile way. PMID:24678932

  2. 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

  3. A sensitive and selective sensing platform based on CdTe QDs in the presence of l-cysteine for detection of silver, mercury and copper ions in water and various drinks.

    PubMed

    Gong, Tingting; Liu, Junfeng; Liu, Xinxin; Liu, Jie; Xiang, Jinkun; Wu, Yiwei

    2016-12-15

    Water soluble CdTe quantum dots (QDs) have been prepared simply by one-pot method using potassium tellurite as stable tellurium source and thioglycolic acid (TGA) as stabilizer. The fluorescence of CdTe QDs can be improved 1.3-fold in the presence of l-cysteine (Cys), however, highly efficiently quenched in the presence of silver or mercury or copper ions. A sensitive and selective sensing platform for analysis of silver, mercury and copper ions has been simply established based on CdTe QDs in the presence of l-cysteine. Under the optimum conditions, excellent linear relationships exist between the quenching degree of the sensing platform and the concentrations of Ag(+), Hg(2+) and Cu(2+) ranging from 0.5 to 40ngmL(-1). By using masking agents of sodium diethyldithiocarbamate (DDTC) for Ag(+) and Cu(2+), NH4OH for Ag(+) and Hg(2+) and 1-(2-Pyridylazo)-2-naphthol (PAN) for Hg(2+) and Cu(2+), Hg(2+), Cu(2+) and Ag(+) can be exclusively detected in coexistence with other two ions, and the detection limits (3σ) were 0.65, 0.063 and 0.088ngmL(-1) for Ag(+), Hg(2+) and Cu(2+), respectively. This effective sensing platform has been used to detection of Ag(+), Hg(2+) and Cu(2+) in water and various drinks with satisfactory results. PMID:27451185

  4. 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

  5. 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.…

  6. 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

  7. Gold nanoparticle-based colorimetric and "turn-on" fluorescent probe for mercury(II) ions in aqueous solution.

    PubMed

    Wang, Hao; Wang, Yongxiang; Jin, Jianyu; Yang, Ronghua

    2008-12-01

    An approach for visual and fluorescent sensing of Hg2+ in aqueous solution is presented. This method is based on the Hg(2+)-induced conformational change of a thymine (T)-rich single-stranded DNA (ssDNA) and the difference in electrostatic affinity between ssDNA and double-stranded (dsDNA) with gold nanoparticles. The dye-tagged ssDNA containing T-T mismatched sequences was chosen as Hg2+ acceptor. At high ionic strength, introduction of the ssDNA to a colloidal solution of the aggregates of gold nanoparticles results in color change, from blue-gray to red of the solution, and the fluorescence quenching of the dye. Binding of Hg2+ with the ssDNA forms the double-stranded structure. This formation of dsDNA reduces the capability to stabilize bare nanoparticles against salt-induced aggregation, remaining a blue-gray in the color of the solution, but fluorescence signal enhancement compared with that without Hg2+. With the optimum conditions described, the system exhibits a dynamic response range for Hg2+ from 9.6 x 10(-8) to 6.4 x 10(-6) M with a detection limit of 4.0 x 10(-8) M. Both the color and fluorescence changes of the system are extremely specific for Hg2+ even in the presence of high concentrations of other heavy and transition metal ions, which meet the selective requirements for biomedical and environmental application. The combined data from transmission electron microscopy, fluorescence anisotropy measurements, and dialysis experiments indicate that both the color and the fluorescence emission changes of the DNA-functioned gold nanoparticles generated by Hg2+ are the results of the metal-induced formation of dsDNA and subsequent formation of nanoparticle aggregates. PMID:19551976

  8. Fluorescent sensor for mercury

    DOEpatents

    Wang, Zidong; Lee, Jung Heon; Lu, Yi

    2011-11-22

    The present invention provides a sensor for detecting mercury, comprising: a first polynucleotide, comprising a first region, and a second region, a second polynucleotide, a third polynucleotide, a fluorophore, and a quencher, wherein the third polynucleotide is optionally linked to the second region; the fluorophore is linked to the first polynucleotide and the quencher is linked to the second polynucleotide, or the fluorophore is linked to the second polynucleotide and the quencher is linked to the first polynucleotide; the first region and the second region hybridize to the second polynucleotide; and the second region binds to the third polynucleotide in the presence of Hg.sup.2+ ions.

  9. 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...

  10. MERCURY IN TREE RINGS

    EPA Science Inventory

    Contamination caused by release of mercury into the environment is a growing concern. This release occurs due to a variety of anthropogenic activities and natural sources. After release, mercury undergoes complicated chemical transformations. The inorganic forms of mercury releas...

  11. Conceptual design for a Mercury relativity satellite

    NASA Technical Reports Server (NTRS)

    Bender, P. L.; Ashby, N.; Wahr, J. M.; Vincent, M. A.

    1989-01-01

    It was shown earlier that 1 x 10 to the -14th Doppler data and 3 cm accuracy range measurements to a small Mercury Relativity Satellite in a polar orbit with four-hour period can give high-accuracy tests of gravitational theory. A particular conceptual design has been developed for such a satellite, which would take less than 10 percent of the approach mass for a possible future Mercury Orbiter Mission. The spacecraft is similar to the Pioneer Venus Orbiter, but scaled down by about a factor four in linear dimensions. A despun antenna 30 cm in diameter is used for tracking. The transmitted power is roughly 0.2 watts at K-band and 0.5 watts at X-band. The orbit parameters for individual eight-hour arcs and the gravity field of Mercury through degree and order 10 are determined mainly from the Doppler data. A 50 MHz K-band sidetone system provides the basic ranging accuracy. The spacecraft mass is 50 kg or less.

  12. A label free aptamer-based LPG sensor for detection of mercury in aquatic solutions

    NASA Astrophysics Data System (ADS)

    Nikbakht, Hamed; Latifi, Hamid; Ziaee, Farzaneh

    2015-09-01

    We demonstrate a label free fiber optic sensor for detection of mercury ions in aquatic solutions. This sensor utilizes aptamers as bio-recognition element which traps mercury ions and cause a refractive index change in the vicinity of the sensor. Refractive index variations lead to a change in the transmission spectrum that can be used to calculate the concentration of mercury ions in that solution. The concentration of 1 nM mercury ions was detected which is below the specific amount determined by the US environmental protection agency as the maximum authorized contaminant level of Hg2+ ions in drinking water.

  13. Magnetosphere, exosphere, and surface of Mercury

    NASA Astrophysics Data System (ADS)

    Cheng, A. F.; Johnson, R. E.; Krimigis, S. M.; Lanzerotti, L. J.

    1987-09-01

    The discovery of an atomic sodium exosphere at Mercury raises the question of whether Mercury, like Io at Jupiter, can maintain a heavy ion magnetosphere. The authors suggest that it does, and that heavy ions (mainly Na+) from the exosphere are typically accelerated to keV energies and make important or dominant contributions to the mass (≡300 g sec-1) and energy (≡3×109W) budgets of the magnetosphere. The sodium supply to the exosphere is largely from within Mercury itself, with external sources like meteoroid infall and the solar wind being relatively unimportant. Therefore Mercury is in the process of losing its semivolatiles. Photosputtering dominates charged particle sputtering and can maintain an adequate rate of Na ejection from the surface.

  14. Segmented ion thruster

    NASA Technical Reports Server (NTRS)

    Brophy, John R. (Inventor)

    1993-01-01

    Apparatus and methods for large-area, high-power ion engines comprise dividing a single engine into a combination of smaller discharge chambers (or segments) configured to operate as a single large-area engine. This segmented ion thruster (SIT) approach enables the development of 100-kW class argon ion engines for operation at a specific impulse of 10,000 s. A combination of six 30-cm diameter ion chambers operating as a single engine can process over 100 kW. Such a segmented ion engine can be operated from a single power processor unit.

  15. Novel regenerable sorbent for mercury capture from flue gases of coal-fired power plant

    SciTech Connect

    Yan Liu; David J.A. Kelly; Hongqun Yang; Christopher C.H. Lin; Steve M. Kuznicki; Zhenghe Xu

    2008-08-15

    A natural chabazite-based silver nanocomposite (AgMC) was synthesized to capture mercury from flue gases of coal-fired power plants. Silver nanoparticles were engineered on zeolite through ion-exchange of sodium ions with silver ions, followed by thermal annealing. Mercury sorption test using AgMC was performed at various temperatures by exposing it to either pulse injection of mercury or continuous mercury flow. A complete capture of mercury by AgMC was achieved up to a capture temperature of 250{sup o}C. Nano silver particles were shown to be the main active component for mercury capture by amalgamation mechanism. Compared with activated carbon-based sorbents, the sorbent prepared in this study showed a much higher mercury capture capacity and upper temperature limit for mercury capture. More importantly, the mercury captured by the spent AgMC could be easily released for safe disposal and the sorbent regenerated by simple heating at 400{sup o}C. Mercury capture tests performed in real flue gas environment showed a much higher level of mercury capture by AgMC than by other potential mercury sorbents tested. In our mercury capture tests, the AgMC exposed to real flue gases showed an increased mercury capture efficiency than the fresh AgMC. 38 refs., 6 figs.

  16. Aqueous mercury adsorption by activated carbons.

    PubMed

    Hadi, Pejman; To, Ming-Ho; Hui, Chi-Wai; Lin, Carol Sze Ki; McKay, Gordon

    2015-04-15

    Due to serious public health threats resulting from mercury pollution and its rapid distribution in our food chain through the contamination of water bodies, stringent regulations have been enacted on mercury-laden wastewater discharge. Activated carbons have been widely used in the removal of mercuric ions from aqueous effluents. The surface and textural characteristics of activated carbons are the two decisive factors in their efficiency in mercury removal from wastewater. Herein, the structural properties and binding affinity of mercuric ions from effluents have been presented. Also, specific attention has been directed to the effect of sulfur-containing functional moieties on enhancing the mercury adsorption. It has been demonstrated that surface area, pore size, pore size distribution and surface functional groups should collectively be taken into consideration in designing the optimal mercury removal process. Moreover, the mercury adsorption mechanism has been addressed using equilibrium adsorption isotherm, thermodynamic and kinetic studies. Further recommendations have been proposed with the aim of increasing the mercury removal efficiency using carbon activation processes with lower energy input, while achieving similar or even higher efficiencies. PMID:25644627

  17. 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

  18. One-pot green synthesis of high quantum yield oxygen-doped, nitrogen-rich, photoluminescent polymer carbon nanoribbons as an effective fluorescent sensing platform for sensitive and selective detection of silver(I) and mercury(II) ions.

    PubMed

    Wang, Zhong-Xia; Ding, Shou-Nian

    2014-08-01

    This work reports on a facile, economical, and green preparative strategy toward water-soluble, fluorescent oxygen-doped, nitrogen-rich, photoluminescent polymer carbon nanoribbons (ONPCRs) with a quantum yield of approximately 25.61% by the hydrothermal process using uric acid as a carbon-nitrogen source for the first time. The as-prepared fluorescent ONPCRs showed paddy leaf-like structure with 80-160 nm length and highly efficient fluorescent quenching ability in the presence of mercury(II) (Hg(2+)) or silver (Ag(+)) ions due to the formed nonfluorescent metal complexes via robust Hg(2+)-O or Ag(+)-N interaction with the O and N of fluorescent ONPCRs, which allowed the analysis of Hg(2+) and Ag(+) ions in a very simple method. By employing this sensor, excellent linear relationships existed between the quenching degree of the ONPCRs and the concentrations of Hg(2+) and Ag(+) ions in the range of 2.0 nM to 60 μM and 5.0 nM to 80 μM, respectively. By using ethylenediaminetetraacetate and ammonia as the masking agent of Hg(2+) and Ag(+) ions, respectively, Hg(2+) or Ag(+) ions were exclusively detected in coexistence with Ag(+) or Hg(2+) ions with high sensitivity, and the detection limits as low as 0.68 and 1.73 nM (3σ) were achieved, respectively, which also provided a reusable detection method for Hg(2+) and Ag(+) ions. Therefore, the easily synthesized fluorescent ONPCRs may have great potential applications in the detection of Hg(2+) and Ag(+) ions for biological assay and environmental protection. PMID:24979236

  19. Reversible colorimetric probes for mercury sensing.

    PubMed

    Coronado, Eugenio; Galán-Mascarós, José R; Martí-Gastaldo, Carlos; Palomares, Emilio; Durrant, James R; Vilar, Ramón; Gratzel, M; Nazeeruddin, Md K

    2005-09-01

    The selectivity and sensitivity of two colorimetric sensors based on the ruthenium complexes N719 [bis(2,2'-bipyridyl-4,4'-dicarboxylate)ruthenium(II) bis(tetrabutylammonium) bis(thiocyanate)] and N749 [(2,2':6',2' '-terpyridine-4,4',4' '-tricarboxylate)ruthenium(II) tris(tetrabutylammonium) tris(isothiocyanate)] are described. It was found that mercury ions coordinate reversibly to the sulfur atom of the dyes' NCS groups. This interaction induces a color change in the dyes at submicromolar concentrations of mercury. Furthermore, the color change of these dyes is selective for mercury(II) when compared with other ions such as lead(II), cadmium(II), zinc(II), or iron(II). The detection limit for mercury(II) ions--using UV-vis spectroscopy--in homogeneous aqueous solutions is estimated to be approximately 20 ppb for N719 and approximately 150 ppb for N749. Moreover, the sensor molecules can be adsorbed onto high-surface-area mesoporous metal oxide films, allowing reversible heterogeneous sensing of mercury ions in aqueous solution. The results shown herein have important implications in the development of new reversible colorimetric sensors for the fast, easy, and selective detection and monitoring of mercuric ions in aqueous solutions. PMID:16131215

  20. Mercury nano-trap for effective and efficient removal of mercury(II) from aqueous solution.

    PubMed

    Li, Baiyan; Zhang, Yiming; Ma, Dingxuan; Shi, Zhan; Ma, Shengqian

    2014-01-01

    Highly effective and highly efficient decontamination of mercury from aqueous media remains a serious task for public health and ecosystem protection. Here we report that this task can be addressed by creating a mercury 'nano-trap' as illustrated by functionalizing a high surface area and robust porous organic polymer with a high density of strong mercury chelating groups. The resultant porous organic polymer-based mercury 'nano-trap' exhibits a record-high saturation mercury uptake capacity of over 1,000 mg g(-1), and can effectively reduce the mercury(II) concentration from 10 p.p.m. to the extremely low level of smaller than 0.4 p.p.b. well below the acceptable limits in drinking water standards (2 p.p.b.), and can also efficiently remove >99.9% mercury(II) within a few minutes. Our work therefore presents a new benchmark for mercury adsorbent materials and provides a new perspective for removing mercury(II) and also other heavy metal ions from contaminated water for environmental remediation. PMID:25410491

  1. Label-free colorimetric detection of mercury via Hg2+ ions-accelerated structural transformation of nanoscale metal-oxo clusters

    NASA Astrophysics Data System (ADS)

    Chen, Kun; She, Shan; Zhang, Jiangwei; Bayaguud, Aruuhan; Wei, Yongge

    2015-11-01

    Mercury and its compounds are known to be extremely toxic but widely distributed in environment. Although many works have been reported to efficiently detect mercury, development of simple and convenient sensors is still longed for quick analyzing mercury in water. In this work, a nanoscale metal-oxo cluster, (n-Bu4N)2[Mo5NaO13(OCH3)4(NO)], (MLPOM), organically-derivatized from monolacunary Lindqvist-type polyoxomolybdate, is found to specifically react with Hg2+ in methanol/water via structural transformation. The MLPOM methanol solution displays a color change from purple to brown within seconds after being mixed with an aqueous solution containing Hg2+. By comparing the structure of polyoxomolybdate before and after reaction, the color change is revealed to be the essentially structural transformation of MLPOM accelerated by Hg2+. Based on this discovery, MLPOM could be utilized as a colorimetric sensor to sense the existence of Hg2+, and a simple and label-free method is developed to selectively detect aqueous Hg2+. Furthermore, the colorimetric sensor has been applied to indicating mercury contamination in industrial sewage.

  2. Chronoamperometric study of the films formed by 4,4'-bipyridyl cation radical salts on mercury in the presence of iodide ions: consecutive two-dimensional phase transitions.

    PubMed

    Gómez, L; Ruiz, J J; Camacho, L; Rodríguez-Amaro, R

    2005-01-01

    This paper reports a new mathematical model for consecutive two-dimensional phase transitions that accounts for the chronoamperometric behavior observed in the formation of electrochemical phases by 4,4'-bipyridyl cation radical (BpyH(2)(*)(+)) on mercury in aqueous iodide solutions. Also, a new interpretation for the induction time is proposed. PMID:15620326

  3. Label-free colorimetric detection of mercury via Hg2+ ions-accelerated structural transformation of nanoscale metal-oxo clusters

    PubMed Central

    Chen, Kun; She, Shan; Zhang, Jiangwei; Bayaguud, Aruuhan; Wei, Yongge

    2015-01-01

    Mercury and its compounds are known to be extremely toxic but widely distributed in environment. Although many works have been reported to efficiently detect mercury, development of simple and convenient sensors is still longed for quick analyzing mercury in water. In this work, a nanoscale metal-oxo cluster, (n-Bu4N)2[Mo5NaO13(OCH3)4(NO)], (MLPOM), organically-derivatized from monolacunary Lindqvist-type polyoxomolybdate, is found to specifically react with Hg2+ in methanol/water via structural transformation. The MLPOM methanol solution displays a color change from purple to brown within seconds after being mixed with an aqueous solution containing Hg2+. By comparing the structure of polyoxomolybdate before and after reaction, the color change is revealed to be the essentially structural transformation of MLPOM accelerated by Hg2+. Based on this discovery, MLPOM could be utilized as a colorimetric sensor to sense the existence of Hg2+, and a simple and label-free method is developed to selectively detect aqueous Hg2+. Furthermore, the colorimetric sensor has been applied to indicating mercury contamination in industrial sewage. PMID:26559602

  4. Mercury ion thruster research, 1978

    NASA Technical Reports Server (NTRS)

    Wilbur, P. J.

    1978-01-01

    The effects of 8 cm thruster main and neutralizer cathode operating conditions on cathode orifice plate temperatures were studied. The effects of cathode operating conditions on insert temperature profiles and keeper voltages are presented for three different types of inserts. The bulk of the emission current is generally observed to come from the downstream end of the insert rather than from the cathode orifice plate. Results of a test in which the screen grid plasma sheath of a thruster was probed as the beam current was varied are shown. Grid performance obtained with a grid machined from glass ceramic is discussed. The effects of copper and nitrogen impurities on the sputtering rates of thruster materials are measured experimentally and a model describing the rate of nitrogen chemisorption on materials in either the beam or the discharge chamber is presented. The results of optimization of a radial field thruster design are presented. Performance of this device is shown to be comparable to that of a divergent field thruster and efficient operation with the screen grid biased to floating potential, where its susceptibility to sputter erosion damage is reduced, is demonstrated.

  5. 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...

  6. 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.

  7. Bioluminescent Probe for Detecting Mercury(II) in Living Mice.

    PubMed

    Jiang, Tianyu; Ke, Bowen; Chen, Hui; Wang, Weishan; Du, Lupei; Yang, Keqian; Li, Minyong

    2016-08-01

    A novel bioluminescence probe for mercury(II) was obtained on the basis of the distinct deprotection reaction of dithioacetal to decanal, so as to display suitable sensitivity and selectivity toward mercury(II) over other ions with bacterial bioluminescence signal. These experimental results indicated such a probe was a novel promising method for mercury(II) bioluminescence imaging in environmental and life sciences ex vivo and in vivo. PMID:27412583

  8. 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 ...

  9. 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.

  10. FATE AND BIOLOGICAL EFFECTS OF MERCURY INTRODUCED INTO ARTIFICIAL STREAMS

    EPA Science Inventory

    Mercuric ion was continuously input to artificial stream channels to provide water concentrations of 0.01, 1.0, and 5.0 micrograms/l. Channel components were periodically sampled for total mercury analyses. The effects of mercury on the algal components of the periphyton communit...

  11. Removal of Mercury by Foam Fractionation Using Surfactin, a Biosurfactant

    PubMed Central

    Chen, Hau-Ren; Chen, Chien-Cheng; Reddy, A. Satyanarayana; Chen, Chien-Yen; Li, Wun Rong; Tseng, Min-Jen; Liu, Hung-Tsan; Pan, Wei; Maity, Jyoti Prakash; Atla, Shashi B.

