Science.gov

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. 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.

  3. 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.

  4. Thermal analytic model of 30 cm engineering model mercury ion thruster

    NASA Technical Reports Server (NTRS)

    Oglebay, J. C.

    1975-01-01

    A lumped parameter thermal nodal network was developed for a 30 cm Engineering Model Mercury Ion Thruster. The network consists of approximately 100 nodes coded in SINDA format for use on the Univac 1106/1108 computer. This model takes into account internal dissipation, radiation, and conduction as well as environmental heating. A series of tests were performed to simulate a wide range of thermal environments on an operating 30 cm thruster, instrumented to measure the temperature distribution within the thruster. The results of these tests were used to calibrate the analytical model. The analytical model along with comparisons between analytical and experimental results for the various operating conditions are presented.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. Compensated control loops for a 30-cm ion thruster

    NASA Technical Reports Server (NTRS)

    Robson, R. R.

    1976-01-01

    The vaporizer dynamic control characteristics of a 30-cm diameter mercury ion thruster were determined by operating the thruster in an open loop steady state mode and then introducing a small sinusoidal signal on the main, cathode, or neutralizer vaporizer current and observing the response of the beam current, discharge voltage, and neutralizer keeper voltage, respectively. This was done over a range of frequencies and operating conditions. From these data, Bode plots for gain and phase were made and mathematical models were obtained. The Bode plots and mathematical models were analyzed for stability and appropriate compensation networks determined. The compensated control loops were incorporated into a power processor and operated with a thruster. The time responses of the compensated loops to changes in set points and recovery from arc conditions are presented.

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. Increased capabilities of the 30-cm diameter Hg ion thruster

    NASA Technical Reports Server (NTRS)

    Rawlin, V. K.; Hawkins, C. E.

    1979-01-01

    Some space flight missions require advanced ion thrusters which operate at conditions much different than those for which the baseline 30-cm Hg thruster was developed. Results of initial tests of a 30-cm Hg thruster with two and three grid ion accelerating systems, operated at higher values of both thrust and power and over a greater range of specific impulse than the baseline conditions are presented. Thruster lifetime at increased input power was evaluated both by extended tests and real time spectroscopic measurements.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. Experimentally Determined Plasma Parameters in a 30 cm Ion Engine

    NASA Technical Reports Server (NTRS)

    Sengupta, Anita; Goebel, Dan; Fitzgerald, Dennis; Owens, Al; Tynan, George; Dorner, Russ

    2004-01-01

    Single planar Langmuir probes and fiber optic probes are used to concurrently measure the plasma properties and neutral density variation in a 30cm diameter ion engine discharge chamber, from the immediate vicinity of the keeper to the near grid plasma region. The fiber optic probe consists of a collimated optical fiber recessed into a double bore ceramic tube fitted with a stainless steel light-limiting window. The optical fiber probe is used to measure the emission intensity of excited neutral xenon for a small volume of plasma, at various radial and axial locations. The single Langmuir probes, are used to generate current-voltage characteristics at a total of 140 spatial locations inside the discharge chamber. Assuming a maxwellian distribution for the electron population, the Langmuir probe traces provide spatially resolved measurements of plasma potential, electron temperature, and plasma density. Data reduction for the NSTAR TH8 and TH15 throttle points indicates an electron temperature range of 1 to 7.9 eV and an electron density range of 4e10 to le13 cm(sup -3), throughout the discharge chamber, consistent with the results in the literature. Plasma potential estimates, computed from the first derivative of the probe characteristic, indicate potential from 0.5V to 11V above the discharge voltage along the thruster centerline. These values are believed to be excessively high due to the sampling of the primary electron population along the thruster centerline. Relative neutral density profiles are also obtained with a fiber optic probe sampling photon flux from the 823.1 nm excited to ground state transition. Plasma parameter measurements and neutral density profiles will be presented as a function of probe location and engine discharge conditions. A discussion of the measured electron energy distribution function will also be presented, with regards to variation from pure maxwellian. It has been found that there is a distinct primary population found along

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. Reduced power processor requirements for the 30-cm diameter HG ion thruster

    NASA Technical Reports Server (NTRS)

    Rawlin, V. K.

    1979-01-01

    The characteristics of power processors strongly impact the overall performance and cost of electric propulsion systems. A program was initiated to evaluate simplifications of the thruster-power processor interface requirements. The power processor requirements are mission dependent with major differences arising for those missions which require a nearly constant thruster operating point (typical of geocentric and some inbound planetary missions) and those requiring operation over a large range of input power (such as outbound planetary missions). This paper describes the results of tests which have indicated that as many as seven of the twelve power supplies may be eliminated from the present Functional Model Power Processor used with 30-cm diameter Hg ion thrusters.

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. Endurance test of a 30-CM-diameter engineering model ion thruster. Task 12: Investigation of thin-film erosion monitors for ion thrusters

    NASA Technical Reports Server (NTRS)

    Beattie, J. R.

    1983-01-01

    An investigation of short term measurement techniques for predicting the wearout of ion thrusters resulting from sputter erosion damage is described. The previously established laminar thin film techniques to provide high precision erosion rate data. However, the erosion rates obtained using this technique are generally substantially higher than those obtained during long term endurance tests (by virtue of the as deposited nature of the thin films), so that the results must be interpreted in a relative sense. Absolute measurements can be performed using a new masked substrate arrangement which was developed during this study. This new technique provides a means for estimating the lifetimes of critical discharge chamber components based on direct measurements of sputter erosion depths obtained during short duration (10 hour) tests. The method enables the effects on lifetime of thruster design and operating parameters to be inferred without the investment of the time and capital required to conduct long term (1000 hour) endurance tests. Results obtained using the direct measurement technique are shown to agree with sputter erosion depths calculated for the plasma conditions of the test and also with lifetest results. The direct measurement approach is shown to be applicable to both mercury and argon discharge plasma environments and should be useful in estimating the lifetimes of inert gas and extended performance mercury ion thrusters presently under development.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. Extended performance technology study 30-cm thruster

    NASA Technical Reports Server (NTRS)

    Beattie, J. R.

    1983-01-01

    The extended performance technology study was an investigation of advanced discharge chambers and thruster components that were designed to operate under conditions which result in an increase in the thrust and thrust to power ratio of the state of the art J-series thruster. The high level of performance was achieved by a discharge chamber that employs a ring cusp magnetic confinement arrangement and a three grid ion extraction assembly. It is shown that the ring cusp magnetic field geometry confines the plasma to the volume immediately adjacent to the ion extraction assembly. A high emission current hollow cathode that demonstrated operation at an emission current as high as J sub E = 40 A, and measurements which show the breakdown voltage of individual sections of the J-series propellant flow electrical isolator is about 340 V per section are investigated.

  19. A mission profile life test facility. [for mercury ion thrusters

    NASA Technical Reports Server (NTRS)

    James, E.; Vetrone, R.; Bechtel, R.

    1978-01-01

    A test facility is being prepared for a 16,000 hour mission profile life test of multiple electric propulsion thrust subsystems. The facility will be capable of simultaneously operating three 2.7 kW, 30 cm mercury ion thrusters and their power processing. The facility will permit conduction of a program of long-term tests to document thruster characteristics as a function of time and operating point to allow prediction of thruster performance for any mission profile. The thruster will be tested in a 7m by 10m vacuum chamber. Each thruster will be installed in a separate lock chamber so that it can be extended into, or extracted from the main chamber without violating the vacuum integrity of the other thruster. The thrusters will exhaust into a 3m by 5m frozen mercury target. The target and an array of cryopanels to collect sputtered target material will be liquid nitrogen chilled. Power processor units will be tested in an adjacent 1.5m by 2m vacuum chamber and will be temperature controlled by simulated heat pipes.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  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. 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.

  6. 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.

  7. 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.

  8. Ultrasensitive sliver nanorods array SERS sensor for mercury ions.

    PubMed

    Song, Chunyuan; Yang, Boyue; Zhu, Yu; Yang, Yanjun; Wang, Lianhui

    2017-01-15

    With years of outrageous mercury emissions, there is an urgent need to develop convenient and sensitive methods for detecting mercury ions in response to increasingly serious mercury pollution in water. In the present work, a portable, ultrasensitive SERS sensor is proposed and utilized for detecting trace mercury ions in water. The SERS sensor is prepared on an excellent sliver nanorods array SERS substrate by immobilizing T-component oligonucleotide probes labeled with dye on the 3'-end and -SH on the 5'-end. The SERS sensor responses to the specific chemical bonding between thymine and mercury ions, which causes the previous flexible single strand of oligonucleotide probe changing into rigid and upright double chain structure. Such change in the structure drives the dyes far away from the excellent SERS substrate and results in a SERS signal attenuation of the dye. Therefore, by monitoring the decay of SERS signal of the dye, mercury ions in water can be detected qualitatively and quantitatively. The experimental results indicate that the proposed optimal SERS sensor owns a linear response with wide detecting range from 1pM to 1μM, and a detection limit of 0.16pM is obtained. In addition, the SERS sensor demonstrates good specificity for Hg(2+), which can accurately identify trace mercury ions from a mixture of ten kinds of other ions. The SERS sensor has been further executed to analyze the trace mercury ions in tap water and lake water respectively, and good recovery rates are obtained for sensing both kinds of water. With its high selectivity and good portability, the ultrasensitive SERS sensor is expected to be a promising candidate for discriminating mercury ions in the fields of environmental monitoring and food safety.

  9. 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.

  10. Ion composition and kinetics in Mercury's magnetotail (Invited)

    NASA Astrophysics Data System (ADS)

    Gershman, D. J.; Slavin, J. A.; Raines, J. M.; Zurbuchen, T.; Anderson, B. J.; Korth, H.; Baker, D. N.; Solomon, S. C.

    2013-12-01

    We present the first targeted study of the kinetic properties of Mercury's magnetotail plasmas using three-dimensional data from the Fast Imaging Plasma Spectrometer sensor on the MESSENGER spacecraft. The average velocity distribution functions of both solar wind and planetary ions in the plasma sheet are consistent with hot, near-isotropic Maxwellian distributions, enabling an estimation of both density and temperature for each species. Although the temperature and density of the H+-dominated plasma sheet vary over the ranges ~2-20 cm-3 and ~5-30 MK, respectively, they maintain a nearly constant thermal pressure of ~0.75 nPa, sufficient to balance the observed diamagnetic depressions in Mercury's magnetotail magnetic field. Solar wind ions, namely He2+ and O6++C5+, retain near-solar-wind abundances with respect to H+ and exhibit mass-proportional ion temperatures. Conversely, planetary ion species such as He+, O+, and Na+ are accelerated to approximately the same average energies. Substantial heavy ion plasma content in the pre-midnight plasma sheet suggests that planetary ions may asymmetrically mass-load Mercury's magnetotail, though it remains to be seen whether the predicted quasi-adiabaticity of these ions permits them to dynamically influence the ambient plasma. No such asymmetry with respect to local midnight is evident in the measured planetary ion temperatures. The temperature of He2+ is strongly correlated with that of H+ in the plasma sheet, which scales linearly with upstream solar wind speed (vsw) due to the conversion of solar wind ram pressure to plasma thermal pressure across Mercury's bow shock. The temperature of Na+-group ions, however, increases only linearly with solar wind speed for vsw < 500 km/s. For vsw > 500 km/s, the temperature of Na+ remains near ~25 MK, suggesting the presence of a saturation effect in the energization process of planetary ions at Mercury.

  11. 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.

  12. Optical properties of mercury ion thruster exhaust plumes Significance for candidate SEP science instruments. [Solar Electric Propulsion

    NASA Technical Reports Server (NTRS)

    Goldstein, R.; Monahan, K. M.

    1975-01-01

    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 emission 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. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. Functionalized diatom silica microparticles for removal of mercury ions

    PubMed Central

    Yu, Yang; Addai-Mensah, Jonas; Losic, Dusan

    2012-01-01

    Diatom silica microparticles were chemically modified with self-assembled monolayers of 3-mercaptopropyl-trimethoxysilane (MPTMS), 3-aminopropyl-trimethoxysilane (APTES) and n-(2-aminoethyl)-3-aminopropyl-trimethoxysilane (AEAPTMS), and their application for the adsorption of mercury ions (Hg(II)) is demonstrated. Fourier transform infrared spectroscopy and x-ray photoelectron spectroscopy analyses revealed that the functional groups (–SH or –NH2) were successfully grafted onto the diatom silica surface. The kinetics and efficiency of Hg(II) adsorption were markedly improved by the chemical functionalization of diatom microparticles. The relationship among the type of functional groups, pH and adsorption efficiency of mercury ions was established. The Hg(II) adsorption reached equilibrium within 60 min with maximum adsorption capacities of 185.2, 131.7 and 169.5 mg g−1 for particles functionalized with MPTMS, APTES and AEAPTMS, respectively. The adsorption behavior followed a pseudo-second-order reaction model and Langmuirian isotherm. These results show that mercapto- or amino-functionalized diatom microparticles are promising natural, cost-effective and environmentally benign adsorbents suitable for the removal of mercury ions from aqueous solutions. PMID:27877475

  18. Naked-eye sensor for rapid determination of mercury ion.

    PubMed

    Liu, Jing; Wu, Dapeng; Yan, Xiaohui; Guan, Yafeng

    2013-11-15

    A naked-eye paper sensor for rapid determination of trace mercury ion in water samples was designed and demonstrated. The mercury-sensing rhodamine B thiolactone was immobilized in silica matrices and the silica matrices were impregnated firmly and uniformly in the filter paper. As water samples flow through the filter paper, the membrane color will change from white to purple red, which could be observed obviously with naked eye, when concentration of mercury ions equals to or exceeds 10nM, the maximum residue level in drinking water recommended by U.S. EPA. The color change can also be recorded by a flatbed scanner and then digitized, reducing the detection limit of Hg(2+) down to 1.2 nM. Moreover, this method is extremely specific for Hg(2+) and shows a high tolerance ratio of interferent coexisting ions. The presence of Na(+) (2 mM), K(+) (2 mM), Fe(3+) (0.1 mM), Zn(2+) (0.1 mM), Mg(2+) (0.1 mM), Ni(2+) (50 μM), Co(2+) (50 μM), Cd(2+) (50 μM), Pb(2+) (50 μM), Cu(2+) (50 μM) and Ag(+) (3.5 μM) did not interfere with the detection of Hg(2+) (25 nM). Finally, the present method was applied in the detection of Hg(2+) in mineral water, tap water and pond water.

  19. Extended Performance 8-cm Mercury Ion Thruster

    NASA Technical Reports Server (NTRS)

    Mantenieks, M. A.

    1981-01-01

    A slightly modified 8-cm Hg ion thruster demonstrated significant increase in performance. Thrust was increased by almost a factor of five over that of the baseline thruster. Thruster operation with various three grid ion optics configurations; thruster performance as a function of accelerator grid open area, cathode baffle, and cathode orifice size; and a life test of 614 hours at a beam current of 250 mA (17.5 mN thrust) are discussed. Highest thruster efficiency was obtained with the smallest open area accelerator grid. The benefits in efficiency from the low neutral loss grids were mitigated, however, by the limitation such grids place on attainable ion beam current densities. The thruster components suffered negligible weight losses during a life test, which indicated that operation of the 8-cm thruster at extended levels of thrust and power is possible with no significant loss of lifetime.

  20. 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.

  1. Ion-Scale Structure in Mercury's Magnetopause Reconnection Diffusion Region

    NASA Technical Reports Server (NTRS)

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

    2016-01-01

    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 approximately 150 milliseconds 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 approximately 0.3 to 3 millivolts per meter reconnection electric fields separated by approximately 5 to10 seconds, resulting in average and peak normalized dayside reconnection rates of approximately 0.02 and approximately 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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+}.

  6. 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.

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

    PubMed

    Vondrasek, R; Pardo, R; Scott, R

    2013-11-01

    An electron cyclotron resonance ion source has been utilized to produce mercury beams with intensities of 4.5 eμA of (202)Hg(29+) and 3.0 eμA of (202)Hg(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.

  8. Mercury

    MedlinePlus

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

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

    PubMed

    Tjoelker, Robert; Prestage, John; Burt, Eric; Chen, Pin; Chong, Yong; Chung, Sang; Diener, William; Ely, Todd; Enzer, Daphna; Mojaradi, Hadi; Okino, Clayton; Pauken, Mike; Robison, David; Swenson, Brad; Tucker, Blake; Wang, R

    2016-03-21

    There are many different atomic frequency standard technologies but few meet the demanding performance, reliability, size, mass, and power constraints required for space operation. JPL is developing a linear ion trap based mercury ion clock, referred to as DSAC (Deep Space Atomic Clock) under NASA's Technology Demonstration Mission (TDM) 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 liters, 16 kilograms, and 47 Watts respectively, with further reductions planned for follow-on applications. Clock performance with an SNR*Q limited stability of 1.5E-13/τ1/2 has been observed and a fractional frequency stability of 2E-15 at 1 day measured (no drift removed). Such a space based stability enables autonomous timekeeping of Δt<0.2 ns/day 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 electro-magnetic susceptibility tests.

  10. Reaction-based two-photon probes for mercury ions: fluorescence imaging with dual optical windows.

    PubMed

    Rao, Alla Sreenivasa; Kim, Dokyoung; Wang, Taejun; Kim, Ki Hean; Hwang, Sekyu; Ahn, Kyo Han

    2012-05-18

    For fluorescent imaging of mercury ions in living species, two-photon probes with dual optical windows are in high demand but remain unexplored. Several dithioacetals were evaluated, and a probe was found, which, upon reaction with mercury species, yielded a two-photon dye; this conversion accompanies ratiometric emission changes with a 97-nm shift, enabling fluorescent imaging of both the probe and mercury ions in cells by one- and two-photon microscopy for the first time.

  11. 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.

  12. Sodium ions circulation in the magnetosphere of Mercury and its contribution to ion sputtering.

    NASA Astrophysics Data System (ADS)

    Mura, Alessandro; Wurz, Peter; Lammer, Helmut; Orsini, Stefano; Milillo, Anna; Massetti, Stefano; Mangano, Valeria; Lichtenegger, Herbert; Khodachenko, Maxim

    2014-05-01

    Here we present the result of our model for the circulation of Sodium ions in the magnetosphere of Mercury. Magnetospheric Na+ ions are the results of the photon ionization of the neutral Na exosphere. We first use a Na exospheric model as a source; then we simulate the Na+ circulation using a single particle Montecarlo model, which takes into account the latest findings from the MESSENGER mission. The Na+ densities and fluxes are computed inside the whole magnetosphere. A subset of the simulated data, corresponding to the MESSENGER orbit, is compared against the data from MESSENGER FIPS instrument, showing a good agreement. Then, the validated Na+ circulation model is used to estimate the Na+ flux onto the surface of Mercury. The precipitation of heavy planetary ions, in fact, is believed to give a substantial contribution to the sputtering process on the surface of Mercury (Delcourt et al., 2003), comparable with that from the precipitation of solar wind plasma. In fact, Na+ ions have a larger sputtering yield compared with that of protons. The results, in terms of sputtered fluxes and generated neutral exosphere, are presented.

  13. 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.

  14. Preparation of amine group-containing chelating fiber for thorough removal of mercury ions.

    PubMed

    Ma, Nianfang; Yang, Ying; Chen, Shuixia; Zhang, Qikun

    2009-11-15

    An aminated chelating fiber (AF) with high adsorption capacity for mercury ions was prepared by grafting copolymerization of acrylonitrile onto polypropylene fiber, followed by aminating with chelating molecule diethylenetriamine. Effects of reaction conditions such as temperature, reaction time, bath ratio and dosage of catalyst on the grafting yield were studied. Chemical structure, tensile strength and thermal stability of AF were characterized. The adsorption performances for mercury were evaluated by batch adsorption experiments and kinetic experiments. The results show that AF is effective for the removal of mercury over a wide range of pH. The chelating fiber also shows much higher adsorption capacities for mercury, the equilibrium adsorption amount could be as high as 657.9 mg/g for mercury. The high adsorption capacity of Hg(2+) on AF is resulted from the strong chelating interaction between amine groups and mercury ions. Two amine groups coordinate with one mercury ion could be speculated from the adsorption capacity and amine group content on AF. The kinetic adsorption results indicate that the adsorption rates of AF for mercury are very rapid. Furthermore, the residual concentration was less than 1 microg/L with feed concentration of mercury below 1mg/L, which can meet the criterion of drinking water, which indicates that the chelating fiber prepared in this study could be applied to low-level Hg contaminated drinking water purification.

  15. Mercury

    MedlinePlus

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

  16. Results of a 1000-hour wear test of 30-cm carbon-carbon ion optics

    NASA Technical Reports Server (NTRS)

    Snyder, John Steven; Brophy, John R.; Anderson, John R.

    2005-01-01

    This paper discusses the results of a 1000-hour wear test intended to determine the erosion resistance and voltage standoff capability of the optics in a relevant environment, i.e. duration testing on an NSTAR-like thruster.

  17. 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.

  18. 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

    2014-07-09

    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.

  19. 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

  20. 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.

  1. 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.

  2. Preliminary results of the mission profile life test of a 30 cm Hg bombardment thruster

    NASA Technical Reports Server (NTRS)

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

    1979-01-01

    Long term tests were performed on a 30 cm Hg bombardment thruster and a power processing unit to determine lifetime characteristics. The thruster performance data and other operational characteristics taken at various times during the test segment are presented and evaluated with the life limiting mechanisms: discharge chamber erosion, deposition and spalling, external erosion, cathode degradation, and propellant isolator leakage. The control algorithms for thruster start up, steady state operation, throttle, detection and correction of off normal conditions, and shutdown are discussed.

  3. Radiation hardness of 30 cm long CsI(Tl) crystals

    NASA Astrophysics Data System (ADS)

    Longo, S.; Roney, J. M.

    2016-08-01

    Measurements of the degradation in performance of 30 cm long CsI(Tl) scintillation crystals exposed to 1 MeV photon doses of 2, 10, 35, 100 and 1000 Gy are presented. The light yield, light yield longitudinal non-uniformity, scintillation decay times, energy resolution and timing resolution of a set of spare crystals from the BABAR and Belle experiments are studied as a function of these doses. In addition, a model that describes the plateau observed in the light output loss as a function of dose in terms of increase in concentrations of absorption centres with irradiation is presented.

  4. A multiple thruster array for 30-cm thrusters. [propulsion system performance

    NASA Technical Reports Server (NTRS)

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

    1975-01-01

    A 3.0 m diameter chamber of the 7.6 m diameter by 21.4 m long vacuum tank was modified to permit testing of an array of up to six 30-cm thrusters with a variety of laboratory and thermal vacuum breadboard 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.

  5. 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.

  6. 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.

  7. 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.

  8. An electrochemical DNA biosensor for trace amounts of mercury ion quantification.

    PubMed

    Maâtouk, Ferdaous; Maâtouk, Mouna; Bekir, Karima; Barhoumi, Houcine; Maaref, Abderrazak; Ben Mansour, Hedi

    2016-10-01

    In this work we report the development of an electrochemical DNA biosensor with high sensitivity for mercury ion detection. A new matrix based on gold nanoparticles (AuNPs)-glutathione (GSH)/cysteine was investigated. The interaction between DNA oligonucleotides and Hg(2+) ions followed by the formation of Thymine-Hg(2+)-Thymine (T-Hg(2+)-T) structures was quantified using different electrochemical methods. It has been shown that the electrochemical impedance spectroscopy (EIS) measurements and the differential pulse voltammetry (DPV) confirmed the specific interaction between the oligonucleotide receptor layer and the Hg(2+) ions. Besides, the developed sensor exhibited high sensitivity towards mercury among some examined metal ions such as Pb(2+), Cu(2+) and Cd(2+). As a result, a high electrochemical response and low detection limit of 50 pM were estimated in the case of Hg(2+) ions. The developed DNA biosensor was applied successfully to the determination of Hg(2+)ions in wastewater samples.

  9. 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.

  10. 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

  11. Long Term Multiplication Behavior Studies of the 30cmx 30cm prototype Gas electron Multiplier

    NASA Astrophysics Data System (ADS)

    Ng, Ying Wun Yvonne; Yu, Jaehoon; Park, Seongtae; White, Andy

    2014-03-01

    The Gas Electron Multiplier (GEM) technology is one of the next generation radiation detector technologies that utilized the ionization in gaseous medium and the electron avalanche to detect a magnified charge value from various radiation and charge particles. With its low building cost, low discharge rate and high resolution, GEM is currently being considered to be one of the candidate gap detectors for the International Linear Collider (ILC) in Japan. It is therefore of crucial for us to study the long term stability of amplification power of the detector. Using cosmic radiation as our radiation source, data has been taken continuously in the past 2 years by the high energy physics group in University of Texas at Arlington to characterize the stability of the 30cmx30cm detector. Effect of atmospheric pressure to the detector amplification is eliminated by a correction algorithm. Noise study has been done to eliminate excessive noise produced by the detector as well as its readout chip. Result shows that the detector gives us a stable 35fC average MPV for the cosmic MIPs with few fC of chamber noise and about 0.5 of chip noise. GEM should work well as a digital calorimeter for uses in the ILC project.

  12. The 30 cm radio flux as a solar proxy for thermosphere density modelling

    NASA Astrophysics Data System (ADS)

    Dudok de Wit, Thierry; Bruinsma, Sean

    2017-03-01

    The 10.7 cm radio flux (F10.7) is widely used as a proxy for solar UV forcing of the upper atmosphere. However, radio emissions at other centimetric wavelengths have been routinely monitored since the 1950 s, thereby offering prospects for building proxies that may be better tailored to space weather needs. Here we advocate the 30 cm flux (F30) as a proxy that is more sensitive than F10.7 to longer wavelengths in the UV and show that it improves the response of the thermospheric density to solar forcing, as modelled with DTM (Drag Temperature Model). In particular, the model bias drops on average by 0-20% when replacing F10.7 by F30; it is also more stable (the standard deviation of the bias is 15-40% smaller) and the density variation at the the solar rotation period is reproduced with a 35-50% smaller error. We compare F30 to other solar proxies and discuss its assets and limitations.

  13. 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).

  14. 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.

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

    NASA Astrophysics Data System (ADS)

    Belikov, Ruslan; Acend Team, Acesat Team

    2015-01-01

    Several mission concepts are being 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 (A and B), which is an extreme outlier among FGKM stars in terms of apparent habitable zone size. Specifically, Alpha Centauri habitable zones span about 0.5-1' in stellocentric angle, ~3x wider than around any other FGKM star. This enables a ~30cm visible light space telescope equipped with a modern high performance coronagraph or starshade to resolve the habitable zone at high contrast and directly image any potentially habitable planet that may exist in the system. Due to the extreme apparent brightness of the stars, exposure times can be as short as minutes with ideal components, or days with realistic ones. This makes it possible to do color photometry on potentially habitable planets 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.The raw contrast requirements for such an instrument can be relaxed to 1e-8 if the mission spends 2 years collecting tens of thousands of images on the same target, enabling a factor of 500-1000 speckle suppression in post processing. The light leak from both stars is controllable with a special wavefront control algorithm known as Multi-Star Wavefront Control (MSWC), which independently suppresses diffraction and aberrations from both stars using independent modes on the deformable mirror (see Thomas et al. at this conference).The presentation will describe the general studies and calculations in more detail and briefly present

  16. 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

  17. 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.

  18. Determination of mercury(II) ion by electrochemical cold vapor generation atomic absorption spectrometry.

    PubMed

    Arbab-Zavar, M Hosein; Rounaghi, G Hosein; Chamsaz, Mahmoud; Masrournia, Mahboube

    2003-05-01

    A technique for determination of mercury is described; it is based on electrolytic reduction of Hg(II) ion on a graphite cathode, the trapping of mercury vapor and its volatilization into a quartz tube aligned in the optical path of an atomic absorption spectrometer. The electrochemical cell consisted of a graphite cathode and an anode operating with constant direct current for the production of mercury atoms. A pre-activated graphite rod was used as the cathode material. The optimum conditions for electrochemical generation of mercury cold vapor (the electrolysis time and current, the flow rate, the type of electrode and electrolyte) were investigated. The characteristic electrochemical data with chemical cold vapor using NaBH4-acid were compared. The presence of cadmium(II), arsenic(III), antimony(III), selenium(IV), bismuth(III), silver(I), lead(II), lithium(I), sodium(I) and potassium(I) showed interference effects which were eliminated by suitable separation techniques. The calibration curve is linear over the range of 5-90 ng ml(-1) mercury(II). The detection limit is 2 ng ml(-1) of Hg(II) and the RSD is 2.5% (n = 10) for 40 ng ml(-1). The accuracy and recovery of the method were investigated by analyzing spiked tap water and river water.

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

    PubMed Central

    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 Hg2+ 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

  20. Old tree with new shoots: silver nanoparticles for label-free and colorimetric mercury ions detection

    NASA Astrophysics Data System (ADS)

    Gao, Shuyan; Jia, Xiaoxia; Chen, Yanli

    2013-01-01

    Mercury in the environment from global mercury emissions as well as various forms of contamination poses severe threats to both human health and the environment. Long-term exposure to high levels of Hg-based toxins results in serious and irreversible damage of the central nervous system and other organs. Therefore, the development of effective sensing systems for mercury detection becomes an increasing demand. In this article, a yogurt-mediated silver nanostructure is reported to be unprecedentedly used in the naked-eye and label-free detection of mercury. The method relies on the redox reaction resulting from the electrode potential difference between Ag+/Ag (0.7996 V) and Hg2+/Hg2 2+ (0.920 V) that makes colorless Hg2+ ions which oxidize colored silver nanoparticle (AgNP) to colorless Ag+. The labor-intensive modification of AgNPs and expensive labeling are avoided, and the traditional AuNPs are substituted by AgNPs in this Hg2+ ions sensing platform, which makes it facile, low-cost, and particularly useful for home, clinic, or field applications as well as resource-limited conditions. This sensing system achieves a detection limit as low as 10 nM, lower than the toxicity level of Hg2+ ions in drinking water (30 nM) defined by World Health Organization, and exhibits excellent selectivity, largely free from the matrix effect of the real water samples. This visual label-free Hg2+ ions sensing motif shows great promise for sensing Hg2+ ions in terms of sensitivity, selectivity, cost, and maneuverability. It is also a good example for the organic combination of green chemistry and functional materials, which may trigger interest in furthering biosystems for environmental science applications.

  1. 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.

  2. Mercury

    NASA Technical Reports Server (NTRS)

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

    1977-01-01

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

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  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. 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.

  13. 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.

  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. 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+).

  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/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.

  17. Mercury removal from water streams through the ion exchange membrane bioreactor concept.

    PubMed

    Oehmen, Adrian; Vergel, Dario; Fradinho, Joana; Reis, Maria A M; Crespo, João G; Velizarov, Svetlozar

    2014-01-15

    Mercury is a highly toxic heavy metal that causes human health problems and environmental contamination. In this study, an ion exchange membrane bioreactor (IEMB) process was developed to achieve Hg(II) removal from drinking water and industrial effluents. Hg(II) transport through a cation exchange membrane was coupled with its bioreduction to Hg(0) in order to achieve Hg removal from concentrated streams, with minimal production of contaminated by-products observed. This study involves (1) membrane selection, (2) demonstration of process effectiveness for removing Hg from drinking water to below the 1ppb recommended limit, and (3) process application for treatment of concentrated water streams, where >98% of the Hg was removed, and the throughput of contaminated water was optimised through membrane pre-treatment. The IEMB process represents a novel mercury treatment technology with minimal generation of contaminated waste, thereby reducing the overall environmental impact of the process.

  18. 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. This paper presents the cycle life test results and also 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.

  19. 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.

  20. [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.

  1. Rhodamine functionalized magnetic core-shell nanocomposite: An emission 'Off-On' sensing system for mercury ion detection and extraction

    NASA Astrophysics Data System (ADS)

    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.

  2. 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

    2015-10-05

    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.

  3. 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

  4. 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.

  5. Selective detection of mercury (II) ion using nonlinear optical properties of gold nanoparticles.

    PubMed

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

    2008-06-25

    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 Hg(2+) 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(+), Mg(2+), Ca(2+)), and transition heavy metal ions (Pb(2+), Pb(+), Mn(2+), Fe(2+), Cu(2+), Ni(2+), Zn(2+), Cd(2+)).

  6. Simple and rapid mercury ion selective electrode based on 1-undecanethiol assembled Au substrate and its recognition mechanism.

    PubMed

    Li, Xian-Qing; Liang, Hai-Qing; Cao, Zhong; Xiao, Qing; Xiao, Zhong-Liang; Song, Liu-Bin; Chen, Dan; Wang, Fu-Liang

    2017-03-01

    A simple and rapid mercury ion selective electrode based on 1-undecanethiol (1-UDT) assembled Au substrate (Au/1-UDT) has been well constructed. 1-UDT was for the purpose of generating self-assembled monolayer on gold surface to recognize Hg(2+) in aqueous solution, which had a working concentration range of 1.0×10(-8)-1.0×10(-4)molL(-1), with a Nernst response slope of 28.83±0.4mV/-pC, a detection limit of 4.5×10(-9)molL(-1), and a good selectivity over the other tested cations. Also, the Au/1-UDT possessed good reproducibility, stability, and short response time. The recovery obtained for the determination of mercury ion in practical tremella samples was in the range of 99.8-103.4%. Combined electrochemical analysis and X-ray photoelectron spectroscopy (XPS) with quantum chemical computation, the probable recognition mechanism of the electrode for selective recognition of Hg(2+) has been investigated. The covalent bond formed between mercury and sulfur is stronger than the one between gold and sulfur and thus prevents the adsorption of 1-UDT molecules on the gold surface. The quantum chemical computation with density functional theory further demonstrates that the strong interaction between the mercury atom and the sulfur atom on the gold surface leads to the gold sulfur bond ruptured and the gold mercury metallophilic interaction.

  7. A selective fluorescence probe for mercury ion based on the fluorescence quenching of terbium(III)-doped cadmium sulfide composite nanoparticles.

    PubMed

    Fu, Jie; Wang, Lun; Chen, Hongqi; Bo, Ling; Zhou, Cailing; Chen, Jingguo

    2010-10-15

    A fluorescent probe for mercury(II) ions, based on the quenching of fluorescence of terbium(III) ions doped in CdS nanoparticles, has been developed. The terbium(III)-doped cadmium sulfide composite nanoparticles were successfully synthesized through a straightforward one-pot process, with the biomolecule glutathione (GSH) as a capping ligand. In addition, the terbium(III) ions were observed an enhancement of emission intensity, owing to fluorescence energy transfer from the excited CdS particles to the emitting terbium(III). Because of a specific interaction, the fluorescence intensity of terbium(III)-doped CdS particles is obviously reduced in the presence of mercury(II) ions. The fluorescence quenching phenomenon of terbium(III) can be attributed to the fact that the energy transfer system was destroyed by combining with mercury(II). Under the optimal conditions, the fluorescent intensity of terbium(III) ions at 491nm decreased linearly with the concentration of mercury(II) ions ranging from 4.5nmolL(-1) to 550nmolL(-1). The limit of detection for mercury(II) was 0.1nmolL(-1). This method is simple, practical, relatively free of interference from coexisting substances and can be successfully applied to the determination of mercury(II) ions in real water samples. In addition, the probable mechanism of reaction between terbium(III)-doped CdS composite nanoparticles and mercury(II) was also discussed.

  8. New cellulose-lysine Schiff-base-based sensor-adsorbent for mercury ions.

    PubMed

    Kumari, Sapana; Chauhan, Ghanshyam S

    2014-04-23

    Mercury is a highly toxic environmental pollutant; thus, there is an urgent need to develop new materials for its simultaneous detection and removal from water. In the present study, new oxidized cellulose-based materials, including their Schiff bases, were synthesized and investigated as a sensor-adsorbent for simple, rapid, highly selective, and simultaneous detection and removal of mercury [Hg(II)] ions. Cellulose was extracted from the pine needles, etherified, oxidized, and modified to Schiff base by reaction with l-lysine. The well-characterized cellulose Schiff base materials were used as a sensor-adsorbent for Hg(II) from aqueous solution. Hg(II) sensing was analysed with naked-eye detection and fluorescence spectroscopy. Schiff base having a decyl chain, C10-O-cell-HC═N-Lys, was observed to be an efficient adsorbent with a very high maximum adsorption capacity of 258.75 mg g(-1). The data were analyzed on the basis of various kinetic and isotherm models, and pseudo-second-order kinetics and Langmuir isotherm were followed for Hg(II) adsorption.

  9. 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.

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

    PubMed Central

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

    2013-01-01

    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. PMID:24178058

  11. 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.

  12. HG ion thruster component testing

    NASA Technical Reports Server (NTRS)

    Mantenieks, M. A.

    1979-01-01

    Cathodes, isolators, and vaporizers are critical components in determining the performance and lifetime of mercury ion thrusters. The results of life tests of several of these components are reported. A 30-cm thruster CIV test in a bell jar has successfully accumulated over 26,000 hours. The cathode has undergone 65 restarts during the life test without requiring any appreciable increases in starting power. Recently, all restarts have been achieved with only the 44 volt keeper supply with no change required in the starting power. Another ongoing 30-cm Hg thruster cathode test has successfully passed the 10,000 hour mark. A solid-insert, 8-cm thruster cathode has accumulated over 4,000 hours of thruster operation. All starts have been achieved without the use of a high voltage ignitor. The results of this test indicate that the solid impregnated insert is a viable neutralizer cathode for the 8-cm thruster.

  13. 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.

  14. Enhanced and selective adsorption of mercury ions on chitosan beads grafted with polyacrylamide via surface-initiated atom transfer radical polymerization.

    PubMed

    Li, Nan; Bai, Renbi; Liu, Changkun

    2005-12-06

    Enhanced and selective removal of mercury ions was achieved with chitosan beads grafted with polyacrylamide (chitosan-g-polyacrylamide) via surface-initiated atom transfer radical polymerization (ATRP). The chitosan-g-polyacrylamide beads were found to have significantly greater adsorption capacities and faster adsorption kinetics for mercury ions than the chitosan beads. At pH 4 and with initial mercury concentrations of 10-200 mg/L, the chitosan-g-polyacrylamide beads can achieve a maximum adsorption capacity of up to 322.6 mg/g (in comparison with 181.8 mg/g for the chitosan beads) and displayed a short adsorption equilibrium time of less than 60 min (compared to more than 15 h for the chitosan beads). Coadsorption experiments with both mercury and lead ions showed that the chitosan-g-polyacrylamide beads had excellent selectivity in the adsorption of mercury ions over lead ions at pH < 6, in contrast to the chitosan beads, which did not show clear selectivity for either of the two metal species. Mechanism study suggested that the enhanced mercury adsorption was due to the many amide groups grafted onto the surfaces of the beads, and the selectivity in mercury adsorption can be attributed to the ability of mercury ions to form covalent bonds with the amide. It was found that adsorbed mercury ions on the chitosan-g-polyacrylamide beads can be effectively desorbed in a perchloric acid solution, and the regenerated beads can be reused almost without any loss of adsorption capacity.

  15. Simultaneous bioremediation and biodetection of mercury ion through surface display of carboxylesterase E2 from Pseudomonas aeruginosa PA1.

    PubMed

    Yin, Kun; Lv, Min; Wang, Qiaoning; Wu, Yixuan; Liao, Chunyang; Zhang, Weiwei; Chen, Lingxin

    2016-10-15

    Mercury is a toxic heavy metal and presents significant threats to organisms and natural ecosystems. Recently, the mercury remediation as well as its detection by environmental-friendly biotechnology has received increasing attention. In this study, carboxylesterase E2 from mercury-resistant strain Pseudomonas aeruginosa PA1 has been successfully displayed on the outer membrane of Escherichia coli Top10 bacteria to simultaneously adsorb and detect mercury ion (Hg(2+)). The transmission electron microscopy analysis shows that Hg(2+) can be absorbed by carboxylesterase E2 and accumulated on the outer membrane of surface-displayed E. coli bacteria. The adsorption of Hg(2+) followed a physicochemical, equilibrated and saturatable mechanism, which well fits the traditional Langmuir adsorption model. The surface-displayed system can be regenerated through regulating pH values. As its activity can be inhibited by Hg(2+), carboxylesterase E2 has been used to detect the concentration of Hg(2+) in water samples. The developed surface display system will be of great potential in the simultaneous bioremediation and biodetection of environmental mercury pollution.

  16. Alkaline hydrothermal conversion of fly ash precipitates into zeolites 3: the removal of mercury and lead ions from wastewater.

    PubMed

    Somerset, Vernon; Petrik, Leslie; Iwuoha, Emmanuel

    2008-04-01

    In this paper, the utilisation of zeolites synthesised from fly ash (FA) and related co-disposal filtrates as low-cost adsorbent material were investigated. When raw FA and co-disposal filtrates were subjected to alkaline hydrothermal zeolite synthesis, the zeolites faujasite, sodalite and zeolite A were formed. The synthesised zeolites were explored to establish its ability to remove lead and mercury ions from aqueous solution in batch experiments, to which various dosages of the synthesised zeolites were added. The test results indicated that when increasing synthesised zeolite dosages of 5-20 g/L were added to the acid mine drainage (AMD) wastewater, the concentrations of lead and mercury in the wastewater were reduced accordingly. The lead concentrations were reduced from 3.23 to 0.38 and 0.17 microg/kg, respectively, at an average pH of 4.5, after the addition of raw FA zeolite and co-disposal filtrate zeolite to the AMD wastewater. On the other hand, the mercury concentration was reduced from 0.47 to 0.17 microg/kg at pH=4.5 when increasing amounts of co-disposal filtrate zeolite were added to the wastewater. The experimental results had shown that the zeolites synthesised from the co-disposal filtrates were effective in reducing the lead and mercury concentrations in the AMD wastewater by 95% and 30%, respectively.

  17. 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.

  18. 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).

  19. 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.

  20. Highly sensitive electrochemical sensor for mercury(II) ions by using a mercury-specific oligonucleotide probe and gold nanoparticle-based amplification.

    PubMed

    Zhu, Zhiqiang; Su, Yuanyuan; Li, Jiang; Li, Di; Zhang, Jiong; Song, Shiping; Zhao, Yun; Li, Genxi; Fan, Chunhai

    2009-09-15

    We report a highly sensitive electrochemical sensor for the detection of Hg(2+) ions in aqueous solution by using a thymine (T)-rich, mercury-specific oligonucleotide (MSO) probe and gold nanoparticles (Au NPs)-based signal amplification. The MSO probe contains seven thymine bases at both ends and a "mute" spacer in the middle, which, in the presence of Hg(2+), forms a hairpin structure via the Hg(2+)-mediated coordination of T-Hg(2+)-T base pairs. The thiolated MSO probe is immobilized on Au electrodes to capture free Hg(2+) in aqueous media, and the MSO-bound Hg(2+) can be electrochemically reduced to Hg(+), which provides a readout signal for quantitative detection of Hg(2+). This direct immobilization strategy leads to a detection limit of 1 microM. In order to improve the sensitivity, MSO probe-modified Au NPs are employed to amplify the electrochemical signals. Au NPs are comodified with the MSO probe and a linking probe that is complementary to a capture DNA probe immobilized on gold electrodes. We demonstrated that this Au NPs-based sensing strategy brings about an amplification factor of more than 3 orders of magnitude, leading to a limit of detection of 0.5 nM (100 ppt), which satisfactorily meets the sensitivity requirement of U.S. Environmental Protection Agency (EPA). This Au NPs-based Hg(2+) sensor also exhibits excellent selectivity over a spectrum of interference metal ions. Considering the high sensitivity and selectivity of this sensor, as well as the cost-effective and portable features of electrochemical techniques, we expect this Au NPs amplified electrochemical sensor will be a promising candidate for field detection of environmentally toxic mercury.

  1. 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 10 ng/L-1.0 µg/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.

  2. High reliability cathode heaters for ion thrusters

    NASA Technical Reports Server (NTRS)

    Mueller, L. A.

    1976-01-01

    A number of space missions have been proposed which will utilize 30-cm mercury bombardment ion thrusters and also will require a large number of thruster restarts. A test program was carried out to determine thermal cycle life of several different cathode heater designs. Plasma/flame sprayed heaters and swaged type heaters were tested. Four of the five plasma/flame sprayed heaters tested failed in a comparatively short time. Four tantalum swaged heaters that were brazed to the tantalum cathode tube were successfully tested and met the goals that were set at the start of the test.

  3. High reliability cathode heaters for ion thrusters

    NASA Technical Reports Server (NTRS)

    Mueller, L. A.

    1976-01-01

    A number of space missions were proposed which utilize 30-cm mercury bombardment ion thrusters and also require a large number of thruster restarts. A test program was carried out to determine thermal cycle life of several different cathode heater designs. Plasma/flame sprayed heaters and swaged type heaters were tested. Four of the five plasma/flame sprayed heaters tested failed in a comparatively short time. Four tantalum swaged heaters that were brazed to the tantalum cathode tube were successfully tested and met the goals that were set at the start of the test.

  4. Sensitive detection for coralyne and mercury ions based on homo-A/T DNA by exonuclease signal amplification.

    PubMed

    Huang, Hailiang; Shi, Shuo; Zheng, Xuyue; Yao, Tianming

    2015-09-15

    Based on specific homo-A/T DNA binding properties, a strategy for coralyne and mercury ions detection was realised by exonuclease-aided signal amplification. Coralyne could specifically bind homo-A DNA and protect it from the hydrolysis of exonuclease I. The coralyne-protected DNA was subsequently used as a trigger strand to hydrolyze DNA2 in exonuclease-aided signal amplification process. Thiazole orange was used to quantify the remainder DNA2. Under the optimal condition, the fluorescence intensity was linearly proportional to the concentration of coralyne in the range of 0.2-100 nM with a limit of detection (LOD) of 0.31 nM, which presented the lowest LOD for coralyne among all reported. With homo-T and Hg(2+) taking the place of homo-A DNA and coralyne, respectively, the system could also be used for Hg(2+) detection. The experiments in real samples also showed good results. This method was label-free, low-cost, easy-operating and highly repeatable for the detection of coralyne and mercury ions. It could also be extended to detect various analytes, such as other metal ions, proteins and small molecules by using appropriate aptamers.

  5. A nano-graphite-DNA hybrid sensor for magnified fluorescent detection of mercury(II) ions in aqueous solution.

    PubMed

    Wei, Yin; Li, Bianmiao; Wang, Xu; Duan, Yixiang

    2014-04-07

    In this communication, we present a nano-graphite-DNA hybrid sensor for fluorescent detection of mercury(II) ions in aqueous solution for the first time. Furthermore, an amplification strategy based on nano-graphite for Hg(2+) detection by using DNase I was demonstrated. The proposed amplified assay was simple and cost-effective with a limit of detection (LOD) for Hg(2+) of 0.5 nM, which was about 20-fold lower than that of traditional unamplified homogeneous assays. We further demonstrated its practical application to detect Hg(2+) in a real sample.

  6. Mercury ions complexation with a series of heterocyclic derivatives of 3-hydroxychromone: spectral effects and prospects for ultrasensitive Hg2+ probing.

    PubMed

    Svechkarev, Denis; Dereka, Bogdan; Doroshenko, Andrey

    2011-05-05

    Complexation of three 3-hydroxychromone derivatives bearing a nitrogen-containing heterocyclic moiety in the position 2 of the chromone bicycle - benzimidazole, quinoline, and 2,5-diphenyloxazole, with mercury(II) ions is reported. Formation of chelate complexes with the metal cations coordinated with the cavity formed by 3-OH and 4-C═O groups was shown, as well as the possibility of side moiety heteroatom participation in binding of metal ions. High sensitivity to mercury of 2,5-diphenyloxazole-substituted 3-hydroxychromone was elucidated, allowing to detect Hg(2+) below the maximum permissible concentration for drinking water. This makes the above-mentioned compound a prospective basis for development of sensors for ultralow mercury concentration detection in water. Unusual fluorescence ignition of 2-(quinolin-2-yl)-3-hydroxychromone at low Hg(2+) concentrations, rarely observed for heavy metals ions complexation with organic fluorescent ligands, was discussed.

  7. 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

    2014-04-07

    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.

  8. Highly selective and quantitative colorimetric detection of mercury(II) ions by carrageenan-functionalized Ag/AgCl nanoparticles.

    PubMed

    Narayanan, Kannan Badri; Han, Sung Soo

    2017-03-15

    The natural algal polysaccharide carrageenan was used for the greener synthesis of silver/silver chloride nanoparticles (Carr-Ag/AgCl NPs) without any toxic chemicals. We report the robust, highly selective, and sensitive colorimetric sensing of Hg(2+) ions using Carr-Ag/AgCl NPs without any further surface modification. The dark-brown color of a solution of Carr-Ag/AgCl NPs turned to white in a concentration-dependent manner with the addition of Hg(2+) ions, confirming the interaction of Carr-Ag/AgCl NPs with Hg(2+) ions. The plot of the extinction ratio of absorbance at 350nm to 450nm (A350/A450) for Carr-Ag/AgCl NPs against the concentration of [Hg(2+)] ions was linear, and the calibration curve was A350/A450=1.05254+0.00318×CHg with a lower detection limit of 1μM. This portable and cost-effective method for mercury(II) ion sensing is widely applicable in on-field qualitative and quantitative measurements of [Hg(2+)] ions in environmental or biological samples.

  9. Synthesis of a novel fluorescent sensor bearing dansyl fluorophores for the highly selective detection of mercury (II) ions.

    PubMed

    Wanichacheva, Nantanit; Watpathomsub, Supranee; Lee, Vannajan Sanghiran; Grudpan, Kate

    2010-03-12

    A new macromolecule possessing two dansyl moieties and based on 2-[4-(2-aminoethylthio)butylthio]ethanamine was prepared as a fluorescent sensor and its mercury sensing properties toward various transition metal, alkali, and alkali earth ions were investigated. The designed compound exhibited pronounced Hg2+-selective ON-OFF type fluorescence switching upon binding. The new compound provided highly selective sensing to Hg2+ in acetonitrile-water solvent mixtures with a detection limit of 2.49 x 10(-7) M or 50 ppb. The molecular modeling results indicated that ions-recognition of the sensor originated from a self assembly process of the reagent and Hg2+ to form a helical wrapping structure with the favorable electrostatic interactions of Hg2+coordinated with sulfur, oxygen, nitrogen atoms and aromatic moieties.

  10. 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.

  11. Investigations on the binding of mercury ions to albumins employing differential pulse voltammetry.

    PubMed

    Castro, Clarissa Silva Pires de; SouzaDe, Jurandir Rodrigues; Bloch, Carlos

    2003-04-01

    Binding of mercury to BSA and Ovalbumin was investigated by Differential Pulse Voltammetry. The method relies on the direct monitoring of peak current variation due to mercury oxidation in the presence of these two albumins. Linear calibration graphs were obtained for both BSA and Ovalbumin in concentrations ranging from 2.49 x 10(-9) to 19.6 x 10(-9) mol L(-1). The acquired data was used to quantify these two proteins independently and to calculate the dissociation constants of Hg-BSA and Hg-Ovalbumin complexes.

  12. 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.

  13. 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)

  14. 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.

  15. 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.

  16. Redox kinetic measurements of glutathione at the mercury electrode by means of square-wave voltammetry. The role of copper, cadmium and zinc ions.

    PubMed

    Mladenov, Mitko; Mirceski, Valentin; Gjorgoski, Icko; Jordanoski, Blagoja

    2004-12-01

    The electrode reaction of glutathione (GSH) at the hanging mercury drop electrode is studied by means of square-wave voltammetry (SWV). At potentials more positive than -0.350 V (vs. Ag/AgCl (3 mol/l KCl)) the oxidation of the mercury electrode in the presence of GSH leads to creation of a sparingly soluble mercury-GSH complex that deposits onto the electrode surface. Under cathodic potential scan, the deposited complex acts as a reducible reactant, giving raise to a well-defined cathodic stripping reversible SW voltammetric response. The electrode reaction can be described by the scheme: Hg(SG)(2(s))+e(-)+2H((aq))(+) = Hg((l))+2GSH((aq)). Thus, the electrode reaction provides information on both thermodynamics and kinetics of the chemical interactions of GSH with mercury. An experimental methodology for measuring the kinetics of the electrode reactions, based on the property known as "quasireversible maximum", is developed. The standard redox rate constant is 5.09, 5.75 and 5.22 cm s(-1) in a phosphate buffer at pH 5.6, 7.0 and 8.5, respectively, with a precision of +/-10%. The high rate of the electrode reaction reflects the strong affinity of GSH towards chemical interaction with mercury. The electrode reaction is particularly sensitive to the presence of heavy metal ions such as Cu(2+), Cd(2+), and Zn(2+.) The rate of the electrode reaction decreases significantly in the presence of these ions due to simultaneous interactions of GSH with the respective ion and mercury.

  17. 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

    2015-11-03

    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.

  18. 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.

