WorldWideScience

Sample records for bio-released gold ions

  1. Gold ions bio-released from metallic gold particles reduce inflammation and apoptosis and increase the regenerative responses in focal brain injury

    DEFF Research Database (Denmark)

    Larsen, Agnete; Kolind, Kristian; Pedersen, Dan Sonne;

    2008-01-01

    Traumatic brain injury results in loss of neurons caused as much by the resulting neuroinflammation as by the injury. Gold salts are known to be immunosuppressive, but their use are limited by nephrotoxicity. However, as we have proven that implants of pure metallic gold release gold ions which do...... not spread in the body, but are taken up by cells near the implant, we hypothesize that metallic gold could reduce local neuroinflammation in a safe way. Bio-liberation, or dissolucytosis, of gold ions from metallic gold surfaces requires the presence of disolycytes i.e. macrophages and the process...... neural stem cell response. We conclude that bio-liberated gold ions possess pronounced anti-inflammatory and neuron-protective capacities in the brain and suggest that metallic gold has clinical potentials. Intra-cerebral application of metallic gold as a pharmaceutical source of gold ions represents...

  2. Phage based green chemistry for gold ion reduction and gold retrieval.

    Science.gov (United States)

    Setyawati, Magdiel I; Xie, Jianping; Leong, David T

    2014-01-22

    The gold mining industry has taken its toll on the environment, triggering the development of more environmentally benign processes to alleviate the waste load release. Here, we demonstrate the use of bacteriophages (phages) for biosorption and bioreduction of gold ions from aqueous solution, which potentially can be applied to remediate gold ions from gold mining waste effluent. Phage has shown a remarkably efficient sorption of gold ions with a maximum gold adsorption capacity of 571 mg gold/g dry weight phage. The product of this phage mediated process is gold nanocrystals with the size of 30-630 nm. Biosorption and bioreduction processes are mediated by the ionic and covalent interaction between gold ions and the reducing groups on the phage protein coat. The strategy offers a simple, ecofriendly and feasible option to recover of gold ions to form readily recoverable products of gold nanoparticles within 24 h.

  3. Phage based green chemistry for gold ion reduction and gold retrieval.

    Science.gov (United States)

    Setyawati, Magdiel I; Xie, Jianping; Leong, David T

    2014-01-22

    The gold mining industry has taken its toll on the environment, triggering the development of more environmentally benign processes to alleviate the waste load release. Here, we demonstrate the use of bacteriophages (phages) for biosorption and bioreduction of gold ions from aqueous solution, which potentially can be applied to remediate gold ions from gold mining waste effluent. Phage has shown a remarkably efficient sorption of gold ions with a maximum gold adsorption capacity of 571 mg gold/g dry weight phage. The product of this phage mediated process is gold nanocrystals with the size of 30-630 nm. Biosorption and bioreduction processes are mediated by the ionic and covalent interaction between gold ions and the reducing groups on the phage protein coat. The strategy offers a simple, ecofriendly and feasible option to recover of gold ions to form readily recoverable products of gold nanoparticles within 24 h. PMID:24359519

  4. Synthesis of gold structures by gold-binding peptide governed by concentration of gold ion and peptide.

    Science.gov (United States)

    Kim, Jungok; Kim, Dong-Hun; Lee, Sylvia J; Rheem, Youngwoo; Myung, Nosang V; Hur, Hor-Gil

    2016-08-01

    Although biological synthesis methods for the production of gold structures by microorganisms, plant extracts, proteins, and peptide have recently been introduced, there have been few reports pertaining to controlling their size and morphology. The gold ion and peptide concentrations affected on the size and uniformity of gold plates by a gold-binding peptide Midas-11. The higher concentration of gold ions produced a larger size of gold structures reached 125.5 μm, but an increased amount of Midas-11 produced a smaller size of gold platelets and increased the yield percentage of polygonal gold particles rather than platelets. The mechanisms governing factors controlling the production of gold structures were primarily related to nucleation and growth. These results indicate that the synthesis of gold architectures can be controlled by newly isolated and substituted peptides under different reaction conditions. PMID:27108675

  5. Enhanced photo-catalytic activity of gold ion and gold modified

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The gold ion modified TiO2 was prepared by means of sol- gelwhereas gold deposited TiO2 was prepared by means of photo- reduction. The physical properties were influenced significantly by the presence of gold ion or gold. The enhanced photo-activity of gold modified TiO2 was quantified in terms of methylene blue degradation. The presence of gold ion in TiO2 lattices or gold on TiO2 surface enhanced their photo-activity. The optimum molar content of gold ion doping and gold deposition all was 0.5%. The first-order rates constants of gold modified TiO2 was more than that of pure TiO2, and decreased by increasing the content of gold ion and gold when their contents were more than 0.5%. Gold iondoped in TiO2 lattices was more effective to enhance the photo-activity than gold on TiO2 surface. Moreover, the relationship between physical properties, chemical properties and photo-activityhas been discussed.

  6. Direct deposition of gold on silicon with focused ion beams

    Energy Technology Data Exchange (ETDEWEB)

    Nebiker, P.W.; Doebeli, M. [Paul Scherrer Inst. (PSI), Villigen (Switzerland); Muehle, R. [Eidgenoessische Technische Hochschule, Zurich (Switzerland)

    1997-09-01

    Irradiation with ions at very low energies (below 500 eV) no longer induces a removal of substrate material, but the ions are directly deposited on the surface. In this way, gold has been deposited on silicon with focused ion beam exposure and the properties of the film have been investigated with atomic force microscopy and Auger electron spectroscopy. (author) 3 figs., 1 ref.

  7. Ion beam analysis of gold jewelry

    Science.gov (United States)

    Demortier, Guy

    1992-02-01

    PIXE milliprobe in a nonvacuum assembly has been proven to be a very rapid and accurate method for the elemental analysis of gold jewelry artefacts. Using protons whose energy is lower than 3 MeV, it is possible to obtain, in a few minutes, the actual composition (copper, iron, gold, silver, etc.) of narrow parts of artefacts, without any sampling, even at microscopic level. Most of the studies of our group in this field concern solders on these jewelry items. Narrow regions of gold artefacts have also been studied with a PIXE microprobe. They were then irradiated in vacuum. Nuclear reaction analyses induced by 2 MeV deuterons are also performed to identify the presence of light elements and, particularly O, N and S. Traces of these elements are of primary importance to characterize the origin of the ores used in various workmanships. Interferences of X-ray lines of Au with those of traces of Cu and Zn are solved using a method of selective excitation of X-rays of these elements. Analytical results have been interpreted in order to understand the workmanship of goldsmiths from the Antiquity. Fakes and repairs (or ornaments added to original artefacts) may also be identified. The ancient recipes are improved to give new soldering procedures at low temperature.

  8. The spectral lines of highly charged gold ions

    Science.gov (United States)

    Hu, Feng; Yang, Jiamin; Zhang, Jiyan; Jiang, Gang

    2015-02-01

    Extreme ultraviolet spectra of highly charged gold were produced with an electron beam ion trap at the University of Electro-Communications, Tokyo. The X-ray spectra (3240-3360 eV) of Au with well-defined maximum charge states ranging from Cu- to Se-like ions were recorded. Guided by configuration interaction calculations, the strongest 3d-5f transitions have been well defined.

  9. Developing Gold Nanowires by Galvanic Replication of Ion Track Templates

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    @@ Scientists at the CAS Institute of Modern Physics (IMP) in Lanzhou, capital of northwest China's Gansu Province, recently made an essential advance in production and investigation of single- and polycrystalline gold nanowires by galvanic replication of ion track templates. Their work was published by the Nanotechnology (Vol. 17, 1922-1926, 2006).

  10. Processing of residual gold (III) solutions via ion exchange

    OpenAIRE

    Alguacil, Francisco José; Adeva, Paloma; Alonso Gámez, Manuel

    2005-01-01

    The processing of gold (III)-hydrochloric acid solutions by the anionic ion exchange Lewatit MP-64_resin has been investigated. The influence of several variables such as the temperature, the hydrochloric acid and metal concentrations in the aqueous solution and the variation of the amount of resin added has been studied. Moreover, a kinetic study performed in the uptake of gold (III) by Lewatit MP-64_shows that either the film-diffusion and the particle-diffusion models fit the adsorption pr...

  11. Radiochemical study of the reactions of heavy ions with gold

    Energy Technology Data Exchange (ETDEWEB)

    Binder, I.

    1977-07-01

    Thick gold foils have been bombarded with heavy-ion projectiles at energies above the Coulomb barrier. The radioactive products were identified and their yields measured using gamma-ray spectrometry and an extensive series of computer programs developed for the data analysis. The total mass-yield distribution was extracted from the data using charge-dispersion curves inferred from the experimental results. One observes a change in the mass-yield distributions corresponding to primarily fusion-fission tractions occurring with the lighter projectiles Ne-20 and Ar-40 and deep-inelastic transfer reactions predominating with heavier Kr-84, Kr-86, and Xe-136 projectiles. For the deep-inelastic transfer reaction, more mass transfer is seen to occur for a higher incident projectile energy, and the Gaussian distribution of products shows exponential tailing. The preferred direction for mass transfer is from gold to the projectile nucleus. Sequential fission is a likely fate for nucludes beyond the lead shell closure. The ''gold finger'' is explained as a combination of mass transfer, nucleon evaporation and sequential fission. The yields of gold nuclides indicate a superposition of two reaction mechanisms, quasi-elastic and deep-inelastic. The angular momentum involved with each mechanism determines which of two isomeric states is the end product of the nuclear reaction. Suggestions are offered regarding the possibility of synthesizing super-heavy elements by use of heavy-ion nuclear reactions.

  12. Elongation of gold nanoparticles in silica glass by irradiation with swift heavy ions

    OpenAIRE

    Awazu, Koichi; Wang, Xiaomin; Fujimaki, Makoto; Tominaga, Junji; Aiba, Hirohiko; OHKI, Yoshimichi; Komatsubara, Tetsuro

    2008-01-01

    We examined the mechanism whereby nanoparticles of gold embedded in silica become elongated and oriented parallel to each other on ion irradiation. Elongation occurred for gold particles with radii smaller than 25 nm. The process was simulated by using a thermal spike model. For small-radius nanoparticles, ion irradiation raises the temperature above the melting points of both gold and silica, whereas for larger nanoparticles neither the gold nanoparticle nor the surrounding silica matrix is ...

  13. Development and experimental application of a gold liquid metal ion source

    Energy Technology Data Exchange (ETDEWEB)

    Davies, N.; Weibel, D.E.; Blenkinsopp, P.; Lockyer, N.; Hill, R.; Vickerman, J.C

    2003-01-15

    A liquid metal ion source (LMIS) based upon a gold/germanium eutectic has been developed. The LMIS emits a variety of ions including monatomic gold and gold clusters. Gold ions have been utilised for SIMS analysis of the polypeptide gramicidin and the polymer poly(ethylene-terepthalate) (PET). It has been found that monatomic gold (Au{sup +}) increases secondary ion yields up to a factor of four compared to gallium, for both gramicidin and PET. The Au{sub 3}{sup +} cluster produces a strong non-linear increase in yield over monatomic gold, for both gramicidin and PET. This effect is greatest at high mass, the yield for the gramicidin molecular ion increasing by a factor of over 60. No evidence has been found to suggest increased fragmentation as a result of cluster ion bombardment. The LMIS also exhibits good static SIMS imaging capacity.

  14. Gene expression profiling of macrophages: implications for an immunosuppressive effect of dissolucytotic gold ions

    Directory of Open Access Journals (Sweden)

    Seifert Oliver

    2012-11-01

    Full Text Available Abstract Background Gold salts has previously been used in the treatment of rheumatoid arthritis but have been replaced by biologicals such as TNF-α inhibitors. The mechanisms behind the anti-inflammatory effect of metallic gold ions are still unknown, however, recent data showed that charged gold atoms are released from pure metallic gold implants by macrophages via a dissolucytosis membrane, and that gold ions are taken up by local macrophages, mast cells and to some extent fibroblasts. These findings open the question of possible immunomodulatory effects of metallic gold and motivate efforts on a deeper understanding of the effect of metallic gold on key inflammatory cells as macrophages. Methods Human macrophage cells (cell line THP-1 were grown on gold foils and intracellular uptake was analysed by autometallography. The impact of phagocytised gold ions on viability of THP-1 cells was investigated by trypan blue staining and TUNEL assay. The global gene expression profile of THP-1 cells after incorporation of gold ions was studied using microarray analysis comprising approximately 20,000 genes. The gene expression data was confirmed by measurement of secreted proteins. Results Autometallography showed intracellular uptake of gold ions into THP-1 cells. No significant effect on viability of THP-1 cells was demonstrated. Our data revealed a unique gene expression signature of dissolucytotic THP-1 cells that had taken up gold ions. A large number of regulated genes were functionally related to immunomodulation. Gold ion uptake induced downregulation of genes involved in rheumatoid arthritis such as hepatocyte growth factor, tenascin-C, inhibitor of DNA binding 1 and 3 and matrix metalloproteinase 13. Conclusion The data obtained in this study offer new insights into the mode of action of gold ions and suggest for the investigation of effects on other key cells and a possible future role of metallic gold as implants in rheumatoid arthritis or

  15. Raman scattering in silicon disordered by gold ion implantation

    Energy Technology Data Exchange (ETDEWEB)

    Lavrentiev, Vasily; Vacik, Jiri; Vosecek, Vaclav [NS Lab, Nuclear Physics Institute AS CR, Rez-130, Husinec 250 68 (Czech Republic); Vorlicek, Vladimir [Institute of Physics AS CR, Na Slovance 2, Prague 182 21 (Czech Republic)

    2010-08-15

    Si (111) covered by a 250-nm thick SiO{sub 2} surface layer has been disordered through implantation of 3.035 MeV gold ions within broad range of fluences from 1 x 10{sup 13} ions/cm{sup 2} to 1 x 10{sup 16} ions/cm{sup 2}. Raman spectroscopy (514.5 nm laser) was applied for characterization of the silicon disordering. Variation of the Raman spectra of silicon after low-fluence implantation (fluences lower than 5 x 10{sup 14} ions/cm{sup 2}) in the vicinity of the transverse optical phonon (1TO) peak reflects the coexistence of bulk Si crystals (c-Si) and Si nanocrystals (nc-Si) in the implanted layer. Implantation with higher fluences yields only the stable 470 cm{sup -1} 1TO peak, corresponding to formation of amorphous phase (a-Si), in this region of the spectra. Detailed analysis of the silicon disorder was performed through calculation of the transverse acoustical phonon (1TA) peak area. The fluence dependence of the peak area reveals qualitative correlation with the depth profile of structural defects in the modified Si layer evaluated from RBS (Rutherford backscattering) experiment and from SRIM (stopping and range of ions in matter) code simulation. This correlation suggests a decrease of the structural disorder in the modified layer region enriched by vacancies. (Abstract Copyright [2010], Wiley Periodicals, Inc.)

  16. Anodic dissolution of gold in alkaline solutions containing thiourea, thiosulfate and sulfite ions

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Gold dissolves electrochemically in alkaline solutions containing ligands to form complex ions with gold ion. Therefore, selective leaching of noble metals is expected without dissolution of base metals such as steels, aluminum alloys in scrap treatment. Gold electrodes were investigated using linear sweep voltammetry, EQCM method and potentiostatic electrolysis in alkaline solutions containing thiourea, Na2SO3 and Na2S2O3. The solution composition, electrode potential affect gold dissolution rate and current efficiency. The gold dissolved from anode electrode forms complex ions, suspension particles as compound precipitates and deposits on cathode electrode as a metal. Anodic efficiency for gold dissolution is between 10% and 22%. This is caused by the oxidation decomposition of sulfite ions and thiourea. The stability of the alkaline solution containing these elements was also estimated by capillary electrophoresis technique.

  17. X-Ray Fluorescence Determination of Trace Gold in an Ion-Exchange Resin

    OpenAIRE

    Mikhailov, I. F.; Baturin, A. A.; A. I. Mikhailov; L.P. Fomina

    2014-01-01

    The use of portable X ray optics with a secondary radiator in the determination of trace gold in an ion exchange resin within the mass fraction range of 1–50 ppm is described. It is shown that the secondary radiator design with primary radiation filtering allows one to determine trace gold in an ion exchange resin when the mass fraction of gold is lower than 1 ppm.

  18. Effect of gold ion concentration on size and properties of gold nanoparticles in TritonX-100 based inverse microemulsions

    Science.gov (United States)

    Ahmad, Tokeer; Wani, Irshad A.; Ahmed, Jahangeer; Al-Hartomy, Omar A.

    2014-04-01

    Gold nanoparticles have been prepared successfully using TritonX-100 inverse microemulsion at different concentrations of HAuCl4 (0.1, 0.05, 0.04, 0.03, 0.02 and 0.01 M). We have studied the effect of gold ion concentration on the particle size, morphology, surface area and optical properties of the gold nanoparticles. The gold nanoparticles were characterized by X-ray diffraction, transmission electron microscopy, UV-Visible spectroscopy and Brunauer-Emmett-Teller surface area analysis. X-ray diffraction studies show the monophasic nature of the gold nanoparticles. TritonX-100 stabilized gold nanoparticles were appeared to be agglomerated at higher concentrations (0.1 and 0.05 M) of Au3+ with an average grain size of 60 and 50 nm, respectively. Monodisperse and uniform gold nanoparticles with well-defined morphologies of an average grain size of 15 and 25 nm were obtained at lower concentrations (0.01 and 0.02 M). UV-Visible spectroscopy shows the characteristic surface plasmon resonance peak ~540 nm along with the peaks at shorter and longer wavelengths may be due to the higher order plasmon resonance of the gold nanoparticles. The surface areas of the gold nanoparticles were found to be in the range of 5.8-107 m2/g which were well in agreement with the electron microscopic studies.

  19. Dielectronic recombination of Co-like gold ions

    International Nuclear Information System (INIS)

    Ab initio calculation of the total dielectronic recombination (DR) rate coefficient from the ground and the first excited states of Co-like gold is performed employing the relativistic distorted-wave approximation with configuration interaction. The DR contributions are explicitly taken into account from the relevant complexes of a Ni-like ion: 3d33/2 3d65/2n'l', 3p5 3d10n'l', 3s 3p63d10n'l', 3d8 4ln'l', 3p5 3d9 4ln'l' and 3s 3p6 3d9 4ln'l' with n' ≤ 25, and 3d8 5ln'l' with n' ≤ 9. The contributions from a higher n' complex are evaluated by an extrapolation procedure. The DR contributions mainly come from complex series 3d8 4ln'l' and 3p5 3d9 4ln'l'. The complex series 3p5 3d10n'l' and 3d8 5ln'l' also contribute significantly to the total DR rates at low and high electron temperatures, respectively. The l' and n' dependences of the partial rate coefficient are investigated. The possible important decays into autoionizing levels followed by radiative cascade (DAC) from the resonant levels are taken into account, as well as the resonant stabilizing and non-resonant stabilizing transitions. The inclusion of DAC transitions enlarges the total DR rate coefficients by a factor of about 10% and may break down the usual n'-3 scaling law of the partial DR rates along some complex series. To evaluate the high n' contributions from these complex series, the level-by-level extrapolation method is developed to include DAC effects. The total DR rate coefficients are fitted to an empirical formula. The present results are compared with those from the semiempirical Burgess-Merts approximation. The DR rate coefficients of Ni-like gold are also presented and compared to those of Co-like gold. In addition, some comments on the published DR data for the NiI isoelectronic sequence are drawn from the present calculation

  20. Gold

    International Nuclear Information System (INIS)

    Present article is devoted to gold content in fluorite. In order to obtain the comprehensive view on gold distribution in fluorite the fluorite formations of various geologic deposits and ores of Kazakhstan, Uzbekistan, Tajikistan, Mongolia, Moldova and some geologic deposits of Russia were studied. The gold content in fluorite of geologic deposits of various mineralogical and genetic type was defined.

  1. Gold nanoparticles solid contact for ion-selective electrodes of highly stable potential readings.

    Science.gov (United States)

    Jaworska, Ewa; Wójcik, Michał; Kisiel, Anna; Mieczkowski, Józef; Michalska, Agata

    2011-09-30

    Internal solution free ion-selective electrodes were prepared applying for the first time gold nanoparticles as a solid contact layer. The presence of a layer of gold nanoparticles stabilized with aliphatic thiols at the back side of the membrane resulted in highly stable potentiometric responses of the sensors, good selectivities and close to Nernstian slopes. Electrochemical studies have confirmed that the applied material is effectively working as capacitive solid contact, yielding high stability sensors. PMID:21872048

  2. Digging gold: keV He+ ion interaction with Au

    Directory of Open Access Journals (Sweden)

    Vasilisa Veligura

    2013-07-01

    Full Text Available Helium ion microscopy (HIM was used to investigate the interaction of a focused He+ ion beam with energies of several tens of kiloelectronvolts with metals. HIM is usually applied for the visualization of materials with extreme surface sensitivity and resolution. However, the use of high ion fluences can lead to significant sample modifications. We have characterized the changes caused by a focused He+ ion beam at normal incidence to the Au{111} surface as a function of ion fluence and energy. Under the influence of the beam a periodic surface nanopattern develops. The periodicity of the pattern shows a power-law dependence on the ion fluence. Simultaneously, helium implantation occurs. Depending on the fluence and primary energy, porous nanostructures or large blisters form on the sample surface. The growth of the helium bubbles responsible for this effect is discussed.

  3. Electron production by sensitizing gold nanoparticles irradiated by fast ions

    CERN Document Server

    Verkhovtsev, Alexey V; Solov'yov, Andrey V

    2014-01-01

    The yield of electrons generated by gold nanoparticles due to irradiation by fast charged projectiles is estimated. The results of calculations are compared to those obtained for pure water medium. It is demonstrated that a significant increase in the number of emitted electrons arises from collective electron excitations in the nanoparticle. The dominating enhancement mechanisms are related to the formation of (i) plasmons excited in a whole nanoparticle, and (ii) atomic giant resonances due to excitation of d electrons in individual atoms. Decay of the collective electron excitations in a nanoparticle embedded in a biological medium thus represents an important mechanism of the low-energy electron production. Parameters of the utilized model approach are justified through the calculation of the photoabsorption spectra of several gold nanoparticles, performed by means of time-dependent density-functional theory.

  4. Ion beam studies of archaeological gold jewellery items

    Science.gov (United States)

    Demortier, G.

    1996-06-01

    Analytical work on material of archaeological interest performed at LARN mainly concerns gold jewellery, with an emphasis to solders on the artefacts and to gold plating or copper depletion gilding. PIXE, RBS but also PIGE and NRA have been applied to a large variety of items. On the basis of elemental analysis, we have identified typical workmanship of ancient goldsmiths in various regions of the world: finely decorated Mesopotamian items, Hellenistic and Byzantine craftsmanship, cloisonne of the Merovingian period, depletion gilding on Pre-Colombian tumbaga. This paper is some shortening of the work performed at LARN during the last ten years. Criteria to properly use PIXE for quantitative analysis of non-homogeneous ancient artefacts presented at the 12th IBA conference in 1995 are also shortly discussed.

  5. Ion beam studies of archaeological gold jewellery items

    International Nuclear Information System (INIS)

    Analytical work on material of archaeological interest performed at LARN mainly concerns gold jewellery, with an emphasis to solders on the artefacts and to gold plating or copper depletion gilding. PIXE, RBS but also PIGE and NRA have been applied to a large variety of items. On the basis of elemental analysis, we have identified typical workmanship of ancient goldsmiths in various regions of the world: finely decorated Mesopotamian items, Hellenistic and Byzantine craftsmanship, cloisonne of the Merovingian period, depletion gilding on Pre-Colombian tumbaga. This paper is some shortening of the work performed at LARN during the last ten years. Criteria to properly use PIXE for quantitative analysis of non-homogeneous ancient artefacts presented at the 12th IBA conference in 1995 are also shortly discussed. (orig.)

  6. Ion beam studies of archaeological gold jewellery items

    Energy Technology Data Exchange (ETDEWEB)

    Demortier, G. [Facultes Universitaires Notre-Dame de la Paix, Namur (Belgium). Lab. d`Analyses par Reactions Nucleaires

    1996-06-01

    Analytical work on material of archaeological interest performed at LARN mainly concerns gold jewellery, with an emphasis to solders on the artefacts and to gold plating or copper depletion gilding. PIXE, RBS but also PIGE and NRA have been applied to a large variety of items. On the basis of elemental analysis, we have identified typical workmanship of ancient goldsmiths in various regions of the world: finely decorated Mesopotamian items, Hellenistic and Byzantine craftsmanship, cloisonne of the Merovingian period, depletion gilding on Pre-Colombian tumbaga. This paper is some shortening of the work performed at LARN during the last ten years. Criteria to properly use PIXE for quantitative analysis of non-homogeneous ancient artefacts presented at the 12th IBA conference in 1995 are also shortly discussed. (orig.).

  7. FY2014 Parameters for Helions and Gold Ions in Booster, AGS, and RHIC

    Energy Technology Data Exchange (ETDEWEB)

    Gardner, C. J. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.

    2014-08-15

    The nominal parameters for helions (helion is the bound state of two protons and one neutron, the nucleus of a helium-3 atom) and gold ions in Booster, AGS, and RHIC are given for the FY2014 running period. The parameters are found using various formulas to derive mass, helion anomalous g-factor, kinetic parameters, RF parameters, ring parameters, etc..

  8. Adsorption of gold ions from industrial wastewater using activated carbon derived from hard shell of apricot stones - an agricultural waste.

    Science.gov (United States)

    Soleimani, Mansooreh; Kaghazchi, Tahereh

    2008-09-01

    In this study, hard shell of apricot stones was selected from agricultural solid wastes to prepare effective and low cost adsorbent for the gold separation from gold-plating wastewater. Different adsorption parameters like adsorbent dose, particle size of activated carbon, pH and agitation speed of mixing on the gold adsorption were studied. The results showed that under the optimum operating conditions, more than 98% of gold was adsorbed onto activated carbon after only 3h. The equilibrium adsorption data were well described by the Freundlich and Langmuir isotherms. Isotherms have been used to obtain thermodynamic parameters. Gold desorption studies were performed with aqueous solution mixture of sodium hydroxide and organic solvents at ambient temperatures. Quantitative recovery of gold ions is possible by this method. As hard shell of apricot stones is a discarded as waste from agricultural and food industries, the prepared activated carbon is expected to be an economical product for gold ion recovery from wastewater. PMID:18178431

  9. Ion irradiation of gold inclusions in SiO2: Experimental evidence for inverse Ostwald ripening

    International Nuclear Information System (INIS)

    When sub mm size gold inclusions in SiO2 are irradiated with MeV gold ions, a ring of nanometer-size clusters is formed in their immediate vicinity. The size, density and radial distribution of these nanoclusters were determined. Our observations are in agreement with a recent prediction that in a driven system, under appropriate ion beam and temperature conditions, the steady-state solute concentration's dependence on precipitate size may be opposite to that expected from the equilibrium Gibbs-Thomson relation. Kinetic Monte-Carlo simulations account for additional experimental results: the irradiation-induced increase in solute concentration can promote nucleation of additional precipitates around the first ring. The latter finding contradicts the usual assumption that ion beam mixing hinders nucleation

  10. Gold nanoparticles with cyclic phenylazomethines: one-pot synthesis and metal ion sensing.

    Science.gov (United States)

    Shomura, Ryo; Chung, Keum Jee; Iwai, Hideo; Higuchi, Masayoshi

    2011-07-01

    New gold nanoparticles covered with cyclic phenylazomethine (CPA) were obtained by a one-pot synthesis. It is confirmed by XPS that imines of CPA in the nanoparticles (Au-CPA) are partially reduced to amines. The amine part of CPA in Au-CPA is attached to the surfaces of gold nanoparticles, and the imine part works as a redox-active site. A glassy carbon electrode modified with Au-CPA was revealed to work as an electrochemical probe for metal ion sensing.

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

    Science.gov (United States)

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

    2013-05-28

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

  12. Size-dependent stability toward dissociation and ligand binding energies of phosphine-ligated gold cluster ions

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, Grant E.; Priest, Thomas A.; Laskin, Julia

    2014-01-01

    The stability of sub-nanometer size gold clusters ligated with organic molecules is of paramount importance to the scalable synthesis of monodisperse size-selected metal clusters with highly tunable chemical and physical properties. For the first time, a Fourier transform ion cyclotron resonance mass spectrometer (FT-ICR-MS) equipped with surface induced dissociation (SID) has been employed to investigate the time and collision energy resolved fragmentation behavior of cationic doubly charged gold clusters containing 7-9 gold atoms and 6-7 triphenylphosphine (TPP) ligands prepared by reduction synthesis in solution. The TPP ligated gold clusters are demonstrated to fragment through three primary dissociation pathways: (1) Loss of a neutral TPP ligand from the precursor gold cluster, (2) asymmetric fission and (3) symmetric fission and charge separation of the gold core resulting in formation of complementary pairs of singly charged fragment ions. Threshold energies and activation entropies of these fragmentation pathways have been determined employing Rice-Ramsperger-Kassel-Marcus (RRKM) modeling of the experimental SID data. It is demonstrated that the doubly charged cluster ion containing eight gold atoms and six TPP ligands, (8,6)2+, exhibits exceptional stability compared to the other cationic gold clusters examined in this study due to its large ligand binding energy of 1.76 eV. Our findings demonstrate the dramatic effect of the size and extent of ligation on the gas-phase stability and preferred fragmentation pathways of small TPP-ligated gold clusters.

  13. Effect of Ions and Ionic Strength on Surface Plasmon Absorption of Single Gold Nanowires.

    Science.gov (United States)

    Baral, Susil; Green, Andrew J; Richardson, Hugh H

    2016-06-28

    The local temperature change from a single optically excited gold nanowire, lithographically prepared on Al0.94Ga0.06N embedded with Er(3+) ions, is measured in air, pure water, and various concentrations of aqueous solutions of ionic solutes of NaCl, Na2SO4, and MgSO4. The absorption cross section of the nanowire under pure water (2.25 × 10(-14) m(2)) and different solution ionic strength is measured from the slopes of temperature change versus laser intensity plots. Addition of charges into the solution decreases the amount of heat generated during optical excitation of the gold nanostructures because the absorption cross section of the gold nanowire is attenuated. A Langmuir-type behavior of the absorption cross section with ionic strength is observed that is identified with an increase in the occupancy of screened interfacial charges. The absorption cross section of the nanowire decreases with ionic strength until a saturation value of 9 × 10(-15) m(2), where saturation in the occupancy of screened interfacial charge occurs. Dynamic measurements of temperature for a single gold nanowire immersed in a microchannel flow cell show a sharp and fast temperature drop for the flow of ionic solution compared to the pure (deionized) water, suggesting that the technique can be developed as a sensor probe to detect the presence of ions in solution. PMID:27215955

  14. Controlled growth of gold nanoparticles in zeolite L via ion-exchange reactions and thermal reduction processes

    KAUST Repository

    Zeng, Shangjing

    2014-09-01

    The growth of gold nanoparticles in zeolite can be controlled using ion-exchange reactions and thermal reduction processes. We produce a number of different sizes of the gold nanoparticles with the particle size increasing with increased temperature of the final heat treatment. © 2014 Elsevier B.V.

  15. Single pass electron beam cooling of gold ions between EBIS LINAC and booster is theoretically possible!

    Energy Technology Data Exchange (ETDEWEB)

    Hershcovitch, A.

    2011-01-01

    Electron beam cooling is examined as an option to reduce momentum of gold ions exiting the EBIS LINAC before injection into the booster. Electron beam parameters are based on experimental data (obtained at BNL) of electron beams extracted from a plasma cathode. Many issues, regarding a low energy high current electron beam that is needed for electron beam cooling to reduce momentum of gold ions exiting the EBIS LINAC before injection into the booster, were examined. Computations and some experimental data indicate that none of these issues is a show stopper. Preliminary calculations indicate that single pass cooling is feasible; momentum spread can be reduced by more than an order of magnitude in about one meter. Hence, this option cooling deserves further more serious considerations.

  16. FY2014 Parameters for Gold Ions in Booster, AGS, and RHIC

    Energy Technology Data Exchange (ETDEWEB)

    Gardner, C. J. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.

    2014-07-30

    The nominal parameters for gold ions in Booster, AGS, and RHIC are given for the FY2014 running period. The parameters are worked out using various formulas to derive mass, kinetic parameters, RF parameters, ring parameters, etc.. The ''standard setup'', ''medium-energy'', and ''low-energy'' parameters are summarized in separate sections.

  17. Analysis of cardiac tissue by gold cluster ion bombardment

    Science.gov (United States)

    Aranyosiova, M.; Chorvatova, A.; Chorvat, D.; Biro, Cs.; Velic, D.

    2006-07-01

    Specific molecules in cardiac tissue of spontaneously hypertensive rats are studied by using time-of-flight secondary ion mass spectrometry (TOF-SIMS). The investigation determines phospholipids, cholesterol, fatty acids and their fragments in the cardiac tissue, with special focus on cardiolipin. Cardiolipin is a unique phospholipid typical for cardiomyocyte mitochondrial membrane and its decrease is involved in pathologic conditions. In the positive polarity, the fragments of phosphatydilcholine are observed in the mass region of 700-850 u. Peaks over mass 1400 u correspond to intact and cationized molecules of cardiolipin. In animal tissue, cardiolipin contains of almost exclusively 18 carbon fatty acids, mostly linoleic acid. Linoleic acid at 279 u, other fatty acids, and phosphatidylglycerol fragments, as precursors of cardiolipin synthesis, are identified in the negative polarity. These data demonstrate that SIMS technique along with Au 3+ cluster primary ion beam is a good tool for detection of higher mass biomolecules providing approximately 10 times higher yield in comparison with Au +.

  18. Synthesis of a stable gold hydrosol by the reduction of chloroaurate ions by the amino acid, aspartic acid

    Indian Academy of Sciences (India)

    Saikat Mandal; P R Selvakannan; Sumant Phadtare; Renu Pasricha; Murali Sastry

    2002-10-01

    Development of reliable protocols for the synthesis of nanoparticles of well-defined sizes and good monodispersity is an important aspect of nanotechnology. In this paper, we present details of the synthesis of gold nanoparticles of good monodispersity by the reduction of aqueous chloroaurate ions by the amino acid, aspartic acid. The colloidal gold solution thus formed is extremely stable in time, indicating electrostatic stabilization via nanoparticle surface-bound amino acid molecules. This observation has been used to modulate the size of the gold nanoparticles in solution by varying the molar ratio of chloroaurate ions to aspartic acid in the reaction medium. Characterization of the aspartic acid-reduced gold nanoparticles was carried out by UV-visible spectroscopy, thermogravimetric analysis and transmission electron microscopy. The use of amino acids in the synthesis and stabilization of gold nanoparticle in water has important implications in the development of new protocols for generation of bioconjugate materials.

  19. Ultra-Peripheral Collisions with gold ions in STAR

    CERN Document Server

    ,

    2016-01-01

    In 2010, the STAR Collaboration collected 38 million low-multiplicity triggers for ultra-peripheral collision studies. We present new results involving photonuclear interactions in ultra-peripheral relativistic heavy ion collisions (UPCs), based on an analysis of 384,000 photoproduced pion pairs, from $\\rho$, $\\omega$ and direct $\\pi^+\\pi^-$ pair production.The $\\omega$ component is clearly visible through its interference with the $\\rho$ peak. The relative amplitudes of the three components have been measured, along with the phase angle between the $\\rho$ and $\\omega$ components. Using a two-year (2010 and 2011) dataset, we explore higher mass final states, and observe a $\\pi^+\\pi^-$ state with a mass of $1653 \\pm 10$ MeV and a width of $164\\pm 15$ MeV (statistical errors only). The state is at least roughly compatible with the $\\rho_3(1690)$. The $\\rho^0$ squared momentum transfer ($t$) spectrum exhibits a spectrum with both coherent and incoherent prodution. The coherent component shows two characteristic ...