    2011-01-01

    The separation of mercury ions from artificially contaminated water by the foam fractionation process using a biosurfactant (surfactin) and chemical surfactants (SDS and Tween-80) was investigated in this study. Parameters such as surfactant and mercury concentration, pH, foam volume, and digestion time were varied and their effects on the efficiency of mercury removal were investigated. The recovery efficiency of mercury ions was highly sensitive to the concentration of the surfactant. The highest mercury ion recovery by surfactin was obtained using a surfactin concentration of 10 × CMC, while recovery using SDS required < 10 × CMC and Tween-80 >10 × CMC. However, the enrichment of mercury ions in the foam was superior with surfactin, the mercury enrichment value corresponding to the highest metal recovery (10.4%) by surfactin being 1.53. Dilute solutions (2-mg L−1 Hg2+) resulted in better separation (36.4%), while concentrated solutions (100 mg L−1) enabled only a 2.3% recovery using surfactin. An increase in the digestion time of the metal solution with surfactin yielded better separation as compared with a freshly-prepared solution, and an increase in the airflow rate increased bubble production, resulting in higher metal recovery but low enrichment. Basic solutions yielded higher mercury separation as compared with acidic solutions due to the precipitation of surfactin under acidic conditions. PMID:22174661

  12. Fluvial transport of mercury, organic carbon, suspended sediment, and selected major ions in contrasting stream basins in South Carolina and New York, October 2004 to September 2009

    USGS Publications Warehouse

    Journey, Celeste A.; Burns, Douglas A.; Riva-Murray, Karen; Brigham, Mark E.; Button, Daniel T.; Feaster, Toby D.; Petkewich, Matthew D.; Bradley, Paul M.

    2012-01-01

    A spatially extensive assessment of the environmental controls on mercury transport and bioaccumulation in stream ecosystems in New York and South Carolina was conducted as part of the U.S. Geological Survey National Water-Quality Assessment Program and included the determination of fluvial transport of mercury and associated constituents during water years 2005–2009. (A water year extends from October of one calendar year to September of the next calendar year.) In the Coastal Plain region of South Carolina, the study area included the Edisto River and its headwater tributary, McTier Creek. In the Adirondack region of New York, the study area included the upper Hudson River and its headwater tributary, Fishing Brook. Median concentrations of filtered total mercury rangedfrom 1.55 nanograms per liter (ng/L) at the Hudson River site to 2.77 ng/L at the Edisto River site. The Edisto River site had the greatest median filtered methylmercury concentration, at 0.32 ng/L, and the Hudson River site had the least median filtered methylmercury concentration, at 0.07 ng/L.

  13. 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.

  14. Absorption characteristics of elemental mercury in mercury chloride solutions.

    PubMed

    Ma, Yongpeng; Xu, Haomiao; Qu, Zan; Yan, Naiqiang; Wang, Wenhua

    2014-11-01

    Elemental mercury (Hg(0)) in flue gases can be efficiently captured by mercury chloride (HgCl2) solution. However, the absorption behaviors and the influencing effects are still poorly understood. The mechanism of Hg(0) absorption by HgCl2 and the factors that control the removal were studied in this paper. It was found that when the mole ratio of Cl(-) to HgCl2 is 10:1, the Hg(0) removal efficiency is the highest. Among the main mercury chloride species, HgCl3(-) is the most efficient ion for Hg(0) removal in the HgCl2 absorption system when moderate concentrations of chloride ions exist. The Hg(0) absorption reactions in the aqueous phase were investigated computationally using Moller-Plesset perturbation theory. The calculated Gibbs free energies and energy barriers are in excellent agreement with the results obtained from experiments. In the presence of SO3(2-) and SO2, Hg(2+) reduction occurred and Hg(0) removal efficiency decreased. The reduced Hg(0) removal can be controlled through increased chloride concentration to some degree. Low pH value in HgCl2 solution enhanced the Hg(0) removal efficiency, and the effect was more significant in dilute HgCl2 solutions. The presence of SO4(2-) and NO3(-) did not affect Hg(0) removal by HgCl2. PMID:25458680

  15. Space Weathering of Asteroids, Mercury, and the Moon

    NASA Astrophysics Data System (ADS)

    Orlando, T. M.; Fiege, K.; Bennett, C. J.; Trieloff, M.; Srama, R.

    2015-11-01

    We summarize recent laboratory studies on photon, ion, and micrometeorite “weathering” of Mercury and asteroid surface analogs as well as actual lunar regolith samples and present results from linking micrometeorite impacts to energetic irradiation.

  16. 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

  17. 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.

  18. The capture of oxidized mercury from simulated desulphurization aqueous solutions.

    PubMed

    Ochoa-González, Raquel; Díaz-Somoano, Mercedes; Martínez-Tarazona, M Rosa

    2013-05-15

    Elemental mercury in flue gases from coal combustion is difficult to control. However, oxidized mercury species are soluble in water and can be removed with a high degree of efficiency in wet flue gas desulphurization (WFGD) systems operating in coal combustion plants, provided that no re-emissions occur. In this article the mechanisms affecting the re-emission of oxidized mercury species in WFGD conditions via sulphite ions are discussed. The parameters studied include the operating temperature, the pH, the redox potential, the concentrations of mercury and oxygen in the flue gas and the concentration of reductive ions in the solution. The results show that temperature, pH and the concentration of mercury at the inlet of the WFGD systems are the most important factors affecting oxidized mercury removal. The results indicate that sulphite ions, not only contribute to the reduction of Hg(2+), but that they may also stabilize the mercury in the liquid fraction of the WFGD limestone slurry. Consequently, factors that increase the sulphite content in the slurry such as a low oxygen concentration promote the co-capture of mercury with sulphur. PMID:23500649

  19. Thiacrown polymers for removal of mercury from waste streams

    DOEpatents

    Baumann, Theodore F.; Reynolds, John G.; Fox, Glenn A.

    2002-01-01

    Thiacrown polymers immobilized to a polystyrene-divinylbenzene matrix react with Hg.sup.2+ under a variety of conditions to efficiently and selectively remove Hg.sup.2+ ions from acidic aqueous solutions, even in the presence of a variety of other metal ions. The mercury can be recovered and the polymer regenerated. This mercury removal method has utility in the treatment of industrial wastewater, where a selective and cost-effective removal process is required.

  20. Thiacrown polymers for removal of mercury from waste streams

    DOEpatents

    Baumann, Theodore F.; Reynolds, John G.; Fox, Glenn A.

    2004-02-24

    Thiacrown polymers immobilized to a polystyrene-divinylbenzene matrix react with Hg.sup.2+ under a variety of conditions to efficiently and selectively remove Hg.sup.2+ ions from acidic aqueous solutions, even in the presence of a variety of other metal ions. The mercury can be recovered and the polymer regenerated. This mercury removal method has utility in the treatment of industrial wastewater, where a selective and cost-effective removal process is required.

  1. Subnanogram determination of inorganic and organic mercury by helium-microwave induced plasma-atomic emission spectrometry

    SciTech Connect

    Fukushi, K. ); Willie, S.N.; Sturgeon, R.E. )

    1993-02-01

    Inorganic and organic mercury were determined by helium-microwave induced plasma-atomic emission spectrometry following cold vapor generation. Whereas only inorganic mercury was reduced by stannous ion in an acidic medium, both inorganic and organic mercury (total mercury) were reduced by stannous ion in the presence of cupric ion in a basic medium. Organic mercury was determined as the difference between total and inorganic mercury. Detection limits for inorganic and organic mercury were 11 and 10 pg, respectively. The accuracy of the proposed method was verified through the determination of inorganic, total and organic mercury in two marine biological standard reference materials, DORM-1 and TORT-1. 21 refs., 1 fig., 4 tabs.

  2. CME impact on Mercury's sputtered exospheric environment

    NASA Astrophysics Data System (ADS)

    Pfleger, M.; Lichtenegger, H. I. M.; Lammer, H.; Mura, A.; Wurz, P.; Martin-Fernandez, J. A.

    2013-09-01

    Solar wind and magnetospheric plasma precipitation onto the surface of Mercury triggers the formation of exospheric particle populations by sputtering processes. Numerical modeling of Mercury's magnetosphere has shown that the weak intrinsic magnetic field of the planet is sufficient to prevent the equatorial regions from being impacted by solar wind ions during moderate solar wind conditions. However, intense fluxes of protons are expected to hit the auroral regions, giving rise to the release of surface elements at high latitudes by ion sputtering. During high solar wind dynamic pressure conditions in the case of CME events, the solar wind protons will have access to Mercury's entire dayside surface, which may result in a considerable filling of the exosphere by sputtered surface material.

  3. Treatment of radioactive laboratory waste for mercury removal

    SciTech Connect

    Osteen, A.B.; Bibler, J.P.

    1990-01-01

    Routine analyses of Savannah River Laboratory wastes at the Savannah River Site occasionally reveal mercury concentrations in the waste in excess of the 0.200 {mu}g/L RCRA limit. An ion exchange resin has been demonstrated to be effective for the removal of dissolved mercury from laboratory waste in a special permitted project. The ion exchange material is Duolite{trademark} GT-73, a polystyrene/divinylbenzene resin with thiol functional groups. As a result of the decontamination demonstration, the resin is in use or under consideration for use with several other SRS radwaste streams as a reliable medium for mercury removal.

  4. Treatment of radioactive laboratory waste for mercury removal. Revision 1

    SciTech Connect

    Osteen, A.B.; Bibler, J.P.

    1990-12-31

    Routine analyses of Savannah River Laboratory wastes at the Savannah River Site occasionally reveal mercury concentrations in the waste in excess of the 0.200 {mu}g/L RCRA limit. An ion exchange resin has been demonstrated to be effective for the removal of dissolved mercury from laboratory waste in a special permitted project. The ion exchange material is Duolite{trademark} GT-73, a polystyrene/divinylbenzene resin with thiol functional groups. As a result of the decontamination demonstration, the resin is in use or under consideration for use with several other SRS radwaste streams as a reliable medium for mercury removal.

  5. 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.

  6. MERCURY IN THE ENVIRONMENT

    EPA Science Inventory

    Mercury is released from a variety of sources and exhibits a complicated chemistry. According to the Mercury Study Report to Congress, mercury fluxes and budgets in water, soil, and other media have increased by a factor of two to five over pre-industrial levels. The primary expo...

  7. Mercury in the environment

    NASA Technical Reports Server (NTRS)

    Fulkerson, W.; Lyon, W. S.; Shults, W. D.; Wallace, R. A.

    1972-01-01

    Problems in assessing mercury concentrations in environmental materials are discussed. Data for situations involving air, water, rocks, soils, sediments, sludges, fossil fuels, plants, animals, foods, and man are drawn together and briefly evaluated. Details are provided regarding the toxicity of mercury along with tentative standards and guidelines for mercury in air, drinking water, and food.

  8. Investigation of mercury thruster isolators

    NASA Technical Reports Server (NTRS)

    Mantenieks, M. A.

    1973-01-01

    Mercury ion thruster isolator lifetime tests were performed using different isolator materials and geometries. Tests were performed with and without the flow of mercury through the isolators in an oil diffusion pumped vacuum facility and cryogenically pumped bell jar. The onset of leakage current in isolators occurred in time intervals ranging from a few hours to many hundreds of hours. In all cases, surface contamination was responsible for the onset of leakage current and subsequent isolator failure. Rate of increase of leakage current and the leakage current level increased approximately exponentially with isolator temperature. Careful attention to shielding techniques and the elimination of sources of metal oxides appear to have eliminated isolator failures as a thruster life limiting mechanism.

  9. Asymmetries in the dust flux at Mercury

    NASA Astrophysics Data System (ADS)

    Borin, P.; Cremonese, G.; Bruno, M.; Marzari, F.

    2016-01-01

    The planet Mercury has an extended and tenuous exosphere made up of atoms that are ejected from the surface by energetic processes, including hypervelocity micrometeoritic impacts, photon-stimulated desorption by UV radiation, and ion sputtering. Meteoroid impacts of particles smaller than 1 cm, which are important for replenishing the exosphere daily, are not well-studied. We present a systematic investigation of spatial asymmetries in the impactor rate of micrometeoroids over Mercury's surface as a function of planetary true anomaly (TAA). Since the orbit of Mercury is quite eccentric a seasonal variation of the impact rate is to be expected. We find that the source peaks near the planetary equator for most TAA. Contrary to previous assumptions, we find the source to be non-uniform in local time. Only certain regions of Mercury are exposed to dust as a result of the orbital elements of Mercury and of the Main Belt particles (inclination less than 20°). Our results offer important constraints on transport models used for interpreting measurements of this exosphere, but also inform studies of space weathering of Mercury's surface.

  10. Design and synthesis of a terbium(III) complex-based luminescence probe for time-gated luminescence detection of mercury(II) ions.

    PubMed

    Cui, Guanfeng; Ye, Zhiqiang; Zhang, Run; Wang, Guilan; Yuan, Jingli

    2012-01-01

    Time-gated luminescence detection technique using lanthanide complexes as luminescent probes is a useful and highly sensitive method. However, the effective application of this technique is limited by the lack of the target-responsive luminescent lanthanide complexes that can specifically recognize various analytes in aqueous solutions. In this work, a dual-functional ligand that can form a stable complex with Tb(3+) and specifically recognize Hg(2+) ions in aqueous solutions, N,N,N(1),N(1)-{[2,6-bis(3'-aminomethyl-1'-pyrazolyl)-4-[N,N-bis(3″,6″-dithiaoctyl)-aminomethyl]- pyridine]} tetrakis(acetic acid) (BBAPTA), has been designed and synthesized. The luminescence of its Tb(3+) complex is weak, but can be effectively enhanced upon reaction with Hg(2+) ions in aqueous solutions. The luminescence response investigations of BBAPTA-Tb(3+) to various metal ions indicate that the complex has a good luminescence sensing selectivity for Hg(2+) ions, but not for other metal ions. Thus a highly sensitive time-gated luminescence detection method for Hg(2+) ions was developed by using BBAPTA-Tb(3+) as a luminescent probe. The dose-dependent luminescence enhancement of the probe shows a good linearity with a detection limit of 17 nM for Hg(2+) ions. These results demonstrated the efficacy and advantages of the new Tb(3+) complex-based luminescence probe for the sensitive and selective detection of Hg(2+) ions. PMID:21853255

  11. Performance of 10-kW class xenon ion thrusters

    NASA Technical Reports Server (NTRS)

    Patterson, Michael J.; Rawlin, Vincent K.

    1988-01-01

    Presented are performance data for laboratory and engineering model 30 cm-diameter ion thrusters operated with xenon propellant over a range of input power levels from approximately 2 to 20 kW. Also presented are preliminary performance results obtained from laboratory model 50 cm-diameter cusp- and divergent-field ion thrusters operating with both 30 cm- amd 50 cm-diameter ion optics up to a 20 kW input power. These data include values of discharge chamber propellant and power efficiencies, as well as values of specific impulse, thruster efficiency, thrust and power. The operation of the 30 cm- and 50 cm-diameter ion optics are also discussed.

  12. Sputtering of sodium on the planet Mercury

    NASA Technical Reports Server (NTRS)

    Mcgrath, M. A.; Johnson, R. E.; Lanzerotti, L. J.

    1986-01-01

    It is shown here that ion sputtering cannot account for the observed neutral sodium vapor column density on Mercury, but that it is an important loss mechanism for Na. Photons are likely to be the dominant stimulus, both directly through photodesorption and indirectly through thermal desorption of absorbed Na. It is concluded that the atmosphere produced is characterized by the planet's surface temperature, with the ion-sputtered Na contributing to a lesser, but more extended, component of the atmosphere.

  13. Kinetics of mercury extraction using oleic acid

    SciTech Connect

    Larson, K.A.; Wiencek, J.M. )

    1993-11-01

    In the absence of halide ion, Hg[sup 2+] is the predominant species in water and can be effectively extracted using oleic acid. The organic phase complex that is formed is HgR[sub 2] [center dot] 2(RH). The presence of polar modifiers in the organic phase facilitates the formation of a complex dimer, [HgR[sub 2] [center dot] 2(RH)][sub 2]. Kinetics of the extraction reaction have been studied as a function of pH, Hg[sup 2+] concentration, oleic acid concentration, and mixing rate in a stirred cell reactor. Extraction kinetics are first order in mercury concentration and zero order with respect to oleic acid concentration and pH. This is consistent with film theory predictions for an instantaneous reaction that is mass transfer controlled. A diffusion/reaction model for mercury extraction in a batch stirred tank reactor has been developed that incorporates this information, and includes mass transfer of mercuric ion from the bulk solution to the droplet surface, equilibrium between aqueous mercury and organic mercury complex at the droplet interface, and diffusion and dimer formation of the complex within the organic phase droplet. Without the use of adjustable parameters, this model successfully predicts mercury extraction rate and equilibrium.

  14. Study of nitrogen flowing afterglow with mercury vapor injection

    SciTech Connect

    Mazánková, V. Krčma, F.; Trunec, D.

    2014-10-21

    The reaction kinetics in nitrogen flowing afterglow with mercury vapor addition was studied by optical emission spectroscopy. The DC flowing post-discharge in pure nitrogen was created in a quartz tube at the total gas pressure of 1000 Pa and discharge power of 130 W. The mercury vapors were added into the afterglow at the distance of 30 cm behind the active discharge. The optical emission spectra were measured along the flow tube. Three nitrogen spectral systems – the first positive, the second positive, and the first negative, and after the mercury vapor addition also the mercury resonance line at 254 nm in the spectrum of the second order were identified. The measurement of the spatial dependence of mercury line intensity showed very slow decay of its intensity and the decay rate did not depend on the mercury concentration. In order to explain this behavior, a kinetic model for the reaction in afterglow was developed. This model showed that the state Hg(6 {sup 3}P{sub 1}), which is the upper state of mercury UV resonance line at 254 nm, is produced by the excitation transfer from nitrogen N{sub 2}(A{sup 3}Σ{sup +}{sub u}) metastables to mercury atoms. However, the N{sub 2}(A{sup 3}Σ{sup +}{sub u}) metastables are also produced by the reactions following the N atom recombination, and this limits the decay of N{sub 2}(A{sup 3}Σ{sup +}{sub u}) metastable concentration and results in very slow decay of mercury resonance line intensity. It was found that N atoms are the most important particles in this late nitrogen afterglow, their volume recombination starts a chain of reactions which produce excited states of molecular nitrogen. In order to explain the decrease of N atom concentration, it was also necessary to include the surface recombination of N atoms to the model. The surface recombination was considered as a first order reaction and wall recombination probability γ = (1.35 ± 0.04) × 10{sup −6} was determined from the experimental data. Also

  15. Study of nitrogen flowing afterglow with mercury vapor injection

    NASA Astrophysics Data System (ADS)

    Mazánková, V.; Trunec, D.; Krčma, F.