  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. 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.

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

    PubMed

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

    2015-10-28

    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 Hg(2+).

  2. 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.

  3. 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.

  4. 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

  5. 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.

  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. 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.

  8. 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.

  9. 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.

  10. 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.

  11. Trace-level mercury ion (Hg2+) analysis in aqueous sample based on solid-phase extraction followed by microfluidic immunoassay.

    PubMed

    Date, Yasumoto; Aota, Arata; Terakado, Shingo; Sasaki, Kazuhiro; Matsumoto, Norio; Watanabe, Yoshitomo; Matsue, Tomokazu; Ohmura, Naoya

    2013-01-02

    Mercury is considered the most important heavy-metal pollutant, because of the likelihood of bioaccumulation and toxicity. Monitoring widespread ionic mercury (Hg(2+)) contamination requires high-throughput and cost-effective methods to screen large numbers of environmental samples. In this study, we developed a simple and sensitive analysis for Hg(2+) in environmental aqueous samples by combining a microfluidic immunoassay and solid-phase extraction (SPE). Using a microfluidic platform, an ultrasensitive Hg(2+) immunoassay, which yields results within only 10 min and with a lower detection limit (LOD) of 0.13 μg/L, was developed. To allow application of the developed immunoassay to actual environmental aqueous samples, we developed an ion-exchange resin (IER)-based SPE for selective Hg(2+) extraction from an ion mixture. When using optimized SPE conditions, followed by the microfluidic immunoassay, the LOD of the assay was 0.83 μg/L, which satisfied the guideline values for drinking water suggested by the United States Environmental Protection Agency (USEPA) (2 μg/L; total mercury), and the World Health Organisation (WHO) (6 μg/L; inorganic mercury). Actual water samples, including tap water, mineral water, and river water, which had been spiked with trace levels of Hg(2+), were well-analyzed by SPE, followed by microfluidic Hg(2+) immunoassay, and the results agreed with those obtained from reduction vaporizing-atomic adsorption spectroscopy.

  12. A highly selective sulfur-free iridium(III)-complex-based phosphorescent chemidosimeter for detection of mercury(II) ions.

    PubMed

    Zeng, Hui; Yu, Fang; Dai, Jun; Sun, Huiqin; Lu, Zhiyun; Li, Ming; Jiang, Qing; Huang, Yan

    2012-04-28

    A neutral phosphorescent coordination compound bearing a benzimidazole ligand, Ir(pbi)(2)(acac) (Hpbi = 1,2-diphenyl-1H-benzo[d]imidazole; Hacac = acetylacetone), is demonstrated to be the first example of a sulfur-free iridium complex for the detection of Hg(2+) cations with high selectivity and sensitivity. Ir(pbi)(2)(acac) shows a multisignaling response towards mercury(II) ions through UV-vis absorption, phosphorescence and electrochemistry measurements. Upon addition of Hg(2+) ions, solutions of this complex change from yellow to colorless, which could be observed easily by the naked eye, while its phosphorescence turns from bright green (λ(PLmax) = 520 nm) into faint skyblue (λ(PLmax) = 476 nm), and the detection limit is calculated to be 2.4 × 10(-7) mol L(-1). (1)H NMR spectroscopic titration as well as ESI-MS results indicate that the decomposition of Ir(pbi)(2)(acac) in the presence of Hg(2+) through rupture of Ir-O bonds is responsible for the significant variations in both optical and electrochemical signals.

  13. l-Tryptophan-capped carbon quantum dots for the sensitive and selective fluorescence detection of mercury ion in aqueous solution

    NASA Astrophysics Data System (ADS)

    Wan, Xuejuan; Li, Shifeng; Zhuang, Lulu; Tang, Jiaoning

    2016-07-01

    l-Tryptophan-capped carbon quantum dots ( l-CQDs) were facilely synthesized through "green" methodology, and the obtained material was utilized as a sensitive and selective fluorescence sensor for mercury ion (Hg2+) in pure aqueous solutions. Carboxyl-functionalized CQDs were first green synthesized by a one-step hydrothermal route, and l-tryptophan was then attached to CQDs via direct surface condensation reaction in aqueous solution at room temperature. The as-synthesized l-CQDs had an average size of ca. 5 nm with a good dispersity in water, and exhibited a favorable selectivity for Hg2+ ions over a range of other common metal cations in aqueous solution (10 mM PBS buffer, pH 6.0). Upon the addition of Hg2+, a complete fluorescence quenching (ON-OFF switching) of l-CQDs was evident from the fluorescence titration experiment, and the fluorescence detection limit of Hg2+ was calculated to be 11 nM, which indicated that the obtained environmentally friendly l-CQDs had sensitive detection capacity for Hg2+ in aqueous solution.

  14. 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.

  15. 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

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. Compensated Multi-Pole Mercury Trapped Ion Frequency Standard and Stability Evaluation of Systematic Effects

    NASA Astrophysics Data System (ADS)

    Burt, E. A.; Taghavi-Larigani, S.; Prestage, J. D.; Tjoelker, R. L.

    2009-04-01

    We have developed a compensated multi-pole Linear Ion Trap Standard (LITS) that eliminates nearly all frequency sensitivity to residual ion number variations. When operated with 199Hg+, this trapped ion clock has recently demonstrated extremely good stability over a 9-month period. The short-term stability has been measured at 5 × 10-14/τ1/2 and an upper limit on long-term fractional frequency deviations of < 2.7 × 10-17/day was measured in comparison to the laser-cooled primary standards and to the post-processed ultra-stable version of TAI known as TTBIPM using GPS carrier phase time transfer. We have also made a first measurement of the Hg+/Hg collision shift and place a limit of +3.8(7.2) × 10-8/Pa on the shift constant.

  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. 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.

  3. 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.

  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.

  5. Enhanced adsorption of mercury ions on thiol derivatized single wall carbon nanotubes.

    PubMed

    Bandaru, Narasimha Murthy; Reta, Nekane; Dalal, Habibullah; Ellis, Amanda V; Shapter, Joseph; Voelcker, Nicolas H

    2013-10-15

    Thiol-derivatized single walled carbon nanotube (SWCNT-SH) powders were synthesized by reacting acid-cut SWCNTs with cysteamine hydrochloride using carbodiimide coupling. Infrared (IR) spectroscopy, Raman spectroscopy and thermogravimetric analysis confirmed the successful functionalization of the SWCNTs. SWCNT-SH powders exhibited a threefold higher adsorption capacity for Hg(II) ions compared to pristine SWCNTs, and a fourfold higher adsorption capacity compared to activated carbon. The influence of adsorption time, pH, initial metal concentration and adsorbent dose on Hg(II) ion removal was investigated. The maximum adsorption capacity of the SWCNT-SH powders was estimated by using equilibrium isotherms, such as Freundlich and Langmuir, and the maximum adsorption capacity of the SWCNT-SH powder was found to be 131 mg/g. A first-order rate model was employed to describe the kinetic adsorption process of Hg(II) ions onto the SWCNT-SH powders. Desorption studies revealed that Hg(II) ions could be easily removed from the SWCNT-SH powders by altering the pH. Further, the adsorption efficiency of recovered SWCNT-SH powders was retained up to 91%, even after 5 adsorption/desorption cycles.

  6. A novel fluorescent array for mercury (II) ion in aqueous solution with functionalized cadmium selenide nanoclusters.

    PubMed

    Chen, Jinlong; Gao, YingChun; Xu, ZhiBing; Wu, GenHua; Chen, YouCun; Zhu, ChangQing

    2006-09-01

    Mono-disperse CdSe nanoclusters have been prepared facilely and functionalized with l-cysteine through two steps by using safe and low cost substances. They are water-soluble and biocompatible. Especially these functionalized quantum dots can be stably soluble in water more than for 30 days, and the intensity of fluorescence and absorbance was decreased less than 15% of fresh prepared CdSe colloids. These functionalized CdSe QDs exhibited strong specific affinity for mercury (II) through QDs interface functional groups. Based on the quenching of fluorescence signals of functionalized CdSe QDs at 530 nm and no obvious wavelength shift or no new emission band in present of Hg (II) at pH 7.75 of phosphate buffer solution, a simple, rapid and specific array for Hg (II) was proposed. In comparison with conventional organic fluorophores, these nanoparticles are brighter, more stable against photobleaching, and do not suffer from blinking. Under optimum conditions, the response of linearly proportional to the concentration of Hg (II) between 0 and 2.0 x10(-6) mol L(-1), and the limit of detection is 6.0 x 10(-9) mol L(-1). The relative standard deviation of six replicate measurements is 1.8% for 1.0 x 10(-7) mol L(-1) Hg (II). The mechanism of reaction is also discussed. The proposed method was successfully applied for Hg (II) detection in four real samples with a satisfactory result that was obtained by cold vapor atomic fluorescence spectrometry (CV-AFS).

  7. 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+).

  8. Observation of mass-asymmetric fission of mercury nuclei in heavy ion fusion

    NASA Astrophysics Data System (ADS)

    Prasad, E.; Hinde, D. J.; Ramachandran, K.; Williams, E.; Dasgupta, M.; Carter, I. P.; Cook, K. J.; Jeung, D. Y.; Luong, D. H.; McNeil, S.; Palshetkar, C. S.; Rafferty, D. C.; Simenel, C.; Wakhle, A.; Khuyagbaatar, J.; Düllmann, Ch. E.; Lommel, B.; Kindler, B.

    2015-06-01

    Background: Mass-asymmetric fission has been observed in low energy fission of 180Hg . Calculations predicted the persistence of asymmetric fission in this region even at excitation energies of 30-40 MeV. Purpose: To investigate fission mass distributions by populating different isotopes of Hg using heavy ion fusion reactions. Methods: Fission fragment mass-angle distributions have been measured for two reactions, 40Ca+142Nd and 13C+182W , populating 182Hg and 195Hg , respectively, using the Heavy Ion Accelerator Facility and CUBE spectrometer at the Australian National University. Measurements were made at beam energies around the capture barrier for the two reactions and mass ratio distributions were obtained using the kinematic reconstruction method. Results: Asymmetric fission has been observed following the population of 182Hg at an excitation energy of 22.8 MeV above the saddle point. A symmetric peaked mass ratio distribution was observed for 195Hg nuclei at a similar excitation energy above the saddle point. Conclusions: Mass-asymmetric fission has been observed in neutron deficient Hg nuclei populated via heavy ion fusion for the first time. The results are consistent with observations from beta-delayed fission measurements and provide a proof-of-principle for expanding experimental studies of the influence of shell effects on the fission processes.

  9. Highly effective removal of mercury and lead ions from wastewater by mercaptoamine-functionalised silica-coated magnetic nano-adsorbents: Behaviours and mechanisms

    NASA Astrophysics Data System (ADS)

    Bao, Shuangyou; Li, Kai; Ning, Ping; Peng, Jinhui; Jin, Xu; Tang, Lihong

    2017-01-01

    A novel hybrid material was fabricated using mercaptoamine-functionalised silica-coated magnetic nanoparticles (MAF-SCMNPs) and was effective in the extraction and recovery of mercury and lead ions from wastewater. The properties of this new magnetic material were explored using various characterisation and analysis methods. Adsorbent amounts, pH levels and initial concentrations were optimised to improve removal efficiency. Additionally, kinetics, thermodynamics and adsorption isotherms were investigated to determine the mechanism by which the fabricated MAF-SCMNPs adsorb heavy metal ions. The results revealed that MAF-SCMNPs were acid-resistant. Sorption likely occurred by chelation through the amine group and ion exchange between heavy metal ions and thiol functional groups on the nanoadsorbent surface. The equilibrium was attained within 120 min, and the adsorption kinetics showed pseudo-second-order (R2 > 0.99). The mercury and lead adsorption isotherms were in agreement with the Freundlich model, displaying maximum adsorption capacities of 355 and 292 mg/g, respectively. The maximum adsorptions took place at pH 5-6 and 6-7 for Hg(II) and Pb(II), respectively. The maximum adsorptions were observed at 10 mg and 12 mg adsorbent quantities for Hg(II) and Pb(II), respectively. The adsorption process was endothermic and spontaneous within the temperature range of 298-318 K. This work demonstrates a unique magnetic nano-adsorbent for the removal of Hg(II) and Pb(II) from wastewater.

  10. 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.

  11. A new peptidyl fluorescent chemosensors for the selective detection of mercury ions based on tetrapeptide.

    PubMed

    Thirupathi, Ponnaboina; Lee, Keun-Hyeung

    2013-12-15

    A novel peptidyl chemosensor (PySO2-His-Gly-Gly-Lys(PySO2)-NH2, 1) was synthesized by incorporation of two pyrene (Py) fluorophores into the tetrapeptide using sulfonamide group. Compound 1 exhibited selective fluorescence response towards Hg(II) over the other metal ions in aqueous buffered solutions. Furthermore, 1 with the potent binding affinity (Kd=120 nM) for Hg(II) detected Hg(II) without interference of other metal ions such as Ag(I), Cu(II), Cd(II), and Pb(II). The binding mode of 1 with Hg(II) was investigated by UV absorbance spectroscopy, (1)H NMR titration experiment, and pH titration experiment. The addition of Hg(II) induced a significant decrease in both excimer and monomer emissions of the pyrene fluorescence. Hg(II) interacted with the sulfonamide groups and the imidazole group of His in the peptidyl chemosensor and then two pyrene fluorophores were close to each other in the peptide. The decrease of both excimer and monomer emission was mainly due to the excimer/monomer emission change by dimerization of two pyrene fluorophores and a quenching effect of Hg(II).

  12. Spectroscopic study of the recognition of 2-quinolinone derivative on mercury ion.

    PubMed

    Zhang, Yongbin; Yang, Yutao; Hao, Junsheng; Yin, Caixia; Huo, Fangjun; Chao, Jianbin; Liu, Diansheng

    2014-11-11

    A new compound based on 2-quinolinone derivative with very little side effects on organisms, 3-(1H-benzo[d]imidazol-2-yl)-6,7-difluoroquinolin-2(1H)-one, has been designed, synthesized and characterized. And its recognition ability was firstly studied by spectroscopy. The result indicated that the compound shows high selectivity for Hg2+ over other metal ions with detectable fluorescent signals in aqueous-methanol media. The proposed mechanism is that the fluorescence of the probe was quenched due to the effect from spin-orbit coupling of Hg2+ after the probe coordinated with Hg2+, and was proved by ESI-MS and 1H NMR analysis.

  13. 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.

  14. 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.

  15. Ion-exchange voltammetry with nafion/poly(sodium 4-styrenesulfonate) mixed coatings on mercury film electrodes: characterization studies and application to the determination of trace metals.

    PubMed

    Rocha, Luciana S; Pinheiro, José Paulo; Carapuça, Helena M

    2006-09-12

    This work aimed to produce improved polymer coatings for the modification of thin mercury film electrodes (TMFEs). The goal is to obtain sensitive, reproducible, mechanically stable and antifouling devices suitable for the determination of trace metal cations in complex media. Therefore, novel mixed coatings of two sulfonated cation-exchange polymers of dissimilar characteristics-Nafion (NA) and poly(sodium 4-styrenesulfonate) (PSS)-were produced by solvent evaporation onto glassy carbon electrodes. The effect of the mass ratio (NA:PSS) on the film morphology was studied by scanning electron microscopy, revealing the formation of biphasic polymer systems, where PSS bead-shaped clusters appeared randomly dispersed into a uniform and compact NA environment. The permselectivity/ion-exchange features of the mixed films onto glassy carbon were evaluated using cathecol, urate, and dopamine. To allow trace metal analysis, thin mercury films were plated through the NA/PSS coatings, being the reproducibility and ion-exchange features of the mixed coatings-TMFE evaluated using lead ions. The best NA/PSS coating was found for the mass ratio of 5.3. Analytical performance of the NA/PSS-TMFE yielded a detection limit of 5.5 nM (3sigma), and the application of this modified electrode to an untreated polluted estuarine water sample produced significant improvements in the quality of the signal compared with that for a bare TMFE.

  16. 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.

  17. 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(-).

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. An EXAFS spectroscopic, large-angle X-ray scattering, and crystallographic study of hexahydrated, dimethyl sulfoxide and pyridine 1-oxide hexasolvated mercury(II) ions.

    PubMed

    Persson, Ingmar; Eriksson, Lars; Lindqvist-Reis, Patric; Persson, Per; Sandström, Magnus

    2008-01-01

    The structure of the solvated mercury(II) ion in water and dimethyl sulfoxide has been studied by means of large-angle X-ray scattering (LAXS) and extended X-ray absorption fine structure (EXAFS) techniques. The distribution of the Hg-O distances is unusually wide and asymmetric in both solvents. In aqueous solution, hexahydrated [Hg(OH(2))(6)](2+) ions in a distorted octahedral configuration, with the centroid of the Hg-O distance at 2.38(1) A, are surrounded by a diffuse second hydration sphere with HgO(II) distances of 4.20(2) A. In dimethyl sulfoxide, the six Hg-O and HgS distances of the hexasolvated [Hg{OS(CH(3))(2)}(6)](2+) complex are centered around 2.38(1) and 3.45(2) A, respectively. The crystal structure of hexakis(pyridine 1-oxide)mercury(II) perchlorate has been redetermined. The space group R(-)3 implies six equal Hg-O distances of 2.3416(7) A for the [Hg(ONC(5)H(5))(6)](2+) complex at 100 K. However, EXAFS studies of this compound, and of the solids hexaaquamercury(II) perchlorate and hexakis(dimethyl sulfoxide)mercury(II) trifluoromethanesulfonate, also with six equidistant Hg-O bonds according to crystallographic results, reveal in all cases strongly asymmetric Hg-O distance distributions. Vibronic coupling of valence states in a so-called pseudo-Jahn-Teller effect probably induces the distorted configurations.

  3. An EXAFS Spectroscopic, Large-Angle X-Ray Scattering, And Crystallographic Study of Hexahydrated, Dimethyl Sulfoxide And Pyridine 1-Oxide Hexasolvated Mercury(II) Ions

    SciTech Connect

    Persson, I.; Eriksson, L.; Lindqvist-Reis, P.; Persson, P.; Sandstrom, M.

    2009-05-21

    The structure of the solvated mercury(II) ion in water and dimethyl sulfoxide has been studied by means of large-angle X-ray scattering (LAXS) and extended X-ray absorption fine structure (EXAFS) techniques. The distribution of the Hg-O distances is unusually wide and asymmetric in both solvents. In aqueous solution, hexahydrated [Hg(OH{sub 2}){sub 6}]{sup 2+} ions in a distorted octahedral configuration, with the centroid of the HgO distance at 2.38(1) {angstrom}, are surrounded by a diffuse second hydration sphere with HgOII distances of 4.20(2) {angstrom}. In dimethyl sulfoxide, the six HgO and HgS distances of the hexasolvated [Hg{l_brace}OS(CH{sub 3}){sub 2}{r_brace}{sub 6}]{sup 2+} complex are centered around 2.38(1) and 3.45(2) {angstrom}, respectively. The crystal structure of hexakis(pyridine 1-oxide)mercury(II) perchlorate has been redetermined. The space group R implies six equal HgO distances of 2.3416(7) {angstrom} for the [Hg(ONC{sub 5}H{sub 5}){sub 6}]{sup 2+} complex at 100 K. However, EXAFS studies of this compound, and of the solids hexaaquamercury(II) perchlorate and hexakis(dimethyl sulfoxide)mercury(II) trifluoromethanesulfonate, also with six equidistant HgO bonds according to crystallographic results, reveal in all cases strongly asymmetric HgO distance distributions. Vibronic coupling of valence states in a so-called pseudo-Jahn-Teller effect probably induces the distorted configurations.

  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. Fluorescent switch for fast and selective detection of mercury (II) ions in vitro and in living cells and a simple device for its removal.

    PubMed

    Yuan, Yue; Jiang, Shenlong; Miao, Qingqing; Zhang, Jia; Wang, Mengjing; An, Linna; Cao, Qinjingwen; Guan, Yafeng; Zhang, Qun; Liang, Gaolin

    2014-07-01

    A water-soluble, biocompatible, and fluorescent chemosensor (1) for label-free, simple, and fast detection of mercury ions (Hg(2+)) in aqueous solutions and in HepG2 cells with high selectivity is reported herein. Chelation of 1 with Hg(2+) results in the disappearance of its fluorescence emission at 350 nm and the appearance of a new emission at 405 nm. Selectivity and interference studies indicated that 1 could be selectively chelated by Hg(2+) without interference from other metal ions. Insight into the mechanisms responsible for its fluorescence effect was gained from ultrafast transient absorption spectroscopy. With these properties, 1 was successfully applied for imaging Hg(2+) in living cells and for removing Hg(2+) from river water. Moreover, we also constructed a simple device for fast and effective removal of Hg(2+) from contaminated liquid samples.

  6. 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.

  7. 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.

  8. 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 ...

  9. [Mercury poisoning].

    PubMed

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

    2011-07-01

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

  10. 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

  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

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

    2014-12-30

    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).

  12. 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 (2.5 pM), 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.

  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. 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.

  16. 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

  17. 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

  18. Non-chromatographic mercury speciation and determination in wine by new core-shell ion-imprinted sorbents.

    PubMed

    Dakova, Ivanka; Yordanova, Tanya; Karadjova, Irina

    2012-09-15

    In this study new Hg(II) core-shell imprinted sorbents (Hg(II)-IIPs) were prepared and tested for speciation and determination of Hg in wine. The silica gel, chemically modified with 3-(trimethoxysilyl)propyl methacrylate (TSPM) was used as supporting material. The Hg(II)-imprinted polymer layer was grafted by copolymerization of methacrylic acid and trimethylolpropane trimethacrylate in the presence of Hg(II) complexes with two different chelating agents: 1-pyrrolidinedithiocarboxylic acid (P(PDC-Hg)/SiG) and 1-(2-thiazolylazo)-2-naphthol (P(TAN-Hg)/SiG). High selectivity and fast kinetics of processes of sorption and desorption for Hg(II) were found by using P(PDC-Hg)/SiG. Recovery experiments performed for selective determination of inorganic mercury in wines showed that the interfering organic matrix did not influence the extraction efficiency. Column solid phase extraction scheme was developed for the determination and speciation of Hg in wines. The limit of detection (LOD) achieved for inorganic mercury determination in wine samples is 0.02 μg L(-1) (3σ), measured by CV AAS. The relative standard deviation varied in the range 6-11% at 0.05-2 μg L(-1) Hg levels. The sorbents showed high mechanical and chemical stability and extraction efficiency has not changed after more than 50 sorption/desorption cycles.

  19. A new isoindoline-based highly selective "turn-on" fluorescent chemodosimeter for detection of mercury ion.

    PubMed

    Zali-Boeini, Hassan; Zareh Jonaghani, Mohammad; Fadaei, Negar; Rudbari, Hadi Amiri

    2017-05-05

    A new isoindoline-based highly efficient turn-on fluorescent chemodosimeter S with a thioamide functionality as a binding site for selective detection of Hg(2+) ion has been developed. The chemodosimeter S showed an extreme selectivity for detection of Hg(2+) ion among various two and three-valent metal ions in acetonitrile/water (70/30, v/v). It was found that, in the presence of Hg(2+) ion the non-fluorescent chemodosimeter S was efficiently and rapidly desulfurized to the corresponding highly fluorescent amide 1. A good linear relationship was shown between the fluorescence intensity and the concentration of Hg(2+) within the range of 0-1μM, with a detection limit of 2.03×10(-8)M.

  20. A bisferrocene-benzobisimidazole triad as a multichannel ditopic receptor for selective sensing of hydrogen sulfate and mercury ions.

    PubMed

    Alfonso, María; Tárraga, Alberto; Molina, Pedro

    2011-12-16

    The bisferrocene-benzobisimidazole triad behaves as a selective redox and fluorescent chemosensor for HSO(4)(-) and Hg(2+) ions, exhibiting an easily detectable signal change in both the redox potential of the ferrocene/ferrocinium redox couple and in the emission band which is red-shifted (Δλ = 10-13 nm) and enhanced in intensity (Chelation Enhanced Fluorescence, CHEF = 486-225) upon complexation with these ions, in EtOH solutions.

  1. 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.

  2. 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.

  3. 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.

  4. Mercury's sodium exosphere

    NASA Astrophysics Data System (ADS)

    Leblanc, F.; Johnson, R. E.

    2003-08-01

    Mercury's neutral sodium exosphere is simulated using a comprehensive 3D Monte Carlo model following sodium atoms ejected from Mercury's surface by thermal desorption, photon stimulated desorption, micro-meteoroid vaporization and solar wind sputtering. The evolution of the sodium surface density with respect to Mercury's rotation and its motion around the Sun is taken into account by considering enrichment processes due to surface trapping of neutrals and ions and depletion of the sodium available for ejection from the surfaces of grains. The change in the sodium exosphere is calculated during one Mercury year taking into account the variations in the solar radiation pressure, the photo-ionization frequency, the solar wind density, the photon and meteoroid flux intensities, and the surface temperature. Line-of-sight column densities at different phase angles, the supply rate of new sodium, average neutral and ion losses over a Mercury year, surface density distribution and the importance of the different processes of ejection are discussed in this paper. The sodium surface density distribution is found to become significantly nonuniform from day to night sides, from low to high latitudes and from morning to afternoon because of rapid depletion of sodium atoms in the surfaces of grains mainly driven by thermal depletion. The shape of the exosphere, as it would be seen from the Earth, changes drastically with respect to Mercury's heliocentric position. High latitude column density maxima are related to maxima in the sodium surface concentration at high latitudes in Mercury's surface and are not necessarily due to solar wind sputtering. The ratio between the sodium column density on the morning side of Mercury's exosphere and the sodium column density on the afternoon side is consistent with the conclusions of Sprague et al. (1997, Icarus 129, 506-527). The model, which has no fitting parameters, shows surprisingly good agreement with recent observations of Potter et

  5. 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.

  6. Trifunctional molecular beacon-mediated quadratic amplification for highly sensitive and rapid detection of mercury(II) ion with tunable dynamic range.

    PubMed

    Zhao, Yue; Liu, Huaqing; Chen, Feng; Bai, Min; Zhao, Junwu; Zhao, Yongxi

    2016-12-15

    Analyses of target with low abundance or concentration varying over many orders of magnitude are severe challenges faced by numerous assay methods due to their modest sensitivity and limited dynamic range. Here, we introduce a homogeneous and rapid quadratic polynomial amplification strategy through rational design of a trifunctional molecular beacon, which serves as not only a reporter molecule but also a bridge to couple two stage amplification modules without adding any reaction components or process other than basic linear amplification. As a test bed for our studies, we took mercury(II) ion as an example and obtained a high sensitivity with detection limit down to 200 pM within 30min. In order to create a tunable dynamic range, homotropic allostery is employed to modulate the target specific binding. When the number of metal binding site varies from 1 to 3, signal response is programmed accordingly with useful dynamic range spanning 50, 25 and 10 folds, respectively. Furthermore, the applicability of the proposed method in river water and biological samples are successfully verified with good recovery and reproducibility, indicating considerable potential for its practicality in complex real samples.

  7. 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

  8. 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.

  9. Alumina physically loaded by thiosemicarbazide for selective preconcentration of mercury(II) ion from natural water samples.

    PubMed

    Ahmed, Salwa A

    2008-08-15

    The multifunctional ligand, thiosemicarbazide, was physically loaded on neutral alumina. The produced alumina-modified solid phase (SP) extractor named, alumina-modified thiosemicarbazide (AM-TSC), experienced high thermal and medium stability. This new phase was identified based on surface coverage determination by thermal desorption method to be 0.437+/-0.1 mmol g(-1). The selectivity of AM-TSC phase towards the uptake of different nine metal ions was checked using simple, fast and direct batch equilibration technique. AM-TSC was found to have the highest capacity in selective extraction of Hg(II) from aqueous solutions all over the range of pH used (1.0-7.0), compared to the other eight tested metal ions. So, Hg(II) uptake was 1.82 mmol g(-1) (distribution coefficient log K(d)=5.658) at pH 1.0 or 2.0 and 1.78, 1.73, 1.48, 1.28 and 1.28 mmol g(-1) (log K(d)=4.607, 4.265, 3.634, 3.372 and 3.372), at pH 3.0, 4.0, 5.0, 6.0 and 7.0, respectively. On the other hand, the metal ions Ca(II), Fe(III), Co(II), Ni(II), Cu(II), Zn(II), Cd(II) and Pb(II) showed low uptake values in range 0.009-0.720 mmol g(-1) (log K(d)<3.0) at their optimum pH values. A mechanism was suggested to explain the unique uptake of Hg(II) ions based on their binding as neutral and chloroanionic species predominate at pH values < or =3.0 of a medium rich in chloride ions. Application of the new phase for the preconcentration of ultratrace amounts of Hg(II) ions spiked natural water samples: doubly distilled water (DDW), drinking tap water (DTW) and Nile river water (NRW) using cold vapor atomic absorption spectroscopy (CV-AAS) was studied. The high recovery values obtained using AM-TSC (98.5+/-0.5, 98.0+/-0.5 and 103.0+/-1.0) for DDW, DTW and NRW samples, respectively based on excellent enrichment factor 1000, along with a good precision (R.S.D.% 0.51-0.97%, n=3) demonstrate the accuracy and validity of the new modified alumina sorbent for preconcentrating ultratrace amounts of Hg(II) with no matrix

  10. 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.

  11. Adsorption of chromium(III), mercury(II) and lead(II) ions onto 4-aminoantipyrine immobilized bentonite.

    PubMed

    Wang, Qihui; Chang, Xijun; Li, Dandan; Hu, Zheng; Li, Ruijun; He, Qun

    2011-02-28

    In this work, the immobilization of 4-aminoantipyrine onto bentonite was carried out and it was then used to investigate the adsorption behavior of Cr(III), Hg(II) and Pb(II) ions from aqueous solutions. The separation and preconcentration conditions of analytes were investigated, including effects of pH, the shaking time, the sample flow rate and volume, the elution condition and the interfering ions. Under optimum pH value (pH 4.0), the maximum static adsorption capacity of the sorbent was found to be 38.8, 52.9 and 55.5 mg g(-1) for Cr(III), Hg(II) and Pb(II), respectively. 2.0 mL of 2% thiourea in 1.0 M HCl solution effectively eluted the adsorbed metal ions. The detection limit (3σ) of this method defined by IUPAC was found to be 0.12, 0.09 and 0.23 ng mL(-1) for Cr(III), Hg(II) and Pb(II), respectively. The relative standard deviation (RSD) was lower 3.0% (n=8). The developed method has been validated by analyzing certified reference materials and successfully applied to the determination of trace Cr(III), Hg(II) and Pb(II) in water samples with satisfactory results.

  12. 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%.

  13. 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.

  14. 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.

  15. Carbon nanoparticle-based ratiometric fluorescent sensor for detecting mercury ions in aqueous media and living cells.

    PubMed

    Lan, Minhuan; Zhang, Jinfeng; Chui, Ying-San; Wang, Pengfei; Chen, Xianfeng; Lee, Chun-Sing; Kwong, Hoi-Lun; Zhang, Wenjun

    2014-12-10

    A novel nanohybrid ratiometric fluorescence sensor is developed for selective detection of mercuric ions (Hg(2+)), and the application has been successfully demonstrated in HEPES buffer solution, lake water, and living cells. The sensor comprises water-soluble fluorescent carbon nanoparticles (CNPs) and Rhodamine B (RhB) and exhibits their corresponding dual emissions peaked at 437 and 575 nm, respectively, under a single excitation wavelength (350 nm). The photoluminescence of the CNPs in the nanohybrid system can be completely quenched by Hg(2+) through effective electron or energy transfer process due to synergetic strong electrostatic interaction and metal-ligand coordination between the surface functional group of CNPs and Hg(2+), while that of the RhB remains constant. This results in an obviously distinguishable fluorescence color variation (from violet to orange) of the nanohybrid solution. This novel sensor can effectively identify Hg(2+) from other metal ions with relatively low background interference even in a complex system such as lake water. The detection limit of this method is as low as 42 nM. Furthermore, the sensing technique is applicable to detect Hg(2+) in living cells.

  16. 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.

  17. 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.

  18. Uptake of Mercury by the Brain

    PubMed Central

    Magos, L.

    1968-01-01

    A technique has been developed for injecting metallic mercury intravenously in aqueous solution. Thirty seconds after intravenous injection of rats with 0·1 μg. metallic mercury labelled with 203Hg nearly 20% of the dose had been exhaled and the concentration in the brain was nearly as high as in the blood. After injection of mercuric ion little of the dose was exhaled, and brain uptake was much less. Oxidation of mercury in the blood was, therefore, not instantaneous, and the rapid transport of the unconverted metallic mercury to the brain and its subsequent rapid diffusion from the blood was responsible for the high level of mercury in the brain after exposure to mercury vapour. The technique might be useful for the study of the passage of highly diffusible vapours through the respiratory membranes. PMID:5723353

  19. One-pot electrochemical synthesis of functionalized fluorescent carbon dots and their selective sensing for mercury ion.

    PubMed

    Hou, Yuxin; Lu, Qiujun; Deng, Jianhui; Li, Haitao; Zhang, Youyu

    2015-03-25

    We propose a simple, economical, and one-pot method to synthesize water-soluble functionalized fluorescent carbon dots (C-Dots) through electrochemical carbonization of sodium citrate and urea. The as-prepared C-Dots have good photostability and exhibit a high quantum yield of 11.9%. The sizes of the C-Dots are mainly distributed in the range of 1.0-3.5 nm with an average size of 2.4 nm. It has been further used as a novel label-free sensing probe for selective detection of Hg(2+) ions with detection limit as low as 3.3 nM. The detection linear range is 0.01-10 μM. The as-prepared C-Dots are also successfully applied for the determination of Hg(2+) in real water samples.

  20. Fluorescent and colorimetric sensors for environmental mercury detection.

    PubMed

    Chen, Guiqiu; Guo, Zhi; Zeng, Guangming; Tang, Lin

    2015-08-21

    Exposure to mercury ions can damage the human brain, the nervous system, the endocrine system, and other biological systems. Much effort has therefore been made to develop real-time monitoring of mercury variations, and many mercury-ion sensors have been reported recently. In this review, mercury-ion sensors reported since 2008 are described and discussed. The sensors are classified as molecular, nanomaterial based, and others. Molecular sensors are based on chemical and hydrogen bond formation, and the other types are based on changes in the materials used.

  1. 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.

  2. Determination of trace mercury by solid substrate-room temperature phosphorimetry quenching method based on catalytic effect of Hg2+ on formation of the ion association complex [Sn(XO)6]4+.[(Fin)4].

    PubMed

    Liu, Jia-Ming; Wu, Ruo-Hong; Li, De-Chang; Zhou, Ping; Zheng, Min-Min; Zeng, Xiao-Yi; Liu, Dong-Xia; Huang, Xiao-Mei; Zhu, Guo-Hui

    2006-09-01

    A new method for the determination of trace mercury by solid substrate-room temperature phosphorimetry (SS-RTP) quenching method has been established. In glycine-HCl buffer solution, xylenol orange (XO) can react with Sn4+ to form the complex [Sn(XO)6]4+. [Sn(XO)6]4+ can interact with Fin- (fluorescein anion) to form the ion associate [Sn(XO)6]4+.[(Fin)4]-, which can emit strong and stable room temperature phosphorescence (RTP) on polyamide membrane (PAM). Hg2+ can catalyze H2O2 oxidizing the ion association complex [Sn(XO)6]4+.[(Fin)4]-, which causes the RTP to quench. The DeltaIp value is directly proportional to the concentration of Hg2+ in the range of 0.016-1.6 fg spot(-1) (corresponding concentration: 0.040-4.0 pg ml(-1), 0.40 microl spot(-1)), and the regression equation of working cure is DeltaIp=10.03+83.15 m Hg2+ (fg spot(-1)), (r=0.9987, n=6) and the detection limit (LD) is 3.6 ag spot(-1)(corresponding concentration: 9.0 x 10(-15) g ml(-1), the sample volume: 0.4 microl). This simple, rapid, accurate method is of high selectivity and good repeatability, and it has been successfully applied to the determination of trace mercury in real samples. The reaction mechanism for catalyzing H2O2 oxidizing the ion association complex ([Sn(XO)6]4+.[(Fin)4]-) SS-RTP quenching method to determine trace mercury is also discussed.

  3. Abundance of mercury in regolith of the Sea of Fertility, Sea of Tranquillity, and Ocean of Storms

    NASA Technical Reports Server (NTRS)

    Belyayev, Y. I.; Koveshnikova, T. A.

    1974-01-01

    The direct determination of mercury by the atomic fluorescent method is described, involving the pulsed thermal atomization of powdered samples when the mercury is vaporized in argon at normal pressure. An increase in the mercury abundance in the regolith of the surficial layer with decrease in grain size and with variation in depth was noted, from 6 minus 1 million the surficial layer to 9 minus 1 million percent at a depth of about 30 cm. It is shown that in conditions simulating lunar day, at temperatures of 130-150 C up to 15 to 20 percent of the mercury is vaporized from a 2 mg regolith weighed sample, and thus the hypothesis is advanced that mercury is adsorbed by the surface layers of the lunar surface material during lunar night and desorbed during lunar day. The assumption is advanced that there exists a meridional mercury wind between subsolar region of the moon (heater) and the polar regions (cooler).

  4. 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.

  5. In Situ, Time-Resolved Accelerator Grid Erosion Measurements in the NSTAR 8000 Hour Ion Engine Wear Test

    NASA Technical Reports Server (NTRS)

    Sovey, J.

    1997-01-01

    Time-resolved, in situ measurements of the charge exchange ion erosion pattern on the downstream face of the accelerator grid have been made during an ongoin wear test of the NSTAR 30 cm ion thruster.

  6. Highly sensitive and specific determination of mercury(II) ion in water, food and cosmetic samples with an ELISA based on a novel monoclonal antibody.

    PubMed

    Wang, Yuzhen; Yang, Hong; Pschenitza, Michael; Niessner, Reinhard; Li, Yuan; Knopp, Dietmar; Deng, Anping

    2012-07-01

    Mercury is one of the most toxic heavy metals present in the environment. In this study, a highly sensitive and specific monoclonal antibody (mAb)-based indirect competitive enzyme-linked immunosorbent assay (ELISA) for the determination of Hg(2+) was developed. A new bifunctional ligand, 6-mercaptonicotinic acid (MNA), which contains a pyridine ring bearing a carboxylic group and a mercapto group, was selected for the preparation of immunogen. After immunization of mice and performing the hybridoma technique, the obtained mAb was characterized for its binding affinity and selectivity for Hg(2+). Based on this novel mAb, an ELISA was established. At optimal experimental conditions, the standard curve of the ELISA for Hg(2+) was constructed in concentration range of 0.1-100 ng mL(-1). The values of IC(50) and LOD of the assay were found to be 1.12 and 0.08 ng mL(-1). The cross-reactivity was lower than 2% with MNA, CH(3)Hg, and CH(3)Hg-MNA and was 11.5% and 4.4% for Hg(+) and Au(3+), respectively. No cross-reactivity was found with other metal ions such as Cu(2+), Sn(2+), Ni(2+), Mn(2+), Pb(2+), Zn(2+), Cd(2+), Fe(2+), Co(2+), Mg(2+), Ca(2+), and anions such as Cl(-), NO(3)(-), NO(2)(-), HCO(3)(-), F(-), and SO(4)(2-), indicating that the assay displays not only high sensitivity but also high selectivity. Different kinds of samples including water, milk, green vegetable, kelp, facial cleanser, and night cream were spiked with Hg(2+) and the extracts were analyzed by ELISA. Acceptable recovery rates of 80.0-113.0% and coefficients of variation of 1.9-18.6% were obtained. A linear relationship between ELISA and cold-vapor atomic fluorescence spectroscopy (CV-AFS) as indicated by a correlation coefficient of 0.97 for liquid samples (water samples) and 0.98 for other samples was obtained. The proposed mAb-based ELISA provides a feasible analytical method for highly sensitive and specific, fast, simple, and accurate determination of uncomplexed trace Hg(2+) in

  7. Mercury, elemental

    Integrated Risk Information System (IRIS)

    Mercury , elemental ; CASRN 7439 - 97 - 6 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarcinoge

  8. Mercury's Messenger

    ERIC Educational Resources Information Center

    Chapman, Clark R.

    2004-01-01

    Forty years after Mariner 2, planetary exploration has still only just begun, and many more missions are on drawing boards, nearing the launch pad, or even en route across interplanetary space to their targets. One of the most challenging missions that will be conducted this decade is sending the MESSENGER spacecraft to orbit the planet Mercury.…

  9. Fluorescent sensor for mercury

    DOEpatents

    Wang, Zidong [Urbana, IL; Lee, Jung Heon [Evanston, IL; Lu, Yi [Champaign, IL

    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.

  10. 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.

  11. 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...

  12. Indicators: Sediment Mercury

    EPA Pesticide Factsheets

    Sediment mercury is mercury that has become embedded into the bottom substrates of aquatic ecosystems. Mercury is a common pollutant of aquatic ecosystems and it can have a substantial impact on both human and wildlife health.

  13. 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.

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

    PubMed

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

    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 degrees 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 degrees 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.

  15. 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

  16. 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

    2005-01-04

    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.

  17. 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.

  18. Poly(ester sulphonic acid) coated mercury thin film electrodes: characterization and application in batch injection analysis stripping voltammetry of heavy metal ions.

    PubMed

    Brett, C M; Fungaro, D A

    2000-01-10

    Mercury-thin film electrodes coated with a thin film of poly(ester sulphonic acid) (PESA) have been investigated for application in the analysis of trace heavy metals by square wave anodic stripping voltammetry using the batch injection analysis (BIA) technique. Different polymer dispersion concentrations in water/acetone mixed solvent are investigated and are characterised by electrochemical impedance measurements on glassy carbon and on mercury film electrodes. The influence of electrolyte anion, acetate or nitrate, on polymer film properties is demonstrated, acetate buffer being shown to be preferable for stripping voltammetry applications. Although stripping currents are between 30 and 70% less at the coated than at bare mercury thin film electrodes, the influence of model surfactants on stripping response is shown to be very small. The effect of the composition of the modifier film dispersion on calibration plots is shown; however, detection limits of around 5 nM are found for all modified electrodes tested. This coated electrode is an alternative to Nafion-coated mercury thin film electrodes for the analysis of trace metals in complex matrices, particularly useful when there is a high concentration of non-ionic detergents.

  19. 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.

  20. Scientific objectives and instrumentation of Mercury Plasma Particle Experiment (MPPE) onboard MMO

    NASA Astrophysics Data System (ADS)

    Saito, Y.; Sauvaud, J. A.; Hirahara, M.; Barabash, S.; Delcourt, D.; Takashima, T.; Asamura, K.; BepiColombo MMO/MPPE Team

    2010-01-01

    Mercury is one of the least explored planets in our solar system. Until the recent flyby of Mercury by MESSENGER, no spacecraft had visited Mercury since Mariner 10 made three flybys: two in 1974 and one in 1975. In order to elucidate the detailed plasma structure and dynamics around Mercury, an orbiter BepiColombo MMO (Mercury Magnetospheric Orbiter) is planned to be launched in 2013 as a joint mission between ESA and ISAS/JAXA. Mercury Plasma Particle Experiment (MPPE) was proposed in order to investigate the plasma/particle environment around Mercury. MPPE is a comprehensive instrument package for plasma, high-energy particle and energetic neutral atom measurements. It consists of seven sensors: two Mercury electron analyzers (MEA1 and MEA2), Mercury ion analyzer (MIA), Mercury 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). Since comprehensive full three-dimensional simultaneous measurements of low to high-energy ions and electrons around Mercury as well as measurements of energetic neutral atoms will not be realized before BepiColombo/MMO's arrival at Mercury, it is expected that many unresolved problems concerning the Mercury magnetosphere will be elucidated by the MPPE observation.

  1. Mercury orbiter - an interdisciplinary mission

    NASA Astrophysics Data System (ADS)

    Grard, R.; Scoon, G.; Coradini, M.

    Mercury is the innermost and a less known terrestrial planet of the Solar System. It possesses a very high density (5.3 g/cu cm at 10 kbar), a small but unexpected magnetic moment (6 x 10-3 that of Earth), and a tenuous exosphere; ground-based radar observations indicate that water ice may exist at the poles. There are still fundamental questions about its accretion and catering history, and its thermal and chemical evolution. The size of Mercury's magnetosphere is just 5% of that of Earth; substorms last 5 min, on average, and their generation process is influenced by the absence of an ionosphere. The model payload of Mercury Orbiter includes a multi-spectral imager, a gamma-and X -ray detector, a magnetometer, charged-particle analysers, a wave receiver and an ion emitter for spacecraft potential control. The spacecraft, the design of which is inherited from ESA's Cluster spacecraft, has a dry mass of 626 kg and is stabilized at 10 rmp, but the telemetry antenna is despun. The bit rate varies between 1.4 and 9 kb/s over the range 1.6-0.64 AU. The spacecraft, launched from Kourou with an Ariane-5, reaches its destination after two gravity assists at Venus and two at Mercury. Its orbit is polar with periherm and apherm altitudes of 400 and 16 800 km, respectively. The spacecraft's operating lifetime around Mercury is 3 Hermean years.

  2. 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.

  3. Temporal variation of Mercury's sodium density

    NASA Astrophysics Data System (ADS)

    Fusegawa, Ayaka; Dairoku, Hayato; Kameda, Shingo; Kagitani, Masato; Okano, Shoichi

    2013-04-01

    Mercury has a thin atmosphere. In the past, Mercury has been observed by Mariner 10 and MESSENGER, and ground-based observations have also been carried out. H, He, O, Na, Mg, K, and Ca were detected in its atmosphere. Solar-photon-stimulated desorption, sputtering by impacting solar particles, and meteoroid vaporization are considered to be the source processes of Mercury's exosphere. However, the primary process among these three processes is unknown as yet. The resonance scattering constitutes exospheric emission. The NaD emission is well suited for study by ground-based observations because of its high intensity. Past observations have shown that the temporal variation and north-south asymmetry of intensity of sodium emission. We have observed Mercury's sodium exosphere at the Haleakala Observatory in Hawaii since April 2011. The observations were performed using a 40 cm Schmidt-Cassegrain telescope, a high-dispersion spectrograph, and a CCD camera. We determined the temporal variation of the sodium density using the observational data. It is possible that the temporal variation of the sodium density is caused by variation of solar wind magnetic field if solar wind ion sputtering is the primary source process of Mercury's exosphere. To verify this assumption, we checked the temporal variation of solar wind magnetic field observed by MESSENGER, and then we compared these variations with our observational result. CMEs toward Mercury probably cause the increase of the sodium density. Potter et al. (1999) suggested that the total amount of sodium on Mercury increased monotonically during several days of observation after CMEs occurred on the same side of the Sun as Mercury. We observed Mercury's sodium exosphere on November 23, 2011 when MESSENGER observed variation of solar wind magnetic field, which indicated CMEs arrived at Mercury. However, our results have not shown large variation of the sodium density like that of Potter et al. (1999). From these results, we

  4. Evidence for water ice near Mercury's north pole from MESSENGER Neutron Spectrometer measurements.

    PubMed

    Lawrence, David J; Feldman, William C; Goldsten, John O; Maurice, Sylvestre; Peplowski, Patrick N; Anderson, Brian J; Bazell, David; McNutt, Ralph L; Nittler, Larry R; Prettyman, Thomas H; Rodgers, Douglas J; Solomon, Sean C; Weider, Shoshana Z

    2013-01-18

    Measurements by the Neutron Spectrometer on the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft show decreases in the flux of epithermal and fast neutrons from Mercury's north polar region that are consistent with the presence of water ice in permanently shadowed regions. The neutron data indicate that Mercury's radar-bright polar deposits contain, on average, a hydrogen-rich layer more than tens of centimeters thick beneath a surficial layer 10 to 30 cm thick that is less rich in hydrogen. Combined neutron and radar data are best matched if the buried layer consists of nearly pure water ice. The upper layer contains less than 25 weight % water-equivalent hydrogen. The total mass of water at Mercury's poles is inferred to be 2 × 10(16) to 10(18) grams and is consistent with delivery by comets or volatile-rich asteroids.

  5. 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

    2008-07-04

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2014-11-01

    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.

  7. 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

    2014-11-20

    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.

  8. 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

  9. 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...

  10. 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.

  11. 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; 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.

  12. 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

  13. 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.

  14. 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 ...

  15. MESSENGER: Exploring Mercury's Magnetosphere

    NASA Astrophysics Data System (ADS)

    Slavin, James A.; Krimigis, Stamatios M.; Acuña, Mario H.; Anderson, Brian J.; Baker, Daniel N.; Koehn, Patrick L.; Korth, Haje; Livi, Stefano; Mauk, Barry H.; Solomon, Sean C.; Zurbuchen, Thomas H.

    2007-08-01

    The MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) mission to Mercury offers our first opportunity to explore this planet’s miniature magnetosphere since the brief flybys of Mariner 10. Mercury’s magnetosphere is unique in many respects. The magnetosphere of Mercury is among the smallest in the solar system; its magnetic field typically stands off the solar wind only ˜1000 to 2000 km above the surface. For this reason there are no closed drift paths for energetic particles and, hence, no radiation belts. Magnetic reconnection at the dayside magnetopause may erode the subsolar magnetosphere, allowing solar wind ions to impact directly the regolith. Inductive currents in Mercury’s interior may act to modify the solar wind interaction by resisting changes due to solar wind pressure variations. Indeed, observations of these induction effects may be an important source of information on the state of Mercury’s interior. In addition, Mercury’s magnetosphere is the only one with its defining magnetic flux tubes rooted beneath the solid surface as opposed to an atmosphere with a conductive ionospheric layer. This lack of an ionosphere is probably the underlying reason for the brevity of the very intense, but short-lived, ˜1-2 min, substorm-like energetic particle events observed by Mariner 10 during its first traversal of Mercury’s magnetic tail. Because of Mercury’s proximity to the sun, 0.3-0.5 AU, this magnetosphere experiences the most extreme driving forces in the solar system. All of these factors are expected to produce complicated interactions involving the exchange and recycling of neutrals and ions among the solar wind, magnetosphere, and regolith. The electrodynamics of Mercury’s magnetosphere are expected to be equally complex, with strong forcing by the solar wind, magnetic reconnection, and pick-up of planetary ions all playing roles in the generation of field-aligned electric currents. However, these field

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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

  1. 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.

  2. 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.

  3. 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.

  4. Global Modeling of ULF waves at Mercury

    NASA Astrophysics Data System (ADS)

    Kim, E. H.; Valeo, E. J.; Johnson, J.; Phillips, C.

    2015-12-01

    ULF waves in the ion cyclotron frequency range waves are regularly observed at Mercury's magnetosphere. Although previous statistical studies have shown that ULF waves are primarily compressional near the equator and transverse with linear polarization at higher latitude, the underlying reason for this distribution of wave polarization has not been understood. In order to address this key question, we have developed a two-dimensional, finite element code that solves the full wave equations in global magnetospheric geometry. Using this code, we show that (1) efficient mode conversion from the fast compressional waves to the ion-ion hybrid resonance occurs at Mercury consistent with previous calculations; (2) such mode-converted waves globally oscillate similar to field-line resonance at Earth; and (3) compressional wave energy is primarily localized near the equator, while field-aligned transverse, linearly polarized waves generated by mode conversion at the ion-ion hybrid resonance radiate to higher latitude. Based on these wave solutions, we suggest that the strong transverse component of observed ULF waves at Mercury in high magnetic latitude can be explained as excitation of the field-line resonant waves at the ion-ion hybrid resonance.

  5. Minamata Convention on Mercury

    EPA Pesticide Factsheets

    On November 6, 2013 the United States signed the Minamata Convention on Mercury, a new multilateral environmental agreement that addresses specific human activities which are contributing to widespread mercury pollution

  6. Basic Information about Mercury

    MedlinePlus

    ... globe -- before it is deposited in soil or water. Mercury that remains in the air for prolonged periods of time and travels across continents is said to be in the "global cycle." One major source of mercury emissions outside of ...

  7. 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.

  8. 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.

  9. 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.

  10. Ancient Maya Mercury

    NASA Astrophysics Data System (ADS)

    Pendergast, David M.

    1982-08-01

    Discovery of mercury in an ancient Maya offering at Lamanai, Belize, has stimulated examination of possible sources of the material in the Maya area. Two zones of cinnabar and native mercury deposits can be defined in the Maya highlands, and the presence of the native metal suggests that the ancient Maya collected rather than extracted the mercury from ore.

  11. Dental amalgam and mercury

    SciTech Connect

    Mackert, J.R. Jr. )

    1991-08-01

    This paper looks at the issues of the current amalgam controversy: the daily dose of mercury from amalgam, hypersensitivity to mercury, claims of adverse effects from amalgam mercury and alleged overnight 'cures.' In addition, the toxicity and allergenicity of the proposed alternative materials are examined with the same kind of scrutiny applied by the anti-amalgam group to dental amalgam. 100 references.

  12. 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.

  13. The surface of Mercury: space weathering effects

    NASA Astrophysics Data System (ADS)

    Baratta, G.; Kanuchova, Z.; Palumbo, M. E.; Sangiorgio, I.; Strazzulla, G.

    2011-10-01

    We present some results of an ongoing experimental research aimed at simulating the effects of ion bombardment (space weathering) in solid objects of the Solar System. In particular we have investigated the color changes induced by the ion bombardment in the UV-Vis-IR In this contribution we focus on materials (silicates) and spectral range (200-300 nanometers) particularly relevant to the study of the Mercury's surface.

  14. 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.

  15. 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.

  16. The effect of copper, zinc, mercury and cadmium on some sperm enzyme activities in the common carp (Cyprinus carpio L.).

    PubMed

    Sarosiek, Beata; Pietrusewicz, Marta; Radziwoniuk, Julita; Glogowski, Jan

    2009-11-01

    The objective of the study was to determine the effect of copper, zinc, cadmium and mercury ions (100, 10 and 1 mg/l) on the activity of some enzymes of carp spermatozoa. Acid phosphatase activity was proved to be relatively insensitive to zinc ions, while copper, mercury and cadmium ions effectively inhibited the activity of this enzyme. Beta-N-acetylglucosaminidase activity was sensitive only to mercury ions. Lactic dehydrogenase activity remained unaffected by heavy metals. Our results showed that, among the examined metals, mercury had the strongest inhibitory effect on enzymatic activities.

  17. Dual mode signaling responses of a rhodamine based probe and its immobilization onto a silica gel surface for specific mercury ion detection.

    PubMed

    Pal, Ajoy; Bag, Bamaprasad

    2015-09-14

    A 3-aminomethyl-(2-amino-1-pyridyl) coupled amino-ethyl-rhodamine-B based probe (2) exhibited simultaneous chromogenic and fluorogenic dual mode signaling responses in the presence of Hg(II) ions only among all the metal ions investigated in an organic aqueous medium. The spiro-cyclic rhodamine signaling subunit undergoes complexation induced structural transformation to result in absorption and fluorescence modulation. Its complexation induced signaling exhibited reversibility with various contrasting reagents having higher affinity towards Hg(II) ions, such as anions (AcO(-)) and competing chelating agents (En). It also exhibited Hg(II)-specific photophysical signaling responses when immobilized onto a silica gel surface attached through its amino-ethyl-receptor end, owing to its structure-conformational advantages for effective coordination. The surface modified silica appended with 2 (SiR-1), as evaluated through the FTIR spectral pattern, thermogravimetric analysis, FESEM images, elemental analysis, X-ray diffraction, surface area determination and particle size analysis, also exhibited reversible Hg(II)-specific signaling in its suspension state in an aqueous medium, enhancing the probe's utility for practical applications such as the detection, isolation and extraction of Hg(II) ions in the presence of other competitive metal ions.

  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. 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.

  20. [Chronic occupational metallic mercurialism].

    PubMed

    Faria, Marcília de Araújo Medrado

    2003-02-01

    This is a review on current knowledge of chronic occupational mercurialism syndrome. Major scientific studies and reviews on clinical manifestation and physiopathology of mercury poisoning were evaluated. The search was complemented using Medline and Lilacs data. Erethism or neuropsychological syndrome, characterized by irritability, personality change, loss of self-confidence, depression, delirium, insomnia, apathy, loss of memory, headaches, general pain, and tremors, is seen after exposure to metallic mercury. Hypertension, renal disturbances, allergies and immunological conditions are also common. Mercury is found in many different work processes: industries, gold mining, and dentistry. As prevention measures are not often adopted there is an increasing risk of mercury poisoning. The disease has been under diagnosed even though 16 clinical forms of mercury poisoning are described by Brazilian regulations. Clinical diagnosis is important, especially because abnormalities in the central nervous, renal and immunological systems can be detected using current medical technology, helping to develop the knowledge and control measures for mercurialism.

  1. 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

  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. Radiation synthesized poly( n-vinyl-2-pyrrolidone)-stabilized-gold nanoparticles as LSPR-based optical sensor for mercury ions estimation

    NASA Astrophysics Data System (ADS)

    Misra, Nilanjal; Kumar, Virendra; Goel, Narender Kumar; Varshney, Lalit

    2015-07-01

    Poly( n-vinyl-2-pyrrolidone)-stabilized-gold nanoparticles (PVP-Au-NPs) have been synthesized via a green-60Co-Gamma radiolytic route and employed as a localized surface plasmon resonance (LSPR)-based optical sensor for estimation of trace quantities of Hg2+ ion in aqueous solutions. The in situ generated PVP-Au-NPs were characterized using UV-vis spectroscopy, transmission electron microscopy, and particle size analysis techniques. Reaction conditions were optimized to obtain uniformly dispersed PVP-Au-NPs with average particle size of 7.1 ± 1.6 nm (±s), which exhibited a narrow LSPR band at 527 nm. The decrease in LSPR band intensity of PVP-Au-NPs with increase in Hg2+ ion concentration was found to be linear in the Hg2+ ion concentration range of 0-100 nM. The LSPR-based PVP-Au-NPs optical sensor system was found to be selective for Hg2+ and independent of interference from other metal ions such as Ca2+, Cu2+, Cd2+, and Fe2+ up to a concentration of 500 nM.

  4. 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 ...

  5. 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.

  6. 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

  7. 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)

  8. Measurement of Doubly Charged Ions in Ion Thruster Plumes

    NASA Technical Reports Server (NTRS)

    Williams, George J., Jr.; Domonkos, Matthew T.; Chavez, Joy M.

    2002-01-01

    The ratio of doubly to singly charged ions was measured in the plumes of a 30 cm and of a 40 cm ion thruster. The measured ratio was correlated with observed erosion rates and thruster operating conditions. The measured and calculated erosion rates paralleled variation in the j(sup ++)/j(sup +) ratio and indicated that the erosion was dominated by Xe III. Simple models of cathode potential surfaces which were developed in support of this work were in agreement with this conclusion and provided a predictive capability of the erosion given the ratio of doubly to singly charged ion currents.

  9. Mercury re-emission in flue gas multipollutants simultaneous absorption system.

    PubMed

    Liu, Yue; Wang, Qingfeng; Mei, Rongjun; Wang, Haiqiang; Weng, Xiaole; Wu, Zhongbiao

    2014-12-02

    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.

  10. 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.

  11. 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.

  12. Formation of N, S-codoped fluorescent carbon dots from biomass and their application for the selective detection of mercury and iron ion

    NASA Astrophysics Data System (ADS)

    Ye, Qianghua; Yan, Fanyong; Luo, Yunmei; Wang, Yinyin; Zhou, Xuguang; Chen, Li

    2017-02-01

    Biomass is regarded as an excellent candidate for the preparation of heteroatom-doped carbon nanomaterials. We have developed a simple and facile one-pot synthesis of nitrogen and sulfur codoped fluorescent carbon dots from pigeon feathers, egg and manure via the pyrolysis carbonization method. The as-prepared four PCDs have high fluorescence quantum yield about 24.87% (PCDs-f), 17.48% (PCDs-w), 16.34% (PCDs-y), 33.50% (PCDs-m), respectively, which is higher than the other carbon dots preparing from biomass. We found that the preparation of PCDs-m with pigeon manure has no favourable selectively with heavy metal ions. However, other PCDs exhibit highly sensitive and selective detection behavior of Hg2 +/Fe3 + ions with a low detection limit of 10.3 and 60.9 nM. They were applied to imaging of human umbilical vein endothelial cells, showing low cytotoxicity and good biocompatibility.

  13. Formation of N, S-codoped fluorescent carbon dots from biomass and their application for the selective detection of mercury and iron ion.

    PubMed

    Ye, Qianghua; Yan, Fanyong; Luo, Yunmei; Wang, Yinyin; Zhou, Xuguang; Chen, Li

    2017-02-15

    Biomass is regarded as an excellent candidate for the preparation of heteroatom-doped carbon nanomaterials. We have developed a simple and facile one-pot synthesis of nitrogen and sulfur codoped fluorescent carbon dots from pigeon feathers, egg and manure via the pyrolysis carbonization method. The as-prepared four PCDs have high fluorescence quantum yield about 24.87% (PCDs-f), 17.48% (PCDs-w), 16.34% (PCDs-y), 33.50% (PCDs-m), respectively, which is higher than the other carbon dots preparing from biomass. We found that the preparation of PCDs-m with pigeon manure has no favourable selectively with heavy metal ions. However, other PCDs exhibit highly sensitive and selective detection behavior of Hg(2+)/Fe(3+) ions with a low detection limit of 10.3 and 60.9nM. They were applied to imaging of human umbilical vein endothelial cells, showing low cytotoxicity and good biocompatibility.

  14. Ultrasensitive SERS Substrate Integrated with Uniform Subnanometer Scale "Hot Spots" Created by a Graphene Spacer for the Detection of Mercury Ions.

    PubMed

    Zhang, Xingang; Dai, Zhigao; Si, Shuyao; Zhang, Xiaolei; Wu, Wei; Deng, Hongbing; Wang, Fubing; Xiao, Xiangheng; Jiang, Changzhong

    2017-03-01

    Mercuric ion (Hg(2+) ) is one of the most toxic and serious environment polluting heavy metal ions, which can be accumulated in human body through food chains and drinking water, and causes serious damage to human organs. Therefore, development of the efficient and sensitive method for detection of Hg(2+) is very necessary. In this study, the high surface sensitivity and fingerprint information about the chemical structures based on surface-enhanced Raman scattering (SERS) for sensing applications are taken advantage of. Au triangular nanoarrays/n-layer graphene/Au nanoparticles sandwich structure with large-area uniform subnanometer gaps are fabricated and used to detect Hg(2+) in water via thymine-Hg(2+) -thymine coordination; the detection limit of Hg(2+) is as low as 8.3 × 10(-9) m. Moreover, this SERS substrate is used to detect the Hg(2+) -contaminated sandy soil and shows excellent performance. This study indicates the sandwich structure has a great potential in detection of toxic metal ions and environmental pollutants.

  15. Determination of mercury(II) ions in seafood samples after extraction and preconcentration by a novel functionalized magnetic metal-organic framework nanocomposite.

    PubMed

    Ghorbani-Kalhor, Ebrahim; Hosseinzadeh-Khanmiri, Rahim; Abolhasani, Jafar; Babazadeh, Mirzaagha; Hassanpour, Akbar

    2015-04-01

    This work describes a novel functionalized magnetic metal-organic framework nanocomposite [(Fe3O4-2,5-dimercapto-1,3,4-thiadiazole)/metal-organic framework] and its application in the preconcentration of Hg(II) ions. The parameters affecting the preconcentration procedure were optimized by a Box-Behnken design through response surface methodology. Three variables (uptake time, magnetic nanosorbent amount, and pH value) were selected as the main factors affecting the sorption step, while four variables (type, volume, and concentration of the eluent; and elution time) were selected as main factors in the optimization study of the elution step. Following the sorption and elution of analytes, the ions were quantified by cold vapor atomic absorption spectrometry. Under the optimum conditions, the limit of detection was 0.01 ng/mL and all the relative standard deviations were less than 10%. The obtained sorption capacity (in mg/g) of this new sorbent was 124. Ultimately, this nanocomposite was successfully applied to the rapid extraction of trace quantities of Hg(II) ions in seafood samples and satisfactory results were obtained.

  16. 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.

  17. 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.'

  18. Thallium Mercury Laser Development

    DTIC Science & Technology

    1981-01-01

    THALLIUM MERCURY LASER DEVELOPMENT C. S. Liu and D. W. Feldman FINAL REPORT (PHASE III) (Period between Feb. 1, 1980 and Jan. 31, 1981) 0 Contract No...Pittsburgh, Pennsylvania 15235 Approved for public release;IDistribution Unlimited 1/i;THALLIUM MERCURY LASER DEVELOPMENT * , , IS C. S./Liu tRD. W /eldman...9 ’ t4 THALLIUM MERCURY LASER DEVELOPMENT C. S. Liu and D. W. Feldman Westinghouse R&D Center Pittsburgh, Pennsylvania 15235 1

  19. 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.

  20. An ion-optical bench for testing ion source lenses

    NASA Astrophysics Data System (ADS)

    Stoffels, J. J.; Ells, D. R.

    1988-06-01

    An ion-optical bench has been designed and constructed to obtain experimental data on the focusing properties of ion lenses in three dimensions. The heart of the apparatus is a position-sensitive detector (PSD) that gives output signals proportional to the x and y positions of each ion impact. The position signals can be displayed on an oscilloscope screen and analyzed by a two-parameter pulse-height analyzer, thereby giving a visual picture of the ion beam cross section and intensity distribution. The PSD itself is mounted on a track and is movable during operation from a position immediately following the ion lens to 30 cm away. This enables the rapid collection of accurate data on the intensity distribution and divergence angles of ions leaving the source lens. Examples of ion lens measurements are given.

  1. 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

  2. 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.

  3. Mercury recovery results of microwave digested tritium facility pump oil

    SciTech Connect

    Whitaker, M.J.; Clymire, J.W.

    1997-09-30

    This report is a follow up of work done earlier this year and recorded in document WSRC-RP-97-322. The scope of this document is to demonstrated the viability of digesting two non-radioactive Tritium facility pump oils, Welch Duoseal and Spindura, neat and spiked with low-level mercury to determine completeness of digestion and recoverability of mercury. As noted in document WSRC-RP-97-322 a microwave digestion methodology was developed with CEM`s ultimate digestion vessel system (UDV) and is the technique used for the follow up task of digesting the above mention pump oils for the preparatory step of cold-vapor mercury analysis.All analytical development for this project was performed at TNX. The determination of the mercury concentration in each digested sample was by cold vapor atomic absorption. The instrument used was a Varian SpectrAA 800 with a vapor generation attachment. This flameless AA procedure is a physical method based on the absorption of radiation at 253.7 nm of mercury vapor. Organo-mercury compounds will not respond to the cold vapor atomic absorption technique, therefore, to acquire a total mercury value it is necessary for a complete digestion to oxidize and convert the organo-mercury species to the mercuric ion.

  4. Colorimetric sensing of silver(I) and mercury(II) ions based on an assembly of Tween 20-stabilized gold nanoparticles.

    PubMed

    Lin, Cheng-Yan; Yu, Cheng-Ju; Lin, Yen-Hsiu; Tseng, Wei-Lung

    2010-08-15

    We have developed a rapid and homogeneous method for the highly selective detection of Hg(2+) and Ag(+) using Tween 20-modified gold nanoparticles (AuNPs). Citrate ions were found to still be adsorbed on the Au surface when citrate-capped AuNPs were modified with Tween 20, which stabilizes the citrate-capped AuNPs against conditions of high ionic strength. When citrate ions had reduced Hg(2+) and Ag(+) to form Hg-Au alloys and Ag on the surface of the AuNPs, Tween 20 was removed from the NP surface. As a result, the AuNPs were unstable under a high-ionic-strength solution, resulting in NP aggregation. The formation of Hg-Au alloys or Ag on the surface of the AuNPs was demonstrated by means of inductively coupled plasma mass spectroscopy and energy-dispersive X-ray spectroscopy. Tween 20-AuNPs could selectively detect Hg(2+) and Ag(+) at concentrations as low as 0.1 and 0.1 microM in the presence of NaCl and EDTA, respectively. Moreover, the probe enables the analysis of AgNPs with a minimum detectable concentration that corresponds to 1 pM. This probe was successfully applied to detect Hg(2+) in drinking water and seawater, Ag(+) in drinking water, and AgNPs in drinking water.

  5. Inclusion of Ethyl Acetoacetate Bearing 7-Hydroxycoumarin Dye by β-Cyclodextrin and its Cooperative Assembly with Mercury(II) Ions: Spectroscopic and Molecular Modeling Studies.

    PubMed

    Aliaga, Margarita E; Fierro, Angélica; Uribe, Iván; García-Río, Luis; Cañete, Álvaro

    2016-10-18

    The inclusion of the fluorescent organic dye, ethyl 3-(7-hydroxy-2-oxo-2H-chromen-3-yl)-3-oxopropanoate (1) by the host β-cyclodextrin (β-CD), and its response toward mercuric ions (Hg(2+) ), was studied by UV/Vis, fluorescence, and (1) H NMR spectroscopic analyses, mass spectrometry and molecular modeling studies. (1) H NMR measurements together with molecular modeling studies for dye 1 demonstrate that it exhibits two tautomeric forms (keto and enol); however, when the dye is included into the β-CD cavity, the enol form predominates. Moreover, by using spectroscopic and spectrometry techniques, a 1:1 stoichiometry was determined for the complexes formed between dye 1 (enol form) and β-CD, with a binding constant (Kb1 =1.8×10(4)  m(-1) ) and for the dye 1 (keto form)-Hg(2+) (Kb2 =2.3×10(3)  m(-1) ). Interestingly, in the presence of 1-β-CD complex and mercuric ions, a ternary supramolecular system (Hg-1-β-CD complex) was established, with a 1:1:1 stoichiometry and a Kb3 value of 4.3×10(3)  m(-1) , with the keto form of the dye being the only one present in this assembly. The three-component system provides a starting point for the development of novel and directed supramolecular assemblies.

  6. Organic mercury levels among the Yanomama of the Brazilian Amazon Basin.

    PubMed

    Sing, Kimberly Anne; Hryhorczuk, Daniel; Saffirio, Giovanni; Sinks, Thomas; Paschal, Daniel C; Sorensen, John; Chen, Edwin H

    2003-11-01

    The Catrimani River basin in northern Brazil is the home of the Yanomama and has been the site of renegade gold mining since 1980. Gold-mining operations release inorganic mercury (Hg) into the environment where it is organified and biomagnified in aquatic ecosystems. Ingestion of mercury-contaminated fish poses a potential hazard to fish-eating populations such as the Yanomama. We surveyed Hg levels in Yanomama villagers living near mined and unmined rivers in 1994 and 1995, and analyzed Hg levels in piranha caught by villagers. In 1994, 90 Yanomama Indians from 5 villages and in 1995, 62 Yanomama Indians from 3 villages participated in the studies. Four villages surveyed in 1994 were located directly on the Catrimani River, approximately 140-160 km downstream from past gold-mining activities. The other village surveyed in 1994 was situated on the unmined Ajaraní River. In 1995, 2 of the Catrimani River villages were revisited, and a third Yanomama village, on the unmined Pacu River, was surveyed. Blood organic mercury levels among all villagers surveyed ranged from 0 to 62.6 microg L(-1) (mean levels in each village between 21.2 microg L(-1) and 43.1 microg L(-1)). Mercury levels in piranha from the mined Catrimani River ranged from 235 to 1084 parts per billion (ppb). Nine of 13 piranhas, measuring 30 cm or longer had total mercury levels which exceeded mercury consumption limits (500 ppb) set by both the World Health Organization and the Brazilian Ministry of Health. Unexpectedly, high mercury levels were also observed in fish and villagers along the unmined Ajaraní and Pacu Rivers suggesting that indirect sources may contribute to environmental mercury contamination in the Amazon basin.

  7. Modeling Mercury in Proteins

    SciTech Connect

    Smith, Jeremy C; Parks, Jerry M

    2016-01-01

    Mercury (Hg) is a naturally occurring element that is released into the biosphere both by natural processes and anthropogenic activities. Although its reduced, elemental form Hg(0) is relatively non-toxic, other forms such as Hg2+ and, in particular, its methylated form, methylmercury, are toxic, with deleterious effects on both ecosystems and humans. Microorganisms play important roles in the transformation of mercury in the environment. Inorganic Hg2+ can be methylated by certain bacteria and archaea to form methylmercury. Conversely, bacteria also demethylate methylmercury and reduce Hg2+ to relatively inert Hg(0). Transformations and toxicity occur as a result of mercury interacting with various proteins. Clearly, then, understanding the toxic effects of mercury and its cycling in the environment requires characterization of these interactions. Computational approaches are ideally suited to studies of mercury in proteins because they can provide a detailed picture and circumvent issues associated with toxicity. Here we describe computational methods for investigating and characterizing how mercury binds to proteins, how inter- and intra-protein transfer of mercury is orchestrated in biological systems, and how chemical reactions in proteins transform the metal. We describe quantum chemical analyses of aqueous Hg(II), which reveal critical factors that determine ligand binding propensities. We then provide a perspective on how we used chemical reasoning to discover how microorganisms methylate mercury. We also highlight our combined computational and experimental studies of the proteins and enzymes of the mer operon, a suite of genes that confers mercury resistance in many bacteria. Lastly, we place work on mercury in proteins in the context of what is needed for a comprehensive multi-scale model of environmental mercury cycling.

  8. Biotoxicity of mercury as influenced by mercury(II) speciation.

    PubMed

    Farrell, R E; Germida, J J; Huang, P M

    1990-10-01

    Integration of physicochemical procedures for studying mercury(II) speciation with microbiological procedures for studying the effects of mercury on bacterial growth allows evaluation of ionic factors (e.g., pH and ligand species and concentration) which affect biotoxicity. A Pseudomonas fluorescens strain capable of methylating inorganic Hg(II) was isolated from sediment samples collected at Buffalo Pound Lake in Saskatchewan, Canada. The effect of pH and ligand species on the toxic response (i.e., 50% inhibitory concentration [IC50]) of the P. fluorescens isolated to mercury were determined and related to the aqueous speciation of Hg(II). It was determined that the toxicities of different mercury salts were influenced by the nature of the co-ion. At a given pH level, mercuric acetate and mercuric nitrate yielded essentially the same IC50s; mercuric chloride, on the other hand, always produced lower IC50s. For each Hg salt, toxicity was greatest at pH 6.0 and decreased significantly (P = 0.05) at pH 7.0. Increasing the pH to 8.0 had no effect on the toxicity of mercuric acetate or mercuric nitrate but significantly (P = 0.05) reduced the toxicity of mercuric chloride. The aqueous speciation of Hg(II) in the synthetic growth medium M-IIY (a minimal salts medium amended to contain 0.1% yeast extract and 0.1% glycerol) was calculated by using the computer program GEOCHEM-PC with a modified data base. Results of the speciation calculations indicated that complexes of Hg(II) with histidine [Hg(H-HIS)HIS+ and Hg(H-HIS)2(2+)], chloride (HgCl+, HgCl2(0), HgClOH0, and HgCl3-), phosphate (HgHPO4(0), ammonia (HgNH3(2+), glycine [Hg(GLY)+], alanine [Hg(ALA)+], and hydroxyl ion (HgOH+) were the Hg species primarily responsible for toxicity in the M-IIY medium. The toxicity of mercuric nitrate at pH 8.0 was unaffected by the addition of citrate, enhanced by the addition of chloride, and reduced by the addition of cysteine. In the chloride-amended system, HgCl+, HgCl2(0), and Hg

  9. 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.

  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 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.

  12. 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 ...

  13. 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...

  14. 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

  15. Dynamic duo captures mercury

    SciTech Connect

    Senior, C.; Adams, B.

    2006-02-15

    There is strong evidence that the combination of wet flue gas desulphurisation (FGD) scrubbers and selective catalytic reduction (SCR) can prove a viable and formidable combination for knocking out mercury. This article analyzes the capabilities and limitations of the SCR-FGD combination for mercury compliance, including applicability to different types of coal and issues with scrubber by-products. 3 figs.

  16. Mercury in the environment

    ScienceCinema

    Idaho National Laboratory - Mike Abbott

    2016-07-12

    Abbott works for Idaho National Laboratory as an environmental scientist. Using state-of-thescienceequipment, he continuously samples the air, looking for mercury. In turn, he'll analyzethis long-term data and try to figure out the mercury's point of or

  17. Mercury: the forgotten planet.

    NASA Astrophysics Data System (ADS)

    Nelson, R. M.

    1997-11-01

    Mercury is the neglected child of the planetary system. Only one spacecraft has every ventured near it, whereas scores have probed the moon, Venus and Mars. The scant facts available show this strange, blazingly hot planet is full of surprises: its anomalous density and magnetic field suggest that Mercury may be where to seek clues to the origin of the solar system.

  18. 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

  19. 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.

  20. Mercury poisoning in wildlife

    USGS Publications Warehouse

    Heinz, G.H.; Fairbrother, Anne; Locke, Louis N.; Hoff, Gerald L.

    1996-01-01

    Mercury is an intriguing contaminant because it has complex chemical properties, a wide range of harmful effects, and an infinite persistence in the environment. Die-offs of wildlife due to mercury have occurred in many countries, especially before mercury seed dressings were banned. Today, most mercury problems are associated with aquatic environments. Methylmercury, the most toxic chemical form, attacks many organ systems, but damage to the central nervous system is most severe. Harmful wet-weight concentrations of mercury, as methylmercury, in the tissues of adult birds and mammals range from about 8-30 ppm in the brain, 20-60 ppm in liver, 20-60 ppm in kidney, and 15-30 ppm in muscle. Young animals may be more sensitive.

  1. Development and Applications of Fluorogenic Probes for Mercury(II) Based on Vinyl Ether Oxymercuration

    PubMed Central

    Ando, Shin; Koide, Kazunori

    2011-01-01

    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 for drinking water, 1–2 ppb. We developed a fluorescence method based on the oxymercuration of vinyl ethers to detect mercury in dental and environmental samples. Chloride ions interfered with the oxymercuration reaction, but the addition of AgNO3 solved this problem. Fine electronic and structural tuning led to the development of a more responsive probe that was less sensitive to chloride ion interference. This second generation probe could detect 1 ppb mercury ions in water. PMID:21294513

  2. 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…

  3. 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

  4. Ultrasensitive and selective detection of copper (II) and mercury (II) ions by dye-coded silver nanoparticle-based SERS probes.

    PubMed

    Li, Feng; Wang, Jing; Lai, Yuming; Wu, Chong; Sun, Shuqing; He, Yonghong; Ma, Hui

    2013-01-15

    A simple and distinctive method for the ultrasensitive detection of Cu(2+) and Hg(2+) based on surface-enhanced Raman scattering (SERS) using cysteine-functionalized silver nanoparticles (AgNPs) attached with Raman-labeling molecules was developed. The glycine residue in a silver nanoparticle-bound cysteine can selectively bind with Cu(2+) and Hg(2+) and form a stable inner complex. Silver nanoparticles co-functionalized with cysteine and 3,5-Dimethoxy-4-(6'-azobenzotriazolyl)phenol (AgNP conjugates) can be used to detect Cu(2+) and Hg(2+) based on aggregation-induced SERS of the Raman tags. The addition of SCN(-) to the analyte can successfully mask Hg(2+) and allow for the selective detection of Cu(2+). This SERS-based assay showed an unprecedented limit of detection (LOD) of 10pM for Cu(2+) and 1pM for Hg(2+); these LODs are a few orders of magnitude more sensitive than the typical colorimetric approach based on the aggregation of noble nanoparticles. The analysis of real water samples diluted with pure water was performed and verified this conclusion. We envisage that this SERS-based assay may provide a general and simple approach for the detection of other metal ions of interest, which can be adopted from their corresponding colorimetric assays that have already been developed with significantly improved sensitivity and thus have wide-range applications in many areas.

  5. 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.

  6. Mercury in the surface soil and cassava, Manihot esculenta (flesh, leaves and peel) near goldmines at Bogoso and Prestea, Ghana.

    PubMed

    Adjorlolo-Gasokpoh, A; Golow, A A; Kambo-Dorsa, J

    2012-12-01

    Mercury amalgamation is used indiscriminately in the recovery of gold by small-scale native gem winners in Ghana. Mercury is released into the environment in the form of wastewater, tailing and vapor from the roasting of amalgam to separate gold. The study looked at the levels of total mercury concentration in surface soil and cassava crop from farms located within the vicinities of Bogoso and Prestea Goldmines. The surface soil total mercury concentrations ranged between 125.29 and 352.52 μg/kg whiles cassava had between 66.60 and 195.47 μg/kg. The results showed proportionately more deposits at higher distances in 15-30 cm soil zone and less deposits at higher distances on leaves with relatively high uptake of the metal occurred at higher distances from the mines into the peels. These results suggest serious mercury pollution to the surface soil and the cassava crop but the speciation exercise showed that mercury is not in the free state, rather bound to hydroxides and organic compounds as complexes.

  7. 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.

  8. 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.

  9. 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.

  10. Diketopyrrolopyrrole Amphiphile-Based Micelle-Like Fluorescent Nanoparticles for Selective and Sensitive Detection of Mercury(II) Ions in Water.

    PubMed

    Nie, Kaixuan; Dong, Bo; Shi, Huanhuan; Liu, Zhengchun; Liang, Bo

    2017-03-07

    A technique for encapsulating fluorescent organic probes in a micelle system offers an important alternative method to manufacture water-soluble organic nanoparticles (ONPs) for use in sensing Hg(2+). This article reports on a study of a surfactant-free micelle-like ONPs based on a 3,6-di(2-thienyl)-2,5-dihydropyrrolo[3,4-c]pyrrole-1,4-dione (TDPP) amphiphile, (2-(2-(2-methoxyethoxy)ethyl)-3,6-di(2-thiophyl)-2,5-dihydropyrrolo[3,4-c]pyrrole-1,4-dione (NDPP) fabricated to monitor Hg(2+) in water. NDPP was synthesized through a simple one-step modification of a commercially available dye TDPP with a flexible and hydrophilic alkoxy. This study reports, for the first time, that TDPP dyes can respond reversibly, sensitively, and selectively to Hg(2+) through TDPP-Hg-TDPP complexation, similar to the well-known thymine(T)-Hg-thymine(T) model and the accompanying molecular aggregation. Interestingly, transmission electron microscopy (TEM) and dynamic light scattering (DLS) confirmed that, in water, NDPP forms loose micelle-like fluorescent ONPs with a hydrohobic TDPP portion encapsulated inside. These micelle-like nanoparticles offer an ideal location for TDPP-Hg complexation with a modest molecular aggregation, thereby providing both clear visual and spectroscopic signals for Hg(2+) sensing. An estimated detection limit of 11 nM for Hg(2+) sensing with this NDPP nanoparticle was obtained. In addition, NDPP ONPs show good water solubility and high selectivity to Hg(2+) in neutral or alkalescent water. It was superior to most micelle-based nanosensors, which require a complicated process in the selection or synthesis of suitable surfactants. The determinations in real samples (river water) were made and satisfactory results were achieved. This study provides a low-cost strategy for fabricating small molecule-based fluorescent nanomaterials for use in sensing Hg(2+). Moreover, the NDPP nanoparticles show potential ability in Hg(2+) ion adsorption and recognization of

  11. Characteristics of atmospheric mercury deposition and size-fractionated particulate mercury in urban Nanjing, China

    NASA Astrophysics Data System (ADS)

    Zhu, J.; Wang, T.; Talbot, R.; Mao, H.; Yang, X.; Fu, C.; Sun, J.; Zhuang, B.; Li, S.; Han, Y.; Xie, M.

    2014-03-01

    A comprehensive measurement study of mercury wet deposition and size-fractionated particulate mercury (HgP) concurrent with meteorological variables was conducted from June 2011 to February 2012 to evaluate the characteristics of mercury deposition and particulate mercury in urban Nanjing, China. The volume-weighted mean (VWM) concentration of mercury in rainwater was 52.9 ng L-1 with a range of 46.3-63.6 ng L-1. The wet deposition per unit area was averaged 56.5 μg m-2 over 9 months, which was lower than that in most Chinese cities, but much higher than annual deposition in urban North America and Japan. The wet deposition flux exhibited obvious seasonal variation strongly linked with the amount of precipitation. Wet deposition in summer contributed more than 80% to the total amount. A part of contribution to wet deposition of mercury from anthropogenic sources was evidenced by the association between wet deposition and sulfates, as well as nitrates in rainwater. The ions correlated most significantly with mercury were formate, calcium, and potassium, which suggested that natural sources including vegetation and resuspended soil should be considered as an important factor to affect the wet deposition of mercury in Nanjing. The average HgP concentration was 1.10 ± 0.57 ng m-3. A distinct seasonal distribution of HgP concentrations was found to be higher in winter as a result of an increase in the PM10 concentration. Overall, more than half of the HgP existed in the particle size range less than 2.1 μm. The highest concentration of HgP in coarse particles was observed in summer, while HgP in fine particles dominated in fall and winter. The size distribution of averaged mercury content in particulates was bimodal, with two peaks in the bins of < 0.7 μm and 4.7-5.8 μm. Dry deposition per unit area of HgP was estimated to be 47.2 μg m-2 using meteorological conditions and a size-resolved particle dry deposition model. This was 16.5% less than mercury wet

  12. 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.

  13. Thallium Mercury Laser Development.

    DTIC Science & Technology

    1980-04-17

    AD-A9 840 WESTINGHOUSE RESEARCH AND DEVELOPMENT CENTER PITTSBU--ETC F/A 20/5 THALLIUM MERCURY LASER DEVELOPMENT .(U) APR 80 C S LIU, D W FELDMAN, J L...PACK NO001I78-C-0131 lIlrt A nEQE-WOTFX-R NL THALLIUM MERCURY LASER DEVELOPMENT C. S. Liu, D. W. Feldman and J. L. Pack FINAL REPORT (PHASE II...PERIOD COVERED Thallium Mercury Laser Development -T- Final Report (Phase II) Feb. 1, 1979 to Jan. 31, 1980 77a. w-atF. -REPORT NUMBER _,___C2-OTEX

  14. 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.

  15. 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.

  16. Mercury cycling in terrestrial watersheds

    USGS Publications Warehouse

    Shanley, James B.; Bishop, Kevin; Banks, Michael S.

    2012-01-01

    This chapter discusses mercury cycling in the terrestrial landscape, including inputs from the atmosphere, accumulation in soils and vegetation, outputs in streamflow and volatilization, and effects of land disturbance. Mercury mobility in the terrestrial landscape is strongly controlled by organic matter. About 90% of the atmospheric mercury input is retained in vegetation and organic matter in soils, causing a buildup of legacy mercury. Some mercury is volatilized back to the atmosphere, but most export of mercury from watersheds occurs by streamflow. Stream mercury export is episodic, in association with dissolved and particulate organic carbon, as stormflow and snowmelt flush organic-rich shallow soil horizons. The terrestrial landscape is thus a major source of mercury to downstream aquatic environments, where mercury is methylated and enters the aquatic food web. With ample organic matter and sulfur, methylmercury forms in uplands as well—in wetlands, riparian zones, and other anoxic sites. Watershed features (topography, land cover type, and soil drainage class) are often more important than atmospheric mercury deposition in controlling the amount of stream mercury and methylmercury export. While reductions in atmospheric mercury deposition may rapidly benefit lakes, the terrestrial landscape will respond only over decades, because of the large stock and slow turnover of legacy mercury. We conclude with a discussion of future scenarios and the challenge of managing terrestrial mercury.

  17. FIELD MEASUREMENT TECHNOLOGY FOR MERCURY IN ...

    EPA Pesticide Factsheets

    Monitoring Technologies International Pty. Ltd. (MTI) has developed a Portable Digital Voltammeter (PDV) designed to identify and measure the concentration of heavy metal ions. MTI's PDV 6000 was demonstrated under the U.S. Environmental Protection Agency Superfund Innovative Technology Evaluation Program in June 2003 in Las Vegas, Nevada. The purpose of the Demonstration was to collect reliable performance and cost data for the PDV 6000. Four other field measurement devices for mercury in soil and sediment were evaluated in May 2003 at the Oak Ridge National Laboratory in Oak Ridge, Tennessee. The key objectives of the Demonstration were: 1) determine sensitivity of each instrument with respect to a vendor-generated method detection limit (MDL) and practical quantitation limit (PQL); 2) determine potential analytical accuracy associated with vendor field measurements; 3) evaluate the precision of vendor field measurements; 4) measure time required to perform mercury measurements; and 5) estimate costs associated with mercury measurements for capital, labor, supplies, and investigation-derived wastes (IDW). The Demonstration also involved analysis of standard reference materials (SRMs), field samples collected from four sites, and spiked field samples for mercury. The performance results for a given field measurement device were compared to those for an off-site laboratory using reference method,

  18. 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.

  19. Discovery of calcium in Mercury's atmosphere.

    PubMed

    Bida, T A; Killen, R M; Morgan, T H

    2000-03-09

    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.

  20. 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.

  1. The Study of Mercury

    NASA Astrophysics Data System (ADS)

    Prockter, Louise M.; Bedini, Peter D.

    2010-01-01

    When the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft enters orbit about Mercury in March 2011 it will begin a new phase in an age-old scientific study of the innermost planet. Despite being visible to the unaided eye, Mercury's proximity to the Sun makes it extremely difficult to observe from Earth. Nonetheless, over the centuries man has pursued a quest to understand the elusive planet, and has teased out information about its motions in the sky, its relation to the other planets, and its physical characteristics. A great leap was made in our understanding of Mercury when the Mariner 10 spacecraft flew past it three times in the mid-1970s, providing a rich set of close-up observations. Now, three decades later, The MESSENGER spacecraft has also visited the planet three times, and is poised to add significantly to the study with a year-long orbital observation campaign.

  2. 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.

  3. High frequency plasma generators for ion thruster applications

    NASA Technical Reports Server (NTRS)

    Divergilio, W. F.; Goede, H.; Komatsu, G. K.; Christensen, T.

    1981-01-01

    Two concepts for high frequency discharge ion thrusters are described. Both sources are designed for use with 30 cm grid sets and argon propellant and utilize multi-cusp permanent magnet geometries for plasma confinement. The RF induction source is a conventional design representing a synthesis of the RIT and multi-cusp concepts. The preliminary data (without system optimization) indicate a discharge efficiency comparable to that obtained in 30 cm hollow cathode multi-cusp argon thrusters. The electron cyclotron heating source is electrodeless and exhibits plasma characteristics which should lead to greatly reduced discharge chamber and screen sputter rates with the optimization of the magnetic fields, microwave frequency, and feed configuration.

  4. Ecosystem conceptual model- Mercury

    USGS Publications Warehouse

    Alpers, Charles N.; Eagles-Smith, Collin A.; Foe, Chris; Klasing, Susan; Marvin-DiPasquale, Mark C.; Slotton, Darell G.; Windham-Myers, Lisamarie

    2008-01-01

    Mercury has been identified as an important contaminant in the Delta, based on elevated concentrations of methylmercury (a toxic, organic form that readily bioaccumulates) in fish and wildlife. There are health risks associated with human exposure to methylmercury by consumption of sport fish, particularly top predators such as bass species. Original mercury sources were upstream tributaries where historical mining of mercury in the Coast Ranges and gold in the Sierra Nevada and Klamath-Trinity Mountains caused contamination of water and sediment on a regional scale. Remediation of abandoned mine sites may reduce local sources in these watersheds, but much of the mercury contamination occurs in sediments stored in the riverbeds, floodplains, and the Bay- Delta, where scouring of Gold-Rush-era sediment represents an ongoing source.Conversion of inorganic mercury to toxic methylmercury occurs in anaerobic environments including some wetlands. Wetland restoration managers must be cognizant of potential effects on mercury cycling so that the problem is not exacerbated. Recent research suggests that wettingdrying cycles can contribute to mercury methylation. For example, high marshes (inundated only during the highest tides for several days per month) tend to have higher methylmercury concentrations in water, sediment, and biota compared with low marshes, which do not dry out completely during the tidal cycle. Seasonally inundated flood plains are another environment experiencing wetting and drying where methylmercury concentrations are typically elevated. Stream restoration efforts using gravel injection or other reworking of coarse sediment in most watersheds of the Central Valley involve tailings from historical gold mining that are likely to contain elevated mercury in associated fines. Habitat restoration projects, particularly those involving wetlands, may cause increases in methylmercury exposure in the watershed. This possibility should be evaluated.The DRERIP

  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

    2014-06-02

    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.

  6. 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

  7. 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.

  8. 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.

  9. 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

  10. 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.

  11. 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.

  12. Mercury exposure and public health.

    PubMed

    Clifton, Jack C

    2007-04-01

    Mercury is a metal that is a liquid at room temperature. Mercury has a long and interesting history deriving from its use in medicine and industry, with the resultant toxicity produced. In high enough doses, all forms of mercury can produce toxicity. The most devastating tragedies related to mercury toxicity in recent history include Minamata Bay and Niagata, Japan in the 1950s, and Iraq in the 1970s. More recent mercury toxicity issues include the extreme toxicity of the dimethylmercury compound noted in 1998, the possible toxicity related to dental amalgams, and the disproved relationship between vaccines and autism related to the presence of the mercury-containing preservative, thimerosal.

  13. Blood serum mercury test report.

    PubMed

    Vandenberge, J; Moodie, A S; Keller, R E

    1977-06-01

    A clinical blood serum mercury test of 111 dentists and auxiliaries revelaed that more than 50% had above normal serum mercury levels. This study showed that there may be a mercury health hazard in some dental environments. Acute mercury poisoning may be corrected simply by removing the cause, but long-term chronic effects are not known. Frequent screening of offices and personnel is advised. Experience reported here indicates that large amounts of mercury vapor are emitted when an amalgam carrier is heated over a flame ot dislodge particles, and also, that water-covered amalgam scrap relesases mercury vapor.

  14. 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.

  15. [Activity of antioxidant enzymes of the rat kidneys under mercury dichloride effect].

    PubMed

    Velyka, A Ia; Pshak, V P; Lopushins'ka, I V

    2014-01-01

    Salts of heavy metals are excreted by the kidneys and, as pro-oxidants, stimulate the processes of free radical oxidation. Mercury ions are accumulated in the kidneys. So the study of the features of antioxidant enzymes adaptive response of different kidney layers in response to mercury dichloride is important. Catalase and glytathionperoxidase activity within rat kidneys 72 hours after mercury dichloride intoxication in the ratio of 5 ml per 1 kg of the animal weight was studied. It was important to reveal the influence of the mercury salts on rat kidney antioxidative system. Decreasing glytathionperoxidase activity in cortical and cerebral substances and renal papillae were accompanied by increased contents of oxidative modified proteins and lipids and morphological changes in renal tissue under salt and water loading after mercury dichloride poisoning. The results obtained evidence for the inhibition of antioxidative protection of enzymes in rat kidneys under the mercury dichloride effect.

  16. 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.

  17. 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.

  18. 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.

  19. Gold nanorods for surface Plasmon resonance detection of mercury (II) in flow injection analysis.

    PubMed

    Trieu, Khang; Heider, Emily C; Brooks, Scott C; Barbosa, Fernando; Campiglia, Andres D

    2014-10-01

    This article investigates the flow injection analysis of mercury (II) ions in tap water samples via surface Plasmon resonance detection. Quantitative analysis of mercury (II) is based on the chemical interaction of metallic mercury with gold nanorods immobilized on a glass substrate. A new flow cell design is presented with the ability to accommodate the detecting substrate in the sample compartment of commercial spectrometers. Two alternatives are here considered for mercury (II) detection, namely stop-flow and continuous flow injection analysis modes. The best limit of detection (2.4 ng mL(-1)) was obtained with the continuous flow injection analysis approach. The accurate determination of mercury (II) ions in samples of unknown composition is demonstrated with a fortified tap water sample.

  20. 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.

  1. 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...

  2. 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

  3. 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.

  4. 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.

  5. Mercury Emissions: The Global Context

    EPA Pesticide Factsheets

    Mercury emissions are a global problem that knows no national or continental boundaries. Mercury that is emitted to the air can travel thousands of miles in the atmosphere before it is eventually deposited back to the earth.

  6. Mercury Study Report to Congress

    EPA Pesticide Factsheets

    EPA's Report to Congress on Mercury provides an assessment of the magnitude of U.S. mercury emissions by source, the health and environmental implications of those emissions, and the availability and cost of control technologies.

  7. Mercury (Environmental Health Student Portal)

    MedlinePlus

    ... Pollutants Natural Disasters Drinking Water Waterborne Diseases & Illnesses Water Cycle Water Treatment Videos Games Experiments For Teachers Home ... Pollutants Natural Disasters Drinking Water Waterborne Diseases & Illnesses Water Cycle Water Treatment Mercury The Basics Mercury — sometimes called ...

  8. Stoichiometry and kinetics of mercury uptake by photosynthetic bacteria.

    PubMed

    Kis, Mariann; Sipka, Gábor; Maróti, Péter

    2017-03-04

    Mercury adsorption on the cell surface and intracellular uptake by bacteria represent the key first step in the production and accumulation of highly toxic mercury in living organisms. In this work, the biophysical characteristics of mercury bioaccumulation are studied in intact cells of photosynthetic bacteria by use of analytical (dithizone) assay and physiological photosynthetic markers (pigment content, fluorescence induction, and membrane potential) to determine the amount of mercury ions bound to the cell surface and taken up by the cell. It is shown that the Hg(II) uptake mechanism (1) has two kinetically distinguishable components, (2) includes co-opted influx through heavy metal transporters since the slow component is inhibited by Ca(2+) channel blockers, (3) shows complex pH dependence demonstrating the competition of ligand binding of Hg(II) ions with H(+) ions (low pH) and high tendency of complex formation of Hg(II) with hydroxyl ions (high pH), and (4) is not a passive but an energy-dependent process as evidenced by light activation and inhibition by protonophore. Photosynthetic bacteria can accumulate Hg(II) in amounts much (about 10(5)) greater than their own masses by well-defined strong and weak binding sites with equilibrium binding constants in the range of 1 (μM)(-1) and 1 (mM)(-1), respectively. The strong binding sites are attributed to sulfhydryl groups as the uptake is blocked by use of sulfhydryl modifying agents and their number is much (two orders of magnitude) smaller than the number of weak binding sites. Biofilms developed by some bacteria (e.g., Rvx. gelatinosus) increase the mercury binding capacity further by a factor of about five. Photosynthetic bacteria in the light act as a sponge of Hg(II) and can be potentially used for biomonitoring and bioremediation of mercury-contaminated aqueous cultures.

  9. 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.

  10. 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.

  11. 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...

  12. 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)

  13. Mercury's magnetosphere: another look

    NASA Astrophysics Data System (ADS)

    Engle, Irene M.

    1997-01-01

    The measurements made of Mercury's magnetic field during the Mercury I flyby and the Mereury III flyby have been incorporated into models of the Hermean magnetosphere-magnetotail system. When the magnetic field data for the first half of the Mereury I flyby and all of the Mercury III flyby were incorporated into a single fit of a scaled version of the Beard ( J. Geophys. Res.84, 2118-2122, 1979) Earth magnetosphere-magnetotail system, a r.m.s. deviation of 9.3 nT for the magnetic field vector was obtained (Bergan and Engle, J. Geophys. Res.86, 1617-1620, 1981). This paper presents results of a study that employs an adaptation of that Beard model but also adopts the assumption that the incident solar wind pressure was different at the times of the two Mercury magnetosphere encounters. Resulting different stand-off distances and scaling factors for the data of the two respective flybys result directly from that single assumption. The study yields a comparable fit of reduced r.m.s. deviation of 7.1 nT and a strength of the Mercury planetary dipole moment D (before any displacement effects are incorporated) between 154 nT RM3 (Merc 1) and 182 nT RM3 (Merc 3). The corresponding standoff distances are 1.31 RM for the Merc 3 encounter and 1.08 RM for the Merc 1 encounter.

  14. 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.

  15. Biotoxicity of mercury as influenced by mercury(II) speciation.

    PubMed Central

    Farrell, R E; Germida, J J; Huang, P M

    1990-01-01

    Integration of physicochemical procedures for studying mercury(II) speciation with microbiological procedures for studying the effects of mercury on bacterial growth allows evaluation of ionic factors (e.g., pH and ligand species and concentration) which affect biotoxicity. A Pseudomonas fluorescens strain capable of methylating inorganic Hg(II) was isolated from sediment samples collected at Buffalo Pound Lake in Saskatchewan, Canada. The effect of pH and ligand species on the toxic response (i.e., 50% inhibitory concentration [IC50]) of the P. fluorescens isolated to mercury were determined and related to the aqueous speciation of Hg(II). It was determined that the toxicities of different mercury salts were influenced by the nature of the co-ion. At a given pH level, mercuric acetate and mercuric nitrate yielded essentially the same IC50s; mercuric chloride, on the other hand, always produced lower IC50s. For each Hg salt, toxicity was greatest at pH 6.0 and decreased significantly (P = 0.05) at pH 7.0. Increasing the pH to 8.0 had no effect on the toxicity of mercuric acetate or mercuric nitrate but significantly (P = 0.05) reduced the toxicity of mercuric chloride. The aqueous speciation of Hg(II) in the synthetic growth medium M-IIY (a minimal salts medium amended to contain 0.1% yeast extract and 0.1% glycerol) was calculated by using the computer program GEOCHEM-PC with a modified data base. Results of the speciation calculations indicated that complexes of Hg(II) with histidine [Hg(H-HIS)HIS+ and Hg(H-HIS)2(2+)], chloride (HgCl+, HgCl2(0), HgClOH0, and HgCl3-), phosphate (HgHPO4(0), ammonia (HgNH3(2+), glycine [Hg(GLY)+], alanine [Hg(ALA)+], and hydroxyl ion (HgOH+) were the Hg species primarily responsible for toxicity in the M-IIY medium. The toxicity of mercuric nitrate at pH 8.0 was unaffected by the addition of citrate, enhanced by the addition of chloride, and reduced by the addition of cysteine. In the chloride-amended system, HgCl+, HgCl2(0), and Hg

  16. 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(+),

  17. MESSENGER Observations of Extreme Space Weather in Mercury's Magnetosphere

    NASA Astrophysics Data System (ADS)

    Slavin, J. A.

    2013-09-01

    Increasing activity on the Sun is allowing MESSENGER to make its first observations of Mercury's magnetosphere under extreme solar wind conditions. At Earth interplanetary shock waves and coronal mass ejections produce severe "space weather" in the form of large geomagnetic storms that affect telecommunications, space systems, and ground-based power grids. In the case of Mercury the primary effect of extreme space weather in on the degree to which this it's weak global magnetic field can shield the planet from the solar wind. Direct impact of the solar wind on the surface of airless bodies like Mercury results in space weathering of the regolith and the sputtering of atomic species like sodium and calcium to high altitudes where they contribute to a tenuous, but highly dynamic exosphere. MESSENGER observations indicate that during extreme interplanetary conditions the solar wind plasma gains access to the surface of Mercury through three main regions: 1. The magnetospheric cusps, which fill with energized solar wind and planetary ions; 2. The subsolar magnetopause, which is compressed and eroded by reconnection to very low altitudes where the natural gyro-motion of solar wind protons may result in their impact on the surface; 3. The magnetotail where hot plasma sheet ions rapidly convect sunward to impact the surface on the nightside of Mercury. The possible implications of these new MESSENGER observations for our ability to predict space weather at Earth and other planets will be described.

  18. 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.

  19. Mercury's Sodium Exosphere: Observations During the MESSENGER Orbital Phase

    NASA Astrophysics Data System (ADS)

    Killen, R. M.; Cassidy, T.; Vervack, R. J.; Burger, M. H.; Merkel, A. W.; Sarantos, M.; Sprague, A. L.; McClintock, W. E.; Benna, M.; Solomon, S. C.

    2012-12-01

    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+, O+, and Na+.

  20. Enhanced mercury oxidation

    SciTech Connect

    Gretta, W.J.; Wu, S.; Kikkawa, H.

    2009-06-15

    A new catalyst offers a new way to enhance mercury control from bituminous coal-fired power plants. Hitachi has developed an SCR catalyst which satisfies high Hg{sup 0} oxidation and low SO{sub 2} oxidation requirements under high temperatures (716 to 770 F). This triple action catalysts, TRAC can significantly enhance mercury oxidation and reduce or eliminate the need for additional mercury control measures such as activated carbon injection. After laboratory testing, pilot-scale tests confirmed an activity of 1.4-1.7 times higher than that of conventional SCR catalyst. The new catalyst has been successfully applied in a commercial PRB-fired boiler without the need for halogens to be added to the fuel feed or flue gas. 2 figs.

  1. 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.

  2. 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.

  3. 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.

  4. Mercury poisoning: a diagnostic challenge.

    PubMed

    Tezer, Hasan; Kaya, Aysenur; Kalkan, Gokhan; Erkocoglu, Mustafa; Ozturk, Kubra; Buyuktasli, Muge

    2012-11-01

    Clinical features of mercury poisoning are nonspecific, and a detailed history is very valuable. The silvery, shiny appearance of mercury makes it very exciting and attractive for children. The overall half-life of elemental mercury in the body averages approximately 2 months. Chelation therapy with dimercaptosuccinic acid is the treatment of choice if the urine or blood level of mercury is high or the symptoms are profound. Here, we describe a 14-year-old boy with fever, respiratory distress, and body rash. Investigation leading to a diagnosis of mercury poisoning was made only after his mother presented with the similar symptoms a few days later.

  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

    2008-07-04

    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.

  6. Gold nanoparticle-aluminum oxide adsorbent for efficient removal of mercury species from natural waters.

    PubMed

    Lo, Sut-I; Chen, Po-Cheng; Huang, Chih-Ching; Chang, Huan-Tsung

    2012-03-06

    We report a new adsorbent for removal of mercury species. By mixing Au nanoparticles (NPs) 13 nm in diameter with aluminum oxide (Al(2)O(3)) particles 50-200 μm in diameter, Au NP-Al(2)O(3) adsorbents are easily prepared. Three adsorbents, Al(2)O(3), Au NPs, and Au NP-Al(2)O(3), were tested for removal of mercury species [Hg(2+), methylmercury (MeHg(+)), ethylmercury (EtHg(+)), and phenylmercury (PhHg(+))]. The Au NP adsorbent has a higher binding affinity (dissociation constant; K(d) = 0.3 nM) for Hg(2+) ions than the Al(2)O(3) adsorbent (K(d) = 52.9 nM). The Au NP-Al(2)O(3) adsorbent has a higher affinity for mercury species and other tested metal ions than the Al(2)O(3) and Au NP adsorbents. The Au NP-Al(2)O(3) adsorbent provides a synergic effect and, thus, is effective for removal of most tested metal ions and organic mercury species. After preconcentration of mercury ions by an Au NP-Al(2)O(3) adsorbent, analysis of mercury ions down to the subppq level in aqueous solution was performed by inductively coupled plasma mass spectrometry (ICP-MS). The Au NP-Al(2)O(3) adsorbent allows effective removal of mercury species spiked in lake water, groundwater, and seawater with efficiencies greater than 97%. We also used Al(2)O(3) and Au NP-Al(2)O(3) adsorbents sequentially for selectively removing Hg(2+) and MeHg(+) ions from water. The low-cost, effective, and stable Au NP-Al(2)O(3) adsorbent shows great potential for economical removal of various mercury species.

  7. 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

  8. Retention of mercury by salmon

    USGS Publications Warehouse

    Amend, Donald F.

    1970-01-01

    Consuming fish that have been exposed repeatedly to mercury derivatives is a potential public health hazard because fish can accumulate and retain mercury in their tissues (Rucker, 1968). Concern has been expressed in the United States because mercurials have been used extensively in industry and as prophylactic and therapeutic agents in fish hatcheries. Rucker and Amend (1969) showed that yearling rainbow trout (Salmo gairdneri) and chinook salmon (Oncorhynchus tshawytscha) exposed to mercurials accumulated excessive amounts of mercury in many tissues. Further, Rucker and Amend (1969) concluded that wild fish that ate mercury-contaminated fish also could contain high mercury levels. Although mercury was eliminated from most tissues within several months, substantial levels remained in the kidney for more than 33 weeks after the last exposure. Since high levels of mercury can be retained in the kidney for an undetermined time, it is possible that returning adult salmon exposed to mercurials as juveniles could constitute a potential hazard to public health. The purpose of this study was to determine whether such fish contained high residual levels of mercury.

  9. 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.)

  10. 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.

  11. Microwave-enhanced cold vapor generation for speciation analysis of mercury by atomic fluorescence spectrometry.

    PubMed

    Wu, Li; Long, Zhou; Liu, Liwei; Zhou, Qin; Lee, Yong-Ill; Zheng, Chengbin

    2012-05-30

    A new and simple cold vapor generation technique utilizing microwave irradiation coupled with atomic fluorescence spectrometry is developed for the speciation analysis of mercury in biological and geological samples. In the presence of formic acid, inorganic mercury (Hg(2+)) and total mercury (both Hg(2+) and methylmercury (MeHg)) can be converted to mercury cold vapor (Hg(0)) by microwave irradiation without and with H(2)O(2), respectively. The cold vapor was subsequently released from the liquid phase and rapidly transported to an atomic fluorescence spectrometer for the mercury detection. Optimum conditions for vapor generation as well as interferences from concomitant ions were carefully investigated. The conventionally required evaporation of the remnants of acid or oxidants was avoided because no significant interferences from these substances were observed, and thus analyte loss and potential contamination were minimized. A limit of detection of 0.005 ng mL(-1) for total mercury or inorganic mercury was obtained. A precision of less than 3% (RSD) at 2 μg L(-1) of mercury species was typical. The accuracy of the method was validated by determination of mercury in geological and biological certified reference materials. The speciation analysis of Hg(2+) and MeHg was achieved by controlling the conditions of microwave-enhanced cold vapor generation and validated via determination of Certified Reference Materials DORM-2, DORM-3 and a real river water sample.

  12. 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.

  13. 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.

  14. Mercury's Plasma Mantle - a survey of MESSENGER observations

    NASA Astrophysics Data System (ADS)

    Jasinski, Jamie Matthew; Slavin, James A.; Raines, Jim; DiBraccio, Gina

    2016-10-01

    The plasma mantle is a region of solar wind plasma entry into the nightside high-latitude magnetosphere. We present a survey of plasma mantles identified in particle and magnetic field measurements from four years of MESSENGER spacecraft observations of Mercury's magnetosphere. The two common observational signatures of this region are ion energy latitude dispersions as well as diamagnetic depressions. From these observations we estimate the contribution of plasma from the solar wind via the mantle and infer magnitude and variability in the cross-magnetospheric electric fields present at Mercury's dynamic magnetosphere.

  15. 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...

  16. 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...

  17. 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…

  18. 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...

  19. Mercury's core evolution

    NASA Astrophysics Data System (ADS)

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

    2016-10-01

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

  20. 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.

  1. 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

  2. [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

  3. 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, ...

  4. 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.

  5. Mercury Phase II Study - Mercury Behavior in Salt Processing Flowsheet

    SciTech Connect

    Jain, V.; Shah, H.; Bannochie, C. J.; Wilmarth, W. R.

    2016-07-25

    Mercury (Hg) in the Savannah River Site Liquid Waste System (LWS) originated from decades of canyon processing where it was used as a catalyst for dissolving the aluminum cladding of reactor fuel. Approximately 60 metric tons of mercury is currently present throughout the LWS. Mercury has long been a consideration in the LWS, from both hazard and processing perspectives. In February 2015, a Mercury Program Team was established at the request of the Department of Energy to develop a comprehensive action plan for long-term management and removal of mercury. Evaluation was focused in two Phases. Phase I activities assessed the Liquid Waste inventory and chemical processing behavior using a system-by-system review methodology, and determined the speciation of the different mercury forms (Hg+, Hg++, elemental Hg, organomercury, and soluble versus insoluble mercury) within the LWS. Phase II activities are building on the Phase I activities, and results of the LWS flowsheet evaluations will be summarized in three reports: Mercury Behavior in the Salt Processing Flowsheet (i.e. this report); Mercury Behavior in the Defense Waste Processing Facility (DWPF) Flowsheet; and Mercury behavior in the Tank Farm Flowsheet (Evaporator Operations). The evaluation of the mercury behavior in the salt processing flowsheet indicates, inter alia, the following: (1) In the assembled Salt Batches 7, 8 and 9 in Tank 21, the total mercury is mostly soluble with methylmercury (MHg) contributing over 50% of the total mercury. Based on the analyses of samples from 2H Evaporator feed and drop tanks (Tanks 38/43), the source of MHg in Salt Batches 7, 8 and 9 can be attributed to the 2H evaporator concentrate used in assembling the salt batches. The 2H Evaporator is used to evaporate DWPF recycle water. (2) Comparison of data between Tank 21/49, Salt Solution Feed Tank (SSFT), Decontaminated Salt Solution Hold Tank (DSSHT), and Tank 50 samples suggests that the total mercury as well as speciated

  6. 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.

  7. Evolution of Mercury's Obliquity

    NASA Astrophysics Data System (ADS)

    Yseboodt, M.; Margot, J. L.

    2005-05-01

    Mercury has a near-zero obliquity, i.e. its spin axis is nearly perpendicular to its orbital plane. In order to constrain the size of the planet's core with the framework suggested by Peale (1976), the obliquity must be known precisely. Rambaux and Bois (2004) have suggested that Mercury's obliquity varies on thousand-year timescales due to planetary perturbations, potentially ruining the feasibility of Peale's experiment. We use a Hamiltonian approach (free of energy dissipation) to study the spin-orbit evolution of Mercury subject to planetary perturbations. We can reproduce an obliquity evolution similar to that of Rambaux and Bois (2004) if we introduce the planetary perturbations abruptly, i.e. by a step function. But if we introduce the planetary effects smoothly starting from an equilibrium position corresponding to the Cassini state (where the spin axis, the normal to the invariable plane and the normal to the orbital plane are aligned), the thousand-year oscillations in the obliquity do not appear. We find an equilibrium value for the obliquity of ˜1.6 arcmin for (B-A)/C = 1.2 10-4 and (C-A)/C = 2.4 10-4, which are combinations of the moments of inertia corresponding to the Mariner 10 gravity data. Our results indicate that planetary perturbations do not force short-period oscillations in Mercury's obliquity, even though such oscillations may appear in numerical integrations involving artificial departures from the Cassini state or the sudden onset of perturbations. Peale (2004) has shown that the periods of damping of the free motions (free precession or free libration) are short compared to the age of the solar system, such that oscillations in obliquity are expected to decay. In the absence of excitation processes, Mercury's obliquity will remain constant, suggesting that one of the important conditions for the success of Peale's experiment is realized.

  8. Fluorescent optical fibre chemosensor for the detection of mercury

    NASA Astrophysics Data System (ADS)

    Nguyen, T. Hien; Wren, Stephen P.; Sun, Tong; Grattan, Kenneth T. V.

    2016-11-01

    This work aims to develop a stable, compact and portable fibre optic sensing system which is capable of real time detection of the mercury ion (II), Hg2+. A novel fluorescent polymeric material for Hg2+ detection, based on a coumarin derivative (acting as the fluorophore) and an azathia crown ether moiety (acting as the mercury ion receptor), has been designed and synthesized. The material was covalently attached to the distal end of an optical fibre and exhibited a significant increase in fluorescence intensity in response to Hg2+ in the μM concentration range via a photoinduced electron transfer (PET) mechanism. The sensor has also demonstrated a high selectivity for Hg2+ over other metal ions. A washing protocol was identified for sensor regeneration, allowing the probe to be re-used. The approach developed in this work can also be used for the preparation of sensors for other heavy metals.

  9. 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.

  10. Mercury Exposure and Heart Diseases

    PubMed Central

    Genchi, Giuseppe; Sinicropi, Maria Stefania; Carocci, Alessia; Lauria, Graziantonio; Catalano, Alessia

    2017-01-01

    Environmental contamination has exposed humans to various metal agents, including mercury. It has been determined that mercury is not only harmful to the health of vulnerable populations such as pregnant women and children, but is also toxic to ordinary adults in various ways. For many years, mercury was used in a wide variety of human activities. Nowadays, the exposure to this metal from both natural and artificial sources is significantly increasing. Recent studies suggest that chronic exposure, even to low concentration levels of mercury, can cause cardiovascular, reproductive, and developmental toxicity, neurotoxicity, nephrotoxicity, immunotoxicity, and carcinogenicity. Possible biological effects of mercury, including the relationship between mercury toxicity and diseases of the cardiovascular system, such as hypertension, coronary heart disease, and myocardial infarction, are being studied. As heart rhythm and function are under autonomic nervous system control, it has been hypothesized that the neurotoxic effects of mercury might also impact cardiac autonomic function. Mercury exposure could have a long-lasting effect on cardiac parasympathetic activity and some evidence has shown that mercury exposure might affect heart rate variability, particularly early exposures in children. The mechanism by which mercury produces toxic effects on the cardiovascular system is not fully elucidated, but this mechanism is believed to involve an increase in oxidative stress. The exposure to mercury increases the production of free radicals, potentially because of the role of mercury in the Fenton reaction and a reduction in the activity of antioxidant enzymes, such as glutathione peroxidase. In this review we report an overview on the toxicity of mercury and focus our attention on the toxic effects on the cardiovascular system. PMID:28085104

  11. 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...

  12. Ices on Mercury: Chemistry of volatiles in permanently cold areas of Mercury's north polar region

    NASA Astrophysics Data System (ADS)

    Delitsky, M. L.; Paige, D. A.; Siegler, M. A.; Harju, E. R.; Schriver, D.; Johnson, R. E.; Travnicek, P.

    2017-01-01

    Observations by the MESSENGER spacecraft during its flyby and orbital observations of Mercury in 2008-2015 indicated the presence of cold icy materials hiding in permanently-shadowed craters in Mercury's north polar region. These icy condensed volatiles are thought to be composed of water ice and frozen organics that can persist over long geologic timescales and evolve under the influence of the Mercury space environment. Polar ices never see solar photons because at such high latitudes, sunlight cannot reach over the crater rims. The craters maintain a permanently cold environment for the ices to persist. However, the magnetosphere will supply a beam of ions and electrons that can reach the frozen volatiles and induce ice chemistry. Mercury's magnetic field contains magnetic cusps, areas of focused field lines containing trapped magnetospheric charged particles that will be funneled onto the Mercury surface at very high latitudes. This magnetic highway will act to direct energetic protons, ions and electrons directly onto the polar ices. The radiation processing of the ices could convert them into higher-order organics and dark refractory materials whose spectral characteristics are consistent with low-albedo materials observed by MESSENGER Laser Altimeter (MLA) and RADAR instruments. Galactic cosmic rays (GCR), scattered UV light and solar energetic particles (SEP) also supply energy for ice processing. Cometary impacts will deposit H2O, CH4, CO2 and NH3 raw materials onto Mercury's surface which will migrate to the poles and be converted to more complex Csbnd Hsbnd Nsbnd Osbnd S-containing molecules such as aldehydes, amines, alcohols, cyanates, ketones, hydroxides, carbon oxides and suboxides, organic acids and others. Based on lab experiments in the literature, possible specific compounds produced may be: H2CO, HCOOH, CH3OH, HCO, H2CO3, CH3C(O)CH3, C2O, CxO, C3O2, CxOy, CH3CHO, CH3OCH2CH2OCH3, C2H6, CxHy, NO2, HNO2, HNO3, NH2OH, HNO, N2H2, N3, HCN, Na2O, Na

  13. High-Power Ion Thruster Technology

    NASA Technical Reports Server (NTRS)

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

    1996-01-01

    Performance data are presented for the NASA/Hughes 30-cm-diam 'common' thruster operated over the power range from 600 W to 4.6 kW. At the 4.6-kW power level, the thruster produces 172 mN of thrust at a specific impulse of just under 4000 s. Xenon pressure and temperature measurements are presented for a 6.4-mm-diam hollow cathode operated at emission currents ranging from 5 to 30 A and flow rates of 4 sccm and 8 sccm. Highly reproducible results show that the cathode temperature is a linear function of emission current, ranging from approx. 1000 C to 1150 C over this same current range. Laser-induced fluorescence (LIF) measurements obtained from a 30-cm-diam thruster are presented, suggesting that LIF could be a valuable diagnostic for real-time assessment of accelerator-arid erosion. Calibration results of laminar-thin-film (LTF) erosion badges with bulk molybdenum are presented for 300-eV xenon, krypton, and argon sputtering ions. Facility-pressure effects on the charge-exchange ion current collected by 8-cm-diam and 30-cm-diam thrusters operated on xenon propellant are presented to show that accel current is nearly independent of facility pressure at low pressures, but increases rapidly under high-background-pressure conditions.

  14. Ultraefficient separation and sensing of mercury and methylmercury ions in drinking water by using aminonaphthalimide-functionalized Fe(3)O(4)@SiO(2) core/shell magnetic nanoparticles.

    PubMed

    Park, Minsung; Seo, Sungmin; Lee, In Su; Jung, Jong Hwa

    2010-07-07

    A new fluorogenic based aminonaphthalimide-functionalized Fe(3)O(4)@SiO(2) core/shell magnetic nanoparticles 1 has been prepared, and its abilities to sense and separate metal ions were evaluated by fluorophotometry. The nanoparticles 1 exhibited a high affinity and selectivity for Hg(2+) and CH(3)Hg(+) ions over competing metal ions.

  15. Surface catalyzed mercury transformation reactions

    NASA Astrophysics Data System (ADS)

    Varanasi, Patanjali

    Mercury is a known pollutant that has detrimental effect on human health and environment. The anthropogenic emissions of mercury account for 10 to 30% of worldwide mercury emissions. There is a need to control/reduce anthropogenic mercury emissions. Many mercury control technologies are available but their effectiveness is dependent on the chemical form of mercury, because different chemical forms of mercury have different physical and chemical properties. Mercury leaves the boiler in its elemental form but goes through various transformations in the post-combustion zone. There is a need to understand how fly ash and flue gas composition affect speciation, partitioning, and reactions of mercury under the full range of post-combustion zone conditions. This knowledge can then be used to predict the chemical transformation of mercury (elemental, oxidized or particulate) in the post combustion zone and thus help with the control of mercury emissions from coal-burning power plants. To accomplish this goal present study was conducted using five coal fly ashes. These ashes were characterized and their catalytic activity was compared under selected reaction conditions in a fixed bed reactor. Based on the results from these fly ash experiments, three key components (carbon, iron oxide and calcium oxide) were chosen. These three components were then used to prepare model fly ashes. Silica/alumina was used as a base for these model fly ashes. One, two or three component model fly ashes were then prepared to investigate mercury transformation reactions. The third set of experiments was performed with five different oxidation catalysts to further understand the mercury oxidation process. Based on the results of these three studies the key components were predicted for different fly ash compositions under variety of flue gas conditions. A fixed bed reactor system was used to conduct this study. In all the experiments, the inlet concentration of Hg0(g) was maintained at 35 mug

  16. 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

    2008-07-04

    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.

  17. 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.

  18. 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.

  19. 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.

  20. Advanced ion thruster research

    NASA Technical Reports Server (NTRS)

    Wilbur, P. J.

    1984-01-01

    A simple model describing the discharge chamber performance of high strength, cusped magnetic field ion thrusters is developed. The model is formulated in terms of the energy cost of producing ions in the discharge chamber and the fraction of ions produced in the discharge chamber that are extracted to form the ion beam. The accuracy of the model is verified experimentally in a series of tests wherein the discharge voltage, propellant, grid transparency to neutral atoms, beam diameter and discharge chamber wall temperature are varied. The model is exercised to demonstrate what variations in performance might be expected by varying discharge chamber parameters. The results of a study of xenon and argon orificed hollow cathodes are reported. These results suggest that a hollow cathode model developed from research conducted on mercury cathodes can also be applied to xenon and argon. Primary electron mean free paths observed in argon and xenon cathodes that are larger than those found in mercury cathodes are identified as a cause of performance differences between mercury and inert gas cathodes. Data required as inputs to the inert gas cathode model are presented so it can be used as an aid in cathode design.

  1. A Study of the Complexation of Mercury(II) with Dicysteinyl Tetrapeptides by Electrospray Ionization Mass Spectrometry.

    PubMed

    Mazlo, Johanna; Ngu-Schwemlein, Maria

    2016-01-08

    In this study we evaluated a method for the characterization of complexes, formed in different relative ratios of mercury(II) to dicysteinyl tetrapeptide, by electrospray ionization orbitrap mass spectrometry. This strategy is based on previous successful characterization of mercury-dicysteinyl complexes involving tripeptides by utilizing mass spectrometry among other techniques. Mercury(II) chloride and a dicysteinyl tetrapeptide were incubated in a degassed buffered medium at varying stoichiometric ratios. The complexes formed were subsequently analyzed on an electrospray mass spectrometer consisting of a hybrid linear ion- and orbi- trap mass analyzer. The electrospray ionization mass spectrometry (ESI-MS) spectra were acquired in the positive mode and the observed peaks were then analyzed for distinct mercury isotopic distribution patterns and associated monoisotopic peak. This work demonstrates that an accurate stoichiometry of mercury and peptide in the complexes formed under specified electrospray ionization conditions can be determined by using high resolution ESI MS based on distinct mercury isotopic distribution patterns.

  2. [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

  3. Mercury contamination of aquatic ecosystems

    USGS Publications Warehouse

    Krabbenhoft, David P.; Rickert, David A.

    1995-01-01

    Mercury has been well known as an environmental pollutant for several decades. As early as the 1950's it was established that emissions of mercury to the environment could have serious effects on human health. These early studies demonstrated that fish and other wildlife from various ecosystems commonly attain mercury levels of toxicological concern when directly affected by mercury-containing emissions from human-related activities. Human health concerns arise when fish and wildlife from these ecosystems are consumed by humans. During the past decade, a new trend has emerged with regard to mercury pollution. Investigations initiated in the late 1980's in the northern-tier states of the U.S., Canada, and Nordic countries found that fish, mainly from nutrient-poor lakes and often in very remote areas, commonly have high levels of mercury. More recent fish sampling surveys in other regions of the U.S. have shown widespread mercury contamination in streams, wet-lands, reservoirs, and lakes. To date, 33 states have issued fish consumption advisories because of mercury contamination. These continental to global scale occurrences of mercury contamination cannot be linked to individual emissions of mercury, but instead are due to widespread air pollution. When scientists measure mercury levels in air and surface water, however, the observed levels are extraordinarily low. In fact, scientists have to take extreme precautions to avoid direct contact with water samples or sample containers, to avert sample contamination (Fig 3). Herein lies an apparent discrepancy: Why do fish from some remote areas have elevated mercury concentrations, when contamination levels in the environment are so low?

  4. Mercury-binding proteins from the marine mussel, Mytilus edulis.

    PubMed Central

    Roesijadi, G

    1986-01-01

    The marine mussel, Mytilus edulis, possesses low molecular weight, metal-binding proteins which can be induced by and, in turn, bind mercury when individuals are exposed to low, but elevated concentrations of mercury as HgCl2. Induction of the proteins by exposure of mussels to copper, cadmium, or mercury is associated with enhanced tolerance to mercury toxicity. Mercury-binding proteins isolated from gills of mussels occur as two molecular weight variants of about 20-25 and 10-12 kdaltons, respectively, on Sephadex G-75. These have been designated as HgBP20 and HgBP10 following the nomenclature used for cadmium-binding proteins. HgBP20 represents the primary mercury-binding species. These exist as dimers which can be dissociated into subunits by treatment with 1% 2-mercaptoethanol. Further purification of HgBP20 by DEAE-cellulose ion-exchange chromatography resulted in the resolution of three major mercury-binding protein peaks; analysis of two of these showed that both had similar amino acid compositions with 26% half-cystine, 16% glycine, and very low levels of the aromatic amino acids phenylalanine and tyrosine (0.3-0.5%), histidine (0.4%), methionine (about 0.5%), and leucine (about 1%). These are similar to the compositions of proteins reported as mussel thioneins by others. Separation of HgBP20 by anion-exchange high-performance liquid chromatography resulted in the resolution of six peaks, indicating a more complex situation than was evident from DEAE-cellulose separations. Although not completely purified, these also contain cysteine- and glycine-rich proteins. PMID:3709464

  5. 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.

  6. Status of the extended life test of the Deep Space 1 flight spare ion engine after 30,352 hours of operation

    NASA Technical Reports Server (NTRS)

    Sengupta, Anita; Brophy, John R.; Goodfellow, Keith D.

    2003-01-01

    The extended life test (ELT) of the Deep Space 1 (DS1) spare flight ion thruster (FT2) was voluntarily terminated June 26th 2003. The test was started in Cotober of 1998, just prior to the launch of the DS1 spacecraft, with the primary purpose of determining the ultimate service life capability of the NASA 30-cm-ion thruster technology.

  7. A 100 Hour Wear Test of the NASA NSTAR Ion Thruster

    NASA Technical Reports Server (NTRS)

    Polk, J. E.; Patterson, M. J.; Brown, J. R.; Rawlin, V. K.; Sovey, J. S.; Myers, R. M.; Blandino, J. J.; Goodfellow, K. D.; Garner, C. E.

    1996-01-01

    In a NASA program to validate 30 cm Xenon ion thruster technology for use in planetary missions a combination of analysis and testing is being used to establish engine reliability. Five long duration tests are planned to identify new failure mechanisms and characterize the parameters which drive known damage accumulation failure modes.

  8. 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.)

  9. Krypton ion thruster performance

    NASA Technical Reports Server (NTRS)

    Patterson, Michael J.; Williams, George J., Jr.

    1992-01-01

    Preliminary data were obtained from a 30 cm ion thruster operating on krypton propellant over the input power range of 0.4-5.5 kW. The data are presented, and compared and contrasted to those obtained with xenon propellant over the same input power envelope. Typical krypton thruster efficiency was 70 percent at a specific impulse of approximately 5000 s, with a maximum demonstrated thrust-to-power ratio of approximately 42 mN/kW at 2090 s specific impulse and 1580 watts input power. Critical thruster performance and component lifetime issues were evaluated. Order-of-magnitude power throttling was demonstrated using a simplified power-throttling strategy.

  10. Krypton Ion Thruster Performance

    NASA Technical Reports Server (NTRS)

    Patterson, Michael J.; Williams, George J.

    1992-01-01

    Preliminary data were obtained from a 30 cm ion thruster operating on krypton propellant over the input power range of 0.4 to 5.5 kW. The data presented are compared and contrasted to the data obtained with xenon propellant over the same input power envelope. Typical krypton thruster efficiency was 70 percent at a specific impulse of approximately 5000 s, with a maximum demonstrated thrust to power ratio of approximately 42 mN/kW at 2090 s specific impulse and 1580 watts input power. Critical thruster performance and component lifetime issues were evaluated. Order of magnitude power throttling was demonstrated using a simplified power-throttling strategy.

  11. Detecting potassium on Mercury

    NASA Technical Reports Server (NTRS)

    Killen, R. M.; Potter, A. E.; Morgan, T. H.

    1991-01-01

    A critical comment on the work of A.L. Sprague et al. (1990) is presented. It is argued that, in attributing an enhanced emission in the potassium D lines on Oct. 14, 1987 in the equatorial region of Mercury to a diffusion source centered on Caloris Basin, Sprague et al. misinterpreted the data. Sprague et al. present a reply, taking issue with the commenters.

  12. Method for mercury refinement

    DOEpatents

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

    1991-04-09

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

  13. Apparatus for mercury refinement

    DOEpatents

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

    1991-01-01

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

  14. Method for mercury refinement

    DOEpatents

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

    1991-01-01

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

  15. Apparatus for mercury refinement

    DOEpatents

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

    1991-07-16

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

  16. Method for scavenging mercury

    DOEpatents

    Chang, Shih-ger; Liu, Shou-heng; Liu, Zhao-rong; Yan, Naiqiang

    2010-07-13

    Disclosed herein is a method for removing mercury from a gas stream comprising contacting the gas stream with a getter composition comprising bromine, bromochloride, sulphur bromide, sulphur dichloride or sulphur monochloride and mixtures thereof. In one preferred embodiment the getter composition is adsorbed onto a sorbent. The sorbent may be selected from the group consisting flyash, limestone, lime, calcium sulphate, calcium sulfite, activated carbon, charcoal, silicate, alumina and mixtures thereof. Preferred is flyash, activated carbon and silica.

  17. Method for scavenging mercury

    DOEpatents

    Chang, Shih-ger; Liu, Shou-heng; Liu, Zhao-rong; Yan, Naiqiang

    2009-01-20

    Disclosed herein is a method for removing mercury from a gas stream comprising contacting the gas stream with a getter composition comprising bromine, bromochloride, sulphur bromide, sulphur dichloride or sulphur monochloride and mixtures thereof. In one preferred embodiment the getter composition is adsorbed onto a sorbent. The sorbent may be selected from the group consisting of flyash, limestone, lime, calcium sulphate, calcium sulfite, activated carbon, charcoal, silicate, alumina and mixtures thereof. Preferred is flyash, activated carbon and silica.

  18. Method for scavenging mercury

    DOEpatents

    Chang, Shih-Ger; Liu, Shou-Heng; Liu, Zhao-Rong; Yan, Naiqiang

    2011-08-30

    Disclosed herein is a method for removing mercury from a gas stream comprising contacting the gas stream with a getter composition comprising bromine, bromochloride, sulphur bromide, sulphur dichloride or sulphur monochloride and mixtures thereof. In one preferred embodiment the getter composition is adsorbed onto a sorbent. The sorbent may be selected from the group consisting of flyash, limestone, lime, calcium sulphate, calcium sulfite, activated carbon, charcoal, silicate, alumina and mixtures thereof. Preferred is flyash, activated carbon and silica.

  19. The planet Mercury (1971)

    NASA Technical Reports Server (NTRS)

    1972-01-01

    The physical properties of the planet Mercury, its surface, and atmosphere are presented for space vehicle design criteria. The mass, dimensions, mean density, and orbital and rotational motions are described. The gravity field, magnetic field, electromagnetic radiation, and charged particles in the planet's orbit are discussed. Atmospheric pressure, temperature, and composition data are given along with the surface composition, soil mechanical properties, and topography, and the surface electromagnetic and temperature properties.

  20. Composition and properties of thallium mercury iodide

    SciTech Connect

    Kennedy, J.H.; Schaupp, C.; Yang, Yuan; Zhang, Zhengming ); Novinson, T.; Hoffard, T. )

    1990-10-01

    Conflicting reports exist in the literature concerning the composition of thallium mercury iodide. Solid state synthesis with HgI{sub 2} and TlI has been reported to give Tl{sub 4}HgI{sub 6} while synthesis from solution has been reported to give Tl{sub 2}HgI{sub 4}. In this report the authors show that the orange compound precipitating from solution is actually a 1:1 mole ratio mixture of Tl{sub 4}HgI{sub 6} and HgI{sub 2}. Pure Tl{sub 4}HgI{sub 6}, which is yellow, can be produced by heating the mixture at 100{degree}C for several days to volatilize HgI{sub 2} or more simply, by adding Tl(I) to a solution containing 2:1 KI:K{sub 2}HgI{sub 4} to provide the additional iodide ions needed for Tl{sub 4}HgI{sub 6}. Tl{sub 4}HgI{sub 6}, unlike Ag{sub 2}HgI{sub 4} and Cu{sub 2}HgI{sub 4}, has no sharp thermochromic changes and has no measurable ionic conductivity. This provides another example of the significant role the metal ion plans in determining structure and properties of metal mercury iodide compounds.

  1. Observations of Metallic Species in Mercury's Exosphere

    NASA Technical Reports Server (NTRS)

    Killen, Rosemary M.; Potter, Andrew E.; Vervack, Ronald J., Jr.; Bradley, E. Todd; McClintock, William E.; Anderson, Carrie M.; Burger, Matthew H.

    2010-01-01

    From observations of the metallic species sodium (Na), potassium (K), and magnesium (Mg) in Mercury's exosphere, we derive implications for source and loss processes. All metallic species observed exhibit a distribution and/or line width characteristic of high to extreme temperature - tens of thousands of degrees K. The temperatures of refractory species, including magnesium and calcium, indicate that the source process for the atoms observed in the tail and near-planet exosphere are consistent with ion sputtering and/or impact vaporization of a molecule with subsequent dissociation into the atomic form. The extended Mg tail is consistent with a surface abundance of 5-8% Mg by number, if 30% of impact-vaporized Mg remains as MgO and half of the impact vapor condenses. Globally, ion sputtering is not a major source of Mg, but locally the sputtered source can be larger than the impact vapor source. We conclude that the Na and K in Mercury's exosphere can be derived from a regolith composition similar to that of Luna 16 soil (or Apollo 17 orange glass), in which the abundance by number is 0.0027 (0.0028) for Na and 0.0006 (0.0045) for K.

  2. Synthesis, characterization, and mercury adsorption properties of hybrid mesoporous aluminosilicate sieve prepared with fly ash

    PubMed Central

    Liu, Minmin; Hou, Li-an; Xi, Beidou; Zhao, Ying; Xia, Xunfeng

    2013-01-01

    A novel hybrid mesoporous aluminosilicate sieve (HMAS) was prepared with fly ash and impregnated with zeolite A precursors. This improved the mercury adsorption of HMAS compared to original MCM-41. The HMAS was characterized by X-ray diffraction (XRD), nitrogen adsorption–desorption, Fourier transform infrared (FTIR) analysis, transmission electron microscopy (TEM) images and 29Si and 27Al magic angle spinning nuclear magnetic resonance (MAS NMR) spectra. These showed that the HMAS structure was still retained after impregnated with zeolite A. But the surface area and pore diameter of HMAS decreased due to pore blockage. Adsorption of mercury from aqueous solution was studied on untreated MCM-41and HMAS. The mercury adsorption rate of HMAS was higher than that of origin MCM-41. The adsorption of mercury was investigated on HMAS regarding the pH of mercury solution, initial mercury concentration, and the reaction temperature. The experimental data fit well to Langmuir and Freundlich isotherm models. The Dublin–Radushkevich isotherm and the characterization show that the mercury adsorption on HMAS involved the ion-exchange mechanisms. In addition, the thermodynamic parameters suggest that the adsorption process was endothermic in nature. The adsorption of mercury on HMAS followed the first order kinetics. PMID:23687400

  3. Synthesis, characterization, and mercury adsorption properties of hybrid mesoporous aluminosilicate sieve prepared with fly ash

    NASA Astrophysics Data System (ADS)

    Liu, Minmin; Hou, Li-an; Xi, Beidou; Zhao, Ying; Xia, Xunfeng

    2013-05-01

    A novel hybrid mesoporous aluminosilicate sieve (HMAS) was prepared with fly ash and impregnated with zeolite A precursors. This improved the mercury adsorption of HMAS compared to original MCM-41. The HMAS was characterized by X-ray diffraction (XRD), nitrogen adsorption-desorption, Fourier transform infrared (FTIR) analysis, transmission electron microscopy (TEM) images and 29Si and 27Al magic angle spinning nuclear magnetic resonance (MAS NMR) spectra. These showed that the HMAS structure was still retained after impregnated with zeolite A. But the surface area and pore diameter of HMAS decreased due to pore blockage. Adsorption of mercury from aqueous solution was studied on untreated MCM-41and HMAS. The mercury adsorption rate of HMAS was higher than that of origin MCM-41. The adsorption of mercury was investigated on HMAS regarding the pH of mercury solution, initial mercury concentration, and the reaction temperature. The experimental data fit well to Langmuir and Freundlich isotherm models. The Dublin-Radushkevich isotherm and the characterization show that the mercury adsorption on HMAS involved the ion-exchange mechanisms. In addition, the thermodynamic parameters suggest that the adsorption process was endothermic in nature. The adsorption of mercury on HMAS followed the first order kinetics.

  4. Influence of limestone characteristics on mercury re-emission in WFGD systems.

    PubMed

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

    2013-03-19

    This work evaluates the influence of the effect of the properties of limestones on their reactivity and the re-emission of mercury under typical wet scrubber conditions. The influence of the composition, particle size, and porosity of limestones on their reactivity and the effect of sorbent concentration, pH, redox potential, and the sulphite and iron content of the slurry on Hg(0) re-emission was assessed. A small particle size, a high porosity and a low magnesium content increased the high reactivity of the limestones. Moreover, it was found that the higher the reactivity of the sample the greater the amount of mercury captured in the scrubber. Although sulphite ions did not cause the re-emission of mercury from the suspensions of the gypsums, the limestones enriched in iron increased Hg(0) re-emission under low oxygen conditions. It was observed that the low pH values of the gypsum suspensions favored the cocapture of mercury because Fe(2+) formation was avoided. The partitioning of the mercury in the byproducts of the scrubber depended on the impurities of the limestones rather than on their particle size. No leaching of mercury from the gypsum samples occurred suggesting that mercury was either tightly bound to the impurities of the limestone or was transformed into insoluble mercury species.

  5. Synthesis, characterization, and mercury adsorption properties of hybrid mesoporous aluminosilicate sieve prepared with fly ash.

    PubMed

    Liu, Minmin; Hou, Li-An; Xi, Beidou; Zhao, Ying; Xia, Xunfeng

    2013-05-15

    A novel hybrid mesoporous aluminosilicate sieve (HMAS) was prepared with fly ash and impregnated with zeolite A precursors. This improved the mercury adsorption of HMAS compared to original MCM-41. The HMAS was characterized by X-ray diffraction (XRD), nitrogen adsorption-desorption, Fourier transform infrared (FTIR) analysis, transmission electron microscopy (TEM) images and (29)Si and (27)Al magic angle spinning nuclear magnetic resonance (MAS NMR) spectra. These showed that the HMAS structure was still retained after impregnated with zeolite A. But the surface area and pore diameter of HMAS decreased due to pore blockage. Adsorption of mercury from aqueous solution was studied on untreated MCM-41and HMAS. The mercury adsorption rate of HMAS was higher than that of origin MCM-41. The adsorption of mercury was investigated on HMAS regarding the pH of mercury solution, initial mercury concentration, and the reaction temperature. The experimental data fit well to Langmuir and Freundlich isotherm models. The Dublin-Radushkevich isotherm and the characterization show that the mercury adsorption on HMAS involved the ion-exchange mechanisms. In addition, the thermodynamic parameters suggest that the adsorption process was endothermic in nature. The adsorption of mercury on HMAS followed the first order kinetics.

  6. Kinetic and Product Studies of the Reaction Between Oxidized Mercury Species and Selected Thiols

    NASA Astrophysics Data System (ADS)

    Si, L.; Ariya, P.

    2008-12-01

    Mercury is a global pollutant with severe potential toxicity. The reduction of oxidized mercury species (Hg(II)) to elemental mercury (Hg(0)) affects the global distribution of mercury and competes for methylation processes of mercury in aquatic environment. This study focused on the reduction of Hg(II) by several selected thiols using a suite of complementary mass spectrometry and cold vapor fluorescence spectroscopy (CVAFS). Previous studies showed that irradiation of benzene solution of six mercury dimercaptides (benzyl, n-propyl, isopropyl, cyclopentyl, t-butyl and phenyl sulfide) at part-per-million level by a mercury arc lamp under a nitrogen atmosphere caused the formation of Hg(0) to occur. The reaction kinetics was studied using CVAFS, and the products of the reaction were analyzed using Matrix-Assisted Laser Desorption Ionization Time-of-Flight Mass spectrometry (MALDI-TOF-MS) and Gas Chromatography-Mass spectrometry (GC-MS). The kinetic data were obtained for 1-butanethiol, and 1-pentanethiol, 1-hexanethiol at environmental relevant conditions. The effects of light, pH, dissolved oxygen and chloride ion on reaction rates were also investigated. We will present our results and discuss their potential environmental implications on mercury cycling.

  7. Preconcentration of total mercury from river water by anion exchange mechanism.

    PubMed

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

    2013-01-01

    A simple and cheap analytical technique was developed for the measurement of total mercury in river water samples using inductively coupled plasma-mass spectrometry (ICP-MS). It is based on the direct complexation of mercury ions using iodide and a cationic surfactant in water for its subsequent solid-phase extraction. Mercury ions are retained on the silica phase as ion pairs in the presence of iodide ions and dodecyltrimethylammonium bromide. Parameters having influential influence on the retention of Hg(II) were investigated: sample flowrate, eluent type, sample volume, iodide and surfactant concentrations. The retained mercury ions are stripped off from silica phase using 10 mL of 8 mol L(-1) HNO3 and quantified by ICP-MS. An enrichment factor of 50 was achieved with a maximum adsorption capacity of 718 μg Hg(II) g(-1). The limit of detection of Hg(II) was 8 pg mL(-1). The developed method was applied for the determination of total mercury in river and tap-water samples.

  8. A Molecular Imaging Approach to Mercury Sensing Based on Hyperpolarized (129)Xe Molecular Clamp Probe.

    PubMed

    Guo, Qianni; Zeng, Qingbin; Jiang, Weiping; Zhang, Xiaoxiao; Luo, Qing; Zhang, Xu; Bouchard, Louis-S; Liu, Maili; Zhou, Xin

    2016-03-14

    Mercury pollution, in the form of mercury ions (Hg(2+)), is a major health and environmental hazard. Commonly used sensors are invasive and limited to point measurements. Fluorescence-based sensors do not provide depth resolution needed to image spatial distributions. Herein we report a novel sensor capable of yielding spatial distributions by MRI using hyperpolarized (129)Xe. A molecular clamp probe was developed consisting of dipyrrolylquinoxaline (DPQ) derivatives and twocryptophane-A cages. The DPQ derivatives act as cation receptors whereas cryptophane-A acts as a suitable host molecule for xenon. When the DPQ moiety interacts with mercury ions, the molecular clamp closes on the ion. Due to overlap of the electron clouds of the two cryptophane-A cages, the shielding effect on the encapsulated Xe becomes important. This leads to an upfield change of the chemical shift of the encapsulated Xe. This sensor exhibits good selectivity and sensitivity toward the mercury ion. This mercury-activated hyperpolarized (129)Xe-based chemosensor is a new concept method for monitoring Hg(2+) ion distributions by MRI.

  9. Synthesis of mercury cuprates

    NASA Astrophysics Data System (ADS)

    Odier, P.; Sin, A.; Toulemonde, P.; Bailly, A.; LeFloch, S.

    2000-08-01

    Mercury cuprates have very interesting potential applications that have not been thoroughly explored until now because of the complexity of their synthesis. This paper presents an overview of recent results concerning their processing. At first, a simple sol-gel technique is described that permits one to easily and intimately mix the precursors. The method uses the gelification of an inorganic solution of the cations by acrylamide polymerization. Mercuration of the precursor at moderate pressures (<2-5 MPa) is then discussed. The control of the total pressure during the synthesis by a simple method is shown, and this enables one to quantify some important parameters of the synthesis and to optimize the superconducting properties. This method has been also used successfully to incorporate mercury into layers of precursors and then to form thick layers of superconducting (Hg, Re)-1223, c-axis oriented. Finally, mercuration at higher pressures (up to 6 GPa) is considered and the case of the double mercury layer Hg-2212 is discussed in connection with the oxygen content of the reactants.

  10. Uncratered Area on Mercury

    NASA Technical Reports Server (NTRS)

    1974-01-01

    A dark, smooth, relatively uncratered area on Mercury was photographed (FDS 226) two hours after Mariner 10 flew by the planet on March 29 from a range of 86,000 kilometers (54,000 miles). Above and to the left of center is a surface similar to the mane material of Earth's moon. It embays and covers rougher, older, heavily cratered topography like that, which can be seen in both upper corners of this picture. The history of heavy cratering seems to be followed by volcanic filling, similar to the process on the Moon. The prominent, sharp crater with a central peak (center) is 30 kilometers (19 miles) across. It is located on the upper left edge of a very bright surface area. The bright crater, to its right is 10 kilometers (6 miles) in diameter. The sun is from the right.

    The Mariner 10 mission, managed by the Jet Propulsion Laboratory for NASA's Office of Space Science, explored Venus in February 1974 on the way to three encounters with Mercury-in March and September 1974 and in March 1975. The spacecraft took more than 7,000 photos of Mercury, Venus, the Earth and the Moon.

    Image Credit: NASA/JPL/Northwestern University

  11. Mercury removal sorbents

    DOEpatents

    Alptekin, Gokhan

    2016-03-29

    Sorbents and methods of using them for removing mercury from flue gases over a wide range of temperatures are disclosed. Sorbent materials of this invention comprise oxy- or hydroxyl-halogen (chlorides and bromides) of manganese, copper and calcium as the active phase for Hg.sup.0 oxidation, and are dispersed on a high surface porous supports. In addition to the powder activated carbons (PACs), this support material can be comprised of commercial ceramic supports such as silica (SiO.sub.2), alumina (Al.sub.2O.sub.3), zeolites and clays. The support material may also comprise of oxides of various metals such as iron, manganese, and calcium. The non-carbon sorbents of the invention can be easily injected into the flue gas and recovered in the Particulate Control Device (PCD) along with the fly ash without altering the properties of the by-product fly ash enabling its use as a cement additive. Sorbent materials of this invention effectively remove both elemental and oxidized forms of mercury from flue gases and can be used at elevated temperatures. The sorbent combines an oxidation catalyst and a sorbent in the same particle to both oxidize the mercury and then immobilize it.

  12. Mercury's Densely Cratered Surface

    NASA Technical Reports Server (NTRS)

    1974-01-01

    Mariner 10 took this picture (FDS 27465) of the densely cratered surface of Mercury when the spacecraft was 18,200 kilometers (8085 miles) from the planet on March 29. The dark line across top of picture is a 'dropout' of a few TV lines of data. At lower left, a portion of a 61 kilometer (38 mile) crater shows a flow front extending across the crater floor and filling more than half of the crater. The smaller, fresh crater at center is about 25 kilometers (15 miles) in diameter. Craters as small as one kilometer (about one-half mile) across are visible in the picture.

    The Mariner 10 mission, managed by the Jet Propulsion Laboratory for NASA's Office of Space Science, explored Venus in February 1974 on the way to three encounters with Mercury-in March and September 1974 and in March 1975. The spacecraft took more than 7,000 photos of Mercury, Venus, the Earth and the Moon.

    Image Credit: NASA/JPL/Northwestern University

  13. Wildfires threaten mercury stocks in northern soils

    USGS Publications Warehouse

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

    2006-01-01

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

  14. Thirty-centimeter-diameter ion milling source

    NASA Technical Reports Server (NTRS)

    Robinson, R. S.

    1978-01-01

    A 30-cm beam diameter ion source has been designed and fabricated for micromachining and sputtering applications. An argon ion current density of 1 mA/cu cm at 500 eV ion energy was selected as a design operating condition. The completed ion source met the design criteria at this operating condition with a uniform and well-collimated beam having an average variation in current density of + or - 5% over the center of 20 cm of the beam. This ion source has a multipole magnetic field that employs permanent magnets between permeable pole pieces. Langmuir probe surveys of the source plasma support the design concepts of a multipole field and a circumferential cathode to enhance plasma uniformity.

  15. Mercury's Magnetic Field

    NASA Astrophysics Data System (ADS)

    Johnson, C. L.

    2014-12-01

    Mercury is the only inner solar system body other than Earth to possess an active core dynamo-driven magnetic field and the only planet with a small, highly dynamic magnetosphere. Measurements made by the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft have provided a wealth of data on Mercury's magnetic field environment. Mercury's weak magnetic field was discovered 40 years ago by the Mariner 10 spacecraft, but its large-scale geometry, strength and origin could not be definitively established. MESSENGER data have shown that the field is dynamo-generated and can be described as an offset axisymmetric dipole field (hereafter OAD): the magnetic equator lies ~0.2 RM (RM = 2440 km) north of the geographic equator and the dipole moment is 2.8 x1019 Am2 (~0.03% that of Earth's). The weak internal field and the high, but variable, solar wind ram pressure drive vigorous magnetospheric dynamics and result in an average distance from the planet center to the sub-solar magnetopause of only 1.42 RM. Magnetospheric models developed with MESSENGER data have allowed re-analysis of the Mariner 10 observations, establishing that there has been no measureable secular variation in the internal field over 40 years. Together with spatial power spectra for the OAD, this provides critical constraints for viable dynamo models. Time-varying magnetopause fields induce secondary core fields, the magnitudes of which confirm the core radius estimated from MESSENGER gravity and Earth-based radar data. After accounting for large-scale magnetospheric fields, residual signatures are dominated by additional external fields that are organized in the local time frame and that vary with magnetospheric activity. Birkeland currents have been identified, which likely close in the planetary interior at depths below the base of the crust. Near-periapsis magnetic field measurements at altitudes greater than 200 km have tantalizing hints of crustal fields, but crustal

  16. Mixed polyelectrolyte coatings on glassy carbon electrodes: Ion-exchange, permselectivity properties and analytical application of poly-l-lysine-poly(sodium 4-styrenesulfonate)-coated mercury film electrodes for the detection of trace metals.

    PubMed

    Monterroso, Sandra C C; Carapuça, Helena M; Duarte, Armando C

    2006-02-28

    The present work describes the preparation, optimization and characterization of mixed polyelectrolyte coatings of poly-l-lysine (PLL) and poly(sodium 4-styrenesulfonate) (PSS) for the modification of thin mercury film electrodes (MFEs). The novel-modified electrodes were applied in the direct analysis of trace metals in estuarine waters by square-wave anodic stripping voltammetry (SWASV). The effects of the coating morphology and thickness and also of the monomeric molar ratio PLL/PSS on the cation-exchange ability of the PLL-PSS polyelectrolyte coatings onto glassy carbon (GC) were evaluated using target cationic species such as dopamine (DA) or lead cation. Further, the semi-permeability of the PLL-PSS-coated electrodes based both on electrostatic interactions and on molecular size leads to an improved anti-fouling ability against several tensioactive species. The analytical usefulness of the PLL-PSS-mixed polyelectrolyte coatings on thin mercury film electrodes is demonstrated via SWASV measurements of trace metals (lead, copper and cadmium at the low nanomolar level; accumulation time of 180s) in estuarine waters containing moderate levels of dissolved organic matter, resulting in a fast and direct methodology requiring no sample pretreatment.

  17. Fundamentals of Mercury Oxidation in Flue Gas

    SciTech Connect

    JoAnn Lighty; Geoffrey Silcox; Constance Senior; Joseph Helble; Balaji Krishnakumar

    2008-07-31

    The objective of this project was to understand the importance of and the contribution of gas-phase and solid-phase coal constituents in the mercury oxidation reactions. The project involved both experimental and modeling efforts. The team was comprised of the University of Utah, Reaction Engineering International, and the University of Connecticut. The objective was to determine the experimental parameters of importance in the homogeneous and heterogeneous oxidation reactions; validate models; and, improve existing models. Parameters studied include HCl, NO{sub x}, and SO{sub 2} concentrations, ash constituents, and temperature. The results suggested that homogeneous mercury oxidation is below 10% which is not consistent with previous data of others and work which was completed early in this research program. Previous data showed oxidation above 10% and up to 100%. However, the previous data are suspect due to apparent oxidation occurring within the sampling system where hypochlorite ion forms in the KCl impinger, which in turn oxidized mercury. Initial tests with entrained iron oxide particles injected into a flame reactor suggest that iron present on fly ash particle surfaces can promote heterogeneous oxidation of mercury in the presence of HCl under entrained flow conditions. Using the data generated above, with homogeneous reactions accounting for less than 10% of the oxidation, comparisons were made to pilot- and full-scale data. The results suggest that heterogeneous reactions, as with the case of iron oxide, and adsorption on solid carbon must be taking place in the full-scale system. Modeling of mercury oxidation using parameters from the literature was conducted to further study the contribution of homogeneous pathways to Hg oxidation in coal combustion systems. Calculations from the literature used rate parameters developed in different studies, in some cases using transition state theory with a range of approaches and basis sets, and in other cases

  18. Adsorption of toxic mercury(II) by an extracellular biopolymer poly(gamma-glutamic acid).

    PubMed

    Inbaraj, B Stephen; Wang, J S; Lu, J F; Siao, F Y; Chen, B H

    2009-01-01

    Adsorption of mercury(II) by an extracellular biopolymer, poly(gamma-glutamic acid) (gamma-PGA), was studied as a function of pH, temperature, agitation time, ionic strength, light and heavy metal ions. An appreciable adsorption occurred at pH>3 and reached a maximum at pH 6. Isotherms were well predicted by Redlich-Peterson model with a dominating Freundlich behavior, implying the heterogeneous nature of mercury(II) adsorption. The adsorption followed an exothermic and spontaneous process with increased orderliness at solid/solution interface. The adsorption was rapid with 90% being attained within 5 min for a 80 mg/L mercury(II) solution, and the kinetic data were precisely described by pseudo second order model. Ionic strength due to added sodium salts reduced the mercury(II) binding with the coordinating ligands following the order: Cl(-) >SO(4)(2-) >NO(3)(-). Both light and heavy metal ions decreased mercury(II) binding by gamma-PGA, with calcium(II) ions showing a more pronounced effect than monovalent sodium and potassium ions, while the interfering heavy metal ions followed the order: Cu(2+) > Cd(2+) > Zn(2+). Distilled water adjusted to pH 2 using hydrochloric acid recovered 98.8% of mercury(II), and gamma-PGA reuse for five cycles of operation showed a loss of only 6.5%. IR spectra of gamma-PGA and Hg(II)-gamma-PGA revealed binding of mercury(II) with carboxylate and amide groups on gamma-PGA.

  19. 49 CFR 173.164 - Mercury (metallic and articles containing mercury).

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 2 2011-10-01 2011-10-01 false Mercury (metallic and articles containing mercury... Than Class 1 and Class 7 § 173.164 Mercury (metallic and articles containing mercury). (a) For transportation by aircraft, mercury must be packaged in packagings which meet the requirements of part 178...

  20. 49 CFR 173.164 - Mercury (metallic and articles containing mercury).

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 2 2010-10-01 2010-10-01 false Mercury (metallic and articles containing mercury... Than Class 1 and Class 7 § 173.164 Mercury (metallic and articles containing mercury). (a) For transportation by aircraft, mercury must be packaged in packagings which meet the requirements of part 178...