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Sample records for metallic current lead

  1. Cryogenic current leads

    Zizek, F.

    1982-01-01

    Theoretical, technical and design questions are examined of cryogenic current leads for SP of magnetic systems. Simplified mathematical models are presented for the current leads. To illustrate modeling, the calculation is made of the real current leads for 500 A and three variants of current leads for 1500 A for the enterprise ''Shkoda.''

  2. Transient current in a quantum dot asymmetrically coupled to metallic leads

    Goker, A; Friedman, B A; Nordlander, P

    2007-01-01

    The time-dependent non-crossing approximation is used to study the transient current in a single-electron transistor attached asymmetrically to two leads following a sudden change in the energy of the dot level. We show that for asymmetric coupling, sharp features in the density of states of the leads can induce oscillations in the current through the dot. These oscillations persist to much longer timescales than the timescale for charge fluctuations. The amplitude of the oscillations increases as the temperature or source-drain bias across the dot is reduced and saturates for values below the Kondo temperature. We discuss the microscopic origin of these oscillations and comment on the possibility for their experimental detection

  3. Lead toxicity: current concerns.

    Goyer, R A

    1993-01-01

    Over the 20-year period since the first issue of Environmental Health Perspectives was published, there has been considerable progress in the understanding of the potential toxicity of exposure to lead. Many of these advances have been reviewed in published symposia, conferences, and review papers in EHP. This brief review identifies major advances as well as a number of current concerns that present opportunities for prevention and intervention strategies. The major scientific advance has be...

  4. Magnesium Diboride Current Leads

    Panek, John

    2010-01-01

    A recently discovered superconductor, magnesium diboride (MgB2), can be used to fabricate conducting leads used in cryogenic applications. Dis covered to be superconducting in 2001, MgB2 has the advantage of remaining superconducting at higher temperatures than the previously used material, NbTi. The purpose of these leads is to provide 2 A of electricity to motors located in a 1.3 K environment. The providing environment is a relatively warm 17 K. Requirements for these leads are to survive temperature fluctuations in the 5 K and 11 K heat sinks, and not conduct excessive heat into the 1.3 K environment. Test data showed that each lead in the assembly could conduct 5 A at 4 K, which, when scaled to 17 K, still provided more than the required 2 A. The lead assembly consists of 12 steelclad MgB2 wires, a tensioned Kevlar support, a thermal heat sink interface at 4 K, and base plates. The wires are soldered to heavy copper leads at the 17 K end, and to thin copper-clad NbTi leads at the 1.3 K end. The leads were designed, fabricated, and tested at the Forschungszentrum Karlsruhe - Institut foer Technische Physik before inclusion in Goddard's XRS (X-Ray Spectrometer) instrument onboard the Astro-E2 spacecraft. A key factor is that MgB2 remains superconducting up to 30 K, which means that it does not introduce joule heating as a resistive wire would. Because the required temperature ranges are 1.3-17 K, this provides a large margin of safety. Previous designs lost superconductivity at around 8 K. The disadvantage to MgB2 is that it is a brittle ceramic, and making thin wires from it is challenging. The solution was to encase the leads in thin steel tubes for strength. Previous designs were so brittle as to risk instrument survival. MgB2 leads can be used in any cryogenic application where small currents need to be conducted at below 30 K. Because previous designs would superconduct only at up to 8 K, this new design would be ideal for the 8-30 K range.

  5. Current leads for superconducting magnets

    Ishibashi, Kenji

    1989-01-01

    Current leads for superconducting magnets have been studied since 1960's. The technology of current leads may seem to have been established both in theory and experiment before the middle of 1970's. Nevertheless, a wide variety of superconducting magnets have been introduced in the last 15 years, and the demands for special current leads have increased in accordance to the variety. A steady advance has been made in the design theory and fabrication of current leads. This paper describes the recent current lead technology regarding the design theory, safety in accidents, and high current capability. (author)

  6. Current lead thermal analysis code 'CURRENT'

    Yamaguchi, Masahito; Tada, Eisuke; Shimamoto, Susumu; Hata, Kenichiro.

    1985-08-01

    Large gas-cooled current lead with the capacity more than 30 kA and 22 kV is required for superconducting toroidal and poloidal coils for fusion application. The current lead is used to carry electrical current from the power supply system at room temperature to the superconducting coil at 4 K. Accordingly, the thermal performance of the current lead is significantly important to determine the heat load requirements of the coil system at 4 K. Japan Atomic Energy Research Institute (JAERI) has being developed the large gas-cooled current leads with the optimum condition in which the heat load is around 1 W per 1 kA at 4 K. In order to design the current lead with the optimum thermal performances, JAERI developed thermal analysis code named as ''CURRENT'' which can theoretically calculate the optimum geometric shape and cooling conditions of the current lead. The basic equations and the instruction manual of the analysis code are described in this report. (author)

  7. Large-capacity current leads

    Ballarino, A.

    2008-01-01

    Feeding superconducting magnets with reliable low-loss devices is a key issue for any cryo-electrical system. Conventional or HTS current leads can be used, and cooling methods, materials, and geometries can be chosen to optimize the thermo-electrical performance of the system. The LHC magnets are powered via more than 3000 current leads transporting altogether about 3 MA of current. With thousands of leads, the LHC lead project represents today the largest project of its kind ever undertaken. Following a review of the LHC lead project, an overview of the choices that can be made for the optimization of large capacity current leads is presented. Examples are given of other leads for large scale magnet systems for which the use of HTS is being envisaged

  8. High temperature superconductor current leads

    Zeimetz, B.; Liu, H.K.; Dou, S.X.

    1996-01-01

    Full text: The use of superconductors in high electrical current applications (magnets, transformers, generators etc.) usually requires cooling with liquid Helium, which is very expensive. The superconductor itself produces no heat, and the design of Helium dewars is very advanced. Therefore most of the heat loss, i.e. Helium consumption, comes from the current lead which connects the superconductor with its power source at room temperature. The current lead usually consists of a pair of thick copper wires. The discovery of the High Temperature Superconductors makes it possible to replace a part of the copper with superconducting material. This drastically reduces the heat losses because a) the superconductor generates no resistive heat and b) it is a very poor thermal conductor compared with the copper. In this work silver-sheathed superconducting tapes are used as current lead components. The work comprises both the production of the tapes and the overall design of the leads, in order to a) maximize the current capacity ('critical current') of the superconductor, b) minimize the thermal conductivity of the silver clad, and c) optimize the cooling conditions

  9. Current Leads, Links and Buses

    Ballarino, A

    2014-01-01

    Electrical transfer from a room temperature power source to a superconducting system is done via conventional or superconducting current leads and superconducting buses or links. The principles of optimization of these devices are presented, with emphasis on the cryogenic, electrical, and superconductor related aspects that drive choices for a system.

  10. Current Leads, Links and Buses

    Ballarino, A [European Organization for Nuclear Research, Geneva (Switzerland)

    2014-07-01

    Electrical transfer from a room temperature power source to a superconducting system is done via conventional or superconducting current leads and superconducting buses or links. The principles of optimization of these devices are presented, with emphasis on the cryogenic, electrical, and superconductor related aspects that drive choices for a system.

  11. High-temperature superconducting current leads

    Hull, J. R.

    1992-07-01

    The use of high-temperature superconductors (HTSs) for current leads to deliver power to devices at liquid helium temperature is near commercial realization. The use of HTSs in this application has the potential to reduce refrigeration requirements and helium boiloff to values significantly lower than the theoretical best achievable with conventional leads. Considerable advantage is achieved by operating these leads with an intermediate temperature heat sink. The HTS part of the lead can be made from pressed and sintered powder. Powder-in-tube fabrication is also possible, however, the normal metal part of the lead acts as a thermal short and cannot provide much stabilization without increasing the refrigeration required. Lead stability favors designs with low current density. Such leads can be manufactured with today's technology, and lower refrigeration results from the same allowable burnout time. Higher current densities result in lower boiloff for the same lead length, but bumout times can be very short. In comparing experiment to theory, the density of helium vapor needs to be accounted for in calculating the expected boiloff. For very low-loss leads, two-dimensional heat transfer and the state of the dewar near the leads may play a dominant role in lead performance.

  12. Design chart of optimum current leads

    Ishibashi, K.; Katase, A.; Maechata, K.

    1986-01-01

    The heat flow through current leads is one of major heat losses in a superconducting magnet system. To reduce the heat flow, current leads have been optimized in a complex way by varying such quantities as conductor length, cross-sectional area, heat transfer coefficient and cooling perimeter. Therefore, this study is made to simplify the design procedure, and to explain the general characteristics of the current leads. A new combined parameter which takes turbulent flow into account is introduced in the present work to enable us to draw a useful design chart. This chart gives, to a wide variety of current leads, detailed information about the optimum design-viz. geometric dimensions, heat flow into liquid helium, and pressure drop of the cooling gas. Change of the cross-sectional area along the conductor may improve the current lead performance. The effects of this area change are examined in detail

  13. Spin currents in metallic nanostructures

    Czeschka, Franz Dominik

    2011-09-05

    A pure spin current, i.e., a flow of angular momentum without accompanying net charge current, is a key ingredient in the field of spintronics. In this thesis, we experimentally investigated two different concepts for pure spin current sources suggested by theory. The first is based on a time-dependent magnetization precession which ''pumps'' a pure spin current into an adjacent non-magnetic conductor. Our experiments quantitatively corroborated important predictions expected theoretically for this approach, including the dependence of the spin current on the sample geometry and the microwave power. Even more important, we could show for the first time that the spin pumping concept is viable in a large variety of ferromagnetic materials and that it only depends on the magnetization damping. Therefore, our experiments established spin pumping as generic phenomenon and demonstrated that it is a powerful way to generate pure spin currents. The second theoretical concept is based on the conversion of charge currents into spin currents in non-magnetic nanostructures via the spin Hall effect. We experimentally investigated this approach in H-shaped, metallic nanodevices, and found that the predictions are linked to requirements not realizable with the present experimental techniques, neither in sample fabrication nor in measurement technique. Indeed, our experimental data could be consistently understood by a spin-independent transport model describing the transition from diffusive to ballistic transport. In addition, the implementation of advanced fabrication and measurement techniques allowed to discover a new non-local phenomenon, the non-local anisotropic magnetoresistance. Finally, we also studied spin-polarized supercurrents carried by spin-triplet Cooper pairs. We found that low resistance interfaces are a key requirement for further experiments in this direction. (orig.)

  14. Current practice in transvenous lead extraction

    Bongiorni, Maria Grazia; Blomström-Lundqvist, Carina; Kennergren, Charles

    2012-01-01

    AIM: Current practice with regard to transvenous lead extraction among European implanting centres was analysed by this survey. METHODS AND RESULTS: Among all contacted centres, 164, from 30 countries, declared that they perform transvenous lead extraction and answered 58 questions...... with a compliance rate of 99.9%. Data from the survey show that there seems to be an overall increasing experience of managing various techniques of lead extraction and a widespread involvement of cardiac centres in this treatment. Results and complication rates seem comparable with those of main international...... registries. CONCLUSION: This survey gives an interesting snapshot of lead extraction in Europe today and gives some clues for future research and prospective European registries....

  15. Versatile high current metal ion implantation facility

    Brown, I.G.; Dickinson, M.R.; Galvin, J.E.; Godechot, X.; MacGill, R.A.

    1992-01-01

    A metal ion implantation facility has been developed with which high current beams of practically all the solid metals of the periodic table can be produced. A multicathode, broad-beam, metal vapor vacuum arc ion source is used to produce repetitively pulsed metal ion beams at an extraction voltage of up to 100 kV, corresponding to an ion energy of up to several hundred kiloelectronvolts because of the ion charge state multiplicity, and with a beam current of up to several amps peak pulsed and several tens of milliamps time averaged delivered onto a downstream target. Implantation is done in a broad-beam mode, with a direct line of sight from ion source to target. Here we summarize some of the features of the ion source and the implantation facility that has been built up around it. (orig)

  16. Design and application consideration of high temperature superconducting current leads

    Wu, J.L.

    1994-01-01

    As a potential major source of heat leak and the resultant cryogen boiloff, cryogenic current leads can significantly affect the refrigeration power requirement of cryogenic power equipment. Reduction of the heat leak associated with current leads can therefore contribute to the development and application of this equipment. Recent studies and tests have demonstrated that, due to their superconducting and low thermal conductivity properties, ceramic high temperature superconductor (HTSC) can be employed in current leads to significantly reduce the heat leak. However, realization of this benefit requires special design considerations pertaining to the properties and the fabrication technology of the relatively new ceramic superconductor materials. Since processing and fabrication technology are continuously being developed in the laboratories, data on material properties unrelated to critical states are quite limited. Therefore, design analysis and experiments have to be conducted in tandem to achieve a successful development. Due to the rather unique combination of superconducting and thermal conductivities which are orders of magnitude lower than copper, ceramic superconductors allow expansion of the operating scenarios of current leads. In addition to the conventional vapor-cooled lead type application, low heat leak conduction-cooled type current leads may be practical and are being developed. Furthermore, a current lead with an intermediate heat leak intercept has been successfully demonstrated in a multiple current lead assembly employing HTSC. These design and application considerations of high temperature superconducting current leads are addressed here

  17. Equilibrium of current driven rotating liquid metal

    Velikhov, E.P.; Ivanov, A.A.; Zakharov, S.V.; Zakharov, V.S.; Livadny, A.O.; Serebrennikov, K.S.

    2006-01-01

    In view of great importance of magneto-rotational instability (MRI) as a fundamental mechanism for angular momentum transfer in magnetized stellar accretion disks, several research centers are involved in experimental study of MRI under laboratory conditions. The idea of the experiment is to investigate the rotation dynamics of well conducting liquid (liquid metal) between two cylinders in axial magnetic field. In this Letter, an experimental scheme with immovable cylinders and fluid rotation driven by radial current is considered. The analytical solution of a stationary flow was found taking into account the external current. Results of axially symmetric numerical simulations of current driven fluid dynamics in experimental setup geometry are presented. The analytical solution and numerical simulations show that the current driven fluid rotation in axial magnetic field provides the axially homogeneous velocity profile suitable for MRI study in classical statement

  18. A Drinking Water Sensor for Lead and Other Heavy Metals.

    Lin, Wen-Chi; Li, Zhongrui; Burns, Mark A

    2017-09-05

    Leakage of lead and other heavy metals into drinking water is a significant health risk and one that is not easily detected. We have developed simple sensors containing only platinum electrodes for the detection of heavy metal contamination in drinking water. The two-electrode sensor can identify the existence of a variety of heavy metals in drinking water, and the four-electrode sensor can distinguish lead from other heavy metals in solution. No false-positive response is generated when the sensors are placed in simulated and actual tap water contaminated by heavy metals. Lead detection on the four-electrode sensor is not affected by the presence of common ions in tap water. Experimental results suggest the sensors can be embedded in water service lines for long-time use until lead or other heavy metals are detected. With its low cost (∼$0.10/sensor) and the possibility of long-term operation, the sensors are ideal for heavy metal detection of drinking water.

  19. Eddy current technologies for thick metal structures

    Takagi, Toshiyuki; Endo, Hisashi

    2004-01-01

    One of approach of an eddy current testing (ECT) for thick metal structures is introduced. The detection limit of ECT is capable of enlarging thick more than 10 mm, which is ordinarily about 5 mm, by the design of probe. On the basis of results of numerical analysis, the defect detection in thick and shape is evaluated by the distribution of experimental ECT signals. The problems of ECT for thick metal structures and measures, approach to probe design, the specifications of probe, evaluation of experimental results and defect detection are described. By ECT fast simulator, good slit sharp is simulated in the case of 10 and 20 mm of EDM slit length and 5, 10 and 15 mm of slit height. (S.Y.)

  20. 600 a Current Leads with Dry and Compact Warm Terminals

    Andersen, T P; Vullierme, B

    2002-01-01

    For the LHC magnet test benches 26 pairs of conventional helium vapour-cooled 600 A current leads are required. The first pair of 600 A current leads has been designed and built by industry and tested at CERN. The main component of the lead is the heat exchanger, which consists of two concentric copper pipes. Special attention was also given to the design of the warm terminal in order to avoid any condensation and to resist at an electrical test of 2 kV. The paper describes construction details and compares calculated and measured values of the main parameters.

  1. Conceptual design of current lead for large scale high temperature superconducting rotating machine

    Le, T. D.; Kim, J. H.; Park, S. I.; Kim, H. M.

    2014-01-01

    High-temperature superconducting (HTS) rotating machines always require an electric current of from several hundreds to several thousand amperes to be led from outside into cold region of the field coil. Heat losses through the current leads then assume tremendous importance. Consequently, it is necessary to acquire optimal design for the leads which would achieve minimum heat loss during operation of machines for a given electrical current. In this paper, conduction cooled current lead type of 10 MW-Class HTS rotating machine will be chosen, a conceptual design will be discussed and performed relied on the least heat lost estimation between conventional metal lead and partially HTS lead. In addition, steady-state thermal characteristic of each one also is considered and illustrated.

  2. Lead (II) and nickel (II) adsorption kinetics from aqueous metal ...

    This paper discusses the kinetics of lead (II) and Nickel (II) ions adsorption from aqueous solutions using chemically modified and unmodified agricultural adsorbents at 28°C, pH 6.2 and 0.01M NaCl ionic strength. The removal of the two metals were found to increase with increase in chemical modification, the sequence ...

  3. Current leads cooling for the series-connected hybrid magnets

    Bai, Hongyu; Marshall, William S.; Bird, Mark D.; Gavrilin, Andrew V.; Weijers, Hubertus W.

    2014-01-01

    Two Series-Connected Hybrid (SCH) magnets are being developed at the National High Magnetic Field Laboratory. Both SCH magnets combine a set of resistive Florida-Bitter coils with a superconducting outsert coil constructed of the cable-in-conduit conductor (CICC). The outsert coils of the two magnets employ 20 kA BSCCO HTS current leads for the power supply although they have different designs and cooling methods. The copper heat exchangers of the HTS current leads for the HZB SCH are cooled with forced flow helium at a supply temperature of 44 K, while the copper heat exchangers of HTS current leads for NHMFL SCH are cooled with liquid nitrogen at a temperature of 78 K in a self-demand boil-off mode. This paper presents the two cooling methods and their impacts on cryogenic systems. Their efficiencies and costs are compared and presented.

  4. Preparation of lead titanate zirconate from metal citrates

    Bastos, C.M.R.

    1994-01-01

    Lead titanate zirconate (PZT) preparation from its metal constituent citrates have been investigated. Metal citrates were obtained by forced precipitation using a dehydration alcohol mixture. Salt solutions of lead nitrate and octahydrated zirconyl chloride, and titanium tetrachloride were treated separately with citric acid and ammonium hydroxide. Zirconium, titanium and lead oxides resulted from thermal decomposition of corresponding citrates at 500 0 C, 450 0 C and 250 0 C, respectively. Lead titanate (PT) and lead zirconate (P Z) were obtained by calcining at 450 0 C and 500 0 C, respectively, after adequate heating of citrates mechanically mixed in ethyl ether. PZT samples were obtained with different starting stoichiometry. Rhombohedral PZT-1 53/47 sample was prepared from co precipitating zirconyl ammonium and ammonium lead citrates in presence of ethanolic titanium oxide dispersion, and calcinating at 800 0 C. Rhombohedral PZT-q 52/48 sample was obtained from heating at 500 0 C for 2 hours a mixture of metal citrates coprecipitated by dehydration mixture of acetone-ethanol-formic acid (2:1:0,06). Tetragonal PZT-m stoichiometry 53/47 sample were obtained by calcining at after 600 0 C for 2 hours after heating a mechanically mixed metal citrates. PT phase arose at 400 0 C. PZT-m powders obtained in a range of 400 0 C-800 0 C were isostatically pressed, and sintered at 1100 0 C and 1200 0 C in saturated Pb O atmosphere. Rhombohedral sintered PZT was obtained with 7,78 g.cm -3 at 1200 0 C. (author). 123 refs, 53 figs, 32 tabs

  5. Surface passivation of high purity granular metals: zinc, cadmium, lead

    Pirozhenko L. A.

    2017-10-01

    Full Text Available For the high purity metals (99.9999%, such as zinc, cadmium, and lead, which are widely used as initial components in growing semiconductor and scintillation crystals (CdTe, CdZnTe, ZnSe, (Cd, Zn, Pb WO4, (Cd, Zn, Pb MoO4 et al., it is very important to ensure reliable protection of the surface from oxidation and adsorption of impurities from the atmosphere. The specific features of surface passivation of high purity cadmium, lead and zinc are not sufficiently studied and require specific methodologies for further studies. The use of organic solutions in the schemes of chemical passivation of the investigated metals avoids hydrolysis of the obtained protective films. The use of organic solvents with pure cation and anion composition as the washing liquid prevents chemisorption of ions present in the conventionally used distilled water. This keeps the original purity of the granular metals. Novel compositions of etchants and etching scheme providing simultaneous polishing and passivation of high purity granular Zn, Cd and Pb are developed. Chemical passivation allows storing metals in the normal atmospheric conditions for more than half a year for Zn and Cd and up to 30 days for Pb without changing the state of the surface. The use of the glycerol-DMF solution in the processes for obtaining Pb granules provides self-passivation of metal surfaces and eliminates the additional chemical processing while maintaining the quality of corrosion protection.

  6. Current practices in generation of small molecule new leads.

    Goodnow, R A

    2001-01-01

    The current drug discovery processes in many pharmaceutical companies require large and growing collections of high quality lead structures for use in high throughput screening assays. Collections of small molecules with diverse structures and "drug-like" properties have, in the past, been acquired by several means: by archive of previous internal lead optimization efforts, by purchase from compound vendors, and by union of separate collections following company mergers. More recently, many drug discovery companies have established dedicated efforts to effect synthesis by internal and/or outsourcing efforts of targeted compound libraries for new lead generation. Although high throughput/combinatorial chemistry is an important component in the process of new lead generation, the selection of library designs for synthesis and the subsequent design of library members has evolved to a new level of challenge and importance. The potential benefits of screening multiple small molecule compound library designs against multiple biological targets offers substantial opportunity to discover new lead structures. Subsequent optimization of such compounds is often accelerated because of the structure-activity relationship (SAR) information encoded in these lead generation libraries. Lead optimization is often facilitated due to the ready applicability of high-throughput chemistry (HTC) methods for follow-up synthesis. Some of the strategies, trends, and critical issues central to the success of lead generation processes are discussed below. Copyright 2002 Wiley-Liss, Inc.

  7. Testing and evaluation of high temperature superconductor current leads

    Yadav, Anand; Puntambekar, Avinash; Manekar, M.A.

    2009-01-01

    National Institute for Inter-disciplinary Science and Technology (NIIST), Council of Scientific and Industrial Research, Trivandrum (formerly Regional Research Laboratory) has accomplished a DAE-BRNS project with Raja Ramanna Centre for Advanced Technology (RRCAT) as principal collaborator for the development of high temperature superconductor (HTS) current leads. These HTS current leads have self-field critical currents (Ic) ranging from 50 A to 1000 A at liquid nitrogen (LN 2 ) temperature. These HTS are made out of silver sheathed Bismuth Strontium Calcium Copper Oxide (BSCCO-2223), for direct application in superconducting (SC) systems involving transportation of high electric currents from power sources at room temperature to superconducting devices at cryogenic temperatures. RRCAT has participated in this project by testing and evaluation of these HTS current leads and carried out actual load trials. In this paper, we will describe the HTS testing setup, tests performed with their testing procedure and the test results. The testing of these HTS has been done with joint effort of Materials Advanced Accelerator Science and Cryogenics Div. and Superconducting Technology Lab (SCT Lab), Advanced Accelerator Module Development Div., using the test facility available at the SCT Lab. (author)

  8. Cumulative exergy losses associated with the production of lead metal

    Szargut, J [Technical Univ. of Silesia, Gliwice (PL). Inst. of Thermal-Engineering; Morris, D R [New Brunswick Univ., Fredericton, NB (Canada). Dept. of Chemical Engineering

    1990-08-01

    Cumulative exergy losses result from the irreversibility of the links of a technological network leading from raw materials and fuels extracted from nature to the product under consideration. The sum of these losses can be apportioned into partial exergy losses (associated with particular links of the technological network) or into constituent exergy losses (associated with constituent subprocesses of the network). The methods of calculation of the partial and constituent exergy losses are presented, taking into account the useful byproducts substituting the major products of other processes. Analyses of partial and constituent exergy losses are made for the technological network of lead metal production. (author).

  9. Production of high purity granular metals: cadmium, zinc, lead

    Shcherban A. P.

    2017-04-01

    Full Text Available Cadmium, zinc and lead are constituent components of many semiconductor compounds. The obtained high purity distillates and ingots are large-size elements, which is not always convenient to use, and thus require additional grinding, which does not always allow maintaining the purity of the original materials. For the growth of semiconductor and scintillation single crystals it is advisable to use "friable" granular high-purity distillates, which can be processed without the risk of contamination. For example, the European low-background experiment LUCIFER required more than 20 kg of high-purity granulated zinc, which was agreed to be supplied by NSC KIPT. This task was then extended to cadmium and lead. Motivated by these tasks, the authors of this paper propose complex processes of deep refining of cadmium, zinc and lead by vacuum distillation. A device producing granules has been developed. The process of granulation of high-purity metals is explored. The purity of produced granules for cadmium and zinc is >99,9999, and >99,9995% for lead granules. To prevent oxidation of metal granules during exposition to air, chemical methods of surface passivation were used. Organic solvent based on dimethylformamide used as a coolant improves the resistance of granules to atmospheric corrosion during the granulation of high purity Cd, Zn and Pb.

  10. Removal of metals from lead-zinc mine tailings using bioleaching and followed by sulfide precipitation.

    Ye, Maoyou; Li, Guojian; Yan, Pingfang; Ren, Jie; Zheng, Li; Han, Dajian; Sun, Shuiyu; Huang, Shaosong; Zhong, Yujian

    2017-10-01

    Mine tailings often contain significant amounts of metals and sulfide, many traditional operations used to minerals was not as good as those currently available. This study investigated metals removal from lead-zinc mine tailings using bioleaching and followed by sulfide precipitation. Metals were dissolved from the tailings by the bacteria in a bioleaching reactor. During a 10% pulp density bioleaching experiment, approximately 0.82% Pb, 97.38% Zn, and 71.37% Fe were extracted after 50 days. With the pulp density of 10% and 20%, the dissolution of metals followed shrinking core kinetic model. Metals (Pb, Zn, and Fe) present in the pregnant bioleaching leachate. Metals were next precipitated as a sulfide phase using sodium sulfide (Na 2 S). Metal precipitations were selectively and quantitatively produced from the bioleaching leachate by adding Na 2 S. More than 99% of the zinc and 75% of the iron was precipitated using 25 g/L Na 2 S in the bioleaching leachate. The results in the study were to provide useful information for recovering or removing metals from lead-zinc mine tailings. Copyright © 2017 Elsevier Ltd. All rights reserved.

  11. Engineering design of a high-temperature superconductor current lead

    Niemann, R.C.; Cha, Y.S.; Hull, J.R.; Daugherty, M.A.; Buckles, W.E.

    1993-01-01

    As part of the US Department of Energy's Superconductivity Pilot Center Program, Argonne National Laboratory and Superconductivity, Inc., are developing high-temperature superconductor (HTS) current leads suitable for application to superconducting magnetic energy storage systems. The principal objective of the development program is to design, construct, and evaluate the performance of HTS current leads suitable for near-term applications. Supporting objectives are to (1) develop performance criteria; (2) develop a detailed design; (3) analyze performance; (4) gain manufacturing experience in the areas of materials and components procurement, fabrication and assembly, quality assurance, and cost; (5) measure performance of critical components and the overall assembly; (6) identify design uncertainties and develop a program for their study; and (7) develop application-acceptance criteria

  12. Engineering design of a high-temperature superconductor current lead

    Niemann, R. C.; Cha, Y. S.; Hull, J. R.; Daugherty, M. A.; Buckles, W. E.

    As part of the US Department of Energy's Superconductivity Pilot Center Program, Argonne National Laboratory and Superconductivity, Inc., are developing high-temperature superconductor (HTS) current leads suitable for application to superconducting magnetic energy storage systems. The principal objective of the development program is to design, construct, and evaluate the performance of HTS current leads suitable for near-term applications. Supporting objectives are to (1) develop performance criteria; (2) develop a detailed design; (3) analyze performance; (4) gain manufacturing experience in the areas of materials and components procurement, fabrication and assembly, quality assurance, and cost; (5) measure performance of critical components and the overall assembly; (6) identify design uncertainties and develop a program for their study; and (7) develop application-acceptance criteria.

  13. Metallic Biomaterials: Current Challenges and Opportunities

    Karthika Prasad

    2017-07-01

    Full Text Available Metallic biomaterials are engineered systems designed to provide internal support to biological tissues and they are being used largely in joint replacements, dental implants, orthopaedic fixations and stents. Higher biomaterial usage is associated with an increased incidence of implant-related complications due to poor implant integration, inflammation, mechanical instability, necrosis and infections, and associated prolonged patient care, pain and loss of function. In this review, we will briefly explore major representatives of metallic biomaterials along with the key existing and emerging strategies for surface and bulk modification used to improve biointegration, mechanical strength and flexibility of biometals, and discuss their compatibility with the concept of 3D printing.

  14. HTS current lead units prepared by the TFA-MOD processed YBCO coated conductors

    Shiohara, K.; Sakai, S.; Ishii, Y.; Yamada, Y.; Tachikawa, K.; Koizumi, T.; Aoki, Y.; Hasegawa, T.; Tamura, H.; Mito, T.

    2010-01-01

    Two superconducting current lead units have been prepared using ten coated conductors of the Tri-Fluoro-Acetate - Metal Organic Deposition (TFA-MOD) processed Y 1 Ba 2 Cu 3 O 7-δ (YBCO) coated conductors with critical current (I c ) of about 170 A at 77 K in self-field. The coated conductors are 5 mm in width, 190 mm in length and about 120 μm in overall thickness. The 1.5 μm thick superconducting YBCO layer was synthesized through the TFA-MOD process on Hastelloy TM C-276 substrate tape with two buffer oxide layers of Gd 2 Zr 2 O 7 and CeO 2 . The five YBCO coated conductors are attached on a 1 mm thick Glass Fiber Reinforced Plastics (GFRP) board and soldered to Cu caps at the both ends. We prepared two 500 A-class current lead units. The DC transport current of 800 A was stably applied at 77 K without any voltage generation in all coated conductors. The voltage between both Cu caps linearly increased with increasing the applied current, and was about 350 μV at 500 A in both current lead units. According to the estimated values of the heat leakage from 77 K to 4.2 K, the heat leakage for the current lead unit was 46.5 mW. We successfully attained reduction of the heat leakage because of improvement of the transport current performance (I c ), a thinner Ag layer of YBCO coated conductor and usage of the GFRP board for reinforcement instead of a stainless steel board used in the previous study. The DC transport current of 1400 A was stably applied when the two current lead units were joined in parallel. The sum of the heat leakages from 77 K to 4.2 K for the combined the current lead units was 93 mW. In comparison with the conventional Cu current leads by gas-cooling, it could be noted that the heat leakage of the current lead is about one order of magnitude smaller than that of the Cu current lead.

  15. Tuning the architectures of lead deposits on metal substrates by electrodeposition

    Yao Chenzhong; Liu Meng; Zhang Peng; He Xiaohui; Li Gaoren; Zhao Wenxia; Liu Peng; Tong Yexiang

    2008-01-01

    Different morphologies of lead (Pb) deposited on different metal substrates have been prepared via electrochemical deposition in aqueous solution. The morphologies of as-deposited lead were determined by scanning electron microscope (SEM). It is found that the various morphologies of the products are dependent on the electrodeposition conditions, including the deposition current densities, concentration of additives, substrates and deposition time. X-ray diffraction (XRD) and transmission electron microscope (TEM) results reveal that all these lead deposits with different morphologies can be assigned to the space group Fm-3m (2 2 5)

  16. Current at Metal-Organic Interfaces

    Kern, Klaus

    2012-02-01

    Charge transport through atomic and molecular constrictions greatly affects the operation and performance of organic electronic devices. Much of our understanding of the charge injection and extraction processes in these systems relays on our knowledge of the electronic structure at the metal-organic interface. Despite significant experimental and theoretical advances in studying charge transport in nanoscale junctions, a microscopic understanding at the single atom/molecule level is missing. In the present talk I will present our recent results to probe directly the nanocontact between single molecules and a metal electrode using scanning probe microscopy and spectroscopy. The experiments provide unprecedented microscopic details of single molecule and atom junctions and open new avenues to study quantum critical and many body phenomena at the atomic scale. Implications for energy conversion devices and carbon based nanoelectronics will also be discussed.

  17. Conceptual design of cooling anchor for current lead on HTS field coils

    Hyeon, C. J.; Kim, J. H.; Quach, H. L. [Dept. of Electrical Engineering, Jeju National University, Jeju (Korea, Republic of); and others

    2017-06-15

    The role of current lead in high-temperature superconducting synchronous machine (HTSSM) is to function as a power supply by connecting the power supply unit at room temperature with the HTS field coils at cryogenic temperature. Such physical and electrical connection causes conduction and Joule-heating losses, which are major thermal losses of HTSSM rotors. To ensure definite stability and economic feasibility of HTS field coils, quickly and smoothly cooling down the current lead is a key design technology. Therefore, in this paper, we introduce a novel concept of a cooling anchor to enhance the cooling performance of a metal current lead. The technical concept of this technology is the simultaneously chilling and supporting the current lead. First, the structure of the current lead and cooling anchor were conceptually designed for field coils for a 1.5 MW-class HTSSM. Then, the effect of this installation on the thermal characteristics of HTS coils was investigated by 3D finite element analysis.

  18. Survey of current lead use, handling, hygiene, and contaminant controls among New Jersey industries.

    Blando, James D; Lefkowitz, Daniel K; Valiante, David; Gerwel, Barbara; Bresnitz, Eddy

    2007-08-01

    In 2003, a chemical handling and use survey was mailed to New Jersey employers identified as currently using lead in their industrial processes. This survey was used to ascertain characteristics about lead use, handling, and protection of employees during manufacturing operations. The survey included a diverse group of current lead users with a total lead use range from less than 1 pound to more than 63 million pounds of lead per year. The survey allowed for a comprehensive characterization of hazards and protective measures associated with this metal, still commonly used in many products and industrial processes. Forty-five surveys were returned by companies that are listed in the New Jersey Adult Blood Lead Registry, which is part of the New Jersey Adult Blood Lead Epidemiology and Surveillance (ABLES) program. This program records and investigates cases of adults with greater than 25 mu g/dL of lead in their blood; most cases are related to occupational exposures. This survey found that greater than 25% of these surveyed companies with significant potential for lead exposure did not employ commonly used and basic industrial hygiene practices. In addition, the survey found that 24% of these companies had not conducted air sampling within the last 3 years. Air sampling is the primary trigger for compliance with the Occupational Safety and Health Administration (OSHA) general industry lead standard. Only 17% of the companies have ever been cited for a violation of the OSHA lead standard, and only 46% of these companies have ever had an OSHA inspection. State-based surveillance can be a useful tool for OSHA enforcement activities. Elevated blood lead values in adults should be considered as a trigger for required compliance with an OSHA general industry lead standard.

  19. Characterization of high-current, high-temperature superconductor current lead elements

    Niemann, R.C.; Evans, D.J.; Fisher, B.L.; Brockenborough, W.E.; Roberts, P.R.; Rodenbush, A.J.

    1996-08-01

    The refrigeration loads of current leads for superconducting magnets can be significantly reduced by using high-temperature superconductor (HTS) leads. An HTS conductor type that is well suited for this application is a laminated sintered stack of HTS powder-in-tube (PIT) tapes. The superconducting elements are normally characterized by their manufacturer by measuring critical currents at 77 K in self field. Additional characterization, which correlates electrical performance at 77 K and at lower temperatures with applied magnetic fields, provides the current lead designer and conductor element manufacturer with critical information. For HTS conductor elements comprising a laminated and sintered stack of Bi-2223 PIT tapes having an alloyed Ag sheath, this characterization uses variable applied fields and operating temperatures

  20. Current perspectives in fragment-based lead discovery (FBLD)

    Lamoree, Bas; Hubbard, Roderick E.

    2017-01-01

    It is over 20 years since the first fragment-based discovery projects were disclosed. The methods are now mature for most ‘conventional’ targets in drug discovery such as enzymes (kinases and proteases) but there has also been growing success on more challenging targets, such as disruption of protein–protein interactions. The main application is to identify tractable chemical startpoints that non-covalently modulate the activity of a biological molecule. In this essay, we overview current practice in the methods and discuss how they have had an impact in lead discovery – generating a large number of fragment-derived compounds that are in clinical trials and two medicines treating patients. In addition, we discuss some of the more recent applications of the methods in chemical biology – providing chemical tools to investigate biological molecules, mechanisms and systems. PMID:29118093

  1. Removing chromium and lead metals using phytoremediation technique

    Al-Anbari Riyad

    2018-01-01

    Full Text Available Phytoremediation technique uses plants parts to remove, extract, and absorb heavy or toxic matter from soil and water. In the present study, Catharanthusroseus (Periwinkle and Nerium Oleander (Oleander were used for removing Chromium (Cr and Lead (Pb metals. These plant species were seeded in polyethylene pots containing 8kg of soil. Each pot was irrigated with wastewater for four months (May, June, July and August and accumulation of the considered metals was analyzed after every month for leaf, stem and root by using Atomic Absorption Spectrophotometer (AAS. This experimental work was carried out in the laboratories of Water Desalination Researches Unit - Building and Construction Engineering Department and Environmental Research Centre at the University of Technology in Baghdad City, Iraq. The concentration of Cr was found to be increased with time. High Cr concentration, 20.34 mg/kg, was recorded at August in leaf of Periwinkle and 19.61 mg/kg in root of Oleander in case of using 100% wastewater (WW. While, for Pb, the maximum concentration, 22 mg/kg, was recorded in June in leaf of Periwinkle and 19.5 mg/kg in steam of Oleander. Accordingly, Oleander has the maximum removal efficiency.

  2. Metal chelators and neurotoxicity: lead, mercury, and arsenic.

    Bjørklund, Geir; Mutter, Joachim; Aaseth, Jan

    2017-12-01

    This article reviews the clinical use of the metal chelators sodium 2,3-dimercapto-1-propanesulfonate (DMPS), meso-2,3-dimercaptosuccinic acid (DMSA), and calcium disodium edetate (CaEDTA, calcium EDTA) in overexposure and poisonings with salts of lead (Pb), mercury (Hg), and arsenic (As). DMSA has considerably lower toxicity than the classic heavy metal antagonist BAL (2,3-dimercaptopropanol) and is also less toxic than DMPS. Because of its adverse effects, CaEDTA should be replaced by DMSA as the antidote of choice in treating moderate Pb poisoning. Combination therapy with BAL and CaEDTA was previously recommended in cases of severe acute Pb poisoning with encephalopathy. We suggest that BAL in such cases acted as a shuttling Pb transporter from the intra- to the extracellular space. The present paper discusses if a combination of the extracellularly distributed DMSA with the ionophore, Monensin may provide a less toxic combination for Pb mobilization by increasing both the efflux of intracellularly deposited Pb and the urinary Pb excretion. Anyhow, oral therapy with DMSA should be continued with several intermittent courses. DMPS and DMSA are also promising antidotes in Hg poisoning, whereas DMPS seems to be a more efficient agent against As poisoning. However, new insight indicates that a combination of low-dosed BAL plus DMPS could be a preferred antidotal therapy to obtain mobilization of the intracerebral deposits into the circulation for subsequent rapid urinary excretion.

  3. EFFICIENCY OF METAL SCRAP SEPARATION IN EDDY CURRENT SEPARATOR

    Gordan Bedeković

    2008-11-01

    Full Text Available Eddy-current separation is most often method used for the recovery of non-ferrous metals (Al, Cu, Zn, Pb from solid wastes and also for separating non-ferrous metals from each other. The feed material comes to rotary drum and magnetic field by belt conveyer. The changing magnetic field induce eddy currents in conductive (metallic particles. Because interaction between this currents and the magnetic field electrodynamic forces will act on conductive particles. Therefore the trajectories of conductive particles will be different from the trajectories of the non-conductive ones. Separation is a result of the combined actions of several forces (electrodynamic, gravitational and frictional. The paper presents results of aluminium recovery from mixture of metallic particles in eddy current separator. Testing were conducted under field condition. Results shows that is possible achieve recovery of 99 % and concentrate quality of 89 % of aluminium (the paper is published in Croatian.

  4. Current correlations in superconductor - normal metal mesoscopic structures

    Bignon, Guillaume

    2005-01-01

    Thanks to the experimental progress in miniaturization and cryogenics over the last twenty years, it is now possible to build sufficiently small electric circuits where the wave like nature of electron becomes significant. In such electric circuit transport properties like current and noise are modified. It corresponds to the mesoscopic scale. Moreover, connecting a mesoscopic circuit to a superconductor enhances the effects due to interference between electrons since a superconductor is a macroscopic source of coherent electrons pairs: the Cooper pairs. In this thesis, we study current correlations in mesoscopic normal metal - superconductor structures. First, the energy dependence of current noise in a normal metal - superconductor tunnel junction is analysed taking into account weak disorder and interactions. We show that if the normal metal is out of equilibrium, current and noise become independent. Next, we consider the case of a superconductor connected to two normal metals by tunnel junctions. We show that it is possible to change the sign of current crossed correlation by tuning the voltages and that it can be used to probe the size of the Cooper pairs. Lastly, using Usadel's quasi-classic theory, we study the energy dependence of noise in a normal metal - normal metal - superconductor double junction. We show that barrier's transparencies modifies significantly both current and noise. (author) [fr

  5. Mechanisms of current flow in metal-semiconductor ohmic contacts

    Blank, T. V.; Gol'dberg, Yu. A.

    2007-01-01

    Published data on the properties of metal-semiconductor ohmic contacts and mechanisms of current flow in these contacts (thermionic emission, field emission, thermal-field emission, and also current flow through metal shunts) are reviewed. Theoretical dependences of the resistance of an ohmic contact on temperature and the charge-carrier concentration in a semiconductor were compared with experimental data on ohmic contacts to II-VI semiconductors (ZnSe, ZnO), III-V semiconductors (GaN, AlN, InN, GaAs, GaP, InP), Group IV semiconductors (SiC, diamond), and alloys of these semiconductors. In ohmic contacts based on lightly doped semiconductors, the main mechanism of current flow is thermionic emission with the metal-semiconductor potential barrier height equal to 0.1-0.2 eV. In ohmic contacts based on heavily doped semiconductors, the current flow is effected owing to the field emission, while the metal-semiconductor potential barrier height is equal to 0.3-0.5 eV. In alloyed In contacts to GaP and GaN, a mechanism of current flow that is not characteristic of Schottky diodes (current flow through metal shunts formed by deposition of metal atoms onto dislocations or other imperfections in semiconductors) is observed

  6. Recovery of leaded-frame metals from integrated circuit package; Shuseki kairo package kara no lead frame kinzoku no kaishu

    Rokukawa, N.; Sakamoto, H. [National Institute for Resources and Environment, Tsukuba (Japan)

    1997-12-25

    Discussions were given on separation and recovery of leaded-frame metals from an integrated circuit (IC) package. A printed wiring board in an electronic device is mounted with an IC package molded with an IC as a major component, and composed of IC chips, leaded-frame metals (the pin section retains the IC chips safely in a mold, and plays a role of terminal with an external circuit), and mold material (thermally hardened and reinforced resin). Quantity of IC packages discarded as a result of the deterioration due to aging is increasing year after year. IC package test pieces were crushed in a mortar, selected of metals manually, and classified by using a magnet and a sieve. The leaded-frame metals were easily separated from the mold material by crushing, and capable of being recovered by using a magnet. However, since the recovered leaded-frame metals are alloys having different compositions, how each metal component could be separated and refined is an important problem to be solved. For the time being, the metals may be utilized as structural materials for building materials by melting and alloying the leaded-frame metals. 10 refs., 7 tabs.

  7. Factors leading to tracheobronchial self-expandable metallic stent fracture.

    Chung, Fu-Tsai; Lin, Shu-Min; Chen, Hao-Cheng; Chou, Chun-Liang; Yu, Chih-Teng; Liu, Chien-Ying; Wang, Chun-Hua; Lin, Horng-Chyuan; Huang, Chien-Da; Kuo, Han-Pin

    2008-11-01

    This retrospective study was to determine factors that contribute to self-expandable metallic stent fracture in patients with tracheobronchial disease. From 2001 to 2006, 139 patients (age, 62.1 +/- 15.4 years; range, 23-87 years) with benign (n = 62) and malignant (n = 77) tracheobronchial disease received 192 Ultraflex (Boston Scientific, Natick, Mass) self-expandable metallic stents (98 in patients with benign disease and 94 in patients with malignant disease). Seventeen fractured self-expandable metallic stents were found; the incidence was 12.2% (17/139 patients) among patients with tracheobronchial disease. Tortuous airway (odds ratio, 4.06; 95% confidence interval, 1.04-18.34; P = .04) independently predicted self-expandable metallic stent fracture. Most self-expandable metallic stent fractures (64.7%, 11/17) were detected 500 to 1000 days after self-expandable metallic stent implantation. Clinical presentations for patients with fractured self-expandable metallic stents included dyspnea exacerbation (70.6%, 12/17) and cough (23.5%, 4/17). Self-expandable metallic stent fracture is not uncommon in patients with tracheobronchial disease. Tortuous airway is an independent predictor for it. Although management of the fractured self-expandable metallic stent in our study was feasible and safe, self-expandable metallic stents should be restricted to a more select population.

  8. Leading research on super metal. 3. Amorphous and nanostructured metallic materials; Super metal no sendo kenkyu. 3. Kogata buzai

    NONE

    1996-03-01

    Very fine structure control technique for amorphous and nanostructured metallic materials was reviewed to exceed the marginal performance of small metallic member materials. In Japan, high strength alloys and anticorrosion alloys are currently developed as an amorphous structure control technique, and ultra fine powder production and nano-compaction molding are studied for nanostructured materials. Fabrication of amorphous alloy wire materials and metal glass in USA are also introduced. Fabrication of metallic nanocrystals deposited within gas phase in Germany are attracting attention. The strength and abrasion resistance are remarkably enhanced by making nanostructured crystals and dispersing them. It may be most suitable to utilize amorphous and nanostructured metallic materials for earth-friendly materials having anticorrosion, and catalyst and biomaterial affinities, and also for magnetic materials. It is important for controlling micro-structures to clarify the formation mechanism of structures. For their processing techniques, the diversity and possibility are suggested, as to the condensation and solidification of gaseous and liquid phase metals, the molding and processing of very fine solid phase alloys, and the manufacturing members by heat treatment. 324 refs., 109 figs., 21 tabs.

  9. Valuable metals - recovery processes, current trends, and recycling strategies

    Froehlich, Peter; Lorenz, Tom; Martin, Gunther; Brett, Beate; Bertau, Martin [Institut fuer Technische Chemie, TU Bergakademie Freiberg, Leipziger Strasse 29, 09599, Freiberg (Germany)

    2017-03-01

    This Review provides an overview of valuable metals, the supply of which has been classified as critical for Europe. Starting with a description of the current state of the art, novel approaches for their recovery from primary resources are presented as well as recycling processes. The focus lies on developments since 2005. Chemistry strategies which are used in metal recovery are summarized on the basis of the individual types of deposit and mineral. In addition, the economic importance as well as utilization of the metals is outlined. (copyright 2017 Wiley-VCH Verlag GmbH and Co. KGaA, Weinheim)

  10. Passivation of Flexible YBCO Superconducting Current Lead With Amorphous SiO2 Layer

    Johannes, Daniel; Webber, Robert

    2013-01-01

    Adiabatic demagnetization refrigerators (ADR) are operated in space to cool detectors of cosmic radiation to a few 10s of mK. A key element of the ADR is a superconducting magnet operating at about 0.3 K that is continually energized and de-energized in synchronism with a thermal switch, such that a piece of paramagnetic salt is alternately warm in a high magnetic field and cold in zero magnetic field. This causes the salt pill or refrigerant to cool, and it is able to suck heat from an object, e.g., the sensor, to be cooled. Current has to be fed into and out of the magnets from a dissipative power supply at the ambient temperature of the spacecraft. The current leads that link the magnets to the power supply inevitably conduct a significant amount of heat into the colder regions of the supporting cryostat, resulting in the need for larger, heavier, and more powerful supporting refrigerators. The aim of this project was to design and construct high-temperature superconductor (HTS) leads from YBCO (yttrium barium copper oxide) composite conductors to reduce the heat load significantly in the temperature regime below the critical temperature of YBCO. The magnet lead does not have to support current in the event that the YBCO ceases to be superconducting. Cus - tomarily, a normal metal conductor in parallel with the YBCO is a necessary part of the lead structure to allow for this upset condition; however, for this application, the normal metal can be dispensed with. Amorphous silicon dioxide is deposited directly onto the surface of YBCO, which resides on a flexible substrate. The silicon dioxide protects the YBCO from chemically reacting with atmospheric water and carbon dioxide, thus preserving the superconducting properties of the YBCO. The customary protective coating for flexible YBCO conductors is silver or a silver/gold alloy, which conducts heat many orders of magnitude better than SiO2 and so limits the use of such a composite conductor for passing current

  11. Critical reflections on the currently leading definition of sustainable employability.

    Fleuren, Bram Bi; de Grip, Andries; Jansen, Nicole Wh; Kant, Imjert; Zijlstra, Fred Rh

    2016-06-01

    Sustainable employability (SE) is an important topic as it deals with employees' abilities to function adequately at work and in the labor market throughout their working lives. However, until now there has been only one attempt to define SE in the international literature (1). This first definition is a valuable contribution to the field as it rightfully describes SE as a multidimensional concept, recognizes the importance of both employee and work characteristics, and acknowledges the inherently longitudinal nature of SE. Despite these merits, we argue that this definition of SE has some serious omissions that are important in capturing SE comprehensively. Specifically, we argue that the definition could be improved in various ways, namely, it should: (i) clarify which aspects of employment constitute someone's SE; (ii) not counterintuitively treat SE as a characteristic of both the job and the employee simultaneously; (iii) not be based on the insufficiently tested assumption that achieving value in work inherently leads to SE; (iv) be formulated in a way that SE can also apply to unemployed individuals; and (v) adequately specify how the inherently longitudinal dimension of SE should be addressed. We would like to contribute to the discussion by providing guidelines for a new adjusted definition of SE that could facilitate further research on this important concept and its determinants. Introduction SE is a topic of vital importance to individual employees, organizations and society alike. It generally refers to employees' capacities to function in work throughout their working life. As participation in work is important for individuals, organizations, and society as a whole, individuals' ability to function in work is essential. For individuals, work provides meaning, financial security as well as social contacts. Organizations need productive employees to survive. Also from a societal perspective, it is important that as many people as possible participate in

  12. Measuring electric conductivity in liquid metals by eddy current method

    Zhuravlev, S.P.; Ostrovskij, O.I.; Grigoryan, V.A.

    1982-01-01

    Technique permitting to apply the method of vertiginous currents for investigation of electric conductivity of metal melts in the high temperature range is presented. Interferences affecting accuracy of measurements are specified and ways of their removing are pointed out. Scheme of measuring and design of the facility are described. Results of measuring electric resistance of liquid Fe, Co, Ni obtained for the first time by this method are presented. The data obtained agree with the results of measurements conducted by the method of the rotating magnetic field. Difference in absolute values of electric resistance in parallel experiments for each metal does not exceed 4%

  13. Heavy liquid metal technologies at KArlsruhe Lead LAboratory KALLA

    Knebel, J.U.; Mueller, G.; Konys, J.

    2002-01-01

    The objectives of the research cover: lead-bismuth technologies; corrosion mechanism and corrosion protection; thermal hydraulics; kinetics of oxygen control systems. Detailed experimental results are presented

  14. Modelling current transfer to cathodes in metal halide plasmas

    Benilov, M S; Cunha, M D; Naidis, G V

    2005-01-01

    This work is concerned with investigation of the main features of current transfer to cathodes under conditions characteristic of metal halide (MH) lamps. It is found that the presence of MHs in the gas phase results in a small decrease of the cathode surface temperature and of the near-cathode voltage drop in the diffuse mode of current transfer; the range of stability of the diffuse mode expands. Effects caused by a variation of the work function of the cathode surface owing to formation of a monolayer of alkali metal atoms on the surface are studied for particular cases where the monolayer is composed of sodium or caesium. It is found that the formation of the sodium monolayer affects the diffuse mode of current transfer only moderately and in the same direction that the presence of metal atoms in the gas phase affects it. Formation of the caesium monolayer produces a dramatic effect: the cathode surface temperature decreases very strongly, the diffuse-mode current-voltage characteristic becomes N-S-shaped

  15. Plutonium metal exchange program : current status and statistical analysis

    Tandon, L. (Lav); Eglin, J. L. (Judith Lynn); Michalak, S. E. (Sarah E.); Picard, R. R.; Temer, D. J. (Donald J.)

    2004-01-01

    The Rocky Flats Plutonium (Pu) Metal Sample Exchange program was conducted to insure the quality and intercomparability of measurements such as Pu assay, Pu isotopics, and impurity analyses. The Rocky Flats program was discontinued in 1989 after more than 30 years. In 2001, Los Alamos National Laboratory (LANL) reestablished the Pu Metal Exchange program. In addition to the Atomic Weapons Establishment (AWE) at Aldermaston, six Department of Energy (DOE) facilities Argonne East, Argonne West, Livermore, Los Alamos, New Brunswick Laboratory, and Savannah River are currently participating in the program. Plutonium metal samples are prepared and distributed to the sites for destructive measurements to determine elemental concentration, isotopic abundance, and both metallic and nonmetallic impurity levels. The program provides independent verification of analytical measurement capabilies for each participating facility and allows problems in analytical methods to be identified. The current status of the program will be discussed with emphasis on the unique statistical analysis and modeling of the data developed for the program. The discussion includes the definition of the consensus values for each analyte (in the presence and absence of anomalous values and/or censored values), and interesting features of the data and the results.

  16. Leakage current characteristics of the multiple metal alloy nanodot memory

    Lee, Gae Hun; Lee, Jung Min; Yang, Hyung Jun; Song, Yun Heub; Bea, Ji Chel; Tanaka, Tetsu

    2010-01-01

    The leakage current characteristics of a multiple metal alloy nanodot device for a nonvolatile random access memory using FePt materials are investigated. Several annealing conditions are evaluated and optimized to suppress the leakage current and to better the memory characterisctics. This work confirmed that the annealing condition of 700 .deg. C in a high vacuum ambience (under 1 x 10 -5 Pa) simultaneously provided good cell characteristics from a high dot density of over 1 x 10 13 /cm 2 and a low leakage current. In addition, a smaller nanodot diameter was found to give a lower leakage current for the multiple nanodot memory. Finally, for the proposed annealing condition, the quadruple FePt multiple nanodot memory with a 2-nm dot diameter provided good leakage current characteristics, showing a threshold voltage shift of under 5% at an initial retention stage of 1000 sec.

  17. The fabrication and characterization of an ex situ plated lead film electrode prepared with the use of a reversibly deposited mediator metal

    Tyszczuk, Katarzyna

    2011-01-01

    Research highlights: → The lead film electrode prepared with use of the mediator metal was elaborated. → The lead-based sensors were characterized by optical and voltammetric methods. → The adsorptive system of folic acid was employed to investigate a new electrode. → The application of the mediator metal improved properties of a lead film electrode. - Abstract: In this paper an ex situ plated lead film electrode prepared with use of the mediator metal (Zn) was elaborated. The electrochemical method for lead film formation is based on a co-deposition of a metal of interest (Pb) with a reversibly deposited mediator metal (Zn) and then on an oxidation of zinc and further deposition of lead by the appropriate potential. This serves to increase the density of islands of lead atoms, promoting lead film growth. The lead-based sensors were characterized by optical method (atomic force microscopy (AFM)) and as well as cyclic, linear sweep and square wave voltammetry. The adsorptive system of folic acid was employed to investigate the electrochemical characteristics a novel type of lead film electrode. Well-formed stripping peaks and a linear dependence of the stripping current on the folic acid concentration were observed on the lead film electrode prepared with use of the mediator metal while comparative measurements attempted with the lead film electrode prepared without use of the mediator metal were unsuccessful.

  18. Broad-beam, high current, metal ion implantation facility

    Brown, I.G.; Dickinson, M.R.; Galvin, J.E.; Godechot, X.; MacGill, R.A.

    1990-07-01

    We have developed a high current metal ion implantation facility with which high current beams of virtually all the solid metals of the Periodic Table can be produced. The facility makes use of a metal vapor vacuum arc ion source which is operated in a pulsed mode, with pulse width 0.25 ms and repetition rate up to 100 pps. Beam extraction voltage is up to 100 kV, corresponding to an ion energy of up to several hundred keV because of the ion charge state multiplicity; beam current is up to several Amperes peak and around 10 mA time averaged delivered onto target. Implantation is done in a broad-beam mode, with a direct line-of-sight from ion source to target. Here we describe the facility and some of the implants that have been carried out using it, including the 'seeding' of silicon wafers prior to CVD with titanium, palladium or tungsten, the formation of buried iridium silicide layers, and actinide (uranium and thorium) doping of III-V compounds. 16 refs., 6 figs

  19. Liquid metal current collector applications and material compatibility

    Carr, S.L.; Stevens, H.O.

    1978-01-01

    The objective of this paper has been to summarize briefly the material considerations involved in the development of liquid metal current collectors for homopolar machinery applications. A significant amount of data in this regard has been obtained over the last several years by individual researchers for NaK exposure conditions. However, NaK material compatibility data over the entire time and temperature range of interest is highly desirable. At DTNSRDC, a 300 kW superconducting homopolar motor and generator are under test, both utilizing free surface tongue-and-groove current collectors with NaK as the working fluid. In addition to demonstrating the feasibility of other aspects of machine design, the intention is to use these machines as vehicles for testing of the several liquid metal current collector concepts which are considered worthwhile candidates for incorporation in future full-scale machines. It is likely that the optimal collector approach for a large low speed motor may be quite different from that for a smaller high speed generator, possibly involving the use of different liquid metals

  20. Occurrence of lead-related symptoms below the current occupational safety and health act allowable blood lead levels.

    Rosenman, Kenneth D; Sims, Amy; Luo, Zhehui; Gardiner, Joseph

    2003-05-01

    To determine the occurrence of symptoms of lead toxicity at levels below the current allowable Occupational Safety and Health Act blood lead level of 50 micrograms/dL, standardized telephone interviews were conducted of individuals reported to a statewide laboratory-based surveillance system. Four hundred and ninety-seven, or 75%, of the eligible participants were interviewed. Gastrointestinal, musculoskeletal, and nervous system symptoms increased with increasing blood lead levels. Nervous, gastrointestinal, and musculoskeletal symptoms all began to be increased in individuals with blood leads between 30-39 micrograms/dL and possibly at levels as low as 25-30 micrograms/dL for nervous system symptoms. The results of this study of increased symptoms are consistent with and provide added weight to previous results showing subclinical changes in the neurologic and renal systems and sperm counts at blood lead levels currently allowed by the Occupational Safety and Health Act.

  1. Isotopic characterisation of lead in contaminated soils from the vicinity of a non-ferrous metal smelter near Plovdiv, Bulgaria

    Bacon, Jeffrey R. [Macaulay Institute, Craigiebuckler, Aberdeen AB15 8QH (United Kingdom)]. E-mail: j.bacon@macaulay.ac.uk; Dinev, Nikolai S. [N Poushkarov Institute of Soil Science and Agroecology, Sofia (Bulgaria)

    2005-03-01

    Soil samples from the vicinity of a non-ferrous metal smelter near Plovdiv, Bulgaria contained very high concentrations of cadmium, lead and zinc (up to 140, 4900 and 5900 mg kg{sup -1}, respectively). A roadside soil in a relatively uncontaminated area also contained high concentrations of the same metals (24, 1550 and 1870 mg kg{sup -1}, respectively) indicating that the transport of ores could be a source of contamination. Even though the lead isotope ratios in all the samples fell within a very narrow range (for example, 1.186-1.195 for {sup 206}Pb/{sup 207}Pb), the samples could be differentiated into three distinct groups: ores ({sup 206}Pb/{sup 207}Pb and {sup 208}Pb/{sup 207}Pb ratios of 1.1874-1.1884 and 2.4755-2.4807, respectively), current deposition (1.1864 and 2.4704-2.4711, respectively) and local background (1.1927-1.1951 and 2.4772-2.4809, respectively). Although most of the current deposition has its origin in the ores used at the smelter, up to 12% could be from other sources such as petrol lead. - Although soils in the vicinity of a non-ferrous metal smelter near Plovdiv, Bulgaria, have become highly contaminated with the ores used, lead isotope analysis has revealed that up to 12% of current deposition could be from other sources such as petrol lead.

  2. Isotopic characterisation of lead in contaminated soils from the vicinity of a non-ferrous metal smelter near Plovdiv, Bulgaria

    Bacon, Jeffrey R.; Dinev, Nikolai S.

    2005-01-01

    Soil samples from the vicinity of a non-ferrous metal smelter near Plovdiv, Bulgaria contained very high concentrations of cadmium, lead and zinc (up to 140, 4900 and 5900 mg kg -1 , respectively). A roadside soil in a relatively uncontaminated area also contained high concentrations of the same metals (24, 1550 and 1870 mg kg -1 , respectively) indicating that the transport of ores could be a source of contamination. Even though the lead isotope ratios in all the samples fell within a very narrow range (for example, 1.186-1.195 for 206 Pb/ 207 Pb), the samples could be differentiated into three distinct groups: ores ( 206 Pb/ 207 Pb and 208 Pb/ 207 Pb ratios of 1.1874-1.1884 and 2.4755-2.4807, respectively), current deposition (1.1864 and 2.4704-2.4711, respectively) and local background (1.1927-1.1951 and 2.4772-2.4809, respectively). Although most of the current deposition has its origin in the ores used at the smelter, up to 12% could be from other sources such as petrol lead. - Although soils in the vicinity of a non-ferrous metal smelter near Plovdiv, Bulgaria, have become highly contaminated with the ores used, lead isotope analysis has revealed that up to 12% of current deposition could be from other sources such as petrol lead

  3. Reaction Current Phenomenon in Bifunctional Catalytic Metal-Semiconductor Nanostructures

    Hashemian, Mohammad Amin

    Energy transfer processes accompany every elementary step of catalytic chemical processes on material surface including molecular adsorption and dissociation on atoms, interactions between intermediates, and desorption of reaction products from the catalyst surface. Therefore, detailed understanding of these processes on the molecular level is of great fundamental and practical interest in energy-related applications of nanomaterials. Two main mechanisms of energy transfer from adsorbed particles to a surface are known: (i) adiabatic via excitation of quantized lattice vibrations (phonons) and (ii) non-adiabatic via electronic excitations (electron/hole pairs). Electronic excitations play a key role in nanocatalysis, and it was recently shown that they can be efficiently detected and studied using Schottky-type catalytic nanostructures in the form of measureable electrical currents (chemicurrents) in an external electrical circuit. These nanostructures typically contain an electrically continuous nanocathode layers made of a catalytic metal deposited on a semiconductor substrate. The goal of this research is to study the direct observations of hot electron currents (chemicurrents) in catalytic Schottky structures, using a continuous mesh-like Pt nanofilm grown onto a mesoporous TiO2 substrate. Such devices showed qualitatively different and more diverse signal properties, compared to the earlier devices using smooth substrates, which could only be explained on the basis of bifunctionality. In particular, it was necessary to suggest that different stages of the reaction are occurring on both phases of the catalytic structure. Analysis of the signal behavior also led to discovery of a formerly unknown (very slow) mode of the oxyhydrogen reaction on the Pt/TiO2(por) system occurring at room temperature. This slow mode was producing surprisingly large stationary chemicurrents in the range 10--50 microA/cm2. Results of the chemicurrent measurements for the bifunctional

  4. Liquid metal magnetohydrodynamic flows in manifolds of dual coolant lead lithium blankets

    Mistrangelo, C., E-mail: chiara.mistrangelo@kit.edu; Bühler, L.

    2014-10-15

    Highlights: • MHD flows in model geometries of DCLL blanket manifolds. • Study of velocity, pressure distributions and flow partitioning in parallel ducts. • Flow partitioning affected by 3D MHD pressure drop and velocity distribution in the expanding zone. • Reduced pressure drop in a continuous expansion compared to a sudden expansion. - Abstract: An attractive blanket concept for a fusion reactor is the dual coolant lead lithium (DCLL) blanket where reduced activation steel is used as structural material and a lead lithium alloy serves both to produce tritium and to remove the heat in the breeder zone. Helium is employed to cool the first wall and the blanket structure. Some critical issues for the feasibility of this blanket concept are related to complex induced electric currents and 3D magnetohydrodynamic (MHD) phenomena that occur in distributing and collecting liquid metal manifolds. They can result in large pressure drop and undesirable flow imbalance in parallel poloidal ducts forming blanket modules. In the present paper liquid metal MHD flows are studied for different design options of a DCLL blanket manifold with the aim of identifying possible sources of flow imbalance and to predict velocity and pressure distributions.

  5. Formal recycling of e-waste leads to increased exposure to toxic metals: an occupational exposure study from Sweden.

    Julander, Anneli; Lundgren, Lennart; Skare, Lizbet; Grandér, Margaretha; Palm, Brita; Vahter, Marie; Lidén, Carola

    2014-12-01

    Electrical and electronic waste (e-waste) contains multiple toxic metals. However, there is currently a lack of exposure data for metals on workers in formal recycling plants. The objective of this study was to evaluate workers' exposure to metals, using biomarkers of exposure in combination with monitoring of personal air exposure. We assessed exposure to 20 potentially toxic metals among 55 recycling workers and 10 office workers at three formal e-waste recycling plants in Sweden. Workers at two of the plants were followed-up after 6 months. We collected the inhalable fraction and OFC (37-mm) fraction of particles, using personal samplers, as well as spot samples of blood and urine. We measured metal concentrations in whole blood, plasma, urine, and air filters using inductively coupled plasma-mass spectrometry following acid digestion. The air sampling indicated greater airborne exposure, 10 to 30 times higher, to most metals among the recycling workers handling e-waste than among the office workers. The exposure biomarkers showed significantly higher concentrations of chromium, cobalt, indium, lead, and mercury in blood, urine, and/or plasma of the recycling workers, compared with the office workers. Concentrations of antimony, indium, lead, mercury, and vanadium showed close to linear associations between the inhalable particle fraction and blood, plasma, or urine. In conclusion, our study of formal e-waste recycling shows that workers performing recycling tasks are exposed to multiple toxic metals. Copyright © 2014. Published by Elsevier Ltd.

  6. Development of a multiple HTS current lead assembly for corrector magnets application

    Wu, J.L.; Dederer, J.T.; Singh, S.K.

    1994-01-01

    Vapor-cooled current leads used for transmitting power to superconducting power equipment such as the corrector magnets in the SSC spools can introduce a significant heat leak into the cryostat which results in cryogen boil-off. Replenishing the boil-off or refrigerating and liquefying the vapors associated with the cooling of these leads may constitute a significant portion of the operating cost and/or the capital investment of the power equipment. Theoretical studies and experiments have demonstrated that the heat leak introduced by a current lead can be significantly reduced by using ceramic high temperature superconductor (HTSC) as part of the conductor in the current leads. A HTSC reduces heat leak in a current lead by being superconducting in the temperature range below its critical temperature and by having a low temperature thermal conductivity which is generally orders of magnitude lower than the copper alloys commonly used as the current lead conductors. This combination reduces Joule heating and heat conduction, resulting in lower heat leak to the cryostat. To demonstrate the advantages and large scale application of this technology, Westinghouse Science ampersand Technology Center has continued its efforts in High Temperature Superconducting (HTS) current lead development. The efforts include qualification testing and selection of commercial sources of HTSC for current leads and the successful development of a 12 x 100 A multiple HTS current lead assembly prototype for SSC Corrector Element Power Lead application. The efforts on the design, fabrication and testing of the multiple HTS lead assembly is reported below

  7. Ultra-Low Heat-Leak, High-Temperature Superconducting Current Leads for Space Applications

    Rey, Christopher M.

    2013-01-01

    NASA Goddard Space Flight Center has a need for current leads used in an adiabatic demagnetization refrigerator (ADR) for space applications. These leads must comply with stringent requirements such as a heat leak of approximately 100 W or less while conducting up to 10 A of electric current, from more than 90 K down to 10 K. Additionally, a length constraint of leak leads currently to NASA's specs.

  8. Persistent currents in metallic rings containing a quantum dot

    Machura, Lukasz; Łuczka, Jerzy

    2015-01-01

    Currents in metallic rings with a quantum dot are studied in the framework of a Langevin equation for a magnetic flux passing through the ring. Two scenarios are considered: one in which thermal fluctuations of the dissipative part of the current are modeled by classical Johnson–Nyquist noise and one in which quantum character of thermal fluctuations is taken into account in terms of a quantum Smoluchowski equation. The impact of the amplitude and phase of the transmission coefficient of the electron through a quantum dot on current characteristics is analyzed. In tailored parameter regimes, both scenarios can exhibit the transition from para- to diamagnetic response of the current versus external magnetic flux. The type of response is more robust to changes of the amplitude of the transmission coefficient and more sensitive to changes of the phase around some values. - Highlights: • Langevin dynamics of the magnetic flux for classical and quantum Smoluchowski regimes. • Current-flux characteristics vs the amplitude and phase of the transmission coefficient. • Crucial role of the phase of the transmission coefficient. • Contribution to the development of effective control of current in mesoscopic rings

  9. Control and monitoring of oxygen content in molten metals. Application to lead and lead-bismuth melts

    Ghetta, V.; Fouletier, J.; Henault, M.; Le Moulec, A.

    2002-01-01

    The sources of error in potentiometric measurements of the oxygen activity in molten metals and the methods proposed to reduce these measurements errors are described. Specific constraints related to low temperature measurements are emphasized. Two set-ups for control of the oxygen activity in molten lead and lead-bismuth were developed. They involve zirconia-based cells, i.e., an oxygen pump and an oxygen probe. The performance of the set-ups was characterized attempts to reduce the working temperature (T<450 deg C) are discussed. (authors)

  10. High-current pulsed ion source for metallic ions

    Gavin, B.; Abbott, S.; MacGill, R.; Sorensen, R.; Staples, J.; Thatcher, R.

    1981-03-01

    A new sputter-ion PIG source and magnet system, optimized for intermediate charge states, q/A of 0.02 to 0.03, is described. This source will be used with the new Wideroe-based injector for the SuperHILAC. Pulsed electrical currents of several emA of heavy metal ions have been produced in a normalized emittance area of .05π cm-mr. The source system is comprised of two electrically separate anode chambers, one in operation and one spare, which can be selected by remote control. The entire source head is small and quickly removable

  11. Current leads for superconducting solenoids in a transportable Dewar flask for currents up to 1kA

    Shirshov, L.S.

    1981-01-01

    A simple design of the current lead for currents up to 1 kA into a transportable helium dewar with 22 mm neck diameter is described. The lead characteristics have been studied at various conditions. Examples of pulse superconducting solenoid usage, parmitting to achieve the magnetic field up to 3.3 T are given. The 1% field homogeneity has been obtained on a length of 90 mm [ru

  12. Criterion for burn-up conditions in gas-cooled cryogenic current leads

    Bejan, A.; Cluss, E.M. Jr.

    1976-01-01

    Superconducting magnets are energized through helium vapour-cooled cryogenic current leads operating at high ratios of current to mass flow. The high current operation where lead temperature, runaway, and eventual burn-up are likely to occur is investigated. A simple criterion for estimating the burn-up operation conditions (current, mass flow) for a given lead geometry (cross-sectional area, length, heat exchanger area) is presented. This article stresses the role played by the available heat exchanger area in avoiding burn-up at high ratios of current to mass flow. (author)

  13. Method to precipitate metals on zirconium articles without using current

    Donaghy, R.E.

    1978-01-01

    Tubes or other bodies made of zirconium or Zr alloys used for taking up nuclear fuels are coated without current with a metal film to improve the mechanical and corrosion properties. The article is activated in a solution of ammonium bifluoride and sulphuric acid where an electrical conducting fixed and loose layer are fermed. This loose film is removed chemically by reacting with fluoroboric acid or hydrofluorosilica acid by ultrasonic treatment or by stripping from organic material (cotton, polyester, nylon). The current-free plating with Cu and Ni is described. The article is washed with deionized water between the process steps and finally degassed at a temperature of 150-200 0 C. (IHOE) [de

  14. Alternating-current MHD conduction pump for ferrous metals

    Nadezhnikov, N.M.; Krauya, V.M.; Yankop, E.K.

    1979-01-01

    Results are presented of theoretical and experimental studies pertaining to an ac MHD conduction pump with separate excitation and a C-core magnet structure. Its mathematical model is based on the following assumptions: (1) During complete braking the liquid metal in the channel is stationary; (2) there is no current leakage in the channel beyond the interelectrode region; (3) during operation the longitudinal axis of the pump is in a vertical position; (4) the current density in the electrodes at a distance infinitely far from the active channel segment is uniformly distributed; (5) there are no magnetic leakage fluxes in the model; and (6) the left-hand electrode in the model can be brought out in two different ways, variant I or variant II. 7 references

  15. Analysis of the stability of native oxide films at liquid lead/metal interfaces

    Lesueur, C.; Chatain, D.; Gas, P.; Bergman, C.; Baque, F.

    2002-01-01

    The interface between liquid lead and different metallic solids (pure metals: Al, Fe and Ni, and T91 steel) was investigated below 400 deg C under ultrahigh vacuum (UHV) by wetting experiments. The aim was to check the physical stability of native oxide films grown at the surface of the substrates, along a contact with liquid lead. Two types of metallic substrates were used: i) conventional bulk polycrystals, and ii) nanocrystalline films obtained by e-beam evaporation under UHV. The actual contact between liquid lead and the solid substrates was achieved by preparing lead drops in-situ. Wetting experiments were performed using sessile drop and/or liquid bridge methods. Fresh solid surfaces and former liquid/solid interfaces can be explored by squeezing and stretching a liquid lead bridge formed between two parallel and horizontal substrates. It is shown that the contact with liquid lead produces the detachment of the native oxide films grown on the metallic solids. It is concluded that if oxide coatings are needed to protect a metallic solid from attack by liquid lead, they should be self-renewable. (authors)

  16. Performance of bismuth tape current leads under vibration; Bi tepu sei denryu rido no shindo tokusei

    Suzuki, E.; Kurihara, M. [Railway Techniical Research Institute, Tokyo (Japan)

    2000-02-25

    The superconducting magnets on Maglev vehicles when running vibrate mechanically due to electromagnetic disturbance from the ground coils. Therefore, the current leads fixed on the superconducting coil, which is vibration at about 98 m/s{sup 2} (=10g), are also required to endure the vibration. We executed dynamic vibration tests for two types of current leads (straight and arc types) which had a multi-stacked configuration of Ag-sheathed Bi2223 tapes impregnated with epoxy resin in a concaved reinforcing gutter. We evaluated the straight-type lead for an operating current of 700 A after every vibration test in liquid nitrogen for one hour under the dynamic strain deformation of 50-100 {mu} on the surface of the reinforcing material covering the current lead. We could not detect degradation of the current lead by vibration through the total cycles of 3.9 x 10{sup 6} after continuous vibration tests. We also executed vibration tests for arc-type current leads which were combined with an actual energized superconducting coil for a Maglev. Large accelerations of these current leads occurred at frequencies of 308 and 375 Hz. In spite of the maximum acceleration of 600-700 m/s{sup 2} generated by actuating the excessive force on a superconducting coil for two seconds, which occurred on these current leads carrying 500 A, the superconductivity of the current leads did not shift to normal conductivity. There was no damage to either type of current lead during these vibration tests. So we confirmed the good prospect for the application of these current leads to actual Maglev superconducting magnets. (author)

  17. Present status and future perspective of R and D on lead heavy metal-cooled fast reactors

    Takahashi, Minoru

    2007-01-01

    Since a lead heavy metal (lead-bismuth eutectic) is chemically inert and has higher boiling point compared to a sodium, a lead heavy metal-cooled fast reactor can be inherently safe and has good nuclear characteristics and is so suitable to a medium-small size of the reactor. R and D on corrosion of a lead heavy metal has been carried out in the world and this issue might be solved to choose specific corrosion resistant alloys for structural materials and fuel cans of a lead heavy metal-cooled reactor. This article reviews present status and future perspective on lead heavy metal-cooled fast reactors. (T. Tanaka)

  18. High temperature superconducting current lead test facility with heat pipe intercepts

    Blumenfeld, P.E.; Prenger, C.; Roth, E.W.; Stewart, J.A.

    1998-01-01

    A high temperature superconducting (HTS) current lead test facility using heat pipe thermal intercepts is under development at the Superconducting Technology Center at Los Alamos National Laboratory. The facility can be configured for tests at currents up to 1,000 A. Mechanical cryocoolers provide refrigeration to the leads. Electrical isolation is maintained by intercepting thermal energy from the leads through cryogenic heat pipes. HST lead warm end temperature is variable from 65 K to over 90 K by controlling heat pipe evaporator temperature. Cold end temperature is variable up to 30 K. Performance predictions in terms of heat pipe evaporator temperature as a function of lead current are presented for the initial facility configuration, which supports testing up to 200 A. Measurements are to include temperature and voltage gradient in the conventional and HTS lead sections, temperature and heat transfer rate in the heat pipes. as well as optimum and off-optimum performance of the conventional lead sections

  19. Liquid metal current collectors for high-speed rotating machinery

    Carr, S.L.

    1976-01-01

    Recent interest in superconducting motors and generators has created a renewed interest in homopolar machinery. Homopolar machine designs have always been limited by the need for compact, high-current, low-voltage, sliding electrical curent collectors. Conventional graphite-based solid brushes are inadequate for use in homopolar machines. Liquid metals, under certain conditions of relative sliding velocities, electrical currents, and magnetic fields are known to be capable of performing well in homopolar machines. An effort to explore the capabilities and limits of a tongue-and-groove style current collector, utilizing sodium-potassium eutectic alloy (NaK) as the working fluid in high sliding speed operation is reported here. A double current collector generator model with a 14.5-cm maximum rotor diameter, 20,000 rpm rotational capability, and electrical current carrying ability was constructed and operated successfully at a peripheral velocity of 125 m/s. The limiting factor in these experiments was a high-speed fluid-flow instability resulting in the ejection of the working fluid from the operating portions of the collectors. The effects of collector size and geometry, working fluid (NaK or water), and cover gas pressure are reported. Hydrodynamic frictional torque-speed curves are given for the two fluids and for several geometries. Electrical resistances as a function of peripheral velocity at 60 amperes are reported, and the phenomenology of the high-speed fluid-flow instabilities is discussed. The possibility of long-term high-speed operation of current collectors of the tongue-and-groove type, along with experimental and theoretical hydrodynamic friction losses at high peripheral velocities, is considered

  20. Concentrations of heavy metals (lead, manganese, cadmium) in blood and urine of former uranium workers

    Apostolova, D.; Pavlova, S.; Paskalev, Z.

    1999-01-01

    Uranium ores contain heavy metals and other stable chemical elements as oxides, hydro-carbonates, sulphates, etc. During chemical processing of ore they could be transformed into compounds soluble in biologic liquids. The purpose of this study was to determine the combined intoxication of uranium miners and millers by heavy metals and radiation. Heavy metal (lead, manganese and cadmium) concentrations in blood and urine od 149 former uranium miners and millers were determined by AAS method. Data of significantly increased lead and manganese concentration in blood (p<0.05) of two groups were established in comparison with a control group. There is no statistical significant differences in the cadmium concentrations. The lead and manganese blood levels at the uranium millers were significant higher than those of the uranium miner group (p<0.05). Tendency towards increased blood lead concentrations of uranium millers depending on the length of service was established

  1. Rectified tunneling current response of bio-functionalized metal-bridge-metal junctions.

    Liu, Yaqing; Offenhäusser, Andreas; Mayer, Dirk

    2010-01-15

    Biomolecular bridged nanostructures allow direct electrical addressing of electroactive biomolecules, which is of interest for the development of bioelectronic and biosensing hybrid junctions. In the present paper, the electroactive biomolecule microperoxidase-11 (MP-11) was integrated into metal-bridge-metal (MBM) junctions assembled from a scanning tunneling microscope (STM) setup. Before immobilization of MP-11, the Au working electrode was first modified by a self-assembled monolayer of 1-undecanethiol (UDT). A symmetric and potential independent response of current-bias voltage (I(t)/V(b)) was observed for the Au (substrate)/UDT/Au (tip) junction. However, the I(t)/V(b) characteristics became potential dependent and asymmetrical after binding of MP-11 between the electrodes of the junction. The rectification ratio of the asymmetric current response varies with gate electrode modulation. A resonant tunneling process between metal electrode and MP-11 enhances the tunneling current and is responsible for the observed rectification. Our investigations demonstrated that functional building blocks of proteins can be reassembled into new conceptual devices with operation modes deviating from their native function, which could prove highly useful in the design of future biosensors and bioelectronic devices. Copyright 2009 Elsevier B.V. All rights reserved.

  2. Rhizofiltration of a Heavy metal (lead) containing wastewater using the wetland plant carex pendula

    Yadav, Brijesh K. [Environmental Hydrogeology Group, Department of Earth Sciences, Faculty of Geosciences, University of Utrecht, Utrecht (Netherlands); Indian Institute of Technology Delhi, Department of Civil Engineering, New Delhi (India); Siebel, Maarten A.; Bruggen, Johan J.A. van [Department of Environmental Resources, UNESCO-IHE Institute for Water Education, Delft (Netherlands)

    2011-05-15

    Rhizofiltration is a subset technique of phytoremediation which refers to the approach of using plant biomass for removing contaminants, primarily toxic metals, from polluted water. The effective implementation of this in situ remediation technology requires experimental as well as conceptual insight of plant-water interactions that control the extraction of targeted metal from polluted water resources. Therefore, pot and simulation experiments are used in this study to investigate the rhizofiltration of a lead containing wastewater using plants of Carex pendula, a common wetland plant found in Europe. The metal contaminant extraction along with plant growth and water uptake rates from a wastewater having varying Pb concentration is studied experimentally for 2 wk. The temporal distribution of the metal concentration in the wastewater and the accumulated metal in different compartments of C. pendula at the end are analyzed using atomic absorption spectrometry. Parameters of the metal uptake kinetics are deduced experimentally for predicting the metal removal by root biomass. Further, mass balance equations coupled with the characterized metal uptake kinetics are used for simulating the metal partitioning from the wastewater to its accumulation in the plant biomass. The simulated metal content in wastewater and plant biomass is compared with the observed data showing a good agreement with the later. Results show that C. pendula accumulates considerable amounts of lead, particularly in root biomass, and can be considered for the cleanup of lead contaminated wastewaters in combination with proper biomass disposal alternatives. Also, the findings can be used for performing further non-hydroponics experiment to mimic the real wetland conditions more closely. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  3. Biosorption of lead and copper by heavy-metal tolerant Micrococcus luteus DE2008.

    Puyen, Zully M; Villagrasa, Eduard; Maldonado, Juan; Diestra, Elia; Esteve, Isabel; Solé, Antoni

    2012-12-01

    Micrococcus luteus DE2008 has the ability to absorb lead and copper. The effect of these metals on biomass and viability of this microorganism were investigated and removal of the metals from culture media was determined. Lead had no effect on the biomass expressed as mg Carbon/cm(3) of M. Iuteus DE2008, but in the case of copper, the minimum metal concentration that affected the biomass was 0.1 mM Cu(II). According to these results this microorganism shows a greater tolerance for lead. The minimum metal concentration that affected viability (expressed as the percentage of live cells) was 0.5 mM for both metals. M. luteus DE2008 exhibited a specific removal capacity of 408 mg/g for copper and 1965 mg/g for lead. This microorganism has a greater ability to absorb Pb(II) than Cu(II). M. luteus DE2008 could be seen as a microorganism capable of restoring environments polluted by lead and copper. Copyright © 2012 Elsevier Ltd. All rights reserved.

  4. Thermal conductivity measurement of HTS tapes and stacks for current lead applications

    Schwarz, Michael; Weiss, Klaus-Peter; Heller, Reinhard; Fietz, Walter H.

    2009-01-01

    The use of high-temperature-superconductors (HTS) within current leads offers a high potential to save cooling-power. The principle of HTS current leads is well established, e.g. for particle accelerators (LHC-CERN) but also on the commercial sector, which offer HTS current leads ready for use in small scale magnets and magnets systems. Future fusion machines currently under construction like ITER, W7-X or JT-60SA also will use HTS current leads. At the moment the standard material for HTS current leads is a Bi 2 Sr 2 Ca 2 Cu 3 O x (BSCCO)-AgAu composite tape. The common way to receive high current capacity current leads is to form stacks by sintering or soldering these tapes together. The solder changes the thermal conductivity of the stacks compared to the single tape in the temperature range from 4 K to 60 K. To estimate the heat flux from the warm environment to the cold application the measurement of the thermal conductivity of the soldered stack is mandatory. Therefore the thermal conductivity of stacks with different number of tapes is investigated. To measure the thermal conduction in the current flow direction, the axial heat flow method is used. Combining these results with FEM simulations gives the possibility to estimate the thermal conductivity normal to the flat tape plane. The resulting anisotropic thermal conductivity can be used to model the behaviour of the HTS tape under thermal disturbances more accurately.

  5. Understanding the molecular mechanism of pulse current charging for stable lithium-metal batteries

    Li, Qi; Tan, Shen; Li, Linlin; Lu, Yingying; He, Yi

    2017-01-01

    High energy and safe electrochemical storage are critical components in multiple emerging fields of technologies. Rechargeable lithium-metal batteries are considered to be promising alternatives for current lithium-ion batteries, leading to as much as a 10-fold improvement in anode storage capacity (from 372 to 3860 mAh g−1). One of the major challenges for commercializing lithium-metal batteries is the reliability and safety issue, which is often associated with uneven lithium electrodeposition (lithium dendrites) during the charging stage of the battery cycling process. We report that stable lithium-metal batteries can be achieved by simply charging cells with square-wave pulse current. We investigated the effects of charging period and frequency as well as the mechanisms that govern this process at the molecular level. Molecular simulations were performed to study the diffusion and the solvation structure of lithium cations (Li+) in bulk electrolyte. The model predicts that loose association between cations and anions can enhance the transport of Li+ and eventually stabilize the lithium electrodeposition. We also performed galvanostatic measurements to evaluate the cycling behavior and cell lifetime under pulsed electric field and found that the cell lifetime can be more than doubled using certain pulse current waveforms. Both experimental and simulation results demonstrate that the effectiveness of pulse current charging on dendrite suppression can be optimized by choosing proper time- and frequency-dependent pulses. This work provides a molecular basis for understanding the mechanisms of pulse current charging to mitigating lithium dendrites and designing pulse current waveforms for stable lithium-metal batteries. PMID:28776039

  6. A Low Heat Inleak Cryogenic Station for Testing HTS Current Leads for the Large Hadron Collider

    Ballarino, A; Gomes, P; Métral, L; Serio, L; Suraci, A

    1999-01-01

    The LHC will be equipped with about 8000 superconducting magnets of all types. The total current to be transported into the cryogenic enclosure amounts to some 3360 kA. In order to reduce the heat load into the liquid helium, CERN intends to use High Temperature Superconducting (HTS) material for leads having current ratings up to 13 kA. The resistive part of the leads is cooled by forced flow of gaseous helium between 20 K and 300 K. The HTS part of the lead is immersed in a 4.5 K liquid helium bath, operates in self cooling conditions and is hydraulically separated from the resistive part. A cryogenic test station has been designed and built in order to assess the thermal and electrical performances of 13 kA prototype current leads. We report on the design, commissioning and operation of the cryogenic test station and illustrate its performance by typical test results of HTS current leads.

  7. Analysis of induced electrical currents from magnetic field coupling inside implantable neurostimulator leads

    Seidman Seth J

    2011-10-01

    Full Text Available Abstract Background Over the last decade, the number of neurostimulator systems implanted in patients has been rapidly growing. Nearly 50, 000 neurostimulators are implanted worldwide annually. The most common type of implantable neurostimulators is indicated for pain relief. At the same time, commercial use of other electromagnetic technologies is expanding, making electromagnetic interference (EMI of neurostimulator function an issue of concern. Typically reported sources of neurostimulator EMI include security systems, metal detectors and wireless equipment. When near such sources, patients with implanted neurostimulators have reported adverse events such as shock, pain, and increased stimulation. In recent in vitro studies, radio frequency identification (RFID technology has been shown to inhibit the stimulation pulse of an implantable neurostimulator system during low frequency exposure at close distances. This could potentially be due to induced electrical currents inside the implantable neurostimulator leads that are caused by magnetic field coupling from the low frequency identification system. Methods To systematically address the concerns posed by EMI, we developed a test platform to assess the interference from coupled magnetic fields on implantable neurostimulator systems. To measure interference, we recorded the output of one implantable neurostimulator, programmed for best therapy threshold settings, when in close proximity to an operating low frequency RFID emitter. The output contained electrical potentials from the neurostimulator system and those induced by EMI from the RFID emitter. We also recorded the output of the same neurostimulator system programmed for best therapy threshold settings without RFID interference. Using the Spatially Extended Nonlinear Node (SENN model, we compared threshold factors of spinal cord fiber excitation for both recorded outputs. Results The electric current induced by low frequency RFID emitter

  8. A novel route for the removal of bodily heavy metal lead (II)

    Huang, Weirong; Zhang, Penghua; Xu, Hui; He, Yongju; Wang, Fei; Liang, Gaowei; Chang, Shengli

    2015-01-01

    The lead ion concentration in bile is considerably higher than in blood, and bile is released into the alimentary tract. Thiol-modified SBA-15 administered orally can combine with lead ions in the alimentary tract. In this paper, the in vitro lead absorption of bile was investigated. This thiol-modified SBA-15 material was used in pharmacodynamics studies on rabbits. The result that the lead content in faeces was notably higher indicates that thiol-modified SBA-15 can efficiently remove lead. The mechanism could include the following: thiol-modified SBA-15 material cuts off the heavy metal lead recirculation in the process of bile enterohepatic circulation by chelating the lead in the alimentary tract, causing a certain proportion of lead to be removed by the thiol mesoporous material, and the lead is subsequently egested out of the body in faeces. The results indicate that this material might be a potential non-injection material for the removal bodily heavy metal lead in the alimentary tract. This material may also be a useful means of lead removal, especially for non-acute sub-poisoning symptoms. (paper)

  9. Design of a high-temperature superconductor current lead for electric utility SMES

    Niemann, R.C.; Cha, Y.S.; Hull, J.R.; Rey, C.M.; Dixon, K.D.

    1995-01-01

    Current leads that rely on high-temperature superconductors (HTSs) to deliver power to devices operating at liquid helium temperature have the potential to reduce refrigeration requirements to levels significantly below those achievable with conventional leads. The design of HTS current leads suitable for use in near-term superconducting magnetic energy storage (SMES) is in progress. The SMES system has an 0.5 MWh energy capacity and a discharge power of 30 MW. Lead-design considerations include safety and reliability, electrical and thermal performance, structural integrity, manufacturability, and cost. Available details of the design, including materials, configuration, and performance predictions, are presented

  10. Prediction of burnout of a conduction-cooled BSCCO current lead

    Seol, S.Y.; Cha, Y.S.; Niemann, R.C.; Hull, J.R.

    1996-01-01

    A one-dimensional heat conduction model is employed to predict burnout of a Bi 2 Sr 2 CaCu 2 O 8 current lead. The upper end of the lead is assumed to be at 77 K and the lower end is at 4 K. The results show that burnout always occurs at the warmer end of the lead. The lead reaches its burnout temperature in two distinct stage. Initially, the temperature rises slowly when part of the lead is in flux-flow state. As the local temperature reaches the critical temperature, it begins to increase sharply. Burnout time depends strongly on flux-flow resistivity

  11. Metal is not inert: role of metal ions released by biocorrosion in aseptic loosening--current concepts.

    Cadosch, Dieter; Chan, Erwin; Gautschi, Oliver P; Filgueira, Luis

    2009-12-15

    Metal implants are essential therapeutic tools for the treatment of bone fractures and joint replacements. The metals and metal alloys used in contemporary orthopedic and trauma surgery are well tolerated by the majority of patients. However, complications resulting from inflammatory and immune reactions to metal implants have been well documented. This review briefly discusses the different mechanisms of metal implant corrosion in the human body, which lead to the release of significant levels of metal ions into the peri-implant tissues and the systemic blood circulation. Additionally, this article reviews the effects of the released ions on bone metabolism and the immune system and discusses their involvement in the pathophysiological mechanisms of aseptic loosening and metal hypersensitivity in patients with metal implants.

  12. Experience of 12 kA / 16 V SMPS during the HTS Current Leads Test

    Panchal, P.; Christian, D.; Panchal, R.; Sonara, D.; Purwar, G.; Garg, A.; Nimavat, H.; Singh, G.; Patel, J.; Tanna, V.; Pradhan, S.

    2017-04-01

    As a part of up gradation plans in SST-1 Tokamak, one pair of 3.3 kA rated prototype hybrid current leads were developed using Di-BSCCO as High Temperature Superconductors (HTS) and the copper heat exchanger. In order to validate the manufacturing procedure prior to go for series production of such current leads, it was recommended to test these current leads using dedicated and very reliable DC switch mode power supply (SMPS). As part of test facility, 12 kA, 16 VDC programmable SMPS was successfully installed, commissioned and tested. This power supply has special features such as modularity, N+1 redundancy, very low ripple voltage, precise current measurements with Direct Current Current Transformer, CC/CV modes with auto-crossover and auto-sequence programming. As a part of acceptance of this converter, A 5.8 mΩ water-cooled resistive dummy load and PLC based SCADA system is designed, developed for commissioning of power supply. The same power supply was used for the testing of the prototype HTS current leads. The paper describes the salient features and experience of state-of-art of power supply and results obtained from this converter during the HTS current leads test.

  13. Recent trends and current practices for secondary processing of zinc and lead. Part II: zinc recovery from secondary sources.

    Sahu, Kamala Kanta; Agrawal, Archana; Pandey, Banshi Dhar

    2004-08-01

    Almost all metallurgical processes are associated with the generation of wastes and residues that may be hazardous or non-hazardous in nature depending upon the criteria specified by institutions such as the US Environment Protection Agency, etc. Wastes containing heavy and toxic metals such as arsenic, cadmium, chromium, nickel, lead, copper, mercury, zinc, etc., that are present beyond permissible limits deemed to be treated or disposed of, and non-hazardous wastes can be utilized for metal recovery or safe disposal. Zinc is in growing demand all over the world. In India, a major amount of zinc is imported and therefore processing of zinc secondaries will assist in satisfying the gap between demand and supply to some extent. This report mainly focuses on the current practices and recent trends on the secondary processing of zinc. Attempts made by various laboratories to develop ecofriendly processes for the recovery of zinc from secondary raw materials are also described and discussed.

  14. Test results of the 18 kA EDIPO HTS current leads

    Wesche, Rainer; Bagnasco, Maurizio; Bruzzone, Pierluigi; Felder, Roland; Guetg, Marc; Holenstein, Manuel; Jenni, Markus; March, Stephen; Roth, Felix; Vogel, Martin

    2011-01-01

    For the new test facility EDIPO (European DIPOle), to be hosted by CRPP, two 18 kA HTS current leads were manufactured and successfully tested. The HTS module, made of AgMgAu/Bi-2223 tapes, is cooled only by heat conduction to the cold end, while the copper part is cooled by forced flow helium gas. The current leads were tested at low voltage up to the maximum current of 18 kA. The helium mass flow rates required for stable operation at various currents were determined. In addition to the steady state operation, the transient behavior in the case of a loss of flow was studied experimentally. The test results provide an estimate of the operational limits of the EDIPO HTS current leads.

  15. Test results of the 18 kA EDIPO HTS current leads

    Wesche, Rainer, E-mail: rainer.wesche@psi.ch [Ecole Polytechnique Federale de Lausanne (EPFL), Centre de Recherches en Physique des Plasmas (CRPP), Association Euratom - Confederation Suisse, 5232 Villigen PSI (Switzerland); Bagnasco, Maurizio; Bruzzone, Pierluigi; Felder, Roland; Guetg, Marc; Holenstein, Manuel; Jenni, Markus; March, Stephen; Roth, Felix; Vogel, Martin [Ecole Polytechnique Federale de Lausanne (EPFL), Centre de Recherches en Physique des Plasmas (CRPP), Association Euratom - Confederation Suisse, 5232 Villigen PSI (Switzerland)

    2011-10-15

    For the new test facility EDIPO (European DIPOle), to be hosted by CRPP, two 18 kA HTS current leads were manufactured and successfully tested. The HTS module, made of AgMgAu/Bi-2223 tapes, is cooled only by heat conduction to the cold end, while the copper part is cooled by forced flow helium gas. The current leads were tested at low voltage up to the maximum current of 18 kA. The helium mass flow rates required for stable operation at various currents were determined. In addition to the steady state operation, the transient behavior in the case of a loss of flow was studied experimentally. The test results provide an estimate of the operational limits of the EDIPO HTS current leads.

  16. Reduction of the heat leak in superconducting system at half-wave-rectified current mode by peltier current lead

    Yamaguchi, Takayuki; Ohtaki, Naohiro; Nakamura, Keiji; Yamaguchi, Satarou; Hasegawa, Yasuhiro

    2002-01-01

    Experiments of Peltier current lead (PCL) were performed by the way of half-wave-rectified current (HWRC) for an evaluation of the PCL system in the drive with the large-rippled current. The current ripple of the HWRC is large, and we discussed the cooling capability of the current ripple. The experimental results revealed that the temperature difference of the thermoelectric-element (TE) increased with the magnitude of the current in the PCL system, despite the large current ripple. Calorimetric measurements revealed that the PCL reduced the heat leak of 60% for the peak current 90A. We compared the PCL systems of the direct current (dc) mode and the HWRC mode. The results showed that the current dependence of the temperature difference in the HWRC mode did not match that of the dc mode, but those of the heat leak matched well. The performance of the Peltier cooling in the HWRC mode is reduced to be 2/π time of the Seebeck coefficient for the dc mode by using the time-average method. (author)

  17. Reduction of the heat leak in superconducting system at half-wave-rectified current mode by peltier current lead

    Yamaguchi, T; Nakamura, K; Yamaguchi, S; Hasegawa, Y

    2002-01-01

    Experiments of Peltier current lead (PCL) were performed by the way of half-wave-rectified current (HWRC) for an evaluation of the PCL system in the drive with the large-rippled current. The current ripple of the HWRC is large, and we discussed the cooling capability of the current ripple. The experimental results revealed that the temperature difference of the thermoelectric-element (TE) increased with the magnitude of the current in the PCL system, despite the large current ripple. Calorimetric measurements revealed that the PCL reduced the heat leak of 60% for the peak current 90A. We compared the PCL systems of the direct current (dc) mode and the HWRC mode. The results showed that the current dependence of the temperature difference in the HWRC mode did not match that of the dc mode, but those of the heat leak matched well. The performance of the Peltier cooling in the HWRC mode is reduced to be 2/pi time of the Seebeck coefficient for the dc mode by using the time-average method. (author)

  18. Effect of pulse current on energy consumption and removal of heavy metals during electrodialytic soil remediation

    Sun, Tian Ran

    pathways to unacceptable dosages, leading to intolerable adverse effects on both public health and the environment. In the last decades, soil and water remediation have gained growing awareness, as the necessity becomes clearer for development of such techniques for elimination of the negative impact from......: transport of water (electroosmosis) and ions (electromigration), with electromigration being the most important transport process when treating heavy metal contaminated soils. Electrodialytic remediation (EDR), one of the enhanced electrochemical remediation techniques, is developed at the Technical...... compartments. Therefore no current is wasted for carrying ions from one electrode compartment to the other. The EDR technique has been tested for decontamination of a variety of different heavy metal polluted particulate materials: mine tailings, soil, different types of fly ashes, sewage sludge, freshwater...

  19. Full Cryogenic Test of 600 A HTS Hybrid Current Leads for the LHC

    Al-Mosawi, MK; Beduz, C; Ballarino, A; Yang, Y

    2007-01-01

    For full cryogenic test of CERN 600 A High Temperature Superconducting (HTS) current leads prior to integration into the Large Hadron Collider (LHC), a ded. facility has been designed, constructed and operated at the University of Southampton. The facility consists of purpose-built test cryostats, 20 K helium gas supply, helium gas flow and temperature control systems and quench protection system. Over 400 such leads have already been successfully tested and qualified for installation at CERN. This paper describes various design and operation aspects of the test facility and presents the detailed cryogenic test results of the CERN 600 A current leads, including steady state 20 K flow rates.

  20. Transient characteristics of current lead losses for the large scale high-temperature superconducting rotating machine

    Le, T. D.; Kim, J. H.; Park, S. I.; Kim, D. J.; Kim, H. M.; Lee, H. G.; Yoon, Y. S.; Jo, Y. S.; Yoon, K. Y.

    2014-01-01

    To minimize most heat loss of current lead for high-temperature superconducting (HTS) rotating machine, the choice of conductor properties and lead geometry - such as length, cross section, and cooling surface area - are one of the various significant factors must be selected. Therefore, an optimal lead for large scale of HTS rotating machine has presented before. Not let up with these trends, this paper continues to improve of diminishing heat loss for HTS part according to different model. It also determines the simplification conditions for an evaluation of the main flux flow loss and eddy current loss transient characteristics during charging and discharging period.

  1. Current-voltage characteristics of the semiconductor nanowires under the metal-semiconductor-metal structure

    Wen, Jing; Zhang, Xitian; Gao, Hong; Wang, Mingjiao

    2013-12-01

    We present a method to calculate the I-V characteristics of semiconductor nanowires under the metal-semiconductor-metal (MSM) structure. The carrier concentration as an important parameter is introduced into the expression of the current. The subband structure of the nanowire has been considered for associating it with the position of the Fermi level and circumventing the uncertainties of the contact areas in the contacts. The tunneling and thermionic emission currents in the two Schottky barriers at the two metal-semiconductor contacts are discussed. We find that the two barriers have different influences on the I-V characteristics of the MSM structure, one of which under the forward bias plays the role of threshold voltage if its barrier height is large and the applied voltage is small, and the other under the reverse bias controls the shapes of I-V curves. Our calculations show that the shapes of the I-V curves for the MSM structure are mainly determined by the barrier heights of the contacts and the carrier concentration. The nearly identical I-V characteristics can be obtained by using different values of the barrier heights and carrier concentration, which means that the contact type conversion can be ascribed not only to the changes of the barrier heights but also that of the carrier concentration. We also discuss the mechanisms of the ohmic-Schottky conversions and clarify the ambiguity in the literature. The possibility about the variation of the carrier concentration under the applied fields has been confirmed by experimental results.

  2. Experimental study of gas-cooled current leads for superconducting magnets

    Warren, R.P.

    1978-04-01

    Design details and experimental test results from several design variations of the gas-cooled, copper current leads used in conjunction with the superconducting dipole magnets for ESCAR (Experimental Superconducting Accelerator Ring) are reported. Thermal acoustic oscillations, which were experienced with an initial design, were eliminated in subsequent designs by a reduction of the hydraulic diameter. The occurrence of these oscillations is in general agreement with the stability analysis of Rott but the observed gas flow dependence is not in agreement with some other recently reported results for leads operated supercritical phase coolant. An empirically determined correlation was obtained by plotting lead resistance vs. enthalpy gain of the coolant gas. The resulting family of curves can be reduced to a single line on a plot of effective resistivity vs. the product of current and cross-sectional area divided by the product of the square of the mass flow of the coolant and the lead length. This correlation, which should be applicable to other designs of copper current leads in which ideal heat transfer to the coolant gas is approached, predicts that the enthalpy gain of the coolant, and therefore the peak lead temperature, is proportional to the cube of the ratio of current to coolant mass flow. The effective value of the strongly temperature-dependent kinematic viscosity of the coolant gas was found to vary linearly with the effective resistivity of the lead

  3. Mock-up qualification and prototype manufacture for ITER current leads

    Zhou, Tingzhi, E-mail: tingszhou@ipp.ac.cn [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei (China); Lu, Kun; Ran, Qingxiang; Ding, Kaizhong; Feng, Hansheng; Wu, Huan; Liu, Chenglian; Song, Yuntao [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei (China); Niu, Erwu [CNDA, Ministry of Science and Technology, Beijing (China); Bauer, Pierre; Devred, Arnaud [Magnet Division, ITER Organization, Cadarache (France)

    2015-10-15

    Highlights: • Vacuum brazing and electron beam welding qualification. • Machine and assembly strategy of fin type heat exchanger. • Soldering and joint resistance test of superconducting joint. • Pre-preg technology with vacuum bag on insulation. - Abstract: Three types of high temperature superconducting current leads (HTSCL) are designed to carry 68 kA, 55 kA or 10 kA to the ITER magnets. Before the supply of the HTS current lead series, the design and manufacturing process is qualified through mock-ups and prototypes. Seven mock-ups, representing the critical technologies of the current leads, were built and tested successfully in the Institute of Plasma Physics of the Chinese Academy of Sciences (ASIPP) in 2013. After the qualification some design features of the HTS leads were updated. This paper summarizes the qualification through mock-ups. In 2014 ASIPP started the manufacture of the prototypes. The preparation and manufacturing process are also described.

  4. Application of spectral analysis for differentiation between metals using signals from eddy-current transducers

    Abramovych, Anton; Poddubny, Volodymyr

    2017-01-01

    The authors theoretically and experimentally substantiated the use of the spectral method for processing a signal of the vortex-current metal detector for dichotomous differentiation between metals. Results of experimental research that prove the possibility of using spectral analysis for differentiation between metals were presented. The vortex-current method for detection of hidden metal objects was analyzed. It was indicated that amplitude of output VCD signal is determined by electric con...

  5. Qualification of Fin-Type Heat Exchangers for the ITER Current Leads

    Ballarino, A; Bordini, B; Devred, A; Ding, K; Niu, E; Sitko, M; Taylor, T; Yang, Y; Zhou, T

    2015-01-01

    The ITER current leads will transfer large currents of up to 68 kA into the biggest superconducting magnets ever built. Following the development of prototypes and targeted trials of specific manufacturing processes through mock-ups, the ASIPP (Chinese Institute of Plasma Physics) is preparing for the series fabrication. A key component of the ITER HTS current leads are the resistive heat exchangers. Special R&D was conducted for these components at CERN and ASIPP in support of their designs. In particular several mock-ups were built and tested in room temperature gas to measure the dynamic pressure drop and compare to 3D CFD models.

  6. A comparison on the heat load of HTS current leads with respect to uniform and non-uniform cross-sectional areas

    Han, Seung Hak; Nam, Seok Ho; Lee, Je Yull; Song, Seung Hyun; Jeon, Hae Ryong; Baek, Geon Woo; Ko, Tae Kuk [Yonsei University, Seoul (Korea, Republic of); Kang, Hyoung Ku [Korea National University of Transportation, Chungju (Korea, Republic of)

    2017-09-15

    Current lead is a device that connects the power supply and superconducting magnets. High temperature superconductor (HTS) has lower thermal conductivity and higher current density than normal metal. For these reasons, the heat load can be reduced by replacing the normal metal of the current lead with the HTS. Conventional HTS current lead has same cross-sectional area in the axial direction. However, this is over-designed at the cold-end (4.2 K) in terms of current. The heat load can be reduced by reducing this part because the heat load is proportional to the cross-sectional area. Therefore, in this paper, heat load was calculated from the heat diffusion equation of HTS current leads with uniform and non-uniform cross-sectional areas. The cross-sectional area of the warm-end (65K) is designed considering burnout time when cooling system failure occurs. In cold-end, Joule heat and heat load due to current conduction occurs at the same time, so the cross-sectional area where the sum of the two heat is minimum is obtained. As a result of simulation, current leads for KSTAR TF coils with uniform and non-uniform cross-sectional areas were designed, and it was confirmed that the non-uniform cross-sectional areas could further reduce the heat load.

  7. Research and development of an aimed magnetic lead current density-magnetic field diagnostic. Final report

    1985-01-01

    A diagnostics survey was made to provide a clear definition of advanced diagnostic needs and the limitations of current approaches in addressing those needs. Special attention was given to the adequacy with which current diagnostics are interfaced to signal processing/data acquisition devices and systems. Critical evaluations of selected alternative diagnostic techniques for future R and D activities are presented. The conceptual basis of the Aimed Magnetic Lead Gradiometric system as a current density/magnetic field diagnostic is established

  8. Health Assessment of Heavy Metal Pollution (Cadmium, Lead, Arsenic in Citrus Marketed in Tehran, Iran, 2015

    Razieh Saleh

    2017-03-01

    Full Text Available Background & Aims of the Study: Today, the environment pollution with heavy metals has increased. It is important to study various types of pollutions specially those regarding fruits. The effect of pollutions on food safety for human consumption is a global concern.  This study was conducted for health assessment of heavy metals pollution (cadmium, lead, and arsenic in citrus marketed in Tehran, Iran in 2015. Materials & Methods: After collecting and preparing 2 samples from each citrus species (tangerine, grapefruit, sweet lime, sour orange, orange with acid digestion method, the citrus pulp and peel were surveyed. Inductively coupled plasma optical emission spectrometry (ICP-OES was used to determine the concentrations of heavy metals with three replications. Moreover, SPSS version 19 was employed to perform statistical analysis. Results: The results showed that the concentration average of Cadmium, Lead and Arsenic in citrus samples of the pulp parts were 19.73, 42.95 and 2.30 mg/kg and in peel parts were 20.09, 42.71 and 2.12 mg/kg, respectively. The average concentrations of heavy metals were higher than WHO maximum permissible limits. Conclusions: Based on these results, consumption of citrus species has no adverse effect on the consumers’ health (except Sweet lime, Orange, Tangerine and Grapefruit in lead is risky for adults and Sweet lime and Orange that Health Index in Lead and Arsenic and Sour Orange, Tangerine and Grapefruit that Health Index in Lead is more than 1 and is risky for children. Thus, individuals living in Tehran should be cautious about using these citrus fruits and researchers should try to obtain national standards in the field of entering these metals to food in environmental conditions that are in Iran.

  9. Multivariate statistical assessment of heavy metal pollution sources of groundwater around a lead and zinc plant

    Zamani Abbas Ali

    2012-12-01

    Full Text Available Abstract The contamination of groundwater by heavy metal ions around a lead and zinc plant has been studied. As a case study groundwater contamination in Bonab Industrial Estate (Zanjan-Iran for iron, cobalt, nickel, copper, zinc, cadmium and lead content was investigated using differential pulse polarography (DPP. Although, cobalt, copper and zinc were found correspondingly in 47.8%, 100.0%, and 100.0% of the samples, they did not contain these metals above their maximum contaminant levels (MCLs. Cadmium was detected in 65.2% of the samples and 17.4% of them were polluted by this metal. All samples contained detectable levels of lead and iron with 8.7% and 13.0% of the samples higher than their MCLs. Nickel was also found in 78.3% of the samples, out of which 8.7% were polluted. In general, the results revealed the contamination of groundwater sources in the studied zone. The higher health risks are related to lead, nickel, and cadmium ions. Multivariate statistical techniques were applied for interpreting the experimental data and giving a description for the sources. The data analysis showed correlations and similarities between investigated heavy metals and helps to classify these ion groups. Cluster analysis identified five clusters among the studied heavy metals. Cluster 1 consisted of Pb, Cu, and cluster 3 included Cd, Fe; also each of the elements Zn, Co and Ni was located in groups with single member. The same results were obtained by factor analysis. Statistical investigations revealed that anthropogenic factors and notably lead and zinc plant and pedo-geochemical pollution sources are influencing water quality in the studied area.

  10. Multivariate statistical assessment of heavy metal pollution sources of groundwater around a lead and zinc plant.

    Zamani, Abbas Ali; Yaftian, Mohammad Reza; Parizanganeh, Abdolhossein

    2012-12-17

    The contamination of groundwater by heavy metal ions around a lead and zinc plant has been studied. As a case study groundwater contamination in Bonab Industrial Estate (Zanjan-Iran) for iron, cobalt, nickel, copper, zinc, cadmium and lead content was investigated using differential pulse polarography (DPP). Although, cobalt, copper and zinc were found correspondingly in 47.8%, 100.0%, and 100.0% of the samples, they did not contain these metals above their maximum contaminant levels (MCLs). Cadmium was detected in 65.2% of the samples and 17.4% of them were polluted by this metal. All samples contained detectable levels of lead and iron with 8.7% and 13.0% of the samples higher than their MCLs. Nickel was also found in 78.3% of the samples, out of which 8.7% were polluted. In general, the results revealed the contamination of groundwater sources in the studied zone. The higher health risks are related to lead, nickel, and cadmium ions. Multivariate statistical techniques were applied for interpreting the experimental data and giving a description for the sources. The data analysis showed correlations and similarities between investigated heavy metals and helps to classify these ion groups. Cluster analysis identified five clusters among the studied heavy metals. Cluster 1 consisted of Pb, Cu, and cluster 3 included Cd, Fe; also each of the elements Zn, Co and Ni was located in groups with single member. The same results were obtained by factor analysis. Statistical investigations revealed that anthropogenic factors and notably lead and zinc plant and pedo-geochemical pollution sources are influencing water quality in the studied area.

  11. Lead content of dried films of domestic paints currently sold in Nigeria

    Adebamowo, Eugenious O.; Scott Clark, C.; Roda, Sandy; Agbede, Oluwole A.; Sridhar, Mynepalli K.C.; Adebamowo, Clement A.

    2007-01-01

    Children are at higher risk from lead exposure because their developing neural system is susceptible to its neurotoxic effects. We studied lead levels of paints manufactured in Nigeria in 2006. Lead levels in 5 colors of paints, each from different manufacturers were measured using flame-atomic absorption spectroscopy. We found that 96% of the paints had higher than recommended levels of lead. The mean lead level of paints ranged from 84.8 to 50,000 ppm, with mean of 14,500 ppm and median of 15,800 ppm. The main determinant of lead levels was color of the paint. As lead levels in paint sold in the past years in Nigeria are likely to be at least as high as that currently sold, it is likely that many existing houses contain dangerously high levels of lead. Efforts need to be undertaken to assess the presence of high lead levels in existing housing and if detected, intervention programs for eliminating risk of exposure should be developed in addition to measures to increase awareness and enforce regulations leading to the elimination of lead based domestic paint

  12. Composite materials with metal oxide attached to lead chalcogenide nanocrystal quantum dots with linkers

    Fuke, Nobuhiro; Koposov, Alexey Y; Sykora, Milan; Hoch, Laura

    2014-12-16

    Composite materials useful for devices such as photoelectrochemical solar cells include a substrate, a metal oxide film on the substrate, nanocrystalline quantum dots (NQDs) of lead sulfide, lead selenide, and lead telluride, and linkers that attach the NQDs to the metal oxide film. Suitable linkers preserve the 1s absorption peak of the NQDs. A suitable linker has a general structure A-B-C where A is a chemical group adapted for binding to a MO.sub.x and C is a chemical group adapted for binding to a NQD and B is a divalent, rigid, or semi-rigid organic spacer moiety. Other linkers that preserve the 1s absorption peak may also be used.

  13. Towards a 20 kA high temperature superconductor current lead module using REBCO tapes

    Heller, R.; Bagrets, N.; Fietz, W. H.; Gröner, F.; Kienzler, A.; Lange, C.; Wolf, M. J.

    2018-01-01

    Most of the large fusion devices presently under construction or in operation consisting of superconducting magnets like EAST, Wendelstein 7-X (W7-X), JT-60SA, and ITER, use high temperature superconductor (HTS) current leads (CL) to reduce the cryogenic load and operational cost. In all cases, the 1st generation HTS material Bi-2223 is used which is embedded in a low-conductivity matrix of AgAu. In the meantime, industry worldwide concentrates on the production of the 2nd generation HTS REBCO material because of the better field performance in particular at higher temperature. As the new material can only be produced in a multilayer thin-film structure rather than as a multi-filamentary tape, the technology developed for Bi-2223-based current leads cannot be transferred directly to REBCO. Therefore, several laboratories are presently investigating the design of high current HTS current leads made of REBCO. Karlsruhe Institute of Technology is developing a 20 kA HTS current lead using brass-stabilized REBCO tapes—as a further development to the Bi-2223 design used in the JT-60SA current leads. The same copper heat exchanger module as in the 20 kA JT-60SA current lead will be used for simplicity, which will allow a comparison of the newly developed REBCO CL with the earlier produced and investigated CL for JT-60SA. The present paper discusses the design and accompanying test of single tape and stack REBCO mock-ups. Finally, the fabrication of the HTS module using REBCO stacks is described.

  14. A circulating loop tester for liquid alloyed metal of lead-bismuth

    Kitano, Teruaki; Ono, Mikinori; Kamata, Kinya

    2002-01-01

    Mitsui Engineering and Shipbuilding Co., Ltd. (MES) had focused to merits of this lead-bismuth alloy, to actively carry out many works on this field such as an experience of development of heat exchanger at industrial level of intercourse with IPPE (Institute of Physics and Power Engineering) in Russia with an experience of using results for 80 years on coolant for nuclear reactor. Before about 20 years, MES developed a heat exchanger for installation at a lead-zinc separation process in a refinery in Japan under cooperation of the Mitsui Metal and Mine Co., Ltd., to deliver it for a power generation system at the Hachinohe refinery. As the heat exchanger aims at control of cooling in the separation process, it also contributes to power generation of about 4,300 kW, and now it continues to separate and contribute to self-power generation in the refinery. The heat exchanger is filled with the liquid alloyed metal of lead-bismuth for an intermediate thermal medium in its casing. The metal has some merits such as inactivity to air and water, high boiling point (1,700 centigrade), almost no volume change at its coagulation, and its minus reactivity coefficient. However, the metal has some problems to be solved, such as its steel corrosion, its purification, and control technology. To grow up lead-bismuth technology to a nuclear energy technology in Japan, the lead-bismuth circulating loop tester was produced on May, 2001, to establish application technology on this system to nuclear energy technology in Japan. (G.K.)

  15. Series Production of 13 kA Current Leads with Dry and Compact Warm Terminals

    Andersen, T P; Vullierme, B

    2005-01-01

    For the LHC magnet test benches 13 pairs of conventional helium vapour-cooled 13 kA current leads are required. The current leads have been designed and built by industry. Attention was given to economical and reliable design and to a design of the warm terminal in order to avoid any condensation. Three pairs of them were tested at CERN. The dry warm terminal enables voltage test at 4.1 kV at cold condition. The paper describes construction details and compares calculated and measured values of the main parameters.

  16. Multiple lead seal assembly for a liquid-metal-cooled fast-breeder nuclear reactor

    Hutter, E.; Pardini, J.A.

    1977-01-01

    A reusable multiple lead seal assembly provides leak-free passage of stainless-steel-clad instrument leads through the cover on the primary tank of a liquid-metal-cooled fast-breeder nuclear reactor. The seal isolates radioactive argon cover gas and sodium vapor within the primary tank from the exterior atmosphere and permits reuse of the assembly and the stainless-steel-clad instrument leads. Leads are placed in flutes in a seal body, and a seal shell is then placed around the seal body. Circumferential channels in the body and inner surface of the shell are contiguous and together form a conduit which intersects each of the flutes, placing them in communication with a port through the wall of the seal shell. Liquid silicone rubber sealant is injected into the flutes through the port and conduit; the sealant fills the space in the flutes not occupied by the leads themselves and dries to a rubbery hardness. A nut, threaded onto a portion of the seal body not covered by the seal shell, jacks the body out of the shell and shears the sealant without damage to the body, shell, or leads. The leads may then be removed from the body. The sheared sealant is cleaned from the body, leads, and shell and the assembly may then be reused with the same or different leads. 3 claims, 6 figures

  17. Lead (Pb) and other metals in New York City community garden soils: factors influencing contaminant distributions.

    Mitchell, Rebecca G; Spliethoff, Henry M; Ribaudo, Lisa N; Lopp, Donna M; Shayler, Hannah A; Marquez-Bravo, Lydia G; Lambert, Veronique T; Ferenz, Gretchen S; Russell-Anelli, Jonathan M; Stone, Edie B; McBride, Murray B

    2014-04-01

    Urban gardens provide affordable fresh produce to communities with limited access to healthy food but may also increase exposure to lead (Pb) and other soil contaminants. Metals analysis of 564 soil samples from 54 New York City (NYC) community gardens found at least one sample exceeding health-based guidance values in 70% of gardens. However, most samples (78%) did not exceed guidance values, and medians were generally below those reported in NYC soil and other urban gardening studies. Barium (Ba) and Pb most frequently exceeded guidance values and along with cadmium (Cd) were strongly correlated with zinc (Zn), a commonly measured nutrient. Principal component analysis suggested that contaminants varied independently from organic matter and geogenic metals. Contaminants were associated with visible debris and a lack of raised beds; management practices (e.g., importing uncontaminated soil) have likely reduced metals concentrations. Continued exposure reduction efforts would benefit communities already burdened by environmental exposures. Copyright © 2014 Elsevier Ltd. All rights reserved.

  18. Lead (Pb) and other metals in New York City community garden soils: factors influencing contaminant distributions

    Mitchell, Rebecca G.; Spliethoff, Henry M.; Ribaudo, Lisa N.; Lopp, Donna M.; Shayler, Hannah A.; Marquez-Bravo, Lydia G.; Lambert, Veronique T.; Ferenz, Gretchen S.; Russell-Anelli, Jonathan M.; Stone, Edie B.; McBride, Murray B.

    2014-01-01

    Urban gardens provide affordable fresh produce to communities with limited access to healthy food but may also increase exposure to lead (Pb) and other soil contaminants. Metals analysis of 564 soil samples from 54 New York City (NYC) community gardens found at least one sample exceeding health-based guidance values in 70% of gardens. However, most samples (78%) did not exceed guidance values, and medians were generally below those reported in NYC soil and other urban gardening studies. Barium (Ba) and Pb most frequently exceeded guidance values and along with cadmium (Cd) were strongly correlated with zinc (Zn), a commonly measured nutrient. Principal component analysis suggested that contaminants varied independently from organic matter and geogenic metals. Contaminants were associated with visible debris and a lack of raised beds; management practices (e.g., importing uncontaminated soil) have likely reduced metals concentrations. Continued exposure reduction efforts would benefit communities already burdened by environmental exposures. PMID:24502997

  19. Study of the contamination of forages and legumes by lead and heavy metals

    Delcarte, E; Impens, R; Kirchmann, R; Nangniot, P; Fagniart, E

    1975-01-01

    A description of the methods used by the authors for their study of contamination of the environment and of the food chain by heavy metals is presented with particular reference to lead, cadmium and zinc. The first phase consists of taking samples, in industrial and urban areas and in the vicinity of highways, of soil and various common plants, including Plantago major L. (greater plantain), Ligustrum sp. (privet), Trifolium repens L. (white clover) and Tussilago farfara L. (coltsfoot). Concentrations of metal substances in these samples are measured by means of oscillopolarography at a set voltage. Risk areas are thus demarcated where fodder, vegetable and fruit samples are taken regularly throughout the vegetation period. A watch is kept on the progress and extent of Zn, Cd, Pb, Ni, Co and Cu fall-out in vegetable gardens and orchards in the vicinity of smelters in the Meuse valley. The results are compared with those obtained in the suburbs of Brussels near highway intersections and in a control area, away from any source of pollution. These results reveal that there is a serious risk of chronic poisoning in human beings and animals which feed on contaminated plants. Parallel laboratory tests are being carried out on the absorption, retention and toxicity of these metal substances in plants. The results obtained using stable lead and /sup 210/lead in Zea mays L. (maize) are discussed. Finally, dairy cattle are being experimentally fed on fodder which has been artificially enriched with stable lead and /sup 210/lead. The aim is to calculate the rate of alimentary lead transfer to the milk, urine and feces.

  20. Atomic structures and covalent-to-metallic transition of lead clusters Pbn (n=2-22)

    Wang Baolin; Zhao Jijun; Chen Xiaoshuang; Shi Daning; Wang Guanghou

    2005-01-01

    The lowest-energy structures and electronic properties of the lead clusters are studied by density-functional-theory calculations with Becke-Lee-Yang-Parr gradient correction. The lowest-energy structures of Pb n (n=2-22) clusters are determined from a number of structural isomers, which are generated from empirical genetic algorithm simulations. The competition between atom-centered compact structures and layered stacking structures leads to the alternative appearance of the two types of structures as global minimum. The size evolution of geometric and electronic properties from covalent bonding towards bulk metallic behavior in Pb clusters is discussed

  1. Enhanced interfacial thermal transport in pnictogen tellurides metallized with a lead-free solder alloy

    Devender,; Ramanath, Ganpati, E-mail: Ramanath@rpi.edu [Department of Materials Science and Engineering, Rensselaer Polytechnic Institute, Troy, New York 12180 (United States); Lofgreen, Kelly; Devasenathipathy, Shankar; Swan, Johanna; Mahajan, Ravi [Intel Corporation, Assembly Test and Technology Development, Chandler, Arizona 85226 (United States); Borca-Tasciuc, Theodorian [Department of Mechanical Aerospace and Nuclear Engineering, Rensselaer Polytechnic Institute, Troy, New York 12180 (United States)

    2015-11-15

    Controlling thermal transport across metal–thermoelectric interfaces is essential for realizing high efficiency solid-state refrigeration and waste-heat harvesting power generation devices. Here, the authors report that pnictogen chalcogenides metallized with bilayers of Sn{sub 96.5}Ag{sub 3}Cu{sub 0.5} solder and Ni barrier exhibit tenfold higher interfacial thermal conductance Γ{sub c} than that obtained with In/Ni bilayer metallization. X-ray diffraction and x-ray spectroscopy indicate that reduced interdiffusion and diminution of interfacial SnTe formation due to Ni layer correlates with the higher Γ{sub c}. Finite element modeling of thermoelectric coolers metallized with Sn{sub 96.5}Ag{sub 3}Cu{sub 0.5}/Ni bilayers presages a temperature drop ΔT ∼ 22 K that is 40% higher than that obtained with In/Ni metallization. Our results underscore the importance of controlling chemical intermixing at solder–metal–thermoelectric interfaces to increase the effective figure of merit, and hence, the thermoelectric cooling efficiency. These findings should facilitate the design and development of lead-free metallization for pnictogen chalcogenide-based thermoelectrics.

  2. Investigation of heavy metals (Cadmium, Lead in Chironomidae and Gammarus pulex Namrood River – Tehran Province

    Rezaei M. Kamali A. and Shapoori M.

    2012-01-01

    Full Text Available Marine ecosystem pollution is one of the important problems of today environment. In this study the existence of heavy metal in the Namrood River, situated in Firoozkooh in Tehran province, Iran has been investigated. The Namrood River is located near Firoozkooh route, and is affected by pollutant from tourist centers, entertainment, gas stations, nearby villages’ sewage systems, farming effluent, and hatchery farms. In some areas, its water is heavily polluted possibly by heavy metals. After selecting two stations in upstream and downstream of the river, they were sampled three times in both cold and hot seasons of year (mid-March, and June for Chironomidae, and Gammarus plux sediments. The measured heavy metals were cadmium and lead. The results showed that the concentration of cadmium in measured samples varied from 0.010-0.2033 ppm. The concentration of lead in samples varied from 0.11-2.16 ppm. The results also indicated that sediments of samples taken from the upper station in the cold season had a higher proportion of cadmium and a higher concentration of lead  than  sediments in the lower station during the hot season.

  3. Experimental and analytical investigation on metal damage suffered from simulated lightning currents

    Yakun, LIU; Zhengcai, FU; Quanzhen, LIU; Baoquan, LIU; Anirban, GUHA

    2017-12-01

    The damage of two typical metal materials, Al alloy 3003 and steel alloy Q235B, subjected to four representative lightning current components are investigated by laboratory and analytical studies to provide fundamental data for lightning protection. The four lightning components simulating the natural lightning consist of the first return stroke, the continuing current of interval stroke, the long continuing current, and the subsequent stroke, with amplitudes 200 kA, 8 kA, 400 A, and 100 kA, respectively. The damage depth and area suffered from different lightning components are measured by the ultrasonic scanning system. And the temperature rise is measured by the thermal imaging camera. The results show that, for both Al 3003 and steel Q235B, the first return stroke component results in the largest damage area with damage depth 0.02 mm uttermost. The long continuing current component leads to the deepest damage depth of 3.3 mm for Al 3003 and much higher temperature rise than other components. The correlation analysis between damage results and lightning parameters indicates that the damage depth has a positive correlation with charge transfer. The damage area is mainly determined by the current amplitude and the temperature rise increases linearly with the charge transfer larger.

  4. Quench propagation in High Temperature Superconducting materials integrated in high current leads

    Milani, D

    2001-01-01

    High temperature superconductors (HTS) have been integrated in the high current leads for the Large Hadron Collider (LHC), under construction at CERN, in order to reduce the heat leak into the liquid helium bath due to the joule effect. The use of the HTS technology in the lower part of the current leads allowed to significantly reduce the heat charge on the cryogenic system. Hybrid current leads have been designed to fulfill the LHC requirements with respect to thermal load; several tests have been performed to study the lead behavior especially during a quench transient. Quench experiments have been performed at CERN on 13 kA prototypes to determine the adequate design and protection. In all the tests it is possible to know the temperature profile of the HTS only with the help of quench simulations that model the thermo-hydraulic processes during quench. The development of a theoretical model for the simulation allows reducing the number of test to perform and to scale the experimental result to other curre...

  5. Bi2212 HTS Tubular Bulk with Conical Shape for Current Lead

    Tamura, H; Mito, T; Yamada, Y; Watanabe, M; Ohkubo, J; Heller, R

    2006-01-01

    Current leads using HTS material have been developed for application in a large scale superconducting magnet system. Tokai University and NIFS have developed Bi2212 tubular bulk which was prepared by a diffusion process. 8 kA of maximum transport current was achieved by a tubular bulk with a cylindrical shape. The maximum current was estimated to be 2 kA at 50 K for this tubular bulk. A current lead can be designed with this bulk the warm end of the HTS part being at 50 K and the cold end at 4.2 K. Under this condition, the cross section of the cold end of the bulk can be reduced. This type of HTS bulk has a great potential for flexible design since the Bi2212 layer can be reacted on the surface of any shapes of substrate. If a conical shaped HTS bulk was made, it could be an advantage for heat leakage to the cold end. To confirm this effect, we have made two types of conical bulk. The transport current of the specimen exceeds 7 kA at 4.2 K and 4 kA of stable current flow was achieved with a warm end temperature of 50 K

  6. Potential Of Microalgae Chlorella vulgaris As Bioremediation Agents of Heavy Metal Pb (Lead On Culture Media

    Rita Sulistya Dewi Endah

    2018-01-01

    Full Text Available The purpose of this study to determine the ability of Chlorella vulgaris in absorbing Pb (lead and the effect of the variation of Pb metal concentration on the growth of Chlorella vulgaris.This study using an experimental study with complete random design with 4 treatments, namely control (without the addition of metal, Pb1 (addition of metal 1 mg / l, Pb3 (3 mg / l and Pb5 (5 mg / l, respectively 3 replications. Exposure Pb ion in Chlorella vulgaris for 7 days. Analysis of the metal content of Pb concentration performed on culture media after exposure it at 3 hours after dispersion Chlorella vulgaris and on day 7 of culture using the AAS method. Do also counting the growth of cells each day. The results of the analysis of the average metal content of Pb in the culture medium at the end of the study was the control (0.1980, Pb1 (0.1453, Pb3 (0.4144 and Pb5 (0.5305. While the average growth of Chlorella vulgaris at the end of the study were control (630.1116 x 104, Pb1 (829.0012 x 104, Pb3 (1069.9446 x 104 and Pb 5 (808.94450 x 104. The results of the analysis of the content of Pb in the F test shown that the difference in concentration of water Pb given real influence on the ability of Chlorella vulgaris in absorbing Pb and growth. The conclusion of this study was Chlorella vulgaris has the ability to absorb metals in the waters, and the provision of various concentrations of Pb can affect the growth of Chlorella vulgaris.

  7. Potential Of Microalgae Chlorella vulgaris As Bioremediation Agents of Heavy Metal Pb (Lead) On Culture Media

    Dewi, Endah Rita Sulistya; Nuravivah, Riza

    2018-02-01

    The purpose of this study to determine the ability of Chlorella vulgaris in absorbing Pb (lead) and the effect of the variation of Pb metal concentration on the growth of Chlorella vulgaris.This study using an experimental study with complete random design with 4 treatments, namely control (without the addition of metal), Pb1 (addition of metal 1 mg / l), Pb3 (3 mg / l) and Pb5 (5 mg / l), respectively 3 replications. Exposure Pb ion in Chlorella vulgaris for 7 days. Analysis of the metal content of Pb concentration performed on culture media after exposure it at 3 hours after dispersion Chlorella vulgaris and on day 7 of culture using the AAS method. Do also counting the growth of cells each day. The results of the analysis of the average metal content of Pb in the culture medium at the end of the study was the control (0.1980), Pb1 (0.1453), Pb3 (0.4144) and Pb5 (0.5305). While the average growth of Chlorella vulgaris at the end of the study were control (630.1116 x 104), Pb1 (829.0012 x 104), Pb3 (1069.9446 x 104) and Pb 5 (808.94450 x 104). The results of the analysis of the content of Pb in the F test shown that the difference in concentration of water Pb given real influence on the ability of Chlorella vulgaris in absorbing Pb and growth. The conclusion of this study was Chlorella vulgaris has the ability to absorb metals in the waters, and the provision of various concentrations of Pb can affect the growth of Chlorella vulgaris.

  8. Thermo-mechanical tests on W7-X current lead flanges

    Dhard, Chandra Prakash; Rummel, Thomas; Zacharias, Daniel; Bykov, Victor; Moennich, Thomas; Buscher, Klaus-Peter

    2013-01-01

    Highlights: • There are significant mechanical loads on the cryostat and radial flanges for W7-X current leads. • These are due to evacuation of W7-X cryostat, cool-down of cold mass, electro-magnetic forces and self weight of leads. • The actual mechanical loads were reduced to simplify the experimental set-up. • The tests were carried out on mock-up flanges test assembly at ambient temperature and at 77 K. • The thermo-mechanical tests on W7-X current lead flanges validate the design and joints of these flanges to the leads. -- Abstract: Fourteen pieces of high temperature superconducting current leads (CL) arranged in seven pairs, will be installed on the outer vessel of Wendelstein 7-X (W7-X) stellarator. In order to support the CL, it is provided with two glass fiber reinforce plastic (GFRP) flanges, namely, the lower cryostat flange (CF) remaining at room temperature and upper radial flange (RF) at about 5 K. Both the flanges i.e. CF and RF experience high mechanical loads with respect to the CL, due to the evacuation of W7-X cryostat, cool-down of cold mass including the CL, electro-magnetic forces due to current and plasma operations and self weight of CL. In order to check the integrity of these flanges for such mechanical loads, thermo-mechanical tests were carried out on these flanges at room temperatures and at liquid nitrogen (LN2) temperatures. The details of test set-up, results and modeling are described in the paper

  9. Development of modular thermostatic vapour-cooled current leads for cryogenic service

    Blessing, H.; Lebrun, P.

    1983-01-01

    Cryogenic current leads cooled by helium vapour have been developed, built and tested. Their construction, based on standard electrolytic copper braids crimped at the ends, is such as to provide flexible cold terminations and make possible a modular design. The warm terminations combine electrical insulation, leak-tightness and integrated thermostatic valves controlling lead temperature and avoiding thermal run-away or ice build-up. After giving a detailed description of their construction, this report presents results of performance and reliability tests made on prototype units. (orig.)

  10. Report on results of current and future metal casting

    Unal, Cetin; Carlson, Neil N.

    2015-01-01

    New modeling capabilities needed to simulate the casting of metallic fuels are added to Truchas code. In this report we summarize improvements we made in FY2015 in three areas; (1) Analysis of new casting experiments conducted with BCS and EFL designs, (2) the simulation of INL's U-Zr casting experiments with Flow3D computer program, (3) the implementation of surface tension model into Truchas for unstructured mesh required to run U-Zr casting.

  11. Thermochemistry of some binary lead and transition metal compounds by high temperature direct synthesis calorimetry

    Meschel, S.V., E-mail: meschel@jfi.uchicago.edu [Illinois Institute of Technology,Thermal Processing Technology Center, 10 W. 32nd Street, Chicago, Illinois 60615 (United States); Gordon Center for Integrated Science, 929 E. 57th Street, Chicago, Illinois 60637 (United States); Nash, P. [Illinois Institute of Technology,Thermal Processing Technology Center, 10 W. 32nd Street, Chicago, Illinois 60615 (United States); Chen, X.Q.; Wei, P. [Materials processing Modeling Division, Shenyang National Laboratory for Materials Science, Institute of Metals Research, 72 Wenhua Road, Shenyang City (China)

    2015-06-05

    Highlights: • Studied binary lead-transition metal alloys by high temperature calorimetry. • Determined the enthalpies of formation of 8 alloys. • Compared the measurements with predictions by the model of Miedema and by the ab initio method. - Abstract: The standard enthalpies of formation of some binary lead and transition metal compounds have been measured by high temperature direct synthesis calorimetry. The reported results are: Pb{sub 3}Sc{sub 5}(−61.3 ± 2.9); PbTi{sub 4}(−16.6 ± 2.4); Pb{sub 3}Y{sub 5}(−64.8 ± 3.6); Pb{sub 3}Zr{sub 5}(−50.6 ± 3.1); PbNb{sub 3}(−10.4 ± 3.4); PbRh(−16.5 ± 3.3); PbPd{sub 3}(−29.6 ± 3.1); PbPt(−34.7 ± 3.3) kJ/mole of atoms. We will compare our results with previously published measurements. We will also compare the experimental measurements with enthalpies of formation of transition metal compounds with elements in the same vertical column in the periodic table. We will compare our measurements with predicted values on the basis of the semi empirical model of Miedema and coworkers and with ab initio values when available.

  12. How to control spin-Seebeck current in a metal-quantum dot-magnetic insulator junction

    Fu, Hua-Hua; Gu, Lei; Wu, Ruqian

    The control of the spin-Seebeck current is still a challenging task for the development of spin caloritronic devices. Here, we construct a spin-Seebeck device by inserting a quantum dot (QD) between the metal lead and magnetic insulator. Using the slave-particle approach and noncrossing approximation, we find that the spin-Seebeck effect increases significantly when the energy level of the QD locates near the Fermi level of the metal lead due to the enhancement of spin flipping and occurrences of quantum resonance. Since this can be easily realized by applying a gate voltage in experiments, the spin-Seebeck device proposed here can also work as a thermovoltaic transistor. Moreover, the optimal correlation strength and the energy level position of the QD are discussed to maximize the spin-Seebeck current as required for applications in controllable spin caloritronic devices.

  13. Accumulation of heavy metals in plants and potential phytoremediation of lead by potato, Solanum tuberosum L.

    Antonious, George F; Snyder, John C

    2007-05-01

    The use of sewage sludge as a source of nutrients in crop production is increasing in the United States and worldwide. A field study was conducted on a 10% slope at Kentucky State University Research Farm. Eighteen plots of 22x3.7 m each were separated using metal borders and the soil in six plots was mixed with sewage sludge, six plots were mixed with yard waste compost, and six unamended plots were used for comparison purposes. During a subsequent 3-year study, plots were planted with potato (year 1), pepper (year 2), and broccoli (year 3). The objectives of this investigation were to: (i) characterize chemical properties of soil-incorporated sewage sludge and yard waste compost; (ii) determine the concentration of seven heavy metals (Cd, Cr, Ni, Pb, Zn, Cu, and Mo) in sewage sludge and yard waste compost used for land farming; and (iii) monitor heavy metal concentrations in edible portions of plants at harvest. Concentrations of heavy metals in sewage sludge were below the U.S. EPA limits. Analysis of potato tubers, peppers, and broccoli grown in sludge-amended soil showed that Cd, Cr, Ni, and Pb were not significantly different from control plants. Concentrations of Zn, Cu, and Mo were significantly greater in tubers and peppers grown in sludge compared to their respective controls. Zn and Mo in broccoli heads were higher than their control plants. The ability of potato to accumulate lead needs additional investigation to optimize the phytoremediation of this pollutant element.

  14. Imprinted Genes and the Environment: Links to the Toxic Metals Arsenic, Cadmium and Lead

    Lisa Smeester

    2014-06-01

    Full Text Available Imprinted genes defy rules of Mendelian genetics with their expression tied to the parent from whom each allele was inherited. They are known to play a role in various diseases/disorders including fetal growth disruption, lower birth weight, obesity, and cancer. There is increasing interest in understanding their influence on environmentally-induced disease. The environment can be thought of broadly as including chemicals present in air, water and soil, as well as food. According to the Agency for Toxic Substances and Disease Registry (ATSDR, some of the highest ranking environmental chemicals of concern include metals/metalloids such as arsenic, cadmium, lead and mercury. The complex relationships between toxic metal exposure, imprinted gene regulation/expression and health outcomes are understudied. Herein we examine trends in imprinted gene biology, including an assessment of the imprinted genes and their known functional roles in the cell, particularly as they relate to toxic metals exposure and disease. The data highlight that many of the imprinted genes have known associations to developmental diseases and are enriched for their role in the TP53 and AhR pathways. Assessment of the promoter regions of the imprinted genes resulted in the identification of an enrichment of binding sites for two transcription factor families, namely the zinc finger family II and PLAG transcription factors. Taken together these data contribute insight into the complex relationships between toxic metals in the environment and imprinted gene biology.

  15. Imprinted Genes and the Environment: Links to the Toxic Metals Arsenic, Cadmium and Lead

    Smeester, Lisa; Yosim, Andrew E.; Nye, Monica D.; Hoyo, Cathrine; Murphy, Susan K.; Fry, Rebecca C.

    2014-01-01

    Imprinted genes defy rules of Mendelian genetics with their expression tied to the parent from whom each allele was inherited. They are known to play a role in various diseases/disorders including fetal growth disruption, lower birth weight, obesity, and cancer. There is increasing interest in understanding their influence on environmentally-induced disease. The environment can be thought of broadly as including chemicals present in air, water and soil, as well as food. According to the Agency for Toxic Substances and Disease Registry (ATSDR), some of the highest ranking environmental chemicals of concern include metals/metalloids such as arsenic, cadmium, and lead. The complex relationships between toxic metal exposure, imprinted gene regulation/expression and health outcomes are understudied. Herein we examine trends in imprinted gene biology, including an assessment of the imprinted genes and their known functional roles in the cell, particularly as they relate to toxic metals exposure and disease. The data highlight that many of the imprinted genes have known associations to developmental diseases and are enriched for their role in the TP53 and AhR pathways. Assessment of the promoter regions of the imprinted genes resulted in the identification of an enrichment of binding sites for two transcription factor families, namely the zinc finger family II and PLAG transcription factors. Taken together these data contribute insight into the complex relationships between toxic metals in the environment and imprinted gene biology. PMID:24921406

  16. Imprinted genes and the environment: links to the toxic metals arsenic, cadmium, lead and mercury.

    Smeester, Lisa; Yosim, Andrew E; Nye, Monica D; Hoyo, Cathrine; Murphy, Susan K; Fry, Rebecca C

    2014-06-11

    Imprinted genes defy rules of Mendelian genetics with their expression tied to the parent from whom each allele was inherited. They are known to play a role in various diseases/disorders including fetal growth disruption, lower birth weight, obesity, and cancer. There is increasing interest in understanding their influence on environmentally-induced disease. The environment can be thought of broadly as including chemicals present in air, water and soil, as well as food. According to the Agency for Toxic Substances and Disease Registry (ATSDR), some of the highest ranking environmental chemicals of concern include metals/metalloids such as arsenic, cadmium, lead and mercury. The complex relationships between toxic metal exposure, imprinted gene regulation/expression and health outcomes are understudied. Herein we examine trends in imprinted gene biology, including an assessment of the imprinted genes and their known functional roles in the cell, particularly as they relate to toxic metals exposure and disease. The data highlight that many of the imprinted genes have known associations to developmental diseases and are enriched for their role in the TP53 and AhR pathways. Assessment of the promoter regions of the imprinted genes resulted in the identification of an enrichment of binding sites for two transcription factor families, namely the zinc finger family II and PLAG transcription factors. Taken together these data contribute insight into the complex relationships between toxic metals in the environment and imprinted gene biology.

  17. Heavy metal balances: Part I. General aspects of cadmium, copper, zinc and lead balance studies in agro-ecosystems

    Moolenaar, S.W.; Lexmond, T.M.

    1999-01-01

    The control of heavy metals in such a way that soil functioning and product quality are not impeded is a prerequisite to sustainable agriculture. The current status of heavy metal accumulation in agricultural soils differs widely by region, by metal, and by agricultural system; levels of concern

  18. 600 A HTc current lead based on BSCCO 2212 rods for LHC magnets

    García-Tabarés, L; Abramian, P; Toral, F; Angurel, L A; Diez, J C; Burriel, R; Natividad, E; Iturbe, R; Etxeandia, J

    2000-01-01

    A 600 A current lead using 2212 BSCCO bulk material is now under construction and will be soon delivered to CERN. Present paper describes the main steps of its design and fabrication, including the two main parts in which it is divided, the superconducting module with the BSCCO rods and the conventional resistive part. An important role in this design was played by previous experimental measurements on subassemblies, which are also described along the paper. (5 refs).

  19. Low flow velocity, fine-screen heat exchangers and vapor-cooled cryogenic current leads

    Steyert, W.A.; Stone, N.J.

    1978-09-01

    The design, construction, and testing of three compact, low temperature heat exchangers are reported. A method is given for the construction of a small (approximately = 20-cm 3 volume) exchanger that can handle 6 g/s helium flow with low pressure drops (ΔP/P = 10 percent) and adequate heat transfer (N/sub tu/ = 3). The use of screen for simple, vapor-cooled current leads into cryogenic systems is also discussed

  20. Single and combined metal contamination in coastal environments in China: current status and potential ecological risk evaluation.

    Manzoor, Romana; Zhang, Tingwan; Zhang, Xuejiao; Wang, Min; Pan, Jin-Fen; Wang, Zhumei; Zhang, Bo

    2018-01-01

    With the development of industrialization and urbanization, metal and metalloid pollution is one of the most serious environmental problems in China. Current contamination status of metals and metalloid and their potential ecological risks along China's coasts were reviewed in the present paper by a comprehensive study on metal contents in marine waters and sediments in the past few decades. The priority metals/metalloid cadmium (Cd), mercury (Hg), chromium (Cr), lead (Pb), and arsenic (As), which were the target elements of the designated project "Comprehensive Prevention and Control of Heavy Metal Pollution" issued by the Chinese government in 2011, were selected considering their high toxicity, persistence, and prevalent existence in coastal environment. Commonly used environmental quality evaluation methods for single and combined metals were compared, and we accordingly suggest the comprehensive approach of joint utilization of the Enrichment Factor and Effect Range Median combined with Pollution Load Index and Mean Effect Range Median Quotient (EEPME); this battery of guidelines may provide consistent, internationally comparable, and accurate understanding of the environment pollution status of combined metals/metalloid and their potential ecological risk.

  1. Optimization of a Two Stage Pulse Tube Refrigerator for the Integrated Current Lead System

    Maekawa, R.; Matsubara, Y.; Okada, A.; Takami, S.; Konno, M.; Tomioka, A.; Imayoshi, T.; Hayashi, H.; Mito, T.

    2008-03-01

    Implementation of a conventional current lead with a pulse tube refrigerator has been validated to be working as an Integrated Current Lead (ICL) system for the Superconducting Magnetic Energy Storage (SMES). Realization of the system is primarily accounted for the flexibility of a pulse tube refrigerator, which does not posses any mechanical piston and/or displacer. As for an ultimate version of the ICL system, a High Temperature Superconducting (HTS) lead links a superconducting coil with a conventional copper lead. To ensure the minimization of heat loads to the superconducting coil, a pulse tube refrigerator has been upgraded to have a second cooling stage. This arrangement reduces not only the heat loads to the superconducting coil but also the operating cost for a SMES system. A prototype two-stage pulse tube refrigerator, series connected arrangement, was designed and fabricated to satisfy the requirements for the ICL system. Operation of the first stage refrigerator is a four-valve mode, while the second stage utilizes a double inlet configuration to ensure its confined geometry. The paper discusses the optimization of second stage cooling to validate the conceptual design

  2. Current state of the absorbable metallic (magnesium) stent.

    Waksman, Ron

    2009-12-15

    BIOTRONIK's absorbable metal stent technology is based ona magnesium alloy that offers superior stent mechanics and biocompatibility. The first generation (AMS-1) showed promising results regarding mechanical properties as well as feasibility and safety in several human applications (150 cases). The second generation (AMS-2.1) shows improved scaffolding and efficacy in animals due to a more slowly degrading magnesium alloy and an optimised stent design. The preclinical results of the drug-eluting AMS-3 are encouraging and the clinical investigational program will resume in 2010.

  3. Study of electromagnetic interference on quench detecting system of HTS current leads for EAST

    Hu, Yanlan; Li, Jiangang; Ji, Zhenshan; Zhu, C.M.; Zhen, L.G.; Xiao, Y.Z.

    2013-01-01

    Highlights: • EAST HTS superconducting magnet system shall be operating in a very noisy environment. • Voltage taps will have a lot of inductive voltage induced on them which makes quench detection very difficult. • The noise comes from the coupling between rapid pulsed poloidal coils, and radiation coupling interference associated with EAST heating systems;. • A series of related electromagnetic compatibility simulation tests have been carried out. • Electromagnetic noises are well restrained by choosing proper anti-interference means. -- Abstract: High temperature superconducting (HTS) material B-2223/Ag-Au has been used for EAST poloidal field (PF) coil current leads for reducing construction and operation cost of cryogenic system. The quench propagation velocity of HTS superconducting material is several orders of magnitude lower than that of normal low temperature current leads. It is difficult to detect weak signal of quench which is easily influenced by strong electromagnetic interference (EMI). In this paper, the sources of EMI from quench detecting system of high temperature current leads have been introduced. And we have chosen reasonable methods for good transformation and protection on the basis of electromagnetic compatibility simulation diagnosis experiments. Recent experimental results showed that the restraint of EMI has been achieved and has met the requirements of experiment

  4. Complexity of MRI induced heating on metallic leads: Experimental measurements of 374 configurations

    Mendoza Gonzalo

    2008-03-01

    Full Text Available Abstract Background MRI induced heating on PM leads is a very complex issue. The widely varying results described in literature suggest that there are many factors that influence the degree of heating and that not always are adequately addressed by existing testing methods. Methods We present a wide database of experimental measurements of the heating of metallic wires and PM leads in a 1.5 T RF coil. The aim of these measurements is to systematically quantify the contribution of some potential factors involved in the MRI induced heating: the length and the geometric structure of the lead; the implant location within the body and the lead path; the shape of the phantom used to simulate the human trunk and its relative position inside the RF coil. Results We found that the several factors are the primary influence on heating at the tip. Closer locations of the leads to the edge of the phantom and to the edge of the coil produce maximum heating. The lead length is the other crucial factor, whereas the implant area does not seem to have a major role in the induced temperature increase. Also the lead structure and the geometry of the phantom revealed to be elements that can significantly modify the amount of heating. Conclusion Our findings highlight the factors that have significant effects on MRI induced heating of implanted wires and leads. These factors must be taken into account by those who plan to study or model MRI heating of implants. Also our data should help those who wish to develop guidelines for defining safe medical implants for MRI patients. In addition, our database of the entire set of measurements can help those who wish to validate their numerical models of implants that may be exposed to MRI systems.

  5. Metals in riparian wildlife of the lead mining district of southeastern Missouri. [Rana catesbeiana, Ondatra zibethicus; Butorides striatus; Nerodia sipedon; Stelgidopteryx serripennis, Riparia riparia

    Niethammer, K.R.; Atkinson, R.D.; Baskett, T.S.; Samson, F.B.

    1985-03-01

    Five species of riparian vertebrates (425 individuals) primarily representing upper trophic levels were collected from the Big River and Black River drainages in two lead mining districts of southeastern Missouri, 1981-82. Big River is subject to metal pollution via erosion and seepage from large tailings piles from inactive lead mines. Black River drains part of a currently mined area. Bull-frogs (Rana catesbeiana), muskrats (Ondatra zibethicus), and green-backed herons (Butorides striatus) collected downstream from the source of metal contamination to Big River had significantly higher lead and cadmium levels than specimens collected at either an uncontaminated upstream site or on Black River. Northern water snakes (Nerodia sipedon) had elevated lead levels below the tailings source, but did not seem to accumulate cadmium. Levels of lead, cadmium, or zinc in northern rough-winged swallows (Stelgidopteryx serripennis) were not related to collecting locality. Carcasses of ten bank swallows (Riparia riparia) collected from a colony nesting in a tailings pile along the Big River had lead concentrations of 2.0-39 ppm wet weight. Differences between zinc concentrations in vertebrates collected from contaminated and uncontaminated sites were less apparent than differences in lead and cadmium. There was little relationship between metal concentrations in the animals studied and their trophic levels. Bull-frogs are the most promising species examined for monitoring environmental levels of lead, cadmium, and zinc.

  6. Eddy current probe and method for flaw detection in metals

    Watjen, John P.

    1987-06-23

    A flaw detecting system is shown which includes a probe having a pair of ferrite cores with in-line gaps in close proximity to each other. An insulating, non-magnetic, non-conducting holder fills the gaps and supports the ferrite cores in a manner such that the cores form a generally V-shape. Each core is provided with an excitation winding and a detection winding. The excitation windings are connected in series or parallel with an rf port for connection thereof to a radio frequency source. The detection windings, which are differentially wound, are connected in series circuit to a detector port for connection to a voltage measuring instrument. The ferrite cores at the in-line gaps directly engage the metal surface of a test piece, and the probe is scanned along the test piece. In the presence of a flaw in the metal surface the detection winding voltages are unbalanced, and the unbalance is detected by the voltage measuring instrument. The insulating holder is provided with a profile which conforms to that of a prominent feature of the test piece to facilitate movement of the probe along the feature, typically an edge or a corner.

  7. Transient current in a quantum dot subject to a change in coupling to its leads

    Izmaylov, A F; Goker, A; Friedman, B A; Nordlander, P

    2006-01-01

    The time-dependent non-crossing approximation is used to calculate the transient currents through a quantum dot in the Kondo regime subject to a sudden change in its coupling to the leads. The currents are found to display transient non-universal behaviour immediately after the perturbation and then to follow a slow universal increase toward equilibrium. The timescales for the approach to equilibrium are shown to be the same as those recently identified in a study of transient currents in a quantum dot subject to a sudden change in the energy of the dot level (Plihal et al 2005 Phys. Rev. B 71 165321). We present improved numerical algorithms which enable relatively fast calculation of the transient response of quantum dots to sudden perturbations

  8. Could persistency of current of injury forecast successful active-fixation pacing lead implantation?

    Shali, Shalaimaiti; Su, Yangang; Qin, Shengmei; Ge, Junbo

    2018-05-01

    Presence of adequate current of injury (COI) was recognized as a sign of favorable pacemaker lead outcome. Little is known regarding the value of its dynamic behavior. We sought to test whether persistency of COI could predict active-fixation pacing lead performance. COI was monitored up to 10min after right ventricular (RV) pacing electrode fixation. COI persistency was defined as the percentage of COI magnitude relative to its initial measurement. An unacceptable pacing threshold (≥1.0V in acute evaluation or ≥2.0V over 2-year follow-up) with or without lead dislodgement was considered as lead failure. Lead implantation was attempted for 217 times in 174 patients (age 66.3±7.8years, 78 female). Acute lead failures occurred 43 times. Independent predictors of acute lead failure were RV enlargement (odds ratio [OR] 1.23, 95% confidential interval [CI] 1.11-2.04, P=0.033), absence of COI (OR 3.13, 95%CI 2.08-9.09, P=0.027), and COI persistency at 5min (OR 0.32, 95%CI 0.20-0.69, P=0.001) and 10min (OR 0.41, 95%CI 0.13-0.77, P=0.001). The optimal cutoffs were COI 5min persistency ≥50% (sensitivity 81.4%; specificity 81.9%) and COI 10min persistency ≥20% (sensitivity 86%; specificity 88.6%). There were 12 lead failures during 24.0±6.4months of follow-up. Patients with COI 5min persistency ≥50% had higher event-free survival compared to those with COI 5min persistency <50% (hazard ratio 3.54, 95% CI 1.04-12.06, P=0.043). COI persistency appears to be a valuable indicator for both acute and long-term outcome of active-fixation pacemaker leads. A precipitous decline in COI may require more attention to make sure of the lead performance. Copyright © 2018 Elsevier Ireland Ltd. All rights reserved.

  9. Current-Voltage Characteristics of the Metal / Organic Semiconductor / Metal Structures: Top and Bottom Contact Configuration Case

    Šarūnas MEŠKINIS

    2013-03-01

    Full Text Available In present study five synthesized organic semiconductor compounds have been used for fabrication of the planar metal / organic semiconductor / metal structures. Both top electrode and bottom electrode configurations were used. Current-voltage (I-V characteristics of the samples were investigated. Effect of the hysteresis of the I-V characteristics was observed for all the investigated samples. However, strength of the hysteresis was dependent on the organic semiconductor used. Study of I-V characteristics of the top contact Al/AT-RB-1/Al structures revealed, that in (0 – 500 V voltages range average current of the samples measured in air is only slightly higher than current measured in nitrogen ambient. Deposition of the ultra-thin diamond like carbon interlayer resulted in both decrease of the hysteresis of I-V characteristics of top contact Al/AT-RB-1/Al samples. However, decreased current and decreased slope of the I-V characteristics of the samples with diamond like carbon interlayer was observed as well. I-V characteristic hysteresis effect was less pronounced in the case of the bottom contact metal/organic semiconductor/metal samples. I-V characteristics of the bottom contact samples were dependent on electrode metal used.DOI: http://dx.doi.org/10.5755/j01.ms.19.1.3816

  10. Bandgap Engineering of Lead-Free Double Perovskite Cs2 AgBiBr6 through Trivalent Metal Alloying.

    Du, Ke-Zhao; Meng, Weiwei; Wang, Xiaoming; Yan, Yanfa; Mitzi, David B

    2017-07-03

    The double perovskite family, A 2 M I M III X 6 , is a promising route to overcome the lead toxicity issue confronting the current photovoltaic (PV) standout, CH 3 NH 3 PbI 3 . Given the generally large indirect band gap within most known double perovskites, band-gap engineering provides an important approach for targeting outstanding PV performance within this family. Using Cs 2 AgBiBr 6 as host, band-gap engineering through alloying of In III /Sb III has been demonstrated in the current work. Cs 2 Ag(Bi 1-x M x )Br 6 (M=In, Sb) accommodates up to 75 % In III with increased band gap, and up to 37.5 % Sb III with reduced band gap; that is, enabling ca. 0.41 eV band gap modulation through introduction of the two metals, with smallest value of 1.86 eV for Cs 2 Ag(Bi 0.625 Sb 0.375 )Br 6 . Band structure calculations indicate that opposite band gap shift directions associated with Sb/In substitution arise from different atomic configurations for these atoms. Associated photoluminescence and environmental stability of the three-metal systems are also assessed. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. Bandgap engineering of lead-free double perovskite Cs_2AgBiBr_6 through trivalent metal alloying

    Du, Ke-zhao; Mitzi, David B.; Meng, Weiwei; Wang, Xiaoming; Yan, Yanfa

    2017-01-01

    The double perovskite family, A_2M"IM"I"I"IX_6, is a promising route to overcome the lead toxicity issue confronting the current photovoltaic (PV) standout, CH_3NH_3PbI_3. Given the generally large indirect band gap within most known double perovskites, band-gap engineering provides an important approach for targeting outstanding PV performance within this family. Using Cs_2AgBiBr_6 as host, band-gap engineering through alloying of In"I"I"I/Sb"I"I"I has been demonstrated in the current work. Cs_2Ag(Bi_1_-_xM_x)Br_6 (M=In, Sb) accommodates up to 75 % In"I"I"I with increased band gap, and up to 37.5 % Sb"I"I"I with reduced band gap; that is, enabling ca. 0.41 eV band gap modulation through introduction of the two metals, with smallest value of 1.86 eV for Cs_2Ag(Bi_0_._6_2_5Sb_0_._3_7_5)Br_6. Band structure calculations indicate that opposite band gap shift directions associated with Sb/In substitution arise from different atomic configurations for these atoms. Associated photoluminescence and environmental stability of the three-metal systems are also assessed. (copyright 2017 Wiley-VCH Verlag GmbH and Co. KGaA, Weinheim)

  12. Lead-210 and heavy metal contents in dated ombrotrophic peat hummocks from Finland

    El-Daoushy, F.; Tolonen, K.

    1984-01-01

    Two Sphagnum fuscum hummock cores, core 1, Kaerpaensuo bog and core F9, Kunonniemensuo bog. from Finland were used in this study. The peats are ombrotrophic and were dated using the moss-increment method. The mosses in both cores were carefully examined for their botanical composition, degree of humification, ash percentage and bulk density. The total accumulated dry peat-matter in the Kunonniemensuo core was almost double that in the Kaerpaensuo core. The total 210 Pb and the supported 210 Pb were measured by isotope dilution and the radon emanation technique. Materials in the same peat samples were analysed for their 210 Pb content at the Institute of Physics, Uppsala, Sweden and the Technical Research Centre of Finland, Espoo, Finland. The annual content of unsupported 210 Pb in the dated peat-layers shows that peat materials are effective traps which could yield information on atmospheric-fluxes both chronologically and regionally. Lead, copper, zinc, iron and manganese were also measured by flame atomic absorption spectrometry (AAS). The total accumulated amounts over the past 150 y of the heavy metals investigated are almost identical for both cores apart from manganese which is considerably higher in the Kunonniemensuo core. However, the metal profiles studied exhibit discontinuity zones more pronounced in the Kunonniemensuo core. The 210 Pb data indicate that growth rate and bulk density variations in ombrotrophic peat bogs affects the accumulation of 210 Pb and similar trace metals. (orig.)

  13. Electroplated reticulated vitreous carbon current collectors for lead-acid batteries: opportunities and challenges

    Gyenge, Elod; Jung, Joey; Mahato, Basanta

    Reticulated, open-cell structures based on vitreous carbon substrates electroplated with a Pb-Sn (1 wt.%) alloy were investigated as current collectors for lead-acid batteries. Scanning and backscattered electron microscopy, cyclic voltammetry, anodic polarization and flooded 2 V single-cell battery testing was employed to characterize the performance of the proposed collectors. A battery equipped with pasted electroplated reticulated vitreous carbon (RVC) electrodes of 137 cm 2 geometric area, at the time of manuscript submission, completed 500 cycles and over 1500 h of continuous operation. The cycling involved discharges at 63 A kg PAM-1 corresponding to a nominal 0.75 h rate and a positive active mass (PAM) utilization efficiency of 21%. The charging protocol was composed of two voltage limited (i.e. 2.6 V/cell), constant current steps of 35 and 9.5 A kg PAM-1, respectively, with a total duration of about 2 h. The charge factor was 1.05-1.15. The observed cycling behavior in conjunction with the versatility of electrodeposition to produce application-dependent optimized lead alloy coating thickness and composition shows promise for the development of lead-acid batteries using electroplated reticulated vitreous carbon collectors.

  14. Operational Experience and Consolidations for the Current Lead Control Valves of the Large Hadron Collider

    Perin, A; Pirotte, O; Krieger, B; Widmer, A

    2012-01-01

    The Large Hadron Collider superconducting magnets are powered by more than 1400 gas cooled current leads ranging from 120 A to 13000 A. The gas flow required by the leads is controlled by solenoid proportional valves with dimensions from DN 1.8 mm to DN 10 mm. During the first months of operation, signs of premature wear were found in the active parts of the valves. This created major problems for the functioning of the current leads threatening the availability of the LHC. Following the detection of the problems, a series of measures were implemented to keep the LHC running, to launch a development program to solve the premature wear problem and to prepare for a global consolidation of the gas flow control system. This article describes first the difficulties encountered and the measures taken to ensure a continuous operation of the LHC during the first year of operation. The development of new friction free valves is then presented along with the consolidation program and the test equipment developed to val...

  15. Pulse current gas metal arc welding characteristics, control and applications

    Ghosh, Prakriti Kumar

    2017-01-01

    This monograph is a first-of-its-kind compilation on high deposition pulse current GMAW process. The nine chapters of this monograph may serve as a comprehensive knowledge tool to use advanced welding engineering in prospective applications. The contents of this book will prove useful to the shop floor welding engineer in handling this otherwise critical welding process with confidence. It will also serve to inspire researchers to think critically on more versatile applications of the unique nature of pulse current in GMAW process to develop cutting edge welding technology.

  16. Eddy current testing device for metallic tubes at least locally curved

    Pigeon, Marcel; Vienot, Claude.

    1975-01-01

    Steam generators, condensers and heat exchangers generally consist of metallic tube bundles, the tubes having a complex geometry. The invention concerns an Eddy current testing device for metallic tubes at least locally curved, operating by translation of a probe inside the tubes [fr

  17. 75 FR 49527 - Metaldyne Corporation, Metaldyne Tubular Products, Currently Known as Flexible Metal, Inc...

    2010-08-13

    ..., Metaldyne Tubular Products, Currently Known as Flexible Metal, Inc., Powertrain Division, Hamburg, MI... certification for workers of the subject firm. The workers are engaged in the production of exhaust manifolds and turbo tubes for the automotive industry. Information shows that on June 10, 2010, Flexible Metals...

  18. Parameters promoting liquid metal embrittlement of the T91 steel in lead-bismuth eutectic alloy

    Proriol Serre, I.; Ye, C.; Vogt, J.B.

    2015-01-01

    The use of liquid lead-bismuth eutectic (LBE) as a spallation target and a coolant in accelerator-driven systems raises the question of the reliability of structural materials, such as T91 martensitic steel in terms of liquid metal assisted damage and corrosion. In this study, the mechanical behaviour of the T91 martensitic steel was examined in liquid lead-bismuth eutectic (LBE) and in inert atmosphere. Several conditions showed the most sensitive embrittlement factor. The Small Punch Test technique was employed using smooth specimens. In this standard heat treatment, T91 appeared in general as a ductile material, and became brittle in the considered conditions if the test was performed in LBE. It turns out that the loading rate appeared as a critical parameter for the occurrence of liquid metal embrittlement (LME) of the T91 steel in LBE. Loading the T91 very slowly instead of rapidly in oxygen saturated LBE resulted in brittle fracture. Furthermore, low-oxygen content in LBE and an increase in temperature promote LME. (authors)

  19. Kinetic study on recovery of metal values in anode slime from used lead batteries

    Itoh, S.; Nagasaka, T. [Tohoku Univ., Sendai (Japan). Dept. of Environmental Studies; Ono, J.; Hino, M. [Tohoku Univ., Sendai (Japan). Dept. of Metallurgy

    2004-07-01

    Oxidation experiments were conducted with pure antimony and antimony-lead bismuth alloys to examine the oxidation kinetics and mechanisms used to treat the anode slime produced during lead electrorefining and recovery of antimony from used lead batteries. In order to recycle and recover valuable metals from the used lead batteries, the oxidation experiments were conducted with pure liquid antimony at temperatures between 973 and 1373 K. The study showed that the gas phase mass transfer step is the basic mechanisms that controls the oxidation rate for pure antimony. It was noted that the oxidation rate of the alloy was identical to that of the pure antimony, suggesting that an oxidation reaction of the anode slime proceeds at the same rate as pure antimony. This is one of the advantages of treating anode slime through oxidation. Mass transfer in the gas phase was the rate-determining step in the alloy oxidation reaction. It was concluded that a higher oxygen partial pressure and sufficient gas flow rate at temperature of 1073 K is needed to conserve energy and recovery antimony oxide. 13 refs., 2 tabs., 12 figs.

  20. Lead (Pb) and other metals in New York City community garden soils: Factors influencing contaminant distributions

    Mitchell, Rebecca G.; Spliethoff, Henry M.; Ribaudo, Lisa N.; Lopp, Donna M.; Shayler, Hannah A.; Marquez-Bravo, Lydia G.; Lambert, Veronique T.; Ferenz, Gretchen S.; Russell-Anelli, Jonathan M.; Stone, Edie B.; McBride, Murray B.

    2014-01-01

    Urban gardens provide affordable fresh produce to communities with limited access to healthy food but may also increase exposure to lead (Pb) and other soil contaminants. Metals analysis of 564 soil samples from 54 New York City (NYC) community gardens found at least one sample exceeding health-based guidance values in 70% of gardens. However, most samples (78%) did not exceed guidance values, and medians were generally below those reported in NYC soil and other urban gardening studies. Barium (Ba) and Pb most frequently exceeded guidance values and along with cadmium (Cd) were strongly correlated with zinc (Zn), a commonly measured nutrient. Principal component analysis suggested that contaminants varied independently from organic matter and geogenic metals. Contaminants were associated with visible debris and a lack of raised beds; management practices (e.g., importing uncontaminated soil) have likely reduced metals concentrations. Continued exposure reduction efforts would benefit communities already burdened by environmental exposures. - Highlights: • We measured metals concentrations in soil from 54 New York City community gardens. • Pb and Ba exceeded health-based guidance values in 9%–12% of garden beds. • Pb concentrations were similar to those in other studies of urban garden soils. • Pb and Ba were associated with Zn, with visible debris, and with non-raised beds. • Observable details can help gardeners focus testing and exposure reduction efforts. - Pb and Ba, which exceeded health-based guidance values in 10–14% of NYC community garden soil samples, are associated with non-raised beds, visible debris, higher pH and Zn

  1. Magnetic resonance imaging inside cylindrical metal containers with an eddy current self-compensated method

    Han, Hui; Balcom, Bruce J

    2011-01-01

    Magnetic resonance imaging (MRI) measurements inside cylindrical metal structures have recently been proposed and form the basis for new high-pressure MRI studies. The critical problem for MRI inside cylindrical metal structures is significant eddy currents induced by the switched magnetic field gradients, which usually corrupt spatial and motion encoding without appropriate correction. In this work a so-called standard SPRITE (single point ramped imaging with T 1 enhancement) technique is applied for imaging inside cylindrical metal structures. We show that the standard SPRITE technique is fundamentally immune to large-scale eddy current effects and yields artifact-free high-quality images with no eddy current correction required. Standard SPRITE image acquisition avoids the complications involved in the measurement and compensation of eddy current effects for MRI with cylindrical metal structures. This work is a substantial advance toward the extension of MRI to new challenging systems, which are of practical importance

  2. Assessment of defects in ferromagnetic metals with eddy currents

    Oaten, Susan Rosemary

    1989-01-01

    This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University. A study was made to identify and size surface breaking defects in ferromagnetic materials with eddy currents, whilst eliminating unwanted signals due to changes in magnetic permeability and probe lift-off. The former was overcome by the use of high frequencies and the latter by utilising the lift-off to characterise the defects. The lift- off or "touch" method was shown to be advantageous in ...

  3. Effect of screening current induced pair breaking on magnetization of superconducting lead nanoparticles

    Yashwant, G.; Prajapat, C.L. [Technical Physics and Prototype Engineering Division, Bhabha Atomic Research Centre, Mumbai, Maharashtra 400 085 (India); Jayakumar, O.D. [Chemistry Division, Bhabha Atomic Research Centre, Mumbai, Maharashtra 400 085 (India); Singh, M.R.; Gupta, S.K. [Technical Physics and Prototype Engineering Division, Bhabha Atomic Research Centre, Mumbai, Maharashtra 400 085 (India); Tyagi, A.K. [Chemistry Division, Bhabha Atomic Research Centre, Mumbai, Maharashtra 400 085 (India); Ravikumar, G. [Technical Physics and Prototype Engineering Division, Bhabha Atomic Research Centre, Mumbai, Maharashtra 400 085 (India)], E-mail: gurazada@barc.gov.in

    2008-06-15

    Magnetization measurements on lead nanoparticles in the size range 35-45 nm are presented. It is shown that the critical fields in these nanoparticles are enhanced significantly above their bulk values with temperature dependence also distinct from that of bulk. The observed 'type II' like shape of the magnetization curves is explained on the basis of the Ginzburg-Landau phenomenology by invoking the pair breaking effect of the London screening currents, which makes the effective penetration depth an increasing function of the field. The temperature dependence of critical field is found to be consistent with our explanation.

  4. Edge effects in four-point direct current potential drop measurements on metal plates

    Lu, Y; Bowler, N; Bowler, J R; Huang, Y

    2009-01-01

    Four-point direct current potential drop (DCPD) measurements are commonly used to measure the conductivity (or resistivity) of semiconductors and ferrous or non-ferrous metals. The measured electrical potential difference is often interpreted in terms of analytic expressions developed for large plates that are either 'thin' or 'thick' relative to the probe length. It is well known that the presence of the back surface of a plate leads to a solution expressed in terms of an infinite series representing the current source and its images. This approach can be generalized to account for multiple surfaces in order to obtain a solution for a finite plate, but convergence of the series is poor when the plate dimensions are similar to or smaller than the separation of the current injection and extraction points. Here, Fourier series representations of the infinite sums are obtained. It is shown that the Fourier series converge with many fewer terms than the series obtained from image theory, for plates with dimensions similar to or smaller than the separation of the current injection and extraction points. Comparing calculated results for the potential drop obtained by a four-point probe centred on finite plates of varying dimension, with those for a probe in contact with a large (laterally infinite) plate, estimates are given of the uncertainty due to edge effects in measurements on small plates interpreted using analytic formulae developed for large plates. It is also shown that these uncertainties due to edge effects are reduced, for a given plate size, if the probe pick-up points are moved closer to the current injection points, rather than adopting the common arrangement in which the four probe points are equally spaced. Calculated values of DCPD are compared with experimental data taken on aluminium and spring-steel plates of various sizes and excellent agreement is obtained.

  5. Edge effects in four-point direct current potential drop measurements on metal plates

    Lu, Y.; Bowler, N.; Bowler, J. R.; Huang, Y.

    2009-07-01

    Four-point direct current potential drop (DCPD) measurements are commonly used to measure the conductivity (or resistivity) of semiconductors and ferrous or non-ferrous metals. The measured electrical potential difference is often interpreted in terms of analytic expressions developed for large plates that are either 'thin' or 'thick' relative to the probe length. It is well known that the presence of the back surface of a plate leads to a solution expressed in terms of an infinite series representing the current source and its images. This approach can be generalized to account for multiple surfaces in order to obtain a solution for a finite plate, but convergence of the series is poor when the plate dimensions are similar to or smaller than the separation of the current injection and extraction points. Here, Fourier series representations of the infinite sums are obtained. It is shown that the Fourier series converge with many fewer terms than the series obtained from image theory, for plates with dimensions similar to or smaller than the separation of the current injection and extraction points. Comparing calculated results for the potential drop obtained by a four-point probe centred on finite plates of varying dimension, with those for a probe in contact with a large (laterally infinite) plate, estimates are given of the uncertainty due to edge effects in measurements on small plates interpreted using analytic formulae developed for large plates. It is also shown that these uncertainties due to edge effects are reduced, for a given plate size, if the probe pick-up points are moved closer to the current injection points, rather than adopting the common arrangement in which the four probe points are equally spaced. Calculated values of DCPD are compared with experimental data taken on aluminium and spring-steel plates of various sizes and excellent agreement is obtained.

  6. Conductor of high electrical current at high temperature in oxygen and liquid metal environment

    Powell, IV, Adam Clayton; Pati, Soobhankar; Derezinski, Stephen Joseph; Lau, Garrett; Pal, Uday B.; Guan, Xiaofei; Gopalan, Srikanth

    2016-01-12

    In one aspect, the present invention is directed to apparatuses for and methods of conducting electrical current in an oxygen and liquid metal environment. In another aspect, the invention relates to methods for production of metals from their oxides comprising providing a cathode in electrical contact with a molten electrolyte, providing a liquid metal anode separated from the cathode and the molten electrolyte by a solid oxygen ion conducting membrane, providing a current collector at the anode, and establishing a potential between the cathode and the anode.

  7. Effects of metallic nanoparticle doped flux on the interfacial intermetallic compounds between lead-free solder ball and copper substrate

    Sujan, G.K.; Haseeb, A.S.M.A.; Afifi, A.B.M.

    2014-01-01

    Lead free solders currently in use are prone to develop thick interfacial intermetallic compound layers with rough morphology which are detrimental to the long term solder joint reliability. A novel method has been developed to control the morphology and growth of intermetallic compound layers between lead-free Sn–3.0Ag–0.5Cu solder ball and copper substrate by doping a water soluble flux with metallic nanoparticles. Four types of metallic nanoparticles (nickel, cobalt, molybdenum and titanium) were used to investigate their effects on the wetting behavior and interfacial microstructural evaluations after reflow. Nanoparticles were dispersed manually with a water soluble flux and the resulting nanoparticle doped flux was placed on copper substrate. Lead-free Sn–3.0Ag–0.5Cu solder balls of diameter 0.45 mm were placed on top of the flux and were reflowed at a peak temperature of 240 °C for 45 s. Angle of contact, wetting area and interfacial microstructure were studied by optical microscopy, field emission scanning electron microscopy and energy-dispersive X-ray spectroscopy. It was observed that the angle of contact increased and wetting area decreased with the addition of cobalt, molybdenum and titanium nanoparticles to flux. On the other hand, wettability improved with the addition of nickel nanoparticles. Cross-sectional micrographs revealed that both nickel and cobalt nanoparticle doping transformed the morphology of Cu 6 Sn 5 from a typical scallop type to a planer one and reduced the intermetallic compound thickness under optimum condition. These effects were suggested to be related to in-situ interfacial alloying at the interface during reflow. The minimum amount of nanoparticles required to produce the planer morphology was found to be 0.1 wt.% for both nickel and cobalt. Molybdenum and titanium nanoparticles neither appear to undergo alloying during reflow nor have any influence at the solder/substrate interfacial reaction. Thus, doping of flux

  8. Effects of metallic nanoparticle doped flux on the interfacial intermetallic compounds between lead-free solder ball and copper substrate

    Sujan, G.K., E-mail: sgkumer@gmail.com; Haseeb, A.S.M.A., E-mail: haseeb@um.edu.my; Afifi, A.B.M., E-mail: amalina@um.edu.my

    2014-11-15

    Lead free solders currently in use are prone to develop thick interfacial intermetallic compound layers with rough morphology which are detrimental to the long term solder joint reliability. A novel method has been developed to control the morphology and growth of intermetallic compound layers between lead-free Sn–3.0Ag–0.5Cu solder ball and copper substrate by doping a water soluble flux with metallic nanoparticles. Four types of metallic nanoparticles (nickel, cobalt, molybdenum and titanium) were used to investigate their effects on the wetting behavior and interfacial microstructural evaluations after reflow. Nanoparticles were dispersed manually with a water soluble flux and the resulting nanoparticle doped flux was placed on copper substrate. Lead-free Sn–3.0Ag–0.5Cu solder balls of diameter 0.45 mm were placed on top of the flux and were reflowed at a peak temperature of 240 °C for 45 s. Angle of contact, wetting area and interfacial microstructure were studied by optical microscopy, field emission scanning electron microscopy and energy-dispersive X-ray spectroscopy. It was observed that the angle of contact increased and wetting area decreased with the addition of cobalt, molybdenum and titanium nanoparticles to flux. On the other hand, wettability improved with the addition of nickel nanoparticles. Cross-sectional micrographs revealed that both nickel and cobalt nanoparticle doping transformed the morphology of Cu{sub 6}Sn{sub 5} from a typical scallop type to a planer one and reduced the intermetallic compound thickness under optimum condition. These effects were suggested to be related to in-situ interfacial alloying at the interface during reflow. The minimum amount of nanoparticles required to produce the planer morphology was found to be 0.1 wt.% for both nickel and cobalt. Molybdenum and titanium nanoparticles neither appear to undergo alloying during reflow nor have any influence at the solder/substrate interfacial reaction. Thus, doping

  9. Stabilization/solidification of battery debris ampersand lead impacted material at Schuylkill Metals, Plant City, Florida

    Anguiano, T.; Floyd, D.

    1997-01-01

    The Schuylkill Metals facility in Plant City Florida (SMPCI) operated as a battery recycling facility for approximately 13 years. During its operation, the facility disposed of battery components in surrounding wetland areas. In March of 1991 the U.S. EPA and SMPCI entered into a Consent Decree for the remediation of the SMPCI site using stabilization/solidification and on-site disposal. In November of 1994, ENTACT began remediation at the facility and to date has successfully stabilized/solidified over 228,000 tons of lead impacted battery components and lead impacted material. The ENTACT process reduces the size of the material to be treated to ensure that complete mixing of the phosphate/cement additive is achieved thereby promoting the chemical reactions of stabilization and solidification. ENTACT has met the following performance criteria for treated material at the SMPCI site: (1) Hydraulic Conductivity less than 1x10 -6 cm/s, (2) Unconfined Compressive Strength greater than 50 psi, (3) Lead, Cadmium, Arsenic, Chromium TCLP Leachability below hazardous levels

  10. Lead and the London Metal Exchange — a happy marriage? The outlook for prices and pricing issues confronting the lead industry

    Keen, A.

    The outlook for the supply-demand balance for refined lead is addressed and takes into account the growing non-fundamental forces on price determination. The market for refined lead is presently experiencing its first year of surplus since the major crisis of the early 1990s. Earlier in the decade, the dissolution of the Soviet Union and recession in developed economies led to a significant rise in London Metal Exchange (LME) stocks. An acceleration absorbed these stocks in an 18-month period in the mid-1990s, and LME lead prices reacted to the market deficit by peaking above US900. Since then the market has balanced, yet prices have declined steadily to less that 50% of their peak levels. It is argued that, on fundamental grounds, prices have fallen below justified levels. As much of the reason for this depression between 1997 and 1999 has been the generally depressive effect of the Asian economic crisis on financial markets, the level of lead prices may now be due for a correction. Other metals have begun to increase during the first half of 1999 and lead, given its neutral fundamental outlook, is now poised to participate in the generally more buoyant moods across LME metals. An increase of approximately 10% in average LME 3-month settlement prices is forecast and will result in annual average prices of US 570/tonne over the course of 1999. Monthly averages and spot prices are predicted to exceed this level, particularly during peak third-quarter demand.

  11. Lead and other trace metals in preeclampsia: A case-control study in Tehran, Iran

    Vigeh, Mohsen; Yokoyama, Kazuhito; Ramezanzadeh, Fateme; Dahaghin, Mojgan; Sakai, Tadashi; Morita, Yoko; Kitamura, Fumihiko; Sato, Hajime; Kobayashi, Yasuki

    2006-01-01

    To assess the effects of environmental exposures to trace metals on the incidence of preeclampsia, concentrations of lead (Pb), antimony (Sb), manganese (Mn), mercury, cadmium, cobalt and zinc in umbilical cord blood (UCB) and mother whole blood (MWB) were measured in 396 postpartum women without occupational exposure to metals in Tehran, Iran, using inductively coupled plasma mass spectrometry. Mother's ages ranged from 15 to 49 (mean 27) years. Preeclampsia was diagnosed in 31 subjects (7.8%). Levels of Pb, Sb and Mn in UCB were significantly higher in preeclampsia cases [mean+/-SD of 4.30+/-2.49μg/dl, 4.16+/-2.73 and 46.87+/-15.03μg/l, respectively] than in controls [3.52+/-2.09μg/dl, 3.17+/-2.68 and 40.32+/-15.19μg/l, respectively] (P<0.05). The logistic regression analysis revealed that one unit increase in the common logarithms of UCB concentration of Pb, Sb or Mn led to increase in the risk of preeclampsia several-fold; unit risks (95% CI) were 12.96 (1.57-107.03), 6.11 (1.11-33.53) and 34.2 (1.81-648.04) for Pb, Sb and Mn, respectively (P<0.05). These findings suggest that environmental exposure to Pb, Sb and Mn may increase the risk of preeclampsia in women without occupational exposure; levels of metals in UCB to be sensitive indicators of female reproductive toxicity as compared with those in mother MWB. Further studies are necessary to confirm these findings, especially on Sb and Mn

  12. Identification of the sources of metal (lead) contamination in drinking waters in north-eastern Tasmania using lead isotopic compositions.

    Harvey, P J; Handley, H K; Taylor, M P

    2015-08-01

    This study utilises a range of scientific approaches, including lead isotopic compositions, to differentiate unknown sources of ongoing lead contamination of a drinking water supply in north-eastern Tasmania, Australia. Drinking water lead concentrations are elevated above the Australian Drinking Water Guideline (10 μg/L), reaching 540 μg/L in the supply network. Water lead isotopic compositions from the town of Pioneer ((208)Pb/(207)Pb 2.406, (206)Pb/(207)Pb 1.144 to (208)Pb/(207)Pb 2.360, (206)Pb/(207)Pb 1.094) and Ringarooma ((208)Pb/(207)Pb 2.398, (206)Pb/(207)Pb 1.117) are markedly different from the local bedrock ((208)Pb/(207)Pb 2.496, (206)Pb/(207)Pb 1.237). The data show that the lead in the local waters is sourced from a combination of dilapidated drinking water infrastructure, including lead jointed pipelines, end-of-life polyvinyl chloride pipes and household plumbing. Drinking water is being inadvertently contaminated by aging infrastructure, and it is an issue that warrants investigation to limit the burden of disease from lead exposure.

  13. Silica nanoparticles capture atmospheric lead: implications in the treatment of environmental heavy metal pollution.

    Yang, Xifei; Shen, Zhiguo; Zhang, Bing; Yang, Jianping; Hong, Wen-Xu; Zhuang, Zhixiong; Liu, Jianjun

    2013-01-01

    Lead (Pb) contamination in the air is a severe global problem, most notably in China. Removal of Pb from polluted air remains a significant challenge. It is unclear what potential effects silica nanoparticles (SiNPs) exposure can have on atmospheric Pb. Here we first characterized the features of SiNPs by measuring the particle size, zeta potential and the specific surface area of SiO(2) particles using a Nicomp 380/ZLS submicron particle sizer, the Brunauer-Emmett-Teller (BET) method and transmission electronic microscopy (TEM). We measured the content of the metal Pb adsorbed by SiNPs exposed to two Pb polluted electric battery plants using inductively coupled plasma mass spectrometry (ICP-MS). It is found that SiNPs exposed to two Pb polluted electric battery plants absorb more atmospheric Pb compared to either blank control or micro-sized SiO(2) particles in a time-dependent manner. This is the first study demonstrating that SiNPs exposure can absorb atmospheric Pb in the polluted environment. These novel findings indicate that SiNPs have potential to serve as a significant adsorbent of Pb from industrial pollution, implicating a potentially novel application of SiNPs in the treatment of environmental heavy metal pollution. Copyright © 2012 Elsevier Ltd. All rights reserved.

  14. Performance comparison of metallic, actinide burning fuel in lead-bismuth and sodium cooled fast reactors

    Weaver, K.D.; Herring, J.S.; Macdonald, P.E.

    2001-01-01

    Various methods have been proposed to ''incinerate'' or ''transmute'' the current inventory of transuranic waste (TRU) that exits in spent light-water-reactor (LWR) fuel, and weapons plutonium. These methods include both critical (e.g., fast reactors) and non-critical (e.g., accelerator transmutation) systems. The work discussed here is part of a larger effort at the Idaho National Engineering and Environmental Laboratory (INEEL) and at the Massachusetts Institute of Technology (MIT) to investigate the suitability of lead and lead-alloy cooled fast reactors for producing low-cost electricity as well as for actinide burning. The neutronics of non fertile fuel loaded with 20 or 30-wt% light water reactor (LWR) plutonium plus minor actinides for use in a lead-bismuth cooled fast reactor are discussed in this paper, with an emphasis on the fuel cycle life and isotopic content. Calculations show that the average actinide burn rate is similar for both the sodium and lead-bismuth cooled cases ranging from -1.02 to -1.16 g/MWd, compared to a typical LWR actinide generation rate of 0.303 g/MWd. However, when using the same parameters, the sodium-cooled case went subcritical after 0.2 to 0.8 effective full power years, and the lead-bismuth cooled case ranged from 1.5 to 4.5 effective full power years. (author)

  15. Non destructive analysis apparatus by eddy currents for non magnetic metallic products

    Coutanceau-Monteil, N.; Billy, F.; Bernard, A.

    1993-01-01

    The device for non destructive testing of nonmagnetic metallic surfaces uses eddy currents with two independent receptors at different positions around the emitting coil which is fed with current impulses and whose axis is parallel to the surface under study. 4 figs

  16. Comparison and analysis of the efficiency of heat exchange of copper rod and copper wires current lead

    Fang, J.; Yu, T.; Li, Z.M.; Wei, B.; Qiu, M.; Zhang, H.J.

    2013-01-01

    Highlights: •An optimized design of HTS binary current leads is proposed. •Temperature distributions of two different current leads are calculated. •Experiments are done to certify the calculated temperature distributions. •The experiments proved that the copper wires increase security margins. -- Abstract: Current leads are the key components that connect the low-temperature and high temperature parts of the cryogenic system. Owing to the wide range of temperatures, current leads are the main sources of heat leakage. Since the HTS tapes have no resistance and the generated Joule heat is almost zero, HTS binary current leads can reduce heat leakage compared to the conventional leads. However, heat will still be generated and conducted to the cryogenic system through the copper parts of the HTS current leads. In order to reduce heat leakage by the copper parts of the HTS current leads, this paper presents an optimized design of the copper parts of HTS binary current leads. Inside the leads, the copper wires were applied as an alternative to the copper rod without changing the overall dimensions. Firstly, the differential function of heat transfer was derived. By solving the function, the optimum number of the copper wires and the temperature distribution of two different current leads were gotten. Then the experiment of the temperature distribution was done, and the experimental results were basically the same with the calculative results. The simulation and related experiments proved that the copper wire can increase security margins and reduce maximum temperatures under the same shunt current

  17. Comparison and analysis of the efficiency of heat exchange of copper rod and copper wires current lead

    Fang, J., E-mail: fangseer@sina.com [School of Electrical Engineering, Beijing Jiaotong University, Beijing (China); Yu, T. [School of Electrical Engineering, Beijing Jiaotong University, Beijing (China); Li, Z.M.; Wei, B.; Qiu, M.; Zhang, H.J. [China Electric Power Research Institute, Haidian District, Beijing (China)

    2013-11-15

    Highlights: •An optimized design of HTS binary current leads is proposed. •Temperature distributions of two different current leads are calculated. •Experiments are done to certify the calculated temperature distributions. •The experiments proved that the copper wires increase security margins. -- Abstract: Current leads are the key components that connect the low-temperature and high temperature parts of the cryogenic system. Owing to the wide range of temperatures, current leads are the main sources of heat leakage. Since the HTS tapes have no resistance and the generated Joule heat is almost zero, HTS binary current leads can reduce heat leakage compared to the conventional leads. However, heat will still be generated and conducted to the cryogenic system through the copper parts of the HTS current leads. In order to reduce heat leakage by the copper parts of the HTS current leads, this paper presents an optimized design of the copper parts of HTS binary current leads. Inside the leads, the copper wires were applied as an alternative to the copper rod without changing the overall dimensions. Firstly, the differential function of heat transfer was derived. By solving the function, the optimum number of the copper wires and the temperature distribution of two different current leads were gotten. Then the experiment of the temperature distribution was done, and the experimental results were basically the same with the calculative results. The simulation and related experiments proved that the copper wire can increase security margins and reduce maximum temperatures under the same shunt current.

  18. The current environmental impact of base-metal mining at the Tui Mine, Te Aroha, New Zealand

    Sabti, H.; Hossain, M.M.; Brooks, R.R.; Stewart, R.B.

    2000-01-01

    The current environmental impact of base metal mining at the Tui Mine, Te Aroha and gold mining near Waihi, was investigated by analysis of local waters, stream sediments and aquatic vegetation. X-ray diffraction analysis of heavy metal fractions in stream sediments showed the presence of pyrite in the upper reaches of the Tunakohoia and Tui streams that drain the mineralised reefs and Tui tailings dam. Relatively immobile lead (galena) was retained close to the source, whereas copper and zinc minerals were more mobile and distributed further downstream from the areas of mineralisation. Gold was determined in sediments from the Ohinemuri and Waitekauri Rivers along with other heavy metals derived from sulphide mineralisation at Waihi and Waitekauri. Analysis of waters from the Tui and Tunakohoia streams showed concentrations of arsenic, cadmium, lead and zinc above recommended levels for potable water in the upper parts of these waterways. The discharge of these streams into the Waihou River (sampled upstream from Te Aroha and downstream past Paeroa) did not have any significant effect on heavy-metal concentrations in this river. Aquatic macrophytes sampled in the Waihou, Ohinemuri and Waitekauri Rivers had very high heavy-metal concentrations compared with the ambient water and should be considered as potentially useful for assessing the impact of low-metal fluxes into the waters. Gold was detected in aquatic marcophytes from streams draining both the Martha Mine at Waihi and the Golden Cross Mine at Waitekauri and indicated the possibility of prospecting for gold by analysis of these plants. (author). 17 refs., 3 figs., 6 tabs

  19. Electrodeposition of alkali and alkali-earth metals on liquid lead cathodes in molten salts

    Caravaca, C.; De Cordoba, G.

    2008-01-01

    Pyrochemical processing of spent nuclear fuel leads to the dissolution as chlorides of fission products (FPs) that have to be removed in order to recycle the salt. Precipitation technique have been tested for the removal of these FPs in the LiCl-KCl, salt selected as reference, with different results. Salt decontamination from lanthanides can be easily achieved as solid precipitates of oxychlorides or single phosphates; however, for the alkaline and alkaline-earth metals this technique is not suitable. Within the EUROPART project (VI FP of the EC), a new route that consist of the electrodeposition of these FP on a liquid lead cathode (LLC) has been considered, including the Li and K constituting the electrolyte. First results obtained with Sr and Cs are presented herein. Although according to the thermodynamic potential values, the electrodeposition order on LLC is Ba, Sr, Li, K and Cs, during our experiments it was not possible to distinguish the electrochemical signals corresponding to the individual elements. (authors)

  20. Effects of metal lead on growth and mycorrhizae of an invasive plant species (Solidago canadensis L.).

    Yang, Ruyi; Yu, Guodong; Tang, Jianjun; Chen, Xin

    2008-01-01

    It is less known whether and how soil metal lead (Pb) impacts the invasion of exotic plants. A greenhouse experiment was conducted to estimate the effects of lead on the growth and mycorrhizae of an invasive species (Solidago canadensis L.) in a microcosm system. Each microcosm unit was separated into HOST and TEST compartments by a replaceable mesh screen that allowed arbuscular mycorrhizal (AM) fungal hyphae rather than plant roots to grow into the TEST compartments. Three Pb levels (control, 300, and 600 mg/kg soil) were used in this study to simulate ambient soil and two pollution sites where S. canadensis grows. Mycorrhizal inoculum comprised five indigenous arbuscular mycorrhizal fungal species (Glomus mosseae, Glomus versiform, Glomus diaphanum, Glomus geosporum, and Glomus etunicatum). The 15N isotope tracer was used to quantify the mycorrhizally mediated nitrogen acquisition of plants. The results showed that S. canadensis was highly dependent on mycorrhizae. The Pb additions significantly decreased biomass and arbuscular mycorrhizal colonization (root length colonized, RLC%) but did not affect spore numbers, N (including total N and 15N) and P uptake. The facilitating efficiency of mycorrhizae on nutrient acquisition was promoted by Pb treatments. The Pb was mostly sequestered in belowground of plant (root and rhizome). The results suggest that the high efficiency of mycorrhizae on nutrient uptake might give S. canadensis a great advantage over native species in Pb polluted soils.

  1. Electrodeposition of alkali and alkali-earth metals on liquid lead cathodes in molten salts

    Caravaca, C.; De Cordoba, G. [CIEMAT/DE/DFN/URAA. Avda. Complutense, 22. 28040 Madrid (Spain)

    2008-07-01

    Pyrochemical processing of spent nuclear fuel leads to the dissolution as chlorides of fission products (FPs) that have to be removed in order to recycle the salt. Precipitation technique have been tested for the removal of these FPs in the LiCl-KCl, salt selected as reference, with different results. Salt decontamination from lanthanides can be easily achieved as solid precipitates of oxychlorides or single phosphates; however, for the alkaline and alkaline-earth metals this technique is not suitable. Within the EUROPART project (VI FP of the EC), a new route that consist of the electrodeposition of these FP on a liquid lead cathode (LLC) has been considered, including the Li and K constituting the electrolyte. First results obtained with Sr and Cs are presented herein. Although according to the thermodynamic potential values, the electrodeposition order on LLC is Ba, Sr, Li, K and Cs, during our experiments it was not possible to distinguish the electrochemical signals corresponding to the individual elements. (authors)

  2. Behavior of Lithium Metal Anodes under Various Capacity Utilization and High Current Density in Lithium Metal Batteries

    Jiao, Shuhong; Zheng, Jianming; Li, Qiuyan; Li, Xing; Engelhard, Mark H.; Cao, Ruiguo; Zhang, Ji-Guang; Xu, Wu

    2018-01-01

    Lithium (Li) metal batteries (LMBs) are regarded as the most promising power sources for electric vehicles. Besides the Li dendrite growth and low Li Coulombic efficiency, how to well match Li metal anode with a high loading (normally over 3.0 mAh cm-2) cathode is another key challenge to achieve the real high energy density battery. In this work, we systematically investigate the effects of the Li metal capacity usage in each cycle, manipulated by varying the cathode areal loading, on the stability of Li metal anode and the cycling performance of LMBs using the LiNi1/3Mn1/3Co1/3O2 (NMC) cathode and an additive-containing dual-salt/carbonate-solvent electrolyte. It is demonstrated that the Li||NMC cells show decent long-term cycling performance even with NMC areal capacity loading up to ca. 4.0 mAh cm-2 and at a charge current density of 1.0 mA cm-2. The increase of the Li capacity usage in each cycle causes variation in the components of the solid electrolyte interphase (SEI) layer on Li metal anode and generates more ionic conductive species from this electrolyte. Further study reveals for the first time that the degradation of Li metal anode and the thickness of SEI layer on Li anode show linear relationship with the areal capacity of NMC cathode. Meanwhile, the expansion rate of consumed Li and the ratio of SEI thickness to NMC areal loading are kept almost the same value with increasing cathode loading, respectively. These fundamental findings provide new perspectives on the rational evaluation of Li metal anode stability for the development of rechargeable LMBs.

  3. The 12-lead electrocardiogram and risk of sudden death: current utility and future prospects.

    Narayanan, Kumar; Chugh, Sumeet S

    2015-10-01

    More than 100 years after it was first invented, the 12-lead electrocardiogram (ECG) continues to occupy an important place in the diagnostic armamentarium of the practicing clinician. With the recognition of relatively rare but important clinical entities such as Wolff-Parkinson-White and the long QT syndrome, this clinical tool was firmly established as a test for assessing risk of sudden cardiac death (SCD). However, over the past two decades the role of the ECG in risk prediction for common forms of SCD, for example in patients with coronary artery disease, has been the focus of considerable investigation. Especially in light of the limitations of current risk stratification approaches, there is a renewed focus on this broadly available and relatively inexpensive test. Various abnormalities of depolarization and repolarization on the ECG have been linked to SCD risk; however, more focused work is needed before they can be deployed in the clinical arena. The present review summarizes the current knowledge on various ECG risk markers for prediction of SCD and discusses some future directions in this field. Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2015. For permissions please email: journals.permissions@oup.com.

  4. Comparison of the Standard of Air Leakage in Current Metal Duct Systems in the World

    Di, Yuhui; Wang, Jiqian; Feng, Lu; Li, Xingwu; Hu, Chunlin; Shi, Junshe; Xu, Qingsong; Qiao, Leilei

    2018-01-01

    Based on the requirements of air leakage of metal ducts in Chinese design standards, technical measures and construction standards, this paper compares the development history, the classification of air pressure levels and the air tightness levels of air leakage standards of current Chinese and international metal ducts, sums up the differences, finds shortage by investigating the design and construction status and access to information, and makes recommendations, hoping to help the majority of engineering and technical personnel.

  5. Control of the electrode metal transfer by means of the welding current pulse generator

    Knyaz'kov, A.; Pustovykh, O.; Verevkin, A.; Terekhin, V.; Shachek, A.; Knyaz'kov, S.; Tyasto, A.

    2016-04-01

    The paper presents a generator of welding current pulses to transfer an electrode metal into the molten pool. A homogeneous artificial line is used to produce near rectangular pulses. The homogeneous artificial line provides the minimum heat input with in the pulse to transfer the electrode metal, and it significantly decreases the impact of disturbances affecting this transfer. The pulse frequency does not exceed 300 Hz, and the duration is 0.6 ÷ 0.9 ms.

  6. Environmental hazard of cadmium, copper, lead and zinc in metal-contaminated soils remediated by sulfosuccinamate formulation.

    del Carmen Hernández-Soriano, Maria; Peña, Aránzazu; Mingorance, M Dolores

    2011-10-01

    Accumulation of metals in soil at elevated concentrations causes risks to the environmental quality and human health for more than one hundred million people globally. The rate of metal release and the alteration of metal distribution in soil phases after soil washing with a sulfosuccinamate surfactant solution (Aerosol 22) were evaluated for four contaminated soils. Furthermore, a sequential extraction scheme was carried out using selective extractants (HAcO, NH(2)OH·HCl, H(2)O(2) + NH(4)AcO) to evaluate which metal species are extracted by A22 and the alteration in metal distribution upon surfactant-washing. Efficiency of A22 to remove metals varied among soils. The washing treatment released up to 50% of Cd, 40% of Cu, 20% of Pb and 12% of Zn, mainly from the soluble and reducible soil fractions, therefore, greatly reducing the fraction of metals readily available in soil. Metal speciation analysis for the solutions collected upon soil washing with Aerosol 22 further confirmed these results. Copper and lead in solution were mostly present as soluble complexes, while Cd and Zn were present as free ions. Besides, redistribution of metals in soil was observed upon washing. The ratios of Zn strongly retained in the soil matrix and Cd complexed with organic ligands increased. Lead was mobilized to more weakly retained forms, which indicates a high bioavailability of the remaining Pb in soil after washing. Comprehensive knowledge on chemical forms of metals present in soil allows a feasible assessment of the environmental impact of metals for a given scenario, as well as possible alteration of environmental conditions, and a valuable prediction for potential leaching and groundwater contamination.

  7. Are Metals Emitted from Electronic Cigarettes a Reason for Health Concern? A Risk-Assessment Analysis of Currently Available Literature

    Konstantinos E. Farsalinos

    2015-05-01

    Full Text Available Background: Studies have found that metals are emitted to the electronic cigarette (EC aerosol. However, the potential health impact of exposure to such metals has not been adequately defined. The purpose of this study was to perform a risk assessment analysis, evaluating the exposure of electronic cigarette (EC users to metal emissions based on findings from the published literature. Methods: Two studies were found in the literature, measuring metals emitted to the aerosol from 13 EC products. We estimated that users take on average 600 EC puffs per day, but we evaluated the daily exposure from 1200 puffs. Estimates of exposure were compared with the chronic Permissible Daily Exposure (PDE from inhalational medications defined by the U.S. Pharmacopeia (cadmium, chromium, copper, lead and nickel, the Minimal Risk Level (MRL defined by the Agency for Toxic Substances and Disease Registry (manganese and the Recommended Exposure Limit (REL defined by the National Institute of Occupational Safety and Health (aluminum, barium, iron, tin, titanium, zinc and zirconium. Results: The average daily exposure from 13 EC products was 2.6 to 387 times lower than the safety cut-off point of PDEs, 325 times lower than the safety limit of MRL and 665 to 77,514 times lower than the safety cut-off point of RELs. Only one of the 13 products was found to result in exposure 10% higher than PDE for one metal (cadmium at the extreme daily use of 1200 puffs. Significant differences in emissions between products were observed. Conclusions: Based on currently available data, overall exposure to metals from EC use is not expected to be of significant health concern for smokers switching to EC use, but is an unnecessary source of exposure for never-smokers. Metal analysis should be expanded to more products and exposure can be further reduced through improvements in product quality and appropriate choice of materials.

  8. RIKEN 200 kV high current implanter for metal surface modification

    Iwaki, M.; Yoshida, K.; Sakudo, N.

    1985-01-01

    A high current, metal ion implanter was constructed in order to aid the formation of a new metastable surface alloy. This implanter, called a RIKEN 200 kV high current implanter, is a modified Lintott high current machine (Series III), which has the advantages of having its own microwave ion source and an extra target chamber. The microwave discharge ion source without a hot-filament has a comparatively long lifetime because the chloride ions and radicals in a plasma during discharge of metal chlorides might prevent metal to deposit on the inner walls of the discharge chamber by bombarding and chemically cleaning them. An extra target chamber for metal modification is able to control the surface composition by utilizing the sputtering effect of the ion beam during ion implantation. The use of this ion source and the extra target chamber is suggested to be suitable for the production of metallic ions and for the implantation into metals. The case study will be introduced for TI implantation into Fe. (orig.)

  9. Lead emissions from road transport in Europe. A revision of current estimates using various estimation methodologies

    Denier van der Gon, H.A.C.; Appelman, W.

    2009-01-01

    Large-scale use of leaded gasoline was an important source of the neurotoxin lead in the European environment. After a sequence of regulations on the allowed gasoline lead content and, eventually, a ban on the use of lead additives in gasoline, road transport was no longer considered a source of

  10. Accumulation of lead, zinc, copper and cadmium by 12 wetland plant species thriving in metal-contaminated sites in China

    Deng, H.; Ye, Z.H.; Wong, M.H.

    2004-01-01

    The concentrations of lead, zinc, copper and cadmium accumulated by 12 emergent-rooted wetland plant species including different populations of Leersia hexandra, Juncus effusus and Equisetum ramosisti were investigated in field conditions of China. The results showed that metal accumulation by wetland plants differed among species, populations and tissues. Populations grown in substrata with elevated metals contained significantly higher metals in plants. Metals accumulated by wetland plants were mostly distributed in root tissues, suggesting that an exclusion strategy for metal tolerance widely exists in them. That some species/populations could accumulate relatively high metal concentrations (far above the toxic concentration to plants) in their shoots indicates that internal detoxification metal tolerance mechanism(s) are also included. The factors affecting metal accumulation by wetland plants include metal concentrations, pH, and nutrient status in substrata. Mostly concentrations of Pb and Cu in both aboveground and underground tissues of the plants were significantly positively related to their total and/or DTPA-extractable fractions in substrata while negatively to soil N and P, respectively. The potential use of these wetland plants in phytoremediation is also discussed

  11. Accumulation of lead, zinc, copper and cadmium by 12 wetland plant species thriving in metal-contaminated sites in China

    Deng, H.; Ye, Z.H.; Wong, M.H

    2004-11-01

    The concentrations of lead, zinc, copper and cadmium accumulated by 12 emergent-rooted wetland plant species including different populations of Leersia hexandra, Juncus effusus and Equisetum ramosisti were investigated in field conditions of China. The results showed that metal accumulation by wetland plants differed among species, populations and tissues. Populations grown in substrata with elevated metals contained significantly higher metals in plants. Metals accumulated by wetland plants were mostly distributed in root tissues, suggesting that an exclusion strategy for metal tolerance widely exists in them. That some species/populations could accumulate relatively high metal concentrations (far above the toxic concentration to plants) in their shoots indicates that internal detoxification metal tolerance mechanism(s) are also included. The factors affecting metal accumulation by wetland plants include metal concentrations, pH, and nutrient status in substrata. Mostly concentrations of Pb and Cu in both aboveground and underground tissues of the plants were significantly positively related to their total and/or DTPA-extractable fractions in substrata while negatively to soil N and P, respectively. The potential use of these wetland plants in phytoremediation is also discussed.

  12. Numerical Studies of Friction Between Metallic Surfaces and of its Dependence on Electric Currents

    Meintanis, Evangelos; Marder, Michael

    2009-03-01

    We will present molecular dynamics simulations that explore the frictional mechanisms between clean metallic surfaces. We employ the HOLA molecular dynamics code to run slider-on-block experiments. Both objects are allowed to evolve freely. We recover realistic coefficients of friction and verify the importance of cold-welding and plastic deformations in dry sliding friction. We also find that plastic deformations can significantly affect both objects, despite a difference in hardness. Metallic contacts have significant technological applications in the transmission of electric currents. To explore the effects of the latter to sliding, we had to integrate an electrodynamics solver into the molecular dynamics code. The disparate time scales involved posed a challenge, but we have developed an efficient scheme for such an integration. A limited electrodynamic solver has been implemented and we are currently exploring the effects of currents in the friction and wear of metallic contacts.

  13. Current Status of Trace Metal Pollution in Soils Affected by Industrial Activities

    Kabir, Ehsanul; Ray, Sharmila; Kim, Ki-Hyun; Yoon, Hye-On; Jeon, Eui-Chan; Kim, Yoon Shin; Cho, Yong-Sung; Yun, Seong-Taek; Brown, Richard J. C.

    2012-01-01

    There is a growing public concern over the potential accumulation of heavy metals in soil, owing to rapid industrial development. In an effort to describe the status of the pollutions of soil by industrial activities, relevant data sets reported by many studies were surveyed and reviewed. The results of our analysis indicate that soils were polluted most significantly by metals such as lead, zinc, copper, and cadmium. If the dominant species are evaluated by the highest mean concentration observed for different industry types, the results were grouped into Pb, Zn, Ni, Cu, Fe, and As in smelting and metal production industries, Mn and Cd in the textile industry, and Cr in the leather industry. In most cases, metal levels in the studied areas were found to exceed the common regulation guideline levels enforced by many countries. The geoaccumulation index (I geo), calculated to estimate the enrichment of metal concentrations in soil, showed that the level of metal pollution in most surveyed areas is significant, especially for Pb and Cd. It is thus important to keep systematic and continuous monitoring of heavy metals and their derivatives to manage and suppress such pollution. PMID:22645468

  14. Current Status of Trace Metal Pollution in Soils Affected by Industrial Activities

    Ehsanul Kabir

    2012-01-01

    Full Text Available There is a growing public concern over the potential accumulation of heavy metals in soil, owing to rapid industrial development. In an effort to describe the status of the pollutions of soil by industrial activities, relevant data sets reported by many studies were surveyed and reviewed. The results of our analysis indicate that soils were polluted most significantly by metals such as lead, zinc, copper, and cadmium. If the dominant species are evaluated by the highest mean concentration observed for different industry types, the results were grouped into Pb, Zn, Ni, Cu, Fe, and As in smelting and metal production industries, Mn and Cd in the textile industry, and Cr in the leather industry. In most cases, metal levels in the studied areas were found to exceed the common regulation guideline levels enforced by many countries. The geoaccumulation index (Igeo, calculated to estimate the enrichment of metal concentrations in soil, showed that the level of metal pollution in most surveyed areas is significant, especially for Pb and Cd. It is thus important to keep systematic and continuous monitoring of heavy metals and their derivatives to manage and suppress such pollution.

  15. High Tc superconducting current leads laser fabrication

    Díez, J. C.

    1998-04-01

    Full Text Available In this work is described a laser float zone melting method designed in our laboratory to the development of superconductor Bi2Sr2CaCu2O8 current leads. The most relevant results obtained with different grown conditions and the influence of the process parameters in the properties of superconductor leads are presented.

    Las barras de alimentación basadas en el superconductor Bi2Sr2CaCu2O8 son de gran interés práctico para la fabricación de criogeneradores capaces de refrigerar bobinas superconductoras a temperaturas inferiores a 77 K e incluso cercanas a 5 K. Las propiedades mecánicas y eléctricas de dichas barras son fundamentales para determinar su grado de fiabilidad, que en última instancia determinar su aplicabilidad a escala comercial. Los parámetros de fabricación utilizando la fusión zonal inducida por láser permiten obtener fibras gruesas de este superconductor capaces de transportar elevadas corrientes a 77 K y a temperaturas inferiores, y con un comportamiento aceptable frente al ciclado térmico y al paso de elevadas intensidades de corriente eléctrica. En este trabajo se describe un sistema de fusión zonal láser diseñado en nuestro laboratorio para el desarrollo de superconductores y se resumen los resultados más significativos obtenidos según las diversas condiciones de crecimiento estudiadas, la influencia de los diversos parámetros de procesado utilizados sobre las propiedades de las fibras superconductoras obtenidas, así como su potencial uso en dispositivos prácticos.

  16. The photo-assisted heat current and its Peltier coefficient in a metal/dot/metal junction

    Crépieux, A

    2012-01-01

    The photo-assisted heat current through a metal/dot/metal junction and its associated Peltier coefficient are computed in the framework of the time-dependent out-of-equilibrium Keldysh formalism in the presence of a dot energy modulation. When the frequency of the modulation is much larger than the amplitude of the modulation, the heat current follows the sinusoidal time evolution of the dot energy. This is no longer the case when the modulation frequency becomes of the order of or smaller than the amplitude of the modulation. To characterize this non-sinusoidal behavior, we have calculated the harmonics of the photo-assisted heat current. The zero-order harmonic can be expressed as an infinite sum of dc heat currents associated with a dot with shifted energies. It exhibits a devil's staircase profile with non-horizontal steps, whereas it is established that the steps are horizontal for the zero-order harmonic of the photo-assisted electric current. This particularity is related to the fact that the dot heat is not a conserved quantity due to energy dissipation within the tunnel barriers.

  17. Spin Injection from Ferromagnetic Metal Directly into Non-Magnetic Semiconductor under Different Injection Currents

    Ning, Deng; Lei, Zhang; Shu-Chao, Zhang; Pei-Yi, Chen; Jian-Shi, Tang

    2010-01-01

    For ferromagnetic metal (FM)/semiconductor (SC) structure with ohmic contact, the effect of carrier polarization in the semiconductor combined with drift part of injection current on current polarization is investigated. Based on the general model we established here, spin injection efficiency under different injection current levels is calculated. Under a reasonable high injection current, current polarization in the semiconductor is actually much larger than that predicted by the conductivity mismatch model because the effect of carrier polarization is enhanced by the increasing drift current. An appreciable current polarization of 1% could be achieved for the FM/SC structure via ohmic contact, which means that efficient spin injection from FM into SC via ohmic contact is possible. The reported dependence of current polarization on temperature is verified quantitatively. To achieve even larger spin injection efficiency, a gradient doping semiconductor is suggested to enhance the drift current effect

  18. Micro-EDXRF surface analyses of a bronze spear head: Lead content in metal and corrosion layers

    Figueiredo, E.; Valerio, P.; Araujo, M.F.; Senna-Martinez, J.C.

    2007-01-01

    A bronze spear head from Central Portugal dated to Late Bronze Age has been analyzed by non-destructive micro-EDXRF in the metal surface and corrosion layers. The artifact had previously been analyzed using a conventional EDXRF spectrometer having a larger incident beam. The quantification of the micro-EDXRF analyses showed that lead content in corrosion layers can reach values up to four times higher than the content determined in the metal surface. Results obtained with the higher energy incident beam from the EDXRF equipment, although referring mainly to the corrosion layers, seem to suffer some influence from the surface composition of the metallic alloy

  19. Current knowledge of US metal and nonmetal miner health: Current and potential data sources for analysis of miner health status

    Yeoman, K. M.; Halldin, C. N.; Wood, J.; Storey, E.; Johns, D.; Laney, A. S.

    2016-01-01

    ABSTRACT Little is known about the current health status of US metal and nonmetal (MNM) miners, in part because no health surveillance systems exist for this population. The National Institute for Occupational Safety and Health (NIOSH) is developing a program to characterize burden of disease among MNM miners. This report discusses current knowledge and potential data sources of MNM miner health. Recent national surveys were analyzed, and literature specific to MNM miner health status was reviewed. No robust estimates of disease prevalence were identified, and national surveys did not provide information specific to MNM miners. Because substantial gaps exist in the understanding of MNM miners' current health status, NIOSH plans to develop a health surveillance program for this population to guide intervention efforts to reduce occupational and personal risks for chronic illness. PMID:25658684

  20. Behavior of Lithium Metal Anodes under Various Capacity Utilization and High Current Density in Lithium Metal Batteries

    Jiao, Shuhong; University of Science and Technology of China, Hefei; Zheng, Jianming; Li, Qiuyan; Li, Xing

    2017-01-01

    We report that lithium (Li) metal batteries (LMBs) have recently attracted extensive interest in the energy-storage field after silence from the public view for several decades. However, many challenges still need to be overcome before their practical application, especially those that are related to the interfacial instability of Li metal anodes. Here, we reveal for the first time that the thickness of the degradation layer on the metallic Li anode surface shows a linear relationship with Li areal capacity utilization up to 4.0 mAh cm -2 in a practical LMB system. The increase in Li capacity utilization in each cycle causes variations in the morphology and composition of the degradation layer on the Li anode. Under high Li capacity utilization, the current density for charge (i.e., Li deposition) is identified to be a key factor controlling the corrosion of the Li metal anode. Lastly, these fundamental findings provide new perspectives for the development of rechargeable LMBs.

  1. Test results of a 20 kA high temperature superconductor current lead using REBCO tapes

    Heller, R.; Fietz, W. H.; Gröner, F.; Heiduk, M.; Hollik, M.; Lange, C.; Lietzow, R.

    2018-05-01

    The Karlsruhe Institute of Technology has developed a 20 kA high temperature superconductor (HTS) current lead (CL) using the second generation material REBCO, as industry worldwide concentrate on the production of this material. The aim was to demonstrate the possibility of replacing the Bi-2223/AgAu tapes by REBCO tapes, while for easy comparison of results, all other components are copies of the 20 kA HTS CL manufactured for the satellite tokamak JT-60SA. After the manufacture of all CL components including the newly developed REBCO module, the assembly of the CL has been executed at KIT and an experiment has been carried out in the CuLTKa test facility where the REBCO CL was installed and connected to a JT-60SA CL via a superconducting bus bar. The experiment covers steady state operation up to 20 kA, pulsed operation, measurement of the heat load at 4.5 K end, loss-of-flow-accident simulations, and quench performance studies. Here the results of these tests are reported and directly compared to those of the JT-60SA CL.

  2. Lead toxicity to Lemna minor predicted using a metal speciation chemistry approach.

    Antunes, Paula M C; Kreager, Nancy J

    2014-10-01

    In the present study, predictive measures for Pb toxicity and Lemna minor were developed from bioassays with 7 surface waters having varied chemistries (0.5-12.5 mg/L dissolved organic carbon, pH of 5.4-8.3, and water hardness of 8-266 mg/L CaCO3 ). As expected based on water quality, 10%, 20%, and 50% inhibitory concentration (IC10, IC20, and IC50, respectively) values expressed as percent net root elongation (%NRE) varied widely (e.g., IC20s ranging from 306 nM to >6920 nM total dissolved Pb), with unbounded values limited by Pb solubility. In considering chemical speciation, %NRE variability was better explained when both Pb hydroxides and the free lead ion were defined as bioavailable (i.e., f{OH} ) and colloidal Fe(III)(OH)3 precipitates were permitted to form and sorb metals (using FeOx as the binding phase). Although cause and effect could not be established because of covariance with alkalinity (p = 0.08), water hardness correlated strongly (r(2)  = 0.998, p minor and highlight the importance of chemical speciation in Pb-based risk assessments for aquatic macrophytes. © 2014 SETAC.

  3. Development and performance test results of 50 kA vapor-cooled current lead for ITER

    Sugimoto, Makoto; Isono, Takaaki; Hamada, Kazuya

    1998-01-01

    JAERI has developed 50 kA current leads for the International Thermonuclear Experimental Reactor (ITER). The Center Solenoid (CS) Model Coil program is under way by means of international collaboration in ITER-EDA. The CS model coil is being developed for ITER CS coil and is for demonstration for ITER construction. The performance test of the CS model coil will be carried out at the JAERI ITER common test facility (CTF). The current lead consists of the vertical lead and the connection lead. The vertical lead is a vapor-cooled type and has a cable-in-conduit geometry. The vertical lead was designed with a heat leak of 1.2 W/kA at a helium flow rate of 0.06 g/(s·kA). The measured heat leak satisfied the designed value. The connection lead was made from copper pipe soldered with NbTi superconducting wires. The pipe was stabilized by the superconducting wires and a cooling channel. The current lead was operated up to 60 kA. The design and the performance test results of 50 kA current leads are reported. The results meet the specifications for the CS model coil test and for the ITER real machine. (author)

  4. [The umbilical blood levels of lead and some other toxic metals as a biomarker of environment-induced exposure].

    Privalova, L I; Malykh, O L; Matiukhina, G V; Gnezdilova, S V

    2007-01-01

    Groups of pregnant women, which made up in Revda, Pervouralsk, Krasnouralsk, and Verkh-Isetsky District of Yekaterinburg, were studied. Tests of umbilical blood samples (UB) for the levels of calcium, iron, chromium, manganese, zinc, nickel, cadmium, lead, arsenic, copper, and mercury have established that the mean concentration of lead and the proportion of samples with elevated UB lead concentrations depend on how close the residential area is located to the major industrial source of emission of this toxic metal into ambient air. This correlation is less marked for other metals or it is not found. The particular position of lead is likely to be explained by the fact that it is entirely foreign to an organism and by the comparative unimportance of a contribution of the sources of exposure to this metal, which are unassociated with man-caused environmental and food pollution. As far as other metals are concerned, the situation is complicated by the fact that they are not only toxic, but when upon minor exposures, also essential biotrace elements with controlled and interdependent toxic kinetics. It is also shown that when a pregnant woman takes a complex of biological protectors promoting a reduction in her body's levels of lead, its concentrations in her body, its UB concentration is much lower than such a bioprophylactic effect is absent.

  5. Development of high current electron source using photoemission from metals with ultrashort laser pulses

    Tsang, T.; Srinivasan-Rao, T.; Fischer, J.

    1990-10-01

    We summarize the studies of photoemission from metal photocathodes using picosecond pulses in the UV (4.66 eV) wavelength and femtosecond laser pulses in the visible (2 eV) wavelengths. To achieve high current density yield from metal photocathodes, multiphoton photoemission using femtosecond laser pulses are suggested. Electron yield improvement incorporating surface photoemission and surface plasmon resonance in metals and metal films are demonstrated. We examine the possibility of the nonlinear photoemission process overtaking the linear process, and identity some possible complexity. To extract the large amount of electrons free of space charge, a pulsed high voltage is designed; the results of the preliminary test are presented. Finally, for the first time, the width of the electron temporal profiles are measured, utilizing the nonlinear photoelectric effect, to below 100 fsec time regime. The results indicated that the electron pulse duration follows the laser pulses and are not limited by the material. 8 refs., 15 figs

  6. Effects of pulse current on energy consumption and removal of heavy metals during electrodialytic soil remediation

    Sun, Tian R.; Ottosen, Lisbeth M.

