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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. 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.

  3. 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.

  4. 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.

  5. The mechanism of corrosion of palladium-silver binary alloys in artificial saliva.

    PubMed

    Joska, L; Marek, M; Leitner, J

    2005-05-01

    Palladium dental casting alloys are alternatives to gold alloys. The aim of this study was to determine the electrochemical behaviour and the corrosion mechanism of binary silver-palladium alloys. Seven binary silver-palladium alloys and pure palladium and silver were tested in a model saliva solution. Electrochemical tests included corrosion potential, polarization resistance, and potentiodynamic polarization measurements. The corrosion products, which may be theoretically formed, were determined by thermodynamic calculation. The behaviour of silver and silver-rich alloys was dominated by the preferential formation of a thiocyanate surface layer, which controlled the free corrosion potential. Palladium dissolved in the form of a thiocyanate complex, but the surface became passivated by either palladium oxide or solid palladium thiocyanate layer, the thermodynamic calculations indicating preference for the oxide. Palladium-rich alloys showed evidence of silver depletion of the surface, resulting in behaviour similar to palladium. Examination of binary silver-palladium alloys has made possible determination of the role of the components of the alloys and model saliva in the corrosion behaviour. The findings are applicable to the more complex commercial dental alloys containing silver and palladium as major components.

  6. Microstructure and segregation behavior of palladium in silver-copper-palladium alloys.

    PubMed

    Chen, K I; Lin, J H; Ju, C P

    1996-07-01

    It has been reported that the addition of palladium can modify the microstructure and improve the properties of Ag-Cu eutectic alloy as well as admixed Cu-rich amalgam. The purpose of this work was to study the microstructure and segregation behavior of palladium in a series of Ag-Cu-Pd alloys. All microstructural and microchemical results consistently indicated a strong tendency for palladium to form the ordered Cu3Pd superlattice in the copper-rich phase of the present ternary alloys. Transmission electron microscopic examination indicated that, in addition to the large Cu-rich particles, numerous small (typically tens of nanometers) Cu-rich particles were distributed in the Ag-rich phase. In the alloys containing 10 and 15 wt% Pd, the Cu3Pd superlattice had an L1(2)-type crystal structure. In the alloy containing 20 wt% Pd, the Cu3Pd had a periodic (regular) APB structure. The solubility of palladium in the Cu-rich phase was always much larger than that in the Ag-rich phase. The ratio of the palladium concentration in the copper-rich phase to that in the silver-rich phase decreased with the overall palladium content.

  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. Mechanical, electrical, and thermal expansion properties of carbon nanotube-based silver and silver-palladium alloy composites

    NASA Astrophysics Data System (ADS)

    Pal, Hemant; Sharma, Vimal

    2014-11-01

    The mechanical, electrical, and thermal expansion properties of carbon nanotube (CNT)-based silver and silver-palladium (10:1, w/w) alloy nanocomposites are reported. To tailor the properties of silver, CNTs were incorporated into a silver matrix by a modified molecular level-mixing process. CNTs interact weakly with silver because of their non-reactive nature and lack of mutual solubility. Therefore, palladium was utilized as an alloying element to improve interfacial adhesion. Comparative microstructural characterizations and property evaluations of the nanocomposites were performed. The structural characterizations revealed that decorated type-CNTs were dispersed, embedded, and anchored into the silver matrix. The experimental results indicated that the modification of the silver and silver-palladium nanocomposite with CNT resulted in increases in the hardness and Young's modulus along with concomitant decreases in the electrical conductivity and the coefficient of thermal expansion (CTE). The hardness and Young's modulus of the nanocomposites were increased by 30%-40% whereas the CTE was decreased to 50%-60% of the CTE of silver. The significantly improved CTE and the mechanical properties of the CNT-reinforced silver and silver-palladium nanocomposites are correlated with the intriguing properties of CNTs and with good interfacial adhesion between the CNTs and silver as a result of the fabrication process and the contact action of palladium as an alloying element.

  9. Electrothermal atomic absorption determination of silver in cadmium selenide

    SciTech Connect

    Khozhainov, Y.M.; Deinikina, N.P.; Tyurin, O.A.

    1985-10-01

    The authors developed an atomic absorption method for determining trace silver in cadmium selenide, restricted to samples of 3 - 10 mg. Used as cp reagents, including those further purified, were distilled nitric acid, isothermally distilled hydrochloric acid, cadmium selenide, and S /SUB r/ grade silver with a purity of 99.999%.

  10. Circular photogalvanic effect observed in silver-palladium film resistors

    NASA Astrophysics Data System (ADS)

    Mikheev, G. M.; Aleksandrov, V. A.; Saushin, A. S.

    2011-06-01

    The surface circular photogalvanic effect (CPGE) at a laser wavelength of 1064 nm was observed for the first time in silver-palladium resistors fabricated by a thick-film technology. The CPGE response was detected using the electrodes oriented parallel to the radiation incidence plane, for the laser beam obliquely incident onto the sample surface. The coefficient of the pulsed laser radiation power conversion into light-induced emf (with the polarity depending on the sign of the circular polarization) amounted to about 80 mV/MW for film dimensions of 0.02 × 20 × 20 mm and a load resistance of 50 Ω. The maximum absolute value of the conversion coefficient was observed for the angles of light incidence of ±60°.

  11. 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.

  12. Effects of cooling methods on silver-palladium castings.

    PubMed

    Jochen, D G; Caputo, A A; Matyas, J

    1988-03-01

    Cast metal specimens for three ceramic metals were subjected to two different types of cooling procedures after casting. One method involved the rapid cooling of the casting as soon as the red glow of the button disappeared. The other method allowed the castings to bench cool to room temperature. Hardness, bond strength, and microstructural determinations lead to the following conclusions. 1. Vickers hardness values for W-1 and Rx-91 alloys for each cooling regimen were not significantly different. Statistically higher hardness values were obtained for the quenched specimens of JP-5 alloys compared with the bench-cooled specimens. 2. Cooling of W-1 and JP-5 alloy specimens by quenching resulted in higher bond strengths than for specimens that were bench-cooled to room temperature. However, bench-cooling Rx-91 alloy lead to higher bond strengths than did quenching. 3. For all of the alloys examined, quenching produced a smaller grain structure than did bench-cooling. 4. From the standpoint of the parameters tested and the saving of processing time, quenching of the silver-palladium ceramic alloys examined is the cooling procedure of choice for W-1 and JP-5 alloys.

  13. 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...

  14. Thermodynamic properties of solid palladium-silver alloys and other alloys are investigated by torsion-effusion technique

    NASA Technical Reports Server (NTRS)

    Myles, K. M.

    1967-01-01

    Vapor pressure data obtained by the torsion-effusion method provides the thermodynamic properties of several transition-metal alloy systems. The vapor pressure of silver over solid silver and over palladium-silver alloys was measured and the results were more accurate than those found previously by other techniques.

  15. Production of Palladium-Silver Thin Film Alloys and Measurements of Phase Diagrams of the PALLADIUM(1-X)SILVER(X)HYDROGEN System.

    NASA Astrophysics Data System (ADS)

    Villalobos-Velasco, Jaime

    1988-06-01

    PdAg Alloy thin films of different compositions were fabricated by crosscondensation of two atomic fluxes on temperature controlled quartz crystal substrates. The fluxes were generated by thermal evaporation of pure materials produced by two electron-beam-guns (e-guns). The process took place under clean high vacuum conditions. Film thickness, growth rate and composition were precisely computer-controlled utilizing three quartz crystal mass monitors (QCM) and a combination of shutters. Criteria for quality of the films were accuracy and homogeneity of thickness and alloy composition. Hydrogen pressure and temperature were carefully controlled for the performance of the hydrogen cycling process in order to study the interaction of hydrogen with the metal alloy thin film structures. All process variables were automatically monitored and controlled to eliminate inaccuracies inherent in manual control. Software and hardware were developed for repeatability of the process parameters and variables to ensure reproduction of the evaporation and hydrogen-cycling processes. Phase diagrams consisting of pressure concentration relations from repeated hydrogen cycling processes were measured using the QCM technique. Results on palladium hydride obtained using the volumetric technique were combined with results from the QCM on similar systems for the development of an empirical method to extract the stress effect inherent in the QCM produced by the expansion of the volume of the palladium host lattice upon hydrogen adsorption. As a consequence bulk behavior of the phase diagrams for thin films thicker than 2500 A were predicted. The results describe the evolution of the phase diagrams of palladium thin films as their thicknesses approach bulk. The evolution of features of the phase diagrams as the incorporation of silver in the palladium host structure changes from 0 to 30% is also described. A reduction of the hydrogen solubility of the PdAg structure occurs as the silver

  16. 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.

  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. Effect of silver and palladium on dye-removal characteristics of anatase-titania nanotubes.

    PubMed

    Harsha, N; Ranya, R; Shukla, S; Biju, S; Reddy, M L P; Warrier, K G K

    2011-03-01

    Anatase-titania nanotubes have been synthesized via hydrothermal and surface-modified by depositing silver and palladium via ultraviolet-reduction method. The pure and surface-modified anatase-titania nanotubes have been characterized using the transmission electron microscope, selected-area electron diffraction, X-ray diffraction, diffuse reflectance, photoluminescence, and Fourier transform infrared spectroscope to reveal their average size, structure, and surface-chemistry. The nanotubes have been utilized for the dye-removal application involving the surface-adsorption mechanism under the dark-condition and photocatalytic degradation mechanism under the ultraviolet-radiation exposure. The variation in the dye-concentration during the dye-adsorption and photocatalysis processes has been determined using the ultraviolet-visible absorption spectrophotometer with methylene blue as a model catalytic dye-agent. It has been shown that silver-deposited anatase-titania nanotubes are more effective in enhancing the kinetics of the dye-removal via surface-adsorption and photocatalytic degradation mechanisms relative to the palladium-deposited anatase-titania nanotubes, which has been attributed to the differences in the surface-chemistry of anatase-titania nanotubes induced by the respective metal-deposition.

  20. Synthesis of triazafluoranthenones via silver(I)-mediated nonoxidative and oxidative intramolecular palladium-catalyzed cyclizations.

    PubMed

    Koutentis, Panayiotis A; Loizou, Georgia; Lo Re, Daniele

    2011-07-15

    Silver(I) fluoride (AgF)-mediated intramolecular nonoxidative and oxidative palladium-catalyzed cyclizations of 1,3-diphenyl- and 8-iodo-1,3-diphenylbenzo[e][1,2,4]triazin-7(1H)-ones 6a (R = H) and 7a (R = I) afford a new 'alkaloid like' ring system 2-phenyl-6H-[1,2,4]triazino[5,6,1-jk]carbazol-6-one 8a (triazafluoranthenone) in 86 and 100% yields, respectively. Furthermore, these cyclization protocols were used to prepare triazafluoranthenone analogues 8b-e bearing dialkylamino, methoxy, and phenylsulfanyl substituents at C-5, which were also independently synthesized from triazafluoranthenone 8a by regioselective nucleophilic addition. Similar AgF-mediated intramolecular nonoxidative and oxidative palladium-catalyzed cyclizations of 8,10-dihydro-1-iodo-10-phenylphenazin-2(7H)-ones 13 gave the new 'alkaloid like' ring system 8H-indolo[1,2,3-mn]phenazin-8-one 14 in 80 and 18% yields, respectively.

  1. 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.

  2. 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.

  3. 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.

  4. Anticancer and antimicrobial metallopharmaceutical agents based on palladium, gold, and silver N-heterocyclic carbene complexes.

    PubMed

    Ray, Sriparna; Mohan, Renu; Singh, Jay K; Samantaray, Manoja K; Shaikh, Mobin M; Panda, Dulal; Ghosh, Prasenjit

    2007-12-05

    Complete synthetic, structural, and biomedical studies of two Pd complexes as well as Au and Ag complexes of 1-benzyl-3-tert-butylimidazol-2-ylidene are reported. Specifically, trans-[1-benzyl-3-tert-butylimidazol-2-ylidene]Pd(pyridine)Cl2 (1a) was synthesized from the reaction of 1-benzyl-3-tert-butylimidazolium chloride (1) with PdCl2 in the presence of K2CO3 as a base. The other palladium complex, [1-benzyl-3-tert-butylimidazol-2-ylidene]2PdCl2 (1b), and a gold complex, [1-benzyl-3-tert-butylimidazol-2-ylidene]AuCl (1c), were synthesized by following a transmetallation route from the silver complex, [1-benzyl-3-tert-butylimidazol-2-ylidene]AgCl (1d), by treatment with (COD)PdCl2 and (SMe2)AuCl, respectively. The silver complex 1d in turn was synthesized by the reaction of 1 with Ag2O. The molecular structures of 1a-d have been determined by X-ray diffraction studies. Biomedical studies revealed that, while the palladium complexes 1a and 1b displayed potent anticancer activity, the gold (1c) and silver (1d) complexes exhibited significant antimicrobial properties. Specifically, 1b showed strong antiproliferative activity against three types of human tumor cells, namely, cervical cancer (HeLa), breast cancer (MCF-7), and colon adenocarcinoma (HCT 116), in culture. The antiproliferative activity of 1b was found to be considerably stronger than that of cisplatin. The 1b complex inhibited tumor cell proliferation by arresting the cell cycle progression at the G2 phase, preventing the mitotic entry of the cell. We present evidence suggesting that the treated cells underwent programmed cell death through a p53-dependent pathway. Though both the gold (1c) and silver (1d) complexes showed antimicrobial activity toward Bacillus subtilis, 1c was found to be ca. 2 times more potent than 1d.

  5. A fire-assay and wet chemical method for the determination of palladium, platinum, gold, and silver in ores and concentrates.

    PubMed

    Moloughney, P E

    1980-04-01

    A method is presented for the determination of palladium, platinum, gold and silver in ores and concentrates by a fire-assay and wet chemical technique. After parting of the lead assay button with dilute nitric acid, and separation of the solution from the residue, the palladium and platinum in the solution are precipitated by the addition of stannous chloride, with tellurium as collector. The resulting precipitate is combined with the gold residue and dissolved in aqua regia, then the solution is analysed for palladium, platinum and gold by atomic-absorption spectrophotometry (AAS). Silver is determined in the original solution by AAS before the reduction step.

  6. Photoluminescence Studies of Silver-Exchanged Cadmium Selenide Crystals. Modification of a Chemical Sensor for Aniline Derivatives by Heterojunction Formation

    DTIC Science & Technology

    1991-05-20

    Photoluminescence Studies of Silver-Exchanged Cadmium Selenide Crystals. Modification of a Chemical Sensor for Aniline Derivatives by Heterojunction...I__I 413r005 1 7TT..E (include Security Classification,) Photoluminescence Studies of Silver-Exchanged Cadmium Selenide Crystals. Moifification of a...Physical Chemistry 7 CO)SA7! CODES !8 S8.BECT TERMS Continue on reverse it. necessary and identity oy block nu’noer) Z.ELD CROUP SuB-GROUP cadmium

  7. The preparation of ultrathin palladium-silver alloy membrane and the application of it to ultra-pure hydrogen purifier

    SciTech Connect

    Ye Jinbiao; Yuan Weikang; Yuan Quan

    1994-12-31

    The composite membrane with an ultrathin dense palladium-silver alloy top-layer have potential to separate hydrogen from gaseous mixtures and to be applied in membrane reactors for hydrogenation or dehydrogenation. The investigation involves the preparation of an ultrathin palladium-silver alloy top-layer with a defect supported on ceramic substract modified by sol-gel. The defect was repaired by chemical reaction and premeation experiment. The result shows that the thickness of top-layer is about 1 um, the flux of hydrogen is 261 ml/cm{sup 2} {center_dot} min at 4 atm in the feed side, and 1 atm in the permeant side at 673 K, and H{sub 2} concentration in the permeant is about 99.9995{approximately} 99.9999%. Meanwhile, the composite membrane has been applied in ultra-pure hydrogen purifiers.

  8. 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.

  9. Evaluation of thiouracil-based adhesive systems for bonding cast silver-palladium-copper-gold alloy.

    PubMed

    Yamashita, Miyuki; Koizumi, Hiroyasu; Ishii, Takaya; Furuchi, Mika; Matsumura, Hideo

    2010-09-01

    This study aimed to evaluate the effect of adhesive systems based on a thiouracil monomer on bonding to silver-palladium-copper-gold (Ag-Pd-Cu-Au) alloy (Castwell M.C.12). Disk specimens were cast from the alloy and then air-abraded with alumina. The disks were bonded using six bonding systems selected from four primers and three luting materials. Shear bond strengths were determined both before and after thermocycling. Bond strength varied from 2.7 MPa to 32.0 MPa. Three systems based on a thiouracil monomer (MTU-6) showed durable bonding to the alloy, with post-thermocycling bond strengths of 22.4 MPa for the Metaltite (MTU-6) primer and Super-Bond, a tri-n-butylborane (TBB) initiated resin, 9.0 MPa for the Multi-Bond II resin, and 8.1 MPa for the Metaltite and Bistite II system. It can be concluded that a combination of thiouracil-based primer and TBB initiated resin is effective for bonding Ag-Pd-Cu-Au alloy.

  10. Gold, silver, and palladium nanoparticle/nano-agglomerate generation, collection, and characterization

    NASA Astrophysics Data System (ADS)

    Boddu, Sunita R.; Gutti, Veera R.; Ghosh, Tushar K.; Tompson, Robert V.; Loyalka, Sudarshan K.

    2011-12-01

    Generation, collection, and characterization of gold, silver, and palladium nanoparticles and nano-agglomerates (collectively "nanoparticles") have been explored. The nanoparticles were generated with a spark aerosol generator (Palas GFG-1000). They were collected using a deposition cell under diffusion and thermophoresis. The shapes and sizes of the deposited particles were measured using transmission electron microscopy (TEM). TEM images showed that the particles were in the range of 8-100 nm in diameter, and their shapes varied from nearly spherical to highly non-spherical. Thermophoresis enhanced the deposition of nanoparticles (over the diffusive or the isothermal deposition) in all cases. Further, the size distributions of the nanoparticles generated in the gas phase (aerosol) were measured using a scanning mobility particle sizer (SMPS 3080, TSI) spectrometer. The SMPS results show that an increase in the spark frequency of the generator shifted the size distributions of the nanoparticles to larger diameters, and the total particle mass production rate increased linearly with increase in the spark frequency. The computational fluid dynamics code Fluent (Ansys) was used to model the flow in the deposition cell, and the computed results conform to the observations.

  11. Palladium and silver abundances in stars with [Fe/H] > -2.6

    NASA Astrophysics Data System (ADS)

    Wu, Xiaoshu; Wang, Liang; Shi, Jianrong; Zhao, Gang; Grupp, Frank

    2015-07-01

    Palladium (Pd) and silver (Ag) are the key elements for probing the weak component in the rapid neutron-capture process (r-process) of stellar nucleosynthesis. We performed a detailed analysis of the high-resolution and high signal-to-noise ratio near-UV spectra from the archive of HIRES on the Keck Telescope, UVES on the VLT, and HDS on the Subaru Telescope, to determine the Pd and Ag abundances of 95 stars. This sample covers a wide metallicity range with -2.6 ≲ [Fe/H] ≲ +0.1, and most of them are dwarfs. The plane-parallel local thermodynamic equilibrium MAFAGS-OS model atmosphere was adopted, and the spectral synthesis method was used to derive the Pd and Ag abundances from Pd iλ 3404 Å and Ag iλ 3280/3382 Å lines. We found that both elements are enhanced in metal-poor stars, and their ratios to iron show flat trends at -0.6 < [Fe/H] < +0.1. The abundance ratios of [Ag/H] and [Pd/H] are well correlated over the whole abundance range. This implies that Pd and Ag have similar formation mechanisms during the Galactic evolution. Tables 1, 2 and Fig. 5 are available in electronic form at http://www.aanda.org

  12. 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.

  13. Electrothermal atomic-absorption determination of silver in zinc and cadmium selenides

    SciTech Connect

    Khozhainov, Yu.M.; Dolova, N.K.

    1987-10-01

    An atomic-absorption signal is dependent on the chemical forms of the test element and matrix in the solution as well as on the processes during electrothermal atomization. The authors have examined the absorption due to silver with a Saturn-2 spectrophotometer with such atomization; the authors used the 328.1 nm line (i = 10 mA, slit width 0.15, time-constant 0.6 sec). The presence of cadmium and zinc was monitored from the 326.1 and 213.8 nm lines respectively. The measurements were made in argon. The internal gas flow was turned off during the atomization. The graphite was used until there were sharp changes in the silver absorption due to change in the structure of the graphite and occurrence of the memory effect. The results from over 100 specimens of cadmium selenide films analyzed for silver showed that the results were in full agreement with the conditions for silver activation (time, temperature, and activator mass).

  14. Skeletal concentrations of lead, cadmium, zinc, and silver in ancient North American Pecos Indians.

    PubMed Central

    Ericson, J E; Smith, D R; Flegal, A R

    1991-01-01

    Bone samples of 14 prehistoric North American Pecos Indians from circa 1400 A.D. were analyzed for lead, cadmium, zinc, and silver by graphite furnace atomic absorption spectrometry to establish the baseline levels of these elements in an ancient North American population. Measurements of outer and inner bone fractions indicate the former were contaminated postmortem for lead, zinc, and cadmium. The contamination-adjusted average (mean +/- SD) level of lead (expressed as the ratio of atomic lead to atomic calcium) in bones of the Indians was 8.4 +/- 4.4 x 10(-7)), which was similar to ratios in bones of ancient Peruvians (0.9 to 7.7 x 10(-7)) and significantly lower than ratios in bones of modern adults in England and the United States (210 to 350 x 10(-7]. The adjusted average concentrations (microgram per gram dry weight) of biologic cadmium, silver, and zinc in the Pecos Indian bones were 0.032 +/- 0.013, 0.094 +/- 0.044, and 130 +/- 66, as compared to concentrations of 1.8, 0.01 to 0.44, and 75 to 170 in the bones of modern people, respectively. Therefore, cadmium concentrations in Pecos Indian bones are also approximately 50-fold lower than those of contemporary humans. These data support earlier findings that most previously reported natural concentrations of lead in human tissues are erroneously high and indicate that natural concentrations of cadmium are also between one and two orders of magnitude lower than contemporary concentrations. PMID:1773793

  15. Palladium alloys for biomedical devices.

    PubMed

    Wataha, John C; Shor, Kavita

    2010-07-01

    In the biomedical field, palladium has primarily been used as a component of alloys for dental prostheses. However, recent research has shown the utility of palladium alloys for devices such as vascular stents that do not distort magnetic resonance images. Dental palladium alloys may contain minor or major percentages of palladium. As a minor constituent, palladium hardens, strengthens and increases the melting range of alloys. Alloys that contain palladium as the major component also contain copper, gallium and sometimes tin to produce strong alloys with high stiffness and relatively low corrosion rates. All current evidence suggests that palladium alloys are safe, despite fears about harmful effects of low-level corrosion products during biomedical use. Recent evidence suggests that palladium poses fewer biological risks than other elements, such as nickel or silver. Hypersensitivity to palladium alone is rare, but accompanies nickel hypersensitivity 90-100% of the time. The unstable price of palladium continues to influence the use of palladium alloys in biomedicine.

  16. Nanoparticle-electrode collision processes: The electroplating of bulk cadmium on impacting silver nanoparticles

    NASA Astrophysics Data System (ADS)

    Zhou, Yi-Ge; Rees, Neil V.; Compton, Richard G.

    2011-08-01

    We report, for the first time, the bulk deposition (electroplating) of a metal onto nanoparticles during collisions with an inert electrode surface. Experiments show that for silver nanoparticles, multiple layers of Cd atoms can be electroplated onto the AgNPs from aqueous Cd 2+ during collisions with a glassy carbon electrode held at a suitably reducing potential, and an average of 19 atomic layers of cadmium are found to be deposited in the few milliseconds that the NP is in contact with the electrode. For comparison, results are also presented for the underpotential deposition of Cd onto AgNPs under similar conditions.

  17. The relative stabilities of tungsten hexacarbonyl, silver neodecanoate some metal acetyl- and hexafluoroacetylacetonates and the thermal properties of the palladium(II) acetonates

    NASA Astrophysics Data System (ADS)

    Poston, S.; Reisman, A.

    1989-07-01

    The relative stabilities of silver neodecanoate, tungsten hexacarbonyl, and a series of metal acetyl- and hexafluoroacetyl- acetonates, were determined using differential ther-mal analysis (DTA) and weight loss analysis. In general, the acetylacetonates decom-pose in the solid state at relatively low temperatures (100-200° C), with several of them exhibiting appreciable vapor pressures at temperatures below which their decomposi-tion rate is significant. Hexaf luoro derivatives of these compounds are, in general, more volatile and decompose at higher temperatures. The thermal decomposition behavior of palladium(II) acetylacetonate and palladium(II) hexafluoroacetylacetonate were each investigated using DTA at atmospheric pressure and under each compound’s equilib-rium or decomposition product(s) vapor pressure in conjunction with weight loss and residue composition analysis. At the heating rates employed, ≤2° C/min, palladium(II) acetylacetonate tends to decompose upon heating in either an inert or oxidizing atmo-sphere before significant quantities volatilize. On the other hand, palladium(II) hex-afluoroacetylacetonate tends to volatilize completely before any signs of decomposition are observed under the same conditions. Heating palladium(II) acetylacetonate in ar-gon, at ≤2° C/min, shows the onset of an endotherm at approximately 196° C, at the conclusion of which a product containing 75% palladium was found, the remainder com-prised of carbon, hydrogen and oxygen. In an oxidizing atmosphere at the above men-tioned heating rate, Palladium(II) acetylacetonate decomposes exothermically at 180° C yielding essentially pure palladium. Continued heating in oxygen, to 800° C results in pure PdO. At 900° C, the PdO decomposes yielding pure palladium. Depending upon the heating rates applied, one or two endotherms may be observed during the heating of palladium(II) hexafluoroacetylacetonate. Heating at 2° C/min in either an argon or ox-ygen atmosphere

  18. Evaluation of two thione primers and composite luting agents used for bonding a silver-palladium-copper-gold alloy.

    PubMed

    Matsumura, H; Atsuta, M; Tanoue, N

    2002-09-01

    The purpose of the current study was to evaluate the bond strength and durability of two metal adhesive systems bonded to a silver-palladium-copper-gold (Ag-Pd) alloy. Disk specimens were cast from an Ag-Pd alloy (Castwell M.C. 12), air-abraded with 50 micro m grain-sized alumina, and they were bonded with two primer-cement bonding systems (Alloy Primer and Panavia Fluoro Cement; Metaltite and Bistite II). For each cement, unprimed specimens were also prepared as experimental controls. Shear bond strengths were determined both before and after thermocycling (4-60 degrees C, 1 min each, 100 000 cycles). The average post-thermocycling bond strengths in MPa (n=8) were: 39.0 for the Metaltite-Bistite II system, 32.2 for the Alloy Primer-Panavia Fluoro Cement system, 23.1 for the Bistite II material and 21.0 for the Panavia Fluoro Cement material. The use of proprietary primers, both of which contain thione functional monomer, enhanced the post-thermocycling bond strengths of both cements (P < 0.05). After thermocycling, however, the difference in bond strength between the two cements was not significant regardless of the use of the primers (P > 0.05). It is concluded that the combined use of the thione primer and the luting agent is necessary for bonding the Ag-Pd alloy examined.

  19. 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.

  20. 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.

  1. Silver-mediated palladium-catalyzed direct C-H arylation of 3-bromoisothiazole-4-carbonitrile.

    PubMed

    Ioannidou, Heraklidia A; Koutentis, Panayiotis A

    2011-03-18

    Silver(I) fluoride-mediated Pd-catalyzed C-H direct arylation/heteroarylation of 3-bromoisothiazole-4-carbonitrile (1a) gives twenty-four 5-aryl/heteroaryl-3-bromoisothiazole-4-carbonitriles. The reaction was partially optimized with respect to catalyst, ligand, and base. During this study 3,3'-dibromo-5,5'-biisothiazole-4,4'-dicarbonitrile (3a) was isolated as a byproduct and subsequently prepared via the silver-mediated Pd-catalyzed oxidative dimerization of 3-bromoisothiazole-4-carbonitrile in 67% yield. The analogous phenylation and oxidative dimerization of 3-chloroisothiazole-4-carbonitrile (1b) gave 3-chloro-5-phenylisothiazole-4-carbonitrile (4) and 3,3'-dichloro-5,5'-biisothiazole-4,4'-dicarbonitrile (3b) in 96% and 69% yields, respectively.

  2. 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.

  3. Copper(I), silver(I), and palladium(II) complexes of a thiaoxamacrocycle displaying unusual topologies.

    PubMed

    Lee, So Young; Park, Sunhong; Lee, Shim Sung

    2009-12-07

    Coordination behavior of the 14-membered dibenzo-O(2)S(2) macrocycle, L, with the soft metal ions such as Pd(II), Cu(I), and Ag(I) is reported. The X-ray structures of the complexes have been determined, and a range of less common structural types, including mono-, di-, and multinuclear species with discrete and continuous forms were obtained. A two-step approach via reaction of dichloro-palladium(II) complex of L as a metalloligand, with L through a treatment of silver(I) perchlorate, led to the formation of bis(ligand) monopalladium(II) complex, [Pd(L)(2)] x 2 ClO(4) x 2 CH(3)NO(2) (1). In this case, the square-planar stereochemical demand of Pd(II) coupled with the coordination of the S(2)-donors of L to a metal center results in the formation of the bis(ligand)-type mononuclear complex. In 1, the ether oxygens of the ring are unbound. L reacts with CuBr to yield related 2:2:2 (metal/ligand/anion) complex of type [Cu(2)Br(2)(L)(2)] (2), in which two ligand molecules are linked by a rhomboid-type Cu-Br(2)-Cu cluster unit. However, the parallel reaction with CuI afforded the mixture of the isostructural 2:2:2 type complex [Cu(2)I(2)(L)(2)] (3a) and double-stranded 1D coordination polymer {[Cu(2)I(2)(L)(2)] x 2 CH(3)CN}(n) (3b). The framework of 3b contains four bridging L coordinated to a rhomboidal Cu-I(2)-Cu motif through the exomonodentate Cu-S bonds. Again, the ether oxygens do not coordinate in copper(I) halide complexes. The observed different reactivity between copper(I) bromide and copper(I) iodide was also confirm by an XRPD measurement. Unlike the Pd(II) and Cu(I) cases, L afforded an unusual tris(L)-disilver(I) (club-sandwich-type) complex [Ag(2)(L)(3)](PF(6))(2) (4) on its reaction with AgPF(6). Each silver adopts a trigonal planar coordination environment with coordination sites occupied by two S atoms from one terminal ligand, and by one S atom from the bridging ligand; once again the ether oxygens are not coordinated. An NMR titration of the

  4. Determination of lead and cadmium in seawater using a vibrating silver amalgam microwire electrode.

    PubMed

    Bi, Zhaoshun; Salaün, Pascal; van den Berg, Constant M G

    2013-03-26

    Silver amalgamated electrodes are a good substrate to determine lead (Pb) and cadmium (Cd) in seawater because they have properties similar to mercury but without the free mercury (Hg). Here a silver amalgamated microwire (SAM) electrode is optimised for the determination of Pb and Cd in coastal waters and uncontaminated ocean waters. The SAM was vibrated during the deposition step to increase the sensitivity, and electroanalytical parameters were optimised. The Hg coating required plating from a relatively concentrated (millimolar) solution, much greater (500×) than used for instance to coat glassy carbon electrodes. However, the coating on the ex situ amalgamated electrode was found to be stable and could be used for up to a week to determine trace levels of Pb in seawater of natural pH. The limit of detection square-wave ASV (50 Hz) using the pre-plated SAM electrode was 8 pM Pb using a 1-min plating time at pH 4.5. The limit of detection in pH 2 seawater was 4 pM using a 5-min plating time, and it was 12 pM using a 10-min plating time at natural pH in the presence of air, using a square-wave frequency of 700 Hz. The vibrating SAM electrode was tested on the determination of Pb in reference seawater samples from the open Atlantic (at the 20 pM level), Pacific, and used for a study of Pb in samples collected over 24 h in Liverpool Bay (Irish Sea).

  5. 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.

  6. Sequestration of radioactive iodine in silver-palladium phases in commercial spent nuclear fuel

    NASA Astrophysics Data System (ADS)

    Buck, Edgar C.; Mausolf, Edward J.; McNamara, Bruce K.; Soderquist, Chuck Z.; Schwantes, Jon M.

    2016-12-01

    Radioactive iodine is the Achilles' heel in the design for the safe geological disposal of spent uranium oxide (UO2) nuclear fuel. Furthermore, iodine's high volatility and aqueous solubility were mainly responsible for the high early doses released during the accident at Fukushima Daiichi in 2011. Studies Kienzler et al., however, have indicated that the instant release fraction (IRF) of radioiodine (131/129I) does not correlate directly with increasing fuel burn-up. In fact, there is a peak in the release of iodine at around 50-60 MW d/kgU, and with increasing burn-up, the IRF of 131/129I decreases. The reasons for this decrease have not fully been understood. We have performed microscopic analysis of chemically processed high burn-up UO2 fuel (80 MW d/kgU) and have found recalcitrant nano-particles containing, Pd, Ag, I, and Br, possibly consistent with a high pressure phase of silver iodide in the undissolved residue. It is likely that increased levels of Ag and Pd from 239Pu fission in high burnup fuels leads to the formation of these metal halides. The occurrence of these phases in UO2 nuclear fuels may reduce the impact of long-lived 129I on the repository performance assessment calculations.

  7. 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.

  8. 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

  9. Intracellular sequestration of zinc, cadmium and silver in Hebeloma mesophaeum and characterization of its metallothionein genes.

    PubMed

    Sácký, Jan; Leonhardt, Tereza; Borovička, Jan; Gryndler, Milan; Briksí, Aleš; Kotrba, Pavel

    2014-06-01

    Sequestration of intracellular heavy metals in eukaryotes involves compartmentalization and binding with cytosolic, cysteine-rich metallothionein (MT) peptides. We examined the roles of these processes in handling of zinc (Zn), cadmium (Cd) and silver (Ag) in sporocarps and a metal-exposed extraradical mycelium of Hebeloma mesophaeum, the Zn-accumulating ectomycorrhizal (EM) species frequently associated with metal disturbed sites. Size exclusion chromatography revealed that the majority of Zn and Cd in the sporocarps and mycelium was contained in a low molecular mass fraction attributable to compartmentalized metal. The staining of hyphal cells with the Zn-specific Zinquin and Cd-specific Leadmium fluorescent tracers labeled Zn and Cd in small, punctuated vesicles and vacuoles, respectively. By contrast, the sporocarp and mycelium Ag was associated with cysteine-rich, 5-kDa peptides. The peptides of the same size were also identified in minor Zn and Cd complexes from the metal-exposed mycelium. We have further isolated and characterized HmMT1, HmMT2 and HmMT3 genes coding for different 5-kDa MTs of H. mesophaeum collected at a lead smelter site. Heterologous complementation assays in metal-sensitive yeast mutants indicated that HmMTs encode functional, metal-specific peptides: only HmMT1 was able to complement sensitivity to Zn; HmMT1 conferred higher tolerance to Cd and Cu than HmMT2 or HmMT3; and both HmMT2 and HmMT3, but not HmMT1, conferred increased tolerance to Ag. The presence of HmMT1 and HmMT3, but not HmMT2, was also confirmed in a H. mesophaeum isolate from an unpolluted site. Gene expression analysis in the extraradical mycelium of this isolate revealed that the transcription of HmMT1 was preferentially induced in the presence of Zn and Cd, while Ag was a stronger inducer of HmMT3. Altogether, these results improve our understanding of the handling of intracellular Zn, Cd and Ag in Hebeloma and represent the first evidence suggesting involvement of MTs

  10. Discrete Silver(I)-Palladium(II)-Oxo Nanoclusters, {Ag4 Pd13 } and {Ag5 Pd15 }, and the Role of Metal-Metal Bonding Induced by Cation Confinement.

    PubMed

    Yang, Peng; Xiang, Yixian; Lin, Zhengguo; Lang, Zhongling; Jiménez-Lozano, Pablo; Carbó, Jorge J; Poblet, Josep M; Fan, Linyuan; Hu, Changwen; Kortz, Ulrich

    2016-12-19

    We introduce the class of discrete silver(I)-palladium(II)-oxo nanoclusters with the preparation of {Ag4 Pd13 } and {Ag5 Pd15 }. Both polyanions represent the first examples of noble metal-capped polyoxo-noble-metalates in a fully inorganic assembly, featuring an unprecedented host-guest mode containing hetero- and homometallic Ag-Pd and Ag-Ag bonding interactions. Comprehensive theoretical calculations suggest that the Ag-Pd metallic bonds originate partially from surface confinement of Ag(I) guest ions onto the anionic polyoxopalladate host that is induced by strong electrostatic forces. This work opens the field of fully inorganic silver-palladium-oxo nanoclusters, which can be considered as discrete mixed noble metal precursors for the formation of monodisperse core-shell nanoparticles, with high relevance for catalysis.

  11. 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.

  12. Exposure of silver carp (Hypophthalmichthys molitrix) to environmentally relevant levels of cadmium: hematology, muscle physiology, and implications for stock enhancement in the Xiangjiang River (Hunan, China).

    PubMed

    Zhang, Ting; Zhang, Yu; Li, DeLiang; Xiao, TiaoYi; Li, Jie

    2013-01-01

    Cadmium is a non-essential metal with a wide distribution that has severe toxic effects on aquatic animals. Changes in hematology and muscle physiology were examined in silver carp (Hypophthalmichthys molitrix) exposed to environmentally relevant levels of cadmium (0.01 mg L(-1)) for 96 h. Cadmium exposure induced significant increases in the red blood cell count, and in the plasma concentrations of cortisol, glucose, and lactate. This suggests that the dose of cadmium was sufficient to cause stress, possibly associated with impaired gas exchange at the gills. There were no changes in hemoglobin concentration or plasma protein concentration. Significant decreases in muscle energy fuels (ATP and glycogen), and increases in muscle lactate persisted until the end of the exposure period, respectively. The changes in muscle lactate and protein in silver carp differed from those observed in response to exposure of fish to cadmium and heavy metals in other studies. The study highlights the importance of selecting unpolluted release sites with suitable water conditions for the survival of newly released individuals for stock enhancement of the Xiangjiang River.

  13. Effect of silver or copper middle layer on the performance of palladium modified nickel foam electrodes in the 2-chlorobiphenyl dechlorination.

    PubMed

    He, Zhiqiao; Sun, Junjun; Wei, Jie; Wang, Qiong; Huang, Chengxiang; Chen, Jianmeng; Song, Shuang

    2013-04-15

    To enhance the activity of chemi-deposited palladium/nickel foam (Pd/Ni) electrodes used for an electrochemical dechlorination process, silver or copper was deposited electrochemically onto the nickel foam substrate (to give Ag/Ni or Cu/Ni) before the chemical deposition of palladium. The physicochemical properties of the resulting materials (Pd/Ni, Pd/Ag/Ni and Pd/Cu/Ni) were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM), and their electrochemical catalytic activities were evaluated by monitoring the electrochemical dechlorination of 2-chlorobiphenyl (2-CB) in strongly alkaline methanol/water solution. The results show that the Pd/Ag/Ni and Pd/Cu/Ni electrodes had consistently higher electrocatalytic activities and current efficiencies (CEs) compared with the untreated Pd/Ni electrode. The Pd/Ag/Ni electrode exhibited the highest activity. The dechlorination was also studied as a function of Pd loading, the Ag or Cu interlayer loadings, and the current density. The Pd loading and the interlayer loadings both had positive effects on the dechlorination reaction. Increasing the current density increased the reaction rate but reduced the CE. The improvement of the electrocatalytic activities of the Pd/Ni electrode by applying the interlayer of Ag or Cu resulted from the enlargement of the effective surface area of the electrode and the adjustment of the metal-H bond energy to the appropriate value, as well as the effective adsorption of 2-CB on Ag. Moreover, the high catalytic activity of the Pd/Ag/Ni electrode was maintained after six successive cyclic experiments, whereas Pd/Cu/Ni electrodes deactivate severely under the same conditions.

  14. Radiotracer study of the adsorption of organic compounds on gold. adsorption of chloroacetic and phenylacetic acid, and the effects of cadmium, copper, and silver adatoms on it

    SciTech Connect

    Horani, G.; Andreev, V.N.; Vazarinov, V.E.

    1986-04-01

    This paper studies the adsorption of monochloroacetic and phenylacetic acid (MA and PA, respectively) by the radiotracer technique on gold-plated gold electrodes in acidic solutions. The authors also study the effect of cadmium, copper, and silver adatoms on these processes. The adsorption of MA was measured as a function of potential of the electrode. Data from these measurements are presented. Data show that cadmium, copper, and silver ions present in the solution have no effect on the adsorption of PA at potentials where they are not adsorbed on the gold surface. It is confirmed that the radiotracer technique will be as effective in adsorption studies on the gold-plated gold electrode as it was in the case of the platinized platinum electrode.

  15. 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.

  16. Plasmonic enhancement of low cost mesoporous Fe2O3-TiO2 loaded with palladium, platinum or silver for dye sensitized solar cells (DSSCs)

    NASA Astrophysics Data System (ADS)

    Sanad, M. M. S.; Shalan, Ahmed E.; Rashad, M. M.; Mahmoud, M. H. H.

    2015-12-01

    In this article, a low cost mesoporous Fe2O3-TiO2 nanoparticles has been synthesized from Abu Ghalaga ilmenite ore, Egypt using simple hydrothermal route. Meanwhile, silver, platinum and palladium metals nanoparticles from spent catalysts have been extracted and deposited between the anatase TiO2 particles using in situ reduction step. The as-synthesized samples were characterized by X-ray diffraction (XRD), transmission electron microscopic (TEM), N2 adsorption-desorption isotherm (SBET) and X-ray photoelectron spectroscopy (XPS). The as-prepared materials were applied as photoanodes in dye-sensitized solar cells (DSSCs), whose photocurrent-voltage J-V characteristic curves measurements were consistently performed. The 0.5% precious metal doped samples NPs exhibit absorption enhancement over a broad wavelength range due to the excitation of localized surface plasmons (LSPs) at different wavelengths which also exhibited very good and enhanced photovoltaic performance as a result of the strong scattering lightresulting of noticeable enhancement of charge transfer rates. Indeed, the Ag@Fe2O3-TiO2 sample exhibited the maximum overall conversion efficiency (η % = 4.5%) and it can be considered as a cost-effective photoanode for DSSCs.

  17. 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.

  18. Antibacterial activity of microstructured sacrificial anode thin films by combination of silver with platinum group elements (platinum, palladium, iridium).

    PubMed

    Köller, Manfred; Bellova, Petri; Javid, Siyamak Memar; Motemani, Yahya; Khare, Chinmay; Sengstock, Christina; Tschulik, Kristina; Schildhauer, Thomas A; Ludwig, Alfred

    2017-05-01

    Five different Ag dots arrays (16 to 400dots/mm(2)) were fabricated on a continuous platinum, palladium, or iridium thin film and for comparison also on titanium film by sputter deposition and photolithographic patterning. To analyze the antibacterial activity of these microstructured films Staphylococcus aureus (S. aureus) were placed onto the array surfaces and cultivated overnight. To analyze the viability of planktonic as well as surface adherent bacteria, the applied bacterial fluid was subsequently aspirated, plated on blood agar plates and adherent bacteria were detected by fluorescence microscopy. A particular antibacterial effect towards S. aureus was induced by Ag dot arrays on each of the platinum group thin film (sacrificial anode system for Ag) in contrast to Ag dot arrays fabricated on the Ti thin films (non-sacrificial anode system for Ag). Among platinum group elements the Ir-Ag system exerted the highest antibacterial activity which was accompanied by most advanced dissolution of the Ag dots and Ag ion release compared to Ag dots on Pt or Pd.

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

    PubMed

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

    2016-01-14

    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.

  20. 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

  1. 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 )

  2. Effect of Chemical Charging/Discharging on Plasmonic Behavior of Silver Metal Nanoparticles Prepared using Citrate-Stabilized Cadmium Selenide Quantum Dots.

    PubMed

    Ingole, Pravin P; Bhat, Mohsin A

    2016-10-18

    The thermodynamics and kinetics of the chemical and electrochemical charging of a catalyst surface are very important to understand its applicability as a catalyst material, particularly in redox catalysis. Through the present study, we hereby communicate the results obtained from our detailed investigations related to the effect of chemical charging on the plasmonic behavior of silver metal nanoparticles (Ag MNPs) as redox catalysts. Two different batches of Ag MNPs were prepared through thermally assisted chemical reduction of silver ions. The difference in these batches was the use or not of citrate-capped cadmium selenide quantum dots (Q-CdSe) for the reduction of solution-phase silver ions to their colloidal plasmonic phase. The charge on the surfaces of the Ag MNPs was varied by the chemical electron injection method by using BH4(-) ions from a NaBH4 solution. The processes of charging and discharging were monitored by using UV/Vis absorption spectroscopy. The impact of the concentration of the reductant on the charging and discharging processes was also investigated. The Ag MNPs were also tested for their voltammetric response, wherein it was observed that it was more difficult to oxidize the Ag MNPs prepared with Q-CdSe seeds than to oxidize Ag MNPs prepared without Q-CdSe particles. Our results demonstrate that Q-CdSe seeds not only enhance the redox catalytic activity of Ag MNPs but also provide stability towards polarization of their plasmonic behavior.

  3. 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

  4. Protective Effects of Calcium on Cadmium Accumulation in Co-Cultured Silver Carp (Hypophthalmichthys molitrix) and Triangle Sail Mussel (Hyriopsis cumingii).

    PubMed

    Li, Deliang; Pi, Jie; Wang, Jianping; Zhu, Pengfei; Lei, Liuping; Zhang, Ting; Liu, Deming

    2016-12-01

    Discovering cost effective strategies to reduce cadmium (Cd) uptake is of great concern for consumer food safety in the aquaculture industry. This study investigated the protective effects of calcium (Ca) on Cd uptake in co-cultured silver carp (Hypophthalmichthys molitrix) and triangle sail mussel (Hyriopsis cumingii). The results show that Ca-depending on its applied concentration-caused a significant decrease in the Cd uptake into muscle (by 48 %-72 %), gills (by 51 %-57 %), liver (by 52 %-81 %) and kidney (by 54 %-81 %) of silver carp (p < 0.001), as well as foot (by 8 %-32 %) and visceral mass (by 40 %-47 %) of triangle sail mussels (p < 0.05). The results indicate that Ca treatment is an effective means of reducing Cd accumulation in aquaculture. Since Ca is often used to increase the quality of pearls produced by triangle sail mussel, the quality of co-cultured edible fish might improve as a consequence of the potentially reduced Cd uptake.

  5. Photocatalytic reduction of nitrite to dinitrogen in aqueous suspensions of metal-loaded titanium(IV) oxide in the presence of a hole scavenger: an ensemble effect of silver and palladium co-catalysts.

    PubMed

    Gekko, Hitoshi; Hashimoto, Keiji; Kominami, Hiroshi

    2012-06-14

    Nitrite (NO(2)(-)) was photocatalytically reduced to dinitrogen (N(2)) in an aqueous suspension of two kinds of titanium(iv) oxide particles loaded with palladium and silver (Pd-TiO(2) and Ag-TiO(2)) at pH 8 under irradiation of UV light in the presence of sodium oxalate as a hole scavenger. The two metal-loaded TiO(2) photocatalysts had different roles in conversion of NO(2)(-) to N(2) and worked in an effective ensemble without conflict: (1) Pd-TiO(2) induced photocatalytic disproportionation of NO(2)(-) to N(2) and nitrate (NO(3)(-)) and (2) Ag-TiO(2) selectively reduced the thus-formed NO(3)(-) back to NO(2)(-) (partially to N(2)) with oxalate acting as a hole scavenger. When Pd-TiO(2) was used alone for NO(3)(-) reduction in the presence of sodium oxalate, Pd-TiO(2) induced fruitless photocatalytic decomposition of oxalate to carbon dioxide and dihydrogen. The presence of Ag-TiO(2) suppressed the fruitless decomposition of oxalate by Pd-TiO(2) because Ag-TiO(2) continuously provided NO(2)(-) in the reaction system using oxalate as a hole scavenger and Pd-TiO(2) therefore only worked as a photocatalyst for disproportionation of NO(2)(-) to N(2) and NO(3)(-) as it did when used alone.

  6. 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

    NASA Astrophysics Data System (ADS)

    Chen, Chong; Zhai, Yong; Li, Chunxi; Li, Fumin

    2014-11-01

    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.

  7. 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.

  8. 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.

  9. 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

  10. 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

    Chen, Chong; Zhai, Yong; Li, Chunxi; Li, Fumin

    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.

  11. Identification, characterization and expression profiles of Chironomus riparius glutathione S-transferase (GST) genes in response to cadmium and silver nanoparticles exposure.

    PubMed

    Nair, Prakash M Gopalakrishnan; Choi, Jinhee

    2011-02-01

    In this study, we report the identification and characterization of 13 cytosolic GST genes in Chironomus riparius from Expressed Sequence Tags (ESTs) database generated using pyrosequencing. Comparative and phylogenetic analyses were undertaken with Drosophila melanogaster and Anopheles gambiae GSTs and 3 Delta, 4 Sigma, 1 each in Omega, Epsilon, Theta, Zeta and 2 unclassified classes of GSTs were identified and characterized. The relative mRNA expression levels of all of the C. riparius GSTs (CrGSTs) genes under different developmental stages were varied with low expression in the larval stage. The antioxidant role of CrGSTs was studied by exposing fourth instar larvae to a known oxidative stress inducer Paraquat and the relative mRNA expression to different concentrations of cadmium (Cd) and silver nanoparticles (AgNPs) for various time intervals were also studied. All the CrGSTs showed up- or down regulation to varying levels based upon the concentration, and duration of exposure. The highest mRNA expression was noticed in Delta3, Sigma4 and Epsilon1 GST class in all treatments. These results show the role of CrGST genes in defense against oxidative stress and its potential as a biomarker to Cd and AgNPs exposure.

  12. Palladium-Catalyzed, Site-Selective Direct Allylation of Aryl C–H Bonds by Silver-Mediated C–H Activation: A Synthetic and Mechanistic Investigation

    PubMed Central

    Lee, Sarah Yunmi; Hartwig, John F.

    2016-01-01

    We describe a method for the site-selective construction of a C(aryl)–C(sp3) bond by the palladium-catalyzed direct allylation of arenes with allylic pivalates in the presence of AgOPiv to afford the linear (E)-allylated arene with excellent regioselectivity; this reaction occurs with arenes that have not undergone site-selective and stereoselective direct allylation previously, such as monofluorobenzenes and non-fluorinated arenes. Mechanistic studies indicate that AgOPiv ligated by a phosphine reacts with the arene to form an arylsilver(I) species, presumably through a concerted metalation–deprotonation pathway. The activated aryl moiety is then transferred to an allylpalladium(II) intermediate formed by oxidative addition of the allylic pivalate to the Pd(0) complex. Subsequent reductive elimination furnishes the allyl–aryl coupled product. The aforementioned proposed intermediates, including an arylsilver complex, have been isolated, structurally characterized, and determined to be chemically and kinetically competent to undergo the proposed elementary steps of the catalytic cycle. PMID:27797512

  13. Palladium-Catalyzed Fluorosulfonylvinylation of Organic Iodides.

    PubMed

    Zha, Gao-Feng; Zheng, Qinheng; Leng, Jing; Wu, Peng; Qin, Hua-Li; Sharpless, K Barry

    2017-03-29

    A palladium-catalyzed fluorosulfonylvinylation reaction of organic iodides is described. Catalytic Pd(OAc)2 with a stoichiometric amount of silver(I) trifluoroacetate enables the coupling process between either an (hetero)aryl or alkenyl iodide with ethenesulfonyl fluoride (ESF). The method is demonstrated in the successful syntheses of eighty-eight otherwise difficult to access compounds, in up to 99 % yields, including the unprecedented 2-heteroarylethenesulfonyl fluorides and 1,3-dienylsulfonyl fluorides.

  14. 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.

  15. Role of a binary metallic modifier in the determination of cadmium in graphite furnace atomic absorption spectrometry.

    PubMed

    Morimoto, Syun; Ashino, Tetsuya; Wagatsuma, Kazuaki

    2010-01-01

    In order to discuss the matrix modifier effect of palladium, iron, and a mixture of palladium and iron for the determination of cadmium in graphite-furnace atomic absorption spectrometry (GF-AAS), we measured the absorption profiles of a cadmium line at various compositions of these elements. Variations in the gas temperature were also estimated with the progress of atomization, by using a two-line method under the assumption of a Boltzmann distribution. The atomic absorption of cadmium appeared on the way of heating from the charring temperature to the atomizing temperature while the gas temperature was still low; it was thus considered that cadmium was atomized through direct conductive heating from the wall of the graphite furnace. Therefore, the effectiveness of modifiers for cadmium would be determined through any reactions on the furnace wall at the programmed charring and atomizing temperatures. The addition of iron, palladium, and an iron-palladium mixture all enhanced the absorption signal of cadmium compared to a pure cadmium sample; however, their effects were different from one another. Each addition of iron or palladium to the sample solution led to an enhancement of the cadmium absorbance, indicating that iron or palladium individually became an effective matrix modifier for the determination of cadmium. However, the addition of palladium was ineffective for the matrix modification in the coexistence of large amounts of iron. Although these phenomena are very complicated, and thus cannot be understood completely, any metallurgical reaction between the constituent elements during heating of the furnace wall, such as the formation of solid solutions and intermetallic compounds, would cause the effect of a matrix modifier in GF-AAS.

  16. 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.

  17. 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.

  18. Cadmium toxicity

    PubMed Central

    Wan, Lichuan; Zhang, Haiyan

    2012-01-01

    Cadmium is a well-known environmental pollutant with distinctly toxic effects on plants. It can displace certain essential metals from a wealth of metalloproteins, and thus disturb many normal physiological processes and cause severe developmental aberrant. The harmful effects of cadmium stress include, but are not limited to: reactive oxygen species overproduction, higher lipid hydroperoxide contents, and chloroplast structure change, which may lead to cell death. Plants have developed diverse mechanisms to alleviate environmental cadmium stress, e.g., cadmium pump and transporting cadmium into the leaf vacuoles. This mini-review focuses on the current research into understanding the cellular mechanisms of cadmium toxicity on cytoskeleton, vesicular trafficking and cell wall formation in plants. PMID:22499203

  19. Cadmium Alternatives

    DTIC Science & Technology

    2012-08-01

    including cadmium! Cadmium Replacements (With MIL-DTL-38999 Designations) Zn/Ni (Class Z) Per ASTM B 841, type D (black) Electroless Nickel plus... Electroless nickel / PTFE (Durmalon®) Electroplated Aluminum (Alumiplate®) Electroplated tin-zinc (SnZn) Control: cadmium with hexavalent chromate... electroless nickel / PTFE performed well Electroplated aluminum performed did not perform well on connectors Electroplated aluminum did not

  20. 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

  1. 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.

  2. Doped palladium containing oxidation catalysts

    SciTech Connect

    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.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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

  8. Silver Sulfadiazine

    MedlinePlus

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

  9. 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.

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

    SciTech Connect

    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.

  11. 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.

  12. Electrically conductive palladium-containing polyimide films

    NASA Technical Reports Server (NTRS)

    St.clair, A. K.; Furtsch, T. A.; Taylor, L. T.

    1981-01-01

    Palladium addition makes light, flexible film with low resistivity to relieve space charging. Polyimide film is prepared in four steps: preparation of polyamic acid in polar solvent; addition of soluable palladium complex salt; fabrication of film of "palladium polyamic acid" solution; and thermal imidization of film to palladium-containing polyimide by 300 C heating. Lowered resistivities were achieved without loss in film flexibility or increase in film weight.

  13. Silver-catalyzed late-stage fluorination.

    PubMed

    Tang, Pingping; Furuya, Takeru; Ritter, Tobias

    2010-09-01

    Carbon-fluorine bond formation by transition metal catalysis is difficult, and only a few methods for the synthesis of aryl fluorides have been developed. All reported transition-metal-catalyzed fluorination reactions for the synthesis of functionalized arenes are based on palladium. Here we present silver catalysis for carbon-fluorine bond formation. Our report is the first example of the use of the transition metal silver to form carbon-heteroatom bonds by cross-coupling catalysis. The functional group tolerance and substrate scope presented here have not been demonstrated for any other fluorination reaction to date.

  14. Stable palladium alloys for diffusion of hydrogen

    NASA Technical Reports Server (NTRS)

    Patapoff, M.

    1973-01-01

    Literature search on hydrogen absorption effect on palladium alloys revealed existence of alloy compositions in which alpha--beta transition does not take place. Survey conclusions: 40 percent gold alloy of palladium should be used in place of palladium; alloy must be free of interstitial impurities; and metallic surfaces of tube must be clean.

  15. 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.

  16. 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.

  17. Photoluminescent Response of Palladium-Cadmium Sulfide and Palladium-Graded Cadmium Sulfoselenide Schottky Diodes to Molecular Hydrogen.

    DTIC Science & Technology

    2014-09-26

    assistance - and helpful discussions. 8 Re ferences 1. Hollingsworth, R. E.; Sites, J. R. 3. Appi . Phys. 1982, 53, 5357 and references therein. 2. Hobson...W. S.; Ellis, A. B. J. Ap. Phys. 1983, 54, 5956 and references therein. 3. Mettler, K. Appi . Phys. 1977, 12, 75. 4. Stephens, R. B. Phys. Rev.. B...1984, 29, 3283. 5. Steele, M. C.; Maclver, B. A. Appi . Phys. Lett. 1976, 28, 687. 6. Yamamoto, N.; Tonomura, S.; Matsuoka-, T.; Tsubomura, H. Surf. Sci

  18. 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)

  19. Determination of cadmium and lead in edible oils by electrothermal atomic absorption spectrometry after reverse dispersive liquid-liquid microextraction.

    PubMed

    López-García, Ignacio; Vicente-Martínez, Yesica; Hernández-Córdoba, Manuel

    2014-06-01

    The dispersive liquid-liquid microextraction of edible oils with a low volume of an acidic solution in the presence of isopropyl alcohol allows cadmium and lead to be completely separated into the aqueous phase. After centrifugation, the metals are determined by electrothermal atomization atomic absorption spectrometry using a palladium salt for chemical modification in the heating cycle. Using a 10 g oil sample, the enrichment factor is 140, which permits detection limits of 0.6 and 10 ng kg(-1) for cadmium and lead, respectively. The results agree with those obtained after sample mineralization. Data for the cadmium and lead levels for 15 samples of different characteristics are given.