  20. Facile purification of colloidal NIR-responsive gold nanorods using ions assisted self-assembly

    Directory of Open Access Journals (Sweden)

    Guo Zhirui

    2011-01-01

    Full Text Available Abstract Anisotropic metal nanoparticles have been paid much attention because the broken symmetry of these nanoparticles often leads to novel properties. Anisotropic gold nanoparticles obtained by wet chemical methods inevitably accompany spherical ones due to the intrinsically high symmetry of face-centred cubic metal. Therefore, it is essential for the purification of anisotropic gold nanoparticles. This work presents a facile, low cost while effective solution to the challenging issue of high-purity separation of seed-mediated grown NIR-responsive gold nanorods from co-produced spherical and cubic nanoparticles in solution. The key point of our strategy lies in different shape-dependent solution stability between anisotropic nanoparticles and symmetric ones and selective self-assembly and subsequent precipitation can be induced by introducing ions to the as-made nanorod solution. As a result, gold nanorods of excellent purity (97% in number density have been obtained within a short time, which has been confirmed by SEM observation and UV-vis-NIR spectroscopy respectively. Based on the experimental facts, a possible shape separation mechanism was also proposed.

  1. Radiosensitizing effect of gold nanoparticles in carbon ion irradiation of human cervical cancer cells

    Science.gov (United States)

    Kaur, Harminder; Avasthi, D. K.; Pujari, Geetanjali; Sarma, Asitikantha

    2013-07-01

    Noble metal nanoparticles have received considerable attention in biotechnology for their role in bio sensing due to surface plasmon resonance, medical diagnostics due to better imaging contrast and therapy. The radiosensitization effect of gold nanoparticles (AuNP) has been gaining popularity in radiation therapy of cancer cells. The better depth dose profile of energetic ion beam proves its superiority over gamma radiation for fighting against cancer. In the present work, the glucose capped gold nanoparticles (Glu-AuNP) were synthesised and internalized in the HeLa cells. Transmission electron microscopic analysis of ultrathin sections of Glu-AuNP treated HeLa cells confirmed the internalization of Glu-AuNPs. Control HeLa cells and Glu-AuNp treated HeLa cells were irradiated at different doses of 62 MeV 12C ion beam (LET - 290keV/μm) at BIO beam line of using 15UD Pelletron accelerator at Inter University Accelerator Centre, New Delhi, India. The survival fraction was assessed by colony forming assay which revealed that the dose of carbon ion for 90% cell killing in Glu-AuNP treated HeLa cells and control HeLa cells are 2.3 and 3.2 Gy respectively. This observation shows ˜ 28% reduction of 12C6+ ion dose for Glu-AuNP treated HeLa cells as compared to control HeLa cells.

  2. Highly sensitive electrochemical lead ion sensor harnessing peptide probe molecules on porous gold electrodes.

    Science.gov (United States)

    Su, Wenqiong; Cho, Misuk; Nam, Jae-Do; Choe, Woo-Seok; Lee, Youngkwan

    2013-10-15

    Lead ion is one of the most hazardous and ubiquitous heavy metal pollutants and poses an increasing threat to the environment and human health. This necessitates rapid and selective detection and/or removal of lead ions from various soil and water resources. Recently, we identified several Pb²⁺ binding peptides via phage display technique coupled with chromatographic biopanning (Nian et al., 2010) where a heptapeptide (TNTLSNN) capable of recognizing Pb²⁺ with high affinity and specificity evolved. In the present study, an electrochemical sensor harnessing this Pb²⁺ affinity peptide as a probe on a porous gold electrode was developed. The three dimensional porous gold electrode was obtained from electrochemical deposition using the dynamic hydrogen bubble template method. A thin layer of poly(thiophene acetic acid) (PTAA) was coated on the porous gold surface. The Pb²⁺ recognizing peptide was immobilized via amide linkage on the PTAA. The developed biosensor was demonstrated to be fast, selective and reproducible in Pb²⁺ etection, exhibiting Pb²⁺-specific peak current values around -0.15 V in a broad concentration range (1-1×10⁷ nM) in 10 min despite the repeated use after regeneration. PMID:23707872

  3. Colorimetric detection of Cu2+ and Pb2+ ions using calix[4]arene functionalized gold nanoparticles

    Indian Academy of Sciences (India)

    Ravi Gunupuru; Debdeep Maity; Gopala R Bhadu; Ashish Chakraborty; Divesh N Srivastava; Parimal Paul

    2014-05-01

    Calixarene functionalized gold nanoparticles (CFAuNPs) have been prepared and characterized by spectroscopic and microscopic (TEM) techniques. To use this material as potential colorimetric sensor, the binding property of this new material has been investigated with a large number of metal ions. It exhibited sharp colour change from dark brown to green and blue, detectable by naked-eye, in the presence of Cu2+ and Pb2+ ions, respectively. It has also triggered substantial change in surface plasmon resonance (SPR) band of the functionalized gold nanoparticles, which in case of Pb(II) is due to the inter particle plasmon coupling arising from the metal-induced aggregation of the nanoparticles and for Cu(II), it is because of the formation of AuCu alloy due to anti-galvanic exchange. The size and aggregation of the nanoparticles are confirmed from HRTEM images, elemental analysis and the line profiling for both the metal ions have been done by STEM-EDX analysis.

  4. Visualization of expanding warm dense gold and diamond heated rapidly by laser-generated ion beams

    International Nuclear Information System (INIS)

    With the development of several novel heating sources, scientists can now heat a small sample isochorically above 10,000 K. Although matter at such an extreme state, known as warm dense matter, is commonly found in astrophysics (e.g., in planetary cores) as well as in high energy density physics experiments, its properties are not well understood and are difficult to predict theoretically. This is because the approximations made to describe condensed matter or high-temperature plasmas are invalid in this intermediate regime. A sufficiently large warm dense matter sample that is uniformly heated would be ideal for these studies, but has been unavailable to date. We have used a beam of quasi-monoenergetic aluminum ions to heat gold and diamond foils uniformly and isochorically. For the first time, we visualized directly the expanding warm dense gold and diamond with an optical streak camera. Furthermore, we present a new technique to determine the initial temperature of these heated samples from the measured expansion speeds of gold and diamond into vacuum. We anticipate the uniformly heated solid density target will allow for direct quantitative measurements of equation-of-state, conductivity, opacity, and stopping power of warm dense matter, benefiting plasma physics, astrophysics, and nuclear physics

  5. Colorimetric Detection of Cadmium Ions Using DL-Mercaptosuccinic Acid-Modified Gold Nanoparticles.

    Science.gov (United States)

    Chen, Na; Chen, Jun; Yang, Jing-Hua; Bai, Lian-Yang; Zhang, Yu-Ping

    2016-01-01

    A colorimetric assay has been developed for detection of Cd²⁺ utilizing DL-mercaptosuccinic acid-modified gold nanoparticles (MSA-AuNPs). The method showed good selectivity for Cd²⁺ over other metal ions. As a result, the linear relationships (r > 0.9606) between concentration 0.07 mM and 0.20 mM for cadmium ion were obtained. The detection limit was as low as 0.07 mM by the naked eye. The effect of pH on the aggregation was optimized. The MSA-AuNPs probe could be used to detect Cd²⁺ in an aqueous solution based on the aggregation-induced color change of MSA-AuNPs. PMID:27398533

  6. Direct patterning of gold oxide thin films by focused ion-beam irradiation

    Science.gov (United States)

    Machalett, F.; Edinger, K.; Melngailis, J.; Diegel, M.; Steenbeck, K.; Steinbeiss, E.

    For direct writing of electrically conducting connections and areas into insulating gold oxide thin films a scanning Ar+ laser beam and a 30 keV Ga+ focused ion beam (FIB) have been used. The gold oxide films are prepared by magnetron sputtering under argon/oxygen plasma. The patterning of larger areas (dimension 10-100 μm) has been carried out with the laser beam by local heating of the selected area above the decomposition temperature of AuOx (130-150 °C). For smaller dimensions (100 nm to 10 μm) the FIB irradiation could be used. With both complementary methods a reduction of the sheet resistance by 6-7 orders of magnitude has been achieved in the irradiated regions (e.g. with FIB irradiation from 1.5×107 Ω/□ to approximately 6 Ω/□). The energy-dispersive X-ray analysis (EDX) show a considerably reduced oxygen content in the irradiated areas, and scanning electron microscopy (SEM), as well as atomic force microscopy (AFM) investigations, indicate that the FIB patterning in the low-dose region (1014 Ga+/cm2) is combined with a volume reduction, which is caused by oxygen escape rather than by sputtering.

  7. FY08 parameters for the injection, acceleration, and extraction of gold ions and deuterons in the booster, AGS, and RHIC

    Energy Technology Data Exchange (ETDEWEB)

    Gardner, C.J.

    2010-08-01

    A Gold ion with charge eQ has N = 197 Nucleons, Z = 79 Protons, and (Z-Q) electrons. (Here Q is an integer and e is the charge of a single proton.) The mass is m = au - Qm{sub e} + E{sub b}/c{sup 2} (1) where a = 196.966552 is the relative atomic mass [1, 2] of the neutral Gold atom, u = 931.494013 MeV/c{sup 2} is the unified atomic mass unit [3], and m{sub e}c{sup 2} = .510998902 MeV is the electron mass [3]. E{sub b} is the binding energy of the Q electrons removed from the neutral Gold atom. This amounts to 0.332 MeV for the helium-like gold ion (Q = 77) and 0.517 MeV for the fully stripped ion. For the Au{sup 31+} ion we have E{sub b} = 13.5 keV. These numbers are given in Ref. [4]. The deuteron mass [3] is 1875.612762(75) MeV/c{sup 2}.

  8. FY10 parameters for the injection, acceleration, and extraction of gold ions in booster, AGS, and RHIC

    Energy Technology Data Exchange (ETDEWEB)

    Gardner, C.J.

    2010-08-01

    A Gold ion with charge eQ has N = 197 Nucleons, Z = 79 Protons, and (Z-Q) electrons. (Here Q is an integer and e is the charge of a single proton.) The mass is m = au - Qm{sub e} + E{sub b}/c{sup 2} (1) where a = 196.966552 is the relative atomic mass [1, 2] of the neutral Gold atom, u = 931.494013 MeV/c{sup 2} is the unified atomic mass unit [3], and m{sub e}c{sup 2} = .510998902 MeV is the electron mass [3]. E{sub b} is the binding energy of the Q electrons removed from the neutral Gold atom. This amounts to 0.332 MeV for the helium-like gold ion (Q = 77) and 0.517 MeV for the fully stripped ion. For the Au{sup 31+} ion we have E{sub b} = 13.5 keV. These numbers are given in Ref. [4].

  9. ITO electrode modified by a gold ion implantation technique for direct electrocatalytic sensing of hydrogen peroxide

    International Nuclear Information System (INIS)

    We report on a simple strategy for the fabrication of gold nanoparticles (AuNPs) on an indium tin oxide substrate using a modified ion implantation method. The morphology, structure and electrochemical features of AuNPs were characterized by atomic force microscopy, electrochemical impedance spectroscopy and cyclic voltammetry. The modified electrode has a large electrochemically active surface and enables strong loading with cytochrome c (Cyt c) proteins. It undergoes enhanced electron transfer at uncompromised electrochemical activity, and also displays good stability and repeatability. The immobilized Cyt c exhibits good electrocatalytic activity towards hydrogen peroxide (H2O2), with a linear relationship between the catalytic current during differential pulse voltammetry and the concentration of H2O2 in the 0.05 μM to 0.2 μM range. The detection limit (S/N = 3) is 0. 01 μM. (author)

  10. Graphene quantum dots functionalized gold nanoparticles for sensitive electrochemical detection of heavy metal ions

    International Nuclear Information System (INIS)

    Graphene quantum dots (GQDs) are emerging zero dimensional materials promising various novel applications due to their extraordinary physicochemical properties. In this work, novel conjugates of GQDs and gold nanoparticles (AuNPs) are synthesized and used for sensitive electrochemical detection of heavy metal ions (Hg2+ and Cu2+). Ultralow detection limit (0.02 nM with S/N = 6.25 for Hg2+ and 0.05 nM with S/N = 4.81 for Cu2+) and high sensitivity (2.47 μA/nM for Hg2+ and 3.69 μA/nM for Cu2+) have been achieved

  11. Gold nanoparticles for the colorimetric and fluorescent detection of ions and small organic molecules

    Science.gov (United States)

    Liu, Dingbin; Wang, Zhuo; Jiang, Xingyu

    2011-04-01

    In recent years, gold nanoparticles (AuNPs) have drawn considerable research attention in the fields of catalysis, drug delivery, imaging, diagnostics, therapy and biosensors due to their unique optical and electronic properties. In this review, we summarized recent advances in the development of AuNP-based colorimetric and fluorescent assays for ions including cations (such as Hg2+, Cu2+, Pb2+, As3+, Ca2+, Al3+, etc) and anions (such as NO2-, CN-, PF6-, F-, I-, oxoanions), and small organic molecules (such as cysteine, homocysteine, trinitrotoluene, melamine and cocaine, ATP, glucose, dopamine and so forth). Many of these species adversely affect human health and the environment. Moreover, we paid particular attention to AuNP-based colorimetric and fluorescent assays in practical applications.

  12. Soft Landing of Mass-Selected Gold Clusters: Influence of Ion and Ligand on Charge Retention and Reactivity

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, Grant E.; Laskin, Julia

    2015-02-01

    Herein, we employ a combination of reduction synthesis in solution, soft landing of mass-selected precursor and product ions, and in situ time-of-flight secondary ion mass spectrometry (TOF-SIMS) to examine the influence of ion and the length of diphosphine ligands on the charge retention and reactivity of ligated gold clusters deposited onto self-assembled monolayer surfaces (SAMs). Product ions (Au10L42+, (10,4)2+, L = 1,3-bis(diphenyl-phosphino)propane, DPPP) were prepared through in-source collision induced dissociation (CID) and precursor ions [(8,4)2+, L = 1,6-bis(diphenylphosphino)hexane, DPPH] were synthesized in solution for comparison to (11,5)3+ precursor ions ligated with DPPP investigated previously (ACS Nano 2012, 6, 573 and J. Phys. Chem. C. 2012, 116, 24977). Similar to (11,5)3+ precursor ions, the (10,4)2+ product ions are shown to retain charge on 1H,1H,2H,2H-perfluorodecanethiol monolayers (FSAMs). Additional abundant peaks at higher m/z indicative of reactivity are observed in the TOF-SIMS spectrum of (10,4)2+ product ions that are not seen for (11,5)3+ precursor ions. The abundance of (10,4)2+ on 16-mercaptohexadecanoic acid (COOH-SAMs) is demonstrated to be lower than on FSAMs, consistent with partial reduction of charge. The (10,4)2+ product ion on 1-dodecanethiol (HSAMs) exhibits peaks similar to those seen on the COOH-SAM. On the HSAM, higher m/z peaks indicative of reactivity are observed similar to those on the FSAM. The (8,4)2+ DPPH precursor ions are shown to retain charge on FSAMs similar to (11,5)3+ precursor ions prepared with DPPP. An additional peak corresponding to attachment of one gold atom to (8,4)2+ is observed at higher m/z for DPPH-ligated clusters. On the COOH-SAM, (8,4)2+ is less abundant than on the FSAM consistent with partial neutralization. The results indicate that although retention of charge by product ions generated by CID is similar to precursor ions their reactivity during analysis with SIMS is different

  13. Gold nanoparticle-sensitized quartz crystal microbalance sensor for rapid and highly selective determination of Cu(II) ions.

    Science.gov (United States)

    Jin, Yulong; Huang, Yanyan; Liu, Guoquan; Zhao, Rui

    2013-09-21

    A novel quartz crystal microbalance (QCM) sensor for rapid, highly selective and sensitive detection of copper ions was developed. As a signal amplifier, gold nanoparticles (Au NPs) were self-assembled onto the surface of the sensor. A simple dip-and-dry method enabled the whole detection procedure to be accomplished within 20 min. High selectivity of the sensor towards copper ions is demonstrated by both individual and coexisting assays with interference ions. This gold nanoparticle mediated amplification allowed a detection limit down to 3.1 μM. Together with good repeatability and regeneration, the QCM sensor was also applied to the analysis of copper contamination in drinking water. This work provides a flexible method for fabricating QCM sensors for the analysis of important small molecules in environmental and biological samples. PMID:23888301

  14. The Effect of Multilayer Gold Nanoparticles on the Electrochemical Response of Ammonium Ion Biosensor Based on Alanine Dehydrogenase Enzyme

    Directory of Open Access Journals (Sweden)

    Tan Ling Ling

    2011-01-01

    Full Text Available The use of multilayer of gold nanoparticles (AuNPs attached on gold electrode surface via thiol chemistry to fabricate an ammonium (NH4+ ion biosensor based on alanine dehydrogenase (AlaDH was investigated. The approach of the study was based on construction of biosensor by direct deposition of AuNPs and 1,8-octanedithiol (C8-DT onto the gold electrode surface. For the immobilisation of enzyme, 2-mercaptoethanol (2BME was first covalently attached to AlaDH via esther bonding and then followed by chemically attached the 2BME-modified AlaDH (2BME-AlaDH moiety onto the AuNPs electrode via the exposed thiol group of 2BME. The resulting biosensor response was examined by means of amperometry for the quantification of NH4+ ion. In the absence of enzyme attachment, the use of three layers of AuNPs was found to improve the electrochemistry of the gold electrode when compared with no AuNPs was coated. However, when more than three layers of AuNPs were coated, the electrode response deteriorated due to excessive deposition of C8-DT. When AlaDH was incoporated into the AuNPs modified electrode, a linear response to NH4+ ion over the concentration range of 0.1–0.5 mM with a detection limit of 0.01 mM was obtained. In the absence of AuNPs, the NH4+ ion biosensor did not exhibit any good linear response range although the current response was observed to be higher. This work demonstrated that the incorporation of AuNPs could lead to the detection of higher NH4+ ion concentration without the need of dilution for high NH4+ ion concentration samples with a rapid response time of <1 min.

  15. Capillary electrophoretic study of thiolated alpha-cyclodextrin-capped gold nanoparticles with tetraalkylammonium ions.

    Science.gov (United States)

    Paau, Man Chin; Lo, Chung Keung; Yang, Xiupei; Choi, Martin M F

    2009-11-27

    Capillary zone electrophoresis (CZE) has been employed to characterize nanometer-sized thiolated alpha-cyclodextrin-capped gold nanoparticles (alpha-CD-S-AuNPs). The addition of tetrabutylammonium (Bu(4)N(+)) ions to the run buffer greatly narrows the migration peak of alpha-CD-S-AuNP. The optimal run buffer was determined to be 10mM Bu(4)N(+) in 30 mM phosphate buffer at pH 12 and an applied voltage of 15 kV. The effect of various tetraalkylammonium ions on the peak width and electrophoretic mobility (mu(e)) of alpha-CD-S-AuNP was studied in detail. Bu(4)N(+) ions assist in inter-linking the alpha-CD-S-AuNPs and narrowing the migration peak in CZE. This observation can be explained by the fact that each Bu(4)N(+) ion can simultaneously interact with several hydrophobic cavities of the surface-attached alpha-CDs on AuNPs. The TEM images show that alpha-CD-S-AuNPs with Bu(4)N(+) are linked together but in the absence of Bu(4)N(+), they are more dispersed. The migration mechanism in CZE is based on the formation of inclusion complexes between Bu(4)N(+) and alpha-CD-S-AuNPs which induces changes in the charge-to-size ratio of alpha-CD-S-AuNPs and mu(e). An inverse linear relationship (r(2)>0.998) exists between the mu(e) and size of alpha-CD-S-AuNPs in the core range 1.4-4.1 nm. The CZE analyses are rapid with migration time less than 4 min. A few nanoliters of each of the alpha-CD-S-AuNP samples were injected hydrodynamically at 0.5 psi for 5s. Our work confirms that CZE is an efficient tool for characterizing the sizes of alpha-CD-S-AuNPs using Bu(4)N(+) ions. PMID:19853853

  16. Simple optical determination of silver ion in aqueous solutions using benzo crown-ether modified gold nanoparticles

    International Nuclear Information System (INIS)

    We describe a method for the modification of gold nanoparticles (Au-NPs) with benzo-15-crown-5 that led to the development of a colorimetric assay for Ag(I) ion. The brown color of a solution of the modified Au-NPs turns to purple on addition of Ag(I) ion. The ratio of the UV-vis absorption at 600 nm and 525 nm is proportional to the concentration of Ag(I) ions in the range from 20 to 950 nM, and the detection limit is 12.5 nM. Other metal ions do not interfere if present in up to millimolar concentrations. The method enables a rapid determination of Ag(I) in lake and drinking water and is amenable to bare-eye readout. (author)

  17. Preconcentration of gold ions from water samples by modified organo-nanoclay sorbent prior to flame atomic absorption spectrometry determination

    Energy Technology Data Exchange (ETDEWEB)

    Afzali, Daryoush, E-mail: daryoush_afzali@yahoo.com [Nanochemistry Department, Research Institute of Environmental Sciences, International Center for Science, High Technology and Environmental Sciences, Kerman (Iran, Islamic Republic of); Mostafavi, Ali [Chemistry Department, Shahid Bahonar University of Kerman, Kerman (Iran, Islamic Republic of); Mirzaei, Mohammad [Nanochemistry Department, Research Institute of Environmental Sciences, International Center for Science, High Technology and Environmental Sciences, Kerman (Iran, Islamic Republic of); Chemistry Department, Shahid Bahonar University of Kerman, Kerman (Iran, Islamic Republic of)

    2010-09-15

    In this work, the applicability of modified organo nanoclay as a new and easy prepared solid sorbent for the preconcentration of trace amounts of Au(III) ion from water samples is studied. The organo nanoclay was modified with 5-(4'-dimethylamino benzyliden)-rhodanine and used as a sorbent for separation of Au(III) ions. The sorption of gold ions was quantitative in the pH range of 2.0-6.0. Quantitative desorption occurred with 6.0 mL of 1.0 mol L{sup -1} Na{sub 2}S{sub 2}O{sub 3}. The amount of eluted Au(III) was measured using flame atomic absorption spectrometry. In the initial solution the linear dynamic range was in the range of 0.45 ng mL{sup -1} to 10.0 {mu}g mL{sup -1}, the detection limit was 0.1 ng mL{sup -1} and the preconcentration factor was 105. Also, the relative standard deviation was {+-}2.3% (n = 8 and C = 2.0 {mu}g mL{sup -1}) and the maximum capacity of the sorbent was 3.9 mg of Au(III) per gram of modified organo nanoclay. The influences of the experimental parameters including sample pH, eluent volume and eluent type, sample volume, and interference of some ions on the recoveries of the gold ion were investigated. The proposed method was applied for preconcentration and determination of gold in different samples.

  18. Selective Aerobic Oxidation of Benzyl Alcohol Driven by Visible Light on Gold Nanoparticles Supported on Hydrotalcite Modified by Nickel Ion

    Directory of Open Access Journals (Sweden)

    Dapeng Guo

    2016-04-01

    Full Text Available A series of hydrotalcite (HT and hydrotalcite modified by the transition metal ion Ni(II was prepared with a modified coprecipitation method before being loaded with gold nanoparticles. The gold supported on Ni3Al hydrotalcite with a Ni2+/Al3+ molar ratio of 3:1 was investigated. Different techniques such as X-ray diffraction (XRD, X-ray photoelectron spectroscopy (XPS and UV-vis diffuse reflection spectrum (UV-vis DRS were applied to characterize the catalysts. A single-phase catalyst with high crystallinity, a layered structure and good composition was successfully fabricated. Good conversions and superior selectivities in the oxidation of benzyl alcohol and its derivatives were obtained with visible light due to the effect of localized surface plasmon resonance (LSPR of gold nanoparticles and the synergy of the transition metal ion Ni(II. This reaction was proven to be photocatalytic by varying the intensity and wavelength of the visible light. The catalyst can be recycled three times. A corresponding photocatalytic mechanism of the oxidation reaction of benzyl alcohol was proposed.

  19. Flame Atomic Absorption Determination of Gold Ion in Aqueous Samples after Preconcentration Using 9-Acridinylamine Functionalized γ-Alumina Nanoparticles

    Directory of Open Access Journals (Sweden)

    Mohammad Karimi

    2013-01-01

    Full Text Available A simple and sensitive solid phase extraction utilizing 9-acridinylamine functionalized alumina nanoparticles was developed, and their potential use for preconcentration and subsequent determination of gold by flame atomic absorption spectrometry (FAAS was investigated. A number of parameters, namely, type, concentration, and volume of eluent, pH of the sample solution, flow rate of extraction, and volume of the sample, were evaluated. The effect of a variety of ions on preconcentration and recovery was also investigated. Gold ions were found to be recovered quantitatively at pH 3.0, with 0.1 mol L−1 thiourea in 2 mol L−1 H2SO4 as eluent. The limit of detection (LOD, defined as five times the standard deviation of the blank, was determined to be lower than 13.0 ppb. Under optimum conditions, the accuracy and precision (RSD% of the method were >98.0 and <1.5%, respectively. To gauge its ability in terms of application to real samples, the proposed method was successfully applied for determination of gold concentration in waste water samples and one soil standard material, and satisfactory results were obtained.

  20. Ultrahigh capacity anode material for lithium ion battery based on rod gold nanoparticles decorated reduced graphene oxide

    Energy Technology Data Exchange (ETDEWEB)

    Atar, Necip, E-mail: necipatar@gmail.com [Department of Chemical Engineering, Pamukkale University, Denizli (Turkey); Eren, Tanju [Department of Chemical Engineering, Pamukkale University, Denizli (Turkey); Yola, Mehmet Lütfi [Department of Metallurgical and Materials Engineering, Sinop University, Sinop (Turkey)

    2015-09-01

    In this study, we report the synthesis of rod shaped gold nanoparticles/2-aminoethanethiol functionalized reduced graphene oxide composite (rdAuNPs/AETrGO) and its application as an anode material for lithium-ion batteries. The structure of the rdAuNPs/AETrGO composite was characterized by scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy and X-ray diffraction. The electrochemical performance was investigated at different current rates by using a coin-type cell. It was found that the rod shaped gold nanoparticles were highly dispersed on the reduced graphene oxide sheets. Moreover, the rdAuNPs/AETrGO composite showed a high specific gravimetric capacity of about 1320 mAh g{sup −1} and a long-term cycle stability. - Highlights: • We prepared rod shaped gold nanoparticles functionalized reduced graphene oxide. • The nanocomposite was used as an anode material for lithium-ion batteries. • The nanocomposite showed a high specific gravimetric capacity of about 1320 mAh g{sup −1}. • The nanocomposite exhibited a long-term cycle stability.

  1. Ultrahigh capacity anode material for lithium ion battery based on rod gold nanoparticles decorated reduced graphene oxide

    International Nuclear Information System (INIS)

    In this study, we report the synthesis of rod shaped gold nanoparticles/2-aminoethanethiol functionalized reduced graphene oxide composite (rdAuNPs/AETrGO) and its application as an anode material for lithium-ion batteries. The structure of the rdAuNPs/AETrGO composite was characterized by scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy and X-ray diffraction. The electrochemical performance was investigated at different current rates by using a coin-type cell. It was found that the rod shaped gold nanoparticles were highly dispersed on the reduced graphene oxide sheets. Moreover, the rdAuNPs/AETrGO composite showed a high specific gravimetric capacity of about 1320 mAh g−1 and a long-term cycle stability. - Highlights: • We prepared rod shaped gold nanoparticles functionalized reduced graphene oxide. • The nanocomposite was used as an anode material for lithium-ion batteries. • The nanocomposite showed a high specific gravimetric capacity of about 1320 mAh g−1. • The nanocomposite exhibited a long-term cycle stability

  2. A colorimetric method for the determination of lead(II) ions using gold nanoparticles and a guanine-rich oligonucleotide

    International Nuclear Information System (INIS)

    We have developed a colorimetric method for the determination of Pb(II) ions. It is based on the use of gold nanoparticles and a guanine-rich synthetic oligonucleotide. On addition of Pb(II), the color of the solution turns from red to blue. The ratio of the UV-vis absorption at 630 nm and 525 nm is proportional to the concentration of Pb(II) ions in the range from 10 to 100 nM, and the detection limit is 20 nM. Other metal ions do not interfere if present in up to a 10-fold molar excess. The method was successfully applied to the detection of Pb(II) in lake water and urine. The recovery in case of spiked samples is 92%. The results show that this method is sensitive, simple and fast. (author)

  3. Colorimetric sensor array based on gold nanoparticles and amino acids for identification of toxic metal ions in water.

    Science.gov (United States)

    Sener, Gulsu; Uzun, Lokman; Denizli, Adil

    2014-01-01

    A facile colorimetric sensor array for detection of multiple toxic heavy metal ions (Hg(2+), Cd(2+), Fe(3+), Pb(2+), Al(3+), Cu(2+), and Cr(3+)) in water is demonstrated using 11-mercaptoundecanoic acid (MUA)-capped gold nanoparticles (AuNPs) and five amino acids (lysine, cysteine, histidine, tyrosine, and arginine). The presence of amino acids (which have functional groups that can form complexes with metal ions and MUA) regulates the aggregation of MUA-capped particles; it can either enhance or diminish the particle aggregation. The combinatorial colorimetric response of all channels of the sensor array (i.e., color change in each of AuNP and amino acid couples) enables naked-eye discrimination of all of the metal ions tested in this study with excellent selectivity. PMID:25330256

  4. Precise determination of the 1s Lamb Shift in hydrogen-like lead and gold ions using microcalorimeters

    CERN Document Server

    Kraft-Bermuth, S; Bleile, A; Echler, A; Egelhof, P; Grabitz, P; Ilieva, S; Kiselev, O; Kilbourne, C; McCammon, D; Meier, J P; Scholz, P

    2016-01-01

    Quantum electrodynamics in very strong Coulomb fields is one scope which has not yet been tested experimentally with suffcient accuracy to really determine whether the perturbative approach is valid. One sensitive test is the determination of the 1s Lamb Shift in highly-charged very heavy ions. The 1s Lamb Shift of hydrogen-like lead (Pb81+) and gold (Au78+) has been determined using the novel detector concept of silicon microcalorimeters for the detection of hard X-rays. The results of (260 +- 22) eV for lead and (208 +- 13) eV for gold are within error bars in good agreement with theoretical predictions. For hydrogen-like lead, this represents the most accurate determination of the 1s Lamb Shift to our knowledge.

  5. Measurement of fragmentation cross sections of 12C ions on a thin gold target with the FIRST apparatus

    Science.gov (United States)

    Toppi, M.; Abou-Haidar, Z.; Agodi, C.; Alvarez, M. A. G.; Aumann, T.; Balestra, F.; Battistoni, G.; Bocci, A.; Böhlen, T. T.; Boudard, A.; Brunetti, A.; Carpinelli, M.; Cirio, R.; Cirrone, G. A. P.; Cortes-Giraldo, M. A.; Cuttone, G.; de Napoli, M.; Durante, M.; Fernández-García, J. P.; Finck, Ch.; Golosio, B.; Iarocci, E.; Iazzi, F.; Ickert, G.; Introzzi, R.; Juliani, D.; Krimmer, J.; Kummali, A. H.; Kurz, N.; Labalme, M.; Leifels, Y.; Le Fèvre, A.; Leray, S.; Marchetto, F.; Monaco, V.; Morone, M. C.; Nicolosi, D.; Oliva, P.; Paoloni, A.; Piersanti, L.; Pleskac, R.; Randazzo, N.; Rescigno, R.; Romano, F.; Rossi, D.; Rosso, V.; Rousseau, M.; Sacchi, R.; Sala, P.; Salvador, S.; Sarti, A.; Scheidenberger, C.; Schuy, C.; Sciubba, A.; Sfienti, C.; Simon, H.; Sipala, V.; Spiriti, E.; Tropea, S.; Vanstalle, M.; Younis, H.; Patera, V.; FIRST Collaboration

    2016-06-01

    A detailed knowledge of the light ions interaction processes with matter is of great interest in basic and applied physics. As an example, particle therapy and space radioprotection require highly accurate fragmentation cross-section measurements to develop shielding materials and estimate acute and late health risks for manned missions in space and for treatment planning in particle therapy. The Fragmentation of Ions Relevant for Space and Therapy experiment at the Helmholtz Center for Heavy Ion research (GSI) was designed and built by an international collaboration from France, Germany, Italy, and Spain for studying the collisions of a 12C ion beam with thin targets. The collaboration's main purpose is to provide the double-differential cross-section measurement of carbon-ion fragmentation at energies that are relevant for both tumor therapy and space radiation protection applications. Fragmentation cross sections of light ions impinging on a wide range of thin targets are also essential to validate the nuclear models implemented in MC simulations that, in such an energy range, fail to reproduce the data with the required accuracy. This paper presents the single differential carbon-ion fragmentation cross sections on a thin gold target, measured as a function of the fragment angle and kinetic energy in the forward angular region (θ ≲6° ), aiming to provide useful data for the benchmarking of the simulation softwares used in light ions fragmentation applications. The 12C ions used in the measurement were accelerated at the energy of 400 MeV/nucleon by the SIS (heavy ion synchrotron) GSI facility.