    2012-01-01

    industrially polluted soils were performed. At a current density of 0.1mA/cm2 in soil 1 and 0.2mA/cm2 in soil 2, there was no difference on energy consumption and removal of heavy metals between pulse current and constant current experiments, but at higher current experiments (i.e., 0.2mA/cm2 in soil 1 and 0......The aims of this paper were to investigate the possibility for energy saving when using a pulsed electric field during electrodialytic soil remediation (EDR) and the effect of the pulsed current on removal of heavy metals. Eight experiments with constant and pulse current in the different.......8mA/cm2 in soil 2) the energy was saved 67% and 60% and the removal of heavy metals was increased 17–76% and 31–51% by pulse current in soil 1 and soil 2, respectively. When comparing the voltage drop at different parts of EDR cells, it was found that the voltage drop of the area across cation...

  7. Trace Metals and Lead Isotopes in modern Sediments Near Rio de Janeiro, Brazil

    Boyle, E. A.; Lazzari, L.; Wagener, A. L.; Carreira, R.; Godoy, J. M.; Noble, A.; Carrasco, G. G.; Moos, S. B.

    2014-12-01

    This work focuses on the export of trace metals and combustion residues from land to ocean and on the Southeast continental margin of Brazil and its historical variability using stable lead isotopes. Two sediment cores were collected, one in highly impacted Guanabara Bay and the other on the Southeast continental shelf. Continental shelf samples were analyzed for trace element concentrations [Mn (117±50 ppm), Ni (6.5±2.3 ppm), Zn (5.0±1.5), (233±46 ppm), ], Pb (5.4±2.4 ppm), as well as Cu, Ag, Cd, Sr, Ba, Tl, U and Pb isotope ratios & Pb-210. Most of the elements show higher concentrations on the upper part of the core compared to the bottom. Downcore changes of the concentrations of these elements were similar. The sediments of adjacent rivers and bays around the upper section of the southeast continental shelf of Brazil are considered highly enriched with Pb, Zn, Cu and Cr such as Guanabara Bay, Sepetiba Bay and Paraíba do Sul River compared with the natural concentrations and other regions in the world. A [Pb] maximum is seen between samples from 24 to 43 cm (~8 ppm). Utilization of tetraethyl lead (TEL) gasoline in Brazil was phased out beginning in 1983 and was largely completed by 1988. Continental shelf Pb-206/Pb-207 varies between 1.174 near the core top to 1.190 at 100 cm, with a sharp difference between samples at 6 and 8 cm. Higher core top Pb, Zn, and Ni corroborate the recent anthropogenic influence on the southeast continental shelf of Brazil. For Guanabara Bay sediment samples [Pb] varies between 90 ppm near the top to 1 ppm at the bottom. Pb-206/Pb-207 varies between 1.161 near the core top to 1.165 near the bottom. Using triple isotope plots we can discern different sources of lead to the region and how these vary with time.

  8. Determining heavy metals in spent compact fluorescent lamps (CFLs) and their waste management challenges: some strategies for improving current conditions.

    Taghipour, Hassan; Amjad, Zahra; Jafarabadi, Mohamad Asghari; Gholampour, Akbar; Norouz, Prviz

    2014-07-01

    From environmental viewpoint, the most important advantage of compact fluorescent lamps (CFLs) is reduction of green house gas emissions. But their significant disadvantage is disposal of spent lamps because of containing a few milligrams of toxic metals, especially mercury and lead. For a successful implementation of any waste management plan, availability of sufficient and accurate information on quantities and compositions of the generated waste and current management conditions is a fundamental prerequisite. In this study, CFLs were selected among 20 different brands in Iran. Content of heavy metals including mercury, lead, nickel, arsenic and chromium was determined by inductive coupled plasma (ICP). Two cities, Tehran and Tabriz, were selected for assessing the current waste management condition of CFLs. The study found that waste generation amount of CFLs in the country was about 159.80, 183.82 and 153.75 million per year in 2010, 2011 and 2012, respectively. Waste generation rate of CFLs in Iran was determined to be 2.05 per person in 2012. The average amount of mercury, lead, nickel, arsenic and chromium was 0.417, 2.33, 0.064, 0.056 and 0.012 mg per lamp, respectively. Currently, waste of CFLs is disposed by municipal waste stream in waste landfills. For improving the current conditions, we propose by considering the successful experience of extended producer responsibility (EPR) in other electronic waste management. The EPR program with advanced recycling fee (ARF) is implemented for collecting and then recycling CFLs. For encouraging consumers to take the spent CFLs back at the end of the products' useful life, a proportion of ARF (for example, 50%) can be refunded. On the other hand, the government and Environmental Protection Agency should support and encourage recycling companies of CFLs both technically and financially in the first place. Copyright © 2014 Elsevier Ltd. All rights reserved.

  9. Modelling of Leakage Current Through Double Dielectric Gate Stack in Metal Oxide Semiconductor Capacitor

    Fatimah A Noor; Mikrajuddin Abdullah; Sukirno; Khairurrijal

    2008-01-01

    In this paper, we have derived analytical expression of leakage current through double barriers in Metal Oxide Semiconductor (MOS) capacitor. Initially, electron transmittance through the MOS capacitor was derived by including the coupling between the transverse and longitudinal energies. The transmittance was then employed to obtain leakage current through the double barrier. In this model, we observed the effect of electron velocity due to the coupling effect and the oxide thickness to the leakage current. The calculated results showed that the leakage current decreases as the electron velocity increases. (author)

  10. Leading research on super metal. 2. Aluminium materials; Super metal no sendo kenkyu. 2. Ogata sozai (aluminium kei)

    NONE

    1996-03-01

    Aluminum materials were surveyed to improve aluminum materials drastically so as to play an important role as prospective materials in response to the changing social environment. Aluminum materials have become the following metal materials to iron materials due to their light weight, durability, and profitability. Based on their merits and demerits, it was made clear how the aluminum materials contribute to the future resource saving, energy saving, and global environmental protection. Review was made on the two research and development themes which contribute to the creation of super metals. Hence, the themes proposed are focused on the creation of new aluminum mill products with ultra fine grain structure using very low temperature processing and on the creation of super-formability aluminum alloy sheets by advanced texture control using processing which can enhance the shearing stress. Results of the research and development are expected to provide wide applicability for other metals, ceramics, and polymers. 433 refs., 315 figs., 56 tabs.

  11. Determining heavy metals in spent compact fluorescent lamps (CFLs) and their waste management challenges: Some strategies for improving current conditions

    Taghipour, Hassan; Amjad, Zahra; Jafarabadi, Mohamad Asghari; Gholampour, Akbar; Norouz, Prviz

    2014-01-01

    Highlights: • Heavy metals in spent compact fluorescent lamps (CFLs) determined. • Current waste management condition of CFLs in Iran assessed. • Currently, waste of CFLs is disposed by municipal waste stream in waste landfills. • We propose extended producer responsibility (EPR) for CFLs waste management. - Abstract: From environmental viewpoint, the most important advantage of compact fluorescent lamps (CFLs) is reduction of green house gas emissions. But their significant disadvantage is disposal of spent lamps because of containing a few milligrams of toxic metals, especially mercury and lead. For a successful implementation of any waste management plan, availability of sufficient and accurate information on quantities and compositions of the generated waste and current management conditions is a fundamental prerequisite. In this study, CFLs were selected among 20 different brands in Iran. Content of heavy metals including mercury, lead, nickel, arsenic and chromium was determined by inductive coupled plasma (ICP). Two cities, Tehran and Tabriz, were selected for assessing the current waste management condition of CFLs. The study found that waste generation amount of CFLs in the country was about 159.80, 183.82 and 153.75 million per year in 2010, 2011 and 2012, respectively. Waste generation rate of CFLs in Iran was determined to be 2.05 per person in 2012. The average amount of mercury, lead, nickel, arsenic and chromium was 0.417, 2.33, 0.064, 0.056 and 0.012 mg per lamp, respectively. Currently, waste of CFLs is disposed by municipal waste stream in waste landfills. For improving the current conditions, we propose by considering the successful experience of extended producer responsibility (EPR) in other electronic waste management. The EPR program with advanced recycling fee (ARF) is implemented for collecting and then recycling CFLs. For encouraging consumers to take the spent CFLs back at the end of the products’ useful life, a proportion of

  12. Determining heavy metals in spent compact fluorescent lamps (CFLs) and their waste management challenges: Some strategies for improving current conditions

    Taghipour, Hassan, E-mail: hteir@yahoo.com [Department of Environmental Health Engineering, Tabriz University of Medical Sciences, Tabriz (Iran, Islamic Republic of); Amjad, Zahra [Student Research Committee, Department of Environmental Health Engineering, Tabriz University of Medical Sciences, Tabriz (Iran, Islamic Republic of); Jafarabadi, Mohamad Asghari [Medical Education Research Center, Department of Statistics and Epidemiology, Tabriz University of Medical Sciences, Tabriz (Iran, Islamic Republic of); Gholampour, Akbar [Department of Environmental Health Engineering, Tabriz University of Medical Sciences, Tabriz (Iran, Islamic Republic of); Norouz, Prviz [Environmental Health Engineering, Shahid Beheshti University of Medical Sciences, Tehran (Iran, Islamic Republic of)

    2014-07-15

    Highlights: • Heavy metals in spent compact fluorescent lamps (CFLs) determined. • Current waste management condition of CFLs in Iran assessed. • Currently, waste of CFLs is disposed by municipal waste stream in waste landfills. • We propose extended producer responsibility (EPR) for CFLs waste management. - Abstract: From environmental viewpoint, the most important advantage of compact fluorescent lamps (CFLs) is reduction of green house gas emissions. But their significant disadvantage is disposal of spent lamps because of containing a few milligrams of toxic metals, especially mercury and lead. For a successful implementation of any waste management plan, availability of sufficient and accurate information on quantities and compositions of the generated waste and current management conditions is a fundamental prerequisite. In this study, CFLs were selected among 20 different brands in Iran. Content of heavy metals including mercury, lead, nickel, arsenic and chromium was determined by inductive coupled plasma (ICP). Two cities, Tehran and Tabriz, were selected for assessing the current waste management condition of CFLs. The study found that waste generation amount of CFLs in the country was about 159.80, 183.82 and 153.75 million per year in 2010, 2011 and 2012, respectively. Waste generation rate of CFLs in Iran was determined to be 2.05 per person in 2012. The average amount of mercury, lead, nickel, arsenic and chromium was 0.417, 2.33, 0.064, 0.056 and 0.012 mg per lamp, respectively. Currently, waste of CFLs is disposed by municipal waste stream in waste landfills. For improving the current conditions, we propose by considering the successful experience of extended producer responsibility (EPR) in other electronic waste management. The EPR program with advanced recycling fee (ARF) is implemented for collecting and then recycling CFLs. For encouraging consumers to take the spent CFLs back at the end of the products’ useful life, a proportion of

  13. Effect of copper and lead on two consortia of phototrophic microorganisms and their capacity to sequester metals

    Burgos, A. [Departament de Genètica i Microbiologia, Universitat Autònoma de Barcelona, Edifici C, Campus de UAB, Bellaterra (Cerdanyola del Vallès), 08193 Barcelona (Spain); Departamento de Recursos Hidrobiológicos, Universidad de Nariño, Pasto (N) (Colombia); Maldonado, J. [Departament de Genètica i Microbiologia, Universitat Autònoma de Barcelona, Edifici C, Campus de UAB, Bellaterra (Cerdanyola del Vallès), 08193 Barcelona (Spain); De los Rios, A. [Museo Nacional de Ciencias Naturales(CSIC), Serrano 115 dpdo, 28006 Madrid (Spain); Solé, A. [Departament de Genètica i Microbiologia, Universitat Autònoma de Barcelona, Edifici C, Campus de UAB, Bellaterra (Cerdanyola del Vallès), 08193 Barcelona (Spain); Esteve, I., E-mail: isabel.esteve@uab.cat [Departament de Genètica i Microbiologia, Universitat Autònoma de Barcelona, Edifici C, Campus de UAB, Bellaterra (Cerdanyola del Vallès), 08193 Barcelona (Spain); Departamento de Recursos Hidrobiológicos, Universidad de Nariño, Pasto (N) (Colombia); Museo Nacional de Ciencias Naturales(CSIC), Serrano 115 dpdo, 28006 Madrid (Spain)

    2013-09-15

    Highlights: •We studied the tolerance-resistance of phototrophic microorganisms to copper and lead. •We determined the capacity of consortia of microorganisms to sequester copper and lead. •CLSM-λscan is a technique for evaluating in vivo effect of metals on microorganisms. •SEM-EDX and TEM-EDX determined the capacity of microorganisms to sequester metals. -- Abstract: The roles of consortia of phototrophic microorganisms have been investigated in this paper to determine their potential role to tolerate or resist metals and to capture them from polluted cultures. With this purpose, two consortia of microorganisms: on one hand, Geitlerinema sp. DE2011 (Ge) and Scenedesmus sp. DE2009 (Sc) (both identified in this paper by molecular biology methods) isolated from Ebro Delta microbial mats, and on the other, Spirulina sp. PCC 6313 (Sp) and Chroococcus sp. PCC 9106 (Ch), from Pasteur culture collection were polluted with copper and lead. In order to analyze the ability of these consortia to tolerate and capture metals, copper and lead were selected, because both have been detected in Ebro Delta microbial mats. The tolerance-resistance to copper and lead for both consortia was determined in vivo and at cellular level by Confocal Laser Scanning Microscopy (CLSM-λscan function). The results obtained demonstrate that both consortia are highly tolerant-resistant to lead and that the limits between the copper concentration having cytotoxic effect and that having an essential effect are very close in these microorganisms. The capacity of both consortia to capture extra- and intracellular copper and lead was determined by Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM) respectively, coupled to an Energy Dispersive X-ray detector (EDX). The results showed that all the microorganisms assayed were able to capture copper extracellularly in the extrapolymeric substances, and lead extra- and intracellularly in polyphosphate inclusions. Moreover

  14. Effect of copper and lead on two consortia of phototrophic microorganisms and their capacity to sequester metals

    Burgos, A.; Maldonado, J.; De los Rios, A.; Solé, A.; Esteve, I.

    2013-01-01

    Highlights: •We studied the tolerance-resistance of phototrophic microorganisms to copper and lead. •We determined the capacity of consortia of microorganisms to sequester copper and lead. •CLSM-λscan is a technique for evaluating in vivo effect of metals on microorganisms. •SEM-EDX and TEM-EDX determined the capacity of microorganisms to sequester metals. -- Abstract: The roles of consortia of phototrophic microorganisms have been investigated in this paper to determine their potential role to tolerate or resist metals and to capture them from polluted cultures. With this purpose, two consortia of microorganisms: on one hand, Geitlerinema sp. DE2011 (Ge) and Scenedesmus sp. DE2009 (Sc) (both identified in this paper by molecular biology methods) isolated from Ebro Delta microbial mats, and on the other, Spirulina sp. PCC 6313 (Sp) and Chroococcus sp. PCC 9106 (Ch), from Pasteur culture collection were polluted with copper and lead. In order to analyze the ability of these consortia to tolerate and capture metals, copper and lead were selected, because both have been detected in Ebro Delta microbial mats. The tolerance-resistance to copper and lead for both consortia was determined in vivo and at cellular level by Confocal Laser Scanning Microscopy (CLSM-λscan function). The results obtained demonstrate that both consortia are highly tolerant-resistant to lead and that the limits between the copper concentration having cytotoxic effect and that having an essential effect are very close in these microorganisms. The capacity of both consortia to capture extra- and intracellular copper and lead was determined by Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM) respectively, coupled to an Energy Dispersive X-ray detector (EDX). The results showed that all the microorganisms assayed were able to capture copper extracellularly in the extrapolymeric substances, and lead extra- and intracellularly in polyphosphate inclusions. Moreover

  15. Simulation studies of current transport in metal-insulator-semiconductor Schottky barrier diodes

    Chand, Subhash; Bala, Saroj

    2007-01-01

    The current-voltage characteristics of Schottky diodes with an interfacial insulator layer are analysed by numerical simulation. The current-voltage data of the metal-insulator-semiconductor Schottky diode are simulated using thermionic emission diffusion (TED) equation taking into account an interfacial layer parameter. The calculated current-voltage data are fitted into ideal TED equation to see the apparent effect of interfacial layer parameters on current transport. Results obtained from the simulation studies shows that with mere presence of an interfacial layer at the metal-semiconductor interface the Schottky contact behave as an ideal diode of apparently high barrier height (BH), but with same ideality factor and series resistance as considered for a pure Schottky contact without an interfacial layer. This apparent BH decreases linearly with decreasing temperature. The effects giving rise to high ideality factor in metal-insulator-semiconductor diode are analysed. Reasons for observed temperature dependence of ideality factor in experimentally fabricated metal-insulator-semiconductor diodes are analysed and possible mechanisms are discussed

  16. Hybrid input-output approach to metal production and its application to the introduction of lead-free solders.

    Nakamura, Shinichiro; Murakami, Shinsuke; Nakajima, Kenichi; Nagasaka, Tetsuya

    2008-05-15

    The production process of metals such as copper, lead, and zinc is characterized by mutual interconnections and interdependence, as well as by the occurrence of a large number of byproducts, which include precious or rare metals, such as gold, silver, bismuth, and indium. On the basis of the framework of waste input-output (WIO), we present a hybrid 10 model that takes full account of the mutual interdependence among the metal production processes and the interdependence between them and all the other production sectors of the economy as well. The combination of a comprehensive representation of the whole national economy and the introduction of process knowledge of metal production allows for a detailed analysis of different materials-use scenarios under the consideration of full supply chain effects. For illustration, a hypothetical case study of the introduction of lead-free solder involving the production of silver as a byproduct of copper and lead smelting processes was developed and implemented using Japanese data. To meet the increased demand for the recovery and recycling of silver resources from end-of-life products, the final destination of metal silver in terms of products and user categories was estimated, and the target components with the highest silver concentration were identified.

  17. Effect of copper and lead on two consortia of phototrophic microorganisms and their capacity to sequester metals.

    Burgos, A; Maldonado, J; De Los Rios, A; Solé, A; Esteve, I

    2013-09-15

    The roles of consortia of phototrophic microorganisms have been investigated in this paper to determine their potential role to tolerate or resist metals and to capture them from polluted cultures. With this purpose, two consortia of microorganisms: on one hand, Geitlerinema sp. DE2011 (Ge) and Scenedesmus sp. DE2009 (Sc) (both identified in this paper by molecular biology methods) isolated from Ebro Delta microbial mats, and on the other, Spirulina sp. PCC 6313 (Sp) and Chroococcus sp. PCC 9106 (Ch), from Pasteur culture collection were polluted with copper and lead. In order to analyze the ability of these consortia to tolerate and capture metals, copper and lead were selected, because both have been detected in Ebro Delta microbial mats. The tolerance-resistance to copper and lead for both consortia was determined in vivo and at cellular level by Confocal Laser Scanning Microscopy (CLSM-λscan function). The results obtained demonstrate that both consortia are highly tolerant-resistant to lead and that the limits between the copper concentration having cytotoxic effect and that having an essential effect are very close in these microorganisms. The capacity of both consortia to capture extra- and intracellular copper and lead was determined by Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM) respectively, coupled to an Energy Dispersive X-ray detector (EDX). The results showed that all the microorganisms assayed were able to capture copper extracellularly in the extrapolymeric substances, and lead extra- and intracellularly in polyphosphate inclusions. Moreover, the studied micro-organisms did not exert any inhibitory effect on each other's metal binding capacity. From the results obtained in this paper, it can be concluded that consortia of phototrophic microorganisms could play a very important role in biorepairing sediments polluted by metals, as a result of their ability to tolerate or resist high concentrations of metals and to

  18. Leading research on next generation metal production technology; Jisedai kinzoku shigen seisan gijutsu no sendo kenkyu

    NONE

    1997-03-01

    The energy saving environment-friendly technology for low- grade difficult-to-process ores was researched focusing attention on the hydro-metallurgical process of non-ferrous metals. This research aims at development of both effective leaching system of metals, and separation/crystallization system recognizing the property difference between metal ions in solution. The leaching system allows the inexpensive molecular level control of electron transfer, mass transfer of metal ions and stabilization of leached metal ions in a solid/liquid interface. The system thus allows selective leaching of metals from various resources such as difficult- to-leach sulfide minerals to prepare concentrated solutions. The separation system can obtain high-purity solutions including each metal ion by advanced separation/concentration technology from the solutions. The crystallization technology (including electrolysis) is developed for preparing target metal materials by molecular level control of nucleation, particle growth, thin film formation and bulky metal formation processes. Overall energy consumption is reduced to 1/3 of that of the pyro-metallurgical method, aiming at zero emission. 15 refs., 14 figs., 11 tabs.

  19. Metal and metalloid foliar uptake by various plant species exposed to atmospheric industrial fallout: Mechanisms involved for lead

    Schreck, E., E-mail: eva.schreck@ensat.fr [Universite de Toulouse (France); INP, UPS (France); EcoLab (Laboratoire Ecologie Fonctionnelle et Environnement) (France); ENSAT, Avenue de l' Agrobiopole, 31326 Castanet Tolosan (France); CNRS (France); EcoLab, 31326 Castanet Tolosan (France); Foucault, Y. [Universite de Toulouse (France); INP, UPS (France); EcoLab (Laboratoire Ecologie Fonctionnelle et Environnement) (France); ENSAT, Avenue de l' Agrobiopole, 31326 Castanet Tolosan (France); CNRS (France); EcoLab, 31326 Castanet Tolosan (France); STCM, Societe de Traitements Chimiques des Metaux, 30 Avenue de Fondeyre 31200 Toulouse (France); Sarret, G. [ISTerre (UMR 5275), Universite J. Fourier and CNRS, BP 53, 38041 Grenoble cedex 9 (France); Sobanska, S. [LASIR (UMR CNRS 8516), Universite de Lille 1, Bat. C5, 59655 Villeneuve d' Ascq cedex (France); Cecillon, L. [ISTerre (UMR 5275), Universite J. Fourier and CNRS, BP 53, 38041 Grenoble cedex 9 (France); Castrec-Rouelle, M. [Universite Pierre and Marie Curie (UPMC-Paris 6), Bioemco (Biogeochimie et Ecologie des Milieux Continentaux), Site Jussieu, Tour 56, 4 Place Jussieu, 75252 Paris cedex 05 (France); Uzu, G. [Laboratoire d' Aerologie (UMR 5560), OMP, UPS 14, Avenue Edouard Belin, 31400 Toulouse (France); GET (UMR 5563), IRD, 14, Avenue Edouard Belin, 31400 Toulouse (France); Dumat, C. [Universite de Toulouse (France); INP, UPS (France); EcoLab (Laboratoire Ecologie Fonctionnelle et Environnement) (France); ENSAT, Avenue de l' Agrobiopole, 31326 Castanet Tolosan (France); CNRS (France); EcoLab, 31326 Castanet Tolosan (France)

    2012-06-15

    Fine and ultrafine metallic particulate matters (PMs) are emitted from metallurgic activities in peri-urban zones into the atmosphere and can be deposited in terrestrial ecosystems. The foliar transfer of metals and metalloids and their fate in plant leaves remain unclear, although this way of penetration may be a major contributor to the transfer of metals into plants. This study focused on the foliar uptake of various metals and metalloids from enriched PM (Cu, Zn, Cd, Sn, Sb, As, and especially lead (Pb)) resulting from the emissions of a battery-recycling factory. Metal and metalloid foliar uptake by various vegetable species, exhibiting different morphologies, use (food or fodder) and life-cycle (lettuce, parsley and rye-grass) were studied. The mechanisms involved in foliar metal transfer from atmospheric particulate matter fallout, using lead (Pb) as a model element was also investigated. Several complementary techniques (micro-X-ray fluorescence, scanning electron microscopy coupled with energy dispersive X-ray microanalysis and time-of-flight secondary ion mass spectrometry) were used to investigate the localization and the speciation of lead in their edible parts, i.e. leaves. The results showed lead-enriched PM on the surface of plant leaves. Biogeochemical transformations occurred on the leaf surfaces with the formation of lead secondary species (PbCO{sub 3} and organic Pb). Some compounds were internalized in their primary form (PbSO{sub 4}) underneath an organic layer. Internalization through the cuticle or penetration through stomata openings are proposed as two major mechanisms involved in foliar uptake of particulate matter. - Graphical abstract: Overall picture of performed observations and mechanisms potentially involved in lead foliar uptake. Highlights: Black-Right-Pointing-Pointer Foliar uptake of metallic particulate matter (PM) is of environmental and health concerns. Black-Right-Pointing-Pointer The leaf morphology influences the adsorption

  20. Heavy Metals (Mercury, Lead and Cadmium Determination in 17 Species of Fish Marketed in Khorramabad City, West of Iran

    Ali Mortazavi

    2016-01-01

    Full Text Available Heavy metals entrance to fish body tissues and transferring to human body systems after their consuming makes numerous undesirable effects and health problems. The aim of this study was to determine some heavy metals (lead, cadmium and mercury in fresh fishes marketed in Khorramabad City, west of Iran. In this descriptive study, five samples of 17 fish species with high consumption were purchased randomly in 2014. Measurement of mercury, lead and cadmium was performed using atomic absorption spectrometry. All measurements were performed three times for each sample. Lead mean levels in fish samples was in the range 0.736 -1.005 ppm, cadmium range was from 0.196 to 0.015 ppm and mean content of mercury was  0.431 - 0.107 ppm. At present mean concentration of lead, mercury and cadmium in supplied fishes muscle is lower than maximum recommended levels according to WHO, EC and FDA guidelines. Based on the obtained results of this study and the importance of heavy metals in foods and their impacts on human health, continuous monitoring of heavy metals levels in foods is necessary.

  1. Lead and other heavy metals in stream sediments in the area of Meža valley

    Julija Fux

    2007-12-01

    Full Text Available In the Meža valley, lead – zinc ore has been exploited and processed for more than 300 years, which has strongly influenced the environment.Previous investigation shave shown increased concentrations of lead and some other metals. At the end of the 20th century, the Meža River was considered a stream with the highest concentrations of heavy metals in Slovenia.When the mine and processing plants ceased to operate, the direct transfer of heavy metals into the environment has strongly decreased. However, the deposits of poor ore and wastes from ore processing have remained as an indirect source of heavy metal pollution. From those places heavy metals have been washed out into the nearby streams, and carried into the Meža River and further into the Drava River. Chemical analysis of the Meža River and its tributaries has shown heavy pollution of the upper Meža River sediments with lead, zinc, molybdenum and cadmium, and partly with arsenic. In the lower Meža valley, those concentrations are mildly decreased. Concentrations of cobalt, chrome, copper and nickel are increased in the area around Ravne as a result of the ironworks industry. Mušenik and Jančarjev potok, both tributaries of the Meža River, contribute a high portion of heavy metal load to the Meža River. A specific case is Helenski potok,in which the concentrations of heavy metals strongly surpass the concentrations measured at all other locations. Although more than 10 years have passed since the mine and ore processing plant in the upper Meža valley were closed, the production has ceased and the rehabilitation measures have been taken, the environment in the upper Meža valley is still highly polluted.

  2. The ancient Romans knew that lead is a dangerous metal but they tolerated it: Is it happening even today?

    Sič Magdolna

    2011-01-01

    Full Text Available In ancient Rome lead was used frequently. The most exposed to the noxiousness of lead were the miners and the workers that were treating the metal. The Romans noticed the lead caused illness with miners, but they nevertheless thought that small amounts of lead do not jeopardize the life of the rest of the population. Moreover, they used lead even for medical treatments. The ancient Romans were not conscious enough about the level of harmfulness of this metal for everyone's health, even for the wealthiest. New scientific methods proved a high level of environmental lead pollution at the time of the Roman Empire. Today, as the harmfulness of lead is scientifically proved, and is therefore eliminated as an addition to petrol. Moreover, most developed countries strive towards further elimination of lead from the environment. Serbia is only at the beginning of this process. Having in mind that in taking actions for the protection of environment we stay behind many countries, we should not take it only as part of the harmonization process with EU law, but as a common task that is in the interests of all.

  3. A Study of Heavy Metal Pollution in China: Current Status, Pollution-Control Policies and Countermeasures

    Hui Hu

    2014-09-01

    Full Text Available In the past 30 years, China’s economy has experienced rapid development, which led to a vast increase in energy consumption and serious environmental pollution. Among the different types of pollution, heavy metal pollution has become one of the major environmental issues in China. A number of studies show that high level of heavy metal exposure is a frequent cause of permanent intellectual and developmental disabilities. In recent years, some traditional pollutants, such as sulfur dioxide and carbon dioxide, have been put under control in China. However, heavy metal pollution, which poses even greater risks to public health and sustainable development, has yet to gain policymakers’ attention. The purpose of this paper is to explore effective countermeasures for heavy metal pollution in China. The present study reviews the current status of China’s heavy metal pollution and analyzes related public policies and countermeasures against that pollution. It also presents a few recommendations and measures for prevention of heavy metal pollution.

  4. Impact ionization processes in the steady state of a driven Mott-insulating layer coupled to metallic leads

    Sorantin, Max E.; Dorda, Antonius; Held, Karsten; Arrigoni, Enrico

    2018-03-01

    We study a simple model of photovoltaic energy harvesting across a Mott-insulating gap consisting of a correlated layer connected to two metallic leads held at different chemical potentials. We address, in particular, the issue of impact ionization, whereby a particle photoexcited to the high-energy part of the upper Hubbard band uses its extra energy to produce a second particle-hole excitation. We find a drastic increase of the photocurrent upon entering the frequency regime where impact ionization is possible. At large values of the Mott gap, where impact ionization is energetically not allowed, we observe a suppression of the current and a piling up of charge in the high-energy part of the upper Hubbard band. Our study is based on a Floquet dynamical mean-field theory treatment of the steady state with the so-called auxiliary master equation approach as impurity solver. We verify that an additional approximation, taking the self-energy diagonal in the Floquet indices, is appropriate for the parameter range we are considering.

  5. Trace metal inventories and lead isotopic composition chronicle a forest fire's remobilization of industrial contaminants deposited in the angeles national forest.

    Odigie, Kingsley O; Flegal, A Russell

    2014-01-01

    The amounts of labile trace metals: [Co] (3 to 11 µg g-1), [Cu] (15 to 69 µg g-1), [Ni] (6 to 15 µg g-1), [Pb] (7 to 42 µg g-1), and [Zn] (65 to 500 µg g-1) in ash collected from the 2012 Williams Fire in Los Angeles, California attest to the role of fires in remobilizing industrial metals deposited in forests. These remobilized trace metals may be dispersed by winds, increasing human exposures, and they may be deposited in water bodies, increasing exposures in aquatic ecosystems. Correlations between the concentrations of these trace metals, normalized to Fe, in ash from the fire suggest that Co, Cu, and Ni in most of those samples were predominantly from natural sources, whereas Pb and Zn were enriched in some ash samples. The predominantly anthropogenic source of excess Pb in the ash was further demonstrated by its isotopic ratios (208Pb/207Pb: 206Pb/207Pb) that fell between those of natural Pb and leaded gasoline sold in California during the previous century. These analyses substantiate current human and environmental health concerns with the pyrogenic remobilization of toxic metals, which are compounded by projections of increases in the intensity and frequency of wildfires associated with climate change.

  6. Trace metal inventories and lead isotopic composition chronicle a forest fire's remobilization of industrial contaminants deposited in the angeles national forest.

    Kingsley O Odigie

    Full Text Available The amounts of labile trace metals: [Co] (3 to 11 µg g-1, [Cu] (15 to 69 µg g-1, [Ni] (6 to 15 µg g-1, [Pb] (7 to 42 µg g-1, and [Zn] (65 to 500 µg g-1 in ash collected from the 2012 Williams Fire in Los Angeles, California attest to the role of fires in remobilizing industrial metals deposited in forests. These remobilized trace metals may be dispersed by winds, increasing human exposures, and they may be deposited in water bodies, increasing exposures in aquatic ecosystems. Correlations between the concentrations of these trace metals, normalized to Fe, in ash from the fire suggest that Co, Cu, and Ni in most of those samples were predominantly from natural sources, whereas Pb and Zn were enriched in some ash samples. The predominantly anthropogenic source of excess Pb in the ash was further demonstrated by its isotopic ratios (208Pb/207Pb: 206Pb/207Pb that fell between those of natural Pb and leaded gasoline sold in California during the previous century. These analyses substantiate current human and environmental health concerns with the pyrogenic remobilization of toxic metals, which are compounded by projections of increases in the intensity and frequency of wildfires associated with climate change.

  7. Trace Metal Inventories and Lead Isotopic Composition Chronicle a Forest Fire’s Remobilization of Industrial Contaminants Deposited in the Angeles National Forest

    Odigie, Kingsley O.; Flegal, A. Russell

    2014-01-01

    The amounts of labile trace metals: [Co] (3 to 11 µg g−1), [Cu] (15 to 69 µg g−1), [Ni] (6 to 15 µg g−1), [Pb] (7 to 42 µg g−1), and [Zn] (65 to 500 µg g−1) in ash collected from the 2012 Williams Fire in Los Angeles, California attest to the role of fires in remobilizing industrial metals deposited in forests. These remobilized trace metals may be dispersed by winds, increasing human exposures, and they may be deposited in water bodies, increasing exposures in aquatic ecosystems. Correlations between the concentrations of these trace metals, normalized to Fe, in ash from the fire suggest that Co, Cu, and Ni in most of those samples were predominantly from natural sources, whereas Pb and Zn were enriched in some ash samples. The predominantly anthropogenic source of excess Pb in the ash was further demonstrated by its isotopic ratios (208Pb/207Pb: 206Pb/207Pb) that fell between those of natural Pb and leaded gasoline sold in California during the previous century. These analyses substantiate current human and environmental health concerns with the pyrogenic remobilization of toxic metals, which are compounded by projections of increases in the intensity and frequency of wildfires associated with climate change. PMID:25259524

  8. Limets 2: a hot-cell test set-up for Liquid Metal Embrittlement (LME) studies in liquid lead alloys

    Van den Bosch, J.; Bosch, R.W.; Al Mazouzi, A.

    2008-01-01

    Full text of publication follows. In the nuclear energy sector one of the main candidate designs for the accelerator driven system (ADS) uses liquid lead or lead bismuth eutectic both as a coolant and as spallation target. In the fusion community liquid lead lithium eutectic is considered as a possible coolant for the blanket and as a tritium source. Therefore the candidate materials for such structural components should not only comply with the operating conditions but in addition need to guarantee chemical and physical integrity when coming into contact with the lead alloys. The latter phenomena can be manifested in terms of erosion/corrosion. and/or of the so called liquid metal embrittlement (LME). Thus the susceptibility to LME of the structural materials under consideration to be used in such applications should be investigated in contact with the various lead alloys. LME, if occurring in any solid metal/liquid meta] couple, is likely to increase with irradiation hardening as localised stresses and crack initiations can promote it. To investigate the mechanical response of irradiated materials in contact with a liquid metal under representative conditions, a dedicated testing facility has recently been developed and built at our centre. It consists of an instrumented hot cell. equipped with a testing machine that allows mechanical testing of active materials in contact with active liquid lead lithium and liquid lead bismuth under well controlled chemistry conditions. The specificity of the installation is to handle highly activated and contaminated samples. Also a dedicated dismantling set-up has been developed that allows to retrieve the samples from the irradiation rig without any supplementary damage. In this presentation we will focus on the technical design of this new installation, its special features that have been developed to allow testing in a hot environment and the modifications and actions that have been taken to allow testing in liquid lead

  9. Current Problems and Possible Solutions in High-Temperature Lead-Free Soldering

    Kroupa, Aleš; Andersson, D.; Hoo, N.; Pearce, J.; Watson, A.; Dinsdale, A.; Mucklejohn, S.

    2012-01-01

    Roč. 21, č. 5 (2012), s. 629-637 ISSN 1059-9495 Institutional support: RVO:68081723 Keywords : lead-free soldering, * materials for high-temperature LF * new technologies for HT lead-free soldering Subject RIV: BJ - Thermodynamics Impact factor: 0.915, year: 2012

  10. Glazed clay pottery and lead exposure in Mexico: Current experimental evidence.

    Diaz-Ruiz, Araceli; Tristán-López, Luis Antonio; Medrano-Gómez, Karen Itzel; Torres-Domínguez, Juan Alejandro; Ríos, Camilo; Montes, Sergio

    2017-11-01

    Lead exposure remains a significant environmental problem; lead is neurotoxic, especially in developing humans. In Mexico, lead in human blood is still a concern. Historically, much of the lead exposure is attributed to the use of handcrafted clay pottery for cooking, storing and serving food. However, experimental cause-and-effect demonstration is lacking. The present study explores this issue with a prospective experimental approach. We used handcrafted clay containers to prepare and store lemonade, which was supplied as drinking water to pregnant rats throughout the gestational period. We found that clay pots, jars, and mugs leached on average 200 µg/l lead, and exposure to the lemonade resulted in 2.5 µg/dl of lead in the pregnant rats' blood. Neonates also showed increased lead content in the hippocampus and cerebellum. Caspase-3 activity was found to be statistically increased in the hippocampus in prenatally exposed neonates, suggesting increased apoptosis in that brain region. Glazed ceramics are still an important source of lead exposure in Mexico, and our results confirm that pregnancy is a vulnerable period for brain development.

  11. Biosorption of Zinc (Zn) and lead (Pb) by metal resistant bacterial isolate from mining tail

    Bautista Hernandez, D. A.; Carranza Alvarado, M.; Fernandez Linares, L.; Ramirez Landy, I.

    2009-07-01

    The use of microbial biomass in the removal of metals in solution, mainly of low concentrations (100 mg L{sup -}1), present advantages in relation to the physicochemical methods. The resistant microorganisms are potential bio sorbents. The objective of the present study was the isolation, starting from mining tail, of strains with capacity of metal bio sorption (Zn and Pb). (Author)

  12. Biosorption of Zinc (Zn) and lead (Pb) by metal resistant bacterial isolate from mining tail

    Bautista Hernandez, D. A.; Carranza Alvarado, M.; Fernandez Linares, L.; Ramirez Landy, I.

    2009-01-01

    The use of microbial biomass in the removal of metals in solution, mainly of low concentrations (100 mg L - 1), present advantages in relation to the physicochemical methods. The resistant microorganisms are potential bio sorbents. The objective of the present study was the isolation, starting from mining tail, of strains with capacity of metal bio sorption (Zn and Pb). (Author)

  13. A Pyoverdin Siderophore Produced By Pseudomonas aeruginosa CHL-004 Binds Lead And Other Heavy Metals

    Heavy metal pollution in soils, sediments and wastewater poses a significant environmental and public health threat due to toxicity and the potential for bioaccumulation in both plant and animal tissues. Remediation of heavy metals in soils and sediments using solely physical or...

  14. A Pyoverdin Siderophore Produced By Pseudomonas aeruginosa CHL-004 Binds Lead And Other Heavy Metals - (Poster)

    Heavy metal pollution in soils, sediments and wastewater poses a significant environmental and public health threat due to toxicity and the potential for bioaccumulation in both plant and animal tissues. Remediation of heavy metals in soils and sediments using solely physical or...

  15. Environmental arsenic, cadmium and lead dust emissions from metal mine operations: Implications for environmental management, monitoring and human health

    Taylor, Mark Patrick, E-mail: mark.taylor@mq.edu.au; Mould, Simon Anthony; Kristensen, Louise Jane; Rouillon, Marek

    2014-11-15

    Although blood lead values in children are predominantly falling globally, there are locations where lead exposure remains a persistent problem. One such location is Broken Hill, Australia, where the percentage of blood lead values >10 μg/dL in children aged 1–4 years has risen from 12.6% (2010), to 13% (2011) to 21% (2012). The purpose of this study was to determine the extent of metal contamination in places accessible to children. This study examines contemporary exposure risks from arsenic, cadmium, lead, silver and zinc in surface soil and dust, and in pre- and post-play hand wipes at six playgrounds across Broken Hill over a 5-day period in September 2013. Soil lead (mean 2,450 mg/kg) and zinc (mean 3,710 mg/kg) were the most elevated metals in playgrounds. Surface dust lead concentrations were consistently elevated (mean 27,500 μg/m{sup 2}) with the highest lead in surface dust (59,900 μg/m{sup 2}) and post-play hand wipes (60,900 μg/m{sup 2}) recorded close to existing mining operations. Surface and post-play hand wipe dust values exceeded national guidelines for lead and international benchmarks for arsenic, cadmium and lead. Lead isotopic compositions ({sup 206}Pb/{sup 207}Pb, {sup 208}Pb/{sup 207}Pb) of surface dust wipes from the playgrounds revealed the source of lead contamination to be indistinct from the local Broken Hill ore body. The data suggest frequent, cumulative and ongoing mine-derived dust metal contamination poses a serious risk of harm to children. - Highlights: 1.Playground soils and surface dust in a mining town have high metal concentrations. 2.Elevated levels of As, Cd, Pb and Zn dust are found on playground users′ hands. 3.Pb isotope analysis shows that the source of playground dust is ore body Pb. 4.Surface mine operations must be contained to reduce childhood lead exposure risks. 5.Mine environmental licences need to set trigger values for As, Cd, Pb and Zn dust.

  16. Environmental arsenic, cadmium and lead dust emissions from metal mine operations: Implications for environmental management, monitoring and human health

    Taylor, Mark Patrick; Mould, Simon Anthony; Kristensen, Louise Jane; Rouillon, Marek

    2014-01-01

    Although blood lead values in children are predominantly falling globally, there are locations where lead exposure remains a persistent problem. One such location is Broken Hill, Australia, where the percentage of blood lead values >10 μg/dL in children aged 1–4 years has risen from 12.6% (2010), to 13% (2011) to 21% (2012). The purpose of this study was to determine the extent of metal contamination in places accessible to children. This study examines contemporary exposure risks from arsenic, cadmium, lead, silver and zinc in surface soil and dust, and in pre- and post-play hand wipes at six playgrounds across Broken Hill over a 5-day period in September 2013. Soil lead (mean 2,450 mg/kg) and zinc (mean 3,710 mg/kg) were the most elevated metals in playgrounds. Surface dust lead concentrations were consistently elevated (mean 27,500 μg/m 2 ) with the highest lead in surface dust (59,900 μg/m 2 ) and post-play hand wipes (60,900 μg/m 2 ) recorded close to existing mining operations. Surface and post-play hand wipe dust values exceeded national guidelines for lead and international benchmarks for arsenic, cadmium and lead. Lead isotopic compositions ( 206 Pb/ 207 Pb, 208 Pb/ 207 Pb) of surface dust wipes from the playgrounds revealed the source of lead contamination to be indistinct from the local Broken Hill ore body. The data suggest frequent, cumulative and ongoing mine-derived dust metal contamination poses a serious risk of harm to children. - Highlights: 1.Playground soils and surface dust in a mining town have high metal concentrations. 2.Elevated levels of As, Cd, Pb and Zn dust are found on playground users′ hands. 3.Pb isotope analysis shows that the source of playground dust is ore body Pb. 4.Surface mine operations must be contained to reduce childhood lead exposure risks. 5.Mine environmental licences need to set trigger values for As, Cd, Pb and Zn dust

  17. Heavy metal multilayers for switching of magnetic unit via electrical current without magnetic field, method and applications

    Ma, Qinli; Li, Yufan; Chien, Chia-ling

    2018-02-20

    Provided is an electric-current-controllable magnetic unit, including: a substrate, an electric-current channel disposed on the substrate, the electric-current channel including a composite heavy-metal multilayer comprising at least one heavy-metal; a capping layer disposed over the electric-current channel; and at least one ferromagnetic layer disposed between the electric-current channel and the capping layer.

  18. The Metal Neurotoxins: An Important Role in Current Human Neural Epidemics?

    Keith Schofield

    2017-12-01

    Full Text Available Many published studies have illustrated that several of the present day neurological epidemics (autism, attention deficit disorder, Alzheimer’s cannot be correlated to any single neurotoxicant. However, the present scientific examination of the numerous global blood monitoring databases for adults that include the concentrations of the neurotoxic elements, aluminum (Al, arsenic (As, lead (Pb, manganese (Mn, mercury (Hg, and selenium (Se clearly indicate that, when considered in combination, for some, the human body may become easily over-burdened. This can be explained by changes in modern lifestyles. Similar data, solely for pregnant women, have been examined confirming this. All these elements are seen to be present in the human body and at not insignificant magnitudes. Currently suggested minimum risk levels (MRL for humans are discussed and listed together with averages of the reported distributions, together with their spread and maximum values. One observation is that many distributions for pregnant women are not too dissimilar from those of general populations. Women obviously have their individual baseline of neurotoxin values before pregnancy and any efforts to modify this to any significant degree is not yet clearly apparent. For any element, distribution shapes are reasonably similar showing broad distributions with extended tails with numerous outlier values. There are a certain fraction of people that lie well above the MRL values and may be at risk, especially if genetically susceptible. Additionally, synergistic effects between neurotoxins and with other trace metals are now also being reported. It appears prudent for women of child-bearing age to establish their baseline values well before pregnancy. Those at risk then can be better identified. Adequate instrumental testing now is commercially available for this. In addition, directives are necessary for vaccination programs to use only non-neurotoxic adjuvants, especially for

  19. Removing lead from metallic mixture of waste printed circuit boards by vacuum distillation: factorial design and removal mechanism.

    Li, Xingang; Gao, Yujie; Ding, Hui

    2013-10-01

    The lead removal from the metallic mixture of waste printed circuit boards by vacuum distillation was optimized using experimental design, and a mathematical model was established to elucidate the removal mechanism. The variables studied in lead evaporation consisted of the chamber pressure, heating temperature, heating time, particle size and initial mass. The low-level chamber pressure was fixed at 0.1 Pa as the operation pressure. The application of two-level factorial design generated a first-order polynomial that agreed well with the data for evaporation efficiency of lead. The heating temperature and heating time exhibited significant effects on the efficiency, which was validated by means of the copper-lead mixture experiments. The optimized operating conditions within the region studied were the chamber pressure of 0.1 Pa, heating temperature of 1023 K and heating time of 120 min. After the conditions were employed to remove lead from the metallic mixture of waste printed circuit boards, the efficiency was 99.97%. The mechanism of the effects was elucidated by mathematical modeling that deals with evaporation, mass transfer and condensation, and can be applied to a wider range of metal removal by vacuum distillation. Copyright © 2013 Elsevier Ltd. All rights reserved.

  20. Web-service for integration of current information from the leading MOOCs

    Sergey P. Timoshin

    2017-01-01

    Full Text Available Purpose. A phenomenon called MOOC (Massive Open Online Course plays a special, “revolutionary” role, introducing of online learning for all stages of the educational process. Today there are a lot of MOOCs, the largest of them: Coursera, edX, Udacity. In connection with the large amount of resources for additional education, a number of questions arise: “How to choose the suitable course as an additional education, how to use the capabilities of MOOCs to improve the quality of the educational process at the university, how to minimize the time for finding the desired course on different platforms?”The purpose of the work is to create a unified information resource that allows you to integrate relevant information from various MOOCs, to reduce the time for finding an appropriate online course for the user, and to raise awareness about new courses and popular specializations, related to information technology.Materials and methods. Web-service is designed as one of the components of the information-educational environment of the Institute of System Analysis and Management. It is aimed at different groups of users: “motivated” students, “unmotivated” students, and lecturers.The initial data for the service is open information about the current online courses on the MOOCs Coursera, edX and Udacity.Each project has its own API, which allows you to get information about online courses. Since MOOCs do not have a common vocabulary in order to use it for searching, there is the problem of creating such a dictionary. To do this we use the Stack Exchange resource (stackexchange.com. The list of keywords is formed through the Stack Exchange API – we select the most popular tags on sites softwareengineering.stackexchange.com and cs.stackexchange.com.Results. As the first stage of implementation, a web application was developed that allows you to view and filter the lists of courses and to see detailed information about the courses

  1. Design optimization of 600 A-13 kA current leads for the Large Hadron Collider project at CERN

    Spiller, D M; Al-Mosawl, M K; Friend, C M; Thacker, P; Ballarino, A

    2001-01-01

    The requirements of the Large Hadron Collider project at CERN for high-temperature superconducting (HTS) current leads have been widely publicized. CERN require hybrid current leads of resistive and HTS materials with current ratings of 600 A, 6 kA and 13 kA. BICC General Superconductors, in collaboration with the University of Southampton, have developed and manufactured prototype current leads for the Large Hadron Collider project. The resistive section consists of a phosphorus de-oxidized copper conductor and heat exchanger and the HTS section is constructed from BICC General's (Pb, Bi)2223 tapes with a reduced thermal conductivity Ag alloy sheath. We present the results of the materials optimization studies for the resistive and the HTS sections. Some results of the acceptance tests at CERN are discussed. (9 refs).

  2. Extraction behaviour of 2-octylaminopyridine towards lead(II) from succinate media and its separation from other toxic metals

    Mane, Chandrashekhar P.; Anuse, Mansing A.

    2008-01-01

    Liquid-liquid extraction of lead(II) from succinate media was carried out with 2-octylaminopyridine (2-OAP) in chloroform. Lead(II) was quantitatively extracted with 0.036 M 2-OAP in chloroform from 0.005-0.007 M sodium succinate when equilibrated for 5 min. Lead(II) from the organic phase was stripped with three 10 mL portions of 0.4 M acetic acid and determined titrimetrically with EDTA. The nature of extracted species was determined from the log-log plot. The optimum conditions have been evaluated based on a critical study of weak acid concentration, extractant concentration, period of equilibration and effect of diluents. The metal loading capacity of the reagent was found to be 8 mg of lead(II) with 10 mL 0.036 M of the extractant. The extraction of the lead(II) was carried out in presence of various ions to ascertain the tolerance limit of individual. Temperature dependence of the extraction equilibrium constants was examined to estimate the apparent thermodynamic functions (ΔH, ΔS and ΔG) for extraction reaction. Lead(II) was successfully separated from commonly associated metal ions such as Bi(III), Hg(II), Cr(VI), Cd(II), Zn(II), Al(III), Ca(II), Ba(II) and from binary and ternary mixtures. The method was extended for determination of lead(II) in real samples

  3. Preparation of lead titanate zirconate from metal citrates; Preparacao do titanato zirconato de chumbo a partir dos citratos metalicos

    Bastos, C M.R.

    1994-12-31

    Lead titanate zirconate (PZT) preparation from its metal constituent citrates have been investigated. Metal citrates were obtained by forced precipitation using a dehydration alcohol mixture. Salt solutions of lead nitrate and octahydrated zirconyl chloride, and titanium tetrachloride were treated separately with citric acid and ammonium hydroxide. Zirconium, titanium and lead oxides resulted from thermal decomposition of corresponding citrates at 500{sup 0} C, 450{sup 0} C and 250{sup 0} C, respectively. Lead titanate (PT) and lead zirconate (P Z) were obtained by calcining at 450{sup 0} C and 500{sup 0} C, respectively, after adequate heating of citrates mechanically mixed in ethyl ether. PZT samples were obtained with different starting stoichiometry. Rhombohedral PZT-1 53/47 sample was prepared from co precipitating zirconyl ammonium and ammonium lead citrates in presence of ethanolic titanium oxide dispersion, and calcinating at 800{sup 0} C. Rhombohedral PZT-q 52/48 sample was obtained from heating at 500{sup 0} C for 2 hours a mixture of metal citrates coprecipitated by dehydration mixture of acetone-ethanol-formic acid (2:1:0,06). Tetragonal PZT-m stoichiometry 53/47 sample were obtained by calcining at after 600{sup 0} C for 2 hours after heating a mechanically mixed metal citrates. PT phase arose at 400{sup 0} C. PZT-m powders obtained in a range of 400{sup 0} C-800{sup 0} C were isostatically pressed, and sintered at 1100{sup 0} C and 1200{sup 0} C in saturated Pb O atmosphere. Rhombohedral sintered PZT was obtained with 7,78 g.cm{sup -3} at 1200{sup 0} C. (author). 123 refs, 53 figs, 32 tabs.

  4. Uptake of metals and metalloids by plants growing in a lead-zinc mine area, Northern Vietnam

    Ha, Nguyen Thi Hoang; Sakakibara, Masayuki; Sano, Sakae; Nhuan, Mai Trong

    2011-01-01

    This study was conducted to evaluate the phytoremediation and phytomining potential of 10 plant species growing naturally at one of the largest lead-zinc mines in Northern Vietnam. Total concentrations of heavy metals and arsenic were determined in the plant and in associated soil and water in and outside of the mine area. The results indicate that hyperaccumulation levels (mg kg -1 dry weight) were obtained in Houttuynia cordata Thunb. (1140) and Pteris vittata L. (3750) for arsenic, and in Ageratum houstonianum Mill. (1130), Potamogeton oxyphyllus Miq. (4210), and P. vittata (1020) for lead. To the best of our knowledge, the present paper is the first report on metal accumulation and hyperaccumulation by H. cordata, A. houstonianum, and P. oxyphyllus. Based on the obtained concentrations of metals, bioconcentration and translocation factors, as well as the biomass of these plants, the two latter species and P. vittata are good candidates for phytoremediation of sites contaminated with arsenic and multi-metals. None of the collected plants was suitable for phytomining, given their low concentrations of useful metals (e.g., silver, gallium, and indium).

  5. Uptake of metals and metalloids by plants growing in a lead-zinc mine area, Northern Vietnam

    Ha, Nguyen Thi Hoang [Graduate School of Science and Engineering, Ehime University, Matsuyama 790-8577 (Japan); Sakakibara, Masayuki, E-mail: sakakiba@sci.ehime-u.ac.jp [Graduate School of Science and Engineering, Ehime University, Matsuyama 790-8577 (Japan); Sano, Sakae [Department of Geology, Ehime University, Matsuyama 790-8577 (Japan); Nhuan, Mai Trong [Department of Environmental Geology, Vietnam National University, Hanoi, 334 Nguyen Trai, Hanoi (Viet Nam)

    2011-02-28

    This study was conducted to evaluate the phytoremediation and phytomining potential of 10 plant species growing naturally at one of the largest lead-zinc mines in Northern Vietnam. Total concentrations of heavy metals and arsenic were determined in the plant and in associated soil and water in and outside of the mine area. The results indicate that hyperaccumulation levels (mg kg{sup -1} dry weight) were obtained in Houttuynia cordata Thunb. (1140) and Pteris vittata L. (3750) for arsenic, and in Ageratum houstonianum Mill. (1130), Potamogeton oxyphyllus Miq. (4210), and P. vittata (1020) for lead. To the best of our knowledge, the present paper is the first report on metal accumulation and hyperaccumulation by H. cordata, A. houstonianum, and P. oxyphyllus. Based on the obtained concentrations of metals, bioconcentration and translocation factors, as well as the biomass of these plants, the two latter species and P. vittata are good candidates for phytoremediation of sites contaminated with arsenic and multi-metals. None of the collected plants was suitable for phytomining, given their low concentrations of useful metals (e.g., silver, gallium, and indium).

  6. Effect of Impurities on the Josephson Current through Helical Metals: Exploiting a Neutrino Paradigm

    Ghaemi, Pouyan; Nair, V. P.

    2016-01-01

    In this Letter we study the effect of time-reversal symmetric impurities on the Josephson supercurrent through two-dimensional helical metals such as on a topological insulator surface state. We show that, contrary to the usual superconducting-normal metal-superconducting junctions, the suppression of the supercurrent in the superconducting-helical metal-superconducting junction is mainly due to fluctuations of impurities in the junctions. Our results, which are a condensed matter realization of a part of the Mikheyev-Smirnov-Wolfenstein effect for neutrinos, show that the relationship between normal state conductance and the critical current of Josephson junctions is significantly modified for Josephson junctions on the surface of topological insulators. We also study the temperature dependence of the supercurrent and present a two fluid model which can explain some of the recent experimental results in Josephson junctions on the edge of topological insulators.

  7. Lead and other elements in house dust of Japanese residences – Source of lead and health risks due to metal exposure

    Yoshinaga, Jun; Yamasaki, Kumiko; Yonemura, Ayumi; Ishibashi, Yuri; Kaido, Takaya; Mizuno, Kodai; Takagi, Mai; Tanaka, Atsushi

    2014-01-01

    The levels of 25 elements in house dust collected from 100 general Japanese residences were measured. Factor analysis was applied on the multi-element data to explore source of Pb (median concentration 49.1 mg/kg) in house dust. Six factors were extracted and Pb was found to have great loading on the fifth factor with Sb and Sn, suggesting solder (Sn), and plastic and metals (Sb) may be the sources of Pb in the house dust of Japanese residences. No significant loading was found on soil-related factors indicating non-significant contribution of Pb in track-in soil. Seven heavy metals (Cd, Cu, Mo, Pb, Sb, Sn, and Zn) were found in house dust at >10 times more condensed than crustal abundance. Health risk of these elements to children via the ingestion of house dust was estimated based on the comparison with tolerable daily intake and found to be non-significant for most of the elements. - Highlights: • Multi-element analysis was carried out for house dust from households in Japan. • Factor analysis was applied on the multivariate data set. • The abundance of lead had a close relationship with antimony and tin in house dust. • Health risk of heavy metals in house dust for children was not serious. - Major source of Pb in house dust of Japanese residences was not track-in soil but unknown materials that contain Pb and Sb and/or Sn

  8. Development of the production of lead and precious metals in Central Asia

    Nikolić Branislav

    2014-01-01

    Full Text Available There were several rich deposits of polymetal ores of non-ferrous and precious metals in the region of Imperial Russia and the Soviet Union. Metallurgical production of these metals was developed even a thousand years ago and was in the top of the world at the beginning of the fourth quarter of the twentieth century. The disintegration of the Soviet Union and the change of government structures caused a reduction of metallurgical production, but there are all conditions to intensify and increase the production of non-ferrous and precious metals in Russia and other former Soviet republics, which are now middle-asian countries.

  9. Coherent Control of Nanoscale Ballistic Currents in Transition Metal Dichalcogenide ReS2.

    Cui, Qiannan; Zhao, Hui

    2015-04-28

    Transition metal dichalcogenides are predicted to outperform traditional semiconductors in ballistic devices with nanoscale channel lengths. So far, experimental studies on charge transport in transition metal dichalcogenides are limited to the diffusive regime. Here we show, using ReS2 as an example, all-optical injection, detection, and coherent control of ballistic currents. By utilizing quantum interference between one-photon and two-photon interband transition pathways, ballistic currents are injected in ReS2 thin film samples by a pair of femtosecond laser pulses. We find that the current decays on an ultrafast time scale, resulting in an electron transport of only a fraction of one nanometer. Following the relaxation of the initially injected momentum, backward motion of the electrons for about 1 ps is observed, driven by the Coulomb force from the oppositely moved holes. We also show that the injected current can be controlled by the phase of the laser pulses. These results demonstrate a new platform to study ballistic transport of nonequilibrium carriers in transition metal dichalcogenides.

  10. Role of iron and aluminum coagulant metal residuals and lead release from drinking water pipe materials.

    Knowles, Alisha D; Nguyen, Caroline K; Edwards, Marc A; Stoddart, Amina; McIlwain, Brad; Gagnon, Graham A

    2015-01-01

    Bench-scale experiments investigated the role of iron and aluminum residuals in lead release in a low alkalinity and high (> 0.5) chloride-to-sulfate mass ratio (CSMR) in water. Lead leaching was examined for two lead-bearing plumbing materials, including harvested lead pipe and new lead: tin solder, after exposure to water with simulated aluminum sulfate, polyaluminum chloride and ferric sulfate coagulation treatments with 1-25-μM levels of iron or aluminum residuals in the water. The release of lead from systems with harvested lead pipe was highly correlated with levels of residual aluminum or iron present in samples (R(2) = 0.66-0.88), consistent with sorption of lead onto the aluminum and iron hydroxides during stagnation. The results indicate that aluminum and iron coagulant residuals, at levels complying with recommended guidelines, can sometimes play a significant role in lead mobilization from premise plumbing.

  11. Interactions between cadmium and lead with acidic soils: Experimental evidence of similar adsorption patterns for a wide range of metal concentrations and the implications of metal migration

    Pokrovsky, O.S.; Probst, A.; Leviel, E.; Liao, B.

    2012-01-01

    Highlights: ► Adsorption experiments of Cd and Pb in acid soils (China, France). ► Large pH conditions and large range of metal concentrations were considered. ► Similar dependencies between metals concentration in solution and metal adsorbed on the surface were predicted using Langmuir and Freundlich equations and surface complexation model (SCM). ► No competition between Cd and Pb detected at pH 5. ► Metal adsorption capacity is two orders of magnitude higher than limit value for soil protection. - Abstract: The importance of high- and low-affinity surface sites for cadmium and lead adsorption in typical European and Asian soils was investigated. Adsorption experiments on surface and deep horizons of acidic brown (Vosges, France) and red loess soils (Hunan, China) were performed at 25 °C as a function of the pH (3.5–8) and a large range of metal concentrations in solution (10 −9 –10 −4 mol l −1 ). We studied the adsorption kinetics using a Cd 2+ -selective electrode and desorption experiments as a function of the solid/solution ratio and pH. At a constant solution pH, all samples exhibited similar maximal adsorption capacities (4.0 ± 0.5 μmol/g Cd and 20 ± 2 μmol/g Pb). A constant slope of adsorbed–dissolved concentration dependence was valid over 5 orders of magnitude of metal concentrations. Universal Langmuir and Freundlich equations and the SCM formalism described the adsorption isotherms and the pH-dependent adsorption edge over very broad ranges of metal concentrations, indicating no high- or low-affinity sites for metal binding at the soil surface under these experimental conditions. At pH 5, Cd and Pb did not compete, in accordance with the SCM. The metal adsorption ability exceeded the value for soil protection by two orders of magnitude, but only critical load guarantees soil protection since metal toxicity depends on metal availability.

  12. Rhizofiltration of a Heavy Metal (Lead) Containing Wastewater Using the Wetland Plant Carex pendula

    Yadav, B.K.; Siebel, M.A.; Van Bruggen, J.J.A.

    2011-01-01

    Rhizofiltration is a subset technique of phytoremediation which refers to the approach of using plant biomass for removing contaminants, primarily toxic metals, from polluted water. The effective implementation of this in situ remediation technology requires experimental as well as conceptual

  13. Metal-enhanced luminescence: Current trend and future perspectives- A review

    Ranjan, Rajeev; Esimbekova, Elena N.; Kirillova, Maria A.; Kratasyuk, Valentina A.

    2017-01-01

    Optically enhanced biosensing strategies are prerequisites for developing miniature and highly sensitive multiplexed analytical platforms. Such smart biosensing systems are highly promising for use in the fields of biomedicine and environmental monitoring. Optical signal enhancement during bioassays is attributed to the complex opto-electronic interactions of incoming photonic signals at the nanomaterial interface. Research on the use of metals other than gold and silver for such purposes tends to extend the spectral window to observe luminescence enhancement effects. Such manifold increase in luminescence may be explained by the principles of plasmon coupling, directional emission led high collection efficiency, Rayleigh scattering and related opto-electronic events. The present review begins with a mechanistic description of important phenomena associated with metal-induced luminescence enhancement, particularly focusing on the origin of metal-enhanced luminescence. This review further analyses the hybrid nanostructure capabilities responsible for maintaining unique opto-electronic properties during bio-functionalisation. Current research trends in this area, future scope of this field for designing useful bioassays and concluding remarks are then discussed. - Highlights: • Nanomaterials significantly differ from their bulk counterparts. • Strong and pronounced photophysical effects at the metal surface provide opportunities for designing novel biosensors. • Metal-enhanced luminescence increases the quantum yield of luminescent reactions. • Under optimal conditions, plasmon coupling enhances the optical effects at the nanometal surface.

  14. Metal-enhanced luminescence: Current trend and future perspectives- A review

    Ranjan, Rajeev [Laboratory of Bioluminescent Biotechnologies, Department of Biophysics, Institute of Fundamental Biology and Biotechnology, Siberian Federal University, 79 Svobodny Prospect, Krasnoyarsk 660041 (Russian Federation); Esimbekova, Elena N., E-mail: esimbekova@yandex.ru [Laboratory of Bioluminescent Biotechnologies, Department of Biophysics, Institute of Fundamental Biology and Biotechnology, Siberian Federal University, 79 Svobodny Prospect, Krasnoyarsk 660041 (Russian Federation); Institute of Biophysics SB RAS, Federal Research Center “Krasnoyarsk Science Center SB RAS”, Akademgorodok 50/50, Krasnoyarsk 660036 (Russian Federation); Kirillova, Maria A. [Laboratory of Bioluminescent Biotechnologies, Department of Biophysics, Institute of Fundamental Biology and Biotechnology, Siberian Federal University, 79 Svobodny Prospect, Krasnoyarsk 660041 (Russian Federation); Kratasyuk, Valentina A. [Laboratory of Bioluminescent Biotechnologies, Department of Biophysics, Institute of Fundamental Biology and Biotechnology, Siberian Federal University, 79 Svobodny Prospect, Krasnoyarsk 660041 (Russian Federation); Institute of Biophysics SB RAS, Federal Research Center “Krasnoyarsk Science Center SB RAS”, Akademgorodok 50/50, Krasnoyarsk 660036 (Russian Federation)

    2017-06-08

    Optically enhanced biosensing strategies are prerequisites for developing miniature and highly sensitive multiplexed analytical platforms. Such smart biosensing systems are highly promising for use in the fields of biomedicine and environmental monitoring. Optical signal enhancement during bioassays is attributed to the complex opto-electronic interactions of incoming photonic signals at the nanomaterial interface. Research on the use of metals other than gold and silver for such purposes tends to extend the spectral window to observe luminescence enhancement effects. Such manifold increase in luminescence may be explained by the principles of plasmon coupling, directional emission led high collection efficiency, Rayleigh scattering and related opto-electronic events. The present review begins with a mechanistic description of important phenomena associated with metal-induced luminescence enhancement, particularly focusing on the origin of metal-enhanced luminescence. This review further analyses the hybrid nanostructure capabilities responsible for maintaining unique opto-electronic properties during bio-functionalisation. Current research trends in this area, future scope of this field for designing useful bioassays and concluding remarks are then discussed. - Highlights: • Nanomaterials significantly differ from their bulk counterparts. • Strong and pronounced photophysical effects at the metal surface provide opportunities for designing novel biosensors. • Metal-enhanced luminescence increases the quantum yield of luminescent reactions. • Under optimal conditions, plasmon coupling enhances the optical effects at the nanometal surface.

  15. Evaluation of the effect of divalent metal transporter 1 gene polymorphism on blood iron, lead and cadmium levels

    Kayaaltı, Zeliha, E-mail: kayaalti@ankara.edu.tr; Akyüzlü, Dilek Kaya; Söylemezoğlu, Tülin

    2015-02-15

    Divalent metal transporter 1 (DMT1), a member of the proton-coupled metal ion transporter family, mediates transport of ferrous iron from the lumen of the intestine into the enterocyte and export of iron from endocytic vesicles. It has an affinity not only for iron but also for other divalent cations including manganese, cobalt, nickel, cadmium, lead, copper, and zinc. DMT1 is encoded by the SLC11a2 gene that is located on chromosome 12q13 in humans and express four major mammalian isoforms (1A/+IRE, 1A/-IRE, 2/+IRE and 2/-IRE). Mutations or polymorphisms of DMT1 gene may have an impact on human health by disturbing metal trafficking. To study the possible association of DMT1 gene with the blood levels of some divalent cations such as iron, lead and cadmium, a single nucleotide polymorphism (SNP) (IVS4+44C/A) in DMT1 gene was investigated in 486 unrelated and healthy individuals in a Turkish population by method of polymerase chain reaction–restriction fragment length polymorphism (PCR–RFLP). The genotype frequencies were found as 49.8% homozygote typical (CC), 38.3% heterozygote (CA) and 11.9% homozygote atypical (AA). Metal levels were analyzed by dual atomic absorption spectrometer system and the average levels of iron, lead and cadmium in the blood samples were 446.01±81.87 ppm, 35.59±17.72 ppb and 1.25±0.87 ppb, respectively. Individuals with the CC genotype had higher blood iron, lead and cadmium levels than those with AA and CA genotypes. Highly statistically significant associations were detected between IVS4+44 C/A polymorphism in the DMT1 gene and iron and lead levels (p=0.001 and p=0.036, respectively), but no association was found with cadmium level (p=0.344). This study suggested that DMT1 IVS4+44 C/A polymorphism is associated with inter-individual variations in blood iron, lead and cadmium levels. - Highlights: • DMT1 IVS4+44 C/A polymorphism is associated with inter-individual variations in blood iron, cadmium and lead levels.

  16. Evaluation of the effect of divalent metal transporter 1 gene polymorphism on blood iron, lead and cadmium levels

    Kayaaltı, Zeliha; Akyüzlü, Dilek Kaya; Söylemezoğlu, Tülin

    2015-01-01

    Divalent metal transporter 1 (DMT1), a member of the proton-coupled metal ion transporter family, mediates transport of ferrous iron from the lumen of the intestine into the enterocyte and export of iron from endocytic vesicles. It has an affinity not only for iron but also for other divalent cations including manganese, cobalt, nickel, cadmium, lead, copper, and zinc. DMT1 is encoded by the SLC11a2 gene that is located on chromosome 12q13 in humans and express four major mammalian isoforms (1A/+IRE, 1A/-IRE, 2/+IRE and 2/-IRE). Mutations or polymorphisms of DMT1 gene may have an impact on human health by disturbing metal trafficking. To study the possible association of DMT1 gene with the blood levels of some divalent cations such as iron, lead and cadmium, a single nucleotide polymorphism (SNP) (IVS4+44C/A) in DMT1 gene was investigated in 486 unrelated and healthy individuals in a Turkish population by method of polymerase chain reaction–restriction fragment length polymorphism (PCR–RFLP). The genotype frequencies were found as 49.8% homozygote typical (CC), 38.3% heterozygote (CA) and 11.9% homozygote atypical (AA). Metal levels were analyzed by dual atomic absorption spectrometer system and the average levels of iron, lead and cadmium in the blood samples were 446.01±81.87 ppm, 35.59±17.72 ppb and 1.25±0.87 ppb, respectively. Individuals with the CC genotype had higher blood iron, lead and cadmium levels than those with AA and CA genotypes. Highly statistically significant associations were detected between IVS4+44 C/A polymorphism in the DMT1 gene and iron and lead levels (p=0.001 and p=0.036, respectively), but no association was found with cadmium level (p=0.344). This study suggested that DMT1 IVS4+44 C/A polymorphism is associated with inter-individual variations in blood iron, lead and cadmium levels. - Highlights: • DMT1 IVS4+44 C/A polymorphism is associated with inter-individual variations in blood iron, cadmium and lead levels.

  17. Lead (Pb heavy metal impacts in the green Ulva lactuca (Chlorophyceae marine algae

    B. Saleh

    2016-05-01

    Full Text Available Toxicity of different lead (Pb (0, 2, 4 and 8 mg/L concentrations in the green Ulva lactuca (Chlorophyta marine algae at physiological level has been investigated 48 h after Pb treatment under laboratory conditions. Thalus algae damages followed Pb treatment as revealed by microscopy test showed that the 4 and 8 mg/L Pb caused morphological changes in cells viability; whereas, no effect observed at the lowest Pb applied concentration (2 mg/L. Data revealed that Pb stress caused reduction in most investigated physiological parameters i.e. Pigments content, osmotic potential and membrane stability index values. This decline in osmotic potential was significantly (p ≤ 0.001 different. Whereas, estimated electric conductivity (EC values increased significantly (p ≤ 0.001 as applied Pb concentration increased. The current study allowed somewhat to highlight and better understanding Pb impacts in U. lactuca algae. Thereby, the studied algae could be used as a useful bioindicator in Pb polluted ecosystems.

  18. Toxicological analysis of the risk of lead exposure in metal processing

    concentration and biological lead toxicity markers in blood and urine were performed for both exposed ... biological samples were determined by spectrophotometric methods. Results: The ..... Occupational lead exposure of storage battery.

  19. Current status of scrap metal recycling and reuse in USA and European countries

    Matsumoto, Akira

    1997-01-01

    Recycling and reuse of natural resources has become a global issue to be pursued, but less effective without voluntary efforts from the every industries and of the individuals. In Japan, recycling and reuse of the scrap metal from dismantling of the nuclear facilities are currently noticed as a promising option and the responsible government organizations just started activities to develope the system for enabling and encouraging the nuclear facility owners to recycle their waste. Coincidently, there have been many reports published recently, which inform successful results of the method and the activities of the international organizations for the same intention. Taking this opportunity, current trends of scrap metal recycling and reuse in the experienced countries are reviewed and the proposals from IAEA, EC and OECD/NEA on the relating issues are summarized and compared in this paper. (author)

  20. Use of lidar point cloud data to support estimation of residual trace metals stored in mine chat piles in the Old Lead Belt of southeastern, Missouri

    Witt, Emitt C.

    2016-01-01

    Historic lead and zinc (Pb-Zn) mining in southeast Missouri’s ―Old Lead Belt‖ has left large chat piles dominating the landscape where prior to 1972 mining was the major industry of the region. As a result of variable beneficiation methods over the history of mining activity, these piles remain with large quantities of unrecovered Pb and Zn and to a lesser extent cadmium (Cd). Quantifying the residual content of trace metals in chat piles is problematic because of the extensive field effort that must go into collecting elevation points for volumetric analysis. This investigation demonstrates that publicly available lidar point data from the U.S. Geological Survey 3D Elevation Program (3DEP) can be used to effectively calculate chat pile volumes as a method of more accurately estimating the total residual trace metal content in these mining wastes. Five chat piles located in St. Francois County, Missouri, were quantified for residual trace metal content. Utilizing lidar point cloud data collected in 2011 and existing trace metal concentration data obtained during remedial investigations, residual content of these chat piles ranged from 9247 to 88,579 metric tons Pb, 1925 to 52,306 metric tons Zn, and 51 to 1107 metric tons Cd. Development of new beneficiation methods for recovering these constituents from chat piles would need to achieve current Federal soil screening standards. To achieve this for the five chat piles investigated, 42 to 72% of residual Pb would require mitigation to the 1200 mg/kg Federal non-playground standard, 88 to 98% of residual Zn would require mitigation to the Ecological Soil Screening level (ESSL) for plant life, and 70% to 98% of Cd would require mitigation to achieve the ESSL. Achieving these goals through an existing or future beneficiation method(s) would remediate chat to a trace metal concentration level that would support its use as a safe agricultural soil amendment.

  1. Novel Method for Sizing Metallic Bottom Crack Depth Using Multi-frequency Alternating Current Potential Drop Technique

    Li Yuting; Gan Fangji; Wan Zhengjun; Liao Junbi; Li Wenqiang

    2015-01-01

    Potential drop techniques are of two types: the direct current potential drop (DCPD) technique and alternating current potential drop (ACPD) technique, and both of them are used in nondestructive testing. ACPD, as a kind of valid method in sizing metal cracks, has been applied to evaluate metal structures. However, our review of most available approaches revealed that some improvements can be done in measuring depth of metal bottom crack by means of ACPD, such as accuracy and sensitivity of s...

  2. Bioaccumulation of thallium and other trace metals in Biscutella laevigata nearby a decommissioned zinc-lead mine (Northeastern Italian Alps).

    Pavoni, Elena; Petranich, Elisa; Adami, Gianpiero; Baracchini, Elena; Crosera, Matteo; Emili, Andrea; Lenaz, Davide; Higueras, Pablo; Covelli, Stefano

    2017-01-15

    The mineral body exploited in Salafossa (Eastern Dolomites) was one of the largest lead/zinc-containing mineral deposits in Europe. Both metals were mainly present as sulphides (sphalerite, ZnS and galena, PbS). Mining activity started around 1550, but it was only around 1960 that the richest veins of the minerals were discovered. The mine closed in 1985, and concentrations of several trace metals, such as thallium (Tl), iron (Fe), manganese (Mn), lead (Pb) and zinc (Zn), were detected in the soils and plant samples (Biscutella laevigata L.) that were collected from eighteen sites selected outside the mine. B. laevigata is a pseudometallophyta species, and it often grows near mining areas where the soil's metal concentrations are significantly higher than those of soil with a natural geochemical background. The total metal concentrations in the plant tissue (roots and leaves of Biscutella laevigata) and in the soil samples - both bulk-soil and the B. laevigata root system (rhizo-soil) - were determined through Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES). The metal extractability and leachability of the soil samples were estimated using soil extractions with DTPA (Diethylenetriaminepentaacetic acid). In addition, metal mobility caused by rainwater runoff was estimated by using a leaching test with a dilute solution of H 2 SO 4 and HNO 3 . The results showed that metals were present in a chemical form available for uptake by the plants' roots. In fact, high concentrations of the metals were also found in the plant tissue (roots and leaves) of B. laevigata, and these concentrations were higher than those whose soils present natural geochemical background levels in the corresponding rhizo-soil. Thus, B. laevigata has shown a marked ability to bioaccumulate trace metals, especially Tl and, to a lesser extent, Zn, Pb, Fe and Mn, and it can influence metal mobility in the rhizo-soil. To assess the uptake and translocation processes of the trace

  3. Using stable lead isotopes to trace heavy metal contamination sources in sediments of Xiangjiang and Lishui Rivers in China.

    Sun, Guo-Xin; Wang, Xin-Jun; Hu, Qin-Hong

    2011-12-01

    Lead isotopes and heavy metal concentrations were measured in two sediment cores sampled in estuaries of Xiangjiang and Lishui Rivers in Hunan province, China. The presence of anthropogenic contribution was observed in both sediments, especially in Xiangjiang sediment. In the Xiangjiang sediment, the lower (206)Pb/(207)Pb and higher (208)Pb/(206)Pb ratio, than natural Pb isotope signature (1.198 and 2.075 for (206)Pb/(207)Pb and (208)Pb/(206)Pb, respectively), indicated a significant input of non-indigenous Pb with low (206)Pb/(207)Pb and high (208)Pb/(206)Pb. The corresponding concentrations of heavy metals (As, Cd, Zn, Mn and Pb) were much higher than natural values, suggesting the contaminations of heavy metals from extensive ore-mining activities in the region. Copyright © 2011 Elsevier Ltd. All rights reserved.

  4. Estimation of the exchange current density and comparative analysis of morphology of electrochemically produced lead and zinc deposits

    Nikolić Nebojša D.

    2017-01-01

    Full Text Available The processes of lead and zinc electrodeposition from the very dilute electrolytes were compared by the analysis of polarization characteristics and by the scanning electron microscopic (SEM analysis of the morphology of the deposits obtained in the galvanostatic regime of electrolysis. The exchange current densities for lead and zinc were estimated by comparison of experimentally obtained polarization curves with the simulated ones obtained for the different the exchange current density to the limiting diffusion current density ratios. Using this way for the estimation of the exchange current density, it is shown that the exchange current density for Pb was more than 1300 times higher than the one for Zn. In this way, it is confirmed that the Pb electrodeposition processes are considerably faster than the Zn electrodeposition processes. The difference in the rate of electrochemical processes was confirmed by a comparison of morphologies of lead and zinc deposits obtained at current densities which corresponded to 0.25 and 0.50 values of the limiting diffusion current densities. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. 172046

  5. Multi-metals column adsorption of lead(II), cadmium(II) and manganese(II) onto natural bentonite clay.

    Alexander, Jock Asanja; Surajudeen, Abdulsalam; Aliyu, El-Nafaty Usman; Omeiza, Aroke Umar; Zaini, Muhammad Abbas Ahmad

    2017-10-01

    The present work was aimed at evaluating the multi-metals column adsorption of lead(II), cadmium(II) and manganese(II) ions onto natural bentonite. The bentonite clay adsorbent was characterized for physical and chemical properties using X-ray diffraction, X-ray fluorescence, Brunauer-Emmett-Teller surface area and cation exchange capacity. The column performance was evaluated using adsorbent bed height of 5.0 cm, with varying influent concentrations (10 mg/L and 50 mg/L) and flow rates (1.4 mL/min and 2.4 mL/min). The result shows that the breakthrough time for all metal ions ranged from 50 to 480 minutes. The maximum adsorption capacity was obtained at initial concentration of 10 mg/L and flow rate of 1.4 mL/min, with 2.22 mg/g of lead(II), 1.71 mg/g of cadmium(II) and 0.37 mg/g of manganese(II). The order of metal ions removal by natural bentonite is lead(II) > cadmium(II) > manganese(II). The sorption performance and the dynamic behaviour of the column were predicted using Adams-Bohart, Thomas, and Yoon-Nelson models. The linear regression analysis demonstrated that the Thomas and Yoon-Nelson models fitted well with the column adsorption data for all metal ions. The natural bentonite was effective for the treatment of wastewater laden with multi-metals, and the process parameters obtained from this work can be used at the industrial scale.

  6. Lead and Cadmium: Priorities for action from UNEP’s perspective for addressing risks posed by these two heavy metals

    Piper D.

    2013-04-01

    Full Text Available The United Nations Environment Programme (UNEP has been focusing on actions with regard to lead and cadmium since 2001 when the work of the Partnership for Clean Fuels and Vehicles (PCFV was initiated. The development and finalization of the reviews of scientific information on lead and cadmium facilitated discussions among Governments in relation to the need for global action with regard to these heavy metals. UNEP continues to address priority areas for focusing to reduce risks posed by lead and cadmium. The Global Alliance to Eliminate Lead Paint (GAELP is a clear example for addressing those risks; however more work is expected to be done in relation to these key issues.

  7. Lead Poisoning

    Lead is a metal that occurs naturally in the earth's crust. Lead can be found in all parts of our ... from human activities such as mining and manufacturing. Lead used to be in paint; older houses may ...

  8. Gate tunneling current and quantum capacitance in metal-oxide-semiconductor devices with graphene gate electrodes

    An, Yanbin; Shekhawat, Aniruddh; Behnam, Ashkan; Pop, Eric; Ural, Ant

    2016-11-01

    Metal-oxide-semiconductor (MOS) devices with graphene as the metal gate electrode, silicon dioxide with thicknesses ranging from 5 to 20 nm as the dielectric, and p-type silicon as the semiconductor are fabricated and characterized. It is found that Fowler-Nordheim (F-N) tunneling dominates the gate tunneling current in these devices for oxide thicknesses of 10 nm and larger, whereas for devices with 5 nm oxide, direct tunneling starts to play a role in determining the total gate current. Furthermore, the temperature dependences of the F-N tunneling current for the 10 nm devices are characterized in the temperature range 77-300 K. The F-N coefficients and the effective tunneling barrier height are extracted as a function of temperature. It is found that the effective barrier height decreases with increasing temperature, which is in agreement with the results previously reported for conventional MOS devices with polysilicon or metal gate electrodes. In addition, high frequency capacitance-voltage measurements of these MOS devices are performed, which depict a local capacitance minimum under accumulation for thin oxides. By analyzing the data using numerical calculations based on the modified density of states of graphene in the presence of charged impurities, it is shown that this local minimum is due to the contribution of the quantum capacitance of graphene. Finally, the workfunction of the graphene gate electrode is extracted by determining the flat-band voltage as a function of oxide thickness. These results show that graphene is a promising candidate as the gate electrode in metal-oxide-semiconductor devices.

  9. Long-term dispersal of heavy metals in a catchment affected by historic lead and zinc mining

    Ciszewski, Dariusz; Kubsik, Urszula; Aleksander-Kwaterczak, Urszula [AGH Univ. of Science and Technology, Krakow (Poland)

    2012-10-15

    The Matylda catchment, in southern Poland, was polluted by the discharge of mine waters from a lead and zinc mine that inundated parts of a valley floor and caused the accumulation of metal-polluted sediments. After a partial reclamation of the mine site in the early 1980s, polluted sediments continue to accumulate on downstream floodplains and in fishponds. The aim of this study was to reconstruct the changes in metal dispersal during 100 years of mining and during the 40-year post-mining period and to propose a strategy for pollution mitigation in the area. Analyses of Cu, Cd, Pb, Zn, Mn, Ca, Mg and Fe concentrations, speciation of heavy metals and mineralogical analyses were undertaken on overbank sediment cores and in stream sediments. Concentrations of the same elements and macro-ions soluble in stream waters were also determined. Concentrations of Zn, Cd and Pb in the sediment profiles vary between 40,000 and 55,000, 300 and 600 and 30,000 and 50,000 mg kg{sup -1}, respectively. Changes of metal concentrations and the stratigraphy of sediments from the floodplains, stream channels and fishponds suggest rapid changes of metal loads migrating downstream during both the mining and post-mining periods. Since the time of mine closure, fine-grained, mine-derived sediments (ca. 12 cm thick) have been the main source of pollution of post-mining sediments and surface waters. Closure of the mine was followed by a relatively short period of rapid redistribution of sediment-associated heavy metals in the stream channel. Since the 1980s, the floodplain and fishponds have received a constant supply of metals. It contrasts with the slow sediment accretion rate and a rapid decrease of metal concentrations in floodplain pools due to dilution by decomposed leaf litter. A fivefold increase of Cd content in waters over the 4.6 km reach of the Matylda stream indicates continuous leaching of this element from the contaminated valley floor. Unsuccessful mine site rehabilitation is

  10. Temporary placement of metallic stent could lead to long-term benefits for benign tracheobronchial stenosis.

    Zhou, Guo-Wu; Huang, Hai-Dong; Sun, Qin-Ying; Xiong, Ye; Li, Qiang; Dong, Yu-Chao; Zhang, Wei

    2015-12-01

    The permanent placement of metallic stent for benign tracheobronchial stenosis (BTS) was controversial. This study was conducted to evaluate the long-term outcomes of temporary placement of metallic stent for BTS. The BTS patients who received temporary placement of retrievable self-expanded metallic stents were included between 2008 and 2011. Pre-stenting and follow-up respiratory status was analyzed. And symptom recurrence-free survival (SRFS) was assessed. A total of 49 stents were successfully temporarily placed in 40 consecutive BTS patients whose etiologies included endobronchial tuberculosis (EBTB) (n=22), post-tracheostomy stenosis (n=10), post-intubation stenosis (n=6) and post radiotherapy stricture (n=2). All stents were removed integrally after a median 18 days' stenting period, without major complications. During the median 27 months follow-up period after stent removal, a total of 22 patients were free of recurrence. And the overall 3-year SRFS rate was 52.0%. According to the etiology, the 3-year SRFS rates were 59.1% and 42.9% in the patients with EBTB and non-EBTB, respectively. Compared with pre-stenting, the follow-up internal diameter of stricture, Hugh-Jones scale, 6-minute walk test (6MWT) and percentage of forced expiratory volume in one second (FEV1%) were significantly improved. Multivariate analysis suggested that granulation tissue growth and tracheobronchial malacia might be independent factors of poor prognosis. Temporary placement of retrievable metallic stent may be an alternative treatment for BTS patients.

  11. Current liquid metal cooled fast reactor concepts: use of the dry reprocess fuel

    Park, Jee Won; Jeong, C. J.; Yang, M. S.

    2003-03-01

    Recent Liquid metal cooled Fast Reactor (LFR) concepts are reviewed for investigating the potential usability of the Dry Reprocess Fuel (DRF). The LFRs have been categorized into two different types: the sodium cooled and the lead cooled systems. In each category, overall design and engineering concepts are collected which includes those of S-PRISM, AFR300, STAR, ENHS and more. Specially, the nuclear fuel types which can be used in these LFRs, have been summarized and their thermal, physical and neutronic characteristics are tabulated. This study does not suggest the best-matching LFR for the DRF, but shows good possibility that the DRF fuel can be used in future LFRs

  12. Current liquid metal cooled fast reactor concepts: use of the dry reprocess fuel

    Park, Jee Won; Jeong, C. J.; Yang, M. S

    2003-03-01

    Recent Liquid metal cooled Fast Reactor (LFR) concepts are reviewed for investigating the potential usability of the Dry Reprocess Fuel (DRF). The LFRs have been categorized into two different types: the sodium cooled and the lead cooled systems. In each category, overall design and engineering concepts are collected which includes those of S-PRISM, AFR300, STAR, ENHS and more. Specially, the nuclear fuel types which can be used in these LFRs, have been summarized and their thermal, physical and neutronic characteristics are tabulated. This study does not suggest the best-matching LFR for the DRF, but shows good possibility that the DRF fuel can be used in future LFRs.

  13. Transition metal-induced activation of alkynes leading to metal carbene species: synthetic application to new {pi}-conjugated molecules

    Abo, T; Ohe, K [Department of Energy and Hydrocarbon Chemistry, Graduate School of Engineering, Kyoto University, Katsura, Nishikyo-ku, Kyoto 615-8510 (Japan)], E-mail: ohe@scl.kyoto-u.ac.jp

    2008-03-15

    The in situ generation of furylcarbene complexes by means of transition metals was applied to catalytic carbene reactions, such as Wittig-type olefination and cycloisomerization reactions. In the presence of [Rh(OAc){sub 2}]{sub 2} as a catalyst and triphenylphosphine as a carbene accepter, carbonyl-ene-ynes 1a reacted with benzaldehyde to give a 2-styrylfuran derivative 3a. The reaction involving phosphine-ylide formation followed by Wittig-type olefination with aldehydes was applied to synthesis of furfurylidene-containing p-extended conjugated molecules. A Ruthenium catalyst underwent cycloisomerization of 1,2-bis(carbonylenyl)acetylene 10a,b to afford 2,2'-bifuran structures. The crystal structure of 5,5'-diphenyl-2,2'-bifuran 11b was determined by X-ray crystallography. The ORTEP drawings of 11b exhibited transoid and highly planar structure. The emission bands of the bisfuran 11b were observed at 414 and 440 nm, its quantum yield (84%) was higher than that of a similar 5,5'-diphenyl-2,2'-bithiophene.

  14. Design of electronic measurement and quench detection equipment for the Current Lead Test facility Karlsruhe (CuLTKa)

    Hollik, Markus; Fietz, Walter H.; Fink, Stefan; Gehrlein, Mirko; Heller, Reinhard; Lange, Christian; Möhring, Tobias

    2013-01-01

    The Current Lead Test facility Karlsruhe (CuLTKa) is under construction at the Karlsruhe Institute of Technology (KIT) to perform acceptance tests of high temperature superconductor (HTS) current leads (CL). CuLTKa is in progress and present planning expects the completion in 2013. The data acquisition system is based on a modular design with electronic measurement and monitoring equipment covering a test voltage of 50 kV DC against ground. It provides plug-in units which enable temperature and voltage measurement at high voltage potential and in addition quench detection units which detect a loss of superconductivity reliably and quickly to avoid damage of the superconducting device under test. Prototype units for quench detection, temperature and voltage measurement have been successfully tested. Six temperature measurement units are already in use in the KIT test facility TOSKA and operated reliably during the acceptance tests of the HTS current leads for Wendelstein 7-X (W7-X) in 2011/2012. CuLTKa will be used first for 26 current leads which will be built in KIT for the fusion experiment JT-60SA. The present paper gives an overview of the design of the electronic measurement and quench detection equipment

  15. Optimization of superconductor--normal-metal--superconductor Josephson junctions for high critical-current density

    Golub, A.; Horovitz, B.

    1994-01-01

    The application of superconducting Bi 2 Sr 2 CaCu 2 O 8 and YBa 2 Cu 3 O 7 wires or tapes to electronic devices requires the optimization of the transport properties in Ohmic contacts between the superconductor and the normal metal in the circuit. This paper presents results of tunneling theory in superconductor--normal-metal--superconductor (SNS) junctions, in both pure and dirty limits. We derive expressions for the critical-current density as a function of the normal-metal resistivity in the dirty limit or of the ratio of Fermi velocities and effective masses in the clean limit. In the latter case the critical current increases when the ratio γ of the Fermi velocity in the superconductor to that of the weak link becomes much less than 1 and it also has a local maximum if γ is close to 1. This local maximum is more pronounced if the ratio of effective masses is large. For temperatures well below the critical temperature of the superconductors the model with abrupt pair potential on the SN interfaces is considered and its applicability near the critical temperature is examined

  16. Polyatomic ions from a high current ion implanter driven by a liquid metal ion source

    Pilz, W.; Laufer, P.; Tajmar, M.; Böttger, R.; Bischoff, L.

    2017-12-01

    High current liquid metal ion sources are well known and found their first application as field emission electric propulsion thrusters in space technology. The aim of this work is the adaption of such kind of sources in broad ion beam technology. Surface patterning based on self-organized nano-structures on, e.g., semiconductor materials formed by heavy mono- or polyatomic ion irradiation from liquid metal (alloy) ion sources (LMAISs) is a very promising technique. LMAISs are nearly the only type of sources delivering polyatomic ions from about half of the periodic table elements. To overcome the lack of only very small treated areas by applying a focused ion beam equipped with such sources, the technology taken from space propulsion systems was transferred into a large single-end ion implanter. The main component is an ion beam injector based on high current LMAISs combined with suited ion optics allocating ion currents in the μA range in a nearly parallel beam of a few mm in diameter. Different types of LMAIS (needle, porous emitter, and capillary) are presented and characterized. The ion beam injector design is specified as well as the implementation of this module into a 200 kV high current ion implanter operating at the HZDR Ion Beam Center. Finally, the obtained results of large area surface modification of Ge using polyatomic Bi2+ ions at room temperature from a GaBi capillary LMAIS will be presented and discussed.

  17. Alternating current loss characteristics in (bismuth,lead)SCCO and yttrium barium copper oxide superconducting tapes

    Nguyen, Doan Ngoc

    Alternating current (AC) loss and current carrying capacity are two of the most crucial considerations in large-scale power applications of high temperature superconducting (HTS) conductors. AC losses result in an increased thermal load for cooling machines, and thus increased operating costs. Furthermore, AC losses can stimulate quenching phenomena or at least decrease the stability margin for superconducting devices. Thus, understanding AC losses is essential for the development of HTS AC applications. The main focus of this dissertation is to make reliable total AC loss measurements and interpret the experimental results in a theoretical framework. With a specially designed magnet, advanced total AC loss measurement system in liquid nitrogen (77 K) has been successfully built. Both calorimetric and electromagnetic methods were employed to confirm the validity of the measured results and to have a more thorough understanding of AC loss in HTS conductors. The measurement is capable of measuring total AC loss in HTS tapes over a wide range of frequency and amplitude of transport current and magnetic field. An accurate phase control technique allows measurement of total AC loss with any phase difference between the transport current and magnetic field by calorimetric method. In addition, a novel total AC loss measurement system with variable temperatures from 30 K to 100 K was successfully built and tested. Understanding the dependence of AC losses on temperature will enable optimization of the operating temperature and design of HTS devices. As a part of the dissertation, numerical calculations using Brandt's model were developed to study electrodynamics and total AC loss in HTS conductors. In the calculations, the superconducting electrical behavior is assumed to follow a power-law model. In general, the practical properties of conductors, including field-dependence of critical current density Jc, n-value and non-uniform distribution of Jc, can be accounted for in

  18. Light-current-induced acceleration of degradation of methylammonium lead iodide perovskite solar cells

    Xiang, Yuren; Zhang, Fan; He, Junjie; Lian, Jiarong; Zeng, Pengju; Song, Jun; Qu, Junle

    2018-04-01

    The photo-conversion efficiency of perovskite solar cells (PSCs) has been improved considerably in recent years, but the poor stability of PSCs still prevents their commercialization. In this report, we use the rate of the integrated short-circuit current change (Drate) to investigate the performance degradation kinetics and identify the degradation of PSCs that is accelerated by the light current. The value of Drate increases by an order of magnitude from about 0.02 to 0.35 mA cm-2·min-1 after light-IV testing. The accelerated degradation progress is proven to be dominated by the hydration process and the migration of the iodine ions of the light current. The migration of the iodine ions enhances the hydration process through a chain reaction, enabling the formation of fast diffusion channels for both H2O and O2, which induce the rapid decomposition of the perovskite film and increase the density of the trap state. The X-ray photoelectron spectroscopy measurement data also indicate that the super oxygen may be formed due to the PCBM damage caused by the migration iodine ions. An understanding of the degradation acceleration mechanism would provide an insight into the effect of ion migration on the stability of PSCs.

  19. Early response to sibutramine in patients not meeting current label criteria: preliminary analysis of SCOUT lead-in period

    Caterson, Ian; Coutinho, Walmir; Finer, Nick

    2010-01-01

    The Sibutramine Cardiovascular Outcomes (SCOUT) trial protocol defines a patient population predominantly outside current European Union label criteria. This article explores responses to sibutramine during the 6-week, single-blind, lead-in period between patients who conformed to the label...... requirements ("conformers") and those who did not ("nonconformers"). SCOUT is an ongoing, randomized, double-blind, placebo-controlled outcome trial in overweight/obese patients at high risk of a cardiovascular event. In total, 10,742 patients received sibutramine and weight management during the lead...... with sibutramine confirms its good tolerability and efficacy in patients who meet current label criteria. Preliminary data from high-risk patients for whom sibutramine is currently contraindicated suggest a low discontinuation rate and few serious adverse events but confirmation from the SCOUT outcome data...

  20. Heavy metals, especially lead, deposition recorded in an ombrotrophic peat bog near Manchester, United Kingdom

    Le Roux, G.; Weiss, D.; Cheburkin, A.; Rausch, N.; Grattant, J.; Krachler, M.; Shotyk, W.

    2003-05-01

    A peat monolith representing up to 4,000 years of peat accumulation near Manchester, England, was collected. Major and trace elements were analysed with XRF and for Cd and Pb in the deeper samples with GF-AAS following acid digestion. Pb isotopic composition was measured with TIMS and ICP-MS. The results show a pollution since the Roman Period due to local lead sources and an increase in lead pollution in the last century due to leaded gasoline as fingerprinted by Pb isotopic signatures.

  1. LEAD POISONING OF WATERFOWL AS INDICATORS OF WATER POLLUTION BY HEAVY METALS

    Zhmud M.E.

    2011-11-01

    Full Text Available The occurrence of lead shot in waterfowl gizzards, surveyed in 1969-1985 years was considered in the south ofWestern Siberia and in the southern Ukraine. The gastric contents were investigated of 1722 birds of 13 species. ForMallard, Garganey, Eurasian Teal, and Common Pochard the lead shot was detected in the coastal areas of theDanube Delta. Maximum infestation was registered for Garganey (33,3% and Common Pochard (25,0%. Theresults are compared with data for other European countries. The necessity and effectiveness of interventions aimedat reducing the extent of lead contamination of waterfowl was discussed.

  2. The formation of metallic plasmas in transient capillary discharges at high current

    Wyndham, E S; Favre, M; Aliaga-Rossel, R

    2006-01-01

    We report observations of the formation of a metallic plasma in a high aspect ratio z-pinch confined within a ceramic capillary. A series of experiments on different capillary geometries was undertaken in which titanium metal rings were used to promote the formation of a titanium plasma through preferential ablation. In an initial vacuum a titanium seed plasma is formed in the hollow cathode (HC) volume by a low energy laser spark. This pre-ionizing plasma is assisted in its expansion into the z-pinch volume by the electron beams generated by a pre-ionizing discharge in the capillary, due to the HC effect. Further intense e-beam activity occurs on applying the main driver current to the capillary electrodes before the discharge impedance abruptly drops to give rise to an ensuing high current z-pinch. A segmented titanium ring structure within the capillary promotes metal ablation. The discharges are performed in tubes of 60 to 110 mm length and 3 and 5 mm effective internal diameter. The main discharge current is provided from a small pulsed power switched coaxial line, at up to 150 kA. The generator may be configured to deliver two different rates of current rise and this is found to have a significant effect on the plasma dynamics. The plasma properties are obtained from observations of the axial x-ray emission. The diagnostics used are filtered Si diodes, filtered time-resolved multi-pinhole camera images and the time resolved soft x-ray spectrum from 3 to 20 nm. While a single species metal plasma is not obtained, a very significant proportion of Ti is achieved in the higher rate of current rise configuration. The fraction of Ti diminishes for the longest length discharges and for the larger diameter tube diameter, as does the observed z-pinch uniformity. There is a weak dependance of the electron temperature with tube geometry, but the plasma density falls substantially in the longer discharges. This coincides with diminished effectiveness of the transient HC

  3. Leading article: Use of smartphones to pass on information about patients - what are the current issues?

    Rokadiya, S; McCaul, J A; Mitchell, D A; Brennan, P A

    2016-07-01

    Many doctors now use mobile devices such as smartphones to communicate with one another about their patients, and sometimes this is without the knowledge and approval of their employer. We know of little information about the use of texting and other web-based messaging services by doctors in hospitals, so we reviewed relevant published studies to assess the safety and usefulness of current methods of digital communication. Copyright © 2016 The British Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.

  4. Current Hypotheses on How Microsatellite Instability Leads to Enhanced Survival of Lynch Syndrome Patients

    Kristen M. Drescher

    2010-01-01

    Full Text Available High levels of microsatellite instability (MSI-high are a cardinal feature of colorectal tumors from patients with Lynch Syndrome. Other key characteristics of Lynch Syndrome are that these patients experience fewer metastases and have enhanced survival when compared to patients diagnosed with microsatellite stable (MSS colorectal cancer. Many of the characteristics associated with Lynch Syndrome including enhanced survival are also observed in patients with sporadic MSI-high colorectal cancer. In this review we will present the current state of knowledge regarding the mechanisms that are utilized by the host to control colorectal cancer in Lynch Syndrome and why these same mechanisms fail in MSS colorectal cancers.

  5. Current hypotheses on how microsatellite instability leads to enhanced survival of Lynch Syndrome patients.

    Drescher, Kristen M; Sharma, Poonam; Lynch, Henry T

    2010-01-01

    High levels of microsatellite instability (MSI-high) are a cardinal feature of colorectal tumors from patients with Lynch Syndrome. Other key characteristics of Lynch Syndrome are that these patients experience fewer metastases and have enhanced survival when compared to patients diagnosed with microsatellite stable (MSS) colorectal cancer. Many of the characteristics associated with Lynch Syndrome including enhanced survival are also observed in patients with sporadic MSI-high colorectal cancer. In this review we will present the current state of knowledge regarding the mechanisms that are utilized by the host to control colorectal cancer in Lynch Syndrome and why these same mechanisms fail in MSS colorectal cancers.

  6. An integral metallic-fueled and lead-cooled reactor concept for the 4th generation reactor

    Santos, Adimir dos; Nascimento, Jamil Alves do

    2002-01-01

    An Integral Lead Reactor (ILR) concept is proposed for the 4th generation reactor to be used in the future. The ILR is loaded with metallic fuel and cooled by lead. It was evaluated in the 300-1500 MWe power range with the Japanese Fast Set 2 cross sections library. This set was tested against several fast benchmarks and the criticality uncertainty was found to be 0.51 %Δk. The reactor is started with U-Zr and changes to the U-TRU-Zr-RE fuel in a stepwise way. In the equilibrium cycle, the burnup reactivity is less than β eff for a core of the order of 300 MWe, pin diameter of 10.4 mm and a pin-pinch to diameter ratio of 1.308. The lead void reactivity is negative for reactor power less than 750 MWe. There is a need to improve the nuclear data for the major actinides. (author)

  7. An integral metallic-fueled and lead-cooled reactor concept for the 4th generation reactor

    Santos, A. dos; Nascimento, J.A. do

    2002-01-01

    An Integral Lead Reactor (ILR) concept is proposed for the 4th generation reactor to be used in the future. The ILR is loaded with metallic fuel and cooled by lead. It was evaluated in the 300-1500 MWe power range with the Japanese Fast Set 2 cross sections library. This set was tested against several fast benchmarks and the criticality uncertainty was found to be 0.51 % Δk. The reactor is started with U-Zr and changes to the U-TRU-Zr-RE fuel in a stepwise way. In the equilibrium cycle, the burnup reactivity is less than β eff for a core of the order of 300 MWe, pin diameter of 10.4 mm and a pin-pitch to diameter ratio of 1.308. The lead void reactivity is negative for reactor power less than 750 MWe. There is a need to improve the nuclear data for the major actinides. (author)

  8. Bioleaching combined brine leaching of heavy metals from lead-zinc mine tailings: Transformations during the leaching process.

    Ye, Maoyou; Yan, Pingfang; Sun, Shuiyu; Han, Dajian; Xiao, Xiao; Zheng, Li; Huang, Shaosong; Chen, Yun; Zhuang, Shengwei

    2017-02-01

    During the process of bioleaching, lead (Pb) recovery is low. This low recovery is caused by a problem with the bioleaching technique. This research investigated the bioleaching combination of bioleaching with brine leaching to remove heavy metals from lead-zinc mine tailings. The impact of different parameters were studied, including the effects of initial pH (1.5-3.0) and solid concentration (5-20%) for bioleaching, and the effects of sodium chloride (NaCl) concentration (10-200 g/L) and temperature (25 and 50 °C) for brine leaching. Complementary characterization experiments (Sequential extraction, X-ray diffractometer (XRD), scanning electronic microscope (SEM)) were also conducted to explore the transformation of tailings during the leaching process. The results showed that bioleaching efficiency was significantly influenced by initial pH and solid concentration. Approximately 85.45% of iron (Fe), 4.12% of Pb, and 97.85% of zinc (Zn) were recovered through bioleaching in optimum conditions. Increasing the brine concentration and temperature promoted lead recovery. Lead was recovered from the bioleaching residues at a rate of 94.70% at 25 °C and at a rate of 99.46% at 50 °C when the NaCl concentration was 150 g/L. The study showed that bioleaching significantly changed the speciation of heavy metals and the formation and surface morphology of tailings. The metals were mainly bound in stable fractions after bioleaching. Copyright © 2016 Elsevier Ltd. All rights reserved.

  9. Recent studies of lead neurotoxicity in children: old metal, new questions

    David C. Bellinger

    2011-09-01

    Full Text Available Many times in the history of lead toxicology the view has prevailed that „the problem” has been solved, and that exposure to lead is no longer a major public health concern. Each time, additional research has demonstrated the prematurity of this judgment. In the last decade, an extraordinary number of new studies have illustrated that „the problem” remains, and that it has dimensions never before considered. Children’s intelligence has traditionally been considered to be the most sensitive endpoint and used as the basis for risk assessment and standard setting. For IQ, the dose-effect relationship appears to be supra-linear, with greater deficits per μg/L increment below than above 100 μg/L. Recent studies have found that greater lead exposure in early childhood is also associated with a wide variety of other outcomes, with some associations evident at biomarker levels comparable to those at which IQ deficits are observed. Among these endpoints are poorer academic achievement, ADHD, conduct disorder, and antisocial behavior. In animals, early life lead exposure has been implicated in neurodegenerative disorders later in life, perhaps via epigenetic mechanisms. Studies employing neuroimaging modalities such as volumetric, diffusion tensor, and functional MRI are providing insights into the neural bases of the cognitive impairments associated with greater lead exposure. Several recent risk assessments (e.g., EFSA, JECFA have concluded that research has yet to identify a threshold level below which lead can be considered „safe”.

  10. Historical and current use of spanish moss as a monitor of atmospheric trace metals

    Whitten, M.L.; Mossler, M.A.; Kosalwat, P.; Newman, J.R. [KBN Engineering and Applied Sciences, Inc., Gainesville, FL (United States)

    1995-12-31

    Spanish moss (Tillandsia usnesoides) is an epiphytic member of the pineapple family, Historically, tissue levels in this plant have illustrated the elevated concentration of lead near well traveled roads, as well as nickel and tin in the vicinity of battery fabrication or smelting facilities, respectively. From a survey of Spanish moss plants growing throughout the Southeast, mercury at or slightly above the limit of detection was present in eight of 128 samples. Five of these samples were collected in Florida. As part of a biomonitoring project, Spanish moss was collected from 1991 to 1993 around a waste-to-energy facility in Lake County, Florida, After three years, the percentage of Spanish moss samples which contained detectable levels of arsenic and cadmium decreased over time. Lead was detected in all samples collected throughout the monitoring period, but the mean concentration decreased from 3.7 mg/kg on a dry weight basis (1991) to 1.4 mg/kg (1993). This trend in lead levels may indicate clearance that is occurring due to the discontinuation of leaded gasoline. The percentage of moss samples containing mercury above the limit of detection increased from 67% (1991) to 97% (1993); however, mean concentrations do not support a trend in increasing concentration of this element (0.30 mg/kg on a fresh weight basis in 1991 vs. 0.19 mg/kg in 1993). Apparently, atmospheric metal concentrations are not increasing in the vicinity of the facility at this time.

  11. Biosorption of lead, copper and cadmium by an indigenous isolate Enterobacter sp. J1 possessing high heavy-metal resistance

    Lu, W.-B.; Shi, J.-J.; Wang, C.-H.; Chang, J.-S.

    2006-01-01

    This study was undertaken to investigate biosorption kinetics and equilibria of lead (Pb), copper (Cu) and cadmium (Cd) ions using the biomass of Enterobacter sp. J1 isolated from a local industry wastewater treatment plant. Efficiency of metal ion recovery from metal-loaded biomass to regenerate the biosorbent was also determined. The results show that Enterobacter sp. J1 was able to uptake over 50 mg of Pb per gram of dry cell, while having equilibrium adsorption capacities of 32.5 and 46.2 mg/g dry cell for Cu and Cd, respectively. In general, Langmuir and Freundlich models were able to describe biosorption isotherm fairly well, except that prediction of Pb adsorption was relatively poor with Langmuir model, suggesting a different mechanism for Pb biosorption. Adjusting the pH value to 3.0 led to nearly complete desorption of Cd from metal-loaded biomass, while over 90% recovery of Pb and Cu ions was obtained at pH ≤ 2. After four repeated adsorption/desorption cycles, biomass of Enterobacter sp. J1 retained 75, 79 and 90% of original capacity for adsorption of Pb, Cu and Cd, respectively, suggesting good reusability of the biosorbent. A combinative model was proposed to describe the kinetics of heavy-metal adsorption by Enterobacter sp. J1 and the model appeared to have an excellent prediction of the experimental data. The model simulation results also seemed to suggest that intracellular accumulation may occur during the uptake of Pb

  12. Biosorption of lead, copper and cadmium by an indigenous isolate Enterobacter sp. J1 possessing high heavy-metal resistance

    Lu, W.-B. [Department of Cosmetic Science, Chung Hwa College of Medical Technology, Tainan, Taiwan (China); Shi, J.-J. [Department of Chemical Engineering, National Cheng Kung University, Tainan, Taiwan (China); Wang, C.-H. [Department of Biological Engineering, Yung Ta Institute of Technology and Commerce, Pingtung, Taiwan (China); Chang, J.-S. [Department of Chemical Engineering, National Cheng Kung University, Tainan, Taiwan (China)]. E-mail: changjs@mail.ncku.edu.tw

    2006-06-30

    This study was undertaken to investigate biosorption kinetics and equilibria of lead (Pb), copper (Cu) and cadmium (Cd) ions using the biomass of Enterobacter sp. J1 isolated from a local industry wastewater treatment plant. Efficiency of metal ion recovery from metal-loaded biomass to regenerate the biosorbent was also determined. The results show that Enterobacter sp. J1 was able to uptake over 50 mg of Pb per gram of dry cell, while having equilibrium adsorption capacities of 32.5 and 46.2 mg/g dry cell for Cu and Cd, respectively. In general, Langmuir and Freundlich models were able to describe biosorption isotherm fairly well, except that prediction of Pb adsorption was relatively poor with Langmuir model, suggesting a different mechanism for Pb biosorption. Adjusting the pH value to 3.0 led to nearly complete desorption of Cd from metal-loaded biomass, while over 90% recovery of Pb and Cu ions was obtained at pH {<=} 2. After four repeated adsorption/desorption cycles, biomass of Enterobacter sp. J1 retained 75, 79 and 90% of original capacity for adsorption of Pb, Cu and Cd, respectively, suggesting good reusability of the biosorbent. A combinative model was proposed to describe the kinetics of heavy-metal adsorption by Enterobacter sp. J1 and the model appeared to have an excellent prediction of the experimental data. The model simulation results also seemed to suggest that intracellular accumulation may occur during the uptake of Pb.

  13. Study of charged hadron multiplicities in charged-current neutrino-lead interactions in the OPERA detector

    Agafonova, N.; Malgin, A.; Matveev, V.; Ryazhskaya, O.; Shakirianova, I. [INR - Institute for Nuclear Research, Russian Academy of Sciences, Moscow (Russian Federation); Aleksandrov, A.; Buontempo, S.; Consiglio, L.; Tioukov, V.; Voevodina, E. [INFN Sezione di Napoli, Naples (Italy); Anokhina, A.; Dzhatdoev, T.; Podgrudkov, D.; Roganova, T. [Lomonosov Moscow State University, SINP MSU - Skobeltsyn Institute of Nuclear Physics, Moscow (Russian Federation); Aoki, S.; Hara, T.; Mizutani, F.; Ozaki, K.; Shibayama, E.; Takahashi, S. [Kobe University, Kobe (Japan); Ariga, A.; Ereditato, A.; Kreslo, I.; Vuilleumier, J.L. [University of Bern, Laboratory for High Energy Physics (LHEP), Albert Einstein Center for Fundamental Physics, Bern (Switzerland); Ariga, T. [University of Bern, Laboratory for High Energy Physics (LHEP), Albert Einstein Center for Fundamental Physics, Bern (Switzerland); Kyushu University, Faculty of Arts and Science, Fukuoka (Japan); Bertolin, A.; Dusini, S.; Kose, U.; Longhin, A.; Pupilli, F.; Stanco, L. [INFN Sezione di Padova, Padua (Italy); Bodnarchuk, I.; Chukanov, A.; Dmitrievski, S.; Gornushkin, Y.; Sotnikov, A.; Vasina, S. [JINR - Joint Institute for Nuclear Research, Dubna (Russian Federation); Bozza, C.; Grella, G.; Stellacci, S.M. [Dipartimento di Fisica, Universita di Salerno (Italy); ' ' Gruppo Collegato' ' INFN, Fisciano, Salerno (Italy); Brugnera, R.; Garfagnini, A.; Laudisio, F.; Medinaceli, E.; Roda, M.; Sirignano, C. [INFN Sezione di Padova, Padua (Italy); Dipartimento di Fisica e Astronomia, Universita di Padova, Padua (Italy); Buonaura, A.; De Lellis, G.; Di Crescenzo, A.; Galati, G.; Hosseini, B.; Lauria, A.; Montesi, M.C.; Strolin, P. [INFN Sezione di Napoli, Naples (Italy); Dipartimento di Fisica, Universita Federico II di Napoli, Naples (Italy); Chernyavskiy, M.; Gorbunov, S.; Okateva, N.; Shchedrina, T.; Starkov, N. [LPI - Lebedev Physical Institute, Russian Academy of Sciences, Moscow (Russian Federation); D' Ambrosio, N.; Di Marco, N.; Schembri, A. [INFN-Laboratori Nazionali del Gran Sasso, Assergi, L' Aquila (Italy); De Serio, M.; Muciaccia, M.T.; Paparella, L.; Pastore, A.; Simone, S. [Dipartimento di Fisica, Universita di Bari, Bari (Italy); INFN Sezione di Bari, Bari (Italy); Amo Sanchez, P. del; Duchesneau, D.; Pessard, H. [LAPP, Universite Savoie Mont Blanc, CNRS/IN2P3, Annecy-le-Vieux (France); Di Ferdinando, D.; Mandrioli, G.; Patrizii, L.; Sirri, G.; Tenti, M. [INFN Sezione di Bologna, Bologna (Italy); Dracos, M.; Jollet, C.; Meregaglia, A. [IPHC, Universite de Strasbourg, CNRS/IN2P3, Strasbourg (France); Ebert, J.; Hagner, C.; Hollnagel, A.; Wonsak, B. [Hamburg University, Hamburg (Germany); Fini, R.A. [INFN Sezione di Bari, Bari (Italy); Fornari, F.; Mauri, N.; Pasqualini, L.; Pozzato, M. [INFN Sezione di Bologna, Bologna (Italy); Dipartimento di Fisica e Astronomia, Universita di Bologna, Bologna (Italy); Fukuda, T.; Hayakawa, T.; Ishiguro, K.; Kitagawa, N.; Komatsu, M.; Miyanishi, M.; Morishima, K.; Naganawa, N.; Naka, T.; Nakamura, M.; Nakano, T.; Niwa, K.; Rokujo, H.; Sato, O.; Shiraishi, T. [Nagoya University, Nagoya (Japan); Gentile, V. [Gran Sasso Science Institute, L' Aquila (Italy); Goldberg, J. [Technion, Department of Physics, Haifa (Israel); Guler, A.M.; Kamiscioglu, M. [METU - Middle East Technical University, Ankara (Turkey); Gustavino, C.; Loverre, P.; Monacelli, P.; Rosa, G. [INFN Sezione di Roma, Rome (Italy); Jakovcic, K.; Ljubicic, A.; Malenica, M. [Rudjer Boskovic Institute, Zagreb (Croatia); Kamiscioglu, C. [METU - Middle East Technical University, Ankara (Turkey); Ankara University, Ankara (Turkey); Kim, S.H.; Park, B.D.; Yoon, C.S. [Gyeongsang National University, Jinju (Korea, Republic of); Klicek, B.; Stipcevic, M. [Center of Excellence for Advanced Materials and Sensing Devices, Ruder Boskovic Institute, Zagreb (Croatia); Kodama, K. [Aichi University of Education, Kariya, Aichi (Japan); Matsuo, T.; Ogawa, S.; Shibuya, H. [Toho University, Funabashi (Japan); Mikado, S. [Nihon University, Narashino, Chiba (Japan); Paoloni, A.; Spinetti, M.; Votano, L. [INFN - Laboratori Nazionali di Frascati, Rome (Italy); Polukhina, N. [LPI - Lebedev Physical Institute, Russian Academy of Sciences, Moscow (Russian Federation); Moscow Engineering Physical Institute Moscow, Moscow (Russian Federation); Terranova, F. [Dipartimento di Fisica, Universita di Milano-Bicocca, Milan (Italy); Vilain, P.; Wilquet, G. [IIHE, Universite Libre de Bruxelles, Brussels (Belgium)

    2018-01-15

    The OPERA experiment was designed to search for ν{sub μ} → ν{sub τ} oscillations in appearance mode through the direct observation of tau neutrinos in the CNGS neutrino beam. In this paper, we report a study of the multiplicity of charged particles produced in charged-current neutrino interactions in lead. We present charged hadron average multiplicities, their dispersion and investigate the KNO scaling in different kinematical regions. The results are presented in detail in the form of tables that can be used in the validation of Monte Carlo generators of neutrino-lead interactions. (orig.)

  14. A high current metal vapour vacuum arc ion source for ion implantation studies

    Evans, P.J.; Noorman, J.T.; Watt, G.C.; Cohen, D.D.; Bailey, G.M.

    1989-01-01

    The main features of the metal vapour vacuum arc(MEVA) as an ion source are presented. The technology utilizes the plasma production capabilities of a vacuum arc cathode. Some of the ions produced in this discharge flow through the anode and the 3 extraction grids to form an extracted ion beam. The high beam current and the potential for generating broad beams, make this technology suitable for implantation of large surface areas. The composition of the vacuum arc cathode determines the particular ions obtained from the MEVA source. 3 refs., 1 tab., 2 figs

  15. The use of alloy 117 as a liquid metal current collector

    Maribo, David; Sondergaard, Neal

    1987-09-01

    Low melting point, bismuth based alloys are potential replacements for NaK78 as liquid metal slip ring material because of their lower reactivity and potentially greater hydrodynamic stability. This paper describes experiments with one such alloy in a model of a 300 kW superconducting homopolar motor using close clearance braid type collectors. Slip ring tip velocities varied from 5 to 20 m/s and currents ranging from 500 to 2000 A. Viscous power losses tend to follow a simple turbulent mode. In all, the data supports the use of low melting point alloys as an alternative to Na78.

  16. Temperature-dependence of Threshold Current Density-Length Product in Metallization Lines: A Revisit

    Duryat, Rahmat Saptono; Kim, Choong-Un

    2016-01-01

    One of the important phenomena in Electromigration (EM) is Blech Effect. The existence of Threshold Current Density-Length Product or EM Threshold has such fundamental and technological consequences in the design, manufacture, and testing of electronics. Temperature-dependence of Blech Product had been thermodynamically established and the real behavior of such interconnect materials have been extensively studied. The present paper reviewed the temperature-dependence of EM threshold in metallization lines of different materials and structure as found in relevant published articles. It is expected that the reader can see a big picture from the compiled data, which might be overlooked when it was examined in pieces. (paper)

  17. Simple laser-driven, metal photocathodes as cold, high-current electron sources

    Saunders, J.D.; Ringler, T.J.; Builta, L.A.; Kauppila, T.J.; Moir, D.C.; Downey, S.W.

    1987-01-01

    Recent developments in excimer laser design have made near ultraviolet light intensities of several MWcm 2 possible in unfocused beams. These advances and recent experiments indicate that high-current, simple-metal photoemissive electron guns are now feasible. Producing more than 50 Acm 2 of illuminated cathode surface, the guns could operate at vacuums of 10 -6 torr with no complicated system components inside the vacuum enclosure. The electron beam produced by such photoemission guns would have very low emittance and high brightness. This beam would also closely follow the temporal characteristics of the laser pulse, making fast risetime, ultrashort electron beam pulses possible

  18. Heavy metals (copper, cadmium, lead, mercury) in mute swans from Denmark

    Elvestad, K.; Karlog, O.; Clausen, B.

    1982-03-01

    During the severe winter of 1978-79, large numbers of mute swans died in coastal areas of Denmark. Of these, 2111 were collected for examination. The analyses confirm previous findings of relatively high copper levels in mute swans (mean for 178 livers was 2680 mg/kg dry weight (Dw) and for 110 kidneys 34 mg/kg Dw) (Table I, Fig. 1). The copper content was not related to sex or age (Table II). The highest liver levels of copper were found in swans from Western Jutland. Cadmium was found at the same relatively low levels as recorded for waterfowl elsewhere (mean for 178 livers was 12 mg/kg Dw, for 110 kidneys 24 mg/kg Dw) (Table I, Fig. 2). The cadmium content was not sex-related, but it increased with age (Table II). The mean mercury content (liver) was 1.4 mg/kg Dw in the 10 birds analysed (Table I). The mean lead content was 15 mg/kg Dw in the 178 livers analysed and 31 mg/kg Dw in 110 sternum (Table I and Fig. 3). The lead content was not sex-related. In sternum, but not in livers, it was related to age (Table II). One third of the swans were found lead-contaminated probably after ingestion of lead pellets. None of the swans carried high levels of both copper, cadmium, and lead (Table III).

  19. Enriching Metal-Oxidizing Microbes from Marine Sediment on Cathodic Currents

    Rowe, A. R.; Nealson, K. H.

    2013-12-01

    The ability of organisms to transfer electrons to and from substrates outside the cell is reshaping the way we look at microbial respiration. While this process, termed extracellular electron transport (EET), has been described in a number of metal reducing organisms, current evidence suggests that this process is widespread in nature and across physiologies. Additionally, it has been speculated that these previously overlooked electrochemical interactions may play an important role in global biogeochemical cycles. Requirements for EET could play a role in why the ';uncultured majority' have so far been resistant to culturing. As such, we are currently developing culturing techniques to target microbes capable of utilizing insoluble electron acceptors utilizing electrochemical techniques. Microbe-electrode interactions are analogous to the reactions that occur between microbes and minerals and may provide an apt way to mimic the environmental conditions (i.e., insoluble electron donor/acceptor at specific redox potentials) required for culturing specialized or EET dependent metabolisms. It has been previously demonstrated that aquatic sediments are capable of utilizing anodes as electron acceptors, thereby generating a current. While, it is known that microbes utilize electrons from a cathode for the reduction of different metals and oxygen in microbial fuel cells, currently there are no reports of environmental enrichments of microbes using cathodes. Replicate microcosms from marine sediments (sampled from Catalina Harbor, California) were incubated with ITO plated glass electrodes. Negative current production at -400mV (vs. Ag/AgCl reference electrodes) potentials was sustained for four weeks. Secondary enrichments were then constructed using the cathode as the primary electron source and a variety of anaerobic terminal electron acceptors--Nitrate, Fe3+, and SO42-. Positive current was maintained in enrichment cultures (compared to abiotic control containing

  20. Current Knowledge on the Use of Computational Toxicology in Hazard Assessment of Metallic Engineered Nanomaterials

    Guangchao Chen

    2017-07-01

    Full Text Available As listed by the European Chemicals Agency, the three elements in evaluating the hazards of engineered nanomaterials (ENMs include the integration and evaluation of toxicity data, categorization and labeling of ENMs, and derivation of hazard threshold levels for human health and the environment. Assessing the hazards of ENMs solely based on laboratory tests is time-consuming, resource intensive, and constrained by ethical considerations. The adoption of computational toxicology into this task has recently become a priority. Alternative approaches such as (quantitative structure–activity relationships ((QSAR and read-across are of significant help in predicting nanotoxicity and filling data gaps, and in classifying the hazards of ENMs to individual species. Thereupon, the species sensitivity distribution (SSD approach is able to serve the establishment of ENM hazard thresholds sufficiently protecting the ecosystem. This article critically reviews the current knowledge on the development of in silico models in predicting and classifying the hazard of metallic ENMs, and the development of SSDs for metallic ENMs. Further discussion includes the significance of well-curated experimental datasets and the interpretation of toxicity mechanisms of metallic ENMs based on reported models. An outlook is also given on future directions of research in this frontier.

  1. Current Knowledge on the Use of Computational Toxicology in Hazard Assessment of Metallic Engineered Nanomaterials.

    Chen, Guangchao; Peijnenburg, Willie; Xiao, Yinlong; Vijver, Martina G

    2017-07-12

    As listed by the European Chemicals Agency, the three elements in evaluating the hazards of engineered nanomaterials (ENMs) include the integration and evaluation of toxicity data, categorization and labeling of ENMs, and derivation of hazard threshold levels for human health and the environment. Assessing the hazards of ENMs solely based on laboratory tests is time-consuming, resource intensive, and constrained by ethical considerations. The adoption of computational toxicology into this task has recently become a priority. Alternative approaches such as (quantitative) structure-activity relationships ((Q)SAR) and read-across are of significant help in predicting nanotoxicity and filling data gaps, and in classifying the hazards of ENMs to individual species. Thereupon, the species sensitivity distribution (SSD) approach is able to serve the establishment of ENM hazard thresholds sufficiently protecting the ecosystem. This article critically reviews the current knowledge on the development of in silico models in predicting and classifying the hazard of metallic ENMs, and the development of SSDs for metallic ENMs. Further discussion includes the significance of well-curated experimental datasets and the interpretation of toxicity mechanisms of metallic ENMs based on reported models. An outlook is also given on future directions of research in this frontier.

  2. Current practices in corrosion, surface characterization, and nickel leach testing of cardiovascular metallic implants.

    Nagaraja, Srinidhi; Di Prima, Matthew; Saylor, David; Takai, Erica

    2017-08-01

    In an effort to better understand current test practices and improve nonclinical testing of cardiovascular metallic implants, the Food and Drug Administration (FDA) held a public workshop on Cardiovascular Metallic Implants: corrosion, surface characterization, and nickel leaching. The following topics were discussed: (1) methods used for corrosion assessments, surface characterization techniques, and nickel leach testing of metallic cardiovascular implant devices, (2) the limitations of each of these in vitro tests in predicting in vivo performance, (3) the need, utility, and circumstances when each test should be considered, and (4) the potential testing paradigms, including acceptance criteria for each test. In addition to the above topics, best practices for these various tests were discussed, and knowledge gaps were identified. Prior to the workshop, discussants had the option to provide feedback and information on issues relating to each of the topics via a voluntary preworkshop assignment. During the workshop, the pooled responses were presented and a panel of experts discussed the results. This article summarizes the proceedings of this workshop and background information provided by workshop participants. Published 2016. This article is a U.S. Government work and is in the public domain in the USA. J Biomed Mater Res Part B: Appl Biomater, 105B: 1330-1341, 2017. Published 2016. This article is a U.S. Government work and is in the public domain in the USA.

  3. Current modeling practice may lead to falsely high benchmark dose estimates.

    Ringblom, Joakim; Johanson, Gunnar; Öberg, Mattias

    2014-07-01

    Benchmark dose (BMD) modeling is increasingly used as the preferred approach to define the point-of-departure for health risk assessment of chemicals. As data are inherently variable, there is always a risk to select a model that defines a lower confidence bound of the BMD (BMDL) that, contrary to expected, exceeds the true BMD. The aim of this study was to investigate how often and under what circumstances such anomalies occur under current modeling practice. Continuous data were generated from a realistic dose-effect curve by Monte Carlo simulations using four dose groups and a set of five different dose placement scenarios, group sizes between 5 and 50 animals and coefficients of variations of 5-15%. The BMD calculations were conducted using nested exponential models, as most BMD software use nested approaches. "Non-protective" BMDLs (higher than true BMD) were frequently observed, in some scenarios reaching 80%. The phenomenon was mainly related to the selection of the non-sigmoidal exponential model (Effect=a·e(b)(·dose)). In conclusion, non-sigmoid models should be used with caution as it may underestimate the risk, illustrating that awareness of the model selection process and sound identification of the point-of-departure is vital for health risk assessment. Copyright © 2014 The Authors. Published by Elsevier Inc. All rights reserved.

  4. Radiogenic lead from poly-metallic thorium ores as a valuable material for advanced nuclear facilities

    Kulikov, Gennady G.; Apse, Vladimir A.; Kulikov, Evgeny G.; Kozhahmet, Bauyrzhan K.; Shkodin, Alexey O.; Shmelev, Anatoly N.

    2017-03-15

    Main purpose of the study is assessing reasonability for recovery, production and application of radiogenic lead as a coolant, neutron moderator and neutron reflector in advanced fast reactors and accelerator-driven systems (ADS). The following results were obtained: 1. Radiogenic lead with high content of isotope {sup 208}Pb can be extracted from thorium or mixed thorium-uranium ores because {sup 208}Pb is a final product of {sup 232}Th natural decay chain. 2. The use of radiogenic lead with high {sup 208}Pb content in advanced fast reactors and ADS makes it possible to improve significantly their neutron-physical and thermal-hydraulic parameters. 3. The use of radiogenic lead with high {sup 208}Pb content in advanced fast reactors as a coolant opens the possibilities for more intense fuel breeding and for application of well-known oxide fuel instead of the promising but not tested enough nitride fuel under the same safety parameters. 4. The use of radiogenic lead with high {sup 208}Pb content in advanced fast reactors as a neutron reflector opens a possibility for substantial elongation of prompt neutron lifetime. As a result, chain fission reaction in the reactor core could be slowed down, and the reactor operation could become safer. 5. The use of radiogenic lead with high {sup 208}Pb content in ADS as a coolant can upgrade substantially the level of neutron flux in the ADS blanket. Thus, favorable conditions could be formed in the ADS blanket for effective transmutation of radioactive wastes with low cross-sections of radiative neutron capture.

  5. Comparative assessment of the effects of salinomycin and monensin on the biodistribution of lead and some essential metal ions in mice, subjected to subacute lead intoxication.

    Ivanova, Juliana; Gluhcheva, Yordanka; Dimova, Donika; Pavlova, Ekaterina; Arpadjan, Sonja

    2016-01-01

    In this study, we present a comparative assessment of the effects of two polyether ionophorous antibiotics (monensin and salinomycin) on the concentrations of lead (Pb), cooper (Cu), zinc (Zn) and iron (Fe) in the kidneys, spleen, liver and brain of Pb-intoxicated animals. Our data demonstrated that the intoxication of ICR male mice with Pb salt resulted in a significant accumulation of Pb in all studied organs of the mice compared to the untreated control animals. The biodistribution of the toxic metal was in the order kidneys>spleen>liver>brain. The treatment of the Pb-intoxicated animals with tetraethylammonium salts of monensic and salinomycinic acids significantly decreased the concentration of the toxic metal ion compared to the toxic control. The effect varied in the interval 38% (for kidneys) to 52% (for brain) compared to the toxic control group (Pb). The tetraethylammonium salt of salinomycinic acid was more effective in reducing the Pb concentration in the brain of the Pb-treated mice compared to monensin. Pb-intoxication did not affect significantly the Zn endogenous concentration compared to the normal values. The treatment of ICR male mice with Pb-salt decreased the Cu concentration in the spleen and increased the Cu concentration in the liver compared to the untreated control animals. The detoxification of the Pb-intoxicated mice with tetraethylammonium salts of salinomycinic and monensic acids restored the Cu concentration in the spleen, but did not affect the Cu levels in the liver. The Pb-intoxication of the ICR mice resulted in a significant decrease of the Fe-concentration in the spleen and liver compared to the untreated control animals. The administration of the tetraethylammonium salts of salinomycinic and monensic acids to the Pb-treated animals restored the levels of Fe in both organs. Copyright © 2015 Elsevier GmbH. All rights reserved.

  6. A Study on the Influence of the Nozzle Lead Angle on the Performance of Liquid Metal Electromagnetic Micro-Jetting

    Zhiwei Luo

    2016-12-01

    Full Text Available To improve the jetting performance of liquid metals, an electromagnetic micro-jetting (EMJ valve that realizes drop-on-demand (DOD jetting while not involving any valve core or moving parts was designed. The influence of the lead angle of the nozzle on the jetting of liquid metal gallium (Ga was investigated. It was found that the Lorentz force component parallel to the nozzle that jets the electrified liquid Ga is always larger than its internal friction; thus, jet can be generated with any lead angle but with different kinetic energies. Experimental results show that the mass of the jetting liquid, the jetting distance, the initial velocity of the jet, and the resulting kinetic energy of the jet increase first and then decrease. When the lead angle is 90°, the mass of the jetting liquid and the kinetic energy are at their maximum. When the angle is 80°, the initial velocity achieves its maximum, with a calculated value of 0.042 m/s. Moreover, very close and comparatively high kinetic energies are obtained at 80° and 90°, indicating that angles in between this range can produce a preferable performance. This work provides an important theoretical basis for the design of the EMJ valve, and may promote the development and application of micro electromagnetic jetting technology.

  7. Domestic UK retrofit challenge: Barriers, incentives and current performance leading into the Green Deal

    Dowson, Mark; Poole, Adam; Harrison, David; Susman, Gideon

    2012-01-01

    This paper reviews the thermal performance of the existing UK housing stock, the main fabric efficiency incentive schemes and the barriers to obtaining deep energy and CO 2 savings throughout the stock. The UK faces a major challenge to improve the thermal performance of its existing housing stock. Millions of dwellings possess ‘hard-to-treat’ solid walls and have glazing which is not cost effective to improve. A range of fabric efficiency incentive schemes exist, but many do not target the full range of private and social housing. From now on, the Green Deal will be the UK's key energy efficiency policy. However, the scheme is forecasted to have low consumer appeal and low incentives for investors. Moreover, calculated Green Deal loan repayments will be reliant upon estimated energy savings, yet it is claimed that retrofit measures may only be half as effective as anticipated due to a lack of monitoring, poor quality installation and the increased use of heating following refurbishment. Looking to Germany, there has been success through the Passivhaus standard, but the UK currently lacks appropriate skills and cost effective components to replicate this approach. In addition, the embodied energy in retrofit products and materials threatens to counter operational savings. - Highlights: ► CERT, CESP, Decent homes and Warm Front have not targeted the full extent of private and social homes. ► There is a risk that Green Deal will fail due to low consumer appeal and low incentives for investors. ► Up to half of the predicted energy savings from whole house retrofits may not be achieved in practice. ► Passivhaus is identified as best practice for retrofit, yet there is a lack of skills and components. ► Embodied energy in materials and components must be better understood to achieve life cycle savings.

  8. Preparation and adsorption characteristics for heavy metals of active silicon adsorbent from leaching residue of lead-zinc tailings.

    Lei, Chang; Yan, Bo; Chen, Tao; Xiao, Xian-Ming

    2018-05-19

    To comprehensively reuse the leaching residue obtained from lead-zinc tailings, an active silicon adsorbent (ASA) was prepared from leaching residue and studied as an adsorbent for copper(II), lead(II), zinc(II), and cadmium(II) in this paper. The ASA was prepared by roasting the leaching residue with either a Na 2 CO 3 /residue ratio of 0.6:1 at 700 °C for 1 h or a CaCO 3 /residue ratio of 0.8:1 at 800 °C for 1 h. Under these conditions, the available SiO 2 content of the ASA was more than 20%. The adsorption behaviors of the metal ions onto the ASA were investigated and the Langmuir, Freundlich, and Dubinin-Radushkevich isotherm models were used to analyze the adsorption isotherm. The result showed that the maximum adsorption capacities of copper(II), lead(II), cadmium(II), and zinc(II) calculated by the Langmuir model were 3.40, 2.83, 0.66, and 0.62 mmol g -1 , respectively. The FT-IR spectra of the ASA and the mean free adsorption energies indicated that ion exchange was the mechanism of copper(II), lead(II), and cadmium(II) adsorption and that chemical reaction was the mechanism of zinc(II) adsorption. These results provide a method for reusing the leaching residue obtained from lead-zinc tailings and show that the ASA is an effective adsorbent for heavy metal pollution remediation.

  9. Bismuth-, Tin-, and Lead-Containing Metal-Organic Materials: Synthesis, Structure, Photoluminescence, Second Harmonic Generation, and Ferroelectric Properties

    Wibowo, Arief Cahyo

    Metal-Organic Materials (MOMs) contain metal moieties and organic ligands that combine to form discrete (e.g. metal-organic polyhedra, spheres or nanoballs, metal-organic polygons) or polymeric structures with one-, two-, or three-dimensional periodicities that can exhibit a variety of properties resulting from the presence of the metal moieties and/or ligand connectors in the structure. To date, MOMs with a range of functional attributes have been prepared, including record-breaking porosity, catalytic properties, molecular magnetism, chemical separations and sensing ability, luminescence and NLO properties, multiferroic, ferroelectric, and switchable molecular dielectric properties. We are interested in synthesizing non-centrosymmetric MOM single crystals possessing one of the ten polar space groups required for non-linear optical properties (such as second harmonic generation) and ferroelectric applications. This thesis is divided into two main parts: materials with optical properties, such as photoluminescence and materials for targeted applications such as second harmonic generation and ferroelectric properties. This thesis starts with an introduction describing material having centrosymmetric, non-polar space groups, single crystals structures and their photoluminescence properties. These crystals exhibit very interesting and rare structures as well as interesting photoluminescence properties. Chapters 2-5 of this thesis focus on photoluminescent properties of new MOMs, and detail the exploratory research involving the comparatively rare bismuth, lead, and tin coordination polymers. Specifically, the formation of single white-light emitting phosphors based on the combination of bismuth or lead with pyridine-2,5-dicarboxylate is discussed (Chapter 2). The observation of a new Bi2O2 layer and a new Bi4O 3 chain in bismuth terephthalate-based coordination polymers is presented in Chapter 3, while the formation of diverse structures of tin-based coordination

  10. Spin-independent transparency of pure spin current at normal/ferromagnetic metal interface

    Hao, Runrun; Zhong, Hai; Kang, Yun; Tian, Yufei; Yan, Shishen; Liu, Guolei; Han, Guangbing; Yu, Shuyun; Mei, Liangmo; Kang, Shishou

    2018-03-01

    The spin transparency at the normal/ferromagnetic metal (NM/FM) interface was studied in Pt/YIG/Cu/FM multilayers. The spin current generated by the spin Hall effect (SHE) in Pt flows into Cu/FM due to magnetic insulator YIG blocking charge current and transmitting spin current via the magnon current. Therefore, the nonlocal voltage induced by an inverse spin Hall effect (ISHE) in FM can be detected. With the magnetization of FM parallel or antiparallel to the spin polarization of pure spin currents ({{\\boldsymbol{σ }}}sc}), the spin-independent nonlocal voltage is induced. This indicates that the spin transparency at the Cu/FM interface is spin-independent, which demonstrates that the influence of spin-dependent electrochemical potential due to spin accumulation on the interfacial spin transparency is negligible. Furthermore, a larger spin Hall angle of Fe20Ni80 (Py) than that of Ni is obtained from the nonlocal voltage measurements. Project supported by the National Basic Research Program of China (Grant No. 2015CB921502), the National Natural Science Foundation of China (Grant Nos. 11474184 and 11627805), the 111 Project, China (Grant No. B13029), and the Fundamental Research Funds of Shandong University, China.

  11. Current trends in degradation assesment on metallic materials of industrial components

    Herrera Palma, Victoria

    2007-01-01

    To needs to assess objectively a structural integrity analysis in nuclear and termal power-, oil- and chemical- industry system, represents a large challenge for engineer and researches related to Materials Science, equipment manufactures or users. These systems share many of their problems with regards to aging mechanism of components metallic materials, high replacement costs and increasing requirements on efficiency and safety. This paper makes an attempt to give an overview of the current trends on material damage and residual life assessment for installation of power-, oil- and chemical industry. Some of the currently existing ideas on components inspection, as an activity for damage detection are shown. A summary on mechanism of material damage and experimental techniques for their characterization is also presented. Finally, some analytical methods with wide appliance in materials damage evaluation and residual life assesment of components are described

  12. The interaction of pulsed eddy current with metal surface crack for various coils

    Yang, H.-C.; Tai, C.-C.

    2002-01-01

    We study the interaction of pulsed eddy current (PEC) with metal surface cracks using various coils that have different geometric sizes. In the previous work, we have showed that the PEC technique can be used to inspect electrical-discharge-machined (EDM) notches with depth from 0.5 mm to 9 mm. The results showed that the relationship between PEC signals and crack depth is obvious. In this work, we further try a series of coils with different radii, heights, turns and shapes. We will discuss the effects of these coil parameters on the PEC signal. Some other critical problems of PEC measurements such as signal drift that caused by heating effect of coil currents will be studied. We also show more experiments on fatigue cracks to demonstrate the capability of PEC technique for cracks inspection

  13. Analysis of Reverse-Bias Leakage Current Mechanisms in Metal/GaN Schottky Diodes

    P. Pipinys

    2010-01-01

    Full Text Available Temperature-dependent reverse-bias current-voltage characteristics obtained by other researchers for Schottky diodes fabricated on GaN are reinterpreted in terms of phonon-assisted tunneling (PhAT model. Temperature dependence of reverse-bias leakage current is shown could be caused by the temperature dependence of electron tunneling rate from traps in the metal-semiconductor interface to the conduction band of semiconductor. A good fit of experimental data with the theory is received in a wide temperature range (from 80 K to 500 K using for calculation the effective mass of 0.222 me. and for the phonon energy the value of 70 meV. The temperature and bias voltages dependences of an apparent barrier height (activation energy are also explicable in the framework of the PhAT model.

  14. Highly effective removal of heavy metals by polymer-based zirconium phosphate: a case study of lead ion.

    Pan, B C; Zhang, Q R; Zhang, W M; Pan, B J; Du, W; Lv, L; Zhang, Q J; Xu, Z W; Zhang, Q X

    2007-06-01

    Zirconium phosphate (ZrP) has recently been demonstrated as an excellent sorbent for heavy metals due to its high selectivity, high thermal stability, and absolute insolubility in water. However, it cannot be readily adopted in fixed beds or any other flowthrough system due to the excessive pressure drop and poor mechanical strength resulting from its fine submicrometer particle sizes. In the present study a hybrid sorbent, i.e., polymer-supported ZrP, was prepared by dispersing ZrP within a strongly acidic cation exchanger D-001 and used for enhanced lead removal from contaminated waters. D-001 was selected as a host material for sorbent preparation mainly because of the Donnan membrane effect resulting from the nondiffusible negatively charged sulfonic acid group on the exchanger surface, which would enhance permeation of the targeted metal ions. The hybrid sorbent (hereafter denoted ZrP-001) was characterized using a nitrogen adsorption technique, scanning electron microscope (SEM), and X-ray diffraction (XRD). Lead sorption onto ZrP-001 was found to be pH dependent due to the ion-exchange mechanism, and its sorption kinetics onto ZrP-001 followed the pseudo-first-order model. Compared to D-001, ZrP-001 exhibited more favorable lead sorption particularly in terms of high selectivity, as indicated by its substantially larger distribution coefficients when other competing cations Na(+), Ca(2+), and Mg(2+) coexisted at a high level in solution. Fixed-bed column runs showed that lead sorption on ZrP-001 resulted in a conspicuous decrease of this toxic metal from 40 mg/L to below 0.05 mg/L. By comparison with D-001 and ZrP-CP (ZrP dispersion within a neutrally charged polymer CP), enhanced removal efficiency of ZrP-001 resulted from the Donnan membrane effect of the host material D-001. Moreover, its feasible regeneration by diluted acid solution and negligible ZrP loss during operation also helps ZrP-001 to be a potential candidate for lead removal from water. Thus

  15. Dark Current And Voltage Measurements Of Metal-Organic-Semiconductor (M-Or-S) Diode

    Adianto

    1996-01-01

    . Some Metal-Organic-Semiconductor (M-Or-S) thin film diodes, constructed with an organic polymer (polymerized toluene) as an active component has been successfully fabricated. The thin film M-Or-S diodes were fabricated on an n-type silicon with resistivity of 250-500 Ocm and p type silicon with resistivity of 10-20 Ocm as a substrate with polymerized toluene used as insulator. When deposited on silicon wafers with electrode of evaporated Ni on the n-type silicon and evaporated Au as the electrode on the polymerized toluene film, the electronic devices of Metal-Organic- Semiconductor (M-Or-S) type can be produced with one of its characteristics is that their light sensitivity. A plasma ion deposition system was constructed and used to deposit organic monomeric substance (toluene) that functioned as an isolator between semiconductor and the evaporated metal electrodes. The current-voltage measurements for different configurations of M-Or-S devices were carried out to determine the current-voltage (1-V) characteristics for M-Or-S devices with different materials and thicknesses. In addition to the 1-V measurement mentioned before, 1-V measurements of the devices were also carried out by using a curve tracer oscilloscope, and the picture of the effective parameters of each of the device could be taken by using a polaroid camera. Since the devices are very sensitive to light, the devices were all tested in a black-box which was covered by a black cloth to make sure that there was no light coming through. The experimental results for p- and n-type silicon substrates showed that an M-Or-S diode with n-type gave a higher breakdown voltage than that p- type silicon. In addition, the reverse bias breakdown voltage increased as the thickness of the thin film increased in the range of 50 -2500 V/μm

  16. Theory of in-plane current induced spin torque in metal/ferromagnet bilayers

    Sakanashi, Kohei; Sigrist, Manfred; Chen, Wei

    2018-05-01

    Using a semiclassical approach that simultaneously incorporates the spin Hall effect (SHE), spin diffusion, quantum well states, and interface spin–orbit coupling (SOC), we address the interplay of these mechanisms as the origin of the spin–orbit torque (SOT) induced by in-plane currents, as observed in the normal metal/ferromagnetic metal bilayer thin films. Focusing on the bilayers with a ferromagnet much thinner than its spin diffusion length, such as Pt/Co with  ∼10 nm thickness, our approach addresses simultaneously the two contributions to the SOT, namely the spin-transfer torque (SHE-STT) due to SHE-induced spin injection, and the inverse spin Galvanic effect spin–orbit torque (ISGE-SOT) due to SOC-induced spin accumulation. The SOC produces an effective magnetic field at the interface, hence it modifies the angular momentum conservation expected for the SHE-STT. The SHE-induced spin voltage and the interface spin current are mutually dependent and, hence, are solved in a self-consistent manner. The result suggests that the SHE-STT and ISGE-SOT are of the same order of magnitude, and the spin transport mediated by the quantum well states may be an important mechanism for the experimentally observed rapid variation of the SOT with respect to the thickness of the ferromagnet.

  17. A self-referenced reflectance sensor for the detection of lead and other heavy metal ions using optical fibres

    Guillemain, H; Rajarajan, M; Sun, T; Grattan, K T V

    2009-01-01

    A self-referenced optical fibre sensor for monitoring heavy metals, especially lead, has been developed and evaluated and the results obtained are discussed in detail in this paper. The sensor probe builds on concepts in prior work, creating a small, compact and portable device using an indicator immobilized at the fibre end. It functions in the visible part of the spectrum where the attenuation caused by fibre transmission is small and it offers a possible solution to the need for devices to be used in the field. This represents on-going research where the factors affecting the probe design and immobilization procedure used are considered and solutions offered

  18. Extraction of uranium and lead from mixed waste debris using a variety of metal/ligand complexes

    Needham, D.A.; Duran, B.L.; Ehler, D.S.; Sauer, N.N.