    2014-10-01

    The reaction kinetics in nitrogen flowing afterglow with mercury vapor addition was studied by optical emission spectroscopy. The DC flowing post-discharge in pure nitrogen was created in a quartz tube at the total gas pressure of 1000 Pa and discharge power of 130 W. The mercury vapors were added into the afterglow at the distance of 30 cm behind the active discharge. The optical emission spectra were measured along the flow tube. Three nitrogen spectral systems - the first positive, the second positive, and the first negative, and after the mercury vapor addition also the mercury resonance line at 254 nm in the spectrum of the second order were identified. The measurement of the spatial dependence of mercury line intensity showed very slow decay of its intensity and the decay rate did not depend on the mercury concentration. In order to explain this behavior, a kinetic model for the reaction in afterglow was developed. This model showed that the state Hg(6 3P1), which is the upper state of mercury UV resonance line at 254 nm, is produced by the excitation transfer from nitrogen N2(A ^3 Σ ^+_u) metastables to mercury atoms. However, the N2(A ^3 Σ ^+_u) metastables are also produced by the reactions following the N atom recombination, and this limits the decay of N2(A ^3 Σ ^+_u) metastable concentration and results in very slow decay of mercury resonance line intensity. It was found that N atoms are the most important particles in this late nitrogen afterglow, their volume recombination starts a chain of reactions which produce excited states of molecular nitrogen. In order to explain the decrease of N atom concentration, it was also necessary to include the surface recombination of N atoms to the model. The surface recombination was considered as a first order reaction and wall recombination probability γ = (1.35 ± 0.04) × 10-6 was determined from the experimental data. Also sensitivity analysis was applied for the analysis of kinetic model in order to

  16. Stabilization of mercury-containing wastes using sulfide.

    PubMed

    Piao, Haishan; Bishop, Paul L

    2006-02-01

    This paper summarizes the findings of our studies on mercury stabilization using sulfide. Primary stabilization variables such as stabilization pH and sulfide/mercury molar ratio were tested. Mercury stabilization effectiveness was evaluated using the Toxicity Characteristic Leaching Procedure (TCLP) and the constant pH leaching tests. The influence of interfering ions on mercury immobilization was also tested. The experimental results indicate that the sulfide-induced treatment technology is an effective way to minimize mercury leaching. It was found that the most effective mercury stabilization occurs at pH 6 combined with a sulfide/mercury molar ratio of 1. The combined use of increased dosage of sulfide and ferrous ions ([S]/[Hg]=2 and [Fe]/[Hg]=3 at pH=6) can significantly reduce interferences by chloride and/or phosphate during sulfide-induced mercury immobilization. The sulfide-treated waste stabilization efficiency reached 98%, even with exposure of the wastes to high pH leachants. PMID:16099084

  17. Characterization of mercury-containing protein in human plasma.

    PubMed

    Yun, Zhaojun; Li, Lu; Liu, Lihong; He, Bin; Zhao, Xingchen; Jiang, Guibin

    2013-06-01

    Characterization of mercury binding protein in the human body is very important for understanding the metabolism and the mechanism of toxication of ingested mercuric compounds. In this study, mercury-containing protein in human plasma was separated by on-line heart-cutting two-dimensional high performance liquid chromatography (2D-HPLC). This 2D separation system used size exclusion liquid chromatography (SEC) followed by weak anion exchange liquid chromatography (WAX) and the two LC parts were coupled by a six-port valve equipped with a storage loop and controled by the computer. The WAX effluent was determined by both UV detection and inductively coupled plasma-mass spectrometry (ICP-MS) to locate the mercury-containing protein. A unique mercury-containing protein fraction was obtained by 2D-HPLC separation and subsequently identified by HPLC coupled with linear ion trap-Fourier transform ion cyclotron resonance mass spectrometry (HPLC-LTQ-FT). The database search confirmed that the mercury-containing protein in the human plasma is human serum albumin (HSA). The stoichiometry and thermodyamics interaction of inorganic mercury (Hg(2+)) with HSA was studied by isothermal titration calorimetry (ITC) and two binding types were observed. Mercury-containing protein in human plasma was separated and identified in the present study and it is important for understanding the metabolism of mercury in the human body. PMID:23748885

  18. Phytoremediation of Ionic and Methyl Mercury P

    SciTech Connect

    Meagher, Richard B.

    1999-06-01

    Our long-term goal is to enable highly productive plant species to extract, resist, detoxify, and/or sequester toxic heavy metal pollutants as an environmentally friendly alternative to physical remediation methods. We have focused this phytoremediation research on soil and water-borne ionic and methylmercury. Mercury pollution is a serious world-wide problem affecting the health of human and wild-life populations. Methylmercury, produced by native bacteria at mercury-contaminated wetland sites, is a particularly serious problem due to its extreme toxicity and efficient biomagnification in the food chain. We engineered several plant species (e.g., Arabidopsis, tobacco, canola, yellow poplar, rice) to express the bacterial genes, merB and/or merA, under the control of plant regulatory sequences. These transgenic plants acquired remarkable properties for mercury remediation. (1) Transgenic plants expressing merB (organomercury lyase) extract methylmercury from their growth substrate and degrade it to less toxic ionic mercury. They grow on concentrations of methylmercury that kill normal plants and accumulate low levels of ionic mercury. (2) Transgenic plants expressing merA (mercuric ion reductase) extract and electrochemically reduce toxic, reactive ionic mercury to much less toxic and volatile metallic mercury. This metal transformation is driven by the powerful photosynthetic reducing capacity of higher plants that generates excess NADPH using solar energy. MerA plants grow vigorously on levels of ionic mercury that kill control plants. Plants expressing both merB and merA degrade high levels of methylmercury and volatilize metallic mercury. These properties were shown to be genetically stable for several generations in the two plant species examined. Our work demonstrates that native trees, shrubs, and grasses can be engineered to remediate the most abundant toxic mercury pollutants. Building on these data our working hypothesis for the next grant period is that

  19. Mercury binding sites in thiol-functionalized mesostructured silica.

    PubMed

    Billinge, Simon J L; McKimmy, Emily J; Shatnawi, Mouath; Kim, HyunJeong; Petkov, Valeri; Wermeille, Didier; Pinnavaia, Thomas J

    2005-06-15

    Thiol-functionalized mesostructured silica with anhydrous compositions of (SiO(2))(1)(-)(x)()(LSiO(1.5))(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 < or = 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(t))(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. PMID:15941284

  20. 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 ...

  1. 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

  2. Mercury's Dynamic Magnetosphere: What Have We Learned from MESSENGER?

    NASA Astrophysics Data System (ADS)

    Slavin, James A.

    2016-04-01

    Mercury's magnetosphere is created by the solar wind interaction with its dipolar, spin-axis aligned, northward offset intrinsic magnetic field. Structurally it resembles that of the Earth in many respects, but the magnetic field intensities and plasma densities are all higher at Mercury due to conditions in the inner solar system. Magnetospheric plasma at Mercury appears to be primarily of solar wind origin, i.e. H+ and He++, but with 10% Na+ derived from the exosphere. Solar wind sputtering and other processes promote neutrals from the regolith into the exosphere where they may be ionized and incorporated into the magnetospheric plasma population. At this point in time, about one year after MESSENGER's impact and one year prior to BepiColombo's launch, we review MESSENGER's observations of magnetospheric dynamics and structure. In doing so we will provide our best answers to the following six questions: Question #1: How do magnetosheath conditions at Mercury differ from what is found at the other planets? Question #2: How do conditions in Mercury's magnetosheath contribute to the dynamic nature of Mercury's magnetosphere? How does magnetopause reconnection at Mercury differ from what is seen at Earth? Are flux transfer events (FTEs) a major driver of magnetospheric convection at Mercury? Question #3: Does reconnection ever erode the dayside magnetosphere to the point where the subsolar region of the surface is exposed to direct solar wind impact? To what extent do induction currents driven in Mercury's interior limit the solar wind flux to the surface? Do FTEs contribute significantly to the solar wind flux reaching the surface? Question #4: What effects do heavy planetary ions have on Mercury's magnetosphere? Question #5: Does Mercury's magnetotail store and dissipate magnetic energy in a manner analogous to substorms at Earth? How is the process affected by the lack of an ionosphere and the expected high electrical resistivity of the crust? Question #6: How

  3. Dual detection of nitrate and mercury in water using disposable electrochemical sensors.

    PubMed

    Bui, Minh-Phuong N; Brockgreitens, John; Ahmed, Snober; Abbas, Abdennour

    2016-11-15

    Here we report a disposable, cost effective electrochemical paper-based sensor for the detection of both nitrate and mercury ions in lake water and contaminated agricultural runoff. Disposable carbon paper electrodes were functionalized with selenium particles (SePs) and gold nanoparticles (AuNPs). The AuNPs served as a catalyst for the reduction of nitrate ions using differential pulse voltammetry techniques. The AuNPs also served as a nucleation sites for mercury ions. The SePs further reinforced this mercury ion nucleation due to their high binding affinity to mercury. Differential pulse stripping voltammetry techniques were used to further enhance mercury ion accumulation on the modified electrode. The fabricated electrode was characterized by scanning electron microscopy, energy-dispersive X-ray spectroscopy, and electrochemistry techniques. The obtained results show that the PEG-SH/SePs/AuNPs modified carbon paper electrode has a dual functionality in that it can detect both nitrate and mercury ions without any interference. The modified carbon paper electrode has improved the analytical sensitivity of nitrate and mercury ions with limits of detection of 8.6µM and 1.0ppb, respectively. Finally, the modified electrode was used to measure nitrate and mercury in lake water samples. PMID:27183277

  4. Molecular mechanisms of the epithelial transport of toxic metal ions, particularly mercury, cadmium, lead, arsenic, zinc and copper. Progress report, January 1, 1980-December 31, 1980

    SciTech Connect

    Wasserman, R H

    1980-01-01

    Investigations were continued to elucidate the mode of transepithelial transport of toxic metal ions across the gastrointestinal tract, as well as their interactions with biological processes and other metal ions. All experimental details that are either published, submitted for publication or in press during this report period are included in the Appendix. Primary attention for this report has been given to the intestinal absorption of lead and its interaction with other biological moieties.

  5. 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)

  6. 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.

  7. 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.

  8. Field Line Resonance at Mercury's Magnetosphere: A Simulation Study

    SciTech Connect

    Eun-Hwa Kim, Jay R. Johnson, and Dong-Hun Lee

    2008-05-22

    Ultra low frequency (ULF) waves, which are assumed to be standing waves on the field, are observed by the Mariner 10 spacecraft at Mercury. These waves are oscillating at 38% of the proton gyrofrequency. It is well known that the heavy ions, such as Na+, are abundant in Mercury's magnetosphere. Because the presence of different ion species has an influence on the plasma dispersion characteristics near the ion gyro-frequencies, such relatively high frequencies of magnetospheric eigenoscillations at Mercury require a multi-fluid treatment for the plasma. Thus ULF waves at Mercury may have a distinct difference from typical ULF oscillations at Earth, which are often described in terms of magnetohydrodynamics (MHD). By adopting a multi-fluid numerical wave model, we examine how magnetic eigenoscillations occur in Mercury's magnetosphere. Because protons and sodium ions are the main constituents at Mercury, we assume an electron-proton- sodium plasma in our model. The frequency spectra and time histories of the electromagnetic fields at the ion-ion hybrid (IIH) and cavity resonances are presented. Our results show: (1) The observed ULF waves are likely compressional waves rather than FLR. (2) Resonant absorption occurs at the IIH resonance, thus incoming compressional waves are converted into the IIH resonance. (3) The IIH resonance is strongly guided by the background magnetic field and shows linear polarization in the east-west meridian. (4) Both the Alfvén and the IIH are suggested as a mechanism for FLR at Mercury. (5) The resonance frequency enables us to estimate the local heavy ion concentration ratio.

  9. Ion propulsion cost effectivity

    NASA Technical Reports Server (NTRS)

    Zafran, S.; Biess, J. J.

    1978-01-01

    Ion propulsion modules employing 8-cm thrusters and 30-cm thrusters were studied for Multimission Modular Spacecraft (MMS) applications. Recurring and nonrecurring cost elements were generated for these modules. As a result, ion propulsion cost drivers were identified to be Shuttle charges, solar array, power processing, and thruster costs. Cost effective design approaches included short length module configurations, array power sharing, operation at reduced thruster input power, simplified power processing units, and power processor output switching. The MMS mission model employed indicated that nonrecurring costs have to be shared with other programs unless the mission model grows. Extended performance missions exhibited the greatest benefits when compared with monopropellant hydrazine propulsion.

  10. 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.

  11. Oxidation of Mercury in Products of Coal Combustion

    SciTech Connect

    Peter Walsh; Giang Tong; Neeles Bhopatkar; Thomas Gale; George Blankenship; Conrad Ingram; Selasi Blavo Tesfamariam Mehreteab; Victor Banjoko; Yohannes Ghirmazion; Heng Ban; April Sibley

    2009-09-14

    scale, burning bituminous coals (Gale, 2006) and blends of bituminous coals with Powder River Basin coal (Gale, 2005). The removal of mercury by fly ash and unburned carbon in the flue gas from combustion of the bituminous coals and blends was reproduced with satisfactory accuracy by the model. The enhancement of mercury capture in the presence of calcium (Gale, 2005) explained a synergistic effect of blending on mercury removal across the baghouse. The extent of mercury oxidation, on the other hand, was not so well described by the simulation, because of oversensitivity of the oxidation process in the model to the concentration of unburned carbon. Combined catalysts and sorbents for oxidation and removal of mercury from flue gas at low temperature were based on surfactant-templated silicas containing a transition metal and an organic functional group. The presence of both metal ions and organic groups within the pore structure of the materials is expected to impart to them the ability to simultaneously oxidize elemental mercury and adsorb the resulting oxidized mercury. Twelve mesoporous organosilicate catalysts/sorbents were synthesized, with and without metals (manganese, titanium, vanadium) and organic functional groups (aminopropyl, chloropropyl, mercaptopropyl). Measurement of mercury oxidation and adsorption by the candidate materials remains for future work.

  12. Pulsed Laser-Driven Molecular Self-assembly of Cephalexin: Aggregation-Induced Fluorescence and Its Utility as a Mercury Ion Sensor.

    PubMed

    Singh, Pradeep Kumar; Prabhune, Asmita; Ogale, Satishchandra

    2015-11-01

    A fluorescent self-assembly of cephalexin is obtained by pulsed laser irradiation process. An intense fluorescence emission is found in the self-assembled form due to occurrence of a typical aggregation-induced emission in cephalexin molecules. It is observed that fluorescence quenching of the self-assembled fluorescent nanostructures occurs in the presence of extremely low Hg(++) ions concentrations (10(-7) m) as compared to other heavy metal ions e.g. Ferrous (Fe(++) ), Manganese (Mn(++) ), Magnesium (Mg(++) ), Cobalt (Co(++) ), Nickel (Ni(++) ) and Zinc (Zn(++) ) at the same concentrations. PMID:26333412

  13. Mercury re-emission in flue gas multipollutants simultaneous absorption system.

    PubMed

    Liu, Yue; Wang, Qingfeng; Mei, Rongjun; Wang, Haiqiang; Weng, Xiaole; Wu, Zhongbiao

    2014-12-01

    Recently, simultaneous removal of SO2, NOx and oxidized mercury in wet flue gas desulfurization (WFGD) scrubber has become a research focus. Mercury re-emission in traditional WFGD system has been widely reported due to the reduction of oxidized mercury by sulfite ions. However, in multipollutants simultaneous absorption system, the formation of a large quantity of nitrate and nitrite ions as NOx absorption might also affect the reduction of oxidized mercury in the aqueous absorbent. As such, this paper studied the effects of nitrate and nitrite ions on mercury re-emission and its related mechanism. Experimental results revealed that the nitrate ions had neglected effect on mercury re-emission while the nitrite ions could greatly change the mercury re-emission behaviors. The nitrite ions could initially improve the Hg(0)-emission through the decomposition of HgSO3NO2(-), but with a further increase in the concentration, they would then inhibit the reduction of bivalent mercury owing to the formation of Hg-nitrite complex [Hg(NO2)x(2-x)]. In addition, the subsequent addition of Cl(-) could further suppress the Hg(0) emission, where the formation of a stable Hg-SO3-NO2-Cl complex was assumed to be the main reason for such strong inhibition effect. PMID:25360573

  14. 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

  15. Phytoremediation of ionic and methyl mercury pollution

    SciTech Connect

    Meagher, R.B.

    1998-06-01

    'The long-term objective of the research is to manipulate single-gene traits into plants, enabling them to process heavy metals and remediate heavy-metal pollution by resistance, sequestration, removal, and management of these contaminants. The authors are focused on mercury pollution as a case study of this plant genetic engineering approach. The working hypothesis behind this proposal was that transgenic plants expressing both the bacterial organo mercury lyase (merB) and the mercuric ion reductase gene (merA) will: (A) remove the mercury from polluted sites and (B) prevent methyl mercury from entering the food chain. The results from the research are so positive that the technology will undoubtedly be applied in the very near future to cleaning large mercury contaminates sites. Many such sites were not remediable previously due to the excessive costs and the negative environmental impact of conventional mechanical-chemical technologies. At the time this grant was awarded 20 months ago, the authors had successfully engineered a small model plant, Arabidopsis thaliana, to use a highly modified bacterial mercuric ion reductase gene, merA9, to detoxify ionic mercury (Hg(II)), reducing it to much less toxic and volatile metallic Hg(0) (Rugh et al., 1996). Seeds from these plants germinate, grow, and set seed at normal growth rates on levels of Hg(II) that are lethal to normal plants. In assays on transgenic seedlings suspended in a solution of Hg(II), 10 ng of Hg(0) was evolved per min per mg wet weight of plant tissue. At that time, the authors had no information on expression of merA in any other plant species, nor had the authors tested merB in any plant. However, the results were so startlingly positive and well received that they clearly presaged a paradigm shift in the field of environmental remediation.'

  16. Comparisons of mercury sources and atmospheric mercury processes between a coastal and inland site

    NASA Astrophysics Data System (ADS)

    Cheng, Irene; Zhang, Leiming; Blanchard, Pierrette; Dalziel, John; Tordon, Rob; Huang, Jiaoyan; Holsen, Thomas M.

    2013-03-01

    Comparisons of mercury sources and atmospheric mercury processes were conducted between a coastal and inland site in northeastern North America. Identifying sources of atmospheric Hg is essential for understanding what is potentially contributing to Hg bioaccumulation at these two sites. A data set consisting of gaseous elemental mercury (GEM), gaseous oxidized mercury (GOM), particle-bound mercury, ozone, trace gases, particulate ions, and meteorological data were analyzed using principal components analysis (PCA), absolute principal component scores (APCS), and back trajectories. The PCA factors representing gaseous Hg condensation on particles during winter and combustion and industrial sources were found at both sites. However, the PCA factor for combustion/industrial sources was not found in 2010 at either site, likely because of SO2 emissions reductions from coal utilities from 2008 to 2010. Using APCS and back trajectories, the combustion/industrial factor at the coastal site was narrowed down to shipping ports along the Atlantic coast. Hg sources affecting coastal sites are different from those affecting inland sites because of the influence of marine airflows. GEM evasion from the ocean was evident from a PCA factor containing GEM, relative humidity, wind speed, and precipitation along with significantly higher contributions of this source (APCS) from oceanic trajectories compared to land/coastal trajectories. Analysis of the effects of ozone and water vapor mixing ratio on %GOM/total gaseous mercury suggest that Hg-Br photochemistry occurred at lower ozone concentrations (<40 ppb) at the coastal site and the absence of free troposphere transport of GOM.

  17. 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.

  18. 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

  19. Studies on the role of gastrointestinal tract contents in the methylation of inorganic mercury compounds

    SciTech Connect

    Ludwicki, J.K.

    1989-02-01

    The toxic action of the mercury compounds and their bioavailability depends on the chemical structure of the compound. It is well known that mercury compounds can be transformed into metallic mercury or to alkyl mercury compounds in the environment. This transformation caused by microorganisms was observed in the soil and human feces. Therefore, the idea that inorganic mercury ingested in small quantities with daily meals can be partly transformed into alkyl mercury compounds can not be rejected without prior experiments. Result of such studies should be of special importance, because of the exceptionally high toxicity of methylmercury ion (MeHg) and its delayed neurotoxic action especially when in utero exposure is concerned. This study aimed at the investigation of the fate of inorganic mercury compounds influenced by the contents of the gastrointestinal tract.

  20. MESSENGER observations of multiscale Kelvin-Helmholtz vortices at Mercury

    NASA Astrophysics Data System (ADS)

    Gershman, Daniel J.; Raines, Jim M.; Slavin, James A.; Zurbuchen, Thomas H.; Sundberg, Torbjörn; Boardsen, Scott A.; Anderson, Brian J.; Korth, Haje; Solomon, Sean C.

    2015-06-01

    Observations by the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft in Mercury's magnetotail demonstrate for the first time that Na+ ions exert a dynamic influence on Mercury's magnetospheric system. Na+ ions are shown to contribute up to ~30% of the ion thermal pressure required to achieve pressure balance in the premidnight plasma sheet. High concentrations of planetary ions should lead to Na+ dominance of the plasma mass density in these regions. On orbits with northward-oriented interplanetary magnetic field and high (i.e., >1 cm-3) Na+ concentrations, MESSENGER has often recorded magnetic field fluctuations near the Na+ gyrofrequency associated with the Kelvin-Helmholtz (K-H) instability. These nightside K-H vortices are characteristically different from those observed on Mercury's dayside that have a nearly constant wave frequency of ~0.025 Hz. Collectively, these observations suggest that large spatial gradients in the hot planetary ion population at Mercury may result in a transition from a fluid description to a kinetic description of vortex formation across the dusk terminator, providing the first set of truly multiscale observations of the K-H instability at any of the diverse magnetospheric environments explored in the solar system.