  6. 'In-situ' observation of halide ion adsorption on a gold electrode using synchrotron far infrared spectroscopy

    International Nuclear Information System (INIS)

    The adsorption of chloride and bromide ions on a gold electrode in the double layer region in 0.5 M perchloric acid solution was observed 'in-situ' for the first time using the technique of synchrotron far infrared reflectance spectroscopy (SFIRS). The Au-Cl surface vibrational frequency was measured to be about 263 cm-1 in chloride concentrations from 0.005 to 0.05 M. The Au-Br stretching mode was observed at 182 cm-1. The SFIRS technique is a promising tool for the investigation of interfacial electrochemical structures and processes with monolayer sensitivity

  7. Derivation of guideline values for gold (III) ion toxicity limits to protect aquatic ecosystems.

    Science.gov (United States)

    Nam, Sun-Hwa; Lee, Woo-Mi; Shin, Yu-Jin; Yoon, Sung-Ji; Kim, Shin Woong; Kwak, Jin Il; An, Youn-Joo

    2014-01-01

    This study focused on estimating the toxicity values of various aquatic organisms exposed to gold (III) ion (Au(3+)), and to propose maximum guideline values for Au(3+) toxicity that protect the aquatic ecosystem. A comparative assessment of methods developed in Australia and New Zealand versus the European Community (EC) was conducted. The test species used in this study included two bacteria (Escherichia coli and Bacillus subtilis), one alga (Pseudokirchneriella subcapitata), one euglena (Euglena gracilis), three cladocerans (Daphnia magna, Moina macrocopa, and Simocephalus mixtus), and two fish (Danio rerio and Oryzias latipes). Au(3+) induced growth inhibition, mortality, immobilization, and/or developmental malformations in all test species, with responses being concentration-dependent. According to the moderate reliability method of Australia and New Zealand, 0.006 and 0.075 mg/L of guideline values for Au(3+) were obtained by dividing 0.33 and 4.46 mg/L of HC5 and HC50 species sensitivity distributions (SSD) with an FACR (Final Acute to Chronic Ratio) of 59.09. In contrast, the EC method uses an assessment factor (AF), with the 0.0006 mg/L guideline value for Au(3+) being divided with the 48-h EC50 value for 0.60 mg/L (the lowest toxicity value obtained from short term results) by an AF of 1000. The Au(3+) guideline value derived using an AF was more stringent than the SSD. We recommend that more toxicity data using various bioassays are required to develop more accurate ecological risk assessments. More chronic/long-term exposure studies on sensitive endpoints using additional fish species and invertebrates not included in the current dataset will be needed to use other derivation methods (e.g., US EPA and Canadian Type A) or the "High Reliability Method" from Australia/New Zealand. Such research would facilitate the establishment of guideline values for various pollutants that reflect the universal effects of various pollutants in aquatic ecosystems. To

  8. Sensitive DNA-hybridization biosensors based on gold nanoparticles for testing DNA damage by Cd(II) ions

    International Nuclear Information System (INIS)

    A DNA biosensor was constructed by immobilizing a 20-mer oligonucleotide probe and hybridizing it with its complementary oligomer on the surface of a glassy carbon electrode modified with gold nanoparticles. The properties of the biosensor and its capability of recognizing its complementary sequence were studied by electrochemical impedance spectroscopy. The oxidative stress caused by cadmium ions can be monitored by differential pulse voltammetry using the cobalt(III)tris(1,10-phenanthroline) complex and methylene blue as electrochemical indicators. The biosensor is capable of indicating damage caused by Cd(II) ions in pH 6.0 solution. The results showed that the biosensor can be used for rapid screening for DNA damage. (author)

  9. Chitosan-functionalized gold nanoparticles for colorimetric detection of mercury ions based on chelation-induced aggregation

    International Nuclear Information System (INIS)

    We are presenting a colorimetric assay for mercury (II) ions. It is based on citosan-functionalized gold nanoparticles (AuNPs) that act as a signaling probe. Hg (II) induces the aggregation of the chitosan-AuNPs through a chelation reaction that occurs between chitosan and Hg (II). This results in a strong decrease of the absorbance of the modified AuNPs and a color change from red to blue. This sensing system displays excellent selectivity over other metal ions and a detection limit as low as 1.35 μM which is lower than the allowed level of Hg (II) in drinking water (30 μM) as defined by World Health Organization. The method is inexpensive, facile, sensitive, and does not require the addition of other reagents in order to improving sensitivity. (author)

  10. Glassy carbon electrode modified by graphene–gold nanocomposite coating for detection of trace lead ions in acetate buffer solution

    International Nuclear Information System (INIS)

    Reduced graphene oxide (RGO) decorated with gold nanoparticles (AuNPs) was electrodeposited on glassy carbon electrode (GCE) using cyclic voltammetric method. The results of Raman spectroscopy confirmed the simultaneous formation of AuNPs and reduction of graphene oxide through the electrodeposition process. Scanning electron microscopic measurements showed a uniform distribution of the AuNPs on the RGO sheets. The RGO-AuNP nanocomposite coated GCE (G–Au/GCE) was used to detect lead ions (Pb2+) contained in a 0.1 M acetate buffer solution (pH 5.3) using square wave anodic stripping voltammetry (SWASV). The G–Au/GCE demonstrated higher detection sensitivity and stronger SWASV signals than the bare GCE, with the limit of detection of about 0.8 nM. - Highlights: • Graphene with gold nanoparticles was electrodeposited on glassy carbon electrode. • The prepared electrode was able to detect trace lead ions at nM concentration. • Interference study against copper confirmed the selectivity of the electrode for lead. • The prepared electrode showed a promising recovery tested in tap water samples

  11. Glassy carbon electrode modified by graphene–gold nanocomposite coating for detection of trace lead ions in acetate buffer solution

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Pui Mun [Interdisplinary Graduate School, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798 (Singapore); Environmental Chemistry and Materials Group (ECMG), Nanyang Environment and Water Research Institute (NEWRI), Nanyang Technological University, 1 Cleantech Loop, Singapore 637141 (Singapore); School of Materials Science and Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798 (Singapore); School of Mechanical and Aerospace Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798 (Singapore); Wang, Zhaomeng [School of Materials Science and Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798 (Singapore); Liu, Xiaoxu [Heilongjiang University of Science and Technology, Harbin 150027 (China); Chen, Zhong [School of Materials Science and Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798 (Singapore); Liu, Erjia, E-mail: MEJLiu@ntu.edu.sg [School of Mechanical and Aerospace Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798 (Singapore)

    2015-06-01

    Reduced graphene oxide (RGO) decorated with gold nanoparticles (AuNPs) was electrodeposited on glassy carbon electrode (GCE) using cyclic voltammetric method. The results of Raman spectroscopy confirmed the simultaneous formation of AuNPs and reduction of graphene oxide through the electrodeposition process. Scanning electron microscopic measurements showed a uniform distribution of the AuNPs on the RGO sheets. The RGO-AuNP nanocomposite coated GCE (G–Au/GCE) was used to detect lead ions (Pb{sup 2+}) contained in a 0.1 M acetate buffer solution (pH 5.3) using square wave anodic stripping voltammetry (SWASV). The G–Au/GCE demonstrated higher detection sensitivity and stronger SWASV signals than the bare GCE, with the limit of detection of about 0.8 nM. - Highlights: • Graphene with gold nanoparticles was electrodeposited on glassy carbon electrode. • The prepared electrode was able to detect trace lead ions at nM concentration. • Interference study against copper confirmed the selectivity of the electrode for lead. • The prepared electrode showed a promising recovery tested in tap water samples.

  12. Formation and bio release of bound residues of [14 C]-lindane and [14 C]-parathion in two Brazilian soils

    International Nuclear Information System (INIS)

    This work studied the extractable and bound residues formation of 14 C-lindane and 14 C-parathion immediately after application and after 3 months of interaction of the pesticides with the soils. Metabolism, bio release, and the possible bioavailability of bound residues were studied by employing bio meter flasks which allowed a relative comparison of the behaviour of the two different 14 C-pesticides, by a balance of the applied or present radiocarbon in the soils after the bio tests. (author)

  13. Visual and colorimetric detection of mercury(II) ion using gold nanoparticles stabilized with a dithia-diaza ligand

    International Nuclear Information System (INIS)

    We have developed a simple method for the highly selective colorimetric detection of dissolved mercury(II) ions via direct formation of gold nanoparticles (AuNPs). The dithia-diaza ligand 2-[3-(2-amino-ethylsulfanyl)-propylsulfanyl]-ethylamine (AEPE) was used as a stabilizer to protect AuNPs from aggregation and to impart highly selective recognition of Hg(II) ion over other metal ions. A solution of Au(III) ion is directly reduced by sodium borohydride in the presence of AEPE and the detergent Triton X-100. This results in the formation of AEPE-AuNPs and a red coloration of the solution. On the other hand, in the presence of Hg(II), the solution turns blue within a few seconds after the addition of borohydride. This can be detected spectrophotometrically or even visually. The method was successfully applied to quantify Hg(II) levels in water sample, with a minimum detectable concentration as low as 35 nM. (author)

  14. Synthesis of nanocrystalline thin films of gold on the surface of GaSb by swift heavy ion

    Energy Technology Data Exchange (ETDEWEB)

    Jadhav, Vidya; Dubey, S. K.; Yadav, A. D.; Singh, A. [Department of Physics, University of Mumbai, Santacruz (E), Mumbai-400 098 (India)

    2013-02-05

    Thin films of gold ({approx}100 nm thick) were deposited on p-type GaSb substrates. These samples were irradiated with 100 MeV Fe{sup 7+}ions for the fluence of 1 Multiplication-Sign 10{sup 13} and 1 Multiplication-Sign 10{sup 14} ions cm{sup -2}. After irradiation, samples were characterized using AFM, UV-VIS -NIR, X-Ray Diffraction techniques. AFM studies showed the presence of clusters on the surface of GaSb. R.M.S. roughness of the sample was found to increase w.r.t ion fluence. Absorption coefficient obtained from the Ultra violet - Visible NIR (UV-VIS -NIR) spectra of the samples irradiated with various fluences compared with non irradiated GaSb. The annealing experiment showed a significant improvement in the absorption coefficient after rapid thermal annealing at temperature of 400 Degree-Sign C. X-Ray Diffraction study reveals different orientations of Au film.

  15. Combining Zn Ion Catalysis with Homogeneous Gold Catalysis: An Efficient Annulation Approach to N-Protected Indoles.

    Science.gov (United States)

    Wang, Yanzhao; Liu, Lianzhu; Zhang, Liming

    2013-02-01

    The Fischer indole synthesis is perhaps the most powerful method for indole preparation, but it often suffers from low regioselectivities with unsymmetric aliphatic ketone substrates and strong acidic conditions and is not suitable for α,β-unsaturated ketones. In this article, we disclose an efficient synthesis of N-protected indoles from N-arylhydroxamic acids/N-aryl-N-hydroxycarbamates and a variety of alkynes via a cooperative gold and zinc catalysis. The zinc catalysis is similar to the related zinc ion catalysis in metalloenzymes such as human carbonic anhydrase II and substantially enhances the O-nucleophilicity of N-acylated hydroxamines by forming the corresponding Zn chelates. The Zn chelates can attack gold-activated alkynes to form O-alkenyl-N-arylhydroxamates, which can undergo facile 3,3-sigmatropic rearrangements and subsequent cyclodehydrations to yield N-protected indole products. This new chemistry offers several important improvements over the Fischer indole synthesis: a) the reaction conditions are mildly acidic and can tolerate sensitive groups such as Boc; b) broader substrate scopes including substrates with pendant carbonyl groups (reactive in the Fischer chemistry) and alkyl chlorides (e.g., 3f); c) better regioselectivities for the formation of 2-substituted indoles under much milder conditions; d) 2-alkenylindoles can be prepared readily in good to excellent yields, but the Fischer chemistry could not; e) with internal alkynes both steric and electronic controls are available for achieving good regioselectivities, while the Fischer chemistry is in general problematic.

  16. The Radiation Enhancement of 15 nm Citrate-Capped Gold Nanoparticles Exposed to 70 keV/μm Carbon Ions.

    Science.gov (United States)

    Liu, Yan; Liu, Xi; Jin, Xiaodong; He, Pengbo; Zheng, Xiaogang; Ye, Fei; Chen, Weiqiang; Li, Qiang

    2016-03-01

    Radiotherapy is an important modality for tumor treatment. The central goal of radiotherapy is to deliver a therapeutic dose to the tumor as much as possible whilst sparing the surrounding normal tissues. On one hand, heavy ion radiation induces maximum damage at the end of the track (called the Bragg Peak). Hadron therapy based on heavy ions is considered superior to conventional X-rays and γ-rays radiations for tumors sited in sensitive tissues, childhood cases and radioresistant cancers. On the other hand, radiation sensitizers enhanced the radiation effects in tumors by increasing the dose specifically to the tumor cells. Recently, the use of gold nanoparticles as potential tumor selective radio-sensitizers has been proposed as a breakthrough in radiotherapy with conventional radiations. The enhanced radiation effect of heavy ions in tumor by using gold nanoparticles as radio-sensitizer may provide alternative in hadron therapy. In this study, we investigated the radiosensitizing effects of carbon ions with a linear energy transfer of 70 keV/μm in the presence of 15 nm citrate-capped AuNPs. The existing of AuNPs resulted in 5.5-fold enhancement in hydroxyl radical production and 24.5% increment in relative biological effectiveness (RBE) values for carbon-ion-irradiated HeLa cells. The study indicated gold nanoparticles can be used as potential radio-sensitizer in carbon ions therapy. PMID:27455642

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

    Science.gov (United States)

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

    2014-01-31

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

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

    International Nuclear Information System (INIS)

    Graphical abstract: -- Highlights: •We report a new electrochemical sensing protocol for the detection of mercury ion. •Gold amalgamation on DNA-based sensing platform was used as nanocatalyst. •The signal was amplified by cycling signal amplification strategy. -- Abstract: Heavy metal ion pollution poses severe risks in human health and environmental pollutant, because of the likelihood of bioaccumulation and toxicity. Driven by the requirement to monitor trace-level mercury ion (Hg2+), herein we construct a new DNA-based sensor for sensitive electrochemical monitoring of Hg2+ by coupling target-induced formation of gold amalgamation on DNA-based sensing platform with gold amalgamation-catalyzed cycling signal amplification strategy. The sensor was simply prepared by covalent conjugation of aminated poly-T(25) oligonucleotide onto the glassy carbon electrode by typical carbodiimide coupling. Upon introduction of target analyte, Hg2+ ion was intercalated into the DNA polyion complex membrane based on T–Hg2+–T coordination chemistry. The chelated Hg2+ ion could induce the formation of gold amalgamation, which could catalyze the p-nitrophenol with the aid of NaBH4 and Ru(NH3)63+ for cycling signal amplification. Experimental results indicated that the electronic signal of our system increased with the increasing Hg2+ level in the sample, and has a detection limit of 0.02 nM with a dynamic range of up to 1000 nM Hg2+. The strategy afforded exquisite selectivity for Hg2+ against other environmentally related metal ions. In addition, the methodology was evaluated for the analysis of Hg2+ in spiked tap-water samples, and the recovery was 87.9–113.8%

  19. Determining the size-dependent structure of ligand-free gold-cluster ions.

    Science.gov (United States)

    Schooss, Detlef; Weis, Patrick; Hampe, Oliver; Kappes, Manfred M

    2010-03-28

    Ligand-free metal clusters can be prepared over a wide size range, but only in comparatively small amounts. Determining their size-dependent properties has therefore required the development of experimental methods that allow characterization of sample sizes comprising only a few thousand mass-selected particles under well-defined collision-free conditions. In this review, we describe the application of these methods to the geometric structural determination of Au(n)(+) and Au(n)(-) with n = 3-20. Geometries were assigned by comparing experimental data, primarily from ion-mobility spectrometry and trapped ion electron diffraction, to structural models from quantum chemical calculations.

  20. Microwave-assisted synthesis of BSA-protected small gold nanoclusters and their fluorescence-enhanced sensing of silver(i) ions

    Science.gov (United States)

    Yue, Yuan; Liu, Tian-Ying; Li, Hong-Wei; Liu, Zhongying; Wu, Yuqing

    2012-03-01

    A one-step microwave-assisted method is used for the synthesis of small gold nanoclusters, Au16NCs@BSA, which are used as a fluorescence enhanced sensor for detection of silver(i) ions with high selectivity and sensitivity.A one-step microwave-assisted method is used for the synthesis of small gold nanoclusters, Au16NCs@BSA, which are used as a fluorescence enhanced sensor for detection of silver(i) ions with high selectivity and sensitivity. Electronic supplementary information (ESI) available: Experimental details of the synthesis of AuNCs@BSA and fluorescent detection, and Fig. S1-S10. See DOI: 10.1039/c2nr12056a

  1. Development of an Ionization Scheme for Gold using the Selective Laser Ion Source at the On-Line Isotope Separator ISOLDE

    CERN Document Server

    Fedosseev, V; Marsh, B A; CERN. Geneva. AB Department

    2006-01-01

    At the ISOLDE on-line isotope separation facility, the resonance ionization laser ion source (RILIS) can be used to ionize reaction products as they effuse from the target. The RILIS process of laser step-wise resonance ionization of atoms in a hot metal cavity provides a highly element selective stage in the preparation of the radioactive ion beam. As a result, the ISOLDE mass separators can provide beams of a chosen isotope with greatly reduced isobaric contamination. The number of elements available at RILIS has been extended to 26, with the addition of a new three-step ionization scheme for gold. The optimal ionization scheme was determined during an extensive study of the atomic energy levels and auto-ionizing states of gold, carried out by means of in-source resonance ionization spectroscopy. Details of the ionization scheme and a summary of the spectroscopy study are presented.

  2. Investigation of argon ion sputtering on the secondary electron emission from gold samples

    Science.gov (United States)

    Yang, Jing; Cui, Wanzhao; Li, Yun; Xie, Guibai; Zhang, Na; Wang, Rui; Hu, Tiancun; Zhang, Hongtai

    2016-09-01

    Secondary electron (SE) yield, δ, is a very sensitive surface property. The values of δ often are not consistent for even identical materials. The influence of surface changes on the SE yield was investigated experimentally in this article. Argon ion sputtering was used to remove the contamination from the surface. Surface composition was monitored by X-ray photoelectron spectroscopy (XPS) and surface topography was scanned by scanning electron microscope (SEM) and atomic force microscope (AFM) before and after every sputtering. It was found that argon sputtering can remove contamination and roughen the surface. An "equivalent work function" is presented in this thesis to establish the relationship between SE yield and surface properties. Argon ion sputtering of 1.5keV leads to a significant increase of so called "work function" (from 3.7 eV to 6.0 eV), and a decrease of SE yield (from 2.01 to 1.54). These results provided a new insight into the influence of surface changes on the SE emission.

  3. 基于电位控制的分金液亚硫酸钠深度还原试验研究%Research on Deep Reduction of Gold Ion in Liquid by Controlling of Redox Potential

    Institute of Scientific and Technical Information of China (English)

    聂华平; 王莉红; 张忠堂; 吴芳芳

    2015-01-01

    T he gold ion in liquid is reduced using sodium sulphite as reductant .T he relation betw een liquid redox potential and gold ion concentration and gold ion reduction rate based on gold ion concentration were determined .Theoretically ,it can be determined when the redox potential drops below to 585 mV ,the reduction rate of gold ion can reach 99% ,and w hen the redox potential is about 505 mV ,the reduction reaction of gold ion will end .%研究了用还原剂亚硫酸钠还原分金液中的金离子,确定了电位与金离子质量浓度及金还原率之间的关系。结果表明:电位降到585 m V以下时,金还原率可达99%;电位约为505 m V时,还原反应结束。

  4. Photoionization cross sections and radiative recombination rate coefficients for positive ions of carbon and gold

    Energy Technology Data Exchange (ETDEWEB)

    Barfield, W.D.

    1977-09-01

    Partial photoionization cross sections based on a nonhydrogenic single-electron model that utilizes Dirac--Slater wave functions and all necessary multipoles have been computed for C III-VI and Au + 8, +16, +24, and +36 for n = 1 - 6 and 10, 0 less than or equal to l < n. By use of detailed balance, radiative recombination rate coefficients are obtained for seven temperatures in the range 10 eV - 3 keV from the photoionization cross sections. The cross sections are compared with those obtained by others using semiclassical (Kramers) and hydrogenic models. In most cases, the recombination rate coefficients (summed over subshells) are larger than those computed using hydrogenic photoionization cross sections, by as much as a factor 30 (Au + 8, n = 5, kT = 43 keV). Analytical fits are given for the rate coefficients summed over l and n. The results are applicable to ionization balance and ion transport calculations for fusion reactors and the solar corona.

  5. Ion mobility based on column leaching of South African gold tailings dam with chemometric evaluation.

    Science.gov (United States)

    Cukrowska, Ewa M; Govender, Koovila; Viljoen, Morris

    2004-07-01

    New column leaching experiments were designed and used as an alternative rapid screening approach to element mobility assessment. In these experiments, field-moist material was treated with an extracting solution to assess the effects of acidification on element mobility in mine tailings. The main advantage of this version of column leaching experiments with partitioned segments is that they give quick information on current element mobility in conditions closely simulating field conditions to compare with common unrepresentative air-dried, sieved samples used for column leaching experiments. Layers from the tailings dump material were sampled and packed into columns. The design of columns allows extracting leachates from each layer. The extracting solutions used were natural (pH 6.8) and acidified (pH 4.2) rainwater. Metals and anions were determined in the leachates. The concentrations of metals (Ca, Mg, Fe, Mn, Al, Cr, Ni, Co, Zn, and Cu) in sample leachates were determined using ICP OES. The most important anions (NO3-, Cl-, and SO4(2)-) were determined using the closed system izotacophoresis ITP analyser. The chemical analytical data from tailings leaching and physico-chemical data from field measurements (including pH, conductivity, redox potential, temperature) were used for chemometric evaluation of element mobility. Principal factor analysis (PFA) was used to evaluate ions mobility from different layers of tailings dump arising from varied pH and redox conditions. It was found that the results from the partitioned column leaching illustrate much better complex processes of metals mobility from tailings dump than the total column. The chemometric data analysis (PFA) proofed the differences in the various layers leachability that are arising from physico-chemical processes due to chemical composition of tailings dump deposit. PMID:15109878

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

    Science.gov (United States)

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

    2012-10-01

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

  7. Highly Sensitive Aluminium(III) Ion Sensor Based on a Self-assembled Monolayer on a Gold Nanoparticles Modified Screen-printed Carbon Electrode.

    Science.gov (United States)

    See, Wong Pooi; Heng, Lee Yook; Nathan, Sheila

    2015-01-01

    A new approach for the development of a highly sensitive aluminium(III) ion sensor via the preconcentration of aluminium(III) ion with a self-assembled monolayer on a gold nanoparticles modified screen-printed carbon electrode and current mediation by potassium ferricyanide redox behavior during aluminium(III) ion binding has been attempted. A monolayer of mercaptosuccinic acid served as an effective complexation ligand for the preconcentration of trace aluminium; this led to an enhancement of aluminium(III) ion capture and thus improved the sensitivity of the sensor with a detection limit of down to the ppb level. Under the optimum experimental conditions, the sensor exhibited a wide linear dynamic range from 0.041 to 12.4 μM. The lower detection limit of the developed sensor was 0.037 μM (8.90 ppb) using a 10 min preconcentration time. The sensor showed excellent selectivity towards aluminium(III) ion over other interference ions.

  8. Gold carbenes, gold-stabilized carbocations, and cationic intermediates relevant to gold-catalysed enyne cycloaddition.

    Science.gov (United States)

    Harris, R J; Widenhoefer, R A

    2016-08-21

    Cationic gold complexes in which gold is bound to a formally divalent carbon atom, typically formulated as gold carbenes or α-metallocarbenium ions, have been widely invoked in a range of gold-catalyzed transformations, most notably in the gold-catalyzed cycloisomerization of 1,n-enynes. Although the existence of gold carbene complexes as intermediates in gold-catalyzed transformations is supported by a wealth of indirect experimental data and by computation, until recently no examples of cationic gold carbenes/α-metallocarbenium ions had been synthesized nor had any cationic intermediates generated via gold-catalyzed enyne cycloaddition been directly observed. Largely for this reason, there has been considerable debate regarding the electronic structure of these cationic complexes, in particular the relative contributions of the carbene (LAu(+)[double bond, length as m-dash]CR2) and α-metallocarbenium (LAu-CR2(+)) forms, which is intimately related to the extent of d → p backbonding from gold to the C1 carbon atom. However, over the past ∼ seven years, a number of cationic gold carbene complexes have been synthesized in solution and generated in the gas phase and cationic intermediates have been directly observed in the gold-catalyzed cycloaddition of enynes. Together, these advances provide insight into the nature and electronic structure of gold carbene/α-metallocarbenium complexes and the cationic intermediates generated via gold-catalyzed enyne cycloaddition. Herein we review recent advances in this area. PMID:27146712

  9. In vitro studies on radiosensitization effect of glucose capped gold nanoparticles in photon and ion irradiation of HeLa cells

    Science.gov (United States)

    Kaur, Harminder; Pujari, Geetanjali; Semwal, Manoj K.; Sarma, Asitikantha; Avasthi, Devesh Kumar

    2013-04-01

    Noble metal nanoparticles are of great interest due to their potential applications in diagnostics and therapeutics. In the present work, we synthesized glucose capped gold nanoparticle (Glu-AuNP) for internalization in the HeLa cell line (human cervix cancer cells). The capping of glucose on Au nanoparticle was confirmed by Raman spectroscopy. The Glu-AuNP did not show any toxicity to the HeLa cell. The γ-radiation and carbon ion irradiation of HeLa cell with and without Glu-AuNP were performed to evaluate radiosensitization effects. The study revealed a significant reduction in radiation dose for killing the HeLa cells with internalized Glu-AuNPs as compared to the HeLa cells without Glu-AuNP. The Glu-AuNP treatment resulted in enhancement of radiation effect as evident from increase in relative biological effectiveness (RBE) values for carbon ion irradiated HeLa cells.

  10. Change in magnetic and structural properties of FeRh thin films by gold cluster ion beam irradiation with the energy of 1.67 MeV/atom

    Science.gov (United States)

    Koide, T.; Saitoh, Y.; Sakamaki, M.; Amemiya, K.; Iwase, A.; Matsui, T.

    2014-05-01

    The effect of energetic cluster ion beam irradiation on magnetic and structural properties of FeRh thin films have been investigated. The cluster ions used in the present studies consist of a few gold atoms with the energy of 1.67 MeV/gold atom. Saturation magnetization of the sample irradiated with Au3 cluster ion beam (280 emu/cc) is larger than that for the irradiated sample with Au1 ion beam (240 emu/cc) for the same irradiation ion fluence. These results can also be confirmed by the X-ray magnetic circular dichroism (XMCD) measurement; the XMCD signal for Au3 cluster ion irradiation is larger than that for Au1 ion irradiation. Since the ion beam irradiation induced magnetization of FeRh is significantly correlated with the amount of the lattice defects in the samples, cluster ion beam irradiation can be considered to effectively introduce the lattice defects in B2-type FeRh rather than the single ion beam. Consequently, cluster ion irradiation is better than single ion irradiation for the viewpoint of saturation magnetization, even if the same irradiation energy is deposited in the samples.

  11. Change in magnetic and structural properties of FeRh thin films by gold cluster ion beam irradiation with the energy of 1.67 MeV/atom

    Energy Technology Data Exchange (ETDEWEB)

    Koide, T.; Iwase, A. [Department of Materials Science, Osaka Prefecture University, Sakai, Osaka 599-8531 (Japan); Saitoh, Y. [Japan Atomic Energy Agency, Takasaki, Gunma 370-1292 (Japan); Sakamaki, M.; Amemiya, K. [High Energy Accelerator Research Organization, Tsukuba, Ibaraki 305-0801 (Japan); Matsui, T., E-mail: t-matsui@21c.osakafu-u.ac.jp [Research Organization for the 21st Century, Osaka Prefecture University Sakai, Osaka 599-8531 (Japan)

    2014-05-07

    The effect of energetic cluster ion beam irradiation on magnetic and structural properties of FeRh thin films have been investigated. The cluster ions used in the present studies consist of a few gold atoms with the energy of 1.67 MeV/gold atom. Saturation magnetization of the sample irradiated with Au3 cluster ion beam (280 emu/cc) is larger than that for the irradiated sample with Au1 ion beam (240 emu/cc) for the same irradiation ion fluence. These results can also be confirmed by the X-ray magnetic circular dichroism (XMCD) measurement; the XMCD signal for Au3 cluster ion irradiation is larger than that for Au1 ion irradiation. Since the ion beam irradiation induced magnetization of FeRh is significantly correlated with the amount of the lattice defects in the samples, cluster ion beam irradiation can be considered to effectively introduce the lattice defects in B2-type FeRh rather than the single ion beam. Consequently, cluster ion irradiation is better than single ion irradiation for the viewpoint of saturation magnetization, even if the same irradiation energy is deposited in the samples.

  12. Small angle proton-proton correlations in collisions of high energy light ions with carbon and gold nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Budilov, V.A.; Filipkowski, A.; Golembiewski, A.; Ilyuschenko, V.I.; Korejwo, A.; Kozma, P.; Laritcheva, A.P.; Nikitin, V.A.; Nomokonov, P.V.; Traikova, M.; Zhidkov, N.K. (Joint Inst. for Nuclear Research, Dubna (USSR)); Kotus, A.; Nawrot, A.; Szawlowski, M.; Zielinski, I.P. (Institute for Nuclear Studies, Warsaw (Poland)); Sidor, G.; Surala, M.; Turowiecki, A.; Wilhelmi, Z.; Zlomanczuk, J. (Warsaw Univ. (Poland). Inst. Fizyki Doswiadczalnej)

    1990-07-05

    Small angle correlations of protons (p>320 MeV/c) emitted in 5.1 GeV/c proton, 4 GeV/c deuteron and 8 GeV/c helium-4 collisions with carbon and gold targets were measured using plastic scintillator hodoscopes and NaI(Tl) detectors placed at 72deg and 101deg with respect to the beam. It has been found that for both targets the two-proton correlation function depends on the emission angle and that this dependence is stronger for the carbon target than for the gold one. (orig.).

  13. Collective optical Kerr effect exhibited by an integrated configuration of silicon quantum dots and gold nanoparticles embedded in ion-implanted silica

    Science.gov (United States)

    Torres-Torres, C.; López-Suárez, A.; Can-Uc, B.; Rangel-Rojo, R.; Tamayo-Rivera, L.; Oliver, A.

    2015-07-01

    The study of the third-order optical nonlinear response exhibited by a composite containing gold nanoparticles and silicon quantum dots nucleated by ion implantation in a high-purity silica matrix is presented. The nanocomposites were explored as an integrated configuration containing two different ion-implanted distributions. The time-resolved optical Kerr gate and z-scan techniques were conducted using 80 fs pulses at a 825 nm wavelength; while the nanosecond response was investigated by a vectorial two-wave mixing method at 532 nm with 1 ns pulses. An ultrafast purely electronic nonlinearity was associated to the optical Kerr effect for the femtosecond experiments, while a thermal effect was identified as the main mechanism responsible for the nonlinear optical refraction induced by nanosecond pulses. Comparative experimental tests for examining the contribution of the Au and Si distributions to the total third-order optical response were carried out. We consider that the additional defects generated by consecutive ion irradiations in the preparation of ion-implanted samples do not notably modify the off-resonance electronic optical nonlinearities; but they do result in an important change for near-resonant nanosecond third-order optical phenomena exhibited by the closely spaced nanoparticle distributions.

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

    Energy Technology Data Exchange (ETDEWEB)

    Misra, Nilanjal; Kumar, Virendra, E-mail: vkrawat75@gmail.com, E-mail: vkumar@barc.gov.in; Goel, Narender Kumar; Varshney, Lalit [Bhabha Atomic Research Centre, Radiation Technology Development Division (India)

    2015-07-15

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

  15. Fabrication of new carbon paste electrodes based on gold nano-particles self-assembled to mercapto compounds as suitable ionophores for potentiometric determination of copper ions

    Directory of Open Access Journals (Sweden)

    Rasoul Pourtaghavi Talemi

    2013-12-01

    Full Text Available In the present study, we investigate the potentiometric behavior of Cu2+ carbon paste electrodes based on two mercapto compounds 2-ethylmino-5-mercapto-1,3,4-thiadiazole (EAMT and 2-acetylamino-5-mercapto-1,3,4-thiadiazole (AAMT self-assembled on gold nano-paricle (GNP as ionophore. Then, the obtained results from the modified electrodes are compared. The self-assembled ionophores exhibit a high selectivity for copper ion (Cu2+, in which the sulfur and nitrogen atoms in their structure play a significant role as the effective coordination donor site for the copper ion. Among these electrodes, the best performance was obtained with the sensor with a EAMT/graphite powder/paraffin oil weight ratio of 4.0/68/28 with 200 µL of GNP which exhibits the working concentration range of 1.6×10−9 to 6.3×10−2 M and a nernstian slope of 28.9±0.4 mVdecade−1 of copper(II activity. The detection limit of electrode was 2.9(±0.2×10−10M and potential response was pH ; in other words, it was independent across the range of 2.8–6.3. The proposed electrode presented very good selectivity and sensitivity towards the Cu2+ ions over a wide variety of cations including alkali, alkaline earth, transition and heavy metal ions. Moreover, the proposed electrode was successfully applied as an indicator electrode in the potentiometric titration of Cu(II ions with EDTA and also the potentiometric determination of copper ions in spiked water samples.

  16. Effective and selective recovery of gold and palladium ions from metal wastewater using a sulfothermophilic red alga, Galdieria sulphuraria.

    Science.gov (United States)

    Ju, Xiaohui; Igarashi, Kensuke; Miyashita, Shin-Ichi; Mitsuhashi, Hiroaki; Inagaki, Kazumi; Fujii, Shin-Ichiro; Sawada, Hitomi; Kuwabara, Tomohiko; Minoda, Ayumi

    2016-07-01

    The demand for precious metals has increased in recent years. However, low concentrations of precious metals dissolved in wastewater are yet to be recovered because of high operation costs and technical problems. The unicellular red alga, Galdieria sulphuraria, efficiently absorbs precious metals through biosorption. In this study, over 90% of gold and palladium could be selectively recovered from aqua regia-based metal wastewater by using G. sulphuraria. These metals were eluted from the cells into ammonium solutions containing 0.2M ammonium salts without other contaminating metals. The use of G. sulphuraria is an eco-friendly and cost-effective way of recovering low concentrations of gold and palladium discarded in metal wastewater. PMID:27118429

  17. Zircon Senstive High Resolution Ion Microprobe (SHRIMP) study of granitoid intrusions in Zhaoye Gold Belt of Shandong Province and its implication

    Institute of Scientific and Technical Information of China (English)

    苗来成; 罗镇宽; 黄佳展; 关康; N.J. McNaughton; D. I. Groves

    1997-01-01

    The zircon Sensitive High Resolution Ion Microprobe (SHRIMP) results show that granitoid intrusions in Zhaoyc Gold Belt were emplaced at two periods of Mesozoic: Linglong and Luanjiahe types of granitic intrusions were emplaced between 160 Ma and 150 Ma (late Jurassic); Guojialing type of granodioritic intrusions, 130 Ma and 126 Ma (early Cretaceous). All the three types contain at least two major generations of inherited zircons with Precambrian ( >650 Ma) and early Mesozoic ages (200-250 Ma), respectively. The former suggests that these plu-tonic rocks are of crustal origin and that Precambrian basement with component of sialic crust up to 3.4 Ga old ( Middle Archean) exists in the region. The presence of abundant inherited zircons with early Mesozoic age indicates that the Precambrian basement was affected by a major tectono-thermal event, that is the collision of the North and South China blocks, at 250 Ma to 200 Ma. SHRIMP results also indicate that the gold mineralization in the region took place

  18. Development of a test strip based on DNA-functionalized gold nanoparticles for rapid detection of mercury (Ⅱ) ions

    Institute of Scientific and Technical Information of China (English)

    Jing Duan; Zhi Yong Guo

    2012-01-01

    A rapid,sensitive,selective and reliable strip assay based on DNA-functionalized gold nanoparticles for Hg2+ detection has been developed,with a detection limit 5 nmol/L.The measurement principle was based on thymine-Hg2+-thymine (T-Hg2+-T)coordination chemistry and streptavidin-biotin interaction.The major advantages of this assay are that results can be read visually without any instrument in less than 10 min and that it does not require any sample pretreatment.

  19. Colorimetric kinetic determination of potassium ions based on the use of a specific aptamer and catalytically active gold nanoparticles

    International Nuclear Information System (INIS)

    We describe a simple, highly sensitive, and selective colorimetric kinetic assay for the determination of potassium(I) by exploiting the specific recognition capability of an appropriate aptamer and catalytic signal amplification by gold nanoparticles (AuNPs). Amplification is based on the reduction of 4-nitrophenol by borohydride which is catalyzed by AuNPs. This leads to a color change of the solution from yellow to colorless, and the color change can be recognized with bare eyes or via photometry. The K(I)-selective aptamer is placed on the AuNPs and forms a tightly bound G-quadruplex with K(I) which partially masks the surface of the AuNPs and prevents 4-nitrophenol to be reduced at the catalytically active surface of the AuNPs. Hence, the rate of decoloration is retarded. The assay displays high selectivity for K(I) over other cations, has a linear response in the 0.1 nM to 10 μM concentration range, and a detection limit as low as 0.06 nM. In addition, these findings pave the way to novel analytical methods based on the use of gold nanoparticle-catalyzed chemical reactions. (author)

  20. A gold electrode modified with amino-modified reduced graphene oxide, ion specific DNA and DNAzyme for dual electrochemical determination of Pb(II) and Hg(II)

    International Nuclear Information System (INIS)

    Multilayered reduced graphene oxide (rGO) was functionalized with amino groups by treatment with nitrogen plasma. Raman spectroscopy showed plasma treatment not to substantially alter the chemical structure of rGO and that a wide range of functional nitrogen groups is evenly incorporated into the carbon lattice. The amino-modified rGO was used to design an electrochemical biosensor in which a DNAzyme, substrate DNA and Pb(II) and Hg(II) binding DNA were immobilized on the amino-rGO placed on a gold electrode. The high concentration of amino groups and the rough surface of the rGO favor DNA immobilization. Heavy metal ions are bound to the surface via specific interaction between DNA and the two ions which are detected by electrochemical impedance spectroscopy at a potential of 0.2 V (vs. Ag/AgCl). The detection limits for Pb(II) and Hg(II) are as low as 7.8 and 5.4 pM, respectively, and the analytical ranges extend from 0.01 to 100 nM. The sensor is highly specific and stable and therefore represents a highly promising tool for use in environmental monitoring. (author)

  1. Simple, Fast and Selective Detection of Adenosine Triphosphate at Physiological pH Using Unmodified Gold Nanoparticles as Colorimetric Probes and Metal Ions as Cross-Linkers

    Directory of Open Access Journals (Sweden)

    Huan Pang

    2012-11-01

    Full Text Available We report a simple, fast and selective colorimetric assay of adenosine triphosphate (ATP using unmodified gold nanoparticles (AuNPs as probes and metal ions as cross-linkers. ATP can be assembled onto the surface of AuNPs through interaction between the electron-rich nitrogen atoms and the electron-deficient surface of AuNPs. Accordingly, Cu2+ ions induce a change in the color and UV/Vis absorbance of AuNPs by coordinating to the triphosphate groups and a ring nitrogen of ATP. A detection limit of 50 nM was achieved, which is comparable to or lower than that achievable by the currently used electrochemical, spectroscopic or chromatographic methods. The theoretical simplicity and high selectivity reported herein demonstrated that AuNPs-based colorimetric assay could be applied in a wide variety of fields by rationally designing the surface chemistry of AuNPs. In addition, our results indicate that ATP-modified AuNPs are less stable in Cu2+, Cd2+ or Zn2+-containing solutions due to the formation of the corresponding dimeric metal-ATP complexes.

  2. Label-free colorimetric biosensing of copper(II) ions with unimolecular self-cleaving deoxyribozymes and unmodified gold nanoparticle probes

    International Nuclear Information System (INIS)

    Using unimolecular copper(II)-dependent self-cleaving deoxyribozymes (DNAzymes), a label-free colorimetric biosensor for copper(II) ions (Cu2+) has been developed based on the sequence-length-dependent adsorption of single-stranded deoxyribonucleic acid (ssDNA) on unmodified gold nanoparticles (AuNPs). In the presence of Cu2+, the Cu2+-dependent DNAzyme could be self-cleaved into short ssDNA fragments. The cleaved short ssDNA could adsorb rapidly onto the surface of the AuNPs. This enhanced the stability of the AuNPs against salt-induced aggregation, and thus the solution color remained red. In the absence of Cu2+, however, uncleaved long ssDNA adsorbed relatively slowly onto the AuNPs and upon the addition of salt, the electrostatic repulsion between the AuNPs was screened, resulting in aggregation of the AuNPs which produced a red-to-blue color change. Thus, Cu2+ detection could be realized by monitoring the color change of the AuNPs. The calibration curve showed that the absorption ratio values at 520 and 620 nm increased linearly over the Cu2+ concentration range of 0.625-15 μM, with a limit of detection of 290 nM. The other environmentally relevant metal ions did not interfere with the determination of Cu2+. Subsequently, the assay was employed to determine Cu2+ in several water samples, and the results were satisfactory. It is expected that the present colorimetric strategy will be possibly extended to the detection of cofactors of other in vitro-selected unimolecular self-cleaving DNAzymes, such as amino acids, nucleic acids, metal ions and small organic molecules.

  3. Label-free colorimetric biosensing of copper(II) ions with unimolecular self-cleaving deoxyribozymes and unmodified gold nanoparticle probes

    Energy Technology Data Exchange (ETDEWEB)

    Wang Yong; Yang Fan; Yang Xiurong, E-mail: xryang@ciac.jl.cn [State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, Jilin 130022 (China); Graduate School of the Chinese Academy of Sciences, Beijing 100039 (China)

    2010-05-21

    Using unimolecular copper(II)-dependent self-cleaving deoxyribozymes (DNAzymes), a label-free colorimetric biosensor for copper(II) ions (Cu{sup 2+}) has been developed based on the sequence-length-dependent adsorption of single-stranded deoxyribonucleic acid (ssDNA) on unmodified gold nanoparticles (AuNPs). In the presence of Cu{sup 2+}, the Cu{sup 2+}-dependent DNAzyme could be self-cleaved into short ssDNA fragments. The cleaved short ssDNA could adsorb rapidly onto the surface of the AuNPs. This enhanced the stability of the AuNPs against salt-induced aggregation, and thus the solution color remained red. In the absence of Cu{sup 2+}, however, uncleaved long ssDNA adsorbed relatively slowly onto the AuNPs and upon the addition of salt, the electrostatic repulsion between the AuNPs was screened, resulting in aggregation of the AuNPs which produced a red-to-blue color change. Thus, Cu{sup 2+} detection could be realized by monitoring the color change of the AuNPs. The calibration curve showed that the absorption ratio values at 520 and 620 nm increased linearly over the Cu{sup 2+} concentration range of 0.625-15 {mu}M, with a limit of detection of 290 nM. The other environmentally relevant metal ions did not interfere with the determination of Cu{sup 2+}. Subsequently, the assay was employed to determine Cu{sup 2+} in several water samples, and the results were satisfactory. It is expected that the present colorimetric strategy will be possibly extended to the detection of cofactors of other in vitro-selected unimolecular self-cleaving DNAzymes, such as amino acids, nucleic acids, metal ions and small organic molecules.

  4. Gold prices

    OpenAIRE

    Joseph G. Haubrich

    1998-01-01

    The price of gold commands attention because it serves as an indicator of general price stability or inflation. But gold is also a commodity, used in jewelry and by industry, so demand and supply affect its pricing and need to be considered when gold is a factor in monetary policy decisions.

  5. Colorimetric determination of copper ions based on the catalytic leaching of silver from the shell of silver-coated gold nanorods

    International Nuclear Information System (INIS)

    We have developed a method for the colorimetric determination of copper ions (Cu2+) that is based on the use of silver-coated gold nanorods (Au–Ag NRs). Its outstanding selectivity and sensitivity result from the catalytic leaching process that occurs between Cu2+, thiosulfate (S2O32−), and the surface of the Au–Ag NRs. The intrinsic color of the Au–Ag NRs changes from bright red to bluish green with decreasing thickness of the silver coating. The addition of Cu2+ accelerates the leaching of silver from the shell caused in the presence of S2O32−. This result in a decrease in the thickness of the silver shell which is accompanied a change in color and absorption spectra of the colloidal solution. The shifts in the absorption maxima are linearly related to the concentrations of Cu2+ over the 3–1,000 nM concentration range (R = 0.996). The method is cost effective and was applied to the determination of Cu2+ in real water samples. (author)

  6. Synthesis and Coordination Chemistry of a Phosphine-Decorated Fluorescein: "Double Turn-On" Sensing of Gold(III) Ions in Water.

    Science.gov (United States)

    Christianson, Anna M; Gabbaï, François P

    2016-06-20

    Although phosphine ligands are ubiquitous in transition metal chemistry, few reports of fluorescent phosphines exist that explore the effect of metal coordination on the photophysical properties of a phosphine-bound fluorescent group. The coordination chemistry of a derivative of fluorescein decorated with an o-phenylene-linked phosphine group has been studied with late transition metals. An Au(I) complex of the phosphine-decorated fluorescein has been structurally characterized, showing that the metal center is held closely over the plane of the fluorophore. Despite the presence of the heavy metal center, however, the phosphine-gold complex displays greatly increased fluorescence compared to the free ligand, in which photoelectron transfer from the lone-pair-bearing phosphine causes low emission. The phosphine-decorated fluorescein ligand was tested in a simple sensing system for metal ions in aqueous solution and shows a "turn-on" response to Au, Ag, and Hg, with an especially dramatic response to Au(III) species. The selectivity for Au(III) was determined to be the result of a "double turn-on" response that is both reaction- and coordination-based. PMID:27267582

  7. Synthesis and Coordination Chemistry of a Phosphine-Decorated Fluorescein: "Double Turn-On" Sensing of Gold(III) Ions in Water.

    Science.gov (United States)

    Christianson, Anna M; Gabbaï, François P

    2016-06-20

    Although phosphine ligands are ubiquitous in transition metal chemistry, few reports of fluorescent phosphines exist that explore the effect of metal coordination on the photophysical properties of a phosphine-bound fluorescent group. The coordination chemistry of a derivative of fluorescein decorated with an o-phenylene-linked phosphine group has been studied with late transition metals. An Au(I) complex of the phosphine-decorated fluorescein has been structurally characterized, showing that the metal center is held closely over the plane of the fluorophore. Despite the presence of the heavy metal center, however, the phosphine-gold complex displays greatly increased fluorescence compared to the free ligand, in which photoelectron transfer from the lone-pair-bearing phosphine causes low emission. The phosphine-decorated fluorescein ligand was tested in a simple sensing system for metal ions in aqueous solution and shows a "turn-on" response to Au, Ag, and Hg, with an especially dramatic response to Au(III) species. The selectivity for Au(III) was determined to be the result of a "double turn-on" response that is both reaction- and coordination-based.

  8. Effects of gold coating on experimental implant fixation

    DEFF Research Database (Denmark)

    Zainali, Kasra; Danscher, Gorm; Jakobsen, Thomas;

    2009-01-01

    Insertions of orthopedic implants are traumatic procedures that trigger an inflammatory response. Macrophages have been shown to liberate gold ions from metallic gold. Gold ions are known to act in an antiinflammatory manner by inhibiting cellular NF-kappa B-DNA binding and suppressing I-kappa B-...

  9. Stage II recovery behavior of a series of ion-irradiated platinum (gold) alloys as studied by field-ion microscopy. [0. 10, 0. 62, and 4. 0 at. percent Au and pure Pt

    Energy Technology Data Exchange (ETDEWEB)

    Wei, C.Y.; Seidman, D.N.

    1976-11-01

    Direct and visible evidence was obtained for long-range migration of self-interstitial atoms (SIAs) in Stage II of three different ion-irradiated platinum (gold) alloys. Field-ion microscope (FIM) specimens of Pt--0.10, 0.62 and 4.0 at. percent Au alloys were irradiated in-situ with 30-keV W/sup +/ or Pt/sup +/ ions at a tip temperature of 35 to 41 K at 2 x 10/sup -9/ torr. Direct observation of the surfaces of the FIM specimens during isochronal warming experiments to 100 K showed that a flux of SIAs crossed the surfaces of the specimens between 40 to 100 K. The spectrum for each alloy consisted of two recovery peaks (substages II/sub B/ and II/sub C/). The results are explained on the basis of an impurity-delayed diffusion mechanism employing a two-level trapping model. The application of this diffusion model to the isochronal recovery spectra yielded a dissociation enthalpy (DELTAh/sub li-Au//sup diss/) and an effective diffusion coefficient for each substage; for substage II/sub B/ DELTAh/sub li-Au//sup diss/ (II/sub B/) = 0.15 eV and for substage II/sub C/ DELTAh/sub li-Au//sup diss/ (II/sub C/) = 0.24 eV. A series of detailed control experiments was also performed to show that the imaging electric field had not caused the observed long-range migration of SIAs and that the observed effects were not the result of surface artifacts. 14 figures, 6 tables.

  10. Efficient On-Off Ratiometric Fluorescence Probe for Cyanide Ion Based on Perturbation of the Interaction between Gold Nanoclusters and a Copper(II)-Phthalocyanine Complex.

    Science.gov (United States)

    Shojaeifard, Zahra; Hemmateenejad, Bahram; Shamsipur, Mojtaba

    2016-06-22

    A new ratiometric fluorescent sensor was developed for the sensitive and selective detection of cyanide ion (CN(-)) in aqueous media. The ratiometric sensing system is based on CN(-) modulated recovery of copper(II) phthalocyanine (Cu(PcTs)) fluorescence signal at the expense of diminished fluorescence intensity of gold nanoclusters (AuNCs). Preliminary experiments revealed that the AuNCs and Cu(PcTs) possess a turn-off effect on each other, the interaction of which being verified through studying their interactions by principle component analysis (PCA) and multivariate cure resolution-alternating least-squares (MCR-ALS) methods. In the presence of CN(-) anion, the AuNCs and Cu(PcTs) interaction was perturbed, so that the fluorescence of Cu (PcTs), already quenched by AuNCs, was found to be efficiently recovered, while the fluorescence intensity of AuNCs was quenched via the formation of a stable [Au(CN)2](-) species. The ratiometric variation of AuNCs and Cu(PcTs) fluorescence intensities leads to designing a highly sensitive probe for CN(-) ion detection. Under the optimal conditions, CN(-) anion was detected without needing any etching time, over the concentration range of 100 nM-220 μM, with a detection limit of 75 nM, which is much lower than the allowable level of CN(-) in water permitted by the World Health Organization (WHO). Moreover, the detection of CN(-) was developed based on the CN(-) effects on the blue and red florescent colors of Cu(PcTs) and AuNCs, respectively. The designed probe displays a continuous color change from red to blue by addition of CN(-), which can be clearly observed by the naked eye in the range of 7-350 μM, under UV lamp. The prepared AuNCs/Cu(PcTs) probe was successfully utilized for the selective and sensitive determination of CN(-) anion in two different types of natural water (Rodbal dam and rainwater) and also in blood serum as a biological sample. PMID:27211049

  11. Gold Returns

    OpenAIRE

    Robert J. Barro; Sanjay P. Misra

    2013-01-01

    From 1836 to 2011, the average real rate of price change for gold in the United States is 1.1% per year and the standard deviation is 13.1%, implying a one-standard-deviation confidence band for the mean of (0.1%, 2.1%). The covariances of gold's real rate of price change with consumption and GDP growth rates are small and statistically insignificantly different from zero. These negligible covariances suggest that gold's expected real rate of return--which includes an unobserved dividend yiel...

  12. Colorimetric response of dithizone product and hexadecyl trimethyl ammonium bromide modified gold nanoparticle dispersion to 10 types of heavy metal ions: understanding the involved molecules from experiment to simulation.

    Science.gov (United States)

    Leng, Yumin; Li, Yonglong; Gong, An; Shen, Zheyu; Chen, Liang; Wu, Aiguo

    2013-06-25

    A new kind of analytical reagent, hexadecyl trimethyl ammonium bromide (CTAB), and dithizone product-modified gold nanoparticle dispersion, is developed for colorimetric response to 10 types of heavy metal ions (M(n+)), including Cr(VI), Cr(3+), Mn(2+), Co(2+), Ni(2+), Cu(2+), Zn(2+), Cd(2+), Hg(2+), and Pb(2+). The color change of the modified gold nanoparticle dispersion is instantaneous and distinct for Mn(2+), Co(2+), Ni(2+), Cu(2+), Zn(2+), Cd(2+), Hg(2+), and Pb(2+). The color change results from the multiple reasons, such as electronic transitions, cation-π interactions, formation of coordination bonds, and M(n+)-induced aggregation of gold nanoparticles (AuNPs). The different combining capacity of heavy metal ions to modifiers results in the different broadening and red-shifting of the plasmon peak of modified AuNPs. In addition, Cr(VI), Cu(2+), Co(2+), Ni(2+), and Mn(2+) cause the new UV-vis absorption peaks in the region of 360-460 nm. The interactions between the modifiers and AuNPs, and between the modifiers and M(n+), are investigated by using Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. The results confirm that AuNPs are modified by CTAB and dithizone products through electrostatic interactions and Au-S bonds, respectively, and the M(n+)-N bonds form between M(n+) and dithizone products. Furthermore, the experimental and density functional theory calculated IR spectra prove that dithizone reacts with NaOH to produce C6H5O(-) and [SCH2N4](2-). The validation of this method is carried out by analysis of heavy metal ions in tap water. PMID:23724944

  13. Gold monetization and gold discipline

    OpenAIRE

    Flood, Robert P.; Peter M. Garber

    1981-01-01

    The paper is a study of the price level and relative price effects of a policy to monetize gold and fix its price at a given future time and at the then prevailing nominal price. Price movements are analyzed both during the transition to the gold standard and during the post-monetization period. The paper also explores the adjustments to fiat money which are necessary to ensure that this type of gold monetization is non-inflationary. Finally, some conditions which produce a run on the governm...

  14. The RHIC gold rush

    CERN Document Server

    Schäfer, T

    2003-01-01

    Physicists are colliding gold nuclei to recreate the fireball that existed in the very early universe, and they may have found evidence for quark-gluon plasma. What happens to ordinary matter as you heat it to higher and higher temperatures, or compress it to greater and greater densities? This simple question underpins a major effort to create extreme conditions in the lab, which has recently taken the shape of the Relativistic Heavy Ion Collider (RHIC). This machine has been colliding gold nuclei since 2000, and has produced tantalizing hints that a new state of matter - the quark-gluon plasma - is created in the reactions. But it has also sparked surprises that are sending researchers back to the drawing board. (U.K.)

  15. 离子注入型与金硅面垒型半导体探测器温度特性比较%Temperature Characteristic Comparison between Ion-injection and Gold Silicon Surface Barrier Semi-conducting Detectors

    Institute of Scientific and Technical Information of China (English)

    崔晓辉; 谷铁男; 张燕; 袁宝吉; 刘明健; 闫学昆

    2011-01-01

    The performance of semi-conducting detector is sensitive to temperature,which directly affects the stability and precision of spectrum system.A bias-voltage testing circuit,used for temperature characteristic testing was designed firstly,and then the characteristic curve between bias-voltage and temperature,for ion-injection detector and gold silicon surface barrier detector respectively,was ascertained.Experimental results show that the temperature characteristic of an ion-injection detector is much better than that of a gold silicon surface barrier detector.This method is valid for the use and selection of semi-conducting detector.%半导体探测器性能受温度影响较大,影响着辐射探测系统的稳定性和测量精度。本文设计了一个温度测试电路,通过温度测试实验分别得出了离子注入型和金硅面垒型半导体探测器的温度特性曲线。测试结果表明,离子注入型半导体探测器的温度特性明显优于金硅面垒型半导体探测器。本文的结果可为半导体探测器的使用、筛选提供参考。

  16. Design of gold nanoshells via a gelatin-mediated self-assembly of gold nanoparticles on silica cores

    OpenAIRE

    Allouche, Joachim; Soulé, Samantha; Dupin, Jean-Charles; Masse, Sylvie; ,; Coradin, Thibaud; Martinez, Hervé

    2014-01-01

    International audience A gelatin-mediated self-assembly of gold nanoparticles on silica particles has been performed during gold ion reduction using ascorbic acid as reductant and PVP as stabilizer. Gold nanoshells with near infrared photothermal properties have been successfully designed.

  17. World Gold Markets, Istanbul Gold Exchange and Gold Risk Management

    OpenAIRE

    Serdar Citak

    1999-01-01

    The establishment of Istanbul Gold Exchange (IGE) is the most important stage in the Turkish gold sector restructuring process. IGE has provided a competitive formation in prices and the price differential between Turkey and international markets has been cut dramatically. Today, Turkish investors can buy and sell gold in international prices in the IGE Precious Metals Market. Gold is accepted as a hedge tool against inflation and as a safe haven in economic crisis, world-wide. Gold is the on...

  18. Green Gold

    International Nuclear Information System (INIS)

    The main purpose of this work is to offer a general panoramic of the processes or experiences pilot that are carried out in the Project Green Gold, as strategy of environmental sustainability and organizational invigoration in Choco, especially in the 12 communities of the municipalities of Tado and Condoto. It is also sought to offer a minimum of information on the techniques of handmade production and to show the possibilities to carry out in a rational way the use and use of the natural resources. The Project Green Gold is carried out by the Corporation Green Gold (COV) and co-financed with resources of international and national character, the intervention of the financial resources it achievement mainly for the use of clean processes in the extraction stages and metals benefit. The project is centered primarily in the absence of use of products or toxic substances as the mercury, fair trade, organizational invigoration, execution of 11 approaches and certification of the metals Gold and Platinum. The COV, it has come executing the proposal from the year 2001 with the premise of contributing to the balance between the rational exploitation of the natural resources and the conservation of the environment in the Choco. In the project they are used technical handmade characteristic of the region framed inside the mining activity and production activities are diversified in the productive family units. Those producing with the support of entities of juridical character, specify the necessary game rules for the extraction and products commercialization

  19. Ion Colliders

    CERN Document Server

    Fischer, W

    2014-01-01

    High-energy ion colliders are large research tools in nuclear physics to study the Quark-Gluon-Plasma (QGP). The range of collision energy and high luminosity are important design and operational considerations. The experiments also expect flexibility with frequent changes in the collision energy, detector fields, and ion species. Ion species range from protons, including polarized protons in RHIC, to heavy nuclei like gold, lead and uranium. Asymmetric collision combinations (e.g. protons against heavy ions) are also essential. For the creation, acceleration, and storage of bright intense ion beams, limits are set by space charge, charge change, and intrabeam scattering effects, as well as beam losses due to a variety of other phenomena. Currently, there are two operating ion colliders, the Relativistic Heavy Ion Collider (RHIC) at BNL, and the Large Hadron Collider (LHC) at CERN.

  20. Quantum Chemistry Calculations on the Interaction Between Kaolinite and Gold

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The density function and discrete variation method (DFT-DVM) is used to study the interaction between kaolinite and gold. The correlation among the structure, chemical bond and stability is discussed. Several models are selected without gold and with gold in different directions and sites. The results show that the models with gold on the edge of kaolinite basal layer are more stable than those with gold above or under the layer, the models with gold near to [AlO2(OH)4] octahedra are more stable than those with gold near to the vacancy without aluminium. The interaction between gold and the surface ions of kaolinite is strong enough to form the surface complexes.

  1. Going for Gold

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    While the international gold price in February hit the highest point in 25 years at $541.20 per ounce for futures delivery, a new gold rush is sweeping across China. According to the World Gold Council, the London-based gold marketing organization funded by leading global gold mining firms, the purchase of gold products in China grew by 9 percent in the first nine

  2. Gold in Modern Economy

    OpenAIRE

    Boryshkevych Olena V.

    2014-01-01

    The article studies the role of gold in modern economy. It analyses dynamics and modern state of the gold market. It studies volumes of contracts in exchange and off-exchange markets. In order to reveal changes of key features of the gold market, it focuses on the study of gold demand volumes, studies volumes and geographical changes in the world gold mining, and analyses volumes of monetary gold of central banks and its share in gold and currency reserves. It analyses price fluctuations in t...

  3. M X-ray production cross-sections of gold and lead by 4 to 12 MeV carbon ions

    International Nuclear Information System (INIS)

    M shell X-ray production cross-sections of Au and Pb induced by 0.33-1.0 MeV/u C2,3,4+ ions are reported. The results are compared with the predictions of the first Born and ECPSSR theories. The first Born predictions are in fair agreement with the measured values, while the ECPSSR calculations are by a factor of 2-5 lower than the data

  4. Gold-Mining

    DEFF Research Database (Denmark)

    Raaballe, J.; Grundy, B.D.

    2002-01-01

    of operating gold mines. Asymmetric information on the reserves in the mine implies that, at a high enough price of gold, the manager of high type finds the extraction value of the company to be higher than the current market value of the non-operating gold mine. Due to this under valuation the maxim of market...... value maximization forces the manager of high type to extract the gold.The implications are three-fold. First, all managers (except the lowest type) extract the gold too soon compared to the first-best policy of leaving the gold in the mine forever. Second, a manager of high type extracts the gold......  Based on standard option pricing arguments and assumptions (including no convenience yield and sustainable property rights), we will not observe operating gold mines. We find that asymmetric information on the reserves in the gold mine is a necessary and sufficient condition for the existence...

  5. 基于手性金纳米粒子圆二色光谱法识别与检测银离子%Recognition and Detection of Silver Ion by Circular Dichroism Spectrum Based on Chiral Gold Nanoparticles

    Institute of Scientific and Technical Information of China (English)

    韦克毅; 王猛; 杜宇; 蔡波; 江云宝

    2016-01-01

    In this work,chiral gold particles with optical activity can be obtained by a facile liquid phase method.The textural proper-ties of the as-prepared samples were characterized by high resolution transmission electron microscopy,circular dichroism spectrum and absorption spectrum.The results show that the average particle size for the production is 3.6 nm and silver ion can be selectively recognized from 1 3 kinds of metal ions in 1 2 min with universal recurrence.We also established the standard curve for detecting silver ion.This study demonstrates that the linear range for this curve is 0.2-30μmol/L,the linearly dependent coefficient is 0.995(n=15),which supplies a simple new environmentally friendly method for quickly detecting and recognizing silver ion in environmental water samples with high precision.%采用液相制备方法获得具有光学活性的手性金纳米粒子,通过吸收光谱和圆二色光谱及高分辨透射电镜对手性金纳米粒子进行表征.利用圆二色光谱法建立手性金纳米粒子对 Ag+选择性识别方法,结果表明手性金纳米粒子对Ag+响应时间仅需12 min,手性金纳米粒子能够从13种常见金属离子中选择性识别 Ag+,并对多种常见金属离子具有较好的抗干扰能力,检测灵敏度高并且具有良好的重现性.所建立标准曲线线性范围为0.2~30μmol/L,线性相关系数R2=0.995(n=15),Ag+的检测限为0.2μmol/L;为环境水样中 Ag+的识别和检测提供了一种简单、精确、快速、环境友好的新方法.

  6. Internal crystallography and thermal history of natural gold alloys

    Science.gov (United States)

    Hough, R.; Cleverley, J. S.

    2011-12-01

    New studies of gold are revealing how metallography is a key component of our understanding of the deposition of precious alloys in primary ore systems. Alluvial gold nuggets once thought to be secondary in origin have now been shown to be the erosional residue of hypogene systems, i.e. primary. This has been achieved through analysis of the internal crystallography using electron back scattered diffraction of large area ion beam polished gold samples. Comparisons of the microstructure are also being made with experiments on gold alloys with the same Ag contents where real time heating and in-situ microstructure mapping reveal the structures are of high temperature origin. A new frontier in gold analysis in both hypogene and supergene systems is the nano domain. In hypogene settings gold at all scales can be metallic and particulate as has been directly observed in refractory ores, or the so called "invisible gold" in pyrite and arsenopyrite. Such nanoparticulate and colloidal transport of gold is a viable mechanism of dispersing the gold during weathering of ore deposits. These gold nanoparticles, long known about in materials sciences and manufacturing have now been seen in these natural environments. Such colloids are also likely to play an important role in gold transport in hydrothermal deposits. The regularly heterogeneous distribution, trace concentration and nanoparticulate grain size of metallic gold in all ore systems has made it difficult for direct observation. Yet, it is critical to be able to establish a broad view of the microstructural/microchemical residence of the actual gold in a given sample. New generation element mapping tools now allow us to 'see' this invisible gold component for the first time and to probe its chemistry and controls on deposition. These studies have the potential to provide a new approach and view of the formation, deposition and provenance history of the metal in all gold deposits.

  7. Evolution of gold thin films to nanoparticles using plasma ion bombardment and their use as a catalyst for carbon nanotube growth

    International Nuclear Information System (INIS)

    We investigate the evolution of Au thin films to nanoparticles caused by plasma ion bombardment and report their validity as a catalyst on the growth of carbon nanotubes (CNTs). The Au thin films having 1–50 Å thickness ranges were precisely prepared by electron beam deposition. The plasma ion bombardments with the plasma power from 5 to 15 W were performed at 500 °C for 10 min under 1.33 × 102 Pa of Ar to investigate the effects of plasma power on the surface structures. It is interesting that the mean size of Au nanoparticles increased as plasma power gets high in the thinner film cases, which might be the results of sputtering and surface diffusion-related aggregation. On the contrary, the mean particle size of the thicker films decreased at lower plasma power regime due to the sputtering, then, increased again at the highest plasma power, which might be caused by the diffusion-induced aggregation of the films. Finally, to investigate the catalytic ability of the thin film-induced Au nanoparticles, we grew CNTs by a thermal chemical vapor deposition with a methane source. It was found that the Au nanoparticles obtained from the plasma-treated 5 Å thick films act as an efficient catalyst for the growth of single-walled CNTs. - Highlights: • We report the evolution of Au thin films to nanoparticles by plasma treatment. • The mean size of Au nanoparticles increased with increasing plasma power. • The nanoparticle size increases by sputtering and diffusion-induced aggregation. • The plasma-treated 5 Å thick films act as an efficient catalyst for SWNTs growth

  8. NA35: sulphur-gold collision

    CERN Multimedia

    1991-01-01

    In this image the real particles produced by the collision of a 6400 GeV sulphur ion with a gold target can be seen as they pass through a streamer chamber. Streamer chambers consist of a gas chamber through which a strong pulsed electric field is passed, creating sparks as a charged particle passes through it. The NA35 experiment, which was in operation in the 1980s, was part of CERN's ongoing heavy ion project.

  9. How many gold atoms make gold metal?

    OpenAIRE

    Häkkinen, Hannu; Malola, Sami

    2015-01-01

    It is well known that a piece of gold is an excellent metal: it conducts heat and electricity, it is malleable to work out for jewellery or thin coatings, and it has the characteristic golden colour. How do these everyday properties – familiar from our macroscopic world – change when a nanometre-size chunk of gold contains only 100, 200 or 300 atoms?

  10. Frontiers in Gold Chemistry

    OpenAIRE

    Mohamed, Ahmed A.

    2015-01-01

    Basic chemistry of gold tells us that it can bond to sulfur, phosphorous, nitrogen, and oxygen donor ligands. The Frontiers in Gold Chemistry Special Issue covers gold complexes bonded to the different donors and their fascinating applications. This issue covers both basic chemistry studies of gold complexes and their contemporary applications in medicine, materials chemistry, and optical sensors. There is a strong belief that aurophilicity plays a major role in the unending applications of g...

  11. Controlled Aspect Ratios of Gold Nanorods in Reduction-Limited Conditions

    Directory of Open Access Journals (Sweden)

    Jong-Yeob Kim

    2011-01-01

    Full Text Available Aspect ratios of gold nanorods have been finely modified in reduction-limited conditions via two electrochemical ways: by changing the amount of a growth solution containing small gold clusters in the presence of already prepared gold nanorods as seeds or by changing electrolysis time in the presence or absence of a silver plate. While the atomic molar ratio of gold in the growth solution to gold in the seed solution is critical in the former method, the relative molar ratio of gold ions to silver ions in the electrolytic solution is important in the latter way for the control of the aspect ratios of gold nanorods. The aspect ratios of gold nanorods decrease with an increase of electrolysis time in the absence of a silver plate, but they increase with an increase of electrolysis time in the presence of a silver plate.

  12. Reversible formation of gold nanoparticle–surfactant composite assemblies for the preparation of concentrated colloidal solutions

    OpenAIRE

    Shalkevich, Natallia; Shalkevich, Andrey; Si-Ahmed, Lynda; Bürgi, Thomas

    2010-01-01

    We have developed a simple method for the preparation of nearly mono-dispersed stable gold colloids with a fairly high concentration using a two step procedure. First we synthesize citrate capped gold nanoparticles and then exchange the citrate ions with triethyleneglycolmono-11-mercaptoundecylether (EGMUDE). This leads to the immediate precipitation and formation of composite assemblies. The gold nanoparticles were successfully self-redispersed after a few days. The prepared gold colloid can...

  13. Functionalization of Amorphous Chalcogenide and Titanium Oxide Layers by Gold Nanoparticles

    OpenAIRE

    Kökényesi Sándor (1946-) (fizikus); Biri Sándor; Hegedűs Csaba (1953-) (fogszakorvos); Csarnovics István (1986-) (fizikus); Csik Attila

    2014-01-01

    The technology problems of fabricating different, nanometers sized gold particles in the layered composites like light-sensitive chalcogenide glass/gold nanoparticles/transparent substrate or titanium/titanium oxide/gold nanoparticles were investigated in our work. Combination of ion implantation, plasma deposition with annealing processes results physical routes for creation of gold nanoparticles in the mentioned structures, which possess plasmon effects. These functionalized structures are ...

  14. Cyclic photochemical re-growth of gold nanoparticles: Overcoming the mask-erosion limit during reactive ion etching on the nanoscale

    Directory of Open Access Journals (Sweden)

    Burcin Özdemir

    2013-12-01

    Full Text Available The basic idea of using hexagonally ordered arrays of Au nanoparticles (NP on top of a given substrate as a mask for the subsequent anisotropic etching in order to fabricate correspondingly ordered arrays of nanopillars meets two serious obstacles: The position of the NP may change during the etching process and, thus, the primary pattern of the mask deteriorates or is completely lost. Furthermore, the NP are significantly eroded during etching and, consequently, the achievable pillar height is strongly restricted. The present work presents approaches on how to get around both problems. For this purpose, arrays of Au NPs (starting diameter 12 nm are deposited on top of silica substrates by applying diblock copolymer micelle nanolithography (BCML. It is demonstrated that evaporated octadecyltrimethoxysilane (OTMS layers act as stabilizer on the NP position, which allows for an increase of their size up to 50 nm by an electroless photochemical process. In this way, ordered arrays of silica nanopillars are obtained with maximum heights of 270 nm and aspect ratios of 5:1. Alternatively, the NP position can be fixed by a short etching step with negligible mask erosion followed by cycles of growing and reactive ion etching (RIE. In that case, each cycle is started by photochemically re-growing the Au NP mask and thereby completely compensating for the erosion due to the previous cycle. As a result of this mask repair method, arrays of silica nanopillar with heights up to 680 nm and aspect ratios of 10:1 are fabricated. Based on the given recipes, the approach can be applied to a variety of materials like silicon, silicon oxide, and silicon nitride.

  15. Anisotropic Gold Nanocrystals:. Synthesis and Characterization

    Science.gov (United States)

    Stiufiuc, R.; Toderas, F.; Iosin, M.; Stiufiuc, G.

    In this letter we report on successful preparation and characterization of anisotropic gold nanocrystals bio-synthesized by reduction of aqueous chloroaurate ions in pelargonium plant extract. The nanocrystals have been characterized by means of Transmission Electron Microscopy (TEM), UV-VIS absorption spectroscopy and tapping mode atomic force microscopy (TM-AFM). Using these investigation techniques, the successful formation of anisotropic single nanocrystals with the preferential growth direction along the gold (111) plane has been confirmed. The high detail phase images could give us an explanation concerning the growth mechanism of the nanocrystals.

  16. The Physico-Chemical Conditions for Mobilization of Gold in Mobin Gold Deposit, Southwest Hunan, China

    Institute of Scientific and Technical Information of China (English)

    谷俐; 杨华; 戴塔根; 刘利萍

    2002-01-01

    Experiments on water-rock interaction were carried out on wall-rock samples from the Mobin gold deposit, Southwest Hunan, China, with the aim of determining the optimum physical and chemical conditions for the mobilization of gold in solution. Results indicate that gold is most easily mobilized from the wall rock-tuffaceous slate of the Mobin Deposit. Mobi lization is optimized if fluids are neutral to slightly alkaline and contain both chlorine and sulphur ions at the concentration and composition of about [0.25M (NH4)2S + 1M NaCl]. The amount of gold leached from the tuffaceous slate increases with temperature although the effect decreases above about 200℃ .

  17. Gold nanoparticle–choline complexes can block nicotinic acetylcholine receptors

    Directory of Open Access Journals (Sweden)

    Chur Chin

    2010-04-01

    Full Text Available Chur Chin1, In Kyeom Kim2, Dong Yoon Lim3, Ki Suk Kim4, Hyang Ae Lee4, Eun Joo Kim41Department of Pediatrics, Fatima Hospital, Daegu, Korea; 2Department of Pharmacology, School of Medicine, Kyungpook National University, Daegu, Korea; 3Department of Pharmacology, School of Medicine, Chosun University, Gwangju, Korea; 4Korea Institute of Toxicology, Daejeon, KoreaAbstract: We identified a novel class of direct ion-channel blockers of ligand-gated ion channels called the gold nanoparticle–choline complex. Negatively charged gold nanoparticles (1.4 nm block ion pores by binding to the sulfur group of the cysteine loop of nicotinic acetylcholine receptors (nAChRs, and currents evoked by acetylcholine (Ach can break these bonds. The current evoked by ACh in nAChRs was blocked directly in ion pores by the gold nanoparticle–choline complex. In adrenal-gland perfusion studies, the complex also blocked nAChRs by diminishing catecholamine release by about 75%. An in vivo study showed muscle relaxation in rats after injection of the complex. These results will foster the application of gold nanoparticles as a direct ion-channel blocker. Keywords: negatively charged gold nanoparticle, choline, gold–sulfur bond, nicotinic acetylcholine receptor, direct ion-channel blocker

  18. Gold Thione Complexes

    OpenAIRE

    Francesco Caddeo; Vanesa Fernández-Moreira; Massimiliano Arca; Antonio Laguna; Vito Lippolis; M. Concepción Gimeno

    2014-01-01

    The reaction of the ligand Et4todit (4,5,6,7-Tetrathiocino-[1,2-b:3,4-b']-diimidazolyl-1,3,8,10-tetraethyl-2,9-dithione) with gold complexes leads to the dinuclear gold(I) complexes [{Au(C6F5)}2(Et4todit)] and [Au(Et4todit)]2(OTf)2, which do not contain any gold-gold interactions, or to the gold(III) derivative [{Au(C6F5)3}2(Et4todit)]. The crystal structures have been established by X-ray diffraction studies and show that the gold centers coordinate to the sulfur atoms of the imidazoline-2-t...

  19. Polymer Protected Gold Nanoparticles

    OpenAIRE

    Shan, Jun

    2006-01-01

    Polymer protected gold nanoparticles have successfully been synthesized by both "grafting-from" and "grafting-to" techniques. The synthesis methods of the gold particles were systematically studied. Two chemically different homopolymers were used to protect gold particles: thermo-responsive poly(N-isopropylacrylamide), PNIPAM, and polystyrene, PS. Both polymers were synthesized by using a controlled/living radical polymerization process, reversible addition-fragmentation chain transfer (RAFT)...

  20. Magic Gold Nanotubes

    OpenAIRE

    SENGER, R. Tuğrul; DAĞ, Sefa; ÇIRACI, Salim

    2005-01-01

    In recent ultra-high-vacuum transmission-electron-microscopy experiments evidence is found for the formation of suspended gold single-wall nanotubes (SWNTs) composed of five helical strands. Similar to carbon nanotubes, the (n,m) notation defines the structure of the gold SWNTs. Experimentally, only the (5,3) tube has been observed to form among several other possible alternatives. Using first-principles calculations we demonstrate that gold atoms can form both freestanding and tip-...

  1. Gold as an investment

    OpenAIRE

    Zemánek, Adam

    2015-01-01

    Bachelor thesis was created to understand investments in gold, to analyse the develop-ment of its price, discussing the reasons why people should invest in gold. Moreover, it introduces different forms of availability and possible earnings from investing in gold. First part is focused on describing important properties of this valuable commodity. Second part of the thesis analyses specific possibilities of investments and compares them with each other from the point of view of an investor.

  2. A Gold Bubble?

    OpenAIRE

    Dirk G Baur; Kristoffer Glover

    2012-01-01

    In this paper we use a test developed by Phillips et al. (2011) to identify a bubble in the gold market. We find that the price of gold followed an explosive price process between 2002 and 2012 interrupted only briefly by the subprime crisis in 2008. We also provide a theoretical foundation for such bubble tests based on a behavioural model of heterogeneous agents and demonstrate that periods of explosive price behaviour are consistent with increased chartist activity in the gold market. The ...

  3. Gold induced apoptsis study

    DEFF Research Database (Denmark)

    Laustsen, Christoffer

    2008-01-01

    in silico methods are here proposed for apoptosis studies and for AMG studies.   Methods   MR - heating of high concentration micrometer gold and low concentration nano gold.   CSLM of ethidum bromide stained cell lines, with and witout gold and automated image processing.   AMG gold uptake study...... the low energy radio frequencies. If the method is demonstrated to be feasible, next step is testing in cell line trials.   Confocal microscopy experiments on cells are very hard to do reliable and reproducible statistic on, due to the fact that that it’s user counting which makes the data. Automatic...

  4. The relative valuation of gold

    OpenAIRE

    Baur, Dirk G.; Beckmann, Joscha; Czudaj, Robert

    2016-01-01

    Gold is a globally traded asset and held in large quantities by investors and central banks. Since there is no established model to assess if the price of gold is overvalued or undervalued, we propose a relative valuation framework based on gold price ratios. We analyze gold prices relative to commodity prices, consumer prices, stock prices, dividend and bond yields and find that the relative value of gold varies significantly over time indicating pronounced periods of mispricing of gold rela...

  5. Gold Nanoparticle-based Dynamic Light Scattering Assay for Detection of Mercury Ion%基于金纳米粒子的动态光散射法检测溶液中的汞离子

    Institute of Scientific and Technical Information of China (English)

    马立娜; 刘殿骏; 王振新

    2014-01-01

    A gold nanoparticle ( GNP)-based dynamic light scattering ( DLS) assay has been developed for detecting mercury ion ( Hg2+) in aqueous solution. The GNPs are able to maintain monodisperse state in relative high ionic strength ( 0. 1 mol/L NaCl ) aqueous solution because Hg2+ aptamer 5’-TTTCTTCTTTCTTCCCCCCTTGTTTGTTGTTT-3’( Probe DNA ) can adsorb on the GNP surface by electrostatic interaction. In the presence of Hg2+, the Probe DNA molecules easily desorb from GNP surface because of T-Hg2+-T formation. The unprotected GNPs form aggregates in 100 mmol/L NaCl solution, resulting in increased significantly the average hydrodynamic diameter of GNPs. Under the conditions of pH 7. 43, 110 nmol/L aptamer, 100 mmol/L NaCl and 30 minutes incubation time of Hg2+with aptamer, the difference of average hydrodynamic diameter (△D ) of GNPs was increased linearly with logarithm of Hg2+concentration over the range from 0. 1 nmol/L to 5 μmol/L, with a detection limit of 0. 1 nmol/L. Moreover, satisfactory results were obtained when the proposed method was applied to detect Hg2+ in real samples.%发展了一种基于汞离子( Hg2+)适配体( Aptamer)免标记金纳米粒子的动态光散射( DLS)法,用于灵敏、选择性的检测溶液中的Hg2+。 Aptamer 5'-TTTCTTCTTTCTTCCCCCCTTGTTTGTTGTTT-3'与Hg2+的特异性结合使金纳米粒子失去保护,在含有100 mmol/L NaCl的缓冲溶液中发生聚集,金纳米粒子的平均水合粒径变大。在pH=7.43,110 nmol/L Aptamer ,100 mmol/L NaCl,Hg2+与Probe DNA孵育时间为30 min的实验条件下,金纳米粒子水合粒径的变化值(DD)与Hg2+的浓度成正比。检出Hg2+的线性范围为0.1 nmol/L~5μmol/L,检出限达0.1 nmol/L。湖水及矿泉水两种水样加标实验表明本方法能够用于实际水样中Hg2+的检测。

  6. Gold recovery from low concentrations using nanoporous silica adsorbent

    Science.gov (United States)

    Aledresse, Adil

    The development of high capacity adsorbents with uniform porosity denoted 5%MP-HMS (5% Mercaptopropyl-Hexagonal Mesoporous Structure) to extract gold from noncyanide solutions is presented. The preliminary studies from laboratory simulated noncyanide gold solutions show that the adsorption capacities of these materials are among the highest reported. The high adsorption saturation level of these materials, up to 1.9 mmol/g (37% of the adsorbent weight) from gold chloride solutions (potassium tetrachloroaurate) and 2.9 mmol/g (57% of the adsorbent weight) from gold bromide solutions (potassium tetrabromoaurate) at pH = 2, is a noteworthy feature of these materials. This gold loading from [AuC4]- and [AuBr4 ]- solutions corresponds to a relative Au:S molar ratio of 2.5:1 and 3.8:1, respectively. These rates are significantly higher than the usual 1:1 (Au:S) ratio expected for metal ion binding with the material. The additional gold ions loaded have been spontaneously reduced to metallic gold in the mesoporous material. Experimental studies indicated high maximum adsorptions of gold as high as 99.9% recovery. Another promising attribute of these materials is their favourable adsorption kinetics. The MP-HMS reaches equilibrium (saturation) in less than 1 minute of exposure in gold bromide and less than 10 minutes in gold chloride. The MP-HMS materials adsorption is significantly improved by agitation and the adsorption capacity of Au (III) ions increases with the decrease in pH. The recovery of adsorbed gold and the regeneration of spent adsorbent were investigated for MP-HMS adsorbent. The regenerated adsorbent (MP-HMS) maintained its adsorption capacity even after repeated use and all the gold was successfully recovered from the spent adsorbent. For the fist time, a promising adsorbent system has been found that is capable of effectively concentrating gold thiosulphate complexes, whereas conventional carbon-inpulp (CIP) and carbon-in-leach (CIL) systems fail. The

  7. Gold in the Books

    Institute of Scientific and Technical Information of China (English)

    江河

    2002-01-01

    In the present Chinese market, more and more businessmen turn to the profit-making trade. Even some counters in the bookstores are selling gold rings, necklaces, bracelets, etc. One day a school teacher asked a store assistant,“Why are you selling gold in your bookstore?”

  8. Gold in psoriatic arthopathy.

    OpenAIRE

    Richter, M B; Kinsella, P; Corbett, M

    1980-01-01

    It has been suggested that gold is not effective in psoriatic arthropathy. We did not agree and therefore did a retrospective study of 98 patients. Gold had been given to 27 and was effective in 22, 14 of whom are still receiving it. The incidence of side effects was low and comparable to those in rheumatoid arthritis.

  9. Optical Properties of Linoleic Acid Protected Gold Nanoparticles

    OpenAIRE

    Ratan Das; Nath, Siddartha S.; Ramendu Bhattacharjee

    2011-01-01

    Linoleic acid-protected gold nanoparticles have been synthesized through the chemical reduction of tetrachloroaurate ions by ethanol in presence of sodium linoleate. The structure of these nanoparticles is investigated using transmission electron microscopy, which shows that the Au nanoparticles are spherical in shape with a narrow size distribution which ranges from 8 to 15 nm. Colloidal dispersion of gold nanoparticles in cyclohexane exhibits absorption bands in the ultraviolet-visible ran...

  10. Optical Properties of Linoleic Acid Protected Gold Nanoparticles

    OpenAIRE

    Das, Ratan; Nath, Siddartha S.; Bhattacharjee, Ramendu

    2011-01-01

    Linoleic acid-protected gold nanoparticles have been synthesized through the chemical reduction of tetrachloroaurate ions by ethanol in presence of sodium linoleate. The structure of these nanoparticles is investigated using transmission electron microscopy, which shows that the Au nanoparticles are spherical in shape with a narrow size distribution which ranges from 8 to 15 nm. Colloidal dispersion of gold nanoparticles in cyclohexane exhibits absorption bands in the ultraviolet-visible rang...

  11. Investigating the toxicity, uptake, nanoparticle formation and genetic response of plants to gold.

    Directory of Open Access Journals (Sweden)

    Andrew F Taylor

    Full Text Available We have studied the physiological and genetic responses of Arabidopsis thaliana L. (Arabidopsis to gold. The root lengths of Arabidopsis seedlings grown on nutrient agar plates containing 100 mg/L gold were reduced by 75%. Oxidized gold was subsequently found in roots and shoots of these plants, but gold nanoparticles (reduced gold were only observed in the root tissues. We used a microarray-based study to monitor the expression of candidate genes involved in metal uptake and transport in Arabidopsis upon gold exposure. There was up-regulation of genes involved in plant stress response such as glutathione transferases, cytochromes P450, glucosyl transferases and peroxidases. In parallel, our data show the significant down-regulation of a discreet number of genes encoding proteins involved in the transport of copper, cadmium, iron and nickel ions, along with aquaporins, which bind to gold. We used Medicago sativa L. (alfalfa to study nanoparticle uptake from hydroponic culture using ionic gold as a non-nanoparticle control and concluded that nanoparticles between 5 and 100 nm in diameter are not directly accumulated by plants. Gold nanoparticles were only observed in plants exposed to ionic gold in solution. Together, we believe our results imply that gold is taken up by the plant predominantly as an ionic form, and that plants respond to gold exposure by up-regulating genes for plant stress and down-regulating specific metal transporters to reduce gold uptake.

  12. Extracellular mycosynthesis of gold nanoparticles using Fusarium solani

    Science.gov (United States)

    Gopinath, K.; Arumugam, A.

    2014-08-01

    The development of eco-friendly methods for the synthesis of nanomaterial shape and size is an important area of research in the field of nanotechnology. The present investigation deals with the extracellular rapid biosynthesis of gold nanoparticles using Fusarium solani culture filtrate. The UV-vis spectra of the fungal culture filtrate medium containing gold ion showed peak at 527 nm corresponding to the plasmon absorbance of gold nanoparticles. FTIR spectra provide an evidence for the presence of heterocyclic compound in the culture filtrate, which increases the stability of the synthesized gold nanoparticles. The X-ray analysis respects the Bragg's law and confirmed the crystalline nature of the gold nanoparticles. AFM analysis showed the results of particle sizes (41 nm). Transmission electron microscopy (TEM) showed that the gold nanoparticles are spherical in shape with the size range from 20 to 50 nm. The use of F. solani will offer several advantages since it is considered as a non-human pathogenic organism. The fungus F. solani has a fast growth rate, rapid capacity of metallic ions reduction, NPs stabilization and facile and economical biomass handling. Extracellular biosynthesis of gold nanoparticles could be highly advantageous from the point of view of synthesis in large quantities, time consumption, eco-friendly, non-toxic and easy downstream processing.

  13. Hunan Gold Corporation Visiting South America to Develop Gold Resources

    Institute of Scientific and Technical Information of China (English)

    2013-01-01

    <正>On November 2nd,Hunan Gold Corporation signed a cooperation agreement to collaboratively exploit gold resources in South America.Gold Corporation has made its first"Step Out",initiating its overseas landscape layout of resources.Gold Corporation is a leading enterprise of nonferrous metals in Hunan Province,the

  14. 16 CFR Appendix to Part 23 - Exemptions Recognized in the Assay for Quality of Gold Alloy, Gold Filled, Gold Overlay, Rolled...

    Science.gov (United States)

    2010-01-01

    ... Quality of Gold Alloy, Gold Filled, Gold Overlay, Rolled Gold Plate, Silver, and Platinum Industry...—Exemptions Recognized in the Assay for Quality of Gold Alloy, Gold Filled, Gold Overlay, Rolled Gold Plate... be considered in any assay for quality of a gold filled, gold overlay and rolled gold plate...

  15. Gold Spiky Nanodumbbells: Anisotropy in Gold Nanostars

    OpenAIRE

    Novikov, Sergey M.; Sánchez-Iglesias, Ana; Schmidt, Mikołaj K.; Chuvilin, Andrey; Aizpurua, Javier; Grzelczak, Marek; Liz-Marzán, Luis M.

    2013-01-01

    A new type of gold nanoparticle—called “spiky nanodumbbells”—is introduced. These particles combine the anisotropy of nanorods with sharp nanoscale features of nanostars, which are important for SERS applications. Both the morphology and the optical response of the particles are characterized in detail, and the experimental results are compared with FDTD simulations, showing good agreement.

  16. 铜(Ⅰ)离子对氰化物溶液中金属离子存在形态的影响%Effect of Copper ( I ) on Existence Form of Gold, Silver and Other Metal Ions in Cyanide Solution

    Institute of Scientific and Technical Information of China (English)

    郑大录; 张廷安; 金创石; 赵洪亮

    2012-01-01

    提出了可以描述在各种金属离子浓度和不同的pH条件下,随铜盐添加量的增加,氰化物溶液中金属离子和CN-存在形态的公式.基于其计算结果,探讨了将铜盐加入含金银的氰化物溶液中时金银的沉淀机理,以及在矿石中铜含量较高时氰化物消耗量增加而金银浸出率降低的原因.将铜盐加入氰化物溶液中时,铜(Ⅰ)离子首先与溶液中游离CN-反应,然后从锌、镉、镍等金属的氰根配合物中"劫持"几乎全部的CN-,以CuCN形式生成沉淀,金银的氰根配合物被"劫持"CN-,以AuCN和AgCN型沉淀物沉淀.%A formula was proposed to describe the existence form of metal and CN- ions in cyanide solution with various copper additions, metal ion concentrations and pH values. Based on the calculation results, the precipitation mechanisms of gold and silver were investigated when copper is added into cyanide solution containing gold and silver, and the causation was also discussed for that the cyanide consumption increased and the leaching rates of gold and silver decreased in condition of high copper content in the ore. When added into cyanide solution, the copper first reacted with free ions of cyanide and then "robbed" almost all of the CN- from cyanide complexes of zinc, cadmium and nickel. CN- was precipitated simultaneously as CuCN. The gold and silver complexes were "robbed" of CN- and precipitated as AuCN and AgCN, resDectivelv.

  17. Gold und Peanuts

    OpenAIRE

    Hashmi, Stephen

    2003-01-01

    Die bisherigen Kenntnisse zur Gold-Katalyse lassen sich wie folgt zusammenfassen: 1. Gold-Katalysatoren reagieren rasch mit Kohlenstoff-Kohlenstoff-Mehrfachbindungen und sind somit besonders für einen Einsatz in der Organischen Chemie,der Chemie des Kohlenstoffs, geeignet. Dies lässt sich damit erklären, dass Gold und Kohlenstoff gemäß des Prinzips der harten und weichen Säuren und Basen („hard and soft acids and bases“, HSABPrinzip)beide als „weich“ klassifiziert werden und dieses Prinzi...

  18. Two gold return puzzles

    OpenAIRE

    Kolev, Gueorgui I.

    2013-01-01

    Since the dismantling of the Bretton Woods system, gold has delivered average return comparable to the average return delivered by the aggregate US stock market. This suggests that none of the growth and technological improvement gains accrued to the financiers. In the context of modern asset pricing models, say the CAPM model or the Fama-French three factor model, gold is a risk free asset, as it has no covariation with the risk factors. The large average gold return is a Jensen's alpha not ...

  19. Gold emissivities for hydrocode applications

    Science.gov (United States)

    Bowen, C.; Wagon, F.; Galmiche, D.; Loiseau, P.; Dattolo, E.; Babonneau, D.

    2004-10-01

    The Radiom model [M. Busquet, Phys Fluids B 5, 4191 (1993)] is designed to provide a radiative-hydrodynamic code with non-local thermodynamic equilibrium (non-LTE) data efficiently by using LTE tables. Comparison with benchmark data [M. Klapisch and A. Bar-Shalom, J. Quant. Spectrosc. Radiat. Transf. 58, 687 (1997)] has shown Radiom to be inaccurate far from LTE and for heavy ions. In particular, the emissivity was found to be strongly underestimated. A recent algorithm, Gondor [C. Bowen and P. Kaiser, J. Quant. Spectrosc. Radiat. Transf. 81, 85 (2003)], was introduced to improve the gold non-LTE ionization and corresponding opacity. It relies on fitting the collisional ionization rate to reproduce benchmark data given by the Averroès superconfiguration code [O. Peyrusse, J. Phys. B 33, 4303 (2000)]. Gondor is extended here to gold emissivity calculations, with two simple modifications of the two-level atom line source function used by Radiom: (a) a larger collisional excitation rate and (b) the addition of a Planckian source term, fitted to spectrally integrated Averroès emissivity data. This approach improves the agreement between experiments and hydrodynamic simulations.

  20. Gold emissivities for hydrocode applications

    International Nuclear Information System (INIS)

    The Radiom model [M. Busquet, Phys Fluids B 5, 4191 (1993)] is designed to provide a radiative-hydrodynamic code with non-local thermodynamic equilibrium (non-LTE) data efficiently by using LTE tables. Comparison with benchmark data [M. Klapisch and A. Bar-Shalom, J. Quant. Spectrosc. Radiat. Transf. 58, 687 (1997)] has shown Radiom to be inaccurate far from LTE and for heavy ions. In particular, the emissivity was found to be strongly underestimated. A recent algorithm, Gondor [C. Bowen and P. Kaiser, J. Quant. Spectrosc. Radiat. Transf. 81, 85 (2003)], was introduced to improve the gold non-LTE ionization and corresponding opacity. It relies on fitting the collisional ionization rate to reproduce benchmark data given by the Averroes superconfiguration code [O. Peyrusse, J. Phys. B 33, 4303 (2000)]. Gondor is extended here to gold emissivity calculations, with two simple modifications of the two-level atom line source function used by Radiom: (a) a larger collisional excitation rate and (b) the addition of a Planckian source term, fitted to spectrally integrated Averroes emissivity data. This approach improves the agreement between experiments and hydrodynamic simulations

  1. Chiseled Gold Ornament

    Institute of Scientific and Technical Information of China (English)

    1998-01-01

    According to some archaeological discoveries, people began to use gold to make ornaments during the Shang Dynasty, more than 3,000 years ago. This partfcular piece of chiseled gold ornament was unearthed in 1957 from the Ming Dynasty tomb of Wang Gui at You’anmen, Beijing. Wang Gui was a head of the Imperial Bodyguard in the Ming Dynasty. His eldest daughter was an imperial concubine of the Emperor Cheng Hua. Consequently, his family held a prominent position at the time. The gold ornament, 50.5 centimeters in length and 295 grams in weight, is composed of two parts. The upper part is shaped like lotus leaves, with fine double lines as the vein. To indicate auspiciousness, a pair of mandarin ducks with lotus flowers in their months sit on either side of the thick leaves. Seven long gold chains measuring 21 centimeters in length link the

  2. Paying twice for Gold

    OpenAIRE

    Ayris, P.

    2014-01-01

    EU governments seem to prefer gold in the debate on Open Access. The problem with ‘gold’ is that often subscription fees for universities persist while authors now pay too. The League of European Research Universities raises critical questions.

  3. Electrolytic refining of gold

    OpenAIRE

    Wohlwill, Emil

    2008-01-01

    At the request of the editor of ELECTROCHEMICAL INDUSTRY, I herewith give some notes on the electrolytic method of gold refining, to supplement the article of Dr. Tuttle (Vol. I, page 157, January, 1903).

  4. The Gold Standard Programme

    DEFF Research Database (Denmark)

    Neumann, Tim; Rasmussen, Mette; Ghith, Nermin;

    2013-01-01

    To evaluate the real-life effect of an evidence-based Gold Standard Programme (GSP) for smoking cessation interventions in disadvantaged patients and to identify modifiable factors that consistently produce the highest abstinence rates.......To evaluate the real-life effect of an evidence-based Gold Standard Programme (GSP) for smoking cessation interventions in disadvantaged patients and to identify modifiable factors that consistently produce the highest abstinence rates....

  5. Joining the Gold Rush

    Institute of Scientific and Technical Information of China (English)

    LIU BO

    2006-01-01

    @@ Flush with advanced technology and large amounts of capital, overseas mining firms are carving a place in the Chinese gold industry Dozens of Western mining companies, particularly those from Canada, are making the journey into the kind of remote corners in China that other overseas investors shy away from. What are they looking for? The answer is one of the most precious substances on the planet: gold.

  6. Gold induced enterocolitis.

    OpenAIRE

    Jackson, C W; Haboubi, N Y; Whorwell, P.J.; Schofield, P. F.

    1986-01-01

    A case of gold associated enterocolitis is described. A review of all 27 previously reported cases revealed that the syndrome induced has common characteristics. The reaction occurs within three months of instituting gold therapy, is characterised by profuse diarrhoea and vomiting with abdominal pain, fever, and sometimes eosinophilia. Petechial changes are prominent on endoscopy and the endoscopic and histological features of the gut lesion do not resemble inflammatory bowel disease. The ove...

  7. Gold prices and inflation

    OpenAIRE

    Tkacz, Greg

    2007-01-01

    Using data for 14 countries over the 1994 to 2005 period, we assess the leading indicator properties of gold at horizons ranging from 6 to 24 months. We find that gold contains significant information for future inflation for several countries, especially for those that have adopted formal inflation targets. This finding may arise from the manner in which inflation expectations are formed in these countries, which may result in more rapidly mean-reverting inflation rates. Compared to other in...

  8. Gold or Penicillamine?

    OpenAIRE

    Offer, R. C.

    1981-01-01

    The recent approval of penicillamine (Cupramine) for use in rheumatoid arthritis has given the physician another remission-inducing drug for this disease. A thorough understanding of penicillamine's administration and toxicity is necessary before the physician begins to use it. Although its efficacy is similar to gold, side effects are considerably more diverse, and longterm side effects require further assessment. This article reviews the clinical use of gold and penicillamine and the factor...

  9. SYNTHESIS AND CHARACTERIZATION OF GOLD NANOPARTICLES BY JUSTICIA GENDARUSSA BURM F. LEAF EXTRACT

    OpenAIRE

    Ponnuswamy Renuka Devi et al.

    2012-01-01

    The unusual physio and chemical properties of gold nanoparticles are found to have more advantage in the field of medicine, diagnostics and biosensors. In the present document, it is reported that Justicia gendarussa leaf extract mediated synthesis of gold nanoparticles by the reduction of gold ions. Three different phytochemical fractions were prepared from methanolic leaf extract by liquid-liquid extraction method using immiscible solvents. The total polyphenols, flavonoids and electron d...

  10. Biosynthesis of gold nanoparticles using diatoms-silica-gold and EPS-gold bionanocomposite formation

    OpenAIRE

    Schröfel, Adam; Kratošová, Gabriela; Bohunická, Markéta; Dobročka, Edmund; Vávra, Ivo

    2011-01-01

    Novel synthesis of gold nanoparticles, EPS-gold, and silica-gold bionanocomposites by biologically driven processes employing two diatom strains (Navicula atomus, Diadesmis gallica) is described. Transmission electron microscopy (TEM) and electron diffraction analysis (SAED) revealed a presence of gold nanoparticles in the experimental solutions of the diatom culture mixed with tetrachloroaureate. Nature of the gold nanoparticles was confirmed by X-ray diffraction studies. Scanning electron m...

  11. Facile synthesis of gold nanoribbons by L-cysteine at room temperature

    Institute of Scientific and Technical Information of China (English)

    HUANG Lan; ZHANG Yu; GUO ZhiRui; GU Ning

    2009-01-01

    Highly crystalline gold nanoribbons have been synthesized via a simple method by L-cysteine reduc-tion of aqueous chloroaurate ions at room temperature, without additional capping agent or surfactant. Based on transmission electron microscopy (TEM) and UV-vis absorption studies for the intermediate products, the formation of gold nanoribbons is regarded as a kind of oriented attachment growth.

  12. Quantitative detection of DNA by autocatalytic enlargement of hybridized gold nanoprobes

    DEFF Research Database (Denmark)

    Zhan, Zongrui; Cao, Cuong; Sim, Sang Jun

    2010-01-01

    and explained for the selection of analytical parameters. To achieve high sensitivity, magnetic particles conjugated with capture probes (PMPs) were employed for the collection of gold nanoprobes. After denaturated by ion a pH 11 solution, the amplified signals of gold nanoprobes, which is proportional...

  13. Poly-thiosemicarbazide membrane for gold recovery

    KAUST Repository

    Villalobos, Luis Francisco

    2014-11-01

    A novel polymeric membrane adsorber with a high density of adsorption sites that can selectively capture Au(III) ions, is proposed as an efficient alternative to recover gold from dilute solutions. Poly-thiosemicarbazide (PTSC), a polymer that contains one chelate site per monomeric unit, was used to fabricate the membranes. This polymer can be easily processed into membranes by a phase inversion technique, resulting in an open and interconnected porous structure suitable for high flux liquid phase applications. This method overcomes the usual low capacities of membrane adsorbents by selecting a starting material that contains the adsorption sites within it, therefore avoiding the necessity to add an external agent into the membrane matrix. The resulting mechanically stable PTSC membranes can operate in a pressure driven permeation process, which eliminates the diffusion limitations commonly present in packed column adsorption processes. This process can selectively recover 97% of the gold present in a solution containing a 9-fold higher copper concentration, while operating at a flux as high as 1868 L/m2 h. The maximum gold uptake measured without sacrificing the mechanical stability of the membrane was 5.4 mmol Au/g. Furthermore the gold can be easily eluted from the membrane with a 0.1 M thiourea solution and the membrane can be reused for at least three cycles without any decrease in its performance. Finally, the ability of this membrane for recovering metals from real-life samples, like seawater and tap water, was tested with promising results.

  14. Plasmonic Gold Decorated MWCNT Nanocomposite for Localized Plasmon Resonance Sensing

    Science.gov (United States)

    Ozhikandathil, J.; Badilescu, S.; Packirisamy, M.

    2015-08-01

    The synergism of excellent properties of carbon nanotubes and gold nanoparticles is used in this work for bio-sensing of recombinant bovine growth hormones (rbST) by making Multi Wall Carbon Nanotubes (MWCNT) locally optically responsive by augmenting it optical properties through Localized Surface Plasmon Resonance (LSPR). To this purpose, locally gold nano particles decorated gold-MWCNT composite was synthesized from a suspension of MWCNT bundles and hydrogen chloroauric acid in an aqueous solution, activated ultrasonically and, then, drop-casted on a glass substrate. The slow drying of the drop produces a “coffee ring” pattern that is found to contain gold-MWCNT nanocomposites, accumulated mostly along the perimeter of the ring. The reaction is studied also at low-temperature, in the vacuum chamber of the Scanning Electron Microscope and is accounted for by the local melting processes that facilitate the contact between the bundle of tubes and the gold ions. Biosensing applications of the gold-MWCNT nanocomposite using their LSPR properties are demonstrated for the plasmonic detection of traces of bovine growth hormone. The sensitivity of the hybrid platform which is found to be 1 ng/ml is much better than that measuring with gold nanoparticles alone which is only 25 ng/ml.

  15. An electrochemical metalloimmunoassay based on a colloidal gold label.

    Science.gov (United States)

    Dequaire, M; Degrand, C; Limoges, B

    2000-11-15

    A novel, sensitive electrochemical immunoassay has been developed using a colloidal gold label that, after oxidative gold metal dissolution in an acidic solution, was indirectly determined by anodic stripping voltammetry (ASV) at a single-use carbon-based screen-printed electrode (SPE). The use of disposable electrodes allows for simplified measurement in 35 microL of solution. The method was evaluated for a noncompetitive heterogeneous immunoassay of an immunoglobulin G (IgG) and a concentration as low as 3 x 10(-12) M was determined, which is competitive with colorimetric ELISA or with immunoassays based on fluorescent europium chelate labels. The high performance of the method is related to the sensitive ASV determination of gold(III) at a SPE (detection limit of 5 x 10(-9) M) and to the release of a large number of gold(III) ions from each gold particle anchored on the immunocomplex (e.g., 1.7 x 10(5) gold atoms are theoretically contained in a 18-nm spherical gold particle). PMID:11101226

  16. The Physico—Chemical Conditions for Mobilization of Gold in Mobin Gold Deposit,Southwest Hunan,China

    Institute of Scientific and Technical Information of China (English)

    谷俐; 杨华; 等

    2002-01-01

    Experiments on water-rock interaction were carried out on wall-rock samples fromtheMobin gold deposit,Southwest Hunan,China ,with the aim of determining the optimum physical and chemical conditions for the mobilization of gold in solution.Results indicate that gold is most easily mobilized from the wall rock-tuffaceous slate of the Mobin Deposit.Mobi-lization is optimized if fluids are neutral to slightly alkaline and contain both chlorine and sul-phur ions at the concentration and composition of about[0.25M(NH4)2+1M NaCl].The amount of gold leached from the tuffaceous slate increases with temperature although the effect decreases above about 200℃.

  17. Exciting first results from deuteron-gold collisions at Brookhaven

    CERN Multimedia

    2003-01-01

    "The latest results from the Relativistic Heavy Ion Collider, the world's most powerful facility for nuclear physics research, strengthen scientists' confidence that RHIC collisions of gold ions have created unusual conditions and that they are on the right path to discover a form of matter called the quark-gluon plasma, believed to have existed in the first microseconds after the birth of the universe" (1 page).

  18. RHIC heavy ion operations performance

    CERN Document Server

    Satogata, T; Ferrone, R; Pilat, F

    2006-01-01

    The Relativistic Heavy Ion Collider (RHIC) completed its fifth year of operation in 2005, colliding copper ion beams with ps=200 GeV/u and 62.4 GeV/u[1]. Previous heavy ion runs have collided gold ions at ps=130 GeV/u, 200 GeV/u, and 62.4 GeV/u[2], and deuterons and gold ions at ps=200 GeV/u[3]. This paper discusses operational performance statistics of this facility, including Cu- Cu delivered luminosity, availability, calendar time spent in physics stores, and time between physics stores. We summarize the major factors affecting operations efficiency, and characterize machine activities between physics stores.

  19. Electroless selective deposition of gold nano-array for silicon nanowires growth

    Directory of Open Access Journals (Sweden)

    Ruiz-Gomes E.

    2014-01-01

    Full Text Available Nanopatterns of gold clusters on a large surface of oriented Si(111 substrates, from the galvanic displacement of gold salt (via the spontaneous reduction of AuCl4 -, are demonstrated in this work. The Si substrate is patterned by Focused Ion Beam (FIB prior to being dipped in a gold solution. Here, we show that these patterns lead to successful control of the position and size of gold clusters. Sequential patterning reveals a powerful maskless alternative to surface preparation prior to Si nanowire growth

  20. GOLD CLUSTER LABELS AND RELATED TECHNOLOGIES IN MOLECULAR MORPHOLOGY.

    Energy Technology Data Exchange (ETDEWEB)

    HAINFELD,J.F.; POWELL,R.D.

    2004-02-04

    Although intensely colored, even the largest colloidal gold particles are not, on their own, sufficiently colored for routine use as a light microscopy stain: only with very abundant antigens or with specialized illumination methods can bound gold be seen. Colloidal gold probes were developed primarily as markers for electron microscopy, for which their very high electron density and selectivity for narrow size distributions when prepared in different ways rendered them highly suited. The widespread use of gold labeling for light microscopy was made possible by the introduction of autometallographic enhancement methods. In these processes, the bound gold particles are exposed to a solution containing metal ions and a reducing agent; they catalyze the reduction of the ions, resulting in the deposition of additional metal selectively onto the particles. On the molecular level, the gold particles are enlarged up to 30-100 nm in diameter; on the macroscale level, this results in the formation of a dark stain in regions containing bound gold particles, greatly increasing visibility and contrast. The applications of colloidal gold have been described elsewhere in this chapter, we will focus on the use of covalently linked cluster complexes of gold and other metals. A gold cluster complex is a discrete molecular coordination compound comprising a central core, or ''cluster'' of electron-dense metal atoms, ligated by a shell of small organic molecules (ligands), which are linked to the metal atoms on the surface of the core. This structure gives clusters several important advantages as labels. The capping of the metal surface by ligands prevents non-specific binding to cell and tissue components, which can occur with colloidal gold. Cluster compounds are more stable and may be used under a wider range of conditions. Unlike colloidal gold, clusters do not require additional macromolecules such as bovine serum albumin or polyethylene glycol for

  1. Charged Hadron Distributions In 19.6-gev Gold+gold Collisions

    CERN Document Server

    Picha, R

    2005-01-01

    Experimental results from a low-energy heavy ion run in year 2001 at the Relativistic Heavy Ion Collider (RHIC) using the Solenoidal Tracker at RHIC (STAR) detector are presented. From the collisions of gold ions at sNN = 19.6 GeV, six species of particles (π±, K±, p, and p¯) are identified via energy loss mechanism and their transverse mass spectra are analyzed at midrapidity (|y| < 0.5) and m T − m0 < 1.0 GeV/c 2. Rapidity distributions, particle ratios, and hadronic freeze-out conditions are discussed. This study provides a low energy measurement at RHIC which is very close to that at the SPS for cross comparison between collider experiments and fixed target experiments. The analysis provides a good reference to study excitation functions of strangeness production, net baryon, and collective flow inside heavy ion collisions.

  2. Nanocomposite gold-silk nanofibers

    OpenAIRE

    Cohen-Karni, Tzahi; Jeong, Kyung Jae; Tsui, Jonathan H.; Reznor, Gally; Mustata, Mirela; Wanunu, Meni; Graham, Adam; Marks, Carolyn; Bell, David C.; Langer, Robert S; Kohane, Daniel S.

    2012-01-01

    Cell-biomaterial interactions can be controlled by modifying the surface chemistry or nanotopography of the material, to induce cell proliferation and differentiation if desired. Here we combine both approaches in forming silk nanofibers (SNFs) containing gold nanoparticles (AuNPs) and subsequently chemically modifying the fibers. Silk fibroin mixed with gold seed nanoparticles was electrospun to form SNFs doped with gold seed nanoparticles (SNFseed). Following gold reduction, there was a two...

  3. ['Gold standard', not 'golden standard'

    NARCIS (Netherlands)

    Claassen, J.A.H.R.

    2005-01-01

    In medical literature, both 'gold standard' and 'golden standard' are employed to describe a reference test used for comparison with a novel method. The term 'gold standard' in its current sense in medical research was coined by Rudd in 1979, in reference to the monetary gold standard. In the same w

  4. Gold extraction from flotation tailings

    International Nuclear Information System (INIS)

    The results of studies on cyanide leaching of gold comprising flotation tailings of antimony ore are given. The possibility to extract 50% of gold by cyanide leaching is shown. The dependence of gold extraction on leaching duration is studied. Influence of kerosine on cyanide leaching of flotation tailings is studied as well.

  5. Chemically functionalized gold nanoparticles: Synthesis, characterization, and applications

    Science.gov (United States)

    Daniel, Weston Lewis

    This thesis focuses on the development and application of gold nanoparticle based detection systems and biomimetic structures. Each class of modified nanoparticle has properties that are defined by its chemical moieties that interface with solution and the gold nanoparticle core. In Chapter 2, a comparison of the biomolecular composition and binding properties of various preparations of antibody oligonucleotide gold nanoparticle conjugates is presented. These constructs differed significantly in terms of their structure and binding properties. Chapter 3 reports the use of electroless gold deposition as a light scattering signal enhancer in a multiplexed, microarray-based scanometric immunoassay using the gold nanoparticle probes evaluated in Chapter 2. The use of gold development results in greater signal enhancement than the typical silver development, and multiple rounds of metal development were found to increase the resulting signal compared to one development. Chapter 4 describes an amplified scanometric detection method for human telomerase activity. Gold nanoparticles functionalized with specific oligonucleotide sequences can efficiently capture telomerase enzymes and subsequently be elongated. Both the elongated and unmodified oligonucleotide sequences are simultaneously measured. At low telomerase concentrations, elongated strands cannot be detected, but the unmodified sequences, which come from the same probe particles, can be detected because their concentration is higher, providing a novel form of amplification. Chapter 5 reports the development of a novel colorimetric nitrite and nitrate ion assay based upon gold nanoparticle probes functionalized with Griess reaction reagents. This assay takes advantage of the distance-dependent plasmonic properties of the gold nanoparticles and the ability of nitrite ion to facilitate the cross coupling of novel nanoparticle probes. The assay works on the concept of a kinetic end point and can be triggered at the EPA

  6. ADSORPTION CAPACITY OF ACTIVATED CARBON FIBER FABRIC IN CYANIDE LEACHING LIQUOR OF GOLD ORES

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Adsorption capacity of ACFF in cyanide leaching liquor of gold ores was studied withcyanide leaching liquor of gold ores, containing various kinds of ions. The adsorbed leaching liquorwas analyzed by atomic emission spectroscopy and colorimetric method. The contents of variouskinds of ions in ACFF were determined with X-ray photoctron spectroscopy. ACFF not onlyadsorbed gold but also adsorbed arsenic, nickel, zinc, calcium, sulphur, bismuth, copper, iron. silverand cyanide anion. Atomic percentage of C and those of O, N, Zr, Fe increase and decreaserespectively with the increase of the layer depth, while those of Ca, Au, Ag keep constant.

  7. Aiming for Gold

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Twenty-three years ago he claimed China’s first Olympic gold medal,with a win in the 50-meter pistol shooting competition.Now Xu Haifeng is leading the country’s modern pentathlon team in its bid for success at the Beijing Games

  8. Turning lead into gold

    DEFF Research Database (Denmark)

    Jensen, Steffen Moltrup Ernø

    For years the field of entrepreneurship has been blinded by the alchemical promise of turning lead into gold, of finding the ones most likely to become the next Branson, Zuckerberg or Gates. The promise has been created in the midst of political and scientific agendas where certain individuals...

  9. Gold Nanoparticle Microwave Synthesis

    Energy Technology Data Exchange (ETDEWEB)

    Krantz, Kelsie E. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Christian, Jonathan H. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Coopersmith, Kaitlin [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Washington, II, Aaron L. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Murph, Simona H. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

    2016-07-27

    At the nanometer scale, numerous compounds display different properties than those found in bulk material that can prove useful in areas such as medicinal chemistry. Gold nanoparticles, for example, display promise in newly developed hyperthermia therapies for cancer treatment. Currently, gold nanoparticle synthesis is performed via the hot injection technique which has large variability in final particle size and a longer reaction time. One underdeveloped area by which these particles could be produced is through microwave synthesis. To initiate heating, microwaves agitate polar molecules creating a vibration that gives off the heat energy needed. Previous studies have used microwaves for gold nanoparticle synthesis; however polar solvents were used that partially absorbed incident microwaves, leading to partial thermal heating of the sample rather than taking full advantage of the microwave to solely heat the gold nanoparticle precursors in a non-polar solution. Through this project, microwaves were utilized as the sole heat source, and non-polar solvents were used to explore the effects of microwave heating only as pertains to the precursor material. Our findings show that the use of non-polar solvents allows for more rapid heating as compared to polar solvents, a reduction in reaction time from 10 minutes to 1 minute, maximizes the efficiency of the reaction, and allows for reproducibility in the size/shape of the fabricated nanoparticles.

  10. Gold Nanoslit Lenses

    OpenAIRE

    Ishii, Satoshi; Kildishev, Alexander V.; Shalaev, Vladimir M.; Chen, Kuo-Ping; Drachev, Vladimir P.

    2011-01-01

    We experimentally demonstrate the focusing properties of arrays of parallel subwavelength-wide nanoslits in a gold film. The lenses are designed to focus either TM- or TE-polarized light and diverge the light of the orthogonal polarization. (C) 2010 Optical Society of America

  11. Gold in Ophiolites

    OpenAIRE

    Castroviejo Bolibar, Ricardo

    2004-01-01

    Ophiolites, as a class, have been currently under-estimated as potential gold targets, although they have been the subject of major scientific research. Their resources have also attracted investors producing Cr, Cu (massive sulphides), Co, Ni (laterites), industrial rocks and minerals (serpentinites, emeralds), etc. They are also potential PGE sources.

  12. Digging for Gold

    Science.gov (United States)

    Waters, John K.

    2012-01-01

    In the case of higher education, the hills are more like mountains of data that "we're accumulating at a ferocious rate," according to Gerry McCartney, CIO of Purdue University (Indiana). "Every higher education institution has this data, but it just sits there like gold in the ground," complains McCartney. Big Data and the new tools people are…

  13. Gold Nanoparticle Microwave Synthesis

    Energy Technology Data Exchange (ETDEWEB)

    Krantz, Kelsie E. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Christian, Jonathan H. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Coopersmith, Kaitlin [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Washington, II, Aaron L. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Murph, Simona H. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

    2016-07-27

    At the nanometer scale, numerous compounds display different properties than those found in bulk material that can prove useful in areas such as medicinal chemistry. Gold nanoparticles, for example, display promise in newly developed hyperthermia therapies for cancer treatment. Currently, gold nanoparticle synthesis is performed via the hot injection technique which has large variability in final particle size and a longer reaction time. One underdeveloped area by which these particles could be produced is through microwave synthesis. To initiate heating, microwaves agitate polar molecules creating a vibration that gives off the heat energy needed. Previous studies have used microwaves for gold nanoparticle synthesis; however, polar solvents were used that partially absorbed incident microwaves, leading to partial thermal heating of the sample rather than taking full advantage of the microwave to solely heat the gold nanoparticle precursors in a non-polar solution. Through this project, microwaves were utilized as the sole heat source, and non-polar solvents were used to explore the effects of microwave heating only as pertains to the precursor material. Our findings show that the use of non-polar solvents allows for more rapid heating as compared to polar solvents, and a reduction in reaction time from 10 minutes to 1 minute; this maximizes the efficiency of the reaction, and allows for reproducibility in the size/shape of the fabricated nanoparticles.

  14. Gold leaching with elemental sulfur in alkaline solutions under oxygen pressure

    Institute of Scientific and Technical Information of China (English)

    方兆珩; 石伟

    2003-01-01

    A gold leaching process by using oxidation products of elemental sulfur in alkaline solutions was pro-posed and investigated. A gold concentrate and a residue from an arsenic refractory gold concentrate by acidic oxida-tion leaching were tested. The residue contains 16.3% elemental sulfur and no more elemental sulfur was added intests. For the concentrate elemental sulfur was added before leaching tests. The leaching ratio of gold depends main-ly on the initial equivalent ratio of elemental sulfur to hydroxyl ions, the consumption of oxygen and the reactiontemperature in the process. Analysis of the experimental results shows that thiosulfate is the majority complexingreagent for gold in the process. Over 90% gold was leached from the residue and 82%-87% from the concentrate byusing this process.

  15. Relationship of polycyclic aromatic sulfur compounds and gold enrichment in the Kupferschiefer from Poland and Germany

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The contents of polycyclic aromatic sulfur compounds (PASCs) in the Kupferschiefer varied from sample to sample. Twenty PASCs were determined in the Kupferschiefer from Poland and Germany. Gold enrichment was only observed in samples with higher PASC contents. At the same time, all the samples with gold enrichment originated from areas close to the redox boundary (the front section of Rote Faule) that was formed by oxidizing brines in contact with the reducing Kupferschiefer. It is proposed that the gold-bearing solutions encountered PASCs in the Kupferschiefer. PASCs could easily displace chloride ions from aurous chloride complexes to form stable gold S-chelates. Subsequent oxidation of these gold organic compounds could destroy the organic components and lead to the formation of metallic gold.

  16. Biosynthesis of anisotropic gold nanoparticles using Maduca longifolia extract and their potential in infrared absorption.

    Science.gov (United States)

    Fayaz, A Mohammed; Girilal, M; Venkatesan, R; Kalaichelvan, P T

    2011-11-01

    Metal nanoparticles, in general, and gold nanoparticles, in particular, are very attractive because of their size- and shape-dependent properties. Biosynthesis of anisotropic gold nanoparticles using aqueous extract of Madhuca longifolia and their potential as IR blockers has been demonstrated. The tyrosine residue was identified as the active functional group for gold ion reduction. These gold nanoparticles were characterized by of UV-Vis spectrophotometer, FTIR, TEM and HrTEM. The presence of proteins was identified by FTIR, SDS-PAGE, UV-Vis and fluorescence spectroscopy. The micrograph revealed the formation of anisotropic gold nanoaprticles. The biologically synthesized gold nanotriangles can be easily coated in the glass windows which are highly efficient in absorbing IR radiations. PMID:21802261

  17. Biosynthesis of anisotropic gold nanoparticles using Maduca longifolia extract and their potential in infrared absorption.

    Science.gov (United States)

    Fayaz, A Mohammed; Girilal, M; Venkatesan, R; Kalaichelvan, P T

    2011-11-01

    Metal nanoparticles, in general, and gold nanoparticles, in particular, are very attractive because of their size- and shape-dependent properties. Biosynthesis of anisotropic gold nanoparticles using aqueous extract of Madhuca longifolia and their potential as IR blockers has been demonstrated. The tyrosine residue was identified as the active functional group for gold ion reduction. These gold nanoparticles were characterized by of UV-Vis spectrophotometer, FTIR, TEM and HrTEM. The presence of proteins was identified by FTIR, SDS-PAGE, UV-Vis and fluorescence spectroscopy. The micrograph revealed the formation of anisotropic gold nanoaprticles. The biologically synthesized gold nanotriangles can be easily coated in the glass windows which are highly efficient in absorbing IR radiations.

  18. Study of chemical processes involved in silver staining of gold nanostructures by Raman scattering

    Science.gov (United States)

    Ji, Xiaohui; Yang, Wensheng

    2016-05-01

    Strong Raman enhancement contributed by ``hot spots'' in directly fused gold dimers offer a selective and sensitive tool for understanding the surface processes involved in the silver staining of gold nanostructures. These processes include the interactions of cations, effects of surface adsorbed Cl- ions, surface replacement of ligands, and reduction of silver ions on the surface of the gold nanocrystals. Results show that in the commonly applied silver staining scheme for gold nanostructures, i.e., the addition of the Raman probe after the deposition of the silver shell, the Raman signals of the probe (p-mercaptobenzoic acid) were weakened greatly, due to the pre-existence of the Cl--Ag+-citrate bridges on the surface of the gold. A new scheme was developed for silver deposition after pre-adsorption of the probe, which achieved a Raman enhancement factor as high as ~5 × 108.Strong Raman enhancement contributed by ``hot spots'' in directly fused gold dimers offer a selective and sensitive tool for understanding the surface processes involved in the silver staining of gold nanostructures. These processes include the interactions of cations, effects of surface adsorbed Cl- ions, surface replacement of ligands, and reduction of silver ions on the surface of the gold nanocrystals. Results show that in the commonly applied silver staining scheme for gold nanostructures, i.e., the addition of the Raman probe after the deposition of the silver shell, the Raman signals of the probe (p-mercaptobenzoic acid) were weakened greatly, due to the pre-existence of the Cl--Ag+-citrate bridges on the surface of the gold. A new scheme was developed for silver deposition after pre-adsorption of the probe, which achieved a Raman enhancement factor as high as ~5 × 108. Electronic supplementary information (ESI) available: Fig. S1-S3. See DOI: 10.1039/c6nr01208f

  19. SYNTHESIS AND CHARACTERIZATION OF GOLD NANOPARTICLES BY JUSTICIA GENDARUSSA BURM F. LEAF EXTRACT

    Directory of Open Access Journals (Sweden)

    Ponnuswamy Renuka Devi et al.

    2012-02-01

    Full Text Available The unusual physio and chemical properties of gold nanoparticles are found to have more advantage in the field of medicine, diagnostics and biosensors. In the present document, it is reported that Justicia gendarussa leaf extract mediated synthesis of gold nanoparticles by the reduction of gold ions. Three different phytochemical fractions were prepared from methanolic leaf extract by liquid-liquid extraction method using immiscible solvents. The total polyphenols, flavonoids and electron donating capacity (DPPH assay of each phytochemical fraction was analyzed. The 1mg/ml of diethyl ether phytochemical fraction produced more gold nanoparticles within 15 minutes when exposed to 10ml of 0.5mM chloroauric acid compared to chloroform and ethyl acetate phytochemical fractions. The structural characteristics of diethyl ether phytochemical fraction synthesized gold nanoparticles were characterized by UV-visible spectroscopy, Dynamic light scattering, Transmission electron microscopy, X-ray diffraction and Fourier transform-infrared spectroscopies. These biosynthesized gold nanoparticles showed surface plasmon resonance band at 536nm in UV-visible spectrum. The size of the gold nanoparticles ranged from 20 to 42nm and 62 to 88nm with spherical, triangle, truncated triangle and hexagonal shapes. From the Fourier transform-infrared spectra of diethyl ether phytochemical fraction and synthesized gold nanoparticles, the possible functional group involved in gold ions reduction and capping of gold nanoparticles were identified. The stability of gold nanoparticles for 5 month period and at different pH range (5-10 was analyzed by observing the changes in surface plasmon resonance of gold nanoparticles. Moreover, the diethyl ether phytochemical fraction showed no cytotoxicity up to 100μg/ml in RAW 264.7 cell line .

  20. Bioleaching of refractory gold ore (Ⅲ)--Fluid leaching Jinya refractory gold concentrate by Thiobacillus ferrooxidans

    Institute of Scientific and Technical Information of China (English)

    闵小波; 柴立元; 陈为亮; 于霞; 张传福; 邝中

    2002-01-01

    A novel fluidized-bed reactor was designed and installed for bioleaching in a semi-continuous way,by which a process for bioleaching-cyanidation of Jinya refractory gold arsenical concentrate was studied.The arsenic extraction rate reaches 82.5% after 4-day batch biooxidation of the concentrate under the optimized condition of pH 2.0,ferric ion concentration 6.5 g/L and pulp concentration 10%.And leached rate of gold in the following cyanidation is over 90%.The parameters of three series fluidized-bed reactors exhibit stability during the semi-continuous bioleaching of the concentrate.Arsenic in the concentrate can be got rid of 91% after 6-day leaching.Even after 4 days,82% of arsenic extraction rate was still obtained.The recovery rates of gold are 92% and 87.5% respectively in cyaniding the above bioleached residues.The results will provide a base for further commercial production of gold development.

  1. Bio-mediated synthesis, characterization and cytotoxicity of gold nanoparticles.

    Science.gov (United States)

    Klekotko, Magdalena; Matczyszyn, Katarzyna; Siednienko, Jakub; Olesiak-Banska, Joanna; Pawlik, Krzysztof; Samoc, Marek

    2015-11-21

    We report here a "green" approach for the synthesis of gold nanoparticles (GNPs) in which the Mentha piperita extract was applied for the bioreduction of chloroauric acid and the stabilization of the formed nanostructures. The obtained GNPs were characterized by UV-Vis absorption spectroscopy and transmission electron microscopy (TEM). The reduction of gold ions with the plant extract leads to the production of nanoparticles with various shapes (spherical, triangular and hexagonal) and sizes (from 10 to 300 nm). The kinetics of the reaction was monitored and various conditions of the synthesis were investigated. As a result, we established protocols optimized towards the synthesis of nanospheres and nanoprisms of gold. The cytotoxic effect of the obtained gold nanoparticles was studied by performing MTT assay, which showed lower cytotoxicity of the biosynthesized GNPs compared to gold nanorods synthesized using the usual seed-mediated growth. The results suggest that the synthesis using plant extracts may be a useful method to produce gold nanostructures for various biological and medical applications. PMID:26456245

  2. Folding induced assembly of polypeptide decorated gold nanoparticles.

    Science.gov (United States)

    Aili, Daniel; Enander, Karin; Rydberg, Johan; Nesterenko, Irina; Björefors, Fredrik; Baltzer, Lars; Liedberg, Bo

    2008-04-30

    Reversible assembly of gold nanoparticles controlled by the homodimerization and folding of an immobilized de novo designed synthetic polypeptide is described. In solution at neutral pH, the polypeptide folds into a helix-loop-helix four-helix bundle in the presence of zinc ions. When immobilized on gold nanoparticles, the addition of zinc ions induces dimerization and folding between peptide monomers located on separate particles, resulting in rapid particle aggregation. The particles can be completely redispersed by removal of the zinc ions from the peptide upon addition of EDTA. Calcium ions, which do not induce folding in solution, have no effect on the stability of the peptide decorated particles. The contribution from folding on particle assembly was further determined utilizing a reference peptide with the same primary sequence but containing both D and L amino acids. Particles functionalized with the reference peptide do not aggregate, as the peptides are unable to fold. The two peptides, linked to the nanoparticle surface via a cysteine residue located in the loop region, form submonolayers on planar gold with comparable properties regarding surface density, orientation, and ability to interact with zinc ions. These results demonstrate that nanoparticle assembly can be induced, controlled, and to some extent tuned, by exploiting specific molecular interactions involved in polypeptide folding. PMID:18380430

  3. The Financial Economics of Gold - a survey

    OpenAIRE

    O'Connor, Fergal; Lucey, Brian; Batten, Jonathan; Baur, Dirk

    2015-01-01

    We review the literature on gold as an investment. We summarize a wide variety of literature. We begin with a review of how the gold markets operate, including the under researched leasing market; we proceed to examine research on physical gold demand and supply, gold mine economics and move onto analyses of gold as an investment. Additional sections provide context on gold market efficiency, the issue of gold market bubbles, gold’s relation to inflation and interest rates, and the very na...

  4. Biosynthesis of gold nanoparticles: A green approach.

    Science.gov (United States)

    Ahmed, Shakeel; Annu; Ikram, Saiqa; Yudha S, Salprima

    2016-08-01

    Nanotechnology is an immensely developing field due to its extensive range of applications in different areas of technology and science. Different types of methods are employed for synthesis of nanoparticles due to their wide applications. The conventional chemical methods have certain limitations with them either in the form of chemical contaminations during their syntheses procedures or in later applications and use of higher energy. During the last decade research have been focussed on developing simple, clean, non-toxic, cost effective and eco-friendly protocols for synthesis of nanoparticles. In order to get this objective, biosynthesis methods have been developed in order to fill this gap. The biosynthesis of nanoparticles is simple, single step, eco-friendly and a green approach. The biochemical processes in biological agents reduce the dissolved metal ions into nano metals. The various biological agents like plant tissues, fungi, bacteria, etc. are used for biosynthesis for metal nanoparticles. In this review article, we summarised recent literature on biosynthesis of gold nanoparticles which have revolutionised technique of synthesis for their applications in different fields. Due to biocompatibility of gold nanoparticles, it has find its applications in biomedical applications. The protocol and mechanism of biosynthesis of gold nanoparticles along with various applications have also been discussed. PMID:27236049

  5. Rushing for gold

    DEFF Research Database (Denmark)

    Jønsson, Jesper Bosse; Bryceson, Deborah Fahy

    2009-01-01

    African rural dwellers have faced depressed economic prospects for several decades. Now, in a number of mineral-rich countries, multiple discoveries of gold and precious stones have attracted large numbers of prospective small-scale miners. While their 'rush' to, and activities within, mining sites...... are increasingly being noted, there is little analysis of miners' mobility patterns and material outcomes. In this article, on the basis of a sample survey and interviews at two gold-mining sites in Tanzania, we probe when and why miners leave one site in favour of another. Our findings indicate that movement...... is often 'rushed' but rarely rash. Whereas movement to the first site may be an adventure, movement to subsequent sites is calculated with knowledge of the many risks entailed. Miners spend considerable time at each site before migrating onwards. Those with the highest site mobility tend to be more...

  6. Gold' 82 - technical sessions

    International Nuclear Information System (INIS)

    Sulphur-isotope studies had been applied by Dr. I. Lambert to a number of deposits in Western Australia and also to certain samples from Vubachickwe and other deposits in Zimbabwe. A study of the sulphur isotopes at the Dickenson Mine, revealed a wide spread of values in the mineralised zones. Metamorphic processes were likely to be significant in the concentration of gold. The iron formations at the Old Jardine Mine had been unfolded by Dr. W.S. Hallager and the pattern of sedimentation was unraveled. A gold-rich zone was separated by a barren gap from the other part of the mineralised zone. Research was also done on the effects of the metamorphic processes, and the ages of mineralisation

  7. Film Ace Takes Gold

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    "Really, I never, never expected to win this," said Chinese director Jia Zhangke on hearing he had taken the top award for his movie Still Life (Sanxia Haoren) at the Venice Film Festival, on September 9. A surprise late entry, Still Life quickly emerged as the favorite and the Gold Lion was again hugged by Chinese. The well-known Chinese director Zhang Yimou won the same award back in 1999, for Not One Less-also a

  8. Multishelled Gold Nanowires

    OpenAIRE

    Bilalbegovic, G.

    1999-01-01

    The current miniaturization of electronic devices raises many questions about the properties of various materials at nanometre-scales. Recent molecular dynamics computer simulations have shown that small finite nanowires of gold exist as multishelled structures of lasting stability. These classical simulations are based on a well-tested embedded atom potential. Molecular dynamics simulation studies of metallic nanowires should help in developing methods for their fabrication, such as electron...

  9. Gold, Oil, and Stocks

    OpenAIRE

    Baruník, Jozef; Kočenda, Evžen; Vácha, Lukáš

    2014-01-01

    We employ a wavelet approach and conduct a time-frequency analysis of dynamic correlations between pairs of key traded assets (gold, oil, and stocks) covering the period from 1987 to 2012. The analysis is performed on both intra-day and daily data. We show that heterogeneity in correlations across a number of investment horizons between pairs of assets is a dominant feature during times of economic downturn and financial turbulence for all three pairs of the assets under research. Heterogenei...

  10. Assemblies of gold icosahedra

    OpenAIRE

    Bilalbegovic, G.

    2004-01-01

    Low-dimensional free-standing aggregates of bare gold clusters are studied by the molecular dynamics simulation. Icosahedra of 55 and 147 atoms are equilibrated at T=300 K. Then, their one- and two-dimensional assemblies are investigated. It is found that icosahedra do not coalescence into large drops, but stable amorphous nanostructures are formed: nanowires for one-dimensional and nanofilms for two-dimensional assemblies. The high-temperature stability of these nanostructures is also invest...

  11. Gold based electro catalysts

    OpenAIRE

    Sivasubramaniam, Prabalini

    2011-01-01

    Gold electrocatalysts have been of growing interest in recent years owing to their reactivity for a variety of important reactions such as the oxygen reduction reaction. This activity has been shown to be dependent on the size of the supported electrocatalyst nanoparticles. In this thesis the effects of Au nanoparticle size are explored for the oxygen reduction, ethanol oxidation and carbon monoxide oxidation reactions (Chapter four). The results show the oxygen reduction and ethanol oxidatio...

  12. Electrocrystallization and characterization of nanostructured gold and gold alloys

    OpenAIRE

    Yevtushenko, Oleksandra

    2007-01-01

    The kinetics of electrocrystallization of nanostructured gold is investigated and the physical proper-ties of nanostructured materials such as thermal stability, surface roughness and hardness are improved. A new stable non-toxic electrolyte for the electrodeposition of gold and gold alloys is presented. Nanoscaling is achieved by pulse techniques. The possibility of controlling the crystallite size depending on physical and chemical process parameters such as pulse duration, current d...

  13. Gold and the Stock Market: 3 Essays on Gold Investments

    OpenAIRE

    Taurasi, Donatella

    2013-01-01

    This thesis gives an overview of the history of gold per se, of gold as an investment good and offers some institutional details about gold and other precious metal markets. The goal of this study is to investigate the role of gold as a store of value and hedge against negative market movements in turbulent times. I investigate gold’s ability to act as a safe haven during periods of financial stress by employing instrumental variable techniques that allow for time varying conditional covarian...

  14. Annealing Effects on the Surface Plasmon of MgO Implanted with Gold

    Science.gov (United States)

    Ueda, A.; Mu, R.; Tung, Y. -S.; Henderson, D. O.; White, C. W.; Zuhr, R. A.; Zhu, Jane G.; Wang, P. W.

    1997-01-01

    Gold ion implantation was carried out with the energy of 1.1 MeV into (100) oriented MgO single crystal. Implanted doses are 1, 3, 6, 10 x 10(exp 16) ions/sq cm. The gold irradiation results in the formation of gold ion implanted layer with a thickness of 0.2 microns and defect formation. In order to form gold colloids from the as-implanted samples, we annealed the gold implanted MgO samples in three kinds of atmospheres: (1)Ar only, (2)H2 and Ar, and (3)O2 and Ar. The annealing over 1200 C enhanced the gold colloid formation which shows surface plasmon resonance band of gold. The surface plasmon bands of samples annealed in three kinds of atmospheres were found to be at 535 nm (Ar only), 524 nm(H2+Ar), and 560 nm (02+Ar), The band positions of surface plasmon can be reversibly changed by an additional annealing.

  15. Synthesis and Characterization of Gold Nanoparticles

    OpenAIRE

    Hedkvist, Olof

    2013-01-01

    This thesis is focused on the synthesis of three different shapes of gold nanoparticles; the gold nanosphere, the gold nanorod and the gold nanocube. These will be synthesized using wet chemistry methods and characterized using UV-Vis- NIR spectroscopy and dynamic light scattering. The results will be used to draw some conclusions as to what factors influence the growth of gold nanoparticles.

  16. Oxygen clamps in gold nanowires

    OpenAIRE

    Novaes, Frederico D.; da Silva, Antonio J. R.; da Silva, E. Z.; Fazzio, A.

    2005-01-01

    We investigate how the insertion of an oxygen atom in an atomically thin gold nanowire can affect its rupture. We find, using ab initio total energy density functional theory calculations, that O atoms when inserted in gold nanowires form not only stable but also very strong bonds, in such a way that they can extract atoms from a stable tip, serving in this way as a clamp that could be used to pull a string of gold atoms.

  17. Green Synthesis of Gold Nanoparticles

    OpenAIRE

    Hamid Reza Ghorbani

    2015-01-01

    There is an increased interest in understanding the toxicity and rational design of gold nanoparticles for biomedical applications in recent years. In this study gold nanoparticles were synthesized using dextrose as a reducing agent. The gold nanoparticles displayed characteristic Surface Plasmon Resonance peak at around 550 nm having a mean particle size of 75±30 nm. In order to identify and analyze nanoparticles, UV–Vis spectroscopy, Scanning electron microscopy (SEM), and dynamic light sca...

  18. 31 CFR 100.4 - Gold coin and gold certificates in general.

    Science.gov (United States)

    2010-07-01

    ... 31 Money and Finance: Treasury 1 2010-07-01 2010-07-01 false Gold coin and gold certificates in... EXCHANGE OF PAPER CURRENCY AND COIN In General § 100.4 Gold coin and gold certificates in general. Gold coins, and gold certificates of the type issued before January 30, 1934, are exchangeable, as...

  19. New Trends in Gold Catalysts

    OpenAIRE

    Leonarda F. Liotta

    2014-01-01

    Gold is an element that has fascinated mankind for millennia. The catalytic properties of gold have been a source of debate, due to its complete chemical inertness when in a bulk form, while it can oxidize CO at temperatures as low as ~200 K when in a nanocrystalline state, as discovered by Haruta in the late 1980s [1]. Since then, extensive activity in both applied and fundamental research on gold has been initiated. The importance of the catalysis by gold represents one of the fasted growin...

  20. Notes on dumping gold beam in the AGS

    Energy Technology Data Exchange (ETDEWEB)

    Gardner, C.J.; Ahrens, L.; Thieberger, P.

    2010-08-01

    Localized losses of gold beam in the AGS during RHIC Run 8 produced vacuum leaks which required the replacement of several vacuum chambers. A review of what happened and why was given by Leif Ahrens at the Run 8 Retreat. The following notes trace the subsequent development of clean dumping of gold beam on the beam dump in the J10 straight. The novel idea of stripping Au77+ ions in order to put them directly into the upstream face of the dump was introduced by Leif Ahrens and developed by all three of us. George Mahler made the actual stripping device and Dave Gassner developed its control. Leif Ahrens successfully commissioned the device with gold beam during Run 10. The reader may find it helpful to first view the figures herein and then refer to the text for details.

  1. Atomically flat single-crystalline gold nanostructures for plasmonic nanocircuitry

    Energy Technology Data Exchange (ETDEWEB)

    Huang, J.S.; Geisler, P.; Bruening, C.; Kern, J.; Prangsma, J.C.; Wu, X.; Feichtner, Thorsten; Ziegler, J.; Weinmann, P.; Kamp, M.; Forchel, A.; Hecht, B. [Wilhelm-Conrad-Roentgen-Center for Complex Material Systems, University of Wuerzburg (Germany); Biagioni, P. [CNISM, Dipartimento di Fisica, Politecnico di Milano (Italy)

    2011-07-01

    Deep subwavelength integration of high-definition plasmonic nano-structures is of key importance for the development of future optical nanocircuitry. So far the experimental realization of proposed extended plasmonic networks remains challenging, mainly due to the multi-crystallinity of commonly used thermally evaporated gold layers. Resulting structural imperfections in individual circuit elements drastically reduce the yield of functional integrated nanocircuits. Here we demonstrate the use of very large but thin chemically grown single-crystalline gold flakes. After immobilization on any arbitrary surface, they serve as an ideal basis for focused-ion beam milling. We present high-definition ultra-smooth gold nanostructures with reproducible nanosized features over micrometer lengthscales. By comparing multi- and single-crystalline optical antennas we prove that the latter have superior optical properties which are in good agreement with numerical simulations.

  2. Atomically flat single-crystalline gold nanostructures for plasmonic nanocircuitry

    CERN Document Server

    Huang, Jer-Shing; Geisler, Peter; Brüning, Christoph; Kern, Johannes; Prangsma, Jord C; Weinmann, Pia; Kamp, Martin; Forchel, Alfred; Biagioni, Paolo; Sennhauser, Urs; Hecht, Bert

    2010-01-01

    Deep subwavelength integration of high-definition plasmonic nanostructures is of key importance for the development of future optical nanocircuitry for high-speed communication, quantum computation and lab-on-a-chip applications. So far the experimental realization of proposed extended plasmonic networks consisting of multiple functional elements remains challenging, mainly due to the multi-crystallinity of commonly used thermally evaporated gold layers. Resulting structural imperfections in individual circuit elements will drastically reduce the yield of functional integrated nanocircuits. Here we demonstrate the use of very large (>100 micron^2) but thin (<80 nm) chemically grown single-crystalline gold flakes, which, after immobilization, serve as an ideal basis for focused-ion beam milling and other top-down nanofabrication techniques on any desired substrate. Using this methodology we obtain high-definition ultrasmooth gold nanostructures with superior optical properties and reproducible nano-sized fe...

  3. Optical Properties of Linoleic Acid Protected Gold Nanoparticles

    Directory of Open Access Journals (Sweden)

    Ratan Das

    2011-01-01

    Full Text Available Linoleic acid-protected gold nanoparticles have been synthesized through the chemical reduction of tetrachloroaurate ions by ethanol in presence of sodium linoleate. The structure of these nanoparticles is investigated using transmission electron microscopy, which shows that the Au nanoparticles are spherical in shape with a narrow size distribution which ranges from 8 to 15 nm. Colloidal dispersion of gold nanoparticles in cyclohexane exhibits absorption bands in the ultraviolet-visible range due to surface plasmon resonance, with absorption maximum at 530 nm. Fluorescence spectra of gold nanoparticles also show an emission peak at 610 nm when illuminated at 450 nm. UV-Vis spectroscopy reveals that these nanoparticles remain stable for 10 days.

  4. Gold phosphide complexes

    OpenAIRE

    2007-01-01

    The vast majority of gold complexes with five group-element donor ligands contain tertiary phosphines, although compounds with amine, arsine or stibine ligands are also known. Although phosphide ligands, which are formed by deprotonation of non-tertiary phosphines, are closely related to the former, they have been employed to a lesser extent, mainly due to their lower stability. Thus, the chemistry of phosphido-bridged derivatives of the main group elements1-3 or transition metals4-6 has been...

  5. Determining gold content

    International Nuclear Information System (INIS)

    A method for determining the gold content of a material, comprises irradiating a body of the material with neutrons and determining the intensity of γ-rays having an energy of 279 keV arising from the reaction 179Au(nn') 179Au → 279 keV. The apparatus has means for conveying the materials past an assembly, which has a neutron source, which does not produce neutrons having sufficient energy to excite fast neutron reactions in non-auriferous constituents. (author)

  6. Paper or Gold

    OpenAIRE

    Mukund Raj

    2003-01-01

    In our society today, money's value is measured by what it can buy—its purchasing power—not by its material worth, but it hasn't always been so. · My previous papers Impact of agriculture output on exchange rates and Currency competition-Survival of the fittest dealt with issues surrounding exchange rate and currency competitions. This paper- Paper or Gold discusses the validity of human society giving importance to paper money. · We all know that the human race always believes in experimenti...

  7. Gold/titania composites: An X-ray absorption spectroscopy study on the influence of the reduction method

    Energy Technology Data Exchange (ETDEWEB)

    Meire, Mieke [Ghent University, Department of Inorganic and Physical Chemistry, Krijgslaan 281-S3, 9000 Ghent (Belgium); Tack, Pieter [Ghent University, Department of Analytical Chemistry, Krijgslaan 281-S12, 9000 Ghent (Belgium); De Keukeleere, Katrien [Ghent University, Department of Inorganic and Physical Chemistry, Krijgslaan 281-S3, 9000 Ghent (Belgium); Balcaen, Lieve [Ghent University, Department of Analytical Chemistry, Krijgslaan 281-S12, 9000 Ghent (Belgium); Pollefeyt, Glenn [Ghent University, Department of Inorganic and Physical Chemistry, Krijgslaan 281-S3, 9000 Ghent (Belgium); Vanhaecke, Frank; Vincze, Laszlo [Ghent University, Department of Analytical Chemistry, Krijgslaan 281-S12, 9000 Ghent (Belgium); Van Der Voort, Pascal; Van Driessche, Isabel [Ghent University, Department of Inorganic and Physical Chemistry, Krijgslaan 281-S3, 9000 Ghent (Belgium); Lommens, Petra, E-mail: Petra.Lommens@UGent.be [Ghent University, Department of Inorganic and Physical Chemistry, Krijgslaan 281-S3, 9000 Ghent (Belgium)

    2015-08-01

    The functionalization of titania based materials with noble metal cocatalysts such as gold or platinum is a well known procedure to improve the catalytic activity of these materials in for example the degradation of organic pollutants or CO conversion. Parameters such as cocatalyst load, noble metal particle size and oxidation state influence the efficiency of these materials. We have impregnated a mesoporous titania powder with a gold salt and used different synthesis routes to reduce the gold ions. A structural analysis was performed using electron microscopy and nitrogen sorption. An X-ray absorption near edge structure spectroscopy study, in both high and low resolution, was performed to investigate the influence of the different reduction methods on the oxidation state of the gold atoms. This technique can also provide information on the local environment of the gold atoms and their interaction with the titanium dioxide host. We found that varying the reduction method has a significant impact on the oxidation state of the gold cocatalysts. This lead to varying interactions with the titania support and charging of the gold nanoparticles. - Highlights: • Influence of reduction method on Au/TiO{sub 2} was studied. • Hydrogen reduction of gold salt results in the smallest particles of 2.4 nm. • XANES is used to determine the oxidation state of gold atoms. • Hydrogen and microwave synthesis produce completely reduced gold particles. • UV reduction of gold salt leads to positively charged particles.

  8. Gold/titania composites: An X-ray absorption spectroscopy study on the influence of the reduction method

    International Nuclear Information System (INIS)

    The functionalization of titania based materials with noble metal cocatalysts such as gold or platinum is a well known procedure to improve the catalytic activity of these materials in for example the degradation of organic pollutants or CO conversion. Parameters such as cocatalyst load, noble metal particle size and oxidation state influence the efficiency of these materials. We have impregnated a mesoporous titania powder with a gold salt and used different synthesis routes to reduce the gold ions. A structural analysis was performed using electron microscopy and nitrogen sorption. An X-ray absorption near edge structure spectroscopy study, in both high and low resolution, was performed to investigate the influence of the different reduction methods on the oxidation state of the gold atoms. This technique can also provide information on the local environment of the gold atoms and their interaction with the titanium dioxide host. We found that varying the reduction method has a significant impact on the oxidation state of the gold cocatalysts. This lead to varying interactions with the titania support and charging of the gold nanoparticles. - Highlights: • Influence of reduction method on Au/TiO2 was studied. • Hydrogen reduction of gold salt results in the smallest particles of 2.4 nm. • XANES is used to determine the oxidation state of gold atoms. • Hydrogen and microwave synthesis produce completely reduced gold particles. • UV reduction of gold salt leads to positively charged particles

  9. Metallic gold treatment reduces proliferation of inflammatory cells, increases expression of VEGF and FGF, and stimulates cell proliferation in the subventricular zone following experimental traumatic brain injury

    DEFF Research Database (Denmark)

    Pedersen, Mie Østergaard; Larsen, Agnete; Pedersen, Dan Sonne;

    2009-01-01

    Traumatic brain injury represents a leading cause of morbidity in young individuals and there is an imperative need for neuroprotective treatments limiting the neurologic impairment following such injury. It has recently been demonstrated that bio-liberated gold ions liberated from small metallic...... increase in cell proliferation in both the ipsilateral and the contralateral subventricular zone was found in response to gold-treatment. In conclusion: we confirmed the previously demonstrated anti-inflammatory effect of bio-liberated gold ions, and further show that metallic gold increases growth factor...

  10. Gold-induced lung disease.

    OpenAIRE

    Heyd, J.; Simmeran, A.

    1983-01-01

    A 70-year-old female with seronegative rheumatoid arthritis developed interstitial pneumonitis while on chrysotherapy. The reversibility of lung disease and favourable response to steroid treatment support the diagnosis of gold-induced lung disease and distinguish this entity from other forms of interstitial lung disease associated with rheumatoid arthritis. The relevant literature related to gold-induced lung disease is briefly reviewed.

  11. Preparation of bicontinuous mesoporous silica and organosilica materials containing gold nanoparticles by co-synthesis method

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Byunghwan [Korea Institute of Industrial Technology, ChonAn, Korea; Zhu, Haoguo [ORNL; Zhang, Zongtao [ORNL; Overbury, Steven {Steve} H [ORNL; Dai, Sheng [ORNL

    2004-01-01

    Catalytic activities of gold strongly depend on its particle size. It is necessary to have homogeneous distributions of small gold nanoparticles with diameters between 2 and 5 nm for excellent catalytic activities. In this study, gold-containing mesoporous silica materials were prepared by a co-synthesis method. The essence of this sol-gel co-synthesis method is to combine together neutral surfactant template synthesis of mesoporous silica materials with the introduction of metal ions via bifunctional silane ligands, so that the formation of mesostructures and metal-ion doping occur simultaneously. The formation of gold nanoparticles with size less than 5 nm inside mesoporous materials (HMS, MSU, and PMO) has been achieved by this co-synthesis sol-gel process. In addition, the effects of post-treatments, such as calcination and reduction, on pore structures and nanoparticle size distributions were also investigated.

  12. Size and shape control in the overgrowth of gold nanorods

    Energy Technology Data Exchange (ETDEWEB)

    Ratto, Fulvio; Matteini, Paolo; Rossi, Francesca; Pini, Roberto, E-mail: r.pini@ifac.cnr.i [Istituto di Fisica Applicata ' Nello Carrara' , Consiglio Nazionale delle Ricerche (Italy)

    2010-08-15

    We report on a new sustainable approach to manipulate the optical behaviour and geometrical properties of gold nanorods in aqueous solutions by fine control of their overgrowth. In our approach, the overgrowth is realized by modulation of the reduction of the gold ions which are left as Au{sup 1+} after the primary step of the synthesis (typically as much as {approx}80% of the gold ions available in the growth solution). The progress of the reduction requires the gradual addition of ascorbic acid, which transforms the Au{sup 1+} into Au{sup 0} and may be performed in the original growth solution with no need for any further manipulation. By control of the total amount and rate of administration of the ascorbic acid, we prove the possibility to realize a systematic modulation of the average lengths, diameters, shapes (rod or dog-bone like), and light extinction of the nanoparticles. A slow overgrowth leads to a gradual enlargement of the lengths and diameters at almost constant shape. In contrast, a faster overgrowth results into a more complex modification of the overall shape of the gold nanorods.

  13. Lamellar multilayer hexadecylaniline-modified gold nanoparticle films deposited by the Langmuir-Blodgett technique

    Indian Academy of Sciences (India)

    Anita Swami; Ashavani Kumar; Murali Sastry

    2003-06-01

    Organization of hexadecylaniline (HDA)-modified colloidal gold particles at the air-water interface and the formation thereafter of lamellar, multilayer films of gold nanoparticles by the Langmuir-Blodgett technique is described in this paper. Formation of HDA-capped gold nanoparticles is accomplished by a simple biphasic mixture experiment wherein the molecule hexadecylaniline present in the organic phase leads to electrostatic complexation and reduction of aqueous chloroaurate ions, capping of the gold nanoparticles thus formed and phase transfer of the now hydrophobic particles into the organic phase. Organization of gold nanoparticles at the air-water interface is followed by surface pressure-area isotherm measurements while the formation of multilayer films of the nanoparticles by the Langmuir-Blodgett technique is monitored by quartz crystal microgravimetry, UVVis spectroscopy, Fourier transform infrared spectroscopy and transmission electron microscopy.

  14. Radiation-enhanced thermal processes during implantation of gold into copper

    Energy Technology Data Exchange (ETDEWEB)

    Perret, N.E.; King, B.V.; Dastoor, P.C. [Newcastle Univ., NSW (Australia). Dept. of Physics

    1996-12-31

    A copper (100) single crystal has been implanted with gold ions at temperatures ranging from 133 K to 673 K. Rutherford Backscattering Spectroscopy (RBS) has been used to observe the changes in the gold implant distribution that occur as a function of the sample temperature during implantation. Two distinct effects have been observed. Firstly the gold implant distribution, as a function of depth, broadens with sample temperature. This broadening of the gold depth profile is most marked at temperatures above 473 K. Secondly, the gold is implanted deeper into the copper crystal as the sample temperature is increased. These results are discussed in terms of radiation enhanced diffusion and radiation-induced segregation processes. 10 refs., 3 figs.

  15. Sulfur radical species form gold deposits on Earth.

    Science.gov (United States)

    Pokrovski, Gleb S; Kokh, Maria A; Guillaume, Damien; Borisova, Anastassia Y; Gisquet, Pascal; Hazemann, Jean-Louis; Lahera, Eric; Del Net, William; Proux, Olivier; Testemale, Denis; Haigis, Volker; Jonchière, Romain; Seitsonen, Ari P; Ferlat, Guillaume; Vuilleumier, Rodolphe; Saitta, Antonino Marco; Boiron, Marie-Christine; Dubessy, Jean

    2015-11-01

    Current models of the formation and distribution of gold deposits on Earth are based on the long-standing paradigm that hydrogen sulfide and chloride are the ligands responsible for gold mobilization and precipitation by fluids across the lithosphere. Here we challenge this view by demonstrating, using in situ X-ray absorption spectroscopy and solubility measurements, coupled with molecular dynamics and thermodynamic simulations, that sulfur radical species, such as the trisulfur ion S3(-), form very stable and soluble complexes with Au(+) in aqueous solution at elevated temperatures (>250 °C) and pressures (>100 bar). These species enable extraction, transport, and focused precipitation of gold by sulfur-rich fluids 10-100 times more efficiently than sulfide and chloride only. As a result, S3(-) exerts an important control on the source, concentration, and distribution of gold in its major economic deposits from magmatic, hydrothermal, and metamorphic settings. The growth and decay of S3(-) during the fluid generation and evolution is one of the key factors that determine the fate of gold in the lithosphere.

  16. High-Yield Synthesis and Applications of Anisotropic Gold Nanoparticles

    Science.gov (United States)

    Vigderman, Leonid

    This work will describe research directed towards the synthesis of anisotropic gold nanoparticles as well as their functionalization and biological applications. The thesis will begin by describing a new technique for the high-yield synthesis of gold nanorods using hydroquinone as a reducing agent. This addresses important limitations of the traditional nanorod synthesis including low yield of gold ions conversion to metallic form and inability to produce rods with longitudinal surface plasmon peak above 850 nm. The use of hydroquinone was also found to improve the synthesis of gold nanowires via the nanorod-seed mediated procedure developed in our lab. The thesis will next present the synthesis of novel starfruitshaped nanorods, mesorods, and nanowires using a modified nanorod-seed mediated procedure. The starfruit particles displayed increased activity as surfaceenhanced Raman spectroscopy (SERS) substrates as compared to smooth structures. Next, a method for the functionalization of gold nanorods using a cationic thiol, 16-mercaptohexadecyltrimethylammonium bromide (MTAB), will be described. By using this thiol, we were able to demonstrate the complete removal of toxic surfactant from the nanorods and were also able to precisely quantify the grafting density of thiol molecules on the nanorod surface through a combination of several analytical techniques. Finally, this thesis will show that MTABfunctionalized nanorods are nontoxic and can be taken up in extremely high numbers into cancer cells. The thesis will conclude by describing the surprising uptake of larger mesorods and nanowires functionalized with MTAB into cells in high quantities.

  17. The adjuvanticity of gold nanoparticles

    Science.gov (United States)

    Dykman, Lev A.; Bogatyrev, Vladimir A.; Staroverov, Sergey A.; Pristensky, Dmitry V.; Shchyogolev, Sergey Yu.; Khlebtsov, Nikolai G.

    2006-06-01

    A new variant of a technique for in vivo production of antibodies to various antigens with colloidal-gold nanoparticles as carrier is discussed. With this technique we obtained highly specific and relatively high-titre antibodies to different antigens. The antibodies were tested by an immunodot assay with gold nanoparticle markers. Our results provide the first demonstration that immunization of animals with colloidal gold complexed with either haptens or complete antigens gives rise to highly specific antibodies even without the use of complete Freund's adjuvant. These findings may attest to the adjuvanticity of gold nanoparticles itself. We provide also experimental results and discussion aimed at elucidation of possible mechanisms of the discovered colloidal-gold-adjuvanticity effect.

  18. One-dimensional fossil-like γ-Fe2O3@carbon nanostructure: preparation, structural characterization and application as adsorbent for fast and selective recovery of gold ions from aqueous solution

    Science.gov (United States)

    Gunawan, Poernomo; Xiao, Wen; Hao Chua, Marcus Wen; Poh-Choo Tan, Cheryl; Ding, Jun; Zhong, Ziyi

    2016-10-01

    One-dimensional (1D) magnetic nanostructures with high thermal stability have important industrial applications, but their fabrication remains a big challenge. Herein we demonstrate a scalable approach for the preparation of stable 1D γ-Fe2O3@carbon, which is also applicable for other metal oxide-core and carbon-shell nanostructures, such as 1D TiO2@carbon. One-dimensional ferric oxyhydroxide (α-FeO(OH)) was initially prepared by a hydrothermal method, followed by carbon coating through hydrothermal treatment of the resulting metal oxide in glucose solution. After calcination in N2 gas at 500 °C and subsequent exposure to air, the initial carbon-coated 1D α-Fe2O3 was converted to 1D γ-Fe2O3@carbon, which was very stable without any observed changes even after 1.5 years of storage under ambient conditions. The materials were then used as adsorbents and found to be highly selective towards Au (III) adsorption, of which the maximum adsorption capacity is about 600 mg Au/g sorbent (1132 mg Au/g carbon). The spent sorbent containing Au after adsorption can be readily collected by applying a magnetic field due to the presence of the magnetic core, and the adsorbed Au particles are subsequently recovered after the combustion and dissolution of the sorbent. This work demonstrates not only a facile approach to the fabrication of robust 1D magnetic materials with a stable carbon shell, but also a possible cyanide-free process for the fast and selective recovery of gold from electronic waste and industrial water.

  19. One-dimensional fossil-like γ-Fe2O3@carbon nanostructure: preparation, structural characterization and application as adsorbent for fast and selective recovery of gold ions from aqueous solution.

    Science.gov (United States)

    Gunawan, Poernomo; Xiao, Wen; Chua, Marcus Wen Hao; Tan, Cheryl Poh-Choo; Ding, Jun; Zhong, Ziyi

    2016-10-14

    One-dimensional (1D) magnetic nanostructures with high thermal stability have important industrial applications, but their fabrication remains a big challenge. Herein we demonstrate a scalable approach for the preparation of stable 1D γ-Fe2O3@carbon, which is also applicable for other metal oxide-core and carbon-shell nanostructures, such as 1D TiO2@carbon. One-dimensional ferric oxyhydroxide (α-FeO(OH)) was initially prepared by a hydrothermal method, followed by carbon coating through hydrothermal treatment of the resulting metal oxide in glucose solution. After calcination in N2 gas at 500 °C and subsequent exposure to air, the initial carbon-coated 1D α-Fe2O3 was converted to 1D γ-Fe2O3@carbon, which was very stable without any observed changes even after 1.5 years of storage under ambient conditions. The materials were then used as adsorbents and found to be highly selective towards Au (III) adsorption, of which the maximum adsorption capacity is about 600 mg Au/g sorbent (1132 mg Au/g carbon). The spent sorbent containing Au after adsorption can be readily collected by applying a magnetic field due to the presence of the magnetic core, and the adsorbed Au particles are subsequently recovered after the combustion and dissolution of the sorbent. This work demonstrates not only a facile approach to the fabrication of robust 1D magnetic materials with a stable carbon shell, but also a possible cyanide-free process for the fast and selective recovery of gold from electronic waste and industrial water. PMID:27585547

  20. Radiation-induced synthesis of gold, iron-oxide composite nanoparticles

    International Nuclear Information System (INIS)

    Composite nanoparticles consisting of magnetic iron oxide nanoparticles and gold nanoparticles were synthesized using gamma-rays or electron beam. Ionizing irradiation induces the generation of reducing species inside the aqueous solution, and gold ions are reduced to form metallic Au nanoparticles. The size of Au nanoparticles depended on the dose rate and the concentration of support iron oxide. The gold nanoparticles on iron oxide nanoparticles selectively adsorb biomolecules via Au-S bonding. By using magnetic property of the support iron oxide nanoparticles, the composite nanoparticles are expected as a new type of magnetic nanocarrier for biomedical applications. (author)

  1. Bleaching of sol-gel glass film with embedded gold nanoparticles by thermal poling

    OpenAIRE

    Mezzapesa, Francesco P.; Carvalho, Isabel C. S.; Kazansky, Peter G.; Kawazu, Mitsuhiro; SAKAGUCHI, Koichi

    2006-01-01

    Gold clusters embedded in glass are expected to be hard to dissolve in the form of ions since gold is essentially a nonreactive metal. In spite of that, bleaching of Au-doped nanocomposite sol-gel glass film on a soda-lime glass substrate is demonstrated in which electric-field thermal poling is employed to effectively dissolve randomly distributed gold nanoparticles (15 nm in diameter) embedded in a low conductivity sol-gel glass film with a volume filling factor as small as 2.3%. The surfac...

  2. Green Chemistry Approach for the Synthesis of Gold Nanoparticles Using the Fungus Alternaria sp.

    Science.gov (United States)

    Dhanasekar, Naresh Niranjan; Rahul, Ganga Ravindran; Narayanan, Kannan Badri; Raman, Gurusamy; Sakthivel, Natarajan

    2015-07-01

    The synthesis of gold nanoparticles has gained tremendous attention owing to their immense applications in the field of biomedical sciences. Although several chemical procedures are used for the synthesis of nanoparticles, the release of toxic and hazardous by-products restricts their use in biomedical applications. In the present investigation, gold nanoparticles were synthesized biologically using the culture filtrate of the filamentous fungus Alternaria sp. The culture filtrate of the fungus was exposed to three different concentrations of chloroaurate ions. In all cases, the gold ions were reduced to Au(0), leading to the formation of stable gold nanoparticles of variable sizes and shapes. UV-Vis spectroscopy analysis confirmed the formation of nanoparticles by reduction of Au(3+) to Au(0). TEM analysis revealed the presence of spherical, rod, square, pentagonal, and hexagonal morphologies for 1 mM chloroaurate solution. However, quasi-spherical and spherical nanoparticles/heart-like morphologies with size range of about 7-13 and 15-18 nm were observed for lower molar concentrations of 0.3 and 0.5 mM gold chloride solution, respectively. The XRD spectrum revealed the face-centered cubic crystals of synthesized gold nanoparticles. FT-IR spectroscopy analysis confirmed the presence of aromatic primary amines, and the additional SPR bands at 290 and 230 nm further suggested that the presence of amino acids such as tryptophan/tyrosine or phenylalanine acts as the capping agent on the synthesized mycogenic gold nanoparticles.

  3. Green Chemistry Approach for the Synthesis of Gold Nanoparticles Using the Fungus Alternaria sp.

    Science.gov (United States)

    Dhanasekar, Naresh Niranjan; Rahul, Ganga Ravindran; Narayanan, Kannan Badri; Raman, Gurusamy; Sakthivel, Natarajan

    2015-07-01

    The synthesis of gold nanoparticles has gained tremendous attention owing to their immense applications in the field of biomedical sciences. Although several chemical procedures are used for the synthesis of nanoparticles, the release of toxic and hazardous by-products restricts their use in biomedical applications. In the present investigation, gold nanoparticles were synthesized biologically using the culture filtrate of the filamentous fungus Alternaria sp. The culture filtrate of the fungus was exposed to three different concentrations of chloroaurate ions. In all cases, the gold ions were reduced to Au(0), leading to the formation of stable gold nanoparticles of variable sizes and shapes. UV-Vis spectroscopy analysis confirmed the formation of nanoparticles by reduction of Au(3+) to Au(0). TEM analysis revealed the presence of spherical, rod, square, pentagonal, and hexagonal morphologies for 1 mM chloroaurate solution. However, quasi-spherical and spherical nanoparticles/heart-like morphologies with size range of about 7-13 and 15-18 nm were observed for lower molar concentrations of 0.3 and 0.5 mM gold chloride solution, respectively. The XRD spectrum revealed the face-centered cubic crystals of synthesized gold nanoparticles. FT-IR spectroscopy analysis confirmed the presence of aromatic primary amines, and the additional SPR bands at 290 and 230 nm further suggested that the presence of amino acids such as tryptophan/tyrosine or phenylalanine acts as the capping agent on the synthesized mycogenic gold nanoparticles. PMID:25737119

  4. Heavy ion acceleration using femtosecond laser pulses

    CERN Document Server

    Petrov, G M; Thomas, A G R; Krushelnick, K; Beg, F N

    2015-01-01

    Theoretical study of heavy ion acceleration from ultrathin (<200 nm) gold foils irradiated by a short pulse laser is presented. Using two dimensional particle-in-cell simulations the time history of the laser bullet is examined in order to get insight into the laser energy deposition and ion acceleration process. For laser pulses with intensity , duration 32 fs, focal spot size 5 mkm and energy 27 Joules the calculated reflection, transmission and coupling coefficients from a 20 nm foil are 80 %, 5 % and 15 %, respectively. The conversion efficiency into gold ions is 8 %. Two highly collimated counter-propagating ion beams have been identified. The forward accelerated gold ions have average and maximum charge-to-mass ratio of 0.25 and 0.3, respectively, maximum normalized energy 25 MeV/nucleon and flux . Analytical model was used to determine a range of foil thicknesses suitable for acceleration of gold ions in the Radiation Pressure Acceleration regime and the onset of the Target Normal Sheath Acceleratio...

  5. GOLD and the fixed ratio

    Directory of Open Access Journals (Sweden)

    Vestbo J

    2012-09-01

    Full Text Available Jørgen VestboUniversity of Manchester, Manchester, UKI read with interest the paper entitled "Diagnosis of airway obstruction in the elderly: contribution of the SARA study" by Sorino et al in a recent issue of this journal.1 Being involved in the Global Initiative for Obstructive Lung Diseases (GOLD, it is nice to see the interest sparked by the GOLD strategy document. However, in the paper by Sorino et al, there are a few misunderstandings around GOLD and the fixed ratio (forced expiratory volume in 1 second/forced volume vital capacity < 0.70 that need clarification.View original paper by Sorino and colleagues.

  6. An Experimental Styudy on Gold Solubility in Amino Acid Solution and Its Geological Significance

    Institute of Scientific and Technical Information of China (English)

    张景荣; 陆建军; 等

    1996-01-01

    The experiments on gold solubility in amino acid solution mdicate that gold is very intensively soluble in amino acid(or other organic acids),which is extensively present in geological bodies,and is most soluble in histidine.The temperature and concentration,acidity and type of amino acid in the solution are important factors affecting gold-amino acid complexing. The solubility of gold in amino acid is different under different conditions of temperature, amino acid concentration and pH value of the solution,At 80℃ and pH=6-8,gold is most soluble in amino acid.Gold dispersed in water and rocks could be concentrated and transported by amino acid and then precipitated in favorable loci.Amino acids might have played an important role in metallogenesis as well as in the formation of source beds of gold.Nitrogen,oxygen and sulfur in amino acid might have reacted with gold to form soluble complex ions.

  7. Chloride sublimation of gold-arsenic concentrates

    International Nuclear Information System (INIS)

    Present article is devoted to chloride sublimation of gold-arsenic concentrates. The results of studies of chloride sublimation of gold-arsenic comprising concentrates of Chore deposit of Tajikistan are considered. It is found that by application sodium chloride for gold-arsenic comprising concentrates it is possible to extract gold and silver from flotation concentrates.

  8. 41 CFR 101-45.002 - Gold.

    Science.gov (United States)

    2010-07-01

    ... 41 Public Contracts and Property Management 2 2010-07-01 2010-07-01 true Gold. 101-45.002 Section... PERSONAL PROPERTY § 101-45.002 Gold. (a) Gold will be sold in accordance with this section and part 102-38 of the Federal Management Regulation. (b) Sales of gold shall be processed to— (1) Use the sealed...

  9. Invisible gold in Colombian auriferous soils

    Energy Technology Data Exchange (ETDEWEB)

    Bustos Rodriguez, H., E-mail: hbustos@ut.edu.co; Oyola Lozano, D.; Rojas Martinez, Y. A. [Universidad del Tolima, Departamento de Fisica (Colombia); Perez Alcazar, G. A. [Universidad del Valle, Departamento de Fisica (Colombia); Balogh, A. G. [Darmstadt University of Technology, Institute of Materials Science (Germany)

    2005-11-15

    Optic microscopy, X-ray diffraction (XRD), Moessbauer spectroscopy (MS), Electron microprobe analysis (EPMA) and secondary ions mass spectroscopy (SIMS) were used to study Colombian auriferous soils. The auriferous samples, collected from El Diamante mine, located in Guachavez-Narino (Colombia), were prepared by means of polished thin sections and polished sections for EPMA and SIMS. Petrography analysis was made using an optical microscope with a vision camera, registering the presence, in different percentages, of the following phases: pyrite, quartz, arsenopyrite, sphalerite, chalcopyrite and galena. By XRD analysis, the same phases were detected and their respective cell parameters calculated. By MS, the presence of two types of pyrite was detected and the hyperfine parameters are: {delta}{sub 1} = 0.280 {+-} 0.01 mm/s and {Delta}Q{sub 1} = 0.642 {+-} 0.01 mm/s, {delta}{sub 2} = 0.379 {+-} 0.01 mm/s and {Delta}Q{sub 2} = 0.613 {+-} 0.01 mm/s. For two of the samples MS detected also the arsenopyrite and chalcopyrite presence. The mean composition of the detected gold regions, established by EPMA, indicated 73% Au and 27% Ag (electrum type). Multiple regions of approximately 200 x 200 {mu}m of area in each mineral sample were analyzed by SIMS registering the presence of 'invisible gold' associated mainly with the pyrite and occasionally with the arsenopyrite.

  10. Enhancement of gold recovery using bioleaching from gold concentrate

    Science.gov (United States)

    Choi, S. H.; Cho, K. H.; Kim, B. J.; Choi, N. C.; Park, C. Y.

    2012-04-01

    The gold in refractory ores is encapsulated as fine particles (sometimes at a molecular level) in the crystal structure of the sulfide (typically pyrite with or without arsenopyrite) matrix. This makes it impossible to extract a significant amount of refractory gold by cyanidation since the cyanide solution cannot penetrate the pyrite/arsenopyrite crystals and dissolve gold particles, even after fine grinding. To effectively extract gold from these ores, an oxidative pretreatment is necessary to break down the sulfide matrix. The most popular methods of pretreatment include nitric acid oxidation, roasting, pressure oxidation and biological oxidation by microorganisms. This study investigated the bioleaching efficiency of Au concentrate under batch experimental conditions (adaptation cycles and chemical composition adaptation) using the indigenous acidophilic bacteria collected from gold mine leachate in Sunsin gold mine, Korea. We conducted the batch experiments at two different chemical composition (CuSO4 and ZnSO4), two different adaptation cycles 1'st (3 weeks) and 2'nd (6 weeks). The results showed that the pH in the bacteria inoculating sample decreased than initial condition and Eh increased. In the chemical composition adaptation case, the leached accumulation content of Fe and Pb was exhibited in CuSO4 adaptation bacteria sample more than in ZnSO4 adaptation bacteria samples, possibly due to pre-adaptation effect on chalcopyrite (CuFeS2) in gold concentrate. And after 21 days on the CuSO4 adaptation cycles case, content of Fe and Pb was appeared at 1'st adaptation bacteria sample(Fe - 1.82 and Pb - 25.81 times per control sample) lower than at 2'nd adaptation bacteria sample(Fe - 2.87 and Pb - 62.05 times per control sample). This study indicates that adaptation chemical composition and adaptation cycles can play an important role in bioleaching of gold concentrate in eco-/economic metallurgy process.

  11. Gold-Catalyzed Synthesis of Heterocycles

    Science.gov (United States)

    Arcadi, Antonio

    2014-04-01

    The following sections are included: * Introduction * Synthesis of Heterocycles via Gold-Catalyzed Heteroatom Addition to Unsaturated C-C Bonds * Synthesis of Heterocyclic Derivatives through Gold-Catalyzed Cyclization of Polyunsaturated Compounds * Synthesis of Heterocyclic Compounds via α-Oxo Gold Carbenoid * Synthesis of Heterocyclic Derivatives through Gold-Catalyzed Cycloaddition Reactions * Synthesis of Heterocyclic Derivatives through Gold-Catalyzed Activation of Carbonyl Groups and Alcohols * Synthesis of Heterocyclic Compounds through Gold-Mediated C-H Bond Functionalization * Gold-Catalyzed Domino Cyclization/Oxidative Coupling Reactions * Conclusions * References

  12. Protein-mediated autoreduction of gold salts to gold nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Basu, Nivedita; Bhattacharya, Resham; Mukherjee, Priyabrata [Department of Biochemistry and Molecular Biology, College of Medicine, Mayo Clinic, Rochester, MN 55905 (United States)], E-mail: Mukherjee.Priyabrata@mayo.edu

    2008-09-01

    Here we report for the first time that proteins can function as unique reducing agents to produce gold nanoparticles from gold salts. We demonstrate that three different proteins, namely, bovine serum albumin (BSA), Rituximab (RIT-an anti-CD20 antibody) and Cetuximab (C225-anti-EGFR antibody), reduce gold salts to gold nanoparticles (GNP). Interestingly, among all the three proteins tested, only BSA can reduce gold salts to gold nanotriangles (GNT). BSA-induced formation of GNT can be controlled by carefully selecting the reaction condition. Heating or using excess of ascorbic acid (AA) as additional reducing agent shifts the reaction towards the formation of GNP with flower-like morphology, whereas slowing down the reaction either by cooling or by adding small amount of AA directs the synthesis towards GNT formation. GNT is formed only at pH 3; higher pHs (pH 7 and pH 10) did not produce any nanoparticles, suggesting the involvement of specific protein conformation in GNT formation. The nanomaterials formed by this method were characterized using UV-visible (UV-vis) spectroscopy and transmission electron microscopy (TEM). This is an important finding that will have uses in various nanotechnological applications, particularly in the green synthesis of novel nanomaterials based on protein structure.

  13. Ion implanted dielectric elastomer circuits

    Science.gov (United States)

    O'Brien, Benjamin M.; Rosset, Samuel; Anderson, Iain A.; Shea, Herbert R.

    2013-06-01

    Starfish and octopuses control their infinite degree-of-freedom arms with panache—capabilities typical of nature where the distribution of reflex-like intelligence throughout soft muscular networks greatly outperforms anything hard, heavy, and man-made. Dielectric elastomer actuators show great promise for soft artificial muscle networks. One way to make them smart is with piezo-resistive Dielectric Elastomer Switches (DES) that can be combined with artificial muscles to create arbitrary digital logic circuits. Unfortunately there are currently no reliable materials or fabrication process. Thus devices typically fail within a few thousand cycles. As a first step in the search for better materials we present a preliminary exploration of piezo-resistors made with filtered cathodic vacuum arc metal ion implantation. DES were formed on polydimethylsiloxane silicone membranes out of ion implanted gold nano-clusters. We propose that there are four distinct regimes (high dose, above percolation, on percolation, low dose) in which gold ion implanted piezo-resistors can operate and present experimental results on implanted piezo-resistors switching high voltages as well as a simple artificial muscle inverter. While gold ion implanted DES are limited by high hysteresis and low sensitivity, they already show promise for a range of applications including hysteretic oscillators and soft generators. With improvements to implanter process control the promise of artificial muscle circuitry for soft smart actuator networks could become a reality.

  14. Heavy ion acceleration in the Breakout Afterburner regime

    CERN Document Server

    Petrov, G M; Thomas, A G R; Krushelnick, K; Beg, F N

    2015-01-01

    Theoretical study of heavy ion acceleration from an ultrathin (20 nm) gold foil irradiated by sub-picosecond lasers is presented. Using two dimensional particle-in-cell simulations we identified two highly efficient ion acceleration schemes. By varying the laser pulse duration we observed a transition from Radiation Pressure Acceleration to the Breakout Afterburner regime akin to light ions. The underlying physics and ion acceleration regimes are similar to that of light ions, however, nuances of the acceleration process make the acceleration of heavy ions more challenging. Two laser systems are studied in detail: the Texas Petawatt Laser and the Trident laser, the former having pulse duration 180 fs, intermediate between very short femtosecond pulses and picosecond pulses. Both laser systems generated directional gold ions beams (~10 degrees half-angle) with fluxes in excess of 1011 ion/sr and normalized energy >10 MeV/nucleon.

  15. Optical trapping of gold aerosols

    DEFF Research Database (Denmark)

    Schmitt, Regina K.; Pedersen, Liselotte Jauffred; Taheri, S. M.;

    2015-01-01

    Aerosol trapping has proven challenging and was only recently demonstrated.1 This was accomplished by utilizing an air chamber designed to have a minimum of turbulence and a laser beam with a minimum of aberration. Individual gold nano-particles with diameters between 80 nm and 200 nm were trapped...... in air using a 1064 nm laser. The positions visited by the trapped gold nano-particle were quantified using a quadrant photo diode placed in the back focal plane. The time traces were analyzed and the trapping stiffness characterizing gold aerosol trapping determined and compared to aerosol trapping...... of nanometer sized silica and polystyrene particles. Based on our analysis, we concluded that gold nano-particles trap more strongly in air than similarly sized polystyrene and silica particles. We found that, in a certain power range, the trapping strength of polystyrene particles is linearly decreasing...

  16. Gold, currencies and market efficiency

    Science.gov (United States)

    Kristoufek, Ladislav; Vosvrda, Miloslav

    2016-05-01

    Gold and currency markets form a unique pair with specific interactions and dynamics. We focus on the efficiency ranking of gold markets with respect to the currency of purchase. By utilizing the Efficiency Index (EI) based on fractal dimension, approximate entropy and long-term memory on a wide portfolio of 142 gold price series for different currencies, we construct the efficiency ranking based on the extended EI methodology we provide. Rather unexpected results are uncovered as the gold prices in major currencies lay among the least efficient ones whereas very minor currencies are among the most efficient ones. We argue that such counterintuitive results can be partly attributed to a unique period of examination (2011-2014) characteristic by quantitative easing and rather unorthodox monetary policies together with the investigated illegal collusion of major foreign exchange market participants, as well as some other factors discussed in some detail.

  17. Discovery of the Gold Isotopes

    OpenAIRE

    Schuh, A.; A. Fritsch; Ginepro, J. Q.; Heim, M.; SHORE, A.; Thoennessen, M

    2009-01-01

    Thirty-six gold isotopes have so far been observed; the discovery of these isotopes is discussed. For each isotope a brief summary of the first refereed publication, including the production and identification method, is presented.

  18. Bubble template synthesis of hollow gold nanoparticles and their applications as theranostic agents

    Science.gov (United States)

    Huang, Chienwen

    Hollow gold nanoparticle with a sub-30nm polycrystalline shell and a 50 nm hollow core has been successfully synthesized through the reduction of sodium gold sulfite by electrochemically evolved hydrogen. Such hollow gold nanoparticles exhibit unique plasmonic properties. They strongly scatter and absorb near infrared light. In this thesis we seek to understand the formation mechanism of hollow gold nanoparticles in this new synthesis process and their plasmonic properties. Also, we explore their biomedical applications as theranostic agents (therapeutic and diagnostic imaging). A lithographically patterned electrode consisting of Ag stripes on a glass substrate was used to investigate the formation process of hollow gold nanoparticles. Ag stripes served as working electrode for electrochemically evolution of hydrogen, and adjacent glass areas provided supporting surface for hydrogen nanobubbles nucleation and growth. Hydrogen nanobubbles served as both templates and reducing agents to trigger the autocatalytic disproportionation reaction of sodium gold sulfite. The effects of applied potential and the additives in the electrolyte have been studied. It has been found that the size and size distribution of hollow gold nanoparticle are directly relative to the applied potential, i.e. the hydrogen evolution rate. It has also been found the addition of Ni2+ ions can greatly improve the size distribution of hollow gold nanoparticles that can be contributed to that the newly electrodeposited nickel metal can enhance the hydrogen evolution efficiency. Another additive, ethylenediamine (EDA) can suppress the autocatalytic reaction of gold sulfite to increase the stability of sodium gold sulfite electrolyte. To capture such electrochemically evolved hydrogen nanobubbles, and subsequently to generate hollow gold nanoparticles in large numbers, alumina membranes were placed on the top of the working electrode. Anodic alumina membrane consists of ~200 nm pores, which provides

  19. Chrysopogon zizanioides aqueous extract mediated synthesis characterization of crystalline silver and gold nanoparticles for biomedical applications

    Directory of Open Access Journals (Sweden)

    Arunachalam KD

    2013-07-01

    Full Text Available Kantha D Arunachalam, Sathesh Kumar Annamalai Center for Environmental Nuclear Research, Directorate of Research, SRM University, Chennai, Tamil Nadu, India Abstract: The exploitation of various plant materials for the biosynthesis of nanoparticles is considered a green technology as it does not involve any harmful chemicals. The aim of this study was to develop a simple biological method for the synthesis of silver and gold nanoparticles using Chrysopogon zizanioides. To exploit various plant materials for the biosynthesis of nanoparticles was considered a green technology. An aqueous leaf extract of C. zizanioides was used to synthesize silver and gold nanoparticles by the bioreduction of silver nitrate (AgNO3 and chloroauric acid (HAuCl4 respectively. Water-soluble organics present in the plant materials were mainly responsible for reducing silver or gold ions to nanosized Ag or Au particles. The synthesized silver and gold nanoparticles were characterized by ultraviolet (UV-visible spectroscopy, scanning electron microscopy (SEM, energy dispersive X-ray analysis (EDAX, Fourier transform infrared spectroscopy (FTIR, and X-ray diffraction (XRD analysis. The kinetics decline reactions of aqueous silver/gold ion with the C. zizanioides crude extract were determined by UV-visible spectroscopy. SEM analysis showed that aqueous gold ions, when exposed to the extract were reduced and resulted in the biosynthesis of gold nanoparticles in the size range 20–50 nm. This eco-friendly approach for the synthesis of nanoparticles is simple, can be scaled up for large-scale production with powerful bioactivity as demonstrated by the synthesized silver nanoparticles. The synthesized nanoparticles can have clinical use as antibacterial, antioxidant, as well as cytotoxic agents and can be used for biomedical applications. Keywords: nanoparticles, bioreduction, SEM, silver, gold

  20. SYNTHESES OF POLYSTYRENE RESINS CONTAINING POLYETHER OLIGOMERS AND THEIR EXTRACTION FOR GOLD (Ⅲ)

    Institute of Scientific and Technical Information of China (English)

    DONG Shihua; LIU Shi; XU Yuwu

    1994-01-01

    Three polystyrene resins containing polyether oligomers as extractants were synthesized and their extraction properties were studied. Gold (Ⅲ) ion could be extracted rapidly by the resins (T1/2<1min.)with high efficiency and capacity (for LS-B resin that were 99.8% and 95.8mg/gR respectively) from aqueous solution but most of the co-existing metal ions such as Pd (Ⅱ),Cu(Ⅱ), Zn (Ⅱ), Pb (Ⅱ) and Cd (Ⅱ) were remained. The extraction capacity and stripping percentage for gold (Ⅲ) remained unchanged in four extraction-stripping cycles. The resins also showed good column extraction-elution properties.

  1. Vibrational autodetachment spectroscopy of Au-6 : Image-charge-bound states of a gold ring

    International Nuclear Information System (INIS)

    Spectral experiments on mass-selected negative cluster ions of gold and silver were performed in the wavelength range near the threshold for one-photon photodetachment of the extra electron. The Au-6 cluster ion displayed a uniquely well resolved spectrum consisting of a progression in a single vibrational mode. Details of this threshold photodetachment spectrum and the associated photoelectron energy distribution suggest an explanation based on autodetachment from totally symmetric vibrational levels of very weakly bound excited electronic state (bound by image charge forces) of the Au-6 cluster in the form of a planar, six-fold symmetric, gold ring

  2. Structural Motifs of Gold Nanoparticles.

    Science.gov (United States)

    Cleveland, C. L.; Luedtke, W. D.; Landman, Uzi

    1996-03-01

    Through an extensive search, involving energy minimization using embedded atom potentials, we found(R.L. Whetten et al./), submitted to Nature (1995). that the energetically optimal sequence for AuN clusters (30 motif, and variants thereof. These predictions for bare gold particles, and for particles coated by sef-assembled thiol monolayers, are discussed in light of recent experiments on the preparation and characterization (including mass spectrometry, electron microscopy, and X-ray diffraction) of nanocrystalline gold molecules (see Ref. 2).

  3. Characterisation of gold from Fiji

    OpenAIRE

    Naden, Jon; Henney, P.J.

    1995-01-01

    This is a study of the variation in chemistry and inclusion mineralogy of bedrock and placer gold from Fiji. It forms part of a large project, undertaking gold characterisation from a wide range of geological environments in Ecuador, Zimbabwe, Malaysia and Fiji. The work was carried out under the Overseas Development AdministratiodBritish Geological Survey Technology Development and Research programme (Project R5549) as part of the British Government’s provision of technical...

  4. Coalescence Behavior of Gold Nanoparticles

    OpenAIRE

    Wang YQ; Liang WS; Geng CY

    2009-01-01

    Abstract The tetraoctylammonium bromide (TOAB)-stabilized gold nanoparticles have been successfully fabricated. After an annealing of the as-synthesized nanoparticles at 300 °C for 30 min, the coalescence behavior of gold nanoparticles has been investigated using high-resolution transmission electron microscopy in detail. Two types of coalescence, one being an ordered combination of two or more particles in appropriate orientations through twinning, and the other being an ordered combina...

  5. Gold, coal and oil.

    Science.gov (United States)

    Dani, Sergio U

    2010-03-01

    Jared Diamond has hypothesized that guns, germs and steel account for the fate of human societies. Here I propose an extension of Diamond's hypothesis and put it in other terms and dimensions: gold, coal and oil account not only for the fate of human societies but also for the fate of mankind through the bodily accumulation of anthropogenic arsenic, an invisible weapon of mass extinction and evolutionary change. The background is clear; arsenic species fulfill seven criteria for a weapon of mass extinction and evolutionary change: (i) bioavailability to all living organisms; (ii) imperceptibility; (iii) acute toxicity; (iv) bioaccumulation and chronic toxicity; (v) adverse impact on reproductive fitness and reproductive outcomes and early-age development and growth in a wide range of microbial, plant and animal species including man; (vi) widespread geographical distribution, mobility and ecological persistence on a centennial to millennial basis and (vii) availability in necessary and sufficient amounts to exert evolutionarily meaningful effects. The proof is becoming increasingly feasible as human exploitation of gold, coal and oil deposits cause sustainable rises of arsenic concentrations in the biosphere. Paradoxically, humans are among the least arsenic-resistant organisms because humans are long-lived, encephalized and complex social metazoans. An arsenic accumulation model is presented here to describe how arsenic accumulates in the human body with increasing age and at different provisionally safe exposure levels. Arsenic accumulates in the human body even at daily exposure levels which are within the lowest possible WHO provisional tolerance limits, yielding bodily arsenic concentrations which are above WHO provisional limits. Ongoing consequences of global scale arsenic poisoning of mankind include age-specific rises in morbidity and mortality followed by adaptive changes. The potential rise of successful forms of inborn resistance to arsenic in humans

  6. Selective recovery of gold from waste mobile phone PCBs by hydrometallurgical process

    International Nuclear Information System (INIS)

    Highlights: ► Selective leaching of Au from scrap mobile phone PCBs by two stage electro-generated chlorine and recovery by ion exchange. ► Copper leaching (97%) by 1st stage electro-generated leaching (ORP value Ag/AgCl) with a minor gold (5%). ► Gold leaching (93%, ∼67 mg/L) by 2nd leaching (ORP value >1100 mVAg/AgCl) in 0.1 mol/L HCl at 25 °C. ► A concentrated gold solution, 6034 mg/L with 99.9% purity was obtained by ion exchange process. - Abstract: The leaching of gold from the scrap mobile phone PCBs by electro-generated chlorine as an oxidant and its recovery by ion exchange process was investigated. The leaching experiments were carried out by employing separate leaching reactor connected with the anode compartment of a Cl2 gas generator. The leaching of gold increased with increase in temperature and initial concentration of chlorine, and was favorable even at low concentration of acid, whereas copper leaching increased with increase in concentration of acid and decrease in temperature. In a two-stage leaching process, copper was mostly dissolved (97%) in 165 min at 25 °C during the 1st stage leaching in 2.0 mol/L HCl by electro-generated chlorine at a current density of 714 A/m2 along with a minor recovery of gold (5%). In the 2nd stage gold was mostly leached out (93% recovery, ∼67 mg/L) from the residue of the 1st stage by the electro-generated chlorine in 0.1 mol/L HCl. Gold recovery from the leach liquor by ion exchange using Amberlite XAD-7HP resin was found to be 95% with the maximum amount of gold adsorbed as 46.03 mg/g resin. A concentrated gold solution, 6034 mg/L with 99.9% purity was obtained in the ion exchange process.

  7. Gold nanoparticle (AuNPs) and gold nanopore (AuNPore) catalysts in organic synthesis.

    Science.gov (United States)

    Takale, Balaram S; Bao, Ming; Yamamoto, Yoshinori

    2014-04-01

    Organic synthesis using gold has gained tremendous attention in last few years, especially heterogeneous gold catalysis based on gold nanoparticles has made its place in almost all organic reactions, because of the robust and green nature of gold catalysts. In this context, gold nanopore (AuNPore) with a 3D metal framework is giving a new dimension to heterogeneous gold catalysts. Interestingly, AuNPore chemistry is proving better than gold nanoparticles based chemistry. In this review, along with recent advances, major discoveries in heterogeneous gold catalysis are discussed.

  8. Synthesis of a New Triazene Reagent and Its Application to the Color Reaction with Gold( Ⅲ ) Ion%一种新的三氮烯试剂的合成并应用于金(Ⅲ)离子的显色反应

    Institute of Scientific and Technical Information of China (English)

    陈文宾; 郑秋霞; 马卫兴; 许兴友

    2011-01-01

    以4-氨基安替比林和对氨基苯磺酸为主要反应物,制备了1-(4-安替比林)-3-(对苯磺酸)三氮烯(ASTA).采用红外光谱法对ASTA的分子组成及结构作了检测.研究了该试剂与金(Ⅲ)的显色反应.在含有Triton X-100的pH 10.3的硼砂-氢氧化钠缓冲溶液中,ASTA与金(Ⅲ)反应生成配合比为2:1的橙红色配合物,在其最大吸收波长496nm处的表观摩尔吸光率为1.8×105L·mol-1·cm-1.金(Ⅲ)的质量浓度在0.06~1.05mg·L-1,范围内与其吸光度呈线性关系,方法的检出限(3S/N)为0.02mg·L-1.方法用于含金矿样品中金(Ⅲ)的测定,结果与原子吸收光谱法相一致,方法的回收率在109.0%~118.2%之间,相对标准偏差(n=6)小于4.0%.%A new reagent, 1-(4-antipyrinyl)-3-(sulfanilic acid)-triazene (ASTA), was synthesized by the reaction between 4-antipyrine and sulfanilic acid. Molecular composition and structure of ASTA were determined by FT-IRS. It was found that in a Na2B4O7-NaOH buffer medium of pH 10. 3 containing Triton X-100, a stable coordination complex (R: Au3+ =2 : 1) was formed by the reaction of ASTA with gold ion, having the absorption maximum at 496 nm. Linear relationship between values of absorbanee and concentration of Au (Ⅲ) ion was obtained in the range of 0.06-1.05 mg·L-1. Detection limit (3S/N) found was 0. 02 mg· L-1 The apparent molar absorptivity of the color system was found to be 1.8 × 105L · mol-1 · cm-1. The proposed method was applied to the determination of Au(Ⅲ) in gold ore samples, and the results obtained were in consistency with those obtained by AAS. Values of recovery were found in the range of 109.0%-118. 2% and RSD (n=6) was less than 4.0%.

  9. Shape tailored green synthesis and catalytic properties of gold nanocrystals

    Science.gov (United States)

    Rajan, Anish; MeenaKumari, M.; Philip, Daizy

    2014-01-01

    The use of environmentally benign procedures is highly desirable for the synthesis of nanoparticles. Here we report a simple, versatile, economic, ecofriendly and reproducible green method for the size-tunable synthesis of stable and crystalline gold nanoparticles of varied shape using aqueous extract of Garcinia Combogia fruit. The predominant anisotropic nature in the morphology of synthesized particles at lower quantities of extract gradually shifted to spherical particles with larger quantity of extract and increase of temperature. The onset of reduction, the time-evolution of the Surface Plasmon Resonance (SPR) and the catalytic activity are studied using UV-Visible spectroscopy. The Selected Area Diffraction (SAED) pattern, the lattice fringes in the High Resolution Transmission Electron Microscopic (HRTEM) image and the X-ray Diffraction (XRD) pattern clearly show the pure crystalline nature of the synthesized gold nanoparticles. The role of carboxyl group present in Garcinia Combogia fruit extract in the reduction of chloroaurate ions is established using Fourier Transform Infrared (FTIR) spectra. The size dependent catalytic activity of the green synthesized gold nanoparticles on the reduction of 4-Nitrophenol to 4-Aminophenol using sodium borohydride is studied and reported for the first time. The first order kinetics is fitted and rate constants are calculated. Catalytically active green synthesized gold nanoparticles with controllable size and shape presents an advanced step in future biomedical and chemical applications.

  10. Modeling of gold production in Malaysia

    Science.gov (United States)

    Muda, Nora; Ainuddeen, Nasihah Rasyiqah; Ismail, Hamizun; Umor, Mohd Rozi

    2013-04-01

    This study was conducted to identify the main factors that contribute to the gold production and hence determine the factors that affect to the development of the mining industry in Malaysia. An econometric approach was used by performing the cointegration analysis among the factors to determine the existence of long term relationship between the gold prices, the number of gold mines, the number of workers in gold mines and the gold production. The study continued with the Granger analysis to determine the relationship between factors and gold production. Results have found that there are long term relationship between price, gold production and number of employees. Granger causality analysis shows that there is only one way relationship between the number of employees with gold production in Malaysia and the number of gold mines in Malaysia.

  11. Charged Hadron Transverse Momentum Spectra In Gold+gold And Deuteron+gold Collisions At 200 Gev Per Nucleon Pair

    CERN Document Server

    Kane, J L

    2005-01-01

    The Relativistic Heavy Ion Collider (RHIC) collides Au ions at a center of mass energy of 200 GeV per nucleon pair, which produces the most energetic collisions yet seen in the laboratory. RHIC has also collided proton beams and deuteron+gold beams. By studying these collisions important information about hadronic matter under extreme conditions and quantum chromodynamics (QCD) can be collected. One of the predictions of QCD is that at very high energy densities the quarks and gluons within hadrons will become deconfined and form a Quark-Gluon Plasma (QGP). These densities are thought to be achievable with Au+Au collisions at RHIC energies. Another prediction theorizes that before the collision, the very high energies of the nuclei will create a condensate of the low momentum gluons within the nuclei before any collisions occur. This condensate is termed the Color Glass Condensate (CGC). Both of these predictions can be tested by studying the transverse momentum, pT, spectra of charged hadrons produced in the...

  12. Anti-aggregation-based spectrometric detection of Hg(II) at physiological pH using gold nanorods.

    Science.gov (United States)

    Rajeshwari, A; Karthiga, D; Chandrasekaran, Natarajan; Mukherjee, Amitava

    2016-10-01

    An efficient detection method for Hg (II) ions at physiological pH (pH7.4) was developed using tween 20-modified gold nanorods (NRs) in the presence of dithiothreitol (DTT). Thiol groups (-SH) at the end of DTT have a higher affinity towards gold atoms, and they can covalently interact with gold NRs and leads to their aggregation. The addition of Hg(II) ions prevents the aggregation of gold NRs due to the covalent bond formation between the -SH group of DTT and Hg(II) ions in the buffer system. The changes in the longitudinal surface plasmon resonance peak of gold NRs were characterized using a UV-visible spectrophotometer. The absorption intensity peak of gold NRs at 679nm was observed to reduce after interaction with DTT, and the absorption intensity was noted to increase by increasing the concentration of Hg(II) ions. The TEM analysis confirms the morphological changes of gold NRs before and after addition of Hg(II) ions in the presence of DTT. Further, the aggregation and disaggregation of gold NRs were confirmed by particle size and zeta potential analysis. The developed method shows an excellent linearity (y=0.001x+0.794) for the graph plotted between the absorption ratio and Hg(II) concentration (1 to 100pM) under the optimized conditions. The limit of detection was noted to be 0.42pM in the buffer system. The developed method was tested in simulated body fluid, and it was found to have a good recovery rate. PMID:27287171

  13. Annealing relaxation of ultrasmall gold nanostructures

    Science.gov (United States)

    Chaban, Vitaly

    2015-01-01

    Except serving as an excellent gift on proper occasions, gold finds applications in life sciences, particularly in diagnostics and therapeutics. These applications were made possible by gold nanoparticles, which differ drastically from macroscopic gold. Versatile surface chemistry of gold nanoparticles allows coating with small molecules, polymers, biological recognition molecules. Theoretical investigation of nanoscale gold is not trivial, because of numerous metastable states in these systems. Unlike elsewhere, this work obtains equilibrium structures using annealing simulations within the recently introduced PM7-MD method. Geometries of the ultrasmall gold nanostructures with chalcogen coverage are described at finite temperature, for the first time.

  14. Synthesis and characterization of gold glyconanoparticles functionalized with sugars of sweet Sorghum syrup.

    Science.gov (United States)

    Kumar, C Ganesh; Mamidyala, Suman Kumar; Sreedhar, Bojja; Reddy, Belum V S

    2011-01-01

    Gold glyconanoparticles were synthesized by a simple, rapid, and eco-friendly method by using sweet Sorghum syrup for application in biomedicine and biotechnology. The nanostructures of the prepared gold nanoparticles were confirmed by using UV-visible absorbance, TEM, SAED, FTIR, EDAX, XRD, and photoluminescence analyses. The formation of gold nanoparticles at both room and boiling temperatures and kinetics of the reaction were monitored by UV-visible spectroscopy and TEM studies. TEM analysis revealed that the obtained nanoparticles were mono-dispersed and spherical in shape with an average particle size of 7 nm. The size of the nanoparticles was influenced by the concentration of Sorghum syrup. The presence of elemental gold was confirmed by EDAX analysis. Based on the FTIR analysis, it was observed that the sugars present in the Sorghum syrup possibly acts as capping agents. The zeta potential analysis revealed that the glyconanoparticles were negatively charged with a potential of -25 mV. The XRD and SAED patterns also suggest that the nanoparticles were crystalline in nature and these particles were found to exhibit visible photoluminescence. Fructose and glucose present in sweet Sorghum syrup were demonstrated as responsible sugars for the reduction of gold ions, and sucrose stabilized the formed nanoparticles. The proposed mechanism for the formation and stabilization of gold glyconanoparticles is based on the phenomenon of "macromolecular crowding." This is the first report on the use of sweet Sorghum syrup for the green synthesis of gold glyconanoparticles at both room and boiling temperatures.

  15. Green synthesis of gold nanoparticles using Stevia rebaudiana leaf extracts: Characterization and their stability.

    Science.gov (United States)

    Sadeghi, Babak; Mohammadzadeh, M; Babakhani, B

    2015-07-01

    Various methods invented and developed for the synthesis of gold nanoparticles that increases daily consumed. According to this method, including potential environmental pollution problems and the complexity of the synthesis, in this study, the feasibility of using the leaves extract of Stevia rebaudiana (SR) for the reduction of gold ions to nanoparticles form have been studied. Stevia leaves were used to prepare the aqueous extract for this study. Gold nanoparticles were characterized with different techniques such as UV-vis spectroscopy, FT-IR spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Transmission electron microscopy experiments showed that these nanoparticles are spherical and uniformly distributed and its size is from 5 to 20 nm. FT-IR spectroscopy revealed that gold nanoparticles were functionalized with biomolecules that have primary amine group (NH2), carbonyl group, OH groups and other stabilizing functional groups. X-ray diffraction pattern showed high purity and face centered cubic structure of gold nanoparticles with size of 17 nm. The scanning electron microscopy (SEM) implies the right of forming gold nanoparticles. The results, confirm that gold nanoparticles have synthesized by the leaves extract of S. rebaudiana (SR).

  16. Green synthesis of gold nanoparticles using Stevia rebaudiana leaf extracts: Characterization and their stability.

    Science.gov (United States)

    Sadeghi, Babak; Mohammadzadeh, M; Babakhani, B

    2015-07-01

    Various methods invented and developed for the synthesis of gold nanoparticles that increases daily consumed. According to this method, including potential environmental pollution problems and the complexity of the synthesis, in this study, the feasibility of using the leaves extract of Stevia rebaudiana (SR) for the reduction of gold ions to nanoparticles form have been studied. Stevia leaves were used to prepare the aqueous extract for this study. Gold nanoparticles were characterized with different techniques such as UV-vis spectroscopy, FT-IR spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Transmission electron microscopy experiments showed that these nanoparticles are spherical and uniformly distributed and its size is from 5 to 20 nm. FT-IR spectroscopy revealed that gold nanoparticles were functionalized with biomolecules that have primary amine group (NH2), carbonyl group, OH groups and other stabilizing functional groups. X-ray diffraction pattern showed high purity and face centered cubic structure of gold nanoparticles with size of 17 nm. The scanning electron microscopy (SEM) implies the right of forming gold nanoparticles. The results, confirm that gold nanoparticles have synthesized by the leaves extract of S. rebaudiana (SR). PMID:25900555

  17. Rapid Synthesis of Size-controlled Gold Nanoparticles by Complex Intramolecular Photoreduction

    Institute of Scientific and Technical Information of China (English)

    DONG Shou-an; YANG Sheng-chun; TANG Chun

    2007-01-01

    A rapid synthesis of size-controlled gold nanoparticles was proposed. The method is based on the sensitive intramolecular photoreduction reaction of Fe( Ⅲ )-EDTA complex in chloroacetic acid-sodium acetate buffer solution,where Fe(Ⅱ)-EDTA complex generated by photo-promotion acts as a reductant of AuCl4- ions. Gold nanoparticles formed were stabilized by EDTA ligand or other protective agents added. As a result, well-dispersed gold nanoparticles with an average diameter range of 6.7 to 50. 9 nm were obtained. According to the characterizations by the UV spectrum and TEM, the intramolecular charge transfer of the excited states of complex Fe(Ⅲ) -EDTA and the mechanism of forming gold nanoparticles were discussed in detail.

  18. Selective Gold Recovery and Catalysis in a Highly Flexible Methionine-Decorated Metal-Organic Framework.

    Science.gov (United States)

    Mon, Marta; Ferrando-Soria, Jesús; Grancha, Thais; Fortea-Pérez, Francisco R; Gascon, Jorge; Leyva-Pérez, Antonio; Armentano, Donatella; Pardo, Emilio

    2016-06-29

    A novel chiral 3D bioMOF exhibiting functional channels with thio-alkyl chains derived from the natural amino acid l-methionine (1) has been rationally prepared. The well-known strong affinity of gold for sulfur derivatives, together with the extremely high flexibility of the thioether "arms" decorating the channels, account for a selective capture of gold(III) and gold(I) salts in the presence of other metal cations typically found in electronic wastes. The X-ray single-crystal structures of the different gold adsorbates Au(III)@1 and Au(I)@1 suggest that the selective metal capture occurs in a metal ion recognition process somehow mimicking what happens in biological systems and protein receptors. Both Au(III)@1 and Au(I)@1 display high activity as heterogeneous catalyst for the hydroalkoxylation of alkynes, further expanding the application of these novel hybrid materials. PMID:27295383

  19. Scale-Up and Operating Factors for Electrolytic Silver Recovery from Effluents of Artisanal Used-Gold-Jewelry Smelting Plants in the Philippines

    OpenAIRE

    Catalino Alfafara, PhD; Monet Concepcion Maguyon, MS; Michael Vincent Laurio, BS; Veronica Migo, PhD; Lorele Trinidad, PhD; Elezabeth Ompad, BS; Jennifer Marie Sunga-Amparo, MA; Marlo Mendoza, MA

    2012-01-01

    Background. The Marilao, Meycauayan and Obando river system (MMORS), in the Philippines is home to many precious metals refineries, where local artisanal gold smelting industries use silver to draw gold out of used jewelry. Copper recovers the silver. The copper-rich wastewater contributes to local pollution. Alternative methods for silver recovery include electrolytic recovery: removal of silver ions from solution, and conversion of the ions into metallic silver. Objectives. Explore opera...

  20. High Brightness Plasmon-Enhanced Nanostructured Gold Photoemitters

    Energy Technology Data Exchange (ETDEWEB)

    Gong, Yu; Joly, Alan G.; Kong, Lingmei; El-Khoury, Patrick Z.; Hess, Wayne P.

    2014-12-30

    Plasmonic nanohole arrays are fabricated in gold thin films by focused ion beam (FIB) lithography. Subsequent heat treatment creates sub 100 nm nanometric structures including tips, rods and flakes, all localized in the nanohole array region. The combined nanohole array and nanostructured surface comprise an efficient photoemitter. High brightness photoemission is observed from this construct using photoemission electron microscopy (PEEM), following 780 nm femtosecond (fs) laser irradiation. By comparing our observables to results of finite difference time domain (FDTD) calculations, we demonstrate that photoemission from the sub-100 nm structures is enhanced in the region of propagating surface plasmons launched from the nanohole arrays. Additionally, by tuning hole diameter and separation in the nanohole array, the photoemission intensity of nanostructured photoemitters can be controlled. We observe a photoemission enhancement of over 108, relative to photoemission from the flat region of the gold substrate at laser intensities well below the ablation threshold.

  1. Chrysopogon zizanioides aqueous extract mediated synthesis, characterization of crystalline silver and gold nanoparticles for biomedical applications.

    Science.gov (United States)

    Arunachalam, Kantha D; Annamalai, Sathesh Kumar

    2013-01-01

    The exploitation of various plant materials for the biosynthesis of nanoparticles is considered a green technology as it does not involve any harmful chemicals. The aim of this study was to develop a simple biological method for the synthesis of silver and gold nanoparticles using Chrysopogon zizanioides. To exploit various plant materials for the biosynthesis of nanoparticles was considered a green technology. An aqueous leaf extract of C. zizanioides was used to synthesize silver and gold nanoparticles by the bioreduction of silver nitrate (AgNO3) and chloroauric acid (HAuCl4) respectively. Water-soluble organics present in the plant materials were mainly responsible for reducing silver or gold ions to nanosized Ag or Au particles. The synthesized silver and gold nanoparticles were characterized by ultraviolet (UV)-visible spectroscopy, scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDAX), Fourier transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD) analysis. The kinetics decline reactions of aqueous silver/gold ion with the C. zizanioides crude extract were determined by UV-visible spectroscopy. SEM analysis showed that aqueous gold ions, when exposed to the extract were reduced and resulted in the biosynthesis of gold nanoparticles in the size range 20-50 nm. This eco-friendly approach for the synthesis of nanoparticles is simple, can be scaled up for large-scale production with powerful bioactivity as demonstrated by the synthesized silver nanoparticles. The synthesized nanoparticles can have clinical use as antibacterial, antioxidant, as well as cytotoxic agents and can be used for biomedical applications. PMID:23861583

  2. ADSORPTION CAPACITY OF ACTIVATED CARBON FIBER FABRIC IN CYANIDE LEACHING LIQUOR OF GOLD ORES

    Institute of Scientific and Technical Information of China (English)

    LIUXiaozhen

    2002-01-01

    Adsorption capacity of ACFF in cyanide leaching liquor of gold ores was studied with cyanide leaching liquor of gold ores,containing various kinds of ions.The adsorbed leaching liquor was analyzed by atomic emission spectroscopy and colorimetric method.The contents of various kinds. of ions in ACFF were determined with X-ray photoctron spectroscopy.ACFF not only adsorbed gold but also adsorbed arsenic,nickel,zinc,calcium,sulphur,bismuth,copper,iron,silver and cyanide,anion.Atomic percentage of C and those of O,N,Zn,Fe increase and decrease respectively with the increase of the layer depth,while those of Ca,Au,Ag keep constant.

  3. Biosynthesis of silver and gold nanoparticles by novel sundried Cinnamomum camphora leaf

    Energy Technology Data Exchange (ETDEWEB)

    Huang Jiale [Department of Chemical and Biochemical Engineering, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005 (China); Li Qingbiao [Department of Chemical and Biochemical Engineering, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005 (China); Sun Daohua [Department of Chemical and Biochemical Engineering, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005 (China); Lu Yinghua [Department of Chemical and Biochemical Engineering, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005 (China); Su Yuanbo [Department of Chemical and Biochemical Engineering, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005 (China); Yang Xin [Department of Chemical and Biochemical Engineering, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005 (China); Wang Huixuan [Department of Chemical and Biochemical Engineering, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005 (China); Wang Yuanpeng [Department of Chemical and Biochemical Engineering, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005 (China); Shao Wenyao [Department of Chemical and Biochemical Engineering, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005 (China); He Ning [Department of Chemical and Biochemical Engineering, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005 (China); Hong Jinqing [Department of Chemical and Biochemical Engineering, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005 (China); Chen Cuixue [Department of Chemical and Biochemical Engineering, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005 (China)

    2007-03-14

    The synthesis of nanocrystals is in the limelight in modern nanotechnology. Biosynthesis of nanoparticles by plant extracts is currently under exploitation. Not only could silver nanoparticles ranging from 55 to 80 nm in size be fabricated, but also triangular or spherical shaped gold nanoparticles could be easily modulated by reacting the novel sundried biomass of Cinnamomum camphora leaf with aqueous silver or gold precursors at ambient temperature. The marked difference of shape control between gold and silver nanoparticles was attributed to the comparative advantage of protective biomolecules and reductive biomolecules. The polyol components and the water-soluble heterocyclic components were mainly responsible for the reduction of silver ions or chloroaurate ions and the stabilization of the nanoparticles, respectively. The sundried leaf in this work was very suitable for simple synthesis of nanoparticles.

  4. Biosynthesis of silver and gold nanoparticles by novel sundried Cinnamomum camphora leaf

    Science.gov (United States)

    Huang, Jiale; Li, Qingbiao; Sun, Daohua; Lu, Yinghua; Su, Yuanbo; Yang, Xin; Wang, Huixuan; Wang, Yuanpeng; Shao, Wenyao; He, Ning; Hong, Jinqing; Chen, Cuixue

    2007-03-01

    The synthesis of nanocrystals is in the limelight in modern nanotechnology. Biosynthesis of nanoparticles by plant extracts is currently under exploitation. Not only could silver nanoparticles ranging from 55 to 80 nm in size be fabricated, but also triangular or spherical shaped gold nanoparticles could be easily modulated by reacting the novel sundried biomass of Cinnamomum camphora leaf with aqueous silver or gold precursors at ambient temperature. The marked difference of shape control between gold and silver nanoparticles was attributed to the comparative advantage of protective biomolecules and reductive biomolecules. The polyol components and the water-soluble heterocyclic components were mainly responsible for the reduction of silver ions or chloroaurate ions and the stabilization of the nanoparticles, respectively. The sundried leaf in this work was very suitable for simple synthesis of nanoparticles.

  5. Direct visualization of lead corona and its nanomolar colorimetric detection using anisotropic gold nanoparticles.

    Science.gov (United States)

    Dwivedi, Charu; Chaudhary, Abhishek; