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Sample records for palladium silver cadmium

  1. Fission products silver, palladium, and cadmium identification in neutron-irradiated SiC TRISO particles using a Cs-Corrected HRTEM

    NASA Astrophysics Data System (ADS)

    van Rooyen, I. J.; Olivier, E. J.; Neethling, J. H.

    2016-08-01

    Electron microscopy investigations of selected coated particles from the first advanced gas reactor experiment at Idaho National Laboratory provided important information on fission product distribution and chemical composition in the silicon-carbide (SiC) layer. Silver precipitates were nano-sized, and therefore high-resolution transmission electron microscopy (HRTEM) was used to provide more information at the atomic level. Based on gamma-ray analysis, this particle which was irradiated to an average burnup of 19.38% fissions per initial metal atom, may have released as much as 10% of its available Ag-110 m inventory during irradiation. The HRTEM investigation focused on silver, palladium, and cadmium due to interest in silver transport mechanisms and possible correlation with palladium and silver previously found. Palladium, silver, and cadmium were found to co-exist in some of the SiC grain boundaries and triple junctions. This study confirmed palladium both at inter and intragranular sites. Phosphor was identified in SiC grain boundaries and triple points.

  2. Atomistic potentials for palladium-silver hydrides

    NASA Astrophysics Data System (ADS)

    Hale, L. M.; Wong, B. M.; Zimmerman, J. A.; Zhou, X. W.

    2013-06-01

    New embedded-atom method potentials for the ternary palladium-silver-hydrogen system are developed by extending a previously developed palladium-hydrogen potential. The ternary potentials accurately capture the heat of mixing and structural properties associated with solid solution alloys of palladium-silver. Stable hydrides are produced with properties that smoothly transition across the compositions. Additions of silver to palladium are predicted to alter the properties of the hydrides by decreasing the miscibility gap and increasing the likelihood of hydrogen atoms occupying tetrahedral interstitial sites over octahedral interstitial sites.

  3. Cloud point extraction and flame atomic absorption spectrometric determination of cadmium(II), lead(II), palladium(II) and silver(I) in environmental samples.

    PubMed

    Ghaedi, Mehrorang; Shokrollahi, Ardeshir; Niknam, Khodabakhsh; Niknam, Ebrahim; Najibi, Asma; Soylak, Mustafa

    2009-09-15

    The phase-separation phenomenon of non-ionic surfactants occurring in aqueous solution was used for the extraction of cadmium(II), lead(II), palladium(II) and silver(I). The analytical procedure involved the formation of understudy metals complex with bis((1H-benzo [d] imidazol-2yl)ethyl) sulfane (BIES), and quantitatively extracted to the phase rich in octylphenoxypolyethoxyethanol (Triton X-114) after centrifugation. Methanol acidified with 1molL(-1) HNO(3) was added to the surfactant-rich phase prior to its analysis by flame atomic absorption spectrometry (FAAS). The concentration of BIES, pH and amount of surfactant (Triton X-114) was optimized. At optimum conditions, the detection limits of (3 sdb/m) of 1.4, 2.8, 1.6 and 1.4 ng mL(-1) for Cd(2+), Pb(2+), Pd(2+) and Ag(+) along with preconcentration factors of 30 and enrichment factors of 48, 39, 32 and 42 for Cd(2+), Pb(2+), Pd(2+) and Ag(+), respectively, were obtained. The proposed cloud point extraction has been successfully applied for the determination of metal ions in real samples with complicated matrix such as radiology waste, vegetable, blood and urine samples. PMID:19380196

  4. Effect of silver on the shape of palladium nanoparticles

    NASA Astrophysics Data System (ADS)

    Gupta, Dikshita; Barman, P. B.; Hazra, S. K.

    2016-05-01

    We report a facile route to prepare palladium-silver nanoparticles at considerably low temperature. First the controlled synthesis of palladium nanoparticles was performed via reduction of sodium tetrachloropalladate (II) in ethylene glycol in the presence of PVP(polyvinylpyrrolidone) as capping agent. The reaction was carried out at three different temperatures-80°C, 100°C and 120°C for one hour. Short reaction time and low synthesis temperature adds advantage to this method over others. Formed palladium nanoparticles were nearly spherical with the average particle size of 7.5±0.5 nm, 9.5±0.5 nm and 10.5±0.5 nm at 80°C, 100°C and 120°C respectively. Secondly, the palladium-silver nanoparticles were prepared by the simultaneous reduction of palladium and silver from their respective precursors in ethylene glycol at 100°C (optimized temperature). The shape and size distribution was studied by TEM (Transmission Electron Microscopy). The role of silver in transforming the shape of palladium nanoparticles from spherical to triangular has been discussed. Spherical symmetry of palladium nanoparticles is disturbed by the interaction of silver ions on the crystal facets of palladium nanoparticles. From UV-vis spectra, the absorption maxima of palladium nanoparticles at 205 nm and absorption maxima of palladium-silver nanoparticles at 272 nm revealed the partial evidence of their formation.

  5. Large silver-cadmium technology program

    NASA Technical Reports Server (NTRS)

    Charlip, S.; Lerner, S.

    1971-01-01

    The effects of varying cell design on operation factors on the electrochemical performance of sealed, silver-cadmium cells were determined. A factorial experiment was conducted for all test cells constructed with organic separators. Three operating factors were evaluated: temperature, depth of discharge, and charge rate. The six construction factors considered were separator, absorber, electrolyte quantity, cadmium electrode type, cadmium-to-silver ratio, and auxiliary electrode. Test cells of 4 ampere-hour capacity were fabricated and cycled. The best performing cells, on a 94 minute orbit, at 40% depth of discharge, were those containing silver-treated fibrous sausage casings as the separator, and Teflon-ated, pressed cadmium electrodes. Cycling data of cells with inorganic separators (Astroset) are given. Best performance was shown by cells with nonwoven nylon absorbers. Rigid inorganic separators provided the best barrier to silver migration.

  6. Silver-palladium braze alloy recovered from masking materials

    NASA Technical Reports Server (NTRS)

    Cierniak, R.; Colman, G.; De Carlo, F.

    1966-01-01

    Method for recovering powdered silver-palladium braze alloy from an acrylic spray binder and rubber masking adhesive used in spray brazing is devised. The process involves agitation and dissolution of masking materials and recovery of suspended precious metal particles on a filter.

  7. Identification of Silver and Palladium in Irradiated TRISO Coated Particles of the AGR-1 Experiment

    SciTech Connect

    van Rooyen, Y. J.; Lillo, T. M.; Wu, Y. Q.

    2014-03-01

    Evidence of the release of certain metallic fission product through intact tristructural isotropic (TRISO) particles has been seen for decades around the world, as well as in the recent AGR-1 experiment at Idaho National Laboratory (INL). However, understanding the basic mechanism of transport is still lacking. This understanding is important because the TRISO coating is part of the high temperature gas reactor functional containment and critical for the safety strategy for licensing purposes. Our approach to identify fission products in irradiated AGR-1 TRISO fuel using scanning transmission electron microscopy (STEM), Electron Energy Loss Spectroscopy (EELS) and Energy Filtered TEM (EFTEM), has led to first-of-a-kind data at the nano-scale indicating the presence of silver at triple points and grain boundaries of the SiC layer in the TRISO particle. Cadmium was also found in the triple junctions. In this initial study, the silver was only identified in SiC grain boundaries and triple points on the edge of the SiC-IPyC interface up to a depth of approximately 0.5 um. Palladium was identified as the main constituent of micron-sized precipitates present at the SiC grain boundaries. Additionally spherical nano-sized palladium rich precipitates were found inside the SiC grains. These nano-sized Pd precipitates were distributed up to a depth of 5 um away from the SiC-IPyC interlayer. No silver was found in the center of the micron-sized fission product precipitates using these techniques, although silver was found on the outer edge of one of the Pd-U-Si containing precipitates which was facing the IPyC layer. Only Pd-U containing precipitates were identified in the IPyC layer and no silver was identified in the IPyC layer. The identification of silver alongside the grain boundaries and the findings of Pd alongside grain boundaries as well as inside the grains, provide significant knowledge for understanding silver and palladium transport in TIRSO fuel, which has been

  8. Gold/palladium and silver/palladium colloids as novel metallic substrates for surface-enhanced Raman scattering.

    PubMed

    Pergolese, Barbara; Bigotto, Adriano; Muniz-Miranda, Maurizio; Sbrana, Giuseppe

    2005-02-01

    New surface-enhanced Raman scattering (SERS) substrates, composed of gold or silver colloidal nanoparticles doped with palladium, were prepared. These novel colloids are stable and maintain a satisfactory SERS efficiency, even after long aging. The interest in doping the coinage metal nanoparticles with palladium is due to the well-known catalytic activity of this metal. Transmission electron microscopy (TEM) and ultraviolet-visible absorption spectroscopy were used to characterize the shape and size of the metal particles. It was found that these bimetallic colloidal nanoparticles have a core-shell structure, with gold or silver coated with palladium clusters.

  9. Effect of recasting on the oxidation layer of a palladium-silver porcelain alloy

    SciTech Connect

    Hong, J.M.; Razzoog, M.E.; Lang, B.R.

    1988-04-01

    The oxidation zone of a commercial palladium-silver porcelain alloy was compared after repeated casting with and without the addition of new alloy. The intensity of palladium, silver, tin, indium, and O K-alpha near the oxidation zone was analyzed with XMA. The intensity curves of tin, silver, and oxygen increased progressively through each generation despite the addition of new alloy. The thickness of the oxidation zone and the microporosities at the internal oxidation zone increased through each generation without the addition of new alloy. Although the findings indicated that the oxidation zone was favorably formed by adding new alloy, 50% by weight, for four generations, the silver and metallic oxides of the oxidation zone increased through each generation. The reuse of the palladium-silver porcelain alloy remains questionable.

  10. Copper, silver, gold and zinc, cadmium, mercury oxides and hydroxides

    SciTech Connect

    Dirkse, T.P.

    1986-01-01

    This book provides a compilation of solubility data published up to 1984, including evaluations of the data. Data are presented on the following: copper (I) oxide; copper (II) oxide and hydroxide; silver (I) oxide; silver (II) oxide; gold (III) hydroxide; zinc oxide and hydroxide; cadmium oxide and hydroxide; and mercury (II) oxide.

  11. GREEN SYNTHESIS OF SILVER AND PALLADIUM NANOPARTICLES AT ROOM TEMPERATURE USING COFFEE AND TEA EXTRACT

    EPA Science Inventory

    An extremely simple green approach that generates bulk quantities of nanocrystals of noble metals such as silver (Ag) and palladium (Pd) using coffee and tea extract at room temperature is described. The single-pot method uses no surfactant, capping agent, and/or template. The ob...

  12. In situ liquid-cell electron microscopy of silver-palladium galvanic replacement reactions on silver nanoparticles.

    PubMed

    Sutter, E; Jungjohann, K; Bliznakov, S; Courty, A; Maisonhaute, E; Tenney, S; Sutter, P

    2014-09-11

    Galvanic replacement reactions provide an elegant way of transforming solid nanoparticles into complex hollow morphologies. Conventionally, galvanic replacement is studied by stopping the reaction at different stages and characterizing the products ex situ. In situ observations by liquid-cell electron microscopy can provide insight into mechanisms, rates and possible modifications of galvanic replacement reactions in the native solution environment. Here we use liquid-cell electron microscopy to investigate galvanic replacement reactions between silver nanoparticle templates and aqueous palladium salt solutions. Our in situ observations follow the transformation of the silver nanoparticles into hollow silver-palladium nanostructures. While the silver-palladium nanocages have morphologies similar to those obtained in ex situ control experiments the reaction rates are much higher, indicating that the electron beam strongly affects the galvanic-type process in the liquid-cell. By using scavengers added to the aqueous solution we identify the role of radicals generated via radiolysis by high-energy electrons in modifying galvanic reactions.

  13. In situ liquid-cell electron microscopy of silver-palladium galvanic replacement reactions on silver nanoparticles

    NASA Astrophysics Data System (ADS)

    Sutter, E.; Jungjohann, K.; Bliznakov, S.; Courty, A.; Maisonhaute, E.; Tenney, S.; Sutter, P.

    2014-09-01

    Galvanic replacement reactions provide an elegant way of transforming solid nanoparticles into complex hollow morphologies. Conventionally, galvanic replacement is studied by stopping the reaction at different stages and characterizing the products ex situ. In situ observations by liquid-cell electron microscopy can provide insight into mechanisms, rates and possible modifications of galvanic replacement reactions in the native solution environment. Here we use liquid-cell electron microscopy to investigate galvanic replacement reactions between silver nanoparticle templates and aqueous palladium salt solutions. Our in situ observations follow the transformation of the silver nanoparticles into hollow silver-palladium nanostructures. While the silver-palladium nanocages have morphologies similar to those obtained in ex situ control experiments the reaction rates are much higher, indicating that the electron beam strongly affects the galvanic-type process in the liquid-cell. By using scavengers added to the aqueous solution we identify the role of radicals generated via radiolysis by high-energy electrons in modifying galvanic reactions.

  14. Highly catalytic hollow palladium nanoparticles derived from silver@silver-palladium core-shell nanostructures for the oxidation of formic acid

    NASA Astrophysics Data System (ADS)

    Chen, Dong; Cui, Penglei; He, Hongyan; Liu, Hui; Yang, Jun

    2014-12-01

    Hollow Palladium (hPd) nanoparticles (NPs) are prepared via a simple and mild successive method. Firstly, core-shell NPs with silver (Ag) cores and silver-palladium (Ag-Pd) alloy shells are synthesized in aqueous phase by galvanic replacement reaction (GRR) between Ag NPs and Pd2+ ion precursors. Saturated aqueous sodium chloride (NaCl) solution was then employed to remove the Ag component from the core and shell regions of core-shell Ag@Ag-Pd NPs, resulting in the formation of hPd NPs with shrunk sizes in comparison with their core-shell parents. Specifically, the hPd NPs exhibit superior catalytic activity and durability for catalyzing the oxidation of formic acid, compared with the Pd NPs reduced by NaBH4 in aqueous solution and commercial Pd/C catalyst from Johnson Matthey, mainly due to the large electrochemically active surface areas of the hollow particles. In addition, The Ag component in core-shell Ag@Ag-Pd NPs has an unfavorable influence on catalytic activity of NPs for formic acid oxidation. However, the durability could be improved due to the electron donating effect from Ag to Pd atoms in the core-shell NPs.

  15. Sealed Silver-oxide Cadmium Batteries for Space Flight, 1960 - 1977

    NASA Technical Reports Server (NTRS)

    Hennigan, Thomas J.

    1978-01-01

    A technical summary of design, development, and test activities with Silver-Oxide Cadmium Batteries at the Goddard Space Flight Center since 1960 is given. The flight experience of over 15 missions has demonstrated the sealed Silver-Oxide Cadmium Battery to be a viable energy storage device for missions requiring ultra-clean magnetic environment.

  16. [Studies on the proper processing of silver-palladium casting alloys].

    PubMed

    Lenz, E; Płonka, B

    1979-01-01

    The internal structure and the hardness of three silver-palladium alloys (Sipal 306, Spall WT 52, Bego Gold-EWL G) were investigated in the as-cast condition, after homogenization and after salt-bath hardening. From the results obtained it is concluded that the optimal processing conditions for Sipal 306 and Spall WT 52 are: homogenization at 850 degrees C for more than 2 hours, and hardening at 430--450 degrees C for 15 minutes. The hardness values thus obtained meet the requirements of the type IV indication of the FDI specification no. 7; however, the inhomogenous structure causes a lower resistance to tarnish.

  17. Density functional theory metadynamics of silver, caesium and palladium diffusion at β-SiC grain boundaries

    NASA Astrophysics Data System (ADS)

    Rabone, Jeremy; López-Honorato, Eddie

    2015-03-01

    The use of silicon carbide in coated nuclear fuel particles relies on this materials impermeability towards fission products under normal operating conditions. Determining the underlying factors that control the rate at which radionuclides such as Silver-110m and Caesium-137 can cross the silicon carbide barrier layers, and at which fission products such as palladium could compromise or otherwise alter the nature of this layer, are of paramount importance for the safety of this fuel. To this end, DFT-based metadynamics simulations are applied to the atomic diffusion of silver, caesium and palladium along a Σ5 grain boundary and to palladium along a carbon-rich Σ3 grain boundary in cubic silicon carbide at 1500 K. For silver, the calculated diffusion coefficients lie in a similar range (7.04 × 10-19-3.69 × 10-17 m2 s-1) as determined experimentally. For caesium, the calculated diffusion rates are very much slower (3.91 × 10-23-2.15 × 10-21 m2 s-1) than found experimentally, suggesting a different mechanism to the simulation. Conversely, the calculated atomic diffusion of palladium is very much faster (7.96 × 10-11-7.26 × 10-9 m2 s-1) than the observed penetration rate of palladium nodules. This points to the slow dissolution and rapid regrowth of palladium nodules as a possible ingress mechanism in addition to the previously suggested migration of entire nodules along grain boundaries. The diffusion rate of palladium along the Σ3 grain boundary was calculated to be slightly slower (2.38 × 10-11-8.24 × 10-10 m2 s-1) than along the Σ5 grain boundary. Rather than diffusing along the precise plane of the boundary, the palladium atom moves through the bulk layer immediately adjacent to the boundary as there is greater freedom to move.

  18. Silver, Gold, Palladium Nanoparticles: Ligand Design, Synthesis and Polymer Composites

    NASA Astrophysics Data System (ADS)

    Iqbal, Muhammad

    least stable, although dialkyl dithiophosphates bind as bi-dentate ligands and are most stable towards cyanide etching. In contrast, dialkyl dithiophosphinates show mixed mono- and bi-dentate binding that generates loosely packed monolayers of low degree of crystallinity. Another part of this thesis (Chapter 4 and 5) employs AuNPs and silver particles as fillers to improve the electrical and thermal conductivities of polyurethane composites. High anisotropic electrical conductivity of thin composite films are obtained after curing at unprecedentedly low gold contents, which is reasoned with the coagulation of AuNPs to conductive gold networks in domains of high concentration of AuNPs. Silver particles and flakes of sizes between 20 nm and 1.5 micron were dispersed in polyurethane to investigate the effect of their size, morphology, aggregation, and dispersion on the thermal conductivity of the composites. Unexpectedly, composites filled with micron sized silver particles outperformed those filled with silver nanoparticles in thermal conductivity and stability. Finally, PdNPs were synthesized in the presence of thiolate ligands of different conical bulk (single phase surfactant free approach) to study the influence of the different ligands on their size (Chapter 6). No systematic effect was observed in contrast to a similar study on AuNPs, which is reasoned with a weaker binding of ligands to the Pd surface.

  19. Syntheses, characterization and properties of silver, copper and palladium complexes from bis(oxazoline)-containing ligands

    NASA Astrophysics Data System (ADS)

    Kuai, Hai-Wei; Cheng, Xiao-Chun; Li, Deng-Hao; Hu, Tao; Zhu, Xiao-Hong

    2015-08-01

    The reactions of 2,6-di(2-oxazolyl)pyridine (L1) and 2,6-bis[(S)-4-phenyl-2-oxazolyl]pyridine (L2) with silver, copper and palladium salts to yield six new complexes: {[Ag5(L1)5](BF4)5}n (1), {[Ag(L1)](SbF6)}n (2), [Cu4I4(L1)2] (3), [Cu6I6(L1)2] (4), [Pd(L‧1)(OAc)] (5), [Pd(L‧2)Cl] (6), which were fully characterized by single-crystal and powder X-ray diffraction, IR, elemental and thermogravimetric analyses. 1 and 2 are a pair of Ag-oxazoline helical chain structure complexes. The spiral directions of chains are opposite in 1, while identical in 2; the measurement of CD spectra can further confirm their meso and chiral structures. Complexes 3 and 4 show eight-nuclear and twelve-nuclear iodine-cuprous cluster structure. Their structural diversity is induced by different molar ratios of CuI:L1. Complexes 5 and 6 are discrete mononuclear palladium complexes. In situ oxazolyl-ring-opening reactions take place in the syntheses of them and the L1 and the L2 were transformed to their oxazolyl-ring opened derivatives L‧1 and L‧2. Moreover, fluorescence, non-linear optical properties, and ferroelectric properties have been investigated.

  20. Selective extraction of copper, mercury, silver and palladium ionsfrom water using hydrophobic ionic liquids.

    SciTech Connect

    Papaiconomou, Nicolas; Lee, Jong-Min; Salminen, Justin; VonStosch, Moritz; Prausnitz, John M.

    2007-06-25

    Extraction of dilute metal ions from water was performed near room temperature with a variety of ionic liquids. Distribution coefficients are reported for fourteen metal ions extracted with ionic liquids containing cations 1-octyl-4-methylpyridinium [4MOPYR]{sup +}, 1-methyl-1-octylpyrrolidinium [MOPYRRO]{sup +} or 1-methyl-1-octylpiperidinium [MOPIP]{sup +}, and anions tetrafluoroborate [BF{sub 4}]{sup +}, trifluoromethyl sulfonate [TfO]{sup +} or nonafluorobutyl sulfonate [NfO]{sup +}. Ionic liquids containing octylpyridinium cations are very good for extracting mercury ions. However, other metal ions were not significantly extracted by any of these ionic liquids. Extractions were also performed with four new task-specific ionic liquids. Such liquids containing a disulfide functional group are efficient and selective for mercury and copper, whereas those containing a nitrile functional group are efficient and selective for silver and palladium.

  1. Syntheses, characterization and properties of silver, copper and palladium complexes from bis(oxazoline)-containing ligands

    SciTech Connect

    Kuai, Hai-Wei Cheng, Xiao-Chun; Li, Deng-Hao; Hu, Tao; Zhu, Xiao-Hong

    2015-08-15

    The reactions of 2,6-di(2-oxazolyl)pyridine (L{sup 1}) and 2,6-bis[(S)-4-phenyl-2-oxazolyl]pyridine (L{sup 2}) with silver, copper and palladium salts to yield six new complexes: ([Ag{sub 5}(L{sup 1}){sub 5}](BF{sub 4}){sub 5}){sub n} (1), ([Ag(L{sup 1})](SbF{sub 6})){sub n} (2), [Cu{sub 4}I{sub 4}(L{sup 1}){sub 2}] (3), [Cu{sub 6}I{sub 6}(L{sup 1}){sub 2}] (4), [Pd(L′{sup 1})(OAc)] (5), [Pd(L′{sup 2})Cl] (6), which were fully characterized by single-crystal and powder X-ray diffraction, IR, elemental and thermogravimetric analyses. 1 and 2 are a pair of Ag-oxazoline helical chain structure complexes. The spiral directions of chains are opposite in 1, while identical in 2; the measurement of CD spectra can further confirm their meso and chiral structures. Complexes 3 and 4 show eight-nuclear and twelve-nuclear iodine–cuprous cluster structure. Their structural diversity is induced by different molar ratios of CuI:L{sup 1}. Complexes 5 and 6 are discrete mononuclear palladium complexes. In situ oxazolyl-ring-opening reactions take place in the syntheses of them and the L{sup 1} and the L{sup 2} were transformed to their oxazolyl-ring opened derivatives L′{sup 1} and L′{sup 2}. Moreover, fluorescence, non-linear optical properties, and ferroelectric properties have been investigated. - Graphical abstract: 2,6-di(2-oxazolyl)pyridine (L{sup 1}) reacts with silver and copper salts to yield helical and cluster structure complexes. - Highlights: • Helical and cluster structure complexes. • In situ oxazolyl-ring-opening reactions. • Fluorescence, non-linear optical properties, and ferroelectric properties.

  2. Cycle life test. Evaluation program for secondary spacecraft cells. [performance tests on silver zinc batteries, silver cadmium batteries, and nickel cadmium batteries

    NASA Technical Reports Server (NTRS)

    Harkness, J. D.

    1976-01-01

    Considerable research is being done to find more efficient and reliable means of starting electrical energy for orbiting satellites. Rechargeable cells offer one such means. A test program is described which has been established in order to further the evaluation of certain types of cells and to obtain performance and failure data as an aid to their continued improvement. The purpose of the program is to determine the cycling performance capabilities of packs of cells under different load and temperature conditions. The various kinds of cells tested were nickel-cadmium, silver-cadmium, and silver-zinc sealed cells. A summary of the results of the life cycling program is given in this report.

  3. Changes in physical and chemical properties of a dental palladium-silver alloy during metal-porcelain bonding.

    PubMed

    Payan, J; Moya, G E; Meyer, J M; Moya, F

    1986-07-01

    The hardening ability of a dental palladium-silver (Pd-Ag-Sn-In) bonding alloy has been investigated, and the distribution of the elements along the metal-ceramic interface have been studied by microprobe analysis. The alloy was found to be highly heterogeneous in its 'as-cast' condition, but homogenized alloy was obtained after heating the alloy at 1000 degrees C for 2 h. Hardening occurred after annealing at 650 degrees C for 1 h. A longer thermal treatment caused the hardness to decrease (over-ageing). The change in hardness could be attributed to an internal oxidation phenomenon. The additional elements tin and indium segregated towards the ceramic-metal interface, with a diffusion of indium only into the porcelain. Diffusion of silver in the ceramics, supposed to be the cause of the 'greening' of dental porcelains baked on silver-rich alloys, has not been detected by the microprobe across the interface. PMID:3531444

  4. Measurements of Aerosol Charge and Size Distribution for Graphite, Gold, Palladium, and Silver Nanoparticles

    SciTech Connect

    Simones, Matthew P.; Gutti, Veera R.; Meyer, Ryan M.; Loyalka, Sudarshan K.

    2011-11-01

    The role of charge on aerosol evolution and hence the nuclear source term has been an issue of interest, and there is a need for both experimental techniques and modeling for quantifying this role. Our focus here is on further exploration of a tandem differential mobility analyzer (TDMA) technique to simultaneously measure both the size and charge (positive, negative and neutral) dependent aerosol distributions. We have generated graphite, gold, silver, and palladium nanoparticles (aerosol) using a spark generator. We measure the electrical mobility-size distributions for these aerosols using a TDMA, and from these data we deduce the full charge-size distributions. We observe asymmetry in the particle size distributions for negative and positive charges. This asymmetry could have a bearing on the dynamics of charged aerosols, indicating that the assumption of symmetry for size distributions of negatively and positively charged particles in source term simulations may not be always appropriate. Also, the experimental technique should find applications in measurements of aerosol rate processes that are affected by both particle charge and size (e.g. coagulation, deposition, resuspension), and hence in modeling and simulation of the nuclear source term.

  5. Effects of Acute Exposure to Sublethal Waterborne Cadmium on Energy Homeostasis in Silver Carp (Hypophthalmichthys molitrix).

    PubMed

    Pi, Jie; Li, Xuelin; Zhang, Ting; Li, Deliang

    2016-10-01

    Effects of acute exposure to sublethal waterborne cadmium (Cd) on energy homeostasis in filter-feeding fishes have rarely been studied. The response patterns of energy substances were investigated in juvenile silver carp (Hypophthalmichthys molitrix) exposed to sublethal waterborne Cd for 96 h. The results showed the 96hLC50 of Cd on juvenile silver carp was 1.723 mg/L. Sublethal acute exposure of Cd significantly affected the energy homeostasis of juvenile silver carp, including increase in plasma glucose and lactate, and decrease in plasma triglyceride, muscle glycogen and triglyceride and liver glycogen. The results indicated that glycogen and triglyceride prior to protein were mobilized to meet the increased demands for detoxication and repair mechanism to sublethal waterborne Cd exposure, and glycogen level depleted faster and restored slower in the liver than in the white muscle in juvenile silver carp. PMID:27488982

  6. Enhancement of atomic absorption sensitivity for cadmium, manganese, nickel, and silver and determination of submicrogram quantities of cadmium and nickel in environmental samples

    SciTech Connect

    Stein, V.B.; McClellan, B.E.

    1980-07-01

    Technical report: Studied were the enhancement effects of organic solids on nickel, manganese, cadmium, and silver using atomic absorption spectrometry. Ketones and acetate esters were the solvents that gave the greatest enhancement to the metals. A method that was used to detect heavy metals in water using ketone and acetate esters as solvents is described. Results of the tests indicate that cadmium and nickel levels in the waters of Tennessee and Kentucky are low. (4 graphs, 25 references, 7 tables)

  7. Novel fluorescent silver nanoparticles: sensitive and selective turn off sensor for cadmium ions

    NASA Astrophysics Data System (ADS)

    Makwana, Bharat A.; Vyas, Disha J.; Bhatt, Keyur D.; Darji, Savan; Jain, Vinod K.

    2016-04-01

    The synthesis of metal nanoparticles by eco-friendly and reliable processes is an important aspect in many fields. In this study, octamethoxy resorcin [4] arene tetrahydrazide (OMRTH)-reduced and stabilized silver nanoparticles were synthesized via a simple one-pot method. Synthesized silver nanoparticles were characterized by UV-visible spectroscopy, transmission electron microscopy (TEM) and particle size analyzer (PSA). Furthermore, the application of OMRTH-AgNps as a simple, cost-effective and sensitive fluorescent sensor for rapid detection of cadmium was explored. Under optimum conditions, the fluorescence intensity of OMRTH-AgNps was inversely proportional to the cadmium concentration. Using OMRTH-AgNps as a selective and sensitive fluorescent probe, cadmium can be detected at a minimum concentration level of 10-8 M in a facile way of fluorescence quenching, i.e., by a "turn off" mechanism. The method has been successfully applied for determination of Cd[II] ions in groundwater and industrial effluent wastewater samples.

  8. Photon-drag in single-walled carbon nanotube and silver-palladium films: the effect of polarization

    NASA Astrophysics Data System (ADS)

    Mikheev, Konstantin G.; Saushin, Aleksandr S.; Zonov, Ruslan G.; Nasibulin, Albert G.; Mikheev, Gennady M.

    2016-03-01

    Polarization influence on the photovoltaic current raised due to the photon-drag effect in the single-walled carbon nanotube (SWNT) films and nanostructured silver-palladium (Ag/Pd) resistive films is examined at the wavelengths of 532 and 1064 nm of nanosecond laser pulses. The SWNT films were synthesized by the aerosol chemical vapor deposition technique. Ag/Pd films, consisting of AgPd alloy and palladium oxide (PdO), were prepared by burning a special paste on a ceramic substrate. The films obtained were characterized by Raman spectroscopy. It is shown that the Ag/Pd films Raman spectra consist of PdO peak that moves from 650 cm-1 to 628 cm-1 as the excitation He-Ne laser power increases. The photocurrent was measured at the oblique incidence of the laser beam on the film in the direction perpendicular to the plane of incidence. It is found that the transverse photocurrent in the SWNT films at circular polarization is absent and does not depend on the direction of the electric field vector rotation (the sign of the circular polarization) of the incident irradiation. The photocurrent in the Ag/Pd films at circular polarized irradiation is significant and depends on the circular polarization sign. The results obtained demonstrate the potential applications of the Ag/Pd resistive films as a sensor of the circular polarization sign of the incident light pulse in a wide wavelength range.

  9. Photon-drag in single-walled carbon nanotube and silver-palladium films: the effect of polarization

    NASA Astrophysics Data System (ADS)

    Mikheev, Konstantin G.; Saushin, Aleksandr S.; Zonov, Ruslan G.; Nasibulin, Albert G.; Mikheev, Gennady M.

    2016-03-01

    Polarization influence on the photovoltaic current raised due to the photon-drag effect in the single-walled carbon nanotube (SWNT) films and nanostructured silver-palladium (Ag/Pd) resistive films is examined at the wavelengths of 532 and 1064 nm of nanosecond laser pulses. The SWNT films were synthesized by the aerosol chemical vapor deposition technique. Ag/Pd films, consisting of AgPd alloy and palladium oxide (PdO), were prepared by burning a special paste on a ceramic substrate. The films obtained were characterized by Raman spectroscopy. It is shown that the Ag/Pd films Raman spectra consist of PdO peak that moves from 650 cm-1 to 628 cm-1 as the excitation He-Ne laser power increases. The photocurrent was measured at the oblique incidence of the laser beam on the film in the direction perpendicular to the plane of incidence. It is found that the transverse photocurrent in the SWNT films at circular polarization is absent and does not depend on the direction of the electric field vector rotation (the sign of the circular polarization) of the incident irradiation. The photocurrent in the Ag/Pd films at circular polarized irradiation is significant and depends on the circular polarization sign. The results obtained demonstrate the potential applications of the Ag/Pd resistive films as a sensor of the circular polarization sign of the incident light pulse in a wide wavelength range.

  10. Corrosion behavior of silver-palladium dental casting alloys in artificial saliva

    NASA Astrophysics Data System (ADS)

    Krajewski, Katherine Mary

    Ag-Pd dental casting alloys have been used as alternatives to high gold alloys in restorative dentistry since the 1980s. These alloys exhibited mechanical properties superior to gold alloys and excellent adherence to porcelain in porcelain fused to metal (PFM) restorations, such as dental crowns. However, later increases in the price of palladium along with concerns regarding possible allergic reactions and palladium's cytotoxicity have limited the use of these alloys. Evaluation of the biocompatibility concern requires a better understanding of the interaction of Ag-Pd alloys with the oral environment, and the cost problem would be lessened if the palladium content could be reduced without lowering the corrosion resistance. Previous studies have shown differences in the corrosion behavior between Pd-rich and Ag-rich alloys, but the mechanisms of the two behaviors are not well understood. The purpose of this study was to characterize the electrochemical behavior of binary Ag-Pd alloys under conditions simulating the exposure in the oral cavity. Electrochemical measurements, surface and solution analysis were performed with alloy composition, electrolyte composition, and exposure time as variables. Results showed the corrosion behavior for all alloys was governed by the formation of an insoluble thiocyanate salt combined with selective dissolution of Ag for the Pd-rich alloys. The tendency to form thiocyanate was found to dominate over the tendency to form chloride, the formation of which was suggested in other studies. The electrode behavior has been explained on the basis of the theory of behavior of electrodes of the second kind. The difference in behavior of Ag-rich and Pd-rich alloys has been related to the difference in the solubility of the salts and difference in bonding of thiocyanate with Pd and Ag.

  11. Application of the TDMA Technique Toward the Size and Charge Distribution Measurement of Graphite, Gold, Palladium, and Silver Aerosols

    NASA Astrophysics Data System (ADS)

    Simones, Matthew Paul

    The knowledge of charge distributions among aerosol particles has been an important topic for many years because of the strong electrostatic interactions which can greatly influence aerosol transport and evolution. Theoretical models have been developed although experimental verification has been limited because of the difficulty in measuring charged aerosols. Recently a method utilizing a tandem differential mobility analyzer (TDMA) has been shown to be applicable toward measuring both the size and charge distributions of nanosized combustion aerosols. The goal of this work is on further exploration of this method toward the measurement of non-combustion aerosols and in particular those associated with very high temperature reactors (VHTRs). The complete bipolar charge and size distributions of spark generated graphite, gold, silver, and palladium aerosol have been measured with a TDMA apparatus assembled and calibrated during this study. In addition, an electrostatic precipitator has been designed and constructed for measuring the size distributions of neutrally charged particles associated with these aerosols. The results show charge asymmetry in all measured aerosols with higher concentrations of positively charged particles than negative at the same charge level. These results differ from equilibrium charge distributions of both Boltzmann and Fuchs showing that charge equilibrium may not always be an appropriate assumption. The TDMA technique should find applications in characterizing VHTR aerosols and rate processes such as coagulation, deposition, and resuspension which will be important for both reactor design, and accident modeling and simulation.

  12. Direct extraction of palladium and silver from waste printed circuit boards powder by supercritical fluids oxidation-extraction process.

    PubMed

    Liu, Kang; Zhang, Zhiyuan; Zhang, Fu-Shen

    2016-11-15

    The current study was carried out to develop an environmental benign process for direct recovery of palladium (Pd) and silver (Ag) from waste printed circuit boards (PCBs) powder. The process ingeniously combined supercritical water oxidation (SCWO) and supercritical carbon dioxide (Sc-CO2) extraction techniques. SCWO treatment could effectively enrich Pd and Ag by degrading non-metallic component, and a precious metal concentrate (PMC) could be obtained, in which the enrichment factors of Pd and Ag reached 5.3 and 4.8, respectively. In the second stage, more than 93.7% Pd and 96.4% Ag could be extracted from PMC by Sc-CO2 modified with acetone and KI-I2 under optimum conditions. Mechanism study indicated that Pd and Ag extraction by Sc-CO2 was a complicated physiochemical process, involving oxidation, complexation, anion exchange, mass transfer and migration approaches. Accordingly, this study established a benign and effective process for selective recovery of dispersal precious metals from waste materials. PMID:27427888

  13. Direct extraction of palladium and silver from waste printed circuit boards powder by supercritical fluids oxidation-extraction process.

    PubMed

    Liu, Kang; Zhang, Zhiyuan; Zhang, Fu-Shen

    2016-11-15

    The current study was carried out to develop an environmental benign process for direct recovery of palladium (Pd) and silver (Ag) from waste printed circuit boards (PCBs) powder. The process ingeniously combined supercritical water oxidation (SCWO) and supercritical carbon dioxide (Sc-CO2) extraction techniques. SCWO treatment could effectively enrich Pd and Ag by degrading non-metallic component, and a precious metal concentrate (PMC) could be obtained, in which the enrichment factors of Pd and Ag reached 5.3 and 4.8, respectively. In the second stage, more than 93.7% Pd and 96.4% Ag could be extracted from PMC by Sc-CO2 modified with acetone and KI-I2 under optimum conditions. Mechanism study indicated that Pd and Ag extraction by Sc-CO2 was a complicated physiochemical process, involving oxidation, complexation, anion exchange, mass transfer and migration approaches. Accordingly, this study established a benign and effective process for selective recovery of dispersal precious metals from waste materials.

  14. Palladium-silver-activated ZnO surface: highly selective methane sensor at reasonably low operating temperature.

    PubMed

    Ghosh, Sugato; Roychaudhuri, Chirasree; Bhattacharya, Raghunath; Saha, Hiranmay; Mukherjee, Nillohit

    2014-03-26

    Metal oxide semiconductors (MOS) are well known as reducing gas sensors. However, their selectivity and operating temperature have major limitations. Most of them show cross sensitivity and the operating temperatures are also relatively higher than the value reported here. To resolve these problems, here, we report the use of palladium-silver (70-30%) activated ZnO thin films as a highly selective methane sensor at low operating temperature (∼100 °C). Porous ZnO thin films were deposited on fluorine-doped tin oxide (FTO)-coated glass substrates by galvanic technique. X-ray diffraction showed polycrystalline nature of the films, whereas the morphological analyses (field emission scanning electron microscopy) showed flake like growth of the grains mainly on xy plane with high surface roughness (107 nm). Pd-Ag (70-30%) alloy was deposited on such ZnO films by e-beam evaporation technique with three different patterns, namely, random dots, ultrathin (∼1 nm) layer and thin (∼5 nm) layer as the activation layer. ZnO films with Pd-Ag dotted pattern were found show high selectivity towards methane (with respect to H2S and CO) and sensitivity (∼80%) at a comparatively low operating temperature of about 100°C. This type of sensor was found to have higher methane selectivity in comparison to other commercially available reducing gas sensor. PMID:24564703

  15. High Temperature Strength of YSZ Joints Brazed with Palladium Silver Copper Oxide Filler Metals

    SciTech Connect

    Darsell, Jens T.; Weil, K. Scott

    2010-06-09

    The Ag-CuOx system is being investigated as potential filler metals for use in air brazing high-temperature electrochemical devices such as solid oxide fuel cells and gas concentrators. The current study examines the effects of palladium addition on the high temperature joint strength of specimens prepared from yttria stabilized zirconia (YSZ) bars brazed with the binary Ag-CuOx, and 15Pd-Ag-CuO. It was found that while the binary Ag-CuOx system exhibits stronger room temperature strength than the 15Pd system the strength is reduced to values equivalent of the 15Pd system at 800°C. The 15Pd system exhibits a lower ambient temperature strength that is retained at 800°C. In both systems the failure mechanism at high temperature appears to be peeling of the noble metal component from the oxide phases and tearing through the noble metal phase whereas sufficient adhesion is retained at lower temperatures to cause fracture of the YSZ substrate.

  16. Determination of silver, bismuth, cadmium, copper, lead, and zinc in geologic materials by atomic absorption spectrometry with tricaprylylmethylammonium chloride

    USGS Publications Warehouse

    Viets, J.G.

    1978-01-01

    Interferences commonly encountered in the determination of silver, bismuth, cadmium, copper, lead, and zinc at crustal abundance levels are effectively eliminated using a rapid, sensitive, organic extraction technique. A potassium chlorate-hydrochloric acid digestion solubilizes the metals not tightly bound in the silicate lattice of rocks, soils, and stream sediments. The six metals are selectively extracted into a 10% Aliquat 336-MIBK organic phase in the presence of ascorbic acid and potassium iodide. Metals in the organic extract are determined by flame atomic absorption spectrometry to the 0.02-ppm level for silver, cadmium, copper, and zinc and to the 0.2-ppm level for bismuth and lead with a maximum relative standard deviation of 18.8% for known reference samples. An additional hydrofluoric acid digestion may be used to determine metals substituted in the silicate lattice.

  17. Evaluation of single liquid primers with organic sulfur compound for bonding between indirect composite material and silver-palladium-copper-gold alloy.

    PubMed

    Shimoe, Saiji; Tanoue, Naomi; Satoda, Takahiro; Murayama, Takeshi; Nikawa, Hiroki; Matsumura, Hideo

    2010-01-01

    The purpose of this study was to evaluate the effect of primers on bonding between a silver-palladium-copper-gold alloy and an indirect composite material. Cast disks were air-abraded with alumina, conditioned with one of five primers (Alloy Primer, Luna-Wing Primer, Metal Primer II, Metaltite, M.L. Primer), and bonded with a light-activated indirect composite. Shear bond strengths were determined after 20,000 times of thermocycling. The results showed that four of the primers, except the Luna-Wing Primer, were effective in enhancing the bond strength as compared with the unprimed control group. Of these four primers, Alloy Primer, Metal Primer II, and M.L. Primer exhibited significantly greater bond strengths. It can be concluded that the effectiveness of primers varies considerably according to the organic sulfur compounds added to the solvent, and that care must be taken in selecting priming agents for bonding the composite material and the silver-palladium-copper-gold alloy.

  18. Low cost hydrogen/novel membranes technology for hydrogen separation from synthesis gas, Phase 1. [Palladium-silver/poly(etherimide), polysulfone/poly(dimethylsiloxane)/poly(ether-esteramide)composite membranes

    SciTech Connect

    Not Available

    1987-01-01

    During this quarter, work continued on the development of high-flux palladium-silver membranes for the separation of hydrogen from carbon dioxide. Palladium-silver/poly(etherimide) composite membranes were prepared by a vacuum sputtering technique. The influence of different poly(etherimide) support membranes on the performance of palladium-silver membranes was investigated. All membranes tested showed a hydrogen/carbon dioxide selectivity lower than that of the uncoated poly(etherimide)/poly(dimethylsiloxane) membranes. This is probably due to damage of the skin layer of the asymmetric poly(etherimide) support membranes during the palladium-silver electron bombardment. Polysulfone/poly(dimethylsiloxane)/poly(ether-ester-amide) composite membranes were also prepared. Membrane samples consistently showed a carbon dioxide/hydrogen selectivity of 9 to 10 and a normalized carbon dioxide flux of 2 to 4 {times} 10{sup {minus}4} cm{sup 3} (STP)/cm{sup 2}{center dot}sec{center dot}cmHg. These are extremely good values, superior to any commercially available membranes for this separation. 2 figs., 4 tabs.

  19. Investigating the distribution of dissolved copper, zinc, silver and cadmium in the Pacific Ocean

    NASA Astrophysics Data System (ADS)

    Janssen, D. J.; Cullen, J. T.

    2012-12-01

    A stated goal of the GEOTRACES program is to better understand the large-scale distribution of trace metals in the marine environment. A characteristic feature of the soft Lewis acid metals like copper (Cu), zinc (Zn), silver (Ag) and cadmium (Cd) is their correlation with the major algal nutrients. These correlations imply that the proximate control on the distribution of these metals is microbial uptake at the ocean surface, sinking associated with particulate organic matter and subsequent remineralization in the ocean interior. Combined with sedimentary records of past metal concentrations such correlations can provide much needed information on water mass circulation and nutrient cycling in the paleo-ocean. Today, as trace nutrients and/or toxins these metals help shape microbial community composition and influence productivity. Here we present depth profiles through the low dissolved oxygen waters of the north Pacific which show decoupling of trace metal-macronutrient relationships driven by depletion anomalies of trace metal concentrations in the broad, low oxygen layer. Similar anomalies have been previously reported in permanently anoxic layers (e.g. fjords) or in waters in contact with suboxic sediments and attributed to sulfidic removal of soft trace metals. The observed trace metal behavior and trace metal-macronutrient relationships in the oxygen minimum layer in the northeastern Pacific is consistent with the possibility of sulfidic scavenging of soft metals and the formation of insoluble metal sulfides in the water column. Implications of this influence on the basin scale distribution of soft metals like Cu, Zn, Ag, Cd through scavenging in the spreading low oxygen layer in the northeastern Pacific are discussed.

  20. Characteristics of solid-state batteries with zinc/cadmium halide-doped silver phosphate glasses as electrolytes

    NASA Astrophysics Data System (ADS)

    Das, S. S.; Baranwal, B. P.; Gupta, C. P.; Singh, Punita

    Several samples of ion-conducting silver phosphate glasses doped with zinc/cadmium halides are prepared and subjected to X-ray diffraction analysis, transference number measurement, and electrical conductivity studies. The percentage transference numbers of these glasses are found to lie between 98.3 and 99.3, which suggests that the glasses are essentially ionic conductors. The conductivity values range from 1.66×10 -2 to 8.66×10 -2 S cm -1 at 300 °C. Solid-state batteries using these glassy systems as electrolytes with the cell configurations Ag||Ag 2OP 2O 5(20%)Zn/CdX 2||(C+I 2) and Ag||Ag 2OP 2O 5(20%)Zn/CdX 2||(C+I 2+electrolyte) (where X is Cl, Br or I) have been fabricated and their discharge characteristics studied. Cells with undoped silver phosphate glasses as electrolytes have also been prepared and studied. The addition of Zn/CdX 2 to silver phosphate glass results in a substantial increase in the open-circuit voltage in the order MI 2>MBr 2>MCl 2 (where M is the dopant cation). Cells with Ag||Ag 2OP 2O 5(20%)Zn/CdI 2||(C+I 2+electrolyte) deliver the best performance.

  1. Cadmium

    Integrated Risk Information System (IRIS)

    Cadmium ; CASRN 7440 - 43 - 9 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarcinogenic Effects

  2. Determination of arsenic, antimony, bismuth, cadmium, copper, lead, molybdenum, silver and zinc in geological materials by atomic-absorption spectrometry

    USGS Publications Warehouse

    Viets, J.G.; O'Leary, R. M.; Clark, Robert J.

    1984-01-01

    Arsenic, antimony, bismuth, cadmium, copper, lead, molybdenum, silver and zinc are very useful elements in geochemical exploration. In the proposed method, geological samples are fused with potassium pyrosulphate and the fusate is dissolved in a solution of hydrochloric acid, ascorbic acid and potassium iodide. When this solution is shaken with a 10% V/V Aliquat 336 - isobutyl methyl ketone organic phase, the nine elements of interest are selectively partitioned in the organic phase. All nine elements can then be determined in the organic phase using flame atomic-absorption spectrometry. The method is rapid and allows the determination of Ag and Cd at levels down to 0.1 p.p.m., Cu, Mo, and Zn down to 0.5 p.p.m., Pb, Bi and Sb down to 1 p.p.m. and As down to 5 p.p.m. in geological materials.

  3. Localized surface plasmon and exciton interaction in silver-coated cadmium sulphide quantum dots

    SciTech Connect

    Ghosh, P.; Rustagi, K. C.; Vasa, P.; Singh, B. P.

    2015-05-15

    Localized surface plasmon and exciton coupling has been investigated on colloidal solutions of silver-coated CdS nanoparticles (NPs), synthesized by gamma irradiation. Two broad photoluminescence (PL) bands (blue/red) corresponding to band to band and defect state transitions have been observed for the bare and coated samples. In case of bare CdS NPs, the intensity of the red PL peak is about ten times higher than the blue PL peak intensity. However, on coating the CdS NPs with silver, the peak intensity of the blue PL band gets enhanced and becomes equal to that of the red PL band. High-resolution transmission electron microscopic (HRTEM) images adequately demonstrate size distribution of these metal/semiconductor nanocomposites. UV-Vis absorption studies show quantum confinement effect in these semiconductor quantum dot (SQD) systems. Absorption spectrum of silver-coated SQDs shows signature of surface plasmon-exciton coupling which has been theoretically verified.

  4. Localized surface plasmon and exciton interaction in silver-coated cadmium sulphide quantum dots

    NASA Astrophysics Data System (ADS)

    Ghosh, P.; Rustagi, K. C.; Vasa, P.; Singh, B. P.

    2015-05-01

    Localized surface plasmon and exciton coupling has been investigated on colloidal solutions of silver-coated CdS nanoparticles (NPs), synthesized by gamma irradiation. Two broad photoluminescence (PL) bands (blue/red) corresponding to band to band and defect state transitions have been observed for the bare and coated samples. In case of bare CdS NPs, the intensity of the red PL peak is about ten times higher than the blue PL peak intensity. However, on coating the CdS NPs with silver, the peak intensity of the blue PL band gets enhanced and becomes equal to that of the red PL band. High-resolution transmission electron microscopic (HRTEM) images adequately demonstrate size distribution of these metal/semiconductor nanocomposites. UV-Vis absorption studies show quantum confinement effect in these semiconductor quantum dot (SQD) systems. Absorption spectrum of silver-coated SQDs shows signature of surface plasmon-exciton coupling which has been theoretically verified.

  5. Investigation of the Distribution of Fission Products Silver, Palladium and Cadmium in Neutron Irradiated SIC using a Cs Corrected HRTEM

    SciTech Connect

    I. J. van Rooyen; E. Olivier; J. H Neethlin

    2014-10-01

    Electron microscopy examinations of selected coated particles from the first advanced gas reactor experiment (AGR-1) at Idaho National Laboratory (INL) provided important information on fission product distribution and chemical composition. Furthermore, recent research using STEM analysis led to the discovery of Ag at SiC grain boundaries and triple junctions. As these Ag precipitates were nano-sized, high resolution transmission electron microscopy (HRTEM) examination was used to provide more information at the atomic level. This paper describes some of the first HRTEM results obtained by examining a particle from Compact 4-1-1, which was irradiated to an average burnup of 19.26% fissions per initial metal atom (FIMA), a time average, volume-averaged temperature of 1072°C; a time average, peak temperature of 1182°C and an average fast fluence of 4.13 x 1021 n/cm2. Based on gamma analysis, it is estimated that this particle may have released as much as 10% of its available Ag-110m inventory during irradiation. The HRTEM investigation focused on Ag, Pd, Cd and U due to the interest in Ag transport mechanisms and possible correlation with Pd, Ag and U previously found. Additionally, Compact 4-1-1 contains fuel particles fabricated with a different fuel carrier gas composition and lower deposition temperatures for the SiC layer relative to the Baseline fabrication conditions, which are expected to reduce the concentration of SiC defects resulting from uranium dispersion. Pd, Ag, and Cd were found to co-exist in some of the SiC grain boundaries and triple junctions whilst U was found to be present in the micron-sized precipitates as well as separately in selected areas at grain boundaries. This study confirmed the presence of Pd both at inter- and intragranular positions; in the latter case specifically at stacking faults. Small Pd nodules were observed at a distance of about 6.5 micron from the inner PyC/SiC interface.

  6. The isotopic composition of zinc, palladium, silver, cadmium, tin, and tellurium in acid-etched residues of the Allende meteorite

    SciTech Connect

    Loss, R.D.; Rosman, K.J.R.; De Laeter, J.R. )

    1990-12-01

    The isotopic and elemental abundances of Zn, Pd, Ag, Cd, Sn, and Te have been measured in three acid-resistant residues extracted from the Allende meteorite. High-efficiency, low-contamination ion-exchange procedures were developed to separate and purify the nanogram amounts of these elements present. Elemental-abundance determinations performed by Mass Spectrometric Isotope Dilution agree with previously published work for similarly derived residues. No isotope anomalies similar to those found for Xe (Xe-HL) in these samples were detected for any of these elements, which is consistent with the residues not being derived directly from the Xe-HL carriers. The lack of major Te-isotope anomalies does not support earlier reports of {sup 126}Te and {sup 130}Te excesses which were measured by neutron activation in similar samples. Small excesses were detected in the minor isotopes of Sn and Te, but these may be due to measurement problems associated with the small ion currents obtained for these samples. Two of the residue solutions contain Cd with up to several percent excesses for {sup 106}Cd and {sup 108}Cd. Interpretations of these results are limited by the unknown nature of the carrier minerals in the residues but may indicate the presence of a p-process component in Allende residues.

  7. Effects of solvent, pH, salts and resin fatty acids on the dechlorination of pentachlorophenol using magnesium-silver and magnesium-palladium bimetallic systems.

    PubMed

    Patel, Upendra D; Suresh, Sumathi

    2008-08-15

    The effects of pH, organic co-solvent, salts such as sodium chloride, sodium sulfate, and co-pollutants, resin and fatty acids (RFAs) on the dechlorination of pentachlorophenol (PCP) by magnesium/silver (Mg/Ag) and magnesium/palladium (Mg/Pd) systems were examined in the present investigations. Such studies provide relevant information about the applicability of bimetallic systems for remediation of raw wastewaters (such as pulp bleaching effluents) or groundwater. Removal efficiencies of 10 mg L(-1) PCP by Mg/Pd and Mg/Ag systems at the end of 1 h reaction were 93% and 78%, respectively, in the presence of acetone (1% v/v). On the other hand, the removal efficiencies were 86% and 70% for reactions conducted in alcoholic solvents (1% v/v) using Mg/Pd and Mg/Ag systems, respectively. The efficiencies of PCP removal by the two bimetallic systems could be correlated to the dipole moments of co-solvents used. The second order reaction rate constant for PCP removal by Mg/Ag system was highest (0.03 L mg(-1) min(-1)) in the absence of any pH-control mechanism. Optimum pH for the dechlorination of PCP by Mg/Pd system was found to be approximately 5.5 and >92% of the compound was removed within 15 min of reaction. Presence of chlorinated and non-chlorinated resin fatty acids (RFAs) resulted in substantial reduction in the rate and extent of PCP removal by Mg/Ag system whereas dechlorination by Mg/Pd remained unaffected. Presence of sodium sulfate or sodium chloride in the reaction phase reduced the rate and extent of PCP removal by Mg/Ag system. PCP dechlorination by Mg/Pd system was adversely impacted by the addition of sodium chloride and unaffected by the presence of sodium sulfate.

  8. Silver

    Integrated Risk Information System (IRIS)

    Silver ; CASRN 7440 - 22 - 4 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarcinogenic Effects )

  9. Heteroaggregation assisted wet synthesis of core-shell silver-silica-cadmium selenide nanowires

    NASA Astrophysics Data System (ADS)

    Pita, Isabel A.; Singh, Shalini; Silien, Christophe; Ryan, Kevin M.; Liu, Ning

    2015-12-01

    A method has been developed for the wet solution synthesis of core shell heterogeneous nanowires. An ultrathin silica layer was first grown around plain silver nanowires to act as a suitable insulator. An outer nanoparticle layer was then attached through heteroaggregation by dispersing the un-functionalized nanowires in toluene solutions containing nanoparticles of CdSe or Au. Total coverage of nanoparticles on nanowires was found to increase with the nanoparticle size, which is attributed to the increase in the van der Waals interaction between the nanoparticles and the nanowire with the increasing size of nanoparticles. Using this method, we achieved over 79.5% coverage of CdSe nanoparticles (24 nm × 11 nm) on the nanowire surface. Although following the same trend, Au nanoparticles show an overall lower coverage than CdSe, with only 24.2% coverage at their largest particle size of 19 nm in diameter. This result is attributed to the increase in steric repulsion during attachment due to the increasing length of capping ligands. Investigation of the core-shell nanowire's optical properties yielded CdSe Raman peak enhancement by a factor of 2-3 due to the excitation of surface plasmon propagation. Our method can be applied to the attachment of a wide range of nanoparticles to nanowire materials in non-polar solution and the core-shell nanowires show great potential for incorporation into various microscopic and drug delivery applications.A method has been developed for the wet solution synthesis of core shell heterogeneous nanowires. An ultrathin silica layer was first grown around plain silver nanowires to act as a suitable insulator. An outer nanoparticle layer was then attached through heteroaggregation by dispersing the un-functionalized nanowires in toluene solutions containing nanoparticles of CdSe or Au. Total coverage of nanoparticles on nanowires was found to increase with the nanoparticle size, which is attributed to the increase in the van der Waals

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

    PubMed

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

    2003-03-01

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

  11. Hydrosilane and bismuth-accelerated palladium catalyzed aerobic oxidative esterification of benzylic alcohols with air.

    PubMed

    Bai, Xing-Feng; Ye, Fei; Zheng, Long-Sheng; Lai, Guo-Qiao; Xia, Chun-Gu; Xu, Li-Wen

    2012-09-01

    In a palladium-catalyzed oxidative esterification, hydrosilane can serve as an activator of palladium catalyst with bismuth, thus leading to a novel ligand- and silver-free palladium catalyst system for facile oxidative esterification of a variety of benzylic alcohols in good yields.

  12. Hydrosilane and bismuth-accelerated palladium catalyzed aerobic oxidative esterification of benzylic alcohols with air.

    PubMed

    Bai, Xing-Feng; Ye, Fei; Zheng, Long-Sheng; Lai, Guo-Qiao; Xia, Chun-Gu; Xu, Li-Wen

    2012-09-01

    In a palladium-catalyzed oxidative esterification, hydrosilane can serve as an activator of palladium catalyst with bismuth, thus leading to a novel ligand- and silver-free palladium catalyst system for facile oxidative esterification of a variety of benzylic alcohols in good yields. PMID:22814568

  13. To study the effect of doping concentration of silver on structural and optical properties of cadmium oxide (CdO) nanostructure

    NASA Astrophysics Data System (ADS)

    Kumar, Rajesh; Sharma, Ashwani; Parmar, R.; Dahiya, S.; Kishor, N.

    2016-05-01

    The present work deals with study of structural and optical properties of Silver (Ag) doped Cadmium oxide (CdO) nanostructured synthesized by Chemical Co-precipitation Techniques followed by calcinations at small temperature. The doping concentrations were changing from 0.1 to 10 at% respectively. Structural analysis study of these calcined materials is carried out by X-ray diffraction (XRD), Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy(TEM). The optical properties of calcined samples were investigating by Fourier transformation infrared (FTIR)spectroscopy, UV-Visible Spectroscopy (UV-Vis). The structural properties analysis results revels that crystallite size are in the range of nano region and TEM results are quite in accordance with XRD results.

  14. On the corrosion behavior and biocompatibility of palladium-based dental alloys

    NASA Astrophysics Data System (ADS)

    Sun, Desheng

    Palladium-based alloys have been used as dental restorative materials for about two decades with good clinical history. But there have been clinical case reports showing possible allergy effects from these alloys. The aim of this study was to characterize the corrosion behavior and mechanisms of several palladium-based dental alloys by potentiodynamic polarization methods, electrochemical impedance spectroscopy (EIS), and scanning Kelvin probe force microscopy/atomic force microscopy (SKPFM/AFM), and to evaluate their biocompatibility by a cell culture technique and an animal model. Using SKPFM/AFM and scanning electron microscopy, the Ru-enriched phase from the use of ruthenium as a grain-refining element was identified as being slightly more noble than the palladium solid solution matrix in a high-palladium alloy. Other secondary precipitates that exist in the microstructures of these high-palladium alloys have minimal differences in Volta potential compared to the matrix. For high-palladium alloys, corrosion is generally uniform due to the predominant palladium content in the different phases. Potentiodynamic polarization and EIS have shown that representative palladium-silver alloys have low corrosion tendency and high corrosion resistance, which are equivalent to a well-known high-noble gold-palladium alloy in simulated body fluid and oral environments. The palladium-silver alloys tested are resistant to chloride ion corrosion. Passivation and dealloying have been identified for all of the tested palladium-silver alloys. The great similarity in corrosion behavior among the palladium-silver alloys is attributed to their similar chemical compositions. The variation in microstructures of palladium-silver alloys tested does not cause significant difference in corrosion behavior. The corrosion resistance of these palladium-silver alloys at elevated potentials relevant to oral environment is still satisfactory. The release of elements from representative dental

  15. Effect of pre-exposure to cadmium and silver on nickel induced toxic manifestations in mice: Possible role of ceruloplasmin and metallothionein

    SciTech Connect

    Srivastava, R.C.; Husain, M.M.; Srivastava, S.K.; Hasan, S.K.; Lai, A.

    1995-05-01

    Recent studies from our laboratory and elsewhere have provided strong evidence for the involvement of reactive oxygen species (ROS) in nickel (Ni) toxicity. The toxic manifestations of Ni are further evident from animal studies where it caused significant depletion in serum ceruloplasmin (CP) activity. CP has been implicated in a variety of crucially important cellular functions including its role in the protection against oxidative damage and as a carrier for the transport of essential metals. Since there is a lack of information about its role in Ni toxicity, an attempt was made to evaluate its implication(s) during Ni exposure. Administration of cadmium chloride (CdCl{sub 2}) or silver nitrate (AgNO{sub 3}) in mice respectively enhance or deplete the activity of serum SP. Besides, both the salts induce metallothioneins (MT), which also serve as an efficient scavenger of ROS. We therefore, studied the effect of Cd and Ag under various predisposing conditions on the protection against Ni-mediated toxic manifestations by evaluating (i) hepatic lipid peroxidation (ii) Ni content in target tissues and (iii) mortality in mice. Our results demonstrate that Cd pretreatment(s) provided significant protection against Ni-mediated toxic responses and reflect the possible interplay of the induced levels of CP and MT. 19 refs., 2 figs., 2 tabs.

  16. Improving the efficiency of cadmium sulfide-sensitized titanium dioxide/indium tin oxide glass photoelectrodes using silver sulfide as an energy barrier layer and a light absorber

    PubMed Central

    2014-01-01

    Cadmium sulfide (CdS) and silver sulfide (Ag2S) nanocrystals are deposited on the titanium dioxide (TiO2) nanocrystalline film on indium tin oxide (ITO) substrate to prepare CdS/Ag2S/TiO2/ITO photoelectrodes through a new method known as the molecular precursor decomposition method. The Ag2S is interposed between the TiO2 nanocrystal film and CdS nanocrystals as an energy barrier layer and a light absorber. As a consequence, the energy conversion efficiency of the CdS/Ag2S/TiO2/ITO electrodes is significantly improved. Under AM 1.5 G sunlight irradiation, the maximum efficiency achieved for the CdS(4)/Ag2S/TiO2/ITO electrode is 3.46%, corresponding to an increase of about 150% as compared to the CdS(4)/TiO2/ITO electrode without the Ag2S layer. Our experimental results show that the improved efficiency is mainly due to the formation of Ag2S layer that may increase the light absorbance and reduce the recombination of photogenerated electrons with redox ions from the electrolyte. PMID:25411566

  17. Determination of lead, cadmium, indium, thallium and silver in ancient ices from Antarctica by isotope dilution-thermal ionization mass spectrometry

    USGS Publications Warehouse

    Matsumoto, A.; Hinkley, T.K.

    1997-01-01

    The concentrations of five chalcophile elements (Pb, Cd, In, Tl and Ag) and the lead isotope rarios in ancient ices from the Taylor Dome near coastal Antarctica, have been determined by the isotope dilutionthermal ionization mass spectrometry (ID-TIMS), with ultra-clean laboratory techniques. The samples were selected from segments of cores, one of which included a visible ash layer. Electric conductivity measurement (ECM) or dielectric properties (DEP) gave distinctive sharp peaks for some of the samples c hosen. Exterior portions of the sample segments were trimmed away by methods described here. Samples w ere evaporated to dryness and later separated into fractions for the five elements using an HBr-HNO3 a nion exchange column method. The concentrations are in the range 2.62-36.7 pg Pb/g of ice, 0.413-2.83 pg Cd/g, 0.081-0.34 pg In/g, 0.096-2.8 pg Tl/g and 0.15-0.84 pg Ag/g. respectively. The dispersions in duplicate analyses are about ??1% for lead and cadmium, ??2% for indium. ??4% for thallium and ??6% for silver, respectively. The concentrations of lead obtained are commonly higher than those in the present-day Antarctic surface snows, but the isotope ratios are distinctively higher than those of the present-day snows and close to those of the other ancient ice collected from a different Antarctic area.

  18. Different behavior of Staphylococcus epidermidis in intracellular biosynthesis of silver and cadmium sulfide nanoparticles: more stability and lower toxicity of extracted nanoparticles.

    PubMed

    Rezvani Amin, Zohreh; Khashyarmanesh, Zahra; Fazly Bazzaz, Bibi Sedigheh

    2016-09-01

    Chemical reagents that are used for synthesis of nanoparticles are often toxic, while biological reagents are safer and cost-effective. Here, the behavior of Staphylococcus epidermidis (ATCC 12228) was evaluated for biosynthesis of silver nanoparticles (Ag-NPs) and cadmium sulfide nanoparticles (CdS-NPs) using TEM images intra- and extracellularly. The bacteria only biosynthesized the nanoparticles intracellularly and distributed Ag-NPs throughout the cytoplasm and on outside surface of cell walls, while CdS-NPs only formed in cytoplasm near the cell wall. A new method for purification of the nanoparticles was used. TEM images of pure CdS-NPs confirmed biosynthesis of agglomerated nanoparticles. Biosynthetic Ag-NPs were more stable against bright light and aggregation reaction than synthetic Ag-NPs (prepared chemically) also biosynthetic Ag-NPs displayed lower toxicity in in vitro assays. CdS-NPs indicated no toxicity in in vitro assays. Biosynthetic nanoparticles as product of the detoxification pathway may be safer and more stable for biosensors. PMID:27430507

  19. Palladium contamination in silicon

    NASA Astrophysics Data System (ADS)

    Polignano, M. L.; Mica, I.; Ceresoli, M.; Codegoni, D.; Somaini, F.; Bianchi, I.; Volonghi, D.

    2015-04-01

    In this work palladium is characterized as a silicon contaminant by recombination lifetime, DLTS, C-V and C-t measurements of palladium-implanted wafers. Palladium introduced by ion implantation is found to remain in the solid solution in silicon after rapid thermal treatments, and to be a very effective recombination center. For this reason recombination lifetime measurements are the most sensitive method to detect palladium in silicon. Two palladium-related levels were found by DLTS in p-type material. One of these levels corresponds to a level reported in the literature as the single donor level of substitutional palladium. For what concerns MOS capacitors, palladium is responsible for negative oxide charge and for degradation of the generation lifetime. In addition, palladium is confirmed to be a very fast diffuser, which segregates at the wafer surface even with low temperature treatments (250 °C). Microscopy inspections showed that palladium precipitates and surface defects were formed upon segregation.

  20. Effects of palladium addition on properties of dental amalgams.

    PubMed

    Chung, K

    1992-05-01

    Palladium-containing amalgam alloys were developed utilizing the atomization method. Single-compositional type alloys were fabricated and palladium was substituted for silver in concentrations up to 5 w/o. Alloy powder with a particle size of less than 45 microns was collected and triturated with mercury. Creep, compressive strength and dimensional change tests were performed according to ADA Specification No. 1 along with controls of Tytin, Valiant and Valiant-Ph.D. Values for creep decreased and compressive strength increased markedly with additions of palladium. Current densities of the experimental amalgams containing palladium were determined to be an order of magnitude less than the original amalgams in the electrochemical test. A trend of positive relationships between properties and palladium additions was indicated.

  1. Functionalization of multiwalled carbon nanotubes for the solid-phase extraction of silver, cadmium, palladium, zinc, manganese and copper by flame atomic absorption spectrometry.

    PubMed

    Ghaedi, Mehrorang; Montazerozohori, M; Nazari, E; Nejabat, R

    2013-07-01

    In the present work, multiwalled carbon nanotube (MWCNT) chemically modified with (3-mercaptopropyl) silanetriolate is efficiently used for the solid-phase extraction of Cu(2+), Ag(+), Cd(2+), Pb(2+), Zn(2+) and Mn(2+) ions prior to their flame atomic absorption spectrometric determination. The influences of the various analytical parameters, including pH, amounts of solid phase, sample volume and eluent conditions and so on, on the recoveries of target analytes were investigated and optimized by one at a time optimization method. The influences of alkaline, alkaline earth and some transition metals on the adsorption and elution of the analytes were also examined. The detection limits for all understudied metal ions were between 1.4 and 2.8 ng mL(-1) (3Sb, n = 10). The evaluation of the thermodynamic parameters such as enthalpy (positive value), Gibbs free energy (negative value) in addition to high value of entropy shows the endothermic and spontaneous nature of sorption process. Following the optimization of variables, the adsorption process follows the intraparticle kinetic model with R (2) of 0.98 and the Langmuir isotherm with high correlation coefficient (R (2) > 0.95). The procedure was applied for the analytes determination in the food samples with satisfactory results (recoveries >95% and relative standard deviation's (RSD) lower than 4%).

  2. Palladium-catalyzed direct coupling of 2-vinylanilines and isocyanides: an efficient synthesis of 2-aminoquinolines.

    PubMed

    Wang, Lijie; Ferguson, Jamie; Zeng, Fanlong

    2015-12-21

    Palladium-catalyzed oxidative coupling of 2-vinylanilines and isocyanides constitutes a direct, facile, and efficient approach to 2-aminoquinolines. The procedure, employing palladium acetate and silver carbonate, is attractive in terms of assembly efficiency, functional group tolerance, and operational simplicity. A variety of 2-aminoquinolines were prepared in good to excellent yields. PMID:26455948

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

    PubMed

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

    2014-05-15

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

  4. Effect of palladium on sulfide tarnishing of noble metal alloys.

    PubMed

    Suoninen, E; Herø, H; Minni, E

    1985-10-01

    Electron spectroscopic studies of Au-Ag-Cu alloys of the type used for dental castings show that small additions (less than or equal to 3 wt%) of palladium reduce essentially the thickness of the sulfide layer formed on surfaces of samples treated in aqueous Na2S solutions. Relative to silver, palladium does not enrich in the sulfide, but statistically significant enrichment is found immediately below the sulfide layer. This enrichment probably takes place during the exposure of the substrate surface to atmosphere before the sulfiding treatment. The mechanism of the impeding effect of palladium on sulfiding is assumed to be a decrease in diffusion from the bulk alloy to the surface due to the enriched layer. The effect cannot be explained by changes in the electronic structure of the alloy due to palladium alloying.

  5. Glass frits coated with silver nanoparticles for silicon solar cells

    NASA Astrophysics Data System (ADS)

    Li, Yingfen; Gan, Weiping; Zhou, Jian; Li, Biyuan

    2015-06-01

    Glass frits coated with silver nanoparticles were prepared by electroless plating. Gum Arabic (GA) was used as the activating agent of glass frits without the assistance of stannous chloride or palladium chloride. The silver-coated glass frits prepared with different GA dosages were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and thermogravimetric analysis (TGA). The characterization results indicated that silver-coated glass frits had the structures of both glass and silver. Spherical silver nanoparticles were distributed on the glass frits evenly. The density and particle size of silver nanoparticles on the glass frits can be controlled by adjusting the GA dosage. The silver-coated glass frits were applied to silver pastes to act as both the densification promoter and silver crystallite formation aid in the silver electrodes. The prepared silver-coated glass frits can improve the photovoltaic performances of solar cells.

  6. Determination of palladium and platinum by atomic absorption

    USGS Publications Warehouse

    Schnepfe, M.M.; Grimaldi, F.S.

    1969-01-01

    Palladium and platinum are determined by atomic absorption after fire-assay concentration into a gold bead. The limit of determination is ~0??06 ppm in a 20-g sample. Serious depressive interelement interferences are removed by buffering the solutions with a mixture of cadmium and copper sulphates with cadmium and copper concentrations each at 0??5%. Substantial amounts of Ag, Al, Au, Bi, Ca, Co, Cr, Fe, Hg, K, La, Mg, Mn, Mo, Na, Ni, Pb, Te, Ti, V, Y, Zn, and the platinum metals do not interfere in the atomic-absorption determination. ?? 1969.

  7. Process for preparing improved silvered glass mirrors

    DOEpatents

    Buckwalter, C.Q. Jr.

    1980-01-28

    Glass mirrors having improved weathering properties are prepared by an improvement in the process for making the mirrors. The glass surface after it has been cleaned but before it is silvered, is contacted with a solution of lanthanide rare earths in addition to a sensitization solution of tin or palladium. The addition of the rare earths produces a mirror which has increased resistance to delamination of the silver from the glass surface in the presence of water.

  8. Process for preparing improved silvered glass mirrors

    DOEpatents

    Buckwalter, Jr., Charles Q.

    1981-01-01

    Glass mirrors having improved weathering properties are prepared by an improvement in the process for making the mirrors. The glass surface after it has been cleaned but before it is silvered, is contacted with a solution of lanthanide rare earths in addition to a sensitization solution of tin or palladium. The addition of the rare earths produces a mirror which has increased resistance to delamination of the silver from the glass surface in the presence of water.

  9. MONTANA PALLADIUM RESEARCH INITIATIVE

    SciTech Connect

    Peters, John; McCloskey, Jay; Douglas, Trevor; Young, Mark; Snyder, Stuart; Gurney, Brian

    2012-05-09

    Project Objective: The overarching objective of the Montana Palladium Research Initiative is to perform scientific research on the properties and uses of palladium in the context of the U.S. Department of Energy's Hydrogen, Fuel Cells and Infrastructure Technologies Program. The purpose of the research will be to explore possible palladium as an alternative to platinum in hydrogen-economy applications. To achieve this objective, the Initiatives activities will focus on several cutting-edge research approaches across a range of disciplines, including metallurgy, biomimetics, instrumentation development, and systems analysis. Background: Platinum-group elements (PGEs) play significant roles in processing hydrogen, an element that shows high potential to address this need in the U.S. and the world for inexpensive, reliable, clean energy. Platinum, however, is a very expensive component of current and planned systems, so less-expensive alternatives that have similar physical properties are being sought. To this end, several tasks have been defined under the rubric of the Montana Palladium Research Iniative. This broad swath of activities will allow progress on several fronts. The membrane-related activities of Task 1 employs state-of-the-art and leading-edge technologies to develop new, ceramic-substrate metallic membranes for the production of high-purity hydrogen, and develop techniques for the production of thin, defect-free platinum group element catalytic membranes for energy production and pollution control. The biomimetic work in Task 2 explores the use of substrate-attached hydrogen-producing enzymes and the encapsulation of palladium in virion-based protein coats to determine their utility for distributed hydrogen production. Task 3 work involves developing laser-induced breakdown spectroscopy (LIBS) as a real-time, in situ diagnostic technique to characterize PGEs nanoparticles for process monitoring and control. The systems engineering work in task 4 will

  10. Palladium-catalyzed dehydrogenative coupling of terminal alkynes with secondary phosphine oxides.

    PubMed

    Yang, Jia; Chen, Tieqiao; Zhou, Yongbo; Yin, Shuangfeng; Han, Li-Biao

    2015-02-28

    The dehydrogenative coupling of terminal alkynes with secondary phosphine oxides is developed. In the presence of a silver additive, palladium acetate could efficiently catalyze the dehydrocoupling of secondary phosphine oxides with a variety of terminal alkynes to produce the corresponding alkynylphosphine oxides in high yields. A reaction mechanism is proposed. PMID:25627893

  11. Atmospheric deposition of silver and thallium since 12 370 14C years BP recorded by a Swiss peat bog profile, and comparison with lead and cadmium.

    PubMed

    Shotyk, William; Krachler, Michael

    2004-05-01

    A peat core from an ombrotrophic bog in Switzerland provides the first complete, long-term record (14 500 years) of atmospheric Ag and Tl deposition. The lack of enrichment of Ag and Tl in the basal peat layer shows that mineral dissolution in the underlying sediments has not contributed measurably to the Ag and Tl inventories in the peat column, and that Ag and Tl were supplied exclusively by atmospheric deposition. The temporal and spatial distribution of modern peaks in Ag and Tl concentrations are similar to those of Pb which is known to be immobile in peat profiles. Silver and Tl, therefore, are effectively immobile in the peat bog also, allowing an atmospheric deposition chronology to be reconstructed. Silver concentrations vary by up to 114x and Tl up to 241x. While Holocene climate change and land use history can explain the variation in metal concentrations and enrichment factors (EF) in ancient peats (i.e. pre-dating the Roman Period), anthropogenic sources have to be invoked to explain the very high EF values (up to 123 in the case of Ag and 12 in the case of Tl) in peat samples since the middle of the 19th Century. The "natural background" EF of Tl in ancient peats is remarkably close to unity, indicating a lack of significant enrichment of this element in atmospheric aerosols due to chemical weathering of crustal rocks. Silver, on the other hand, shows a pronounced enrichment from 8030 to 5230 (14)C years BP (12x compared to crustal rocks); this may be due to weathering phenomena or biological processes, both of which are driven by climate. Even compared to the natural enrichment of Ag during the mid-Holocene, however, the enrichments of Ag and Tl in modern peats from the Industrial Period are at least an order of magnitude greater. The Pb/Ag and Tl/Ag ratios show that Pb and Tl are preferentially released, compared to Ag, during smelting of argentiferous Pb ores mined during the Roman and Medieval Periods.

  12. Silver Sulfadiazine

    MedlinePlus

    Silver sulfadiazine, a sulfa drug, is used to prevent and treat infections of second- and third-degree ... Silver sulfadiazine comes in a cream. Silver sulfadiazine usually is applied once or twice a day. Follow ...

  13. Development of palladium nanowires

    NASA Astrophysics Data System (ADS)

    Cheng, Chuanding

    Inherent limitations of traditional lithography have prompted the search for means of achieving self-assembly of nano-scale structures and networks for the next generation of electronic and photonic devices. The nanowire, the basic building block of a nanocircuit, has recently become the focus of intense research. Reports on nanowire synthesis and assembly have appeared in the scientific literature, which include Vapor-Liquid-Solid mechanism, template-based electrochemical fabrication, solvothermal or wet chemistry, and assembly by fluid alignment or microchannel networks. An ideal approach for practical application of nanowires would circumvent technical and economic constraints of templating. Here we report on the self-assembly of highly-ordered metallic nanowires directly from a palladium acetate solution under an applied alternating current (AC) electric field of relatively high intensity and frequency. DNA-templated nanowires are first presented here. DNA molecules were stretched and positioned by electric field, followed by metallization by palladium acetate solution. Palladium nanowire arrays have been found to grow directly between microelectrodes without any template, under an alternating electric field of relatively high intensity and frequency. The wires grew spontaneously along the direction of the electric field and have high uniformity and conductivity. Single 75 nm-diameter palladium nanowires have also been self-assembled from aqueous solution at predefined locations between 15 mum-gap electrodes built on a SiO2 substrate. Nanowire assembly was initiated by application an electric field, and it occurred only along the direction of field lines where the field is strongest. Related metals did not support single nanowire assembly under comparable conditions. Current-limiting circuits for controlled nanowire synthesis, electric field simulation, and growth mechanism were studied. The simple and straightforward approach to nanowire assembly outlined here

  14. Silver based batteries for high power applications

    NASA Astrophysics Data System (ADS)

    Karpinski, A. P.; Russell, S. J.; Serenyi, J. R.; Murphy, J. P.

    The present status of silver oxide-zinc technology and applications has been described by Karpinski et al. [A.P. Karpinski, B. Makovetski, S.J. Russell, J.R. Serenyi, D.C. Williams, Silver-Zinc: status of technology and applications, Journal of Power Sources, 80 (1999) 53-60], where the silver-zinc couple is still the preferred choice where high specific energy/energy density, coupled with high specific power/power density are important for high-rate, weight or size/configuration sensitive applications. Perhaps the silver oxide cathode can be considered one of the most versatile electrode materials. When coupled with other anodes and corresponding electrolyte management system, the silver electrode provides for a wide array of electrochemical systems that can be tailored to meet the most demanding, high power requirements. Besides zinc, the most notable include cadmium, iron, metal hydride, and hydrogen electrode for secondary systems, while primary systems include lithium and aluminum. Alloys including silver are also available, such as silver chloride, which when coupled with magnesium or aluminum are primarily used in many seawater applications. The selection and use of these couples is normally the result of a trade-off of many factors. These include performance, safety, risk, reliability, and cost. When high power is required, silver oxide-zinc, silver oxide-aluminum, and silver oxide-lithium are the most energetic. For moderate performance (i.e., lower power), silver oxide-zinc or silver-cadmium would be the system of choice. This paper summarizes the suitability of the silver-based couples, with an emphasis on the silver-zinc system, as primary or rechargeable power sources for high energy/power applications.

  15. Doped palladium containing oxidation catalysts

    DOEpatents

    Mohajeri, Nahid

    2014-02-18

    A supported oxidation catalyst includes a support having a metal oxide or metal salt, and mixed metal particles thereon. The mixed metal particles include first particles including a palladium compound, and second particles including a precious metal group (PMG) metal or PMG metal compound, wherein the PMG metal is not palladium. The oxidation catalyst may also be used as a gas sensor.

  16. Synthesis and structural characterization of silver(I), copper(I) coordination polymers and a helicate palladium(II) complex of dipyrrolylmethane-based dipyrazole ligands: the effect of meso substituents on structural formation.

    PubMed

    Guchhait, Tapas; Barua, Bhagyasree; Biswas, Aritra; Basak, Biswanath; Mani, Ganesan

    2015-05-21

    A new class of multidentate dipyrrolylmethane based ditopic tecton, 1,9-bis(3,5-dimethylpyrazolylmethyl)dipyrrolylmethane, containing diethyl (L1) or cyclohexylidene (L2) substituents at the meso carbon atom were readily synthesized in 28-45% yields in two different ways starting from dipyrrolylmethanes. A one dimensional coordination polymer structure ([(L2)Ag][BF4])n was obtained when L2 was treated with AgBF4, whereas the analogous reaction between L1 and AgBF4 afforded the dicationic binuclear metallacycle complex [(L1)2Ag2][BF4]2. In addition, yet another coordination polymeric structure [(L1)CuI]n was obtained from the reaction between L1 and CuI. The analogous reaction of L1 with [Pd(PhCN)2Cl2] afforded the binuclear palladium complex [(L1)2Pd2Cl4] having a double-stranded helicate structure. The observed structural differences are attributed to the effects of the substituents present at the meso carbon atom of the ligand, in addition to the nature of the metal centre, coordination number and the preferred geometry.

  17. Protein-Modified-Paramagnetic-Particles as a Tool for Detection of Silver(I) Ions

    NASA Astrophysics Data System (ADS)

    Kizek, R.; Krizkova, S.; Adam, V.; Huska, D.; Hubalek, J.; Trnkova, L.

    2009-04-01

    In a number of published articles the toxic effect of silver(I) ions on aquatic organisms is described. Silver(I) ions in aquatic environment are stable in a wide range of pH. Under alkali pH AgOH and Ag(OH)2- can be formed. However, in water environment there are many compounds to interact with silver(I) ions. The most important ones are chloride anions, which forms insoluble precipitate with silver(I) ions (AgCl). The insoluble silver containing compounds do not pose any threat to aquatic organisms. Toxicity of silver ions is probably caused by their very good affinity to nucleic acids and also proteins. The binding into active enzyme site leads to the expressive enzyme reaction inhibition. Silver(I) ions are into living environment introduced thanks to anthropogenic activities. They easily contaminate atmosphere as well as aquatic environment or soils. Several authors described using of carbon electrode as working electrode for determination of silver. Recently, we have suggested heavy metal biosensor based on interaction of metal ions with low molecular mass protein called metallothionein (MT), which was adsorbed on the surface of hanging mercury drop electrode (HMDE). The biosensor was successfully used for detection of cadmium(II) and zinc(II) ions, cisplatin, cisplatin-DNA adducts and palladium(II) ions. Due to the convincing results with MT as biological component we report on suggesting of heavy metal biosensor based on immobilization of metallothionein (MT) on the surface of carbon paste electrode (CPE) via MT-antibodies. Primarily we studied of basic electrochemical behaviour of MT at surface of carbon paste electrode by using of square wave voltammetry (SWV). Detection limit (3 S/N) for MT was evaluated as 0.1 μg/ml. After that we have evaluated the electroactivity of MT at surface of SWV, we aimed our attention on the way of capturing of MT on the surface of CPE. We choose antibody against MT obtained from chicken eggs for these purposes. Antibodies

  18. Non-gassing nickel-cadmium battery electrodes and cells

    NASA Technical Reports Server (NTRS)

    Luksha, E.; Gordy, D. J.

    1972-01-01

    The concept of a negative limited nongassing nickel-cadmium battery was demonstrated by constructing and testing practical size experimental cells of approximately 25 Ah capacity. These batteries operated in a gas-free manner and had measured energy densities of 10-11 Wh/lb. Thirty cells were constructed for extensive testing. Some small cells were tested for over 200 cycles at 100% depth. For example, a small cell with an electrodeposited cadmium active mass on a silver screen still had 55% of its theoretical capacity (initial efficiency was 85%). There was no evidence of deterioration of gassing properties with cycling of the nickel electrodes. The charge temperature was observed to be the most critical variable governing nickel electrode gassing. This variable was shown to be age dependent. Four types of cadmium electrodes were tested: an electrodeposited cadmium active mass on a cadmium or silver substrate, a porous sintered silver substrate based electrode, and a Teflon bonded pressed cadmium electrode. The electrodeposited cadmium mass on a silver screen was found to be the best all-around electrode from a performance point of view and from the point of view of manufacturing them in a size required for a 25 Ah size battery.

  19. Palladium(II)-Catalyzed Enantioselective Synthesis of α-(Trifluoromethyl)arylmethylamines.

    PubMed

    Johnson, Thomas; Luo, Bo; Lautens, Mark

    2016-06-17

    We describe a method for the synthesis of α-(trifluoromethyl)arylmethylamines that consists of the palladium(II)-catalyzed addition of arylboroxines to imines derived from trifluoroacetaldehyde. Palladium acetate is used as a catalyst with electron-neutral or electron-rich arylboroxines, and it was found that addition of an ammonium or silver salt was crucial to promote the reaction of electron-poor boroxines. With (S)-t-Bu-PyOX as the chiral ligand, this method delivers a variety of α-trifluoromethylated amines in 57-91% yield and with greater than 92% ee in most cases. PMID:27246788

  20. Electrothermal atomisation atomic absorption conditions and matrix modifications for determining antimony, arsenic, bismuth, cadmium, gallium, gold, indium, lead, molybdenum, palladium, platinum, selenium, silver, tellurium, thallium and tin following back-extraction of organic aminohalide extracts

    USGS Publications Warehouse

    Clark, J.R.

    1986-01-01

    A multi-element organic-extraction and back-extraction procedure, that had been developed previously to eliminate matrix interferences in the determination of a large number of trace elements in complex materials such as geological samples, produced organic and aqueous solutions that were complex. Electrothermal atomisation atomic absorption conditions and matrix modifications have been developed for 13 of the extracted elements (Ag, As, Au, Bi, Cd, Ga, In, Pb, Sb, Se, Sn, Te and Tl) that enhance sensitivity, alleviate problems resulting from the complex solutions and produce acceptable precision. Platinum, Pd and Mo can be determined without matrix modification directly on the original unstripped extracts.

  1. Hydrogen absorption induced metal deposition on palladium and palladium-alloy particles

    DOEpatents

    Wang, Jia X.; Adzic, Radoslav R.

    2009-03-24

    The present invention relates to methods for producing metal-coated palladium or palladium-alloy particles. The method includes contacting hydrogen-absorbed palladium or palladium-alloy particles with one or more metal salts to produce a sub-monoatomic or monoatomic metal- or metal-alloy coating on the surface of the hydrogen-absorbed palladium or palladium-alloy particles. The invention also relates to methods for producing catalysts and methods for producing electrical energy using the metal-coated palladium or palladium-alloy particles of the present invention.

  2. Study of palladium plating components

    NASA Technical Reports Server (NTRS)

    1977-01-01

    Palladium deposits were prepared by electrolysis for evaluation as catalytic materials. Electrolysis was carried out in acidic solutions consisting of either 1.0 M in NaCl and 0.01 M PdCl2 or 1.0 M NaCl and 0.04 M PdCl2. It was during the preparation of the palladium deposits that unexpected observations were made that led to the request for analytical services. The analyses did not, nor were they intended to, answer all of the questions. They did, however, shed light on the nature and magnitude of some of the contaminants in the solutions and in the palladium electrodes, as well as characterize the forms of the palladium deposits. Results of analyses are grouped into solution, deposit, and electrode categories for comparison purposes.

  3. Hydrogen response of porous palladium nano-films

    NASA Astrophysics Data System (ADS)

    Gupta, D.; Barman, P. B.; Hazra, S. K.

    2015-08-01

    Palladium nanoparticles were synthesized by reducing sodium tetrachloropalladate at 100°C using Ethylene Glycol as reducing agent. The nanoparticles were characterized by TEM (Transmission Electron Microscopy), and optical absorption spectroscopy. The average particle size (<10 nm) was obtained from TEM images, and the palladium SPR (Surface Plasmon Resonance) absorption maxima was observed at ˜220 nm. The porous sensing films were prepared by drying the nanoparticles precipitate on cleaned glass substrates. The high porosity of these films, as revealed by Atomic Force Microscopy (AFM) studies, made these films suitable for hydrogen sensor applications. The resistance of the films, measured by making silver paste contacts on the porous surface, changed upon exposure to 1000 ppm hydrogen in nitrogen. Optimum sensor response was obtained at 50°C, beyond which it deteriorated. The total response comprising of initial rise and subsequent fall in resistance, is due to the formation of Pd-hydrides (whose resistivity is higher relative to Pd), and closure of interparticle gaps due to lattice expansion of palladium, respectively. A detailed analysis of the results based on the sensing mechanism has been discussed in the paper.

  4. Hydrogen response of porous palladium nano-films

    SciTech Connect

    Gupta, D. Barman, P. B.; Hazra, S. K.

    2015-08-28

    Palladium nanoparticles were synthesized by reducing sodium tetrachloropalladate at 100°C using Ethylene Glycol as reducing agent. The nanoparticles were characterized by TEM (Transmission Electron Microscopy), and optical absorption spectroscopy. The average particle size (<10 nm) was obtained from TEM images, and the palladium SPR (Surface Plasmon Resonance) absorption maxima was observed at ∼220 nm. The porous sensing films were prepared by drying the nanoparticles precipitate on cleaned glass substrates. The high porosity of these films, as revealed by Atomic Force Microscopy (AFM) studies, made these films suitable for hydrogen sensor applications. The resistance of the films, measured by making silver paste contacts on the porous surface, changed upon exposure to 1000 ppm hydrogen in nitrogen. Optimum sensor response was obtained at 50°C, beyond which it deteriorated. The total response comprising of initial rise and subsequent fall in resistance, is due to the formation of Pd-hydrides (whose resistivity is higher relative to Pd), and closure of interparticle gaps due to lattice expansion of palladium, respectively. A detailed analysis of the results based on the sensing mechanism has been discussed in the paper.

  5. Low-cost method for fabricating palladium and palladium-alloy thin films on porous supports

    DOEpatents

    Lee, Tae H; Park, Chan Young; Lu, Yunxiang; Dorris, Stephen E; Balachandran, Uthamalingham

    2013-11-19

    A process for forming a palladium or palladium alloy membrane on a ceramic surface by forming a pre-colloid mixture comprising a powder palladium source, carrier fluid, dispersant and a pore former and a binder. Ultrasonically agitating the precolloid mixture and applying to a substrate with an ultrasonic nozzle and heat curing the coating form a palladium-based membrane.

  6. Mechanistic Studies of Gold and Palladium Cooperative Dual-Catalytic Cross-Coupling Systems

    PubMed Central

    Al-Amin, Mohammad; Roth, Katrina E.; Blum, Suzanne A.

    2014-01-01

    Double-label crossover, modified-substrate, and catalyst comparison experiments in the gold and palladium dual-catalytic rearrangement/cross-coupling of allenoates were performed in order to probe the mechanism of this reaction. The results are consistent with a cooperative catalysis mechanism whereby 1) gold activates the substrate prior to oxidative addition by palladium, 2) gold acts as a carbophilic rather than oxophilic Lewis acid, 3) competing olefin isomerization is avoided, 4) gold participates beyond the first turnover and therefore does not serve simply to generate the active palladium catalyst, and 5) single-electron transfer is not involved. These experiments further demonstrate that the cooperativity of both gold and palladium in the reaction is essential because significantly lower to zero conversion is achieved with either metal alone in comparison studies that examined multiple potential gold, palladium, and silver catalysts and precatalysts. Notably, employment of the optimized cocatalysts, PPh3AuOTf and Pd2dba3, separately (i.e., only Au or only Pd) results in zero conversion to product at all monitored time points compared to quantitative conversion to product when both are present in cocatalytic reactions. PMID:24757581

  7. Palladium/kieselguhr composition and method

    DOEpatents

    Mosley, W.C. Jr.

    1993-09-28

    A hydrogen-absorbing composition and method for making such a composition are described. The composition comprises a metal hydride, preferably palladium, deposited onto a porous substrate such as kieselguhr, for use in hydrogen-absorbing processes. The composition is made by immersing a substrate in a concentrated solution containing palladium, such as tetra-amine palladium nitrate. Palladium from the solution is deposited onto the porous substrate, which is preferably in the form of kieselguhr particles. The substrate is then removed from the solution, calcined, and heat treated. This process is repeated until the desired amount of palladium has been deposited onto the substrate.

  8. Palladium/kieselguhr composition and method

    DOEpatents

    Mosley, Jr., Wilbur C.

    1993-01-01

    A hydrogen-absorbing composition and method for making such a composition. The composition comprises a metal hydride, preferably palladium, deposited onto a porous substrate such as kieselguhr, for use in hydrogen-absorbing processes. The composition is made by immersing a substrate in a concentrated solution containing palladium, such as tetra-amine palladium nitrate. Palladium from the solution is deposited onto the porous substrate, which is preferably in the form of kieselguhr particles. The substrate is then removed from the solution, calcined, and heat treated. This process is repeated until the desired amount of palladium has been deposited onto the substrate.

  9. Palladium Catalyzed Reduction of Nitrobenzene.

    ERIC Educational Resources Information Center

    Mangravite, John A.

    1983-01-01

    Compares two palladium (Pd/C) reducing systems to iron/tin-hydrochloric acid (Fe/HCl and Sn/HCl) reductions and suggests an efficient, clean, and inexpensive procedures for the conversion of nitrobenzene to aniline. Includes laboratory procedures used and discussion of typical results obtained. (JN)

  10. Reclaiming silver from silver zeolite

    SciTech Connect

    Reimann, G.A.

    1991-10-01

    Silver zeolite is used to capture radioiodines from air cleaning systems in some nuclear facilities at the Idaho National Engineering Laboratory. It may become radioactively contaminated and/or poisoned by hydrocarbon vapors, which diminishes its capacity for iodine. Silver zeolite contains up to 38 wt% silver. A pyrometallurgical process was developed to reclaim the silver before disposing of the unserviceable zeolite as a radioactive waste. A flux was formulated to convert the refractory aluminosilicate zeolite structure into a low-melting fluid slag, with Na{sub 2}O added as NAOH instead of Na{sub 2}CO{sub 3} to avoid severe foaming due to CO{sub 2} evolution. A propane-fired furnace was built to smelt 45 kg charges at 1300C in a carbon-bonded silicon carbide crucible. A total of 218 kg (7000 tr oz) of silver was reclaimed from 1050 kg of unserviceable zeolite. Silver recoveries of 97% were achieved, and the radioisotopes were fixed as stable silicates in a vitreous slag that was disposed of as a low level waste. Recovered silver was refined using oxygen and cast into 100 tr oz bars assaying 99.8+% silver and showing no radioactive contamination.

  11. Reclaiming silver from silver zeolite

    SciTech Connect

    Reimann, G.A.

    1991-10-01

    Silver zeolite is used to capture radioiodines from air cleaning systems in some nuclear facilities at the Idaho National Engineering Laboratory. It may become radioactively contaminated and/or poisoned by hydrocarbon vapors, which diminishes its capacity for iodine. Silver zeolite contains up to 38 wt% silver. A pyrometallurgical process was developed to reclaim the silver before disposing of the unserviceable zeolite as a radioactive waste. A flux was formulated to convert the refractory aluminosilicate zeolite structure into a low-melting fluid slag, with Na[sub 2]O added as NAOH instead of Na[sub 2]CO[sub 3] to avoid severe foaming due to CO[sub 2] evolution. A propane-fired furnace was built to smelt 45 kg charges at 1300C in a carbon-bonded silicon carbide crucible. A total of 218 kg (7000 tr oz) of silver was reclaimed from 1050 kg of unserviceable zeolite. Silver recoveries of 97% were achieved, and the radioisotopes were fixed as stable silicates in a vitreous slag that was disposed of as a low level waste. Recovered silver was refined using oxygen and cast into 100 tr oz bars assaying 99.8+% silver and showing no radioactive contamination.

  12. Palladium as electrode in DNA sequencing

    NASA Astrophysics Data System (ADS)

    Chen, Xiang

    2013-08-01

    We construct a molecular junction comprising two identical "reader" molecules that are each linked on one end to a DNA single base via hydrogen bonds and on the other end to a palladium electrode. The structure of the junction is thus palladium-reader-base-reader-palladium. The palladium-reader contacts occur via Pd-S bonds. We calculated the electronic structure and conductance of the molecular junctions. Compared with the performance of molecular junctions with gold or titanium nitride electrodes, the current-voltage characteristics of the molecular junctions with palladium electrodes show higher sensitivity to the identity of the bridging DNA base, allowing the DNA bases to be distinguished more easily. Therefore, palladium is a superior electrode for molecular electronics and DNA sequencing.

  13. Electrically conductive palladium containing polyimide films

    NASA Technical Reports Server (NTRS)

    Taylor, L. T.; St.clair, A. K.; Carver, V. C.; Furtsch, T. A. (Inventor)

    1982-01-01

    Lightweight, high temperature resistant, electrically conductive, palladium containing polyimide films and methods for their preparation are described. A palladium (II) ion-containing polyamic acid solution is prepared by reacting an aromatic dianhydride with an equimolar quantity of a palladium II ion-containing salt or complex and the reactant product is cast as a thin film onto a surface and cured at approximately 300 C to produce a flexible electrically conductive cyclic palladium containing polyimide. The source of palladium ions is selected from the group of palladium II compounds consisting of LiPdCl4, PdS(CH3)2Cl2Na2PdCl4, and PdCl2. The films have application to aerodynamic and space structures and in particular to the relieving of space charging effects.

  14. Understanding Palladium Acetate from a User Perspective.

    PubMed

    Carole, William A; Colacot, Thomas J

    2016-06-01

    The behavior of palladium acetate is reviewed with respect to its synthesis, characterization, structure (in both solution and solid state), and activation pathways. In addition, comparisons of catalytic activities between pure palladium acetate and two common byproducts, Pd3 (OAc)5 (NO2 ) and polymeric [Pd(OAc)2 ]n , typically present in commercially available material are reviewed. Hence, this minireview serves as a concise guide for the users of palladium acetate from both academia and industry. PMID:27125630

  15. Titanium(IV) oxide photocatalysts with palladium

    SciTech Connect

    Papp, J.; Shen, H.S.; Kershaw, R.; Dwight, K.; Wold, A. )

    1993-03-01

    Samples of palladium decomposed onto TiO[sub 2] particles were prepared by two methods: the dispersion of a PdCl[sub 2] solution followed by thermal decomposition, and the photodecomposition of PdCl[sub 2]. The addition of palladium to all samples increased their photocatalytic activity toward the degradation of 1,4-dichlorobenzene. This increase was optimized and compared for these two preparative methods. Palladium was also decomposed onto TiO[sub 2] thin films by the photodecomposition of PdCl[sub 2]. The addition of palladium to the films increased their photocatalytic activity toward the degradation of salicylic acid. 35 refs., 4 figs., 4 tabs.

  16. Palladium-silver chronology of IAB iron meteorites

    NASA Astrophysics Data System (ADS)

    Theis, K. J.; Schönbächler, M.; Benedix, G. K.; Rehkämper, M.; Andreasen, R.; Davies, C.

    2013-01-01

    The extinct 107Pd-107Ag decay system (half-life ˜6.5 Ma) is a useful chronometer to constrain the thermal evolution of the IAB parent body. To this end, Pd/Ag concentrations and the Ag isotope compositions of metals separated from 6 different IAB iron meteorites were determined. The samples show ɛ107Ag variations between +0.1 and +15.8 with 108Pd/109Ag ratios between 38 and 200. The data can be divided into two groups based on their petrology, each defining an isochron: a graphite and troilite rich inclusion bearing group (A), with the IAB meteorites Toluca, Odessa and Canyon Diablo and a more silicate rich group (B), which includes Campo Del Cielo, Caddo County and Goose Lake. Using the initial abundance of 107Pd derived from carbonaceous chondrites, the corresponding age for the group (A) is 18.7 (+3.6/-5.0) Ma after the start of the solar system and 14.9 (+2.5/-4.9) Ma for the group (B). This suggests that the last thermal event to reach high enough temperatures to melt metal on the IAB parent body occurred within the first 15 Ma of our solar system.

  17. Palladium Decorated Graphene-Nanoribbon Network for Enhanced Gas Sensing.

    PubMed

    Kuru, Cihan; Choi, Duyoung; Choi, Chulmin; Kim, Young Jin; Jin, Sungho

    2015-03-01

    The fabrication of large-scale graphene nanoribbon (GNR) network and its application for gas sensing are reported. A large area, nanoscale GNR network was produced by a facile approach of silver nanowires (Ag NWs) templated graphene masking and subsequent 02 plasma etching. GNR network shows significantly enhanced sensitivity to ammonia gas compared to pristine graphene layer. The gas detection sensitivity of the nanoscale GNR network is even further improved by decorating GNR network with palladium (Pd) or platinum (Pt) nanoparticles, which show a relative resistance response of 65% and 45%, respectively to 50 ppm (parts per million) of ammonia (NH3) in nitrogen (N2) at room temperature as well as good reversibility in air.

  18. Development of highly sensitive cadmium iondashselective electrodes by titration method and its application to cadmium ion determination in industrial waste water.

    PubMed

    Ito, S; Asano, Y; Wada, H

    1997-04-01

    Characteristics of cadmium iondashselective electrode made cadmium sulphide (CdS)-silver sulphide (Ag(2)S) mixture were studied. CdS-Ag(2)S mixtures were obtained by gas/solid-phase reaction between silver-cadmium mixed powder and hydrogen sulphide gas (dry method) and by ionic reaction between cadmium-silver mixed ions and sulphide ion (wet method). As a result, it was found that the CdS-Ag(2)S mixture had to be made in the condition of excess existence of sulfur and had better regulate the excess sulfur quantity minimum, for the CdS-Ag(2)S pressed membrane gave a good Nernstian response against the cadmium ion concentration change. As the best way, CdS-Ag(2)S mixture was obtained by adding sulphide ion solution to 5 mol% cadmium ion and 95 mol% silver ion mixed solution while measuring silver sulphide (Ag(2)S) electrode potential as an indicator electrode. According to the reaction was stopped when the potential variation from the initial potential in the sulphide ion solution reached at 87-116 mV which the sulphide ion concentration became 10(-3) - 10(-4) of the initial concentration, the cadmium ion membrane pressed diameter of 8 mm and thickness of 2 mm showed a Nernstian response from 10(-8) to 10(-1) M of cadmium ion concentration. Furthermore, aiming to its application for industrial waste water, masking buffer for interfering metal ions such as lead ion (Pb(2+)) and copper ion (Cu(2+)), which were possibly coexisted and to adjust total ionic strength and pH of sample was developed. The present Cd(2+) iondashselective electrode was applied to the determination of Cd(2+) in the industrial waste water. The good regression line with correlation factor of 0.984 was obtained compared with the conventional atomic absorption spectroscopy. PMID:18966791

  19. Electronic transitions of palladium dimer

    SciTech Connect

    Qian, Yue; Ng, Y. W.; Chen, Zhihua; Cheung, A. S.-C.

    2013-11-21

    The laser induced fluorescence spectrum of palladium dimer (Pd{sub 2}) in the visible region between 480 and 700 nm has been observed and analyzed. The gas-phase Pd{sub 2} molecule was produced by laser ablation of palladium metal rod. Eleven vibrational bands were observed and assigned to the [17.1] {sup 3}II{sub g} - X{sup 3}Σ{sub u}{sup +} transition system. The bond length (r{sub o}) and vibrational frequency (ΔG{sub 1/2}) of the ground X{sup 3}Σ{sub u}{sup +} state were determined to be 2.47(4) Å and 211.4(5) cm{sup −1}, respectively. A molecular orbital energy level diagram was used to understand the observed ground and excited electronic states. This is the first gas-phase experimental investigation of the electronic transitions of Pd{sub 2}.

  20. Tritium Production from Palladium Alloys

    SciTech Connect

    Claytor, T.N.; Schwab, M.J.; Thoma, D.J.; Teter, D.F.; Tuggle, D.G.

    1998-04-19

    A number of palladium alloys have been loaded with deuterium or hydrogen under low energy bombardment in a system that allows the continuous measurement of tritium. Long run times (up to 200 h) result in an integration of the tritium and this, coupled with the high intrinsic sensitivity of the system ({approximately}0.1 nCi/l), enables the significance of the tritium measurement to be many sigma (>10). We will show the difference in tritium generation rates between batches of palladium alloys (Rh, Co, Cu, Cr, Ni, Be, B, Li, Hf, Hg and Fe) of various concentrations to illustrate that tritium generation rate is dependent on alloy type as well as within a specific alloy, dependent on concentration.

  1. Cadmium carcinogenesis in review.

    PubMed

    Waalkes, M P

    2000-04-01

    Cadmium is an inorganic toxicant of great environmental and occupational concern which was classified as a human carcinogen in 1993. Occupational cadmium exposure is associated with lung cancer in humans. Cadmium exposure has also, on occasion, been linked to human prostate cancer. The epidemiological data linking cadmium and pulmonary cancer are much stronger than for prostatic cancer. Other target sites for cadmium carcinogenesis in humans (liver, kidney, stomach) are considered equivocal. In rodents, cadmium causes tumors at several sites and by various routes. Cadmium inhalation in rats results in pulmonary adenocarcinomas, supporting a role in human lung cancer. Prostate tumors and preneoplastic proliferative lesions can be induced in rats after cadmium ingestion or injection. Prostatic carcinogenesis in rats occurs only at cadmium doses below those that induce chronic degeneration and dysfunction of the testes, a well-known effect of cadmium, confirming the androgen dependency of prostate tumors. Other targets of cadmium in rodents include the testes, adrenals, injection sites, and hematopoietic system. Various treatments can modify cadmium carcinogenesis including supplemental zinc, which prevents cadmium-induced injection site and testicular tumors while facilitating prostatic tumors. Cadmium is poorly mutagenic and probably acts through indirect mechanisms, although the precise mechanisms remain unknown. PMID:10830873

  2. Cadmium carcinogenesis in review.

    PubMed

    Waalkes, M P

    2000-04-01

    Cadmium is an inorganic toxicant of great environmental and occupational concern which was classified as a human carcinogen in 1993. Occupational cadmium exposure is associated with lung cancer in humans. Cadmium exposure has also, on occasion, been linked to human prostate cancer. The epidemiological data linking cadmium and pulmonary cancer are much stronger than for prostatic cancer. Other target sites for cadmium carcinogenesis in humans (liver, kidney, stomach) are considered equivocal. In rodents, cadmium causes tumors at several sites and by various routes. Cadmium inhalation in rats results in pulmonary adenocarcinomas, supporting a role in human lung cancer. Prostate tumors and preneoplastic proliferative lesions can be induced in rats after cadmium ingestion or injection. Prostatic carcinogenesis in rats occurs only at cadmium doses below those that induce chronic degeneration and dysfunction of the testes, a well-known effect of cadmium, confirming the androgen dependency of prostate tumors. Other targets of cadmium in rodents include the testes, adrenals, injection sites, and hematopoietic system. Various treatments can modify cadmium carcinogenesis including supplemental zinc, which prevents cadmium-induced injection site and testicular tumors while facilitating prostatic tumors. Cadmium is poorly mutagenic and probably acts through indirect mechanisms, although the precise mechanisms remain unknown.

  3. Palladium-Catalyzed Site-Selective C-H Functionalization of Weakly Coordinating Sulfonamides: Synthesis of Biaryl Sulfonamides.

    PubMed

    Vanjari, Rajeshwer; Guntreddi, Tirumaleswararao; Singh, Krishna Nand

    2016-03-01

    A novel and site selective C-H functionalization of unsubstituted sulfonamides has been developed for the synthesis of ortho aryl sulfonamides. The reaction involves highly regioselective ortho mono arylation of weakly coordinating SO2 NH2 directing group by means of aryl iodides. Palladium acetate in the presence of silver(I) oxide is found to be the most effective catalytic system. PMID:26763530

  4. Large-scale atomistic simulations of helium-3 bubble growth in complex palladium alloys

    NASA Astrophysics Data System (ADS)

    Hale, Lucas M.; Zimmerman, Jonathan A.; Wong, Bryan M.

    2016-05-01

    Palladium is an attractive material for hydrogen and hydrogen-isotope storage applications due to its properties of large storage density and high diffusion of lattice hydrogen. When considering tritium storage, the material's structural and mechanical integrity is threatened by both the embrittlement effect of hydrogen and the creation and evolution of additional crystal defects (e.g., dislocations, stacking faults) caused by the formation and growth of helium-3 bubbles. Using recently developed inter-atomic potentials for the palladium-silver-hydrogen system, we perform large-scale atomistic simulations to examine the defect-mediated mechanisms that govern helium bubble growth. Our simulations show the evolution of a distribution of material defects, and we compare the material behavior displayed with expectations from experiment and theory. We also present density functional theory calculations to characterize ideal tensile and shear strengths for these materials, which enable the understanding of how and why our developed potentials either meet or confound these expectations.

  5. Palladium-Catalyzed Direct Cyclopropylation of Heterocycles.

    PubMed

    Wu, Xiaojin; Lei, Chuanhu; Yue, Guizhou; Zhou, Jianrong Steve

    2015-08-10

    Many 1,3-azoles and thiophenes are directly cyclopropylated in the presence of a simple palladium catalyst. The relative configuration on the three-membered rings is retained in the products. Thus, the cyclopropyl-halide bond undergoes concerted oxidative addition to palladium(0) and cyclopropyl radicals are not involved in the productive pathway.

  6. Biaxially textured metal substrate with palladium layer

    DOEpatents

    Robbins, William B [Maplewood, MN

    2002-12-31

    Described is an article comprising a biaxially textured metal substrate and a layer of palladium deposited on at least one major surface of the metal substrate; wherein the palladium layer has desired in-plane and out-of-plane crystallographic orientations, which allow subsequent layers that are applied on the article to also have the desired orientations.

  7. Process for producing cadmium sulfide on a cadmium telluride surface

    DOEpatents

    Levi, Dean H.; Nelson, Art J.; Ahrenkiel, Richard K.

    1996-01-01

    A process for producing a layer of cadmium sulfide on a cadmium telluride surface to be employed in a photovoltaic device. The process comprises providing a cadmium telluride surface which is exposed to a hydrogen sulfide plasma at an exposure flow rate, an exposure time and an exposure temperature sufficient to permit reaction between the hydrogen sulfide and cadmium telluride to thereby form a cadmium sulfide layer on the cadmium telluride surface and accomplish passivation. In addition to passivation, a heterojunction at the interface of the cadmium sulfide and the cadmium telluride can be formed when the layer of cadmium sulfide formed on the cadmium telluride is of sufficient thickness.

  8. HRTEM/AEM and SEM study of fluid-rock interactions: Interaction of copper, silver, selenium, chromium, and cadmium-bearing solutions with geological materials at near surface conditions, with an emphasis on phyllosilicates

    SciTech Connect

    Veblen, D.R.; Ilton, E.S.

    1992-05-01

    Biotite has been reacted with acidic solutions, at 25'' +/-3''C, bearing silver (Ag{sub 2}SO{sub 4}), selenium (selenite), chromium (hexavalent Cr), and copper (CuSO{sub 4}). The experiments were open to the atmosphere. Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) show that biotite sorbs and reduces Ag+(aq) to metallic silver. Polygonal precipitates and inclusions of metallic silver (with diameters ranging from 10's of angstroms to > {ge} {mu}m) are concentrated on the edges of the biotite flakes and also in the interlayer region. X-ray photoelectron spectroscopy (XPS) of biotites reacted with selenite-bearing solutions show that the oxidation state of selenium sorbed on the surface of biotite is Se{sup 4+}. XPS of biotites reacted with Cr{sup 6+}-bearing solutions show that the oxidation state of chromium sorbed on the surface of biotite is Cr{sup 3+}. Copper-bearing solutions were reacted with low-F biotite in contrast to our previous work with high-F biotite (Olden et al., in press). Results indicate that low-F biotite absorbs more readily and extensively than high-F biotite. Further work on copper-enriched biotite from the chrysocolla zone has revealed that the mode of copper incorporation in biotite is more complex than previously described.

  9. Mechanisms of Cadmium Carcinogenesis

    EPA Science Inventory

    Cadmium is a transition metal and an ubiquitous environmental and industrial pollutant. Laboratory animal studies and epidemiological studies have shown that exposure to cadmium is associated with various organ toxicities and carcinogenic effects. Several national and internation...

  10. Cadmium sulfide membranes

    DOEpatents

    Spanhel, Lubomir; Anderson, Marc A.

    1992-07-07

    A method is described for the creation of novel q-effect cadmium sulfide membranes. The membranes are made by first creating a dilute cadmium sulfide colloid in aqueous suspension and then removing the water and excess salts therefrom. The cadmium sulfide membrane thus produced is luminescent at room temperature and may have application in laser fabrication.

  11. Cadmium sulfide membranes

    DOEpatents

    Spanhel, Lubomir; Anderson, Marc A.

    1991-10-22

    A method is described for the creation of novel q-effect cadmium sulfide membranes. The membranes are made by first creating a dilute cadmium sulfide colloid in aqueous suspension and then removing the water and excess salts therefrom. The cadmium sulfide membrane thus produced is luminescent at room temperature and may have application in laser fabrication.

  12. Gold, palladium, and gold-palladium alloy nanoshells on silica nanoparticle cores.

    PubMed

    Kim, Jun-Hyun; Bryan, William W; Chung, Hae-Won; Park, Chan Young; Jacobson, Allan J; Lee, T Randall

    2009-05-01

    The synthesis of gold, palladium, and gold-palladium alloy nanoshells (approximately 15-20 nm thickness) was accomplished by the reduction of gold and palladium ions onto dielectric silica core particles (approximately 100 nm in diameter) seeded with small gold nanoparticles (approximately 2-3 nm in diameter). The size, morphology, elemental composition, and optical properties of the nanoshells were characterized using field-emission scanning electron microscopy, transmission electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction, and ultraviolet-visible spectroscopy. The results demonstrate the successful growth of gold, palladium, and gold-palladium alloy nanoshells, where the optical properties systematically vary with the relative content of gold and palladium. The alloy nanoshells are being prepared for use in applications that stand to benefit from photoenhanced catalysis. PMID:20355892

  13. Silver cyanide

    Integrated Risk Information System (IRIS)

    Silver cyanide ; CASRN 506 - 64 - 9 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarcinogenic Ef

  14. Preliminary studies on palladium nanoparticle as a novel label for DNA microarray and their corresponding detection.

    PubMed

    Wang, Zhifei; Li, Hongyin; Zhen, Shuang; Zhang, Yuanying; He, Nongyue

    2013-06-01

    This paper firstly describes the preliminary results achieved by using palladium nanoparticle (Pd NP) as a novel label for the detection of DNA hybridization in DNA microarray. And two signal amplification procedures based on "the silver staining" or "the cobalt staining" are presented during above analysis. The results show that the label Pd NP-ssDNA (target) (single strand DNA(target)) performs high single base pair mismatch-discrimination capability. The succeeding silver staining or cobalt staining procedure greatly amplifies such a signal through the catalysis of Pd. For "the silver staining:' the background staining is very low and the silver deposition only occurs around Pd NPs. So such a procedure provides a alternative for "Gold Label Silver Stain" presented by Mirkin C. A. For "the cobalt staining," not only a colorimetric array but also a magnetic sensor (such as Magnetic Tunnel Junction sensor, MTJ) can be used to detect the obtained cobalt dot due to its strong magnetic property, which provides a new strategy for DNA microarray detection. So as the proof-of-concept investigations, this work proved the feasibility of the application of Pd NPs as the label in DNA microarray assay.

  15. Cadmium and renal cancer

    SciTech Connect

    Il'yasova, Dora; Schwartz, Gary G. . E-mail: gschwart@wfubmc.edu

    2005-09-01

    Background: Rates of renal cancer have increased steadily during the past two decades, and these increases are not explicable solely by advances in imaging modalities. Cadmium, a widespread environmental pollutant, is a carcinogen that accumulates in the kidney cortex and is a cause of end-stage renal disease. Several observations suggest that cadmium may be a cause of renal cancer. Methods: We performed a systematic review of the literature on cadmium and renal cancer using MEDLINE for the years 1966-2003. We reviewed seven epidemiological and eleven clinical studies. Results: Despite different methodologies, three large epidemiologic studies indicate that occupational exposure to cadmium is associated with increased risk renal cancer, with odds ratios varying from 1.2 to 5.0. Six of seven studies that compared the cadmium content of kidneys from patients with kidney cancer to that of patients without kidney cancer found lower concentrations of cadmium in renal cancer tissues. Conclusions: Exposure to cadmium appears to be associated with renal cancer, although this conclusion is tempered by the inability of studies to assess cumulative cadmium exposure from all sources including smoking and diet. The paradoxical findings of lower cadmium content in kidney tissues from patients with renal cancer may be caused by dilution of cadmium in rapidly dividing cells. This and other methodological problems limit the interpretation of studies of cadmium in clinical samples. Whether cadmium is a cause of renal cancer may be answered more definitively by future studies that employ biomarkers of cadmium exposure, such as cadmium levels in blood and urine.

  16. Evaluation of the potential carcinogenicity of cadmium, cadium acetate, cadmium bromide, cadmium chloride. Final report

    SciTech Connect

    Not Available

    1988-06-01

    Cadmium is a probable human carcinogen, classified as weight-of-evidence Group B1 under the EPA Guidelines for Carcinogen Risk Assessment (U.S. EPA, 1986a). Evidence on potential carcinogenicity from animal studies is Sufficient, and the evidence from human studies is Limited. The potency factor (F) for cadmium is estimated to be 57.9/(mg/kg/day) (based on epidemiology data for cadmium workers), placing it in potency group 2 according to the CAG's methodology for evaluating potential carcinogens (U.S. EPA, 1986b). Cadmium weight of evidence and potency are based on epidemiology data for cadmium workers exposed to cadmium oxide and/or cadmium fume. Although human data for cadmium salts are lacking, due to the responsiveness of animals to soluble cadmium compounds, especially cadmium chloride, the weight of evidence and potency for cadmium acetate, cadmium bromide and cadmium chloride are considered to be the same as those cadmium compounds to which workers are exposed. Thus, cadmium acetate, cadmium bromide, and cadmium chloride are all classified as weight-of-evidence Group and the potency group, cadmium, cadmium acetate, cadmium bromide, and cadmium chloride are assigned MEDIUM hazard rankings for the purposes of RQ adjustment. Combining the weight-of-evidence group and the potency group, carbon tetrachloride is assigned a MEDIUM hazard ranking for the purposes of RQ adjustment.

  17. Palladium and its alloys as membrane catalysts

    SciTech Connect

    Gryaznov, V.M.

    1983-05-01

    Possibilities have been examined for the use of selective transport of hydrogen through palladium alloy membranes in order to increase the efficiency of hydrogen recovery from gas mixtures and catalytic reactions in which hydrogen is consumed or formed. By varying the hydrogen concentration in the bulk and on the surface of a palladium alloy, it becomes possible to increase the selectivity of hydrogenation reactions. Continuous and semicontinuous methods have been developed for obtaining valuable products on membrane catalysts.

  18. Palladium and gold nanotubes as oxygen reduction reaction and alcohol oxidation reaction catalysts in base.

    PubMed

    Alia, Shaun M; Duong, Kathlynne; Liu, Toby; Jensen, Kurt; Yan, Yushan

    2014-06-01

    Palladium (PdNTs) and gold nanotubes (AuNTs) were synthesized by the galvanic displacement of silver nanowires. PdNTs and AuNTs have wall thicknesses of 6 nm, outer diameters of 60 nm, and lengths of 5-10 and 5-20 μm, respectively. Rotating disk electrode experiments showed that the PdNTs and AuNTs have higher area normalized activities for the oxygen reduction reaction (ORR) than conventional nanoparticle catalysts. The PdNTs produced an ORR area activity that was 3.4, 2.2, and 3.7 times greater than that on carbon-supported palladium nanoparticles (Pd/C), bulk polycrystalline palladium, and carbon-supported platinum nanoparticles (Pt/C), respectively. The AuNTs produced an ORR area activity that was 2.3, 9.0, and 2.0 times greater than that on carbon-supported gold nanoparticles (Au/C), bulk polycrystalline gold, and Pt/C, respectively. The PdNTs also had lower onset potentials than Pd/C and Pt/C for the oxidation of methanol (0.236 V), ethanol (0.215 V), and ethylene glycol (0.251 V). In comparison to Pt/C, the PdNTs and AuNTs further demonstrated improved alcohol tolerance during the ORR.

  19. Palladium catalysis for energy applications

    SciTech Connect

    Pfefferle, L. D.; Datye, Abhaya

    2001-03-01

    Palladium (Pd) is an attractive catalyst for a range of new combustion applications comprising primary new technologies for future industrial energy needs, including gas turbine catalytic combustion, auto exhaust catalysts, heating and fuel cells. Pd poses particular challenges because it changes both chemical state and morphology as a function of temperature and reactant environment and those changes result in positive and negative changes in activity. Interactions with the support, additives, water, and contaminants as well as carbon formation have also been observed to affect Pd catalyst performance. This report describes the results of a 3.5 year project that resolves some of the conflicting reports in the literature about the performance of Pd-based catalysis.

  20. Fluorometric imaging methods for palladium and platinum and the use of palladium for imaging biomolecules.

    PubMed

    Tracey, Matthew P; Pham, Dianne; Koide, Kazunori

    2015-07-21

    Neither palladium nor platinum is an endogenous biological metal. Imaging palladium in biological samples, however, is becoming increasingly important because bioorthogonal organometallic chemistry involves palladium catalysis. In addition to being an imaging target, palladium has been used to fluorometrically image biomolecules. In these cases, palladium species are used as imaging-enabling reagents. This review article discusses these fluorometric methods. Platinum-based drugs are widely used as anticancer drugs, yet their mechanism of action remains largely unknown. We discuss fluorometric methods for imaging or quantifying platinum in cells or biofluids. These methods include the use of chemosensors to directly detect platinum, fluorescently tagging platinum-based drugs, and utilizing post-labeling to elucidate distribution and mode of action.

  1. Cadmium - a metallohormone?

    PubMed Central

    Byrne, Celia; Divekar, Shailaja D.; Storchan, Geoffrey B.; Parodi, Daniela A.; Martin, Mary Beth

    2009-01-01

    Cadmium is a heavy metal that is often referred to as the metal of the 20th Century. It is widely used in industry principally in galvanizing and electroplating, in batteries, in electrical conductors, in the manufacture of alloys, pigments, and plastics, and in the stabilization of phosphate fertilizers. As a byproduct of smelters, cadmium is a prevalent environmental contaminant. In the general population, exposure to cadmium occurs primarily through dietary sources, cigarette smoking, and, to a lesser degree, drinking water. Although the metal has no known physiological function, there is evidence to suggest that the cadmium is a potent metallohormone. This review summarizes the increasing evidence that cadmium mimics the function of steroid hormones, addresses our current understanding of the mechanism by which cadmium functions as a hormone, and discusses its potential role in development of the hormone dependent cancers. PMID:19362102

  2. Cadmium in tobacco

    SciTech Connect

    Yue, L. )

    1992-03-01

    The present study was conducted to determine the cadmium level in tobacco planted in five main tobacco-producing areas, a cadmium polluted area, and in cigarettes produced domestically (54 brands). The results indicate that average cadmium content in tobacco was 1.48 (0.10-4.95 mg/kg), which was similar to that of Indian tobacco (1.24 mg/kg), but the cadmium of tobacco produced in the cadmium polluted area was quite high (8.60 mg/kg). The average cigarette cadmium was 1.05 micrograms/g (with filter tip) and 1.61 micrograms/g (regular cigarette). Therefore special attention should be paid to the soil used in planting tobacco.

  3. Cadmium - A metallohormone?

    SciTech Connect

    Byrne, Celia; Divekar, Shailaja D.; Storchan, Geoffrey B.; Parodi, Daniela A.; Martin, Mary Beth

    2009-08-01

    Cadmium is a heavy metal that is often referred to as the metal of the 20th century. It is widely used in industry principally in galvanizing and electroplating, in batteries, in electrical conductors, in the manufacture of alloys, pigments, and plastics, and in the stabilization of phosphate fertilizers. As a byproduct of smelters, cadmium is a prevalent environmental contaminant. In the general population, exposure to cadmium occurs primarily through dietary sources, cigarette smoking, and, to a lesser degree, drinking water. Although the metal has no known physiological function, there is evidence to suggest that the cadmium is a potent metallohormone. This review summarizes the increasing evidence that cadmium mimics the function of steroid hormones, addresses our current understanding of the mechanism by which cadmium functions as a hormone, and discusses its potential role in development of the hormone dependent cancers.

  4. Palladium catalyzed hydrogenation of bio-oils and organic compounds

    DOEpatents

    Elliott, Douglas C.; Hu, Jianli; Hart, Todd R.; Neuenschwander, Gary G.

    2008-09-16

    The invention provides palladium-catalyzed hydrogenations of bio-oils and certain organic compounds. Experimental results have shown unexpected and superior results for palladium-catalyzed hydrogenations of organic compounds typically found in bio-oils.

  5. Palladium catalyzed hydrogenation of bio-oils and organic compounds

    DOEpatents

    Elliott, Douglas C [Kennewick, WA; Hu, Jianli [Richland, WA; Hart,; Todd, R [Kennewick, WA; Neuenschwander, Gary G [Burbank, WA

    2011-06-07

    The invention provides palladium-catalyzed hydrogenations of bio-oils and certain organic compounds. Experimental results have shown unexpected and superior results for palladium-catalyzed hydrogenations of organic compounds typically found in bio-oils.

  6. Cadmium toxicity and treatment.

    PubMed

    Bernhoft, Robin A

    2013-01-01

    Cadmium is a heavy metal of considerable toxicity with destructive impact on most organ systems. It is widely distributed in humans, the chief sources of contamination being cigarette smoke, welding, and contaminated food and beverages. Toxic impacts are discussed and appear to be proportional to body burden of cadmium. Detoxification of cadmium with EDTA and other chelators is possible and has been shown to be therapeutically beneficial in humans and animals when done using established protocols.

  7. Cadmium Toxicity and Treatment

    PubMed Central

    Bernhoft, Robin A.

    2013-01-01

    Cadmium is a heavy metal of considerable toxicity with destructive impact on most organ systems. It is widely distributed in humans, the chief sources of contamination being cigarette smoke, welding, and contaminated food and beverages. Toxic impacts are discussed and appear to be proportional to body burden of cadmium. Detoxification of cadmium with EDTA and other chelators is possible and has been shown to be therapeutically beneficial in humans and animals when done using established protocols. PMID:23844395

  8. ENCAPSULATION OF PALLADIUM IN POROUS WALL HOLLOW GLASS MICROSPHERES

    SciTech Connect

    Heung, L; George Wicks, G; Ray Schumacher, R

    2008-04-09

    A new encapsulation method was investigated in an attempt to develop an improved palladium packing material for hydrogen isotope separation. Porous wall hollow glass microspheres (PWHGMs) were produced by using a flame former, heat treating and acid leaching. The PWHGMs were then filled with palladium salt using a soak-and-dry process. The palladium salt was reduced at high temperature to leave palladium inside the microspheres.

  9. Palladium-cobalt particles as oxygen-reduction electrocatalysts

    DOEpatents

    Adzic, Radoslav; Huang, Tao

    2009-12-15

    The present invention relates to palladium-cobalt particles useful as oxygen-reducing electrocatalysts. The invention also relates to oxygen-reducing cathodes and fuel cells containing these palladium-cobalt particles. The invention additionally relates to methods for the production of electrical energy by using the palladium-cobalt particles of the invention.

  10. Nickel-Cadmium Cell Design Variable Program Data Analysis

    NASA Technical Reports Server (NTRS)

    Morrow, G. W.

    1985-01-01

    A program was undertaken in conjunction with the General Electric Company to evaluate 9 of the more important nickel cadmium aerospace cell designs that are currently being used or that have been used in the past 15 years. Design variables tested in this program included teflonated negative plates, silver treated negative plates, light plate loading level, no positive plate cadmium treatment, plate design of 1968 utilizing both old and new processing techniques, and electrochemically impregnated positive plates. The data acquired from these test packs in a low Earth orbit cycling regime is presented and analyzed here. This data showed conclusively that the cells manufactured with no positive plate cadmium treatment outperformed all other cell designs in all aspects of the program and that the cells with teflonated negative electrodes performed very poorly.

  11. Process for producing cadmium sulfide on a cadmium telluride surface

    DOEpatents

    Levi, D.H.; Nelson, A.J.; Ahrenkiel, R.K.

    1996-07-30

    A process is described for producing a layer of cadmium sulfide on a cadmium telluride surface to be employed in a photovoltaic device. The process comprises providing a cadmium telluride surface which is exposed to a hydrogen sulfide plasma at an exposure flow rate, an exposure time and an exposure temperature sufficient to permit reaction between the hydrogen sulfide and cadmium telluride to thereby form a cadmium sulfide layer on the cadmium telluride surface and accomplish passivation. In addition to passivation, a heterojunction at the interface of the cadmium sulfide and the cadmium telluride can be formed when the layer of cadmium sulfide formed on the cadmium telluride is of sufficient thickness. 12 figs.

  12. Californium Recovery from Palladium Wire

    SciTech Connect

    Burns, Jon D.

    2014-08-01

    The recovery of 252Cf from palladium-252Cf cermet wires was investigated to determine the feasibility of implementing it into the cermet wire production operation at Oak Ridge National Laboratory’s Radiochemical Engineering Development Center. The dissolution of Pd wire in 8 M HNO3 and trace amounts of HCl was studied at both ambient and elevated temperatures. These studies showed that it took days to dissolve the wire at ambient temperature and only 2 hours at 60°C. Adjusting the ratio of the volume of solvent to the mass of the wire segment showed little change in the kinetics of dissolution, which ranged from 0.176 mL/mg down to 0.019 mL/mg. A successful chromatographic separation of 153Gd, a surrogate for 252Cf, from Pd was demonstrated using AG 50x8 cation exchange resin with a bed volume of 0.5 mL and an internal diameter of 0.8 cm.

  13. Palladium on Plastic Substrates for Plasmonic Devices

    PubMed Central

    Zuppella, Paola; Pasqualotto, Elisabetta; Zuccon, Sara; Gerlin, Francesca; Corso, Alain Jody; Scaramuzza, Matteo; De Toni, Alessandro; Paccagnella, Alessandro; Pelizzo, Maria Guglielmina

    2015-01-01

    Innovative chips based on palladium thin films deposited on plastic substrates have been tested in the Kretschmann surface plasmon resonance (SPR) configuration. The new chips combine the advantages of a plastic support that is interesting and commercially appealing and the physical properties of palladium, showing inverted surface plasmon resonance (ISPR). The detection of DNA chains has been selected as the target of the experiment, since it can be applied to several medical early diagnostic tools, such as different biomarkers of cancers or cystic fibrosis. The results are encouraging for the use of palladium in SPR-based sensors of interest for both the advancement of biodevices and the development of hydrogen sensors. PMID:25585102

  14. The Effect of Palladium Additions on the Solidus/Liquidus Temperatures and Wetting Properties of Ag-CuO Based Air Brazes

    SciTech Connect

    Darsell, Jens T.; Weil, K. Scott

    2007-05-16

    As a means of increasing the use temperature of ceramic-ceramic and ceramic-metal air brazes, palladium was investigated as possible ternary addition to the currently employed silver - copper oxide system. The silver component was directly substituted with palladium to form the following series of alloys: (100-y)[(100-z)Pd - (z)Ag] - (y)CuOx where y = 0 - 34 mol% CuOx, z = 50 - 100 mol% silver, and x = 0, 0.5, and 1, denoting copper metal, Cu2O, or CuO. From differential scanning calorimetry, it was determined that the addition of palladium causes an increase in the solidus and liquidus temperatures of the resulting Pd-Ag-CuO brazes. In general, the liquidus was found to increase by approximately 220°C for the (100-y)(25Pd - 75Ag) - (z)CuOx filler metal compositions relative to comparable Ag-CuOx alloys. Likewise, the solidus was found to increase for these alloys, respectively by 185°C and 60°C, respectively for CuOx contents of y = 0 - 1mol% and 4 - 10 mol%. For the (100-y)(50Pd - 50Ag) - (y)CuOx alloys, the solidus increased between 280 - 390°C over a copper oxide compositional range of x = 0 to 8 mol%. It was determined from sessile drop experiments conducted on alumina substrates that in all cases the palladium causes an increase in the wetting angle relative to the corresponding binary braze. Alloy compositions of (100-y)(25Pd - 75Ag) - (y)CuOx displayed increased wetting angles of 5-20° relative to comparable binary compositions. (100-y)(50Pd - 50Ag) - (y)CuOx alloys exhibited an increase in contact angle of 10-60° and compositions containing less than 10 mol% CuOx were not able to wet the substrate. Scanning electron microscopy indicated that the microstructure of the braze consists of discrete CuOx precipitates in an alloyed silver-palladium matrix. In both the binary and ternary filler metal formulations, a reaction layer consisting of CuAlO2 was observed along the interface with the alumina substrate. This reaction product appears to be beneficial

  15. Highly Concentrated Palladium Hydrides/Deuterides; Theory

    SciTech Connect

    Papaconstantopoulos, Dimitrios

    2013-11-26

    Accomplishments are reported in these areas: tight-binding molecular dynamics study of palladium; First-principles calculations and tight-binding molecular dynamics simulations of the palladium-hydrogen system; tight-binding studies of bulk properties and hydrogen vacancies in KBH{sub 4}; tight-binding study of boron structures; development of angular dependent potentials for Pd-H; and density functional and tight-binding calculations for the light-hydrides NaAlH4 and NaBH4

  16. The truth about silver.

    PubMed

    Ovington, Liza G

    2004-09-01

    Interest in silver as a topical agent in wound healing is undergoing a renaissance. Having basic information regarding silver's chemical properties and potential actions in the wound bed is important to its appropriate clinical use. Such information is also relevant to the interpretation of silver's in vitro antimicrobial (antiseptic) effects, which in turn relate to issues involved in the evaluation of the clinical effects of silver in vivo. Gaining an understanding of the basic science of silver products and the different challenges inherent to in vitro versus in vivo antimicrobial evaluations will allow clinicians to address several key questions inherent when considering the use of silver as a topical antimicrobial: 1) Are there different forms of silver? 2) How does the amount of silver released into the wound environment correlate with clinical benefit? 3) How does the rate of silver release correlate with clinical benefit?

  17. Efficient palladium-catalyzed aminocarbonylation of aryl iodides using palladium nanoparticles dispersed on siliceous mesocellular foam.

    PubMed

    Tinnis, Fredrik; Verho, Oscar; Gustafson, Karl P J; Tai, Cheuk-Wai; Bäckvall, Jan-E; Adolfsson, Hans

    2014-05-12

    A highly dispersed nanopalladium catalyst supported on mesocellular foam (MCF), was successfully used in the heterogeneous catalysis of aminocarbonylation reactions. During the preliminary evaluation of this catalyst it was discovered that the supported palladium nanoparticles exhibited a "release and catch" effect, meaning that a minor amount of the heterogeneous palladium became soluble and catalyzed the reaction, after which it re-deposited onto the support.

  18. Viral-templated Palladium Nanocatalysts

    NASA Astrophysics Data System (ADS)

    Yang, Cuixian

    Despite recent progress on nanocatalysis, there exist several critical challenges in simple and readily controllable nanocatalyst synthesis including the unpredictable particle growth, deactivation of catalytic activity, cumbersome catalyst recovery and lack of in-situ reaction monitoring. In this dissertation, two novel approaches are presented for the fabrication of viral-templated palladium (Pd) nanocatalysts, and their catalytic activities for dichromate reduction reaction and Suzuki Coupling reaction were thoroughly studied. In the first approach, viral template based bottom-up assembly is employed for the Pd nanocatalyst synthesis in a chip-based format. Specifically, genetically displayed cysteine residues on each coat protein of Tobacco Mosaic Virus (TMV) templates provide precisely spaced thiol functionalities for readily controllable surface assembly and enhanced formation of catalytically active Pd nanoparticles. Catalysts with the chip-based format allow for simple separation and in-situ monitoring of the reaction extent. Thorough examination of synthesis-structure-activity relationship of Pd nanoparticles formed on surface-assembled viral templates shows that Pd nanoparticle size, catalyst loading density and catalytic activity of viral-templated Pd nanocatalysts can be readily controlled simply by tuning the synthesis conditions. The viral-templated Pd nanocatalysts with optimized synthesis conditions are shown to have higher catalytic activity per unit Pd mass than the commercial Pd/C catalysts. Furthermore, tunable and selective surface assembly of TMV biotemplates is exploited to control the loading density and location of Pd nanocatalysts on solid substrates via preferential electroless deposition. In addition, the catalytic activities of surface-assembled TMV-templated Pd nanocatalysts were also investigated for the ligand-free Suzuki Coupling reaction under mild reaction conditions. The chip-based format enables simple catalyst separation and

  19. Combine palladium with iron for enhanced dechlorination

    SciTech Connect

    1995-07-01

    Research Corporation Technologies (RCT; Tucson, Arizona) is completing bench-scale testing of a new groundwater-treatment process that uses particles of palladium-coated iron to dechlorinate organic compounds. The palladized-iron process, developed by a research team at the University of Arizona, dechlorinates low-molecular-weight hydrocarbons by converting the chlorinated organics to chloride ions and either methane or ethane gas. A three-month test of an above-ground treatment unit is scheduled to begin in September. The key to the new process is the palladium. When elemental iron is immersed in water, it oxidizes and releases electrons, which create a reducing environment. This reducing environment breaks down chlorinated and fluorinated organic compounds. Unfortunately, a layer of metal oxide (rust) forms on the iron surface. This layer ultimately impedes the flow of electrons into the water and makes the reduction process slow and inefficient. To overcome this, RCT deposits a small amount (0.05 wt%) of palladium as discrete islands on the iron particles. This palladium prevents rust from coating the iron but does not impede the steady flow of the electrons needed to sustain a reducing environment.

  20. Hydrogen and Palladium Foil: Two Classroom Demonstrations

    ERIC Educational Resources Information Center

    Klotz, Elsbeth; Mattson, Bruce

    2009-01-01

    In these two classroom demonstrations, students observe the reaction between H[subscript 2] gas and Pd foil. In the first demonstration, hydrogen and palladium combine within one minute at 1 atm and room temperature to yield the non-stoichiometric, interstitial hydride with formula close to the maximum known value, PdH[subscript 0.7]. In the…

  1. Mineral commodity profiles: Cadmium

    USGS Publications Warehouse

    Butterman, W.C.; Plachy, Jozef

    2004-01-01

    Overview -- Cadmium is a soft, low-melting-point metal that has many uses. It is similar in abundance to antimony and bismuth and is the 63d element in order of crustal abundance. Cadmium is associated in nature with zinc (and, less closely, with lead and copper) and is extracted mainly as a byproduct of the mining and processing of zinc. In 2000, it was refined in 27 countries, of which the 8 largest accounted for two-thirds of world production. The United States was the third largest refiner after Japan and China. World production in 2000 was 19,700 metric tons (t) and U.S. production was 1,890 t. In the United States, one company in Illinois and another in Tennessee refined primary cadmium. A Pennsylvania company recovered cadmium from scrap, mainly spent nickel-cadmium (NiCd) batteries. The supply of cadmium in the world and in the United States appears to be adequate to meet future industrial needs; the United States has about 23 percent of the world reserve base.

  2. Voltammetric studies on the palladium oxides in alkaline media

    SciTech Connect

    Moo Cheol Jeong; In Hyeong Yeo . Dept. of Chemistry); Chong Hong Pyun . Solid State Chemistry Lab.)

    1993-07-01

    The formation and stripping of palladium oxides on a palladium electrode in a 0.1M LiOH solution was studied by cyclic voltammetry. Cyclic polarization methods were used to form palladium oxides on the surface of the palladium electrode. Three different types of palladium oxides were found to be formed in alkaline solutions. A higher oxidation state of palladium oxide (PdO[sub 3]) can be formed (induced) on the surface of the electrode even at low anodic potential limit, 0.6 V (vs. SCE). Strong evidence that PdO[sub 3] can only be formed in a specific potential range is presented. From the voltammograms obtained after a long cyclic polarization time, the peak in the range of [minus]0.47 to [minus]0.60 V could be attributed to the reduction of dehydrated PdO.

  3. Cadmium transporters in the kidney and cadmium-induced nephrotoxicity.

    PubMed

    Yang, Hong; Shu, Yan

    2015-01-09

    Among the organs in which the environmental pollutant cadmium causes toxicity, the kidney has gained the most attention in recent years. Numerous studies have sought to unravel the exact pathways by which cadmium enters the renal epithelial cells and the mechanisms by which it causes toxicity in the kidney. The purpose of this review is to present the progress made on the mechanisms of cadmium transport in the kidney and the role of transporter proteins in cadmium-induced nephrotoxicity.

  4. Cadmium migration in aerospace nickel cadmium cells

    NASA Technical Reports Server (NTRS)

    Mcdermott, P. P.

    1976-01-01

    The effects of temperature, the nature of separator material, charge and discharge, carbonate contamination, and the mode of storage are studied with respect to the migration of active material from the negative toward the positive plate. A theoretical model is proposed which takes into account the solubility of cadmium in various concentrations of hydroxide and carbonate at different temperatures, the generation of the cadmiate ion, Cd(OH)3(-), during discharge, the migration of the cadmiate ion and particulate Cd(OH)2 due to electrophoretic effects and the movement of electrolyte in and out of the negative plate and, finally, the recrystallization of cadmiate ion in the separator as Cd(OH)2. Application of the theoretical model to observations of cadmium migration in cycled cells is also discussed.

  5. Plausible Mechanisms of Cadmium Carcinogenesis

    EPA Science Inventory

    Cadmium is a transition metal and an ubiquitous environmental and industrial pollutant. Laboratory animal studies and epidemiological studies have shown that exposure to cadmium is associated with various organ toxicities and carcinogenic effects. Several national and internation...

  6. N-doped mesoporous carbons supported palladium catalysts prepared from chitosan/silica/palladium gel beads.

    PubMed

    Zeng, Minfeng; Wang, Yudong; Liu, Qi; Yuan, Xia; Feng, Ruokun; Yang, Zhen; Qi, Chenze

    2016-08-01

    In this study, a heterogeneous catalyst including palladium nanoparticles supported on nitrogen-doped mesoporous carbon (Pd@N-C) is synthesized from palladium salts as palladium precursor, colloidal silica as template, and chitosan as carbon source. N2 sorption isotherm results show that the prepared Pd@N-C had a high BET surface area (640m(2)g(-1)) with large porosity. The prepared Pd@N-C is high nitrogen-rich as characterized with element analysis. X-ray photoelectron spectroscopy (XPS), high-resolution transmission electron microscopy (HR-TEM), and Raman spectroscopy characterization of the catalyst shows that the palladium species with different chemical states are well dispersed on the nitrogen-containing mesoporous carbon. The Pd@N-C is high active and shows excellent stability as applied in Heck coupling reactions. This work supplies a successful method to prepare Pd heterogeneous catalysts with high performance from bulk biopolymer/Pd to high porous nitrogen-doped carbon supported palladium catalytic materials. PMID:27155234

  7. Process for recovery of palladium from nuclear fuel reprocessing wastes

    DOEpatents

    Campbell, David O.; Buxton, Samuel R.

    1981-01-01

    Palladium is selectively removed from spent nuclear fuel reprocessing waste by adding sugar to a strong nitric acid solution of the waste to partially denitrate the solution and cause formation of an insoluble palladium compound. The process includes the steps of: (a) adjusting the nitric acid content of the starting solution to about 10 M, (b) adding 50% sucrose solution in an amount sufficient to effect the precipitation of the palladium compound, (c) heating the solution at reflux temperature until precipitation is complete, and (d) centrifuging the solution to separate the precipitated palladium compound from the supernatant liquid.

  8. Process for recovery of palladium from nuclear fuel reprocessing wastes

    DOEpatents

    Campbell, D.O.; Buxton, S.R.

    1980-06-16

    Palladium is selectively removed from spent nuclear fuel reprocessing waste by adding sugar to a strong nitric acid solution of the waste to partially denitrate the solution and cause formation of an insoluble palladium compound. The process includes the steps of: (a) adjusting the nitric acid content of the starting solution to about 10 M; (b) adding 50% sucrose solution in an amount sufficient to effect the precipitation of the palladium compound; (c) heating the solution at reflux temperature until precipitation is complete; and (d) centrifuging the solution to separate the precipitated palladium compound from the supernatant liquid.

  9. Optimization of silver-dielectric-silver nanoshell for sensing applications

    SciTech Connect

    Shirzaditabar, Farzad; Saliminasab, Maryam

    2013-08-15

    In this paper, resonance light scattering (RLS) properties of a silver-dielectric-silver nanoshell, based on quasi-static approach and plasmon hybridization theory, are investigated. Scattering spectrum of silver-dielectric-silver nanoshell has two intense and clearly separated RLS peaks and provides a potential for biosensing based on surface plasmon resonance and surface-enhanced Raman scattering. The two RLS peaks in silver-dielectric-silver nanoshell are optimized by tuning the geometrical dimensions. In addition, the optimal geometry is discussed to obtain the high sensitivity of silver-dielectric-silver nanoshell. As the silver core radius increases, the sensitivity of silver-dielectric-silver nanoshell decreases whereas increasing the middle dielectric thickness increases the sensitivity of silver-dielectric-silver nanoshell.

  10. Optimization of silver-dielectric-silver nanoshell for sensing applications

    NASA Astrophysics Data System (ADS)

    Shirzaditabar, Farzad; Saliminasab, Maryam

    2013-08-01

    In this paper, resonance light scattering (RLS) properties of a silver-dielectric-silver nanoshell, based on quasi-static approach and plasmon hybridization theory, are investigated. Scattering spectrum of silver-dielectric-silver nanoshell has two intense and clearly separated RLS peaks and provides a potential for biosensing based on surface plasmon resonance and surface-enhanced Raman scattering. The two RLS peaks in silver-dielectric-silver nanoshell are optimized by tuning the geometrical dimensions. In addition, the optimal geometry is discussed to obtain the high sensitivity of silver-dielectric-silver nanoshell. As the silver core radius increases, the sensitivity of silver-dielectric-silver nanoshell decreases whereas increasing the middle dielectric thickness increases the sensitivity of silver-dielectric-silver nanoshell.

  11. Kinetic Studies on the Palladium(II)-Catalyzed Oxidative Cross-Coupling of Thiophenes with Arylboron Compounds and Their Mechanistic Implications.

    PubMed

    Schnapperelle, Ingo; Breitenlechner, Stefan; Bach, Thorsten

    2015-12-01

    Reaction orders for the key components in the palladium(II)-catalyzed oxidative cross-coupling between phenylboronic acid and ethyl thiophen-3-yl acetate were obtained by the method of initial rates. It turned out that the reaction rate not only depended on the concentration of palladium trifluoroacetate (reaction order: 0.97) and phenylboronic acid (reaction order: 1.26), but also on the concentration of the thiophene (reaction order: 0.55) and silver oxide (reaction order: -1.27). NMR spectroscopy titration studies established the existence of 1:1 complexes between the silver salt and both phenylboronic acid and ethyl thiophen-3-yl acetate. A low inverse kinetic isotope effect (kH /kD =0.93) was determined upon employing the 4-deuterated isotopomer of ethyl thiophen-3-yl acetate and monitoring its reaction to the 4-phenyl-substituted product. A Hammett analysis performed with para-substituted 2-phenylthiophenes gave a negative ρ value for oxidative cross-coupling with phenylboronic acid. Based on the kinetic data and additional evidence, a mechanism is suggested that invokes transfer of the phenyl group from phenylboronic acid to a 1:1 complex of palladium trifluoroacetate and thiophene as the rate-determining step. Proposals for the structure of relevant intermediates are made and discussed. PMID:26515114

  12. Large-scale atomistic simulations of helium-3 bubble growth in complex palladium alloys

    DOE PAGES

    Hale, Lucas M.; Zimmerman, Jonathan A.; Wong, Bryan M.

    2016-05-18

    Palladium is an attractive material for hydrogen and hydrogen-isotope storage applications due to its properties of large storage density and high diffusion of lattice hydrogen. When considering tritium storage, the material’s structural and mechanical integrity is threatened by both the embrittlement effect of hydrogen and the creation and evolution of additional crystal defects (e.g., dislocations, stacking faults) caused by the formation and growth of helium-3 bubbles. Using recently developed inter-atomic potentials for the palladium-silver-hydrogen system, we perform large-scale atomistic simulations to examine the defect-mediated mechanisms that govern helium bubble growth. Our simulations show the evolution of a distribution of materialmore » defects, and we compare the material behavior displayed with expectations from experiment and theory. In conclusion, we also present density functional theory calculations to characterize ideal tensile and shear strengths for these materials, which enable the understanding of how and why our developed potentials either meet or confound these expectations.« less

  13. Large-scale atomistic simulations of helium-3 bubble growth in complex palladium alloys.

    PubMed

    Hale, Lucas M; Zimmerman, Jonathan A; Wong, Bryan M

    2016-05-21

    Palladium is an attractive material for hydrogen and hydrogen-isotope storage applications due to its properties of large storage density and high diffusion of lattice hydrogen. When considering tritium storage, the material's structural and mechanical integrity is threatened by both the embrittlement effect of hydrogen and the creation and evolution of additional crystal defects (e.g., dislocations, stacking faults) caused by the formation and growth of helium-3 bubbles. Using recently developed inter-atomic potentials for the palladium-silver-hydrogen system, we perform large-scale atomistic simulations to examine the defect-mediated mechanisms that govern helium bubble growth. Our simulations show the evolution of a distribution of material defects, and we compare the material behavior displayed with expectations from experiment and theory. We also present density functional theory calculations to characterize ideal tensile and shear strengths for these materials, which enable the understanding of how and why our developed potentials either meet or confound these expectations. PMID:27208963

  14. Platinum-ruthenium-palladium fuel cell electrocatalyst

    DOEpatents

    Gorer, Alexander

    2006-02-07

    A catalyst suitable for use in a fuel cell, especially as an anode catalyst, that contains platinum at a concentration that is between about 20 and about 60 atomic percent, ruthenium at a concentration that is between about 20 and about 60 atomic percent, palladium at a concentration that is between about 5 and about 45 atomic percent, and having an atomic ratio of platinum to ruthenium that is between about 0.7 and about 1.2. Alternatively, the catalyst may contain platinum at a concentration that is between about 25 and about 50 atomic percent, ruthenium at a concentration that is between about 25 and about 55 atomic percent, palladium at a concentration that is between about 5 and about 45 atomic percent, and having a difference between the concentrations of ruthenium and platinum that is no greater than about 20 atomic percent.

  15. Carbon Nanotube Interconnects Realized through Functionalization and Sintered Silver Attachment.

    PubMed

    Gopee, V; Thomas, O; Hunt, C; Stolojan, V; Allam, J; Silva, S R P

    2016-03-01

    Carbon nanotubes (CNTs) in the form of interconnects have many potential applications, and their ability to perform at high temperatures gives them a unique capability. We show the development of a novel transfer process using CNTs and sintered silver that offers a unique high-temperature, high-conductivity, and potentially flexible interconnect solution. Arrays of vertically aligned multiwalled carbon nanotubes of approximately 200 μm in length were grown on silicon substrates, using low-temperature photothermal chemical vapor deposition. Oxygen plasma treatment was used to introduce defects, in the form of hydroxyl, carbonyl, and carboxyl groups, on the walls of the carbon nanotubes so that they could bond to palladium (Pd). Nanoparticle silver was then used to bind the Pd-coated multiwalled CNTs to a copper substrate. The silver-CNT-silver interconnects were found to be ohmic conductors, with resistivity of 6.2 × 10(-4) Ωm; the interconnects were heated to temperatures exceeding 300 °C (where common solders fail) and were found to maintain their electrical performance. PMID:26835786

  16. Sample Characterization of Palladium Supported on Tetraphenylborate

    SciTech Connect

    Barnes, M.J.

    2001-04-04

    The primary objective of this research was to use XAFS spectroscopic techniques such as SANES and EXAFS to obtain information on Pd and Hg in samples that were potentially supported on KTPB and had been reacted with dissolved TPB and TPB decomposition products. This work was performed in support of the Small Tank Tetraphenylborate Salt Disposition Alternative program seeking to better understand the mechanism of palladium catalyzed tetraphenylborate decomposition.

  17. A recyclable perfluoroalkylated PCP pincer palladium complex.

    PubMed

    Duncan, Daniel; Hope, Eric G; Singh, Kuldip; Stuart, Alison M

    2011-03-01

    A new fluorous PCP pincer ligand has been coordinated to Ni(II), Pd(II) and Pt(II). The air stable palladium complex, which promotes Heck reactions between methyl acrylate and either aryl bromides or iodides, can be recovered intact by fluorous solid-phase extraction and was reused four times in the Heck reaction between methyl acrylate and 4-bromoacetophenone without loss in catalytic activity. PMID:21264422

  18. Hydrogen in magnesium palladium thin layer structures

    NASA Astrophysics Data System (ADS)

    Kruijtzer, G. L.

    2008-02-01

    In this thesis, the study of hydrogen storage, absorption and desorption in magnesium layers is described. The magnesium layers have a thickness of 50-500 nm and are covered by a palladium layer which acts as a hydrogen dissociation/association catalyst. The study was preformed under ultra high vacuum conditions to avoid oxygen contamination. The main analysis techniques were RBS, ERD and TDS.

  19. Organometallic palladium reagents for cysteine bioconjugation.

    PubMed

    Vinogradova, Ekaterina V; Zhang, Chi; Spokoyny, Alexander M; Pentelute, Bradley L; Buchwald, Stephen L

    2015-10-29

    Reactions based on transition metals have found wide use in organic synthesis, in particular for the functionalization of small molecules. However, there are very few reports of using transition-metal-based reactions to modify complex biomolecules, which is due to the need for stringent reaction conditions (for example, aqueous media, low temperature and mild pH) and the existence of multiple reactive functional groups found in biomolecules. Here we report that palladium(II) complexes can be used for efficient and highly selective cysteine conjugation (bioconjugation) reactions that are rapid and robust under a range of bio-compatible reaction conditions. The straightforward synthesis of the palladium reagents from diverse and easily accessible aryl halide and trifluoromethanesulfonate precursors makes the method highly practical, providing access to a large structural space for protein modification. The resulting aryl bioconjugates are stable towards acids, bases, oxidants and external thiol nucleophiles. The broad utility of the bioconjugation platform was further corroborated by the synthesis of new classes of stapled peptides and antibody-drug conjugates. These palladium complexes show potential as benchtop reagents for diverse bioconjugation applications.

  20. Discovery of Cadmium, Indium, and Tin Isotopes

    NASA Astrophysics Data System (ADS)

    Amos, Stephanie; Thoennessen, Michael

    2009-10-01

    As of today, no comprehensive study has been made covering the initial observations and identifications of isotopes. A project has been undertaken at MSU to document the discovery of all the known isotopes. The criteria defining discovery of a given isotope is the publication of clear mass and element assignment in a refereed journal. Prior to the current work the documentation of the discovery of eleven elements had been completed^1. These elements are cerium^2, arsenic, gold, tungsten, krypton, silver, vanadium, einsteinium, iron, barium, and cobalt. We will present the new documentation for the cadmium, indium, and tin isotopes. Thirty-seven cadmium isotopes, thirty-eight indium isotopes, and thirty-eight tin isotopes have been discovered so far. The description for each discovered isotope includes the year of discovery, the article published on the discovery, the article's author, the method of production, the method of identification, and any previous information concerning the isotope discovery. A summary and overview of all ˜500 isotopes documented so far as a function of discovery year, method and place will also be presented. ^1http://www.nscl.msu.edu/˜thoennes/2009/discovery.htm ^2J.Q. Ginepro, J. Snyder, and M. Thoennessen, At. Data Nucl. Data. Tables, in press (2009), doi:10.1016/j.adt.2009.06.002

  1. Platinum- and platinum alloy-coated palladium and palladium alloy particles and uses thereof

    DOEpatents

    Adzic, Radoslav; Zhang, Junliang; Mo, Yibo; Vukmirovic, Miomir Branko

    2010-04-06

    The present invention relates to particle and nanoparticle composites useful as oxygen-reduction electrocatalysts. The particle composites are composed of a palladium or palladium-alloy particle or nanoparticle substrate coated with an atomic submonolayer, monolayer, bilayer, or trilayer of zerovalent platinum atoms. The invention also relates to a catalyst and a fuel cell containing the particle or nanoparticle composites of the invention. The invention additionally includes methods for oxygen reduction and production of electrical energy by using the particle and nanoparticle composites of the invention.

  2. Reduced hydrogen cadmium plating

    SciTech Connect

    Hoeller, T.; Ross, L. ); Varma, R. ); Agarwala, V.S. )

    1991-01-01

    This paper demonstrates the advantages of using a periodic reverse pulse plating method, incorporating a fast cathodic pulse which is separated from the subsequent anodic/cathodic pulses by a long rest period in producing silvery cadmium coatings on steel from aqueous fluoroborate electrolyte. Also, the deposition obtained by combination of pulse currents and turbulent electrolyte flow system (forced convection of electrolyte, Re {approximately} 20-25,000) result in a near hydrogen-free electrodeposition of fine- grained cadmium. This is confirmed by the determination of diffusible hydrogen by the electrochemical (Barnach Electrode) method.

  3. [Acute and chronic cadmium poisoning].

    PubMed

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

    2010-02-01

    Cadmium is a metallic impurity in various minerals. The two main cadmium exposure sources in general population are food and tobacco smoking. Its industrial exploitation has grown in the early twentieth century. Cadmium is used in accumulators or alkaline batteries (80%) and in pigments for paints or plastics (10%), in electrolytic process by deposit or by cadmium plating on metals or to reduce melting points (welding rods...). Cadmium is a cumulative toxic substance whose half-time for elimination is about 20 to 40 years and it is mainly stored in the liver and kidneys. Inhalation of cadmium oxide fumes may cause inhalation fevers or chemical pneumonitis. Cadmium chronic poisoning causes mainly renal tubulopathy and could be the cause of osteomalacia and diffuse osteoporosis. Cadmium is classified as certain carcinogen agent for humans by International Agency for Research on Cancer (IARC). The most relevant biological index exposure is the urinary cadmium. According to literature, no chelating agent can be still used in human cadmium poisonings. In France, some diseases caused by occupational exposure to cadmium may be compensated.

  4. Cadmium-Aluminum Layered Double Hydroxide Microspheres for Photocatalytic CO2 Reduction.

    PubMed

    Saliba, Daniel; Ezzeddine, Alaa; Sougrat, Rachid; Khashab, Niveen M; Hmadeh, Mohamad; Al-Ghoul, Mazen

    2016-04-21

    We report the synthesis of cadmium-aluminum layered double hydroxide (CdAl LDH) using the reaction-diffusion framework. As the hydroxide anions diffuse into an agar gel matrix containing the mixture of aluminum and cadmium salts at a given ratio, they react to give the LDH. The LDH self-assembles inside the pores of the gel matrix into a unique spherical-porous shaped microstructure. The internal and external morphologies of the particles are studied by electron microscopy and tomography revealing interconnected channels and a high surface area. This material is shown to exhibit a promising performance in the photoreduction of carbon dioxide using solar light. Moreover, the palladium-decorated version shows a significant improvement in its reduction potential at room temperature. PMID:27028104

  5. Electrical properties of polyimides containing a near-surface deposit of silver

    NASA Technical Reports Server (NTRS)

    Rancourt, J. D.; Porta, G. M.; Taylor, L. T.

    1987-01-01

    Films containing a surface or near-surface deposit of palladium, gold or copper metal as well as tin, cobalt, copper, or lithium oxides have been prepared by dissolving appropriate metal salts into poly(amide-acid)/N,N-dimethylacetamide solutions and curing the solvent cast films to temperatures up to 300 C. This preparation technique has been extended to evaluate the thermal, spectroscopic, and electrical characteristics of condensation polyimide films modified with silver nitrate. A near-surface deposit of metallic silver results but the reflective surface has high electrical resistivity (sheet resistivity) due to a polymer coating or overlayer above the metal. Details pertaining to the silver nitrate modified condensation polyimides are presented. Also, the applicability of the structural model and electrical model previously proposed for the cobalt oxide system are assessed.

  6. Genetics Home Reference: Silver syndrome

    MedlinePlus

    ... Me Understand Genetics Home Health Conditions Silver syndrome Silver syndrome Enable Javascript to view the expand/collapse boxes. Download PDF Open All Close All Description Silver syndrome belongs to a group of genetic disorders ...

  7. Selective extraction of palladium(II) with theophylline derivatives.

    PubMed

    Kaikake, K; Baba, Y

    2001-03-01

    Theophylline derivatives with some kinds of alkyl chains were synthesized and used in extraction experiments involving metal ions. Theophylline derivatives have exhibited a high selectivity for palladium over other precious metals and base metals. The extraction of palladium from acidic chloride media has been investigated using theophylline derivatives (= RN) as extractants. Palladium(II) was found to be extracted with 7-octyltheophylline according to the following reaction: PdCl2 + 2RN <==> PdCl2(RN)2. The extraction equilibrium constant was determined to be K = 2.67 x 10(8) ( moldm(-3))(-2). In addition, the stripping of palladium was performed to an extent of 100% by a single batchwise treatment with a 1.0 mol dm(-3) ammonia solution. The stoichiometric relation in the extraction of palladium was supported by an analysis using mass spectrometry.

  8. Cadmium plating replacements

    NASA Technical Reports Server (NTRS)

    Nelson, Mary J.; Groshart, Earl C.

    1995-01-01

    The Boeing Company has been searching for replacements to cadmium plate. Two alloy plating systems seem close to meeting the needs of a cadmium replacement. The two alloys, zinc-nickel and tin-zinc are from alloy plating baths; both baths are neutral pH. The alloys meet the requirements for salt fog corrosion resistance, and both alloys excel as a paint base. Currently, tests are being performed on standard fasteners to compare zinc-nickel and tin-zinc on threaded hardware where cadmium is heavily used. The Hydrogen embrittlement propensity of the zinc-nickel bath has been tested, and just beginning for the tin-zinc bath. Another area of interest is the electrical properties on aluminum for tin-zinc and will be discussed. The zinc-nickel alloy plating bath is in production in Boeing Commercial Airplane Group for non-critical low strength steels. The outlook is promising that these two coatings will help The Boeing Company significantly reduce its dependence on cadmium plating.

  9. Cadmium-induced osteomalacia.

    PubMed Central

    Blainey, J D; Adams, R G; Brewer, D B; Harvey, T C

    1980-01-01

    The detailed study of a battery plate maker, who had worked with cadmium for 36 years, showed that proteinuria, typical of renal tubular dysfunction, had been observed for 25 years and during the last 12 years of his life the patient had suffered increasing disability from gross bone disease. Several bone biopsies and detailed metabolic studies showed typical severe osteomalacia, which responded well initially to calcium and vitamin D treatment. Examination of the liver both in life and after death showed a gross excess of cadmium. This was also found in the kidneys after death. Previously unreported changes were present in the bones, especially the lumbar vertebrae which were probably more the result of gross bone deformity than cadmium deposition. The mechanism of development of the severe acquired Fanconi syndrome was thought to be a combination of dietary calcium and vitamin D deficiency and impaired calcium absorption from abnormal vitamin D synthesis, related to the cadmium deposition in the renal tubules, which also caused the defect in renal tubular reabsorption. Images PMID:7426480

  10. CADMIUM PHOSPHATE GLASS

    DOEpatents

    Carpenter, H.W.; Johnson, P.D.

    1963-04-01

    A method of preparing a cadmium phosphate glass that comprises providing a mixture of solid inorganic compounds of cadmuim and phosphate having vaporizable components and heating the resulting composition to a temperature of at least 850 un. Concent 85% C is presented. (AEC)

  11. A Silver Opportunity.

    ERIC Educational Resources Information Center

    Desser, Debra M.

    1996-01-01

    Presents an assignment that involves forming student companies to determine and defend cost estimates for producing a silver Oscar statuette. Includes an assessment rubric for cooperative effort. (JRH)

  12. Dosimetry using silver salts

    DOEpatents

    Warner, Benjamin P.

    2003-06-24

    The present invention provides a method for detecting ionizing radiation. Exposure of silver salt AgX to ionizing radiation results in the partial reduction of the salt to a mixture of silver salt and silver metal. The mixture is further reduced by a reducing agent, which causes the production of acid (HX) and the oxidized form of the reducing agent (R). Detection of HX indicates that the silver salt has been exposed to ionizing radiation. The oxidized form of the reducing agent (R) may also be detected. The invention also includes dosimeters employing the above method for detecting ionizing radiation.

  13. Chelating agents and cadmium intoxication

    SciTech Connect

    Shinobu, L.A.

    1985-01-01

    A wide range of conventional chelating agents have been screened for (a) antidotal activity in acute cadmium poisoning and (b) ability to reduce aged liver and kidney deposits of cadmium. Chelating agents belonging to the dithiocarbamate class have been synthesized and tested in both the acute and chronic modes of cadmium intoxication. Several dithiocarbamates, not only provide antidotal rescue, but also substantially decrease the intracellular deposits of cadmium associated with chronic cadmium intoxication. Fractionating the cytosol from the livers and kidneys of control and treated animals by Sephadex G-25 gel filtration clearly demonstrates that the dithiocarbamates are reducing the level of metallothionein-bound cadmium. However, the results of cell culture (Ehrlich ascites) studies designed to investigate the removal of cadmium from metallothionein and subsequent transport of the resultant cadmium complex across the cell membrane were inconclusive. In other in vitro investigations, the interaction between isolated native Cd, Zn-metallothionein and several chelating agents was explored. Ultracentrifugation, equilibrium dialysis, and Sephadex G-25 gel filtration studies have been carried out in an attempt to determine the rate of removal of cadmium from metallothionein by these small molecules. Chemical shifts for the relevant cadmium-dithiocarbamate complexes have been determined using natural abundance Cd-NMR.

  14. On the optimum conditions for the reduction of nitrate to nitrite by cadmium.

    PubMed

    Nydahl, F

    1976-05-01

    The variables of direct importance in the reduction of nitrate to nitrite by a metallic reductant such as cadmium used in a reductor column are discussed with special reference to the determination of nitrate as nitrite in very dilute solutions, e.g., natural waters. As a result of these considerations the effect of flow-rate (expressed as bed-volumes min ), pH, temperature, chloride concentration and various types of reductor cadmium on the yield of nitrite is investigated. The effect of dissolved oxygen in the sample solution on pH and cadmium concentration in the reduced solution is demonstrated. At constant pH a maximum yield of nitrite is obtained at a certain flow-rate, which is explained as the result of a rapid formation and simultaneously proceeding slow reduction of nitrite. With increasing pH this maximum is shifted to lower flow-rates, and grows broader whilst the yield at maximum approaches 100%; at pH 9.5 a yield of 99.9 +/- 0.1% is obtained. The temperature has little effect on the reduction rate in the interval 20-30 degrees but at 10 degrees the reduction is noticeably slower. Chloride ions have a strongly retarding effect on the reduction rate but the yield at maximum is not affected. Electrolytically precipitated cadmium, filings of pure cadmium or amalgamated pure cadmium all give practically the same yield at maximum though some differences in reduction rate are observed. Impure cadmium or copper-cadmium and silver-cadmium, owing to the formation of galvanic cells with higher reducing power, give a high reduction rate, which also applies to nitrite, causing a poorer yield at maximum. The practical consequences of the results are thoroughly discussed.

  15. On the optimum conditions for the reduction of nitrate to nitrite by cadmium.

    PubMed

    Nydahl, F

    1976-05-01

    The variables of direct importance in the reduction of nitrate to nitrite by a metallic reductant such as cadmium used in a reductor column are discussed with special reference to the determination of nitrate as nitrite in very dilute solutions, e.g., natural waters. As a result of these considerations the effect of flow-rate (expressed as bed-volumes min ), pH, temperature, chloride concentration and various types of reductor cadmium on the yield of nitrite is investigated. The effect of dissolved oxygen in the sample solution on pH and cadmium concentration in the reduced solution is demonstrated. At constant pH a maximum yield of nitrite is obtained at a certain flow-rate, which is explained as the result of a rapid formation and simultaneously proceeding slow reduction of nitrite. With increasing pH this maximum is shifted to lower flow-rates, and grows broader whilst the yield at maximum approaches 100%; at pH 9.5 a yield of 99.9 +/- 0.1% is obtained. The temperature has little effect on the reduction rate in the interval 20-30 degrees but at 10 degrees the reduction is noticeably slower. Chloride ions have a strongly retarding effect on the reduction rate but the yield at maximum is not affected. Electrolytically precipitated cadmium, filings of pure cadmium or amalgamated pure cadmium all give practically the same yield at maximum though some differences in reduction rate are observed. Impure cadmium or copper-cadmium and silver-cadmium, owing to the formation of galvanic cells with higher reducing power, give a high reduction rate, which also applies to nitrite, causing a poorer yield at maximum. The practical consequences of the results are thoroughly discussed. PMID:18961874

  16. The silver ions contribution into the cytotoxic activity of silver and silver halides nanoparticles

    NASA Astrophysics Data System (ADS)

    Klimov, A. I.; Zherebin, P. M.; Gusev, A. A.; Kudrinskiy, A. A.; Krutyakov, Y. A.

    2015-11-01

    The biocidal action of silver nanoparticles capped with sodium citrate and silver halides nanoparticles capped with non-ionic surfactant polyoxyethylene(20)sorbitan monooleate (Tween 80®) against yeast cells Saccharomyces cerevisiae was compared to the effect produced by silver nitrate and studied through the measurement of cell loss and kinetics of K+ efflux from the cells. The cytotoxicity of the obtained colloids was strongly correlated with silver ion content in the dispersions. The results clearly indicated that silver and silver halides nanoparticles destroyed yeast cells through the intermediate producing of silver ions either by dissolving of salts or by oxidation of silver.

  17. Californium--palladium metal neutron source material

    DOEpatents

    Dahlen, B.L.; Mosly, W.C. Jr.; Smith, P.K.; Albenesius, E.L.

    1974-01-22

    Californium, as metal or oxide, is uniformly dispersed throughout a noble metal matrix, provided in compact, rod or wire form. A solution of californium values is added to palladium metal powder, dried, blended and pressed into a compact having a uni-form distribution of californium. The californium values are decomposed to californium oxide or metal by heating in an inert or reducing atmosphere. Sintering the compact to a high density closes the matrix around the dispersed californium. The sintered compact is then mechanically shaped into an elongated rod or wire form. (4 claims, no drawings) (Official Gazette)

  18. Direct Observation of Paramagnons in Palladium

    SciTech Connect

    Doubble, R.; Hayden, S M.; Dai, Pengcheng; Mook Jr, Herbert A; Thompson, James R; Frost, C.

    2010-01-01

    We report an inelastic neutron scattering study of the spin fluctuations in the nearly ferromagnetic element palladium. Dispersive over-damped collective magnetic excitations or 'paramagnons' are observed up to 128 meV. We analyze our results in terms of a Moriya-Lonzarich-type spin-fluctuation model and estimate the contribution of the spin fluctuations to the low-temperature heat capacity. In spite of the paramagnon excitations being relatively strong, their relaxation rates are large. This leads to a small contribution to the low-temperature electronic specific heat.

  19. The Silver Bullet Syndrome.

    ERIC Educational Resources Information Center

    Dehne, George C.

    1995-01-01

    Many colleges address complex problems with a single "silver bullet" strategy. Because value shifts according to the consumer's situation or goal, private colleges should become more aware of their "situational value" and exploit it. This requires an understanding of how students choose colleges. In contrast, popular silver bullets target…

  20. Palladium-defect complexes in diamond and silicon carbide

    NASA Astrophysics Data System (ADS)

    Abiona, A. A.; Kemp, W.; Timmers, H.; Bharuth-Ram, K.

    2015-04-01

    Time Differential Perturbed Angular Correlations (TDPAC) studies, supported by Density Functional Theory (DFT) modelling, have shown that palladium atoms in silicon and germanium pair with vacancies. Building on these results, here we present DFT predictions and some tentative TDPAC results on palladium-defect complexes and site locations of palladium impurities in diamond and silicon carbide. For both diamond and silicon carbide, the DFT calculations predict that a split-vacancy V-PdBI-V complex is favoured, with the palladium atom on a bond-centred interstitial site having a nearest-neighbour semi-vacancy on either side. Consistent with experimental results, this configuration is also assigned to palladium complexes in silicon and germanium. For silicon carbide, the DFT modelling predicts furthermore that a palladium atom in replacing a carbon atom moves to a bond-centred interstitial site and pairs with a silicon vacancy to form a complex that is more stable than that of a palladium atom which replaces a silicon atom and then moves to a bond-centred interstitial site pairings with a carbon vacancy. These two competing alternatives differ by 8.94 eV. The favourable pairing with a silicon vacancy is also supported independently by TRIM Monte Carlo calculations, which predict that more silicon vacancies than carbon vacancies are created during heavy ion. implantation.

  1. High concentration of deuterium in palladium from plasma ion implantation

    SciTech Connect

    Uhm, H.S.; Lee, W.M. )

    1991-11-01

    Based on a theoretical calculation, a new scheme to increase deuterium density in palladium over its initial value is presented. This deuterium enrichment scheme makes use of plasma ion implantation. A cylindrical palladium rod (target) preloaded with deuterium atoms, coated with a diffusion-barrier material, is immersed in a deuterium plasma. The palladium rod is connected to a high-power modulator which provides a series of negative-voltage pulses. During these negative pulses, deuterium ions fall into the target, penetrate the diffusion barrier, and are implanted inside the palladium. For reasonable system parameters allowed by present technology, it is found from theoretical calculations that the saturation deuterium density after prolonged ion implantation can be several times the palladium atomic number density. Assuming an initial deuterium density, {ital n}{sub 0}=4{times}10{sup 22} cm{sup {minus}3}, it is also found that the deuterium density in palladium can triple its original value within a few days of the ion implantation for a reasonable target size. Because of the small diffusion coefficient in palladium, the incoming ions do not diffuse quickly inward, thereby accumulating near the target surface at the beginning of the implantation.

  2. Method for the recovery of silver from silver zeolite

    DOEpatents

    Reimann, George A.

    1986-01-01

    High purity silver is recovered from silver exchanged zeolite used to capture radioactive iodine from nuclear reactor and nuclear fuel reprocessing environments. The silver exchanged zeolite is heated with slag formers to melt and fluidize the zeolite and release the silver, the radioactivity removing with the slag. The silver containing metallic impurities is remelted and treated with oxygen and a flux to remove the metal impurities. About 98% of the silver in the silver exchanged zeolite having a purity of 99% or better is recoverable by the method.

  3. Method for the recovery of silver from silver zeolite

    DOEpatents

    Reimann, G.A.

    1985-03-05

    High purity silver is recovered from silver exchanged zeolite used to capture radioactive iodine from nuclear reactor and nuclear fuel reprocessing environments. The silver exchanged zeolite is heated with slag formers to melt and fluidize the zeolite and release the silver, the radioactivity removing with the slag. The silver containing metallic impurities is remelted and treated with oxygen and a flux to remove the metal impurities. About 98% of the silver in the silver exchanged zeolite having a purity of 99% or better is recoverable by the method.

  4. Cadmium biosorption by Saccharomyces cerevisiae

    SciTech Connect

    Volesky, B.; May, H.; Holan, Z.R. )

    1993-04-01

    Cadmium uptake by nonliving and resting cells of Saccharomyces cerevisiae obtained from aerobic or anaerobic cultures from pure cadmium-bearing solutions was examined. The highest cadmium uptake exceeding 70 mg Cd/g was observed with aerobic baker's yeast biomass from the exponential growth phase. Nearly linear sorption isotherms featured by higher sorbing resting cells together with metal deposits localized exclusively in vacuoles indicate the possibility of a different metal-sequestering mechanism when compared to dry nonliving yeasts which did not usually accumulate more than 20 mg Cd/g. The uptake of cadmium was relatively fast, 75% of the sorption completed in less than 5 min.

  5. Silver-zinc: status of technology and applications

    NASA Astrophysics Data System (ADS)

    Karpinski, A. P.; Makovetski, B.; Russell, S. J.; Serenyi, J. R.; Williams, D. C.

    Michel Yardney and Professor Henri André developed the first practical silver-zinc battery more than 55 years ago. Since then, primary and rechargeable silver-zinc batteries have attracted a variety of applications due to their high specific energy/energy density, proven reliability and safety, and the highest power output per unit weight and volume of all commercially available batteries. Although significant improvements have been achieved on traditional systems such as lead-acid and nickel/cadmium, and in spite of the advent of new electrochemistries such as lithium-ion and nickel/metal hydride, many users still rely on silver-zinc to satisfy their most demanding and critical requirements. Over the past few years, several of the internal components have been subject to many studies which resulted in significant improvements in the battery wet life and cycle life. Specifically, these include new separator materials which offer an alternative to the cellulosic membranes, improvements to the zinc electrode that include additives that help reduce shape-change and dendritic growth, and to a lesser extent, process changes to the silver electrode and additives to the electrolyte. In comparison, the commonly used secondary systems are lead-acid, nickel/cadmium, nickel/metal hydride, and lithium-ion. Each has attributes which make them desirable for certain applications. Where low cost, high voltage, and high rate capability is required, the lead-acid battery is an obvious choice whenever size and weight are not critical. For applications requiring longer wet life, moderate rate capability, and high cycle life, nickel/cadmium or nickel/metal hydride can be used in spite of their poor charge retention and higher costs. Relatively newer systems are also available such as lithium-ion or lithium polymer technology which are preferred for their high voltage and excellent cycle life. Among the disadvantages of these systems are higher costs, limited configurations (usually

  6. Silver(II) Oxide or Silver(I,III) Oxide?

    ERIC Educational Resources Information Center

    Tudela, David

    2008-01-01

    The often called silver peroxide and silver(II) oxide, AgO or Ag[subscript 2]O[subscript 2], is actually a mixed oxidation state silver(I,III) oxide. A thermochemical cycle, with lattice energies calculated within the "volume-based" thermodynamic approach, explain why the silver(I,III) oxide is more stable than the hypothetical silver(II) oxide.…

  7. Mineral commodity profiles: Silver

    USGS Publications Warehouse

    Butterman, W.C.; Hilliard, Henry E.

    2005-01-01

    Overview -- Silver is one of the eight precious, or noble, metals; the others are gold and the six platinum-group metals (PGM). World mine production in 2001 was 18,700 metric tons (t) and came from mines in 60 countries; the 10 leading producing countries accounted for 86 percent of the total. The largest producer was Mexico, followed by Peru, Australia, and the United States. About 25 percent of the silver mined in the world in 2001 came from silver ores; 15 percent, from gold ores and the remaining 60 percent, from copper, lead, and zinc ores. In the United States, 14 percent of the silver mined in 2001 came from silver ores; 39 percent, from gold ores; 10 percent, from copper and copper-molybdenum ores; and 37 percent, from lead, zinc, and lead-zinc ores. The precious metal ores (gold and silver) came from 30 lode mines and 10 placer mines; the base-metal ores (copper, lead, molybdenum, and zinc) came from 24 lode mines. Placer mines yielded less than 1 percent of the national silver production. Silver was mined in 12 States, of which Nevada was by far the largest producer; it accounted for nearly one-third of the national total. The production of silver at domestic mines generated employment for about 1,100 mine and mill workers. The value of mined domestic silver was estimated to be $290 million. Of the nearly 27,000 t of world silver that was fabricated in 2001, about one-third went into jewelry and silverware, one-fourth into the light-sensitive compounds used in photography, and nearly all the remainder went for industrial uses, of which there were 7 substantial uses and many other small-volume uses. By comparison, 85 percent of the silver used in the United States went to photography and industrial uses, 8 percent to jewelry and silverware, and 7 percent to coins and medals. The United States was the largest consumer of silver followed by India, Japan, and Italy; the 13 largest consuming countries accounted for nearly 90 percent of the world total. In the

  8. Tritium evolution from various morphologies of palladium

    SciTech Connect

    Tuggle, D.G.; Claytor, T.N.; Taylor, S.F. |

    1994-04-01

    The authors have been able to extend the tritium production techniques to various novel morphologies of palladium. These include small solid wires of various diameters and a type of pressed powder wire and a plasma cell. In most successful experiments, the amount of palladium required, for an equivalent tritium output, has been reduced by a factor of 100 over the older powder methods. In addition, they have observed rates of tritium production (>5 nCi/h) that far exceed most of the previous results. Unfortunately, the methods that they currently use to obtain the tritium are poorly understood and consequently there are numerous variables that need to be investigated before the new methods are as reliable and repeatable as the previous techniques. For instance, it seems that surface and/or bulk impurities play a major role in the successful generation of any tritium. In those samples with total impurity concentrations of >400 ppM essentially no tritium has been generated by the gas loading and electrical simulation methods.

  9. Principal Locations of Metal Loading from Flood-Plain Tailings, Lower Silver Creek, Utah, April 2004

    USGS Publications Warehouse

    Kimball, Briant A.; Runkel, Robert L.; Walton-Day, Katherine

    2007-01-01

    Because of the historical deposition of mill tailings in flood plains, the process of determining total maximum daily loads for streams in an area like the Park City mining district of Utah is complicated. Understanding the locations of metal loading to Silver Creek and the relative importance of these locations is necessary to make science-based decisions. Application of tracer-injection and synoptic-sampling techniques provided a means to quantify and rank the many possible source areas. A mass-loading study was conducted along a 10,000-meter reach of Silver Creek, Utah, in April 2004. Mass-loading profiles based on spatially detailed discharge and chemical data indicated five principal locations of metal loading. These five locations contributed more than 60 percent of the cadmium and zinc loads to Silver Creek along the study reach and can be considered locations where remediation efforts could have the greatest effect upon improvement of water quality in Silver Creek.

  10. Targeted silver nanoparticles for ratiometric cell phenotyping

    NASA Astrophysics Data System (ADS)

    Willmore, Anne-Mari A.; Simón-Gracia, Lorena; Toome, Kadri; Paiste, Päärn; Kotamraju, Venkata Ramana; Mölder, Tarmo; Sugahara, Kazuki N.; Ruoslahti, Erkki; Braun, Gary B.; Teesalu, Tambet

    2016-04-01

    Affinity targeting is used to deliver nanoparticles to cells and tissues. For efficient targeting, it is critical to consider the expression and accessibility of the relevant receptors in the target cells. Here, we describe isotopically barcoded silver nanoparticles (AgNPs) as a tool for auditing affinity ligand receptors in cells. Tumor penetrating peptide RPARPAR (receptor: NRP-1) and tumor homing peptide GKRK (receptor: p32) were used as affinity ligands on the AgNPs. The binding and uptake of the peptide-functionalized AgNPs by cultured PPC-1 prostate cancer and M21 melanoma cells was dependent on the cell surface expression of the cognate peptide receptors. Barcoded peptide-functionalized AgNPs were synthesized from silver and palladium isotopes. The cells were incubated with a cocktail of the barcoded nanoparticles [RPARPAR (R), GKRK (K), and control], and cellular binding and internalization of each type of nanoparticle was assessed by inductively coupled plasma mass spectrometry. The results of isotopic analysis were in agreement with data obtained using optical methods. Using ratiometric measurements, we were able to classify the PPC-1 cell line as mainly NRP-1-positive, with 75 +/- 5% R-AgNP uptake, and the M21 cell line as only p32-positive, with 89 +/- 9% K-AgNP uptake. The isotopically barcoded multiplexed AgNPs are useful as an in vitro ratiometric phenotyping tool and have potential uses in functional evaluation of the expression of accessible homing peptide receptors in vivo.Affinity targeting is used to deliver nanoparticles to cells and tissues. For efficient targeting, it is critical to consider the expression and accessibility of the relevant receptors in the target cells. Here, we describe isotopically barcoded silver nanoparticles (AgNPs) as a tool for auditing affinity ligand receptors in cells. Tumor penetrating peptide RPARPAR (receptor: NRP-1) and tumor homing peptide GKRK (receptor: p32) were used as affinity ligands on the AgNPs. The

  11. Analysis of 12 AH aerospace nickel-cadmium cells from the design variable program

    NASA Technical Reports Server (NTRS)

    Vasanth, Kunigahalli L.; Morrow, George

    1987-01-01

    The Design Variable Program of NASA/GSFC provided a systematic approach to evaluate the performance of 12 Ampere-Hour Nickel-Cadmium cells of different designs. Design Variables tested in this program included teflonated negative plates, silver treated negative plates, lightly loaded negative plates, positive plates with no cadmium treatment, plate design of 1968 utilizing old and new processing techniques and electrochemically impregnated positive plates. These cells were life cycled in a Low-Earth Orbit (LEO) regime for 3 to 4 years. Representative cells taken from the Design Variable Program were examined via chemical, electrochemical and surface analyses. The results indicate the following: (1) positive swelling and carbonate content in the electrolyte increase as a function of number of cycles; (2) electrolyte distribution follows a general order NEG greater than POS greater than SEP; (3) control and No PQ groups outperformed the rest of the groups; and (4) the polyproylene group exhibited heavy cadmium migration and poor performance.

  12. Regulation of expression of an auxin-induced soybean sequence by cadmium

    SciTech Connect

    Hagen, G.; Uhrhammer, N.; Guilfoyle, T.J.

    1988-05-05

    An auxin-regulated soybean sequence has been characterized and shown to be induced by the heavy metals cadmium, silver, and copper. Cadmium induces the accumulation of two size classes of mRNA: a 1-kilobase (kb) RNA class, which is the same size as the RNA class induced by auxin, silver, and copper, and a 1.4-kb RNA class. DNA sequences analysis of cDNA clones and a soybean genomic fragment has shown the presence of an intron in this gene. A restriction fragment probe isolated from the intron segment hybridizes specifically to the 1.4-kb mRNA. The transcription rate of this sequences is rapidly increased following exposure of soybean primary leaves to cadmium, as assayed by nuclear run-off transcription experiments. These results suggest that cadmium not only induces the transcription of a specific soybean sequences, but interferes with the processing of the precursor mRNA, resulting in the accumulation of the 1.4-kb mRNA precursor species.

  13. The distribution of palladium in a Pd-modified 4130 steel

    NASA Astrophysics Data System (ADS)

    Miller, M. K.; Brenner, S. S.; Burke, M. G.

    1987-05-01

    The addition of palladium to a 4130 steel reduces its sensitivity to stress corrosion cracking and to hydrogen-induced cracking. The atom probe field-ion microscope has been used to study the microstructure and microchemistry of these palladium-modified 4130 steels with particular emphasis on the distribution of palladium between the various phases and internal interfaces. The palladium was found to segregate to the ferrite-ferrite lath boundaries to form a mono-atomically thick adsorbate layer. Palladium-manganese precipitates both at the lath boundaries and in the ferrite matrix were also detected. Most of the palladium was found to remain in solution in the ferrite.

  14. Crossover behavior in hydrogen sensing mechanism for palladium ultrathin films.

    SciTech Connect

    Darling, S. B.; Ramanathan, M.; Skudlarek, G.; Wang, H. H.; Illinois Math and Science Academy

    2010-01-01

    Palladium has been extensively studied as a material for hydrogen sensors because of the simplicity of its reversible resistance change when exposed to hydrogen gas. Various palladium films and nanostructures have been used, and different responses have been observed with these diverse morphologies. In some cases, such as with nanowires, the resistance will decrease, whereas in others, such as with thick films, the resistance will increase. Each of these mechanisms has been explored for several palladium structures, but the crossover between them has not been systematically investigated. Here we report on a study aimed at deciphering the nanostructure-property relationships of ultrathin palladium films used as hydrogen gas sensors. The crossover in these films is observed at a thickness of {approx} 5 nm. Ramifications for future sensor developments are discussed.

  15. Palladium-based electrocatalysts and fuel cells employing such electrocatalysts

    DOEpatents

    Masel; Richard I. , Zhu; Yimin , Larsen; Robert T.

    2010-08-31

    A direct organic fuel cell includes a fluid fuel comprising formic acid, an anode having an electrocatalyst comprising palladium nanoparticles, a fluid oxidant, a cathode electrically connected to the anode, and an electrolyte interposed between the anode and the cathode.

  16. Gold over Branched Palladium Nanostructures for Photothermal Cancer Therapy.

    PubMed

    McGrath, Andrew J; Chien, Yi-Hsin; Cheong, Soshan; Herman, David A J; Watt, John; Henning, Anna M; Gloag, Lucy; Yeh, Chen-Sheng; Tilley, Richard D

    2015-12-22

    Bimetallic nanostructures show exciting potential as materials for effective photothermal hyperthermia therapy. We report the seed-mediated synthesis of palladium-gold (Pd-Au) nanostructures containing multiple gold nanocrystals on highly branched palladium seeds. The nanostructures were synthesized via the addition of a gold precursor to a palladium seed solution in the presence of oleylamine, which acts as both a reducing and a stabilizing agent. The interaction and the electronic coupling between gold nanocrystals and between palladium and gold broadened and red-shifted the localized surface plasmon resonance absorption maximum of the gold nanocrystals into the near-infrared region, to give enhanced suitability for photothermal hyperthermia therapy. Pd-Au heterostructures irradiated with an 808 nm laser light caused destruction of HeLa cancer cells in vitro, as well as complete destruction of tumor xenographs in mouse models in vivo for effective photothermal hyperthermia.

  17. Preparation and characterization of polyaniline-palladium composite films

    SciTech Connect

    Li, H.S.; Josowicz, M.; Baer, D.R.; Engelhard, M.H.; Janata, J.

    1995-03-01

    Palladium is a preeminent material for the preparation of sensors for hydrogen and hydrogen-evolving compounds. Conducting polyaniline can be chemically or electrochemically functionalized by the incorporation of palladium clusters. Different interfaces in a three-dimensional matrix for hydrogen adsorption, desorption, and evolution were synthesized and characterized. Dispersions of palladium clusters in the polymer film were formed by various preparation routes, which can be classified as one or two-step processes. In the one-step process, the composite material was obtained during the electrosynthesis of polyaniline film. In the two-step processes, Pd aggregated into the polyaniline modified electrode. Electrochemical examination, x-ray photoelectron spectroscopy, and Auger electron spectroscopy have been employed to characterize the composite materials in view of the hydrogen sorption and evolution as well as the binding energy stale and the spatial distribution of the palladium clusters in polyaniline film.

  18. Parametric formulation of the dielectric function of palladium and palladium hydride thin films.

    PubMed

    Vargas, William E; Azofeifa, Daniel E; Clark, Neville; Solis, Hugo; Montealegre, Felipe; Cambronero, Michael

    2014-08-20

    A parametric description of the dielectric function of Pd thin films with thicknesses between 10 and 30 nm is reported. These films were grown at room temperature on amorphous quartz substrates by electron beam evaporation, with a base pressure of 7.0×10(-7)  mbar. By using nonpolarized normal incident light, transmission spectra were measured for wavelengths between 240 and 1050 nm. Inversion of the spectra by means of a projected gradient method enables us to obtain the mean dielectric function of the Pd grains in the films. We follow the Brendel-Bormann model to describe the frequency dependence of the dielectric function, with the plasma frequency, collision frequency, and screening factor as parameters in the free electron term. The contributions of bound electrons and their interband transitions, described in terms of Lorentz oscillators, involve the resonance frequencies, decay times, strengths, and Gaussian widths as parameters of the model. All these parameters have been optimized from the Pd grains' dielectric function, which fits the transmission spectra. A similar procedure was followed for Pd films exposed to a hydrogen atmosphere close to one bar. Thus, the dielectric functions of palladium and palladium hydride can easily be calculated through spectral ranges covering near-ultraviolet, visible, and near-infrared wavelengths. This can be used to model the behavior of nano-sized structures in which palladium particles or thin films are exposed to hydrogen pressures close to one bar.

  19. Synthesis of silver nanoparticles by electron irradiation of silver acetate

    NASA Astrophysics Data System (ADS)

    Li, Yue; Kim, Yong Nam; Lee, Eun Je; Cai, Wei Ping; Cho, Sung Oh

    2006-10-01

    A novel and facile route to synthesize crystalline silver nanoparticles is presented, which is based on electron irradiation technique. Only by irradiating an electron beam onto silver acetate precursor material, silver nanocrystals with the sizes of 15-40 nm were synthesized. The morphology and chemical composition of the irradiated samples were characterized by SEM, TEM, XRD and EELS. The precursor material was decomposed by the energetic electrons and consequently the chemical composition of the material was changed. As the electron fluence was gradually increased, the precursor was converted to silver (I) oxide and finally into silver nanocrystals. Thus, besides silver nanoparticles, silver oxide film can also be synthesized using the electron irradiation technique by controlling the electron fluence. The technique can be useful for mass production of silver nanoparticles and for patterned silver nanoparticle film.

  20. FASTGAS: Fast Gas Sampling for palladium exchange tests

    SciTech Connect

    Malinowski, M.E.; Stewart, K.D.; VerBerkmoes, A.A.

    1991-06-01

    A mass spectrometric technique for measuring the composition of gas flows in rapid H/D exchange reactions in palladium compacts has been developed. This method, called FASTGAS (Fast Gas Sampling)'' has been used at atmospheric pressures and above with a time response of better than 100 ms. The current implementation of the FASTGAS technique is described in detail and examples of its application to palladium hydride exchange tests are given. 12 refs., 10 figs.

  1. Method of forming supported doped palladium containing oxidation catalysts

    SciTech Connect

    Mohajeri, Nahid

    2014-04-22

    A method of forming a supported oxidation catalyst includes providing a support comprising a metal oxide or a metal salt, and depositing first palladium compound particles and second precious metal group (PMG) metal particles on the support while in a liquid phase including at least one solvent to form mixed metal comprising particles on the support. The PMG metal is not palladium. The mixed metal particles on the support are separated from the liquid phase to provide the supported oxidation catalyst.

  2. Design and fabrication of silver-hydrogen cells

    NASA Technical Reports Server (NTRS)

    Klein, M. G.

    1975-01-01

    The design and fabrication of silver-hydrogen secondary cells capable of delivering higher energy densities than comparable nickel-cadmium and nickel-hydrogen cells and relatively high cycle life is presented. An experimental task utilizing single electrode pairs for the optimization of the individual electrode components, the preparation of a design for lightweight 20Ahr cells, and the fabrication of four 20Ahr cells in heavy wall test housing containing electrode stacks of the lightweight design are described. The design approach is based on the use of a single cylindrical self-contained cell with a stacked disc sequence of electrodes. The electrode stack design is based on the use of NASA- Astropower Separator Material, PPF fuel cell anodes, an intercell electrolyte reservoir concept and sintered silver electrodes. Results of performance tests are given.

  3. Silver recovery system data

    SciTech Connect

    Boulineau, B.

    1991-08-26

    In August of 1990 the Savannah River Site Photography Group began testing on a different type of silver recovery system. This paper describes the baseline study and the different phases of installation and testing of the system.

  4. Give silver a shine.

    PubMed

    Fromm, Katharina M

    2011-02-01

    Katharina M. Fromm explains how, as well as catalysis and jewellery, silver serves a myriad of medicinal applications--some of which are even behind poetic traditions such as throwing coins in wishing wells. PMID:21258393

  5. Electrochemical behavior of silver sulfide

    SciTech Connect

    Drouven, B.U.E.

    1982-01-01

    The electrochemical behavior of silver sulfide in sulfuric acid as well as in nitric acid was studied using electrodes made from synthetic silver sulfide. The primary techniques used were potentiostatic, potentiodynamic, galvanostatic and corrosion cell experiments. The cathodic reaction of silver sulfide produces silver and hydrogen sulfide. This reaction mechanism is a sequential two step charge transfer involving a single electron in each step. Silver ions are produced from silver sulfide upon applying an anodic potential. The dissolution rate of silver sulfide can be so high that the formation of silver sulfate occurs which partially covers the silver sulfide surface and inhibits a further rate increase. The sulfur from the silver sulfide will be oxidized at low overpotentials to elemental sulfur; at high overpotentials, the oxidation to sulfate or bisulfate is observed. The results suggest that the catalysis of chalcopyrite by the addition of silver ions is caused by the formation and subsequent dissolution of silver sulfide leaving a porous layer behind. The understanding of the reaction mechanism of silver sulfide dissolution and its optimization will significantly improve the economic evaluation of industrial processes using the catalyzed leaching of chalcopyrite. The present knowledge of the catalysis indicates that other ions may be substituted for silver ions which would increase the feasibility of hydrometallurgical processes.

  6. Electrocatalysts having platium monolayers on palladium, palladium alloy, and gold alloy core-shell nanoparticles, and uses thereof

    DOEpatents

    Adzic, Radoslav; Mo, Yibo; Vukmirovic, Miomir; Zhang, Junliang

    2010-12-21

    The invention relates to platinum-coated particles useful as fuel cell electrocatalysts. The particles are composed of a noble metal or metal alloy core at least partially encapsulated by an atomically thin surface layer of platinum atoms. The invention particularly relates to such particles having a palladium, palladium alloy, gold alloy, or rhenium alloy core encapsulated by an atomic monolayer of platinum. In other embodiments, the invention relates to fuel cells containing these electrocatalysts and methods for generating electrical energy therefrom.

  7. Synthesis of palladium(0) and -(II) complexes with chelating bis(N-heterocyclic carbene) ligands and their application in semihydrogenation.

    PubMed

    Sluijter, Soraya N; Warsink, Stefan; Lutz, Martin; Elsevier, Cornelis J

    2013-05-28

    A transmetallation route, using silver(I) precursors, to several zero- and di-valent palladium complexes with chelating bis(N-heterocyclic carbene) ligands bearing various N-substituents has been established. The resulting complexes have been characterized by NMR and mass spectroscopy. In addition, the structure of a representative compound, [Pd(0)(bis-(Mes)NHC)(η(2)-ma)] (3a), was confirmed by X-ray crystal structure determination. In contrast to the transfer semihydrogenation, in which only low activity was observed, complex 3a showed activity (TOF = 49 mol(sub) mol(cat)(-1) h(-1)) and selectivity comparable to its monodentate counterparts in the semihydrogenation of 1-phenyl-1-propyne with molecular hydrogen.

  8. Palladium(II) complexes of 1,10-phenanthroline: Synthesis and X-ray crystal structure determination

    PubMed Central

    Adrian, Rafael A.; Broker, Grant A.; Tiekink, Edward R. T.

    2009-01-01

    Two palladium(II) complexes, [Pd(phen)(N≡CCH3)2][O3SCF3]2 (1) and [Pd(phen)(μ-OH)]2[O3SCF3]2·2H2O (2) (where phen= 1,10-phenanthroline), have been crystallized following the reaction of Pd(phen)Cl2 with silver triflate, Ag(O3SCF3), in acetonitrile and water, respectively. The structures of both complexes are based on a Pd(phen)2+ metal core, with two acetonitrile molecules binding in a monodentate fashion in complex 1 and two hydroxo bridges holding together two cores to form a dimer in complex 2. Additionally, both complexes present a hydrogen bonded 3-D network involving the triflate anions in 1, and water and triflate anions in 2. Both complexes have been characterized by infrared and 1H NMR spectroscopy and their crystal structures determined by X-ray crystallography. PMID:19693286

  9. Mineral of the month: cadmium

    USGS Publications Warehouse

    Klimasauskas, Edward

    2005-01-01

    Cadmium, which was once used almost exclusively for pigments, now has many diverse applications. Cadmium’s low melting point, excellent electrical conductivity and resistance to corrosion make it valuable for many products including batteries, electroplated coatings, stabilizers for plastics, solar cells and nonferrous alloys. Today’s cadmium is primarily used in rechargeable batteries, accounting for about 78 percent of consumption in 2004. In 2000, an estimated 3.5 billion consumer batteries were sold in the United States, of which almost 10 percent were nickel-cadmium batteries.

  10. Leaching of Silver from Silver-Impregnated Food Storage Containers

    ERIC Educational Resources Information Center

    Hauri, James F.; Niece, Brian K.

    2011-01-01

    The use of silver in commercial products has proliferated in recent years owing to its antibacterial properties. Food containers impregnated with micro-sized silver promise long food life, but there is some concern because silver can leach out of the plastic and into the stored food. This laboratory experiment gives students the opportunity to…

  11. Recovery of cesium and palladium from nuclear reactor fuel processing waste

    DOEpatents

    Campbell, David O.

    1976-01-01

    A method of recovering cesium and palladium values from nuclear reactor fission product waste solution involves contacting the solution with a source of chloride ions and oxidizing palladium ions present in the solution to precipitate cesium and palladium as Cs.sub.2 PdCl.sub.6.

  12. Dynamics of palladium on nanocarbon in the direct synthesis of H2O2.

    PubMed

    Arrigo, Rosa; Schuster, Manfred E; Abate, Salvatore; Wrabetz, Sabine; Amakawa, Kazuhiko; Teschner, Detre; Freni, Maria; Centi, Gabriele; Perathoner, Siglinda; Hävecker, Michael; Schlögl, Robert

    2014-01-01

    This work aims to clarify the nanostructural transformation accompanying the loss of activity and selectivity for the hydrogen peroxide synthesis of palladium and gold-palladium nanoparticles supported on N-functionalized carbon nanotubes. High-resolution X-ray photoemission spectroscopy (XPS) allows the discrimination of metallic palladium, electronically modified metallic palladium hosting impurities, and cationic palladium. This is paralleled by the morphological heterogeneity observed by high-resolution TEM, in which nanoparticles with an average size of 2 nm coexisted with very small palladium clusters. The morphological distribution of palladium is modified after reaction through sintering and dissolution/redeposition pathways. The loss of selectivity is correlated to the extent to which these processes occur as a result of the instability of the particle at the carbon surface. We assign beneficial activity in the selective hydrogenation of oxygen to palladium clusters with a modified electronic structure compared with palladium metal or palladium oxides. These beneficial species are formed and stabilized on carbons modified with nitrogen atoms in substitutional positions. The formation of larger metallic palladium particles not only reduces the number of active sites for the synthesis, but also enhances the activity for deep hydrogenation to water. The structural instability of the active species is thus detrimental in a dual way. Minimizing the chance of sintering of palladium clusters by all means is thus the key to better performing catalysts.

  13. Cadmium effects on the thyroid gland.

    PubMed

    Jancic, Snezana A; Stosic, Bojan Z

    2014-01-01

    Cadmium has been listed as one of the 126 priority pollutants and a category I carcinogen. Carcinogenic effects of cadmium on the lungs, testicles, and prostate are widely recognized, but there has been insufficient research on the effect of cadmium on the thyroid gland. Cadmium has the affinity to accumulate not only in the liver, kidneys, and pancreas but also in the thyroid gland. It has been established that cadmium blood concentration correlates positively with its accumulation in the thyroid gland. Women of fertile age have higher cadmium blood and urine concentrations than men. In spite of its redox inertia, cadmium brings about oxidative stress and damage to the tissue by indirect mechanisms. Mitochondria are considered to be the main intracellular targets for cadmium. Colloid cystic goiter, adenomatoid follicular hyperplasia with low-grade dysplasia and thyroglobulin hypo- and asecretion, and parafollicular cell diffuse and nodular hyperplasia and hypertrophy are often found in chronic cadmium toxicity. PMID:24388198

  14. Cadmium effects on the thyroid gland.

    PubMed

    Jancic, Snezana A; Stosic, Bojan Z

    2014-01-01

    Cadmium has been listed as one of the 126 priority pollutants and a category I carcinogen. Carcinogenic effects of cadmium on the lungs, testicles, and prostate are widely recognized, but there has been insufficient research on the effect of cadmium on the thyroid gland. Cadmium has the affinity to accumulate not only in the liver, kidneys, and pancreas but also in the thyroid gland. It has been established that cadmium blood concentration correlates positively with its accumulation in the thyroid gland. Women of fertile age have higher cadmium blood and urine concentrations than men. In spite of its redox inertia, cadmium brings about oxidative stress and damage to the tissue by indirect mechanisms. Mitochondria are considered to be the main intracellular targets for cadmium. Colloid cystic goiter, adenomatoid follicular hyperplasia with low-grade dysplasia and thyroglobulin hypo- and asecretion, and parafollicular cell diffuse and nodular hyperplasia and hypertrophy are often found in chronic cadmium toxicity.

  15. Stimulation of Cadmium Uptake in Relation to the Cadmium Content of Plants 1

    PubMed Central

    Petit, Charles M.; Ringoet, Arthur; Myttenaere, Constant

    1978-01-01

    The time course of cadmium uptake by the roots of intact tomato plants (Lycopersicon esculentum Mill.) was measured in a nutrient solution with a micromolar cadmium concentration until all cadmium in the medium was exhausted. Exhaustion taking a few hours, cadmium was repeatedly added to the nutrient solution. The initial rate of cadmium uptake was computed for each cadmium addition. This rate sharply increased and ultimately leveled off, the maximum value being about three times higher than the value measured after the first cadmium addition. The stimulating effect of cadmium was associated with an inhibitory effect at higher levels of cadmium concentrations. An increase in the net cadmium influx with time could not be explained by the binding of heavy metal to a fixed number of organic compounds. Conceivably, the production of binding sites could be increased and cadmium might play a part in controlling the rate of sites production. PMID:16660557

  16. Recovery of Elemental Palladium by Shewanella putrefaciens

    NASA Astrophysics Data System (ADS)

    Akasaka, S.; Xia, X.; Sawada, K.; Enokida, Y.; Yamamoto, I.; Ohnuki, T.

    2006-12-01

    Microbial reduction of metals plays an important role in environmental behavior and provides a technique for the recovery of metals from industrial wastewater. Recently, demand for platinum group metals (PGMs) increases by their catalytic properties. The extreme rarity of PGMs have led to a growing interest in their recovery. Palladium, one of PGMs, has different oxidation states of Pd(II) and Pd(0). The oxidized form of Pd(II) is soluble, while the reduced form of Pd(0) is insoluble. In this study, microbial reduction of palladium by Fe(III)- reducing bacterium, Shewanella putrefaceins was conducted. This bacterium is known to be capable of reducing metals, such as Mn(IV), U(VI), or Tc(VII) with organic C or H2 as an electron donor. In order to investigate the potential of S. putrefaciens to reduce Pd(II) in solution, resting cells or heat-killed cells were suspended under anaerobic conditions with lactate or H2 as an electron donor. The cells of S. putrefaciens (NBRC3908) were grown in aerobic medium, harvested by centrifugation, and then washed with 25 mmol/dm3 HEPES and 100 mmol/dm3 NaCl (HEPES-NaCl) solution (pH 7.0). The heat-killed cells were autoclaved for 20 min at 121 degrees C. The cell suspension (21.5 mg in dry weight) was resuspended in the HEPES-NaCl solution which contained 1.0 mmol/dm3 Na2PdCl4 (Wako Pure chemical Industries, Ltd). The suspensions were bubbled with N2 for 15 min before 10 mmol/dm3 lactate or 4.8 v/v% H2 was added. The suspensions were then incubated at 30 degrees C. Redox potential (Eh) and pH of the solutions were measured in an inert glove box with Ar gas. Concentration of Pd(II) was measured by Inductively Coupled Plasma Atomic Emission Spectrometer (ICP-AES). Deposited Pd and cells were analyzed by X-ray powder diffraction (XRD) and Scanning Electron Microscope (SEM) with Energy-Dispersive Spectroscopy (EDS). Approximately 86% of Pd(II) of the initial concentration was removed from solution by the resting cells within 24 h when

  17. Mercury Telluride and Cadmium Telluride

    NASA Technical Reports Server (NTRS)

    2004-01-01

    A semiconductor's usefulness is determined by how atoms are ordered within the crystal's underlying three-dimensional structure. While this mercury telluride and cadmium telluride alloy sample mixes completely in Earth -based laboratories, convective flows prevent them from mixing uniformly.

  18. Aversiveness of cadmium in solution.

    PubMed

    Cory-Slechta, D A; Weiss, B

    1981-12-01

    Weanling rats were given cadmium chloride solutions as drinking water (0, 25, 50 or 150 ppm Cd). Immediate decrements in fluid consumption and retarded weight gain were observed at the highest concentration. In addition, two of the 150 ppm rats died within four days. The rapid onset of these effects suggested taste aversion and sharply reduced water intake, not physiological impairment, as the cause. To test this possibility, rats were given a choice between two drinking water solutions. One contained distilled water, the other cadmium. Concentrations as low as 1 ppm were rejected by some rats. Additional studies showed that chronic cadmium exposure modified the intake pattern of saccharin solutions typical of rats, and that the addition of saccharin to the 150 ppm cadmium solution did not reduce its aversive properties. These data indicated that the taste of cadmium, at least in solution, is aversive to rats. Since taste aversion can reduce fluid and food consumption, and consequently body weight, properly designed experiments must include adequate control procedures such as pair-feeding and pair-watering to differentiate unique effects of cadmium from those produced by undernutrition.

  19. [Tobacco cadmium health risk assessment and reduction techniques: A review].

    PubMed

    Cao, Chen-liang; Ma, Yi-bing; Li, Ju-mei; Wei, Dong-pu; Shi, Yi

    2015-04-01

    Tobacco is one of the cadmium accumulation and tolerance plants. Decreasing cadmium content of tobacco contributes to environmental safety and human health. Three aspects on tobacco cadmium research were reviewed in this paper, i.e. uptake and distribution of cadmium in tobacco, and health risk assessment of cadmium in tobacco and reduction measures. The current situations and existing challenges in the research field were discussed. The cadmium tolerance mechanisms of tobacco were reviewed, the factors on cadmium uptake were analyzed, and the general distribution of cadmium in tobacco was summarized. From the point of health risk assessment, the lack of cadmium limits in tobacco was identified, the recommended formula to calculate cadmium limits of tobacco based on atmosphere cadmium limits and digestion cadmium limits was provided and the cadmium limits of tobacco were estimated using each formula, and suggestions on cadmium limits in tobacco were presented. At last, we put forward several effective reduction measures to lower cadmium level in tobacco leaves.

  20. Palladium-Catalyzed Arylation of Fluoroalkylamines

    PubMed Central

    Brusoe, Andrew T.; Hartwig, John F.

    2015-01-01

    We report the synthesis of fluorinated anilines by palladium-catalyzed coupling of fluoroalkylamines with aryl bromides and aryl chlorides. The products of these reactions are valuable because anilines typically require the presence of an electron-withdrawing substituent on nitrogen to suppress aerobic or metabolic oxidation, and the fluoroalkyl groups have steric properties and polarity distinct from those of more common electron-withdrawing amide and sulfonamide units. The fluoroalkylaniline products are unstable under typical conditions for C–N coupling reactions (heat and strong base). However, the reactions conducted with the weaker base KOPh, which has rarely been used in cross-coupling to form C–N bonds, occurred in high yield in the presence of a catalyst derived from commercially available AdBippyPhos and [Pd(allyl)Cl]2. Under these conditions, the reactions occur with low catalyst loadings (<0.50 mol % for most substrates) and tolerate the presence of various functional groups that react with the strong bases that are typically used in Pd-catalyzed C–N cross-coupling reactions of aryl halides. The resting state of the catalyst is the phenoxide complex, (BippyPhosPd(Ar)OPh); due to the electron-withdrawing property of the fluoroalkyl substituent, the turnover-limiting step of the reaction is reductive elimination to form the C–N bond. PMID:26065341

  1. Superlattices of platinum and palladium nanoparticles

    SciTech Connect

    MARTIN,JAMES E.; WILCOXON,JESS P.; ODINEK,JUDY G.; PROVENCIO,PAULA P.

    2000-04-06

    The authors have used a nonionic inverse micelle synthesis technique to form nanoclusters of platinum and palladium. These nanoclusters can be rendered hydrophobic or hydrophilic by the appropriate choice of capping ligand. Unlike Au nanoclusters, Pt nanoclusters show great stability with thiol ligands in aqueous media. Alkane thiols, with alkane chains ranging from C{sub 6} to C{sub 18} were used as hydrophobic ligands, and with some of these they were able to form 2-D and/or 3-D superlattices of Pt nanoclusters as small as 2.7 nm in diameter. Image processing techniques were developed to reliably extract from transmission electron micrographs (TEMs) the particle size distribution, and information about the superlattice domains and their boundaries. The latter permits one to compute the intradomain vector pair correlation function of the particle centers, from which they can accurately determine the lattice spacing and the coherent domain size. From these data the gap between the particles in the coherent domains can be determined as a function of the thiol chain length. It is found that as the thiol chain length increases, the gaps between particles within superlattice domains increases, but more slowly than one might expect, possibly indicating thiol chain interdigitation.

  2. Porous palladium coated conducting polymer nanoparticles for ultrasensitive hydrogen sensors.

    PubMed

    Lee, Jun Seop; Kim, Sung Gun; Cho, Sunghun; Jang, Jyongsik

    2015-12-28

    Hydrogen, a clean-burning fuel, is of key importance to various industrial applications, including fuel cells and in the aerospace and automotive industries. However, hydrogen gas is odorless, colorless, and highly flammable; thus appropriate safety protocol implementation and monitoring are essential. Highly sensitive hydrogen leak detection and surveillance sensor systems are needed; additionally, the ability to maintain uniformity through repetitive hydrogen sensing is becoming increasingly important. In this report, we detail the fabrication of porous palladium coated conducting polymer (3-carboxylate polypyrrole) nanoparticles (Pd@CPPys) to detect hydrogen gas. The Pd@CPPys are produced by means of facile alkyl functionalization and chemical reduction of a pristine 3-carboxylate polypyrrole nanoparticle-contained palladium precursor (PdCl(2)) solution. The resulting Pd@CPPy-based sensor electrode exhibits ultrahigh sensitivity (0.1 ppm) and stability toward hydrogen gas at room temperature due to the palladium sensing layer.

  3. Palladium-Catalyzed Arylation of Alkyl Sulfenate Anions.

    PubMed

    Jia, Tiezheng; Zhang, Mengnan; Jiang, Hui; Wang, Carol Y; Walsh, Patrick J

    2015-11-01

    A unique palladium-catalyzed arylation of alkyl sulfenate anions is introduced that affords aryl alkyl sulfoxides in high yields. Due to the base sensitivity of the starting sulfoxides, sulfenate anion intermediates, and alkyl aryl sulfoxide products, the use of a mild method to generate alkyl sulfenate anions was crucial to the success of this process. Thus, a fluoride triggered elimination strategy was employed with alkyl 2-(trimethylsilyl)ethyl sulfoxides to liberate the requisite alkyl sulfenate anion intermediates. In the presence of palladium catalysts with bulky monodentate phosphines (SPhos and Cy-CarPhos) and aryl bromides or chlorides, alkyl sulfenate anions were readily arylated. Moreover, the thermal fragmentation and the base promoted elimination of alkyl sulfoxides was overridden. The alkyl sulfenate anion arylation exhibited excellent chemoselectivity in the presence of functional groups, such as anilines and phenols, which are also known to undergo palladium catalyzed arylation reactions.

  4. Palladium-catalyzed modification of unprotected nucleosides, nucleotides, and oligonucleotides.

    PubMed

    Shaughnessy, Kevin H

    2015-05-22

    Synthetic modification of nucleoside structures provides access to molecules of interest as pharmaceuticals, biochemical probes, and models to study diseases. Covalent modification of the purine and pyrimidine bases is an important strategy for the synthesis of these adducts. Palladium-catalyzed cross-coupling is a powerful method to attach groups to the base heterocycles through the formation of new carbon-carbon and carbon-heteroatom bonds. In this review, approaches to palladium-catalyzed modification of unprotected nucleosides, nucleotides, and oligonucleotides are reviewed. Polar reaction media, such as water or polar aprotic solvents, allow reactions to be performed directly on the hydrophilic nucleosides and nucleotides without the need to use protecting groups. Homogeneous aqueous-phase coupling reactions catalyzed by palladium complexes of water-soluble ligands provide a general approach to the synthesis of modified nucleosides, nucleotides, and oligonucleotides.

  5. Local magnetism in palladium bionanomaterials probed by muon spectroscopy.

    PubMed

    Creamer, Neil J; Mikheenko, Iryna P; Johnson, Clive; Cottrell, Stephen P; Macaskie, Lynne E

    2011-05-01

    Palladium bionanomaterial was manufactured using the sulfate-reducing bacterium, Desulfovibrio desulfuricansm, to reduce soluble Pd(II) ions to cell-bound Pd(0) in the presence of hydrogen. The biomaterial was examined using a Superconducting Quantum Interference Device (SQUID) to measure bulk magnetisation and by Muon Spin Rotation Spectroscopy (µSR) which is uniquely able to probe the local magnetic environment inside the sample. Results showed behaviour attributable to interaction of muons both with palladium electrons and the nuclei of hydrogen trapped in the particles during manufacture. Electronic magnetism, also suggested by SQUID, is not characteristic of bulk palladium and is consistent with the presence of nanoparticles previously seen in electron micrographs. We show the first use of μSR as a tool to probe the internal magnetic environment of a biologically-derived nanocatalyst material.

  6. Porous palladium coated conducting polymer nanoparticles for ultrasensitive hydrogen sensors.

    PubMed

    Lee, Jun Seop; Kim, Sung Gun; Cho, Sunghun; Jang, Jyongsik

    2015-12-28

    Hydrogen, a clean-burning fuel, is of key importance to various industrial applications, including fuel cells and in the aerospace and automotive industries. However, hydrogen gas is odorless, colorless, and highly flammable; thus appropriate safety protocol implementation and monitoring are essential. Highly sensitive hydrogen leak detection and surveillance sensor systems are needed; additionally, the ability to maintain uniformity through repetitive hydrogen sensing is becoming increasingly important. In this report, we detail the fabrication of porous palladium coated conducting polymer (3-carboxylate polypyrrole) nanoparticles (Pd@CPPys) to detect hydrogen gas. The Pd@CPPys are produced by means of facile alkyl functionalization and chemical reduction of a pristine 3-carboxylate polypyrrole nanoparticle-contained palladium precursor (PdCl(2)) solution. The resulting Pd@CPPy-based sensor electrode exhibits ultrahigh sensitivity (0.1 ppm) and stability toward hydrogen gas at room temperature due to the palladium sensing layer. PMID:26598964

  7. Catalytic removal of carbon monoxide over carbon supported palladium catalyst.

    PubMed

    Srivastava, Avanish Kumar; Saxena, Amit; Shah, Dilip; Mahato, T H; Singh, Beer; Shrivastava, A R; Gutch, P K; Shinde, C P

    2012-11-30

    Carbon supported palladium (Pd/C) catalyst was prepared by impregnation of palladium chloride using incipient wetness technique, which was followed by liquid phase reduction with formaldehyde. Thereafter, Pd/C catalyst was characterized using X-ray diffractometery, scanning electron microscopy, atomic absorption spectroscopy, thermo gravimetry, differential scanning calorimetry and surface characterization techniques. Catalytic removal of carbon monoxide (CO) over Pd/C catalyst was studied under dynamic conditions. Pd/C catalyst was found to be continuously converting CO to CO(2) through the catalyzed reaction, i.e., CO+1/2O(2)→CO(2). Pd/C catalyst provided excellent protection against CO. Effects of palladium wt%, CO concentration, humidity, space velocity and reaction environment were also studied on the breakthrough behavior of CO. PMID:23083941

  8. Electrical resistivity of some palladium-silver alloys containing hydrogen at 4.2 K

    NASA Technical Reports Server (NTRS)

    Smith, R. J.; Otterson, D. A.

    1974-01-01

    The electrical resistivities of the alloys 90at.%Pd - 10at.%Ag, 80at.%Pd - 20at.%Ag, 70at.%Pd - 30at.%Ag, 60at.%Pd - 40at.%Ag, and 50at.%Pd - 50at.%Ag were measured as functions of absorbed hydrogen x at 4.2 K. These results show a minimum in the resistivity for all the alloys except 90Pd-10Ag; they show a maximum for all the alloys except for 50Pd-Ag. We associate the shapes of the plots with a modification of the Pd D-band because of the substitutional alloying of Ag and the interstitial absorption of hydrogen.

  9. Palladium and ruthenium supported silver migration in 3C-silicon carbide

    NASA Astrophysics Data System (ADS)

    O'Connell, Jacques Herman; Neethling, Johannes Henoch

    2015-01-01

    Surrogate TRISO particles were infiltrated with a Pd Ag mixture and heat treated at 1000 °C to investigate the effect of Pd on Ag transport through current state of the art TRISO coatings for use in HTGRs. The experiment was repeated with Ru instead of Pd because of the similarities in the reaction between Pd and Ru with SiC. It was found that both Pd and Ru form their respective silicides after heat treatment together with the simultaneous precipitation of graphite. In both cases Ag was concentrated along the leading edge of the reaction zone which itself was concentrated along grain boundaries. However, the effect of Pd was much more pronounced than that of Ru making Ru at most a secondary contributor to Ag migration through SiC in TRISO fuel.

  10. Glutathione-stabilized palladium nanozyme for colorimetric assay of silver(I) ions.

    PubMed

    Fu, Yan; Zhang, Haixiang; Dai, Shengdong; Zhi, Xing; Zhang, Jinli; Li, Wei

    2015-10-01

    Glutathione-capped Pd nanoparticles with a size of 1.4-3.5 nm are facilely synthesized for peroxidase nanomimetics. The molar ratio of [Na2PdCl4]/[GSH] greatly affects the physicochemical properties including particle sizes, surface charge states and enzymatic activities. The most efficient Pd-based nanozyme, consisting of approximately 57% metallic Pd(0) species with an average diameter of 2.6 nm, exhibits the K(m) value of 0.068 mM toward 3,3',5,5'-tetramethylbenzidine and 156 mM toward hydrogen peroxide. Ag(+) selectively binds to Pd(0) species through metallophilic interactions and induces an apparent aggregation of Pd nanoparticles. This is the first report that Ag(+) significantly inhibits the peroxidase mimicking activity of Pd nanoparticles. A Pd-based nanozyme is employed to explore colorimetric detection of Ag(+) with the limit of detection of 1.2 nM. This developed sensing system is potentially applicable for quantitative detection of Ag(+) in drinking water as well as Ag nanoparticles in aqueous solution.

  11. Hydrogen-induced high-temperature segregation in palladium silver membranes.

    PubMed

    Zeng, Gaofeng; Jia, Haiyuan; Goldbach, Andreas; Zhao, Lingfang; Miao, Shu; Shi, Lei; Sun, Chenglin; Xu, Hengyong

    2014-12-14

    Higher operation temperatures benefit H2 permeability and selectivity of metal membranes and they are interesting for e.g. water gas shift and steam reforming in membrane reactors. Hence the behaviour of PdAg-ceramic composite membranes has been investigated between 823 K and 923 K. The H2 flux of membranes with less than 10 μm thick alloy layers decreased continuously with time during operation under H2 at 873 K and above. This was accompanied by a steady increase of the activation energy for H2 permeation and the growth of Ag-depleted crystallites on the membrane surface. All phenomena could be reversed through annealing under N2 at 923 K. The textural and permeability changes are consistent with a segregation mechanism starting with metal sublimation from hydrogenated PdAg layers and subsequent metal resublimation. This implies an enhancement of the yet unknown metal activities in PdAg hydride phases over metallic PdAg alloys. Ramifications for application of thin-layered, supported PdAg membranes for H2 separation above 823 K are discussed. PMID:25336424

  12. Effect of microstructure on hydrogen permeation through thermally stable, sputtered palladium-silver alloy membranes

    SciTech Connect

    McLeod, L. S.; Degertekin, F. L.; Fedorov, A. G.

    2007-06-25

    The authors report on fabrication and hydrogen separation performance of an array of thin, freestanding Pd/Ag alloy membranes. Film deposition from an alloyed sputtering target results in robust film characteristics. Long-term stability of the membranes has been demonstrated with experimental testing at temperatures of 473-627 K. Within the testing period the membrane has withstood more than 30 thermal cycles by returning to ambient temperature between subsequent tests. Throughout the long-term testing, hydrogen permeation levels have increased by more than a factor of 2. Electron microscopy of the membranes indicates that performance enhancement is due to microstructural changes which are promoted at elevated temperatures.

  13. CONTROL ROD ALLOY CONTAINING NOBLE METAL ADDITIONS

    DOEpatents

    Anderson, W.K.; Ray, W.E.

    1960-05-01

    Silver-base alloys suitable for use in the fabrication of control rods for neutronic reactors are given. The alloy consists of from 0.5 wt.% to about 1.5 wt.% of a noble metal of platinum, ruthenium, rhodium, osmium, or palladium, up to 10 wt.% of cadmium, from 2 to 20 wt.% indium, the balance being silver.

  14. Porous palladium coated conducting polymer nanoparticles for ultrasensitive hydrogen sensors

    NASA Astrophysics Data System (ADS)

    Lee, Jun Seop; Kim, Sung Gun; Cho, Sunghun; Jang, Jyongsik

    2015-12-01

    Hydrogen, a clean-burning fuel, is of key importance to various industrial applications, including fuel cells and in the aerospace and automotive industries. However, hydrogen gas is odorless, colorless, and highly flammable; thus appropriate safety protocol implementation and monitoring are essential. Highly sensitive hydrogen leak detection and surveillance sensor systems are needed; additionally, the ability to maintain uniformity through repetitive hydrogen sensing is becoming increasingly important. In this report, we detail the fabrication of porous palladium coated conducting polymer (3-carboxylate polypyrrole) nanoparticles (Pd@CPPys) to detect hydrogen gas. The Pd@CPPys are produced by means of facile alkyl functionalization and chemical reduction of a pristine 3-carboxylate polypyrrole nanoparticle-contained palladium precursor (PdCl2) solution. The resulting Pd@CPPy-based sensor electrode exhibits ultrahigh sensitivity (0.1 ppm) and stability toward hydrogen gas at room temperature due to the palladium sensing layer.Hydrogen, a clean-burning fuel, is of key importance to various industrial applications, including fuel cells and in the aerospace and automotive industries. However, hydrogen gas is odorless, colorless, and highly flammable; thus appropriate safety protocol implementation and monitoring are essential. Highly sensitive hydrogen leak detection and surveillance sensor systems are needed; additionally, the ability to maintain uniformity through repetitive hydrogen sensing is becoming increasingly important. In this report, we detail the fabrication of porous palladium coated conducting polymer (3-carboxylate polypyrrole) nanoparticles (Pd@CPPys) to detect hydrogen gas. The Pd@CPPys are produced by means of facile alkyl functionalization and chemical reduction of a pristine 3-carboxylate polypyrrole nanoparticle-contained palladium precursor (PdCl2) solution. The resulting Pd@CPPy-based sensor electrode exhibits ultrahigh sensitivity (0.1 ppm

  15. Palladium-Catalyzed Oxidative Domino Carbocyclization–Arylation of Bisallenes

    PubMed Central

    2016-01-01

    Herein we report a highly efficient and site-selective palladium-catalyzed oxidative carbocyclization–arylation reaction of bisallenes and arylboronic acids under operationally simple conditions for the selective synthesis of cyclohexadiene derivatives. The palladium source and the solvent proved to be crucial for the selectivity and the reactivity displayed. Interestingly, in the absence of the nucleophile, an oxidative carbocyclization-β-elimination pathway predominates. The reaction conditions are compatible with a wide range of functional groups, and the reaction exhibits broad substrate scope. Furthermore, key information regarding the mechanism was obtained using control experiments and kinetic studies. PMID:27761298

  16. Structure of Palladium Nanoclusters for Hydrogen Gas Sensors

    SciTech Connect

    Stevens, K.J.; Ingham, B.; Toney, M.F.; Brown, S.A.; Lassesson, A.; /SLAC, SSRL /Canterbury U.

    2009-05-11

    Palladium nanoclusters produced by inert gas aggregation/magnetron sputtering are used as building blocks for the construction of nano electronic devices with large surface to volume ratios that can be used as sensitive hydrogen gas sensors in fuel cells and in petrochemical plants. X-ray diffraction (XRD), extended X-ray absorption fine structure (EXAFS), and high resolution transmission electron microscopy (HRTEM) have been used to characterize the structure, lattice constant, particle diameter and oxide thickness of the palladium nanoclusters in order to understand the operation of these sensors. Grazing incidence XRD (GIXRD) of heat treated Pd clusters has shown that the palladanite structure forms at elevated temperatures.

  17. Kinetic investigation of indium-palladium alloy electrodeposition

    SciTech Connect

    Vinogradov, S.N.; Perelygin, Yu.P.; Efimov, E.A.

    1988-01-01

    The kinetics of alloy deposition of ammonium-citrate electrolyte used to produce alloys with indium content were studied. The electrolytes were composed of palladium, indium, ammonium sulfate, monosodium citrate, ammonium chloride, and saccharin at pH 9.5. Stationary and rotating disk electrodes and a potentiostat were used for the investigation. Spectrophotometry determined the mixed formation of citrate-ammonia palladium complexes. It was found that the considerable depolarization of indium ion discharge into the alloy occurred when saccharin was present in the electrolyte, and its direct electroreduction occurs from hydroxide compounds.

  18. High-Valent Organometallic Copper and Palladium in Catalysis

    PubMed Central

    Hickman, Amanda J.; Sanford, Melanie S.

    2015-01-01

    Preface Copper and palladium catalysts are critically important for numerous commercial chemical processes. Improvements in the activity, selectivity, and scope of these catalysts have the potential to dramatically reduce the environmental impact and increase the sustainability of chemical reactions. One rapidly emerging strategy to achieve these goals is to exploit “high-valent” copper and palladium intermediates in catalysis. This review describes exciting recent advances involving both the fundamental chemistry and the applications of these high-valent metal complexes in numerous synthetically useful catalytic transformations. PMID:22498623

  19. Heterocycle Formation via Palladium-Catalyzed C–H Functionalization

    PubMed Central

    Mei, Tian-Sheng; Kou, Lei; Ma, Sandy; Engle, Keary M.; Yu, Jin-Quan

    2016-01-01

    Heterocyclic compounds are ubiquitous in natural products, pharmaceuticals, and agrochemicals. Therefore, the design of novel protocols to construct heterocycles more efficiently is a major area of focus in the organic chemistry. In the past several years, cyclization reactions based upon palladium-catalyzed C–H activation have received substantial attention due to their capacity for expediting heterocycle synthesis. This review discusses strategies for heterocycle synthesis via palladium-catalyzed C–H bond activation and highlights recent examples from the literature. PMID:27397938

  20. Tales From Silver Lands.

    ERIC Educational Resources Information Center

    Finger, Charles J.

    In 1925, "Tales From Silver Lands" was awarded the Newbery medal as the most distinguished contribution to American children's literature for the year. The book contains a collection of 19 short stories learned from the Indians of South America as the author traveled to different lands. As described on the dust jacket, the tales are about "strange…

  1. Potassium silver cyanide

    Integrated Risk Information System (IRIS)

    Jump to main content . Integrated Risk Information System Recent Additions | Contact Us Search : All EPA IRIS • You are here : EPA Home • Research • Environmental Assessment • IRIS • IRIS Summaries Redirect Page As of September 28 , 2010 , the assessment summary for potassium silver cyanide is inclu

  2. Mechanisms of Cadmium Carcinogenesis [Abstract 2015

    EPA Science Inventory

    Cadmium is a transition metal and an ubiquitous environmental and industrial pollutant. Laboratory animal studies and epidemiological studies have shown that exposure to cadmium is associated with various organ toxicities and carcinogenic effects. Several national and internation...

  3. Antibacterial activity and toxicity of silver - nanosilver versus ionic silver

    NASA Astrophysics Data System (ADS)

    Kvitek, L.; Panacek, A.; Prucek, R.; Soukupova, J.; Vanickova, M.; Kolar, M.; Zboril, R.

    2011-07-01

    The in vitro study of antibacterial activity of silver nanoparticles (NPs), prepared via modified Tollens process, revealed high antibacterial activity even at very low concentrations around several units of mg/L. These concentrations are comparable with concentrations of ionic silver revealing same antibacterial effect. However, such low concentrations of silver NPs did not show acute cytotoxicity to mammalian cells - this occurs at concentrations higher than 60 mg/L of silver, while the cytotoxic level of ionic silver is much more lower (approx. 1 mg/L). Moreover, the silver NPs exhibit lower acute ecotoxicity against the eukaryotic organisms such as Paramecium caudatum, Monoraphidium sp. and D. melanogaster. The silver NPs are toxic to these organisms at the concentrations higher than 30 mg/L of silver. On contrary, ionic silver retains its cytoxicity and ecotoxicity even at the concentration equal to 1 mg/L. The performed experiments demonstrate significantly lower toxicity of silver NPs against the eukaryotic organisms than against the prokaryotic organisms.

  4. Role of palladium in the redox electrochemistry of ferrocene monocarboxylic acid encapsulated within ORMOSIL networks.

    PubMed

    Pandey, P C; Upadhyay, B C

    2005-07-14

    We report herein the effect of palladium on the redox electrochemistry of ferrocene monocarboxylic acid encapsulated within an organically modified sol-gel glass network (ORMOSIL). It has been found that amount of palladium and its geometrical distribution significantly alter the redox electrochemistry of FcMCA. The geometrical distribution of palladium has been controlled by two methods: (i) palladium is allowed to link within nanostructured network of the ORMOSIL which was subsequently availed from the reactivity of palladium chloride and trimethoxysilane; (ii) palladium powder is encapsulated together FcMCA thus allowing the presence of palladium within the nanoporous domain. The content of palladium is varied by controlling the reaction dynamics of palladium chloride and trimethoxysilane interaction. For this we initially allowed to trigger hydrolysis, condensation and poly-condensation of trimethoxysilane and dimethyldiethoxysilane in acidic medium and subsequently partially dried ORMOSIL film was allowed to interact with palladium chloride. Even with partially dried ORMOSIL derived from trimethoxysilane and dimethyldiethoxysilane undergoes rapid interaction with palladium chloride and the transparent color of ORMOSIL changed to a black colour due to the formation of palladium silicon linkage. The palladium-silicon linkage has been identified by NMR, UV-VIS and transmission electron spectroscopy. The electrochemistry of FcMCA encapsulated within such an ORMOSIL matrix has been studied. Excellent redox electrochemistry of ferrocene monocarboxylic acid having peak potential separation tending to 0 for a multilayered electrode was investigated. The palladium content has been found to affect the redox electrochemistry of ferrocene as well as electrocatalytic efficiency of new ORMOSIL material. The electroanalysis of NADH is reported. The modified electrode is very sensitive to NADH with lowest detection limit of < 1 microM.

  5. Well-defined coinage metal transfer agents for the synthesis of NHC-based nickel, rhodium and palladium macrocycles.

    PubMed

    Andrew, Rhiann E; Storey, Caroline M; Chaplin, Adrian B

    2016-06-01

    With a view to use as carbene transfer agents, well-defined silver(i) and copper(i) complexes of a macrocyclic NHC-based pincer ligand, bearing a central lutidine donor and a dodecamethylene spacer [CNC-(CH2)12, 1], have been prepared. Although the silver adduct is characterised by X-ray diffraction as a dinuclear species anti-[Ag(μ-1)]2(2+), variable temperature measurements indicate dynamic structural interchange in solution involving fragmentation into mononuclear [Ag(1)](+) on the NMR time scale. In contrast, a mononuclear structure is evident in both solution and the solid-state for the analogous copper adduct partnered with the weakly coordinating [BAr(F)4](-) counter anion. A related copper derivative, bearing instead the more coordinating cuprous bromide dianion [Cu2Br4](2-), is notable for the adoption of an interesting tetranuclear assembly in the solid-state, featuring two cuprophilic interactions and two bridging NHC donors, but is not retained on dissolution. Coinage metal precursors [M(1)]n[BAr(F)4]n (M = Ag, n = 2; M = Cu, n = 1) both act as carbene transfer agents to afford palladium, rhodium and nickel complexes of 1 and the effectiveness of these precursors has been evaluated under equivalent reaction conditions. PMID:27157720

  6. Well-defined coinage metal transfer agents for the synthesis of NHC-based nickel, rhodium and palladium macrocycles.

    PubMed

    Andrew, Rhiann E; Storey, Caroline M; Chaplin, Adrian B

    2016-06-01

    With a view to use as carbene transfer agents, well-defined silver(i) and copper(i) complexes of a macrocyclic NHC-based pincer ligand, bearing a central lutidine donor and a dodecamethylene spacer [CNC-(CH2)12, 1], have been prepared. Although the silver adduct is characterised by X-ray diffraction as a dinuclear species anti-[Ag(μ-1)]2(2+), variable temperature measurements indicate dynamic structural interchange in solution involving fragmentation into mononuclear [Ag(1)](+) on the NMR time scale. In contrast, a mononuclear structure is evident in both solution and the solid-state for the analogous copper adduct partnered with the weakly coordinating [BAr(F)4](-) counter anion. A related copper derivative, bearing instead the more coordinating cuprous bromide dianion [Cu2Br4](2-), is notable for the adoption of an interesting tetranuclear assembly in the solid-state, featuring two cuprophilic interactions and two bridging NHC donors, but is not retained on dissolution. Coinage metal precursors [M(1)]n[BAr(F)4]n (M = Ag, n = 2; M = Cu, n = 1) both act as carbene transfer agents to afford palladium, rhodium and nickel complexes of 1 and the effectiveness of these precursors has been evaluated under equivalent reaction conditions.

  7. 21 CFR 73.2500 - Silver.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 1 2014-04-01 2014-04-01 false Silver. 73.2500 Section 73.2500 Food and Drugs... ADDITIVES EXEMPT FROM CERTIFICATION Cosmetics § 73.2500 Silver. (a) Identity. (1) The color additive, silver, is a crystalline powder of high purity silver prepared by the reaction of silver nitrate with...

  8. 21 CFR 73.2500 - Silver.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 1 2011-04-01 2011-04-01 false Silver. 73.2500 Section 73.2500 Food and Drugs... ADDITIVES EXEMPT FROM CERTIFICATION Cosmetics § 73.2500 Silver. (a) Identity. (1) The color additive, silver, is a crystalline powder of high purity silver prepared by the reaction of silver nitrate with...

  9. 21 CFR 73.2500 - Silver.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 1 2012-04-01 2012-04-01 false Silver. 73.2500 Section 73.2500 Food and Drugs... ADDITIVES EXEMPT FROM CERTIFICATION Cosmetics § 73.2500 Silver. (a) Identity. (1) The color additive, silver, is a crystalline powder of high purity silver prepared by the reaction of silver nitrate with...

  10. 21 CFR 73.2500 - Silver.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 1 2010-04-01 2010-04-01 false Silver. 73.2500 Section 73.2500 Food and Drugs... ADDITIVES EXEMPT FROM CERTIFICATION Cosmetics § 73.2500 Silver. (a) Identity. (1) The color additive, silver, is a crystalline powder of high purity silver prepared by the reaction of silver nitrate with...

  11. 21 CFR 73.2500 - Silver.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 1 2013-04-01 2013-04-01 false Silver. 73.2500 Section 73.2500 Food and Drugs... ADDITIVES EXEMPT FROM CERTIFICATION Cosmetics § 73.2500 Silver. (a) Identity. (1) The color additive, silver, is a crystalline powder of high purity silver prepared by the reaction of silver nitrate with...

  12. 29 CFR 1928.1027 - Cadmium.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 29 Labor 9 2014-07-01 2014-07-01 false Cadmium. 1928.1027 Section 1928.1027 Labor Regulations...) OCCUPATIONAL SAFETY AND HEALTH STANDARDS FOR AGRICULTURE Occupational Health § 1928.1027 Cadmium. See § 1910.1027, Cadmium....

  13. 29 CFR 1928.1027 - Cadmium.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 29 Labor 9 2010-07-01 2010-07-01 false Cadmium. 1928.1027 Section 1928.1027 Labor Regulations...) OCCUPATIONAL SAFETY AND HEALTH STANDARDS FOR AGRICULTURE Occupational Health § 1928.1027 Cadmium. See § 1910.1027, Cadmium....

  14. 29 CFR 1928.1027 - Cadmium.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 29 Labor 9 2012-07-01 2012-07-01 false Cadmium. 1928.1027 Section 1928.1027 Labor Regulations...) OCCUPATIONAL SAFETY AND HEALTH STANDARDS FOR AGRICULTURE Occupational Health § 1928.1027 Cadmium. See § 1910.1027, Cadmium....

  15. Characterization of Electrochemically Generated Silver

    NASA Technical Reports Server (NTRS)

    Adam, Niklas; Martinez, James; Carrier, Chris

    2014-01-01

    Silver biocide offers a potential advantage over iodine, the current state of the art in US spacecraft disinfection technology, in that silver can be safely consumed by the crew. Low concentrations of silver (<500 ppb) have been shown to kill bacteria in water systems and keep it safe for potability. Silver does not require hardware to remove it from a water system, and therefore can provide a simpler means for disinfecting water. The Russian segment of the International Space Station has utilized an electrochemically generated silver solution, which is colloidal in nature. To be able to reliably provide a silver biocide to drinking water by electrochemical means would reduce mass required for removing another biocide such as iodine from the water. This would also aid in crew time required to replace iodine removal cartridges. Future long term missions would benefit from electrochemically produced silver as the biocide could be produced on demand and requires only a small concentration to be effective. Since it can also be consumed safely, there is less mass in removal hardware and little consumables required for production. The goal of this project initially is to understand the nature of the electrochemically produced silver, the particle sizes produced by the electrochemical cell and the effect that voltage adjustment has on the particle size. In literature, it has been documented that dissolved oxygen and pH have an effect on the ionization of the electrochemical silver so those parameters would be measured and possibly adjusted to understand their effect on the silver.

  16. Mechanisms of cadmium carcinogenesis

    SciTech Connect

    Joseph, Pius

    2009-08-01

    Cadmium (Cd), a heavy metal of considerable occupational and environmental concern, has been classified as a human carcinogen by the International Agency for Research on Cancer (IARC). The carcinogenic potential of Cd as well as the mechanisms underlying carcinogenesis following exposure to Cd has been studied using in vitro cell culture and in vivo animal models. Exposure of cells to Cd results in their transformation. Administration of Cd in animals results in tumors of multiple organs/tissues. Also, a causal relationship has been noticed between exposure to Cd and the incidence of lung cancer in human. It has been demonstrated that Cd induces cancer by multiple mechanisms and the most important among them are aberrant gene expression, inhibition of DNA damage repair, induction of oxidative stress, and inhibition of apoptosis. The available evidence indicates that, perhaps, oxidative stress plays a central role in Cd carcinogenesis because of its involvement in Cd-induced aberrant gene expression, inhibition of DNA damage repair, and apoptosis.

  17. Palladium catalyzed C3-arylation of 4-hydroxy-2-pyridones.

    PubMed

    Anagnostaki, Elissavet E; Fotiadou, Anna D; Demertzidou, Vera; Zografos, Alexandros L

    2014-07-01

    The direct arylation of N-substituted-4-hydroxy-2-pyridones with aryl boronic acids has been achieved under palladium catalysis. The mild reaction conditions applied in this method and the use of a conventional catalytic system offer an attractive protocol for the efficient synthesis of a variety of 3-arylated products.

  18. Operation of platinum-palladium catalysts with leaded gasoline.

    PubMed

    Teague, D M; Clougherty, L B; Speca, A N

    1975-04-01

    The effect of various fuel additives on the ability of platinum-palladium catalytic converters to remove the carbon monoxide and hydrocarbon components of automotive exhaust has been examined. Engine dynamometer studies suggest that these catalysts may be successfully used in conjunction with fuels of relatively high tetraethyllead concentrations, provided the ethylene dibromide portion of the scavenger is excluded. PMID:50929

  19. Observation of a crossover in kinetic aggregation of Palladium colloids

    NASA Astrophysics Data System (ADS)

    Ghafari, M.; Ranjbar, M.; Rouhani, S.

    2015-10-01

    We use field emission scanning electron microscope (FE-SEM) to investigate the growth of palladium colloids over the surface of thin films of WO3/glass. The film is prepared by Pulsed Laser Deposition (PLD) at different temperatures. A PdCl2 (aq) droplet is injected on the surface and in the presence of steam hydrogen the droplet is dried through a reduction reaction process. Two distinct aggregation regimes of palladium colloids are observed over the substrates. We argue that the change in aggregation dynamics emerges when the measured water drop Contact Angel (CA) for the WO3/glass thin films passes a certain threshold value, namely CA ≈ 46°, where a crossover in kinetic aggregation of palladium colloids occurs. Our results suggest that the mass fractal dimension of palladium aggregates follows a power-law behavior. The fractal dimension (Df) in the fast aggregation regime, where the measured CA values vary from 27° up to 46° according to different substrate deposition temperatures, is Df = 1.75(± 0.02) - the value of Df is in excellent agreement with kinetic aggregation of other colloidal systems in fast aggregation regime. Whereas for the slow aggregation regime, with CA = 58°, the fractal dimension changes abruptly to Df = 1.92(± 0.03). We have also used a modified Box-Counting method to calculate fractal dimension of gray-level images and observe that the crossover at around CA ≈ 46° remains unchanged.

  20. Palladium based cermet composite for hydrogen separation at elevated temperature

    NASA Astrophysics Data System (ADS)

    Tsai, Yen-Chang; Lin, Chien-Cheng; Lin, Wei-Lin; Wang, Jeng-Han; Chen, San-Yuan; Lin, Pang; Wu, Pu-Wei

    2015-01-01

    A cermet composite consisting of palladium and BaCe0.4Zr0.4Gd0.1Dy0.1O3-x (BCZGD) is fabricated by mixing palladium and BCZGD powders in a ball mill, followed by pressing and sintering at 1450 °C for 24 h in air. The Pd-BCZGD cermet demonstrates impressive hydrogen permeation flux in a mixture of hydrogen and carbon dioxide at elevated temperature, in which the palladium plays the predominant role of facile transport in the hydrogen atoms whereas the BCZGD provides channels for proton conduction. Material characterization including scanning electron microscopy (SEM), X-ray diffraction (XRD), and thermo-gravimetric analysis (TGA) are performed. XRD patterns indicate pure phases of fcc palladium and perovskite BCZGD. SEM images and element mapping suggest a homogeneous mixture of cermet without noticeable defect and phase segregation. TGA results confirm stability of the cermet against carbon dioxide without chemical decomposition. The hydrogen permeation flux is determined via a gas chromatography from 400 to 700 °C at various hydrogen concentration gradients. We record a hydrogen flux of 1.25 cm3 min-1 cm-2 in 50% hydrogen and 50% carbon dioxide at 700 °C, with a selectivity of H2/CO2 approaching infinity.

  1. STRONTIUM AS AN EFFICIENT PROMOTER FOR SUPPORTED PALLADIUM HYDROGENATION CATALYSTS

    EPA Science Inventory

    The effect of strontium promotion is studied for a series of supported palladium catalysts such as Pd/zeolite-β, Pd/Al2O3, Pd/SiO2, Pd/hydrotalcite and Pd/MgO. Strontium is found to be an effective promoter for enhancing the metal area, perce...

  2. Discovery of palladium, antimony, tellurium, iodine, and xenon isotopes

    SciTech Connect

    Kathawa, J.; Fry, C.; Thoennessen, M.

    2013-01-15

    Currently, thirty-eight palladium, thirty-eight antimony, thirty-nine tellurium, thirty-eight iodine, and forty xenon isotopes have been observed and the discovery of these isotopes is described here. For each isotope a brief synopsis of the first refereed publication, including the production and identification method, is presented.

  3. Batch Studies of Sodium Tetraphenylborate Decomposition on Reduced Palladium Catalyst

    SciTech Connect

    Barnes, M.J.

    2001-02-13

    In these batch experiments we obtained preliminary information on palladium based catalytic decomposition of sodium tetraphenylborate (NaTPB). These preliminary data provide necessary data to design subsequent catalytic decomposition experiments for NaTPB using a continuous stirred tank reactor (CSTR).

  4. Operation of platinum-palladium catalysts with leaded gasoline.

    PubMed Central

    Teague, D M; Clougherty, L B; Speca, A N

    1975-01-01

    The effect of various fuel additives on the ability of platinum-palladium catalytic converters to remove the carbon monoxide and hydrocarbon components of automotive exhaust has been examined. Engine dynamometer studies suggest that these catalysts may be successfully used in conjunction with fuels of relatively high tetraethyllead concentrations, provided the ethylene dibromide portion of the scavenger is excluded. PMID:50929

  5. Palladium-Catalyzed Enantioselective 1,1-Fluoroarylation of Aminoalkenes

    PubMed Central

    2016-01-01

    The development of an enantioselective palladium-catalyzed 1,1-fluoroarylation of unactivated aminoalkenes is described. The reaction uses arylboronic acids as the arene source and Selectfluor as the fluorine source to generate benzylic fluorides in good yields with excellent enantioselectivities. This transformation, likely proceeding through an oxidative Heck mechanism, affords 1,1-difunctionalized alkene products. PMID:26378886

  6. The Reaction of Carbon Dioxide with Palladium Allyl Bonds

    PubMed Central

    Wu, Jianguo; Green, Jennifer C.; Hruszkewycz, Damian P.; Incarvito, Christopher D.; Schmeier, Timothy J.

    2010-01-01

    A family of palladium allyl complexes of the type bis(2-methylallyl)Pd(L) (L = PMe3 (1), PEt3 (2), PPh3 (3) or NHC (4); NHC = 1,3-Bis(2,6-diisopropylphenyl)-1,3-dihydro-2H-imidazol-2-ylidene) have been prepared through the reaction of bis(2-methylallyl)Pd with the appropriate free ligand. Compounds 1–4 contain one η1 and one η3-2-methylallyl ligand and 3 was characterized by X-ray crystallography. These complexes react rapidly with CO2 at low temperature to form well defined unidentate palladium carboxylates of the type (η3-2-methylallyl)Pd(OC(O)C4H7)(L) (L = PMe3 (6), PEt3 (7), PPh3 (8) or NHC (9). The structure of 9 was elucidated using X-ray crystallography. The mechanism of the reaction of 1–4 with CO2 was probed using a combination of experimental and theoretical (density functional theory) studies. The coordination mode of the allyl ligand is crucial and whereas nucleophilic η1-allyls react rapidly with CO2, η3-allyls do not react. We propose that the reaction of η1-palladium allyls with CO2 does not proceed via direct insertion of CO2 into the Pd-C bond but through nucleophilic attack of the terminal olefin on electrophilic CO2, followed by an associative substitution at palladium. PMID:21218132

  7. Operation of platinum-palladium catalysts with leaded gasoline.

    PubMed

    Teague, D M; Clougherty, L B; Speca, A N

    1975-04-01

    The effect of various fuel additives on the ability of platinum-palladium catalytic converters to remove the carbon monoxide and hydrocarbon components of automotive exhaust has been examined. Engine dynamometer studies suggest that these catalysts may be successfully used in conjunction with fuels of relatively high tetraethyllead concentrations, provided the ethylene dibromide portion of the scavenger is excluded.

  8. Palladium-109 labeled anti-melanoma monoclonal antibodies

    DOEpatents

    Srivastava, S.C.; Fawwaz, R.A.; Ferrone, S.

    1984-04-30

    The invention consists of new monoclonal antibodies labelled with Palladium 109, a beta-emitting radionuclide, the method of preparing this material, and its use in the radiotherapy of melanoma. The antibodies are chelate-conjugated and demonstrate a high uptake in melanomas. (ACR)

  9. Oxidation of methane over palladium catalysts: effect of the support.

    PubMed

    Escandón, Lara S; Ordóñez, Salvador; Vega, Aurelio; Díez, Fernando V

    2005-01-01

    This work is focused on the deep catalytic oxidation of methane over supported palladium catalysts. The influences of the metal loading, oxidation state of palladium, nature of supports, presence of promoters in the supports (for zirconia-based supports), and thermal stability have been studied experimentally. Catalysts were prepared by incipient wetness of commercially available supports with aqueous solutions of palladium nitrate. For gamma-alumina support, it was observed that the optimal amount of palladium is between 0.5% and 2%, with higher amounts leading to a loss in specific activity. Concerning the oxidation state of the catalyst, it is concluded that for all the supports tested in the present work, a reduction of the catalyst is not needed, yielding the same conversion at steady state catalysts reduced and oxidised. The thermal stability of various supported catalysts were also studied, zirconia supports being the most active. These supports, specially Y-modified zirconia support, do not suffer appreciable deactivation below 500 degrees C.

  10. Hydrometallurgical recovery of silver from waste silver oxide button cells

    NASA Astrophysics Data System (ADS)

    Sathaiyan, N.; Nandakumar, V.; Ramachandran, P.

    In recent years, recycling of household batteries has attracted much attention mainly with respect to environmental aspects in addition to the savings. Small silver oxide primary cells used in electric watches become a waste after their life is over. Recycling procedures are needed to prevent any environmental impact from these wastes and to recover the value inherent in the scrap. Smelting and electrolytic methods are discussed for silver recovery from this battery waste. Acid leaching of waste batteries and precipitation of silver as silver chloride followed by smelting at 1000 °C yields a silver recovery of about 83%. An electrolytic route is studied as an alternative to the smelting operation and involves the electrodeposition of silver with higher purity from a silver thiosulfate complex prepared from silver chloride. The electrolysis is potentiostatically controlled at a potential of -0.400 to -0.600 V (SCE) for avoiding side-reactions such as the sulfiding of silver. Although recovery methods have been identified in principle, their suitability for mixed small battery waste and economic factors have yet to be demonstrated.

  11. Hexamitiasis in cadmium-exposed mice.

    PubMed

    Exon, J H; Patton, N M; Koller, L D

    1975-09-01

    Mortality was observed in 4- to 5-week-old Swiss Webster mice exposed to 300 or 3 ppm cadmium as cadmium chloride in the drinking water. Mice receiving 300 ppm cadium suffered 26% mortality as compared with 7% of those on the low cadmium dose. Death did not occur in control mice. Clinical signs and histopathology established Hexamita muris as the causative agent. Cadmium lesions were not observed. It is suggested that mortality due to hexamitiasis resulted from synergism between cadmium and H muris.

  12. The effect of cadmium on the environment

    SciTech Connect

    Cole, J.F.; Volpe, R.

    1983-02-01

    Information on the effect of cadmium in the environment reported during the past several years has raised considerable questions about the validity of past conclusions. For example, it appears that the critical concentration of cadmium in the renal cortex may be significantly higher than previously thought, and also, there is growing evidence that cadmium was not responsible for Itai-Itai disease in Japan. These findings concerning cadmium are encouraging and indicate that while cadmium is certainly toxic, the new information should be considered by governmental authorities before steps are taken to enact overly stringent regulations based on assumptions and regulations that may no longer be correct.

  13. Genetics Home Reference: Russell-Silver syndrome

    MedlinePlus

    ... Genetics Home Health Conditions Russell-Silver syndrome Russell-Silver syndrome Enable Javascript to view the expand/collapse ... Download PDF Open All Close All Description Russell-Silver syndrome is a growth disorder characterized by slow ...

  14. Nickel cadmium battery expert system

    NASA Technical Reports Server (NTRS)

    1986-01-01

    The applicability of artificial intelligence methodologies for the automation of energy storage management, in this case, nickel cadmium batteries, is demonstrated. With the Hubble Space Telescope Electrical Power System (HST/EPS) testbed as the application domain, an expert system was developed which incorporates the physical characterization of the EPS, in particular, the nickel cadmium batteries, as well as the human's operational knowledge. The expert system returns not only fault diagnostics but also status and advice along with justifications and explanations in the form of decision support.

  15. Silver Ink For Jet Printing

    NASA Technical Reports Server (NTRS)

    Vest, R. W.; Singaram, Saraswathi

    1989-01-01

    Metallo-organic ink containing silver (with some bismuth as adhesion agent) applied to printed-circuit boards and pyrolized in air to form electrically conductive patterns. Ink contains no particles of silver, does not have to be mixed during use to maintain homogeneity, and applied to boards by ink-jet printing heads. Consists of silver neodecanoate and bismuth 2-ethylhexanoate dissolved in xylene and/or toluene.

  16. Arsenic-cadmium interaction in rats.

    PubMed

    Díaz-Barriga, F; Llamas, E; Mejía, J J; Carrizales, L; Santoyo, M E; Vega-Vega, L; Yáñez, L

    1990-11-01

    Simultaneous exposure to cadmium and arsenic is highly probable in the urban area of San Luis Potosi, Mexico due to common localization of copper and zinc smelters. Therefore, in this work, rats were intraperitoneally exposed either to cadmium or arsenic alone, or simultaneously to both metals. The effects of these treatments on three different toxicological parameters were studied. Cadmium modified the LD50 of arsenic and conversely arsenic modified the LD50 for cadmium. At the histopathological level, arsenic appeared to protect against the cadmium effects, especially on testes. This protective effect seemed to be related to the glutathione levels found in this tissue: rats exposed to both arsenic and cadmium, presented glutathione values intermediate to those observed after exposure to either metal alone; arsenic had the highest value and cadmium the lowest. In liver, rats exposed to arsenic, cadmium or arsenic and cadmium, presented glutathione values below those in the saline group, with the lowest value corresponding to the arsenic and cadmium treatment. The results appear to support the proposed interaction between arsenic and cadmium and coexposure to both metals seems to alter certain effects produced by either metal alone. PMID:2219140

  17. Determination of cadmium in biological samples.

    PubMed

    Klotz, Katrin; Weistenhöfer, Wobbeke; Drexler, Hans

    2013-01-01

    Analyses of cadmium concentrations in biological material are performed using inductively coupled plasma mass spectrometry (ICP-MS) and atomic absorption spectrometry (AAS), but also electrochemical methods, neutron activation analysis (NAA), and X-ray fluorescence spectrometry (XRF). The predominant sample matrices include blood, plasma, serum, and urine, as well as hair, saliva, and tissue of kidney cortex, lung, and liver. While cadmium in blood reveals rather the recent exposure situation, cadmium in urine reflects the body burden and is an indicator for the cumulative long term exposure.After chronic exposure, cadmium accumulates in the human body and causes kidney diseases, especially lesions of proximal tubular cells. A tubular proteinuria causes an increase in urinary excretion of microproteins. Excretions of retinol binding protein (RBP), β2-microglobulin (β2-M), and α1-microglobulin are validated biomarkers for analyzing cadmium effects. For this purpose, immunological procedures such as ELISA, and radio- and latex-immunoassays are used.However, proteinuria is not specific to cadmium, but can also occur after exposure to other nephrotoxic agents or due to various kidney diseases. In summary, cadmium in urine and blood are the most specific biomarkers of cadmium exposure. A combination of parameters of exposure (cadmium in blood, cadmium in urine) and parameters of effect (e.g., β2-M, RBP) is required to reveal cadmium-induced nephrological effects. PMID:23430771

  18. Cadmium inhalation and male reproductive toxicity.

    PubMed

    Ragan, H A; Mast, T J

    1990-01-01

    Cadmium is a highly toxic element that is cumulative and has a long biological half-life in mammals. The severe toxicity of cadmium in man has been known for more than 100 years. Despite the knowledge that cadmium is toxic, only 20 human cases of poisoning via ingestion were recorded prior to 1941, whereas in the ensuing five-year period more than 680 cases of cadmium poisonings from accidental oral ingestion of this metal were documented. Some of the recorded effects of exposure to cadmium in laboratory animals include renal tubular damage, placental and testicular necrosis, structural and functional liver damage, osteomalacia, testicular tumors, teratogenic malformations, anemia, hypertension, pulmonary edema, chronic pulmonary emphysema, and induced deficiencies of iron, copper, and zinc. Some of these effects have also been observed in human after accidental exposures to cadmium oxide fumes and are characteristic of the syndrome described in Japan as Itai Itai disease in which ingestion of cadmium is the inciting chemical.

  19. MOD silver metallization for photovoltaics

    NASA Technical Reports Server (NTRS)

    Vest, G. M.; Vest, R. W.

    1984-01-01

    The development of flat plate solar arrays is reported. Photovoltaic cells require back side metallization and a collector grid system on the front surface. Metallo-organic decomposition (MOD) silver films can eliminate most of the present problems with silver conductors. The objectives are to: (1) identify and characterize suitable MO compounds; (2) develop generic synthesis procedures for the MO compounds; (3) develop generic fabrication procedures to screen printable MOD silver inks; (4) optimize processing conditions to produce grid patterns and photovoltaic cells; and (5) develop a model which describes the adhesion between the fired silver film and the silicon surface.

  20. Silver Nanoparticles in Dental Biomaterials

    PubMed Central

    Corrêa, Juliana Mattos; Mori, Matsuyoshi; Sanches, Heloísa Lajas; da Cruz, Adriana Dibo; Poiate, Isis Andréa Venturini Pola

    2015-01-01

    Silver has been used in medicine for centuries because of its antimicrobial properties. More recently, silver nanoparticles have been synthesized and incorporated into several biomaterials, since their small size provides great antimicrobial effect, at low filler level. Hence, these nanoparticles have been applied in dentistry, in order to prevent or reduce biofilm formation over dental materials surfaces. This review aims to discuss the current progress in this field, highlighting aspects regarding silver nanoparticles incorporation, such as antimicrobial potential, mechanical properties, cytotoxicity, and long-term effectiveness. We also emphasize the need for more studies to determine the optimal concentration of silver nanoparticle and its release over time. PMID:25667594

  1. Selective Facet Reactivity During Cation Exchange in Cadmium Sulfide Nanorods

    SciTech Connect

    Sadtler, Bryce; Demchenko, Denis; Zheng, Haimei; Hughes, Steven; Merkle, Maxwell; Dahmen, Ulrich; Wang, Lin-Wang; Alivisatos, A. Paul

    2008-12-18

    The partial transformation of ionic nanocrystals through cation exchange has been used to synthesize nanocrystal heterostructures. We demonstrate that the selectivity for cation exchange to take place at different facets of the nanocrystal plays an important role in determining the resulting morphology of the binary heterostructure. In the case of copper I (Cu+) cation exchange in cadmium sulfide (CdS) nanorods, the reaction starts preferentially at the ends of the nanorods such that copper sulfide (Cu2S) grows inwards from either end. The resulting morphology is very different from the striped pattern obtained in our previous studies of silver I (Ag+) exchange in CdS nanorods where non-selective nucleation of silver sulfide (Ag2S) occurs. From interface formation energies calculated for several models of epitaxialconnections between CdS and Cu2S or Ag2S, we infer the relative stability of each interface during the nucleation and growth of Cu2S or Ag2S within the CdS nanorods. The epitaxial connections of Cu2S to the end facets of CdS nanorods minimize the formation energy, making these interfaces stable throughout the exchange reaction. However, as the two end facets of wurtzite CdS nanorods are crystallographically nonequivalent, asymmetric heterostructures can be produced.

  2. Testing of a 7-tube palladium membrane reactor for potential use in TEP

    SciTech Connect

    Carlson, Bryan J; Trujillo, Stephen; Willms, R. Scott

    2010-01-01

    A Palladium Membrane Reactor (PMR) consists of a palladium/silver membrane permeator filled with catalyst (catalyst may be inside or outside the membrane tubes). The PMR is designed to recover tritium from the methane, water, and other impurities present in fusion reactor effluent. A key feature of a PMR is that the total hydrogen isotope content of a stream is significantly reduced as (1) methane-steam reforming and/or water-gas shift reactions proceed on the catalyst bed and (2) hydrogen isotopes are removed via permeation through the membrane. With a PMR design matched to processing requirements, nearly complete hydrogen isotope removals can be achieved. A 3-tube PMR study was recently completed. From the results presented in this study, it was possible to conclude that a PMR is appropriate for TEP, perforated metal tube protectors function well, platinum on aluminum (PtA) catalyst performs the best, conditioning with air is probably required to properly condition the Pd/Ag tubes, and that CO/CO{sub 2} ratios maybe an indicator of coking. The 3-tube PMR had a permeator membrane area of 0.0247 m{sup 2} and a catalyst volume to membrane area ratio of 4.63 cc/cm{sup 2} (with the catalyst on the outside of the membrane tubes and the catalyst only covering the membrane tube length). A PMR for TEP will require a larger membrane area (perhaps 0.35 m{sup 2}). With this in mind, an intermediate sized PMR was constructed. This PMR has 7 permeator tubes and a total membrane area of 0.0851 m{sup 2}. The catalyst volume to membrane area ratio for the 7-tube PMR was 5.18 cc/cm{sup 2}. The total membrane area of the 7-tube PMR (0.0851 m{sup 2}) is 3.45 times larger than total membrane area of the 3-tube PMR (0.0247 m{sup 2}). The following objectives were identified for the 7-tube PMR tests: (1) Refine test measurements, especially humidity and flow; (2) Refine maintenance procedures for Pd/Ag tube conditioning; (3) Evaluate baseline PMR operating conditions; (4) Determine PMR

  3. Palladium-catalyzed carbene migratory insertion using conjugated ene-yne-ketones as carbene precursors.

    PubMed

    Xia, Ying; Qu, Shuanglin; Xiao, Qing; Wang, Zhi-Xiang; Qu, Peiyuan; Chen, Li; Liu, Zhen; Tian, Leiming; Huang, Zhongxing; Zhang, Yan; Wang, Jianbo

    2013-09-11

    Palladium-catalyzed cross-coupling reactions between benzyl, aryl, or allyl bromides and conjugated ene-yne-ketones lead to the formation of 2-alkenyl-substituted furans. This novel coupling reaction involves oxidative addition, alkyne activation-cyclization, palladium carbene migratory insertion, β-hydride elimination, and catalyst regeneration. Palladium (2-furyl)carbene is proposed as the key intermediate, which is supported by DFT calculations. The palladium carbene character of the key intermediate is validated by three aspects, including bond lengths, Wiberg bond order indices, and molecular orbitals, by comparison to those reported for stable palladium carbene species. Computational studies also revealed that the rate-limiting step is ene-yne-ketone cyclization, which leads to the formation of the palladium (2-furyl)carbene, while the subsequent carbene migratory insertion is a facile process with a low energy barrier (<5 kcal/mol). PMID:23947689

  4. Microstructure-stability relations studies of porous chitosan microspheres supported palladium catalysts.

    PubMed

    Zeng, Minfeng; Zhang, Xin; Qi, Chenze; Zhang, Xian-Man

    2012-12-01

    In this study, polyethylene glycol (PEG) with different molecular weight, polyvinyl pyrrolidone (PVP), and polyvinyl alcohol (PVA), are chosen as porogens for preparing chitosan base porous microsphere supported palladium catalyst for coupling reactions. The pore structure of the microspheres was controlled by the compatibility of chitosan and counterpart polymers. The prepared porous chitosan microspheres supported palladium heterogeneous catalysts have been evaluated using the well-established Ullmann reductive homocoupling and the Heck cross-coupling reactions. The activities, stabilities and recyclability of the porous chitosan microspheres supported palladium catalysts are not only highly dependent upon the surface areas of the solid supports, but also upon the chemical properties of the water-soluble polymers. The degradation of the prepared heterogeneous palladium catalysts is mainly caused by a combination of the palladium leaching and the morphological transformation of the palladium species from the amorphous into the crystals.

  5. Aptamer selection for fishing of palladium ion using graphene oxide-adsorbed nanoparticles.

    PubMed

    Cho, Yea Seul; Lee, Eun Jeong; Lee, Gwan-Ho; Hah, Sang Soo

    2015-12-01

    A new aptamer selection method using graphene oxide (GO)-adsorbed nanoparticles (GO-adsorbed NPs) was employed for specific fishing of palladium ion. High affinity ssDNA aptamers were isolated through 13 rounds of selection and the capacity of the selected DNA aptamers for palladium ion uptake was measured, clarifying that DNA01 exhibits the highest affinity to palladium ion with a dissociation constant (Kd) of 4.60±1.17 μM. In addition, binding ability of DNA01 to palladium ion was verified against other metal ions, such as Li(+), Cs(+), Mg(2+), and Pt(2+). Results of the present study suggest that future modification of DNA01 may improve palladium ion-binding ability, leading to economic recovery of palladium from water solution.

  6. Cadmium in Jamaican Bush Teas

    PubMed Central

    Hoo Fung, LA; Rattray, VR; Lalor, GC

    2014-01-01

    Samples of Jamaican plants used as bush teas were collected from households in high soil-cadmium (Cd) areas of central Jamaica and analysed by graphite furnace atomic absorption spectrophotometry for total cadmium and for cadmium extractable with a hot water brew as prepared for human consumption to determine their contribution to dietary cadmium exposure. The concentrations ranged from < 0.03 to 6.85 μg/g for total Cd, between 1 and 15% of which was extracted with a hot water brew. One cup (200 ml) of the teas examined was found to contain < 0.04–1.18 μg of Cd and would contribute 0.1 – 0.3 μg of Cd to a person's dietary intake. This is significantly below the provisional tolerable weekly intake (PTWI) of 7 μg Cd/kg body weight established by the World Health Organization (WHO). While this suggests that bush tea consumption does not contribute significantly to the PTWI, some of the teas examined exceed the WHO recommendation of less than 0.3 mg/kg Cd for medicinal plants. PMID:25303189

  7. Mercury Telluride and Cadmium Telluride

    NASA Technical Reports Server (NTRS)

    2004-01-01

    A semiconductor's usefulness is determined by how atoms are ordered within the crystal's underlying three-dimensional structure. While this mercury telluride and cadmium telluride alloy sample mixes completely in Earth -based laboratories, convective flows prevent them from mixing uniformly. In space, the ingredients mix more homogenously, resulting in a superior product.

  8. Electronic properties of the silver-silver chloride cluster interface.

    PubMed

    Glaus, Stephan; Calzaferri, Gion; Hoffmann, Roald

    2002-04-15

    The objective of this study was to gain insight into the electronic structure of silver-silver chloride cluster composites and especially into the metal-semiconductor interface. For this purpose a theoretical study of (AgCl)(n) (n=4, 32, 108, 192, and 256), of Ag(m) (m=1-9, 30, 115, 276, and 409), and of the cluster composites Ag(115)-(AgCl)(192) and Ag(409)-(AgCl)(192) has been carried out. Density of levels (DOL), local density of levels (l-DOL), and projection of surface states, as well as projection of properties of individual atoms or groups of atoms obtained in molecular orbital calculations, are shown to be powerful tools for gaining deep insight into the properties of these large systems. The Ag(115)-(AgCl)(192) aggregate, consisting of a cubic Ag(115) cluster without corner atoms on top of a cubic (AgCl)(192) cluster, was found to be remarkably stable with a cluster-to-cluster distance of about 280 pm, and a geometry in which the number of bonding interactions between the silver atoms of Ag(115) and the chloride ions of (AgCl)(192) is at its maximum. A sharp jump in charge distribution occurs at the Ag(115)-(AgCl)(192) composite interface. The first AgCl slab picks up negative charge from the two adjacent silver slabs, so that in total the silver cluster is positively charged. In addition, the core of the silver cluster is positively charged with respect to its outermost layer. The main reason for the charge transfer from the silver cluster to the silver chloride is the newly formed MIGS (metal induced gap states) in the energy-gap range of the silver chloride and the MIdS (metal induced d states) in the d-orbital region. Their wave functions mix with orbitals of the silver cluster and with both the orbitals of the silver and the chloride ions of the silver chloride. The MIGS and the MIdS are of a quite localized nature. In them, nearest neighbor interactions dominate, with the exception of close-lying silver chloride surface states-which mix in to a large

  9. Method for recovering palladium and technetium values from nuclear fuel reprocessing waste solutions

    DOEpatents

    Horwitz, E. Philip; Delphin, Walter H.

    1979-07-24

    A method for recovering palladium and technetium values from nuclear fuel reprocessing waste solutions containing these and other values by contacting the waste solution with an extractant of tricaprylmethylammonium nitrate in an inert hydrocarbon diluent which extracts the palladium and technetium values from the waste solution. The palladium and technetium values are recovered from the extractant and from any other coextracted values with a strong nitric acid strip solution.

  10. Carbon-carbon cross coupling reactions in ionic liquids catalysed by palladium metal nanoparticles.

    PubMed

    Prechtl, Martin H G; Scholten, Jackson D; Dupont, Jairton

    2010-05-12

    A brief summary of selected pioneering and mechanistic contributions in the field of carbon-carbon cross-coupling reactions with palladium nanoparticles (Pd-NPs) in ionic liquids (ILs) is presented. Five exemplary model systems using the Pd-NPs/ILs approach are presented: Heck, Suzuki, Stille, Sonogashira and Ullmann reactions which all have in common the use of ionic liquids as reaction media and the use of palladium nanoparticles as reservoir for the catalytically active palladium species.

  11. Chelation of cadmium.

    PubMed Central

    Andersen, O

    1984-01-01

    The toxicity of cadmium is determined by chelation reactions: in vivo, Cd2+ exists exclusively in coordination complexes with biological ligands, or with administered chelating agents. The Cd2+ ion has some soft character, but it is not a typical soft ion. It has a high degree of polarizability, and its complexes with soft ligands have predominantly covalent bond characteristics. Cd2+ forms the most stable complexes with soft donor atoms (S much greater than N greater than 0). The coordination stereochemistry of Cd2+ is unusually varied, including coordination numbers from 2 to 8. Even though the Cd2+ ion is a d10 ion, disturbed coordination geometries are often seen. Generally, the stability of complexes increases with the number of coordination groups contributed by the ligand; consequently, complexes of Cd2+ with polydentate ligands containing SH groups are very stable. Cd2+ in metallothionein (MT) is coordinated with 4 thiolate groups, and the log stability constant is estimated to 25.5. Complexes between Cd2+ and low molecular weight monodentate or bidentate ligands, e.g., free amino acids (LMW-Cd), seem to exist very briefly, and Cd2+ is rapidly bound to high molecular weight proteins, mainly serum albumin. These complexes (HMW-Cd) are rapidly scavenged from blood, mainly by the liver, and Cd2+ is redistributed to MT. After about 1 day the Cd-MT complex (MT-Cd) almost exclusively accounts for the total retained dose of Cd2+, independent of the route of exposure. MT-Cd is slowly transferred to and accumulated in kidney cortex. The acute toxicity and interorgan distribution of parenterally administered Cd2+ are strongly influenced by preceding MT induction, or decreased capacity for MT synthesis; however, the gastrointestinal (GI) uptake of Cd2+ seems unaffected by preceding MT induction resulting in considerable capacity for Cd2+ chelation in intestinal mucosa, and this finding indicates that endogenous MT is not involved in Cd2+ absorption. The toxicity of

  12. Modulation of cadmium bioaccumulation and enhancing cadmium tolerance in Pichia kudriavzevii by sodium chloride preincubation.

    PubMed

    Ma, Ning; Li, Chunsheng; Zhang, Dandan; Yu, Jinzhi; Xu, Ying

    2016-07-01

    Application of growing microorganisms for cadmium removal is limited by the sensitivity of living cells to cadmium. The effects of sodium chloride (NaCl) preincubation on the cadmium bioaccumulation and tolerance of Pichia kudriavzevii and Saccharomyces cerevisiae were investigated in this study. NaCl preincubation significantly reduced the intracellular and cell-surface cadmium bioaccumulation of P. kudriavzevii at both 6 and 20 mg L(-1) cadmium, while no obvious effect was observed in S. cerevisiae except that the intracellular cadmium bioaccumulation at 20 mg L(-1) cadmium was reduced obviously by 20-60 g L(-1)  NaCl. For both yeasts, the improved contents of protein and proline after NaCl preincubation contributed to the cadmium tolerance. The thiol contents in P. kudriavzevii under cadmium stress were alleviated by NaCl preincubation, which might be due to the decrease of intracellular cadmium bioaccumulation. NaCl preincubation enhanced the contents of glycerol and trehalose in P. kudriavzevii under cadmium stress, while no acceleration was observed in S. cerevisiae. The results suggested that NaCl preincubation could be applied in cadmium removal by growing P. kudriavzevii to increase the cadmium tolerance of the yeast. PMID:26753521

  13. Distribution of cadmium in the pearl oyster following exposure to cadmium in seawater

    SciTech Connect

    Francesconi, K.A. )

    1989-08-01

    Laboratory studies on the uptake of cadmium from seawater have shown that bivalve molluscs readily accumulated cadmium from this medium and that the relative concentrations of cadmium between viscera and muscle were always the same as those found in natural populations. These results suggested that in the natural environment seawater was a major source of cadmium for bivalve molluscs. Results of a recent study have indicated that seawater is not always the major contributor of cadmium to bivalve molluscs. These authors reported high levels of cadmium in the pearl oyster Pinctada albina albina, collected from Shark Bay in Western Australia, and noted that there was no correlation between cadmium concentrations in the oysters and cadmium concentrations in the surrounding seawater. Australia is one of several countries which have a maximum permissible level of cadmium in molluscs. The possibility that the pearl oyster, and perhaps other molluscs as well, may accumulate cadmium preferentially in different tissues depending upon the source of cadmium has important implications in the area of contaminants in marine foodstuffs. The present study reports the uptake and distribution of cadmium within P. albina albina when subjected to cadmium in seawater alone.

  14. Modulation of cadmium bioaccumulation and enhancing cadmium tolerance in Pichia kudriavzevii by sodium chloride preincubation.

    PubMed

    Ma, Ning; Li, Chunsheng; Zhang, Dandan; Yu, Jinzhi; Xu, Ying

    2016-07-01

    Application of growing microorganisms for cadmium removal is limited by the sensitivity of living cells to cadmium. The effects of sodium chloride (NaCl) preincubation on the cadmium bioaccumulation and tolerance of Pichia kudriavzevii and Saccharomyces cerevisiae were investigated in this study. NaCl preincubation significantly reduced the intracellular and cell-surface cadmium bioaccumulation of P. kudriavzevii at both 6 and 20 mg L(-1) cadmium, while no obvious effect was observed in S. cerevisiae except that the intracellular cadmium bioaccumulation at 20 mg L(-1) cadmium was reduced obviously by 20-60 g L(-1)  NaCl. For both yeasts, the improved contents of protein and proline after NaCl preincubation contributed to the cadmium tolerance. The thiol contents in P. kudriavzevii under cadmium stress were alleviated by NaCl preincubation, which might be due to the decrease of intracellular cadmium bioaccumulation. NaCl preincubation enhanced the contents of glycerol and trehalose in P. kudriavzevii under cadmium stress, while no acceleration was observed in S. cerevisiae. The results suggested that NaCl preincubation could be applied in cadmium removal by growing P. kudriavzevii to increase the cadmium tolerance of the yeast.

  15. Separation of Hydrogen Using an Electroless Deposited Thin-Film Palladium-Ceramic Composite Membrane

    SciTech Connect

    Ilias, S.; King, F.G.; Fan, Ting-Fang; Roy, S.

    1996-12-31

    The primary objective of this project was to prepare and characterize a hydrogen permselective palladium-ceramic composite membrane for high temperature gas separations and catalytic membrane reactors. Electroless plating method was used to deposit a thin palladium film on microporous ceramic substrate. The objective of this paper is to discuss the preparation and characterization of a thin-film palladium-ceramic composite membrane for selective separation of hydrogen at elevated temperatures and pressures. In this paper, we also present a model to describe the hydrogen transport through the palladium-ceramic composite membrane in a cocurrent flow configuration.

  16. Review on palladium-containing perovskites: synthesis, physico-chemical properties and applications in catalysis.

    PubMed

    Essoumhi, Abdellatif; El Kazzouli, Saïd; Bousmina, Mosto

    2014-02-01

    This review reports on the recent advances in the synthesis and physico-chemical properties of palladium-containing perovskites. Initially, the perovskite structure is briefly reviewed, then palladium-containing perovskites synthesis and physico-chemical properties are detailed. The applications of palladium-containing perovskites in catalysis; namely, NO reduction, methane combustion, methanol as well as ethanol oxidation, are briefly highlighted. The involvement and the important contribution of palladium-containing perovskites in cross-coupling reactions, especially Suzuki-Miyaura, Sonogashira, Ulmann and Grignard, are discussed. PMID:24749470

  17. Extraction of palladium from acidic solutions with the use of carbon adsorbents

    SciTech Connect

    O.N. Kononova; N.G. Goryaeva; N.B. Dostovalova; S.V. Kachin; A.G. Kholmogorov

    2007-08-15

    We studied the sorption of palladium(II) on LKAU-4, LKAU-7, and BAU carbon adsorbents from model hydrochloric acid solutions and the solutions of spent palladium-containing catalysts. It was found that sorbents based on charcoal (BAU) and anthracite (LKAU-4) were characterized by high sorption capacities for palladium. The kinetics of the saturation of carbon adsorbents with palladium(II) ions was studied, and it was found that more than 60% of the initial amount of Pd(II) was recovered in a 1-h contact of an adsorbent with a model solution. This value for the solutions of spent catalysts was higher than 35%.

  18. Silver stain for electron microscopy

    NASA Technical Reports Server (NTRS)

    Corbett, R. L.

    1972-01-01

    Ammoniacal silver stain used for light microscopy was adapted advantageously for use with very thin biological sections required for electron microscopy. Silver stain can be performed in short time, has more contrast, and is especially useful for low power electron microscopy.

  19. Corrosion protection for silver reflectors

    DOEpatents

    Arendt, Paul N.; Scott, Marion L.

    1991-12-31

    A method of protecting silver reflectors from damage caused by contact with gaseous substances which are often present in the atmosphere and a silver reflector which is so protected. The inventive method comprises at least partially coating a reflector with a metal oxide such as aluminum oxide to a thickness of 15 .ANG. or less.

  20. Silver against Pseudomonas aeruginosa biofilms.

    PubMed

    Bjarnsholt, Thomas; Kirketerp-Møller, Klaus; Kristiansen, Søren; Phipps, Richard; Nielsen, Anne Kirstine; Jensen, Peter Østrup; Høiby, Niels; Givskov, Michael

    2007-08-01

    Silver has been recognized for its antimicrobial properties for centuries. Most studies on the antibacterial efficacy of silver, with particular emphasis on wound healing, have been performed on planktonic bacteria. Our recent studies, however, strongly suggest that colonization of wounds involves bacteria in both the planktonic and biofilm modes of growth. The action of silver on mature in vitro biofilms of Pseudomonas aeruginosa, a primary pathogen of chronic infected wounds, was investigated. The results show that silver is very effective against mature biofilms of P. aeruginosa, but that the silver concentration is important. A concentration of 5-10 mug/mL silver sulfadiazine eradicated the biofilm whereas a lower concentration (1 mug/mL) had no effect. The bactericidal concentration of silver required to eradicate the bacterial biofilm was 10-100 times higher than that used to eradicate planktonic bacteria. These observations strongly indicate that the concentration of silver in currently available wound dressings is much too low for treatment of chronic biofilm wounds. It is suggested that clinicians and manufacturers of the said wound dressings consider whether they are treating wounds primarily colonized either by biofilm-forming or planktonic bacteria.

  1. Cadmium content of plants as affected by soil cadmium concentration

    SciTech Connect

    Lehoczky, E.; Szabados, I.; Marth, P.

    1996-12-31

    Pot experiments were conducted in greenhouse conditions to study the effects of increasing cadmium (Cd) levels on biomass production and Cd contents in corn, (Zea mays L.), garlic (Allium sativum L.), and spinach (Spinacia oleracea L.). Plants were grown in two soil types: Eutric cambisol soil and A gleyic luvisol soil. Spinach proved to be the most sensitive to Cd treatments as its biomass considerably decreased with the increasing Cd levels. Cadmium contents of the three crops increased with increasing levels of Cd applications. Statistical differences were observed in the Cd contents of crops depending on soil type. With the same Cd rates, Cd tissue concentration of test plants grown in the strongly acidic Gleyic luvisol soil were many times higher than that of plants grown in a neutral Eutric cambisol soil. 14 refs., 4 tabs.

  2. METHOD TO TEST ISOTOPIC SEPARATION EFFICIENCY OF PALLADIUM PACKED COLUMNS

    SciTech Connect

    Heung, L; Gregory Staack, G; James Klein, J; William Jacobs, W

    2007-06-27

    The isotopic effect of palladium has been applied in different ways to separate hydrogen isotopes for many years. At Savannah River Site palladium deposited on kieselguhr (Pd/k) is used in a thermal cycling absorption process (TCAP) to purify tritium for over ten years. The need to design columns for different throughputs and the desire to advance the performance of TCAP created the need to evaluate different column designs and packing materials for their separation efficiency. In this work, columns with variations in length, diameter and metal foam use, were tested using an isotope displacement method. A simple computer model was also developed to calculate the number of theoretical separation stages using the test results. The effects of column diameter, metal foam and gas flow rate were identified.

  3. A stable single-site palladium catalyst for hydrogenations.

    PubMed

    Vilé, Gianvito; Albani, Davide; Nachtegaal, Maarten; Chen, Zupeng; Dontsova, Dariya; Antonietti, Markus; López, Núria; Pérez-Ramírez, Javier

    2015-09-14

    We report the preparation and hydrogenation performance of a single-site palladium catalyst that was obtained by the anchoring of Pd atoms into the cavities of mesoporous polymeric graphitic carbon nitride. The characterization of the material confirmed the atomic dispersion of the palladium phase throughout the sample. The catalyst was applied for three-phase hydrogenations of alkynes and nitroarenes in a continuous-flow reactor, showing its high activity and product selectivity in comparison with benchmark catalysts based on nanoparticles. Density functional theory calculations provided fundamental insights into the material structure and attributed the high catalyst activity and selectivity to the facile hydrogen activation and hydrocarbon adsorption on atomically dispersed Pd sites.

  4. The catalytic inactivation of cellulase enzyme components by palladium complexes

    SciTech Connect

    Woodward, J.; Gooch, M.G.; Shultz, M.D.

    1993-10-01

    It has been discovered that sodium hexachloropalladate is a strong inhibitor of cellobiohydrolase I (CBH I) from Trichoderma reesei having an I{sub 50} of <50 {mu}M with p-nitrophenylcellobioside (PNPC) as the substrate. Similar complexes of the metals platinum, osmium, iridium, and rhodium have little effect on CBH I. Other cellulase activities (Avicelase, {beta}-glucanase) are also inhibited by the palladium complex, suggesting that inhibition of two major types of catalytic activity in cellulase are affected. Preliminary data on the kinetics of inhibition of CBH I by sodium hexachloropalladate indicate that the inhibition is reversible and, possibly, uncompetitive. It is anticipated that sodium hexachloropalladate and other palladium complexes will be useful for determining the effect of the binding of catalytically inactivated CBH I and other cellulase components on the structure of cellulose fibers.

  5. A DFT study of arsine adsorption on palladium doped graphene: Effects of palladium cluster size

    NASA Astrophysics Data System (ADS)

    Kunaseth, Manaschai; Mudchimo, Tanabat; Namuangruk, Supawadee; Kungwan, Nawee; Promarak, Vinich; Jungsuttiwong, Siriporn

    2016-03-01

    In this study, we have investigated the size effects of palladium (Pd) doped single-vacancy defective graphene (SDG) surface to the adsorption of AsH3 and its dehydrogenated products on Pd using density functional theory calculations. Here, Pd cluster binding study revealed that Pd6 nanocluster bound strongest to the SDG surface, while adsorption of AsHx (x = 0-3) on the most stable Pdn doped SDG showed that dehydrogenated arsine compounds adsorbed onto the surface stronger than the pristine AsH3 molecule. Charge analysis revealed that considerable amount of charge migration from Pd to dehydrogenated arsine molecules after adsorption may constitute strong adsorption for dehydrogenated arsine. In addition, study of thermodynamic pathways of AsH3 dehydrogenation on Pdn doped SDG adsorbents indicated that Pd cluster doping on SDG adsorbent tends to be thermodynamically favorable for AsH3 decomposition than the single-Pd atom doped SDG. Hence, our study has indicated that Pd6 clusters doped SDG is more advantageous as adsorbent material for AsH3 removal.

  6. Sea ducks and aquaculture: the cadmium connection.

    PubMed

    Bendell, L I

    2011-03-01

    Elevated concentrations of cadmium have been reported in the kidneys of sea ducks that forage along the Pacific Northwest, and cadmium has been postulated as a possible cause of population declines. The blue mussel (Mytilus spp.) which occurs in dense numbers on aquaculture structures and are a primary prey item for sea ducks also contain elevated cadmium concentrations. To determine if foraging on mussels associated with aquaculture structures could pose a toxicological risk to sea ducks, amounts of cadmium ingested per body weight per day by a representative sea duck species, the surf scoter (Melanitta perspicillata), were estimated and compared to the reported avian cadmium NOAEL (no observable adverse effect level) and LOAEL (lowest observable adverse effect level). Results indicate that in some locations within the Pacific Northwest, sea ducks could be exposed to toxicologically significant levels of cadmium associated with mussels foraged from aquaculture structures. This raises the possibility that such exposure could be contributing to observed population declines in these species.

  7. Cadmium resistance in Drosophila: a small cadmium binding substance

    SciTech Connect

    Jacobson, K.B.; Williams, M.W.; Richter, L.J.; Holt, S.E.; Hook, G.J.; Knoop, S.M.; Sloop, F.V.; Faust, J.B.

    1985-01-01

    A small cadmium-binding substance (CdBS) has been observed in adult Drosophila melanogaster that were raised for their entire growth cycle on a diet that contained 0.15 mM CdCl/sub 2/. Induction of CdBS was observed in strains that differed widely in their sensitivity of CdCl/sub 2/. This report describes the induction of CdBS and some of its characteristics. 17 refs., 4 figs., 1 tab.

  8. Rethinking Schools and the Power of Silver

    ERIC Educational Resources Information Center

    Sleeter, Christine

    2011-01-01

    This 25th anniversary of "Rethinking Schools" can be thought of as its silver anniversary. Silver itself must be considered through contrasting lenses. On the one hand, as lessons in "Rethinking Globalization" teach, silver and gold were the basis of Europe's horrendous exploitation of Latin America. On the other hand, silver is often associated…

  9. Tolerance to cadmium and cadmium-binding ligands in Great Salt Lake brine shrimp (Artemia salina)

    SciTech Connect

    Jayasekara, S.; Drown, D.B.; Sharma, R.P.

    1986-02-01

    Information on the accumulation of cadmium in cytosolic proteins of Great Lake brine shrimp (Artemia salina) was obtained from animals collected directly from the lake and also from animal hatched and maintained in three sublethal concentrations of cadmium (0.5, 2.0, 5.0 ppm) in saltwater aquaria. Brine shrimp growth under these conditions was monitored by measuring body lengths during a 7-day exposure period. Heat-stable, cadmium-binding ligands were isolated and identified by Sephadex G-75 chromatography and atomic absorption spectrophotometry. Cadmium was found to be equally distributed between high and low molecular weight proteins in animals collected from the lake and the 0.5 ppm cadmium group. There was also a slight growth stimulation noted in the 0.5-pm group. Higher cadmium incorporation was noted in low molecular weight fractions with increasing cadmium concentration in the exposure media. Low molecular weight fractions were also found to have high uv absorption characteristics at 250 nm and low absorption at 280 nm. Molecular weight of the cadmium-binding ligands was found to be 11,000 as estimated by the gel filtration method. De novo synthesis of this protein was increased as a function of cadmium concentration in the media. However, slow accumulation of cadmium in other protein fractions was also noticed in higher cadmium exposure groups, suggesting the existence of possible tolerance mechanisms in brine shrimp exposed to suspected acute cadmium concentrations.

  10. Cadmium in smoke particulates of regular and filter cigarettes containing low and high cadmium concentrations

    SciTech Connect

    Bache, C.A.; Reid, C.M.; Hoffman, D.; Adams, J.D.; Lisk, D.J.

    1986-03-01

    In the work reported, filter and nonfilter cigarettes were prepared from high-cadmium tobacco grown on a municipal sludge-amended soil or a low-cadmium tobacco grown on untreated soil alone. These were smoked by machine to determine the effectiveness of the cigarette filters in possibly reducing the quantities of cadmium in the mainstream smoke particulates.

  11. Metallothionein-like cadmium binding protein in rat testes administered with cadmium and selenium

    SciTech Connect

    Ohta, H.; Seki, Y.; Imamiya, S.

    1988-08-01

    It is well known that the testicular damage caused by acute cadmium toxicity are protected by simultaneous selenium administration with cadmium, and that the cadmium concentration in the testis increases remarkably as compared with that of only cadmium administration. The increased cadmium in the testis was found in the high molecular weight fraction containing selenium, and it has been thought that the shift of cadmium from the low molecular weight fraction to the high molecular weight fraction containing selenium is an important protection mechanism. However, the cadmium concentration in this high molecular weight fraction decreased with time, then re-shifted to the fraction of metallothionein, a low molecular weight protein having a protective effect against cadmium toxicity. While recently studying the cadmium binding protein, like metallothionein, in testes, it has been reported that the amino acid composition of cadmium binding protein in testis is not similar to that of the hepatic metallothionein. The present study was undertaken to clarify the properties of the increased cadmium binding protein in the testis protected by simultaneous selenium administration with cadmium.

  12. Unsupported palladium alloy membranes and methods of making same

    SciTech Connect

    Way, J. Douglas; Thoen, Paul; Gade, Sabina K.

    2015-06-02

    The invention provides support-free palladium membranes and methods of making these membranes. Single-gas testing of the unsupported foils produced hydrogen permeabilities equivalent to thicker membranes produced by cold-rolling. Defect-free films as thin as 7.2 microns can be fabricated, with ideal H.sub.2/N.sub.2 selectivities as high as 40,000. Homogeneous membrane compositions may also be produced using these methods.

  13. Palladium Catalyzed Intramolecular Acylcyanation of Alkenes Using α-Iminonitriles

    PubMed Central

    Rondla, Naveen R.; Ogilvie, Jodi M.; Pan, Zhongda

    2014-01-01

    Reported here is a palladium catalyzed intramolecular acylcyanation of alkenes using α-iminonitriles. Through this method, highly functionalized indanones are synthesized in moderate to high yields using Pd(PPh3)4, without need for any additional ligands, and a common Lewis acid (ZnCl2). Additionally, the reaction tolerates substitution at various positions on the aromatic ring including electron donating, and electron withdrawing groups. PMID:24980625

  14. Biaryl Phosphine Ligands in Palladium-Catalyzed Amination

    PubMed Central

    Surry, David S.

    2012-01-01

    Palladium-catalyzed amination of aryl halides has undergone rapid development in the last 12 years. This has been largely driven by implementation of new classes of ligands. Biaryl phosphines have proven to provide especially active catalysts in this context. This review discusses the applications that these catalysts have found in C-N cross-coupling in heterocycle synthesis, pharmaceuticals, materials science and natural product synthesis. PMID:18663711

  15. TCAP HYDROGEN ISOTOPE SEPARATION USING PALLADIUM AND INVERSE COLUMNS

    SciTech Connect

    Heung, L.; Sessions, H.; Xiao, S.

    2010-08-31

    The Thermal Cycling Absorption Process (TCAP) was further studied with a new configuration. Previous configuration used a palladium packed column and a plug flow reverser (PFR). This new configuration uses an inverse column to replace the PFR. The goal was to further improve performance. Both configurations were experimentally tested. The results showed that the new configuration increased the throughput by a factor of more than 2.

  16. Cadmium content of umbilical cord blood

    SciTech Connect

    Rabinowitz, M.; Finch, H.

    1984-06-01

    Cadmium was measured in the umbilical cord blood at birth from 94 healthy babies. Samples were dried and ashed at low temperatures with an oxygen plasma prior to atomic absorption spectrometry. The concentration of cadmium ranged from 0.003 to 0.210 ..mu..g/dl, with a mean of 0.045 +/- 0.063 (SD). Blood lead, maternal smoking, and proximity of residence to automobile traffic were not statistically related to cadmium levels.

  17. Plasma cadmium and zinc in human hypertension.

    PubMed

    Thind, G S; Fischer, G M

    1976-11-01

    1. Plasma cadmium and zinc were determined by atomic absorption spectrophotometry in inferior venal caval or peripheral venous blood in thrity hypertensive patients and fifteen normal subjects. 2. The mean plasma cadium in hypertensive patients was significantly higher than in normal control subjects. 3. The plasma cadmium/zinc ratio was significantly greater in hypertensive patients. 4. There was a significant positive correlation between the plasma cadmium/zinc ratio and the mean arterial blood pressure.

  18. Thermal stability of PLD grown silver nanoparticles

    NASA Astrophysics Data System (ADS)

    Shokeen, Poonam; Jain, Amit; Kapoor, Avinashi

    2016-05-01

    Present work discusses the stability of silver nanoparticles at different annealing temperatures. Air muffle furnace annealing is performed to study the thermal stability of pulsed laser deposited silver nanoparticles. Silver reacts with atmospheric oxygen to form silver oxide at annealing temperatures below 473K and thermal decomposition of silver oxide takes place at temperatures above 473K. Oxide formation results in core shrinkage of silver, which in turn affects the surface plasmon resonance of silver nanoparticles. With increase in annealing temperature, the surface plasmon effect of nanoparticles starts to fade. SEM, XRD and UV-vis spectroscopy have been performed to analysis various structural and optical properties.

  19. A Silver DNAzyme.

    PubMed

    Saran, Runjhun; Liu, Juewen

    2016-04-01

    Silver is a very common heavy metal, and its detection is of significant analytical importance. DNAzymes are DNA-based catalysts; they typically recruit divalent and trivalent metal ions for catalysis. Herein, we report a silver-specific RNA-cleaving DNAzyme named Ag10c obtained after six rounds of in vitro selection. Ag10c displays a catalytic rate of 0.41 min(-1) with 10 μM Ag(+) at pH 7.5 with 200 mM NaNO3, while its activity is completely inhibited with the same concentration of NaCl. Ag10c is highly specific for Ag(+) among all the tested metals. A catalytic beacon biosensor is designed by labeling a fluorophore and a quencher on the DNAzyme. Fluorescence enhancement is observed in the presence of Ag(+) with a detection limit of 24.9 nM Ag(+). The sensor shows a similar analytical performance in Lake Huron water. This is the first monovalent transition metal dependent RNA-cleaving DNAzyme. Apart from its biosensor application, this study strengthens the idea of exploring beyond the traditional understanding of multivalent ion dependent DNAzyme catalysis. PMID:26977895

  20. A Silver DNAzyme.

    PubMed

    Saran, Runjhun; Liu, Juewen

    2016-04-01

    Silver is a very common heavy metal, and its detection is of significant analytical importance. DNAzymes are DNA-based catalysts; they typically recruit divalent and trivalent metal ions for catalysis. Herein, we report a silver-specific RNA-cleaving DNAzyme named Ag10c obtained after six rounds of in vitro selection. Ag10c displays a catalytic rate of 0.41 min(-1) with 10 μM Ag(+) at pH 7.5 with 200 mM NaNO3, while its activity is completely inhibited with the same concentration of NaCl. Ag10c is highly specific for Ag(+) among all the tested metals. A catalytic beacon biosensor is designed by labeling a fluorophore and a quencher on the DNAzyme. Fluorescence enhancement is observed in the presence of Ag(+) with a detection limit of 24.9 nM Ag(+). The sensor shows a similar analytical performance in Lake Huron water. This is the first monovalent transition metal dependent RNA-cleaving DNAzyme. Apart from its biosensor application, this study strengthens the idea of exploring beyond the traditional understanding of multivalent ion dependent DNAzyme catalysis.

  1. Retiring the Silver Bullet

    SciTech Connect

    Lasure, Linda L.

    2006-01-01

    Over the past few decades, advances in biology and electronics have resulted in an enormous increase in the screening rate of new compounds and in the capacity to synthesize vast numbers of new compounds. The understanding of disease has greatly improved. At the same time, the number of targets (or diseases) for the silver bullets has also increased. Yet, the belief that we have to screen enormous numbers of compounds to find the next new drug continues. Today, disease is understood to be a complex interaction of many systems. This ought to cause us to change our paradigm, but it has not. The fundamental reason for the apparent failure of our drug discovery and development research is that we are operating under the constraints of an out-of-date paradigm. The silver-bullet paradigm has always been a myth. Now is the time to debunk the myth and change the paradigm. Our other option is to continue on as we are and accept that the United States will become obsolete on the playing field of drug discovery.

  2. Thermodynamics of the hybrid interaction of hydrogen with palladium nanoparticles

    NASA Astrophysics Data System (ADS)

    Griessen, Ronald; Strohfeldt, Nikolai; Giessen, Harald

    2016-03-01

    Palladium-hydrogen is a prototypical metal-hydrogen system. It is therefore not at all surprising that a lot of attention has been devoted to the absorption and desorption of hydrogen in nanosized palladium particles. Several seminal articles on the interaction of H with Pd nanocubes and nanoparticles have recently been published. Although each article provides for the first time detailed data on specific aspects of hydrogen in nanoparticles, they individually do not contain enough information to draw firm conclusions about the involved mechanisms. Here, we show that the large body of data available so far in literature exhibits general patterns that lead to unambiguous conclusions about the processes involved in H absorption and desorption in Pd nanoparticles. On the basis of a remarkably robust scaling law for the hysteresis in absorption-desorption isotherms, we show that hydrogen absorption in palladium nanoparticles is consistent with a coherent interface model and is thus clearly different from bulk Pd behaviour. However, H desorption occurs fully coherently only for small nanoparticles (typically smaller than 50 nm) at temperatures sufficiently close to the critical temperature. For larger particles it is partially incoherent, as in bulk, where dilute α-PdHx and high concentration β-PdHx phases coexist.

  3. Platinum and palladium oxalates: positive-tone extreme ultraviolet resists

    NASA Astrophysics Data System (ADS)

    Sortland, Miriam; Hotalen, Jodi; Re, Ryan Del; Passarelli, James; Murphy, Michael; Kulmala, Tero S.; Ekinci, Yasin; Neisser, Mark; Freedman, Daniel A.; Brainard, Robert L.

    2015-10-01

    Here, we present platinum and palladium mononuclear complexes with EUV photosensitivity and lithographic performance. Many platinum and palladium complexes show little or no EUV sensitivity; however, we have found that metal carbonates and metal oxalates (L2M(CO3) and L2M(C2O4); M=Pt or Pd) are sensitive to EUV. The metal carbonates give negative-tone behavior. The most interesting result is that the metal oxalates give the first positive-tone EUV resists based on mononuclear organometallic compounds. In particular, (dppm)Pd(C2O4) (dppm=1,1-bis(diphenylphosphino)methane) (23) prints 30-nm dense lines with E of 50 mJ/cm2. Derivatives of (23) were synthesized to explore the relationship between the core metal and the resist sensitivity. The study showed that palladium-based resists are more sensitive than platinum-based resists. The photoreaction has been investigated for two of our most promising resists, (dppm)Pd(C2O4) (23) and EtPPdC2O4 (27). Our experiments suggest the loss of CO2 and the formation of a zerovalent L4Pd complex upon exposure to light. We have identified dppm2Pd(δ(P)23.6) as the main photoproduct for (23) and EtPPd (δ(P)32.7) as the main photoproduct for (27).

  4. Methane ignition catalyzed by in situ generated palladium nanoparticles

    SciTech Connect

    Shimizu, T.; Abid, A.D.; Poskrebyshev, G.; Wang, H.; Nabity, J.; Engel, J.; Yu, J.; Wickham, D.; Van Devener, B.; Anderson, S.L.; Williams, S.

    2010-03-15

    Catalytic ignition of methane over the surfaces of freely-suspended and in situ generated palladium nanoparticles was investigated experimentally and numerically. The experiments were conducted in a laminar flow reactor. The palladium precursor was a compound (Pd(THD){sub 2}, THD: 2,2,6,6-tetramethyl-3,5-heptanedione) dissolved in toluene and injected into the flow reactor as a fine aerosol, along with a methane-oxygen-nitrogen mixture. For experimental conditions chosen in this study, non-catalytic, homogeneous ignition was observed at a furnace temperature of {proportional_to}1123 K, whereas ignition of the same mixture with the precursor was found to be {proportional_to}973 K. In situ production of Pd/PdO nanoparticles was confirmed by scanning mobility, transmission electron microscopy and X-ray photoelectron spectroscopy analyses of particles collected at the reactor exit. The catalyst particle size distribution was log-normal. Depending on the precursor loading, the median diameter ranged from 10 to 30 nm. The mechanism behind catalytic ignition was examined using a combined gas-phase and gas-surface reaction model. Simulation results match the experiments closely and suggest that palladium nanocatalyst significantly shortens the ignition delay times of methane-air mixtures over a wide range of conditions. (author)

  5. Thermodynamics of the hybrid interaction of hydrogen with palladium nanoparticles.

    PubMed

    Griessen, Ronald; Strohfeldt, Nikolai; Giessen, Harald

    2016-03-01

    Palladium-hydrogen is a prototypical metal-hydrogen system. It is therefore not at all surprising that a lot of attention has been devoted to the absorption and desorption of hydrogen in nanosized palladium particles. Several seminal articles on the interaction of H with Pd nanocubes and nanoparticles have recently been published. Although each article provides for the first time detailed data on specific aspects of hydrogen in nanoparticles, they individually do not contain enough information to draw firm conclusions about the involved mechanisms. Here, we show that the large body of data available so far in literature exhibits general patterns that lead to unambiguous conclusions about the processes involved in H absorption and desorption in Pd nanoparticles. On the basis of a remarkably robust scaling law for the hysteresis in absorption-desorption isotherms, we show that hydrogen absorption in palladium nanoparticles is consistent with a coherent interface model and is thus clearly different from bulk Pd behaviour. However, H desorption occurs fully coherently only for small nanoparticles (typically smaller than 50 nm) at temperatures sufficiently close to the critical temperature. For larger particles it is partially incoherent, as in bulk, where dilute α-PdHx and high concentration β-PdHx phases coexist.

  6. Thermodynamics of the hybrid interaction of hydrogen with palladium nanoparticles.

    PubMed

    Griessen, Ronald; Strohfeldt, Nikolai; Giessen, Harald

    2016-03-01

    Palladium-hydrogen is a prototypical metal-hydrogen system. It is therefore not at all surprising that a lot of attention has been devoted to the absorption and desorption of hydrogen in nanosized palladium particles. Several seminal articles on the interaction of H with Pd nanocubes and nanoparticles have recently been published. Although each article provides for the first time detailed data on specific aspects of hydrogen in nanoparticles, they individually do not contain enough information to draw firm conclusions about the involved mechanisms. Here, we show that the large body of data available so far in literature exhibits general patterns that lead to unambiguous conclusions about the processes involved in H absorption and desorption in Pd nanoparticles. On the basis of a remarkably robust scaling law for the hysteresis in absorption-desorption isotherms, we show that hydrogen absorption in palladium nanoparticles is consistent with a coherent interface model and is thus clearly different from bulk Pd behaviour. However, H desorption occurs fully coherently only for small nanoparticles (typically smaller than 50 nm) at temperatures sufficiently close to the critical temperature. For larger particles it is partially incoherent, as in bulk, where dilute α-PdHx and high concentration β-PdHx phases coexist. PMID:26569476

  7. Nanometer-Size Effect on Hydrogen Sites in Palladium Lattice.

    PubMed

    Akiba, Hiroshi; Kofu, Maiko; Kobayashi, Hirokazu; Kitagawa, Hiroshi; Ikeda, Kazutaka; Otomo, Toshiya; Yamamuro, Osamu

    2016-08-17

    Nanometer-sized materials attract much attention because their physical and chemical properties are substantially different from those of bulk materials owing to their size and surface effects. In this work, neutron powder diffraction experiments on the nanoparticles of palladium hydride, which is the most popular metal hydride, have been performed at 300, 150, and 44 K to investigate the positions of the hydrogen atoms in the face-centered cubic (fcc) lattice of palladium. We used high-quality PdD0.363 nanocrystals with a diameter of 8.0 ± 0.9 nm. The Rietveld analysis revealed that 30% of D atoms are located at the tetrahedral (T) sites and 70% at the octahedral (O) sites. In contrast, only the O sites are occupied in bulk palladium hydride and in most fcc metal hydrides. The temperature dependence of the T-site occupancy suggested that the T-sites are occupied only in a limited part, probably in the subsurface region, of the nanoparticles. This is the first study to determine the hydrogen sites in metal nanoparticles. PMID:27462875

  8. Process for making silver metal filaments

    DOEpatents

    Bamberger, Carlos E.

    1997-01-01

    A process for making silver metal particles from silver salt particles having the same morphology. Precursor silver salt particles selected from the group consisting of silver acetate and silver sulfide having a selected morphology are contained in a reactor vessel having means for supporting the particles in an air suspension to prevent the agglomeration of the particles. Air is flowed through the reactor vessel at a flow rate sufficient to suspend the particles in the reactor vessel. The suspended precursor silver salt particles are heated to a processing temperature and at a heating rate below which the physical deterioration of the suspended precursor silver salt particles takes place. The suspended precursor silver salt particles are maintained at the processing temperature for a period of time sufficient to convert the particles into silver metal particles having the same morphology as the precursor silver salt particles.

  9. Process for making silver metal filaments

    SciTech Connect

    Bamberger, C.E.

    1997-05-06

    A process is disclosed for making silver metal particles from silver salt particles having the same morphology. Precursor silver salt particles selected from the group consisting of silver acetate and silver sulfide having a selected morphology are contained in a reactor vessel having means for supporting the particles in an air suspension to prevent the agglomeration of the particles. Air is flowed through the reactor vessel at a flow rate sufficient to suspend the particles in the reactor vessel. The suspended precursor silver salt particles are heated to a processing temperature and at a heating rate below which the physical deterioration of the suspended precursor silver salt particles takes place. The suspended precursor silver salt particles are maintained at the processing temperature for a period of time sufficient to convert the particles into silver metal particles having the same morphology as the precursor silver salt particles. 1 fig.

  10. Microbial Responses to Environmentally Toxic Cadmium.

    PubMed

    Roane; Pepper

    1999-11-01

    We analyzed the soil microbial communities from one uncontaminated and two metal-impacted soils and found that while cadmium adversely affected the numbers of culturable bacteria in all soils, cadmium-resistant isolates were found from each of the soils. With exposure to 24 and 48 µg ml(-1) soluble cadmium, the metal-contaminated soil communities were more resistant than the uncontaminated soil community. In addition, in one metal-stressed soil, the resistant population became more resistant with increased cadmium levels. Ribosomal 16S DNA sequencing identified the isolates as Arthrobacter, Bacillus, or Pseudomonas spp. Further characterization demonstrated that two of the isolates were highly resistant to soluble cadmium with maximum resistance at 275 µg ml(-1) cadmium. These isolates were also resistant to a variety of antibiotics, namely ampicillin, gentamicin, penicillin, and streptomycin, but no overall correlation was found between enhanced antibiotic resistance and cadmium resistance. One Pseudomonas isolate H1 did become more resistant with increasing cadmium levels, suggesting a different resistance mechanism at high cadmium concentrations. PMID:10758182

  11. The Epigenetic Effects of Prenatal Cadmium Exposure.

    PubMed

    Vilahur, Nadia; Vahter, Marie; Broberg, Karin

    2015-06-01

    Prenatal exposure to the highly toxic and common pollutant cadmium has been associated with adverse effects on child health and development. However, the underlying biological mechanisms of cadmium toxicity remain partially unsolved. Epigenetic disruption due to early cadmium exposure has gained attention as a plausible mode of action, since epigenetic signatures respond to environmental stimuli and the fetus undergoes drastic epigenomic rearrangements during embryogenesis. In the current review, we provide a critical examination of the literature addressing prenatal cadmium exposure and epigenetic effects in human, animal, and in vitro studies. We conducted a PubMed search and obtained eight recent studies addressing this topic, focusing almost exclusively on DNA methylation. These studies provide evidence that cadmium alters epigenetic signatures in the DNA of the placenta and of the newborns, and some studies indicated marked sexual differences for cadmium-related DNA methylation changes. Associations between early cadmium exposure and DNA methylation might reflect interference with de novo DNA methyltransferases. More studies, especially those including environmentally relevant doses, are needed to confirm the toxicoepigenomic effects of prenatal cadmium exposure and how that relates to the observed health effects of cadmium in childhood and later life.

  12. Process for removing cadmium from scrap metal

    DOEpatents

    Kronberg, J.W.

    1995-04-11

    A process is described for the recovery of a metal, in particular, cadmium contained in scrap, in a stable form. The process comprises the steps of mixing the cadmium-containing scrap with an ammonium carbonate solution, preferably at least a stoichiometric amount of ammonium carbonate, and/or free ammonia, and an oxidizing agent to form a first mixture so that the cadmium will react with the ammonium carbonate to form a water-soluble ammine complex; evaporating the first mixture so that ammine complex dissociates from the first mixture leaving carbonate ions to react with the cadmium and form a second mixture that includes cadmium carbonate; optionally adding water to the second mixture to form a third mixture; adjusting the pH of the third mixture to the acid range whereby the cadmium carbonate will dissolve; and adding at least a stoichiometric amount of sulfide, preferably in the form of hydrogen sulfide or an aqueous ammonium sulfide solution, to the third mixture to precipitate cadmium sulfide. This mixture of sulfide is then preferably digested by heating to facilitate precipitation of large particles of cadmium sulfide. The scrap may be divided by shredding or breaking up to expose additional surface area. Finally, the precipitated cadmium sulfide can be mixed with glass formers and vitrified for permanent disposal. 2 figures.

  13. Effects of dietary cadmium on mallard ducklings

    USGS Publications Warehouse

    Cain, B.W.; Sileo, L.; Franson, J.C.; Moore, J.

    1983-01-01

    Mallard (Anas platyrhynchos) ducklings were fed cadmium in the diet at 0, 5, 10, or 20 ppm from 1 day of age until 12 weeks of age. At 4-week intervals six males and six females from each dietary group were randomly selected, bled by jugular venipuncture, and necropsied. Significant decreases in packed cell volume (PCV) and hemoglobin (Hb) concentration and a significant increase in serum glutamic pyruvic transaminase (GPT) were found at 8 weeks of age in ducklings fed 20 ppm cadmium. Mild to severe kidney lesions were evident in ducklings fed 20 ppm cadmium for 12 weeks. No other blood chemistry measurement, hematological parameter, or tissue histopathological measurement indicated a reaction to cadmium ingestion. Body weight, liver weight, and the ratio of the femur weight to length were not affected by dietary cadmium. Femur cadmium concentration In all ducklings 12 weeks of age declined from the values detected at 4 and 8 weeks of age. Liver cadmium concentrations were significantly higher in relation to the increased dietary levels and in relation to the length of time the ducklings were fed the cadmium diets. At 12 weeks of age the cadmium concentration in liver tissue was twice that in the diet.

  14. Process for removing cadmium from scrap metal

    DOEpatents

    Kronberg, James W.

    1995-01-01

    A process for the recovery of a metal, in particular, cadmium contained in scrap, in a stable form. The process comprises the steps of mixing the cadmium-containing scrap with an ammonium carbonate solution, preferably at least a stoichiometric amount of ammonium carbonate, and/or free ammonia, and an oxidizing agent to form a first mixture so that the cadmium will react with the ammonium carbonate to form a water-soluble ammine complex; evaporating the first mixture so that ammine complex dissociates from the first mixture leaving carbonate ions to react with the cadmium and form a second mixture that includes cadmium carbonate; optionally adding water to the second mixture to form a third mixture; adjusting the pH of the third mixture to the acid range whereby the cadmium carbonate will dissolve; and adding at least a stoichiometric amount of sulfide, preferably in the form of hydrogen sulfide or an aqueous ammonium sulfide solution, to the third mixture to precipitate cadmium sulfide. This mixture of sulfide is then preferably digested by heating to facilitate precipitation of large particles of cadmium sulfide. The scrap may be divided by shredding or breaking up to expose additional surface area. Finally, the precipitated cadmium sulfide can be mixed with glass formers and vitrified for permanent disposal.

  15. Process for removing cadmium from scrap metal

    DOEpatents

    Kronberg, J.W.

    1994-01-01

    A process for the recovery of a metal, in particular, cadmium contained in scrap, in a stable form. The process comprises the steps of mixing the cadmium-containing scrap with an ammonium carbonate solution, preferably at least a stoichiometric amount of ammonium carbonate, and/or free ammonia, and an oxidizing agent to form a first mixture so that the cadmium will react with the ammonium carbonate to form a water-soluble ammine complex; evaporating the first mixture so that ammine complex dissociates from the first mixture leaving carbonate ions to react with the cadmium and form a second mixture that includes cadmium carbonate; optionally adding water to the second mixture to form a third mixture; adjusting the pH of the third mixture to the acid range whereby the cadmium carbonate will dissolve; and adding at least a stoichiometric amount of sulfide, preferably in the form of hydrogen sulfide or an aqueous ammonium sulfide solution, to the third mixture to precipitate cadmium sulfide. This mixture of sulfide is then preferably digested by heating to facilitate precipitation of large particles of cadmium sulfide. The scrap may be divided by shredding or breaking up to exposure additional surface area. Finally, the precipitated cadmium sulfide can be mixed with glass formers and vitrified for permanent disposal.

  16. Cadmium, metallothionein and renal tubular toxicity.

    PubMed

    Nordberg, M; Jin, T; Nordberg, G F

    1992-01-01

    Cadmium-induced nephrotoxicity develops at cadmium concentrations in the renal cortex of 10-300 micrograms/g wet weight. The actual concentration at which it develops depends on a number of factors, e.g., exposure route, chemical species of cadmium administered, rate of administration and simultaneous exposure to other metals. The role of these factors can be explained by a mechanism of cadmium nephrotoxicity in which both extracellular and intracellular metallothionein binding play an essential role. In reindeer used for human food, cadmium was shown to be bound to metallothionein-like proteins. If cadmium bound to such proteins enters the blood plasma via the gastrointestinal tract, this is of special toxicological significance. Metallothionein-bound cadmium in the plasma of experimental animals is efficiently transported to the kidney. Tubular dysfunction in the kidney following a normally tubulotoxic dose of cadmium bound to metallothionein was prevented by preinduction of metallothionein synthesis by small non-toxic doses of cadmium. PMID:1303954

  17. Ultrafine nanoporous palladium-aluminum film fabricated by citric acid-assisted hot-water-treatment of aluminum-palladium alloy film

    SciTech Connect

    Harumoto, Takashi; Tamura, Yohei; Ishiguro, Takashi

    2015-01-15

    Hot-water-treatment has been adapted to fabricate ultrafine nanoporous palladium-aluminum film from aluminum-palladium alloy film. Using citric acid as a chelating agent, a precipitation of boehmite (aluminum oxide hydroxide, AlOOH) on the nanoporous palladium-aluminum film was suppressed. According to cross-sectional scanning transmission electron microscopy observations, the ligament/pore sizes of the prepared nanoporous film were considerably small (on the order of 10 nm). Since this fabrication method only requires aluminum alloy film and hot-water with chelating agent, the ultrafine nanoporous film can be prepared simply and environmentally friendly.

  18. Cadmium telluride photovoltaic radiation detector

    DOEpatents

    Agouridis, D.C.; Fox, R.J.

    A dosimetry-type radiation detector is provided which employs a polycrystalline, chlorine-compensated cadmium telluride wafer fabricated to operate as a photovoltaic current generator used as the basic detecting element. A photovoltaic junction is formed in the wafer by painting one face of the cadmium telluride wafer with an n-type semi-conductive material. The opposite face of the wafer is painted with an electrically conductive material to serve as a current collector. The detector is mounted in a hermetically sealed vacuum containment. The detector is operated in a photovoltaic mode (zero bias) while DC coupled to a symmetrical differential current amplifier having a very low input impedance. The amplifier converts the current signal generated by radiation impinging upon the barrier surface face of the wafer to a voltage which is supplied to a voltmeter calibrated to read quantitatively the level of radiation incident upon the detecting wafer.

  19. Cadmium telluride photovoltaic radiation detector

    DOEpatents

    Agouridis, Dimitrios C.; Fox, Richard J.

    1981-01-01

    A dosimetry-type radiation detector is provided which employs a polycrystalline, chlorine-compensated cadmium telluride wafer fabricated to operate as a photovoltaic current generator used as the basic detecting element. A photovoltaic junction is formed in the wafer by painting one face of the cadmium telluride wafer with an n-type semiconductive material. The opposite face of the wafer is painted with an electrically conductive material to serve as a current collector. The detector is mounted in a hermetically sealed vacuum containment. The detector is operated in a photovoltaic mode (zero bias) while DC coupled to a symmetrical differential current amplifier having a very low input impedance. The amplifier converts the current signal generated by radiation impinging upon the barrier surface face of the wafer to a voltage which is supplied to a voltmeter calibrated to read quantitatively the level of radiation incident upon the detecting wafer.

  20. One-pot synthesis of gold-palladium@palladium core-shell nanoflowers as efficient electrocatalyst for ethanol electrooxidation

    NASA Astrophysics Data System (ADS)

    Qiu, Xiaoyu; Dai, Yuxuan; Tang, Yawen; Lu, Tianhong; Wei, Shaohua; Chen, Yu

    2015-03-01

    In this work, a simple polyallylamine-assisted water-based synthesis is successfully used to synthesize high-quality gold-palladium@palladium (Au-Pd@Pd) core-shell nanoflowers. Transmission electron microscopy, X-ray powder diffraction, element mapping, energy dispersive spectroscopy, and X-ray photoelectron spectroscopy techniques are used to characterize the morphology, structure and composition of Au-Pd@Pd core-shell nanoflowers. The as-prepared Au-Pd@Pd core-shell nanoflowers exhibit significantly enhanced electrocatalytic activity for the ethanol oxidation reaction (EOR) in basic medium compared with commercial Pd black. In addition, Au-Pd@Pd core-shell nanoflowers also show higher durability for the EOR than commercial Pd black.

  1. Synthesis and characterization of palladium and palladium-cobalt nanoparticles on Vulcan XC-72R for the oxygen reduction reaction.

    PubMed

    Arroyo-Ramírez, Lisandra; Montano-Serrano, Rubenier; Luna-Pineda, Tatiana; Román, Félix R; Raptis, Raphael G; Cabrera, Carlos R

    2013-11-27

    A single-source approach was used to synthesize bimetallic nanoparticles on a high-surface-area carbon-support surface. The synthesis of palladium and palladium-cobalt nanoparticles on carbon black (Vulcan XC-72R) by chemical and thermal reduction using organometallic complexes as precursors is described. The electrocatalysts studied were Pd/C, Pd2Co/C, and PdCo2/C. The nanoparticles composition and morphology were characterized using inductively coupled plasma mass spectrophotometer (ICP-MS), X-ray photoelectron spectroscopy (XPS), energy-dispersive X-ray fluorescence spectroscopy (EDS), X-ray diffraction (XRD), and transmission electron microscopy (TEM) techniques. Electrocatalytic activity towards the oxygen reduction reaction (ORR) and methanol tolerance in oxygen-saturated acid solution were determined. The bimetallic catalyst on carbon support synthetized by thermal reduction of the Pd2Co precursor has ORR electrocatalytic activity and a higher methanol tolerance than a Pt/C catalyst.

  2. Historical perspectives on cadmium toxicology

    SciTech Connect

    Nordberg, Gunnar F.

    2009-08-01

    The first health effects of cadmium (Cd) were reported already in 1858. Respiratory and gastrointestinal symptoms occurred among persons using Cd-containing polishing agent. The first experimental toxicological studies are from 1919. Bone effects and proteinuria in humans were reported in the 1940's. After World War II, a bone disease with fractures and severe pain, the itai-itai disease, a form of Cd-induced renal osteomalacia, was identified in Japan. Subsequently, the toxicokinetics and toxicodynamics of Cd were described including its binding to the protein metallothionein. International warnings of health risks from Cd-pollution were issued in the 1970's. Reproductive and carcinogenic effects were studied at an early stage, but a quantitative assessment of these effects in humans is still subject to considerable uncertainty. The World Health Organization in its International Program on Chemical Safety, WHO/IPCS (1992) (Cadmium. Environmental Health Criteria Document 134, IPCS. WHO, Geneva, 1-280.) identified renal dysfunction as the critical effect and a crude quantitative evaluation was presented. In the 1990's and 2000 several epidemiological studies have reported adverse health effects, sometimes at low environmental exposures to Cd, in population groups in Japan, China, Europe and USA (reviewed in other contributions to the present volume). The early identification of an important role of metallothionein in cadmium toxicology formed the basis for recent studies using biomarkers of susceptibility to development of Cd-related renal dysfunction such as gene expression of metallothionein in peripheral lymphocytes and autoantibodies against metallothionein in blood plasma. Findings in these studies indicate that very low exposure levels to cadmium may give rise to renal dysfunction among sensitive subgroups of human populations such as persons with diabetes.

  3. Beyond the use of modifiers in selective alkyne hydrogenation: silver and gold nanocatalysts in flow mode for sustainable alkene production.

    PubMed

    Vilé, Gianvito; Pérez-Ramírez, Javier

    2014-11-21

    We report on the excellent stereo and chemoselectivity of nanosized silver and gold catalysts in the three-phase hydrogenation of acetylenic compounds under flow chemistry conditions. The materials featuring metal nanoparticles in the range of 2-21 nm were prepared by spray deposition or incipient wetness impregnation of silver nitrate and sol immobilisation of gold chloride on different carriers (Al2O3, SiO2, TiO2, and carbon), followed by activation in various atmospheres. The samples were characterised by ICP-OES, N2 sorption, XPS, HAADF-STEM, and HRTEM, and evaluated in a continuous-flow flooded-bed micro-reactor. Both metals display optimal activities for particles below 5 nm, enabling stable operation at T = 373 K and P = 10 bar. While the performance of the silver catalysts is less influenced by the support, the gold nanoparticles exhibit significant activity only when deposited on TiO2, likely due to the strong metal-support interaction. Hydrogenations of functionalised alkynes reveal that silver and gold match, and in some cases exceed, the selectivity of benchmark palladium-based catalysts. Furthermore, in contrast to Pd, the Ag and Au samples require no modifiers, which brings fundamental and practical simplifications for their understanding and large scale manufacture. Therefore, these materials could be advantageously used for the continuous production of olefinic intermediates in the fine chemical and pharmaceutical industries. PMID:25132414

  4. Silver Complexes of Dihalogen Molecules.

    PubMed

    Malinowski, Przemysław J; Himmel, Daniel; Krossing, Ingo

    2016-08-01

    The perfluorohexane-soluble and donor-free silver compound Ag(A) (A=Al(OR(F) )4 ; R(F) =C(CF3 )3 ) prepared using a facile novel route has unprecedented capabilities to form unusual and weakly bound complexes. Here, we report on the three dihalogen-silver complexes Ag(Cl2 )A, Ag(Br2 )A, and Ag(I2 )A derived from the soluble silver compound Ag(A) (characterized by single-crystal/powder XRD, Raman spectra, and quantum-mechanical calculations). PMID:27404568

  5. MOD silver metallization for photovoltaics

    NASA Technical Reports Server (NTRS)

    Vest, G. M.; Vest, R. W.

    1985-01-01

    The feasibility of utilizing metallo-organic decomposition (MOD) silver inks were investigated for front contact metallization of solar cells. Generic synthesis procedures were developed for all metallo-organic compounds investigated. Silver neodecanoate was found to be the most suitable silver metallo-organic compound for use in thick film inks, but the quality of the inks was found to be highly dependent on its purity. Although neither the process nor inks were completely optimized for solar cell front contact metallization, they show great promise for this application.

  6. New Palladium-Catalyzed Approaches to Heterocycles and Carbocycles

    SciTech Connect

    Qinhua Huang

    2004-12-19

    The tert-butylimines of o-(1-alkynyl)benzaldehydes and analogous pyridinecarbaldehydes have been cyclized under very mild reaction conditions in the presence of I{sub 2}, ICl, PhSeCl, PhSCl and p-O{sub 2}NC{sub 6}H{sub 4}SCl to give the corresponding halogen-, selenium- and sulfur-containing disubstituted isoquinolines and naphthyridines, respectively. Monosubstituted isoquinolines and naphthyridines have been synthesized by the metal-catalyzed ring closure of these same iminoalkynes. This methodology accommodates a variety of iminoalkynes and affords the anticipated heterocycles in moderate to excellent yields. The Pd(II)-catalyzed cyclization of 2-(1-alkynyl)arylaldimines in the presence of various alkenes provides an efficient way to synthesize a variety of 4-(1-alkenyl)-3-arylisoquinolines in moderate to excellent yields. The introduction of an ortho-methoxy group on the arylaldimine promotes the Pd-catalyzed cyclization and stabilizes the resulting Pd(II) intermediate, improving the yields of the isoquinoline products. Highly substituted naphthalenes have been synthesized by the palladium-catalyzed annulation of a variety of internal alkynes, in which two new carbon-carbon bonds are formed in a single step under relatively mild reaction conditions. This method has also been used to synthesize carbazoles, although a higher reaction temperature is necessary. The process involves arylpalladation of the alkyne, followed by intramolecular Heck olefination and double bond isomerization. This method accommodates a variety of functional groups and affords the anticipated highly substituted naphthalenes and carbazoles in good to excellent yields. Novel palladium migratiodarylation methodology for the synthesis of complex fused polycycles has been developed, in which one or more sequential Pd-catalyzed intramolecular migration processes involving C-H activation are employed. The chemistry works best with electron-rich aromatics, which is in agreement with the idea that

  7. Surface oxygen triggered size change of palladium nano-crystals impedes catalytic efficacy.

    PubMed

    Zou, Jianli; Stewart, Scott G; Raston, Colin L; Iyer, K Swaminathan

    2011-02-14

    Palladium nano-crystals increase in size during the initial recycling in Heck cross coupling reactions. We demonstrate that oxygen adsorbed on the surface of palladium nano-crystals plays a pivotal role in driving the ripening. This in turn is associated with a loss in catalytic activity.

  8. Palladium-Catalyzed Heteroarylation and Concomitant ortho-Alkylation of Aryl Iodides.

    PubMed

    Lei, Chuanhu; Jin, Xiaojia; Zhou, Jianrong Steve

    2015-11-01

    Three-component couplings were achieved from common aryl halides, alkyl halides, and heteroarenes under palladium and norbornene co-catalysis. The reaction forges hindered aryl-heteroaryl bonds and introduces ortho-alkyl groups to aryl rings. Various heterocycles such as oxazoles, thiazoles and thiophenes underwent efficient coupling. The heteroarenes were deprotonated in situ by bases without the assistance of palladium catalysts.

  9. Nephropathy in cadmium workers: assessment of risk from airborne occupational exposure to cadmium.

    PubMed Central

    Thun, M J; Osorio, A M; Schober, S; Hannon, W H; Lewis, B; Halperin, W

    1989-01-01

    To assess the quantitative relation between exposure to airborne cadmium and various markers of renal tubular and glomerular function, 45 male workers employed at a plant that recovers cadmium from industrial waste and 32 male hospital workers of similar age and geographical location were examined. Cumulative external exposure to airborne cadmium (dose) was estimated from historical air sampling data, adjusted for respirator use. Increasing cadmium dose was associated with multiple renal tubular functional abnormalities, including reduced reabsorption of beta-2-microglobulin (beta-2), retinol binding protein (RBP), calcium, and phosphate. Serum creatinine concentration also increased with cadmium dose, suggesting impaired glomerular function. Mean systolic and diastolic blood pressures were higher in the cadmium workers than in the unexposed (134 v 120 mm Hg and 80 v 73 mm Hg respectively), but only systolic blood pressure was significantly associated with cadmium dose in multivariate analyses. Cadmium dose remained the most important predictor of serum creatinine concentration after controlling for age, blood pressure, body size, and other extraneous factors. Logistic regression to model the probability (prevalence) of various renal abnormalities with increasing dose of cadmium was used. The probability of multiple tubular abnormalities and raised serum creatinine concentration increased sharply at cumulative cadmium exposures exceeding 300 mg/m3 days, corresponding to working for 4.3 years at the current permissible United States exposure limit for cadmium dust. PMID:2818957

  10. Improvement of cadmium phytoremediation after soil inoculation with a cadmium-resistant Micrococcus sp.

    PubMed

    Sangthong, Chirawee; Setkit, Kunchaya; Prapagdee, Benjaphorn

    2016-01-01

    Cadmium-resistant Micrococcus sp. TISTR2221, a plant growth-promoting bacterium, has stimulatory effects on the root lengths of Zea mays L. seedlings under toxic cadmium conditions compared to uninoculated seedlings. The performance of Micrococcus sp. TISTR2221 on promoting growth and cadmium accumulation in Z. mays L. was investigated in a pot experiment. The results indicated that Micrococcus sp. TISTR2221significantly promoted the root length, shoot length, and dry biomass of Z. mays L. transplanted in both uncontaminated and cadmium-contaminated soils. Micrococcus sp. TISTR2221 significantly increased cadmium accumulation in the roots and shoots of Z. mays L. compared to uninoculated plants. At the beginning of the planting period, cadmium accumulated mainly in the shoots. With a prolonged duration of cultivation, cadmium content increased in the roots. As expected, little cadmium was found in maize grains. Soil cadmium was significantly reduced with time, and the highest percentage of cadmium removal was found in the bacterial-inoculated Z. mays L. after transplantation for 6 weeks. We conclude that Micrococcus sp. TISTR2221 is a potent bioaugmenting agent, facilitating cadmium phytoextraction in Z. mays L. PMID:26336850

  11. Hydrogen sulfide modulates cadmium-induced physiological and biochemical responses to alleviate cadmium toxicity in rice.

    PubMed

    Mostofa, Mohammad Golam; Rahman, Anisur; Ansary, Md Mesbah Uddin; Watanabe, Ayaka; Fujita, Masayuki; Tran, Lam-Son Phan

    2015-09-11

    We investigated the physiological and biochemical mechanisms by which H2S mitigates the cadmium stress in rice. Results revealed that cadmium exposure resulted in growth inhibition and biomass reduction, which is correlated with the increased uptake of cadmium and depletion of the photosynthetic pigments, leaf water contents, essential minerals, water-soluble proteins, and enzymatic and non-enzymatic antioxidants. Excessive cadmium also potentiated its toxicity by inducing oxidative stress, as evidenced by increased levels of superoxide, hydrogen peroxide, methylglyoxal and malondialdehyde. However, elevating endogenous H2S level improved physiological and biochemical attributes, which was clearly observed in the growth and phenotypes of H2S-treated rice plants under cadmium stress. H2S reduced cadmium-induced oxidative stress, particularly by enhancing redox status and the activities of reactive oxygen species and methylglyoxal detoxifying enzymes. Notably, H2S maintained cadmium and mineral homeostases in roots and leaves of cadmium-stressed plants. By contrast, adding H2S-scavenger hypotaurine abolished the beneficial effect of H2S, further strengthening the clear role of H2S in alleviating cadmium toxicity in rice. Collectively, our findings provide an insight into H2S-induced protective mechanisms of rice exposed to cadmium stress, thus proposing H2S as a potential candidate for managing toxicity of cadmium, and perhaps other heavy metals, in rice and other crops.

  12. Improvement of cadmium phytoremediation after soil inoculation with a cadmium-resistant Micrococcus sp.

    PubMed

    Sangthong, Chirawee; Setkit, Kunchaya; Prapagdee, Benjaphorn

    2016-01-01

    Cadmium-resistant Micrococcus sp. TISTR2221, a plant growth-promoting bacterium, has stimulatory effects on the root lengths of Zea mays L. seedlings under toxic cadmium conditions compared to uninoculated seedlings. The performance of Micrococcus sp. TISTR2221 on promoting growth and cadmium accumulation in Z. mays L. was investigated in a pot experiment. The results indicated that Micrococcus sp. TISTR2221significantly promoted the root length, shoot length, and dry biomass of Z. mays L. transplanted in both uncontaminated and cadmium-contaminated soils. Micrococcus sp. TISTR2221 significantly increased cadmium accumulation in the roots and shoots of Z. mays L. compared to uninoculated plants. At the beginning of the planting period, cadmium accumulated mainly in the shoots. With a prolonged duration of cultivation, cadmium content increased in the roots. As expected, little cadmium was found in maize grains. Soil cadmium was significantly reduced with time, and the highest percentage of cadmium removal was found in the bacterial-inoculated Z. mays L. after transplantation for 6 weeks. We conclude that Micrococcus sp. TISTR2221 is a potent bioaugmenting agent, facilitating cadmium phytoextraction in Z. mays L.

  13. Hydrogen sulfide modulates cadmium-induced physiological and biochemical responses to alleviate cadmium toxicity in rice

    PubMed Central

    Mostofa, Mohammad Golam; Rahman, Anisur; Ansary, Md. Mesbah Uddin; Watanabe, Ayaka; Fujita, Masayuki; Phan Tran, Lam-Son

    2015-01-01

    We investigated the physiological and biochemical mechanisms by which H2S mitigates the cadmium stress in rice. Results revealed that cadmium exposure resulted in growth inhibition and biomass reduction, which is correlated with the increased uptake of cadmium and depletion of the photosynthetic pigments, leaf water contents, essential minerals, water-soluble proteins, and enzymatic and non-enzymatic antioxidants. Excessive cadmium also potentiated its toxicity by inducing oxidative stress, as evidenced by increased levels of superoxide, hydrogen peroxide, methylglyoxal and malondialdehyde. However, elevating endogenous H2S level improved physiological and biochemical attributes, which was clearly observed in the growth and phenotypes of H2S-treated rice plants under cadmium stress. H2S reduced cadmium-induced oxidative stress, particularly by enhancing redox status and the activities of reactive oxygen species and methylglyoxal detoxifying enzymes. Notably, H2S maintained cadmium and mineral homeostases in roots and leaves of cadmium-stressed plants. By contrast, adding H2S-scavenger hypotaurine abolished the beneficial effect of H2S, further strengthening the clear role of H2S in alleviating cadmium toxicity in rice. Collectively, our findings provide an insight into H2S-induced protective mechanisms of rice exposed to cadmium stress, thus proposing H2S as a potential candidate for managing toxicity of cadmium, and perhaps other heavy metals, in rice and other crops. PMID:26361343

  14. A versatile silver oxide-zinc battery for synchronous orbit and planetary missions.

    NASA Technical Reports Server (NTRS)

    Schwartz, H. J.; Soltis, D. G.

    1972-01-01

    A new kind of silver-zinc cell has been developed and tested under NASA support which can withstand severe heat sterilization requirements. These cells could be used on planetary lander mission which require wet-stand periods of over a year, a modest number of cycles (400 to 500) and may require dry heat sterilization. The weight advantage of these cells over the traditional nickel-cadmium batteries also makes it an attractive alternative for synchronous orbit service where 400 to 500 cycles would be required over a 5 year period.

  15. A versatile silver oxide-zinc battery for synchronous orbit and planetary missions

    NASA Technical Reports Server (NTRS)

    Schwartz, H. J.; Soltis, D. G.

    1973-01-01

    A new kind of silver-zinc cell has been developed and tested under NASA support which can withstand severe heat sterilization requirements and does not display the traditional life limiting aspect of zinc electrodes - i.e., shape change. These cells could be used on a planetary lander mission which requires wet-stand periods of over a year, a modest number of cycles (400 to 500) and may require dry heat sterilization. The weight advantage of these cells over the traditional nickel-cadmium batteries makes them also an attractive alternative for synchronous orbit service where 400 to 500 cycles would be required over a five-year period.

  16. A versatile silver oxide-zinc battery for synchronous orbit and planetary missions

    NASA Technical Reports Server (NTRS)

    Schwartz, H. J.; Soltis, D. G.

    1972-01-01

    A new kind of silver-zinc cell was developed and tested under NASA support which can withstand severe heat sterilization requirements and does not display the traditional life limiting aspect of sinc electrodes i.e. shape change. These cells could be used on planetary lander mission which require wet-stand periods of over a year, a modest number of cycles (400 to 500) and may require dry heat sterilization. The weight advantage of these cells over the traditional nickel cadmium batteries also makes it an attractive alternative for synchronous orbit service where 400 to 500 cycles would be required over a 5 year period.

  17. Antimicrobial effects of silver zeolite, silver zirconium phosphate silicate and silver zirconium phosphate against oral microorganisms

    PubMed Central

    Saengmee-anupharb, Sirikamon; Srikhirin, Toemsak; Thaweboon, Boonyanit; Thaweboon, Sroisiri; Amornsakchai, Taweechai; Dechkunakorn, Surachai; Suddhasthira, Theeralaksna; Kamaguchi, Arihide

    2013-01-01

    Objective To evaluate the antimicrobial activities of silver inorganic materials, including silver zeolite (AgZ), silver zirconium phosphate silicate (AgZrPSi) and silver zirconium phosphate (AgZrP), against oral microorganisms. In line with this objective, the morphology and structure of each type of silver based powders were also investigated. Methods The antimicrobial activities of AgZ, AgZrPSi and AgZrP were tested against Streptococcus mutans, Lactobacillus casei, Candida albicans and Staphylococcus aureus using disk diffusion assay as a screening test. The minimum inhibitory concentration (MIC) and minimum lethal concentration (MLC) were determined using the modified membrane method. Scanning electron microscope and X-ray diffraction were used to investigate the morphology and structure of these silver materials. Results All forms of silver inorganic materials could inhibit the growth of all test microorganisms. The MIC of AgZ, AgZrPSi and AgZrP was 10.0 g/L whereas MLC ranged between 10.0–60.0 g/L. In terms of morphology and structure, AgZrPSi and AgZrP had smaller sized particles (1.5–3.0 µm) and more uniformly shaped than AgZ. Conclusions Silver inorganic materials in the form of AgZ, AgZrPSi and AgZrP had antimicrobial effects against all test oral microorganisms and those activities may be influenced by the crystal structure of carriers. These results suggest that these silver materials may be useful metals applied to oral hygiene products to provide antimicrobial activity against oral infection. PMID:23570016

  18. Palladium-Mediated Surface-Initiated Kumada Catalyst Polycondensation: A Facile Route Towards Oriented Conjugated Polymers.

    PubMed

    Huddleston, N Eric; Sontag, S Kyle; Bilbrey, Jenna A; Sheppard, Gareth R; Locklin, Jason

    2012-12-21

    Palladium-mediated surface-initiated Kumada catalyst transfer polycondensation is used to generate poly(3-methyl thiophene) films with controlled thickness up to 100 nm. The palladium initiator density is measured using cyclic voltammetry and a ferrocene-capping agent, where the surface density is found to be 55% (1.1 × 10(14) molecules per cm(2)). UV-Vis spectroscopy and AFM show increased aggregation in palladium-initiated films due to the higher grafting density of palladium initiators on the surface. The anisotropy of the P3MT films is determined using polarized UV-Vis spectroscopy, which indicates a degree of orientation perpendicular to the substrate. Evidence that palladium can maintain π-complexation even at elevated temperatures, is also shown through the exclusive intramolecular coupling of both a phenyl and thiophene-based magnesium bromide with different dihaloarenes.

  19. Interstitial modification of palladium nanoparticles with boron atoms as a green catalyst for selective hydrogenation.

    PubMed

    Chan, Chun Wong Aaron; Mahadi, Abdul Hanif; Li, Molly Meng-Jung; Corbos, Elena Cristina; Tang, Chiu; Jones, Glenn; Kuo, Winson Chun Hsin; Cookson, James; Brown, Christopher Michael; Bishop, Peter Trenton; Tsang, Shik Chi Edman

    2014-01-01

    Lindlar catalysts comprising of palladium/calcium carbonate modified with lead acetate and quinoline are widely employed industrially for the partial hydrogenation of alkynes. However, their use is restricted, particularly for food, cosmetic and drug manufacture, due to the extremely toxic nature of lead, and the risk of its leaching from catalyst surface. In addition, the catalysts also exhibit poor selectivities in a number of cases. Here we report that a non-surface modification of palladium gives rise to the formation of an ultra-selective nanocatalyst. Boron atoms are found to take residence in palladium interstitial lattice sites with good chemical and thermal stability. This is favoured due to a strong host-guest electronic interaction when supported palladium nanoparticles are treated with a borane tetrahydrofuran solution. The adsorptive properties of palladium are modified by the subsurface boron atoms and display ultra-selectivity in a number of challenging alkyne hydrogenation reactions, which outclass the performance of Lindlar catalysts. PMID:25523894

  20. Palladium-catalyzed combustion of methane: Simulated gas turbine combustion at atmospheric pressure

    SciTech Connect

    Griffin, T.; Weisenstein, W.; Scherer, V.; Fowles, M.

    1995-04-01

    Atmospheric pressure tests were performed in which a palladium catalyst ignites and stabilizes the homogeneous combustion of methane. Palladium exhibited a reversible deactivation at temperatures above 750 C, which acted to ``self-regulate`` its operating temperature. A properly treated palladium catalyst could be employed to preheat a methane/air mixture to temperatures required for ignition of gaseous combustion (ca. 800 C) without itself being exposed to the mixture adiabatic flame temperature. The operating temperature of the palladium was found to be relatively insensitive to the methane fuel concentration or catalyst inlet temperature over a wide range of conditions. Thus, palladium is well suited for application in the ignition and stabilization of methane combustion.

  1. Interstitial modification of palladium nanoparticles with boron atoms as a green catalyst for selective hydrogenation

    NASA Astrophysics Data System (ADS)

    Chan, Chun Wong Aaron; Mahadi, Abdul Hanif; Li, Molly Meng-Jung; Corbos, Elena Cristina; Tang, Chiu; Jones, Glenn; Kuo, Winson Chun Hsin; Cookson, James; Brown, Christopher Michael; Bishop, Peter Trenton; Tsang, Shik Chi Edman

    2014-12-01

    Lindlar catalysts comprising of palladium/calcium carbonate modified with lead acetate and quinoline are widely employed industrially for the partial hydrogenation of alkynes. However, their use is restricted, particularly for food, cosmetic and drug manufacture, due to the extremely toxic nature of lead, and the risk of its leaching from catalyst surface. In addition, the catalysts also exhibit poor selectivities in a number of cases. Here we report that a non-surface modification of palladium gives rise to the formation of an ultra-selective nanocatalyst. Boron atoms are found to take residence in palladium interstitial lattice sites with good chemical and thermal stability. This is favoured due to a strong host-guest electronic interaction when supported palladium nanoparticles are treated with a borane tetrahydrofuran solution. The adsorptive properties of palladium are modified by the subsurface boron atoms and display ultra-selectivity in a number of challenging alkyne hydrogenation reactions, which outclass the performance of Lindlar catalysts.

  2. Brazing of Stainless Steels to Yttria Stabilized Zirconia (YSZ) Using Silver -Base Brazes

    NASA Technical Reports Server (NTRS)

    Singh, Mrityunjay; Shpargel, Tarah P.; Asthana, Rajiv

    2005-01-01

    Three silver-base brazes containing either noble metal palladium (Palcusil-10 and Palcusil-15) or active metal titanium (Ticusil) were evaluated for high-temperature oxidation resistance, and their effectiveness in joining yttria stabilized zirconia (YSZ) to a corrosion-resistant ferritic stainless steel. Thermogravimetric analysis (TGA), and optical- and scanning electron microscopy (SEM) coupled with energy dispersive spectrometry (EDS) were used to evaluate the braze oxidation behavior and the structure and chemistry of the YSZ/braze/steel joints. The effect of the braze type and processing conditions on the interfacial microstructure and composition of the joint regions is discussed with reference to the chemical changes that occur at the interface. It was found that chemical interdiffusion of the constituents of YSZ, steel and the brazes led to compositional changes and/or interface reconstruction, and metallurgically sound joints.

  3. Mercaptobenzoic acid-palladium(0) complexes as active catalysts for S-benzylation with benzylic alcohols via (η(3)-benzyl)palladium(II) cations in water.

    PubMed

    Hikawa, Hidemasa; Azumaya, Isao

    2014-08-21

    Mercaptobenzoic acid-palladium(0) complexes show high catalytic activity for S-benzylation with benzylic alcohols via the (η(3)-benzyl)palladium(II) cation in water. Notably, these palladium(0) complexes could play an important role in formation of active (η(3)-benzyl)palladium(II) cation complexes followed by S-benzylation. Hammett studies on the rate constants of S-benzylation by various substituted alcohols show good correlation between log(kX/kH) and the σ(+) value of the respective substituents. From the slope, negative ρ values are obtained, suggesting that there is a build-up of positive charge in the transition state. Water plays an important role in the catalytic system for sp(3) C-O bond activation and stabilization of the activated Pd(II) cation species. The catalytic system can be performed using only 2.5 mol% Pd2(dba)3 without the phosphine ligand or other additives.

  4. Silver Nafion for Thermogalvanic Applications

    NASA Astrophysics Data System (ADS)

    Chang, William; Popere, Bhooshan; Evans, Chris; Russ, Boris; Segalman, Rachel

    2015-03-01

    Thermogalvanics convert a temperature gradient, typically from waste heat, into electrical power using a reversible electrochemical reaction. The conversion efficiency in thermogalvanics, like with thermoelectrics, are governed by the Seebeck coefficient, the carrier conductivity and the thermal conductivity of the material. We demonstrate that the material systems silver Nafion and silver poly-styrenesulfonate are air-stable, water processable materials that demonstrate extremely high Seebeck coefficients and moderate carrier conductivities. These power factors, when coupled with the low thermal conductivities inherent in polymers, results in materials with excellent thermogalvanic figure of merits. We show the dependence of these three material properties to material composition and processing. In this talk, we show how the Seebeck coefficient in silver Nafion and silver polystyrene-sulfonate are opposite in sign, allowing construction of a thermogalvanic device. With these ion conductors, we hope to open up a flexible pathway to waste heat recovery using materials typically studied for electrochemical applications.

  5. Highly selective and sensitive fluorescence chemosensor for the detection of palladium species based on Tsuji-Trost reaction.

    PubMed

    Xu, Zhong-Yong; Li, Jing; Guan, Su; Zhang, Lei; Dong, Chang-Zhi

    2015-09-01

    A new chemosensor 7-nitro-2,1,3-benzoxadiazole-4-allyl-N-(thiophen-2-ylmethyl)carbamate (NBDTC) was synthesized and utilized for palladium detection based on the Tsuji-Trost reaction. NBDTC displayed specific and ratiometric fluorescent responses toward palladium species. The chemosensor showed more than 50-fold enhancement in fluorescence intensity with the presence of PEG400 and palladium because NBDTC can be transformed to NBDT under palladium-catalyzing Tsuji-Trost reaction. NBDTC displayed high selectivity and sensitivity for palladium species with the detection limit of 1.13×10(-9) M.

  6. Gold/Palladium Alloy for Carbon-Halogen Bond Activation: An Unprecedented Halide Dependence.

    PubMed

    Dhital, Raghu Nath; Bobuatong, Karan; Ehara, Masahiro; Sakurai, Hidehiro

    2015-12-01

    New catalytic activity of gold/palladium alloy nanoclusters (NCs) for carbon-halogen bond activation is demonstrated. In the case of an aryl chloride, the inclusion of gold in a bimetallic catalyst is indispensable to achieve the coupling reactions. Gold has the unique effect of stabilizing palladium, such that Pd(2+) leached from clusters by means of spillover of chloride during oxidative addition. The thus-formed spillover intermediate further reacts heterogeneously in both Ullmann and Suzuki-type coupling reactions through a new type of mechanism. In the case of an aryl bromide, Ullmann coupling occurs through the spillover of bromide, similar to that of aryl chloride. However, a significant fraction of palladium also leached, which diminished the Ullmann coupling activity of the aryl bromide and, as a result, the order of reactivity was ArCl>ArBr. With regard to the activation of the C-Br bond towards a Suzuki-type reaction, the inclusion of a higher gold content in gold/palladium clusters stabilized palladium to prevent the leaching of Pd(2+) from the clusters by means of spillover of bromide. The spillover intermediate reacts heterogeneously with PhB(OH)2, palladium-rich gold/palladium, or pure palladium clusters; the oxidative addition of ArBr favors the extraction of palladium from the clusters, yielding Pd(2+) intermediates. The extracted intermediates react homogenously (Pd(2+/)Pd(0) catalysis) with PhB(OH)2, which results in the higher selectivity of the cross-coupling product. An initial step to observe such unprecedented halide dependency, together with the dynamic behavior of palladium on the surface of gold is the oxidative addition of Ar-X. A detailed insight into the first oxidative addition process was also examined by quantum chemical calculations.

  7. Electroneutral intrinsic point defects in cadmium chalcogenides

    SciTech Connect

    Kharif, Ya.L.; Kudryashov, N.I.; Strunilina, T.A.

    1987-12-01

    Low-mobility electrically neutral intrinsic point defects were observed in cadmium chalcogenides. It was shown that the concentration of these defects is proportional to the cadmium vapor pressure to the 1/3 power at a constant temperature, and a mechanism for the formation of these defects were proposed.

  8. 29 CFR 1928.1027 - Cadmium.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 29 Labor 9 2011-07-01 2011-07-01 false Cadmium. 1928.1027 Section 1928.1027 Labor Regulations Relating to Labor (Continued) OCCUPATIONAL SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR (CONTINUED) OCCUPATIONAL SAFETY AND HEALTH STANDARDS FOR AGRICULTURE Occupational Health § 1928.1027 Cadmium. See §...

  9. 29 CFR 1928.1027 - Cadmium.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 29 Labor 9 2013-07-01 2013-07-01 false Cadmium. 1928.1027 Section 1928.1027 Labor Regulations Relating to Labor (Continued) OCCUPATIONAL SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR (CONTINUED) OCCUPATIONAL SAFETY AND HEALTH STANDARDS FOR AGRICULTURE Occupational Health § 1928.1027 Cadmium. See §...

  10. Effects of dietary cadmium on Mallard ducklings

    SciTech Connect

    Cain, B.W.; Sileo, L.; Franson, J.C.; Moore, J.

    1983-12-01

    Mallard (Anan platyrhynchos) ducklings were fed cadmium in the diet at 0, 5, 10, or 20 ppm from 1 day of age until 12 weeks of age. At 4-week intervals six males and six females from each dietary group were randomly selected, bled by jugular venipuncture, and necropsied. Significant decreases in packed cell volume (PCV) and hemoglobin (Hb) concentration and a significant increase in serum glutamic pyruvic transaminase (GPT) were found at 8 weeks of age in ducklings fed 20 ppm cadmium for 12 weeks. No other blood chemistry measurement, hematological parameter, or tissue histopathological measurement indicated a reaction to cadmium ingestion. Body weight, liver weight, and the ratio of the femur weight to length were not affected by dietary cadmium. Femur cadmium concentration in all ducklings 12 weeks of age declined from the values detected at 4 and 8 weeks of age. Liver cadmium concentrations were significantly higher in relation to the increased dietary levels and in relation to the length of time the ducklings were fed the cadmium diets. At 12 weeks of age the cadmium concentration in liver tissue was twice that in the diet. 38 references.

  11. Cadmium concentrations in tobacco and tobacco smoke

    SciTech Connect

    Scherer, G.; Barkemeyer, H.

    1983-02-01

    The amount of cadmium in tobacco depends on the variety and origin of the plant as well as on the analytical method used to determine cadmium. In the literature, cadmium concentrations in tobacco of between 0.5 and 5 ppm are reported. Modern German cigarette tobacco contains about 0.5-1.5 micrograms cadmium/cigarette. Of importance for the smoker is the amount of the metal in the mainstream smoke. The cadmium level in the mainstream smoke of modern cigarettes is reduced by means of filters and other construction features. The average Cd value of German filter cigarettes is less than 0.1 microgram/cigarette in mainstream smoke. An average daily intake of about 1 microgram cadmium by smoking 20 cigarettes can be calculated on the basis of an experimentally proved pulmonary retention rate of 50%. Pulmonary resorption rates relevant to uptake rates of cadmium by smoking are discussed. It can be assumed that cadmium uptake by smoking modern cigarettes has been reduced because of modifications in tobacco processing and cigarette construction in the last few decades.

  12. Association of urinary cadmium and myocardial infarction

    SciTech Connect

    Everett, Charles J. Frithsen, Ivar L.

    2008-02-15

    We conducted a cross-sectional analysis of individuals 45-79 years old in the National Health and Nutrition Examination Survey III (1988-1994) (NHANES III). Myocardial infarction was determined by electrocardiogram (ECG). Our sample included 4912 participants, which when weighted represented 52,234,055 Americans. We performed adjusted logistic regressions with the Framingham risk score, pack-years of smoking, race-ethnicity, and family history of heart attack, and diabetes as covariates. Urinary cadmium {>=}0.88 {mu}g/g creatinine had an odds ratio of 1.86 (95% CI 1.26-2.75) compared to urinary cadmium <0.43 {mu}g/g creatinine. This result supports the hypothesis that cadmium is associated with coronary heart disease. When logistic regressions were done by gender, women, but not men, showed a significant association of urinary cadmium with myocardial infarction. Women with urinary cadmium {>=}0.88 {mu}g/g creatinine had an odds ratio of 1.80 (95% CI 1.06-3.04) compared to urinary cadmium <0.43 {mu}g/g creatinine. When the analysis was restricted to never smokers (N=2187) urinary cadmium {>=}0.88 {mu}g/g creatinine had an odds ratio of 1.85 (95% CI 1.10-3.14) compared to urinary cadmium <0.43 {mu}g/g creatinine.

  13. 29 CFR 1915.1027 - Cadmium.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 29 Labor 7 2012-07-01 2012-07-01 false Cadmium. 1915.1027 Section 1915.1027 Labor Regulations Relating to Labor (Continued) OCCUPATIONAL SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR (CONTINUED... Cadmium. Note: The requirements applicable to shipyard employment under this section are identical...

  14. 29 CFR 1915.1027 - Cadmium.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 29 Labor 7 2011-07-01 2011-07-01 false Cadmium. 1915.1027 Section 1915.1027 Labor Regulations Relating to Labor (Continued) OCCUPATIONAL SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR (CONTINUED... Cadmium. Note: The requirements applicable to shipyard employment under this section are identical...

  15. 29 CFR 1915.1027 - Cadmium.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 29 Labor 7 2013-07-01 2013-07-01 false Cadmium. 1915.1027 Section 1915.1027 Labor Regulations Relating to Labor (Continued) OCCUPATIONAL SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR (CONTINUED... Cadmium. Note: The requirements applicable to shipyard employment under this section are identical...

  16. 29 CFR 1915.1027 - Cadmium.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 29 Labor 7 2010-07-01 2010-07-01 false Cadmium. 1915.1027 Section 1915.1027 Labor Regulations Relating to Labor (Continued) OCCUPATIONAL SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR (CONTINUED... Cadmium. Note: The requirements applicable to shipyard employment under this section are identical...

  17. 29 CFR 1915.1027 - Cadmium.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 29 Labor 7 2014-07-01 2014-07-01 false Cadmium. 1915.1027 Section 1915.1027 Labor Regulations Relating to Labor (Continued) OCCUPATIONAL SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR (CONTINUED... Cadmium. Note: The requirements applicable to shipyard employment under this section are identical...

  18. Synthesis and study on the luminescence properties of cadmium borate phosphors

    SciTech Connect

    Annalakshmi, O.; Jose, M.T.; Venkatraman, B.; Amarendra, G.

    2014-02-01

    Highlights: • Cadmium borate synthesized by solid state sintering technique. • Neutron sensitivity of the material ten times that of TLD-600. • Gamma sensitivity is found to be twice that of TLD-100. • Gamma response is linear from 0.1 to 10{sup 3} mGy. - Abstract: Cadmium borate compound prepared through wet chemical reaction from the starting chemicals followed by high temperature solid state synthesis below the melting point to get the final TL phosphor powder. Phase purity and bond details of cadmium borate crystals are characterized using X-ray diffraction technique and infrared spectroscopy. Feasibility of these materials for radiation dosimetry applications was studied after gamma and neutron irradiation. Gamma irradiation of undoped phosphors show a single peak around 185 °C whereas doping with gadolinium and silver, new more intense peak observed at 290 °C. Irradiation to thermal neutrons revealed single peak around 170 °C for all the phosphors. TL emission spectra and photoluminescence (PL) studies were also carried out on the phosphors. These borate materials are found to be highly sensitive to neutrons and hence can be used for neutron detection. Neutron sensitivity of the material is about ten times that of TLD-600.

  19. Cadmium stannate selective optical films for solar energy applications

    NASA Technical Reports Server (NTRS)

    Haacke, G.

    1975-01-01

    Efforts concentrated on reducing the electrical sheet resistance of sputtered cadmium stannate films, installing and testing equipment for spray coating experiments, and sputter deposition of thin cadmium sulfide layers onto cadmium stannate electrodes. In addition, single crystal silicon wafers were coated with cadmium stannate. Work also continued on the development of the backwall CdS solar cell.

  20. Preliminary flight prototype silver ion monitoring system

    NASA Technical Reports Server (NTRS)

    Brady, J.

    1974-01-01

    The design, fabrication, and testing of a preliminary flight prototype silver ion monitoring system based on potentiometric principles and utilizing a solid-state silver sulfide electrode paired with a pressurized double-junction reference electrode housing a replaceable electrolyte reservoir is described. The design provides automatic electronic calibration utilizing saturated silver bromide solution as a silver ion standard. The problem of loss of silver ion from recirculating fluid, its cause, and corrective procedures are reported. The instability of the silver sulfide electrode is discussed as well as difficulties met in implementing the autocalibration procedure.

  1. Silver composite cathodes for alkaline secondary batteries

    NASA Astrophysics Data System (ADS)

    Ferrando, William A.

    1989-08-01

    This invention relates to electrochemical cells and more particularly to silver electrodes for electrochemical cells. Accordingly, an object of this invention is to provide a new, lighter weight silver electrode for secondary cells. Another object of this invention is to provide an electrode which requires less silver to operate. A further object of this invention is to provide a silver electrode which uses the silver more efficiently. Yet another object of the invention is to provide an easier, less expensive method of manufacturing silver electrodes for secondary cells.

  2. Luminescent Cyclometalated Platinum and Palladium Complexes with Novel Photophysical Properties

    NASA Astrophysics Data System (ADS)

    Turner, Eric

    Organic light emitting diodes (OLEDs) is a rapidly emerging technology based on organic thin film semiconductors. Recently, there has been substantial investment in their use in displays. In less than a decade, OLEDs have grown from a promising academic curiosity into a multi-billion dollar global industry. At the heart of an OLED are emissive molecules that generate light in response to electrical stimulation. Ideal emitters are efficient, compatible with existing materials, long lived, and produce light predominantly at useful wavelengths. Developing an understanding of the photophysical processes that dictate the luminescent properties of emissive materials is vital to their continued development. Chapter 1 and Chapter 2 provide an introduction to the topics presented and the laboratory methods used to explore them. Chapter 3 discusses a series of tridentate platinum complexes. A synthetic method utilizing microwave irradiation was explored, as well as a study of the effects ligand structure had on the excited state properties. Results and techniques developed in this endeavor were used as a foundation for the work undertaken in later chapters. Chapter 4 introduces a series of tetradentate platinum complexes that share a phenoxy-pyridyl (popy) motif. The new molecular design improved efficiency through increased rigidity and modification of the excited state properties. This class of platinum complexes were markedly more efficient than those presented in Chapter 3, and devices employing a green emitting complex of the series achieved nearly 100% electron-to-photon conversion efficiency in an OLED device. Chapter 5 adapts the ligand structure developed in Chapter 4 to palladium. The resulting complexes exceed reported efficiencies of palladium complexes by an order of magnitude. This chapter also provides the first report of a palladium complex as an emitter in an OLED device. Chapter 6 discusses the continuation of development efforts to include carbazolyl

  3. Detecting Airborne Mercury by Use of Palladium Chloride

    NASA Technical Reports Server (NTRS)

    Ryan, Margaret; Shevade, Abhijit; Kisor, Adam; Homer, Margie; Jewell, April; Manatt, Kenneth; Torres, Julia; Soler, Jessica; Taylor, Charles

    2009-01-01

    Palladium chloride films have been found to be useful as alternatives to the gold films heretofore used to detect airborne elemental mercury at concentrations of the order of parts per billion (ppb). Somewhat more specifically, when suitably prepared palladium chloride films are exposed to parts-per-billion or larger concentrations of airborne mercury, their electrical resistances change by amounts large enough to be easily measurable. Because airborne mercury adversely affects health, it is desirable to be able to detect it with high sensitivity, especially in enclosed environments in which there is a risk of leakage of mercury from lamps or other equipment. The detection of mercury by use of gold films involves the formation of gold/mercury amalgam. Gold films offer adequate sensitivity for detection of airborne mercury and could easily be integrated into an electronic-nose system designed to operate in the temperature range of 23 to 28 C. Unfortunately, in order to regenerate a gold-film mercury sensor, one must heat it to a temperature of 200 C for several minutes in clean flowing air. In preparation for an experiment to demonstrate the present sensor concept, palladium chloride was deposited from an aqueous solution onto sets of gold electrodes and sintered in air to form a film. Then while using the gold electrodes to measure the electrical resistance of the films, the films were exposed, at a temperature of 25 C, to humidified air containing mercury at various concentrations from 0 to 35 ppb (see figure). The results of this and other experiments have been interpreted as signifying that sensors of this type can detect mercury in room-temperature air at concentrations of at least 2.5 ppb and can readily be regenerated at temperatures <40 C.

  4. Theoretical investigations of silver clusters and silver-ligand systems.

    SciTech Connect

    Jellinek, J.; Salian, U.; Srinivas, S.

    1999-05-19

    Studies directed at understanding structural and electronic properties of silver clusters have been and remain the subject of an active theoretical [1-22] and experimental [23- 38] effort. One of the reasons is the (still) important role these systems play in the photographic process. Investigations of interactions of silver clusters with different atoms and molecules are motivated primarily by a possible utility of these clusters in catalytic processes. The important role of silver in the selective oxidation of ethylene into ethylene oxide, the feedstock for polyester production, is well-known [39]. Possible variations in chemical reactivity with the cluster size and understanding of the mechanisms of interactions with different ligands may lead to new and more efficient applications. Investigations of cluster-ligand systems also contribute a great deal to a better understanding of gas-surface interactions. Accordingly, theoretical studies of silver clusters and cluster-ligand systems [40-44] fall into two categories--those that use clusters as models for silver surfaces [40], and those that target clusters and cluster-ligand interactions as subjects in their own right [41-44]. The common goal of all these studies is to elucidate the nature of the interatomic interactions and bonding at the microscopic level and thereby arrive at a fundamental understanding and description of the various structural and electronic properties.

  5. Palladium nanoparticles on InP for hydrogen detection

    PubMed Central

    2011-01-01

    Layers of palladium (Pd) nanoparticles on indium phosphide (InP) were prepared by electrophoretic deposition from the colloid solution of Pd nanoparticles. Layers prepared by an opposite polarity of deposition showed different physical and morphological properties. Particles in solution are separated and, after deposition onto the InP surface, they form small aggregates. The size of the aggregates is dependent on the time of deposition. If the aggregates are small, the layer has no lateral conductance. Forward and reverse I-V characteristics showed a high rectification ratio with a high Schottky barrier height. The response of the structure on the presence of hydrogen was monitored. PMID:21711487

  6. Synthesis of Dihydrobenzofurans via Palladium-Catalyzed Heteroannulations

    SciTech Connect

    Roman Vladimirovich Rozhkov

    2004-12-19

    Palladium-catalyzed heteroannulation of 1,3-dienes with 3-iodo-2-alkenols, and 2-iodo-2-alkenols, as well as their amino analogs, affords the corresponding cyclic ethers and amines respectively. The presence of a {beta}-hydrogen in the vinylic halide results in {beta}-hydride elimination giving the corresponding alkyne. The presence of a bulky group in the {alpha}-position of the vinylic halide results in failure or reduced amounts of annulation products. A chloride source, pyridine base and electron-rich phosphine are essential for this reaction.

  7. Bulk synthesis of nanoporous palladium and platinum powders

    DOEpatents

    Robinson, David B.; Fares, Stephen J.; Tran, Kim L.; Langham, Mary E.

    2012-04-17

    Disclosed is a method for providing nanoporous palladium and platinum powders. These materials were synthesized on milligram to gram scales by chemical reduction of tetrahalo-complexes with ascorbate in a concentrated aqueous surfactant at temperatures between -20.degree. C. and 30.degree. C. The prepared particles have diameters of approximately 50 nm, wherein each particle is perforated by pores having diameters of approximately 3 nm, as determined by electron tomography. These materials are of potential value for hydrogen and electrical charge storage applications.

  8. Bulk synthesis of nanoporous palladium and platinum powders

    DOEpatents

    Robinson, David B; Fares, Stephen J; Tran, Kim L; Langham, Mary E

    2014-04-15

    Disclosed is a method for providing nanoporous palladium and platinum powders. These materials were synthesized on milligram to gram scales by chemical reduction of tetrahalo-complexes with ascorbate in a concentrated aqueous surfactant at temperatures between -20.degree. C. and 30.degree. C. The prepared particles have diameters of approximately 50 nm, wherein each particle is perforated by pores having diameters of approximately 3 nm, as determined by electron tomography. These materials are of potential value for hydrogen and electrical charge storage applications.

  9. The Palladium-Catalyzed Trifluoromethylation of Vinyl Sulfonates

    PubMed Central

    Cho, Eun Jin; Buchwald, Stephen L.

    2011-01-01

    A method for the palladium-catalyzed trifluoromethylation of cyclohexenyl sulfonates has been developed. Various cyclohexenyl triflates and nonaflates underwent trifluoromethylation under mild reaction conditions using a catalyst system composed of Pd(dba)2 or [(allyl)PdCl]2 and the monodentate biaryl phosphine ligand tBuXPhos. The trifluoromethyl anion (CF3−) or its equivalent for the process was generated in situ from TMSCF3 in combination with KF or TESCF3 in combintion with RbF. PMID:22111687

  10. Ozone sensing based on palladium decorated carbon nanotubes.

    PubMed

    Colindres, Selene Capula; Aguir, Khalifa; Cervantes Sodi, Felipe; Vargas, Luis Villa; Salazar, José Moncayo; Febles, Vicente Garibay

    2014-04-14

    Multiwall carbon nanotubes (MWCNTs) were easily and efficiently decorated with Pd nanoparticles through a vapor-phase impregnation-decomposition method starting from palladium acetylacetonates. The sensor device consisted on a film of sensitive material (MWCNTs-Pd) deposited by drop coating on platinum interdigitated electrodes on a SiO₂ substrate. The sensor exhibited a resistance change to ozone (O₃) with a response time of 60 s at different temperatures and the capability of detecting concentrations up to 20 ppb. The sensor shows the best response when exposed to O3 at 120 °C. The device shows a very reproducible sensor performance, with high repeatability, full recovery and efficient response.

  11. Altered avoidance behavior of young black ducks fed cadmium

    USGS Publications Warehouse

    Heinz, G.H.; Haseltine, S.D.; Sileo, L.

    1983-01-01

    Pairs of adult black ducks (Anas rubripes) were fed a diet containing 0, 4 or 40 ppm cadmium as cadmium chloride. One-week-old ducklings that had been fed thc same dietary concentrations of cadmium as had their parents were tested for avoidance of a fright stimulus. Ducklings fed 4 ppm cadmium ran significantly farther from the stimulus than did controls or ducklings fed 40 ppm cadmium. Such an alteration in behavior could have harmful effects on wild birds.

  12. Direct and quinone-mediated palladium reduction by Geobacter sulfurreducens: mechanisms and modeling.

    PubMed

    Pat-Espadas, Aurora M; Razo-Flores, Elías; Rangel-Mendez, J Rene; Cervantes, Francisco J

    2014-01-01

    Palladium(II) reduction to Pd(0) nanoparticles by Geobacter sulfurreducens was explored under conditions of neutral pH, 30 °C and concentrations of 25, 50, and 100 mg of Pd(II)/L aiming to investigate the effect of solid species of palladium on their microbial reduction. The influence of anthraquinone-2,6-disulfonate was reported to enhance the palladium reaction rate in an average of 1.7-fold and its addition is determining to achieve the reduction of solid species of palladium. Based on the obtained results two mechanisms are proposed: (1) direct, which is fully described considering interactions of amide, sulfur, and phosphoryl groups associated to proteins from bacteria on palladium reduction reaction, and (2) quinone-mediated, which implies multiheme c-type cytochromes participation. Speciation analysis and kinetic results were considered and integrated into a model to fit the experimental data that explain both mechanisms. This work provides elements for a better understanding of direct and quinone-mediated palladium reduction by G. sulfurreducens, which could facilitate metal recovery with concomitant formation of valuable palladium nanoparticles in industrial processes.

  13. Interaction of cadmium with phosphate on goethite

    SciTech Connect

    Venema, P.; Hiemstra, T.; Riemsdijk, W.H. van

    1997-08-01

    Interactions between different ions are of importance in understanding chemical processes in natural systems. In this study simultaneous adsorption of phosphate and cadmium on goethite is studied in detail. The charge distribution (CD)-multisite complexation (MUSIC) model has been successful in describing extended data sets of cadmium adsorption and phosphate adsorption on goethite. In this study, the parameters of this model for these two data sets were combined to describe a new data set of simultaneous adsorption of cadmium and phosphate on goethite. Attention is focused on the surface speciation of cadmium. With the extra information that can be obtained from the interaction experiments, the cadmium adsorption model is refined. For a perfect description of the data, the singly coordinated surface groups at the 110 face of goethite were assumed to form both monodentate and bidentate surface species with cadmium. The CD-MUSIC model is able to describe data sets of both simultaneous and single adsorption of cadmium and phosphate with the same parameters. The model calculations confirmed the idea that only singly coordinated surface groups are reactive for specific ion binding.

  14. Cadmium inhalation and male reproductive toxicity

    SciTech Connect

    Ragan, H.A.; Mast, T.J. )

    1990-01-01

    Cadmium is a highly toxic element that is cumulative and has a long biological half-life in mammals. The severe toxicity of cadmium in man has been known for more than 100 years. Despite the knowledge that cadmium is toxic, only 20 human cases of poisoning via ingestion were recorded prior to 1941, whereas in the ensuing five-year period more than 680 cases of cadmium poisonings from accidental oral ingestion of this metal were documented. Some of the recorded effects of exposure to cadmium in laboratory animals include renal tubular damage, placental and testicular necrosis, structural and functional liver damage, osteomalacia, testicular tumors, teratogenic malformations, anemia, hypertension, pulmonary edema, chronic pulmonary emphysema, and induced deficiencies of iron, copper, and zinc. Some of these effects have also been observed in human after accidental exposures to cadmium oxide fumes and are characteristic of the syndrome described in Japan as Itai Itai disease in which ingestion of cadmium is the inciting chemical.134 references.

  15. Cadmium determination in Mexican-produced tobacco

    SciTech Connect

    Saldivar De R., L.; Soto, R.; Fortoul, T.I. ); Luna, M.; Reyes, E. )

    1991-06-01

    Exposure to cadmium by inhalation or ingestion is dangerous for human health. This metal induces damage to the kidneys, the bones, the prostate, and the lungs. In the lungs, cadmium can produce cancer, emphysema, and fibrosis. It is well known that tobacco leaves are contaminated with cadmium, a metal that has been related to pulmonary damage. In this paper the authors report the concentration of cadmium in tobacco leaves and in cigarettes produced for domestic consumption. Fifty-five cigarettes of different brands, prices, and stocks were analyzed as well as 48 samples from four different types of tobacco. The average concentration of cadmium in cigarettes was 4.41 {plus minus} 0.67 {mu}g/g, and 2.65 {plus minus} 0.99 {mu}g/g for tobacco leaves; the content of cadmium, was 2.8 {plus minus} 0.4 {mu}g/cigarette. It was estimated that a person that smokes 20 Mexican cigarettes per day can increase his(her) cadmium burden by 1.4 to 2.8 {mu}g per day.

  16. Process for producing large grain cadmium telluride

    DOEpatents

    Hasoon, F.S.; Nelson, A.J.

    1996-01-16

    A process is described for producing a cadmium telluride polycrystalline film having grain sizes greater than about 20 {micro}m. The process comprises providing a substrate upon which cadmium telluride can be deposited and placing that substrate within a vacuum chamber containing a cadmium telluride effusion cell. A polycrystalline film is then deposited on the substrate through the steps of evacuating the vacuum chamber to a pressure of at least 10{sup {minus}6} torr.; heating the effusion cell to a temperature whereat the cell releases stoichiometric amounts of cadmium telluride usable as a molecular beam source for growth of grains on the substrate; heating the substrate to a temperature whereat a stoichiometric film of cadmium telluride can be deposited; and releasing cadmium telluride from the effusion cell for deposition as a film on the substrate. The substrate then is placed in a furnace having an inert gas atmosphere and heated for a sufficient period of time at an annealing temperature whereat cadmium telluride grains on the substrate grow to sizes greater than about 20 {micro}m.

  17. Process for producing large grain cadmium telluride

    DOEpatents

    Hasoon, Falah S.; Nelson, Art J.

    1996-01-01

    A process for producing a cadmium telluride polycrystalline film having grain sizes greater than about 20 .mu.m. The process comprises providing a substrate upon which cadmium telluride can be deposited and placing that substrate within a vacuum chamber containing a cadmium telluride effusion cell. A polycrystalline film is then deposited on the substrate through the steps of evacuating the vacuum chamber to a pressure of at least 10.sup.-6 torr.; heating the effusion cell to a temperature whereat the cell releases stoichiometric amounts of cadmium telluride usable as a molecular beam source for growth of grains on the substrate; heating the substrate to a temperature whereat a stoichiometric film of cadmium telluride can be deposited; and releasing cadmium telluride from the effusion cell for deposition as a film on the substrate. The substrate then is placed in a furnace having an inert gas atmosphere and heated for a sufficient period of time at an annealing temperature whereat cadmium telluride grains on the substrate grow to sizes greater than about 20 .mu.m.

  18. Response of Pleurotus ostreatus to cadmium exposure

    SciTech Connect

    Favero, N.; Bressa, G.; Costa, P. )

    1990-08-01

    The possibility of utilizing agroindustrial wastes in the production of edible, high-quality products (e.g., mushrooms) implies the risk of bringing toxic substances, such as heavy metals, into the human food chain. Thus, growth in the presence of cadmium and cadmium accumulation limits have been studied in the industrially cultivated fungus P. ostreatus. Fruit body production is substantially unaffected in the presence of 25, 139, and 285 mg Cd/kg of dried substrate. Cadmium concentration in fruit bodies is related to cadmium substrate level, the metal being present at higher levels in caps (22-56 mg/kg dry wt) than in stems (13-36 mg/kg dry wt). Concentration factor (CF), very low in the controls (about 2), further decreases in treated specimens. The presence of a cadmium control mechanism in this fungi species is suggested. Fruit body cadmium levels could, however, represent a risk for P. ostreatus consumers, according to FAO/WHO limits related to weekly cadmium intake.

  19. Urinary metallothionein as an indicator of cadmium body burden and of cadmium-induced nephrotoxicity

    SciTech Connect

    Shaikh, Z.A.; Tohyama, C.

    1984-03-01

    There is a need to identify specific biological indicator(s) of cadmium exposure so that the renal damage can be prevented. Towards this end, the usefulness of urinary metallothionein as an indicator of cadmium body burden has been examined. It is found that, in both animals and humans, urinary metallothionein level is related to the hepatic and renal cadmium burdens. Significant correlations are also found between the urinary metallothionein and urinary cadmium and ..beta../sub 2/-microglobulin. Furthermore, it is noted that cadmium-exposed individuals with renal dysfunction excrete significantly more metallothionein than those with normal renal function. Thus it appears that there is merit to include metallothionein among the clinical parameters monitored in cadmium-exposed individuals. More tests are needed to define a critical concentration of metallothionein in urine which is related to the onset of renal dysfunction.

  20. Murine strain differences and the effects of zinc on cadmium concentrations in tissues after acute cadmium exposure.

    PubMed

    King, L M; Anderson, M B; Sikka, S C; George, W J

    1998-10-01

    The role of strain differences in cadmium tissue distribution was studied using sensitive (129/J) and resistant (A/J) mice. These murine strains have previously been shown to differ in their susceptibility to cadmium-induced testicular toxicity. Cadmium concentration was measured in testis, epididymis, seminal vesicle, liver, and kidney at 24 h after cadmium chloride exposure (4, 10, and 20 micromol/kg CdCl2). The 129/J mice exhibited a significant increase in cadmium concentration in testis, epididymis, and seminal vesicle at all cadmium doses used, compared to A/J mice. However, cadmium concentrations in liver and kidney were not different between the strains, at any dose, indicating that cadmium uptake is similar in these organs at 24 h. These murine strains demonstrate similar hepatic and renal cadmium uptake but significantly different cadmium accumulation in the reproductive organs at 24 h. The mechanism of the protective effect of zinc on cadmium toxicity was studied by assessing the impact of zinc acetate (ZnAc) treatment on cadmium concentrations in 129/J mice after 24 h. Zinc pretreatment (250 micromol/kg ZnAc), given 24 h prior to 20 micromol/kg CdCl2 administration, significantly decreased the amount of cadmium in the testis, epididymis, and seminal vesicle of 129/J mice, and significantly increased the cadmium content of the liver after 24 h. Cadmium levels in the kidney were unaffected at this time. Zinc pretreatment also prevented the cadmium-induced decrease in testicular sperm concentration and epididymal sperm motility seen in 129/J mice. These findings suggest that the differences in the two murine strains may be attributed partly to the differential accumulation of cadmium in murine gonads. This may be caused by strain differences in the specificity of cadmium transport mechanisms. The protective role of zinc in cadmium-induced testicular toxicity in the sensitive strain may be due to an interference in the cadmium uptake by susceptible

  1. Meteor Beliefs Project: The Palladium in ancient and early Medieval sources

    NASA Astrophysics Data System (ADS)

    McBeath, A. Alistair; Gheorghe, A. D.

    2004-08-01

    An examination of the, apparently meteoritic, object, anciently called the Palladium after the Greek goddess Pallas Athene, is presented, as discussed in various ancient and early medieval sources. Although made of wood, the Palladium was believed to have fallen from the sky. In myths, it was a powerful totemic object, first at the legendary city of Troy, then later at Rome, and had magically protective properties associated with it. Despite its implausibly meteoritic nature, the Palladium can be suggested as supporting the case for ancient meteorite worship.

  2. A palladium-nanoparticle and silicon-nanowire-array hybrid: a platform for catalytic heterogeneous reactions.

    PubMed

    Yamada, Yoichi M A; Yuyama, Yoshinari; Sato, Takuma; Fujikawa, Shigenori; Uozumi, Yasuhiro

    2014-01-01

    We report the development of a silicon nanowire array-stabilized palladium nanoparticle catalyst, SiNA-Pd. Its use in the palladium-catalyzed Mizoroki-Heck reaction, the hydrogenation of an alkene, the hydrogenolysis of nitrobenzene, the hydrosilylation of an α,β-unsaturated ketone, and the C-H bond functionalization reactions of thiophenes and indoles achieved a quantitative production with high reusability. The catalytic activity reached several hundred-mol ppb of palladium, reaching a TON of 2 000 000.

  3. Longitudinal studies of exposure to cadmium.

    PubMed Central

    Armstrong, R; Chettle, D R; Scott, M C; Blindt, M; Mason, H J

    1992-01-01

    Measurements of urinary proteins, blood and urinary cadmium, and in vivo kidney and liver cadmium have been made for a group of workers at several times between 1981 and 1990. The possibility of the introduction of measurement artifacts due to the use of different in vivo measurement systems has been assessed and is considered to be small. Changes in cadmium body burden with time have been studied in relation to kidney function. The results suggest several interesting patterns, although more data are needed to elucidate these further. They do, however, show the effectiveness of good hygiene in the workplace. PMID:1515347

  4. Cadmium blood concentrations in relation to nutrition.

    PubMed

    Krajcovicová-Kudládková, Marica; Ursínyová, Monika; Masánová, Vlasta; Béderová, Alzbeta; Valachovicová, Martina

    2006-09-01

    Cadmium is a toxic element ubiquitous in the environment, which damages biological systems in various ways. The major source of cadmium exposure is food. High cadmium content in the soil leads to high cadmium concentrations in certain plants such as grains (above all surface layers and germs), oil or non-oil seeds, fruit and vegetables. These food commodities are the crucial components of a vegetarian nutrition. Blood cadmium concentrations were measured in two non-smoking population groups: the vegetarian group (n = 80) and the non-vegetarian (control) group of general population on traditional mixed diet (n = 84). The significantly higher blood cadmium content (1.78 +/- 0.22 vs. 0.45 +/- 0.04 microg/l) was measured in vegetarian group. Healthy risk values > 5 microg/l were found in 6 vegetarians vs. no non-vegetarian. The highest cadmium concentration (3.15 +/- 0.77 microg/l) was measured in vegan subgroup (plant food only, n = 10) and that value decreased with increasing animal food consumption (1.75 +/- 0.36 microg/l, lactovegetarian and lactoovovegetarian subgroup/added dairy products and eggs, n = 41/, 1.34 +/- 0.21 microg/I, semivegetarian subgroup /as a previous subgroup and added white meat, n = 291). Risk vegetarians vs. non-risk vegetarians consume significantly higher amounts of whole grain products, grain sprouts and oil seeds. Blood cadmium content is directly influenced by age (r = 0.32, p < 0.001), by whole grain product intake (r = 0.66, p < 0.001) and by duration of vegetarianism (r = 0.5, p < 0.001). Oxidative stress plays a major role in chronic cadmium induced hepatic and renal toxicity as well as in other consequences of cadmium injuries. Vegetarians have significantly higher plasma concentrations of natural antioxidants. The sufficient antioxidative protection against cadmium induced free radical formation in vegetarians may inhibit the harmful effects of greater cadmium intake from plant food.

  5. Cadmium blood concentrations in relation to nutrition.

    PubMed

    Krajcovicová-Kudládková, Marica; Ursínyová, Monika; Masánová, Vlasta; Béderová, Alzbeta; Valachovicová, Martina

    2006-09-01

    Cadmium is a toxic element ubiquitous in the environment, which damages biological systems in various ways. The major source of cadmium exposure is food. High cadmium content in the soil leads to high cadmium concentrations in certain plants such as grains (above all surface layers and germs), oil or non-oil seeds, fruit and vegetables. These food commodities are the crucial components of a vegetarian nutrition. Blood cadmium concentrations were measured in two non-smoking population groups: the vegetarian group (n = 80) and the non-vegetarian (control) group of general population on traditional mixed diet (n = 84). The significantly higher blood cadmium content (1.78 +/- 0.22 vs. 0.45 +/- 0.04 microg/l) was measured in vegetarian group. Healthy risk values > 5 microg/l were found in 6 vegetarians vs. no non-vegetarian. The highest cadmium concentration (3.15 +/- 0.77 microg/l) was measured in vegan subgroup (plant food only, n = 10) and that value decreased with increasing animal food consumption (1.75 +/- 0.36 microg/l, lactovegetarian and lactoovovegetarian subgroup/added dairy products and eggs, n = 41/, 1.34 +/- 0.21 microg/I, semivegetarian subgroup /as a previous subgroup and added white meat, n = 291). Risk vegetarians vs. non-risk vegetarians consume significantly higher amounts of whole grain products, grain sprouts and oil seeds. Blood cadmium content is directly influenced by age (r = 0.32, p < 0.001), by whole grain product intake (r = 0.66, p < 0.001) and by duration of vegetarianism (r = 0.5, p < 0.001). Oxidative stress plays a major role in chronic cadmium induced hepatic and renal toxicity as well as in other consequences of cadmium injuries. Vegetarians have significantly higher plasma concentrations of natural antioxidants. The sufficient antioxidative protection against cadmium induced free radical formation in vegetarians may inhibit the harmful effects of greater cadmium intake from plant food. PMID:17152224

  6. Cost estimate for muddy water palladium production facility at Mound

    SciTech Connect

    McAdams, R.K.

    1988-11-30

    An economic feasibility study was performed on the ''Muddy Water'' low-chlorine content palladium powder production process developed by Mound. The total capital investment and total operating costs (dollars per gram) were determined for production batch sizes of 1--10 kg in 1-kg increments. The report includes a brief description of the Muddy Water process, the process flow diagram, and material balances for the various production batch sizes. Two types of facilities were evaluated--one for production of new, ''virgin'' palladium powder, and one for recycling existing material. The total capital investment for virgin facilities ranged from $600,000 --$1.3 million for production batch sizes of 1--10 kg, respectively. The range for recycle facilities was $1--$2.3 million. The total operating cost for 100% acceptable powder production in the virgin facilities ranged from $23 per gram for a 1-kg production batch size to $8 per gram for a 10-kg batch size. Similarly for recycle facilities, the total operating cost ranged from $34 per gram to $5 per gram. The total operating cost versus product acceptability (ranging from 50%--100% acceptability) was also evaluated for both virgin and recycle facilities. Because production sizes studied vary widely and because scale-up factors are unknown for batch sizes greater than 1 kg, all costs are ''order-of-magnitude'' estimates. All costs reported are in 1987 dollars.

  7. Palladium dimers adsorbed on graphene: A DFT study

    SciTech Connect

    Kaur, Gagandeep; Gupta, Shuchi; Dharamvir, Keya

    2015-05-15

    The 2D structure of graphene shows a great promise for enhanced catalytic activity when adsorbed with palladium. We performed a systematic density functional theory (DFT) study of the adsorption of palladium dimer (Pd{sub 2}) on graphene using SIESTA package, in the generalized gradient approximation (GGA). The adsorption energy, geometry, and charge transfer of Pd{sub 2}-graphene system are calculated. Both horizontal and vertical orientations of Pd{sub 2} on graphene are studied. Our calculations revealed that the minimum energy configuration for Pd dimer is parallel to the graphene sheet with its two atoms occupying centre of adjacent hexagonal rings of graphene sheet. Magnetic moment is induced for Pd dimer adsorbed on graphene in vertical orientation while horizontal orientation of Pd dimer on graphene do not exhibit magnetism. Insignificant energy differences among adsorption sites means that dimer mobility on the graphene sheet is high. There is imperceptible distortion of graphene sheet perpendicular to its plane. However, some lateral displacements are seen.

  8. Palladium(II) complexes of diphenylvinyl- and phenyldivinylphosphine

    SciTech Connect

    Rahn, J.A.; Holt, M.S.; O'Neil-Johnson, M.; Nelson, J.H.

    1988-04-20

    Palladium(II) complexes of the ligands L = Ph/sub 2/PCH/double bond/CH/sub 2/ and PhP(CH/double bond/CH/sub 2/)/sub 2/ have been prepared and characterized by elemental analysis, infrared spectroscopy, and /sup 1/H, /sup 1/H(/sup 31/P), /sup 13/C(/sup 1/H), /sup 31/P(/sup 1/H), and /sup 1/H//sup 13/C HETCOR nuclear magnetic resonance spectroscopy. These complexes exist as temperature-dependent equilibrium mixtures of cis and trans isomers in solution. Equilibrium thermodynamics for the isomerization process cis-L/sub 2/PdX/sub 2/ /rightleftharpoons/ trans-L/sub 2/PdX/sub 2/, determined by variable-temperature /sup 31/P(/sup 1/H) NMR spectroscopy, demonstrate that the cis isomers are in general thermodynamically more stable than the trans isomers. However, the relatively isomer stabilities are anion dependent with the trans isomer becoming more stable in the order Cl < Br < I. Coordination of a vinylphosphine to palladium(II) strongly polarizes the C/double bond/C double bond as evidenced by /sup 13/C NMR data. 27 refs., 2 figs., 4 tabs.

  9. The Myth of the Silver Surfer

    ERIC Educational Resources Information Center

    Gorard, Stephen; Selwyn, Neil

    2008-01-01

    In this article, the authors write about the myth of the "silver surfers"--those third-age learners adept at using the internet and other technologies for a mixture of formal and informal learning episodes. The notion of the silver surfer has endured since the latter half of the 1990s. It is sustained by the annual Silver Surfer week, media…

  10. Accumulation of cadmium and zinc in Evodiopanax innovans.

    PubMed

    Takenaka, Chisato; Kobayashi, Motoharu; Kanaya, Shotaro

    2009-12-01

    The use of tree species for phytoremediation of contaminated soil offers the advantage of a large biomass in which to store contaminants. We investigated the cadmium (Cd) and zinc (Zn) accumulation ability of Evodiopanax innovans, a common deciduous tree species belonging to the Araliaceae family and widely found in secondary forests in Japan. Sampling was conducted at an old silver mine. Leaf samples were collected from nine tree species, including E. innovans. The seasonal variation of metal concentrations in the leaves and the detailed distribution of metals in the leaves and twigs of E. innovans were measured. We also analyzed the contents of organic acids in the leaves. The highest concentration of Cd in the leaves of E. innovans was 118 μg/g, which exceeds the threshold level for being considered a Cd hyperaccumulator (100 μg/g). For Zn, the highest value was 1040 μg/g in leaves, which is less than required to qualify as a Zn hyperaccumulator. Both Cd and Zn were found to accumulate in the petioles and veins of leaves and the bark of twigs. Since the oxalic acid content of leaves showed a weak correlation with Cd concentration, oxalic acid may play an important role in the accumulation of Cd. Taking both the Cd concentration level and the biomass of this woody plant into consideration, it may be possible to use E. innovans for the phytoremediation of Cd-contaminated soils.

  11. Durable silver coating for mirrors

    DOEpatents

    Wolfe, Jesse D.; Thomas, Norman L.

    2000-01-01

    A durable multilayer mirror includes reflective layers of aluminum and silver and has high reflectance over a broad spectral range from ultraviolet to visible to infrared. An adhesion layer of a nickel and/or chromium alloy or nitride is deposited on an aluminum surface, and a thin layer of silver is then deposited on the adhesion layer. The silver layer is protected by a passivation layer of a nickel and/or chromium alloy or nitride and by one or more durability layers made of metal oxides and typically a first layer of metal nitride. The durability layers may include a composite silicon aluminum nitride and an oxinitride transition layer to improve bonding between nitride and oxide layers.

  12. Geometrical parameters effects on local electric field enhancement of silver-dielectric-silver multilayer nanoshell

    SciTech Connect

    Shirzaditabar, Farzad; Saliminasab, Maryam

    2013-05-15

    The local electric field enhancement at different points of silver-dielectric-silver nanoshell is investigated using quasi-static theory. Because of the symmetric and anti-symmetric coupling between surface plasmon of inner silver core and outer silver shell, the local electric field spectrum of silver-dielectric-silver has two distinct peaks at resonance wavelengths. The silver core size and middle dielectric thickness affect the local electric field enhancement at different points of silver-dielectric-silver nanoshell. Increasing the silver core radius always leads to blue shift of shorter resonance wavelength and red shift of longer resonance wavelength. We observed two distinct local electric field peaks, which are corresponded to the symmetric and anti-symmetric coupling between inner and outer surface plasmons. In a system with thick silver shell, local electric field enhancement is greater than a system with thin silver shell. However, the local electric field variations as a function of silver core radius in both systems are different at different points of nanoshell. The effects of the dielectric thickness variations on local electric field are different from those from silver core size variations. As the dielectric thickness is about 3 nm, the highest local electric field enhancement occurs at the surface of the inner silver core, where the symmetric and anti-symmetric modes are mixed together.

  13. Geometrical parameters effects on local electric field enhancement of silver-dielectric-silver multilayer nanoshell

    NASA Astrophysics Data System (ADS)

    Shirzaditabar, Farzad; Saliminasab, Maryam

    2013-05-01

    The local electric field enhancement at different points of silver-dielectric-silver nanoshell is investigated using quasi-static theory. Because of the symmetric and anti-symmetric coupling between surface plasmon of inner silver core and outer silver shell, the local electric field spectrum of silver-dielectric-silver has two distinct peaks at resonance wavelengths. The silver core size and middle dielectric thickness affect the local electric field enhancement at different points of silver-dielectric-silver nanoshell. Increasing the silver core radius always leads to blue shift of shorter resonance wavelength and red shift of longer resonance wavelength. We observed two distinct local electric field peaks, which are corresponded to the symmetric and anti-symmetric coupling between inner and outer surface plasmons. In a system with thick silver shell, local electric field enhancement is greater than a system with thin silver shell. However, the local electric field variations as a function of silver core radius in both systems are different at different points of nanoshell. The effects of the dielectric thickness variations on local electric field are different from those from silver core size variations. As the dielectric thickness is about 3 nm, the highest local electric field enhancement occurs at the surface of the inner silver core, where the symmetric and anti-symmetric modes are mixed together.

  14. Sulfidation of silver nanoparticles

    NASA Astrophysics Data System (ADS)

    Levard, C.; Michel, F. M.; Brown, G. E.

    2010-12-01

    Rapid development of nanotechnologies that exploit the properties of silver nanoparticles (Ag-NPs) raises questions concerning the impact of Ag on the environment. Ag-NPs are currently among the most widely used in the nanotechnology industry and the amount released into the environment is expected to increase along with production (1). When present in geochemical systems, Ag-NPs may undergo a variety of changes due to varying redox, pH, and chemical conditions. Expected changes range from surface modification (e.g., oxidation, sulfidation, chloridation etc.) to complete dissolution and re-precipitation. In this context, the focus of our work is on understanding the behavior of synthetic Ag-NPs with different particle sizes under varying conditions relevant to the environment. Sulfidation of Ag-NPs is of particular interest since it among the processes most likely to occur in aqueous systems, in particular under reducing conditions. Three sizes of Ag-NPs coated with polyvinyl pyrrolidone were produced using the polyol process (2) (7 ±1; 20 ±4, and 40 ±9 nm). Batch solutions containing the different Ag-NPs were subsequently reacted with Na2S solutions of different concentrations. The sulfidation process was followed step-wise for 24 hours and the corrosion products formed were characterized by electron microscopy (TEM/SEM), diffraction (XRD), and photo-electron spectroscopy (XPS). Surface charge (pHPZC) of the products formed during this process was also measured, as were changes in solubility and reactivity. Based on experimental observations we infer that the sulfidation process is the result of dissolution-precipitation and find that: (i) acanthite (Ag2S) is formed as a corrosion product; (ii) Ag-NPs aggregation increased with sulfidation rate; (iii) pHPZC increases with the rate of sulfidation; and (iv) the solubility of the corrosion products formed from sulfidation appears lower than that of non-sulfidated Ag-NPs. We observe size-dependent differences in

  15. Room temperature chemical bath deposition of cadmium selenide, cadmium sulfide and cadmium sulfoselenide thin films with novel nanostructures

    NASA Astrophysics Data System (ADS)

    VanderHyde, Cephas A.; Sartale, S. D.; Patil, Jayant M.; Ghoderao, Karuna P.; Sawant, Jitendra P.; Kale, Rohidas B.

    2015-10-01

    A simple, convenient and low cost chemical synthesis route has been used to deposit nanostructured cadmium sulfide, selenide and sulfoselenide thin films at room temperature. The films were deposited on glass substrates, using cadmium acetate as cadmium ion and sodium selenosulfate/thiourea as a selenium/sulfur ion sources. Aqueous ammonia was used as a complex reagent and also to adjust the pH of the final solution. The as-deposited films were uniform, well adherent to the glass substrate, specularly reflective and red/yellow in color depending on selenium and sulfur composition. The X-ray diffraction pattern of deposited cadmium selenide thin film revealed the nanocrystalline nature with cubic phase; cadmium sulfide revealed mixture of cubic along with hexagonal phase and cadmium sulfoselenide thin film were grown with purely hexagonal phase. The morphological observations revealed the growth and formation of interesting one, two and three-dimensional nanostructures. The band gap of thin films was calculated and the results are reported.

  16. Correlation between theoretical descriptor and catalytic oxygen reduction activity of graphene supported palladium and palladium alloy electrocatalysts

    NASA Astrophysics Data System (ADS)

    Seo, Min Ho; Choi, Sung Mook; Lee, Dong Un; Kim, Won Bae; Chen, Zhongwei

    2015-12-01

    The oxygen reduction reaction, ORR, performances of graphene-supported palladium (Pd) and palladium alloys (Pd3X: X = Ag, Co and Fe) catalysts with highly dispersed catalyst particles are investigated in acidic and alkaline conditions using a rotating disk electrode, RDE. Graphene nanosheet, GNS, supported Pd based catalysts are fabricated without surfactant through the impregnation of Pd and 2nd metal precursors on GNS, leading to small and uniformly dispersed nanoparticles, even when high metal loading of up to 60 wt.% are deposited on supports. The ab-initio density functional theory, DFT, calculations, which are based on the d-band center theory, have been applied to correlate with the results of the ORR performances obtained by half-cell tests. Additionally, the cohesive energy, Ecoh, and dissolution potential, Um, for the Pd nanoparticles have been calculated to understand thermodynamic stability. To elucidate the d-band center shift, the Pd 3d5/2 core-level binding energies for Pd/GNS, Pd3Ag/GNS, Pd3Fe/GNS and Pd3Co/GNS have been investigated by X-ray photoelectron spectroscopy, XPS. The GNS-supported Pd, or Pd-based alloy-nanoparticle catalyst shows good ORR activity under acidic and alkaline conditions, suggesting it may offer potential replacement for Pt for use in cathode electrodes of anion-exchange membrane fuel cell, AEMFC, and acid based polymer electrolyte fuel cell, PEMFC.

  17. Research support for cadmium telluride crystal growth

    NASA Technical Reports Server (NTRS)

    Rosenberger, Franz; Banish, Michael

    1993-01-01

    Work performed during the period 11 Feb. 1992 to 10 Aug. 1993 on research support for cadmium telluride crystal growth is reported. Work on chemical impurity characterization and mass spectroscopy is described.

  18. Floating zone melting of cadmium telluride

    NASA Technical Reports Server (NTRS)

    Chang, Wen-Ming; Regel, L. L.; Wilcox, W. R.

    1992-01-01

    To produce superior crystals of cadmium telluride, floating zone melting in space has been proposed. Techniques required for floating zone melting of cadmium telluride are being developed. We have successfully float-zoned cadmium telluride on earth using square rods. A resistance heater was constructed for forming the molten zone. Evaporation of the molten zone was controlled by adding excess cadmium to the growth ampoule combined with heating of the entire ampoule. An effective method to hold the feed rod was developed. Slow rotation of the growth ampoule was proven experimentally to be necessary to achieve a complete symmetric molten zone. Most of the resultant cylindrical rods were single crystals with twins. Still needed is a suitable automatic method to control the zone length. We tried a fiber optical technique to control the zone length, but experiments showed that application of this technique to automate zone length control is unlikely to be successful.

  19. Lactation-induced cadmium-binding proteins

    SciTech Connect

    Bhattacharyya, M.H.; Solaiman, D.; Garvey, J.S.; Miyazaki, W.Y.

    1987-01-01

    Previously we have demonstrated an increase during midlactation in /sup 109/Cd adsorption and increased retention by the duodenum, kidney, and mammary tissue of mouse dams receiving environmental levels of cadmium//sup 109/Cd via drinking water, with little change in /sup 109/Cd retention in liver and jejunum compared to nonpregnant controls. Results are reported here of a study of cadmium deposition during midlactation as associated with induction of metallothionein (MT). A cadmium/hemoglobin (Cd/Hb) assay and radioimmunoassay for MT which measures heat-stable cadmium binding capacity in tissues was used to determine MT concentrations in fractions of kidney, liver, duodenum, and jejunum from female mice. Both assays demonstrated clear lactation-induced increases in MT concentrations in liver, kidney, and duodenum, with MT concentrations falling rapidly to control levels after weaning. 4 refs., 1 tab.

  20. Effect of cadmium on meiosis. [Rats

    SciTech Connect

    Fowler, A.J.; Singh, D.N.; Dwivedi, C.

    1982-10-01

    Adult male albino Sprague-Dawley rats were injected with cadmium as cadmium chloride at dosages of 5 and 10 ..mu..moles/kg. After sacrifice, testes were removed and cells prepared for microscopic analysis. Counts of chromosome number at dysjunction or precocious separation of homologous and sex chromosomes were made. The degeneration of sex vesicles at early prophase and tetraploid cells at metaphase I and II was scored and compared with control data. At least three hundred cells were counted from each slide. Results indicate that cadmium produces degeneration of sex vesicles, precocious separation of sex chromosomes, and tetraploidy. Increased occurrence was observed at 72 hours after cadmium injection and at the higher dosage of 10 ..mu..moles/kg compared with a post-injection time of 48 hours and a dosage of 5 ..mu..moles/kg. However, a significant tetraploidy was observed only at 10 ..mu..moles/kg. (JMT)

  1. Electronic properties of polycrystalline ceramic cadmium sulphide

    NASA Astrophysics Data System (ADS)

    Saha, H.; Das, S.

    1985-11-01

    An attempt has been made to explain the current transport mechanism of ceramic cadmium sulphide lasers using a semiconductor-grain boundary-semiconductor barrier model. It is shown that a sine-hyperbolic current-voltage relationship holds good for ceramic cadmium sulphide. Grain boundary parameters like potential barrier (phi sub B) and average one-electron trapping state density (N sub T) in the grain boundary are determined experimentally for the first time for ceramic cadmium sulphide through the study of the current-voltage characteristics and zero-bias capacitances. The variation of phi sub B and (N sub T) with temperature (28 C to -120 C) and bias voltage has also been investigated. It is concluded that the thermionic field emission components of current play a major role in the current transport characteristics of a ceramic cadmium sulphide layer.

  2. Solvent extraction of palladium(II) with a Schiff base and separation of palladium from Pd(II)-Pt(VI) mixture

    SciTech Connect

    Ouyang, J.M.

    1999-09-01

    A new Schiff base extractant, N,N{prime}-bis[1-phenyl-3-methyl-5-hydroxy-pyrazole-4-benzylidenyl]-1,3-propylene diamine (H{sub 2}A) was synthesized and characterized. The extraction mechanism of palladium(II) from HNO{sub 3} or HCIO{sub 2} medium with H{sub 2}A in chloroform or toluene was investigated. The influences of the Schiff base concentration in the organic phase, the concentration of palladium, the pH and anions (Cl{sup {minus}}, SO{sub 4}{sup =}, NO{sub 3}{sup {minus}}, ClO{sub 4}{sup {minus}}) in the aqueous phase and the temperature on the distribution ration for palladium (II) have been examined. The extracted complex has been confirmed by chemical analysis, thermoanalyses and IR spectroscopy. It was found that palladium is extracted according to the following extraction reaction: Pd(H{sub 2}O){sub 2}Cl{sub 2(a)} + H{sub 2}A{sub (o)} == Pd(HA)Cl{sub (o)}+H{sup +}{sub (a)} + Cl{sup {minus}}{sub (a)} + 2H{sub 2}O. The extraction equilibrium constants of palladium(II) were 8.4 and 21.3 in chloroform and toluene diluents, respectively. The values for the enthalpy and standard free energy of extraction were also obtained. The separation of Pd(II) from the mixed solution of Pd(II)-Pt(IV) was achieved by adjusting the pH.

  3. Wet processing of palladium for use in the tritium facility at Westinghouse, Savannah River, SC. Preparation of palladium using the Mound Muddy Water process

    SciTech Connect

    Baldwin, D.P.; Zamzow, D.S.

    1998-11-10

    Palladium used at Savannah River for tritium storage is currently obtained from a commercial source. In order to better understand the processes involved in preparing this material, Savannah River is supporting investigations into the chemical reactions used to synthesize this material and into the conditions necessary to produce palladium powder that meets their specifications. This better understanding may help to guarantee a continued reliable source for this material in the future. As part of this evaluation, a work-for-others contract between Westinghouse Savannah River Company and the Ames Laboratory Metallurgy and Ceramics Program was initiated. During FY98, the process for producing palladium powder developed in 1986 by Dan Grove of Mound Applied Technologies (USDOE) was studied to understand the processing conditions that lead to changes in morphology in the final product. This report details the results of this study of the Mound Muddy Water process, along with the results of a round-robin analysis of well-characterized palladium samples that was performed by Savannah River and Ames Laboratory. The Mound Muddy Water process is comprised of three basic wet chemical processes, palladium dissolution, neutralization, and precipitation, with a number of filtration steps to remove unwanted impurity precipitates.

  4. Mineral resource of the month: silver

    USGS Publications Warehouse

    Brooks, William E.

    2007-01-01

    Silver has been used for thousands of years as ornaments and utensils, for trade and as the basis of many monetary systems. The metal has played an important part in world history. Silver from the mines at Laurion, Greece, for example, financed the Greek victory over the Persians in 480 B.C. Silver from Potosi, Bolivia, helped Spain become a world power in the 16th and 17th centuries. And silver from the gold-silver ores at the Comstock Lode in Virginia City, Nev., helped keep the Union solvent during the Civil War.

  5. Cadmium Exposure and Incident Peripheral Arterial Disease

    PubMed Central

    Tellez-Plaza, Maria; Guallar, Eliseo; Fabsitz, Richard R.; Howard, Barbara V.; Umans, Jason G.; Francesconi, Kevin A.; Goessler, Walter; Devereux, Richard B.; Navas-Acien, Ana

    2014-01-01

    Background Cadmium has been associated with peripheral arterial disease in cross-sectional studies but prospective evidence is lacking. Our goal was to evaluate the association of urine cadmium concentrations with incident peripheral arterial disease in a large population-based cohort. Methods and Results A prospective cohort study was performed with 2,864 adult American Indians 45-74 years old from Arizona, Oklahoma and North and South Dakota who participated in the Strong Heart Study in 1989-91 and were followed through two follow-up examination visits in 1993-1995 and 1997-1999. Participants were free of peripheral arterial disease, defined as an ankle brachial index <0.9 or >1.4, at baseline and had complete baseline information on urine cadmium, potential confounders and ankle brachial index determinations in the follow-up examinations. Urine cadmium was measured using inductively coupled plasma mass spectrometry (ICPMS) and corrected for urinary dilution by normalization to urine creatinine.. Multivariable-adjusted hazard ratios (HR) were computed using Cox-proportional hazards models for interval-censored data. A total of 470 cases of incident peripheral arterial disease, defined as an ankle brachial index <0.9 or >1.4, were identified. After adjustment for cardiovascular disease risk factors including smoking status and pack-years, the hazard ratio comparing the 80th to the 20th percentile of urine cadmium concentrations was 1.41 (1.05, 1.81). The hazard ratio comparing the highest to the lowest tertile was 1.96 (1.32, 2.81). The associations persisted after excluding participants with ankle brachial index > 1.4 only as well as in subgroups defined by sex and smoking status. Conclusions Urine cadmium, a biomarker of long-term cadmium exposure, was independently associated with incident peripheral arterial disease, providing further support for cadmium as a cardiovascular disease risk factor. PMID:24255048

  6. Cadmium Exposure and Incident Cardiovascular Disease

    PubMed Central

    Tellez-Plaza, Maria; Guallar, Eliseo; Howard, Barbara V.; Umans, Jason G.; Francesconi, Kevin A.; Goessler, Walter; Silbergeld, Ellen K.; Devereux, Richard B.; Navas-Acien, Ana

    2014-01-01

    Background Cadmium is a widespread toxic metal with potential cardiovascular effects, but no studies have evaluated cadmium and incident cardiovascular disease. We evaluated the association of urine cadmium concentration with cardiovascular disease incidence and mortality in a large population-based cohort. Methods We conducted a prospective cohort study of 3,348 American Indian adults aged 45–74 years from Arizona, Oklahoma and North and South Dakota who participated in the Strong Heart Study in 1989–1991. Urine cadmium was measured using inductively coupled plasma mass spectrometry. Follow-up extended through 31 December 2008. Results The geometric mean cadmium level in the study population was 0.94 μg/g (95% confidence interval= 0.92 – 0.93). We identified 1,084 cardiovascular events, including 400 deaths. After adjustment for sociodemographic and cardiovascular risk factors, the hazard ratios (comparing the 80th to the 20th percentile of urine cadmium concentrations) was 1.43 for cardiovascular mortality (95% confidence interval=1.21 – 1.70), and 1.34 for coronary heart disease mortality (1.10 – 1.63). The corresponding hazard ratios for incident cardiovascular disease, coronary heart disease, stroke, and heart failure were 1.24 (1.11 – 1.38), 1.22 (1.08 – 1.38), 1.75 (1.17 – 2.59) and 1.39 (1.01 – 1.94), respectively. The associations were similar in most study subgroups including never-smokers. Conclusions Urine cadmium, a biomarker of long-term exposure, was associated with increased cardiovascular mortality and with increased incidence of cardiovascular disease. These findings support that cadmium exposure is a cardiovascular risk factor. PMID:23514838

  7. Cadmium as a respiratory toxicant

    SciTech Connect

    Grose, E.C.; Graham, J.A.

    1987-01-01

    Cadmium is a major respiratory toxicant as evidenced by numerous human and animal studies. Controlled animal inhalation studies provide supporting evidence to the associations observed in epidemiological studies that Cd has the potential to cause lung fibrosis, emphysema, cancer, and kidney disease after prolonged exposure. Shorter-term exposure studies indicate that mechanisms thought to be involved in several of these chronic disease states (especially fibrosis and emphysema) are acutely activated. The evidence of toxicity is sufficiently clear that a TLV has been set and the International Agency for Research on Cancer has named Cd as a Group B1 substance (probable human carcinogen). The risk to Cd exposure is enhanced by its chemical and physical properties that result in bioaccumulation. Thus, even a low-level exposure over long periods of time would be expected to reach doses that could be toxic.

  8. MOD silver metallization for photovoltaics. Quarterly technical report, March 1, 1984-May 31, 1984. [Metalloorganic deposition

    SciTech Connect

    Vest, G.M.; Vest, R.W.

    1984-07-16

    It was demonstrated that the nature of the initial solvent used to extract the silver neodecanoate during synthesis or to render it into solution for ink formulation has a profound influence on fired film properties. The lower the boiling point of the initial solvent, the more of it was removed during rotary vacuum evaporation, and the less effect it had on fired film properties. Benzene and tetrahydrofuran were superior to xylene and toluene, and inks which used them in their preparation produced fired films with excellent appearance and adhesion if the proper firing sequence was used. The best films also had electrical resistivities very close to that of pure silver, which indicates that near theoretical density was achieved. Platinum and palladium metallo-organic compounds were investigated so that fired films with good solder leach resistance could be produced. Six metallo-organic compounds were synthesized, four of them were used to make inks, and the properties of films made from these inks were evaluated. The most promising compound evaluated was Pt 2,4 pentane dionate, but additional studies are required.

  9. A general and efficient aldehyde decarbonylation reaction by using a palladium catalyst.

    PubMed

    Modak, Atanu; Deb, Arghya; Patra, Tuhin; Rana, Sujoy; Maity, Soham; Maiti, Debabrata

    2012-05-01

    A facile decarbonylation reaction of aldehydes has been developed by employing Pd(OAc)(2). A wide variety of substrates are decarbonylated, without using any exogenous ligand for palladium as well as CO-scavenger.

  10. The palladium assisted transfer reduction of. alpha. ,. beta. -unsaturated nitroalkenes to oximes using ammonium formate

    SciTech Connect

    Kabalka, G.W.; Pace, R.D.; Wadgaonkar, P.P. )

    1990-01-01

    {alpha},{beta}-Unsaturated nitroalkenes are readily reduced to the corresponding oximes in good yields using ammonium formate in the presence of palladium. The reactions occur rapidly at room temperature in a solvent system of methanol and tetrahydrofuran.

  11. Reduction of FCCI effects in lanthanide-iron diffusion couples by doping with palladium

    NASA Astrophysics Data System (ADS)

    Egeland, G. W.; Mariani, R. D.; Hartmann, T.; Porter, D. L.; Hayes, S. L.; Kennedy, J. R.

    2013-09-01

    Fast-reactor metallic fuels produce lanthanide fission products which have been shown to diffuse to the fuel periphery. Lanthanides interacting with the cladding is one cause of fuel-cladding chemical interaction. To test the viability of reducing the interaction by pinning these lanthanides, palladium was chosen as a fuel dopant based on the lanthanide-palladium intermetallic thermodynamic stability and fuel compatibility. Three lanthanides were tested, neodymium, cerium, and praseodymium, along with their 1:1 palladium compounds, against iron using diffusion couples. These experiments show the direct contact effect on iron of each lanthanide and its respective palladium compound at temperatures from 580 °C to 700 °C for 100 h.

  12. PALLADIUM-CATALYZED OXIDATION OF STYRENE AND ALKENES IN PRESENCE OF IONIC LIQUIDS (WACKER REACTION)

    EPA Science Inventory

    The use of ionic liquids in various synthetic transformations is gaining significance due to the enhanced reaction rates, potential for recycling and compatibility with various organic compounds and organometallic catalysts. Palladium-catalyzed oxidation of styrene and other alk...

  13. The palladium-catalyzed intermolecular C-H chalcogenation of arenes.

    PubMed

    Qiu, Renhua; Reddy, Vutukuri Prakash; Iwasaki, Takanori; Kambe, Nobuaki

    2015-01-01

    Palladium catalyzes the intermolecular chalcogenation of carbazole, 2-phenylpyridine, benzo[h]quinolone, and indole derivatives with disulfides and diselenides via selective C-H bond cleavage, providing a convenient route to thio and selenoethers. PMID:25437148

  14. Study of the kinetics of catalytic decomposition of hydrazine vapors on palladium

    NASA Technical Reports Server (NTRS)

    Khomenko, A. A.; Apelbaum, L. O.

    1987-01-01

    The decomposition rates of N2H4 on a palladium surface are studied. Experiments were conducted in a circulating unit at atmosphere pressure. The experimental method is described. The laws found for the reaction kinetics are explained by equations.

  15. Platinum-ruthenium-palladium alloys for use as a fuel cell catalyst

    DOEpatents

    Gorer, Alexander

    2002-01-01

    A noble metal alloy composition for a fuel cell catalyst, a ternary alloy composition containing platinum, ruthenium and palladium. The alloy shows increased activity as compared to well-known catalysts.

  16. Synthesis of 2-indolylphosphines by palladium-catalyzed annulation of 1-alkynylphosphine sulfides with 2-iodoanilines.

    PubMed

    Kondoh, Azusa; Yorimitsu, Hideki; Oshima, Koichiro

    2010-04-01

    Palladium-catalyzed annulation of 1-alkynylphosphine sulfides with 2-iodoanilines followed by desulfidation affords 3-substituted 2-indolylphosphines. This annulation/desulfidation sequential protocol offers a conceptually new approach to bulky heteroarylphosphines.

  17. Palladium-Zeolite nanofiber as an effective recyclable catalyst membrane for water treatment.

    PubMed

    Choi, Jungsu; Chan, Sophia; Yip, Garriott; Joo, Hyunjong; Yang, Heejae; Ko, Frank K

    2016-09-15

    Zeolite is an exciting natural material due to its unique capability of ammonium nitrogen (NH3N) adsorption in water. In this study, multifunctional hybrid composites of zeolite/palladium (Ze/Pd) on polymer nanofiber membranes were fabricated and explored for sustainable contaminant removal. SEM and XRD demonstrated that zeolite and palladium nanoparticles were uniformly distributed and deposited on the nanofibers. NH3N recovery rate was increased from 23 to 92% when palladium coated zeolite was embedded on the nanofiber. Multifunctional nanofibers of Ze/Pd membranes were able to adsorb NH3N on the zeolites placed on the surface of fibers and palladium catalysts were capable of selective oxidation of NH3N to N2 gas. The cycling of NH3N adsorption-oxidation, high flux, hydrophilicity, and flexibility of the membrane makes it a strong candidate for water treatment. PMID:27253639

  18. Methods of IR spectroscopy in monitoring of chemotherapy of oncological pathologies using palladium complexes

    NASA Astrophysics Data System (ADS)

    Tolstorozhev, G. B.; Bel'kov, M. V.; Skornyakov, I. V.; Pekhn'o, V. I.; Kozachkova, A. N.; Tsarik, N. V.; Kutsenko, I. P.; Sharykina, N. I.

    2014-11-01

    FTIR spectroscopy is used to study mammary-gland tissues of mice with a sarcoma tumor (strain 180). Spectral features that are typical of malignant tumors are revealed in the FTIR spectra in the sarcoma-tumor tissues. Tumor tissues are studied after treatment using coordination compounds based on palladium complexes with 3-amino-1-hydroxypropylidene-1,1-diphosphonic acid and zoledronic acid. A therapeutic effect is not revealed after treatment using palladium complex with 3-amino-1-hydroxypropylidene-1,1-diphosphonic acid. The suppression of tumor growth amounts to 59% when palladium complexes with zoledronic acid are used. Suppression of tumor growth is accompanied by variations in spectral characteristics. With respect to diagnostic features, the FTIR spectra of tumor tissues after treatment with the palladium complexes with zoledronic acid are similar to the FTIR spectra of tissues that are free of malignant tumors. Specific spectroscopic characteristics that make it possible to control the chemotherapy of oncological pathologies are determined.

  19. Screening micro-organisms for cadmium absorption from aqueous solution and cadmium absorption properties of Arthrobacter nicotianae.

    PubMed

    Tsuruta, Takehiko; Umenai, Daishi; Hatano, Tomonobu; Hirajima, Tsuyoshi; Sasaki, Keiko

    2014-01-01

    To obtain basic information on how microbial cells absorb cadmium from aqueous solution, we examined cadmium absorption in various micro-organisms. Of 51 micro-organism strains tested, we found that some Gram-positive bacteria, such as, Arthrobacter nicotianae and Bacillus subtilis, and some actinomycetes, such as, Streptomyces flavoviridis and S. levoris were highly capable of absorbing cadmium from an aqueous solution. A. nicotianae absorbed the largest amount of cadmium, over 800 μmol cadmium per gram of dry wt. cells. However, cadmium absorption by A. nicotianae was affected by the solution pH, cadmium concentration, and cell density. The absorption of cadmium was very rapid. Some factors that affected cadmium absorption by A. nicotianae cells were also discussed.

  20. Drinking-Water Criteria Document for Cadmium (final draft), December 1986. Final draft report

    SciTech Connect

    Not Available

    1986-12-01

    The Office of Drinking Water, Environmental Protection Agency has prepared a Drinking Water Criteria Document on Cadmium. The Criteria Document is an extensive review of the following topics: Physical and chemical properties of Cadmium; Toxicokinetics and human exposure to cadmium; health effects of cadmium in humans and animals; mechanisms of toxicological effects of cadmium; and quantification of toxicological effects of cadmium.

  1. Palladium-catalyzed through-space C(sp(3))-H and C(sp(2))-H bond activation by 1,4-palladium migration: efficient synthesis of [3,4]-fused oxindoles.

    PubMed

    Piou, Tiffany; Bunescu, Ala; Wang, Qian; Neuville, Luc; Zhu, Jieping

    2013-11-18

    Palladium two step: Linear anilides were converted into the title compounds in good to excellent yields through a palladium-catalyzed domino carbopalladation/1,4-palladium shift sequence. The C(sp(3) )-H activation involves a seven-membered palladacycle, and is chemoselective in the presence of competitive C(sp(2) )H bonds. DMA=N,N-dimethylacetamide, OPiv=pivalate.

  2. Concentration of cadmium in Coturnix quail fed earthworms.

    PubMed

    Stoewsand, G S; Bache, C A; Gutenmann, W H; Lisk, D J

    1986-01-01

    Earthworms (Lumbriscus terrestris), collected from soils in southern Ontario, Canada, that had no previous history of cadmium application, contained 3 ppm cadmium. They were fed to Coturnix quail as 60% dry weight of their diet for 63 d to examine the extent of deposition of native cadmium. Cadmium in kidney, liver, and excreta was greatly elevated above that of birds fed a control diet without worms. No increase in the level of cadmium in eggs was found. The factors affecting the association of cadmium in soils and worms and their assimilation and possible toxic effects in foraging birds are discussed. PMID:3712497

  3. Concentration of cadmium in Coturnix quail fed earthworms

    SciTech Connect

    Stoewsand, G.S.; Bache, C.A.; Gutenmann, W.H.; Lisk, D.J.

    1986-01-01

    Earthworms (Lumbriscus terrestris), collected from soils in southern Ontario, Canada, that had no previous history of cadmium application, contained 3 ppm cadmium. They were fed to Coturnix quail as 60% dry weight of their diet for 63 d to examine the extent of deposition of native cadmium. Cadmium in kidney, liver, and excreta was greatly elevated above that of birds fed a control diet without worms. No increase in the level of cadmium in eggs was found. The factors affecting the association of cadmium in soils and worms and their assimilation and possible toxic effects in foraging birds are discussed.

  4. Cadmium Modulates Biofilm Formation by Staphylococcus epidermidis

    PubMed Central

    Wu, Xueqing; Santos, Regiane R.; Fink-Gremmels, Johanna

    2015-01-01

    The aim of the study was to evaluate the effect of cadmium exposure on Staphylococcus epidermidis (ATCC 35984) biofilm formation. Bacteria were cultured in the absence or presence of different concentrations (0–50 µM) of cadmium. Biofilm formation and bacterial viability were assessed. Quantitative Real Time-PCR (qRT-PCR) was used to determine the mRNA expression of molecular markers of S. epidermidis biofilm formation and dispersion. S. epidermidis biofilm formation was stimulated (p < 0.001) by 1.56 and 3.13 µM cadmium. Confocal laser scanning microscopy (CLSM) analysis confirmed an increase in biofilm thickness (23 and 22 µm, versus 17.8 µm in the controls) after exposure to 1.56 or 3.13 µM cadmium, respectively. qRT-PCR was performed showing the up-regulation of atlE, embp, aap, icaA and icaB after exposure to 3.13 µM cadmium. Taken together, these findings show that cadmium at low, sub-toxic concentrations acts as inducer of S. epidermidis biofilm formation. PMID:25749322

  5. Cadmium-113 shielding tensors of cadmium compounds. 3. Single-crystal studies on cadmium glycinate monohydrate and cadmium dinitrato bis(1,1,3,3-tetramethyl-2-thiourea)

    SciTech Connect

    Honkonen, R.S.; Marchetti, P.S.; Ellis, P.D.

    1986-03-05

    Cadmium glycinate monohydrate and cadmium dinitrato bis(1,1,3,3-tetramethyl-2-thiourea) have been investigated by single-crystal oriented /sup 113/Cd NMR. The cadmium shielding tensor elements for the two sulfur-four oxygen system in Cd(C/sub 5/H/sub 12/N/sub 2/S)/sub 2/(NO/sub 3/)/sub 2/ are -340, +308, and +327 ppm for sigma/sub 11/, sigma/sub 22/, and sigma/sub 33/, respectively. The 438 ppm anisotropy and the extreme magnitude of sigma/sub 11/ are discussed in terms of cadmium-sulfur and cadmium-nitrate interactions. The orientation of the shielding tensor is in agreement with previous results for oxo-cadmium crystals. The /sup 113/Cd shielding tensor elements for Cd(NH/sub 2/CH/sub 2/CO/sub 2/)''H/sub 2/O were determined to be -116, +200, and +256 ppm relative to solid Cd(ClO/sub 4/)/sub 2/. The orientation of the tensor in this two nitrogen-four oxygen system was found to be dominated by the glycinate chelate moieties. 25 references, 3 figures, 4 tables.

  6. Cadmium Exposure and Risk of Any Fracture

    PubMed Central

    Cheng, Xianlin; Niu, Yuming; Ding, Qingyang; Yin, Xinhai; Huang, Guanglei; Peng, Juxiang; Song, Jukun

    2016-01-01

    Abstract Several observational studies have investigated the relation between cadmium exposure and risk of any fracture. However, the results from epidemiological studies for the association are inconsistent. We conducted a meta-analysis to evaluate the relationship between cadmium exposure and risk of any fracture. The pertinent studies were identified by a search of PubMed and Embase databases from 1966 to June 2015. Seven articles involving 21,941 fracture cases and 504,346 participants were included. The meta-analysis showed that the pooled relative risk of any fracture for the highest versus lowest category of cadmium concentration was 1.30 (95% confidence interval = 1.13–1.49). In subgroup analyses, the significant association remained consistent when stratified by study type, geographical region, method of cadmium exposure assessment, and gender. Our meta-analysis showed that a high cadmium exposure may be a risk factor for any fracture. However, this result should be interpreted cautiously because of the heterogeneity among studies and existence of publication bias. Additional large, high-quality prospective studies are needed to evaluate the association between cadmium exposure and the risk of development of fracture. PMID:26962791

  7. Antagonists for acute oral cadmium chloride intoxication

    SciTech Connect

    Basinger, M.A.; Jones, M.M.; Holscher, M.A.; Vaughn, W.K.

    1988-01-01

    An examination has been carried out on the relative efficacy of a number of chelating agents when acting as antagonists for oral cadmium chloride intoxication in mice. The compounds were administered orally after the oral administration of cadmium chloride at 1 mmol/kg. Of the compounds examined, several were useful in terms of enhancing survival, but by far the most effective in both enhancing survival and leaving minimal residual levels of cadmium in the liver and the kidney, was meso-2,3-dimercaptosuccinic acid (DMSA). Several polyaminocarboxylic acids also enhanced survival. The most effective of these in reducing liver and kidney levels of cadmium were diethylenetriaminepentaacetic acid (DTPA), trans-1,2-diaminocyclohexane-N,N,N'N'-tetraacetic acid (CDTA), and triethylenetetraminehexaacetic acid (TTHA). D-Penicillamine (DPA) was found to promote survival but also led to kidney cadmium levels higher than those found in the controls. Sodium 2,3-dimercaptopropane-1-sulfonate (DMPS) was as effective in promoting survival as DMSA but left levels of cadmium in the kidney and liver that were approximately four times greater than those found with DMSA.

  8. Cadmium affects retinogenesis during zebrafish embryonic development

    SciTech Connect

    Hen Chow, Elly Suk; Yu Hui, Michelle Nga; Cheng, Chi Wa; Cheng, Shuk Han

    2009-02-15

    Ocular malformations are commonly observed in embryos of aquatic species after exposure to toxicants. Using zebrafish embryos as the model organism, we showed that cadmium exposure from sphere stage (4 hpf) to end of segmentation stage (24 hpf) induced microphthalmia in cadmium-treated embryos. Embryos with eye defects were then assessed for visual abilities. Cadmium-exposed embryos were behaviorally blind, showing hyperpigmentation and loss of camouflage response to light. We investigated the cellular basis of the formation of the small eyes phenotype and the induction of blindness by studying retina development and retinotectal projections. Retinal progenitors were found in cadmium-treated embryos albeit in smaller numbers. The number of retinal ganglion cells (RGC), the first class of retinal cells to differentiate during retinogenesis, was reduced, while photoreceptor cells, the last batch of retinal neurons to differentiate, were absent. Cadmium also affected the propagation of neurons in neurogenic waves. The neurons remained in the ventronasal area and failed to spread across the retina. Drastically reduced RGC axons and disrupted optic stalk showed that the optic nerves did not extend from the retina beyond the chiasm into the tectum. Our data suggested that impairment in neuronal differentiation of the retina, disruption in RGC axon formation and absence of cone photoreceptors were the causes of microphthalmia and visual impairment in cadmium-treated embryos.

  9. Influence of injected silver content on synthesis of silver coated nickel particles by DC thermal plasma

    NASA Astrophysics Data System (ADS)

    Park, Si Taek; Kim, Tae-Hee; Park, Dong-Wha

    2016-06-01

    Silver nanoparticle-coated spherical nickel particles were prepared from a mixture of micro-sized silver and nickel as raw materials by DC thermal plasma treatment. The mixture of micro-sized silver and nickel powders was injected into the high-temperature region of an argon thermal plasma jet. Although the silver, with its very high thermal conductivity and relatively low boiling point, was thoroughly evaporated by this process, nickel was not evaporated perfectly because of its comparatively low thermal conductivity and high boiling point. The rough nickel powder was spheroidized as it melted. Finally, silver evaporated by the thermal plasma quickly condensed into nanoparticles on the surfaces of the micro-sized spherical nickel particles, aided by the sharp temperature gradient of the thermal plasma jet. With varying the ratios of silver to nickel feedstock from 1:10 to 5:1, the products synthesized in each condition were examined by XRD, XPS, FE-SEM, and FE-TEM. More silver nanoparticles were attached on the nickel by increasing the injected feedstock to 9.8 at% silver. Meanwhile, a decrease of silver in the products was observed when larger amounts of silver were introduced to the thermal plasma jet. The exposed silver components decreased with greater proportions of silver feedstock because of the metal's dendritic structure and the formation of silver-coated silver particles.

  10. Palladium-catalyzed imidoylative cyclization of α-isocyanoacetamides: efficient access to C2-diversified oxazoles.

    PubMed

    Wang, Jian; Luo, Shuang; Huang, Jinbo; Mao, Tingting; Zhu, Qiang

    2014-08-25

    A novel procedure for the synthesis of C2-diversified oxazoles, through palladium-catalyzed imidoylative cyclization of α-isocyanoacetamides with aryl, vinyl, alkynyl halides, or triflates, was developed. Migratory insertion of isocyanide into a Csp3-palladium(II) intermediate in a cascade process was also realized, generating alkyl-substituted oxazoles. Therefore, oxazoles functionalized at the C2 position with sp, sp(2), and sp(3) hybridized carbon atoms are accessible by applying this method.

  11. Palladium-Catalyzed Dearomative Cyclocarbonylation by C-N Bond Activation.

    PubMed

    Yu, Hui; Zhang, Guoying; Huang, Hanmin

    2015-09-01

    A fundamentally novel approach to bioactive quinolizinones is based on the palladium-catalyzed intramolecular cyclocarbonylation of allylamines. [Pd(Xantphos)I2 ], which features a very large bite angle, has been found to facilitate the rapid carbonylation of azaarene-substituted allylamines into bioactive quinolizinones in good to excellent yields. This transformation represents the first dearomative carbonylation and is proposed to proceed by palladium-catalyzed CN bond activation, dearomatization, CO insertion, and a Heck reaction.

  12. Synthesis of 1,4:3,6-dianhydrohexitols diesters from the palladium-catalyzed hydroesterification reaction.

    PubMed

    Pruvost, Romain; Boulanger, Jérôme; Léger, Bastien; Ponchel, Anne; Monflier, Eric; Ibert, Mathias; Mortreux, André; Chenal, Thomas; Sauthier, Mathieu

    2014-11-01

    The hydroesterification of alpha olefins has been used to synthesize diesters from bio-based secondary diols: isosorbide, isomannide, and isoidide. The reaction was promoted by 0.2% palladium catalyst generated in situ from palladium acetate/triphenylphosphine/para-toluene sulfonic acid. Optimized reaction conditions allowed the selective synthesis of the diesters with high yields and the reaction conditions could be scaled up to the synthesis of hundred grams of diesters from isosorbide and 1-octene with solvent-free conditions.

  13. Noble Metal Catalysts for Mercury Oxidation in Utility Flue Gas: Gold, Palladium and Platinum Formulations

    SciTech Connect

    Presto, A.A.; Granite, E.J

    2008-07-01

    The use of noble metals as catalysts for mercury oxidation in flue gas remains an area of active study. To date, field studies have focused on gold and palladium catalysts installed at pilot scale. In this article, we introduce bench-scale experimental results for gold, palladium and platinum catalysts tested in realistic simulated flue gas. Our initial results reveal some intriguing characteristics of catalytic mercury oxidation and provide insight for future research into this potentially important process.

  14. Palladium(II)-catalyzed direct alkoxylation of arenes: evidence for solvent-assisted concerted metalation deprotonation.

    PubMed

    Anand, Megha; Sunoj, Raghavan B

    2011-09-16

    Density functional theory investigations on the mechanism of palladium acetate catalyzed direct alkoxylation of N-methoxybenzamide in methanol reveal that the key steps involve solvent-assisted N-H as well as C-H bond activations. The transition state for the critical palladium-carbon bond formation through a concerted metalation deprotonation (CMD) process leading to a palladacycle intermediate has been found to be more stable in the methanol-assisted pathway as compared to an unassisted route.

  15. Palladium-catalyzed direct C2 arylation of N-substituted indoles with 1-aryltriazenes.

    PubMed

    Liu, Can; Miao, Tao; Zhang, Lei; Li, Pinhua; Zhang, Yicheng; Wang, Lei

    2014-09-01

    A novel and efficient palladium-catalyzed C2 arylation of N-substituted indoles with 1-aryltriazenes for the synthesis of 2-arylindoles was developed. In the presence of BF3⋅OEt2 and palladium(II) acetate (Pd(OAc)2), N-substituted indoles reacted with 1-aryltriazenes in N,N-dimethylacetamide (DMAC) to afford the corresponding aryl-indole-type products in good to excellent yields.

  16. Development of disposable bulk-modified screen-printed electrode based on bismuth oxide for stripping chronopotentiometric analysis of lead (II) and cadmium (II) in soil and water samples.

    PubMed

    Kadara, Rashid O; Tothill, Ibtisam E

    2008-08-01

    A bulk-modified screen-printed carbon electrode characterised for metal ion detection is presented. Bismuth oxide (Bi(2)O(3)) was mixed with graphite-carbon ink to obtain the modified electrode. The best composition was 2% Bi(2)O(3) (wt%) in the graphite-carbon ink. The modified electrode with onboard screen-printed carbon counter and silver-silver chloride pseudo-reference electrodes exhibited good performance in the electrochemical measurement of lead (II) and cadmium (II). The electrode displayed excellent linear behaviour in the concentration range examined (20-300 microg L(-1)) with limits of detection of 8 and 16 microg L(-1) for both lead (II) and cadmium (II), respectively. The analytical utility of the modified electrode was illustrated by the stripping chronopotentiometric determinations of lead (II) in soil extracts and wastewater samples.

  17. Anomalous biogeochemical behavior of cadmium in subantarctic surface waters: Mechanistic constraints from cadmium isotopes

    NASA Astrophysics Data System (ADS)

    Gault-Ringold, Melanie; Adu, Toyin; Stirling, Claudine H.; Frew, Russell D.; Hunter, Keith A.

    2012-08-01

    Cadmium, a highly toxic metal, exhibits a nutrient-type profile in the oceans that is closely correlated to that of the major nutrients phosphate and nitrate. Despite its complexity, the relationship between cadmium and phosphate has been used to infer historic phosphate utilization and biological controls on oceanic CO2 concentrations. Cadmium isotopes offer the potential to constrain the mechanisms controlling cadmium cycling in the oceans, reducing uncertainty associated with the cadmium paleonutrient proxy. Using techniques in double spiking and MC-ICPMS, we report seasonal Cd isotopic and concentration data along with major nutrients and other essential trace metal (Fe, Zn, and Co) concentrations from subantarctic surface waters. We show, for the first time, a 50-fold seasonal decrease in dissolved cadmium concentrations in subantarctic waters that is due to biological uptake. However, this drawdown in Cd is decoupled from phosphate and shows no coincident shift in cadmium isotopic composition. These data, along with the preferential removal of Cd from surface waters relative to Zn, imply that cadmium is supply-limited to phytoplankton and may have a more significant biological role in these low Zn subantarctic surface waters than in regions with higher Zn concentrations.

  18. Characterization and recycling of cadmium from waste nickel-cadmium batteries.

    PubMed

    Huang, Kui; Li, Jia; Xu, Zhenming

    2010-11-01

    A severe threat was posed due to improper and inefficient recycling of waste batteries in China. The present work considered the fundamental aspects of the recycling of cadmium from waste nickel-cadmium batteries by means of vacuum metallurgy separation in scale-up. In the first stage of this work, the characterization of waste nickel-cadmium batteries was carried out. Five types of batteries from different brands and models were selected and their components were characterized in relation to their elemental chemical composition and main phase. In the second stage of this work, the parameters affecting the recycling of cadmium by means of vacuum metallurgy separation were investigated and a L(16) (4(4)) orthogonal design was applied to optimize the parameters. With the thermodynamics theory and numerical analysis, it can be seen that the orthogonal design is an effective tool for investigating the parameters affecting the recycling of cadmium. The optimum operating parameters for the recycling of cadmium obtained by orthogonal design and verification test were 1073 K (temperature), 2.5h (heating time), 2 wt.% (the addition of carbon powder), and 30 mm (the loaded height), respectively, with recycling efficiency approaching 99.98%. The XRD and ICP-AES analyzed results show that the condensed product was characterized as metallic cadmium, and cadmium purity was 99.99% under the optimum condition. PMID:20541388

  19. The use of palladium to obtain reproducible boundary conditions for permeability measurements using galvanostatic charging

    NASA Astrophysics Data System (ADS)

    Bowker, J.; Piercy, G. R.

    1985-05-01

    The diffusion current of hydrogen through palladium in an electrochemical cell initially rises linearly with the charging current, reaches a steady “plateau” value, and then rises again. The diffusivity of hydrogen in palladium was measured using standard transient techniques in the initial region of low current density. Combining this value with the measured value of diffusion current at the plateau level gave a concentration of hydrogen at the entrance surface of the palladium that was the same for three different palladium thicknesses, and was equal to the saturation value in α palladium. It is proposed that this can be used as a known and reproducible effective hydrogen pressure (0.019 atm) if palladium is plated onto other metals before measuring their permeability in an electrochemical cell. Experimental evidence for this was obtained from permeability measurements made on several thicknesses of iron. Permeation studies were also made on AISI 410 stainless steel and tin plated mild steel. The measured value for electrolytic tinplate was 107 times that expected from extrapolation of high temperature data. This could be attributed to grain boundaries or porosity covering 0.003 pct of the area. The permeability values of iron and stainless steel are 8.4 x 1012 and 2.8 x 1013 H atom/cm • s • √atm, respectively.

  20. Recycling of a spent iron based catalyst for the complete oxidation of toluene: effect of palladium.

    PubMed

    Kim, Sang Chai; Nah, Jae Woon

    2015-01-01

    Complete oxidation of volatile organic compound (toluene) was carried out to assess the property and activity of the palladium-spent iron based catalyst. The properties of the prepared catalysts were characterized by using the Brunauer-Emmett-Teller method and by conducting temperature-programmed reduction, X-ray diffraction, X-ray photoelectron spectroscopy and field emission transmission electron microscopy. The addition of palladium to the spent iron based catalyst pretreated with oxalic acid shifted the conversion curve for the total oxidation of toluene to lower temperature. An increase in the toluene conversion due to palladium was highly related to the easier lattice oxygen mobility of the catalysts. Instrumental analysis suggested the presence of a strong interaction between palladium and iron oxide species. Moreover, in the case of reducing the Pd/Fe catalyst with hydrogen, palladium accelerated the reducing iron oxides, subsequently decreasing the toluene conversion. As a result, the oxidation states of palladium and iron had an important effect on the catalytic activity.

  1. Formation of iron oxides in a highly alkaline medium in the presence of palladium ions

    NASA Astrophysics Data System (ADS)

    Krehula, Stjepko; Musić, Svetozar

    2009-04-01

    The effect of the presence of palladium ions in a highly alkaline precipitation system on the formation of iron oxides was investigated using X-ray powder diffraction (XRPD), Mössbauer and FT-IR spectroscopies, field emission scanning electron microscopy (FE-SEM) and energy dispersive X-ray spectroscopy (EDS). Acicular α-FeOOH particles precipitated in a highly alkaline medium with the addition of tetramethylammonium hydroxide (TMAH) were used as reference material. The initial addition of palladium ions to that precipitation system had a significant effect on the formation of iron oxide phases and their properties. In the presence of palladium ions, the initially formed α-FeOOH has been transformed to α-Fe 2O 3 crystals in the form of hexagonal bipyramids via a dissolution-reprecipitation mechanism with a simultaneous formation of metallic palladium nanoparticles. These palladium nanoparticles acted as a catalyst for the reductive dissolution of α-Fe 2O 3 particles and the formation of Fe 3O 4 crystals in the form of octahedrons. Increase in the initial concentration of palladium ions in the precipitation system accelerated the transformation process α-FeOOH → α-Fe 2O 3 → Fe 3O 4 and influenced changes in the shape of α-Fe 2O 3 and Fe 3O 4 particles.

  2. Tritium production from a low voltage deuterium discharge on palladium and other metals

    SciTech Connect

    Claytor, T.N.; Jackson, D.D.; Tuggle, D.G.

    1995-09-01

    Over the past year the authors have been able to demonstrate that a plasma loading method produces an exciting and unexpected amount of tritium from small palladium wires. In contrast to electrochemical hydrogen or deuterium loading of palladium, this method yields a reproducible tritium generation rate when various electrical and physical conditions are met. Small diameter wires (100--250 microns) have been used with gas pressures above 200 torr at voltages and currents of about 2,000 V at 3--5 A. By carefully controlling the sputtering rate of the wire, runs have been extended to hundreds of hours allowing a significant amount (> 10`s nCi) of tritium to accumulate. they show tritium generation rates for deuterium-palladium foreground runs that are up to 25 times larger than hydrogen-palladium control experiments using materials from the same batch. They illustrate the difference between batches of annealed palladium and as received palladium from several batches as well as the effect of other metals (Pt, Ni, Nb, Zr, V, W, Hf) to demonstrate that the tritium generation rate can vary greatly from batch to batch.

  3. Determination of platinum and palladium in geological materials by neutron-activation analysis after fire-assay preconcentration

    USGS Publications Warehouse

    Rowe, J.J.; Simon, F.O.

    1971-01-01

    Fire-asay preconcentration followed by neutron-activation analysis permits the determination of as little as 0.5 ppM of platinum and 0.5 ppM of palladium on a 20-g sample. Platinum and palladium are separated with carriers and beta-counted. Results for the platinum and palladium content of seven U.S.G.S. standard rocks are presented. ?? 1971.

  4. Development of a second generation palladium-catalyzed cycloalkenylation and its application to bioactive natural product synthesis.

    PubMed

    Toyota, Masahiro

    2013-07-01

    A novel palladium-catalyzed intramolecular oxidative alkylation of unactivated olefins is described. This protocol was devised to solve one of the drawbacks of the original palladium-catalyzed cycloalkenylation that we developed. We call this new procedure the 'second generation palladium-catalyzed cycloalkenylation'. This protocol has been applied to the total syntheses of cis-195A, trans-195A, boonein, scholareins A, C, D, and alpha-skytanthine.

  5. Cadmium removal by Lemna minor and Spirodela polyrhiza.

    PubMed

    Chaudhuri, Devaleena; Majumder, Arunabha; Misra, Amal K; Bandyopadhyay, Kaushik

    2014-01-01

    The present study investigates the ability of two genus of duckweed (Lemna minor and Spirodela polyrhiza) to phytoremediate cadmium from aqueous solution. Duckweed was exposed to six different cadmium concentrations, such as, 0.5,1.0,1.5, 2.0, 2.5, and 3.0 mg/L and the experiment was continued for 22 days. Water samples were collected periodically for estimation of residual cadmium content in aqueous solution. At the end of treatment period plant samples were collected and accumulated cadmium content was measured. Cadmium toxicity was observed through relative growth factor and changes in chlorophyll content Experimental results showed that Lemna minor and Spirodela polyrhiza were capable of removing 42-78% and 52-75% cadmium from media depending upon initial cadmium concentrations. Cadmium was removed following pseudo second order kinetic model Maximum cadmium accumulation in Lemna minor was 4734.56 mg/kg at 2 mg/L initial cadmium concentration and 7711.00 mg/kg in Spirodela polyrhiza at 3 mg/L initial cadmium concentration at the end of treatment period. Conversely in both cases maximum bioconcentration factor obtained at lowest initial cadmium concentrations, i.e., 0.5 mg/L, were 3295.61 and 4752.00 for Lemna minor and Spirodela polyrhiza respectively. The present study revealed that both Lemna minor and Spirodela polyrhiza was potential cadmium accumulator.

  6. Cigarette smoke cadmium breakthrough from traditional filters: implications for exposure.

    PubMed

    Pappas, R Steven; Fresquez, Mark R; Watson, Clifford H

    2015-01-01

    Cadmium, a carcinogenic metal, is highly toxic to renal, skeletal, nervous, respiratory and cardiovascular systems. Accurate and precise quantification of mainstream smoke cadmium levels in cigarette smoke is important because of exposure concerns. The two most common trapping techniques for collecting mainstream tobacco smoke particulate for analysis are glass fiber filters and electrostatic precipitators. We observed that a significant portion of total cadmium passed through standard glass fiber filters that are used to trap particulate matter. We therefore developed platinum traps to collect the cadmium that passed through the filters and tested a variety of cigarettes with different physical parameters for quantities of cadmium that passed though the filters. We found <1% cadmium passed through electrostatic precipitators. In contrast, cadmium that passed through 92 mm glass fiber filters on a rotary smoking machine was significantly higher, ranging from 3.5 to 22.9% of total smoke cadmium deliveries. Cadmium passed through 44 mm filters typically used on linear smoking machines to an even greater degree, ranging from 13.6 to 30.4% of the total smoke cadmium deliveries. Differences in the cadmium that passed through from the glass fiber filters and electrostatic precipitator could be explained in part if cadmium resides in the smaller mainstream smoke aerosol particle sizes. Differences in particle size distribution could have toxicological implications and could help explain the pulmonary and cardiovascular cadmium uptake in smokers.

  7. Characterization of cadmium proteinuria in man and rat.

    PubMed Central

    Lauwerys, R R; Bernard, A; Roels, H A; Buchet, J P; Viau, C

    1984-01-01

    In workers chronically exposed to cadmium and without signs of renal insufficiency, plasma proteins with molecular weight ranging from 11,800 to 450,000 are excreted in greater amount in urine. Increased urinary excretion of low and high molecular weight proteins can occur independently. Because of its greater stability in urine and provided a sensitive immunological technique is used, the determination of retinol-binding protein is a more practical and reliable test of proximal tubular function than beta 2-microglobulin. The evaluation of renal function of workers removed from cadmium exposure indicates that cadmium-induced renal lesions, albeit of slow progression, are not reversible when exposures ceases. In workers chronically exposed to cadmium or removed from cadmium exposure, metallothionein in urine is directly correlated with cadmium in urine but not with cadmium in blood or years of cadmium exposure. The association between cadmium in urine and metallothionein in urine is independent of the status of renal function and the intensity of current exposure to cadmium. Whereas the repeated IP injection of high doses of cadmium to rat gives rise to a mixed or tubular type proteinuria, the prolonged oral administration of cadmium results mainly in the development of a glomerular type proteinuria. The former is usually reversible after cessation of treatment whereas the latter is not. Circulating antiglomerular basement membrane antibodies have been found in man and in rat chronically exposed to cadmium. The pathogenic significance of this finding deserves further investigation. Images FIGURE 5. PMID:6376088

  8. Cadmium removal by Lemna minor and Spirodela polyrhiza.

    PubMed

    Chaudhuri, Devaleena; Majumder, Arunabha; Misra, Amal K; Bandyopadhyay, Kaushik

    2014-01-01

    The present study investigates the ability of two genus of duckweed (Lemna minor and Spirodela polyrhiza) to phytoremediate cadmium from aqueous solution. Duckweed was exposed to six different cadmium concentrations, such as, 0.5,1.0,1.5, 2.0, 2.5, and 3.0 mg/L and the experiment was continued for 22 days. Water samples were collected periodically for estimation of residual cadmium content in aqueous solution. At the end of treatment period plant samples were collected and accumulated cadmium content was measured. Cadmium toxicity was observed through relative growth factor and changes in chlorophyll content Experimental results showed that Lemna minor and Spirodela polyrhiza were capable of removing 42-78% and 52-75% cadmium from media depending upon initial cadmium concentrations. Cadmium was removed following pseudo second order kinetic model Maximum cadmium accumulation in Lemna minor was 4734.56 mg/kg at 2 mg/L initial cadmium concentration and 7711.00 mg/kg in Spirodela polyrhiza at 3 mg/L initial cadmium concentration at the end of treatment period. Conversely in both cases maximum bioconcentration factor obtained at lowest initial cadmium concentrations, i.e., 0.5 mg/L, were 3295.61 and 4752.00 for Lemna minor and Spirodela polyrhiza respectively. The present study revealed that both Lemna minor and Spirodela polyrhiza was potential cadmium accumulator. PMID:24933906

  9. Cigarette Smoke Cadmium Breakthrough from Traditional Filters: Implications for Exposure

    PubMed Central

    Pappas, R. Steven; Fresquez, Mark R.; Watson, Clifford H.

    2015-01-01

    Cadmium, a carcinogenic metal, is highly toxic to renal, skeletal, nervous, respiratory, and cardiovascular systems. Accurate and precise quantification of mainstream smoke cadmium levels in cigarette smoke is important because of exposure concerns. The two most common trapping techniques for collecting mainstream tobacco smoke particulate for analysis are glass fiber filters and electrostatic precipitators. We observed that a significant portion of total cadmium passed through standard glass fiber filters that are used to trap particulate matter. We therefore developed platinum traps to collect the cadmium that passed through the filters and tested a variety of cigarettes with different physical parameters for quantities of cadmium that passed though the filters. We found less than 1% cadmium passed through electrostatic precipitators. In contrast, cadmium that passed through 92 mm glass fiber filters on a rotary smoking machine was significantly higher, ranging from 3.5% to 22.9% of total smoke cadmium deliveries. Cadmium passed through 44 mm filters typically used on linear smoking machines to an even greater degree, ranging from 13.6% to 30.4% of the total smoke cadmium deliveries. Differences in the cadmium that passed through from the glass fiber filters and electrostatic precipitator could be explained in part if cadmium resides in the smaller mainstream smoke aerosol particle sizes. Differences in particle size distribution could have toxicological implications and could help explain the pulmonary and cardiovascular cadmium uptake in smokers. PMID:25313385

  10. Plasmonic characterization of photo-induced silver nanoparticles extracted from silver halide based TEM film

    NASA Astrophysics Data System (ADS)

    Sudheer, Tiwari, P.; Varshney, G. K.; Rai, V. N.; Srivastava, A. K.

    2016-05-01

    The plasmonic responses of silver nanoparticles extracted from silver halide based electron microscope film are investigated. Photo-reduction process is carried out to convert the silver halide grains into the metallic silver. The centrifuge technique is used for separating the silver nanoparticles from the residual solution. Morphological study performed by field emission scanning electron microscope (FESEM) shows that all the nanoparticles have an average diameter of ~120 nm with a high degree of mono dispersion in size. The localized surface plasmon resonance (LSPR) absorption peak at ~537 nm confirms the presence of large size silver nanoparticles.

  11. Engineering-Scale Liquid Cadmium Cathode Experiments

    SciTech Connect

    D Vaden; B. R. Westphal; S. X. Li; T. A. Johnson; K. B. Davies; D. M. Pace

    2006-08-01

    Recovery of transuranic actinides (TRU) using electrorefining is a process being investigated as part of the Department of Energy (DOE) Advanced Fuel Cycle Initiative (AFCI). TRU recovery via electrorefining onto a solid cathode is very difficult as the thermodynamic properties of transuranics are not favourable for them to remain in the metal phase while significant quantities of uranium trichloride exist in the electrolyte. Theoretically, the concentration of transuranics in the electrolyte must be approximately 106 greater than the uranium concentration in the electrolyte to produce a transuranic deposit on a solid cathode. Using liquid cadmium as a cathode contained within a LiCl-KCl eutectic salt, the co-deposition of uranium and transuranics is feasible because the activity of the transuranics in liquid cadmium is very small. Depositing transuranics and uranium in a liquid cadmium cathode (LCC) theoretically requires the concentration of transuranics to be two to three times the uranium concentration in the electrolyte. Three LCC experiments were performed in an Engineering scale elecdtrorefiner, which is located in the argon hot cell of the Fuel Conditioning Facility at the Materials and Fuels Complex on the Idaho National Laboratory. Figure 1 contains photographs of the LCC assembly in the hot cell prior to the experiment and a cadmium ingot produced after the first LCC test. Figure 1. Liquid Cadmium Cathode (left) and Cadmium Ingot (right) The primary goal of the engineering-scale liquid cadmium cathode experiments was to electrochemically collect kilogram quantities of uranium and plutonium via a LCC. The secondary goal was to examine fission product contaminations in the materials collected by the LCC. Each LCC experiment used chopped spent nuclear fuel from the blanket region of the Experimental Breeder Reactor II loaded into steel baskets as the anode with the LCC containing 26 kg of cadmium metal. In each experiment, between one and two kilograms of

  12. Telomerization of amino acids with butadiene, catalyzed by palladium complexes

    SciTech Connect

    Dzhemilev, U.M.; Fakhretdinov, R.N.; Telin, A.G.

    1987-01-10

    The telomerization of ..cap alpha..-, ..beta..-, ..gamma..-, and epsilon-amino acids having various structures with butadiene under the influence of the three-component palladium catalyst Pd(acac)/sub 2/-PPh/sub 3/-AlEt/sub 3/ was investigated in DMSO-toluene solution. The ..cap alpha..- and epsilon-aliphatic and also the ..cap alpha..-, ..beta..-, and ..gamma..-aromatic amino acids react with butadiene, giving the products from octadienylation at the amino group exclusively. Under the conditions of telomerization aliphatic ..beta..-amino acids are cleaved with the formation of unsaturated tertiary amines. In the case of aliphatic ..gamma..-amino acids it is possible to obtain telomers alkylated at the carbonyl group.

  13. Ozone Sensing Based on Palladium Decorated Carbon Nanotubes

    PubMed Central

    Colindres, Selene Capula; Aguir, Khalifa; Sodi, Felipe Cervantes; Vargas, Luis Villa; Moncayo Salazar, José A.; Febles, Vicente Garibay

    2014-01-01

    Multiwall carbon nanotubes (MWCNTs) were easily and efficiently decorated with Pd nanoparticles through a vapor-phase impregnation-decomposition method starting from palladium acetylacetonates. The sensor device consisted on a film of sensitive material (MWCNTs-Pd) deposited by drop coating on platinum interdigitated electrodes on a SiO2 substrate. The sensor exhibited a resistance change to ozone (O3) with a response time of 60 s at different temperatures and the capability of detecting concentrations up to 20 ppb. The sensor shows the best response when exposed to O3 at 120 °C. The device shows a very reproducible sensor performance, with high repeatability, full recovery and efficient response. PMID:24736133

  14. COMPARATIVE CORROSION BEHAVIOR OF TWO PALLADIUM CONTAINING TITANIUM ALLOYS

    SciTech Connect

    T. Lian, T. Yashiki, T. Nakayama, T. Nakanishi, R. B. Rebak

    2006-07-23

    The ASTM standard B 265 provides the requirements for the chemical composition of titanium (Ti) alloys. It is planned to use corrosion resistant and high strength titanium alloys to fabricate the drip shield at the proposed Yucca Mountain Repository. Titanium grade (Gr) 7 (R52400) and other Ti alloys are currently being characterized for this application. Ti Gr 7 contains 0.15% Palladium (Pd) to increase its corrosion performance. In this article we report results on the comparative short term corrosion behavior of Ti Gr 7 and a Ruthenium (Ru) containing alloy (Ti Gr 33). Ti Gr 33 also contains a small amount of Pd. Limited electrochemical testing such as polarization resistance and cyclic potentiodynamic curves showed that both alloys have a similar corrosion behavior in the tested environments.

  15. Comparative Corrosion Behavior of Two Palladium Containing Titanium Alloys

    SciTech Connect

    Lian, T; Yashiki, T; Nakayama, T; Nakanishi, T; Rebak, R B

    2006-02-05

    The ASTM standard B 265 provides the requirements for the chemical composition of titanium (Ti) alloys. It is planned to use corrosion resistant and high strength titanium alloys to fabricate the drip shield at the proposed Yucca Mountain Repository. Titanium grade (Gr) 7 (R52400) and other Ti alloys are currently being characterized for this application. Ti Gr 7 contains 0.15% Palladium (Pd) to increase its corrosion performance. In this article we report results on the comparative short term corrosion behavior of Ti Gr 7 and a Ruthenium (Ru) containing alloy (Ti Gr 33). Ti Gr 33 also contains a small amount of Pd. Limited electrochemical testing such as polarization resistance and cyclic potentiodynamic curves showed that both alloys have a similar corrosion behavior in the tested environments.

  16. Bio‐palladium: from metal recovery to catalytic applications

    PubMed Central

    De Corte, Simon; Hennebel, Tom; De Gusseme, Bart; Verstraete, Willy; Boon, Nico

    2012-01-01

    Summary While precious metals are available to a very limited extent, there is an increasing demand to use them as catalyst. This is also true for palladium (Pd) catalysts and their sustainable recycling and production are required. Since Pd catalysts exist nowadays mostly under the form of nanoparticles, these particles need to be produced in an environment‐friendly way. Biological synthesis of Pd nanoparticles (‘bio‐Pd’) is an innovative method for both metal recovery and nanocatalyst synthesis. This review will discuss the different bio‐Pd precipitating microorganisms, the applications of the catalyst (both for environmental purposes and in organic chemistry) and the state of the art of the reactors based on the bio‐Pd concept. In addition, some main challenges are discussed, which need to be overcome in order to create a sustainable nanocatalyst. Finally, some outlooks for bio‐Pd in environmental technology are presented. PMID:21554561

  17. Optical absorption spectra of palladium doped gold cluster cations

    SciTech Connect

    Kaydashev, Vladimir E.; Janssens, Ewald Lievens, Peter

    2015-01-21

    Photoabsorption spectra of gas phase Au{sub n}{sup +} and Au{sub n−1}Pd{sup +} (13 ≤ n ≤ 20) clusters were measured using mass spectrometric recording of wavelength dependent Xe messenger atom photodetachment in the 1.9–3.4 eV photon energy range. Pure cationic gold clusters consisting of 15, 17, and 20 atoms have a higher integrated optical absorption cross section than the neighboring sizes. It is shown that the total optical absorption cross section increases with size and that palladium doping strongly reduces this cross section for all investigated sizes and in particular for n = 14–17 and 20. The largest reduction of optical absorption upon Pd doping is observed for n = 15.

  18. Spectroscopic study of low-temperature hydrogen absorption in palladium

    SciTech Connect

    Ienaga, K. Takata, H.; Onishi, Y.; Inagaki, Y.; Kawae, T.; Tsujii, H.; Kimura, T.

    2015-01-12

    We report real-time detection of hydrogen (H) absorption in metallic palladium (Pd) nano-contacts immersed in liquid H{sub 2} using inelastic electron spectroscopy (IES). After introduction of liquid H{sub 2}, the spectra exhibit the time evolution from the pure Pd to the Pd hydride, indicating that H atoms are absorbed in Pd nano-contacts even at the temperature where the thermal process is not expected. The IES time and bias voltage dependences show that H absorption develops by applying bias voltage 30 ∼ 50 mV, which can be explained by quantum tunneling. The results represent that IES is a powerful method to study the kinetics of high density H on solid surface.

  19. Spectroscopic study of low-temperature hydrogen absorption in palladium

    NASA Astrophysics Data System (ADS)

    Ienaga, K.; Takata, H.; Onishi, Y.; Inagaki, Y.; Tsujii, H.; Kimura, T.; Kawae, T.

    2015-01-01

    We report real-time detection of hydrogen (H) absorption in metallic palladium (Pd) nano-contacts immersed in liquid H2 using inelastic electron spectroscopy (IES). After introduction of liquid H2, the spectra exhibit the time evolution from the pure Pd to the Pd hydride, indicating that H atoms are absorbed in Pd nano-contacts even at the temperature where the thermal process is not expected. The IES time and bias voltage dependences show that H absorption develops by applying bias voltage 30 ˜ 50 mV, which can be explained by quantum tunneling. The results represent that IES is a powerful method to study the kinetics of high density H on solid surface.

  20. Comparative modelling of chemical ordering in palladium-iridium nanoalloys

    SciTech Connect

    Davis, Jack B. A.; Johnston, Roy L.; Rubinovich, Leonid; Polak, Micha

    2014-12-14

    Chemical ordering in “magic-number” palladium-iridium nanoalloys has been studied by means of density functional theory (DFT) computations, and compared to those obtained by the Free Energy Concentration Expansion Method (FCEM) using derived coordination dependent bond energy variations (CBEV), and by the Birmingham Cluster Genetic Algorithm using the Gupta potential. Several compositions have been studied for 38- and 79-atom particles as well as the site preference for a single Ir dopant atom in the 201-atom truncated octahedron (TO). The 79- and 38-atom nanoalloy homotops predicted for the TO by the FCEM/CBEV are shown to be, respectively, the global minima and competitive low energy minima. Significant reordering of minima predicted by the Gupta potential is seen after reoptimisation at the DFT level.

  1. Fabrication of Phenanthroline Modified Graphene Nanosheets Decorated with Palladium Nanoparticles.

    PubMed

    Lingappan, Niranjanmurthi; Kim, Do Hoon; Park, Chan; Gal, Yeong-Soon; Lim, Kwon Taek

    2015-01-01

    Palladium nanoparticles decorated modified reduced graphene oxide (RGO) composite was synthesized by a two-step process using 1,10-Phenanthroline (PHEN) as bridging agent. Firstly, the graphene oxide (GO) was non-covalently modified with the PHEN molecules through π-π interaction between two components. Then, the modified GO was complexed with Pd precursor and subsequently reduced from Pd2+ to Pd0 using NaBH4 to yield Pd dispersed modified RGO sheets. The structure and morphology of the resulting composites were characterized by FTIR, TGA, EDX, FESEM, HRTEM and XRD measurements. XPS results revealed that the reduction of Pd2+ to metal-lic Pd was successfully achieved, while the HRTEM and FESEM micrographs suggested that the Pd nanoparticles were well-dispersed on the functionalized graphene sheets.

  2. Water-soluble colorimetric and ratiometric fluorescent probe for selective imaging of palladium species in living cells.

    PubMed

    Liu, Wei; Jiang, Jie; Chen, Chunyang; Tang, Xiaoliang; Shi, Jinmin; Zhang, Peng; Zhang, Kaiming; Li, Zhiqi; Dou, Wei; Yang, Lizi; Liu, Weisheng

    2014-12-01

    A novel water-soluble colorimetric and ratiometric fluorescent probe was synthesized and applied to imaging palladium species under physiological conditions in phosphate buffered saline (PBS) containing less than 1% organic cosolvent without adding any additional reagents. Based on palladium triggered terminal propargyl ethers cleavage reaction, the probe exhibited a high selectivity and sensitivity for palladium species of all the typical oxidation states (0, +2, +4), with a low detection limit (25 nM, 2.7 μg/L) and an obvious color change. Furthermore, the probe was successfully used for ratiometric fluorescence imaging of palladium in living cells.

  3. Selective hydrogenation of phenylacetylene on pumice-supported palladium catalysts

    SciTech Connect

    Duca, D; Liotta, L.F.; Deganello, G.

    1995-06-01

    The liquid phase, selective hydrogenation of phenylacetylene on pumice-supported palladium catalysts has been studied for a large range of metallic dispersions (14% {le} D{sub x} {le} 62%). The kinetics were analyzed by a five-parameter mathematical model. The mechanism was determined by the contribution of three basic routes involving only surface species in the rate-determining steps. The hydrogenation of phenylacetylene to styrene is {open_quotes}structure insensitive{close_quotes}. The disappearance rate constant of styrene produced from phenylacetylene is slightly lower than that of phenylacetylene and does not change in the case of the direct hydrogenation of styrene on the same Pd/pumice catalyst. However, Q{sub 3} (the ratio of adsorption constants K{sub Eb}/K{sub St}, where Eb is ethylbenzene and St is styrene), which is typical of a zero-order reaction (Q{sub 3}{r_arrow}0) in the case of the direct hydrogenation, is practically constant (Q{sub 3}{approx_equal}2) in the case of dehydrogenation of styrene produced from phenylacetylene. This is explained by the formation, in the latter case, of polymeric species or other species which are difficult to hydrogenate and by the consequent occupation of active sites so that the adsorption of styrene is inhibited. These species are also thought to be responsible for a flattening effect in the catalytic activity. Activity and selectivity data are critically analyzed and compared with those reported for other supported palladium catalysts. Since Pd/pumice catalysts also show high activity and selectivity at high metal dispersions, they could be of interest for industrial applications. 48 refs., 9 figs., 3 tabs.

  4. Palladium-modified aluminide coatings: Mechanisms of formation

    SciTech Connect

    Lamesle, P.; Steinmetz, P.; Steinmetz, J.; Alperine, S.

    1995-02-01

    The need to increase the efficiency of turbo engines has led manufacturers to increase the temperature of gases at the exhaust of the combustion chamber. Another limiting factor for the lifetime of blades or vanes used in gas turbines is hot corrosion due to the condensation of alkaline sulfate produced by the oxidation of sulfur contained in kerosene or fuels. To overcome these problems, the use of protective coatings has come into general use. A systematic investigation of the influence of Pd-Ni predeposit alloys on the microstructure and composition of aluminum diffusion coatings has been conducted on Ni base superalloys (mainly IN738). Their metallurgical structure has been studied with a special emphasis on the nature of the phases and distribution of the various elements throughout the coating section. A two-layer structure similar to that formed on simple aluminide coatings is observed whatever the type of aluminizing treatment (low and high aluminum activity, pack of vapor-phase coating). The superficial layer is, however, very different from that observed in simple aluminide coatings, since it is constituted with a ternary PdNi aluminide. Palladium concentration profiles, which significantly differ when using low or high activity cements, and the results of a study of the ternary Ni-Pd-Al phase diagram, provide qualitative indications concerning the coatings` growth processes. Palladium, if present at a sufficient level, enhances Al diffusion in the beta phase. In the case of low activity processes, a consequence of this increase of Al diffusion flux is the location of an NiAl reaction zone inside the coating.

  5. Palladium complexes with simple iminopyridines as catalysts for polyketone synthesis.

    PubMed

    Rosar, V; Dedeic, D; Nobile, T; Fini, F; Balducci, G; Alessio, E; Carfagna, C; Milani, B

    2016-10-01

    Four iminopyridines (N-N') differing in the nature of the substituents on the iminic carbon and on the ortho positions of the aryl ring (H or CH3) on the iminic nitrogen were used for the synthesis of neutral and monocationic palladium(ii) complexes of general formulae [Pd(CH3)Cl(N-N')] and [Pd(CH3)(NCCH3)(N-N')][PF6]. The detailed NMR characterization in solution highlighted that: (i) for both series of complexes, the Pd-CH3 signal is progressively shifted to a lower frequency on increasing the number of methyl groups on the ligand skeleton; (ii) for the neutral derivatives, the chemical shift of the (15)N NMR signals, determined through {(1)H,(15)N}-HMBC spectra, is significantly affected by the coordination to palladium; (iii) the coordination induced shift (CIS) of the nitrogen atom trans to the CH3 ligand is smaller than the other. The structure in the solid state for the neutral derivatives with all the four ligands was solved, pointing out that: (iv) the Pd-C bond distance increases with the basicity of the nitrogen-donor ligand; (v) the Pd-N bond distance correlates well with the CIS value. The combining of the solution and solid state structural features allows stating that: (vi) the Pd-CH3 singlet is a good probe for the electron donor capability of the ligand; (vii) the CIS value might be used as a probe for the strength of the Pd-N bond. All monocationic complexes generated active catalysts for the CO/vinyl arene copolymerization, leading to prevailingly syndiotactic polyketones. The catalyst performances, both in terms of catalyst productivity and polymer molecular weight, correlate well with the precatalyst structural features. PMID:27604383

  6. Effect of nano silver and silver nitrate on seed yield of (Ocimum basilicum L.)

    PubMed Central

    2014-01-01

    Background The aim of this study was to evaluate the effect of nano silver and silver nitrate on yield of seed in basil plant. The study was carried out in a randomized block design with three replications. Results Four levels of either silver nitrate (0, 100, 200 and 300 ppm) or nano silver (0, 20, 40, and 60 ppm) were sprayed on basil plant at seed growth stage. The results showed that there was no significant difference between 100 ppm of silver nitrate and 60 ppm concentration of nano silver on the shoot silver concentration. However, increasing the concentration of silver nitrate from 100 to 300 ppm caused a decrease in seed yield. In contrast, a raise in the concentration of nano silver from 20 to 60 ppm has led to an improvement in the seed yield. Additionally, the lowest amount of seed yield was found with control plants. Conclusions Finally, with increasing level of silver nitrate, the polyphenol compound content was raised but the enhancing level of nano silver resulting in the reduction of these components. In conclusion, nano silver can be used instead of other compounds of silver. PMID:25383311

  7. Cadmium exposure induces hematuria in Korean adults

    SciTech Connect

    Han, Seung Seok; Kim, Myounghee; Lee, Su Mi; Lee, Jung Pyo; Kim, Sejoong; Joo, Kwon Wook; Lim, Chun Soo; Kim, Yon Su; Kim, Dong Ki

    2013-07-15

    Introduction: Toxic heavy metals have adverse effects on human health. However, the risk of hematuria caused by heavy metal exposure has not been evaluated. Methods: Data from 4701 Korean adults were obtained in the Korean National Health and Nutritional Examination Survey (2008–2010). Blood levels of the toxic heavy metals cadmium, lead, and mercury were measured. Hematuria was defined as a result of ≥+1 on a urine dipstick test. The odds ratios (ORs) for hematuria were measured according to the blood heavy metal levels after adjusting for multiple variables. Results: Individuals with blood cadmium levels in the 3rd and 4th quartiles had a greater OR for hematuria than those in the 1st quartile group: 3rd quartile, 1.35 (1.019–1.777; P=0.037); 4th quartile, 1.52 (1.140–2.017; P=0.004). When blood cadmium was considered as a log-transformed continuous variable, the correlation between blood cadmium and hematuria was significant: OR, 1.97 (1.224–3.160; P{sub trend}=0.005). In contrast, no significant correlations between hematuria and blood lead or mercury were found in the multivariate analyses. Discussion: The present study shows that high cadmium exposure is associated with a risk of hematuria. -- Highlights: • A high level of blood cadmium is associated with a high risk of hematuria. • This correlation is independent of several confounding factors. • Blood levels of lead and mercury are not associated with risk of hematuria. • This is the first study on the correlation between cadmium exposure and hematuria risk.

  8. Toxicity of cadmium to the developing lung

    SciTech Connect

    Daston, G.P.

    1981-01-01

    The effects of cadmium on the developing lung and pulmonary surfactant were studied. Pregnant rats received subcutaneous injections of cadmium chloride on days 12 to 15 of gestation and were sacrificed throughout late gestation. The treatment resulted in high embryonic mortality and growth regardation. Fetal lung weight was reduced 20 to 30% due to hypoplasia, as the number of lung cells (DNA/lung) but not cell size (protein/cell) was lowered. The ultrastructural development of alveolar epithelium was altered; cytodifferentiation was delayed; and the cytoplasmic inclusions which contain pulmonary surfactant, were reduced in the term fetus. Accumulation of phosphatidylcholine (PC), the major component of pulmonary surfactant, was diminished in the lungs of treated fetuses. The immediate cause of this lowered accumulation was a decreased rate of synthesis of PC from choline. Carbohydrates probably represent a major source of PC precursors and are present in large quantities in the fetal lung as glycogen. The pulmonary glycogen content of cadmium-exposed fetuses was diminished. It is postulated that this is a reason for the lowered rate of PC synthesis. Maternally administered cadmium did not pass through the placenta; thus, the mechanism of fetotoxicity was indirect. Maternal cadmium exposure did result in lowered fetal zinc levels. Coadministration of zinc with cadmium raised fetal zinc concentration to control values and alleviated all fetotoxicity. Fetal zinc deficiency is a possible mechanism for the toxic effects on the developing lung. Several dams were allowed to give birth and their offspring were observed for respiratory problems. Cadmium treatment delayed parturition by about a day. Symptoms of respiratory distress syndrome (RDS) were observed in 11% of the treated neonates. All but one of these individuals died and had lungs with hyaline membranes. This is the only known case of an environmental agent causing neonatal RDS.

  9. Hazards to wildlife from soil-borne cadmium reconsidered

    USGS Publications Warehouse

    Beyer, W.N.

    2000-01-01

    Cadmium is a toxic element that should be included in environmental risk assessments of contaminated soils. This paper argues, however, that hazards to wildlife from cadmium have often been overstated. The literature contains only meager evidence that wild animals have been seriously harmed by cadmium, even at severely contaminated sites. Although some researchers have reported that wildlife have accumulated concentrations of cadmium in their kidneys that were above suggested injury thresholds, the thresholds may be disputed, since they were well below the World Health Organization criterion of 200 mg/kg (wet weight) of cadmium in the renal cortex for protecting human health. Recent risk assessments have concluded that soil cadmium concentrations less than 1 mg/kg are toxic to soil organisms and wildlife, which implies that background concentrations of cadmium naturally found in soils are hazardous. An examination of the databases used to support these assessments suggested that the toxicity of cadmium has been exaggerated.

  10. SUBSTITUTION OF CADMIUM CYANIDE ELECTROPLATING WITH ZINC CHLORIDE ELECTROPLATING

    EPA Science Inventory

    The study evaluated the zinc chloride electroplating process as a substitute for cadmium cyanide electroplating in the manufacture of industrial connectors and fittings at Aeroquip Corporation. The process substitution eliminates certain wastes, specifically cadmium and cyanide, ...

  11. Contemporary anthropogenic silver cycle: a multilevel analysis.

    PubMed

    Johnson, Jeremiah; Jirikowic, Julie; Bertram, Marlen; van Beers, D; Gordon, R B; Henderson, Kathryn; Klee, R J; Lanzano, Ted; Lifset, R; Oetjen, Lucia; Graedel, T E

    2005-06-15

    Anthropogenic cycling of silver in 1997 is presented using three discrete governmental units: 64 countries encompassing what we believe to be over 90% of global silver flows, 9 world regions, and the entire planet. Using material flow analysis (MFA) techniques, the country level cycles are aggregated to produce the regional cycles, which are used to form a "best estimate" global cycle. Interesting findings include the following: (1) several silver-mining countries export ore and concentrate but also import silver-containing semiproducts and products; (2) the level of development for a country, as indicated by the gross domestic product, is a fair indicator of silver use, but several significant outliers exist; (3) the countries with the greatest mine production include Mexico, the United States, Peru, and China, whereas the United States, Japan, India, Germany, and Italy lead in the fabrication and manufacture of products; (4) North America and Europe's use of silver products exceed that of other regions on a per capita basis; (5) global silver discards, including tailings and separation waste, totaled approximately 57% of the silver mined; (6) approximately 57% of the silver entering waste management globally is recycled; and (7) the amount of silver entering landfills globally is comparable to the amount found in tailings. The results of this MFA lay the basis for further analysis, which in turn can offer insight into natural resource policy, the characterization of environmental impact, and better resource management.

  12. Contemporary anthropogenic silver cycle: a multilevel analysis.

    PubMed

    Johnson, Jeremiah; Jirikowic, Julie; Bertram, Marlen; van Beers, D; Gordon, R B; Henderson, Kathryn; Klee, R J; Lanzano, Ted; Lifset, R; Oetjen, Lucia; Graedel, T E

    2005-06-15

    Anthropogenic cycling of silver in 1997 is presented using three discrete governmental units: 64 countries encompassing what we believe to be over 90% of global silver flows, 9 world regions, and the entire planet. Using material flow analysis (MFA) techniques, the country level cycles are aggregated to produce the regional cycles, which are used to form a "best estimate" global cycle. Interesting findings include the following: (1) several silver-mining countries export ore and concentrate but also import silver-containing semiproducts and products; (2) the level of development for a country, as indicated by the gross domestic product, is a fair indicator of silver use, but several significant outliers exist; (3) the countries with the greatest mine production include Mexico, the United States, Peru, and China, whereas the United States, Japan, India, Germany, and Italy lead in the fabrication and manufacture of products; (4) North America and Europe's use of silver products exceed that of other regions on a per capita basis; (5) global silver discards, including tailings and separation waste, totaled approximately 57% of the silver mined; (6) approximately 57% of the silver entering waste management globally is recycled; and (7) the amount of silver entering landfills globally is comparable to the amount found in tailings. The results of this MFA lay the basis for further analysis, which in turn can offer insight into natural resource policy, the characterization of environmental impact, and better resource management. PMID:16047806

  13. Surface enhanced Raman scattering of new acridine based fluorophore adsorbed on silver electrode.

    PubMed

    Solovyeva, Elena V; Myund, Liubov A; Denisova, Anna S

    2015-10-01

    4,5-Bis(N,N-di(2-hydroxyethyl)iminomethyl)acridine (BHIA) is a new acridine based fluoroionophore and a highly-selective sensor for cadmium ion. The direct interaction of the aromatic nitrogen atom with a surface is impossible since there are bulky substituents in the 4,5-positions of the acridine fragment. Nevertheless BHIA molecule shows a reliable SERS spectrum while adsorbed on a silver electrode. The analysis of SERS spectra pH dependence reveals that BHIA species adsorbed on a surface can exist in both non-protonated and protonated forms. The adsorption of BHIA from alkaline solution is accompanied by carbonaceous species formation at the surface. The intensity of such "carbon bands" turned out to be related with the supporting electrolyte (KCl) concentration. Upon lowering the electrode potential the SERS spectra of BHIA do not undergo changes but the intensity of bands decreases. This indicates that the adsorption mechanism on the silver surface is realized via aromatic system of acridine fragment. In case of such an adsorption mechanism the chelate fragment of the BHIA molecule is capable of interaction with the solution components. Addition of Cd(2+) ions to a system containing BHIA adsorbed on a silver electrode in equilibrium with the solution leads to the formation of BHIA/Cd(2+) complex which desorption causes the loss of SERS signal. PMID:25956332

  14. An ultrasensitive label-free electrochemical immunosensor based on signal amplification strategy of multifunctional magnetic graphene loaded with cadmium ions

    PubMed Central

    Li, Faying; Li, Yueyun; Dong, Yunhui; Jiang, Liping; Wang, Ping; Liu, Qing; Liu, Hui; Wei, Qin

    2016-01-01

    Herein, a novel and ultrasensitive label-free electrochemical immunosensor was proposed for quantitative detection of human Immunoglobulin G (IgG). The amino functionalized magnetic graphenes nanocomposites (NH2-GS-Fe3O4) were prepared to bond gold and silver core-shell nanoparticles (Au@Ag NPs) by constructing stable Au-N and Ag-N bond between Au@Ag NPs and -NH2. Subsequently, the Au@Ag/GS-Fe3O4 was applied to absorb cadmium ion (Cd2+) due to the large surface area, high conductivity and exceptional adsorption capability. The functional nanocomposites of gold and silver core-shell magnetic graphene loaded with cadmium ion (Au@Ag/GS-Fe3O4/Cd2+) can not only increase the electrocatalytic activity towards hydrogen peroxide (H2O2) but also improve the effective immobilization of antibodies because of synergistic effect presented in Au@Ag/GS-Fe3O4/Cd2+, which greatly extended the scope of detection. Under the optimal conditions, the proposed immunosensor was used for the detection of IgG with good linear relation in the range from 5 fg/mL to 50 ng/mL with a low detection limit of 2 fg/mL (S/N = 3). Furthermore, the proposed immunosensor showed high sensitivity, special selectivity and long-term stability, which had promising application in bioassay analysis. PMID:26880596

  15. Ultrafast electronic relaxation processes in semiconductor nanoparticles (silver iodide, silver iodide/silver sulfide, silver bromide/silver sulfide, silver sulfide, cupric sulfide, and copper sulfide) and carotenoids

    NASA Astrophysics Data System (ADS)

    Brelle, Michael Chris

    2000-11-01

    This dissertation examines primarily the ultrafast dynamics of excited state charge carriers in semiconductor nanoparticles. The dissertation also briefly examines the excited state lifetimes of a few carotenoids. Understanding the dynamic properties of charge carriers in semiconductor nanoparticles is crucial for the further development of applications utilizing these systems. The dynamic properties including shallow and deep trapping as well as recombination have been studied in a variety of semiconductor nanoparticle systems. Kinetic modeling was utilized to assist in the assignment of all observed signals and the nature of the decays. The first observation of ultrafast trapping in silver halides was observed in AgI nanoparticles including the identification that interstitial silver ions may act as deep traps. Several interesting phenomena were observed in Ag2S and CuxS nanoparticles including dark shallow trap states and shallow trap state saturation leading to increased transient absorption over transient bleach with increasing excitation intensity. These observations have provided further insight into the relaxation pathways for charge carriers in semiconductor nanoparticle systems. Lifetimes of the S2 excited states of four carotenoids have also been determined. The S2 lifetime for beta-carotene was confirmed from previous fluorescence up-conversion experiments whereas the S2 lifetimes that were previously unknown for three carotenoids, violaxanthin, neaxanthin, and lutein were discovered. These experiments together demonstrate the capabilities of femtosecond pump-probe spectroscopy to characterize and better understand the processes involved in the ultrafast relaxation events in both molecular and nanoparticle systems.

  16. Process for thin film deposition of cadmium sulfide

    DOEpatents

    Muruska, H. Paul; Sansregret, Joseph L.; Young, Archie R.

    1982-01-01

    The present invention teaches a process for depositing layers of cadmium sulfide. The process includes depositing a layer of cadmium oxide by spray pyrolysis of a cadmium salt in an aqueous or organic solvent. The oxide film is then converted into cadmium sulfide by thermal ion exchange of the O.sup.-2 for S.sup.-2 by annealing the oxide layer in gaseous sulfur at elevated temperatures.

  17. The chemical status of cadmium ion in the placenta. [Mice

    SciTech Connect

    Hanlon, D.P.; Specht, C.; Ferm, V.H.

    1982-02-01

    The chemical status of cadmium ion in the chorioallantoic and yolk sac placentas of SWV strain mice during the critical phase of embryonic organogenesis was investigated. Twenty-four hours after a single teratogenic dose of cadmium ion, both placentas contained significant amounts of a macromolecular chelator. Gel filtration data and disc electrophoresis data suggest that the cadmium-binding macromolecule of the chorioallantois (which binds 61% of the cadmium ion content of the tissues) is a metallothionein dimer.

  18. Low-temperature solution processing of palladium/palladium oxide films and their pH sensing performance.

    PubMed

    Qin, Yiheng; Alam, Arif U; Pan, Si; Howlader, Matiar M R; Ghosh, Raja; Selvaganapathy, P Ravi; Wu, Yiliang; Deen, M Jamal

    2016-01-01

    Highly sensitive, easy-to-fabricate, and low-cost pH sensors with small dimensions are required to monitor human bodily fluids, drinking water quality and chemical/biological processes. In this study, a low-temperature, solution-based process is developed to prepare palladium/palladium oxide (Pd/PdO) thin films for pH sensing. A precursor solution for Pd is spin coated onto pre-cleaned glass substrates and annealed at low temperature to generate Pd and PdO. The percentages of PdO at the surface and in the bulk of the electrodes are correlated to their sensing performance, which was studied by using the X-ray photoelectron spectroscope. Large amounts of PdO introduced by prolonged annealing improve the electrode's sensitivity and long-term stability. Atomic force microscopy study showed that the low-temperature annealing results in a smooth electrode surface, which contributes to a fast response. Nano-voids at the electrode surfaces were observed by scanning electron microscope, indicating a reason for the long-term degradation of the pH sensitivity. Using the optimized annealing parameters of 200°C for 48 h, a linear pH response with sensitivity of 64.71±0.56 mV/pH is obtained for pH between 2 and 12. These electrodes show a response time shorter than 18 s, hysteresis less than 8 mV and stability over 60 days. High reproducibility in the sensing performance is achieved. This low-temperature solution-processed sensing electrode shows the potential for the development of pH sensing systems on flexible substrates over a large area at low cost without using vacuum equipment.

  19. Toxicogenomic responses of nanotoxicity in Daphnia magna exposed to silver nitrate and coated silver nanoparticles

    EPA Science Inventory

    Applications for silver nanomaterials in consumer products are rapidly expanding, creating an urgent need for toxicological examination of the exposure potential and ecological effects of silver nanoparticles (AgNPs). The integration of genomic techniques into environmental toxic...

  20. Aquatic Toxicity Comparison of Silver Nanoparticles and Silver Nanowires.

    PubMed

    Sohn, Eun Kyung; Johari, Seyed Ali; Kim, Tae Gyu; Kim, Jin Kwon; Kim, Ellen; Lee, Ji Hyun; Chung, Young Shin; Yu, Il Je

    2015-01-01

    To better understand the potential ecotoxicological impact of silver nanoparticles (AgNPs) and silver nanowires (AgNWs) released into freshwater environments, the toxicities of these nanomaterials were assessed and compared using Organization for Economic Cooperation and Development (OECD) test guidelines, including a "Daphnia sp., acute immobilization test," "Fish, acute toxicity test," and "freshwater alga and cyanobacteria, growth inhibition test." Based on the estimated median lethal/effective concentrations of AgNPs and AgNWs, the susceptibility to the nanomaterials was different among test organisms (daphnia > algae > fish), suggesting that the AgNPs are classified as "category acute 1" for Daphnia magna, "category acute 2" for Oryzias latipes, and "category acute 1" for Raphidocelis subcapitata, while the AgNWs are classified as "category acute 1" for Daphnia magna, "category acute 2" for Oryzias latipes, and "category acute 2" for Raphidocelis subcapitata, according to the GHS (Globally Harmonized System of Classification and Labelling of Chemicals). In conclusion, the present results suggest that more attention should be paid to prevent the accidental or intentional release of silver nanomaterials into freshwater aquatic environments. PMID:26125025