  20. 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.

  1. Cadmium and the kidney.

    PubMed Central

    Friberg, L

    1984-01-01

    The paper is a review of certain aspects of importance of cadmium and the kidney regarding the assessment of risks and understanding of mechanisms of action. The review discusses the following topics: history and etiology of cadmium-induced kidney dysfunction and related disorders; cadmium metabolism, metallothionein and kidney dysfunction; cadmium in urine as indicator of body burden, exposure and kidney dysfunction; cadmium levels in kidney and liver as indicators of kidney dysfunction; characteristics of early kidney dysfunction; the critical concentration concept; critical concentrations of cadmium in kidney cortex; and prognosis. PMID:6734547

  2. 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.

  3. 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}.

  4. Cadmium and zinc relationships.

    PubMed

    Elinder, C G; Piscator, M

    1978-08-01

    Cadmium and zinc concentrations in kidney and liver have been measured under different exposure situations in different species including man. The results show that zinc increases almost equimolarly with cadmium in kidney after long-term low-level exposure to cadmium, e.g., in man, horse, pig, and lamb. In contrast, the increase of zinc follows that of cadmium to only a limited extent, e.g., in guinea pig, rabbit, rat, mouse, and chicks. In liver, the cadmium--zinc relationship seems to be reversed in such a way that zinc increases with cadmium more markedly in laboratory animals than in higher mammals. These differences between cadmium and zinc relationships in humans and large farm animals and those in commonly used laboratory animals must be considered carefully before experimental data on cadmium and zinc relationships in laboratory animals can be extrapolated to humans.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. Tensile properties of palladium-silver alloys with absorbed hydrogen

    NASA Technical Reports Server (NTRS)

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

    1975-01-01

    The alloys 90Pd-10Ag, 80Pd-20Ag, 70Pd-30Ag, 60Pd-40Ag, and 50Pd-50Ag containing absorbed hydrogen were tested in tension. The results show the tensile properties to be independent of the phase transition. Also, hydrogen in the lattice does not necessarily cause embrittlement or poor elongation. The changes in the tensile properties appear dependent on the electron to atom site ratio.

  11. 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.

  12. High-Spin States in PALLADIUM-107, PALLADIUM-108 and SILVER-109.

    NASA Astrophysics Data System (ADS)

    Pohl, Kenneth R.

    1995-01-01

    High-spin states in ^{107,108 }Pd and ^{109}Ag have been studied by charged-particle-gamma , gamma-gamma , and charged-particle-gamma -gamma coincidence measurements of heavy-ion fusion-evaporation reactions. Charged-particle -gamma measurements of gamma -ray spectra, angular distributions, and excitation functions were performed using an ^{18 }O beam with an enriched ^{96 }Zr target at beam energies of 56, 63, 72, and 80 MeV. Background measurements were performed using a ^{rm nat}Zr target. Charged -particle-gamma-gamma measurements using the same reaction at beam energies of 70 and 60 MeV were used to measure gamma -gamma coincidences, coincidence intensities, and gated angular distributions. A gamma-gamma measurement using the reaction ^{100}Mo( ^{13}C,p3n)^ {109}Ag at E_{BEAM } = 65 MeV was performed to measure a low-energy transition in ^{109}Ag. Partial level schemes of ^{107,108 }Pd and ^{109}Ag were constructed from the gamma- gamma coincidence measurements. These levels schemes significantly extend the known high-spin decay patterns of ^{107}Pd and ^{108}Pd. The ^{109}Ag results represent the first measurement of high-spin states in that nuclide. New collective bands have been discovered in all three nuclides. The principal bands in each exhibit the general property of back-bends corresponding to the rotational alignment of a pair of h_{11over2 } quasi-neutrons. Rotational alignments and Routhians have been compared to predictions of the cranked shell model and total Routhian surface calculations. Transition properties in ^{107}Pd and ^{109}Ag have been compared to predictions of a geometrical model in the context of the cranked shell model.

  13. Observations on Gold-Palladium-Silver and Gold-Palladium Alloys,

    DTIC Science & Technology

    1979-02-07

    over a one—inch gauge length with a breakaway ex— tensometer .~ 4- All hardness (DPN) values were obtained through the use of a testing machine~~ and a...structures of all three materials exhibit striking similarities with respect to average grain size and grain configuration. This, in part , may account

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. Palladium on plastic substrates for plasmonic devices.

    PubMed

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

    2015-01-09

    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.

  19. 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.

  20. 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

  1. 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.

  2. Russell-Silver syndrome

    MedlinePlus

    Silver-Russell syndrome; Silver syndrome; RSS; Russell-Silver syndrome ... Organization for Rare Disorders -- rarediseases.org/rare-diseases/russell-silver-syndrome NIH/NLM Genetics Home Reference -- ghr. ...

  3. 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.

  4. Antibacterial Silver

    PubMed Central

    Clement, Julia L.; Jarrett, Penelope S.

    1994-01-01

    The antibacterial activity of silver has long been known and has found a variety of applications because its toxicity to human cells is considerably lower than to bacteria. The most widely documented uses are prophylactic treatment of burns and water disinfection. However, the mechanisms by which silver kills cells are not known. Information on resistance mechanisms is apparently contradictory and even the chemistry of Ag+ in such systems is poorly understood. Silver binds to many cellular components, with membrane components probably being more important than nucleic acids. It is difficult to know whether strong binding reflects toxicity or detoxification: some sensitive bacterial strains have been reported as accumulating more silver than the corresponding resistant strain, in others the reverse apparently occurs. In several cases resistance has been shown to be plasmid mediated. The plasmids are reported as difficult to transfer, and can also be difficult to maintain, as we too have found. Attempts to find biochemical differences between resistant and sensitive strains have met with limited success: differences are subtle, such as increased cell surface hydrophobicity in a resistant Escherichia coli. Some of the problems are due to defining conditions in which resistance can be observed. Silver(I) has been shown to bind to components of cell culture media, and the presence of chloride is necessary to demonstrate resistance. The form of silver used must also be considered. This is usually water soluble AgNO3, which readily precipitates as AgCl. The clinically preferred compound is the highly insoluble silver sulfadiazine, which does not cause hypochloraemia in burns. It has been suggested that resistant bacteria are those unable to bind Ag+ more tightly than does chloride. It may be that certain forms of insoluble silver are taken up by cells, as has been found for nickel. Under our experimental conditions, silver complexed by certain ligands is more cytotoxic

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  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. 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.

  12. 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.

  13. Nonstoichiometry of crystalline cadmium selenide

    SciTech Connect

    Kharif, Ya.L.; Brezhnev, V.Yu.; Kovtunenko, P.V.

    1987-08-01

    A highly sensitive physicochemical method is developed for determining the cadmium concentration (10/sup -5/ at. % for a 10 g sample weight), dissolved in cadmium selenide. The nonstoichiometry of cadmium selenide crystals is studied after high-temperature annealing at 870-1370/sup 0/K in cadmium vapor. For the first time, it is discovered that in the investigated crystals the dissolved cadmium exists primarily in the form of electrically neutral defects, which are presumably clusters of selenium vacancies with low mobility.

  14. 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

  15. Palladium Implanted Silicon Carbide for Hydrogen Sensing

    NASA Technical Reports Server (NTRS)

    Muntele, C. I.; Ila, D.; Zimmerman, R. L.; Muntele, L.; Poker, D. B.; Hensley, D. K.; Larkin, David (Technical Monitor)

    2001-01-01

    Silicon carbide is intended for use in fabrication of high-temperature, efficient hydrogen sensors. Traditionally, when a palladium coating is applied on the exposed surface of SiC, the chemical reaction between palladium and hydrogen produces a detectable change in the surface chemical potential. We have produced both a palladium coated SiC as well as a palladium, ion implanted SiC sensor. The palladium implantation was done at 500 C into the Si face of 6H, N-type SiC at various energies, and at various fluences. Then, we measured the hydrogen sensitivity response of each fabricated sensor by exposing them to hydrogen while monitoring the current flow across the p-n junction(s), with respect to time. The sensitivity of each sensor was measured at temperatures between 27 and 300 C. The response of the SiC sensors produced by Pd implantation has revealed a completely different behaviour than the SiC sensors produced by Pd deposition. In the Pd-deposited SiC sensors as well as in the ones reported in the literature, the current rises in the presence of hydrogen at room temperature as well as at elevated temperatures. In the case of Pd-implanted SiC sensors, the current decreases in the presence of hydrogen whenever the temperature is raised above 100 C. We will present the details and conclusions from the results obtained during this meeting.

  16. Infrared birefringence spectra for cadmium sulfide and cadmium selenide.

    PubMed

    Chenault, D B; Chipman, R A

    1993-08-01

    Measurements of the birefringence spectra for cadmium sulfide and cadmium selenide from 2.5 to 16.5µm obtained with a rotating sample spectropolarimeter are presented. Because of the similarity in the birefringence spectra for cadmium sulfide and cadmium selenide, a highly achromatic IR retarder can be constructed from a combination of these materials. The ordinary and extraordinary refractive indices for cadmium sulfide are estimated in the region from 10.6 to 15 µm and for cadmium selenide from 10.6 to 16.5 µm by combining these birefringence data with an extrapolation of previous dispersion relations.

  17. 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.

  18. 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

  19. 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.

  20. 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

  1. 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.

  2. Synthesis of palladium nanoparticles by sonochemical reduction of palladium(II) nitrate in aqueous solution.

    PubMed

    Nemamcha, Abderrafik; Rehspringer, Jean-Luc; Khatmi, Djameledine

    2006-01-12

    The sonochemical synthesis of stable palladium nanoparticles has been achieved by ultrasonic irradiation of palladium(II) nitrate solution. The starting solutions were prepared by the addition of different concentrations of palladium(II) nitrate in ethylene glycol and poly(vinylpyrrolidone) (PVP). The resulting mixtures were irradiated with ultrasonic 50 kHz waves in a glass vessel for 180 min. The UV-visible absorption spectroscopy and pH measurements revealed that the reduction of Pd(II) to metallic Pd has been successfully achieved and that the obtained suspensions have a long shelf life. The protective effect of PVP was studied using Fourier transform infrared (FT-IR) spectroscopy. It has been found that, in the presence of ethylene glycol, the stabilization of the nanoparticles results from the adsorption of the PVP chain on the palladium particle surface via the coordination of the PVP carbonyl group to the palladium atoms. The effect of the initial Pd(II) concentration on the Pd nanoparticle morphology has been investigated by transmission electron microscopy. It has been shown that the increase of the Pd(II)/PVP molar ratio from 0.13 x 10(-3) to 0.53 x 10(-3) decreases the number of palladium nanoparticles with a slight increase in particle size. For the highest Pd(II)/PVP value, 0.53 x 10(-3), the reduction reaction leads to the unexpected smallest nanoparticles in the form of aggregates.

  3. 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.

  4. Palladium-catalyzed substitution of allylic fluorides.

    PubMed

    Hazari, Amaruka; Gouverneur, Véronique; Brown, John M

    2009-01-01

    As unusual substrates for the Tsuji-Trost allylation reaction, allylic fluorides are responsive to palladium-catalyzed substitution. Their activity towards this reaction fits in the series OCO(2)Me>OBz>F>OAc. The classic stereoretention mechanism that involves sequential inversions does not operate in this case. Several distinct cases are considered.

  5. 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…

  6. Structure of doubly-even cadmium nuclei studied by βdecay

    NASA Astrophysics Data System (ADS)

    Rinta-Antila, S.; Wang, Y.; Dendooven, P.; Huikari, J.; Jokinen, A.; Kankainen, A.; Kolhinen, V. S.; Lhersonneau, G.; Nieminen, A.; Nummela, S.; Penttilä, H.; Peräjärvi, K.; Szerypo, J.; Wang, J. C.; Äystö, J.

    2005-09-01

    We have studied the structure of even-even cadmium isotopes via beta decay of ground and excited isomeric states of parent silver isotopes. Measurements of mass A = 116, 118 and 120 cadmium nuclides were carried out at an ion guide isotope separation on-line facility at the University of Jyväskylä. Decay schemes of 116mAg, 118mAg, 120gAg and 120mAg are considerably extended. Obtained data have enabled extension of available systematics of the three-phonon states to more neutron-rich cadmium nuclei. As a continuation we have conducted an experiment at ISOLDE, CERN to study heavier A = 122, 124, and 126 cadmium nuclides, the analysis of the collected data is underway.

  7. Preparation of 103Pd seed-molecular plating of 103Pd onto silver rod.

    PubMed

    Zhang, Chunfu; Wang, Yongxian; Tian, Haibin; Yin, Duanzhi

    2002-09-01

    A method for 103Pd "molecular plating" onto the surface of a silver rod is reported. The optimal composition of the plating bath is as follows: palladium chloride 0.1 mol/l, formaldehyde 2 mol/l, nitric acid 1 mol/l, and formic acid 0.4 mol/l. The 103Pd molecular plating procedure will last 25 min at 30 degrees C. This article provides a valuable experience for the preparation of 103Pd brachytherapy seed.

  8. Cadmium in the aquatic environment

    SciTech Connect

    Nriagu, J.O.; Sprague, J.B.

    1987-01-01

    This volume presents a comprehensive account of current research on the chemistry and toxicology of cadmium in natural waters. The first four chapters focus on the sources (natural vs. anthropogenic), behavior, and fate of cadmium in natural waters. These are followed by three chapters on the biocycling and effects of cadmium on freshwater biota. The ecotoxicity of cadmium to marine biota are covered by the next two chapters. The final chapter presents a succinct review of the analytical chemistry of cadmium in natural waters.

  9. The reactions of palladium(II), thallium(III) and lead(IV) trifluoroacetates with 3beta-acetoxyandrost-5-en-17-one: crystal structure of the first trifluoroacetate bridged 5,6,7-pi-allyl steroid palladium dimer.

    PubMed

    Ruddock, Peter L; Williams, David J; Reese, Paul B

    2004-03-01

    A number of metal trifluoroacetates were reacted with the olefin 3beta-acetoxyandrost-5-en-17-one (6). Palladium(II) trifluoroacetate afforded bis[micro-trifluoroacetato(alpha-5,7-eta-3beta-acetoxyandrostenyl-17-one)palladium(II)] (20), a new ring B pi-allyl steroid-palladium complex, in quantitative yield. Thallium(III) trifluoroacetate gave 3beta-acetoxy-5alpha-hydroxy-6beta-trifluoroacetoxyandrostan-17-one (16), 3beta-acetoxy-6beta-trifluoroacetoxyandrost-4-en-17-one (9), 3beta-acetoxy-4beta-trifluoroacetoxyandrost-5-en-17-one (10), and 3beta-acetoxy-5alpha,6beta-dihydroxyandrostan-17-one (17). Lead(IV) trifluoroacetate yielded 9, 10 and 16. 3beta-Acetoxy-5alpha,6beta-bis(trifluoroacetoxy)androstan-17-one (15), a new compound, was also formed in this reaction. During the course of the lead(IV) studies the dichlorosteroid 21 and the rearranged allylic oxidation product 24 were formed. Their formation was attributed to the generation of lead(IV) chloride in the reaction. Silver(I) and copper(II) trifluoroacetates proved to be unreactive towards 6.

  10. Recent Development of Palladium-Supported Catalysts for Chemoselective Hydrogenation.

    PubMed

    Monguchi, Yasunari; Ichikawa, Tomohiro; Sajiki, Hironao

    2017-01-01

    This paper describes practical and selective hydrogenation methodologies using heterogeneous palladium catalysts. Chemoselectivity develops dependent on the catalyst activity based on the characteristic of the supports, derived from structural components, functional groups, and/or morphologies. We especially focus on our recent development of heterogeneous palladium catalysts supported on chelate resin, ceramic, and spherically shaped activated carbon. In addition, the application of flow technology for chemoselective hydrogenation using the palladium catalysts immobilized on molecular sieves 3A and boron nitride is outlined.

  11. Cadmium sulphide solar cell

    SciTech Connect

    Bassett, P.J.; Verheijen, A.W.

    1984-07-31

    The invention relates to the manufacture of cadmium sulphide solar cells. A cell is formed of a glass substrate 10, a front contact 12 made, for example, of tin oxide, a cadmium sulphide layer 14 and a copper sulphide layer 16, the junction between the layers 14 and 16 is photovoltaic. In order to form a rear contact 18 on the copper sulphide layer, the invention proposes vapor depositing a mixed layer of copper and copper oxide onto the sulphide layer. The invention also describes a method of heat treatment following the formation of the rear contact in order to optimise the electrical performance of the cell.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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)

  17. Cadmium plating replacements

    SciTech Connect

    Nelson, M.J.; Groshart, E.C.

    1995-03-01

    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.

  18. 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.

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

    SciTech Connect

    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 material 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.

  20. 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

  1. Characterization of hydrogen responsive nanoporous palladium films synthesized via a spontaneous galvanic displacement reaction.

    PubMed

    Patton, J F; Lavrik, N V; Joy, D C; Hunter, S R; Datskos, P G; Smith, D B; Sepaniak, M J

    2012-11-23

    A model is presented regarding the mechanistic properties associated with the interaction of hydrogen with nanoporous palladium (np-Pd) films prepared using a spontaneous galvanic displacement reaction (SGDR), which involves PdCl(2) reduction by atomic Ag. Characterization of these films shows both chemical and morphological factors, which influence the performance characteristics of np-Pd microcantilever (MC) nanomechanical sensing devices. Raman spectroscopy, uniquely complemented with MC response profiles, is used to explore the chemical influence of palladium oxide (PdO). These combined techniques support a reaction mechanism that provides for rapid response to H(2) and recovery in the presence of O(2). Post-SGDR processing via reduction of PdCl(2)(s) in a H(2) environment results in a segregated nanoparticle three-dimensional matrix dispersed in a silver layer. The porous nature of the reduced material is shown by high resolution scanning electron microscopy. Extended grain boundaries, typical of these materials, result in a greater surface area conducive to fast sorption/desorption of hydrogen, encouraged by the presence of PdO. X-ray diffraction and inductively coupled plasma-optical emission spectroscopy are employed to study changes in morphology and chemistry occurring in these nanoporous films under different processing conditions. The unique nature of chemical/morphological effects, as demonstrated by the above characterization methods, provides evidence in support of observed nanomechanical response/recovery profiles offering insight for catalysis, H(2) storage and improved sensing applications.

  2. 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?

  3. The semiconductivity and stability of palladium oxide

    NASA Technical Reports Server (NTRS)

    Rey, E.; Miles, R. B.; Royce, B. S. H.; Kamal, M. R.

    1978-01-01

    Palladium metal films are prepared on quartz substrates by RF sputtering from a pure palladium target in an argon atmosphere. These films are then oxidized in air or in an oxygen atmosphere at 700 C for periods between 24 hr and 6 days. Either treatment is found to produce good-quality thin films of PdO with a uniform orange transmission. Attention is focused on optical and electrical conductivity measurements made on PdO films with a view toward determining their band gap, conductivity and thermal stability in vacuum and in the presence of oxygen. It is shown that hydrogen greatly reduces the thermal stability of PdO. The film decomposes to Pd metal by 350 K in the presence of hydrogen as compared to a temperature of about 580 K in vacuum.

  4. 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.

  5. Online sensing of palladium in flowing streams.

    PubMed

    Bu, Xiaodong; Williams, Michael; Jo, Junyong; Koide, Kazunori; Welch, Christopher J

    2017-01-05

    Rapid palladium (Pd) catalyzed deallylation of an uncoloured reagent within a flowing stream affords a dose dependent colour formation that can be used for convenient online analysis of trace levels of Pd contamination using a modified HPLC instrument. An application to the online sensing of Pd breakthrough from a flow through Pd adsorption cartridge is described. An alternative configuration of the instrumentation allows the rapid (<1 min) and accurate measurement of Pd levels within samples injected via a conventional HPLC autosampler.

  6. Palladium-catalyzed asymmetric quaternary stereocenter formation.

    PubMed

    Gottumukkala, Aditya L; Matcha, Kiran; Lutz, Martin; de Vries, Johannes G; Minnaard, Adriaan J

    2012-05-29

    An efficient palladium catalyst is presented for the formation of benzylic quaternary stereocenters by conjugate addition of arylboronic acids to a variety of β,β-disubstituted carbocyclic, heterocyclic, and acyclic enones. The catalyst is readily prepared from PdCl(2), PhBOX, and AgSbF(6), and provides products in up to 99% enantiomeric excess, with good yields. Based on this strategy, (-)-α-cuparenone has been prepared in only two steps.

  7. 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.

  8. Palladium-Catalyzed, Enantioselective Heine Reaction

    PubMed Central

    2016-01-01

    Aziridines are important synthetic intermediates for the generation of nitrogen-containing molecules. N-Acylaziridines undergo rearrangement by ring expansion to produce oxazolines, a process known as the Heine reaction. The first catalytic, enantioselective Heine reaction is reported for meso-N-acylaziridines where a palladium(II)–diphosphine complex is employed. The highly enantioenriched oxazoline products are valuable organic synthons and potential ligands for transition-metal catalysis. PMID:27398262

  9. Palladium-Catalyzed, Enantioselective Heine Reaction.

    PubMed

    Punk, Molly; Merkley, Charlotte; Kennedy, Katlyn; Morgan, Jeremy B

    2016-07-01

    Aziridines are important synthetic intermediates for the generation of nitrogen-containing molecules. N-Acylaziridines undergo rearrangement by ring expansion to produce oxazolines, a process known as the Heine reaction. The first catalytic, enantioselective Heine reaction is reported for meso-N-acylaziridines where a palladium(II)-diphosphine complex is employed. The highly enantioenriched oxazoline products are valuable organic synthons and potential ligands for transition-metal catalysis.

  10. Organometallic Palladium Reagents for Cysteine Bioconjugation

    PubMed Central

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

    2015-01-01

    Transition-metal based reactions have found wide use in organic synthesis and are used frequently to functionalize small molecules.1,2 However, there are very few reports of using transition-metal based reactions to modify complex biomolecules3,4, 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 biopolymers. Here we report that palladium(II) complexes can be used for efficient and highly selective cysteine conjugation reactions. The bioconjugation reaction is rapid and robust under a range of biocompatible 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 new bioconjugation platform was further corroborated by the synthesis of new classes of stapled peptides and antibody-drug conjugates. These palladium complexes show potential as a new set of benchtop reagents for diverse bioconjugation applications. PMID:26511579

  11. Organometallic palladium reagents for cysteine bioconjugation

    NASA Astrophysics Data System (ADS)

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

    2015-10-01

    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.

  12. Mechanism of action of a palladium modifier

    NASA Astrophysics Data System (ADS)

    L'vov, Boris V.

    2000-11-01

    The mechanism of low-temperature migration of analytes onto a palladium modifier and the mechanism of analyte retention on palladium in the pyrolysis stage have been interpreted on the basis of the method of absolute reaction rates and the mechanism of dissociative evaporation of solids. As has been shown previously by the author, the decomposition of solids, in particular, metal nitrates, occurs through the congruent gasification of all reaction products, irrespective of their saturated pressure (with the simultaneous condensation of low-volatility species). In the interval between gasification and condensation, these species could diffuse for some distance from the primary site. An application of the method of absolute reaction rates (the Hertz-Langmuir vaporization models) to the kinetics of analyte release in the presence of a palladium modifier permits the interpretation of the retention mechanism as dissociative chemisorption. The experimental data from the literature (the appearance temperatures and activation energies for Ag, As, Au, Bi, Cd, Cu, Se and Tl) were used in these calculations.

  13. 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.

  14. 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.

  15. Method of epitaxially depositing cadmium sulfide

    NASA Technical Reports Server (NTRS)

    Hawrylo, Frank Z. (Inventor)

    1980-01-01

    A single crystal layer of either cadmium sulfide or an alloy of cadmium sulfide and indium phosphide is epitaxially deposited on a substrate of cadmium sulfide by liquid phase epitaxy using indium as the solvent.

  16. Effect of Palladium Form on Tetraphenylborate Decomposition Rate

    SciTech Connect

    Walker, D.D.

    1998-04-28

    Palladium catalyzes the decomposition of tetraphenylborate in alkaline solutions. Researchers postulate several decomposition mechanisms that differ in the form of the palladium catalyst. Potential forms include solid and soluble, different soluble species (such as aqueous or organic soluble), and different oxidation states (i.e., 0, II, and IV). Initial tests measured the reactivity and distribution of four Pd forms in tetraphenylborate slurries.

  17. Palladium/Copper-Cocatalyzed Oxidative Amidobrominations of Alkenes.

    PubMed

    Chen, Xiao Yun; Bohmann, Rebekka Anna; Wang, Long; Dong, Shunxi; Räuber, Christoph; Bolm, Carsten

    2015-07-13

    In the presence of LiBr, a palladium/copper combination catalyzes dehydrogenative amidobrominations of acrylates with NH-sulfoximines, leading to N-vinylated products by dual NH/CH coupling, followed by oxidative enamide bromination. Mechanistically, the domino process is proposed to involve palladium(II) species as key intermediates. First synthetic applications of the products have been demonstrated.

  18. An improved palladium-based DMFCs cathode catalyst.

    PubMed

    Li, Huanqiao; Xin, Qin; Li, Wenzhen; Zhou, Zhenhua; Jiang, Luhua; Yang, Shaohua; Sun, Gongquan

    2004-12-07

    A novel carbon-supported palladium-rich Pd3Pt1/C catalyst prepared by a modified polyol process showed a better cell performance than Pt/C in direct methanol fuel cells, which may be attributed to palladium's inactivity to methanol electro-oxidation while exhibiting good performance to oxygen reduction reaction.

  19. The Silver Halides

    ERIC Educational Resources Information Center

    Sahyun, M. R. V.

    1977-01-01

    Illustrates the type of fractional bonding for solid silver halides. Treats the silver halides as electron excess compounds, and develops a model of a localized bonding unit that may be iterated in three dimensions to describe the bulk phase. (MLH)

  20. Cadmium sulfite hexahydrate revisited

    PubMed Central

    Baggio, Sergio; Ibáñez, Andrés; Baggio, Ricardo

    2008-01-01

    The present structural revision of the title compound, tetra­cadmium tetra­sulfite hexa­hydrate, [Cd4(SO3)4(H2O)5]·H2O, is a low-temperature upgrade (T = 100 K and R = 0.017) of the original room-temperature structure reported by Kiers & Vos [Cryst. Struct. Commun. (1978). 7, 399–403; T = 293 K and R = 0.080). The compound is a three-dimensional polymer with four independent cadmium centres, four sulfite anions and six water mol­ecules, five of them coordinated to two cadmium centres and the remaining one an unbound solvent mol­ecule which completes the asymmetric unit. There are two types of cadmium environment: CdO8 (through four chelating sulfite ligands) and CdO6 (by way of six monocoordinated ligands). The former groups form planar arrays [parallel to (001) and separated by half a unit cell translation along c], made up of chains running along [110] and [10], respectively. These chains are, in turn, inter­connected both in an intra­planar as well as in an inter­planar fashion by the latter CdO6 polyhedra into a tight three-dimensional framework. There is, in addition, an extensive network of hydrogen bonds, in which all 12 water H atoms act as donors and eight O atoms from all four sulfite groups and two water mol­ecules act as acceptors. PMID:21202728

  1. 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.

  2. 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.

  3. Scalable synthesis of nanoporous palladium powders.

    SciTech Connect

    Robinson, David B.; Tran, Kim L.; Clift, W. Miles; Arslan Ilke; Langham, Mary Elizabeth; Ong, Markus D.; Fares, Stephen James

    2009-03-01

    Nanoporous palladium powders are synthesized on milligram to gram scales by chemical reduction of tetrachloro complexes by ascorbate in a concentrated aqueous surfactant at temperatures between -20 and 30 C. Particle diameters are approximately 50 nm, and each particle is perforated by 3 nm pores, as determined by electron tomography. These materials are of potential value for storage of hydrogen isotopes and electrical charge; producing them at large scales in a safe and efficient manner will help realize this. A slightly modified procedure also results in nanoporous platinum.

  4. 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.

  5. 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)

  6. 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.

  7. 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.

  8. 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.

  9. Synthesis of silicon oxide nanowires and nanotubes with cobalt-palladium or palladium catalysts

    NASA Astrophysics Data System (ADS)

    Esterina, Ria; Liu, X. M.; Ross, C. A.; Adeyeye, A. O.; Choi, W. K.

    2012-07-01

    The dewetting behaviors of cobalt (Co), cobalt palladium (CoPd), and palladium (Pd) thin films on oxidized silicon substrates were examined. We observed the formation of craters in the oxide layer and pits in the Si substrate for larger CoPd or Pd catalyst particles and thinner oxide. Nanowires and nanotubes were observed near the Si pits. The nanowires and nanotubes grow via a vapor-solid-solid or vapor-liquid-solid mechanism with the silicon vapor source provided from the substrate. The original Si atoms that form the nanowires or nanotubes were oxidized in situ by the residual oxygen atoms present in the chamber. Some of the nanotubes had a series of embedded sub-catalysts that formed branches from the primary nanotube.

  10. SINGLE CRYSTAL CADMIUM SULFIDE AND CADMIUM SELENIDE INSULATED-GATE FIELD-EFFECT TRIODES.

    DTIC Science & Technology

    Insulated-gate field-effect triodes were fabricated on single crystal cadmium sulfide and cadmium selenide . Both bulk crystals and platelets were...used for single crystal samples. Chromium and aluminum were found to make low impedance contacts to cadmium sulfide and cadmium selenide . The...polycrystalline cadmium sulfide and cadmium selenide IGFET’s. The characteristics of the fabricated devices were unstable with respect to time and temperature

  11. 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.

  12. 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.

  13. Nanostructuring of Palladium with Low-Temperature Helium Plasma

    PubMed Central

    Fiflis, P.; Christenson, M.P.; Connolly, N.; Ruzic, D.N.

    2015-01-01

    Impingement of high fluxes of helium ions upon metals at elevated temperatures has given rise to the growth of nanostructured layers on the surface of several metals, such as tungsten and molybdenum. These nanostructured layers grow from the bulk material and have greatly increased surface area over that of a not nanostructured surface. They are also superior to deposited nanostructures due to a lack of worries over adhesion and differences in material properties. Several palladium samples of varying thickness were biased and exposed to a helium helicon plasma. The nanostructures were characterized as a function of the thickness of the palladium layer and of temperature. Bubbles of ~100 nm in diameter appear to be integral to the nanostructuring process. Nanostructured palladium is also shown to have better catalytic activity than not nanostructured palladium. PMID:28347109

  14. Highly efficient palladium-catalyzed hydrostannation of ethyl ethynyl ether.

    PubMed

    Andrews, Ian P; Kwon, Ohyun

    2008-12-08

    The palladium-catalyzed hydrostannation of acetylenes is widely exploited in organic synthesis as a means of forming vinyl stannanes for use in palladium-catalyzed cross-coupling reactions. Application of this methodology to ethyl ethynyl ether results in an enol ether that is challenging to isolate from the crude reaction mixture because of incompatibility with typical silica gel chromatography. Reported here is a highly efficient procedure for the palladium-catalyzed hydrostannation of ethyl ethynyl ether using 0.1% palladium(0) catalyst and 1.0 equiv of tributyltin hydride. The product obtained is a mixture of regioisomers that can be carried forward with exclusive reaction of the beta-isomer. This method is highly reproducible; relative to previously reported procedures, it is more economical and involves a more facile purification procedure.

  15. 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.

  16. 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.

  17. 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.

  18. Synthesis and characterization of nitrides of iridium and palladiums

    SciTech Connect

    Crowhurst, Jonathan C.; Goncharov, Alexander F.; Sadigh, B.; Zaug, J.M.; Aberg, D.; Meng, Yue; Prakapenka, Vitali B.

    2008-08-14

    We describe the synthesis of nitrides of iridium and palladium using the laser-heated diamond anvil cell. We have used the in situ techniques of x-ray powder diffraction and Raman scattering to characterize these compounds and have compared our experimental findings where possible to the results of first-principles theoretical calculations. We suggest that palladium nitride is isostructural with pyrite, while iridium nitride has a monoclinic symmetry and is isostructural with baddeleyite.

  19. 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.

  20. 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.

  1. Influence of casting procedures on the corrosion resistance of clinical dental alloys containing palladium.

    PubMed

    Viennot, Stéphane; Lissac, Michèle; Malquarti, Guillaume; Dalard, Francis; Grosgogeat, Brigitte

    2006-05-01

    The aim of this study was to compare the in vitro corrosion resistance in artificial saliva of two palladium-silver alloys (a Pd-Ag (Pors on 4) and an Ag-Pd (Palliag LTG)), with and without casting defects; 1 nickel-chrome alloy and 1 high-gold alloy, cast under recommended conditions, served as controls. For each of the palladium-based alloys, three specimens corresponding to three different casting conditions were used: under recommended conditions, with the use of a graphite-containing investment and crucible, and by reusing the sprues and sprue button. The electrochemical tests were run in Fusayama-Meyer artificial saliva. The open-circuit potential was recorded in mV/SCE at t=24h. Then, potentiodynamic polarization was performed to measure the polarization resistance (R(p)) in kOmega cm(2) and the corrosion current (i(corr)) in microA cm(-2). Data were evaluated with one-way analysis of variance and multiple comparisons test (alpha=0.05). In addition, each specimen was examined by scanning electron microscopy. Compared to the control alloys, the electrochemical experiments in artificial saliva indicated satisfactory corrosion resistance for the Pd-Ag and Ag-Pd alloys; these results are related to their high noble metal content and stable substructure. The Pd-Ag alloy displayed superior electrochemical properties to those of the Ag-Pd alloy regardless of the casting condition. The use of the graphite-containing crucible and investment during the cast process did not dramatically reduce the corrosion resistance values, but the reuse of sprues and the sprue button did. The optimal corrosion resistance values were obtained for the alloys cast according to the recommended conditions.

  2. 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.

  3. 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.

  4. Time-Dependent Changes in Morphology and Composition of Solid Particles Collected From Heavy Water Electrolyte after Electrolysis with a Palladium Cathode

    NASA Astrophysics Data System (ADS)

    Dash, John; Wang, Q.

    2009-03-01

    Recently, we have observed particles floating on the surfaces of electrolytes after electrolysis, in four cells, each of which contained a heavy water electrolyte and a Pd cathode. Solid particles were unexpected from electrolysis, so it seemed important to characterize these particles. Cu grids were used to collect particles from the electrolyte surface. Then, a scanning electron microscope ( SEM ) and an energy dispersive spectrometer ( EDS ) were used to study the surfaces of these particles and to record time-dependent changes which were occurring. The morphology and composition of the particles were determined . After storage at ambient for 11 days, there were large changes in the morphology and composition of the particles. For example, one portion of the particles contained a large number of microspheres. A typical microsphere contained mostly carbon and palladium, whereas the matrix near the microsphere contained mostly palladium with less carbon and a significant amount of silver. One day later the same microsphere had increased carbon and reduced palladium, but there was no significant change in the composition of the matrix. Results for other particles from other cells will also be presented.

  5. Electronic Transitions of Palladium and Vanadium Dimer

    NASA Astrophysics Data System (ADS)

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

    2013-06-01

    The laser induced fluorescence (LIF) spectrum of palladium dimer (Pd_{2}) in the visible region between 480 and 700 nm has been studied. Five vibrational bands were recorded and analyzed; they are assigned to a ^{3} Π _{g} - X^{3} Σ _{u} ^{+} system. The vibrational frequency of the ground X^{3} Σ _{u} ^{+} state has been determined to be 211.4 cm^{-1}. This is the first experimental observation of the LIF spectrum of Pd_{2}. In addition, the LIF spectrum of vanadium dimer (V_{2}) has also been studied; several new transition band systems were observed in the wavelength between 480 and 530 nm. The analysis of the spectra recorded for these two molecules will be presented.

  6. Palladium-Catalyzed Aminocarbonylation of Allylic Alcohols.

    PubMed

    Li, Haoquan; Neumann, Helfried; Beller, Matthias

    2016-07-11

    A benign and efficient palladium-catalyzed aminocarbonylation reaction of allylic alcohols is presented. The generality of this novel process is demonstrated by the synthesis of β,γ-unsaturated amides including aliphatic, cinnamyl, and terpene derivatives. The choice of ligand is crucial for optimal carbonylation processes: Whereas in most cases the combination of PdCl2 with Xantphos (L6) gave best results, sterically hindered substrates performed better in the presence of simple triphenylphosphine (L10), and primary anilines gave the best results using cataCXium® PCy (L8). The reactivity of the respective catalyst system is significantly enhanced by addition of small amounts of water. Mechanistic studies and control experiments revealed a tandem allylic alcohol amination/C-N bond carbonylation reaction sequence.

  7. 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

  8. 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

  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. 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.

  11. 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…

  12. 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.

  13. Cadmium accumulation and depuration in Anodonta anatina exposed to cadmium chloride or cadmium-EDTA complex

    SciTech Connect

    Holwerda, D.A.; Hemelraad, J.; Veenhof, P.R.; Zandee, D.I.

    1988-03-01

    The authors have previously reported on the uptake and distribution of cadmium in unionids, experimentally exposed to cadmium chloride. The purpose of the present investigation was to study the effect of metal chelation on cadmium kinetics, including metal elimination in the post-exposure phase. Generally, chelation of ionic metal by natural substances like humic acids or by synthetic compounds like EDTA decreases its environmental toxicity through a diminished rate of uptake, as compared with the free ion. The influences of metal chelation on bioconcentration and on toxicity do not always run parallel. To their knowledge, there are no data on the effect of chelation on metal kinetics in freshwater clams. Data on rates of cadmium elimination from aquatic invertebrates are highly divergent, but Cd excretion is invariably found to be smaller than uptake.

  14. 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.

  15. 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.

  16. 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

  17. 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.

  18. 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.

  19. 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.…

  20. 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

  1. 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.

  2. Metallothionein and bioaccumulation of cadmium in juvenile bluegills exposed to aqueous and sediment-associated cadmium

    SciTech Connect

    Cope, W.G.

    1991-01-01

    The author evaluated metallothionein (MT), free (unbound) hepatic cadmium and whole body cadmium as indicators of cadmium exposure in juvenile bluegills Lepomis macrochirus in laboratory tests. Two types of cadmium exposure were tested; aqueous and sediment-associated. In the aqueous tests, fish were exposed to cadmium (0.0 to 32.3 [mu]g/L) in an intermittent-flow diluter. In the sediment-associated cadmium test, fish were exposed to resuspended river sidment containing 1.3 to 21.4 [mu]g Cd/g (dry weight) at a nominal total suspended solids concentration of 1,000 mg/L in revolving, circular glass exposure chambers. Total cadmium concentrations were measured in various bluegill liver fractions, whole bluegill, water, and resuspended sediment to assess the partitioning and bioaccumulation of cadmium after the tests. Mean concentrations of MT and free cadmium in bluegill livers and concentrations of cadmium in whole bluegills were positively correlated with aqueous cadmium concentration and were equally suitable as indicators of aqueous cadmium exposure. Sediment-associated cadmium was biologically available, but to a lesser extent than aqueous cadmium. Cadmium concentrations in whole bluegills exposed to resuspended river sediment were 1.5- to 3.5-fold the concentrations in bluegills in sediment-free controls. Free cadmium and MT concentrations in bluegill liver and whole-body cadmium concentrations in bluegills were positively correlated with the cadmium concentrations in filtered water, resuspended sediment, and bulk river sediment; however, whole-body cadmim concentrations were a more sensitive indicator of exposure to sediment-associated cadmium than either free cadmium or MT concentratons in liver.

  3. 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.

  4. Electrically Conductive Photopatternable Silver Paste for High-Frequency Ring Resonator and Band-Pass Filter

    NASA Astrophysics Data System (ADS)

    Umarji, Govind; Qureshi, Nilam; Gosavi, Suresh; Mulik, Uttam; Kulkarni, Atul; Kim, Taesung; Amalnerkar, Dinesh

    2017-02-01

    In conventional thick-film technology, there are often problems associated with poor edges, rough surfaces, and reproducibility due to process limitations, especially for high-frequency applications. These difficulties can be circumvented by using thin-film technology, but process cost and complexity remain major concerns. In this context, photopatternable thick-film technology can offer a viable alternative due to its Newtonian rheology, which can facilitate formation of the required sharp edges. We present herein a unique attempt to formulate a photopatternable silver paste with organic (photosensitive polymer) to inorganic (silver and glass) ratio of 30:70, developed in-house by us for fabrication of thick-film-based ring resonator and band-pass filter components. The ring resonator and band-pass component structures were realized by exposing screen-printed film to ultraviolet light at wavelength of 315 nm to 400 nm for 30 s to crosslink the photosensitive polymer. The pattern was subsequently developed using 1% sodium carbonate aqueous solution. For comparison, conventional silver and silver-palladium thick films were produced using in-house formulations. The surface topology and microstructural features were examined by stereomicroscopy and scanning electron microscopy. The smoothness and edge definition of the film were assessed by profilometry. The resistivity of the samples was observed and remained in the range from 3.4 μΩ cm to 3.6 μΩ cm. The electrical properties were compared by measuring the insertion loss characteristics. The results revealed that the ring resonator fabricated using the photopatternable silver paste exhibited better high-frequency properties compared with components based on conventional silver or silver-palladium paste, especially in terms of the resonant frequency of 10.1 GHz (versus 10 GHz designed) with bandwidth of 80 MHz. Additionally, the band-pass filter fabricated using the photopatternable silver paste displayed better

  5. The detection of palladium particles in proton exchange membrane fuel-cell water by laser-induced breakdown spectroscopy (LIBS).

    PubMed

    Snyder, Stuart C; Wickun, William G; Mode, Jeremy M; Gurney, Brian D; Michels, Fred G

    2011-06-01

    Laser-induced breakdown spectroscopy (LIBS) using conditional data analysis was applied to aqueous suspensions of palladium particles in the reformate water of palladium-based proton exchange membrane fuel cells. A significant amount of palladium was found in the water, indicating degradation of the fuel-cell cathode catalytic layers. The palladium particle-size detection limit was found to be about 400 nm. Calibration procedures to quantify the palladium concentration are discussed.

  6. FTIR spectroscopic investigations of polyaniline derivatives palladium systems

    NASA Astrophysics Data System (ADS)

    Hasik, M.; Drelinkiewicz, A.; Wenda, E.; Paluszkiewicz, C.; Quillard, S.

    2001-09-01

    Ring-substituted polyaniline derivatives: poly( o-toluidine) (POT) and poly( o-chloroaniline) (POC) have been treated with PdCl 2 solutions in 0.1 and 1 M HCl. Polymer-palladium systems thus obtained have been studied by vibrational spectroscopic methods (MIR, FIR, Raman) and chemical analysis. Results have been compared with those obtained for unsubstituted polyaniline (PANI)-palladium systems prepared under similar experimental conditions as well as for POT, POC, PANI treated with 0.1 and 1 M HCl. It has been found that in all the cases polymers are protonated. Substitution of one hydrogen atom in PANI ring with -Cl and -CH 3 influences the basic and redox properties of the parent polymer The lowest reactivity towards palladium ions has been observed in the case of POC.

  7. 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.

  8. 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.

  9. 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.

  10. Palladium-Catalyzed Arylation of Alkyl Sulfenate Anions.

    PubMed

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

    2015-11-04

    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.

  11. On the structure of small palladium particles

    SciTech Connect

    Herrera, R.; Avalos-Borja, M.; Schabes-Retchkiman, P.; Romeu, D.; Jose-Yacaman, M. . Inst. de Fisica); Ponce, F. )

    1989-09-01

    The study of small noble metal particles is becoming increasingly important in many fields in physics (1). The advent of high-resolution electron microscopy (HREM) has allowed a deeper understanding of structural aspects of small particles. This work reports the study of particles of palladium with a diameter less than 3 nm. Specimens were prepared by in-situ deposition of Pd onto thin carbon films under near-UHV conditions in the specimen preparation chamber. Faulted decahedral MTP was grown using a recursive (R) growth model which generates infinite, space-filling structures reproducing the structure of crystals, twinned particles and quasicrystals. R growth consists of the formation of a cluster by iterative addition of points (atoms) from a given star vector. The method presented sheds some light on a point that has been controversial in the past about the nature of MTP's. Some authors have claimed that these structures can be considered as FCC twins with a disclination to close the resulting gap. The fact that they can be obtained quite simply from stable smaller units appears to make the disclination unnecessary.

  12. Palladium-Catalyzed Arylation of Fluoroalkylamines.

    PubMed

    Brusoe, Andrew T; Hartwig, John F

    2015-07-08

    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.

  13. 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.

  14. 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.

  15. 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.

  16. Determination of the nonstoichiometry of cadmium selenide

    SciTech Connect

    Brezhnev, V.Yu.; Kharif, Ya.L.; Kovtunenko, P.V.

    1986-11-01

    In the annealing of cadmium selenide crystals, cadmium dissolves in the crystals. As a result, their composition deviates from stoichiometry, which affects their electrical conductivity and photosensitivity. In order to obtain crystals with the required properties, it is necessary to determine the amount of dissolved cadmium, i.e., the nonstoichiometry of the crystals. In this paper, the authors experimented with and report on the two methods of extracting dissolved cadmium: recrystallization of the sample by evaporation and condensation; and by creating the conditions for the occurrence of a diffusion stream of cadmium from the bulk to the surface of the crystals.

  17. Nickel cadmium battery expert system

    NASA Astrophysics Data System (ADS)

    1986-11-01

    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.

  18. 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.

  19. 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

  20. 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.

  1. Reduced cadmium body burden in cadmium-exposed calves fed supplemental zinc

    SciTech Connect

    Lamphere, D.N.; Dorn, C.R.; Reddy, C.S.; Meyer, A.W.

    1984-02-01

    The objectives of this study were to evaluate the use of practical supplemental dietary zinc to modify the cadmium content in edible bovine tissues and to identify copper interactions with cadmium and zinc. The effect of supplemental zinc (200 or 600 ..mu..g/g) on the concentrations of cadmium, zinc, and copper in liver, kidney cortex, muscle, and blood of calves fed 50 ..mu..g/g cadmium for 60 days was evaluated. Blood samples were collected before and eight times after starting to feed cadmium or cadmium plus zinc. Liver, kidney, and muscle samples were collected when calves were slaughtered (baseline, at beginning of experimental feeding; cadmium-fed, at end of 60 days feeding). The cadmium concentrations of all sample types collected were markedly increased by the feeding of cadmium. Feeding 600 ..mu..g/g supplemental zinc significantly increased the zinc concentrations of liver, kidney cortex, and blood and decreased the cadmium accumulation in these organs as well as muscle. The copper concentrations of muscle or blood were not altered by feeding cadmium with or without zinc but those of liver and kidney cortex were significantly increased by higher dietary levels of zinc and cadmium. The potential use of dietary zinc salts in reducing cadmium body burden in food animals suspected or known to have high cadmium intakes is suggested.

  2. The ternary system cerium-palladium-silicon

    SciTech Connect

    Lipatov, Alexey; Gribanov, Alexander; Grytsiv, Andriy; Rogl, Peter; Murashova, Elena; Seropegin, Yurii; Giester, Gerald; Kalmykov, Konstantin

    2009-09-15

    Phase relations in the ternary system Ce-Pd-Si have been established for the isothermal section at 800 deg. C based on X-ray powder diffraction and EMPA techniques on about 130 alloys, which were prepared by arc-melting under argon or powder reaction sintering. Eighteen ternary compounds have been observed to participate in the phase equilibria at 800 deg. C. Atom order was determined by direct methods from X-ray single-crystal counter data for the crystal structures of tau{sub 8}-Ce{sub 3}Pd{sub 4}Si{sub 4} (U{sub 3}Ni{sub 4}Si{sub 4}-type, Immm; a=0.41618(1), b=0.42640(1), c=2.45744(7) nm), tau{sub 16}-Ce{sub 2}Pd{sub 14}Si (own structure type, P4/nmm; a=0.88832(2), c=0.69600(2) nm) and also for tau{sub 18}-CePd{sub 1-x}Si{sub x} (x=0.07; FeB-type, Pnma; a=0.74422(5), b=0.45548(3), c=0.58569(4) nm). Rietveld refinements established the atom arrangement in the structures of tau{sub 5}-Ce{sub 3}PdSi{sub 3} (Ba{sub 3}Al{sub 2}Ge{sub 2}-type, Immm; a=0.41207(1), b=0.43026(1), c=1.84069(4) nm) and tau{sub 13}-Ce{sub 3-x}Pd{sub 20+x}Si{sub 6} (0<=x<=1, Co{sub 20}Al{sub 3}B{sub 6}-type, Fm3-barm; a=1.21527(2) nm). The ternary compound Ce{sub 2}Pd{sub 3}Si{sub 3} (structure-type Ce{sub 2}Rh{sub 1.35}Ge{sub 4.65}, Pmmn; a=0.42040(1), b=0.42247(1), c=1.72444(3) nm) was detected as a high-temperature compound, however, does not participate in the equilibria at 800 deg. C. Phase equilibria in Ce-Pd-Si are characterized by the absence of cerium solubility in palladium silicides. Mutual solubility among cerium silicides and cerium-palladium compounds are significant whereby random substitution of the almost equally sized atom species palladium and silicon is reflected in extended homogeneous regions at constant Ce-content such as for tau{sub 2}-Ce(Pd{sub x}Si{sub 1-x}){sub 2} (AlB{sub 2}-derivative type), tau{sub 6}-Ce(Pd{sub x}Si{sub 1-x}){sub 2} (ThSi{sub 2}-type) and tau{sub 7}-CePd{sub 2-x}Si{sub 2+x}. The crystal structures of compounds tau{sub 4}-Ce{sub a}pprox{sub 8}Pd

  3. 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

  4. An Evaluation of the Palladium-Silver Isotope Systematics in the Oldest Differentiated Planetesimal: Beyond Shock

    NASA Astrophysics Data System (ADS)

    Horan, M. F.; Carlson, R. W.; Blichert-Toft, J.

    2012-03-01

    Pd-Ag isotopic systematics in Muonionlusta (Group IVA iron meteorite, troilite Pb-Pb age = 4565.3±0.1 Ma) yield an initial solar system abundance of 107Pd/108Pd of (2.8±0.4) × 10^-^5, despite heterogeneous shock effects in troilite.

  5. 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.

  6. Silver and Gold:Palladium nanoparticles produced by Inert gas condensation

    NASA Astrophysics Data System (ADS)

    Perez-Tijerina, Eduardo; Gracia-Pinilla, Miguel A.; Mejia-Rosales, Sergio; de La Cruz Hernandez, Wencel; Jose-Yacaman, Miguel

    2007-03-01

    We report the synthesis of (AuPd and Ag) metallic nanoparticles (NPs) deposited on silicon and sapphire wafers and TEM grids. The NPs are formed by an inert gas condensation technique, based on dc-magnetron sputtering followed by condensation in high pressure zone. The size of the NPs was controlled through the variation of gas flow (Ar and He) inside the condensation zone, magnetron power, and condensation zone length. The NPs are negatively charged and may therefore be mass selected by a quadrupole mass filter, obtaining the size-distribution of NPs. We performed morphological, structural and composition studies of the NPs by mass spectroscopy, AES, XPS, AFM, UV-Visible spectroscopy, TEM, and HRTEM. Our procedure allows both a remarkable control over average size of the nanoparticles on the sample, and deviations below 5% around this average size.

  7. Sequestration of radioactive iodine in silver-palladium phases in commercial spent nuclear fuel

    SciTech Connect

    Buck, Edgar C.; Mausolf, Edward J.; McNamara, Bruce K.; Soderquist, Chuck Z.; Schwantes, Jon M.

    2016-12-01

    Radioactive iodine is the Achilles’ heel in the design for the safe geological disposal of spent UO2 nuclear fuel. Iodine’s high solubility and anticipated instant release during waste package compromise jeopardize performance assessment calculations. However, dissolution studies have indicated that the instant release fraction (IRF) of radioiodine (I) does not correlate with increasing fuel burn-up. In fact, there is a peak in the release iodine at around 50-60 Mwd/kgU and with increasing burn-up the instant release of iodine decreases. Detailed electron microscopy analysis of high burn-up fuel (~80 MWd/kgU) has revealed the presence of (Pd,Ag)(I,Br) nano-particles. As UO2 fuels are irradiated, the Ag and Pd content increases, from 239Pu fission, enabling radioiodine to be retained. The occurrence of these phases in nuclear fuels may have significant implications for the long-term behavior of iodine.

  8. Twin plane decoration of silver nanorods with palladium by galvanic exchange at a controlled rate.

    PubMed

    Sławiński, Grzegorz W; Ivanova, Olga S; Zamborini, Francis P

    2011-11-01

    Here we describe the galvanic exchange of surface-grown Ag nanorods (NRs) and nanowires (NWs) with PdCl(4)(2-) as a function of the PdCl(4)(2-) concentration. The morphology of the resulting AgPd alloy nanostructures depends on the galvanic exchange rate, which increases with increasing PdCl(4)(2-) concentration over a specific concentration range. When the concentration of PdCl(4)(2-) exceeds 7.5 × 10(-5) M (or ratio of moles of PdCl(4)(2-) in solution to moles of Ag on the surface > 542), rapid galvanic exchange results in Pd deposition over the entire Ag nanostructure in the early stages of exchange. When the concentration of PdCl(4)(2-) is in the range of 1.0 × 10(-5) to 5.0 × 10(-5) M (moles of PdCl(4)(2-) in solution to moles of Ag on the surface = 13-54), Pd deposition occurs preferentially at high energy twin plane defects in the form of well-spaced nanoparticles during the early stages of exchange. In later stages, the Pd deposits grow and coalescence into a rough shell, and etching of the Ag leads to a presumably hollow nanostructure. Composition analysis by linear sweep voltammetry as a function of time shows that the galvanic exchange rate is much slower than the diffusion-limited rate and, when correlated with UV-vis spectroscopy, shows that less than 10% Pd in the nanostructure completely dampens the Ag-localized surface plasmon band.

  9. 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…

  10. 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.

  11. Phyto-crystallization of palladium through reduction process using Cinnamom zeylanicum bark extract.

    PubMed

    Sathishkumar, M; Sneha, K; Kwak, In Seob; Mao, Juan; Tripathy, S J; Yun, Y-S

    2009-11-15

    In this paper we studied the potential of nanocrystalline palladium particle production using Cinnamom zeylanicum bark extract (CBE) as the biomaterial for the first time. We studied the effects of biomaterial dosage, pH and temperature on nanoparticle formation; none of these factors had a major effect on the size and shape of the nanoparticles formed. Transmission electron microscopy (TEM) observations confirmed the synthesis of nano-sized palladium particles. More or less uniformly sized palladium nanoparticles were synthesized with an average size ranging from 15 to 20 nm. It was found that the zeta potential of these formed palladium nanoparticles was negative, and that it increased with an increase in pH. Energy dispersive X-ray (EDX) analysis results confirmed the significant presence of palladium. Of the palladium ions, 60% were reduced to a zero valent form by CBE. Terpenoids are believed to play an important role in palladium nanoparticle biosynthesis through the reduction of palladium ions. Currently, however, the exact mechanism for the synthesis of palladium nanoparticles is unclear. Our protocol for the phyto-synthesis of palladium nanoparticles under moderate pH and room temperature offers a new means to develop environmentally benign nanoparticles.

  12. 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.

  13. 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.

  14. Palladium-catalyzed enantioselective 1,1-fluoroarylation of aminoalkenes.

    PubMed

    He, Ying; Yang, Zhenyu; Thornbury, Richard T; Toste, F Dean

    2015-09-30

    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.

  15. 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.

  16. 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

  17. Palladium(III)-Catalyzed Fluorination of Arylboronic Acid Derivatives

    PubMed Central

    Tang, Pingping; Murphy, Jennifer M.; Ritter, Tobias

    2013-01-01

    A practical, palladium-catalyzed synthesis of aryl fluorides from arylboronic acid derivatives is presented. The reaction is operationally simple and amenable to multi-gram-scale synthesis. Evaluation of the reaction mechanism suggests a single-electron-transfer pathway, involving a Pd(III) intermediate that has been isolated and characterized. PMID:24040932

  18. Palladium(III)-catalyzed fluorination of arylboronic acid derivatives.

    PubMed

    Mazzotti, Anthony R; Campbell, Michael G; Tang, Pingping; Murphy, Jennifer M; Ritter, Tobias

    2013-09-25

    A practical, palladium-catalyzed synthesis of aryl fluorides from arylboronic acid derivatives is presented. The reaction is operationally simple and amenable to multigram-scale synthesis. Evaluation of the reaction mechanism suggests a single-electron-transfer pathway, involving a Pd(III) intermediate that has been isolated and characterized.

  19. Hydrogen storage studies of palladium decorated nitrogen doped graphene nanoplatelets.

    PubMed

    Vinayan, B P; Sethupathi, K; Ramaprabhu, S

    2012-08-01

    Hydrogen storage in materials is of significant importance in the present scenario of depleting conventional energy sources. Porous solids such as activated carbon or nanostructured carbon materials have promising future as hydrogen storage media. The hydrogen storage capacity in nanostructured carbon materials can be further enhanced by atomic hydrogen spillover from a supported catalyst. In the present work, the hydrogen storage properties of nitrogen doped graphene nanoplatelets (N-GNP) and palladium decorated nitrogen doped graphene nanoplatelets (Pd/N-GNP) have been investigated. The results show that hydrogen uptake capacity of nitrogen doped graphene nanoplatelets and palladium decorated nitrogen doped graphene nanoplatelets at pressure 32 bar and temperature 25 degrees C is 0.42 wt% and 1.25 wt% respectively. The dispersion of palladium nanoparticles increases the hydrogen storage capacity of nitrogen doped graphene nanoplatelets by 0.83 wt%. This may be due to high dispersion of palladium nanoparticles and strong adhesion between metal and graphene nanoplatelets over the surface of N-GNP, which enhances the spillover mechanism. Thus, an increase in the hydrogen spillover effect and the binding energy between metal nanoparticles and supporting material achieved by nitrogen doping has been observed to result in a higher hydrogen storage capacity of pristine GNP.

  20. 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

  1. Palladium(II)-catalyzed direct alkenylation of nonaromatic enamides.

    PubMed

    Gigant, Nicolas; Gillaizeau, Isabelle

    2012-07-06

    A mild and efficient method for the direct alkenylation of nonaromatic enamides was achieved through a palladium(II)-catalyzed C-H functionalization. The reaction scope includes cyclic and acyclic enamides and a range of activated alkenes. This approach represents the first successful direct C(3)-functionalization of nonaromatic cyclic enamides.

  2. 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)

  3. Palladium-catalyzed synthesis of functionalized tetraarylphosphonium salts.

    PubMed

    Marcoux, David; Charette, André B

    2008-01-18

    An efficient method to synthesize functionalized tetraarylphosphonium salts is described. This palladium-catalyzed coupling reaction between aryl iodides, bromides, or triflates and triphenylphosphine generates phosphonium salts in high yields. The coupling is compatible with a variety of functional groups such as alcohols, ketones, aldehydes, phenols, and amides.

  4. 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...

  5. Palladium-catalyzed stereocontrolled vinylation of azoles and phenothiazine.

    PubMed

    Lebedev, Artyom Y; Izmer, Vyatcheslav V; Kazyul'kin, Denis N; Beletskaya, Irina P; Voskoboynikov, Alexander Z

    2002-02-21

    [reaction: see text] Vinylation of various azoles (pyrrole, indole, carbazole, and their derivatives) and phenothiazine with vinyl bromides catalyzed by palladium-phosphine complexes results in the respective N-vinylazoles in 30-99% yields. This reaction with cis- and trans-beta-bromostyrenes is stereospecific giving the respective products with full retention of configuration.

  6. 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.

  7. Palladium catalyzed alkoxy- and aminocarbonylation of vinyl tosylates.

    PubMed

    Reeves, Diana C; Rodriguez, Sonia; Lee, Heewon; Haddad, Nizar; Krishnamurthy, Dhileepkumar; Senanayake, Chris H

    2011-05-06

    The palladium catalyzed alkoxycarbonylation and aminocarbonylation of vinyl tosylates are described. A variety of ketone and aldehyde derived vinyl tosylates may be carbonylated in the presence of primary, secondary, and tertiary alcohols, or primary and secondary amines, to provide the corresponding esters and amides in good yields. The alkoxycarbonylation was applied to a short synthesis of isoguvacine.

  8. Mechanisms of cadmium induced genomic instability.

    PubMed

    Filipič, Metka

    2012-05-01

    Cadmium is an ubiquitous environmental contaminant that represents hazard to humans and wildlife. It is found in the air, soil and water and, due to its extremely long half-life, accumulates in plants and animals. The main source of cadmium exposure for non-smoking human population is food. Cadmium is primarily toxic to the kidney, but has been also classified as carcinogenic to humans by several regulatory agencies. Current evidence suggests that exposure to cadmium induces genomic instability through complex and multifactorial mechanisms. Cadmium dose not induce direct DNA damage, however it induces increase in reactive oxygen species (ROS) formation, which in turn induce DNA damage and can also interfere with cell signalling. More important seems to be cadmium interaction with DNA repair mechanisms, cell cycle checkpoints and apoptosis as well as with epigenetic mechanisms of gene expression control. Cadmium mediated inhibition of DNA repair mechanisms and apoptosis leads to accumulation of cells with unrepaired DNA damage, which in turn increases the mutation rate and thus genomic instability. This increases the probability of developing not only cancer but also other diseases associated with genomic instability. In the in vitro experiments cadmium induced effects leading to genomic instability have been observed at low concentrations that were comparable to those observed in target organs and tissues of humans that were non-occupationally exposed to cadmium. Therefore, further studies aiming to clarify the relevance of these observations for human health risks due to cadmium exposure are needed.

  9. Absorbent silver (I) antimicrobial fabrics

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In recent years, silver in form of silver ions, has been gaining importance in the wound management as an effective broad-spectrum antimicrobial agent. Silver has a long history as an antimicrobial agent, especially in the treatment of wounds. Alginates and carboxymethyl (CM) cotton contain carboxyl...

  10. Bioaccumulation of cadmium by growing Zygosaccharomyces rouxii and Saccharomyces cerevisiae.

    PubMed

    Li, Chunsheng; Jiang, Wei; Ma, Ning; Zhu, Yinglian; Dong, Xiaoyan; Wang, Dongfeng; Meng, Xianghong; Xu, Ying

    2014-03-01

    Bioaccumulation via growing cells is a potential technique for heavy metal removal from food materials. The cadmium bioaccumulation characteristics by growing Zygosaccharomyces rouxii and Saccharomyces cerevisiae were investigated. Z. rouxii displayed powerful cadmium removal ability at low cadmium concentrations, which mainly depended on the intracellular cadmium bioaccumulation. The percentage of intracellular cadmium bioaccumulation of both yeasts obviously decreased with the increase of initial biomass and cadmium concentrations. Low pH and elevated concentrations of zinc and copper significantly decreased the intracellular cadmium bioaccumulation of both yeasts but improved the cadmium tolerance and the cell-surface cadmium bioaccumulation of Z. rouxii. Cadmium removal of Z. rouxii was improved by zinc and copper conditionally. Z. rouxii that possessed more powerful cadmium tolerance and removal ability at low pH and high concentration of competing ions can be developed into a potential cadmium removal agent using in complex food environment in future.

  11. 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.

  12. Tunable optical properties of silver-dielectric-silver nanoshell

    NASA Astrophysics Data System (ADS)

    Shirzaditabar, Farzad; Saliminasab, Maryam

    2014-05-01

    Tunable optical properties of silver-dielectric-silver nanoshell including surface plasmon resonance (SPR) and resonance light scattering (RLS) based on quasi-static theory are investigated. When the silver core radius increases, the longer resonance wavelength red shifts and light scattering cross-section decreases whereas the shorter resonance wavelength blue shifts and the light scattering cross-section increases. The effect of middle dielectric thickness on the light scattering cross-section of nanoshell is different from those of the silver core radius changes. As middle dielectric radius increases, the longer resonance wavelength first blue shifts and then red shifts and the light scattering cross-section increases whereas the shorter resonance wavelength always red shifts and the light scattering cross-section decreases. The sensitivity of RLS to the refractive index of embedding medium is also reported. As the silver core radius increases, the sensitivity of silver-dielectric-silver nanoshell decreases whereas increasing the middle dielectric thickness leads to increase the sensitivity of silver-dielectric-silver nanoshell. Tunable optical properties of silver-dielectric-silver nanoshell verify the biosensing potential of this nanostructure.

  13. 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.

  14. Update on Alternatives for Cadmium Coatings on Military Electrical Connectors

    DTIC Science & Technology

    2010-03-01

    established torque/tension requirements) • Shock resistance • Solderability • Temperature resistance • Vibration resistance CCCs are applied over cadmium...Likewise, titanium alloys and Inconel® have been found to be adequate as substrate substitutes for cadmium plated fas- teners5, but these may also...Cadmium LHE Cadmium Titanium Cadmium Titanium Cadmium IVD Aluminum IVD Aluminum Acid Zinc Nickel Acid Zinc Nickel Alkaline Zinc Nickel Alkaline Zinc

  15. 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

  16. 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.

  17. Electrochemical properties of palladium adlayers on Pt(1 0 0) substrates

    NASA Astrophysics Data System (ADS)

    Álvarez, B.; Berná, A.; Rodes, A.; Feliu, J. M.

    2004-12-01

    The formation of submonolayers of palladium on well-defined Pt(1 0 0) electrodes is described. It has been found that the adsorption of NO at open circuit and its further reductive stripping enable the possibility to prepare Pt(1 0 0) electrodes fully covered by the first palladium layer, without contributions coming from palladium in the subsequent layers. This method enables a better characterization of the palladium islands formed in the submonolayer range. The CO displacement method points out that hydrogen and anion adsorption play a role in the charge transfer processes involved in the voltammetric profile. The analysis of the charge-potential curves is used to determine the values of the potentials of zero total charge (pztc) of the different adelectrodes. The pztc diminishes almost linearly with palladium coverage, this shift being related to increasing anion adsorption at low potentials. Adsorbed palladium does not electrocatalyze the oxidation of adsorbed CO.

  18. Characterization of the {beta}-phase of the palladium-hydrogen equation of state

    SciTech Connect

    Fisher, K.J.

    1998-07-01

    The {beta}-phase of the P-C-T curves of the palladium-hydrogen system is encountered at high pressures of gaseous hydrogen and low temperatures of this system. The {beta}-phase is characterized by an increase in the concentration of hydrogen in the palladium lattice with an increase in pressure of the free hydrogen gas surrounding the palladium. The P-C-T curves in this study are determined by gravimetric measurements of the hydrided palladium sample to determine the amount of hydrogen within the palladium lattice. The amount of hydrogen is kept constant within the experimental system and the temperature is varied which changes the pressures. The objective of this experimental thesis is to accurately determine the P-C-T curves of palladium in the {beta}-phase region to pressures of 20,000 psia and medium to low temperature region of {minus}60 C to 100 C.

  19. Cadmium telluride in tellurium—cadmium films consisting of ultradispersed particles

    NASA Astrophysics Data System (ADS)

    Tuleushev, Yu. Zh.; Volodin, V. N.; Migunova, A. A.; Lisitsyn, V. N.

    2015-08-01

    Solid solutions of tellurium in cadmium, cadmium in tellurium, and cadmium in cadmium telluride synthesized during sputtering are formed for the first time by ion-plasma sputtering and the codeposition of ultradispersed Te and Cd particle fluxes onto substrates moving with respect to the fluxes. This fact supports thermofluctuation melting and coalescence of small particles. The lattice parameter of cadmium telluride, which coexists with an amorphous solid solution of tellurium in cadmium in a coating, is smaller than the tabulated value and reaches it when the cadmium concentration in a coating increases to 70 at %. The lattice parameter of the fcc lattice of cadmium telluride increases with the cadmium concentration in a coating according to the linear relation a = 0.0002CCd + 0.6346 nm (where CCd is the cadmium concentration in the coating, at %), which is likely to indicate a certain broadening of the homogeneity area. The estimation of the particle size shows that the cadmium telluride grain size is 10-15 nm, which implies that the coatings are nanocrystalline. The absorption and transmission spectra of the tellurium—cadmium films at the fundamental absorption edge demonstrate that their energy gaps are larger than that of stoichiometric CdTe, which can be explained by the experimental conditions of crystal structure formation.

  20. 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.

  1. 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.

  2. Adhesives, silver amalgam.

    PubMed

    1995-09-01

    The most recent advancement in silver amalgam is use of resin formulations to bond metal to tooth both chemically &/or physically, Since, historically, amalgam has been used successfully without adhesion to tooth, obvious clinical question is: Why is bonding now desirable? Two major clinical reasons to bond are: (1) Adhesive can increase fracture resistance of amalgam restored teeth & decrease cusp fractures; & (2) Seal provided by adhesive can greatly decrease, & often eliminate post-operative sensitivity. Following report summarizes CRA laboratory study of shear bond strength & sealing capability of 23 commercial adhesives used to bond 2 types of silver amalgam to tooth structure.

  3. 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.

  4. Cadmium, A Health Hazard Surface Treatment

    DTIC Science & Technology

    2000-04-01

    of this EEC Directive under German law resulted in the Chemicals Prohibitory Regulation (Chemikalien-Verbotsverordnung). Thus, for example, cadmium...and its alloys must not be marketed pursuant to this EEC Directive and the Chemicals Prohibitory Regulation. However, the present legal situation does...this question and then explain those characteristics of cadmium which are injurious to health in greater detail: Cadmium is a chemical element and is a

  5. Dislocation Etching Solutions for Mercury Cadmium Selenide

    DTIC Science & Technology

    2014-09-01

    Dislocation Etching Solutions for Mercury Cadmium Selenide by Kevin Doyle and Sudhir Trivedi ARL-CR-0744 September 2014...Etching Solutions for Mercury Cadmium Selenide Kevin Doyle and Sudhir Trivedi Sensors and Electron Devices Directorate, ARL prepared by...Solutions for Mercury Cadmium Selenide 5a. CONTRACT NUMBER W811NF-12-2-0019 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) Kevin Doyle and

  6. Mercury Cadmium Selenide for Infrared Detection

    DTIC Science & Technology

    2013-06-01

    REPORT Mercury cadmium selenide for infrared detection 14. ABSTRACT 16. SECURITY CLASSIFICATION OF: Samples of HgCdSe alloys were grown via molecular...NUMBER John Dinan 512-245-6711 3. DATES COVERED (From - To) Standard Form 298 (Rev 8/98) Prescribed by ANSI Std. Z39.18 - Mercury cadmium selenide for...PAGE (SF298) (Continuation Sheet) Continuation for Block 13 ARO Report Number Mercury cadmium selenide for infrared detection Block 13

  7. Structure, energetic and phase transition of small nickel-palladium heterogeneous clusters

    NASA Astrophysics Data System (ADS)

    Hewage, Jinasena W.

    2014-06-01

    Molecular dynamics simulation (MD) with Sutton-Chen potential for palladium-palladium, nickel-nickel and palladium-nickel interactions has been used to generate the minimum energy structures and to study the thermodynamic and dynamic properties of mixed transition metal cluster motifs of Ni n Pd(13- n) for n ≤ 13. Thirteen particle icosahedral clusters of neat palladium and nickel atoms were first reproduced accordingly with the results in literature. Then in the palladium icosahedra, each palladium atom has been successively replaced by nickel atom. Calculation is repeated for both palladium-centered and nickel-centered clusters. It is found that the nickel-centered clusters are more stable than the palladium-centered clusters and cohesive energy increases along the palladium end to nickel end. Phase transition of each cluster from one end-species to the other end-species is studied by means of caloric curve, root mean square bond fluctuation and heat capacity. Trend in variation of melting temperature is opposite to the energy trend. Palladium-centered cluster shows a premelting at low temperature due to the solid-solid structural transition. Species-centric order parameters developed by Hewage and Amar is used to understand the dynamic behavior in the solid-solid transition of palladium-centered cluster to more stable nickel-centered cluster (premelting). This species-centric order parameter calculation further confirmed the stability of nickel-centered species over those of palladium-centered species and solid-solid structural transition at low temperature.

  8. 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.

  9. Palladium-Boron Alloys and Methods for Making and Using Such Alloys

    DTIC Science & Technology

    2000-05-19

    solid solution in the palladium and the alloy having a two-phase structure, wherein each phase of the two-phase structure has the same crystal structure has the other phase and has a different set of lattice parameters from the other phase such that the palladium is greatly hardened by...by a process wherein palladium and an amount of boron sufficient to place the boron in solid solution , but insufficient to combine with the

  10. A Palladium-Binding Deltarhodopsin for Light-Activated Conversion of Protonic to Electronic Currents.

    PubMed

    Soto-Rodríguez, Jessica; Hemmatian, Zahra; Josberger, Erik E; Rolandi, Marco; Baneyx, François

    2016-08-01

    Fusion of a palladium-binding peptide to an archaeal rhodopsin promotes intimate integration of the lipid-embedded membrane protein with a palladium hydride protonic contact. Devices fabricated with the palladium-binding deltarhodopsin enable light-activated conversion of protonic currents to electronic currents with on/off responses complete in seconds and a nearly tenfold increase in electrical signal relative to those made with the wild-type protein.

  11. Process for removing cadmium from scrap metal

    SciTech Connect

    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.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. Toward Financially Viable Phytoextraction and Production of Plant-Based Palladium Catalysts.

    PubMed

    Harumain, Zakuan A S; Parker, Helen L; Muñoz García, Andrea; Austin, Michael J; McElroy, Con Robert; Hunt, Andrew J; Clark, James H; Meech, John A; Anderson, Christopher W N; Ciacci, Luca; Graedel, T E; Bruce, Neil C; Rylott, Elizabeth L

    2017-02-27

    Although a promising technique, phytoextraction has yet to see significant commercialization. Major limitations include metal uptake rates and subsequent processing costs. However, it has been shown that liquid-culture-grown Arabidopsis can take up and store palladium as nanoparticles. The processed plant biomass has catalytic activity comparable to that of commercially available catalysts, creating a product of higher value than extracted bulk metal. We demonstrate that the minimum level of palladium in Arabidopsis dried tissues for catalytic activity comparable to commercially available 3% palladium-on-carbon catalysts was achieved from dried plant biomass containing between 12 and 18 g·kg(-1) Pd. To advance this technology, species suitable for in-the-field application: mustard, miscanthus, and 16 willow species and cultivars, were tested. These species were able to grow, and take up, palladium from both synthetic and mine-sourced tailings. Although levels of palladium accumulation in field-suitable species are below that required for commercially available 3% palladium-on-carbon catalysts, this study both sets the target, and is a step toward, the development of field-suitable species that concentrate catalytically active levels of palladium. Life cycle assessment on the phytomining approaches described here indicates that the use of plants to accumulate palladium for industrial applications has the potential to decrease the overall environmental impacts associated with extracting palladium using present-day mining processes.

  18. 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%.

  19. Optical properties and surface morphology studies of palladium contacts on mercuric iodide single crystals

    NASA Astrophysics Data System (ADS)

    George, M. A.; Azoulay, M.; Burger, A.; Biao, Y.; Silberman, E.; Nason, D.

    1993-04-01

    Palladium is chemically suitable for electric contacts on mercuric iodide detectors for photon and nuclear radiation detection, so the understanding of palladium contacts is important for fundamental and practical scientific purposes. A study has been conducted on the surface morphology of evaporated contacts using atomic force microscopy (AFM) and optical transmission and reflection. Evaporated palladium coatings are typically nonuniform and may deposit selectively on mercuric iodide surface defects. Reflection measurements show that coating thickness and surface treatment affect intensity, position, and shape of a reflected peak characteristic of the mercuric iodide structure. Results indicate that the band gap energy in the surface of the mercuric iodide is lowered by palladium contacts.

  20. 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.

  1. Toxic effects of palladium compounds on the isolated rat heart.

    PubMed

    Perić, Tanja; Jakovljević, Vladimir Lj; Zivkovic, Vladimir; Krkeljic, Jelena; Petrović, Zorica D; Simijonović, Dusica; Novokmet, Slobodan; Djuric, Dragan M; Janković, Slobodan M

    2012-01-01

    Taken into consideration limited data about effects of palladium on cardiovascular system, the aim of our study was to compare toxicity of inorganic and organic palladium compounds on the isolated rat heart. The hearts (total number n=30, 6 for each experimental group) excised from Wistar albino rats, male sex, age 8 weeks, and body mass 180-200 g, were retrogradely perfused according to the Langendorff technique at constant perfusion pressure (70 cm H2O). After the insertion of sensor in the left ventricle, the parameters of heart function: maximum rate of left ventricular pressure development (dP/dt max), systolic left ventricular pressure (SLVP), diastolic left ventricular pressure (DLVP), mean blood pressure (MBP) and heart rate (HR)), were continuously registered. The experiments were performed during control conditions, and in the presence of perfusion with incresing concentration of the following: (triethanolamine (TEA), triethanolamine acetate (TEAA), palladium(II)chloride (PdCl2), and trans-dichlorobis(triethanolamine-N)palladium(II) complex (trans-[PdCl2(TEA)2])) started every 30 minutes (30, 60, 90, 120 minute). dP/dt max was not affected significantly by either TEAA, TEA, PdCl2 or Pd complex. SLVP was, also, not affected significantly by either TEAA, TEA, PdCl2, or Pd complex. DLVP was significantly decreased by both TEAA and PdCl2, while TEA and Pd complex did not show significant effect. MBP was significantly decreased only by PdCl2, while TEAA, TEA and Pd complex did not show significant effect. HR was significantly decreased by all compounds- PdCl2, TEAA, TEA and Pd complex. In our study, inorganic palladium compound (PdCl2) induced clear depression of the isolated rat heart contractility, manifested as drop in diastolic and mean blood pressure , and as decrease of the heart rate. On the other hand, it seems that palladium, when bound in an organic compound (linked to TEA in Pd complex), does not contribute significantly to cardio-toxicity in our

  2. Interpreting NHANES biomonitoring data, cadmium.

    PubMed

    Ruiz, Patricia; Mumtaz, Moiz; Osterloh, John; Fisher, Jeffrey; Fowler, Bruce A

    2010-09-15

    Cadmium (Cd) occurs naturally in the environment and the general population's exposure to it is predominantly through diet. Chronic Cd exposure is a public health concern because Cd is a known carcinogen; it accumulates in the body and causes kidney damage. The National Health and Nutritional Examination Survey (NHANES) has measured urinary Cd; the 2003-2004 NHANES survey cycle reported estimates for 2257 persons aged 6 years and older in the Fourth National Report on Human Exposure to Environmental Chemicals. As part of translational research to make computerized models accessible to health risk assessors we re-coded a cadmium model in Berkeley Madonna simulation language. This model was used in our computational toxicology laboratory to predict the urinary excretion of cadmium. The model simulated the NHANES-measured data very well from ages 6 to 60+ years. An unusual increase in Cd urinary excretion was observed among 6-11-year-olds, followed by a continuous monotonic rise into the seventh decade of life. This observation was also made in earlier studies that could be life stage-related and a function of anatomical and phsysiological changes occurring during this period of life. Urinary excretion of Cd was approximately twofold higher among females than males in all age groups. The model describes Cd's cumulative nature in humans and accommodates the observed variation in exposure/uptake over the course of a lifetime. Such models may be useful for interpreting biomonitoring data and risk assessment.

  3. 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…

  4. 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

  5. Determination of cadmium vapor pressure over dichromium cadmium tetraselenide by the atomic absorption method

    SciTech Connect

    Bel'skii, N.K.; Ochertyanova L.I.; Zhegalinka, V.A.

    1986-07-01

    By the atomic absorption method one measures the light absorption by the vapor of the investigated element as a function of the temperature of the evaporating surface. To measure vapor pressure the authors use cadmium selenide of the purity grade, which was recrystallized by sublimitation. The optical density of the vapor over cadmium selenide was determined in the temperature range 820-890 K. Using atomic spectroscopy the vapor pressure of cadmium over cadmium selenide was determined in dichromium cadmium tetraselenide with different amounts of deviation from stoichiometry at 790-880 deg. The results are compared with the literature data.

  6. 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

  7. Palladium dimers adsorbed on graphene: A DFT study

    NASA Astrophysics Data System (ADS)

    Kaur, Gagandeep; Gupta, Shuchi; Dharamvir, Keya

    2015-05-01

    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 (Pd2) on graphene using SIESTA package, in the generalized gradient approximation (GGA). The adsorption energy, geometry, and charge transfer of Pd2-graphene system are calculated. Both horizontal and vertical orientations of Pd2 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 in cubic silicon carbide: Stability and kinetics

    NASA Astrophysics Data System (ADS)

    Roma, Guido

    2009-12-01

    Several technological applications of silicon carbide are concerned with the introduction of palladium impurities. Be it intentional or not, this may lead to the formation of silicides. Not only this process is not well understood, but the basic properties of palladium impurities in silicon carbide, such as solubility or diffusion mechanisms, are far from being known. Here the stability and kinetics of isolated Pd impurities in cubic silicon carbide are studied by first principles calculations in the framework of density functional theory. The preferential insertion sites, as well as the main migration mechanisms, are analyzed and presented here, together with the results for solution and migration energies. The early stages of nucleation are discussed based on the properties of isolated impurities and the smallest clusters.

  9. 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.

  10. Anomalous transport and possible phase transition in palladium nanojunctions.

    PubMed

    Scott, Gavin D; Palacios, Juan J; Natelson, Douglas

    2010-05-25

    Many phenomena in condensed matter are thought to result from competition between different ordered phases. Palladium is a paramagnetic metal close to both ferromagnetism and superconductivity and is, therefore, a potentially interesting material to consider. Nanoscale structuring of matter can modify relevant physical energy scales, leading to effects such as locally modified magnetic interactions. We present transport measurements in electromigrated palladium break junction devices showing the emergence at low temperatures of anomalous sharp features in the differential conductance. These features appear symmetrically in applied bias and exhibit a temperature dependence of their characteristic voltages reminiscent of a mean-field phase transition. The systematic variation of these voltages with zero bias conductance, together with density functional theory calculations illustrating the relationship between the magnetization of Pd and atomic coordination, suggests that the features may result from the onset of spontaneous magnetization in the nanojunction electrodes. We propose that the characteristic conductance features are related to inelastic tunneling involving magnetic excitations.

  11. 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.

  12. 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.

  13. SRS history and experience with palladium diffusers. Revision 1

    SciTech Connect

    Clark, E.A.; Dauchess, D.A.; Heung, L.K.; Rabun, R.L.; Motyka, T.

    1995-08-11

    The Savannah River Site (SRS) has processed tritium in support of national defense programs since 1955. Palladium diffusers have been used extensively for separating hydrogen isotopes from inert gases (such as argon, helium, and nitrogen). In almost forty years of service, the design of the diffuser has been steadily improving. Several diffuser designs from different manufacturers have been evaluated at SRS. The operating experience gained from these designs together with failure analyses performed on failed units have led to several recommendations for improved diffuser designs and operating methods. This experience gained at SRS and the following recommendations form the basis of this report. Even though palladium diffuser technology has proven to be reliable, SRS has examined several alternative technologies over the past several years. This report will also review some of these promising alternatives.

  14. Complete oxidation of methane on palladium catalysts. Final Report

    SciTech Connect

    Ribeiro, Fabio H.

    2003-07-17

    This is the final report for grant DE-FG02-00ER15026. It summarizes all the accomplishments in these 8 sections: (1) Adaptations on Existing Unit and Construction of New Unit; (2) Turnover Rate and Reaction Orders for the Complete Oxidation of Methane on a Palladium Foil in Excess Dioxygen; (3) Surface area increase on Pd foils after oxidation in excess methane; (4) UV Raman spectroscopic study of hydrogen bonding in gibbsite and bayerite between 93 and 453 K; (5) Coverage of Palladium Catalysts by Oxidized Silicon During Complete Oxidation of Methane; (6) Kinetics of Methane Oxidation under lean conditions over Pd and PdO; (7) An Explanation for the Hysteresis on the Oxidation of Methane; and (8) Structure of Pd(111) after oxidation in O{sub 2}.

  15. Oxidation of hydrogen on palladium: Chemicurrents in the Schottky nanodiode

    NASA Astrophysics Data System (ADS)

    Grankin, D. V.; Styrov, V. V.; Simchenko, S. V.; Grankin, V. P.; Gural'nik, O. A.

    2017-02-01

    The oxidation of hydrogen on palladium was studied by the chemicurrents method using the nanosized catalytic Pd/ n-Si Schottky diode. The chemicurrent was found to be generated when the reactions H2+O2 and H + O + H2 + O2 occurred on the palladium surface, occasionally in the auto-oscillation mode. A model was created that describes the complex kinetic behavior of the reaction. Mathematical modeling was performed and showed the possibility of complex auto-oscillations of chemicurrent similar to those obtained in experiments. The catalytic Schottky nanodiode method was shown to be effective for reaction visualization and can be used as a new physical method for investigating the chemical processes on the catalyst surface.

  16. Study of the interaction of palladium bis(acetylacetonate) with boron trifluoride etherate by IR and UV spectroscopy

    SciTech Connect

    Tkach, V.S.; Ratovskii, G.V.; Dmitrieva, T.V.; Malakhova, N.D.; Shmidt, F.K.

    1985-10-01

    It has been shown in this work that the reaction of palladium bis(acetylacetonate) with boron trifluoride etherate is accompanied by the stepwise intracoordination exchange of acetylacetonato ligands for fluorine between palladium and boron. The process can proceed in two directions, depending on the initial concentration of the palladium complex and the B:Pd atomic ratio in the reaction medium. Different coordination compounds containing boron and palladium, but differing significantly in solubility in organic solvents are, accordingly, obtained.

  17. 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.

  18. Asymmetric Palladium-Catalyzed Directed Intermolecular Fluoroarylation of Styrenes

    PubMed Central

    2015-01-01

    A mild catalytic asymmetric direct fluoro-arylation of styrenes has been developed. The palladium-catalyzed three-component coupling of Selectfluor, a styrene and a boronic acid, provides chiral monofluorinated compounds in good yield and in high enantiomeric excess. A mechanism proceeding through a Pd(IV)-fluoride intermediate is proposed for the transformation and synthesis of an sp3 C–F bond. PMID:24617344

  19. Atomic Mass and Nuclear Binding Energy for Pd-103 (Palladium)

    NASA Astrophysics Data System (ADS)

    Sukhoruchkin, S. I.; Soroko, Z. N.

    This document is part of the Supplement containing the complete sets of data of Subvolume A `Nuclei with Z = 1 - 54' of Volume 22 `Nuclear Binding Energies and Atomic Masses' of Landolt-Börnstein - Group I `Elementary Particles, Nuclei and Atoms'. It provides atomic mass, mass excess, nuclear binding energy, nucleon separation energies, Q-values, and nucleon residual interaction parameters for atomic nuclei of the isotope Pd-103 (Palladium, atomic number Z = 46, mass number A = 103).

  20. Palladium- (and nickel-) catalyzed vinylation of aryl halides†

    PubMed Central

    Denmark, Scott E.; Butler, Christopher R.

    2009-01-01

    Functionalized styrenes are extremely useful building blocks for organic synthesis and for functional polymers. One of the most general syntheses of styrenes involves the combination of an aryl halide with a vinyl organometallic reagent under catalysis by palladium or nickel complexes. This Feature Article provides the first comprehensive summary of the vinylation methods currently available along with a critical comparison of the efficiency, cost and scope of the methods. PMID:19081992

  1. 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.

  2. Unsupported palladium alloy membranes and methods of making same

    DOEpatents

    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.

  3. An Infrared Spectroelectrochemical Study of Cyanide Adsorption on Palladium Surfaces

    DTIC Science & Technology

    1987-01-01

    NUMBER(s) Kevin Ashley, Frederick Weinert, Mahesh G. Samant, H. Seki and M. R. Philpott N00014-82-C-0583 ) PERFORMING ORGANIZATION NAME AND ADDRESS...8217TROELECTROCHEMICAL STUD 01)’ OCY(ANID)E ADSORPTION ON PAL.LADIUMN SUJRFACES hy Kevin Ashley, Frederick WVeinert, Mahiesh C. Simint, Ff. Seki. NI. R...SPECTROELECTROCHEMICAL STUDY OF CYANIDE ADSORPTION ON PALLADIUM SURFACES Kevin Ashley* and Frederick Weinert Department of Chemistry San Jose State

  4. 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

  5. Immunochromatographic assay of cadmium levels in oysters.

    PubMed

    Nishi, Kosuke; Kim, In-Hae; Itai, Takaaki; Sugahara, Takuya; Takeyama, Haruko; Ohkawa, Hideo

    2012-08-15

    Oysters are one of foodstuffs containing a relatively high amount of cadmium. Here we report on establishment of an immunochromatographic assay (ICA) method of cadmium levels in oysters. Cadmium was extracted with 0.l mol L(-1) HCl from oysters and cleaned up from other metals by the use of an anion-exchange column. The behavior of five metals Mn, Fe, Cu, Zn, and Cd was monitored at each step of extraction and clean-up procedure for the ICA method in an inductively coupled plasma-mass spectrometry (ICP-MS) analysis. The results revealed that a simple extraction method with the HCl solution was efficient enough to extract almost all of cadmium from oysters. Clean-up with an anion-exchange column presented almost no loss of cadmium adsorbed on the column and an efficient removal of metals other than cadmium. When a spiked recovery test was performed in the ICA method, the recovery ranged from 98% to 112% with relative standard deviations between 5.9% and 9.2%. The measured values of cadmium in various oyster samples in the ICA method were favorably correlated with those in ICP-MS analysis (r(2)=0.97). Overall results indicate that the ICA method established in the present study is an adequate and reliable detection method for cadmium levels in oysters.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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)

  12. Colorimetric sensing of malathion using palladium-gold bimetallic nanozyme.

    PubMed

    Singh, Shefali; Tripathi, Pranav; Kumar, Nitin; Nara, Seema

    2017-06-15

    In this work, a simple, sensitive and selective label free colorimetric assay using palladium-gold nanorod as nanozyme is reported for malathion detection. Study investigates the peroxidase potential of the nanozyme on colorimetric substrates and explores the effect of selected organophosphates on their enzyme mimetic activity. Palladium-gold nanozyme shows excellent peroxidase mimetic activity with O-phenylenediamine in the presence of hydrogen peroxide. Its Kinetic parameters Km and kcat are better than horseradish peroxidase which makes it a superior enzyme. Nanozyme is stable over a broad temperature range (4-70°C) and shows high peroxidase activity from 2 to 6pH. The peroxidase activity of nanozyme is selectively quenched with increasing concentration of malathion and is the principle of developed assay. Assay has a lowest detection limit of 60ng/ml and shows no cross-reaction with other analogous organophosphates or metal salts. Validation on tap water samples spiked with different concentrations of malathion shows good recovery in the range of 80-106%. Assay also displays good intra and inter-assay precision which lie in the range of 2.7-6.1% and 3.2-5.9% respectively. This study demonstrated the catalytic potential of palladium-gold nanorods, which can be employed as nanozyme for developing highly sensitive detection methods.

  13. An Evaluation of Formic Acid as an Electron Donor for Palladium (PD) Catalyzed Destruction of Nitroaromatic Compounds

    DTIC Science & Technology

    2006-05-31

    AN EVALUATION OF FORMIC ACID AS AN ELECTRON DONOR FOR PALLADIUM (PD) CATALYZED DESTRUCTION OF NITROAROMATIC COMPOUNDS Mark R. Stevens, Capt...AN EVALUATION OF FORMIC ACID AS AN ELECTRON DONOR FOR PALLADIUM (PD) CATALYZED DESTRUCTION OF NITROAROMATIC COMPOUNDS THESIS...UNLIMITED. AFIT/GEM/ENV/04M-19 AN EVALUATION OF FORMIC ACID AS AN ELECTRON DONOR FOR PALLADIUM (PD) CATALYZED DESTRUCTION OF

  14. Novel Cadmium Resistance Determinant in Listeria monocytogenes.

    PubMed

    Parsons, Cameron; Lee, Sangmi; Jayeola, Victor; Kathariou, Sophia

    2017-03-01

    Listeria monocytogenes is a foodborne pathogen that can cause severe disease (listeriosis) in susceptible individuals. It is ubiquitous in the environment and often exhibits resistance to heavy metals. One of the determinants that enables Listeria to tolerate exposure to cadmium is the cadAC efflux system, with CadA being a P-type ATPase. Three different cadA genes (designated cadA1 to cadA3) were previously characterized in L. monocytogenes A novel putative cadmium resistance gene (cadA4) was recently identified through whole-genome sequencing, but experimental confirmation for its involvement in cadmium resistance is lacking. In this study, we characterized cadA4 in L. monocytogenes strain F8027, a cadmium-resistant strain of serotype 4b. By screening a mariner-based transposon library of this strain, we identified a mutant with reduced tolerance to cadmium and that harbored a single transposon insertion in cadA4 The tolerance to cadmium was restored by genetic complementation with the cadmium resistance cassette (cadA4C), and enhanced cadmium tolerance was conferred to two unrelated cadmium-sensitive strains via heterologous complementation with cadA4C Cadmium exposure induced cadA4 expression, even at noninhibitory levels. Virulence assessments in the Galleria mellonella model suggested that a functional cadA4 suppressed virulence, potentially promoting commensal colonization of the insect larvae. Biofilm assays suggested that cadA4 inactivation reduced biofilm formation. These data not only confirm cadA4 as a novel cadmium resistance determinant in L. monocytogenes but also provide evidence for roles in virulence and biofilm formation.IMPORTANCEListeria monocytogenes is an intracellular foodborne pathogen causing the disease listeriosis, which is responsible for numerous hospitalizations and deaths every year. Among the adaptations that enable the survival of Listeria in the environment are the abilities to persist in biofilms, grow in the cold, and tolerate

  15. 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.

  16. Silver ion release from antimicrobial polyamide/silver composites.

    PubMed

    Kumar, Radhesh; Münstedt, Helmut

    2005-05-01

    Silver ion (Ag(+)) the versatile antimicrobial species was released in a steady and prolonged manner from a silver-filled polyamide composite system. Metallic silver powder having varying specific surface area (SSA) has been used as a resource of biocide in polyamide. Strong evidences are found showing the release of the antimicrobial species from the resulting composite upon soaking it in water due to the interaction of the diffused water molecules with the dispersed silver powder within the matrix. The Ag(+) release was observed as increasing with time and concentration of the silver powder and is found to be influenced by the SSA of the silver powder, changes in the physical state of the composite specimen as a result of the water diffusion and the composite morphology. It is observed that the Ag(+) release increases initially which is followed by a marginal increase between day 4 and 6. Composites containing higher amounts of silver (4 and 8 wt%) exhibit a further rise in Ag(+) release from the sixth day of storage in water. Composite containing silver particles with the lowest specific surface area (0.78 m(2)/g) showed highest Ag(+) release. SEM shows a finer dispersion of the silver powder (4 wt%) having lowest SSA. However particles with higher (1.16 and 2.5 m(2)/g) SSA possess an agglomerated morphology leading to lower Ag(+) release. The composites are found to release Ag(+) at a concentration level capable of rendering an antimicrobial efficacy.

  17. 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.

  18. 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.

  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. Infrared cadmium selenide photoconductor and process of making same

    SciTech Connect

    Faria, S.

    1987-02-17

    The process is described of making an infrared responsive cadmium selenide photoconductor comprising the steps of preparing a blend of cadmium selenide, copper-containing cadmium selenide mix and cadmium chloride, and firing the blend at a temperature of about 425/sup 0/C.

  1. 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.

  2. New Palladium-Catalyzed Approaches to Heterocycles and Carbocycles

    SciTech Connect

    Huang, Qinhua

    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 I2, ICl, PhSeCl, PhSCl and p-O2NC6H4SCl 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

  3. Comparative proteome analysis of high and low cadmium accumulating soybeans under cadmium stress.

    PubMed

    Hossain, Zahed; Hajika, Makita; Komatsu, Setsuko

    2012-12-01

    A comparative proteomic study was performed to unravel the protein networks involved in cadmium stress response in soybean. Ten-day-old seedlings of contrasting cadmium accumulating soybean cultivars-Harosoy (high cadmium accumulator), Fukuyutaka (low cadmium accumulator), and their recombinant inbred line CDH-80 (high cadmium accumulator) were exposed to 100 μM CdCl(2) treatment for 3 days. Root growth was found to be affected under cadmium stress in all. Varietal differences at root protein level were evaluated. NADP-dependent alkenal double bond reductase P1 was found to be more abundant in low cadmium accumulating Fukuyutaka. Leaf proteome analysis revealed that differentially expressed proteins were primarily involved in metabolism and energy production. The results indicate that both high and low cadmium accumulating cultivars and CDH-80 share some common defense strategies to cope with the cadmium stress. High abundance of enzymes involved in glycolysis and TCA cycle might help cadmium challenged cells to produce more energy necessary to meet the high energy demand. Moreover, enhanced expressions of photosynthesis related proteins indicate quick utilization of photoassimilates in energy generation. Increased abundance of glutamine synthetase in all might be involved in phytochelatin mediated detoxification of cadmium ions. In addition, increased abundance of antioxidant enzymes, namely superoxide dismutase, ascorbate peroxidase, catalase, ensures cellular protection from reactive oxygen species mediated damages under cadmium stress. Enhanced expression of molecular chaperones in high cadmium accumulating cultivar might be another additional defense mechanism for refolding of misfolded proteins and to stabilize protein structure and function, thus maintain cellular homeostasis.

  4. Palladium deuteride formation in the cathode of an electrochemical cell: An in situ neutron diffraction study

    SciTech Connect

    Rotella, F.J.; Richardson, J.W. Jr.; Redey, L.; Felcher, G.P.; Hitterman, R.L.; Kleb, R.

    1991-12-31

    In this report, neutron diffraction of palladium cathodes is utilized to reveal palladium deuteride formation within the crystal structure of the metal. The experiment described in this report demonstrates the efficacy of neutron powder diffraction as a tool for structural studies of metal deuterides/hydrides and the feasibility of in situ diffraction measurements from a working electrochemical cell. (JL)

  5. Palladium deuteride formation in the cathode of an electrochemical cell: An in situ neutron diffraction study

    SciTech Connect

    Rotella, F.J.; Richardson, J.W. Jr.; Redey, L.; Felcher, G.P.; Hitterman, R.L.; Kleb, R.

    1991-01-01

    In this report, neutron diffraction of palladium cathodes is utilized to reveal palladium deuteride formation within the crystal structure of the metal. The experiment described in this report demonstrates the efficacy of neutron powder diffraction as a tool for structural studies of metal deuterides/hydrides and the feasibility of in situ diffraction measurements from a working electrochemical cell. (JL)

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

    PubMed

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

    2015-11-02

    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.

  7. A facile route for preparing a mesoporous palladium coordination polymer as a recyclable heterogeneous catalyst.

    PubMed

    Zhang, Siyong; Liu, Qinghua; Shen, Ming; Hu, Bingwen; Chen, Qun; Li, Hexing; Amoureux, Jean-Paul

    2012-04-21

    To overcome the separation difficulty of the palladium-based homogeneous catalyst, the palladium complex can be anchored on various supports such as silica, polymers and nanoparticles. For the same purpose, we describe a general and facile method to immobilize palladium bis(phosphine) complexes on the basis of the technique widely used for metal-organic framework (MOF) synthesis, yielding a mesoporous coordination polymer palladium-CP1. Although palladium complexes are generally not stable enough to allow further manipulation, we succeeded in preparation of a palladium coordination polymer without by-product Pd clusters or nanoparticles. The fresh palladium-CP1 catalyst exhibits a yield close to 55% for tolane at room temperature and 24 h in Sonogashira coupling of iodobenzene and phenylacetylene, as compared with a yield of 89% for its homogeneous counterpart [Pd(PPh(3))(2)Cl(2)]. Furthermore, this catalyst is stable enough to be reused more than four times with no Pd and Zn leaching. Therefore this new immobilization method offers great promise for the produce of recyclable palladium heterogeneous catalysts with higher activity and higher thermal and chemical stability in the future.

  8. Palladium-catalyzed carbonylation of o-iodoanilines for synthesis of isatoic anhydrides.

    PubMed

    Gao, Sha; Chen, Ming; Zhao, Mi-Na; Du, Wei; Ren, Zhi-Hui; Wang, Yao-Yu; Guan, Zheng-Hui

    2014-05-02

    A novel palladium-catalyzed oxidative double carbonylation of o-iodoanilines for the synthesis of isatoic anhydrides has been developed. The reaction employs readily available o-iodoanilines as the starting materials and proceeds under mild conditions. For extension, palladium-catalyzed oxidative carbonylation of anthranilic acids was developed for the synthesis of substituted isatoic anhydrides in high to excellent yields.

  9. Palladium-catalyzed allylation of acidic and less nucleophilic anilines using allylic alcohols directly.

    PubMed

    Hsu, Yi-Chun; Gan, Kim-Hong; Yang, Shyh-Chyun

    2005-10-01

    The direct activation of C-O bonds in allylic alcohols by palladium complexes has been accelerated by carrying out the reactions in the presence of titanium(IV) isoproxide and 4 A molecular sieves. The acidic and less nucleophilic anilines such as diphenylamine, phenothiazine, 4-cyanoaniline, and nitroanilines are efficiently allylated under palladium catalysis using allylic alcohols as allylating reagents.

  10. 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.

  11. 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.

  12. Silver-halide gelatin holograms

    NASA Astrophysics Data System (ADS)

    Chang, B. J.; Winick, K.

    1980-05-01

    The use of a silver-halide gelatin for volume phase holograms having a wide spectral response and lower exposure requirements than alternatives and using commercially available silver salts, is proposed. The main difference between the dichromated gelatin and silver-halide processes is the creation of a hologram latent image, which is given in the form of a hardness differential between exposed and unexposed regions in the silver halide hologram; the differential is in turn created by the reaction products of either tanning development or tanning bleach, which harden the gelatin with link-bonds between molecules.

  13. 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

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. 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

    2015-09-05

    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.

  19. Sources of cadmium in the environment.

    PubMed

    Hutton, M

    1983-02-01

    This paper is concerned with quantifying the major sources of cadmium in the European Community and assessing the relative significance of such inputs to the environmental compartments, air, land, and water. The methodology involved identification of potential sources of cadmium, including natural processes, as well as those associated with human activities. This was followed by a review of any emission studies of these processes and subsequent estimation of an emission factor for each source. The emission factor was applied to the most recent production or consumption data for the process in question to obtain an estimate of the annual discharge. The steel industry and waste incineration, followed by volcanic action and zinc production, are estimated to account for the largest emissions of atmospheric cadmium in the region. Waste disposal results in the single largest input of cadmium to land; the quantity of cadmium associated with this source is greater than the total from the four other major sources--coal combustion, iron and steel production, phosphate fertilizer manufacture and use, and zinc production. The characterization of cadmium inputs to aquatic systems is incomplete but of the sources considered, the manufacture of cadmium-containing articles accounts for the largest discharge, followed by phosphate fertilizer manufacture and zinc production.

  20. Main sources of lead and cadmium

    SciTech Connect

    Not Available

    1989-03-01

    Lead-acid batteries used in cars accounted for 65% of the lead in MSW in 1986, and rechargeable nickel-cadmium batteries contributed 52% of the cadmium discarded in the U.S. since 1980. According to an EPA draft report, other major sources of lead are consumer electronics 27%; glass and ceramics, 4%; and such plastic items as PVC resins. Other less significant sources of lead are soldered cans, pigments, brass and bronze products, light bulbs, rubber products, used oil, and lead foil wine bottle wrappers. Cadmium comes from other sources in addition to nickel-cadmium batteries. Plastics using cadmium as stabilizer (mainly PVC) or in pigments contribute 28% of the total amount entering the waste stream. Consumer electronics account for 9% (including cadmium-plated steel chassis on old TV sets and radios); appliances which used to be built with cadmium-plated parts to resist corrosion, 5% pigments, particularly those used in non-newspaper printing inks, textile dyes and paints, 4%; and glass and ceramics, 1.6% of the total.

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. Effects of cadmium on heart mitochondrial respiration

    SciTech Connect

    Kisling, G.M.; Kopp, S.J.; Paulson, D.J.; Tow, J.P.

    1986-03-01

    The purpose of this study was to determine the direct effect of cadmium on isolated heart mitochondrial respiration. Mitochondria were rapidly prepared by polytroning hearts from male Sprague-Dawley rats in a 0.25 M Sucrose, 4 mM Tris, 1 mM EGTA, 0.2% BSA buffer (pH 7.4), followed by a two-part differential centrifugation. Mitochondria were resuspended in this same Tris-sucrose-BSA buffer minus EGTA and mitochondrial respiration was assayed using a Clark oxygen electrode system at a concentration of 0.5 mg total mitochondrial protein/ml assay buffer. At 5 x 10/sup -6/ M cadmium, mitochondrial state 3 respiration (pyruvate plus malate) was reduced to a level 74.8% of the control value. A 50% reduction in state 3 respiratory rate was achieved at a cadmium concentration of 8.75 x 10/sup -6/ M. The respiratory control ratio did not change significantly but at higher cadmium concentrations (< greater than or equal to 1.25 x 10/sup -5/ M) the ADP/O ratio was increased. None of the cadmium concentrations tested, from 10/sup -8/ to 10/sup -4/ M, demonstrated an uncoupling response. These data suggest that cadmium acts strictly as an inhibitor of heart mitochondrial oxidative phosphorylation. These results contrast those of earlier work involving liver mitochondria in which cadmium was reported to uncouple mitochondrial respiration.

  6. Spectral properties of powder preparations of cadmium telluride and cadmium selenide with controlled nonstoichiometry

    NASA Astrophysics Data System (ADS)

    Khomyakov, A. V.; Mozhevitina, E. N.; Kuz'min, V. V.; Kon'kova, N. A.; Avetissov, I. Ch.

    2015-03-01

    The reflection spectra of powder preparations of cadmium telluride and cadmium selenide with different contents of overstoichiometric components have been investigated in the range of 800-1700 nm. The reflectance is found to be maximum for samples with compositions close to stoichiometric. An increase in the concentration of overstoichiometric cadmium more radically reduces the reflectance in comparison with preparations containing excess chalcogen. It is shown that halftone images in the near-IR range can be formed by using of these materials.

  7. 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

  8. 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.

  9. 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.

  10. 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.

  11. 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

  12. 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.

  13. Decreased glomerular filtration rate in solderers exposed to cadmium.

    PubMed Central

    Järup, L; Persson, B; Elinder, C G

    1995-01-01

    OBJECTIVES--to evaluate the degree of cadmium induced glomerular impairment and to assess the dose-response relation between cadmium dose and the prevalence of glomerular dysfunction. METHODS--A comparison of glomerular filtration rates (GFR) assessed by Cr-EDTA clearance was made in 42 solderers previously exposed to cadmium for at least five years. Blood and urine data were collected at health examinations in 1984, 1989, and 1993. Individual doses of cadmium were estimated by analysing cadmium in blood. RESULTS--Glomerular lesions induced by cadmium are irreversible and the GFR decreases with the degree of tubular damage. The GFR also decreases with cadmium dose and there is a dose-response relation between blood cadmium and prevalence of glomerular damage with 3.4% prevalence at blood cadmium concentrations below 50 nmol/l, 33% at blood cadmium concentrations between 50 and 75 nmol/l and 100% prevalence of glomerular damage when cadmium in blood exceeds 75 nmol/l. CONCLUSIONS--The kidney lesions induced by cadmium are irreversible and the prevalence of those lesions are dose dependent. There is also evidence of a dose related decrease in GFR even a long time after the end of exposure. Exposure to cadmium should therefore be minimised and workers exposed to cadmium should be examined regularly for many years after the end of exposure. PMID:8563845

  14. 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.

  15. 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.

  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. 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…

  18. Silver clusters and chemistry in zeolites

    SciTech Connect

    Sun, T.; Seff, K. . Dept. of Chemistry)

    1994-06-01

    The spectroscopic work done on silver clusters trapped in solid noble gas matrices at low temperature has been extensively reviewed by Ozin, and Henglein has done the same for photochemical studies of colloidal silver particles in solution. This article will review the chemistry of silver in zeolite hosts, including the synthesis and structures of silver clusters. 127 refs.

  19. 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.

  20. Bulk synthesis of nanoporous palladium and platinum powders

    DOEpatents

    Robinson, David B [Fremont, CA; Fares, Stephen J [Pleasanton, CA; Tran, Kim L [Livermore, CA; Langham, Mary E [Pleasanton, CA

    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.

  1. Gold-Palladium core@shell nanoalloys: experiments and simulations

    PubMed Central

    Spitale, A.; Perez, M. A.; Mejía-Rosales, S.; Yacamán, M. J.

    2015-01-01

    In this work, we report a facile synthesis route, structural characterization, and full atomistic simulations of gold-palladium nanoalloys. Through aberration corrected-STEM, UV-vis and EDS chemical analysis, we were able to determine that Au(core)-Pd(shell) bimetallic nanoparticles were formed. Using different computational approaches, we were capable to establish how the size of the core and the thickness of the shell will affect the thermodynamic stability of several core-shell nanoalloys. Finally, grand canonical simulations using different sampling procedures were used to study the growth mechanism of Pd atoms on Au seeds of different shape. PMID:25735727

  2. 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

  3. Synthesis of Dihydrobenzofurans via Palladium-Catalyzed Heteroannulations

    SciTech Connect

    Rozhkov, Roman Vladimirovich

    2004-01-01

    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 β-hydrogen in the vinylic halide results in β-hydride elimination giving the corresponding alkyne. The presence of a bulky group in the α-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.

  4. Palladium-Catalyzed Enantioselective Decarboxylative Allylic Alkylation of Cyclopentanones.

    PubMed

    Craig, Robert A; Loskot, Steven A; Mohr, Justin T; Behenna, Douglas C; Harned, Andrew M; Stoltz, Brian M

    2015-11-06

    The first general method for the enantioselective construction of all-carbon quaternary centers on cyclopentanones by enantioselective palladium-catalyzed decarboxylative allylic alkylation is described. Employing the electronically modified (S)-(p-CF3)3-t-BuPHOX ligand, α-quaternary cyclopentanones were isolated in yields up to >99% with ee's up to 94%. Additionally, in order to facilitate large-scale application of this method, a low catalyst loading protocol was employed, using as little as 0.15 mol % Pd, furnishing the product without any loss in ee.

  5. Palladium-catalysed synthesis of triaryl(heteroaryl)methanes

    NASA Astrophysics Data System (ADS)

    Zhang, Shuguang; Kim, Byeong-Seon; Wu, Chen; Mao, Jianyou; Walsh, Patrick J.

    2017-03-01

    Tetraarylmethane derivatives are desirable for a variety of applications, but difficult to access with modern C-C bond-forming reactions. Here we report a straightforward method for palladium-catalysed arylation of aryl(heteroaryl)methanes and diaryl(heteroaryl)methanes with aryl chlorides. This reaction enables introduction of various aryl groups to construct triaryl(heteroaryl)methanes via a C-H functionalization in good to excellent yield, and represents the first step towards a general transition metal catalysed synthesis of tetraarylmethanes.

  6. Cold fusion in palladium: a more realistic calculation.

    PubMed

    Parmenter, R H; Lamb, W E

    1990-11-01

    The Thomas-Fermi-Mott equation is modified to take account of the fact that conduction electrons in a metal may be considered to have an effective mass at wave-numbers comparable with or less than the inverse Debye screening length, but they should be considered to have the free-electron mass at much larger wavenumbers. This modification allows for a more realistic calculation of the fusion rate of deuteron pairs in palladium, this rate being 10(-23) sec-1, comparable with some experimental results. The Oppenheimer-Phillips process enhances the rate by a factor of 2.262.

  7. 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.

  8. Synthesis of monodispersed bimetallic palladium-copper nanoscale colloids

    SciTech Connect

    Bradley, J.S.; Hill, E.W.; Klein, C. ); Chaudret, B.; Duteil, A. )

    1993-03-01

    Bimetallic clusters have been the subject of many studies of the surface chemistry and catalytic properties of metal crystallites on solid supports. Mixtures of palladium acetate and copper acetate were refluxed in 2-ethoxyethanol in the presence of poly(vinylpyrrolidone) to give 40-[angstrom] alloy nanoclusters. TEM and EDAX analysis showed that the particles were homogeneously bimetallic and crystalline, with a composition determined by the ratio of the metal acetates used. Carbon monoxide adsorbed on the colloidal particles binds reversibly to both metals. 9 refs., 3 figs.

  9. Gold-palladium core@shell nanoalloys: experiments and simulations.

    PubMed

    Spitale, A; Perez, M A; Mejía-Rosales, S; Yacamán, M J; Mariscal, M M

    2015-11-14

    In this work, we report a facile synthesis route, structural characterization, and full atomistic simulations of gold-palladium nanoalloys. Through aberration corrected-STEM, UV-vis spectroscopy and EDS chemical analysis, we were able to determine that Au(core)-Pd(shell) bimetallic nanoparticles were formed. Using different computational approaches, we were capable of establishing how the size of the core and the thickness of the shell will affect the thermodynamic stability of several core-shell nanoalloys. Finally, grand canonical simulations using different sampling procedures were used to study the growth mechanism of Pd atoms on Au seeds of different shapes.

  10. 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.

  11. 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.

  12. 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.

  13. 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)

  14. 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.

  15. The study of palladium ions incorporation into the mesoporous ordered silicates

    NASA Astrophysics Data System (ADS)

    Zienkiewicz-Strzałka, M.; Pikus, S.

    2012-11-01

    In this work mesoporous ordered silica materials containing palladium species were prepared using of tetraammine palladium chloride ([Pd(NH3)4]Cl2) complex as a palladium source during synthesis and by wetness impregnation of pure support by solution containing dissolved metal salt. The ammonia ligands from tetraammine palladium chloride were removed during calcination or during thermal treatment at 300 °C in oxygen atmosphere. For reduction of palladium ions to metallic state as prepared materials were treated by hydrogen at high temperature. In this work the locations of palladium atoms in silica lattice were considered by study of binding energy changes of cardinal atoms of mesoporous ordered silica. Ordered mesoporous silicates (MCM-41 and SBA-15) are very promising materials for a wide range of industrial applications due to their unique properties as well-defined ordered structure and excellent textural properties. They exhibit high surface area with high pore volume. Such supports ensure a high dispersion of the metal nanoparticles or other active phases providing the high activity of solid catalysts. The obtained materials were characterized primarily by X-ray diffraction (XRD) technique, X-ray photoelectron spectroscopy (XPS), nitrogen adsorption-desorption isotherms, and infrared spectroscopy. The proportional content of palladium was controlled by X-ray fluorescence technique.

  16. Synthesis of iron nanoparticles via chemical reduction with palladium ion seeds.

    PubMed

    Huang, Kuo-Cheng; Ehrman, Sheryl H

    2007-01-30

    We report on the synthesis of highly monodisperse iron nanoparticles, using a chemical reduction method. Iron nanoparticles with an average diameter of 6 nm and a geometric standard deviation of 1.3 were synthesized at a pH of 9.50 from ferric chloride precursor with sodium borohydride as the reducing agent, polyacrylic acid as the dispersing agent, and palladium ions as seeds for iron nanoparticle nucleation. The resulting nanoparticles were ferromagnetic at 5 K and superparamagnetic at 350 K. The dispersing agent polyacrylic acid (PAA) was shown to prevent iron nanoparticles and possibly palladium clusters from aggregating; in the absence of PAA, only aggregated iron nanoparticles were obtained. The addition of palladium ions decreased the diameter of iron nanoparticles presumably by providing sites for heterogeneous nucleation onto palladium clusters. In the absence of palladium ions, the mean diameter of iron nanoparticles was approximately 110 nm and the standard deviation increased to 2.0. The pH of the solution also was found to have a significant effect on the particle diameter, likely by affecting PAA ionization and altering the conformation of the polymer chains. At lower pH (8.75), the PAA is less ionized and its ability to disperse palladium clusters is reduced, so the number of palladium seeds decreases. Therefore, the resulting iron nanoparticles were larger, 59 nm in diameter, versus 6 nm for nanoparticles formed at a pH of 9.50.

  17. 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.

  18. 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

  19. 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.

  20. Oral toxicity of silver ions, silver nanoparticles and colloidal silver--a review.

    PubMed

    Hadrup, Niels; Lam, Henrik R

    2014-02-01

    Orally administered silver has been described to be absorbed in a range of 0.4-18% in mammals with a human value of 18%. Based on findings in animals, silver seems to be distributed to all of the organs investigated, with the highest levels being observed in the intestine and stomach. In the skin, silver induces a blue-grey discoloration termed argyria. Excretion occurs via the bile and urine. The following dose-dependent animal toxicity findings have been reported: death, weight loss, hypoactivity, altered neurotransmitter levels, altered liver enzymes, altered blood values, enlarged hearts and immunological effects. Substantial evidence exists suggesting that the effects induced by particulate silver are mediated via silver ions that are released from the particle surface. With the current data regarding toxicity and average human dietary exposure, a Margin of Safety calculation indicates at least a factor of five before a level of concern to the general population is reached.

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. Determination of the melting temperature of palladium nanoparticles by X-ray absorption spectroscopy

    NASA Astrophysics Data System (ADS)

    Vlasenko, V. G.; Podsukhina, S. S.; Kozinkin, A. V.; Zubavichus, Ya. V.

    2016-02-01

    The anharmonicity parameters of the interatomic potential in ~4-nm palladium nanoparticles deposited on poly(tetra)fluoroethylene microgranules 0.2-0.5 μm in average size were studied by X-ray absorption spectroscopy from an analysis of temperature-dependent EXAFS Pd K edges. The parameters of the interatomic potential obtained were used to calculate melting temperature T melt = 1591 K and Debye temperature ΘD = 257 K of palladium nanoparticles; these temperatures are significantly lower than those in metallic palladium: 277 K and 1825 K, respectively.

  9. 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.

  10. 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

    2014-01-03

    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.

  11. Supported Palladium Nanoparticles Synthesized by Living Plants as a Catalyst for Suzuki-Miyaura Reactions

    PubMed Central

    Parker, Helen L.; Rylott, Elizabeth L.; Hunt, Andrew J.; Dodson, Jennifer R.; Taylor, Andrew F.; Bruce, Neil C.; Clark, James H.

    2014-01-01

    The metal accumulating ability of plants has previously been used to capture metal contaminants from the environment; however, the full potential of this process is yet to be realized. Herein, the first use of living plants to recover palladium and produce catalytically active palladium nanoparticles is reported. This process eliminates the necessity for nanoparticle extraction from the plant and reduces the number of production steps compared to traditional catalyst palladium on carbon. These heterogeneous plant catalysts have demonstrated high catalytic activity in Suzuki coupling reactions between phenylboronic acid and a range of aryl halides containing iodo-, bromo- and chloro- moieties. PMID:24489869

  12. Low Temperature Hydrogen Transport Using Palladium/Copper Membrane

    SciTech Connect

    Lessing, Paul Alan; Wood, Henry Carwin; Zuck, Larry Douglas

    2003-06-01

    Results are presented from low temperature hydrogen permeation experiments using a palladium/copper membrane. Inlet pressure was varied from 5 psig to 180 psig, while temperature was varied from 25°C to 275°C. The palladium/copper membranes exhibited flow stability problems at low temperatures and pressures when using ultra high purity hydrogen. A preconditioning step of high temperatures and inlet pressures of pure hydrogen was necessary to stimulate any substantial permeate flows. After pre-conditioning, results showed zero hydrogen flow when using 3–4% hydrogen mixed with helium or argon. It is thought that the inert gas atoms were adsorbed into the membrane surface and thus blocked the hydrogen atom dissolution. When using pure hydrogen at low to moderate temperatures and low pressures, no measurable permeate flow was observed. Also, zero permeate flow was observed at relatively high temperatures (e.g., 150°C) and a low inlet pressure (5 psig). The cause of the zero permeate flow, when using pure hydrogen, was attributed to interface control of the permeation process. Interface control could be due to: (a) insufficient energy to split the hydrogen molecule into hydrogen atoms, or (b) a reversible phase change from beta to alpha of crystals at the near surface.

  13. 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.

  14. 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.

  15. 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

  16. 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.

  17. Strain differences in toxicity of oral cadmium intake in rats.

    PubMed

    Ninkov, Marina; Popov Aleksandrov, Aleksandra; Mirkov, Ivana; Demenesku, Jelena; Mileusnic, Dina; Jovanovic Stojanov, Sofija; Golic, Natasa; Tolinacki, Maja; Zolotarevski, Lidija; Kataranovski, Dragan; Brceski, Ilija; Kataranovski, Milena

    2016-10-01

    Influence of genetic background on toxicity of oral cadmium (Cd) administration (30 days, in drinking water; 5 ppm and 50 ppm of cadmium) was examined in Albino Oxford (AO) and Dark Agouti (DA) rats. Similar cadmium deposition was noted in gut and draining mesenteric lymph nodes (MLN) of both strains but intensity and/or the pattern of responses to cadmium in these tissues differ. Less intense intestinal damage and leukocyte infiltration was observed in gut of cadmium-exposed AO rats. While gut-associated lymph node cells of DA rats responded to cadmium with an increase of cell proliferation, oxidative activity, IFN-γ, IL-17 production and expression, no changes of these activities of MLN cells of cadmium-treated AO rats were observed. Spleen, which accumulated cadmium comparable to MLN, responded to metal by drop in cell viability and by reduced responsiveness of proliferation and cytokine production to stimulation in DA rats solely, which suggest tissue dependence of cadmium effects. More pronounced cadmium effects on MLN and spleen cells of DA rats (which accumulated similar cadmium doses as AO rats), showed greater susceptibility of this strain to cadmium. The results presented, for the first time, depict the influence of genetic background to effects of oral cadmium administration.

  18. 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).

  19. 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.

  20. Palladium(II)-Catalyzed Enantioselective Reactions Using COP Catalysts.

    PubMed

    Cannon, Jeffrey S; Overman, Larry E

    2016-10-18

    Allylic amides, amines, and esters are key synthetic building blocks. Their enantioselective syntheses under mild conditions is a continuing pursuit of organic synthesis methods development. One opportunity for the synthesis of these building blocks is by functionalization of prochiral double bonds using palladium(II) catalysis. In these reactions, nucleopalladation mediated by a chiral palladium(II) catalyst generates a new heteroatom-substituted chiral center. However, reactions where nucleopalladation occurs with antarafacial stereoselectivity are difficult to render enantioselective because of the challenge of transferring chiral ligand information across the square-planar palladium complex to the incoming nucleophile. In this Account, we describe the development and use of enantiopure palladium(II) catalysts of the COP (chiral cobalt oxazoline palladacyclic) family for the synthesis of enantioenriched products from starting materials derived from prochiral allylic alcohols. We begin with initial studies aimed at rendering catalyzed [3,3]-sigmatropic rearrangements of allylic imidates enantioselective, which ultimately led to the identification of the significant utility of the COP family of Pd(II) catalysts. The first use of an enantioselective COP catalyst was reported by Richards' and our laboratories in 2003 for the enantioselective rearrangement of allylic N-arylimidates. Shortly thereafter, we discovered that the chloride-bridged COP dimer, [COP-Cl]2, was an excellent enantioselective catalyst for the rearrangement of (E)-allylic trichloroacetimidates to enantioenriched allylic trichloroacetamides, this conversion being the most widely used of the allylic imidate rearrangements. We then turn to discuss SN2' reactions catalyzed by the acetate-bridged COP dimer, [COP-OAc]2, which proceed by a unique mechanism to provide branched allylic esters and allylic phenyl ethers in high enantioselectivity. Furthermore, because of the unique nucleopalladation

  1. 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

  2. Identification of three relationships linking cadmium accumulation to cadmium tolerance and zinc and citrate accumulation in lettuce.

    PubMed

    Zorrig, Walid; Rouached, Aïda; Shahzad, Zaigham; Abdelly, Chedly; Davidian, Jean-Claude; Berthomieu, Pierre

    2010-10-15

    Lettuce (Lactuca sativa) is a plant species that shows high accumulation of cadmium, a toxic heavy metal. Lettuce is therefore a good model both for identifying determinants controlling cadmium accumulation in plant tissues and for developing breeding strategies aimed at limiting cadmium accumulation in edible tissues. In this work, 14-day-old plants from three lettuce varieties were grown for 8 days on media supplemented with cadmium concentrations ranging from 0 to 50 microM. Growth, as well as Cd(2+), Zn(2+), K(+), Ca(2+), NO(3)(-), SO(4)(2-), Cl(-), phosphate, malate and citrate root an shoot contents were analyzed. The three lettuce varieties Paris Island Cos, Red Salad Bowl and Kordaat displayed differential abilities to accumulate cadmium in roots and shoots, Paris Island Cos displaying the lowest cadmium content and Kordaat the highest. From the global analysis of the three varieties, three main trends were identified. First, a common negative correlation linked cadmium tissue content and relative dry weight reduction in response to cadmium treatments in the three varieties. Second, increasing cadmium concentration in the culture medium resulted in a parallel increase in zinc tissue content in all lettuce varieties. A common strong positive correlation between cadmium and zinc contents was observed for all varieties. This suggested that systems enabling zinc and cadmium transport were induced by cadmium. Finally, the cadmium treatments had a contrasting effect on anion contents in tissues. Interestingly, citrate content in shoots was correlated with cadmium translocation from roots to shoots, suggesting that citrate might play a role in cadmium transport in the xylem vessels. Altogether, these results shed light on three main strategies developed by lettuce to cope with cadmium, which could help to develop breeding strategies aimed at limiting cadmium accumulation in lettuce.

  3. 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.

  4. 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.

  5. 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.

  6. Copper-cadmium interaction in mice: effects of copper status on retention and distribution of cadmium after cadmium exposure

    SciTech Connect

    Bourcier, D.R.

    1982-01-01

    The role of increased dietary copper in altering the accumulation of cadmium and other metals in tissues, was investigated. Female Swiss-Webster mice were pretreated with cadmium or copper in drinking water for three weeks prior to cadmium exposure for an additional nine weeks, with sub groups from each dose level receiving Cu additions to the Cd supplemented water. In Cd pretreated animals, a significant decrease was observed in Cd concentrations in liver and kidney when Cu was added to Cd in drinking water. Cadmium levels in soluble protein fractions of liver of animals administered 5 ppm Cd were approximately three fold greater than that for the same Cd dose when Cu was added. The same was the case for the metallothionein-like protein fraction (MTP) of the liver cytosol. In copper pretreated animals similar trends were noted in that brain, spleen, liver (but not kidney) Cd levels were decreased in animals receiving Cu additions to the Cd dose. Increased binding of Cd to the MTP fraction was observed after both in vivo and in vitro exposure of intestinal mucosal cells to cadmium.

  7. A critical review of Cadmium in the Marine environment

    NASA Astrophysics Data System (ADS)

    Simpson, W. R.

    All aspects of the marine chemistry, geochemistry, cycling, fluxes and biochemistry of cadmium are reviewed and discussed. The main sections include: 1. A review summary. 2. The aquatic chemistry of cadmium in terms of inorganic and organic speciation, adsorption on to minerals and particulate matter and desorption remobilization from sediments. 3. The distribution of cadmium in the world's estuaries, seas and oceans and the marine disposal of cadmium-containing wastes. 4. The estimation of the global fluvial and aeolian input of cadmium to the oceans, the input of cadmium to sediments various particulate phases, the anthropogenic influence on cadmium fluxes for this century and the calculation of oceanic residence times based on the data. 5. Some physiological and biochemical effects of cadmium on bacteria, phytoplankton species and marine animals. 6. A brief outline of research needs and analytical methods.

  8. 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.

  9. Crystallographic Description for Nanoparticle Asemblies - Application to Cadmium Selenide Clusters

    DTIC Science & Technology

    2001-01-01

    Application to Cadmium Selenide Clusters DISTRIBUTION: Approved for public release, distribution unlimited This paper is part of the following report...Proc. Vol. 635 © 2001 Materials Research Society Crystallographic Description for Nanoparticle Asemblies - Application to Cadmium Selenide Clusters. A

  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. The "silver-nitrate-oma".

    PubMed

    McBride, T J; Rand, B; Dhillon, S S

    2012-01-01

    This case report demonstrates and emphasises the unusual radiographic appearance of silver nitrate treatment in a 30-year-old patient, who subsequently underwent excision biopsy of a presumed potentially malignant lesion.

  12. Highly sensitive plasmonic silver nanorods.

    PubMed

    Jakab, Arpad; Rosman, Christina; Khalavka, Yuriy; Becker, Jan; Trügler, Andreas; Hohenester, Ulrich; Sönnichsen, Carsten

    2011-09-27

    We compare the single-particle plasmonic sensitivity of silver and gold nanorods with similar resonance wavelengths by monitoring the plasmon resonance shift upon changing the environment from water to 12.5% sucrose solution. We find that silver nanoparticles have 1.2 to 2 times higher sensitivity than gold, in good agreement with simulations based on the boundary-elements-method (BEM). To exclude the effect of particle volume on sensitivity, we test gold rods with increasing particle width at a given resonance wavelength. Using the Drude-model of optical properties of metals together with the quasi-static approximation (QSA) for localized surface plasmons, we show that the dominant contribution to higher sensitivity of silver is the lower background polarizability of the d-band electrons and provide a simple formula for the sensitivity. We improve the reversibility of the silver nanorod sensors upon repeated cycles of environmental changes by blocking the high energy parts of the illumination light.

  13. A novel palladium-catalyzed hydroalkoxylation of alkenes with a migration of double bond.

    PubMed

    Tan, Jiajing; Zhang, Zuhui; Wang, Zhiyong

    2008-04-21

    A novel palladium-catalyzed addition of alcohols to olefins was developed, in which a migration of double bond was involved. By this new method, a variety of allylic ethers were prepared with moderate to high yields under mild conditions.

  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. 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...

  16. Tetramine dichloro-palladium subcellular localization in the kidney: electron microprobe study.

    PubMed

    Berry, J P

    1987-01-01

    Palladium salt has been used for some time in experimental therapy protocols; with this in mind, we carried out a study of the effect of tetramine dichloro-palladium (soluble salt) upon kidney cells. Using an electron microprobe, we were able to detect the presence of palladium associated with sulfur and iron in the lysosomes of the proximal tubule cells. Our results were compared with those obtained using Cis-diaminedichloro-platinum (Cis-DDP), an anti-cancer drug used in the treatment of diverse tumors. The mechanism of intralysosomal concentration of palladium as a non soluble salt associated with sulfur appeared to be related to local sulfatase activity. Finally, iron concentration appeared to be related to the inhibition process of erythropoiesis.

  17. Palladium-catalyzed carbonylation reaction of aryl bromides with 2-hydroxyacetophenones to form flavones.

    PubMed

    Wu, Xiao-Feng; Neumann, Helfried; Beller, Matthias

    2012-10-01

    Flavone of the month: a general and efficient method for the palladium-catalyzed carbonylative synthesis of flavones has been developed. Starting from aryl bromides and 2-hydroxyacetophenones, the corresponding flavones have been isolated in good yields.

  18. Development of polysilane-supported palladium/alumina hybrid catalysts and their application to hydrogenation.

    PubMed

    Oyamada, Hidekazu; Naito, Takeshi; Miyamoto, Shinpei; Akiyama, Ryo; Hagio, Hiroyuki; Kobayashi, Shū

    2008-01-07

    Novel immobilized Pd catalysts, polysilane-supported palladium/alumina hybrid catalysts, have been developed. The catalysts showed high catalytic activity for hydrogenation, and could be used in an organic solvent or under solvent-free conditions.

  19. 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.

  20. 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.

  1. Electrodeposition of a palladium nanocatalyst by ion confinement in polyelectrolyte multilayers.

    PubMed

    Vago, Miguel; Tagliazucchi, Mario; Williams, Federico J; Calvo, Ernesto J

    2008-11-30

    A highly efficient and selective material for electrocatalytic hydrogenation has been prepared by depositing monodisperse palladium nanoparticles of size (6+/-1) nm by electrochemical reduction of PdCl(4)(2-) confined in a polyelectrolyte multilayer film.

  2. Staining proteins in gels with silver nitrate.

    PubMed

    Simpson, Richard J

    2007-07-01

    INTRODUCTIONSilver staining is one of the commonly used procedures for visualizing proteins in acrylamide gels. All silver staining methods rely on the reduction of ionic to metallic silver to provide metallic silver images; the selective reduction at gel sites occupied by proteins compared to nonprotein sites is dependent on differences in the oxidation-reduction potentials at these sites. There are two broad methodologies for silver staining. One approach (nondiamine silver nitrate stains) uses silver nitrate as the silvering agent and formaldehyde in alkaline carbonate solution as the developing agent, whereas the other approach (diamine or ammoniacal stains) uses ammoniacal silver as the silvering agent and formaldehyde in dilute citric acid as the developing agent. Although protocols using ammoniacal silver are arguably more sensitive and give darker hues than those based on silver nitrate, they are more prone to negative staining, resulting in hollow or "doughnut" spots, give unacceptable backgrounds with tricine-based gel systems, and are not very robust because of their reliance on the ammonia-silver ratio. Additionally, ammoniacal silver staining is more sensitive for basic proteins but less so for very acidic proteins. This protocol describes a silver nitrate staining approach. Its sensitivity is in the low-nanogram range, which is 50-100 times more sensitive than classical Coomassie Blue staining, ~10 times better than colloidal Coomassie Blue staining, and at least twice as sensitive as the zinc/imidazole negative staining method.

  3. 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.

  4. Silver-Halide Gelatin Holograms.

    DTIC Science & Technology

    1980-02-01

    PREPARATION OF R-10 TYPE BLEACHES Stock Solution A: Distilled water - 500 ml Ammonium dichromate - 20g Concentrated sulfuric acid - 14 ml Distilled water to...for the preparation of a bleach solution 5 Rinse in running water for 15 seconds Red Light 6 Soak in 0.5% ammonium dichromate for 5 minutes Red Light...those of con- ventional dichromated gelatin holograms, can be formed employing commercial silver-halide films. Major advantages of silver-halide

  5. Ab initio study of the formation of vacancy and hydrogen-vacancy complexes in palladium and its hydride

    NASA Astrophysics Data System (ADS)

    Supryadkina, I. A.; Bazhanov, D. I.; Ilyushin, A. S.

    2014-01-01

    We report on the results of ab initio calculations of vacancy and hydrogen-vacancy complexes in palladium and palladium hydride. Comparative analysis of the energies of the formation of defect complexes in palladium and its hydride has revealed that the formation of vacancy clusters is easier in the palladium hydride structure. Investigation of hydrogen-vacancy complexes in bulk crystalline palladium has shown that a hydrogen atom and a vacancy interact to form a stable hydrogen-vacancy (H-Vac) defect complex with a binding energy of E b = -0.21 eV. To investigate the initial stage in the formation of hydrogen-vacancy complexes (H n -Vac m ), we consider the clusterization of defects into clusters containing H-Vac and H2-Vac complexes as a structural unit. It is found that hydrogen-vacancy complexes form 2D defect structures in palladium in the (100)-type planes.

  6. Transfer hydrogenation using recyclable polyurea-encapsulated palladium: efficient and chemoselective reduction of aryl ketones.

    PubMed

    Yu, Jin-Quan; Wu, Hai-Chen; Ramarao, Chandrashekar; Spencer, Jonathan B; Ley, Steven V

    2003-03-21

    A robust and recyclable palladium catalyst [Pd0EnCat] has been prepared by ligand exchange of polyurea-encapsulated palladium(II) acetate with formic acid, resulting in deposition of Pd(0) in the support material; Pd0EnCat is shown to be a highly efficient transfer hydrogenation catalyst for chemoselective reduction of a wide range of aryl ketones to benzyl alcohols.

  7. Stereoselective synthesis of 2,5-disubstituted morpholines using a palladium-catalyzed hydroamination reaction.

    PubMed

    McGhee, Alicia; Cochran, Brian M; Stenmark, Torrey A; Michael, Forrest E

    2013-08-04

    A palladium-catalyzed hydroamination reaction is the key step in a stereoselective synthesis of 2,5-disubstituted and 2,3,5-trisubsituted morpholines from carbamate-protected aziridines. Aziridines are selectively attacked at the more substituted position by unsaturated alcohol nucleophiles using Lewis acid catalysts. Palladium-catalyzed hydroamination of the resulting aminoalkenes gives morpholines as a single diastereomer in excellent yield.

  8. 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.

  9. Palladium-Catalyzed Dearomative Cyclocarbonylation by C-N Bond Activation.

    PubMed

    Yu, Hui; Zhang, Guoying; Huang, Hanmin

    2015-09-07

    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.

  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 1,4-difunctionalization of butadiene to form skipped polyenes.

    PubMed

    McCammant, Matthew S; Liao, Longyan; Sigman, Matthew S

    2013-03-20

    A palladium-catalyzed 1,4-addition across the commodity chemical 1,3-butadiene to afford skipped polyene products is reported. Through a palladium σ → π → σ allyl isomerization, two new carbon-carbon bonds are formed with high regioselectivity and trans stereoselectivity of the newly formed alkene. The utility of this method is highlighted by the successful synthesis of the ripostatin A skipped triene core.

  12. Synthesis and resolution of planar-chiral ruthenium-palladium complexes with ECE' pincer ligands.

    PubMed

    Bonnet, Sylvestre; Li, Jie; Siegler, Maxime A; von Chrzanowski, Lars S; Spek, Anthony L; van Koten, Gerard; Klein Gebbink, Robertus J M

    2009-01-01

    Feel the pinch! Planar-chiral, cationic, ruthenium-palladium complexes based on eta(6),eta(1)-coordinated ECE' pincer ligands are synthesized as racemic mixtures by reacting ECE'-palladium complexes and [Ru(C(5)R(5))(MeCN)(3)](+) arenophiles (R=H or Me). Chiral resolution of the cationic complexes was achieved by using the chiral counterion [Delta-TRISPHAT](-), and solving the X-ray crystal structure of one diastereoisomer (shown here).

  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. The cadmium electrode: Review of the status of research

    NASA Technical Reports Server (NTRS)

    Gross, S.; Glockling, R. J.

    1976-01-01

    Investigations characterizing the negative cadmium electrode used in a nickel cadmium battery cell are summarized with citations to references where more detailed information is available. Emphasis is placed on data pertinent to aerospace applications. An evaluation of some of the published results of cadmium electrode research is included.

  15. Cadmium affects the social behaviour of rainbow trout, Oncorhynchus mykiss.

    PubMed

    Sloman, Katherine A; Scott, Graham R; Diao, Zhongyu; Rouleau, Claude; Wood, Chris M; McDonald, D Gord

    2003-10-29

    The present study investigated both the effects of cadmium on the social interactions of rainbow trout and the differential accumulation of waterborne cadmium among social ranks of fish. Fish exposed to waterborne cadmium concentrations of 2 microg l(-1) for 24 h, followed by a 1, 2 or 3 day depuration period in clean water, had a decreased ability to compete with non-exposed fish. However, the competitive ability of exposed fish given a 5 day depuration period was not significantly impaired. Cadmium accumulated in the olfactory apparatus of fish exposed to waterborne cadmium for 24 h and decreased significantly only after 5 days depuration in clean water. Among groups of ten fish held in stream tanks, where all fish were exposed to cadmium, there were significant effects on social behaviour and growth rate. Dominance hierarchies formed faster among fish exposed to cadmium than among control fish, and overall growth rates were higher in the cadmium treatment. In groups of ten fish, social status also affected tissue accumulation of cadmium during waterborne exposure, with dominant fish accumulating more cadmium at the gill. In conclusion, exposure to low levels of cadmium, affects the social behaviour of fish, in part due to accumulation in the olfactory apparatus, and dominant fish accumulate more gill cadmium than subordinates during chronic waterborne exposure.

  16. Cadmium adsorption on vermiculite, zeolite and pumice: batch experimental studies.

    PubMed

    Panuccio, Maria Rosaria; Sorgonà, Agostino; Rizzo, Marcella; Cacco, Giovanni

    2009-01-01

    Batch experiments were performed to evaluate the combined effects of ionic activity, pH, and contact time on the cadmium sorption in three different minerals, vermiculite, zeolite, and pumice, commonly employed as substrata in nurseries and recently considered for their potential use in remediation methods. The extent of cadmium sorption was vermiculite>zeolite>pumice, as shown by the Langmuir and Freundlich parameters, and it was highly dependent on mineral characteristics. The percentage of cadmium sorption in zeolite and vermiculite did not depend on cadmium concentration, while in pumice this percentage was positively correlated to the initial cadmium concentration. At low cadmium concentrations (30-120 microM), the metal sorbed on zeolite was mainly present in the nonexchangeable form (70%) at levels much higher than those found for vermiculite and pumice. The primary variable responsible for determination of cadmium mobility in these minerals was confirmed to be pH. The ionic concentrations of Hoagland nutrient solution were significantly modified by both pH and mineral composition, while the presence of cadmium caused no changes. With vermiculite and zeolite, the time-course of cadmium sorption was related to mineral composition to a greater extent than to cadmium concentration. While with pumice, the percentage of cadmium sorbed after 6 weeks was lower than with the other two minerals, and it was inversely correlated to the initial cadmium concentration.

  17. Cadmium and copper metallothioneins in the American lobster, Homarus americanus

    SciTech Connect

    Engel, D.W.; Brouwer, M.

    1986-03-01

    Lobsters were fed cadmium-rich oysters for 28 days, and the induction of cadmium metallothionein and its relation to concentrations of cadmium, copper, and zinc in the digestive gland and gills was determined. A portion of the tissues also was retained for determining the cytosolic distribution of these metals by gel filtration and ion-exchange chromatography. The digestive gland contained a majority of the cadmium, copper, and zinc, and both cadmium and zinc were actively accumulated from the oysters. Gel chromatography of the digestive gland cytosol showed that initially only copper was bound to a protein with a molecular weight in the range of metallothionein (i.e., 10,000-7000). However, after feeding on cadmium-laden oysters for 28 days, both cadmium and copper were bound to the metallothioneinlike protein. Further purification of the cadmium/copper protein by ion-exchange chromatography showed that a large portion of the copper and all of the cadmium did not bind to DEAE-Sephacel. The induction of cadmium metallothionein in the digestive gland is correlated with tissue cadmium concentration. Coincident with the induction of the cadmium metallothionein was a cytosolic redistribution of copper. The distribution of zinc was not affected.

  18. Cadmium uptake and accumulation by the decapod crustacean Penaeus indicus.

    PubMed

    Nuñez-Nogueira, Gabriel; Rainbow, Philip S

    2005-09-01

    Juveniles of the dendrobranchiate decapod Penaeus indicus take up radiolabelled cadmium from solution over the exposure concentration range of 1.8-31.5 microg L(-1), with an uptake rate constant of 0.090 L g(-1)d(-1) at 15 salinity and 25 degrees C. New cadmium taken up is added to the existing cadmium content of the prawn with no significant excretion, and the rate of accumulation of radiolabelled cadmium is a measure of the absolute cadmium uptake rate from solution. Moulting had no significant effect on the accumulation of cadmium. Newly accumulated cadmium is distributed to all organs with the highest proportions of body content being found in the hepatopancreas, exoskeleton, gills and remaining soft tissues, the hepatopancreas and gills containing the highest labelled cadmium concentrations. Like other crustaceans, penaeid prawns inhabiting anthropogenically contaminated coastal waters with raised cadmium bioavailabilities can be expected to contain raised body concentrations of cadmium. Cadmium concentrations of most field-collected adult penaeids are relatively low, as a probable consequence of the growth dilution of their cadmium contents as a result of the rapid growth rates of penaeid prawns.

  19. Cadmium Recycling in the United States in 2000

    USGS Publications Warehouse

    Plachy, Jozef

    2003-01-01

    Recycling of cadmium is a young and growing industry that has been influenced by environmental concerns and regulatory constraints. Domestic recycling of cadmium began in 1989 as a byproduct of processing of spent nickel-cadmium batteries. In 1995, International Metals Reclamation Co. Inc. expanded its operations by building a dedicated cadmium recycling plant. In 2000, an estimated 13 percent of cadmium consumption in the United States was sourced from recycled cadmium, which is derived mainly from old scrap or, to lesser degree, new scrap. The easiest forms of old scrap to recycle are small spent nickel-cadmium batteries followed by flue dust generated during recycling of galvanized steel and small amounts of alloys that contain cadmium. Most of new scrap is generated during manufacturing processes, such as nickel-cadmium battery production. All other uses of cadmium are in low concentrations and, therefore, difficult to recycle. Consequently, much of this cadmium is dissipated and lost. The amount of cadmium in scrap that was unrecovered in 2000 was estimated to be 2,030 t, and an estimated 285 t was recovered. Recycling efficiency was estimated to be about 15 percent.

  20. Cadmium recycling in the United States in 2000

    USGS Publications Warehouse

    Plachy, Jozef

    2003-01-01

    Recycling of cadmium is a young and growing industry that has been influenced by environmental concerns and regulatory constraints. Domestic recycling of cadmium began in 1989 as a byproduct of processing of spent nickel-cadmium batteries. In 1995, International Metals Reclamation Co. Inc. expanded its operations by building a dedicated cadmium recycling plant. In 2000, an estimated 13 percent of cadmium consumption in the United States was sourced from recycled cadmium, which is derived mainly from old scrap or, to lesser degree, new scrap. The easiest forms of old scrap to recycle are small spent nickel-cadmium batteries followed by flue dust generated during recycling of galvanized steel and small amounts of alloys that contain cadmium. Most of new scrap is generated during manufacturing processes, such as nickel-cadmium battery production. All other uses of cadmium are in low concentrations and, therefore, difficult to recycle. Consequently, much of this cadmium is dissipated and lost. The amount of cadmium in scrap that was unrecovered in 2000 was estimated to be 2,030 metric tons, and an estimated 285 tons was recovered. Recycling efficiency was estimated to be about 15 percent.

  1. Thermodynamics for complex formation between palladium(ii) and oxalate.

    PubMed

    Pilný, Radomír; Lubal, Přemysl; Elding, Lars I

    2014-08-28

    Complex formation between [Pd(H2O)4](2+) and oxalate (ox = C2O4(2-)) has been studied spectrophoto-metrically in aqueous solution at variable temperature, ionic strength and pH. Thermodynamic parameters at 298.2 K and 1.00 mol dm(-3) HClO4 ionic medium for the complex formation [Pd(H2O)4](2+) + H2ox ⇄ [Pd(H2O)2(ox)] + 2H3O(+) with equilibrium constant K1,H (in mol dm(-3)) are log10K1,H = 3.38 ± 0.08, ΔH = -33 ± 3 kJ mol(-1), and ΔS = -48 ± 11 J K(-1) mol(-1), as determined from spectrophotometric equilibrium titrations at 15.0, 20.0, 25.0 and 31.0 °C. Thermodynamic overall stability constants β (in (mol dm(-3))(-n), n = 1,2) for [Pd(H2O)2(ox)] and [Pd(ox)2](2-) at zero ionic strength and 298.2 K, defined as the equilibrium constants for the reaction Pd(2+) + nox(2-) ⇄ [Pd(ox)n](2-2n) (water molecules omitted) are log10β = 9.04 ± 0.06 and log10β = 13.1 ± 0.3, respectively, calculated by use of Specific Ion Interaction Theory from spectrophotometric titrations with initial hydrogen ion concentrations of 1.00, 0.100 and 0.0100 mol dm(-3) and ionic strengths of 1.00, 2.00 or 3.00 mol dm(-3). The values derived together with literature data give estimated overall stability constants for Pd(ii) compounds such as [Pd(en)(ox)] and cis-[Pd(NH3)2Cl2], some of them analogs to Pt(ii) complexes used in cancer treatment. The palladium oxalato complexes are significantly more stable than palladium(ii) complexes with monodentate O-bonding ligands. A comparison between several different palladium complexes shows that different parameters contribute to the stability variations observed. These are discussed together with the so-called chelate effect.

  2. 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.

  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. Cadmium induces cadmium-tolerant gene expression in the filamentous fungus Trichoderma harzianum.

    PubMed

    Cacciola, Santa O; Puglisi, Ivana; Faedda, Roberto; Sanzaro, Vincenzo; Pane, Antonella; Lo Piero, Angela R; Evoli, Maria; Petrone, Goffredo

    2015-11-01

    The filamentous fungus Trichoderma harzianum, strain IMI 393899, was able to grow in the presence of the heavy metals cadmium and mercury. The main objective of this research was to study the molecular mechanisms underlying the tolerance of the fungus T. harzianum to cadmium. The suppression subtractive hybridization (SSH) method was used for the characterization of the genes of T. harzianum implicated in cadmium tolerance compared with those expressed in the response to the stress induced by mercury. Finally, the effects of cadmium exposure were also validated by measuring the expression levels of the putative genes coding for a glucose transporter, a plasma membrane ATPase, a Cd(2+)/Zn(2+) transporter protein and a two-component system sensor histidine kinase YcbA, by real-time-PCR. By using the aforementioned SSH strategy, it was possible to identify 108 differentially expressed genes of the strain IMI 393899 of T. harzianum grown in a mineral substrate with the addition of cadmium. The expressed sequence tags identified by SSH technique were encoding different genes that may be involved in different biological processes, including those associated to primary and secondary metabolism, intracellular transport, transcription factors, cell defence, signal transduction, DNA metabolism, cell growth and protein synthesis. Finally, the results show that in the mechanism of tolerance to cadmium a possible signal transduction pathway could activate a Cd(2+)/Zn(2+) transporter protein and/or a plasma membrane ATPase that could be involved in the compartmentalization of cadmium inside the cell.

  5. 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.

  6. Electrochemical Properties of Palladium and Platinum Phosphine Complexes.

    DTIC Science & Technology

    1985-09-30

    19 .3 Molecular orbital Energy Diagram for Square Planar Pd-Phosphine Complexes.......................... 20 4 Cyclic Voltammogram...hydrogen, and therefore cause reaction 6 and 7 to be more difficult than reaction 1. Similar results have been observed with lead, indium, cadmium ... voltammetry : trans-PdIIL 2x2 , where L = PPh 3, PBu 3, PCy3, NHMe 2 (Ph - phenyl, Bu = n-butyl, Cy = cyclohexyl, Me methyl) and X = Cl or I; cis-PdII(LL)X2

  7. Cadmium and Its Neurotoxic Effects

    PubMed Central

    Wang, Bo; Du, Yanli

    2013-01-01

    Cadmium (Cd) is a heavy metal that has received considerable concern environmentally and occupationally. Cd has a long biological half-life mainly due to its low rate of excretion from the body. Thus, prolonged exposure to Cd will cause toxic effect due to its accumulation over time in a variety of tissues, including kidneys, liver, central nervous system (CNS), and peripheral neuronal systems. Cd can be uptaken from the nasal mucosa or olfactory pathways into the peripheral and central neurons; for the latter, Cd can increase the blood brain barrier (BBB) permeability. However, mechanisms underlying Cd neurotoxicity remain not completely understood. Effect of Cd neurotransmitter, oxidative damage, interaction with other metals such as cobalt and zinc, estrogen-like, effect and epigenetic modification may all be the underlying mechanisms. Here, we review the in vitro and in vivo evidence of neurotoxic effects of Cd. The available finding indicates the neurotoxic effects of Cd that was associated with both biochemical changes of the cell and functional changes of central nervous system, suggesting that neurotoxic effects may play a role in the systemic toxic effects of the exposure to Cd, particularly the long-term exposure. PMID:23997854

  8. 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.

  9. Facile synthesis of bacitracin-templated palladium nanoparticles with superior electrocatalytic activity

    NASA Astrophysics Data System (ADS)

    Li, Yanji; Wang, Zi; Li, Xiaoling; Yin, Tian; Bian, Kexin; Gao, Faming; Gao, Dawei

    2017-02-01

    Palladium nanomaterials have attracted great attention on the development of electrocatalysts for fuel cells. Herein, we depicted a novel strategy in the synthesis of palladium nanoparticles with superior electrocatalytic activity. The new approach, based on the self-assembly of bacitracin biotemplate and palladium salt for the preparation of bacitracin-palladium nanoparticles (Bac-PdNPs), was simple, low-cost, and green. The complex, composed by a series of spherical Bac-PdNPs with a diameter of 70 nm, exhibited a chain-liked morphology in TEM and a face-centered cubic crystal structure in X-Ray diffraction and selected area electron diffraction. The palladium nanoparticles were mono-dispersed and stable in aqueous solution as shown in TEM and zeta potential. Most importantly, compared to the commercial palladium on carbon (Pd/C) catalyst (8.02 m2 g-1), the Bac-PdNPs showed a larger electrochemically active surface area (47.57 m2 g-1), which endowed the products an excellent electrocatalytic activity for ethanol oxidation in alkaline medium. The strategy in synthesis of Bac-PdNPs via biotemplate approach might light up new ideas in anode catalysts for direct ethanol fuel cells.

  10. An ultrasensitive label-free electrochemical immunosensor based on signal amplification strategy of multifunctional magnetic graphene loaded with cadmium ions

    NASA Astrophysics Data System (ADS)

    Li, Faying; Li, Yueyun; Dong, Yunhui; Jiang, Liping; Wang, Ping; Liu, Qing; Liu, Hui; Wei, Qin

    2016-02-01

    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.

  11. 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

  12. 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.

  13. Facile fabrication of ultrafine palladium nanoparticles with size- and location-control in click-based porous organic polymers.

    PubMed

    Li, Liuyi; Zhao, Huaixia; Wang, Jinyun; Wang, Ruihu

    2014-05-27

    Two click-based porous organic polymers (CPP-1 and CPP-2) are readily synthesized through a click reaction. Using CPP-1 and CPP-2 as supports, palladium nanoparticles (NPs) with uniform and dual distributions were prepared through H2 and NaBH4 reduction routes, respectively. Ultrafine palladium NPs are effectively immobilized in the interior cavities of polymers. The coordination of 1,2,3-triazolyl to palladium and the confinement effect of polymers on palladium NPs are verified by solid-state (13)C NMR and IR spectra, XPS analyses, EDX mapping, and computational calculation. The steric and electronic properties of polymers have a considerable influence on the interaction between polymers and palladium NPs, as well as the catalytic performances of NPs. The ultrafine palladium NPs with uniform distribution exhibit superior stability and recyclability over palladium NPs with dual distributions and palladium on charcoal in the hydrogenation of nitroarenes, and no obvious agglomeration and loss of catalytic activity were observed after recycling several times. The excellent performances mainly result from synergetic effects between palladium NPs and polymers.

  14. Biosorption of cadmium with brown macroalgae.

    PubMed

    Gutiérrez, Claudia; Hansen, Henrik K; Hernández, Piroska; Pinilla, Carolina

    2015-11-01

    Sorption experiments for cadmium removal using two brown macroalgae Lessonia nigrescens and Durvillaea antarctica were carried out. Although both types of algae were capable of retaining cadmium, differences in their performance were observed. The optimum pH was 3.7±0.2, and to achieve the equilibrium, 5 days of contact time were necessary for both biosorbents. The maximum experimental uptake obtained was similar for the two biosorbents: 95.3 mg Cd g(-1) by D. antarctica and 109.5 mg Cd g(-1) by L. nigrescens. The Langmuir model described the equilibrium sorption isotherms very well for both biosorbents and the Lagergren pseudo primer order model described the sorption kinetics for L. nigrescens satisfactorily and the Ho and Mckay pseudo second order model for D. antarctica. It was found that cadmium uptake by D. antarctica was faster than by L. nigrescens.

  15. 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.

  16. 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.

  17. Direct visualization of hydrogen absorption dynamics in individual palladium nanoparticles

    NASA Astrophysics Data System (ADS)

    Narayan, Tarun C.; Hayee, Fariah; Baldi, Andrea; Leen Koh, Ai; Sinclair, Robert; Dionne, Jennifer A.

    2017-01-01

    Many energy storage materials undergo large volume changes during charging and discharging. The resulting stresses often lead to defect formation in the bulk, but less so in nanosized systems. Here, we capture in real time the mechanism of one such transformation--the hydrogenation of single-crystalline palladium nanocubes from 15 to 80 nm--to better understand the reason for this durability. First, using environmental scanning transmission electron microscopy, we monitor the hydrogen absorption process in real time with 3 nm resolution. Then, using dark-field imaging, we structurally examine the reaction intermediates with 1 nm resolution. The reaction proceeds through nucleation and growth of the new phase in corners of the nanocubes. As the hydrogenated phase propagates across the particles, portions of the lattice misorient by 1.5%, diminishing crystal quality. Once transformed, all the particles explored return to a pristine state. The nanoparticles' ability to remove crystallographic imperfections renders them more durable than their bulk counterparts.

  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. Electronic Transitions of Palladium Monoboride and Platinum Monoboride

    NASA Astrophysics Data System (ADS)

    Ng, Y. W.; Pang, H. F.; Wong, Y. S.; Qian, Yue; Cheung, A. S.-C.

    2012-06-01

    Electronic transition spectrum of palladium monoboride (PdB) and platinum (PtB) monoboride have been studied using the technique of laser-ablation/reaction free jet expansion and laser induced fluorescence spectroscopy. The metal monoborides were produced by reacting laser ablated metal atoms and diborane ((B_2H_6) seeded in argon. Five and six vibrational bands were observed respectively for the PdB and PtB molecules. Preliminary analysis of the rotationally resolved structure showed that both molecules have X2 Σ+ ground state. Least-squares fit of the measured line positions yielded molecular constants for the electronic states involved. Molecular and electronic structures of PdB and PtB are discussed using a molecular orbital energy level diagram. Financial support from the Research Grants Council of the Hong Kong Special Administrative Region, China (Project No. HKU 701008P) is gratefully acknowledged.

  20. Potential application of palladium nanoparticles as selective recyclable hydrogenation catalysts

    NASA Astrophysics Data System (ADS)

    Mukherjee, DebKumar

    2008-03-01

    The search for more efficient catalytic systems that might combine the advantages of both homogeneous (catalyst modulation) and heterogeneous (catalyst recycling) catalysis is one of the most exciting challenges of modern chemistry. More recently with the advances of nanochemistry, it has been possible to prepare soluble analogues of heterogeneous catalysts. These nanoparticles are generally stabilized against aggregation into larger particles by electrostatic or steric protection. Herein we demonstrate the use of room temperature ionic liquid for the stabilization of palladium nanoparticles that are recyclable catalysts for the hydrogenation of carbon-carbon double bonds and application of these catalysts to the selective hydrogenation of internal or terminal C=C bonds in unsaturated primary alcohols. The particles suspended in room temperature ionic liquid show no metal aggregation or loss of catalytic activity even on prolonged use.

  1. 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.

  2. Green Synthesis, Characterization and Uses of Palladium/Platinum Nanoparticles

    NASA Astrophysics Data System (ADS)

    Siddiqi, Khwaja Salahuddin; Husen, Azamal

    2016-11-01

    Biogenic synthesis of palladium (Pd) and platinum (Pt) nanoparticles from plants and microbes has captured the attention of many researchers because it is economical, sustainable and eco-friendly. Plant and their parts are known to have various kinds of primary and secondary metabolites which reduce the metal salts to metal nanoparticles. Shape, size and stability of Pd and Pt nanoparticles are influenced by pH, temperature, incubation time and concentrations of plant extract and that of the metal salt. Pd and Pt nanoparticles are broadly used as catalyst, as drug, drug carrier and in cancer treatment. They have shown size- and shape-dependent specific and selective therapeutic properties. In this review, we have discussed the biogenic fabrication of Pd/Pt nanoparticles, their potential application as catalyst, medicine, biosensor, medical diagnostic and pharmaceuticals.

  3. 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.

  4. [Determination of palladium in automobile exhaust catalysts by FAAS method].

    PubMed

    Wei, Xiao-Feng; Cai, Guo-Hui; Xiao, Yi-Hong; Zhan, Ying-Ying; Xie, Zeng-Hong; Wei, Ke-Mei

    2009-12-01

    Palladium in automotive exhaust catalyst was determined by flame atomic absorption spectrometry (FAAS). The analytical conditions and the coexisting elements interference were studied. The catalyst was dissolved by the mixture of H2O2 and HCl. Pd in the solution was directly determined by FAAS method. The linearity of working curve ranges from 0.1 to 15 microg x mL(-1); the detection limit is 0.029 microg x mL(-1); the relative standard deviation (RSD) range is from 0.8% to 2.5%; and the recovery rate range is from 99.6% to 101.2%. It is a simple and convenient method for accurate analysis of Pd in the exhaust catalysts.

  5. 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

  6. Lipid peroxidation induced by maternal cadmium exposure in mouse pups

    SciTech Connect

    Baohui Xu |; Yapin Jin; Zhaoliang Feng; Zhaofa Xu; Matsushita, Toshio

    1993-11-01

    Cadmium as an environmental pollutant has received considerable attention and its toxic effects have been studied extensively in human and adult animals. Moreover, an International Task Group on Metal Accumulation (1973) has established that although it is in a limited quantity cadmium can be transported across placenta and excreted through milk in animals. Likewise, it can pass through placenta in humans. Furthermore, the fact is that women in the cadmium-polluted areas are continuously exposed to cadmium during gestation and lactation. Even if they are removed from the exposure, the body burden of cadmium probably remains high because of the very long biological half-time of cadmium which is estimated to be between 17.6 and 33 years. Thus, it is possible that fetuses and pups may be exposed to cadmium during maternal gestation and lactation. Although placenta affords some protection from cadmium exposure, cadmium exposure prior to day 10-11 when placenta forms may be deleterious. Cadmium exposure during pregnancy and its effects on offsprings, which were mainly focused on litter size, pup survival, pup growth and cadmium contents in pups following maternal cadmium exposure have been reported. Lipid peroxide has been considered as a sensitive toxicological index for environmental pollutants. The inhibited antioxidant enzymes and enhanced lipid peroxidation due to cadmium exposure have been demonstrated both in humans and animals. Therefore, the present study was designed to evaluate the toxic effects of maternal cadmium exposure on mouse pups using both the indices used in the previous studies and determinations of lipid peroxide concentrations in various pup organs. In conclusion, data from the present study indicate that the detection of LPO concentration in selected pup tissues is a sensitive index for evaluating the effects of maternal cadmium exposure on mouse pups. 16 refs., 4 tabs.

  7. 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.

  8. 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.

  9. Synthesis, structure and dynamics of NHC-based palladium macrocycles.

    PubMed

    Andrew, Rhiann E; Chaplin, Adrian B

    2014-01-21

    A series of macrocyclic CNC pincer pro-ligands based on bis(imidazolium)lutidine salts with octa-, deca- and dodecamethylene spacers have been prepared and their coordination chemistry investigated. Using a Ag2O based transmetallation strategy, cationic palladium(II) chloride complexes [PdCl{CNC-(CH2)n}][BAr(F)4] (n = 8, 10, 12; Ar(F) = 3,5-C6H3(CF3)2) were prepared and fully characterised in solution, by NMR spectroscopy and ESI-MS, and in the solid-state, by X-ray crystallography. The smaller macrocyclic complexes (n = 8 and 10) exhibit dynamic behaviour in solution, involving ring flipping of the alkyl spacer across the Pd-Cl bond, which was interrogated by variable temperature NMR spectroscopy. In the solid-state, distorted coordination geometries are observed with the spacer skewed to one side of the Pd-Cl bond. In contrast, a static C2 symmetric structure is observed for the dodecamethylene based macrocycle. For comparison, palladium(II) fluoride analogues [PdF{CNC-(CH2)n}][BAr(F)4] (n = 8, 10, 12) were also prepared and their solution and solid-state structures contrasted with those of the chlorides. Notably, these complexes exhibit very low frequency (19)F chemical shifts (ca. -400 ppm) and the presence of C-H···F interactions ((2h)J(FC) coupling observed by (13)C NMR spectroscopy). The dynamic behaviour of the fluoride complexes is largely consistent with the smaller ancillary ligand; [PdF{CNC-(CH2)8}][BAr(F)4] exceptionally shows C(2v) time averaged symmetry in solution at room temperature (CD2Cl2, 500 MHz) as a consequence of dual fluxional processes of the pincer backbone and alkyl spacer.

  10. 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.

  11. Engineering-Scale Distillation of Cadmium for Actinide Recovery

    SciTech Connect

    J.C. Price; D. Vaden; R.W. Benedict

    2007-10-01

    During the recovery of actinide products from spent nuclear fuel, cadmium is separated from the actinide products by a distillation process. Distillation occurs in an induction-heated furnace called a cathode processor capable of processing kilogram quantities of cadmium. Operating parameters have been established for sufficient recovery of the cadmium based on mass balance and product purity. A cadmium distillation rate similar to previous investigators has also been determined. The development of cadmium distillation for spent fuel treatment enhances the capabilities for actinide recovery processes.

  12. Effect of co-exposure and cadmium in rats

    SciTech Connect

    Tandon, S.K.; Tewari, P.C.

    1987-10-01

    Metabolism and toxicity of heavy metals may be influenced by certain factors such as protein malnutrition, essential element deficiency or alcoholism. Ethanol has been found to enhance the absorption of lead in body and alcoholics have been reported to be more susceptible to lead intoxication. As alcoholism may be common among industry workers and a significant section of population, who may be exposed to cadmium, it was considered of interest to investigate the influence of ethanol-cadmium co-exposure on cadmium sensitive hepatic, renal and serum enzymes, tissue accumulation of cadmium, essential trace element status and cadmium induced hepatic metallothione in synthesis in rats.

  13. The new insights into cadmium sensing

    PubMed Central

    Chmielowska-Bąk, Jagna; Gzyl, Jarosław; Rucińska-Sobkowiak, Renata; Arasimowicz-Jelonek, Magdalena; Deckert, Joanna

    2014-01-01

    Cadmium (Cd) is non-essential heavy metal, which in excess, exhibits deleterious effects to the most of the organisms. Mobilization of defense mechanisms against this toxic agent requires rapid activation of signaling pathways. The article presents recent advances in the research concerning cadmium signal transduction in plants. New insights into the involvement of reactive oxygen species (ROS), nitric oxide (NO), plant growth regulators, and Cd-induced protein modifications are reviewed. Moreover, the role of recently recognized Cd-associated signal elements, including micro RNAs and several cis- and trans-acting elements is discussed. PMID:24917871

  14. Mineral resource of the month: cadmium

    USGS Publications Warehouse

    Tolcin, Amy C.

    2012-01-01

    The element cadmium was discovered in 1817 by Friedrich Stromeyer, a professor of chemistry at the University of Göttingen in Germany. Stromeyer noticed that a yellowish glow would occur when heat was applied to certain samples of calamine, a zinc-carbonate. This was unusual as the reaction was expected to be colorless. After further testing, Stromeyer deduced that an unknown metallic impurity in the carbonate caused the color change. He called the new metal "cadmium" after "kadmeia," the Greek word for calamine.

  15. Cadmium-induced testicular injury

    SciTech Connect

    Siu, Erica R.; Mruk, Dolores D.; Porto, Catarina S.; Cheng, C. Yan

    2009-08-01

    Cadmium (Cd) is an environmental toxicant and an endocrine disruptor in humans and rodents. Several organs (e.g., kidney, liver) are affected by Cd and recent studies have illustrated that the testis is exceedingly sensitive to Cd toxicity. More important, Cd and other toxicants, such as heavy metals (e.g., lead, mercury) and estrogenic-based compounds (e.g., bisphenols) may account for the recent declining fertility in men among developed countries by reducing sperm count and testis function. In this review, we critically discuss recent data in the field that have demonstrated the Cd-induced toxicity to the testis is probably the result of interactions of a complex network of causes. This is likely to involve the disruption of the blood-testis barrier (BTB) via specific signal transduction pathways and signaling molecules, such as p38 mitogen-activated protein kinase (MAPK). We also summarize current studies on factors that confer and/or regulate the testis sensitivity to Cd, such as Cd transporters and metallothioneins, the impact of Cd on the testis as an endocrine disruptor and oxidative stress inducer, and how it may disrupt the Zn{sup 2+} and/or Ca{sup 2+} mediated cellular events. While much work is needed before a unified mechanistic pathway of Cd-induced testicular toxicity emerges, recent studies have helped to identify some of the likely mechanisms and/or events that take place during Cd-induced testis injury. Furthermore, some of the recent studies have shed lights on potential therapeutic or preventive approaches that can be developed in future studies by blocking or minimizing the destructive effects of Cd to testicular function in men.

  16. Cadmium-induced Testicular Injury*

    PubMed Central

    Siu, Erica R.; Mruk, Dolores D.; Porto, Catarina S.; Cheng, C. Yan

    2009-01-01

    Cadmium (Cd) is an environmental toxicant and an endocrine disruptor in humans. Several organs (e.g., kidney, liver) are affected by Cd and recent studies have illustrated that the testis is exceedingly sensitive to Cd toxicity. More important, Cd and other toxicants, such as heavy metals (e.g., lead, mercury) and estrogenic-based compounds (e.g., bisphenols) may account for the recent declining fertility in men among developed countries by reducing sperm count and testis function. In this review, we critically discuss recent data in the field that have demonstrated the Cd-induced toxicity to the testis is probably the result of interactions of a complex network of causes. This is likely to involve the disruption of the blood-testis barrier (BTB) via specific signal transduction pathways and signaling molecules, such as p38 mitogen-activated protein kinase (MAPK). We also summarize current studies on factors that confer the testis sensitivity to Cd, such as Cd transporters and metallothioneins, and the impact of Cd on the testis as an endocrine disruptor, oxidative stress inducer and how it may disrupt the Zn+2 and/or Ca+2 mediated cellular events. While much work is needed before a unified mechanistic pathway of Cd-induced testicular toxicity is emerged, recent studies have helped to identify some of the likely mechanisms and/or events that take place during Cd-induced testis injury. Furthermore, some of the recent studies have shed lights on potential therapeutic or preventive approaches that can be developed in future studies by blocking or minimizing the destructive effects of Cd to testicular function in men. PMID:19236889

  17. Metallothionein protection of cadmium toxicity

    SciTech Connect

    Klaassen, Curtis D. Liu, Jie; Diwan, Bhalchandra A.

    2009-08-01

    The discovery of the cadmium (Cd)-binding protein from horse kidney in 1957 marked the birth of research on this low-molecular weight, cysteine-rich protein called metallothionein (MT) in Cd toxicology. MT plays minimal roles in the gastrointestinal absorption of Cd, but MT plays important roles in Cd retention in tissues and dramatically decreases biliary excretion of Cd. Cd-bound to MT is responsible for Cd accumulation in tissues and the long biological half-life of Cd in the body. Induction of MT protects against acute Cd-induced lethality, as well as acute toxicity to the liver and lung. Intracellular MT also plays important roles in ameliorating Cd toxicity following prolonged exposures, particularly chronic Cd-induced nephrotoxicity, osteotoxicity, and toxicity to the lung, liver, and immune system. There is an association between human and rodent Cd exposure and prostate cancers, especially in the portions where MT is poorly expressed. MT expression in Cd-induced tumors varies depending on the type and the stage of tumor development. For instance, high levels of MT are detected in Cd-induced sarcomas at the injection site, whereas the sarcoma metastases are devoid of MT. The use of MT-transgenic and MT-null mice has greatly helped define the role of MT in Cd toxicology, with the MT-null mice being hypersensitive and MT-transgenic mice resistant to Cd toxicity. Thus, MT is critical for protecting human health from Cd toxicity. There are large individual variations in MT expression, which might in turn predispose some people to Cd toxicity.

  18. Cadmium Exposure and Pancreatic Cancer in South Louisiana

    PubMed Central

    Luckett, Brian G.; Su, L. Joseph; Rood, Jennifer C.; Fontham, Elizabeth T. H.

    2012-01-01

    Cadmium has been hypothesized to be a pancreatic carcinogen. We test the hypothesis that cadmium exposure is a risk factor for pancreatic cancer with a population-based case-control study sampled from a population with persistently high rates of pancreatic cancer (south Louisiana). We tested potential dietary and nondietary sources of cadmium for their association with urinary cadmium concentrations which reflect long-term exposure to cadmium due to the accumulation of cadmium in the kidney cortex. Increasing urinary cadmium concentrations were significantly associated with an increasing risk of pancreatic cancer (2nd quartile OR = 3.34, 3rd = 5.58, 4th = 7.70; test for trend P ≤ 0.0001). Potential sources of cadmium exposure, as documented in the scientific literature, found to be statistically significantly associated with increased risk of pancreatic cancer included working as a plumber, pipefitter or welder (OR = 5.88) and high consumption levels of red meat (4th quartile OR = 6.18) and grains (4th quartile OR = 3.38). Current cigarette smoking, at least 80 pack years of smoking, occupational exposure to cadmium and paints, working in a shipyard, and high consumption of grains were found to be statistically significantly associated with increased concentrations of urinary cadmium. This study provides epidemiologic evidence that cadmium is a potential human pancreatic carcinogen. PMID:23319964

  19. Nano- and microcrystalline particles of palladium formed on hydrogen-bombarded palladium surfaces; their structure and formation kinetics

    NASA Astrophysics Data System (ADS)

    Senda, S.; Muto, H.; Takamori, H.; Okuyama, F.

    2003-03-01

    Crystalline particles of palladium are known to form on polycrystalline Pd interacting with low-energy hydrogen ions. These particles disperse on the glassy medium called the “matrix". The particles were recently confirmed by transmission electron microscopy to be classified into two groups: the particles emerging from the projectile-implanted subsurface together with the outflowing matrix and those newly produced on the hydrogen-bombarded matrix. The latter type of particles was nucleated as a crystalline cluster on the disordered substrate, and then underwent three-dimensional growth into a nanocrystal under the bombard- ment of showering hydrogen ions. Some particles presented a bubble-like TEM contrast, independently of their growth history. Such particles were chestnut-like in structure, with a hard shell wrapping the less-dense interior, and their formation may be attributed to a chemical process occurring within the particles.

  20. Cardiovascular actions of cadmium at environmental exposure levels

    SciTech Connect

    Kopp, S.J.; Glonek, T.; Perry, H.M. Jr.; Erlanger, M.; Perry, E.F.

    1982-08-27

    A low intake of dietary cadmium induces specific dose-dependent functional and biochemical changes in the cardiovascular tissues of rats. Maximum changes occur when the cadmium intake is 10 to 20 micrograms per kilogram of body weight per day. The changes reflect the accumulation of critical concentrations of cadmium in the cardiovascular tissues. The biologic activity of cadmium is demonstrated for intakes that approach those of the average American adult exposed to the usual environmental concentrations of the element but not to industrial concentrations. The sensitivity of the cardiovascular system to low doses of cadmium could not be anticipated by extrapolation from data on exposure to high concentrations of cadmium. The data support the hypothesis that ingested or inhaled environmental cadmium may contribute to essential hypertension in humans.