    1997-01-01

    To ensure the safety of our Nation's nuclear stockpile, Los Alamos National Laboratory is in the process of constructing the DARHT (Dual Axis Radiographic Hydrodynamic Test) facility. DARHT will examine the effects of aging and the stability of our stockpile. Contained testing will be phased in to reduce the impact of these tests, which contain depleted uranium, on our environment. The main focus of this research is to develop a treatment scheme for the recovery of depleted uranium and lead from shot debris that will result from these tests. The goals of this research are to optimize the conditions on a bench scale using a commercially available water soluble polymer to bind the lead and a variety of metal/ligand complexes such as 4,5-dihydroxy-1,3-benzene-disulfonic acid, dithionite, sodium carbonate/bicarbonate, and sodium hypochlorite to bind the uranium. Studies were conducted on a mixture of debris, such as wood, cable, paper towels, and tubing that contained both uranium and lead ranging in concentration from 10-1000's of ppm of contaminants. Experiments were done varying combinations and successions of extractant solutions as well as a number of sequential extractions. Studies show that a mixture of sodium hypochlorite and carbonate removed 90+% of both uranium and lead. We then focused on a separation scheme for the lead and uranium

  19. Removal of lead (II) from metal plating effluents using sludge based activated carbon as adsorbent.

    Raju, P; Saseetharan, M K

    2010-01-01

    A novel adsorbent was prepared from waste sludge obtained from a sugar mill for removing heavy metals from industrial wastewater. The adsorption studies were carried out in batch and continuous modes for both sugar mill sludge based carbon and commercial carbon. In batch studies, experiments were conducted at ambient temperature to assess the influence of the parameters such as pH, adsorbent dose, contact time and equilibrium concentration. Adsorption data for the prepared carbon was found to satisfy both the Freundlich and Langmuir isotherms. Column studies were carried out to delineate the effect of varying depth of carbon at constant flow rate. The breakthrough curves were drawn to establish the mechanism. The result shows that the sludge based activated carbon can be used as an alternative for commercial carbon.

  20. Pre-treatment technology for electrochemical detection of heavy metal lead and cadmium in food

    Ke YAN

    2015-04-01

    Full Text Available Wet digestion is used as the pre-treatment technology for the electrochemical detection of heavy metals in food, and the complete wet digestion condition of food sample is optimized by electrochemical experiments. The results show that the experimental samples can be digested completely using the Nitric acid-hydrogen peroxide system and is not pre-digested after adding 10 mL nitric acid at 120~140 ℃ and adding 10~15 mL of hydrogen peroxide during the heating process. The correlation coefficient of electrochemical detect is 0.99 for digestion solution of the samples, and the recovery of standard addition is 82%~115%. Wet digestion as a pre-treatment technology of food samples. It can digest sample fully and meet the requirements of electrochemical detection.

  1. A study on the corrosion characteristics of lead-bismuth liquid metal

    Tak, Nam Il; Park, Won S.; Han, Seok Jung; Jeong, Won Seok

    1999-03-01

    Pb-Bi eutectic has been adopted as a coolant and spallation target material of HYPER (Hybrid Power Extraction Reactor), an accelerator driven subcritical transmutation system. The contents and scope of the present study are to implement systematic survey and analyses of available results on the corrosion characteristics of Pb-Bi liquid metal which are considered to be the most important among Pb-Bi coolant technologies and to provide fundamental bases for future research efforts. Major parameters affecting the corrosion of structural materials in liquid metals are temperature, flow velocity, contents of impurities in coolant, compositions of structural materials, and so forth. It was already known that for traditional commercial austenitic steels of 18Cr-10Ni-Ti type and 12%Cr ferritic steels, the operating temperatures of Pb-Bi coolant cannot be raised above 400 dg C and 450 dg C, respectively. However, extensive researches have been performed to protect structural materials under higher operating temperature such as the development of various kinds of coating methods for steels and the investigations of coolant inhibition by different chemical elements. The available experimental results show that the effective methods to improve the performance of structural materials in Pb-Bi coolant are the development of suitable steel alloys, the creation of oxide type coatings, and the control of oxygen inhibition. According to the recently presented research results of URRS, utilization of these methods makes it possible to raise the operating temperature limit to 620-650 dg C. It provides the possibility of usage of Pb-Bi coolant for the transmutation system, HYPER some day. (Author). 27 refs., 6 tabs., 15 figs

  2. A study on the corrosion characteristics of lead-bismuth liquid metal

    Tak, Nam Il; Park, Won S.; Han, Seok Jung; Jeong, Won Seok

    1999-03-01

    Pb-Bi eutectic has been adopted as a coolant and spallation target material of HYPER (Hybrid Power Extraction Reactor), an accelerator driven subcritical transmutation system. The contents and scope of the present study are to implement systematic survey and analyses of available results on the corrosion characteristics of Pb-Bi liquid metal which are considered to be the most important among Pb-Bi coolant technologies and to provide fundamental bases for future research efforts. Major parameters affecting the corrosion of structural materials in liquid metals are temperature, flow velocity, contents of impurities in coolant, compositions of structural materials, and so forth. It was already known that for traditional commercial austenitic steels of 18Cr-10Ni-Ti type and 12%Cr ferritic steels, the operating temperatures of Pb-Bi coolant cannot be raised above 400 dg C and 450 dg C, respectively. However, extensive researches have been performed to protect structural materials under higher operating temperature such as the development of various kinds of coating methods for steels and the investigations of coolant inhibition by different chemical elements. The available experimental results show that the effective methods to improve the performance of structural materials in Pb-Bi coolant are the development of suitable steel alloys, the creation of oxide type coatings, and the control of oxygen inhibition. According to the recently presented research results of URRS, utilization of these methods makes it possible to raise the operating temperature limit to 620-650 dg C. It provides the possibility of usage of Pb-Bi coolant for the transmutation system, HYPER some day. (Author). 27 refs., 6 tabs., 15 figs.

  3. Heavy metal contamination of topsoils around a lead and zinc smelter in the Republic of Macedonia

    Stafilov, Trajce; Sajn, Robert; Pancevski, Zlatko; Boev, Blazo; Frontasyeva, Marina V.; Strelkova, Lyudmila P.

    2010-01-01

    The results of a first systematic study of spatial distribution of different elements in surface soil over the Veles region (50 km 2 ) known for its lead and zinc industrial activity in the recent past are reported. A total of 201 soil samples were collected according to a dense net in urban area and less dense net in rural area. The total of 42 elements were analyzed by epithermal neutron activation analysis (ENAA) and by atomic absorption spectrometry (AAS). The content of elements such as As, Au, Cd, Cu, Hg, In, Pb, Sb, Se, Zn in soil samples around the lead and zinc smelter and in the adjacent part of the town of Veles has appeared to be much higher than in those collected in the surrounding areas due to the pollution from the plant. Thus, the content of Cd (three times); Pb and Zn (two times) is even higher than the corresponding intervention (critical) values according to the Dutch standards. The results obtained by two complementary analytical techniques, AAS and ENAA, are discussed in terms of multivariate statistics. GIS technology was applied to depict the areas most affected by contamination from the lead and zinc smelter.

  4. Electrochemical stripping determination of traces of copper, lead, cadmium and zinc in zirconium metal and zirconium dioxide

    Stulik, K.; Beran, P.; Dolezal, J.; Opekar, F.

    1978-01-01

    Procedures have been developed for the determination of copper, lead, cadmium and zinc in zirconium metal and zirconium dioxide, at concentrations of 1ppm or less. Zirconium metal was dissolved in sulphuric acid, and zirconium dioxide decomposed under pressure with hydrofluoric acid. Sample solutions were prepared in dilute sulphuric acid. For the stripping determination, the sample solution was either mixed with a complexing tartrate base electrolyte or the pre-electrolysis was carried out in acid solution, with the acid solution being exchanged for a pure base electrolyte (e.g. an acetate buffer) for the stripping step. The stripping step was monitored by d.c., differential pulse and Kalousek commutator voltammetry and the three methods were compared. A stationary mercury-drop electrode can generally be used for all the methods, whereas a mercury-film electrode is suitable only for the d.c. voltammetric determination of copper, lead and cadmium, as pulse measurements with films are poorly reproducible and the electrodes are easily damaged. The relative standard deviation does not exceed 20%. Some samples contained relatively large amounts of copper, which is best separated by electrodeposition on a platinum electrode. (author)

  5. Susceptibility of 2 1/4 Cr-1Mo steel to liquid metal induced embrittlement by lithium-lead solutions

    Eberhard, B.A.; Edwards, G.R.

    1984-08-01

    An investigation has been conducted on the liquid metal induced embrittlement susceptibility of 2 1/4Cr-1Mo steel exposed to lithium and 1a/o lead-lithium at temperatures between 190 0 C and 525 0 C. This research was part of an ongoing effort to evaluate the compatibility of liquid lithium solutions with potential fusion reactor containment materials. Of particular interest was the microstructure present in a weld heat-affected zone, a microstructure known to be highly susceptible to corrosive attack by liquid lead-lithium solutions. Embrittlement susceptibility was determined by conducting tension tests on 2 1/4Cr-1Mo steel exposed to an inert environment as well as to a lead-lithium liquid and observing the change in tensile behavior. The 2 1/4Cr-1Mo steel was also given a base plate heat treatment to observe its embrittlement susceptibility to 1a/o lead-lithium. The base plate microstructure was severely embrittled at temperatures less than 500 0 C. Tempering the base plate was effective in restoring adequate ductility to the steel

  6. Airborne concentrations of toxic metals resulting from the use of low melting point lead alloys to construct radiotherapy shielding

    McCullough, E.C.; Senjem, D.H.

    1981-01-01

    Determinations of airborne concentrations of lead, cadmium, bismuth, and tin were made above vessels containing a fusible lead alloy (158 0 F melting point) commonly used for construction of radiotherapy blocks. Fume concentrations were determined by collection on a membrane filter and analysis by atomic absorption spectrophotometry. Samples were obtained for alloy temperatures of 200 0 , 400 0 , and 600 0 F. In all instances, concentrations were much lower than the applicable occupational limits for continuous exposure. The results of this study indicate that the use of a vented hood as a means of reducing air concentrations of toxic metals above and near vessels containing low temperature melting point lead allows commonly used in construction of radiotherapy shields appears unjustifiable. However, proper handling procedures should be observed to avoid entry into the body via alternate pathways (e.g., ingestion or skin absorption). Transmission data of a non-cadmium containing lead alloy with a melting point of 203 0 F was ascertained and is reported on

  7. Detection of certain minerals of uranium, zinc, lead and other metals using photoluminescence

    Seigel, H.O.; Robbins, J.C.

    1980-01-01

    We have discovered that certain photoluminescent minerals of uranium, lead, zinc, fluorine, tungsten and other elements which may naturally occur at the surface of the earth can be selectively detected in the presence of most other photoluminescent minerals and organic materials which are likely to occur at the earth's surface. The base of selective ldetection is the discovery that the lifetimes of photoluminescent emission of materials in the latter class are much shorter than the lifetimes of photoluminescent emission of materials in the former class. This invention utilizes this discovery in the detection of minerals of uranium, zinc, lead, flourine, tungsten, molybdenum, mercury and other elements. In one embodiment of the invention, using a laser or other short duration source of optical excitation, measurements of the photoluminescent response of the earth are made at times sufficiently long for the photoluminescence of other common and unwanted sources to have substantially decayed, thereby selectively detection and identifying certain minerals of potiential economic interest. In another embodiment a source of light is modulated at a predetermined frequency and the photoluminescent response of the earth which is out-of-phase with the source is measured. In a third embodiment this source of light may be incident solar radiation after passage through asuitable modulator

  8. Liquid Metallic Hydrogen II. A Critical Assessment of Current and Primordial Helium Levels in the Sun

    Robitaille P.-M.

    2013-04-01

    Full Text Available Before a solar model becomes viable in astrophysics, one mus t consider how the ele- mental constitution of the Sun was ascertained, especially relative to its principle com- ponents: hydrogen and helium. Liquid metallic hydrogen has been proposed as a solar structural material for models based on condensed matter (e .g. Robitaille P.-M. Liq- uid Metallic Hydrogen: A Building Block for the Liquid Sun. Progr. Phys. , 2011, v. 3, 60–74. There can be little doubt that hydrogen plays a d ominant role in the uni- verse and in the stars; the massive abundance of hydrogen in t he Sun was established long ago. Today, it can be demonstrated that the near isointe nse nature of the Sun’s Balmer lines provides strong confirmatory evidence for a dis tinct solar surface. The situation relative to helium remains less conclusive. Stil l, helium occupies a prominent role in astronomy, both as an element associated with cosmol ogy and as a byproduct of nuclear energy generation, though its abundances within the Sun cannot be reliably estimated using theoretical approaches. With respect to th e determination of helium lev- els, the element remains spectroscopically silent at the le vel of the photosphere. While helium can be monitored with ease in the chromosphere and the prominences of the corona using spectroscopic methods, these measures are hig hly variable and responsive to elevated solar activity and nuclear fragmentation. Dire ct assays of the solar winds are currently viewed as incapable of providing definitive in formation regarding solar helium abundances. As a result, insight relative to helium r emains strictly based on the- oretical estimates which couple helioseismological appro aches to metrics derived from solar models. Despite their “state of the art” nature, heliu m estimates based on solar models and helioseismology are suspect on several fronts, i ncluding their reliance on solar opacities. The best knowledge can only come from the so

  9. Health risk assessment of heavy metals (cadmium, nickel, lead and zinc in withdrawed parsley vegetable from some farms in Hamedan city

    M Cheraghi

    2014-11-01

    Results: Average concentration of cadmium, nickel, lead and zinc in parsley vegetable is in the order of 1/14, 2/56, 16/65 and 25/23 mg/kg and average concentration of this metals in soil is in the order of 0/23, 23/51, 20/85 and 57/5 mg/kg. Results of this study showed that average concentration of Cadmium and Leadin parsley is above WHO/FAO whereas average concentration of Nickel and Zink in parsleywas assessed less than WHO/FAO. Also the average concentration of every four metals in soil of farms was less than WHO/FAO levels.On the other hand the amount of risk and health index (HRI in parsley for lead metal was above 1 and for cadmium, nickel and zinc metals was less than 1. Conclusion: According to the studing results, cultivated parsley in this area was polluted to the heavy metalsCadmium and Lead, and the results indicates the very easy transferring of this metals from soil to parsley that was not healthy for human daily consumption and risk and health index (HRI that was above 1 for lead metal shows the hygienic potential risk of this metal in relation to the polluted parsley consumption in human daily alimentary diet.

  10. Action of fluorine, lead, and zinc on soils, vegetation and animals in metal works

    Paluch, J.; Karweta, S.; Szalonek, I.

    Almost all the activities of industry exert an influence on the biosphere. In examining the complicated problems of the interaction of industry and the biosphere it is necessary to distinguish between three fundamental groups of factors which, without doubt, are destructive. They are: (1) sources which pollute surface and subterranean water thus polluting soils; (2) sources which pollute the atmosphere with solids, gases and, rarely, liquids; and (3) the installations and actions which cause changes in the shape of the land, often connected with the direct devastation of the soil, and influence the hydrology of the area. The authors study the actions of fluorine, lead and zinc in relation to these factors. 4 tables.

  11. Molecular dynamics simulation of metallic impurity diffusion in liquid lead-bismuth eutectic (LBE)

    Gao, Yun; Takahashi, Minoru; Cavallotti, Carlo; Raos, Guido

    2018-04-01

    Corrosion of stainless steels by lead-bismuth eutectic (LBE) is an important problem which depends, amongst other things, on the diffusion of the steel components inside this liquid alloy. Here we present the results of classical molecular dynamics simulations of the diffusion of Fe and Ni within LBE. The simulations complement experimental studies of impurity diffusion by our group and provide an atomic-level understanding of the relevant diffusion phenomena. They are based on the embedded atom method (EAM) to represent many-body interactions among atoms. The EAM potentials employed in our simulations have been validated against ab initio density functional calculations. We show that the experimental and simulation results for the temperature-dependent viscosity of LBE and the impurity diffusion coefficients can be reconciled by assuming that the Ni and Fe diffuse mainly as nanoscopic clusters below 1300 K. The average Fe and Ni cluster sizes decrease with increasing the temperature and there is essentially single-atom diffusion at higher temperatures.

  12. Current status and policies on biodiesel industry in Malaysia as the world's leading producer of palm oil

    Abdullah, A.Z.; Salamatinia, B.; Mootabadi, H.; Bhatia, S.

    2009-01-01

    This article discusses current status of palm oil-based biodiesel industry in Malaysia, the policies introduced and strategies for its implementation. Due to renewability, high production rate, technical feasibility and role in reducing greenhouse gases (GHG) emission, palm oil is in the right position to supply the energy needs by the incorporation into the diesel supply. As a leading producer of palm oil, Malaysia has embarked on a comprehensive palm biofuel program since 1982. It has successfully established the use of palm biodiesel blend (B5) as a suitable fuel for the transport and industrial sectors through the introduction of the National Biofuel Policy. The current scenario of biodiesel program in Malaysia, as well as biofuel policies with respect to its use, technology, export, environmental issues and implementation aspects are thoroughly discussed. The roles of the policy towards the prosperity of the stakeholders, oil price and the reduction of greenhouse gasses are also highlighted. (author)

  13. The mechanisms associated with the development of hypertension after exposure to lead, mercury species or their mixtures differs with the metal and the mixture ratio.

    Wildemann, Tanja M; Siciliano, Steven D; Weber, Lynn P

    2016-01-02

    Hypertension is considered to be the most important risk factor for the development of cardiovascular diseases. Beside life-style risk factors, exposure to lead and mercury species are increasingly discussed as potential risk factors. Although there are a few previous studies, the underlying mechanism by which exposure to lead and mercury disturb blood pressure regulation is not currently understood. Potential mechanisms are oxidative stress production, kidney damage and activation of the renin-angiotensin system (RAS), all of which can interact to cause dysregulation of blood pressure. Male rats (Wistar) were exposed to lead, inorganic mercury, methylmercury or two mixtures of all three metals for four weeks through the drinking water. The two mixture ratios were based on ratios of known reference values or environmental exposure from the literature. To investigate the potential mechanism of actions, blood pressure was measured after four weeks and compared to plasma nitrotyrosine or reduced/oxidized glutathione levels in liver as markers for oxidative stress. Plasma renin and angiotensin II levels were used as markers for RAS activation. Finally, kidney function and injury were assessed via urinary and plasma creatinine levels, creatinine clearance and urinary kidney-injury molecule (KIM-1). While exposure to lead by itself increased oxidative stress and kidney damage along with blood pressure, inorganic mercury did not affect blood pressure or any end-point examined. Conversely, methylmercury instead increased RAS activation along with blood pressure. Surprisingly, when administered as mixtures, lead no longer increased oxidative stress or altered kidney function. Moreover, the mixture based on an environmental ratio no longer had an effect on blood pressure, while the reference value ratio still retained an increase in blood pressure. Based on our results, the prominent mechanism of action associated with the development of hypertension seems to be oxidative

  14. Genotoxicity of two heavy metal compounds: lead nitrate and cobalt chloride in Polychaete Perinereis cultrifera.

    Singh, Nisha; Bhagat, Jacky; Ingole, Baban S

    2017-07-01

    The present study explores the in vivo and in vitro genotoxic effects of lead nitrate, [Pb(NO 3 ) 2 ] a recognized environmental pollutant and cobalt chloride (CoCl 2 ), an emerging environmental pollutant in polychaete Perinereis cultrifera using comet assay. Despite widespread occurrence and extensive industrial applications, no previous published reports on genotoxicity of these compounds are available in polychaete as detected by comet assay. Polychaetes were exposed in vivo to Pb(NO 3 ) 2 (0, 100, 500, and 1000 μg/l) and CoCl 2 (0, 100, 300, and 500 μg/l) for 5 days. At 100 μg/l Pb(NO 3 ) 2 concentration, tail DNA (TDNA) values in coelomocytes were increase by 1.16, 1.43, and 1.55-fold after day 1, day 3, and day 5, whereas, OTM showed 1.12, 2.33, and 2.10-fold increase in in vivo. Pb(NO 3 ) 2 showed a concentration and time-dependent genotoxicity whereas CoCl 2 showed a concentration-dependent genotoxicity in in vivo. A concentration-dependent increase in DNA damage was observed in in vitro studies for Pb(NO 3 ) 2 and CoCl 2 . DNA damage at 500 μg/L showed almost threefold increase in TDNA and approximately fourfold increase in OTM as compared to control in in vitro. Our studies suggest that Pb(NO 3 ) 2 and CoCl 2 have potential to cause genotoxic damage, with Pb(NO 3 ) 2 being more genotoxic in polychaete and should be used more carefully in industrial and other activities. Graphical abstract.

  15. Alterations in growth, oxidative damage, and metal uptake of five aromatic rice cultivars under lead toxicity.

    Ashraf, Umair; Hussain, Saddam; Anjum, Shakeel Ahmad; Abbas, Farhat; Tanveer, Mohsin; Noor, Mehmood Ali; Tang, Xiangru

    2017-06-01

    Lead (Pb) affects plant growth and its related physio-biochemical functions negatively. The present study investigated the responses of five different fragrant rice cultivars viz., Meixiangzhan (MXZ-2), Xiangyaxiangzhan (XYXZ), Guixiangzhan (GXZ), Basmati-385 (B-385), and Nongxiang-18 (NX-18) to four different Pb concentrations viz., 0, 400, 800 and 1200 μM. Results depicted that Pb toxicity significantly (P rice plants; nonetheless, a significant variation was found in the sensitivity of rice cultivars to Pb toxicity. Soluble sugars increased significantly only at 1200 μM in GXZ and 800 μM in B-385, whilst the maximum reductions in protein contents were observed at 1200 μM Pb for all rice cultivars. Proline contents were reduced for XYXZ and NX-18 at Pb1200 μM. Activities of superoxide dismutase (SOD), peroxidase (POD), catalase (CAT) and ascorbate peroxidase (APX) as well as reduced glutathione (GSH) and oxidized glutathione (GSSG) showed differential behavior among Pb treatments and rice cultivars. Among rice cultivars, GXZ showed better antioxidative defense system under Pb toxicity compared with all other cultivars. For all rice cultivars, the trend for Pb accumulation was recorded as: roots > stems > leaves. Furthermore, significant but negative correlations among Pb uptake and plant height (r = -0.79), tillers per plant (r = -0.91) and plant dry biomass (r = -0.81) were recorded for all rice cultivars whereas the values of translocation factor (TF) from stems to leaves were higher than roots to stems. In sum, Pb reduced the early growth and caused physio-biochemical changes in all rice cultivars, nonetheless, GXZ proved better able to tolerate Pb stress than all other rice cultivars under study. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

  16. Assessment of metals pollution on agricultural soil surrounding a lead-zinc mining area in the Karst region of Guangxi, China.

    Zhang, Chaolan; Li, Zhongyi; Yang, Weiwei; Pan, Liping; Gu, Minghua; Lee, DoKyoung

    2013-06-01

    Soil samples were collected on farmland in a lead-zinc mining area in the Karst region of Guangxi, China. The contamination of the soil by eight metals (Cd, Hg, As, Cu, Pb, Cr, Zn, Ni) was determined. Among all these metals, Cd is the most serious pollutant in this area. Zn, Hg as well asPb can also be measured at high levels, which may affect the crop production. All other metals contributed marginally to the overall soil contamination. Besides the evaluation of single metals, the Nemerow synthetic index indicated that the soil is not suitable for agricultural use.

  17. Band gap tuning and fluorescence properties of lead sulfide Pb0.9A0.1S (A: Fe, Co, and Ni) nanoparticles by transition metal doping

    Parveen, Azra; Agrawal, Shraddha; Azam, Ameer

    2018-02-01

    Transition metal-doped lead sulfide nanoparticles (PbS-NPs) were synthesized by co-precipitation method. The crystallite phase and morphological studies were carried out by X-ray diffraction (XRD) and transmission electron microscopy (TEM). Optical studies were performed by UV-Visible absorption, fluorescence emission spectroscopy and Fourier transforms infrared spectroscopy (FTIR). XRD analysis reveals that the pure and transition metal-doped PbS- NPs have a single crystalline phase with cubic structure devoided of any other secondary phase. The notable effect on optical absorbance and band gap was observed with transition metal doping in lead sulphide. The optical energy band gap values were found to increase with the doping of transition metal. UV-Visible absorption and fluorescence emission spectra display a blue shift with subsequent transition metal doping which may arise due to quantum confinement effect making it worth for having applications in optoelectronic devices.

  18. Lead isotopes and trace metal ratios of aerosols as tracers of Pb pollution sources in Kanpur, India

    Sen, Indra; Bizimis, Michael; Tripathi, Sachchida; Paul, Debajyoti; Tyagi, Swati; Sengupta, Deep

    2015-04-01

    The anthropogenic flux of Pb in the Earth's surface is almost an order of magnitude higher than its corresponding natural flux [1]. Identifying the sources and pathways of anthropogenic Pb in environment is important because Pb toxicity is known to have adverse effects on human health. Pb pollution sources for America, Europe, and China are well documented. However, sources of atmospheric Pb are unknown in India, particularly after leaded gasoline was phased out in 2000. India has a developing economy with a rapidly emerging automobile and high temperature industry, and anthropogenic Pb emission is expected to rise in the next decade. In this study, we report on the Pb- isotope compositions and trace metal ratios of airborne particulates collected in Kanpur, an industrial city in northern India. The Pb concentration in the airborne particulate matter varies between 14-216 ng/m3, while the other heavy metals vary by factor of 10 or less, e.g. Cd=0.3-3 ng/m3, As=0.4-3.5 ng/m3, Zn=36-161 ng/m3, and Cu=3-22 ng/m3. The 206Pb/207Pb, 208Pb/206Pb, and 208Pb/207Pb vary between 1.112 - 1.129, 2.123-2.141, and 2.409-2.424 respectively, and are highly correlated with each other (R2>0.9). Pb isotopes and trace metal data reveals that coal combustion is the major source of anthropogenic Pb in the atmosphere, with limited contribution from mining and smelting processes. We further conclude that combination of Pb isotope ratios and V/Pb ratios are powerful tracers for Pb source apportionment studies, which is otherwise difficult to differentiate based only on Pb systematics [1] Sen and Peucker-Ehrenbrink (2012), Environ. Sci. Technol.(46), 8601-8609

  19. Current trends in the design of metallic coatings for harsh turbine environments

    Gleeson, Brian [Pittsburgh Univ., PA (United States). Dept. of Mechanical Engineering and Materials Science

    2010-07-01

    The reliable and long-term operation of gas turbine engines at varying high temperatures and under the highly corrosive conditions found in technical applications requires further developments in materials science and technology. Quite often, the current engineering design solution to this problem is to coat the high-temperature turbine component materials, typically {gamma}-Ni+{gamma}'-Ni{sub 3}Al nickel-base superalloys, with a metallic alloy composition that is highly resistant to oxidation or corrosion. Ideally, such resistance is provided by the formation of a thermally grown oxide (TGO) scale of Al{sub 2}O{sub 3}. Indeed, the commonly used {beta}-NiAl-based coatings are excellent Al{sub 2}O{sub 3}-scale formers; however, their resistance to accelerated attack by molten-salt induced hot corrosion can rather poor. The hot-corrosion resistance of {beta}-based coatings can be improved by chromium or silicon addition, but potentially at the expense of oxidation resistance. This presentation will primarily focus on hot corrosion attack and the current approaches that are used to try to mitigate this form of attack. It will be shown that many factors affect hot corrosion resistance, particularly the composition and structure of the coating. The results from recent work on the effects of relative phase fractions, morphologies and chemistries will be drawn upon to provide guidance for optimized coating design. (orig.)

  20. Feasibility of ultrasonic and eddy current methods for measurement of residual stress in shot peened metals

    Lavrentyev, Anton I.; Stucky, Paul A.; Veronesi, William A.

    2000-01-01

    Shot peening is a well-known method for extending the fatigue life of metal components by introducing compressive residual stresses near their surfaces. The capability to nondestructively evaluate the near surface residual stress would greatly aid the assurance of proper fatigue life in shot-peened components. This paper presents preliminary results from a feasibility study examining the use of ultrasonic and eddy current NDE methods for residual stress measurement in components where the stress has been introduced by shot peening. With an ultrasonic method, a variation of ultrasonic surface wave speed with shot peening intensity was measured. Near surface conductivity was measured by eddy current methods. Since the effective penetration depth of both methods employed is inversely related to the excitation frequency, by making measurements at different frequencies, each method has the potential to provide the stress-depth profile. Experiments were conducted on aluminum specimens (alloy 7075-T7351) peened within the Almen peening intensity range of 4C to 16C. The experimental results obtained demonstrate a correlation between peening intensity and Rayleigh wave velocity and between peening intensity and conductivity. The data suggests either of the methods may be suitable, with limitations, for detecting unsatisfactory levels of shot peening. Several factors were found to contribute to the measured responses: surface roughness, near surface plastic deformation (cold work) and residual stress. The contribution of each factor was studied experimentally. The feasibility of residual stress determination from the measured data is discussed

  1. Spatiotemporal exposome dynamics of soil lead and children's blood lead pre- and ten years post-Hurricane Katrina: Lead and other metals on public and private properties in the city of New Orleans, Louisiana, U.S.A.

    Mielke, Howard W; Gonzales, Christopher R; Powell, Eric T; Mielke, Paul W

    2017-05-01

    Anthropogenic re-distribution of lead (Pb) principally through its use in gasoline additives and lead-based paints have transformed the urban exposome. This unique study tracks urban-scale soil Pb (SPb) and blood Pb (BPb) responses of children living in public and private communities in New Orleans before and ten years after Hurricane Katrina (29 August 2005). To compare and evaluate associations of pre- and ten years post-Katrina SPb and children's BPb on public and private residential census tracts in the core and outer areas of New Orleans, and to examine correlations between SPb and nine other soil metals. The Louisiana Healthy Housing and Childhood Lead Poisoning Prevention Program BPb (µg/dL) data from pre- (2000-2005) and post-Katrina (2010-2015) for ≤6-year-old children. Data from public and adjacent private residential census tracts within core and outer areas are stratified from a database that includes 916 and 922 SPb and 13,379 and 4830 BPb results, respectively, from pre- and post-Katrina New Orleans. Statistical analyses utilize Multi-Response Permutation Procedure and Spearman's Rho Correlation. Pre- to Post-Katrina median SPb decreases in public and private core census tracts were from 285 to 55mg/kg and 710-291mg/kg, respectively. In public and private outer census tracts the median SPb decreased from 109 to 56mg/kg and 88-55mg/kg. Children's BPb percent ≥5µg/dL on public and private core areas pre-Katrina was 63.2% and 67.5%, and declined post-Katrina to 7.6% and 20.2%, respectively. BPb decreases also occurred in outer areas. Soil Pb is strongly correlated with other metals. Post-Katrina re-building of public housing plus landscaping amends the exposome and reduces children's BPb. Most importantly, Hurricane Katrina revealed that decreasing the toxicants in the soil exposome is an effective intervention for decreasing children's BPb. Copyright © 2017 Elsevier Inc. All rights reserved.

  2. Microbes in Heavy Metal Remediation: A Review on Current Trends and Patents.

    Mishra, Geetesh Kumar

    2017-01-01

    Heavy metal pollution in the environmental samples like soil, water and runoff water is a worldwide problem. Such contamination of environmental matrices by the heavy metals accumulates due to various activities involving human driven sources and industries, although agriculture and sewage disposal are the largest source for the heavy metal contamination. Disposal of heavy metals or waste products containing heavy metals in the environment postures a trivial threat to public safety and health. Heavy metals are persistence and they can also cause biomagnifications and accumulate in food chain. Microbial bioremediation of heavy metal is emerging as an effective technique. Microbial bioremediation is a highly efficient environmental friendly procedure which also reduces the cost of cleanup process associated with heavy metal contamination. New methods for removal of heavy metals from the environmental samples are under development and most recent advancements have been made in exploring the knowledge of metal-microbes interactions and its use for heavy metal remediation. This review paper will focus on the microbial bioremediation process and highlight some of the newly developed patented methods for microbial bioremediation of the heavy metals from the environmental samples using microbial populations. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

  3. Upgrade of the Gas Flow Control System of the Resistive Current Leads of the LHC Inner Triplet Magnets: Simulation and Experimental Validation

    Perin, A; Casas-Cubillos, J; Pezzetti, M

    2014-01-01

    The 600 A and 120 A circuits of the inner triplet magnets of the Large Hadron Collider are powered by resistive gas cooled current leads. The current solution for controlling the gas flow of these leads has shown severe operability limitations. In order to allow a more precise and more reliable control of the cooling gas flow, new flowmeters will be installed during the first long shutdown of the LHC. Because of the high level of radiation in the area next to the current leads, the flowmeters will be installed in shielded areas located up to 50 m away from the current leads. The control valves being located next to the current leads, this configuration leads to long piping between the valves and the flowmeters. In order to determine its dynamic behaviour, the proposed system was simulated with a numerical model and validated with experimental measurements performed on a dedicated test bench.

  4. Upgrade of the gas flow control system of the resistive current leads of the LHC inner triplet magnets: Simulation and experimental validation

    Perin, A.; Casas-Cubillos, J.; Pezzetti, M. [CERN, CH-1211 Geneva 23 (Switzerland); Almeida, M. [Universidade Federal de Minas Gerais, 31270-901 Belo Horizonte (Brazil)

    2014-01-29

    The 600 A and 120 A circuits of the inner triplet magnets of the Large Hadron Collider are powered by resistive gas cooled current leads. The current solution for controlling the gas flow of these leads has shown severe operability limitations. In order to allow a more precise and more reliable control of the cooling gas flow, new flowmeters will be installed during the first long shutdown of the LHC. Because of the high level of radiation in the area next to the current leads, the flowmeters will be installed in shielded areas located up to 50 m away from the current leads. The control valves being located next to the current leads, this configuration leads to long piping between the valves and the flowmeters. In order to determine its dynamic behaviour, the proposed system was simulated with a numerical model and validated with experimental measurements performed on a dedicated test bench.

  5. Effect of localized states on the current-voltage characteristics of metal-semiconductor contacts with thin interfacial layer

    Chattopadhyay, P.

    1994-10-01

    The role of discrete localized states on the current-voltage characteristics of metal-semiconductor contact is examined. It is seen that, because of these localized states, the logarithmic current vs voltage characteristics become nonlinear. Such nonlinearity is found sensitive to the temperature, and the energy and density of the localized states. The predicted temperature dependence of barrier height and the current-voltage characteristics are in agreement with the experimental results of Aboelfotoh [ Phys. Rev. B39, 5070 (1989)].

  6. Role of perfluoropolyether-based electrolytes in lithium metal batteries: Implication for suppressed Al current collector corrosion and the stability of Li metal/electrolytes interfaces

    Cong, Lina; Liu, Jia; Armand, Michel; Mauger, Alain; Julien, Christian M.; Xie, Haiming; Sun, Liqun

    2018-03-01

    The development of safe and high performance lithium metal batteries represents a major technological challenge for this new century. Historically, intrinsic instabilities of conventional liquid organic electrolytes induced battery failures and safety issues that hinder the practical utilization of advanced rechargeable lithium metal batteries. Herein, we report a multifunctional perfluoropolyether-based liquid polymer electrolyte (PFPE-MC/LiTFSI), presenting a unique "anion-solvent" interaction. This interaction optimizes the interfacial chemistry of lithium metal batteries, which effectively inhibits the corrosion of aluminum current collectors, suppresses lithium dendrite growth, and also facilitates the formation of a thin and stable SEI layer on Li anode. Even at a high current density of 0.7 mA cm-2, the lithium dendrites do not form after 1360 h of continuous operation. The LiFePO4|PFPE-MC/LiTFSI|Li cell delivers a stable cycling performance with over 99.9% columbic efficiency either at ambient temperature or high temperature, which is significantly superior to those using traditional carbonate electrolytes. In addition, PFPE-MC/LiTFSI electrolyte also possesses eye-catching properties, such as being non-flammable, non-volatile, non-hygroscopic, and existing in the liquid state between -90 °C and 200 °C, which further ensures the high safety of the lithium metal batteries, making this electrolyte promising for the development of high energy lithium metal batteries.

  7. Unknown risk: co-exposure to lead and other heavy metals among children living in small-scale mining communities in Zamfara State, Nigeria.

    Bartrem, Casey; Tirima, Simba; von Lindern, Ian; von Braun, Margrit; Worrell, Mary Claire; Mohammad Anka, Shehu; Abdullahi, Aishat; Moller, Gregory

    2014-08-01

    The lead poisoning crisis in Zamfara State, Northern Nigeria has been called the worst such case in modern history and it presents unique challenges for risk assessment and management of co-exposure to multiple heavy metals. More than 400 children have died in Zamfara as a result of ongoing lead intoxication since early in 2010. A review of the common toxic endpoints of the major heavy metals advances analysis of co-exposures and their common pathologies. Environmental contamination in Bagega village, examined by X-ray fluorescence of soils, includes lead, mercury, cadmium, arsenic and manganese. Co-exposure risk is explored by scoring common toxic endpoints and hazard indices to calculate a common pathology hazard risk ranking of Pb > As > Hg > Cd > Mn. Zamfara presents an extreme picture of both lead and multiple heavy metal mortality and morbidity, but similar situations have become increasingly prevalent worldwide.

  8. Combining tree-ring metal concentrations and lead, carbon and oxygen isotopes to reconstruct peri-urban atmospheric pollution

    Annick Doucet

    2012-08-01

    Full Text Available In this study, we analysed the tree-ring metal concentrations and isotope ratios of five stands located in three contrasted settings to infer the diffuse air pollution history of the northern part of the Windsor–Québec City Corridor in eastern Canada. Tree-ring series show that the Cd and Zn accumulation rates were higher between 1960 and 1986 and that the long-term acidification of the soil (Ca/Al series was likely induced by NOx and SOx deposition (δ15N and δ13C trends as proxy. The Pb concentrations and 206Pb/207Pb ratios indicate that the dominant source of lead from 1880 to the 1920s was the combustion of north-eastern American coal, which was succeeded by the combustion of leaded gasoline from the 1920s to the end of the 1980s. Our modelling approach allows separating the climatic and anthropogenic effects on the tree-ring δ13C and δ18O responses. Diffuse air pollution caused an enrichment in 13C in all stands and a decrease of the δ18O values only in three of the stands. This study indicates that dendrogeochemistry can show contrasted responses to environmental changes and that the combination of several independent indicators constitutes a powerful tool to reconstruct the air pollution history in the complex context of peri-urban regions.

  9. Adsorption by and artificial release of zinc and lead from porous concrete for recycling of adsorbed zinc and lead and of porous concrete to reduce urban non-point heavy metal runoff.

    Harada, Shigeki; Yanbe, Miyu

    2018-04-01

    This report describes the use of porous concrete at the bottom of a sewage trap to prevent runoff of non-point heavy metals into receiving waters, and, secondarily, to reduce total runoff volume during heavy rains in urbanized areas while simultaneously increasing the recharge volume of heavy-metal-free water into underground aquifers. This idea has the advantage of preventing clogging, which is fundamentally very important when using pervious materials. During actual field experiments, two important parameters were identified: maximum adsorption weight of lead and zinc by the volume of porous concrete, and heavy metal recovery rate by artificial acidification after adsorption. To understand the effect of ambient heavy metal concentration, a simple mixing system was used to adjust the concentrations of lead and zinc solutions. The concrete blocks used had been prepared for a previous study by Harada & Komuro (2010). The results showed that maximum adsorption depended on the ambient concentration, expressed as the linear isothermal theory, and that recovery depended on the final pH value (0.5 or 0.0). The dependence on pH is very important for recycling the porous concrete. A pH of 0.5 is important for recycling both heavy metals, especially zinc, (8.0-22.1% of lead and 42-74% of zinc) and porous concrete because porous concrete has not been heavily damaged by acid. However, at a pH of 0.0, the heavy metals could be recovered: 30-60% of the lead and 75-125% of the zinc. At a higher pH, such as 2.0, no release of heavy metals occurred, indicating the safety to the environment of using porous concrete, because the lowest recorded pH of rainfall in Japan is. 4.0. Copyright © 2018 Elsevier Ltd. All rights reserved.

  10. LiCl-LiI molten salt electrolyte with bismuth-lead positive electrode for liquid metal battery

    Kim, Junsoo; Shin, Donghyeok; Jung, Youngjae; Hwang, Soo Min; Song, Taeseup; Kim, Youngsik; Paik, Ungyu

    2018-02-01

    Liquid metal batteries (LMBs) are attractive energy storage device for large-scale energy storage system (ESS) due to the simple cell configuration and their high rate capability. The high operation temperature caused by high melting temperature of both the molten salt electrolyte and metal electrodes can induce the critical issues related to the maintenance cost and degradation of electrochemical properties resulting from the thermal corrosion of materials. Here, we report a new chemistry of LiCl-LiI electrolyte and Bi-Pb positive electrode to lower the operation temperature of Li-based LMBs and achieve the long-term stability. The cell (Li|LiCl-LiI|Bi-Pb) is operated at 410 °C by employing the LiCl-LiI (LiCl:LiI = 36:64 mol %) electrolyte and Bi-Pb alloy (Bi:Pb = 55.5:44.5 mol %) positive electrode. The cell shows excellent capacity retention (86.5%) and high Coulombic efficiencies over 99.3% at a high current density of 52 mA cm-2 during 1000th cycles.

  11. Theoretical estimates of supernova-neutrino cross sections for the stable even-even lead isotopes: Charged-current reactions

    Almosly, W.; Carlsson, B. G.; Suhonen, J.; Toivanen, J.; Ydrefors, E.

    2016-10-01

    A detailed study of the charged-current supernova electron neutrino and electron antineutrino scattering off the stable even-mass lead isotopes A =204 , 206, and 208 is reported in this work. The proton-neutron quasiparticle random-phase approximation (pnQRPA) is adopted to construct the nuclear final and initial states. Three different Skyrme interactions are tested for their isospin and spin-isospin properties and then applied to produce (anti)neutrino-nucleus scattering cross sections for (anti)neutrino energies below 80 MeV. Realistic estimates of the nuclear responses to supernova (anti)neutrinos are computed by folding the computed cross sections with a two-parameter Fermi-Dirac distribution of the electron (anti)neutrino energies. The computed cross sections are compared with earlier calculations and the analyses are extended to take into account the effects coming from the neutrino oscillations.

  12. Conceptual design of a forced-flow-cooled 20-kA current lead using Ag-alloy-sheathed Bi-2223 high-temperature superconductors

    Heller, R.

    1994-11-01

    The use of high-temperature superconductors in current leads to reduce refrigeration power has been investigated by many groups in the past. Most used YBCO and Bi-2212 bulk superconductors, although their critical current density is not very high. In this paper, BI-2223 HTSC tapes sheathed with Ag alloys are used in the design of a 20-kA current lead because of their higher critical current in medium magnetic fields. The lead current of 20 kA is related to the coil current of the planned stellarator WENDELSTEIN 7-X. Forced-now helium cooling has been used in the design, allowing position-independent and well-controlled operation. The design characteristics of the lead are presented and 4-K helium cooling of the whole lead, as well as 60-K helium cooling of the copper part of the lead, is discussed. The power consumption at zero current, and the lead's behaviour in case of loss of coolant flow, are given, The results of the design allow extrapolation to current leads of the 50-kA range

  13. Investigation of corrosion, water reaction, polonium evaporation and bismuth resource in liquid metal lead-bismuth technology

    Takano, Hideki; Takizuka, Takakazu [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment; Kitano, Teruaki [Mitsui Shipbuilding and Engineering Co. Ltd., Tokyo (Japan)

    2000-10-01

    Lead-bismuth is the first candidate material for liquid metal target find coolant of fueled blanket system in accelerator-driven system (ADS) studied at JAERI. Advantages of the lead-bismuth utilization are non-active material, very low capture cross section, low melting point of 125degC and high boiling point of 1670degC, and beside coolant void reactivity become negative. But problems are due to the high corrosivity to most of the structural materials and the corrosive data are scarcity. In this report, corrosivity, reaction with water, thermal-hydraulics, chemical toxicity etc. are studied by investigating some facilities utilized and researched really for lead or lead-bismuth. And, furthermore, polonium evaporation rate and bismuth resource are investigated. Main results obtained are as follows: (1) In a refinery, there are enough employment experience for liquid Pb-Bi in period of about 17 years and not corrosion for the thermal conductive materials (1Cr-0.5Mo steel) used under the condition of natural convection with temperature around 400degC. (2) In Russia, extensive experience in the use as Russian submarines and in R and D during about 50 years are available. And as a result, it will be able to lead approximately zero corrosion for Cr-Si materials by adjusting oxygen film with oxygen concentration control between 10{sup -7} to 10{sup -5}% mass. However, the corrosion data are not enough systematically collected involving them in radiation dose field. (3) In liquid-dropping experiment, it is shown that interaction between water and high temperature liquid Pb-Bi is reduced steeply with rising of atmosphere pressure. But, in order to design the second circuit removal model of ADS, the interaction should be evaluated by water continuous injection experiment. (4) Polonium forms PbPo in Pb-Bi, and the evaporation rate become less three factor than that of Po, and furthermore, the rate decreases in the atmosphere. The effects of Po on employee and environment

  14. Bandgap engineering of lead-free double perovskite Cs{sub 2}AgBiBr{sub 6} through trivalent metal alloying

    Du, Ke-zhao; Mitzi, David B. [Department of Mechanical Engineering and Materials Science, and Department of Chemistry, Duke University, Durham, NC (United States); Meng, Weiwei; Wang, Xiaoming; Yan, Yanfa [Department of Physics and Astronomy and Wright Center for Photovoltaics Innovation and Commercialization, The University of Toledo, OH (United States)

    2017-07-03

    The double perovskite family, A{sub 2}M{sup I}M{sup III}X{sub 6}, is a promising route to overcome the lead toxicity issue confronting the current photovoltaic (PV) standout, CH{sub 3}NH{sub 3}PbI{sub 3}. Given the generally large indirect band gap within most known double perovskites, band-gap engineering provides an important approach for targeting outstanding PV performance within this family. Using Cs{sub 2}AgBiBr{sub 6} as host, band-gap engineering through alloying of In{sup III}/Sb{sup III} has been demonstrated in the current work. Cs{sub 2}Ag(Bi{sub 1-x}M{sub x})Br{sub 6} (M=In, Sb) accommodates up to 75 % In{sup III} with increased band gap, and up to 37.5 % Sb{sup III} with reduced band gap; that is, enabling ca. 0.41 eV band gap modulation through introduction of the two metals, with smallest value of 1.86 eV for Cs{sub 2}Ag(Bi{sub 0.625}Sb{sub 0.375})Br{sub 6}. Band structure calculations indicate that opposite band gap shift directions associated with Sb/In substitution arise from different atomic configurations for these atoms. Associated photoluminescence and environmental stability of the three-metal systems are also assessed. (copyright 2017 Wiley-VCH Verlag GmbH and Co. KGaA, Weinheim)

  15. Hot stars in young massive clusters: Mapping the current Galactic metallicity

    de la Fuente, Diego; Najarro, Francisco; Davies, Ben; Trombley, Christine; Figer, Donald F.; Herrero, Artemio

    2013-06-01

    Young Massive Clusters (YMCs) with ages guarantee that these objects present the same chemical composition than the surrounding environment where they are recently born. Finally, the YMCs host very massive stars whose extreme luminosities allow to accomplish detailed spectroscopic analyses even in the most distant regions of the Milky Way. Our group has carried out ISAAC/VLT spectroscopic observations of hot massive stars belonging to several YMCs in different locations around the Galactic disk. As a result, high signal-to-noise, near-infrared spectra of dozens of blue massive stars (including many OB supergiants, Wolf-Rayet stars and a B hypergiant) have been obtained. These data are fully reduced, and NLTE spherical atmosphere modeling is in process. Several line diagnostics will be combined in order to calculate metal abundances accurately for each cluster. The diverse locations of the clusters will allow us to draw a two-dimensional chemical map of the Galactic disk for the first time. The study of the radial and azimuthal variations of elemental abundances will be crucial for understanding the chemical evolution of the Milky Way. Particularly, the ratio between Fe-peak and alpha elements will constitute a powerful tool to investigate the past stellar populations that originated the current Galactic chemistry.

  16. Exposure of Bacterial Biofilms to Electrical Current Leads to Cell Death Mediated in Part by Reactive Oxygen Species.

    Brinkman, Cassandra L; Schmidt-Malan, Suzannah M; Karau, Melissa J; Greenwood-Quaintance, Kerryl; Hassett, Daniel J; Mandrekar, Jayawant N; Patel, Robin

    2016-01-01

    Bacterial biofilms may form on indwelling medical devices such as prosthetic joints, heart valves and catheters, causing challenging-to-treat infections. We have previously described the 'electricidal effect', in which bacterial biofilms are decreased following exposure to direct electrical current. Herein, we sought to determine if the decreased bacterial quantities are due to detachment of biofilms or cell death and to investigate the role that reactive oxygen species (ROS) play in the observed effect. Using confocal and electron microscopy and flow cytometry, we found that direct current (DC) leads to cell death and changes in the architecture of biofilms formed by Gram-positive and Gram-negative bacteria. Reactive oxygen species (ROS) appear to play a role in DC-associated cell death, as there was an increase in ROS-production by Staphylococcus aureus and Staphylococcus epidermidis biofilms following exposure to DC. An increase in the production of ROS response enzymes catalase and superoxide dismutase (SOD) was observed for S. aureus, S. epidermidis and Pseudomonas aeruginosa biofilms following exposure to DC. Additionally, biofilms were protected from cell death when supplemented with antioxidants and oxidant scavengers, including catalase, mannitol and Tempol. Knocking out SOD (sodAB) in P. aeruginosa led to an enhanced DC effect. Microarray analysis of P. aeruginosa PAO1 showed transcriptional changes in genes related to the stress response and cell death. In conclusion, the electricidal effect results in death of bacteria in biofilms, mediated, at least in part, by production of ROS.

  17. Variations in Metal Tolerance and Accumulation in Three Hydroponically Cultivated Varieties of Salix integra Treated with Lead

    Sun, Haijing; Chen, Yitai; Pan, Hongwei; Yang, Xiaoe; Rafiq, Tariq

    2014-01-01

    Willow species have been suggested for use in the remediation of contaminated soils due to their high biomass production, fast growth, and high accumulation of heavy metals. The tolerance and accumulation of metals may vary among willow species and varieties, and the assessment of this variability is vital for selecting willow species/varieties for phytoremediation applications. Here, we examined the variations in lead (Pb) tolerance and accumulation of three cultivated varieties of Salix integra (Weishanhu, Yizhibi and Dahongtou), a shrub willow native to northeastern China, using hydroponic culture in a greenhouse. In general, the tolerance and accumulation of Pb varied among the three willow varieties depending on the Pb concentration. All three varieties had a high tolerance index (TI) and EC50 value (the effective concentration of Pb in the nutrient solution that caused a 50% inhibition on biomass production), but a low translocation factor (TF), indicating that Pb sequestration is mainly restricted in the roots of S. integra. Among the three varieties, Dahogntou was more sensitive to the increased Pb concentration than the other two varieties, with the lowest EC50 and TI for root and above-ground tissues. In this respect, Weishanhu and Yizhibi were more suitable for phytostabilization of Pb-contaminated soils. However, our findings also indicated the importance of considering the toxicity symptoms when selecting willow varieties for the use of phytoremediation, since we also found that the three varieties revealed various toxicity symptoms of leaf wilting, chlorosis and inhibition of shoot and root growth under the higher Pb concentrations. Such symptoms could be considered as a supplementary index in screening tests. PMID:25268840

  18. Variations in metal tolerance and accumulation in three hydroponically cultivated varieties of Salix integra treated with lead.

    Shufeng Wang

    Full Text Available Willow species have been suggested for use in the remediation of contaminated soils due to their high biomass production, fast growth, and high accumulation of heavy metals. The tolerance and accumulation of metals may vary among willow species and varieties, and the assessment of this variability is vital for selecting willow species/varieties for phytoremediation applications. Here, we examined the variations in lead (Pb tolerance and accumulation of three cultivated varieties of Salix integra (Weishanhu, Yizhibi and Dahongtou, a shrub willow native to northeastern China, using hydroponic culture in a greenhouse. In general, the tolerance and accumulation of Pb varied among the three willow varieties depending on the Pb concentration. All three varieties had a high tolerance index (TI and EC50 value (the effective concentration of Pb in the nutrient solution that caused a 50% inhibition on biomass production, but a low translocation factor (TF, indicating that Pb sequestration is mainly restricted in the roots of S. integra. Among the three varieties, Dahogntou was more sensitive to the increased Pb concentration than the other two varieties, with the lowest EC50 and TI for root and above-ground tissues. In this respect, Weishanhu and Yizhibi were more suitable for phytostabilization of Pb-contaminated soils. However, our findings also indicated the importance of considering the toxicity symptoms when selecting willow varieties for the use of phytoremediation, since we also found that the three varieties revealed various toxicity symptoms of leaf wilting, chlorosis and inhibition of shoot and root growth under the higher Pb concentrations. Such symptoms could be considered as a supplementary index in screening tests.

  19. Different Reactive Oxygen Species Lead to Distinct Changes of Cellular Metal Ions in the Eukaryotic Model Organism Saccharomyces cerevisiae

    Peter J. Rogers

    2011-11-01

    Full Text Available Elemental uptake and export of the cell are tightly regulated thereby maintaining the ionomic homeostasis. This equilibrium can be disrupted upon exposure to exogenous reactive oxygen species (ROS, leading to reduction or elevation of the intracellular metal ions. In this study, the ionomic composition in the eukaryotic model organism Saccharomyces cerevisiae was profiled using the inductively-coupled plasma optical emission spectrometer (ICP-OES following the treatment with individual ROS, including hydrogen peroxide, cumen hydroperoxide, linoleic acid hydroperoxide (LAH, the superoxide-generating agent menadione, the thiol-oxidising agent diamide [diazine-dicarboxylic acid-bis(dimethylamide], dimedone and peroxynitrite. The findings demonstrated that different ROS resulted in distinct changes in cellular metal ions. Aluminium (Al3+ level rose up to 50-fold after the diamide treatment. Cellular potassium (K+ in LAH-treated cells was 26-fold less compared to the non-treated controls. The diamide-induced Al3+ accumulation was further validated by the enhanced Al3+ uptake along the time course and diamide doses. Pre-incubation of yeast with individual elements including iron, copper, manganese and magnesium failed to block diamide-induced Al3+ uptake, suggesting Al3+-specific transporters could be involved in Al3+ uptake. Furthermore, LAH-induced potassium depletion was validated by a rescue experiment in which addition of potassium increased yeast growth in LAH-containing media by 26% compared to LAH alone. Taken together, the data, for the first time, demonstrated the linkage between ionomic profiles and individual oxidative conditions.

  20. Group 13 ligand supported heavy-metal complexes: first structural evidence for gallium-lead and gallium-mercury bonds.

    Prabusankar, Ganesan; Gemel, Christian; Winter, Manuela; Seidel, Rüdiger W; Fischer, Roland A

    2010-05-25

    Heavy-metal complexes of lead and mercury stabilized by Group 13 ligands were derived from the oxidative addition of Ga(ddp) (ddp=HC(CMeNC(6)H(3)-2,6-iPr(2))(2), 2-diisopropylphenylamino-4-diisopropyl phenylimino-2-pentene) with corresponding metal precursors. The reaction of Me(3)PbCl and Ga(ddp) afforded compound [{(ddp)Ga(Cl)}PbMe(3)] (1) composed of Ga-Pb(IV) bonds. In addition, the monomeric plumbylene-type compound [{(ddp)Ga(OSO(2)CF(3))}(2)Pb(thf)] (2a) with an unsupported Ga-Pb(II)-Ga linkage was obtained by the reaction of [Pb(OSO(2)CF(3))(3)] with Ga(ddp) (2 equiv). Compound 2a falls under the rare example of a discrete plumbylene-type compound supported by a nonclassical ligand. Interesting structural changes were observed when [Pb(OSO(2)CF(3))(3)]2.H(2)O was treated with Ga(ddp) in a 1:2 ratio to yield [{(ddp)Ga(mu-OSO(2)CF(3))}(2)(OH(2))Pb] (2b) at below -10 degrees C. Compound 2b consists of a bent Ga-Pb-Ga backbone with a bridging triflate group between the Ga-Pb bond and a weakly interacting water molecule at the gallium center. Similarly, the reaction of mercury thiolate Hg(SC(6)F(5)) with Ga(ddp) (2 equiv) produced the bimetallic homoleptic compounds anti-[{(ddp)Ga(SC(6)F(5))}(2)Hg] (3a) and gauche-[{(ddp)Ga(SC(6)F(5))}(2)Hg] (3b), respectively, with a linear Ga-Hg-Ga linkage. Compounds 1-3 were structurally characterized and these are the first examples of compounds comprised of Ga-Pb(II), Ga-Pb(IV), and Ga-Hg bonds.

  1. Cytotoxic and phenotypic effects of uranium and lead on osteoblastic cells are highly dependent on metal speciation

    Milgram, S.; Carriere, M.; Thiebault, C.; Malaval, L.; Gouget, B.

    2008-01-01

    Bone is one of the main retention organs for uranium (U) and lead (Pb). The clinical effects of U or Pb poisoning are well known: acute and chronic intoxications impair bone formation. However, only few studies dealt with the cellular and molecular mechanisms of their toxicity. The purpose of this study was to investigate acute cytotoxicity of U and Pb and their phenotypic effects on rat and human osteoblasts, the cells responsible for bone formation. The most likely species of the toxicants in contact with cells after blood contamination were selected for cell exposure. Results showed that the cytotoxic effect of U and Pb is highly dependent on their speciation. Thus, Pb was cytotoxic when left free in the exposure medium or when complexed with carbonate, cystein or citrate, but not when complexed with albumin or phosphate, under an insoluble form. U was cytotoxic whatever its speciation, but differences in sensitivity were observed as a function of speciation. Population growth recovery could be obtained after exposure to low doses of U or Pb, except for some U-carbonate complexes which had irreversible effects whatever the dose. The activation of two markers of bone formation and mineralization, osteocalcin and bone sialoprotein (BSP), was observed after exposure to non-toxic doses or non-toxic species of U or Pb while their inhibition was observed after toxic exposure to both metals. This work provides new elements to better understand the complex mechanisms of U and Pb toxicity to osteoblasts. Our results also illustrate the importance of a strictly controlled speciation of the metals in toxicological studies

  2. New pathway for the formation of metallic cubic phase Ge-Sb-Te compounds induced by an electric current.

    Park, Yong-Jin; Cho, Ju-Young; Jeong, Min-Woo; Na, Sekwon; Joo, Young-Chang

    2016-02-23

    The novel discovery of a current-induced transition from insulator to metal in the crystalline phase of Ge2Sb2Te5 and GeSb4Te7 have been studied by means of a model using line-patterned samples. The resistivity of cubic phase Ge-Sb-Te compound was reduced by an electrical current (~1 MA/cm(2)), and the final resistivity was determined based on the stress current density, regardless of the initial resistivity and temperature, which indicates that the conductivity of Ge-Sb-Te compound can be modulated by an electrical current. The minimum resistivity of Ge-Sb-Te materials can be achieved at high kinetic rates by applying an electrical current, and the material properties change from insulating to metallic behavior without a phase transition. The current-induced metal transition is more effective in GeSb4Te7 than Ge2Sb2Te5, which depends on the intrinsic vacancy of materials. Electromigration, which is the migration of atoms induced by a momentum transfer from charge carriers, can easily promote the rearrangement of vacancies in the cubic phase of Ge-Sb-Te compound. This behavior differs significantly from thermal annealing, which accompanies a phase transition to the hexagonal phase. This result suggests a new pathway for modulating the electrical conductivity and material properties of chalcogenide materials by applying an electrical current.

  3. 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

    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

  4. Novel Method for Sizing Metallic Bottom Crack Depth Using Multi-frequency Alternating Current Potential Drop Technique

    Li, Yuting; Gan, Fangji; Wan, Zhengjun; Liao, Junbi; Li, Wenqiang

    2015-10-01

    Potential drop techniques are of two types: the direct current potential drop (DCPD) technique and alternating current potential drop (ACPD) technique, and both of them are used in nondestructive testing. ACPD, as a kind of valid method in sizing metal cracks, has been applied to evaluate metal structures. However, our review of most available approaches revealed that some improvements can be done in measuring depth of metal bottom crack by means of ACPD, such as accuracy and sensitivity of shallow crack. This paper studied a novel method which utilized the slope of voltage ratio-frequency curve to solve bottom crack depth by using a simple mathematic equation based on finite element analysis. It is found that voltage ratio varies linearly with frequency in the range of 5-15 Hz; this range is slightly higher than the equivalent frequency and lower than semi-permeable frequency. Simulation and experiment show that the novel method can measure the bottom crack depth accurately.

  5. High Charge State Ions Extracted from Metal Plasmas in the Transition Regime from Vacuum Spark to High Current Vacuum Arc

    Yushkov, Georgy Yu.; Anders, A.

    2008-01-01

    Metal ions were extracted from pulsed discharge plasmas operating in the transition region between vacuum spark (transient high voltage of kV) and vacuum arc (arc voltage ∼ 20 V). At a peak current of about 4 kA, and with a pulse duration of 8 (micro)s, we observed mean ion charges states of about 6 for several cathode materials. In the case of platinum, the highest average charge state was 6.74 with ions of charge states as high as 10 present. For gold we found traces of charge state 11, with the highest average charge state of 7.25. At currents higher than 5 kA, non-metallic contaminations started to dominate the ion beam, preventing further enhancement of the metal charge states

  6. 1-D thermal-hydraulic analysis of the high temperature superconducting current leads for the ITER magnet system from 5 K to 300 K

    Rizzo, Enrico, E-mail: enrico.rizzo@kit.edu [Institute for Technical Physics, Karlsruhe Institute of Technology, 76344 Eggenstein-Leopoldshafen (Germany); Bauer, Pierre [ITER Organization, Cadarache (France); Heller, Reinhard [Institute for Technical Physics, Karlsruhe Institute of Technology, 76344 Eggenstein-Leopoldshafen (Germany); Richard, Laura Savoldi; Zanino, Roberto [Dipartimento Energia, Politecnico di Torino, 10129 Torino (Italy)

    2013-12-15

    Highlights: • A global, predictive picture of the ITER HTS current lead is not yet available. • A predictive 1-D, steady state thermal-hydraulic analysis of the full length HTS current leads has been performed. • For the heat exchanger, correlations previously derived by the same authors have been used. • The results have been compared with the ITER relevant requirements. • According to our results, the ITER HTS current leads will fulfill the requirements. -- Abstract: The magnet system of ITER includes high temperature superconducting (HTS) current leads with a maximum current of 68 kA for the toroidal field (TF) coils, 55 kA for the poloidal field (PF)/central solenoid (CS) coils and 10 kA for the control coils (CC), respectively. Although different in terms of size and operative conditions, the ITER HTS current leads have been all designed on the basis of an established concept, which was successfully developed for the LHC at CERN and proven by the so-called 70 kA “demonstrator” lead made by KIT and by the ITER pre-prototypes made by ASIPP in China. A broad R and D campaign has been undertaken by ASIPP and CERN in order to find optimized designs for each component of the leads. Nevertheless, a comprehensive picture of the performance of the entire HTS current leads is not yet available. In this paper, a steady state, full length, thermal-hydraulic 1-D modeling is applied to the study of the three types (TF, PF/CS, CC) of ITER HTS current leads. The results of this predictive analysis are then compared with relevant ITER requirements. It was found that the present design of the HTS current leads will fulfill these specifications.

  7. A systematic study of biochemical effects of heavy metal pollution. Programme of the research and preliminary results on cadmium and lead

    Sabbioni, E.; Girardi, F.; Marafante, E.

    1975-01-01

    The distribution of labelled metal pollutants at low-dose in organs, subcellular fractions and isolated and fractional component of subcellular fractions, in view of identifying specific metal binding component, was studied. Two types of experiments were carried out, on rats. Long-term experiments (up to 3-4 months), the labelled metal was administred at low concentrations (environmental levels) over long periods of time in order to simulate as close as possible the conditions of polluted environments. Short-term experiments (1-7 days), the labelled metal was injected at acute or subacute levels. 5 elements were selected (Cd, Zn, Se, Hg, Cr) for the long term experiments and 4 elements (Pb, V, Ni, Be) for the short term experiments. The essential present knowledge on the behavior at cellular level of heavy metals which were chosen were summarized. Preliminary results on biochemical effects of cadmium and lead were reported

  8. A new model of dispersion for metals leading to a more accurate modeling of plasmonic structures using the FDTD method

    Vial, A.; Dridi, M.; Cunff, L. le [Universite de Technologie de Troyes, Institut Charles Delaunay, CNRS UMR 6279, Laboratoire de Nanotechnologie et d' Instrumentation Optique, 12, rue Marie Curie, BP-2060, Troyes Cedex (France); Laroche, T. [Universite de Franche-Comte, Institut FEMTO-ST, CNRS UMR 6174, Departement de Physique et de Metrologie des Oscillateurs, Besancon Cedex (France)

    2011-06-15

    We present FDTD simulations results obtained using the Drude critical points model. This model enables spectroscopic studies of metallic structures over wider wavelength ranges than usually used, and it facilitates the study of structures made of several metals. (orig.)

  9. Decay heat removal analyses on the heavy liquid metal cooled fast breeding reactor. Comparisons of the decay heat removal characteristics on lead, lead-bismuth and sodium cooled reactors

    Sakai, Takaaki; Ohshima, Hiroyuki; Yamaguchi, Akira

    2000-04-01

    The feasibility study on several concepts for the commercial fast breeder reactor(FBR) in future has been conducted in JNC for the kinds of possible coolants and fuel types to confirm the direction of the FBR developments in Japan. In this report, Lead and Lead-Bismuth eutectic coolants were estimated for the decay heat removal characteristics by the comparison with sodium coolant that has excellent features for the heat transfer and heat transport performance. Heavy liquid metal coolants, such as Lead and Lead-Bismuth, have desirable chemical inertness for water and atmosphere. Therefore, there are many economical plant proposals without an intermediate heat transport system that prevents the direct effect on a reactor core by the chemical reaction between water and the liquid metal coolant at the hypocritical tube failure accidents in a steam generator. In this study, transient analyses on the thermal-hydraulics have been performed for the decay heat removal events in Equivalent plant' with the Lead, Lead-Bismuth and Sodium coolant by using Super-COPD code. And a resulted optimized lead cooled plant in feasibility study was also analyzed for the comparison. In conclusion, it is become clear that the natural circulation performance, that has an important roll in passive safety characteristic of the reactor, is more excellent in heavy liquid metals than sodium coolant during the decay heat removal transients. However, we need to confirm the heat transfer reduction by the oxidized film or the corrosion products expected to appear on the heat transfer surface in the Lead and Lead-Bismuth circumstance. (author)

  10. Enhancement of chitosan-graphene oxide SPR sensor with a multi-metallic layers of Au–Ag–Au nanostructure for lead(II) ion detection

    Kamaruddin, Nur Hasiba [Department of Electric, Electronic and Systems Engineering, Faculty of Engineering and Built Environment, Universiti Kebangsaan Malaysia, 43600 UKM Bangi, Selangor (Malaysia); Bakar, Ahmad Ashrif A., E-mail: ashrif@ukm.edu.my [Department of Electric, Electronic and Systems Engineering, Faculty of Engineering and Built Environment, Universiti Kebangsaan Malaysia, 43600 UKM Bangi, Selangor (Malaysia); Yaacob, Mohd Hanif; Mahdi, Mohd Adzir [Wireless and Photonic Network Research Centre, Faculty of Engineering, Universiti Putra Malaysia, 43400 Serdang, Selangor (Malaysia); Zan, Mohd Saiful Dzulkefly [Department of Electric, Electronic and Systems Engineering, Faculty of Engineering and Built Environment, Universiti Kebangsaan Malaysia, 43600 UKM Bangi, Selangor (Malaysia); Shaari, Sahbudin [Institute of Microengineering and Nanoelectronics, Universiti Kebangsaan Malaysia, 43600 UKM Bangi, Selangor (Malaysia)

    2016-01-15

    Highlights: • Tri-metallic Au–Ag–Au CS-GO SPR sensor was fabricated for the first time. • The tri-metallic nanostructure provided an enhanced evanescent field. • Successful functionalization of the CS-GO sensing layer. • Superior performance for lead(II) ion detection. - Abstract: We demonstrate the enhancement of surface plasmon resonance (SPR) technique by implementing a multi-metallic layers of Au–Ag–Au nanostructure in the chitosan-graphene oxide (CS-GO) SPR sensor for lead(II) ion detection. The performance of the sensor is analyzed via SPR measurements, from which the sensitivity, signal-to-noise ratio and repeatability are determined. The nanostructure layers are characterized using field emission scanning electron microscopy (FESEM), atomic force microscopy (AFM), X-ray diffraction (XRD), Raman spectroscopy and X-ray photoelectron spectroscopy (XPS). We showed that the proposed structure has increased the shift in the SPR angle up to 3.5° within the range of 0.1–1 ppm due to the enhanced evanescent field at the sensing layer-analyte interface. This sensor also exhibits great repeatability which benefits from the stable multi-metallic nanostructure. The SNR value of 0.92 for 5 ppm lead(II) ion solution and reasonable linearity range up to that concentration shows that the tri-metallic CS-GO SPR sensor gives a good response towards the lead(II) ion solution. The CS-GO SPR sensor is also sensitive to at least a 10{sup −5} change in the refractive index. The results prove that our proposed tri-metallic CS-GO SPR sensor demonstrates a strong performance and reliability for lead(II) ion detection in accordance with the standardized lead safety level for wastewater.

  11. Spintronics with metals: Current perpendicular-to-the-plane magneto-transport studies

    Sharma, Amit

    In this thesis, we present studies to produce new information about three topics: current perpendicular to the plane magnetoresistance (CPP-MR), spin transfer torque (STT), and antiferromagnetic spintronics. Large values of CPP-MR interface parameters---specific interface resistance (Area times resistance), 2AR*, and scattering asymmetry, gamma---are desirable for the use of CPP-MR in devices. Stimulated by a nanopillar study by the Cornell Group, we first discovered that Py/Al had an unusually large 2AR*, but a small gamma. In the hope of finding metal pairs with large values of both the interface parameters, the Py/Al studies led us to study the following interfaces: (a) F/Al with F: Py (= Ni84Fe16). Co, Fe, Co91Fe9, and (b) F/N: Py/Pd, Fe/V, Fe/Nb and Co/Pt. None of the metal pairs looks better for CPP-MR devices. The Cornell group also found that bracketing Al with thin Cu in Py/Al/Py nanopillars, gave an MR similar to Py/Al/Py rather than to Py/Cu/Py. To try to understand this result, we studied the effect of Cu/Al/Cu spacers on ADeltaR = AR(AP) - AR(P) of Py exchange biased spin valves (EBSVs). Here AR(AP) and AR(P) are the specific resistances in the anti-parallel (AP) and parallel (P) configurations of the F layers. Intriguingly, fixing the Al thickness tAl = 10 nm and varying tCu has no effect on ADeltaR, but fixing tCu = 10 nm and varying t Al significantly affected ADeltaR. These unusual behaviors are probably due to strong Al and Cu intermixing, with probable formation of some fraction of ordered alloys. Recent calculations predicted that 2AR of Al/Ag interfaces would vary substantially with orientation and with alloying. The latter is a special potential problem, because Al and Ag interdiffuse at room temperature. To compare with the calculations, we determined 2AR of sputtered Al/Ag interfaces with (111) orientation. Our estimate agrees with calculations that assume 4 monolayers of interfacial disorder, consistent with modest intermixing. To aid in

  12. Toxic metals in breast milk samples from Ankara, Turkey: assessment of lead, cadmium, nickel, and arsenic levels.

    Gürbay, Aylin; Charehsaz, Mohammad; Eken, Ayşe; Sayal, Ahmet; Girgin, Gözde; Yurdakök, Murat; Yiğit, Şule; Erol, Dilek Demir; Şahin, Gönül; Aydın, Ahmet

    2012-10-01

    Toxic metals are one of the significant groups of chemical contaminants that humans are exposed to by oral, inhalation, and dermal routes. Exposure to these chemicals begins with intrauterine life and continues during lactation period at the first years of life. Breastfeeding has a much more special place than other nutrition options for infants. However, when possibility of contaminant transfer by breast milk is considered, its safety and quality is essential. Regarding infant and mother health and limited number of information on this field in Turkey, measuring contamination levels in breast milk is important. Therefore, in the present study, lead (Pb), cadmium (Cd), nickel (Ni), and arsenic (As) levels were measured by atomic absorption spectrometry in 64 breast milk samples obtained from mothers from Ankara, Turkey. Pb and Ni levels in breast milk samples were found to be 391.45±269.01 μg/l and 43.94±33.82 μg/l (mean ± SD), respectively. Cd was found only in one of 64 samples, and the level was 4.62 μg/l. As level was below the limit of quantification (LOQ, 7.6 μg/l) in all samples. These findings will accurately direct strategies and solutions of protection against contaminants in order to reduce their levels in biological fluids.

  13. Lead and cadmium in leaves of deciduous trees in Beijing, China: Development of a metal accumulation index (MAI)

    Liu Yanju; Zhu Yongguan; Ding Hui

    2007-01-01

    Lead and cadmium uptake was investigated for common deciduous street trees in Beijing in this study. Species having Cd accumulation included Populus tomentosa, Sophora japonica and Catalpa speciosa. P. tomentosa had the highest ratios between leaf and soil Cd (0.848), followed by S. japonica (0.536), C. speciosa (0.493), Paulownia tomentosa (0.453) and Juglans regia (0.415). Pb levels were high in leaves of C. speciosa, J. regia and Pa. tomentosa. S. japonica had the highest ratio between leaf Pb and soil Pb (0.146), followed by Pa. tomentosa (0.143), Ginko biloba (0.103) and C. speciosa (0.095). A predictive foliar metal accumulation index (MAI) was developed and C. speciosa was calculated to have the highest MAI value (53.8). This suggests that C. speciosa would be a good choice for planting in areas of Beijing where soil contamination with Cd and Pb may be a problem. - Catalpa speciosa had the highest MAI value

  14. Modeling the dark current histogram induced by gold contamination in complementary-metal-oxide-semiconductor image sensors

    Domengie, F., E-mail: florian.domengie@st.com; Morin, P. [STMicroelectronics Crolles 2 (SAS), 850 Rue Jean Monnet, 38926 Crolles Cedex (France); Bauza, D. [CNRS, IMEP-LAHC - Grenoble INP, Minatec: 3, rue Parvis Louis Néel, CS 50257, 38016 Grenoble Cedex 1 (France)

    2015-07-14

    We propose a model for dark current induced by metallic contamination in a CMOS image sensor. Based on Shockley-Read-Hall kinetics, the expression of dark current proposed accounts for the electric field enhanced emission factor due to the Poole-Frenkel barrier lowering and phonon-assisted tunneling mechanisms. To that aim, we considered the distribution of the electric field magnitude and metal atoms in the depth of the pixel. Poisson statistics were used to estimate the random distribution of metal atoms in each pixel for a given contamination dose. Then, we performed a Monte-Carlo-based simulation for each pixel to set the number of metal atoms the pixel contained and the enhancement factor each atom underwent, and obtained a histogram of the number of pixels versus dark current for the full sensor. Excellent agreement with the dark current histogram measured on an ion-implanted gold-contaminated imager has been achieved, in particular, for the description of the distribution tails due to the pixel regions in which the contaminant atoms undergo a large electric field. The agreement remains very good when increasing the temperature by 15 °C. We demonstrated that the amplification of the dark current generated for the typical electric fields encountered in the CMOS image sensors, which depends on the nature of the metal contaminant, may become very large at high electric field. The electron and hole emissions and the resulting enhancement factor are described as a function of the trap characteristics, electric field, and temperature.

  15. Metal contamination of soils and crops affected by the Chenzhou lead/zinc mine spill (Hunan, China).

    Liu, Hongyu; Probst, Anne; Liao, Bohan

    2005-03-01

    In 1985, the collapse of the tailing dam in Chenzhou lead/zinc mine (Hunan, southern China) led to the spread of mining waste spills on the farmland along the Dong River. After the accident, an urgent soil cleaning up was carried out in some places. Seventeen years later, cereal (rice, maize, and sorghum), pulses (soybean, Adzuki bean, mung bean and peanut), vegetables (ipomoea, capsicum, taro and string bean) and the rooted soils were sampled at four sites: (1) the mining area (SZY), (2) the area still covered with the mining tailing spills (GYB), (3) the cleaned area from mining tailing spills (JTC), and (4) a background site (REF). Metal concentrations in the crops and soils were analyzed to evaluate the long-term effects of the spilled waste on the soil and the potential human exposure through food chains. The results showed that the physical-chemical properties of the soils obviously changed due to the different farming styles used by each individual farmer. Leaching effects and plant extraction of metals from some soils were quite weak. Certain soils were still heavily polluted with As, Cd, Zn, Pb and Cu. The contamination levels were in the order of GYB>SZY>JTC showing that the clean-up treatment was effective. The maximum allowable concentration (MAC) levels for Chinese agricultural soils were still highly exceeded, particularly for As and Cd (followed by Zn, Pb and Cu), with mean concentrations of 709 and 7.6 mg kg(-1), respectively. These concentrations exceed the MAC levels by 24 times for As and 13 times for Cd at GYB. Generally, the edible leaves or stems of crops were more heavily contaminated than seeds or fruits. Ipomoea was the most severely contaminated crop. The concentrations of Cd and Pb were 3.30 and 76.9 mg kg(-1) in ipomoea leaves at GYB, which exceeded the maximum permit levels (0.5 mg kg(-1) for Cd and 9 mg kg(-1) for Pb) by 6.6 and 8.5 times, respectively. Taro (+skin) could accumulate high concentrations of Zn and Cd in the edible stem

  16. Evaluation of heavy metals level (arsenic, nickel, mercury and lead effecting on health in drinking water resource of Kohgiluyeh county using geographic information system (GIS

    Abdolazim Alinejad

    2016-08-01

    Full Text Available This study was conducted to determine the amount of heavy metals (Arsenic, Nickel, Mercury, and Lead in drinking water resource of Kohgiluyeh County using Geographic Information System (GIS. This cross-sectional study was conducted on drinking water resource of Kohgiluyeh County (33 water supplies and 4 heavy metals in 2013. 264 samples were analyzed in this study. The experiments were performed at the laboratory of Water and Wastewater Company based on Standard Method. The Atomic Adsorption was used to evaluate the amount of heavy metals. The results were mapping by Geographic Information System software (GIS 9.3 after processing of parameters. Finally, the data were analyzed by SPSS 16 and Excel 2007. The maximum amount of each heavy metal and its resource were shown as follow: Nickel or Ni (Source of w12, 124ppb, Arsenic or As (w33, 42 ppb, Mercury or Hg (w22 and w30, 96ppb, Lead or Pb (w21, 1553ppb. Also, the GIS maps showed that Lead in the central region was very high, Mercury and Arsenic in the northern region were high and Nickel in the eastern and western regions was high. The Kriging method and Gauss model were introduced as best method for interpolation of these metals. Since the concentration of these heavy metals was higher than standard levels in most drinking water supplies in Kohgiluyeh County and these high levels of heavy metals can cause the adverse effects on human health; therefore, the environmental and geological studies are necessary to identify the pollution resource and elimination and removal of heavy metals

  17. Health risk assessment of various metal(loid)s via multiple exposure pathways on children living near a typical lead-acid battery plant, China

    Cao, Suzhen; Duan, Xiaoli; Zhao, Xiuge; Wang, Beibei; Ma, Jin; Fan, Delong; Sun, Chengye; He, Bin; Wei, Fusheng; Jiang, Guibin

    2015-01-01

    Manufacture of lead-acid batteries is of widespread interest because of its emissions of heavy metals and metalloids into environment, harming environmental quality and consequently causing detrimental effects on human health. In this study, exposure pathways and health risks of children to heavy metal(loid)s (Pb, Cd, As, etc) were investigated based on field sampling and questionnaire. Pb was one of the most abundant elements in children's blood, with an elevated blood lead level of 12.45 μg dL −1 . Soil/dust and food were heavily polluted by targeted metal(loid)s. Food ingestion accounted for more than 80% of the total exposure for most metal(loid)s. The non-cancer risks to children were 3–10 times higher than the acceptable level of 1, while the cancer risks were 5–200 times higher than the maximum acceptable level of 1.0 × 10 −4 . The study emphasized the significance of effective environmental management, particularly to ensure food security near battery facilities. - Highlights: • The health risks of children living around a typical lead-acid battery was analyzed. • The exposure pathways of children to 12 heavy metal(loid)s were assessed. • Courtyard soil and indoor dust and duplicate food were contaminated by metal(loid)s. • Food ingestion was the major pathway for children's exposure to most metal(loid)s. • Higher potentially non-cancer and cancer risks happened to the local children. - The children living around a typical lead-acid battery plant suffered from serious health risks, which mainly attributed to food ingestion and air inhalation exposure

  18. Influence of Electrolyte Modulus on the Local Current Density at a Dendrite Tip on a Lithium Metal Electrode

    Harry, KJ; Higa, K; Srinivasan, V; Balsara, NP

    2016-08-10

    Understanding and controlling the electrochemical deposition of lithium is imperative for the safe use of rechargeable batteries with a lithium metal anode. Solid block copolymer electrolyte membranes are known to enhance the stability of lithium metal anodes by mechanically suppressing the formation of lithium protrusions during battery charging. Time-resolved hard X-ray microtomography was used to monitor the internal structure of a symmetric lithium-polymer cell during galvanostatic polarization. The microtomography images were used to determine the local rate of lithium deposition, i.e. local current density, in the vicinity of a lithium globule growing through the electrolyte. Measurements of electrolyte displacement enabled estimation of local stresses in the electrolyte. At early times, the current density was maximized at the globule tip, as expected from simple current distribution arguments. At later times, the current density was maximized at the globule perimeter. We show that this phenomenon is related to the local stress fields that arise as the electrolyte is deformed. The local current density, normalized for the radius of curvature, decreases with increasing compressive stresses at the lithium-polymer interface. To our knowledge, our study provides the first direct measurement showing the influence of local mechanical stresses on the deposition kinetics at lithium metal electrodes.

  19. Application of Streaming Effect and Joule Heating Effect of Pulse Current in Crack Healing of Metal Materials

    Jian Chu

    2017-06-01

    Full Text Available Remanufacture engineering is an emerging industry that saves resources as well as protects the environment. However, cracks on remanufactured components can result in serious trouble. Therefore, in order to avoid unnecessary waste of resources and energy, these cracks should be repaired radically in order to ensure the smooth progressing of the remanufacturing process. Consequently, the crack healing technique of metal materials is very important in the field of remanufacturing. In this study, the U-shape vane stainless steel of a centrifugal compressor which had cracks was processed by pulse current using a high pulse current discharge device, and the influence of the streaming effect and Joule heating effect of pulse current on the crack healing of metal materials was studied, aiming to provide references for the better application of this technology in the remanufacturing field in the future.

  20. Survey of heavy metal pollution (copper, lead, zinc, cadmium, iron and manganese in drinking water resources of Nurabad city, Lorestan, Iran 2013

    GHodratolah Shams Khorramabadi

    2016-09-01

    Full Text Available Background: Healthy water passes through the pipelines from supply resources to consuming places in which passing from these stages may cause some cases of contamination like heavy metal contamination. Therefore, the aim of this study was to evaluate the contamination of heavy metals (copper, lead, zinc, cadmium, iron, and manganese in water resources of Nurabad city of Lorestan in 2013. Materials and Methods: In this cross-sectional study, samples were collected from 7 wells of drinking water and 2 water storage tanks during 6 months in Nurabad. So that, heavy metal parameters such as copper, lead, zinc, cadmium, iron, and manganese were measured using an atomic absorption device and also electrical conductivity, sulfate, chloride and total dissolved solids were also measured in accordance with standard methods. Results: Results indicated that the concentration of studied metals in water sources was lower than the national standards and World Health Organization standard, and in the water supply system the concentration of some metals was more than standard level. Moreover, the results showed that the concentration of studied heavy metals were more in winter than in autumn. Conclusion: Generally, in the water resources of Nurabad city the concentration of studied heavy metals was lower than the national standards and World Health Organization standard and there are not problems for water consumers. However, due to public health and the presence of a high concentration of these metals in the distribution supply, the heavy metal concentration in drinking water of this region should be monitored regularly by responsible organizations.

  1. Influence of lead and the metallic ions of copper, zinc, thorium, beryllium and thallium on the germination of seeds. [Pepidium sativum; Sinapis alba

    Dilling, W J

    1926-01-01

    Experiments were performed to determine whether lead salts had any special retarding influence on the germination and early growth of seeds and whether any other metals (Cu, Zn, Th, Be, Tl) possessed the action in more marked degree. The experiments were done chiefly with cress (Pepidium sativum) and mustard (Sinapis alba). Results indicated that lead has a definite inhibiting action on germination and, in strengths of 0.27%, practically checks it, while exercising a deleterious effect on the growth of the seedling. With 0.12% strength, germination is delayed four days and averages 40% below the control with slow and stunted growth. 0.05% lead reduces germination by 20%, delays it by a day, but the young plants make good growth. The results indicated that other metallic ions possess, like lead, the power of inhibiting germination and growth of seeds.

  2. Is metal artefact reduction mandatory in cardiac PET/CT imaging in the presence of pacemaker and implantable cardioverter defibrillator leads?

    Ghafarian, Pardis [Shahid Beheshti University, Department of Radiation Medicine, Tehran (Iran, Islamic Republic of); Geneva University Hospital, Division of Nuclear Medicine, Geneva 4 (Switzerland); Tehran University of Medical Sciences, Research Center for Science and Technology in Medicine, Tehran (Iran, Islamic Republic of); Aghamiri, S.M.R. [Shahid Beheshti University, Department of Radiation Medicine, Tehran (Iran, Islamic Republic of); Ay, Mohammad R. [Tehran University of Medical Sciences, Research Center for Science and Technology in Medicine, Tehran (Iran, Islamic Republic of); Tehran University of Medical Sciences, Department of Medical Physics and Biomedical Engineering, Tehran (Iran, Islamic Republic of); Tehran University of Medical Sciences, Research Institute for Nuclear Medicine, Tehran (Iran, Islamic Republic of); Rahmim, Arman [Johns Hopkins University, Department of Radiology, Baltimore, MD (United States); Schindler, Thomas H. [Geneva University, Cardiovascular Center, Nuclear Cardiology, Geneva (Switzerland); Ratib, Osman [Geneva University Hospital, Division of Nuclear Medicine, Geneva 4 (Switzerland); Zaidi, Habib [Geneva University Hospital, Division of Nuclear Medicine, Geneva 4 (Switzerland); Geneva University, Geneva Neuroscience Center, Geneva (Switzerland)

    2011-02-15

    Cardiac PET/CT imaging is often performed in patients with pacemakers and implantable cardioverter defibrillator (ICD) leads. However, metallic implants usually produce artefacts on CT images which might propagate to CT-based attenuation-corrected (CTAC) PET images. The impact of metal artefact reduction (MAR) for CTAC of cardiac PET/CT images in the presence of pacemaker, ICD and ECG leads was investigated using both qualitative and quantitative analysis in phantom and clinical studies. The study included 14 patients with various leads undergoing perfusion and viability examinations using dedicated cardiac PET/CT protocols. The PET data were corrected for attenuation using both artefactual CT images and CT images corrected using the MAR algorithm. The severity and magnitude of metallic artefacts arising from these leads were assessed on both linear attenuation coefficient maps ({mu}-maps) and attenuation-corrected PET images. CT and PET emission data were obtained using an anthropomorphic thorax phantom and a dedicated heart phantom made in-house incorporating pacemaker and ICD leads attached at the right ventricle of the heart. Volume of interest-based analysis and regression plots were performed for regions related to the lead locations. Bull's eye view analysis was also performed on PET images corrected for attenuation with and without the MAR algorithm. In clinical studies, the visual assessment of PET images by experienced physicians and quantitative analysis did not reveal erroneous interpretation of the tracer distribution or significant differences when PET images were corrected for attenuation with and without MAR. In phantom studies, the mean differences between tracer uptake obtained without and with MAR were 10.16{+-}2.1% and 6.86{+-}2.1% in the segments of the heart in the vicinity of metallic ICD or pacemaker leads, and were 4.43{+-}0.5% and 2.98{+-}0.5% in segments far from the leads. Although the MAR algorithm was able to effectively improve

  3. Correlation between heavy metal ions (copper, zinc, lead concentrations and root length of Allium cepa L. in polluted river water

    Soraya Moreno Palacio

    2005-06-01

    Full Text Available The present work was performed using the common onion (Allium cepa L. as a bioindicator of toxicity of heavy metals in river water. The test waters were collected at two sampling sites: at the beginning and the end of the Toledo River. The bulbs of A. cepa L. were grown in test water with nine concentration levels of copper, zinc and lead from 0.1 to 50 ppm. In the laboratory, the influence of these test liquids on the root growth was examined during five days. For test liquids containing below 0.03-ppm dissolved Cu the root growth was reduced by 40% However, the same reduction occurred for 1-ppm dissolved Zn. For dissolved Pb, results reveal toxicity above 0.1 and 0.6 ppm at the beginning and the end of the Toledo river water, respectively.O presente trabalho foi realizado utilizando a cebola comum (Allium cepa L. como bioindicador da toxicidade de metais pesados em água de rio. As águas de teste foram coletadas em dois locais: na nascente e na foz do rio Toledo. Os bulbos de A. cepa L. foram cultivados em água de teste com nove níveis de concentração de cobre, zinco e chumbo de 0,1 a 50 ppm. Em laboratório a influência destes líquidos de teste em crescimento de raiz foi examinada durante cinco dias. Em todos os líquidos de teste o metal dissolvido contido foi medido pela técnica TXRF. Para líquidos de teste contendo 0,1-ppm de Cu dissolvido o crescimento da raiz foi reduzido em 50%. Entretanto, ocorreu a mesma redução para 1-ppm de Zn dissolvido. Para Pb dissolvido, o método do Allium teste revela toxidade acima de 0,1 e 0,5 ppm para a nascente e a foz do rio Toledo, respectivamente.

  4. Heavy metals in Iberian soils: Removal by current adsorbents/amendments and prospective for aerogels.

    Vareda, João P; Valente, Artur J M; Durães, Luisa

    2016-11-01

    Heavy metals are dangerous pollutants that in spite of occurring naturally are released in major amounts to the environment due to anthropogenic activities. After being released in the environment, the heavy metals end up in the soils where they accumulate as they do not degrade, adversely affecting the biota. Because of the dynamic equilibria between soil constituents, the heavy metals may be present in different phases such as the solid phase (immobilized contaminants) or dissolved in soil solution. The latter form is the most dangerous because the ions are mobile, can leach and be absorbed by living organisms. Different methods for the decontamination of polluted soils have been proposed and they make use of two different approaches: mobilizing the heavy metals, which allows their removal from soil, or immobilization that maintains the metal concentrations in soils but keeps them in an inert form due to mechanisms like precipitation, complexation or adsorption. Mobilization of the heavy metals is known to cause leaching and increase plant uptake, so this treatment can cause greater problems. Aerogels are incredible nanostructured, lightweight materials with high surface area and tailorable surface chemistry. Their application in environmental cleaning has been increasing in recent years and very promising results have been obtained. The functionalization of the aerogels can give them the ability to interact with heavy metals, retaining the latter via strong adsorptive interactions. Thus, this review surveys the existing literature for remediation of soils using an immobilization approach, i.e. with soil amendments that increase the soil sorption/retention capacity for heavy metals. The considered framework was a set of heavy metals with relevance in polluted Iberian soils, namely Cd, Cr, Cu, Ni, Pb and Zn. Moreover, other adsorbents, especially aerogels, have been used for the removal of these contaminants from aqueous media; because groundwater and soil

  5. Conceptual design of a 20-kA current lead using forced-flow cooling and Ag-alloy-sheathed Bi-2223 high-temperature superconductors

    Heller, R.; Hull, J.R.

    1994-01-01

    High-temperature superconductors (HTSs), consisting of Bi-2223 HTS tapes sheathed with Ag alloys are proposed for a 20-kA current lead for the planned stellarator WENDELSTEIN 7-X. Forced-flow He cooling is used, and 4-K He cooling of the whole lead as well as 60-K He cooling of the copper part of the lead, is discussed. Power consumption and behavior in case of loss of He flow are given

  6. Liquid helium boil-off measurements of heat leakage from sinter-forged BSCCO current leads under DC and AC conditions

    Cha, Y.S.; Niemann, R.C.; Hull, J.R.; Youngdahl, C.A.; Lanagan, M.T.; Nakade, M.; Hara, T.

    1995-06-01

    Liquid helium boil-off experiments are conducted to determine the heat leakage rate of a pair of BSCCO 2223 high-temperature superconductor current leads made by sinter forging. The experiments are carried out in both DC and AC conditions and with and without an intermediate heat intercept. Current ranges are from 0-500 A for DC tests and 0-1,000 A rms for AC tests. The leads are self-cooled. Results show that magnetic hysteresis (AC) losses for both the BSCCO leads and the low-temperature superconductor current jumper are small for the current range. It is shown that significant reduction in heat leakage rate (liquid helium boil-off rate) is realized by using the BSCCO superconductor leads. At 100 A, the heat leakage rate of the BSCCO/copper binary lead is approximately 29% of that of the conventional copper lead. Further reduction in liquid helium boil-off rate can be achieved by using an intermediate heat intercept. For example, at 500 K, the heat leakage rate of the BSCCO/copper binary lead is only 7% of that of the conventional copper lead when an intermediate heat intercept is used

  7. Parity-Forbidden Transitions and Their Impact on the Optical Absorption Properties of Lead-Free Metal Halide Perovskites and Double Perovskites.

    Meng, Weiwei; Wang, Xiaoming; Xiao, Zewen; Wang, Jianbo; Mitzi, David B; Yan, Yanfa

    2017-07-06

    Using density functional theory calculations, we analyze the optical absorption properties of lead (Pb)-free metal halide perovskites (AB 2+ X 3 ) and double perovskites (A 2 B + B 3+ X 6 ) (A = Cs or monovalent organic ion, B 2+ = non-Pb divalent metal, B + = monovalent metal, B 3+ = trivalent metal, X = halogen). We show that if B 2+ is not Sn or Ge, Pb-free metal halide perovskites exhibit poor optical absorptions because of their indirect band gap nature. Among the nine possible types of Pb-free metal halide double perovskites, six have direct band gaps. Of these six types, four show inversion symmetry-induced parity-forbidden or weak transitions between band edges, making them not ideal for thin-film solar cell applications. Only one type of Pb-free double perovskite shows optical absorption and electronic properties suitable for solar cell applications, namely, those with B + = In, Tl and B 3+ = Sb, Bi. Our results provide important insights for designing new metal halide perovskites and double perovskites for optoelectronic applications.

  8. Current role of ICP-MS in clinical toxicology and forensic toxicology: a metallic profile.

    Goullé, Jean-Pierre; Saussereau, Elodie; Mahieu, Loïc; Guerbet, Michel

    2014-08-01

    As metal/metalloid exposure is inevitable owing to its omnipresence, it may exert toxicity in humans. Recent advances in metal/metalloid analysis have been made moving from flame atomic absorption spectrometry and electrothermal atomic absorption spectrometry to the multi-elemental inductively coupled plasma (ICP) techniques as ICP atomic emission spectrometry and ICP-MS. ICP-MS has now emerged as a major technique in inorganic analytical chemistry owing to its flexibility, high sensitivity and good reproducibility. This in depth review explores the ICP-MS metallic profile in human toxicology. It is now routinely used and of great importance, in clinical toxicology and forensic toxicology to explore biological matrices, specifically whole blood, plasma, urine, hair, nail, biopsy samples and tissues.

  9. Current Status of Health and Safety Issues of Sodium/Metal Chloride (Zebra) Batteries

    David Trickett

    1998-01-01

    This report addresses environmental, health, and safety (EH ampersand S) issues associated with sodium/ metal chloride batteries, in general, although most references to specific cell or battery types refer to units developed or being developed under the Zebra trademark. The report focuses on issues pertinent to sodium/metal chloride batteries and their constituent components; however, the fact that some ''issues'' arise from interaction between electric vehicle (EV) and battery design com- pels occasional discussion amid the context of EV vehicle design and operation. This approach has been chosen to provide a reasonably comprehensive account of the topic from a cell technology perspective and an applications perspective

  10. Current Status of Health and Safety Issues of Sodium/Metal Chloride (Zebra) Batteries

    Trickett, D.

    1998-12-15

    This report addresses environmental, health, and safety (EH&S) issues associated with sodium/ metal chloride batteries, in general, although most references to specific cell or battery types refer to units developed or being developed under the Zebra trademark. The report focuses on issues pertinent to sodium/metal chloride batteries and their constituent components; however, the fact that some ''issues'' arise from interaction between electric vehicle (EV) and battery design compels occasional discussion amid the context of EV vehicle design and operation. This approach has been chosen to provide a reasonably comprehensive account of the topic from a cell technology perspective and an applications perspective.

  11. Monitoring of heavy metals in selected Water Supply Systems in Poland, in relation to current regulations

    Szuster-Janiaczyk, Agnieszka; Zeuschner, Piotr; Noga, Paweł; Skrzypczak, Marta

    2018-02-01

    The study presents an analysis of water quality monitoring in terms of the content of heavy metals, which is conducted in three independent water supply systems in Poland. The analysis showed that the monitoring of heavy metals isn't reliable - both the quantity of tested water samples and the location of the monitoring points are the problem. The analysis of changes in water quality from raw water to tap water was possible only for one of the analysed systems and indicate a gradual deterioration of water quality, although still within acceptable limits of legal regulations.

  12. Comparison of lithium and the eutectic lead lithium alloy, two candidate liquid metal breeder materials for self-cooled blankets

    Malang, S.; Mattas, R.

    1994-06-01

    Liquid metals are attractive candidates for both near-term and long-term fusion applications. The subjects of this comparison are the differences between the two candidate liquid metal breeder materials Li and LiPb for use in breeding blankets in the areas of neutronics, magnetohydrodynamics, tritium control, compatibility with structural materials, heat extraction system, safety, and required R ampersand D program. Both candidates appear to be promising for use in self-cooled breeding blankets which have inherent simplicity with the liquid metal serving as both breeders and coolant. The remaining feasibility question for both breeder materials is the electrical insulation between liquid metal and duct walls. Different ceramic coatings are required for the two breeders, and their crucial issues, namely self-healing of insulator cracks and radiation induced electrical degradation are not yet demonstrated. Each liquid metal breeder has advantages and concerns associated with it, and further development is needed to resolve these concerns

  13. Experimental Study of Liquidus of the "FeO"-SiO2-PbO Slags in Equilibrium with Air and with Metallic Lead

    Shevchenko, Maksym; Hidayat, Taufiq; Hayes, Peter C.; Jak, Evgueni

    Limited data are available on phase equilibria of the "FeO"-SiO2-PbO slag system at conditions used in the lead smelting due to difficulties from lead vaporization and interactions with metal and ceramic crucibles. Recently experimental procedures have been developed and successfully applied to complex industrial slag-metal-matte systems involving high temperature equilibration on a primary phase substrate and rapid quenching followed by the electron probe X-ray microanalysis. The liquidus isotherms and invariant lines in the "FeO"-SiO2-PbO slag system in equilibrium with air and with metallic lead have been constructed. Preliminary data compared to the FactSage package predictions demonstrate differences in some aspects, indicating the possibility for further improvement of the thermodynamic database. The present work is a part of the integrated experimental and thermodynamic modelling research program on multi-phase lead systems in support of the optimization and development of complex lead smelting, refining and recycling technologies.

  14. Anomalous temperature dependence of the current in a metal-oxide-polymer resistive switching diode

    Gomes, H.L.; Rocha, P.R.F.; Kiazadeh, A.; Leeuw, de D.M.; Meskers, S.C.J.

    2011-01-01

    Metal-oxide polymer diodes exhibit non-volatile resistive switching. The current–voltage characteristics have been studied as a function of temperature. The low-conductance state follows a thermally activated behaviour. The high-conductance state shows a multistep-like behaviour and below 300 K an

  15. Current-Fluctuation Mechanism of Field Emitters Using Metallic Single-Walled Carbon Nanotubes with High Crystallinity

    Norihiro Shimoi

    2017-12-01

    Full Text Available Field emitters can be used as a cathode electrode in a cathodoluminescence device, and single-walled carbon nanotubes (SWCNTs that are synthesized by arc discharge are expected to exhibit good field emission (FE properties. However, a cathodoluminescence device that uses field emitters radiates rays whose intensity considerably fluctuates at a low frequency, and the radiant fluctuation is caused by FE current fluctuation. To solve this problem, is very important to obtain a stable output for field emitters in a cathodoluminescence device. The authors consider that the electron-emission fluctuation is caused by Fowler–Nordheim electron tunneling and that the electrons in the Fowler–Nordheim regime pass through an inelastic potential barrier. We attempted to develop a theoretical model to analyze the power spectrum of the FE current fluctuation using metallic SWCNTs as field emitters, owing to their electrical conductivity by determining their FE properties. Field emitters that use metallic SWCNTs with high crystallinity were successfully developed to achieve a fluctuating FE current from field emitters at a low frequency by employing inelastic electron tunneling. This paper is the first report of the successful development of an inelastic-electron-tunneling model with a Wentzel–Kramers–Brillouin approximation for metallic SWCNTs based on the evaluation of FE properties.

  16. Annual trace-metal load estimates and flow-weighted concentrations of cadmium, lead, and zinc in the Spokane River basin, Idaho and Washington, 1999-2004

    Donato, Mary M.

    2006-01-01

    Streamflow and trace-metal concentration data collected at 10 locations in the Spokane River basin of northern Idaho and eastern Washington during 1999-2004 were used as input for the U.S. Geological Survey software, LOADEST, to estimate annual loads and mean flow-weighted concentrations of total and dissolved cadmium, lead, and zinc. Cadmium composed less than 1 percent of the total metal load at all stations; lead constituted from 6 to 42 percent of the total load at stations upstream from Coeur d'Alene Lake and from 2 to 4 percent at stations downstream of the lake. Zinc composed more than 90 percent of the total metal load at 6 of the 10 stations examined in this study. Trace-metal loads were lowest at the station on Pine Creek below Amy Gulch, where the mean annual total cadmium load for 1999-2004 was 39 kilograms per year (kg/yr), the mean estimated total lead load was about 1,700 kg/yr, and the mean annual total zinc load was 14,000 kg/yr. The trace-metal loads at stations on North Fork Coeur d'Alene River at Enaville, Ninemile Creek, and Canyon Creek also were relatively low. Trace-metal loads were highest at the station at Coeur d'Alene River near Harrison. The mean annual total cadmium load was 3,400 kg/yr, the mean total lead load was 240,000 kg/yr, and the mean total zinc load was 510,000 kg/yr for 1999-2004. Trace-metal loads at the station at South Fork Coeur d'Alene River near Pinehurst and the three stations on the Spokane River downstream of Coeur d'Alene Lake also were relatively high. Differences in metal loads, particularly lead, between stations upstream and downstream of Coeur d'Alene Lake likely are due to trapping and retention of metals in lakebed sediments. LOADEST software was used to estimate loads for water years 1999-2001 for many of the same sites discussed in this report. Overall, results from this study and those from a previous study are in good agreement. Observed differences between the two studies are attributable to streamflow

  17. The role of current characteristics of the arc evaporator in formation of the surface metal-coating composite

    Plikhunov, V V; Petrov, L M; Grigorovich, K V

    2016-01-01

    The influence of current characteristics of the vacuum arc evaporator on the interaction process of plasma streams with the surface under treatment during generation of the physicochemical properties of the formed metal-coating composite is considered. It is shown that the interaction of plasma streams with the processed surface provides surface heating, defects elimination, change in energy properties, and mass transfer of plasma stream elements activating surface diffusion processes whose intensity is evaluated by the arc current magnitude and location of the processed surface relative to the cathode axis. (paper)

  18. Current state of knowledge of the concentration of mercury and other heavy metals in fresh water fish in Colombia

    Mancera Rodriguez, Nestor Javier; Alvarez Leon, Ricardo

    2006-01-01

    One of the most important environmental problems in the country refers to the indiscriminate use of chemical precursors in illicit activities, the use of heavy metals as mercury in mining activities, the spill of served waters and another type of compound related with the industrial activities of raw and the inadequate agricultural practices. This has led to chemical contamination especially by heavy metals, considered one of the most dangerous for the aquatic ecosystems and the present species in them. Fish have the capacity to store these compounds in their organism in a concentration higher than that in the surrounding environment (water), therefore, their concentration are important indicators of the contamination level, but also this implies that their consumption can become a serious health problem for the populations that feeds from them. The concentration of heavy metals in fish of fresh water is better known in the basin of the Magdalena river, especially in the region of the Mojana and in the marshes of the south of the department of Bolivar where the levels of contamination by mercury and other metals has been studied due to the development of multiple industrial activities, including gold mining and petrochemical industries. However, little is known in the country about the problem generated by the disposal heavy metals in rivers and lakes and their impact on the fish resource, deterioration of ecosystems and human health. Based in the current norms bio-assays have been used to check the effects of the aquatic contamination on fresh waters fish and the evaluation of at least three parameters (heavy metals, temperature, effluents) in eight species of fresh waters fish: carassius auratus, oreochromis spp., piractus brachypomus, prochilodus magdalenae, astyanax fasciatus, colossoma bidens, gambusia affinis and grundulus bogotensis

  19. Current State of Knowledge of the Concentration of Mercury and Other Heavy Metals in Fresh Water Fish in Colombia

    Néstor Javier Mancera-Rodríguez

    2006-01-01

    Full Text Available One of the most important environmental problems in the country refers to the indiscriminate use of chemical precursors in illicit activities, the use of heavy metals as mercury in mining activities, the spill of served waters and another type of compound related with the industrial activities of raw and the inadequate agricultural practices. This has led to chemical contamination especially by heavy metals, considered one of the most dangerous for the aquatic ecosystems and the present species in them. Fish have the capacity to store these compounds in their organism in a concentration higher important indicators of the contamination level, but also this implies that their consumption can become a serious health problem for the populations that feeds from them. The concentration of heavy metals in fish of fresh water is better known in the basin of the Magdalena river, especially in the region of the Mojana and in the marshes of the south of the Department of Bolivar where the levels of contamination by mercury and other metals has been studied due to the development of multiple industrial activities, including gold mining and petrochemical industries. However, little is known in the country about the problem generated by the disposal heavy metals in rivers and lakes and their impact on the fish resource, deterioration of ecosystems and human health. Based in the current norms bio-assays have been used to check the effects of the aquatic contamination on fresh waters fish and the evaluation of at least three parameters (heavy metals, temperature, effluents in eight species of fresh waters fish: Carassius auratus, Oreochromis spp., Piractus brachypomus, Prochilodus magdalenae, Astyanax fasciatus, Colossoma bidens, Gambusia affinis and Grundulus bogotensis.

  20. Nanoscale leakage current measurements in metal organic chemical vapor deposition crystalline SrTiO3 films

    Rozier, Y.; Gautier, B.; Hyvert, G.; Descamps, A.; Plossu, C.; Dubourdieu, C.; Ducroquet, F.

    2009-01-01

    The properties of SrTiO 3 thin films, grown by liquid injection metal organic chemical vapor deposition on Si/SiO 2 , using a mixture of precursors, have been investigated at the nanoscale using an Atomic Force Microscope in the so-called Conductive Atomic Force Microscopy mode. Maps of the leakage currents with a nanometric resolution have been obtained on films elaborated at different temperatures and stoichiometries in order to discriminate the role of each parameter on the onset of leakage currents in the resulting layers. It appears that the higher the deposition temperature, the higher the leakage currents of the films. The mapping with a nanometric precision allows to show a heterogeneous behaviour of the surface with leaky grains and insulating boundaries. The study of films elaborated at the same temperature with different compositions supports the assumption that the leakage currents on Ti-rich layers are far higher than on Sr-rich layers

  1. Experimental study of the features of the running part liquid metal target on lead-bismuth alloy

    Beznosov, A.V.; Meluzov, A.G.; Novozhilova, O.O.; Efanov, A.D.

    2007-01-01

    The results of experimental investigations of the through part of a full-scale liquid metal target of an accelerator-control system, where the working cavity of the target communicates directly with the particle accelerator cavity, are presented. Two design variants were investigated - with vertical and horizontal orientation of the target axis in space and spinning of the flow in front of the nozzle adapter located in front of the entrance of the eutectic into the working cavity of the target. The profiles obtained for the free coolant surface with liquid metal flowing through vertically and horizontally positioned targets are presented. It is confirmed that when the pressure of the free surface of the liquid metal corresponds to the pressure in the accelerator cavity it is possible that liquid metal will not flow into the cavity simulating the connecting piece for inflow of accelerated particles with the piece oriented vertically or horizontally [ru

  2. Provenance Studies on Metal Artefacts of the Early Danish Bronze Age: Comparing lead isotope data with the archaeological evidence

    Nørgaard, Heide Wrobel; Vandkilde, Helle; Pernicka, Ernst

    2017-01-01

    As early as 2100 BCE, societies in the hotspot zone of Denmark and Scania began to use metal. However, this region has not exploited metal ores of their own; therefore the origin of the metal used is of key significance to understanding and modelling the cross-European interconnectivities that were...... established through the necessity of trading. The Nordic region was for the very first time fully dependent on one crucial exogenous resource. The related change within the political economy surely resulted in the establishment of the Nordic Bronze Age. However, little is known about the significance......, the extent and the direction of this metal trade. For the Bronze Age in northern Europe (NBA) two possible transport routes stand opposite each other; on the one hand a continental route that connected the Alps, Central Europe and the NBA; and on the other hand, a maritime route linking Mediterranean...

  3. Heavy metal pollution and ecological risk assessment of the paddy soils near a zinc-lead mining area in Hunan.

    Lu, Sijin; Wang, Yeyao; Teng, Yanguo; Yu, Xuan

    2015-10-01

    Soil pollution by Cd, Hg, As, Pb, Cr, Cu, and Zn was characterized in the area of the mining and smelting of metal ores at Guiyang, northeast of Hunan Province. A total of 150 topsoil (0-20 cm) samples were collected in May 2012 with a nominal density of one sample per 4 km(2). High concentrations of heavy metals especially, Cd, Zn, and Pb were found in many of the samples taken from surrounding paddy soil, indicating a certain extent of spreading of heavy metal pollution. Sequential extraction technique and risk assessment code (RAC) were used to study the mobility of chemical forms of heavy metals in the soils and their ecological risk. The results reveal that Cd represents a high ecological risk due to its highest percentage of the exchangeable and carbonate fractions. The metals of Zn and Cu pose a medium risk, and the rest of the metals represent a low environmental risk. The range of the potential ecological risk of soil calculated by risk index (RI) was 123.5~2791.2 and revealed a considerable-high ecological risk in study area especially in the neighboring and surrounding the mining activities area. Additionally, cluster analyses suggested that metals such as Pb, As, Hg, Zn, and Cd could be from the same sources probably related to the acidic drainage and wind transport of dust. Cluster analysis also clearly distinguishes the samples with similar characteristics according to their spatial distribution. The results could be used during the ecological risk screening stage, in conjunction with total concentrations and metal fractionation values to better estimate ecological risk.

  4. Calculation of induced current densities and specific absorption rates (SAR) for pregnant women exposed to hand-held metal detectors

    Kainz, Wolfgang; Chan, Dulciana D; Casamento, Jon P; Bassen, Howard I

    2003-01-01

    The finite difference time domain (FDTD) method in combination with a well established frequency scaling method was used to calculate the internal fields and current densities induced in a simple model of a pregnant woman and her foetus, when exposed to hand-held metal detectors. The pregnant woman and foetus were modelled using a simple semi-heterogeneous model in 10 mm resolution, consisting of three different types of tissue. The model is based on the scanned shape of a pregnant woman in the 34th gestational week. Nine different representative models of hand-held metal detectors operating in the frequency range from 8 kHz to 2 MHz were evaluated. The metal detectors were placed directly on the abdomen of the computational model with a spacing of 1 cm. Both the induced current density and the specific absorption rate (SAR) are well below the recommended limits for exposure of the general public published in the ICNIRP Guidelines and the IEEE C95.1 Standard. The highest current density is 8.3 mA m -2 and the highest SAR is 26.5 μW kg -1 . Compared to the limits for the induced current density recommended in the ICNIRP Guidelines, a minimum safety factor of 3 exists. Compared to the IEEE C95.1 Standard, a safety factor of 60,000 for the specific absorption rate was found. Based on the very low specific absorption rate and an induced current density below the recommended exposure limits, significant temperature rise or nerve stimulation in the pregnant woman or in the foetus can be excluded

  5. The Environmentally Sound Aquaculture Strategies Based on Bioaccumulation of Heavy Metal of Lead (Pb) on Seaweed of Gracilaria verrucosa on Aquaculture Areas of MuararejaVillage, Tegal City

    Nurjanah; Ambariyanto; Supriharyono; Yulianto, Bambang

    2018-02-01

    Community activities such as industry, trade, animal husbandry and agriculture and ssettlements resulting in heavy metals of lead (Pb) can be accumulated in water, sediment and seaweed Gracillaria verrucosa. It can contaminate ponds and affect aquaculture activities in Tegal. Seaweed Gracilaria verrucosa is afisheries commodity that has economical value and cultivated in the area of aquaculture MuararejaTegal. It can serve as fitoremedian that will help reduce the impact of heavy metal pollution due to its ability to accumulate pollutants. The objective of this study was to analyze bioaccumulation of heavy metals of lead (Pb) and its relationship with water quality management in order to develop seaweed cultivation of Gracillaria verrucosa in ponds in the area of aquaculture MuararejaTegal. The method used in this study is a survey, analysis of heavy metals of lead (Pb) in pond water, sediment and seaweed using Atomic Absorption Spectrophotometer (AAS) and the data were analyzed by descriptive quantitative. Bioconcentration of lead (Pb) during the dry season in pond water, sediment and seaweed Gracillaria verrucosa was measured from 0.003 to 0.025 ppm,5.543 to 23.699 ppm and 0.209 to 0.326 ppm respectively. While in the rainy season bioconcentration of lead (Pb) are from 0.003 to 0.015 ppm, sediment from 6.377 to 9.858 ppm and 0.209 to 0.326 ppm respectively. Bioconcentration of Pb in dry season was higher than in the rainy season and the biggest bioconcentration was found in the sediment pond waters. Pb bioaccumulation low and still below the quality standards of the Ministry of Environment decision 51 of 2004 so that the product is safe for consumption.

  6. The analysis on the current status of the overseas recycle technology of the metallic radioactive wastes

    Shin, Jae In; Kim, Hee Reyoung; Jung, Kee Jung

    2002-05-01

    It was understood that regulation criteria for material release varied with countries and that international standards were not setup. But, most advanced countries are continuously studying on the recycling of metallic wastes for the purpose of the reuse of resources and disposal cost reduction. Practically, the advanced countries make a lot of cost profits compared with disposal as their metallic wastes are recycled and reused through technology like melting. The reasonable international standards are also expected to be set in the near future because of the aggressive cooperation between international agencies such as IAEA and NEA toward recycling these wastes. In our case, the recycle criteria for radioactive waste containing radioactive nuclide with long half-life such as Cs-137(half-life: 30y) and Co-60(half-life: 5.26y) including others, which are generated from the nuclear fission or dismantling of nuclear facilities, are not yet established. Therefore, it is required that the recommendation and legalization of the regulatory criteria be carried out for the recycle and reuse of metallic wastes to be generated from the dismantling of domestic nuclear facilities in the future

  7. Multiscale models of metal behaviour and structural change under the action of high-current electron irradiation

    Mayer, A E; Krasnikov, V S; Mayer, P N; Pogorelko, V V

    2017-01-01

    We present our models of the tensile fracture of metals in the solid and molten states, the melting and the plastic deformation of the solid metals. Also we discuss implementation of these models for simulation of the high current electron beam impact on metals. The models are constructed in the following way: the atomistic simulations are used at the first stage for investigation of dynamics and kinetics of structural defects in material (voids, dislocations, melting cites); equations describing evolution of such defects are constructed, verified, and their parameters are identified by means of comparison with the atomistic simulation result; finally, the defects evolution equations are incorporated into the continuum model of the substance behaviour on the macroscopic scale. The obtained continuum models with accounting of defects subsystems are tested in comparison with the experimental results known from literature. The proposed models not only allow one to describe the metal behaviour under the conditions of intensive electron irradiation, but they also allow one to determine the structural changes in the irradiated material. (paper)

  8. Novel Method for Sizing Metallic Bottom Crack Depth Using Multi-frequency Alternating Current Potential Drop Technique

    Li Yuting

    2015-10-01

    Full Text Available Potential drop techniques are of two types: the direct current potential drop (DCPD technique and alternating current potential drop (ACPD technique, and both of them are used in nondestructive testing. ACPD, as a kind of valid method in sizing metal cracks, has been applied to evaluate metal structures. However, our review of most available approaches revealed that some improvements can be done in measuring depth of metal bottom crack by means of ACPD, such as accuracy and sensitivity of shallow crack. This paper studied a novel method which utilized the slope of voltage ratio-frequency curve to solve bottom crack depth by using a simple mathematic equation based on finite element analysis. It is found that voltage ratio varies linearly with frequency in the range of 5-15 Hz; this range is slightly higher than the equivalent frequency and lower than semi-permeable frequency. Simulation and experiment show that the novel method can measure the bottom crack depth accurately.

  9. Magnetization switching of a metallic nanomagnet via current-induced surface spin-polarization of an underlying topological insulator

    Roy, Urmimala; Dey, Rik; Pramanik, Tanmoy; Ghosh, Bahniman; Register, Leonard F.; Banerjee, Sanjay K.

    2015-01-01

    We consider a thermally stable, metallic nanoscale ferromagnet (FM) subject to spin-polarized current injection and exchange coupling from the spin-helically locked surface states of a topological insulator (TI) to evaluate possible non-volatile memory applications. We consider parallel transport in the TI and the metallic FM, and focus on the efficiency of magnetization switching as a function of transport between the TI and the FM. Transport is modeled as diffusive in the TI beneath the FM, consistent with the mobility in the TI at room temperature, and in the FM, which essentially serves as a constant potential region albeit spin-dependent except in the low conductivity, diffusive limit. Thus, it can be captured by drift-diffusion simulation, which allows for ready interpretation of the results. We calculate switching time and energy consumed per write operation using self-consistent transport, spin-transfer-torque (STT), and magnetization dynamics calculations. Calculated switching energies and times compare favorably to conventional spin-torque memory schemes for substantial interlayer conductivity. Nevertheless, we find that shunting of current from the TI to a metallic nanomagnet can substantially limit efficiency. Exacerbating the problem, STT from the TI effectively increases the TI resistivity. We show that for optimum performance, the sheet resistivity of the FM layer should be comparable to or larger than that of the TI surface layer. Thus, the effective conductivity of the FM layer becomes a critical design consideration for TI-based non-volatile memory

  10. Current-induced metal-insulator transition in VO x thin film prepared by rapid-thermal-annealing

    Cho, Choong-Rae; Cho, SungIl; Vadim, Sidorkin; Jung, Ranju; Yoo, Inkyeong

    2006-01-01

    The phenomenon of metal-insulator transition (MIT) in polycrystalline VO x thin films and their preparations have been studied. The films were prepared by sputtering of vanadium thin films succeeded by Rapid Thermal Annealing (RTA) in oxygen ambient at 500 deg. C. Crystalline, compositional, and morphological characterizations reveal a continuous change of phase from vanadium metal to the highest oxide phase, V 2 O 5 , with the time of annealing. Electrical MIT switching has been observed in these films. Sweeping mode, electrode area, and temperature dependent MIT has been studied in Pt/VO x /Pt vertical structure. The important parameters for MIT in VO x have been found to be the current density and the electric field, which depend on carrier density in the films

  11. Angular detector of defects in a metallic tube by eddy currents

    Broudeur, R.

    1990-01-01

    The angular detector of defects in a metallic tube has two centering pieces for the clad positioning on both sides of a backing ring of the measuring coil. The inner diameter of the backing ring and the diameter of the centering pieces are in the ratio 4/3±0.6/3 and their axis are eccentric. This setting over associated at the guiding piece of the sheath in rotation gives at the measuring coil a functioning as a ponctual probe [fr

  12. A comparative study on the property determination of metal matrix composites using ultrasonic and eddy current techniques

    Jeong, Hyun Jo

    1997-01-01

    Ultrasonic and eddy current methods were developed for the quantitative determination of material properties in particulate reinforced metal matrix composites. The proposed techniques employed measurements of ultrasonic velocity and eddy current conductivity, together with theoretical models which relate the effective anisotropic properties of the composites to their microstructures. The approach was used for a wide range of SiC particulate reinforced Al matrix(SiC p /Al) composites to estimate the particulate volume fractions of the composites. The SiC p volume fraction was calculated by coupling the measured velocity and conductivity with their corresponding model predictions. Both methods were shown to be reliable in determining the reinforcement volume fractions. However, the ultrasonic method was found to be better than the eddy current method, since the electrical conductivity was sensitive to the presence of intermetallic compounds formed during processing stage.

  13. Catalytic polarographic currents of platinum metal complexes and their application to determination of trace concentrations of the elements

    Ezerskaya, N.A.; Kiseleva, I.N.

    1984-01-01

    Several types of catalytic electrode processes with the participation of platinum metal complexes and used for the determination of the element microconcentrations have been considered in the review. It is pointed out that to measure catalytic currents of hydrogen solutions nitroso compounds, which are prepared by heating chloride complexes of Ru(3) and (4) with NaNO 2 are used. The method is applicable for ruthenium determination in commercial nitric acid solutions. Ru determination in solution of ruthenium (4) dimeric chloride complex on graphite electrode, using catalytic currents of hydrogen, surpasses in sensitivity the determination of the element, using the method of inversion voltammetry. Certain other complexes of Ru and determination methods of ruthenium in them are considered. Hydrogen catalytic currents in the complexes solutions with organic ligands are the most perspective for analysis

  14. Non-destructive testing (NDT) of metal cracks using a high Tc rf-SQUID and eddy current method

    Lu, D.F.; Fan, C.; Ruan, J.Z. [Midwest Superconductivity Inc., Lawrence, KS (United States)] [and others

    1994-12-31

    A SQUID is the most sensitive device to detect change in magnetic field. A non-destructive testing (NDT) device using high temperature SQUIDs and eddy current method will be much more sensitive than those currently used eddy current systems, yet much cheaper than one with low temperature SQUIDs. In this paper, we present our study of such a NDT device using a high temperature superconducting rf-SQUID as a gradiometer sensor. The result clearly demonstrates the expected sensitivity of the system, and indicates the feasibility of building a portable HTS SQUID NDT device with the help from cryocooler industry. Such a NDT device will have a significant impact on metal corrosion or crack detection technology.

  15. Non-destructive testing (NDT) of metal cracks using a high Tc rf-SQUID and eddy current method

    Lu, D.F.; Fan, C.; Ruan, J.Z.

    1994-01-01

    A SQUID is the most sensitive device to detect change in magnetic field. A non-destructive testing (NDT) device using high temperature SQUIDs and eddy current method will be much more sensitive than those currently used eddy current systems, yet much cheaper than one with low temperature SQUIDs. In this paper, we present our study of such a NDT device using a high temperature superconducting rf-SQUID as a gradiometer sensor. The result clearly demonstrates the expected sensitivity of the system, and indicates the feasibility of building a portable HTS SQUID NDT device with the help from cryocooler industry. Such a NDT device will have a significant impact on metal corrosion or crack detection technology

  16. Features of the low-power charge controller of lead-acid current sources charged by solar batteries

    Tukfatullin, O.F.; Yuldoshev, I.A.; Solieva, N.A.

    2008-01-01

    Influence of different factors on exploitations characteristics of solar photoelectric plant is investigated by field-performance data. A construction of charge controller of the lead-acid accumulator battery charging by means of solar battery is analyzed taking into account these factors. (authors)

  17. Early response to sibutramine in patients not meeting current label criteria: preliminary analysis of SCOUT lead-in period

    Caterson, Ian; Coutinho, Walmir; Finer, Nick

    2010-01-01

    pulse rate increases; median 1.5 bpm (nonconformers) vs. 3.0 bpm (conformers). There was a low incidence of serious adverse events (conformers: 1.0%; nonconformers: 2.8%) and ~93% of patients in both groups completed the 6-week period. The SCOUT lead-in period evaluating weight management...

  18. Ecotoxicology: Lead

    Scheuhammer, A.M.; Beyer, W.N.; Schmitt, C.J.; Jorgensen, Sven Erik; Fath, Brian D.

    2008-01-01

    Lead (Pb) is a naturally occurring metallic element; trace concentrations are found in all environmental media and in all living things. However, certain human activities, especially base metal mining and smelting; combustion of leaded gasoline; the use of Pb in hunting, target shooting, and recreational angling; the use of Pb-based paints; and the uncontrolled disposal of Pb-containing products such as old vehicle batteries and electronic devices have resulted in increased environmental levels of Pb, and have created risks for Pb exposure and toxicity in invertebrates, fish, and wildlife in some ecosystems.

  19. Horizontal and Vertical Distribution of Heavy Metals in Farm Produce and Livestock around Lead-Contaminated Goldmine in Dareta and Abare, Zamfara State, Northern Nigeria

    O. E. Orisakwe

    2017-01-01

    Full Text Available Background. Hitherto studies in response to the June 2010 lead poisoning, Zamfara State, Nigeria, have focused on clinical interventions without information on livestock and other metals. Objective. This study has investigated the distribution of heavy metals in farm produce and livestock around lead-contaminated goldmine in Dareta and Abare, Zamfara State, Nigeria. Methods. Vegetables, soil, water, blood, and different meat samples were harvested from goat, sheep, cattle, and chicken from Dareta, Abare, and Gusau communities. The samples were digested with 10 mL of a mix of nitric and perchloric acids; the mixture was then heated to dryness. Lead, cadmium, zinc, chromium, copper, magnesium, and nickel were analysed using flame Atomic Absorption Spectrophotometer. The daily intake, bioaccumulation factor, and target hazard quotient (THQ were calculated. Results. Chicken bone-muscles from Dareta had the highest concentrations of lead, zinc, and nickel (28.2750, 16.1650, and 4.2700 mg/kg, resp., while chicken brain had the highest levels of cadmium, magnesium (0.3800 and 67.5400 mg/kg, and chromium (6.1650 mg/kg, kidney tissue inclusive. Conclusion. In addition to lead, cadmium may also be of concern in the contaminated mining communities of Zamfara State, Nigeria, given the high levels of cadmium in meat and vegetables samples from these areas.

  20. Molecular mechanisms of the epithelial transport of toxic metal ions, particularly mercury, cadmium, lead, arsenic, zinc, and copper. Progress report, January 1, 1979-December 31, 1979

    Wasserman, R.H.

    1979-01-01

    The mechanism of lead transport is presented, and especially the particular similarities or dissimilarities between lead and calcium in this process. The absorption of these metals was determined cockerels, raised on a commercial diet or on a specified diet, using in vivo ligated loop procedure. The dose administered into the loop contained 0.5 μCi 203 Pb (and/or 0.1 μCi 47 Ca), and 0.01 mM lead acetate (and/or mM CaCl 2 ) in 0.5 ml 0.15 M NaCl,pH 6.5. It was shown that lead is rapidly taken up by the mucosal tissue, and slowly transferred into the body, whereas less calcium is retained by the tissue and the transfer of calcium is many times as effective as that for lead. They appear to respond in a similar manner to a low calcium intake and vitamin D treatment. Increasing luminal stable lead concentration significantly reduced the percentage of radiolead significantly reduced the percentage of radiolead absorbed, but did not affect the absorption of calcium. Also, vitamin D enhanced the transfer of plasma 47 Ca into the lumen but did not affect the transfer of plasma 203 Pb. Intravenous administration of 1,25(OH) 2 CC to rachitic chicks enhanced calcium and lead absorption, but the maximal absorption of these metals occurred at slightly different times after administering this metabolite, indicating that two different transport systems may be involved. It was concluded that lead is transported across the epithelial wall by a passive diffusion and this process is affected by vitamin D in a similar manner as this vitamin affects the diffusional component of calcium transport

  1. Immersed transient eddy current flow metering: a calibration-free velocity measurement technique for liquid metals

    Krauter, N.; Stefani, F.

    2017-10-01

    Eddy current flow meters are widely used for measuring the flow velocity of electrically conducting fluids. Since the flow induced perturbations of a magnetic field depend both on the geometry and the conductivity of the fluid, extensive calibration is needed to get accurate results. Transient eddy current flow metering has been developed to overcome this problem. It relies on tracking the position of an impressed eddy current system that is moving with the same velocity as the conductive fluid. We present an immersed version of this measurement technique and demonstrate its viability by numerical simulations and a first experimental validation.

  2. Immersed transient eddy current flow metering: a calibration-free velocity measurement technique for liquid metals

    Krauter, N; Stefani, F

    2017-01-01

    Eddy current flow meters are widely used for measuring the flow velocity of electrically conducting fluids. Since the flow induced perturbations of a magnetic field depend both on the geometry and the conductivity of the fluid, extensive calibration is needed to get accurate results. Transient eddy current flow metering has been developed to overcome this problem. It relies on tracking the position of an impressed eddy current system that is moving with the same velocity as the conductive fluid. We present an immersed version of this measurement technique and demonstrate its viability by numerical simulations and a first experimental validation. (paper)

  3. Systematic review and meta-analysis links autism and toxic metals and highlights the impact of country development status: Higher blood and erythrocyte levels for mercury and lead, and higher hair antimony, cadmium, lead, and mercury.

    Saghazadeh, Amene; Rezaei, Nima

    2017-10-03

    Autism spectrum disorder (ASD) is a heterogeneous neurodevelopmental disorder that affects cognitive and higher cognitive functions. Increasing prevalence of ASD and high rates of related comorbidities has caused serious health loss and placed an onerous burden on the supporting families, caregivers, and health care services. Heavy metals are among environmental factors that may contribute to ASD. However, due to inconsistencies across studies, it is still hard to explain the association between ASD and toxic metals. Therefore the objective of this study was to investigate the difference in heavy metal measures between patients with ASD and control subjects. We included observational studies that measured levels of toxic metals (antimony, arsenic, cadmium, lead, manganese, mercury, nickel, silver, and thallium) in different specimens (whole blood, plasma, serum, red cells, hair and urine) for patients with ASD and for controls. The main electronic medical database (PubMed and Scopus) were searched from inception through October 2016. 52 studies were eligible to be included in the present systematic review, of which 48 studies were included in the meta-analyses. The hair concentrations of antimony (standardized mean difference (SMD)=0.24; 95% confidence interval (CI): 0.03 to 0.45) and lead (SMD=0.60; 95% confidence interval (CI): 0.17 to 1.03) in ASD patients were significantly higher than those of control subjects. ASD patients had higher erythrocyte levels of lead (SMD=1.55, CI: 0.2 to 2.89) and mercury (SMD=1.56, CI: 0.42 to 2.70). There were significantly higher blood lead levels in ASD patients (SMD=0.43, CI: 0.02 to 0.85). Sensitivity analyses showed that ASD patients in developed but not in developing countries have lower hair concentrations of cadmium (SMD=-0.29, CI: -0.46 to -0.12). Also, such analyses indicated that ASD patients in developing but not in developed lands have higher hair concentrations of lead (SMD=1.58, CI: 0.80 to 2.36) and mercury (SMD=0

  4. Mutual Inductance Problem for a System Consisting of a Current Sheet and a Thin Metal Plate

    Fulton, J. P.; Wincheski, B.; Nath, S.; Namkung, M.

    1993-01-01

    Rapid inspection of aircraft structures for flaws is of vital importance to the commercial and defense aircraft industry. In particular, inspecting thin aluminum structures for flaws is the focus of a large scale R&D effort in the nondestructive evaluation (NDE) community. Traditional eddy current methods used today are effective, but require long inspection times. New electromagnetic techniques which monitor the normal component of the magnetic field above a sample due to a sheet of current as the excitation, seem to be promising. This paper is an attempt to understand and analyze the magnetic field distribution due to a current sheet above an aluminum test sample. A simple theoretical model, coupled with a two dimensional finite element model (FEM) and experimental data will be presented in the next few sections. A current sheet above a conducting sample generates eddy currents in the material, while a sensor above the current sheet or in between the two plates monitors the normal component of the magnetic field. A rivet or a surface flaw near a rivet in an aircraft aluminum skin will disturb the magnetic field, which is imaged by the sensor. Initial results showed a strong dependence of the flaw induced normal magnetic field strength on the thickness and conductivity of the current-sheet that could not be accounted for by skin depth attenuation alone. It was believed that the eddy current imaging method explained the dependence of the thickness and conductivity of the flaw induced normal magnetic field. Further investigation, suggested the complexity associated with the mutual inductance of the system needed to be studied. The next section gives an analytical model to better understand the phenomenon.

  5. Metal-free current collectors based on graphene materials for supecapacitors produced by 3D printing

    Baskakov, S. A.; Baskakova, Yu. V.; Lyskov, N. V.; Dremova, N. N.; Shul'ga, Yu. M.

    2017-10-01

    Supercapacitor (SC) current collectors with electrodes made of graphite oxide reduced during microwave exfoliation are produced from a commercial filament with a graphene component via layer-by-layer fusing with a 3D printer. The separator is made of a graphene oxide film. The current collectors are investigated by means of IR spectroscopy. Electrochemical tests are performed for the assembled SC that include tests of its cyclic stability up to 1000 cycles.

  6. Numerical Simulation of Tunneling Current in an Anisotropic Metal-Oxide-Semiconductor Capacitor

    Khairurrijal khairurrijal

    2012-09-01

    Full Text Available In this paper, we have developed a model of the tunneling currents through a high-k dielectric stack in MOS capacitors with anisotropic masses. The transmittance was numerically calculated by employing a transfer matrix method and including longitudinal-transverse kinetic energy coupling which is represented by an electron phase velocity in the gate. The transmittance was then applied to calculate tunneling currents in TiN/HfSiOxN/SiO2/p-Si MOS capacitors. The calculated results show that as the gate electron velocity increases, the transmittance decreases and therefore the tunneling current reduces. The tunneling current becomes lower as the effective oxide thickness (EOT of HfSiOxN layer increases. When the incident electron passed through the barriers in the normal incident to the interface, the electron tunneling process becomes easier. It was also shown that the tunneling current was independent of the substrate orientation. Moreover, the model could be used in designing high speed MOS devices with low tunneling currents.

  7. MECHANISM(S) OF UPTAKE AND SEQUESTRATION OF LEAD AND OTHER HEAVY METALS BY PSEUDOMONAS AERUGINOSA CHL-004

    Heavy metals in soils and sediments of anthropogenic origin are a major environmental concern, due to the significant health risks they pose and due to the difficulties encountered with their remediation. Diverse industries involved in energy production, pigment synthesis and the...

  8. The combined effect of freeze thaw events and heavy metal pollution leads to distinct lethal synergy in Enchytraeus albidus

    Boas, Sara Wincentz; Slotsbo, Stine; Holmstrup, Martin

    Many anthropogenic activities negatively affect the environment and stress the organisms living here in various ways. Due to global warming it is likely that freeze-thaw events will replace permanent freezing of soils in arctic regions. Metals are some of the most common contaminants in soil...

  9. Comparison of the concentrations of metal elements and isotopes of lead found in rice and rice bran.

    Dai, Shouhui; Yang, Hui; Yang, Lan; Wang, Fuhua; Du, Ruiying; Wen, Dian

    2014-08-01

    Very few studies have investigated the difference in the distribution of metal elements between rice and rice bran samples. In this study, the concentrations of 27 metal elements (Li, Be, Na, Mg, Al, K, Ca, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, As, Se, Rb, Sr, Ag, Cd, Cs, Ba, Tl, Pb, and U) in 56 polished rice and their corresponding bran samples were determined. A significant difference in concentrations of all elements except Ag and Cd was found between rice and bran (P rice ratios of 1.21 to 36.3. High concentrations of metal elements, especially that of the heavy metal Cr, in bran samples present a potential safety issue for bran products, such as food and feed containing bran. Pb isotope ((204)Pb, (206)Pb, (207)Pb, and (208)Pb) ratios also were determined. The (206)Pb/(207)Pb and (208)Pb/(207)Pb ratios in bran were generally higher than those in rice (P rice and bran samples were distinctly different from each other, indicating that Pb isotope composition is an effective for discriminating between bran and rice samples.

  10. Archaeological reconstruction of medieval lead production: Implications for ancient metal provenance studies and paleopollution tracing by Pb isotopes

    Baron, Sandrine; Le-Carlier, Cecile; Carignan, Jean; Ploquin, Alain

    2009-01-01

    The identification of metal provenance is often based on chemical and Pb isotope analyses of materials from the operating chain, mainly ores and metallic artefacts. Such analyses, however, have their limits. Some studies are unable to trace metallic artefacts or ingots to their ore sources, even in well-constrained archaeological contexts. Possible reasons for this difficulty are to be found among a variety of limiting factors: (i) problems of ore signatures, (ii) mixing of different ores (alloys), (iii) the use of additives during the metallurgical process, (iv) metal recycling and (v) possible Pb isotopic fractionation during metal production. This paper focuses on the issue of Pb isotope fractionation during smelting to address the issue of metal provenance. Through an experimental reconstruction of argentiferous Pb production in the medieval period, an attempt was made to better understand and interpret the Pb isotopic composition of ore smelting products. It is shown that the measured differences (outside the total external uncertainties of 0.005 (2*sd) for 206 Pb/ 204 Pb ratios) in Pb signatures measured between ores, slag and smoke are not due to Pb mass fractionation processes, but to (1) ore heterogeneity (Δ 206 Pb/ 204 Pb slag-ores = 0.066) and (2) the use of additives during the metallurgical process (Δ 206 Pb/ 204 Pb slag-ores = 0.083). Even if these differences are due to causes (1) and/or (2), smoke from the ore reduction appears to reflect the ore mining area without a significant disturbance of its Pb signature for all the isotopic ratios (Δ 206 Pb/ 204 Pb smokes-ores = 0.026). Thus, because the isotopic heterogeneity of the mining district and additives is averaged in slags, slag appears as the most relevant product to identify ancient metal provenance. Whereas aiming at identifying a given mine seems beyond the possibilities provided by the method, searching for the mining district through analysis of the smelting workshop materials should

  11. Contamination and health risks of soil heavy metals around a lead/zinc smelter in southwestern China.

    Li, Peizhong; Lin, Chunye; Cheng, Hongguang; Duan, Xiaoli; Lei, Kai

    2015-03-01

    Anthropogenic emissions of toxic metals from smelters are a global problem. The objective of this study was to investigate the distribution of toxic metals in soils around a 60 year-old Pb/Zn smelter in a town in Yunnan Province of China. Topsoil and soil core samples were collected and analyzed to determine the concentrations of various forms of toxic metals. The results indicated that approximately 60 years of Pb/Zn smelting has led to significant contamination of the local soil by Zn, Pb, Cd, As, Sb, and Hg, which exhibited maximum concentrations of 8078, 2485, 75.4, 71.7, 25.3, and 2.58mgkg(-1), dry wet, respectively. Other metals, including Co, Cr, Cu, Mn, Ni, Sc, and V, were found to originate from geogenic sources. The concentrations of smelter driven metals in topsoil decreased with increasing distance from the smelter. The main contamination by Pb, Zn, and Cd was found in the upper 40cm of soil around the Pb/Zn smelter, but traces of Pb, Zn, and Cd contamination were found below 100cm. Geogenic Ni in the topsoil was mostly bound in the residual fraction (RES), whereas anthropogenic Cd, Pb, and Zn were mostly associated with non-RES fractions. Therefore, the smelting emissions increased not only the concentrations of Cd, Pb, and Zn in the topsoil but also their mobility and bioavailability. The hazard quotient and hazard index showed that the topsoil may pose a health risk to children, primarily due to the high Pb and As contents of the soil. Copyright © 2014 Elsevier Inc. All rights reserved.

  12. Low-Cost Open-Source Voltage and Current Monitor for Gas Metal Arc Weld 3D Printing

    Pinar, A.; Wijnen, B.; Anzalone, G. C.; Havens, T. C.; Sanders, P. G.; Pearce, J. M.

    2015-01-01

    Arduino open-source microcontrollers are well known in sensor applications for scientific equipment and for controlling RepRap 3D printers. Recently low-cost open-source gas metal arc weld (GMAW) RepRap 3D printers have been developed. The entry-level welders used have minimal controls and therefore lack any real-time measurement of welder voltage or current. The preliminary work on process optimization of GMAW 3D printers requires a low-cost sensor and data logger system to measure welder cu...

  13. Deposition of heavy metal in the environment. Balances of the consumption and fate of lead and cadmium 1984-1989

    Balzer, D.

    1991-10-01

    The data on the consumption and fate of lead and cadmium as well as their compounds was compiled in a balance for the Federal Republic of Germany for the period between 1984 and 1989. To obtain a general overview of the known mass flows, additional flow sheets for lead and cadmium were drawn up. (orig./BBR) [de

  14. Metal metabolism in laboratory animals and human tissues as investigated by neutron activation analysis: current status and perspectives

    Sabbioni, E.; Pietra, R.; Marafante, E.

    1982-01-01

    The definition of dose-response relationships in man is the essential requisite to set scientifically health protection standards for the evaluation of a safe level exposure of humans to heavy metals. The derivation of these relationships requires sequential multidisciplinary informations including data on metabolic patterns and biochemical effects in mammals. Unfortunately, sufficient data are not available to establish dose-response curves expecially in long term-low level exposure conditions and a need exists to gather such informations for each metal on absorption, distribution and excretion in laboratory animals and humans. This paper: (1) discuss main problems related to the use of neutron activation analysis (NAA) in metallobiochemistry of present levels of trace elements; (2) report data on the current applications of NAA in metallobiochemistry in relation to the work carried out in the context of a project Heavy Metal Pollution of CEC JRC - Ispra. Applications deal with in vivo studies on laboratory animals, in vitro studies on biochemical systems and experiments on tissues of human origin; (3) discuss the perspectives of the use of the nuclear techniques in the environmental toxicology. (author)

  15. Continuum model of tensile fracture of metal melts and its application to a problem of high-current electron irradiation of metals

    Mayer, Alexander E.; Mayer, Polina N.

    2015-01-01

    A continuum model of the metal melt fracture is formulated on the basis of the continuum mechanics and theory of metastable liquid. A character of temperature and strain rate dependences of the tensile strength that is predicted by the continuum model is verified, and parameters of the model are fitted with the use of the results of the molecular dynamics simulations for ultra-high strain rates (≥1–10/ns). A comparison with experimental data from literature is also presented for Al and Ni melts. Using the continuum model, the dynamic tensile strength of initially uniform melts of Al, Cu, Ni, Fe, Ti, and Pb within a wide range of strain rates (from 1–10/ms to 100/ns) and temperatures (from melting temperature up to 70–80% of critical temperature) is calculated. The model is applied to numerical investigation of a problem of the high-current electron irradiation of Al, Cu, and Fe targets

  16. Extraction and recovery of mercury and lead from aqueous waste streams using redox-active layered metal chalcogenides. Annual progress report, September 15, 1996 - September 14, 1997

    Dorhout, P.K.; Strauss, S.H.

    1997-01-01

    'The authors have begun to examine the extraction and recovery of heavy elements from aqueous waste streams using redox-active metal chalcogenides. They have been able to prepare extractants from known chalcogenide starting materials, studied the efficacy of the extractants for selective removal of soft metal ions from aqueous phases, studied the deactivation of extractants and the concomitant recovery of soft metal ions from the extractants, and characterized all of the solids and solutions thus far in the study. The study was proposed as two parallel tasks: Part 1 and Part 2 emphasize the study and development of known metal chalcogenide extractants and the synthesis and development of new metal chalcogenide extractants, respectively. The two tasks were divided into sub-sections that study the extractants and their chemistry as detailed below: Preparation and reactivity of metal chalcogenide host solids Extraction of target waste (guest) ions from simulated waste streams Examination of the guest-host solids recovery of the guest metal and reuse of extractant Each section of the two tasks was divided into focused subsections that detail the specific problems and solutions to those problems that were proposed. The extent to which those tasks have been accomplished and the continued efforts of the team are described in detail below. (b) Progress and Results. The DOE-supported research has proceeded largely as proposed and has been productive in its first 12 months. Two full-paper manuscripts were submitted and are currently under peer review. A third paper is in preparation and will be submitted shortly. In addition, 5 submitted or invited presentations have been made.'

  17. Coordination chemistry of two heavy metals: I, Ligand preferences in lead(II) complexation, toward the development of therapeutic agents for lead poisoning: II, Plutonium solubility and speciation relevant to the environment

    Neu, Mary Patricia [Univ. of California, Berkeley, CA (United States)

    1993-11-01

    The coordination chemistry and solution behavior of the toxic ions lead(II) and plutonium(IV, V, VI) have been investigated. The ligand pKas and ligand-lead(II) stability constants of one hydroxamic acid and four thiohydroaxamic acids were determined. Solution thermodynamic results indicate that thiohydroxamic acids are more acidic and slightly better lead chelators than hydroxamates, e.g., N-methylthioaceto-hydroxamic acid, pKa = 5.94, logβ120 = 10.92; acetohydroxamic acid, pKa = 9.34, logβ120 = 9.52. The syntheses of lead complexes of two bulky hydroxamate ligands are presented. The X-ray crystal structures show the lead hydroxamates are di-bridged dimers with irregular five-coordinate geometry about the metal atom and a stereochemically active lone pair of electrons. Molecular orbital calculations of a lead hydroxamate and a highly symmetric pseudo octahedral lead complex were performed. The thermodynamic stability of plutonium(IV) complexes of the siderophore, desferrioxamine B (DFO), and two octadentate derivatives of DFO were investigated using competition spectrophotometric titrations. The stability constant measured for the plutonium(IV) complex of DFO-methylterephthalamide is logβ120 = 41.7. The solubility limited speciation of 242Pu as a function of time in near neutral carbonate solution was measured. Individual solutions of plutonium in a single oxidation state were added to individual solutions at pH = 6.0, T = 30.0, 1.93 mM dissolved carbonate, and sampled over intervals up to 150 days. Plutonium solubility was measured, and speciation was investigated using laser photoacoustic spectroscopy and chemical methods.

  18. Coordination chemistry of two heavy metals: I, Ligand preferences in lead(II) complexation, toward the development of therapeutic agents for lead poisoning: II, Plutonium solubility and speciation relevant to the environment

    Neu, M.P.

    1993-11-01

    The coordination chemistry and solution behavior of the toxic ions lead(II) and plutonium(IV, V, VI) have been investigated. The ligand pK a s and ligand-lead(II) stability constants of one hydroxamic acid and four thiohydroaxamic acids were determined. Solution thermodynamic results indicate that thiohydroxamic acids are more acidic and slightly better lead chelators than hydroxamates, e.g., N-methylthioaceto-hydroxamic acid, pK a = 5.94, logβ 120 = 10.92; acetohydroxamic acid, pK a = 9.34, logβ l20 = 9.52. The syntheses of lead complexes of two bulky hydroxamate ligands are presented. The X-ray crystal structures show the lead hydroxamates are di-bridged dimers with irregular five-coordinate geometry about the metal atom and a stereochemically active lone pair of electrons. Molecular orbital calculations of a lead hydroxamate and a highly symmetric pseudo octahedral lead complex were performed. The thermodynamic stability of plutonium(IV) complexes of the siderophore, desferrioxamine B (DFO), and two octadentate derivatives of DFO were investigated using competition spectrophotometric titrations. The stability constant measured for the plutonium(IV) complex of DFO-methylterephthalamide is logβ 110 = 41.7. The solubility limited speciation of 242 Pu as a function of time in near neutral carbonate solution was measured. Individual solutions of plutonium in a single oxidation state were added to individual solutions at pH = 6.0, T = 30.0, 1.93 mM dissolved carbonate, and sampled over intervals up to 150 days. Plutonium solubility was measured, and speciation was investigated using laser photoacoustic spectroscopy and chemical methods

  19. Unexpected current lowering by a low work-funkction metal contact: Mg/SI-GaAs

    Dubecký, F.; Dubecký, M.; Hubík, Pavel; Kindl, Dobroslav; Gombia, E.; Baldini, M.; Nečas, V.

    2013-01-01

    Roč. 82, APR (2013), s. 72-76 ISSN 0038-1101 Institutional support: RVO:68378271 Keywords : Schottky barrier * low-bias transport * semi-insulating GaAs * low work -function * high resistence * low leakage current * blocking contact Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.514, year: 2013

  20. On the surface recombination current of metal-insulator semiconductor inversion layer solar cells

    Nielsen, Otto M.

    1981-01-01

    voltages Voc were found to be lower than for ~ cells. The measured differences in Voc were higher than expected from the dark characteristics which is explained as a difference in the surface recombination current due to a higher interface state density Nss of ~ cells. Journal of Applied Physics...

  1. Microstructure and critical current density in high-Tc metal oxide superconductors

    Johnson, S.M.; Gusman, M.I.

    1992-03-01

    Superconductor powders in the U-Ba-Cu-O (YBCO) and Bi-Pb-Sr-Ca-Cu-O (BSCCO) systems were synthesized by freeze-drying. Powders were characterized, and processed into samples for evaluation of superconducting behavior. Freeze-drying is attractive because the powders have high purity, are homogeneous, have a small size and are active. YBCO powders can be sintered to high density at 890 degrees C. Many compositions, processing approaches and heat treatments were explored in an effort to understand relations between microstructure and critical density, and to improve the critical current density. Powders were also formed into sputtering targets for coating preparation at Stanford University. The highest critical current density achieved with the YBCO powders was ∼15,000 A/cm 2 at 4.2K and 0.5T using powders treated to prevent carbon contamination. The BSCCO materials with the highest critical current density, ∼30,000 A/cm 2 at the same conditions were formed by heat treating melted and quenched samples. All critical current density measurements were made by Stanford University, a subcontractor to this effort. Stanford University also prepared coatings by off-axis magnetron sputtering

  2. Heavy metals (lead, cadmium, methylmercury, arsenic) in commonly imported rice grains (Oryza sativa) sold in Saudi Arabia and their potential health risk.

    Al-Saleh, Iman; Abduljabbar, Mai

    2017-10-01

    The levels of heavy metals (lead, cadmium, methylmercury and arsenic) were determined in 37 brands of imported rice commonly consumed in Saudi Arabia after soaking and rinsing with water, and their potential health risks to residents were estimated by three indices: hazard quotient (HQ), hazard index (HI) and cancer risk (CR). The mean levels of lead, cadmium, methylmercury and total arsenic in soaked (rinsed) rice grains were 0.034 (0.057), 0.015 (0.027), 0.004 (0.007) and 0.202 (0.183) μg/g dry weight, respectively. Soaking or rinsing rice grains with water decreased lead and cadmium levels in all brands to safe levels. All brands had total arsenic above the acceptable regulatory limits, irrespective of soaking or rinsing, and eight soaked and 12 rinsed brands contained methylmercury. The levels of all heavy metals except cadmium were above the acceptable regulatory limits when the rice was neither rinsed nor soaked. Weekly intakes of lead, cadmium, methylmercury and total arsenic from soaked (rinsed) grains were 0.638 (1.068), 0.279 (0.503), 0.271 (0.309) and 3.769 (3.407) μg/kg body weight (bw). The weekly intakes of lead and methylmercury from the consumption of one rinsed and two soaked rice brands respectively, exceeded the Provisional Tolerance Weekly Intake set by the Food and Agriculture Organization and the World Health Organization. The weekly intake of total arsenic for all brands was above the lowest benchmark dose lower confidence limit (BMDL 01 ) level of 0.3μg/kg bw/d for an increased cancer risk set by European Food Safety Authority. Either soaking or rinsing grains before consumption can minimize the non-carcinogenic health risks to residents from cadmium and lead (HQrice contaminated mainly with arsenic (HQ>1 all brands) and to a lesser extent with methylmercury (HQ>1 in 4 brands), even when soaked or rinsed with water before consumption. The combined non-carcinogenic effect of all metals expressed as HI was >1, including soaked or rinsed

  3. Current studies on bacterospermia the leading cause of male infertility: a prot?g? and potential threat towards mans extinction

    Isaiah, Ibeh Nnana; Nche, Bikwe Thomas; Nwagu, Ibeh Georgina; Nnanna, Ibeh Isaiah

    2011-01-01

    Background: The current rise of male infertility associated with bacterospermia and urogenital infection has been on the increase amongst adult married males in Benin metropolis and a major cause of concern to male fertility and reproduction in Nigeria. Aim: To microbiologically isolate and study the infectious agent that has led to male infertility and also to study the percentage occurrence of bacteropsermia and urogenital caused infertility in adult married males in Benin metropolis Materi...

  4. Industrial inline PVD metallization for silicon solar cells with laser fired contacts leading to 21.8% efficiency

    Nekarda, J.; Reinwand, D.; Hartmann, P.; Preu, R.

    2010-01-01

    In this contribution we present the latest results of our experiments in regard to an industrially feasible inline physical vapor deposition (PVD) metallization method for the rear side of passivated solar cells. In an earlier publication, the quality of such processed layers and the feasibility of the tool was already shown and compared with a commonly used laboratory process based on electron beam evaporation. Since then a difference in the Voc potential in the range of ~ 4 mV between both ...

  5. Anchoring plant metallothioneins to the inner face of the plasma membrane of Saccharomyces cerevisiae cells leads to heavy metal accumulation.

    Lavinia Liliana Ruta

    Full Text Available In this study we engineered yeast cells armed for heavy metal accumulation by targeting plant metallothioneins to the inner face of the yeast plasma membrane. Metallothioneins (MTs are cysteine-rich proteins involved in the buffering of excess metal ions, especially Cu(I, Zn(II or Cd(II. The cDNAs of seven Arabidopsis thaliana MTs (AtMT1a, AtMT1c, AtMT2a, AtMT2b, AtMT3, AtMT4a and AtMT4b and four Noccaea caerulescens MTs (NcMT1, NcMT2a, NcMT2b and NcMT3 were each translationally fused to the C-terminus of a myristoylation green fluorescent protein variant (myrGFP and expressed in Saccharomyces cerevisiae cells. The myrGFP cassette introduced a yeast myristoylation sequence which allowed directional targeting to the cytosolic face of the plasma membrane along with direct monitoring of the intracellular localization of the recombinant protein by fluorescence microscopy. The yeast strains expressing plant MTs were investigated against an array of heavy metals in order to identify strains which exhibit the (hyperaccumulation phenotype without developing toxicity symptoms. Among the transgenic strains which could accumulate Cu(II, Zn(II or Cd(II, but also non-canonical metal ions, such as Co(II, Mn(II or Ni(II, myrGFP-NcMT3 qualified as the best candidate for bioremediation applications, thanks to the robust growth accompanied by significant accumulative capacity.

  6. Anchoring plant metallothioneins to the inner face of the plasma membrane of Saccharomyces cerevisiae cells leads to heavy metal accumulation.

    Ruta, Lavinia Liliana; Lin, Ya-Fen; Kissen, Ralph; Nicolau, Ioana; Neagoe, Aurora Daniela; Ghenea, Simona; Bones, Atle M; Farcasanu, Ileana Cornelia

    2017-01-01

    In this study we engineered yeast cells armed for heavy metal accumulation by targeting plant metallothioneins to the inner face of the yeast plasma membrane. Metallothioneins (MTs) are cysteine-rich proteins involved in the buffering of excess metal ions, especially Cu(I), Zn(II) or Cd(II). The cDNAs of seven Arabidopsis thaliana MTs (AtMT1a, AtMT1c, AtMT2a, AtMT2b, AtMT3, AtMT4a and AtMT4b) and four Noccaea caerulescens MTs (NcMT1, NcMT2a, NcMT2b and NcMT3) were each translationally fused to the C-terminus of a myristoylation green fluorescent protein variant (myrGFP) and expressed in Saccharomyces cerevisiae cells. The myrGFP cassette introduced a yeast myristoylation sequence which allowed directional targeting to the cytosolic face of the plasma membrane along with direct monitoring of the intracellular localization of the recombinant protein by fluorescence microscopy. The yeast strains expressing plant MTs were investigated against an array of heavy metals in order to identify strains which exhibit the (hyper)accumulation phenotype without developing toxicity symptoms. Among the transgenic strains which could accumulate Cu(II), Zn(II) or Cd(II), but also non-canonical metal ions, such as Co(II), Mn(II) or Ni(II), myrGFP-NcMT3 qualified as the best candidate for bioremediation applications, thanks to the robust growth accompanied by significant accumulative capacity.

  7. Study of the tunnelling initiated leakage current through the carbon nanotube embedded gate oxide in metal oxide semiconductor structures

    Chakraborty, Gargi; Sarkar, C K; Lu, X B; Dai, J Y

    2008-01-01

    The tunnelling currents through the gate dielectric partly embedded with semiconducting single-wall carbon nanotubes in a silicon metal-oxide-semiconductor (MOS) structure have been investigated. The application of the gate voltage to such an MOS device results in the band bending at the interface of the partly embedded oxide dielectric and the surface of the silicon, initiating tunnelling through the gate oxide responsible for the gate leakage current whenever the thickness of the oxide is scaled. A model for silicon MOS structures, where carbon nanotubes are confined in a narrow layer embedded in the gate dielectric, is proposed to investigate the direct and the Fowler-Nordheim (FN) tunnelling currents of such systems. The idea of embedding such elements in the gate oxide is to assess the possibility for charge storage for memory device applications. Comparing the FN tunnelling onset voltage between the pure gate oxide and the gate oxide embedded with carbon nanotubes, it is found that the onset voltage decreases with the introduction of the nanotubes. The direct tunnelling current has also been studied at very low gate bias, for the thin oxide MOS structure which plays an important role in scaling down the MOS transistors. The FN tunnelling current has also been studied with varying nanotube diameter

  8. Fabrication and Evaluation of One-Axis Oriented Lead Zirconate Titanate Films Using Metal-Oxide Nanosheet Interface Layer

    Minemura, Yoshiki; Nagasaka, Kohei; Kiguchi, Takanori; Konno, Toyohiko J.; Funakubo, Hiroshi; Uchida, Hiroshi

    2013-09-01

    Nanosheet Ca2Nb3O20 (ns-CN) layers with pseudo-perovskite-type crystal configuration were applied on the surface of polycrystalline metal substrates to achieve preferential crystal orientation of Pb(Zr,Ti)O3 (PZT) films for the purpose of enhanced ferroelectricity comparable to that of epitaxial thin films. PZT films with tetragonal symmetry (Zr/Ti=0.40:0.60) were fabricated by chemical solution deposition (CSD) on ns-CN-buffered Inconel 625 and SUS 316L substrates, while ns-CN was applied on the the substrates by dip-coating. The preferential crystal growth on the ns-CN layer can be achieved by favorable lattice matching between (001)/(100)PZT and (001)ns-CN planes. The degree of (001) orientation was increased for PZT films on ns-CN/Inconel 625 and ns-CN/SUS 316L substrates, whereas randomly-oriented PZT films with a lower degree of (001) orientation were grown on bare and Inconel 625 films. Enhanced remanent polarization of 60 µC/cm2 was confirmed for the PZT films on ns-CN/metal substrates, ascribed to the preferential alignment of the polar [001] axis normal to the substrate surface, although it also suffered from higher coercive field above 500 kV/cm caused by PZT/metal interfacial reaction.

  9. Insulation model of power lead for 66 kV class superconducting fault current limiter; Chodendo genryuki denryu rido yo zetsuen no kaihatsu

    Sakai, M.; Fukuda, A.; Shimada, M.; Urata, M. [Toshiba Corp., Tokyo (Japan); Okuma, T.; Sato, Y.; Iwata, Y. [Tokyo Electric Power Co. Ink., Tokyo (Japan)

    1999-06-07

    We advance the development of high-temperature superconductivity current limiter using the normal conduction transition. Since the rated voltage is high with 66kV, we desire that solid insulation which consists of main insulating layer and multiple layers in semiconductive layer is conducted to the current lead which connects the ordinary temperature and very low temperature division. And, it is necessary to sufficiently decrease the void, since crack proof and dielectric strength lower, when large bubble exists in the main insulating layer. We use ethylene propylene rubber for the solid insulation of superconducting cable. Though filler has entered the EP-rubber, the formability lowers, when we put filler in, and the void becomes easy to be generated. Then, we produced the current lead insulation model using the EP-rubber without filler, and we carried out crack-resistant test and withstand voltage test. (NEDO)

  10. Design and array signal suggestion of array type pulsed eddy current probe for health monitoring of metal tubes

    Shin, Young Kil [Dept. of Electrical Engineering, Kunsan National University, Kunsan (Korea, Republic of)

    2015-10-15

    An array type probe for monitoring metal tubes is proposed in this paper which utilizes peak value and peak time of a pulsed eddy current(PEC) signal. The probe consists of an array of encircling coils along a tube and the outside of coils is shielded by ferrite to prevent source magnetic fields from directly affecting sensor signals since it is the magnetic fields produced by eddy currents that reflect the condition of metal tubes. The positions of both exciter and sensor coils are consecutively moved automatically so that manual scanning is not necessary. At one position of send-receive coils, peak value and peak time are extracted from a sensor PEC signal and these data are accumulated for all positions to form an array type peak value signal and an array type peak time signal. Numerical simulation was performed using the backward difference method in time and the finite element method for spatial analysis. Simulation results showed that peak value increases and the peak appears earlier as the defect depth or length increases. The proposed array signals are shown to be excellent in reflecting the defect location as well as variations of defect depth and length within the array probe.

  11. Metal current collector-free freestanding silicon–carbon 1D nanocomposites for ultralight anodes in lithium ion batteries

    Choi, Jang Wook

    2010-12-15

    Although current collectors take up more weight than active materials in most lithium ion battery cells, so far research has been focused mainly on improving gravimetric capacities of active materials. To address this issue of improving gravimetric capacities based on overall cell components, we develop freestanding nanocomposites made of carbon nanofibers (CNFs) and silicon nanowires (SiNWs) as metal current collector-free anode platforms. Intrinsically large capacities of SiNWs as active materials in conjunction with the light nature of freestanding CNF films allow the nanocomposites to achieve 3-5 times improved gravimetric capacities compared to what have been reported in the literature. Moreover, three-dimensional porous structures in the CNF films facilitate increased mass loadings of SiNWs when compared to flat substrates and result in good cycle lives over 40 cycles. This type of nanocomposite cell suggests that 3D porous platforms consisting of light nanomaterials can provide for higher gravimetric and areal capacities when compared to conventional battery cells based on flat, heavy metal substrates. © 2010 Elsevier B.V. All rights reserved.

  12. Direct Metal Laser Sintering Titanium Dental Implants: A Review of the Current Literature

    Mangano, F.; Chambrone, L.; van Noort, R.; Miller, C.; Hatton, P.; Mangano, C.

    2014-01-01

    Statement of Problem. Direct metal laser sintering (DMLS) is a technology that allows fabrication of complex-shaped objects from powder-based materials, according to a three-dimensional (3D) computer model. With DMLS, it is possible to fabricate titanium dental implants with an inherently porous surface, a key property required of implantation devices. Objective. The aim of this review was to evaluate the evidence for the reliability of DMLS titanium dental implants and their clinical and histologic/histomorphometric outcomes, as well as their mechanical properties. Materials and Methods. Electronic database searches were performed. Inclusion criteria were clinical and radiographic studies, histologic/histomorphometric studies in humans and animals, mechanical evaluations, and in vitro cell culture studies on DMLS titanium implants. Meta-analysis could be performed only for randomized controlled trials (RCTs); to evaluate the methodological quality of observational human studies, the Newcastle-Ottawa scale (NOS) was used. Results. Twenty-seven studies were included in this review. No RCTs were found, and meta-analysis could not be performed. The outcomes of observational human studies were assessed using the NOS: these studies showed medium methodological quality. Conclusions. Several studies have demonstrated the potential for the use of DMLS titanium implants. However, further studies that demonstrate the benefits of DMLS implants over conventional implants are needed. PMID:25525434

  13. Direct metal laser sintering titanium dental implants: a review of the current literature.

    Mangano, F; Chambrone, L; van Noort, R; Miller, C; Hatton, P; Mangano, C

    2014-01-01

    Statement of Problem. Direct metal laser sintering (DMLS) is a technology that allows fabrication of complex-shaped objects from powder-based materials, according to a three-dimensional (3D) computer model. With DMLS, it is possible to fabricate titanium dental implants with an inherently porous surface, a key property required of implantation devices. Objective. The aim of this review was to evaluate the evidence for the reliability of DMLS titanium dental implants and their clinical and histologic/histomorphometric outcomes, as well as their mechanical properties. Materials and Methods. Electronic database searches were performed. Inclusion criteria were clinical and radiographic studies, histologic/histomorphometric studies in humans and animals, mechanical evaluations, and in vitro cell culture studies on DMLS titanium implants. Meta-analysis could be performed only for randomized controlled trials (RCTs); to evaluate the methodological quality of observational human studies, the Newcastle-Ottawa scale (NOS) was used. Results. Twenty-seven studies were included in this review. No RCTs were found, and meta-analysis could not be performed. The outcomes of observational human studies were assessed using the NOS: these studies showed medium methodological quality. Conclusions. Several studies have demonstrated the potential for the use of DMLS titanium implants. However, further studies that demonstrate the benefits of DMLS implants over conventional implants are needed.

  14. Direct Metal Laser Sintering Titanium Dental Implants: A Review of the Current Literature

    F. Mangano

    2014-01-01

    Full Text Available Statement of Problem. Direct metal laser sintering (DMLS is a technology that allows fabrication of complex-shaped objects from powder-based materials, according to a three-dimensional (3D computer model. With DMLS, it is possible to fabricate titanium dental implants with an inherently porous surface, a key property required of implantation devices. Objective. The aim of this review was to evaluate the evidence for the reliability of DMLS titanium dental implants and their clinical and histologic/histomorphometric outcomes, as well as their mechanical properties. Materials and Methods. Electronic database searches were performed. Inclusion criteria were clinical and radiographic studies, histologic/histomorphometric studies in humans and animals, mechanical evaluations, and in vitro cell culture studies on DMLS titanium implants. Meta-analysis could be performed only for randomized controlled trials (RCTs; to evaluate the methodological quality of observational human studies, the Newcastle-Ottawa scale (NOS was used. Results. Twenty-seven studies were included in this review. No RCTs were found, and meta-analysis could not be performed. The outcomes of observational human studies were assessed using the NOS: these studies showed medium methodological quality. Conclusions. Several studies have demonstrated the potential for the use of DMLS titanium implants. However, further studies that demonstrate the benefits of DMLS implants over conventional implants are needed.

  15. Effect of cadmium, chromium, lead and metal mixtures on survival and growth of juveniles of the scallop Argopecten ventricosus (Sowerby II, 1842).

    Sobrino-Figueroa, Alma S; Cáceres-Martínez, Carlos; Botello, Alfonso V; Nunez-Nogueira, G

    2007-08-01

    The effects of Cd, Cr, Pb and their mixtures on the growth and sensitivity of the scallop Argopecten ventricosus were analyzed in this study. Cadmium showed to be more toxic metal to juveniles (96 hour median lethal concentration (LC(50)) = 0.396 mg Cd/L), followed by lead (LC(50) = 0.830 mg Pb/L) and chromium (LC(50) = 3.430 mg Cr/L). Cadmium toxicity was 8 times higher than chromium and 2 times than lead. The most toxic combination was Cd + Cr + Pb. (LC(50) = 0.302 mg/L). Based on toxic units analyses (T.U.), a synergistic effect was observed for Cr + Pb and Cd + Cr + Pb. (T.U. = 0.374; T.U. = 0.403), and antagonic effects for Cd + Cr and Cd + Pb (T.U. = 1.26; T.U. = 1.43) respectively. The level of effect (from high to low) on the growth of A. ventricosus juveniles was: Cd > Cd + Cr + Pb > Cr > Pb. The EC(50) (metal concentration where a reduction of 50% growing rate is observed) obtained were: Cd = 0.018 mg/L, Cd + Cr + Pb = 0.104 mg/L, Cr = 0.51 mg/L and Pb = 4.21 mg/L. These results suggest that A. ventricosus juveniles are more sensitive to these metals in comparison to other juveniles from other bivalve species (e.g., A. irradians, Mytillus edulis, Crassostrea virginica).

  16. Characterization of heavy metal-resistant endophytic bacteria from rape (Brassica napus) roots and their potential in promoting the growth and lead accumulation of rape

    Sheng Xiafang; Xia Juanjuan; Jiang Chunyu; He Linyan; Qian Meng

    2008-01-01

    Two lead (Pb)-resistant endophytic bacteria were isolated from rape roots grown in heavy metal-contaminated soils and characterized. A pot experiment was conducted for investigating the capability of the two isolates to promote the growth and Pb uptake of rape from Pb-amended soil. The two isolates were identified as Pseudomonas fluorescens G10 and Microbacterium sp. G16 based on the 16S rDNA gene sequence analysis. Strains G10 and G16 exhibited different multiple heavy metal and antibiotic resistance characteristics and increased water-soluble Pb in solution and in Pb-added soil. Root elongation assays demonstrated increases in root elongation of inoculated rape seedlings compared to the control plants. Strain G16 produced indole acetic acid, siderophores and 1-aminocyclopropane-1-carboxylate deaminase. Increases in biomass production and total Pb uptake in the bacteria-inoculated plants were obtained compared to the control. The two strains could colonize the root interior and rhizosphere soil of rape after root inoculation. - Heavy metal-resistant endophytic bacteria from rape have the potential of promoting the growth and lead uptake of rape

  17. Impact of two iron(III) chelators on the iron, cadmium, lead and nickel accumulation in poplar grown under heavy metal stress in hydroponics.

    Mihucz, Victor G; Csog, Árpád; Fodor, Ferenc; Tatár, Enikő; Szoboszlai, Norbert; Silaghi-Dumitrescu, Luminiţa; Záray, Gyula

    2012-04-15

    Poplar (Populus jacquemontiana var. glauca cv. Kopeczkii) was grown in hydroponics containing 10 μM Cd(II), Ni(II) or Pb(II), and Fe as Fe(III) EDTA or Fe(III) citrate in identical concentrations. The present study was designed to compare the accumulation and distribution of Fe, Cd, Ni and Pb within the different plant compartments. Generally, Fe and heavy-metal accumulation were higher by factor 2-7 and 1.6-3.3, respectively, when Fe(III) citrate was used. Iron transport towards the shoot depended on the Fe(III) chelate and, generally, on the heavy metal used. Lead was accumulated only in the root. The amounts of Fe and heavy metals accumulated by poplar were very similar to those of cucumber grown in an identical way, indicating strong Fe uptake regulation of these two Strategy I plants: a cultivar and a woody plant. The Strategy I Fe uptake mechanism (i.e. reducing Fe(III) followed by Fe(II) uptake), together with the Fe(III) chelate form in the nutrient solution had significant effects on Fe and heavy metal uptake. Poplar appears to show phytoremediation potential for Cd and Ni, as their transport towards the shoot was characterized by 51-54% and 26-48% depending on the Fe(III) supply in the nutrient solution. Copyright © 2012 Elsevier GmbH. All rights reserved.

  18. Adsorbent material based on passion-fruit wastes to remove lead (Pb), chromium (Cr) and copper (Cu) from metal-contaminated waters

    Campos-Flores, Gaby; Castillo-Herrera, Alberto; Gurreonero-Fernández, Julio; Obeso-Obando, Aída; Díaz-Silva, Valeria; Vejarano, Ricardo

    2018-04-01

    The aim of the present work was to evaluate the feasibility of passion-fruit shell (PFS) biomass as adsorbent material to remove heavy metals from contaminated waters. Model mediums were used, which were composed of distilled water and the respective metal: lead (Pb), chromium (Cr) and copper (Cu), with a dose of 10g of dry PFSbiomass per liter of medium. The residual concentration of each metal was determined by Atomic Absorption Spectrophotometry (AAS). A good adsorption capacity was exhibited by this agro industrial waste, achieving removal levels of 96,93 and 82% for Pb, Cr and Cu, respectively. In addition, the results obtained showed an adequate fit to the Freundlich model (R2 > 0.91), on the basis of which, the following values of adsorption capacity (k: 1.7057, 0.6784, 0.3302) and adsorption intensity (n: 0.6869, 2.3474, 1.0499), for Pb, Cr and Cu respectively, were obtained. Our results suggest that Pb, Cr and Cu ions can be removed by more than 80% by using this agro industrial waste, which with a minimum treatment could be used as an adsorbent material in the treatment of metal-contaminated waters.

  19. Metallic amorphous electrodeposited molybdenum coating from aqueous electrolyte: Structural, electrical and morphological properties under current density

    Nemla, Fatima [LEPCM, Department of Physics, University of Batna (Algeria); Cherrad, Djellal, E-mail: cherradphisic@yahoo.fr [Laboratory for Developing New Materials and Their Characterizations, University of Setif (Algeria)

    2016-07-01

    Graphical abstract: - Highlights: • Although difficulties related to electrodeposition of Mo films, we have successfully coated onto a cooper substrate. • A good formation of bcc Mo phase and lattice parameter was very accurate. • It seems that electrical properties of our samples are good and suitable as back contact for thin film solar cells. • It seems that grain size, microstrain and dislocation density are all managed and correlated to retain the resistivity to a considerable minimum value. - Abstract: Molybdenum coatings are extensively utilized as back contact for CIGS-based solar cells. However, their electrodeposition from aqueous electrolyte still sophisticates, since long time, owing to the high reactivity with oxygen. In this study, we present a successful 30 min electrodeposition experiment of somewhat thick (∼0.98–2.9 μm) and of moderate surface roughness RMS (∼47–58 nm), metallic bright Mo coating from aqueous electrolyte containing molybdate ions. XRD analysis and Hall Effect measurements have been used to confirm the presence of Mo. The crystal structure of deposits was slightly amorphous in nature to body centred cubic structure (bcc) Mo (110), (211) and (220) face. Lattice parameters exhibit some weak fluctuated tensile stress when compared to the reference lattice parameter. Additionally, our calculated lattice parameters are in good agreement with some previous works from literature. Discussions on the grain growth prove that they are constrained by grain boundary energy not the thickness effect. Further discussions were made on the electrical resistivity and surface morphology. Resonance scattering of Fermi electrons are expected to contribute towards the variation in the film resistivity through the carrier mobility limitation. However, studied samples might be qualified as candidates for solar cell application.

  20. Effects of rapeseed residue on lead and cadmium availability and uptake by rice plants in heavy metal contaminated paddy soil.

    Ok, Yong Sik; Usman, Adel R A; Lee, Sang Soo; Abd El-Azeem, Samy A M; Choi, Bongsu; Hashimoto, Yohey; Yang, Jae E

    2011-10-01

    Rapeseed (Brassica napus L.) has been cultivated for biodiesel production worldwide. Winter rapeseed is commonly grown in the southern part of Korea under a rice-rapeseed double cropping system. In this study, a greenhouse pot experiment was conducted to assess the effects of rapeseed residue applied as a green manure alone or in combinations with mineral N fertilizer on Cd and Pb speciation in the contaminated paddy soil and their availability to rice plant (Oryza sativa L.). The changes in soil chemical and biological properties in response to the addition of rapeseed residue were also evaluated. Specifically, the following four treatments were evaluated: 100% mineral N fertilizer (N100) as a control, 70% mineral N fertilizer+rapeseed residue (N70+R), 30% mineral N fertilizer+rapeseed residue (N30+R) and rapeseed residue alone (R). The electrical conductivity and exchangeable cations of the rice paddy soil subjected to the R treatment or in combinations with mineral N fertilizer treatment, N70+R and N30+R, were higher than those in soils subjected to the N100 treatment. However, the soil pH value with the R treatment (pH 6.3) was lower than that with N100 treatment (pH 6.9). Use of rapeseed residue as a green manure led to an increase in soil organic matter (SOM) and enhanced the microbial populations in the soil. Sequential extraction also revealed that the addition of rapeseed residue decreased the easily accessible fraction of Cd by 5-14% and Pb by 30-39% through the transformation into less accessible fractions, thereby reducing metal availability to the rice plant. Overall, the incorporation of rapeseed residue into the metal contaminated rice paddy soils may sustain SOM, improve the soil chemical and biological properties, and decrease the heavy metal phytoavailability. Copyright © 2011 Elsevier Ltd. All rights reserved.

  1. Luminescent hybrid materials based on (8-hydroxyquinoline)-substituted metal-organic complexes and lead-borate glasses

    Petrova, Olga B.; Anurova, Maria O.; Akkuzina, Alina A.; Saifutyarov, Rasim R.; Ermolaeva, Ekaterina V.; Avetisov, Roman I.; Khomyakov, Andrew V.; Taydakov, Ilya V.; Avetissov, Igor Ch.

    2017-07-01

    Novel luminescent organic-inorganic hybrid materials based on 8-hydroxyquinoline metal complexes (Liq, Kq, Naq, Rbq, Mgq2, Srq2, Znq2, Scq3, Alq3, Gaq3, and Inq3) have been synthesized by a high temperature exchange reaction with 80PbF2-20B2O3 inorganic low-melting glass. The mechanical and optical properties, transmission spectra, emission an excitation photoluminescence, and luminescence kinetic of hybrid materials were studied. All hybrid materials showed a wide luminescence band in the range 400-700 nm.

  2. Spectrochemical determination of tantalum in plutonium metal using direct current plasma emission spectrometry

    Fadeff, S.K.; Morris, W.F.

    1983-01-01

    Tantalum is determined by direct current plasma spectrometry after separation of plutonium from solution as PuF 3 . After centrifugation of the PuF 3 precipitate, a low level of plutonium remains in solution in sufficient quantity to cause spectral interferences. It is necessary to determine the plutonium by dc plasma spectrometry and apply a correction to determine low tantalum concentrations with good accuracy and precision. Tantalum can be determined down to 0.4 ppM in solution with a relative standard deviation of 10 percent. Better precision can be achieved at higher concentrations. The procedure is simple and convenient for glovebox work. 5 references, 1 figure, 1 table

  3. Humectants To Augment Current From Metallized Zinc Cathodic Protection Systems on Concrete

    Holcomb, Gordon R.; Covino Jr., Bernard S.; Cramer, Stephen D.; Russell, James H. Russell; Bullard, Sophie J.; Collins, W. Keith; Bennett, Jack E. (J.E. Bennett Consulting, Inc.); Soltesz, Steven M. (ODOT); Laylor, H. Martin (ODOT)

    2002-12-01

    Cathodic protection (CP) systems using thermal-sprayed zinc anodes are employed to mitigate the corrosion process in reinforced concrete structures. However, the performance of the anodes is improved by moisture at the anode-concrete interface. Research was conducted to investigate the effect of hydrophilic chemical additives, humectants, on the electrical performance and service life of zinc anodes. Lithium bromide and lithium nitrate were identified as feasible humectants with lithium bromide performing better under galvanic CP and lithium nitrate performing better under impressed current CP. Both humectants improved the electrical operating characteristics of the anode and increased the service life by up to three years.

  4. Quench characteristics of Ag/AuBi2223 HTS-stainless steel stack used for the hybrid current leads of the large hadron collider

    Al-Mosawi, M K; Beduz, C; Yang, Y; Ballarino, A

    2008-01-01

    The quench characteristics of Ag/Au sheathed Bi2223 tapes have been investigated in an adiabatic condition and in a configuration similar to that used in hybrid high temperature superconducting current leads, namely the 13000A leads used for the Large Hadron Collider at CERN. A specialised rig was designed and constructed to provide a carefully controlled environment. The samples were prepared from HTS tape soldered onto a stainless steel substrate with a number of temperature sensors at various positions along the length of tape. One end of the lead (cold end) was maintained at 6K using G-M cryo-cooler whereas the temperature of the other end (warm end) can be varied and maintained at temperatures up to 100K. The thermal runaway currents (quench currents) at various warm end temperatures (in the range of 40-100K) were determined. The temperature evolutions at various locations along the tape were recorded at different top end temperatures and currents. The effect of the stainless steel mechanical reinforceme...

  5. Contaminant Characteristics and Health Risk Assessment of Heavy Metals in Soils from Lead-Zincs Melting Plant in Huize County, Yunnan Province, China

    LIU Xiao-yan

    2016-05-01

    Full Text Available In order to explore history environmental problems of lead-zinc smelting, Huize County, Yunnan Province, forty-two surface soil samples were collected randomly from 14 sampling sites surrounding lead-zinc smelting plant. Heavy metals(Cr, Cu, Mn, Ni, Pb, Zn, Cd, As and Hg in all samples were determined by inductively coupled plasma-optical emission spectroscopy and atomic fluorescence spectrophotometer. Contamination characteristics of heavy metals in soils were observed on the basis of background values of comprehensive pollution index method. Potential risk was evaluated by using the geoaccumulation index(Igeo, potential ecological risk index(RI and health risk assessment method. The results indicated that the average concentrations of Cr, Cu, Mn, Ni, Pb, Zn, Cd, As and Hg were 92.25, 226.81, 1 567.45, 65.16, 394.66, 1 451.63, 11.16, 43.81, 0.47 mg·kg-1, respectively. Based on the Environmental Quality Standard for Soil, the multiple super scale of Cd concentration was highest, more than 274 times. According to the Igeo, Cd ranged from partial severity to serious degree. The RI indicated that the soils around lead-zinc smelting plant were at the serious ecological hazard level. Health risk assessment showed that Pb and Cd in soils surrounding old site had potential health risk to children.

  6. Deposition of airborne metals around the lead-zinc mine in Maarmorilik monitored by lichens and mosses

    Pilegaard, K.

    1994-01-01

    The deposition of heavy metals around the Pb-Zn mine in Maarmorilik (Greenland) was monitored during the year 1979-1990 by analyses of concentrations in in situ lichens (Cetraria nivalis and Umbilicaria Lyngei) and higher plants (rhododendron lapponicum). Concentrations of the metals Ag, As, Cd, Cu, Hg, Pb, S b and Zn decreased with increasing distance from the mining and milling complex according to the model: y = ax b + C where y = concentrations, x = distance, c = background concentration, a and b = constants. The spread was most pronounced west of Maarmorilik. Exposed Pb-Zn mineralizations in the area were found not to influence the overall deposition pattern. The transport of pollutants to higher altitudes was little. Airborne pollution with Cd, Pb and Zn was monitored with suspended Sphagnumbags during a period with ship-loading of concentrates and compared to a period without this activity. There was a strongly increased deposition of airborne Cd, Pb and Zn during periods of ship-loading. The primary sources of pollution were the concentrate conveyor and the ship-loader. Sphagnum-bags were also used to monitor the effects of remedial actions carried out in the mining town. Analyses of the concentrations of Pb in Cetraria during the years 1979 to 1990 showed that pollution during the last years was only about half as large as during the early years. This decrease is attributed to the pollution abatement carried out at the mining complex. (au) (23 refs.)

  7. Heavy metal pollution associated with an abandoned lead-zinc mine in the Kirki region, NE Greece.

    Nikolaidis, Christos; Zafiriadis, Ilias; Mathioudakis, Vasileios; Constantinidis, Theodore

    2010-09-01

    The "Agios Philippos" mine in the Kirki region (NE Greece) has been abandoned in 1998 after half a century of ore exploration without a reclamation or remediation plan. This article aims at elucidating the potential environmental risks associated with this site by quantifying pollution in tailing basins, stream waters, stream sediments and agricultural fields. Concentrations of heavy metals in the abandoned mine tailings reached 12,567 mg/kg for Pb, 22,292 mg/kg for Zn, 174 mg/kg for Cd and 241 mg/kg for As. The geoaccumulation index and enrichment factor for these metals were indicative of extremely high contamination (I(geo) > 5) and extremely high enrichment (EF > 40), respectively. Stream waters in the proximity of the mine had an acidic pH equal to 5.96 and a high sulfate content (SO(4)(-2) = 545.5 mg/L), whereas concentrations of Mn, Zn and Cd reached 2,399 microg/L, 7,681 microg/L and 11.2 microg/L. High I(geo) and EF values for Cd, Zn and As in stream sediments indicates that surface water pollution has a historic background, which is typically associated with acid mine drainage. Agricultural fields in the proximity of the mine exhibited high I(geo) and EF values, which were in decreasing order Cd > Pb > Zn > As. These findings urge for an immediate remediation action of the afflicted area.

  8. Exothermic reaction induced by high-density current in metals: Possible nuclear origin

    Dufour, J. [Laboratoire des sciences nucleaires, CNAM 2, rue Conte 75141, Cedex 03 Paris (France)]. E-mail: dufourj@cnam.fr; Murat, D.; Dufour, X.; Foos, J. [Laboratoire des sciences nucleaires, CNAM 2, rue Conte 75141, Cedex 03 Paris (France)

    2005-07-01

    Since 1989, many experimenters worked on low-energy nuclear reactions (LENR). They face both an experimental and a theoretical dilemma: how to design simple and convincing experiments in a complex system and if the phenomenon has a nuclear origin, why do they observe no radiation. A rather simple water mass flow calorimeter was designed to study this phenomenon under different experimental conditions. First results indicate that a high-density current induced an exothermic reaction in a hydrogen processed palladium wire. A working hypothesis is presented to solve the theoretical dilemma. This working hypothesis is based on the possible existence of a still hypothetical proton/electron resonance. We underline that a working hypothesis is not a theory presented to explain the phenomenon; this is just a conceptual scheme to drive the authors to build experiments. (author)

  9. Exothermic reaction induced by high-density current in metals: Possible nuclear origin

    Dufour, J.; Murat, D.; Dufour, X.; Foos, J.

    2005-01-01

    Since 1989, many experimenters worked on low-energy nuclear reactions (LENR). They face both an experimental and a theoretical dilemma: how to design simple and convincing experiments in a complex system and if the phenomenon has a nuclear origin, why do they observe no radiation. A rather simple water mass flow calorimeter was designed to study this phenomenon under different experimental conditions. First results indicate that a high-density current induced an exothermic reaction in a hydrogen processed palladium wire. A working hypothesis is presented to solve the theoretical dilemma. This working hypothesis is based on the possible existence of a still hypothetical proton/electron resonance. We underline that a working hypothesis is not a theory presented to explain the phenomenon; this is just a conceptual scheme to drive the authors to build experiments. (author)

  10. TRADITIONAL RURAL WETLANDS IN HARYANA STATE OF INDIA ARE CURRENTLY CONFRONTING MULTICORNERED THREATS LEADING TO EXTINCTION SOONER THAN LATER

    Rohtash chand Gupta

    2012-05-01

    Full Text Available The most serious threat to traditional rural ponds in Haryana is associated with transformed societal behavioural patterns, ethics, values and life style, amongst several others. The siltation of ponds with adjoining areas, soil coming in with rain water is a very serious cause of stratification of rural ponds. Also contracting of village community land for sun drying of cow dung cakes inspires villagers to overload periphery of each pond with cow dung turning the premises into grave-yard of dung. This dung is the major source of polluting pond water into blackish water with high load of organic matter. Moreover, it leads to over excessive eutrophication. Building of major highways and connectivity roads have resulted into compartmentalization and degradation of village ponds. Inhabitation of peripheral village ponds boundaries by lower section of society for dwelling purposes is more threat to wetlands. The indifferent inclination of villagers towards silted ponds drenched in bad odour and blackish sludge is the story of 80% of the cases. The total blockage of run-off rainy water towards the natural age old rural ponds due to obstruction by way of human inhabitation has resulted into desertification of shallow water sheet in 90% of the cases. The oblivion of harvesting dried silt in summer for brick making has spelled doom for the ponds turning them into flat ground through successive decades and so on. The water quality in all ponds was overshooting the decaying stage due to the continuous mixing of cow dung drenched rainy water. Over excessive usage of ponds for bathing of cattle, dumping of cow dung and rotten vegetables waste has turned ponds into live sinks of dirt, garbage and rural dairy wastes. Majority of village ponds are now out of existence or in deep black sludge laden or converted into Fish-Farming wetlands. The present studies have indicated that Winter migratory birds like Greylag Goose Anser anser, Bar-headed Goose Anser

  11. Prediction of liquid metal alloy radiant properties from measurements of the Hall coefficient and the direct current resistivity

    Havstad, M.A.; Qiu, T.

    1995-04-01

    The thermal radiative properties of high temperature solid and liquid metal alloys are particularly useful to research and development efforts in laser cladding and machining, electron beam welding and laser isotope separation. However the cost, complexity, and difficulty of measuring these properties have forced the use of crude estimates from the Hagen-Rubens relation, the Drude relations, or extrapolation from low temperature or otherwise flawed data (e.g., oxidized). The authors have found in this work that published values for the Hall coefficient and the electrical resistivity of liquid metal alloys can provide useful estimates of the reflectance and emittance of some groups of binary liquid metal and high temperature solid alloys. The estimation method computes the Drude free electron parameters, and thence the optical constants and the radiant properties from the dependence of the Hall coefficient and direct current resistivity on alloy composition (the Hall coefficient gives the free electron density and the resistivity gives the average time between collisions). They find that predictions of the radiant properties of molten cerium-copper alloy, which use the measured variations in the Hall coefficient and resistivity (both highly nonlinear) as a function of alloy fraction (rather than linear combinations of the values of the pure elements) yield a good comparison to published measurements of the variation of the normal spectral emittance (a different but also nonlinear function) of cerium-copper alloy at the single wavelength available for comparison, 0.645 μm. The success of the approach in the visible range is particularly notable because one expects a Drude based approach to improve with increasing wavelength from the visible into the infrared. Details of the estimation method, the comparison between the calculation and the measured emittance, and a discussion of what groups of elements may also provide agreement is given

  12. Increasing phosphorus concentration in the extraradical hyphae of Rhizophagus irregularis DAOM 197198 leads to a concomitant increase in metal minerals.

    Zhang, Lin; Jiang, Caiyun; Zhou, Jiachao; Declerck, Stéphane; Tian, Changyan; Feng, Gu

    2016-11-01

    Plants associated with arbuscular mycorrhizal fungi (AMF) acquire phosphorus via roots and extraradical hyphae. How soil P level affects P accumulation within hyphae and how P in hyphae influences the accumulation of metal minerals remains little explored. A bi-compartmented in vitro cultivation system separating a root compartment (RC), containing a Ri T-DNA transformed carrot root associated to the AMF Rhizophagus irregularis DAOM 197198, from a hyphal compartment (HC), containing only the extraradical hyphae, was used. The HC contained a liquid growth medium (i.e., the modified Strullu-Romand medium containing P in the form of KH 2 PO 4 ) without (0 μM) or adjusted to 35, 100, and 700 μM of KH 2 PO 4 . The accumulation of P and metal minerals (Ca, Mg, K, Na, Fe, Cu, Mn) within extraradical hyphae and AMF-colonized roots, and the expression of the phosphate transporter gene GintPT were assessed. The expression of GintPT in the extraradical hyphae did not differ in absence of KH 2 PO 4 or in presence of 35 and 100 μM KH 2 PO 4 in the HC but was markedly reduced in presence of 700 μM KH 2 PO 4 . Hyphal P concentration was significantly lowest in absence of KH 2 PO 4 , intermediate at 35 and 100 μM KH 2 PO 4 and significantly highest in presence of 700 μM KH 2 PO 4 in the HC. The concentrations of K, Mg, and Na were positively associated with the concentration of P in the extraradical hyphae developing in the HC. Similarly, P concentration in extraradical hyphae in the HC was related to P concentration in the growth medium and influenced the concentration of K, Mg, and Na. The accumulation of the metal mineral K, Mg, and Na in the extraradical hyphae developing in the HC was possibly related to their function in neutralizing the negative charges of PolyP accumulated in the hyphae.

  13. The concentration of heavy metals: zinc, cadmium, lead, copper, mercury, iron and calcium in head hair of a randomly selected sample of Kenyan people

    Wandiga, S.O.; Jumba, I.O.

    1982-01-01

    An intercomparative analysis of the concentration of heavy metals:zinc, cadmium, lead, copper, mercury, iron and calcium in head hair of a randomly selected sample of Kenyan people using the techniques of atomic absorption spectrophotometry (AAS) and differential pulse anodic stripping voltammetry (DPAS) has been undertaken. The percent relative standard deviation for each sample analysed using either of the techniques show good sensitivity and correlation between the techniques. The DPAS was found to be slightly sensitive than the AAs instrument used. The recalculated body burden rations of Cd to Zn, Pb to Fe reveal no unusual health impairement symptoms and suggest a relatively clean environment in Kenya.(author)

  14. Assessment of Hair Aluminum, Lead, and Mercury in a Sample of Autistic Egyptian Children: Environmental Risk Factors of Heavy Metals in Autism.

    Mohamed, Farida El Baz; Zaky, Eman Ahmed; El-Sayed, Adel Bassuoni; Elhossieny, Reham Mohammed; Zahra, Sally Soliman; Salah Eldin, Waleed; Youssef, Walaa Yousef; Khaled, Rania Abdelmgeed; Youssef, Azza Mohamed

    2015-01-01

    The etiological factors involved in the etiology of autism remain elusive and controversial, but both genetic and environmental factors have been implicated. The aim of this study was to assess the levels and possible environmental risk factors and sources of exposure to mercury, lead, and aluminum in children with autism spectrum disorder (ASD) as compared to their matched controls. One hundred ASD children were studied in comparison to 100 controls. All participants were subjected to clinical evaluation and measurement of mercury, lead, and aluminum through hair analysis which reflects past exposure. The mean Levels of mercury, lead, and aluminum in hair of the autistic patients were significantly higher than controls. Mercury, lead, and aluminum levels were positively correlated with maternal fish consumptions, living nearby gasoline stations, and the usage of aluminum pans, respectively. Levels of mercury, lead, and aluminum in the hair of autistic children are higher than controls. Environmental exposure to these toxic heavy metals, at key times in development, may play a causal role in autism.

  15. Low-Cost Open-Source Voltage and Current Monitor for Gas Metal Arc Weld 3D Printing

    A. Pinar

    2015-01-01

    Full Text Available Arduino open-source microcontrollers are well known in sensor applications for scientific equipment and for controlling RepRap 3D printers. Recently low-cost open-source gas metal arc weld (GMAW RepRap 3D printers have been developed. The entry-level welders used have minimal controls and therefore lack any real-time measurement of welder voltage or current. The preliminary work on process optimization of GMAW 3D printers requires a low-cost sensor and data logger system to measure welder current and voltage. This paper reports on the development of a low-cost open-source power measurement sensor system based on Arduino architecture. The sensor system was designed, built, and tested with two entry-level MIG welders. The full bill of materials and open source designs are provided. Voltage and current were measured while making stepwise adjustments to the manual voltage setting on the welder. Three conditions were tested while welding with steel and aluminum wire on steel substrates to assess the role of electrode material, shield gas, and welding velocity. The results showed that the open source sensor circuit performed as designed and could be constructed for <$100 in components representing a significant potential value through lateral scaling and replication in the 3D printing community.

  16. Molecular dynamics simulations of metallic friction and of its dependence on electric currents - development and first results

    Meintanis, Evangelos Anastasios

    We have extended the HOLA molecular dynamics (MD) code to run slider-on-block friction experiments for Al and Cu. Both objects are allowed to evolve freely and show marked deformation despite the hardness difference. We recover realistic coefficients of friction and verify the importance of cold-welding and plastic deformations in dry sliding friction. Our first data also show a mechanism for decoupling between load and friction at high velocities. Such a mechanism can explain an increase in the coefficient of friction of metals with velocity. The study of the effects of currents on our system required the development of a suitable electrodynamic (ED) solver, as the disparity of MD and ED time scales threatened the efficiency of our code. Our first simulations combining ED and MD are presented.

  17. Identification of up-regulated genes from the metal-hyperaccumulator aquatic fern Salvinia minima Baker, in response to lead exposure.

    Leal-Alvarado, Daniel A; Martínez-Hernández, A; Calderón-Vázquez, C L; Uh-Ramos, D; Fuentes, G; Ramírez-Prado, J H; Sáenz-Carbonell, L; Santamaría, J M

    2017-12-01

    Lead (Pb) is one of the most serious environmental pollutants. The aquatic fern Salvinia minima Baker is capable to hyper-accumulate Pb in their tissues. However, the molecular mechanisms involved in its Pb accumulation and tolerance capacity are not fully understood. In order to investigate the molecular mechanisms that are activated by S. minima in response to Pb, we constructed a suppression subtractive hybridization library (SSH) in response to an exposure to 40μM of Pb(NO 3 ) 2 for 12h. 365 lead-related differentially expressed sequences tags (ESTs) were isolated and sequenced. Among these ESTs, 143 unique cDNA (97 were registered at the GenBank and 46 ESTs were not registered, because they did not meet the GenBank conditions). Those ESTs were identified and classified into 3 groups according to Blast2GO. In terms of metabolic pathways, they were grouped into 29 KEGG pathways. Among the ESTs, we identified some that might be part of the mechanism that this fern may have to deal with this metal, including abiotic-stress-related transcription factors, some that might be involved in tolerance mechanisms such as ROS scavenging, membrane protection, and those of cell homeostasis recovery. To validate the SSH library, 4 genes were randomly selected from the library and analyzed by qRT-PCR. These 4 genes were transcriptionally up-regulated in response to lead in at least one of the two tested tissues (roots and leaves). The present library is one of the few genomics approaches to study the response to metal stress in an aquatic fern, representing novel molecular information and tools to understand the molecular physiology of its Pb tolerance and hyperaccumulation capacity. Further research is required to elucidate the functions of the lead-induced genes that remain classified as unknown, to perhaps reveal novel molecular mechanisms of Pb tolerance and accumulation capacity in aquatic plants. Copyright © 2017 Elsevier B.V. All rights reserved.

  18. A study of radionuclides, metals and stable lead isotope ratios in sediments and soils in the vicinity of natural U-mineralisation areas in the Northern Territory

    Frostick, A.; Bollhoefer, A.; Parry, D.

    2011-01-01

    Australian guidelines recommend that tailings materials from uranium (U) mining and milling be contained without any detrimental impact on the environment for at least 1000 years. Natural analogue sites are being investigated to determine if they can provide data on the rates of natural erosion processes which occur over these timescales, for input into predictive geomorphic computer models. This paper presents radionuclide, metal and stable lead (Pb) isotope data from sediment cores and surface soils in the vicinity of two mineralised areas in the Alligator Rivers Region. Surface scrapes from the natural Anomaly no. 2, south of the Ranger mineral lease, exhibit radiogenic 206 Pb/ 207 Pb and 208 Pb/ 207 Pb ratios, and elevated U and metal concentrations typical for a near surface U anomaly. In contrast, samples taken from the Koongarra mineral lease (KML) show radionuclide activity and metal concentrations similar to natural areas elsewhere in the Alligator Rivers Region and Pb isotope ratios are closer to present day average crustal ratios (PDAC), as the orebodies at KML are covered by surficial sand. A sediment core collected from Anbangbang Billabong, downstream of KML, exhibits small variations in Pb isotope ratios that indicate that approximately 1% of the upper sediments in the sediment core may be derived from material originating from the U anomaly at Koongarra.

  19. A study of radionuclides, metals and stable lead isotope ratios in sediments and soils in the vicinity of natural U-mineralisation areas in the Northern Territory

    Frostick, A., E-mail: Alison.Frostick@cdu.edu.au [Charles Darwin University, School of Environment and Life Sciences, Darwin NT 0909 (Australia); ERISS, GPO Box 461, Darwin NT 0801 (Australia); Bollhoefer, A. [ERISS, GPO Box 461, Darwin NT 0801 (Australia); Parry, D. [AIMS, PO Box 41775, Casuarina NT 0811 (Australia)

    2011-10-15

    Australian guidelines recommend that tailings materials from uranium (U) mining and milling be contained without any detrimental impact on the environment for at least 1000 years. Natural analogue sites are being investigated to determine if they can provide data on the rates of natural erosion processes which occur over these timescales, for input into predictive geomorphic computer models. This paper presents radionuclide, metal and stable lead (Pb) isotope data from sediment cores and surface soils in the vicinity of two mineralised areas in the Alligator Rivers Region. Surface scrapes from the natural Anomaly no. 2, south of the Ranger mineral lease, exhibit radiogenic {sup 206}Pb/{sup 207}Pb and {sup 208}Pb/{sup 207}Pb ratios, and elevated U and metal concentrations typical for a near surface U anomaly. In contrast, samples taken from the Koongarra mineral lease (KML) show radionuclide activity and metal concentrations similar to natural areas elsewhere in the Alligator Rivers Region and Pb isotope ratios are closer to present day average crustal ratios (PDAC), as the orebodies at KML are covered by surficial sand. A sediment core collected from Anbangbang Billabong, downstream of KML, exhibits small variations in Pb isotope ratios that indicate that approximately 1% of the upper sediments in the sediment core may be derived from material originating from the U anomaly at Koongarra.

  20. Background levels of heavy metals in surficial sediments of the Gulf of Lions (NW Mediterranean): An approach based on 133Cs normalization and lead isotope measurements

    Roussiez, Vincent; Ludwig, Wolfgang; Probst, Jean-Luc; Monaco, Andre

    2005-01-01

    This paper presents an attempt to reach natural background levels of heavy metals in surficial sediments of the Gulf of Lions (NW Mediterranean). To correct for the grain-size effect, normalization procedures based on a clay mineral indicator element are commonly used, after a first grain size separation by sieving. In our study, we tested the applicability of this method with respect to commonly used normalizer elements, and found that stable Cs shows the best ability to reflect the fine sediment fraction. Background levels were successfully reached for Co, Cr, Cu, Ni and Pb, compared to various literature references. Nevertheless, in the case of lead, the normalized data depicted a general enrichment in all samples, and the natural levels could only be reached when concentrations were corrected for the atmospheric contribution by analysing lead isotope ratios. Also for Zn, a general enrichment was found in our samples, although less important. - Among several potential normalizers, stable Cs ( 133 Cs) depicted the best ability to correct for the grain-size effect of shelf sediments and was used to estimate regional background levels of heavy metals

  1. Quantitative analysis of toxic metals lead and cadmium in water jet by laser-induced breakdown spectroscopy

    Cheri, M. Sadegh; Tavassoli, S. H.

    2011-03-20

    Laser-induced breakdown spectroscopy (LIBS) has been applied to the analysis of toxic metals Pb and Cd in Pb(NO{sub 3}){sub 2} and Cd(NO{sub 3}){sub 2}.4H{sub 2}O aqueous solutions, respectively. The plasma is generated by focusing a nanosecond Nd:YAG ({lambda}=1064 nm) laser on the surface of liquid in the homemade liquid jet configuration. With an assumption of local thermodynamic equilibrium (LTE), calibration curves of Pb and Cd were obtained at different delay times between 1 to 5 {mu}s. The temporal behavior of limit of detections (LOD) was investigated and it is shown that the minimum LODs for Pb and Cd are 4 and 68 parts in 10{sup 6} (ppm), respectively. In order to demonstrate the correctness of the LTE assumption, plasma parameters including plasma temperature and electron density are evaluated, and it is shown that the LTE condition is satisfied at all delay times.

  2. Application of SIMS to the study of selective deposition of trace amounts of lead and bismuth from solution onto the metals nickel and silver

    Smith, D.; Peck, G.

    1996-01-01

    Full text: The natural 233 U decay series includes the trio 210 Pb, 210 Bi and 210 Po. These are useful in estimating rates of environmental processes and 210 Po is a major contributor to the radiation dose of marine organisms. To develop an understanding of the distribution of these closely related radionuclides in the environment it is necessary to be able to measure all three. Accurate measurements depend on preliminary separation of the nuclides. Isolation and measurement of 210 Bi has been a continuing problem and this has restricted the study of the role of this nuclide in environmental processes. We have developed a sample preparation that includes plating polonium from solution onto a silver disc then plating bismuth onto a nickel disc and leaving the lead in solution. The 210 Bi is measured by Cerenkov counting. Any 210 Pb plating onto nickel with the bismuth would interfere in subsequent counting as it decays rapidly to 210 Bi. We have used SIMS (Secondary Ion Mass Spectrometry) to measure bismuth and lead deposited on the nickel and silver discs. This is possible because the stable isotopes of the four elements do not overlap. SIMS is especially appropriate for this study as the Bi and Pb deposited as thin films on the metal surface. Careful selection of experimental conditions allowed quantitative measurements of lead and bismuth without mutual interference. The results have been used in developing plating conditions that optimise separation of lead and bismuth

  3. Stable lead isotope ratios and metals in freshwater mussels from a uranium mining environment in Australia’s wet-dry tropics

    Bollhöfer, Andreas

    2012-01-01

    Highlights: ► Lead isotope ratios in mussels from Magela more uranogenic than from Sandy catchment. ► Additional input of Broken Hill type lead further downstream of mine site. ► Lead isotope ratios in mussels ideal for source apportionment of lead into waterways. - Abstract: Concentrations of Fe, Mn, Cu, Zn, U and Pb, and stable Pb isotopes 206 Pb, 207 Pb and 208 Pb were measured via inductively coupled plasma mass spectrometry in sediments, water and freshwater mussels (Velesunio angasi) from two catchments in the Alligator Rivers Region, Australia. Sediment U and Pb concentrations were higher in Magela Creek downstream than upstream of the Ranger U mine due to the mineralised nature of the catchment and potential local input of sediment from the mine site. Water metal concentrations were highest in Georgetown Creek, which is a tributary of Magela Creek and part drains the Ranger mine site, but there was little difference in concentrations between the Magela Creek upstream and downstream sites. Metal concentrations in mussels collected immediately upstream and downstream of the mine site also showed little difference, whereas Pb isotope ratios displayed a very distinct pattern. The 206 Pb/ 207 Pb and 208 Pb/ 207 Pb isotope ratios were more uranogenic downstream than upstream of the site and also more uranogenic than ratios measured in Sandy Billabong, a reference billabong in a catchment not influenced by U mineralisation. Isotope ratios were also more uranogenic in younger mussels, potentially due to the increasing footprint of the mine site over the past decade. The most uranogenic ratios were found in mussels from Georgetown Creek and at a site approximately 2 km downstream. At Mudginberri Billabong, approximately 12 km downstream of the Ranger mine, the relative contribution of uranogenic Pb to the total Pb concentration in mussels was small and overwhelmed by the input of industrial Pb with a Broken Hill type Pb signature. Whereas metal uptake by and

  4. Electrochemistry at a Metal Nanoparticle on a Tunneling Film: A Steady-State Model of Current Densities at a Tunneling Ultramicroelectrode.

    Hill, Caleb M; Kim, Jiyeon; Bard, Allen J

    2015-09-09

    Here, a new methodology is proposed for treating electrochemical current densities in metal-insulator-metal nanoparticle (M-I-MNP) systems. The described model provides broad, practical insights about MNP-mediated electron transfer to redox species in solution, where electron transfer from the underlying electrode to a MNP via tunneling and heterogeneous electron transfer from the MNP to redox species in solution are treated as sequential steps. Tunneling is treated through an adaptation of the Simmons model of tunneling in metal-insulator-metal structures, and explicit equations are provided for tunneling currents, which demonstrate the effect of various experimental parameters, such as insulator thickness and MNP size. Overall, a general approach is demonstrated for determining experimental conditions where tunneling will have a measurable impact on the electrochemistry of M-I-MNP systems.

  5. Characteristics of drain-modulated generation current in n-type metal-oxide-semiconductor field-effect transistor

    Chen Hai-Feng; Guo Li-Xin; Zheng Pu-Yang; Dong Zhao; Zhang Qian

    2015-01-01

    Drain-modulated generation current I DMG induced by interface traps in an n-type metal-oxide-semiconductor field-effect transistor (nMOSFET) is investigated. The formation of I DMG ascribes to the change of the Si surface potential φ s . This change makes the channel suffer transformation from the inversion state, depletion I state to depletion II state. The simulation result agrees with the experiment in the inversion and depletion I states. In the depletion II state, the theoretical curve goes into saturation, while the experimental curve drops quickly as V D increases. The reason for this unconformity is that the drain-to-gate voltage V DG lessens φ s around the drain corner and controls the falling edge of the I DMG curve. The experiments of gate-modulated generation and recombination currents are also applied to verify the reasonability of the mechanism. Based on this mechanism, a theoretical model of the I DMG falling edge is set up in which I DMG has an exponential attenuation relation with V DG . Finally, the critical fitting coefficient t of the experimental curves is extracted. It is found that t = 80 mV = 3kT/q. This result fully shows the accuracy of the above mechanism. (paper)

  6. Ferroelectric and piezoelectric properties of lead-free BaTiO{sub 3} doped Bi{sub 0.5}Na{sub 0.5}TiO{sub 3} thin films from metal-organic solution deposition

    Acharya, Susant Kumar [Division of Advanced Materials Engineering, Hydrogen and Fuel Cell Research Center, Chonbuk National University, Jeonju 561-756 (Korea, Republic of); Department of Semiconductor Science and Technology, Basic Research Laboratory (BRL), Semiconductor Physics Research Center (SPRC), Chonbuk National University, Jeonju 561-756 (Korea, Republic of); Lee, Sang-Kwon; Hyung, Jung-Hwan [Department of Semiconductor Science and Technology, Basic Research Laboratory (BRL), Semiconductor Physics Research Center (SPRC), Chonbuk National University, Jeonju 561-756 (Korea, Republic of); Yang, Yun-Ho; Kim, Bok-Hee [Division of Advanced Materials Engineering, Hydrogen and Fuel Cell Research Center, Chonbuk National University, Jeonju 561-756 (Korea, Republic of); Ahn, Byung-Guk, E-mail: bkahn@jbnu.ac.kr [Division of Advanced Materials Engineering, Hydrogen and Fuel Cell Research Center, Chonbuk National University, Jeonju 561-756 (Korea, Republic of)

    2012-11-05

    Highlights: Black-Right-Pointing-Pointer Lead-free BNT-BT thin films from an optimized metal-organic solution deposition. Black-Right-Pointing-Pointer Phase and microstructure evolution with annealing temperature. Black-Right-Pointing-Pointer A relatively low leakage current density. Black-Right-Pointing-Pointer Good dielectric constant of 613 at a frequency of 1 kHz. Black-Right-Pointing-Pointer High remanent polarization and piezoelectric constant comparable to PZT thin films. - Abstract: Lead-free 0.94Bi{sub 0.5}Na{sub 0.5}TiO{sub 3}-0.06BaTiO{sub 3} (BNT-BT) piezoelectric thin films were prepared by metal-organic solution deposition onto a Pt/Ti/SiO{sub 2}/Si substrate. A dense and well crystallized thin film with a perovskite phase was obtained by annealing these films at 700 Degree-Sign C. Atomic force microscopy showed that these films were smooth and crack-free with an average grain size on the order of 200 nm. Thin films of 356 nm thickness exhibited a small signal dielectric constant and a loss tangent at 1 kHz of 613 and 0.044, respectively. Ferroelectric hysteresis measurements indicated a remanent polarization value of 21.5 {mu}C/cm{sup 2} with a coercive field of 164.5 kV/cm. The leakage current density of the thin film was 4.08 Multiplication-Sign 10{sup -4} A/cm{sup 2} at an applied electric field of 200 kV/cm. A typical butterfly-shaped piezoresponse loop was observed and the effective piezoelectric coefficient (d{sub 33}) of the BNT-BT thin film was approximately 51.6 pm/V.

  7. Effects of pH and phosphate on metal distribution with emphasis on As speciation and mobilization in soils from a lead smelting site

    Impellitteri, Christopher A. [United States Environmental Protection Agency, National Risk Management Research Laboratory, 26 West Martin Luther King Drive, Cincinnati, OH 45268 (United States)]. E-mail: Impellitteri.christopher@epa.gov

    2005-06-01

    Arsenic in soils from the Asarco lead smelter in East Helena, Montana was characterized by X-ray absorption spectroscopy (XAS). Arsenic oxidation state and geochemical speciation were analyzed as a function of depth (two sampling sites) and surface distribution. These results were compared with intensive desorption/dissolution experiments performed in a pH stat reactor for samples from the site with the highest degree of As heterogeneity. The objectives of the study were to investigate the solid-phase geochemical As speciation, assess the speciation of As in solutions equilibrated with the solids under controlled pH (pH=4 or 6) and Eh (using hydrogen or air) environments, observe the effects of phosphate on the release of As into solution, and examine the effects of phosphate on metal mobility in the systems. Arsenic was predominantly found in the As(V) valence state, though there was evidence that As(III) and As(0) were present also. The dominant geochemical phase was scorodite (FeAsO{sub 4}.2H{sub 2}O). The pH was controlled in the pH stat experiments by the addition of equinormal solutions of monoprotic (HNO{sub 3}), diprotic (H{sub 2}SO{sub 4}), or triprotic (H{sub 3}PO{sub 4}) acids. For many of the divalent metal cations, solution concentrations greatly decreased in the presence of phosphate. Solutions were also analyzed for anions. Evidence exists for sulfate release into solution. More As was released into solution at lower pH. A slight increase in solution arsenate occurs with the addition of phosphate, but the risk posed from the increased desorption/dissolution of As must be weighed against the decrease in solution concentrations of many metals especially Pb. If tailings from this site underwent acidification (e.g., acid mine drainage), in situ sequestration of metals by phosphate could be combined with placement of subsurface permeable reactive barriers for capture of As to reduce the risk associated with arsenic and trace metal mobilization. Results

  8. Effects of pH and phosphate on metal distribution with emphasis on As speciation and mobilization in soils from a lead smelting site

    Impellitteri, Christopher A.

    2005-01-01

    Arsenic in soils from the Asarco lead smelter in East Helena, Montana was characterized by X-ray absorption spectroscopy (XAS). Arsenic oxidation state and geochemical speciation were analyzed as a function of depth (two sampling sites) and surface distribution. These results were compared with intensive desorption/dissolution experiments performed in a pH stat reactor for samples from the site with the highest degree of As heterogeneity. The objectives of the study were to investigate the solid-phase geochemical As speciation, assess the speciation of As in solutions equilibrated with the solids under controlled pH (pH=4 or 6) and Eh (using hydrogen or air) environments, observe the effects of phosphate on the release of As into solution, and examine the effects of phosphate on metal mobility in the systems. Arsenic was predominantly found in the As(V) valence state, though there was evidence that As(III) and As(0) were present also. The dominant geochemical phase was scorodite (FeAsO 4 .2H 2 O). The pH was controlled in the pH stat experiments by the addition of equinormal solutions of monoprotic (HNO 3 ), diprotic (H 2 SO 4 ), or triprotic (H 3 PO 4 ) acids. For many of the divalent metal cations, solution concentrations greatly decreased in the presence of phosphate. Solutions were also analyzed for anions. Evidence exists for sulfate release into solution. More As was released into solution at lower pH. A slight increase in solution arsenate occurs with the addition of phosphate, but the risk posed from the increased desorption/dissolution of As must be weighed against the decrease in solution concentrations of many metals especially Pb. If tailings from this site underwent acidification (e.g., acid mine drainage), in situ sequestration of metals by phosphate could be combined with placement of subsurface permeable reactive barriers for capture of As to reduce the risk associated with arsenic and trace metal mobilization. Results from this study could be used

  9. Improvements in DC Current-Ioltage (I-V) Characteristics of n-GaN Schottky Diode using Metal Overlap Edge Termination

    Munir, T.; Aziz, A. A.; Abdullah, M. J.; Ain, M. F.

    2010-01-01

    Practical design of GaN Schottky diodes incorporating a field plate necessitates an understanding of how the addition of such plate affects the diode performance. In this paper, we investigated the effects on DC current-voltage (I-V) characteristics of n-GaN schottky diode by incorporating metal overlap edge termination. The thickness of the oxide film varies from 0.001 to 1 micron. Two-dimensional Atlas/Blaze simulations revealed that severe electric field crowding across the metal semiconductor contact will cause reliability concern and limit device breakdown voltage. DC current-voltage (I-V) measurements indicate that the forward currents are higher for thinner oxide film schottky diodes with metal overlap edge termination than those of unterminated schottky diodes. The forward current increased due to formation of an accumulation layer underneath the oxide layer. Extending the field plate to beyond periphery regions of schottky contact does not result in any significant increase in forward current. The new techniques of ramp oxide metal overlap edge termination have been implemented to increase the forward current of n-GaN schottky diode. In reverse bias, breakdown voltage increased with edge termination oxide up to a certain limit of oxide thickness.

  10. Quantitative assessment of metal elements using moss species as biomonitors in downwind area of lead-zinc mine.

    Balabanova, Biljana; Stafilov, Trajče; Šajn, Robert; Andonovska, Katerina Bačeva

    2017-02-23

    Distributions of a total of 21 elements were monitored in significantly lead-zinc polluted area using moss species (Hypnum cupressiforme and Camptothecium lutescens) used interchangeably, covering a denser sampling network. Interspecies comparison was conducted using Box-Cox transformed values, due to their skewed distribution. The median concentrations of trace elements in the both mosses examined decreased in the following order: Fe>Mn>Zn>Pb>Cu>Ni∼Cr∼As>Co>Cd>Hg. For almost all analyzed elements, H. cupressiforme revealed higher bio-accumulative abilities. For arsenic contents was obtained ER-value in favor of C. lutescens. The ER for the element contents according to the distance from the pollution source in selected areas was significantly enriched for the anthropogenic introduced elements As, Cd, Cu, Pb and Zn. After Box-Cox transformation of the content values, T B was significantly different for As (4.82), Cd (3.84), Cu (2.95), Pb (4.38), and Zn (4.23). Multivariate factor analysis singled out four elemental associations: F1 (Al-Co-Cr-Fe-Li-Ni-V), F2 (Cd-Pb-Zn), F3 (Ca-Mg-Na-P) and F4 (Cu) with a total variance of 89%. Spatial distribution visualized the hazardously higher contents of "hot spots" of Cd > 1.30 mg/kg, Cu > 22 mg/kg, Pb > 130 mg/kg and Zn > 160 mg/kg. Therefore, main approach in moss biomonitoring should be based on data management of the element distribution by reducing the effect of extreme values (considering Box-Cox data transformation); the interspecies variation in sampling media does not deviate in relation to H. cupressiforme vs. C. lutescens.

  11. Comparative assessment of soil contamination by lead and heavy metals in riparian and agricultural areas (southern Québec, Canada).

    Saint-Laurent, Diane; Hähni, Marlies; St-Laurent, Julien; Baril, Francis

    2010-08-01

    Soils contaminated with hydrocarbons (C(10)-C(50)), PAHS, lead and other heavy metals were recently found in the banks of two major rivers in southern Québec. Alluvial soils are contaminated over a distance of 100 kilometers. Eight sampling sites, including some located in agriculture areas (farm woodlots) have been selected to compare air pollution (aerosol fallout and rainout) and river pollution values. The concentrations detected in soil profiles for As, Cd and Pb vary between 3.01 to 37.88 mg kg(-1) (As), 0.11 to 0.81 mg kg(-1) (Cd) 12.32 to 149.13 mg kg(-1) (Pb). These metallic elements are considered highly toxic and can harm wildlife and human health at high levels. The maximum concentration of Pb (149.13 mg kg(-1)) in soils of the riparian zone is twelve times higher than the average Pb concentration found in a natural state evaluated at 15.3 mg kg(-1) (SD 17.5). Pb concentrations in soils of agricultural areas (woodland control sites) range between 12 and 22 mg kg(-1), and given that these values are recorded in surrounding cultivated land, the issue of the quality of agricultural products (crops and forage) to feed livestock or destined for human consumption must be further addressed in detail.

  12. Comparative Assessment of Soil Contamination by Lead and Heavy Metals in Riparian and Agricultural Areas (Southern Québec, Canada

    Francis Baril

    2010-08-01

    Full Text Available Soils contaminated with hydrocarbons (C10–C50, PAHS, lead and other heavy metals were recently found in the banks of two major rivers in southern Québec. Alluvial soils are contaminated over a distance of 100 kilometers. Eight sampling sites, including some located in agriculture areas (farm woodlots have been selected to compare air pollution (aerosol fallout and rainout and river pollution values. The concentrations detected in soil profiles for As, Cd and Pb vary between 3.01 to 37.88 mg kg−1 (As, 0.11 to 0.81 mg kg−1 (Cd 12.32 to 149.13 mg kg−1 (Pb. These metallic elements are considered highly toxic and can harm wildlife and human health at high levels. The maximum concentration of Pb (149.13 mg kg−1 in soils of the riparian zone is twelve times higher than the average Pb concentration found in a natural state evaluated at 15.3 mg kg−1 (SD 17.5. Pb concentrations in soils of agricultural areas (woodland control sites range between 12 and 22 mg kg−1, and given that these values are recorded in surrounding cultivated land, the issue of the quality of agricultural products (crops and forage to feed livestock or destined for human consumption must be further addressed in detail.

  13. Contents of the heavy metals nickel and lead in leaves of Paulownia elongata S.Y. Hu and Paulownia fortunei Hems. in Serbia

    Stanković Dragica

    2009-01-01

    Full Text Available A comparative study was carried out on the capabilities of the two species Paulownia elongata S. Y. Hu and Paulownia fortunei Hems. as biomonitors of atmospheric (and soil heavy-metal pollution. Research on content of the heavy metals nickel (Ni and lead (Pb in leaves of the species Paulownia elongata growing under urban and suburban conditions with the comparison to the concentration of these elements in leaves of the species Paulownia elongata and Paulownia fortunei on an experimental plot in Bela Crkva showed average nickel concentrations of 2.7 μg/g on the experimental plot in Bela Crkva, Serbia, twice as low as the concentrations measured under extreme urban conditions (6.62 μg/g, or 4.54 μg/g in the immediate vicinity of suburban traffic lines. Inasmuch as Paulownia elongata endures urban conditions well, it can be recommended for cultivation in parks, tree alleys, and wind-protection zones along urban and regional traffic lines.

  14. A Heavy Metal Atmospheric Deposition Study Around the Lead and Copper-Zinc Smelters in Baia Mare, Romania, Employing the Moss Biomonitoring Technique, ENAA and FAAS

    Culicov, O A; Steinnes, E; Okina, O S; Santa, Z; Todoran, R

    2001-01-01

    The mosses Pleurozium schreberi, Pseudoscleropodium purum and Rhytidiadelphus squarrosus were used as biomonitors to study the atmospheric deposition of metals around the lead and copper-zinc smelters in Baia Mare. Sa