  1. 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

  2. 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 ...

  3. Mercury in the environment

    ScienceCinema

    Idaho National Laboratory - Mike Abbott

    2010-01-08

    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

  4. Blood Mercury Level

    EPA Science Inventory

    This indicator describes the presence of mercury in the blood of segments of the U.S. population from 1999 to 2008. Mercury can cause developmental and neurological problems, especially in children. This indicator shows how exposure to this environmental contaminant has change...

  5. MERCURY RESEARCH STRATEGY

    EPA Science Inventory

    The U.S. Environmental Protection Agency's (EPA's) Office of Research and Development (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 ...

  6. Mercury On Deck

    NASA Technical Reports Server (NTRS)

    1963-01-01

    The crew of the U.S.S. Kearsarge spell out the words 'Mercury 9' on the ship's flight deck while on the way to the recovery area where astronaut Gordon Cooper is expected to splash down in his 'Faith 7' Mercury space capsule.

  7. Atmospheric Deposition of Mercury

    EPA Science Inventory

    With the advent of the industrial era, the amount of mercury entering the global environment increased dramatically. Releases of mercury in its elemental form from gold mines and chlor-alkali plants, as sulfides such as mercaptans and agricultural chemicals, and as volatile emiss...

  8. DNA-capped mesoporous silica nanoparticles as an ion-responsive release system to determine the presence of mercury in aqueous solutions

    PubMed Central

    Zhang, Yunfei; Yuan, Quan; Chen, Tao; Chen, Yan

    2013-01-01

    We have developed DNA-functionalized silica nanoparticles for the rapid, sensitive, and selective detection of mercuric ion (Hg2+) in aqueous solution. Two DNA strands were designed to cap the pore of dye-trapped silica nanoparticles. In the presence of ppb level Hg2+, the two DNA strands are dehybridized to uncap the pore, releasing the dye cargo with detectable enhancements of fluorescence signal. This method enables rapid (less than 20min) and sensitive (LOD 4ppb) detection, and it was also able to discriminate Hg2+ from twelve other environmentally relevant metal ions. The superior properties of the as-designed DNA-functionalized silica nanoparticles can be attributed to the large loading capacity and highly ordered pore structure of mesoporous silica nanoparticles, as well as the selective binding of thymine-rich DNA with Hg2+ . Our design serves as a new prototype for metal-ion sensing systems and it also has promising potential for detection of various targets in stimulus-release systems. PMID:22240146

  9. MESSENGER at Mercury: Early Orbital Operations

    NASA Technical Reports Server (NTRS)

    McNutt, Ralph L., Jr; Solomon, Sean C.; Bedini, Peter D.; Anderson, Brian J.; Blewett, David T.; Evans, Larry G.; Gold, Robert E.; Krimigis, Stamatios M.; Murchie, Scott L.; Nittler, Larry R.; Philips, Roger J.; Prockter, Louise M.; Slavin, James A.; Zuber, M. T.; Finnegan, Eric J.; Grant, David G.

    2013-01-01

    angles. Targeted areas have been selected for spectral coverage into the ultraviolet with the Ultraviolet and Visible Spectrometer (UVVS). MESSENGER's Mercury Laser Altimeter is acquiring topographic profiles when the slant range to Mercury's surface is less than 1800 km, encompassing latitudes from 20 deg. S to the north pole. Topography over the remainder of the southern hemisphere will be derived from stereo imaging, radio occultations, and limb profiles. MESSENGER's radio science experiment is determining Mercury's gravity field from Doppler signals acquired during frequent downlinks. MESSENGER's Magnetometer is measuring the vector magnetic field both within Mercury's magnetosphere and in Mercury's solar wind environment at an instrument sampling rate of up to 20 samples/s. The UVVS is determining the three-dimensional, time-dependent distribution of Mercury's exospheric neutral and ionic species via their emission lines. During each spacecraft orbit, the Energetic Particle Spectrometer measures energetic electrons and ions, and the Fast Imaging Plasma Spectrometer measures the energies and mass per charge of thermal plasma components, both within Mercury's magnetosphere and in Mercury's solar-wind environment. The primary mission observation sequence will continue for one Earth year, until March 2012. An extended mission, currently under discussion with NASA, would add a second year of orbital observations targeting a set of focused follow-on questions that build on observations to date and take advantage of the more active Sun expected during 2012-2013. MESSENGER's total primary mission cost, projected at $446 M in real-year dollars, is comparable to that of Mariner 10 after adjustment for inflation.

  10. MESSENGER at Mercury: Early Orbital Operations

    NASA Technical Reports Server (NTRS)

    McNutt, Ralph L., Jr.; Solomon, Sean C.; Bedini, Peter D.; Anderson, Brian J.; Blewett, David T.; Evans, Larry G.; Gold, Robert E.; Krimigis, Stamatios M.; Murchie, Scott L.; Nittler, Larry R.; Slavin, James A.

    2012-01-01

    . Targeted areas have been selected for spectral coverage into the ultraviolet with the Ultraviolet and Visible Spectrometer (UVVS). MESSENGER's Mercury Laser Altimeter is acquiring topographic profiles when the slant range to Mercury's surface is less than 1800 km, encompassing latitudes from 201S to the north pole. Topography over the remainder of the southern hemisphere will be derived from stereo imaging, radio occultations, and limb profiles. MESSENGER's radio science experiment is determining Mercury's gravity field from Doppler signals acquired during frequent downlinks. MESSENGER's Magnetometer is measuring the vector magnetic field both within Mercury's magnetosphere and in Mercury's solar wind environment at an instrument sampling rate of up to 20 samples/s. The UVVS is determining the three-dimensional, time-dependent distribution of Mercury's exospheric neutral and ionic species via their emission lines. During each spacecraft orbit, the Energetic Particle Spectrometer measures energetic electrons and ions, and the Fast Imaging Plasma Spectrometer measures the energies and mass per charge of thermal plasma components, both within Mercury's magnetosphere and in Mercury's solar-wind environment. The primary mission observation sequence will continue for one Earth year, until March 2012. An extended mission, currently under discussion with NASA, would add a second year of orbital observations targeting a set of focused follow-on questions that build on observations to date and take advantage of the more active Sun expected during 2012-2013. MESSENGER's total primary mission cost, projected at $446 M in real-year dollars, is comparable to that of Mariner 10 after adjustment for inflation.

  11. MESSENGER at Mercury: Early orbital operations

    NASA Astrophysics Data System (ADS)

    McNutt, Ralph L.; Solomon, Sean C.; Bedini, Peter D.; Anderson, Brian J.; Blewett, David T.; Evans, Larry G.; Gold, Robert E.; Krimigis, Stamatios M.; Murchie, Scott L.; Nittler, Larry R.; Phillips, Roger J.; Prockter, Louise M.; Slavin, James A.; Zuber, Maria T.; Finnegan, Eric J.; Grant, David G.; MESSENGER Team

    2014-01-01

    angles. Targeted areas have been selected for spectral coverage into the ultraviolet with the Ultraviolet and Visible Spectrometer (UVVS). MESSENGER's Mercury Laser Altimeter is acquiring topographic profiles when the slant range to Mercury's surface is less than 1800 km, encompassing latitudes from 20°S to the north pole. Topography over the remainder of the southern hemisphere will be derived from stereo imaging, radio occultations, and limb profiles. MESSENGER's radio science experiment is determining Mercury's gravity field from Doppler signals acquired during frequent downlinks. MESSENGER's Magnetometer is measuring the vector magnetic field both within Mercury's magnetosphere and in Mercury's solar wind environment at an instrument sampling rate of up to 20 samples/s. The UVVS is determining the three-dimensional, time-dependent distribution of Mercury's exospheric neutral and ionic species via their emission lines. During each spacecraft orbit, the Energetic Particle Spectrometer measures energetic electrons and ions, and the Fast Imaging Plasma Spectrometer measures the energies and mass per charge of thermal plasma components, both within Mercury's magnetosphere and in Mercury's solar-wind environment. The primary mission observation sequence will continue for one Earth year, until March 2012. An extended mission, currently under discussion with NASA, would add a second year of orbital observations targeting a set of focused follow-on questions that build on observations to date and take advantage of the more active Sun expected during 2012-2013. MESSENGER's total primary mission cost, projected at $446 M in real-year dollars, is comparable to that of Mariner 10 after adjustment for inflation.

  12. Getting rid of mercury

    SciTech Connect

    Reisch, M.S.

    2008-11-24

    Anticipating a US rule on mercury removal from coal flue gas, technology providers jockey for position. By 2013, if the federal rule imposing regulation of mercury emissions which have begun or are about to begin in 20 eastern states goes nationwide, mercury control will be big business. For the near term, utilities are adopting activated carbon to control mercury emissions. McIlvaine Co. projects the US market for activated carbon will jump from 10 million lb in 2010 to 350 million by 2013. Norit and Calgon Carbon are already increasing production of activated carbon (mainly from coal) and ADA Environmental Solutions (ADA-ES) is building a new plant. Albermarle is developing a process to treat activated carbon with bromine; Corning has developed a sulfur impregnated activated carbon filtration brick. New catalysts are being developed to improve the oxidation of mercury for removal from flue gas. 2 photos.

  13. 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…

  14. MERCURY MULTI-YEAR PLAN

    EPA Science Inventory

    A 1997 EPA Mercury Study Report to Congress discussed the magnitude of mercury emissions in the United States, and concluded that a plausible link exists between human activities that release mercury from industrial and combustion sources in the United States and methyl mercury c...

  15. Integrity Monitoring of Mercury Discharge Lamps

    NASA Technical Reports Server (NTRS)

    Tjoelker, Robert L.

    2010-01-01

    Mercury discharge lamps are critical in many trapped ion frequency standard applications. An integrity monitoring system can be implemented using end-of-life signatures observed in operational mercury discharge lamps, making it possible to forecast imminent failure and to take action to mitigate the consequences (such as switching to a redundant system). Mercury lamps are used as a source of 194-nm ultraviolet radiation for optical pumping and state selection of mercury trapped ion frequency standards. Lamps are typically fabricated using 202Hg distilled into high-purity quartz, or other 194-nm transmitting material (e.g., sapphire). A buffer gas is also placed into the bulb, typically a noble gas such as argon, neon, or krypton. The bulbs are driven by strong RF fields oscillating at .200 MHz. The lamp output may age over time by two internal mechanisms: (1) the darkening of the bulb that attenuates light transmission and (2) the loss of mercury due to migration or chemical interactions with the bulb surface. During fabrication, excess mercury is placed into a bulb, so that the loss rate is compensated with new mercury emanating from a cool tip or adjacent reservoir. The light output is nearly constant or varies slightly at a constant rate for many months/years until the mercury source is depleted. At this point, the vapor pressure abruptly falls and the total light output and atomic clock SNR (signal-to-noise ratio) decrease. After several days to weeks, the light levels decrease to a point where the atomic clock SNR is no longer sufficient to stay in lock, or the lamp self-extinguishes. This signature has been observed in four separate end-of-life lamp failures while operating in the Deep Space Network (DSN). A simple integrator circuit can observe and document steady-state lamp behavior. When the light levels drop over a predetermined time interval by a specified amount (e.g., 20 percent), an alarm is set. For critical operational applications, such as the DSN

  16. Fluorescence turn-on detection of mercury ions based on the controlled adsorption of a perylene probe onto the gold nanoparticles.

    PubMed

    Li, Juanmin; Chen, Jian; Chen, Yang; Li, Yongxin; Shahzad, Sohail Anjum; Wang, Yan; Yang, Meiding; Yu, Cong

    2016-01-01

    A novel fluorescence turn-on strategy based on Au nanoparticles and a perylene probe for the sensing of Hg(2+) ions has been developed. It was observed that a perylene probe could be adsorbed onto the surface of Au NPs through strong electrostatic and hydrophobic interactions. Its fluorescence was efficiently quenched by the Au nanoparticles. However, in the presence of Hg(2+) and NaBH4, Hg(2+) was reduced and an Au/Hg amalgam was formed on the surface of the Au nanoparticles. The perylene probe could hardly be adsorbed and quenched by the Au/Hg amalgam. A turn on fluorescence signal was therefore detected. The assay is quite sensitive, and 5 nM Hg(2+) could be easily detected. It is also very selective, a number of metal ions were tested and no noticeable interference was observed. The assay was also successfully applied for the determination of Hg(2+) in lake water samples. A simple, fast, inexpensive, highly sensitive and selective Hg(2+) sensing strategy is therefore established. PMID:26618370

  17. 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

  18. 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.

  19. 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

  20. 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.

  1. Inhalation uptake of low level elemental mercury vapor and its tissue distribution in rats

    SciTech Connect

    Oberski, S.P.; Fang, S.C.

    1980-07-01

    Elemental mercury vapor is the major component of mercury found in the atmosphere. Furthermore, if usage of coal is increased to meet the energy demand, then atmospheric levels of mercury are expected to rise. Current atmospheric concentrations of mercury vapor over select urban areas of the United States range from 0.5 to 50 ng m/sup -3/ with a mean of 7 ng m/sup -3/. Mercury concentration in brain tissue following inhalation of elemental mercury is significantly higher than those from intravenous injection or oral administration of either organic or ionic mercurials. Although elemental mercury is rapidly oxidized in the blood to the less diffusable mercuric ion, the transient occurrence of elemental mercury in the blood stream and the increased levels detected in the central nervous system are likely a result of its rapid diffusion into target tissues. This study reports the inhalation uptake and consequent tissue distribution of radioactive elemental mercury vapor in rats over a concentration range of 15 to 916 ng m/sup -3/, with particular emphasis on measurement below 50 ng m/sup -3/, in an effort to determine if the tissue distribution of mercury after a low level exposure is similar to those reported using higher concentrations.

  2. 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

  3. Performance Evaluation of 40 cm Ion Optics for the NEXT Ion Engine

    NASA Technical Reports Server (NTRS)

    Soulas, George C.; Haag, Thomas W.; Patterson, Michael J.

    2002-01-01

    The results of performance tests with two 40 cm ion optics sets are presented and compared to those of 30 cm ion optics with similar aperture geometries. The 40 cm ion optics utilized both NSTAR and TAG (Thick-Accelerator-Grid) aperture geometries. All 40 cm ion optics tests were conducted on a NEXT (NASA's Evolutionary Xenon Thruster) laboratory model ion engine. Ion optics performance tests were conducted over a beam current range of 1.20 to 3.52 A and an engine input power range of 1.1 to 6.9 kW. Measured ion optics' performance parameters included near-field radial beam current density profiles, impingement-limited total voltages, electron backstreaming limits, screen grid ion transparencies, beam divergence angles, and start-up transients. Impingement-limited total voltages for 40 cm ion optics with the NSTAR aperture geometry were 60 to 90 V lower than those with the TAG aperture geometry. This difference was speculated to be due to an incomplete burn-in of the TAG ion optics. Electron backstreaming limits for the 40 cm ion optics with the TAG aperture geometry were 8 to 19 V higher than those with the NSTAR aperture geometry due to the thicker accelerator grid of the TAG geometry. Because the NEXT ion engine provided beam flatness parameters that were 40 to 63 percent higher than those of the NSTAR ion engine, the 40 cm ion optics outperformed the 30 cm ion optics.

  4. 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.

  5. Missions to Mercury

    NASA Astrophysics Data System (ADS)

    Grard, Réjean; Laakso, Harry; Svedhem, Håkan

    2002-10-01

    Mercury is a poorly known planet. It is difficult to observe from Earth and to explore with spacecraft, due to its proximity to the Sun. Only the NASA probe Mariner 10 caught a few glimpses of Mercury during three flybys, more than 27 years ago. Still, this planet is an interesting and important object because it belongs, like our own Earth, to the family of the terrestrial planets. After reviewing what we know about Mercury and recapitulating the major findings of Mariner 10, we present the two missions, Messenger and BepiColombo, which will perform the first systematic exploration of this forgotten planet in 2009 and 2014, respectively.

  6. Operating Characteristics of a 15-cm dia. Ion Engine for Small Planetary Spacecraft

    NASA Technical Reports Server (NTRS)

    Brophy, J. R.; Pless, L. C.; Mueller, J.; Anderson, J.

    1993-01-01

    A 15-cm diameter, scaled-down version of the NASA light-weight 30-cm ion engine has been developed for potential application to very small planetary spacecraft. Integration of the 15-cm ion source into 4x15-cm segmented engine configuration results in a 30-cm equivalent engine which can be throttled over a 7-to-1 input power variation with a constant beam current in each of the four segments. Throttling the segmented engine by turning off individual segments can result in a significant decrease in the required service life (and qualification requirements) of the ion source components.

  7. Mercury cycling in terrestrial watersheds

    USGS Publications Warehouse

    Shanley, James B.; Bishop, Kevin

    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.

  8. Mercury heavy-metal-induced physiochemical changes and genotoxic alterations in water hyacinths [Eichhornia crassipes (Mart.)].

    PubMed

    Malar, Srinivasan; Sahi, Shivendra Vikram; Favas, Paulo J C; Venkatachalam, Perumal

    2015-03-01

    Mercury heavy metal pollution has become an important environmental problem worldwide. Accumulation of mercury ions by plants may disrupt many cellular functions and block normal growth and development. To assess mercury heavy metal toxicity, we performed an experiment focusing on the responses of Eichhornia crassipes to mercury-induced oxidative stress. E. crassipes seedlings were exposed to varying concentrations of mercury to investigate the level of mercury ions accumulation, changes in growth patterns, antioxidant defense mechanisms, and DNA damage under hydroponics system. Results showed that plant growth rate was significantly inhibited (52 %) at 50 mg/L treatment. Accumulation of mercury ion level were 1.99 mg/g dry weight, 1.74 mg/g dry weight, and 1.39 mg/g dry weight in root, leaf, and petiole tissues, respectively. There was a decreasing trend for chlorophyll a, b, and carotenoids with increasing the concentration of mercury ions. Both the ascorbate peroxidase and malondialdehyde contents showed increased trend in leaves and roots up to 30 mg/L mercury treatment and slightly decreased at the higher concentrations. There was a positive correlation between heavy metal dose and superoxide dismutase, catalase, and peroxidase antioxidative enzyme activities which could be used as biomarkers to monitor pollution in E. crassipes. Due to heavy metal stress, some of the normal DNA bands were disappeared and additional bands were amplified compared to the control in the random amplified polymorphic DNA (RAPD) profile. Random amplified polymorphic DNA results indicated that genomic template stability was significantly affected by mercury heavy metal treatment. We concluded that DNA changes determined by random amplified polymorphic DNA assay evolved a useful molecular marker for detection of genotoxic effects of mercury heavy metal contamination in plant species. PMID:25323404

  9. Mercury's Caloris Basin

    NASA Technical Reports Server (NTRS)

    2001-01-01

    Mercury: Computer Photomosaic of the Caloris Basin

    The largest basin on Mercury (1300 km or 800 miles across) was named Caloris (Greek for 'hot') because it is one of the two areas on the planet that face the Sun at perihelion.

    The Image Processing Lab at NASA's Jet Propulsion Laboratory produced this photomosaic using computer software and techniques developed for use in processing planetary data. The Mariner 10 spacecraft imaged the region during its initial flyby of the planet.

    The Mariner 10 spacecraft was launched in 1974. The spacecraft took images of Venus in February 1974 on the way to three encounters with Mercury in March and September 1974 and March 1975. The spacecraft took more than 7,000 images of Mercury, Venus, the Earth and the Moon during its mission.

    The Mariner 10 Mission was managed by the Jet Propulsion Laboratory for NASA's Office of Space Science in Washington, D.C.

  10. A highly sensitive label-free sensor for Mercury ion (Hg²⁺) by inhibiting thioflavin T as DNA G-quadruplexes fluorescent inducer.

    PubMed

    Ge, Jia; Li, Xi-Ping; Jiang, Jian-Hui; Yu, Ru-Qin

    2014-05-01

    DNA sequences with guanine repeats can be induced to form G-quartets that adopt G-quadruplex structures in the presence of thioflavin T (ThT). ThT plays a dual role of inducing DNA sequences to fold into quadruplex structures and of sensing the change by its remarkable fluorescence enhancement. ThT binding to the DNA sequences with guanine repeats showed highly specific fluorescence enhancement compared with single/double-stranded DNA. In this work, we have utilized the conformational switch from G-quadruplex complex induced by fluorogenic dye ThT to Hg(2+) mediated T-Hg-T double-stranded DNA formation, thereby pioneering a facile approach to detect Hg(2+) with fluorescence spectrometry. Through this approach, Hg(2+) in aqueous solutions can be detected at 5 nM with fluorescence spectrometry in a facile way, with high selectivity against other metal ions. These results indicate the introduced label-free method for fluorescence spectrometric Hg(2+) detection is simple, quantitative, sensitive, and highly selective. PMID:24720966

  11. 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.

  12. Mercury iodide crystal growth

    NASA Technical Reports Server (NTRS)

    Cadoret, R.

    1982-01-01

    The purpose of the Mercury Iodide Crystal Growth (MICG) experiment is the growth of near-perfect single crystals of mercury Iodide (HgI2) in a microgravity environment which will decrease the convection effects on crystal growth. Evaporation and condensation are the only transformations involved in this experiment. To accomplish these objectives, a two-zone furnace will be used in which two sensors collect the temperature data (one in each zone).

  13. 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

  14. Mercury's Surface Magnetic Field Determined from Proton-Reflection Magnetometry

    NASA Technical Reports Server (NTRS)

    Winslow, Reka M.; Johnson, Catherine L.; Anderson, Brian J.; Gershman, Daniel J.; Raines, Jim M.; Lillis, Robert J.; Korth, Haje; Slavin, James A.; Solomon, Sean C.; Zurbuchen, Thomas H.; Zuber, Maria T.

    2014-01-01

    Solar wind protons observed by the MESSENGER spacecraft in orbit about Mercury exhibit signatures of precipitation loss to Mercury's surface. We apply proton-reflection magnetometry to sense Mercury's surface magnetic field intensity in the planet's northern and southern hemispheres. The results are consistent with a dipole field offset to the north and show that the technique may be used to resolve regional-scale fields at the surface. The proton loss cones indicate persistent ion precipitation to the surface in the northern magnetospheric cusp region and in the southern hemisphere at low nightside latitudes. The latter observation implies that most of the surface in Mercury's southern hemisphere is continuously bombarded by plasma, in contrast with the premise that the global magnetic field largely protects the planetary surface from the solar wind.

  15. A screening-level mercury deposition model for wetland ecosystems

    SciTech Connect

    Fink, L.E.

    1995-12-31

    A highly aggregated, three-compartment, carbon cycling model was constructed for a screening-level simulation of net carbon, phosphorus, and mercury deposition in the Everglades Nutrient Removal Project, a 3,742-acre constructed wetland in South Florida. The model was initialized using ENR or Everglades values for model variables. The model was calibrated to calculate biomass turnover, decomposition, and release rates that reproduced the observed apparent phosphorus settling rate constant and the observed organic and inorganic carbon and total phosphorus concentrations in surface sediments. The mercury deposition rate was calculated by partitioning water column mercuric ion onto settling organic and inorganic carbon particles using site-specific or literature values for partition coefficients. From the annual mass balance budget for total mercury calculated with site-specific or literature values, the phosphorus-calibrated model reproduced the observed total mercury concentrations in surface sediments from a typical Everglades marsh within screening-level tolerances.

  16. 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.

  17. Catalytic Reactor For Oxidizing Mercury Vapor

    DOEpatents

    Helfritch, Dennis J.

    1998-07-28

    A catalytic reactor (10) for oxidizing elemental mercury contained in flue gas is provided. The catalyst reactor (10) comprises within a flue gas conduit a perforated corona discharge plate (30a, b) having a plurality of through openings (33) and a plurality of projecting corona discharge electrodes (31); a perforated electrode plate (40a, b, c) having a plurality of through openings (43) axially aligned with the through openings (33) of the perforated corona discharge plate (30a, b) displaced from and opposing the tips of the corona discharge electrodes (31); and a catalyst member (60a, b, c, d) overlaying that face of the perforated electrode plate (40a, b, c) opposing the tips of the corona discharge electrodes (31). A uniformly distributed corona discharge plasma (1000) is intermittently generated between the plurality of corona discharge electrode tips (31) and the catalyst member (60a, b, c, d) when a stream of flue gas is passed through the conduit. During those periods when corona discharge (1000) is not being generated, the catalyst molecules of the catalyst member (60a, b, c, d) adsorb mercury vapor contained in the passing flue gas. During those periods when corona discharge (1000) is being generated, ions and active radicals contained in the generated corona discharge plasma (1000) desorb the mercury from the catalyst molecules of the catalyst member (60a, b, c, d), oxidizing the mercury in virtually simultaneous manner. The desorption process regenerates and activates the catalyst member molecules.

  18. Discovery of calcium in Mercury's atmosphere.

    PubMed

    Bida, T A; Killen, R M; Morgan, T H

    2000-03-01

    The composition and evolutionary history of Mercury's crust are not well determined. The planet as a whole has been predicted to have a refractory, anhydrous composition: rich in Ca, Al, Mg and Fe, but poor in Na, K, OH, and S. Its atmosphere is believed to be derived in large part from the surface materials. A combination of effects that include impact vaporization (from infalling material), volatile evaporation, photon-stimulated desorption and sputtering releases material from the surface to form the atmosphere. Sodium and potassium have already been observed in Mercury's atmosphere, with abundances that require a volatile-rich crust. The sodium probably results from photon-stimulated desorption, and has a temperature of 1,500 K (ref. 10). Here we report the discovery of calcium in the atmosphere near Mercury's poles. The column density is very low and the temperature is apparently very high (12,000 K). The localized distribution and high temperature, if confirmed, suggest that the atmospheric calcium may arise from surface sputtering by ions, which enter Mercury's auroral zone. The low abundance of atmospheric Ca may indicate that the regolith is rarefied in calcium. PMID:10724161

  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. Determination of methylmercury and inorganic mercury by coupling short-column ion chromatographic separation, on-line photocatalyst-assisted vapor generation, and inductively coupled plasma mass spectrometry.

    PubMed

    Chen, Kuan-ju; Hsu, I-hsiang; Sun, Yuh-chang

    2009-12-18

    We have combined short-column ion chromatographic separation and on-line photocatalyst-assisted vapor generation (VG) techniques with inductively coupled plasma mass spectrometry to develop a simple and sensitive hyphenated method for the determination of aqueous Hg(2+) and MeHg(+) species. The separation of Hg(2+) and MeHg(+) was accomplished on a cation-exchange guard column using a glutathione (GSH)-containing eluent. To achieve optimal chromatographic separation and signal intensities, we investigated the influence of several of the operating parameters of the chromatographic and photocatalyst-assisted VG systems. Under the optimized conditions of VG process, the shortcomings of conventional SnCl(2)-based VG techniques for the vaporization of MeHg(+) was overcome; comparing to the concentric nebulizer-ICP-MS system, the analytical sensitivity of ICP-MS toward the detection of Hg(2+) and MeHg(+) were also improved to 25- and 7-fold, respectively. With the use of our established HPLC-UV/nano-TiO(2)-ICP-MS system, the precision for each analyte, based on three replicate injections of 2 ng/mL samples of each species, was better than 15% RSD. This hyphenated method also provided excellent detection limits--0.1 and 0.03 ng/mL for Hg(2+) and MeHg(+), respectively. A series of validation experiments--analysis of the NIST 2672a Standard Urine Reference Material and other urine samples--confirmed further that our proposed method could be applied satisfactorily to the determination of inorganic Hg(2+) and MeHg(+) species in real samples. PMID:19913233

  2. Why mercury prefers soft ligands

    SciTech Connect

    Riccardi, Demian M; Guo, Hao-Bo; Gu, Baohua; Parks, Jerry M; Summers, Anne; Miller, S; Liang, Liyuan; Smith, Jeremy C

    2013-01-01

    Mercury (Hg) is a major global pollutant arising from both natural and anthropogenic sources. Defining the factors that determine the relative affinities of different ligands for the mercuric ion, Hg2+, is critical to understanding its speciation, transformation, and bioaccumulation in the environment. Here, we use quantum chemistry to dissect the relative binding free energies for a series of inorganic anion complexes of Hg2+. Comparison of Hg2+ ligand interactions in the gaseous and aqueous phases shows that differences in interactions with a few, local water molecules led to a clear periodic trend within the chalcogenide and halide groups and resulted in the well-known experimentally observed preference of Hg2+ for soft ligands such as thiols. Our approach establishes a basis for understanding Hg speciation in the biosphere.

  3. 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...

  4. Current approaches of the management of mercury poisoning: need of the hour

    PubMed Central

    2014-01-01

    Mercury poisoning cases have been reported in many parts of the world, resulting in many deaths every year. Mercury compounds are classified in different chemical types such as elemental, inorganic and organic forms. Long term exposure to mercury compounds from different sources e.g. water, food, soil and air lead to toxic effects on cardiovascular, pulmonary, urinary, gastrointestinal, neurological systems and skin. Mercury level can be measured in plasma, urine, feces and hair samples. Urinary concentration is a good indicator of poisoning of elemental and inorganic mercury, but organic mercury (e.g. methyl mercury) can be detected easily in feces. Gold nanoparticles (AuNPs) are a rapid, cheap and sensitive method for detection of thymine bound mercuric ions. Silver nanoparticles are used as a sensitive detector of low concentration Hg2+ ions in homogeneous aqueous solutions. Besides supportive therapy, British anti lewisite, dimercaprol (BAL), 2,3-dimercaptosuccinic acid (DMSA. succimer) and dimercaptopropanesulfoxid acid (DMPS) are currently used as chelating agents in mercury poisoning. Natural biologic scavengers such as algae, azolla and other aquatic plants possess the ability to uptake mercury traces from the environment. PMID:24888360

  5. Current approaches of the management of mercury poisoning: need of the hour.

    PubMed

    Rafati-Rahimzadeh, Mehrdad; Rafati-Rahimzadeh, Mehravar; Kazemi, Sohrab; Moghadamnia, Ali Akbar

    2014-01-01

    Mercury poisoning cases have been reported in many parts of the world, resulting in many deaths every year. Mercury compounds are classified in different chemical types such as elemental, inorganic and organic forms. Long term exposure to mercury compounds from different sources e.g. water, food, soil and air lead to toxic effects on cardiovascular, pulmonary, urinary, gastrointestinal, neurological systems and skin. Mercury level can be measured in plasma, urine, feces and hair samples. Urinary concentration is a good indicator of poisoning of elemental and inorganic mercury, but organic mercury (e.g. methyl mercury) can be detected easily in feces. Gold nanoparticles (AuNPs) are a rapid, cheap and sensitive method for detection of thymine bound mercuric ions. Silver nanoparticles are used as a sensitive detector of low concentration Hg2+ ions in homogeneous aqueous solutions. Besides supportive therapy, British anti lewisite, dimercaprol (BAL), 2,3-dimercaptosuccinic acid (DMSA. succimer) and dimercaptopropanesulfoxid acid (DMPS) are currently used as chelating agents in mercury poisoning. Natural biologic scavengers such as algae, azolla and other aquatic plants possess the ability to uptake mercury traces from the environment. PMID:24888360

  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. Evaluation of Crystalline Silicotitanate and Self-Assembled Monolayers on Mesoporous Support for Cesium and Mercury Removal from DWPF Recycle

    SciTech Connect

    Oji, L.N.

    1999-11-05

    The affinities for cesium and mercury ions contained in DWPF recycle simulants and Tank-22H waste have been evaluated using Crystalline Silicotitanate (CST) and Self-Assembled Monolayers on Mesoporous Support (SAMMS) ion-exchange materials, respectively. Results of the performance evaluations of CST on the uptake of cesium with simulants and actual DWPF recycle samples (Tank 22H) indicate that, in practice, this inorganic ion-exchange material can be used to remove radioactive cesium from the DWPF recycle. SAMMS material showed little or no affinity for mercury from highly alkaline DWPF waste. However, at near neutral conditions (DWPF simulant solution pH adjusted to 7), SAMMS was found to have a significant affinity for mercury. Conventional Duolite/256 ion exchange material showed an increase in affinity for mercury with increase in DWPF recycle simulant pH. Duolite/256 GT-73 also had a high batch distribution coefficient for mercury uptake from actual Tank 22H waste.

  8. Determination of mercury in fish samples by slurry sampling electrothermal vaporization inductively coupled plasma mass spectrometry

    NASA Astrophysics Data System (ADS)

    Liaw, Ming-Jyh; Jiang, Shiuh-Jen; Li, Yi-Ching

    1997-06-01

    Ultrasonic slurry sampling electrothermal vaporization inductively coupled plasma mass spectrometry (USS-ETV-ICP-MS) has been applied to the determination of mercury in several fish samples. The effects of instrument operating conditions and slurry preparation on the ion signals are reported. Palladium was used as modifier to delay the vaporization of mercury in this study. As the vaporization behavior of mercury in fish slurry and aqueous solution is quite different, the standard addition method was used for the determination of mercury in reference materials. The detection limit of mercury estimated from the standard addition curve was in the range 0.002-0.004 μg g -1 for different samples. This method has been applied to the determination of mercury in dogfish muscle reference material (DORM-1 and DORM-2) and dogfish liver reference material (DOLT-1). Accuracy was better than 4% and precision was better than 7% with the USS-ETV-ICP-MS method.

  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. Current Status of MPPE (Mercury Plasma Particle Experiment) on BepiColombo/MMO

    NASA Astrophysics Data System (ADS)

    Saito, Yoshifumi; Hirahara, Masafumi; Barabash, Stas; Delcourt, Dominique; André, Nicolas; Takashima, Takeshi; Asamura, Kazushi

    2015-04-01

    Mercury's plasma/particle environment has gradually become clear thanks to the new observations made by MESSENGER spacecraft orbiting around Mercury. However, it is also true that many questions will be left unsolved. In order to elucidate the detailed plasma structure and dynamics around Mercury, an orbiter BepiColombo MMO (Mercury Magnetospheric Orbiter) is going to be launched in 2016 as a joint mission between ESA and ISAS/JAXA. Mercury Plasma/Particle Experiment (MPPE) is a comprehensive instrument package for plasma, high-energy particle and energetic neutral atom measurements. It consists of 7 sensors: two Mercury Electron Analyzers (MEA1 and MEA2), Mercury Ion Analyzer (MIA), Mass Spectrum Analyzer (MSA), High Energy Particle instrument for electron (HEP-ele), High Energy Particle instrument for ion (HEP-ion), and Energetic Neutrals Analyzer (ENA). Currently, the MPPE sensors are on the MMO spacecraft under system integration test at ISAS/JAXA (Institute of Space and Astronautical Science / Japan Aerospace Exploration Agency). Evaluation of the sensor calibration data and the final check of the onboard processing software are being made in order to realize the flawless future plasma/particle observations around Mercury.

  11. 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.

  12. Biogeochemistry: Better living through mercury

    NASA Astrophysics Data System (ADS)

    Schaefer, Jeffra K.

    2016-02-01

    Mercury is a toxic element with no known biological function. Laboratory studies demonstrate that mercury can be beneficial to microbial growth by acting as an electron acceptor during photosynthesis.

  13. Ninety six well laboratory and field techniques for the analysis of mercury

    SciTech Connect

    Kido, H.; Wengatz, I.; Szurdoki, F.; Hammock, B.

    1994-12-31

    Because of its toxicity, the presence of mercury in the environment is of significant concern. Traditional instrumental methods, such as cold vapor atomic absorption spectrometry, have so far filled the need for mercury environmental analysis. However, less expensive methods that simplify sample preparation and analyze multiple samples simultaneously would facilitate environmental mercury monitoring. ELISA technology and related methods have the potential to do this. An ELISA for the detection of mercury has already been described by Wylie et al. The authors have developed an alternative method which combines low-cost enzyme amplification methodology with the highly sensitive and selective chemical detection of mercuric ions by sulfur-containing ligands; instead of antibodies. In preliminary experiments, high sensitivity for mercuric ions has been achieved, with interferences by only a few other metals. Some aspects of assay development and the application of this technology for the analysis of mercury in environmental samples will be presented.

  14. Separation of mercury from aqueous mercuric chloride solutions by onion skins

    SciTech Connect

    Asai, S.; Konishi, Y.; Tomisaki, H.; Nakanishi, M.

    1986-01-01

    The separation of mercury from aqueous HgCl/sub 2/ solutions by onion skins (outermost coat) was studied both experimentally and theoretically. The distribution equilibria were measured by the batchwise method. The experimental results revealed that onion skin is a useful material for separating mercury from aqueous systems. The distribution data obtained at 25/sup 0/C were analyzed by using the theory based on the law of mass action. The separation of dissolved mercury by onion skins was found to be a process accompanied by an ion-exchange reaction of the cationic complex HgCl/sup +/ and an adsorption of the neutral complex HgCl/sub 2/. The equilibrium constants of the ion-exchange and adsorption processes at 25/sup 0/C and the mercury-binding capacity of onion skins were determined. Further, it was found that the distribution equilibrium of mercury is comparatively insensitive to temperature.

  15. Evidence for magnetospheric effects on the sodium atmosphere of Mercury

    NASA Astrophysics Data System (ADS)

    Potter, A. E.; Morgan, T. H.

    1990-05-01

    Monochromatic images of Mercury at the sodium D2 emission line showed excess sodium emission in localized regions at high northern and southern latitudes and day-to-day global variations in the distribution of sodium emission. These phenomena support the suggestion that magnetospheric effects could be the cause. Sputtering of surface minerals could produce sodium vapor in polar regions during magnetic substorms, when magnetospheric ions directly impact the surface. Another important process may be the transport of sodium ions along magnetic field lines toward polar regions, where they impact directly on the surface of Mercury and are neutralized to regenerate neutral sodium atoms. Day-to-day variations in planetary sodium distributions could result from changing solar activity, which can change the magnetosphere in time scales of a few hours. Observations of the sodium exosphere may provide a tool for remote monitoring of the magnetosphere of Mercury.

  16. Mercury's Atmosphere and Magnetosphere: MESSENGER Third Flyby Observations

    NASA Technical Reports Server (NTRS)

    Slavin, James A.; Anderson, Brian J.; Baker, Daniel N.; Benna, Mehdi; Johnson, Catherine L.; Gloeckler, George; Killen, Rosemary M.; Krimigis, Stamatios M.; McClintock, William; McNutt, Ralph L., Jr.; Schriver, David; Solomon, Sean C.; Sprague, Ann L.; Vevack, Ronald J., Jr.; Zurbuchen, Thomas H.

    2009-01-01

    MESSENGER's third flyby of Mercury en route to orbit insertion about the innermost planet took place on 29 September 2009. The earlier 14 January and 6 October 2008 encounters revealed that Mercury's magnetic field is highly dipolar and stable over the 35 years since its discovery by Mariner 10; that a structured, temporally variable exosphere extends to great altitudes on the dayside and forms a long tail in the anti-sunward direction; a cloud of planetary ions encompasses the magnetosphere from the dayside bow shock to the downstream magnetosheath and magnetotail; and that the magnetosphere undergoes extremely intense magnetic reconnect ion in response to variations in the interplanetary magnetic field. Here we report on new results derived from observations from MESSENGER's Mercury Atmospheric and Surface Composition Spectrometer (MASCS), Magnetometer (MAG), and Energetic Particle and Plasma Spectrometer (EPPS) taken during the third flyby.

  17. 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.

  18. MESSENGER observations of the composition of Mercury's ionized exosphere and plasma environment.

    PubMed

    Zurbuchen, Thomas H; Raines, Jim M; Gloeckler, George; Krimigis, Stamatios M; Slavin, James A; Koehn, Patrick L; Killen, Rosemary M; Sprague, Ann L; McNutt, Ralph L; Solomon, Sean C

    2008-07-01

    The region around Mercury is filled with ions that originate from interactions of the solar wind with Mercury's space environment and through ionization of its exosphere. The MESSENGER spacecraft's observations of Mercury's ionized exosphere during its first flyby yielded Na+, O+, and K+ abundances, consistent with expectations from observations of neutral species. There are increases in ions at a mass per charge (m/q) = 32 to 35, which we interpret to be S+ and H2S+, with (S+ + H2S+)/(Na+ + Mg+) = 0.67 +/- 0.06, and from water-group ions around m/q = 18, at an abundance of 0.20 +/- 0.03 relative to Na+ plus Mg+. The fluxes of Na+, O+, and heavier ions are largest near the planet, but these Mercury-derived ions fill the magnetosphere. Doubly ionized ions originating from Mercury imply that electrons with energies less than 1 kiloelectron volt are substantially energized in Mercury's magnetosphere. PMID:18599777

  19. Student Exposure to Mercury Vapors.

    ERIC Educational Resources Information Center

    Weber, Joyce

    1986-01-01

    Discusses the problem of mercury vapors caused by spills in high school and college laboratories. Describes a study which compared the mercury vapor levels of laboratories in both an older and a newer building. Concludes that the mercurial contamination of chemistry laboratories presents minimal risks to the students. (TW)

  20. ATMOSPHERIC MERCURY TRANSPORT AND DEPOSITION

    EPA Science Inventory

    The current state of our scientific understanding the mercury cycle tells us that most of the mercury getting into fish comes from atmospheric deposition, but methylation of that mercury in aquatic systems is required for the concentrations in fish to reach harmful levels. We st...

  1. MERCURY IN MARINE LIFE DATABASE

    EPA Science Inventory

    The purpose of the Mercury in Marine Life Project is to organize information on estuarine and marine species so that EPA can better understand both the extent of monitoring for mercury and level of mercury contamination in the biota of coastal environments. This report follows a ...

  2. Reference Atmosphere for Mercury

    NASA Technical Reports Server (NTRS)

    Killen, Rosemary M.

    2002-01-01

    We propose that Ar-40 measured in the lunar atmosphere and that in Mercury's atmosphere is due to current diffusion into connected pore space within the crust. Higher temperatures at Mercury, along with more rapid loss from the atmosphere will lead to a smaller column abundance of argon at Mercury than at the Moon, given the same crustal abundance of potassium. Because the noble gas abundance in the Hermean atmosphere represents current effusion, it is a direct measure of the crustal potassium abundance. Ar-40 in the atmospheres of the planets is a measure of potassium abundance in the interiors, since Ar-40 is a product of radiogenic decay of K-40 by electron capture with the subsequent emission of a 1.46 eV gamma-ray. Although the Ar-40 in the Earth's atmosphere is expected to have accumulated since the late bombardment, Ar-40 in the atmospheres of Mercury and the Moon is eroded quickly by photoionization and electron impact ionization. Thus, the argon content in the exospheres of the Moon and Mercury is representative of current effusion rather than accumulation over the lifetime of the planet.

  3. The sodium exosphere and magnetosphere of Mercury

    NASA Astrophysics Data System (ADS)

    Ip, W.-H.

    1986-05-01

    Following the recent optical discovery of intense sodium D-line emission from Mercury, the scenario of an extended exosphere of sodium and other metallic atoms is explored. It is shown that the strong effect of solar radiation pressure acceleration would permit the escape of Na atoms from Mercury's surface even if they are ejected at a velocity lower than the surface escape velocity. Fast photoionization of the Na atoms is effective in limiting the tailward extension of the sodium exosphere, however. The subsequent loss of the photoions to the magnetosphere could be a significant source of the magnetospheric plasma. The recirculation of the magnetospheric charged particles to the planetary surface could also play an important role in maintaining an extended sodium exosphere as well as a magnetosphere of sputtered metallic ions.

  4. Investigation of mercury thruster isolators. [service life

    NASA Technical Reports Server (NTRS)

    Mantenieks, M. A.

    1973-01-01

    Mercury ion thruster isolator lifetime tests were performed using different isolator materials and geometries. Tests were performed with and without the flow of mercury through the isolators in an oil diffusion pumped vacuum facility and cryogenically pumped bell jar. The onset of leakage current in isolators tested occurred in time intervals ranging from a few hours to many hundreds of hours. In all cases, surface contamination was responsible for the onset of leakage current and subsequent isolator failure. Rate of increase of leakage current and the leakage current level increased approximately exponentially with isolator temperature. Careful attention to shielding techniques and the elimination of sources of metal oxides appear to have eliminated isolator failures as a thruster life limiting mechanism.

  5. Sensing Mercury for Biomedical and Environmental Monitoring

    PubMed Central

    Selid, Paul D.; Xu, Hanying; Collins, E. Michael; Face-Collins, Marla Striped; Zhao, Julia Xiaojun

    2009-01-01

    Mercury is a very toxic element that is widely spread in the atmosphere, lithosphere, and surface water. Concentrated mercury poses serious problems to human health, as bioaccumulation of mercury within the brain and kidneys ultimately leads to neurological diseases. To control mercury pollution and reduce mercury damage to human health, sensitive determination of mercury is important. This article summarizes some current sensors for the determination of both abiotic and biotic mercury. A wide array of sensors for monitoring mercury is described, including biosensors and chemical sensors, while piezoelectric and microcantilever sensors are also described. Additionally, newly developed nanomaterials offer great potential for fabricating novel mercury sensors. Some of the functional fluorescent nanosensors for the determination of mercury are covered. Afterwards, the in vivo determination of mercury and the characterization of different forms of mercury are discussed. Finally, the future direction for mercury detection is outlined, suggesting that nanomaterials may provide revolutionary tools in biomedical and environmental monitoring of mercury. PMID:22346707

  6. Follow that mercury!

    SciTech Connect

    Linero, A.A.

    2008-07-01

    The article discusses one technology option for avoiding release of mercury captured by power plant pollution control equipment in order to render it usable in concrete. This is the use of selective catalytic reduction for NOx control and lime spray dryer absorbers (SDA) for SO{sub 2} control prior to particulate collection by fabric filters. In this scenario all mercury removed is trapped in the fabric filter baghouse. The US EPA did not establish mercury emission limits for existing cement plants in the latest regulation 40 CFR 63, Subpart LLL (December 2006) and was sued by the Portland Cement Association because of the Hg limits established for new kilns and by several states and environmental groups for the lack of limits on existing ones. A full version of this article is available on www.acaa-usa.org/AshatWork.htm. 2 figs.

  7. Water displacement mercury pump

    DOEpatents

    Nielsen, M.G.

    1984-04-20

    A water displacement mercury pump has a fluid inlet conduit and diffuser, a valve, a pressure cannister, and a fluid outlet conduit. The valve has a valve head which seats in an opening in the cannister. The entire assembly is readily insertable into a process vessel which produces mercury as a product. As the mercury settles, it flows into the opening in the cannister displacing lighter material. When the valve is in a closed position, the pressure cannister is sealed except for the fluid inlet conduit and the fluid outlet conduit. Introduction of a lighter fluid into the cannister will act to displace a heavier fluid from the cannister via the fluid outlet conduit. The entire pump assembly penetrates only a top wall of the process vessel, and not the sides or the bottom wall of the process vessel. This insures a leak-proof environment and is especially suitable for processing of hazardous materials.

  8. Mercury radar speckle dynamics

    NASA Astrophysics Data System (ADS)

    Holin, Igor V.

    2010-06-01

    Current data reveal that Mercury is a dynamic system with a core which has not yet solidified completely and is at least partially decoupled from the mantle. Radar speckle displacement experiments have demonstrated that the accuracy in spin-dynamics determination for Earth-like planets can approach 10 -5. The extended analysis of space-time correlation properties of radar echoes shows that the behavior of speckles does not prevent estimation of Mercury's instantaneous spin-vector components to accuracy of a few parts in 10 7. This limit can be reached with more powerful radar facilities and leads to constraining the interior in more detail from effects of spin dynamics, e.g., from observation of the core-mantle interplay through high precision monitoring of the 88-day spin-variation of Mercury's crust.

  9. Water displacement mercury pump

    DOEpatents

    Nielsen, Marshall G.

    1985-01-01

    A water displacement mercury pump has a fluid inlet conduit and diffuser, a valve, a pressure cannister, and a fluid outlet conduit. The valve has a valve head which seats in an opening in the cannister. The entire assembly is readily insertable into a process vessel which produces mercury as a product. As the mercury settles, it flows into the opening in the cannister displacing lighter material. When the valve is in a closed position, the pressure cannister is sealed except for the fluid inlet conduit and the fluid outlet conduit. Introduction of a lighter fluid into the cannister will act to displace a heavier fluid from the cannister via the fluid outlet conduit. The entire pump assembly penetrates only a top wall of the process vessel, and not the sides or the bottom wall of the process vessel. This insures a leak-proof environment and is especially suitable for processing of hazardous materials.

  10. The magnetosphere of Mercury

    NASA Technical Reports Server (NTRS)

    Ness, N. F.

    1976-01-01

    Data on Mercury's magnetosphere and on the plasma, planetomagnetic, and energetic particle environment of the planet obtained in three encounters (Mariner 10 flybys) are compared, and tasks for future research are outlined. The Mercury bow shock and magnetopause are much closer to the planet than the earth counterparts are to the earth. The magnetotail with embedded plasma sheet-field reversal region, global deflection of the solar wind by an intrinsic dipolar magnetic field, variations in solar wind momentum flux, and absence of such features as ionosphere, plasmasphere, and radiation belts, are described. Energetic electrons are accelerated in the magnetotail, however, and the interplanetary magnetic field variations distort Mercury's magnetosphere to produce a southward field associated with substorm-like disturbances.

  11. Mercury Atomic Frequency Standards for Space Based Navigation and Timekeeping

    NASA Technical Reports Server (NTRS)

    Tjoelker, R. L.; Burt, E. A.; Chung, S.; Hamell, R. L.; Prestage, J. D.; Tucker, B.; Cash, P.; Lutwak, R.

    2012-01-01

    A low power Mercury Atomic Frequency Standard (MAFS) has been developed and demonstrated on the path towards future space clock applications. A self contained mercury ion breadboard clock: emulating flight clock interfaces, steering a USO local oscillator, and consuming approx 40 Watts has been operating at JPL for more than a year. This complete, modular ion clock instrument demonstrates that key GNSS size, weight, and power (SWaP) requirements can be achieved while still maintaining short and long term performance demonstrated in previous ground ion clocks. The MAFS breadboard serves as a flexible platform for optimizing further space clock development and guides engineering model design trades towards fabrication of an ion clock for space flight.

  12. Control of mercury pollution.

    PubMed

    Noyes, O R; Hamdy, M K; Muse, L A

    1976-01-01

    When a 203Ng(NO3)2 solution was kept at 25 degrees C in glass or polypropylene containers, 50 and 80% of original radioactivity was adsorbed to the containers' walls after 1 and 4 days, respectively. However, no loss in radioactivity was observed if the solution was supplemented with HgCl as carrier (100 mug Hg2+/ml) and stored in either container for 13 days. When 203Hg2+ was dissolved in glucose basal salt broth with added carrier, levels of 203Hg2+ in solution (kept in glass) decreased to 80 and 70% of original after 1 and 5 days and decreased even more if stored in polypropylene (60 and 40% of original activity after 1 and 4 days, respectively). In the absence of carrier, decreases of 203Hg2+ activities in media stored in either container were more pronounced due to chemisorption (but) not diffusion. The following factors affecting the removal of mercurials from aqueous solution stored in glass were examined: type and concentration of adsorbent (fiber glass and rubber powder); pH; pretreatment of the rubber; and the form of mercury used. Rubber was equally effective in the adsorption of organic and inorganic mercury. The pH of the aqueous 203Hg2+ solution was not a critical factor in the rate of adsorption of mercury by the rubber. In addition, the effect of soaking the rubber in water for 18 hr did not show any statistical difference when compared with nontreated rubber. It can be concluded that rubber is a very effective adsorbent of mercury and, thus, can be used as a simple method for control of mercury pollution. PMID:1549

  13. Mosaic Postcards from Mercury

    NASA Astrophysics Data System (ADS)

    Hallau, K. G.; Chapman, C. R.; Edmonds, J.; Goldstein, J.; Hirshon, B.; Solomon, S. C.; Vanhala, H.; Weir, H. M.; Messenger Education; Public Outreach Team

    2010-12-01

    On its journey to become the first spacecraft to orbit Mercury, NASA’s MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft has followed a trajectory that included three flybys of the innermost planet. During the flybys, images captured by the Mercury Dual Imaging System revealed parts of the planet’s surface never before seen at close range, as well as high-resolution views of craters, crater rays, scarps, faults, and volcanic vents and flows. To help students and teachers better understand this revealing new look at Mercury, the MESSENGER Education and Public Outreach team will share these high-resolution images of Mercury's surface throughout the upcoming Year of the Solar System. By means of an intriguing format that mimics methods used by the MESSENGER team, a series of images printed at large postcard size will each highlight a small "slice" of Mercury, such as a crater or fault. The individual cards can then be pieced together, puzzle-style, on a poster-sized grid to reveal a larger mosaic view of the planet. Each card contains engaging text, the URL for an accompanying website, and coordinates for that region of the planet, helping students understand scientific concepts related to and revealed by MESSENGER's journey. The first set of cards will feature scarps, volcanic plains, the topography of a crater and the composition of its interior units, rayed craters, nested craters, and a deposit produced by explosive volcanic eruptions. Cards will be available for free on the accompanying website, distributed by MESSENGER Educator Fellows, or handed out at meetings, conferences, and workshops.

  14. MESSENGER: Insights Regarding the Relationship between Mercury's Surface and Its Neutral and Ionized Exosphere

    NASA Astrophysics Data System (ADS)

    Sprague, Ann L.; Vervack, R. J.; Killen, R. M.; McClintock, W. E.; Starr, R. D.; Schriver, D.; Trávnícek, P.; Orlando, T. M.; McClain, J. L.; Grieves, G. A.; Boynton, W. V.; Lawrence, D. J.; MESSENGER Team

    2010-10-01

    Measurements by instruments on MESSENGER during the spacecraft's three Mercury flybys have led to discoveries of previously undetected neutral (Mg) and ionized (Ca+) species in Mercury's neutral and ionized exosphere and mapped these and previously known constituents (Na, Ca) on the anti-sunward side of the planet and over the poles. Also, Neutron Spectrometer measurements have indicated neutron absorption consistent with the presence of some combination of Fe, Ti, Sm, and Gd. Another element with a high neutron cross section is Mn. Manganese-bearing pyroxene has been inferred from modeling of Mercury Atmospheric and Surface Composition Spectrometer (MASCS) spectra of Mercury's surface. The total neutron cross section of Mn-bearing clinopyroxene, for example, (294.2 barns), is comparable to that of ilmenite (284.0 barns), and we suggest it as a possible neutron absorber at Mercury. Some ions and neutrals can be released directly from mineral surfaces by electron-stimulated desorption (ESD). Because cross sections of neutrals can be higher than photon-stimulated desorption (PSD) cross sections and because active electron precipitation on both the day and night side of Mercury can produce ESD of ions, at least part of the ionized exosphere is produced directly from surface materials by ESD. The process does not require photoionization of atoms or molecules. One inference is that model assumptions for ion production and magnetospheric- interactions may need to add ESD as another source. ESD experiments and simulations of electron precipitation on Mercury provide support for this suggestion. More laboratory work is required to quantify known, and to discover other, pathways to ion desorption from Mercury's surface. Searches for resonant fluorescent emissions from atoms, molecules and ions (e.g., Mn and S emission line triplets near 280 and 162 nm, respectively) in Mercury's neutral and ionized exosphere during the orbital phase of the MESSENGER mission are planned.

  15. CARBON BED MERCURY EMISSIONS CONTROL FOR MIXED WASTE TREATMENT

    SciTech Connect

    Nick Soelberg; Joe Enneking

    2010-11-01

    Mercury has had various uses in nuclear fuel reprocessing and other nuclear processes, and so is often present in radioactive and mixed (both radioactive and hazardous according tohe Resource Conservation and Recovery Act) wastes. Depending on regulatory requirements, the mercury in the off-gas must be controlled with sometimes very high efficiencies. Compliance to the Hazardous Waste Combustor (HWC) Maximum Achievable Control Technology (MACT) standards can require off-gas mercury removal efficiencies up to 99.999% for thermally treating some mixed waste streams. Several test programs have demonstrated this level of off-gas mercury control using fixed beds of granular sulfur-impregnated activated carbon. Other results of these tests include: (a) The depth of the mercury control mass transfer zone was less than 15-30 cm for the operating conditions of these tests, (b) MERSORB® carbon can sorb Hg up to 19 wt% of the carbon mass, and (c) the spent carbon retained almost all (98 – 99.99%) of the Hg; but when even a small fraction of the total Hg dissolves, the spent carbon can fail the TCLP test when the spent carbon contains high Hg concentrations. Localized areas in a carbon bed that become heated through heat of adsorption, to temperatures where oxidation occurs, are referred to as “bed hot spots.” Carbon bed hot spots must be avoided in processes that treat radioactive and mixed waste. Key to carbon bed hot spot mitigation are (a) designing for sufficient gas velocity, for avoiding gas flow maldistribution, and for sufficient but not excessive bed depth, (b) monitoring and control of inlet gas flowrate, temperature, and composition, (c) monitoring and control of in-bed and bed outlet gas temperatures, and (d) most important, monitoring of bed outlet CO concentrations. An increase of CO levels in the off-gas downstream of the carbon bed to levels about 50-100 ppm higher than the inlet CO concentration indicate CO formation in the bed, caused by carbon bed

  16. Mercury binding on activated carbon

    SciTech Connect

    Bihter Padak; Michael Brunetti; Amanda Lewis; Jennifer Wilcox

    2006-11-15

    Density functional theory has been employed for the modeling of activated carbon (AC) using a fused-benzene ring cluster approach. Oxygen functional groups have been investigated for their promotion of effective elemental mercury binding on AC surface sites. Lactone and carbonyl functional groups yield the highest mercury binding energies. Further, the addition of halogen atoms has been considered to the modeled surface, and has been found to increase the AC's mercury adsorption capacity. The mercury binding energies increase with the addition of the following halogen atoms, F {gt} Cl {gt} Br {gt} I, with the fluorine addition being the most promising halogen for increasing mercury adsorption.

  17. Mercury CEM Calibration

    SciTech Connect

    John Schabron; Joseph Rovani; Mark Sanderson

    2008-02-29

    Mercury continuous emissions monitoring systems (CEMS) are being implemented in over 800 coal-fired power plant stacks. The power industry desires to conduct at least a full year of monitoring before the formal monitoring and reporting requirement begins on January 1, 2009. It is important for the industry to have available reliable, turnkey equipment from CEM vendors. 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 generators are used to calibrate mercury CEMs at power plant sites. The Clean Air Mercury Rule (CAMR) which was published in the Federal Register on May 18, 2005 requires that calibration be performed with NIST-traceable standards (Federal Register 2007). Traceability procedures will be defined by EPA. An initial draft traceability protocol was issued by EPA in May 2007 for comment. In August 2007, EPA issued an interim traceability protocol for elemental mercury generators (EPA 2007). The protocol is based on the actual analysis of the output of each calibration unit at several concentration levels ranging initially from about 2-40 {micro}g/m{sup 3} elemental mercury, and in the future down to 0.2 {micro}g/m{sup 3}, and this analysis will be directly traceable to analyses by NIST. The document is divided into two separate sections. The first deals with the qualification of generators by the vendors for use in mercury CEM calibration. The second describes the procedure that the vendors must use to certify the generator models that meet the qualification specifications. The NIST traceable certification is performance based, traceable to analysis using isotope dilution inductively coupled plasma/mass spectrometry performed by NIST in Gaithersburg, MD. The

  18. Mercury's Sodium Exosphere: Observations during the MESSENGER Orbital Phase

    NASA Technical Reports Server (NTRS)

    Killen, Rosemary M.; Cassidy, Timothy A.; Vervack, Ronald J., Jr.; Burger, Matthew H.; Merkel, Aimee W.; Sarantos, Menelaos; Sprague, Ann L.; McClintock, William E.; Benna, Mehdi; Solomon, Sean C.

    2012-01-01

    The MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft entered into orbit about Mercury on March 18,2011. We now have approximately five Mercury years of data from orbit. Prior to the MESSENGER mission, Mercury's surface-bounded exosphere was known to contain H, He, Na. K, and Ca. The Ultraviolet and Visible Spectrometer (UVVS) began routine orbital observations of both the dayside and nightside exosphere on March 29. 2011, measuring altitude profiles for all previously detected neutral species except for He and K. We focus here on what we have learned about the sodium exosphere: its spatial, seasonal, and sporadic variation. Observations to date permit delineation of the relative roles of photon-stimulated desorption (PSD) and impact vaporization (IV) from seasonal and spatial effects, as well as of the roles of ions both as sputtering agents and in their possible role to enhance the efficiency of PSD. Correlations of Mercury's neutral sodium exosphere with measurements from MESSENGER's Magnetometer (MAG) and Energetic Particle and Plasma Spectrometer (EPPS) provide insight into the roles of ions and electrons. Models incorporating MAG observations provide a basis for identifying the location and area of the surface exposed to solar wind plasma, and EPPS observations reveal episodic populations of energetic electrons in the magnetosphere and the presence of planetary He(+), 0(+), and Na(+),

  19. Mercury removal from aqueous streams utilizing microemulsion liquid membranes

    SciTech Connect

    Larson, K.A.; Wiencek, J.M.

    1994-11-01

    The goal of this work is the removal of mercury ion from wastewater using thermodynamically stable microemulsions as liquid membranes. The research focuses on identification and modeling of the appropriate aqueous and organic phase equilibrium reactions for mercury extraction and stripping, comparison of extraction kinetics between coarse emulsions and microemulsions, and demulsification and recovery of the emulsion components. An oleic acid microemulsion liquid membrane (water-in-oil) containing sulfuric acid as the internal phase reduces the feed phase mercury concentration from 460 mg/l to 0.84 mg/l in a single contacting. This compares favorably with a control extraction (oleic acid/no internal phase) which results in a final concentration of 20 mg/l Hg{sup +2}. Microemulsions can be demulsified using butanol as an additive. The demulsification kinetics are proportional to butanol concentration and temperature and inversely proportional to surfactant concentration. The demulsification rate is second order with respect to water concentration which implies that the rate-limiting step in the process is the rate of internal phase droplet encounters. Proof-of-principle experiments demonstrate the ability to extract mercury ion using microemulsions formulated with recycled organic phase, albeit at a somewhat reduced efficiency. The reduced efficiency is attributed to increased internal phase leakage due to residual butanol in the oil phase. Finally, the cycle is brought around full circle by recovering metallic mercury from the internal phase by electroplating. 27 refs., 11 figs., 1 tab.

  20. Compressibility of Mercury's dayside magnetosphere

    NASA Astrophysics Data System (ADS)

    Zhong, J.; Wan, W. X.; Wei, Y.; Slavin, J. A.; Raines, J. M.; Rong, Z. J.; Chai, L. H.; Han, X. H.

    2015-12-01

    The Mercury is experiencing significant variations of solar wind forcing along its large eccentric orbit. With 12 Mercury years of data from Mercury Surface, Space ENvironment, GEochemistry, and Ranging, we demonstrate that Mercury's distance from the Sun has a great effect on the size of the dayside magnetosphere that is much larger than the temporal variations. The mean solar wind standoff distance was found to be about 0.27 Mercury radii (RM) closer to the Mercury at perihelion than at aphelion. At perihelion the subsolar magnetopause can be compressed below 1.2 RM of ~2.5% of the time. The relationship between the average magnetopause standoff distance and heliocentric distance suggests that on average the effects of the erosion process appears to counter balance those of induction in Mercury's interior at perihelion. However, at aphelion, where solar wind pressure is lower and Alfvénic Mach number is higher, the effects of induction appear dominant.

  1. Mercury and mercury compounds toxicology. (Latest citations from the Life Sciences Collection data base). Published Search

    SciTech Connect

    Not Available

    1992-10-01

    The bibliography contains citations concerning the toxic effects of mercury and mercury compounds on biological systems. Mercury metal, mercury vapors, organic mercury compounds, mercury halides, and other inorganic mercury compounds are discussed. Citations include acute, chronic, environmental, metabolic, and pathological effects; and clinical biochemistry of mercury exposure. Heavy metal pollution and bioaccumulation are referenced in related bibliographies. (Contains 250 citations and includes a subject term index and title list.)

  2. Mercury and mercury compounds toxicology. (Latest citations from the Life Sciences Collection database). Published Search

    SciTech Connect

    Not Available

    1994-04-01

    The bibliography contains citations concerning the toxic effects of mercury and mercury compounds on biological systems. Mercury metal, mercury vapors, organic mercury compounds, mercury halides, and other inorganic mercury compounds are discussed. Citations include acute, chronic, environmental, metabolic, and pathological effects; and clinical biochemistry of mercury exposure. Heavy metal pollution and bioaccumulation are referenced in related bibliographies. (Contains 250 citations and includes a subject term index and title list.)

  3. Plane Mercury librations

    NASA Astrophysics Data System (ADS)

    Barkin, Yu. V.; Ferrandiz, J. M.

    2009-04-01

    Introduction. In 1988 I. Kholin [1] has developed a precision method of determination of parameters of rotation of planets on complex radar-tracking observations on two radio telescopes making base and definitely carried on surface of the Earth. His American colleagues for the period approximately in 4 with small year have executed a series of radar-tracking measurements on a method and I. Kholin's program [2] and have obtained for the specified period 21 values of angular velocity of rotation of this planet [3]. With the help of numerical integration of the equations of rotary motion on the found values they managed to determine with high accuracy the basic dynamic parameter in the theory of Mercury librations (B - A)•Cm = (2.03± 0.12) × 10-4 and the corresponding to it the value of amplitude of the basic librations35"8 ± 2"1. These results have served as convincing arguments for the benefit of the Peale's assumption, that a core of Mercury is liquid, or in partially molten [4]. Authors also managed to obtain for the first time parameters of resonant librations in a longitude which opening from radar observations was predicted earlier [5]. Its amplitude makes about 300", the period is equal approximately to 12 years. In the paper [6] parameters of the perturbed rotational motion have been determined with the help of the analytical theory and with formal using of results of mentioned work [3] on determination of 21 values of angular velocity of Mercury. In result the estimations of amplitudes of forced librations of first five harmonics with the periods: 87.97 d, 43.99 d, 29.33 d, 21.99 d and 17.59 d have been obtained. The appropriate amplitudes make values:34"05 ± 1"27, 3"59 ± 0"13, 0"354 ± 0"013, 0"072 ± 0"003 and 0"016 ± 0"001. The amplitude and the period of free librations of Mercury in a longitude are determined: 290"9 ± 67"0 and 12.37 ± 0.23 yr, consequently. The phase of this variation has made28401 ± 1402. In the paper we construct the similar

  4. Method and apparatus for sampling atmospheric mercury

    DOEpatents

    Trujillo, Patricio E.; Campbell, Evan E.; Eutsler, Bernard C.

    1976-01-20

    A method of simultaneously sampling particulate mercury, organic mercurial vapors, and metallic mercury vapor in the working and occupational environment and determining the amount of mercury derived from each such source in the sampled air. A known volume of air is passed through a sampling tube containing a filter for particulate mercury collection, a first adsorber for the selective adsorption of organic mercurial vapors, and a second adsorber for the adsorption of metallic mercury vapor. Carbon black molecular sieves are particularly useful as the selective adsorber for organic mercurial vapors. The amount of mercury adsorbed or collected in each section of the sampling tube is readily quantitatively determined by flameless atomic absorption spectrophotometry.

  5. Mercury's magnetosphere after MESSENGER's first flyby.

    PubMed

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

    2008-07-01

    Observations by MESSENGER show that Mercury's magnetosphere is immersed in a comet-like cloud of planetary ions. The most abundant, Na+, is broadly distributed but exhibits flux maxima in the magnetosheath, where the local plasma flow speed is high, and near the spacecraft's closest approach, where atmospheric density should peak. The magnetic field showed reconnection signatures in the form of flux transfer events, azimuthal rotations consistent with Kelvin-Helmholtz waves along the magnetopause, and extensive ultralow-frequency wave activity. Two outbound current sheet boundaries were observed, across which the magnetic field decreased in a manner suggestive of a double magnetopause. The separation of these current layers, comparable to the gyro-radius of a Na+ pickup ion entering the magnetosphere after being accelerated in the magnetosheath, may indicate a planetary ion boundary layer. PMID:18599776

  6. Predicting mercury in mallard ducklings from mercury in chorioallantoic membranes

    USGS Publications Warehouse

    Heinz, G.H.; Hoffman, D.J.

    2003-01-01

    Methylmercury has been suspected as a cause of impaired reproduction in wild birds, but the confounding effects of other environmental stressors has made it difficult to determine how much mercury in the eggs of these wild species is harmful. Even when a sample egg can be collected from the nest of a wild bird and the mercury concentration in that egg compared to the laboratory-derived thresholds for reproductive impairment, additional information on the mercury levels in other eggs from that nest would be helpful in determining whether harmful levels of mercury were present in the clutch. The measurement of mercury levels in chorioallantoic membranes offers a possible way to estimate how much mercury was in a chick that hatched from an egg, and also in the whole fresh egg itself. While an embryo is developing, wastes are collected in a sac called the chorioallantoic membranes, which often remain inside the eggshell and can be collected for contaminant analysis. We fed methylmercury to captive mallards to generate a broad range of mercury levels in eggs, allowed the eggs to hatch normally, and then compared mercury concentrations in the hatchling versus the chorioallantoic membranes left behind in the eggshell. When the data from eggs laid by mercury- treated females were expressed as common logarithms, a linear equation was created by which the concentration of mercury in a duckling could be predicted from the concentration of mercury in the chorioallantoic membranes from the same egg. Therefore, if it were not possible to collect a sample egg from a clutch of wild bird eggs, the collection of the chorioallantoic membranes could be substituted, and the mercury predicted to be in the chick or whole egg could be compared to the thresholds of mercury that have been shown to cause harm in controlled feeding studies with pheasants, chickens, and mallards.

  7. Mercury removal from solution by superconducting magnetic separation with nanostructured magnetic adsorbents

    NASA Astrophysics Data System (ADS)

    Okamoto, T.; Tachibana, S.; Miura, O.; Takeuchi, M.

    2011-11-01

    Recently, mercury Hg concentration in human blood increases due to expanding the global mercury contamination. Excess mercury bioaccumulation poses a significant health risk. In order to decrease mercury concentration in the environment and human blood, we have developed two different kinds of nanostructured magnetic adsorbents for mercury to apply them to superconducting magnetic separation instead of conventional filtration. One is magnetic beads (MBs) which have nanosize magnetite particles in the core and a lot of SH radicals on the surface to adsorb Hg ions effectively. MBs were developed mainly to remove mercury from human blood. The maximum amount of the adsorption for MBs is 6.3 mg/g in the solution in less than a minute. Dithiothreitol can easily remove mercury adsorbed to MBs, hence MBs can be reusable. The other is nanostructured magnetic activated carbon (MAC) which is activated carbon with mesopores and nanosize magnetite. The maximum amount of the adsorption for MAC is 38.3 mg/g in the solution. By heat-treatment mercury can be easily removed from MAC. We have studied superconducting magnetic separation using each adsorbent for mercury removal from solution.

  8. MERCURY CYCLING AND BIOMAGNIFICATION

    EPA Science Inventory

    Mercury cycling and biomagnification was studied in man-made ponds designed for watering livestock on the Cheyenne River Sioux Reservation in South Dakota. Multiple Hg species were quantified through multiple seasons for 2 years in total atmospheric deposition samples, surface wa...

  9. Magnetosphere of Mercury

    NASA Technical Reports Server (NTRS)

    Whang, Y. C.

    1975-01-01

    A model magnetosphere of Mercury using Mariner 10 data is presented. Diagrams of the bow shock wave and magnetopause are shown. The analysis of Mariner 10 data indicates that the magnetic field of the planet is intrinsic. The magnetic tail and secondary magnetic fields, and the influence of the solar wind are also discussed.

  10. MERCURY CEMS: TECHNOLOGY UPDATE

    EPA Science Inventory

    The paper reviews the technologies involved with continuous emission monitors (CEMs) for mercury (Hg) which are receiving incresed attention and focus. Their potential use as a compliance assurance tool is of particular interest. While Hg CEMs are currently used in Europe for com...

  11. Hazards of Mercury.

    ERIC Educational Resources Information Center

    Environmental Research, 1971

    1971-01-01

    Common concern for the protection and improvement of the environment and the enhancement of human health and welfare underscore the purpose of this special report on the hazards of mercury directed to the Secretary's Pesticide Advisory Committee, Department of Health, Education, and Welfare. The report summarizes the findings of a ten-member study…

  12. ATMOSPHERIC MERCURY RESEARCH

    EPA Science Inventory

    Environmental contamination from mercury has been recognized for decades as a growing problem to humans and wildlife. It is released from a variety of sources, exhibits a complicated chemistry, and proceeds via several different pathways to humans and wildlife. According to the...

  13. Tidal Dissipation in Mercury

    NASA Technical Reports Server (NTRS)

    Bills, B. G.

    2002-01-01

    The spatial pattern and total inventory of tidal dissipation within Mercury depends sensitively on internal structure and on orbital eccentricity. Surface heat flow from this source may exceed 3 mW/sq m, and will vary with time as the orbital eccentricity fluctuates. Additional information is contained in the original extended abstract.

  14. MERCURY SPECIATION AND CAPTURE

    EPA Science Inventory

    In December 2000, the U.S. Environmental Protection Agency (USEPA) announced its intent to regulate mercury emissions from coal-fired electric utility steam generating plants. Maximum achievable control technology (MACT) requirements are to be proposed by December 2003 and finali...

  15. Mercury Shopping Cart Interface

    NASA Technical Reports Server (NTRS)

    Pfister, Robin; McMahon, Joe

    2006-01-01

    Mercury Shopping Cart Interface (MSCI) is a reusable component of the Power User Interface 5.0 (PUI) program described in another article. MSCI is a means of encapsulating the logic and information needed to describe an orderable item consistent with Mercury Shopping Cart service protocol. Designed to be used with Web-browser software, MSCI generates Hypertext Markup Language (HTML) pages on which ordering information can be entered. MSCI comprises two types of Practical Extraction and Report Language (PERL) modules: template modules and shopping-cart logic modules. Template modules generate HTML pages for entering the required ordering details and enable submission of the order via a Hypertext Transfer Protocol (HTTP) post. Shopping cart modules encapsulate the logic and data needed to describe an individual orderable item to the Mercury Shopping Cart service. These modules evaluate information entered by the user to determine whether it is sufficient for the Shopping Cart service to process the order. Once an order has been passed from MSCI to a deployed Mercury Shopping Cart server, there is no further interaction with the user.

  16. An oligonucleotide-functionalized carbon nanotube chemiresistor for sensitive detection of mercury in saliva.

    PubMed

    Wordofa, Dawit N; Ramnani, Pankaj; Tran, Thien-Toan; Mulchandani, Ashok

    2016-04-25

    Divalent mercuric (Hg(2+)) ion and monomethyl mercury (CH3Hg(+)) are two forms of mercury that are known to be highly toxic to humans. In this work, we present a highly selective, sensitive and label-free chemiresistive biosensor for the detection of both, Hg(2+) and CH3Hg(+) ions using DNA-functionalized single-walled carbon nanotubes (SWNTs). The SWNTs were functionalized with the capture oligonucleotide, polyT, using a linker molecule. The polyT was hybridized with polyA to form a polyT:polyA duplex. Upon exposure to mercury ions, the polyT:polyA duplex dehybridizes and a T-Hg(2+)-T duplex is formed. This structure switch leads to the release of polyA from the SWNT surface and correspondingly a change in the resistance of the chemiresistive biosensor is observed, which is used to quantify the mercury ion concentration. The biosensor showed a wide dynamic range of 0.5 to 100 nM for the detection of CH3Hg(+) ions in buffer solution with a sensitivity of 28.34% per log (nM) of CH3Hg(+). Finally, real world application of the biosensor was demonstrated by the detection of Hg(2+) and CH3Hg(+) ions in simulated saliva samples spiked with a known concentration of mercury ions. PMID:26902487

  17. Mercury Information Clearinghouse

    SciTech Connect

    Chad A. Wocken; Michael J. Holmes; Dennis L. Laudal; Debra F. Pflughoeft-Hassett; Greg F. Weber; Nicholas V. C. Ralston; Stanley J. Miller; Grant E. Dunham; Edwin S. Olson; Laura J. Raymond; John H. Pavlish; Everett A. Sondreal; Steven A. Benson

    2006-03-31

    The Canadian Electricity Association (CEA) identified a need and contracted the Energy & Environmental Research Center (EERC) to create and maintain an information clearinghouse on global research and development activities related to mercury emissions from coal-fired electric utilities. With the support of CEA, the Center for Air Toxic Metals{reg_sign} (CATM{reg_sign}) Affiliates, and the U.S. Department of Energy (DOE), the EERC developed comprehensive quarterly information updates that provide a detailed assessment of developments in the various areas of mercury monitoring, control, policy, and research. A total of eight topical reports were completed and are summarized and updated in this final CEA quarterly report. The original quarterly reports can be viewed at the CEA Web site (www.ceamercuryprogram.ca). In addition to a comprehensive update of previous mercury-related topics, a review of results from the CEA Mercury Program is provided. Members of Canada's coal-fired electricity generation sector (ATCO Power, EPCOR, Manitoba Hydro, New Brunswick Power, Nova Scotia Power Inc., Ontario Power Generation, SaskPower, and TransAlta) and CEA, have compiled an extensive database of information from stack-, coal-, and ash-sampling activities. Data from this effort are also available at the CEA Web site and have provided critical information for establishing and reviewing a mercury standard for Canada that is protective of environment and public health and is cost-effective. Specific goals outlined for the CEA mercury program included the following: (1) Improve emission inventories and develop management options through an intensive 2-year coal-, ash-, and stack-sampling program; (2) Promote effective stack testing through the development of guidance material and the support of on-site training on the Ontario Hydro method for employees, government representatives, and contractors on an as-needed basis; (3) Strengthen laboratory analytical capabilities through

  18. [Mercury in vaccines].

    PubMed

    Hessel, Luc

    2003-01-01

    Thiomersal, also called thimerosal, is an ethyl mercury derivative used as a preservative to prevent bacterial contamination of multidose vaccine vials after they have been opened. Exposure to low doses of thiomersal has essentially been associated with hypersensitivity reactions. Nevertheless there is no evidence that allergy to thiomersal could be induced by thiomersal-containing vaccines. Allergy to thiomersal is usually of delayed-hypersensitivity type, but its detection through cutaneous tests is not very reliable. Hypersensitivity to thiomersal is not considered as a contraindication to the use of thiomersal-containing vaccines. In 1999 in the USA, thiomersal was present in approximately 30 different childhood vaccines, whereas there were only 2 in France. Although there were no evidence of neurological toxicity in infants related to the use of thiomersal-containing vaccines, the FDA considered that the cumulative dose of mercury received by young infants following vaccination was high enough (although lower than the FDA threshold for methyl mercury) to request vaccine manufacturers to remove thiomersal from vaccine formulations. Since 2002, all childhood vaccines used in Europe and the USA are thiomersal-free or contain only minute amounts of thiomersal. Recently published studies have shown that the mercury levels in the blood, faeces and urine of children who had received thiomersal-containing vaccines were much lower than those accepted by the American Environmental Protection Agency. It has also been demonstrated that the elimination of mercury in children was much faster than what was expected on the basis of studies conducted with methyl mercury originating from food. Recently, the hypothesis that mercury contained in vaccines could be the cause of autism and other neurological developmental disorders created a new debate in the medical community and the general public. To date, none of the epidemiological studies conducted in Europe and elsewhere

  19. Mercury control in 2009

    SciTech Connect

    Sjostrom, S.; Durham, M.; Bustard, J.; Martin, C.

    2009-07-15

    Although activated carbon injection (ACI) has been proven to be effective for many configurations and is a preferred option at many plants sufficient quantities of powdered activated coking (PAC) must be available to meet future needs. The authors estimate that upcoming federal and state regulations will result in tripling the annual US demand for activated carbon to nearly 1.5 billion lb from approximately 450 million lb. Rapid expansion of US production capacity is required. Many PAC manufacturers are discussing expansion of their existing production capabilities. One company, ADA Carbon Solutions, is in the process of constructing the largest activated carbon facility in North America to meet the future demand for PAC as a sorbent for mercury control. Emission control technology development and commercialization is driven by regulation and legislation. Although ACI will not achieve > 90% mercury control at every plant, the expected required MACT legislation level, it offers promise as a low-cost primary mercury control technology option for many configurations and an important trim technology for others. ACI has emerged as the clear mercury-specific control option of choice, representing over 98% of the commercial mercury control system orders to date. As state regulations are implemented and the potential for a federal rule becomes more imminent, suppliers are continuing to develop technologies to improve the cost effectiveness and limit the balance of plant impacts associated with ACI and are developing additional PAC production capabilities to ensure that the industry's needs are met. The commercialisation of ACI is a clear example of industry, through the dedication of many individuals and companies with support from the DOE and EPRI, meeting the challenge of developing cost-effectively reducing emissions from coal-fired power plants. 7 refs., 1 fig.

  20. 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, ...

  1. Gastrointestinal absorption of metallic mercury.

    PubMed

    Sandborgh-Englund, Gunilla; Einarsson, Curt; Sandström, Magnus; Ekstrand, Jan

    2004-09-01

    The absorption of mercury from the gastrointestinal systems of 7 subjects, of whom none had any amalgam fillings, was examined in this study. The authors obtained quantitative information about mercury concentration in plasma and duodenal fluid after the gastrointestinal systems of the subjects were exposed to liquid elemental mercury enclosed in rubber balloons (i.e., approximately 20 g of mercury), using a standard procedure followed for the sampling of bile. Plasma samples were collected prior to exposure, as well as up to 10 d following exposure, and duodenal fluid was collected 1 h, 2 h, 4 h, and 6 h during the intubation process. The authors studied the kinetics of dissolution in vitro by leaching elemental liquid mercury and mercuric chloride. The results of this study supported the hypothesis that metallic mercury is oxidized in the gastrointestinal tract. In addition, the authors determined that duodenal intubation, while using liquid metallic mercury in rubber bags, resulted in the diffusion of minor amounts of atomic elemental mercury through the rubber walls. The absorbed amount of mercury that reached the central circulation was comparable to a daily dose of mercury from dental amalgam in the amalgam-bearing population. PMID:16381485

  2. MERCURY USAGE AND ALTERNATIVES IN THE ELECTRICAL AND ELECTRONICS INDUSTRIES

    EPA Science Inventory

    Many industries have already found alternatives for mercury or have greatly decreased mercury use. However, the unique electromechanical and photoelectric properties of mercury and mercury compounds have made replacement of mercury difficult in some applications. This study was i...

  3. MERCURY USAGE AND ALTERNATING IN THE ELECTRICAL AND ELECTRONICS INDUSTRIES

    EPA Science Inventory

    Many industries have already found alternatives for mercury or have greatly decreased mercury use. owever, the unique electromechanical and photoelectric properties of mercury and mercury compounds have made replacement of mercury difficult in some applications. his study was ini...

  4. Mercury's exosphere: observations during MESSENGER's First Mercury flyby.

    PubMed

    McClintock, William E; Bradley, E Todd; Vervack, Ronald J; Killen, Rosemary M; Sprague, Ann L; Izenberg, Noam R; Solomon, Sean C

    2008-07-01

    During MESSENGER's first Mercury flyby, the Mercury Atmospheric and Surface Composition Spectrometer measured Mercury's exospheric emissions, including those from the antisunward sodium tail, calcium and sodium close to the planet, and hydrogen at high altitudes on the dayside. Spatial variations indicate that multiple source and loss processes generate and maintain the exosphere. Energetic processes connected to the solar wind and magnetospheric interaction with the planet likely played an important role in determining the distributions of exospheric species during the flyby. PMID:18599778

  5. Removal of mercury (II), elemental mercury and arsenic from simulated flue gas by ammonium sulphide.

    PubMed

    Ning, Ping; Guo, Xiaolong; Wang, Xueqian; Wang, Ping; Ma, Yixing; Lan, Yi

    2015-01-01

    A tubular resistance furnace was used as a reactor to simulate mercury and arsenic in smelter flue gases by heating mercury and arsenic compounds. The flue gas containing Hg(2+), Hg(0) and As was treated with ammonium sulphide. The experiment was conducted to investigate the effects of varying the concentration of ammonium sulphide, the pH value of ammonium sulphide, the temperature of ammonium sulphide, the presence of SO2 and the presence of sulphite ion on removal efficiency. The prepared adsorption products were characterized by Fourier transform infrared spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy and scanning electron microscopy. The results showed that the optimal concentration of ammonium sulphide was 0.8 mol/L. The optimal pH value of ammonium sulphide was 10, and the optimal temperature of ammonium sulphide was 20°C.Under the optimum conditions, the removal efficiency of Hg(2+), Hg(0) and As could reach 99%, 88.8%, 98%, respectively. In addition, SO2 and sulphite ion could reduce the removal efficiency of mercury and arsenic from simulated flue gas. PMID:25965547

  6. MERCURY DEPOSITION AND LAKE QUALITY TRENDS

    EPA Science Inventory

    Watershed factors influence the differing trends in mercury residue levels. Fish mercury concentrations show positive correlations with water color, methylmercury concentrations, and plankton mercury, and negative correlations with pH and alkalinity.

  7. Recovery of mercury from acid waste residues

    DOEpatents

    Greenhalgh, W.O.

    1987-02-27

    Mercury can be recovered from nitric acid-containing fluids by reacting the fluid with aluminum metal to produce mercury metal, and thence quenching the reactivity of the nitric acid prior to nitration of the mercury metal. 1 fig.

  8. Recovery of mercury from acid waste residues

    DOEpatents

    Greenhalgh, Wilbur O.

    1989-01-01

    Mercury can be recovered from nitric acid-containing fluids by reacting the fluid with aluminum metal to produce mercury metal, and then quenching the reactivity of the nitric acid prior to nitration of the mercury metal.

  9. Recovery of mercury from acid waste residues

    DOEpatents

    Greenhalgh, Wilbur O.

    1989-12-05

    Mercury can be recovered from nitric acid-containing fluids by reacting the fluid with aluminum metal to produce mercury metal, and then quenching the reactivity of the nitric acid prior to nitration of the mercury metal.

  10. Calculating the X-Ray Fluorescence from the Planet Mercury Due to High-Energy Electrons

    NASA Technical Reports Server (NTRS)

    Burbine, T. H.; Trombka, J. I.; Bergstrom, P. M., Jr.; Christon, S. P.

    2005-01-01

    The least-studied terrestrial planet is Mercury due to its proximity to the Sun, which makes telescopic observations and spacecraft encounters difficult. Our lack of knowledge about Mercury should change in the near future due to the recent launching of MESSENGER, a Mercury orbiter. Another mission (BepiColombo) is currently being planned. The x-ray spectrometer on MESSENGER (and planned for BepiColombo) can characterize the elemental composition of a planetary surface by measuring emitted fluorescent x-rays. If electrons are ejected from an atom s inner shell by interaction with energetic particles such as photons, electrons, or ions, electrons from an outer shell can transfer to the inner shell. Characteristic x-rays are then emitted with energies that are the difference between the binding energy of the ion in its excited state and that of the ion in its ground state. Because each element has a unique set of energy levels, each element emits x-rays at a unique set of energies. Electrons and ions usually do not have the needed flux at high energies to cause significant x-ray fluorescence on most planetary bodies. This is not the case for Mercury where high-energy particles were detected during the Mariner 10 flybys. Mercury has an intrinsic magnetic field that deflects the solar wind, resulting in a bow shock in the solar wind and a magnetospheric cavity. Electrons and ions accelerated in the magnetosphere tend to follow its magnetic field lines and can impact the surface on Mercury s dark side Modeling has been done to determine if x-ray fluorescence resulting from the impact of high-energy electrons accelerated in Mercury's magnetosphere can be detected by MESSENGER. Our goal is to understand how much bulk chemical information can be obtained from x-ray fluorescence measurements on the dark side of Mercury.

  11. Crater chains on Mercury

    NASA Astrophysics Data System (ADS)

    Shevchenko, V.; Skobeleva, T.

    After discovery of disruption comet Shoemaker-Levy 9 into fragment train before it's collision with Jupiter there was proposed that linear crater chains on the large satellites of Jupiter and on the Moon are impact scars of past tidally disrupted comets.It's known that radar images have revealed the possible presence of water ice deposits in polar regions of Mercury. Impacts by a few large comets seem to provide the best explanation for both the amount and cleanliness of the ice deposits on Mercury because they have a larger volatile content that others external sources, for example, asteroid. A number of crater chains on the surface of Mercury are most likely the impact tracks of "fragment trains" of comets tidally disrupted by Sun or by Mercury and are not secondary craters. Mariner 10 image set (the three Mariner 10 flybys in 1974-1975) was used to recognize the crater chains these did not associate with secondary crater ejecta from observed impact structures. As example, it can be shown such crater chain located near crater Imhotep and crater Ibsen (The Kuiper Quadrangle of Mercury). Resolution of the Mariner 10 image is about 0.54 km/pixel. The crater chain is about 50 km long. It was found a similar crater chain inside large crater Sophocles (The Tolstoj Quadrangle of Mercury). The image resolution is about 1.46 km/pixel. The chain about 50 km long is located in northen part of the crater. Image resolution limits possibility to examine the form of craters strongly. It seems the craters in chains have roughly flat floor and smooth form. Most chain craters are approximately circular. It was examined many images from the Mariner 10 set and there were identified a total 15 crater chains and were unable to link any of these directly to any specific large crater associated with ejecta deposits. Chain craters are remarkably aligned. All distinguished crater chains are superposed on preexisting formations. A total of 127 craters were identified in the 15 recognized

  12. Volatilization of Mercury By Bacteria

    PubMed Central

    Magos, L.; Tuffery, A. A.; Clarkson, T. W.

    1964-01-01

    Volatilization of mercury has been observed from various biological media (tissue homogenates, infusion broth, plasma, urine) containing mercuric chloride. That micro-organisms were responsible was indicated by the finding that the rates of volatilization were highly variable, that a latent period often preceded volatilization, that toluene inhibited the process, and that the capacity to volatilize mercury could be transferred from one biological medium to another. Two species of bacteria when isolated and cultured from these homogenates were able to volatilize mercury. Two other bacteria, one of which was isolated from the local water supply, were also highly active. The volatile mercury was identified as mercury vapour. The importance of these findings in relation to the storage of urine samples prior to mercury analysis is discussed. PMID:14249899

  13. Space weathering on Mercury: Simulation of plagioclase weathering

    NASA Astrophysics Data System (ADS)

    Sasaki, Sho; Hiroi, Takahiro; Helbert, Jorn; Arai, Tomoko

    The optical property of the surfaces of airless silicate bodies such as the Moon, Mercury and asteroids should change in time. Typical characteristics of the change, "space weathering", are darkening, spectral reddening, and attenuation of absorption bands in reflectance spectra. The space weathering is caused by the formation of nanophase metallic iron particles in amorphous surface coatings from the deposition of ferrous silicate vapor, which was formed by high velocity dust impacts as well as irradiation of the solar wind ions. Nanophase iron particles have been confirmed in the lunar soil coating [1]. Moreover, experimental studies using pulse laser showed the formation of nanophase ion particles on the surface should control the spectral darkening and reddening [2]. Mariner 10 and MESSENGER spacecraft showed that Mercury has more impact craters asso-ciated with bright rays than the Moon. The space weathering rate on Mercury's surface might be slower than that of the lunar surface, although dust flux and solar wind flux causing the weathering should be one order of magnitude of greater on Mercury than on the Moon [3]. The Mercury Atmospheric and Surface Composition Spectrometer (MASCS) on board MES-SENGER measured reflectance spectra from Mercury's surface during the two flybys in 2008 [4] with the wavelength range between 0.2 and 1.3 microns. MASCS spectra show variation in the slope, which can be explained by lunar-like maturity trend due to the difference of space weathering degree. Spectral absorption in the UV range shows that the ferrous oxide (Fe2+) content in average surface/subsurface material is as low as a few weight percent. This could explain apparent low weathering rate on Mercury. Growth of size of nanophase iron could also have lowered the weathering degree. Size of nanophase iron particles should increase by Ostwald ripening under high temperature of several 100C [5] . And repeated irradiation by high velocity dust impacts as well as solar wind

  14. [Mercury (and...) through the centuries].

    PubMed

    Kłys, Małgorzata

    2010-01-01

    Mercury has a long history, fascinating in its many aspects. Through the centuries--from ancient times to the present day--the metal in its various forms, also known under the name "quicksilver", accompanied the man and was used for diversified purposes. Today, mercury is employed in manufacturing thermometers, barometers, vacuum pumps and explosives. It is also used in silver and gold mining processes. Mercury compounds play a significant role in dentistry, pharmaceutical industry and crop protection. The contemporary use of mercury markedly decreases, but historically speaking, the archives abound in materials that document facts and events occurring over generations and the immense intellectual effort aiming at discovering the true properties and mechanisms of mercury activity. Mercury toxicity, manifested in destruction of biological membranes and binding of the element with proteins, what disturbs biochemical processes occurring in the body, was discovered only after many centuries of the metal exerting its effect on the lives of individuals and communities. For centuries, mercury was present in the work of alchemists, who searched for the universal essence or quintessence and the so-called philosopher's stone. In the early modern era, between the 16th and 19th centuries, mercury was used to manufacture mirrors. Mercury compounds were employed as a medication against syphilis, which plagued mankind for more than four hundred years--from the Middle Ages till mid 20th century, when the discovery of penicillin became the turning point. This extremely toxic therapy resulted in much suffering, individual tragedies, chronic poisonings leading to fatalities and dramatic sudden deaths. In the last fifty years, there even occurred attempts of mentally imbalanced individuals at injecting themselves with metallic mercury, also as a performance-enhancing drug. Instances of mass mercury poisoning occurred many times in the past in consequence of eating food products

  15. Remediation of mercury contaminated sites - A review.

    PubMed

    Wang, Jianxu; Feng, Xinbin; Anderson, Christopher W N; Xing, Ying; Shang, Lihai

    2012-06-30

    Environmental contamination caused by mercury is a serious problem worldwide. Coal combustion, mercury and gold mining activities and industrial activities have led to an increase in the mercury concentration in soil. The objective of this paper is to present an up-to-date understanding of the available techniques for the remediation of soil contaminated with mercury through considering: mercury contamination in soil, mercury speciation in soil; mercury toxicity to humans, plants and microorganisms, and remediation options. This paper describes the commonly employed and emerging techniques for mercury remediation, namely: stabilization/solidification (S/S), immobilization, vitrification, thermal desorption, nanotechnology, soil washing, electro-remediation, phytostabilization, phytoextraction and phytovolatilization. PMID:22579459

  16. Mercury, Vaccines, and Autism

    PubMed Central

    Baker, Jeffrey P.

    2008-01-01

    The controversy regarding the once widely used mercury-containing preservative thimerosal in childhood vaccines has raised many historical questions that have not been adequately explored. Why was this preservative incorporated in the first place? Was there any real evidence that it caused harm? And how did thimerosal become linked in the public mind to the “autism epidemic”? I examine the origins of the thimerosal controversy and their legacy for the debate that has followed. More specifically, I explore the parallel histories of three factors that converged to create the crisis: vaccine preservatives, mercury poisoning, and autism. An understanding of this history provides important lessons for physicians and policymakers seeking to preserve the public’s trust in the nation’s vaccine system. PMID:18172138

  17. Transpressional Structures on Mercury

    NASA Astrophysics Data System (ADS)

    Massironi, M.; Di Achille, G.; Ferrari, S.; Giacomini, L.; Popa, C.; Pozzobon, R.; Zusi, M.; Cremonese, G.; Palumbo, P.

    2012-04-01

    Mercury is classically dominated by contractional features at a global scale (e.g. Watters et al.2009, EPSL]). Nonetheless, numerous evidences of strike-slip kinematics have been found on Mercury Dual Imaging System (MDIS) camera images mainly derived from the three MESSENGER flybys and acquired near the terminator. This proves that several lobate scarps and high-relief ridges may be interpreted as transpressional structures more than thrust and back-thrusts systems. This finding may support either tidal despinning or residual mantle convection on ruling the nucleation and development of lobate scarps, although within the general framework of planetary contraction and cooling. In addition, the presence of faults with a clear strike-slip kinematic component may possibly affect future estimates of the hermean radius shortening.

  18. Toxicity of mercury and mercury compounds. (Latest citations from Pollution Abstracts). Published Search

    SciTech Connect

    Not Available

    1993-02-01

    The bibliography contains citations concerning the toxic effects of mercury and mercury compounds on biological systems. The citations examine mercury halides, organic mercury compounds, mercury metal, and mercury vapor. Metabolism, toxicology, occupational exposure, symptoms of exposure, mechanisms of interaction with biological systems, demographics of mercury accumulation and poisoning, and case reports are considered. Heavy metal pollution and bioaccumulation are referenced in related bibliographies. (Contains 250 citations and includes a subject term index and title list.)

  19. Mercury's Exosphere explored by BepiColombo mission

    NASA Astrophysics Data System (ADS)

    Hikosaka, K.; Yoshikawa, I.; Yamazaki, A.; Nozawa, H.; Kameda, S.; Yoshioka, K.

    2005-12-01

    The Mercury's Sodium Atmosphere Interferometer (MSASI) on BepiColombo will address a wealth of fundamental scientific questions pertaining to the Mercury's exosphere. Together, our measurement on the overall scale will provide ample new information on regolith-exosphere-magnetosphere coupling as well as new understanding of the dynamics governing the surface-bounded exosphere. Discoveries of Na, K and Ca from the ground-based observations clearly arises that the regolith of Mercury releases a fraction of its content to the atmosphere. Some processes are proposed up to now as release mechanisms, e.g. (1) Chemical sputtering, (2) Thermal desorption, (3) Photon-stimulated desorption, (4) Ion sputtering, and (5) Micro-meteoroid impact/vaporization. These processes are associated with different energies of ejection from regolith and behaviors in different regions of Mercury's surface. Therefore different types of population are born from the surface, depending on the process. The distribution of the neutral atmosphere is strongly affected by solar radiation. The shape and size of the exosphere could change depending on True anomaly angle (TAA). We can see the variability of the spatial distribution of the Mercury atmosphere using the Monte Carlo simulation. MSASI is a high-dispersion visible spectrometer working in the spectral range around sodium D2 emission (589nm) and devoted to the characterization of the Mercury_fs exosphere. A tandem Fabry-Perot etalon is used to achieve a compact design. A one degree-of-freedom scanning mirror is employed to allow obtaining full-disk image of the planet and selected region of interest, e.g. polar regions, Caloris Basin, and magnetosphere. In this paper, we will show the feasibility of identifying a process, which is responsible for sodium exosphere of Mercury. We also report the current status of our hardware development.

  20. Treatment of Mercury Contaminated Oil from Sandia National Laboratory

    SciTech Connect

    Klasson, KT

    2002-05-28

    First Article Tests of a stabilization method for greater than 260 mg mercury/kg oil were performed under a treatability study. This alternative treatment technology will address treatment of U.S. Department of Energy (DOE) organics (mainly used pump oil) contaminated with mercury and other heavy metals. Some of the oil is also co-contaminated with tritium, other radionuclides, and hazardous materials. The technology is based on contacting the oil with a sorbent powder (Self-Assembled Mercaptan on Mesoporous Support, SAMMS), proven to adsorb heavy metals, followed by stabilization of the oil/powder mixture using a stabilization agent (Nochar N990). Two variations of the treatment technology were included in the treatability study. The SAMMS (Self-Assembled Mercaptan on Mesoporous Silica) technology was developed by the Pacific Northwest National Laboratory for removal and stabilization of RCRA metals (i.e., lead, mercury, cadmium, silver, etc.) and for removal of mercury from organic solvents [1]. The SAMMS material is based on self-assembly of functionalized monolayers on mesoporous oxide surfaces. The unique mesoporous oxide supports provide a high surface area, thereby enhancing the metal-loading capacity. SAMMS material has high flexibility in that it binds with different forms of mercury, including metallic, inorganic, organic, charged, and neutral compounds [1] The material removes mercury from both organic wastes, such as pump oils, and from aqueous wastes. Mercury-loaded SAMMS not only passes TCLP tests, but also has good long-term durability as a waste form because: (1) the covalent binding between mercury and SAMMS has good resistance in ion-exchange, oxidation, and hydrolysis over a wide pH range and (2) the uniform and small pore size of the mesoporous silica prevents bacteria from solubilizing the bound mercury. Nochar's N990 Petrobond (Nochar, Inc., Indianapolis, IN) is an oil stabilization agent, specifically formulated for stabilizing vacuum pump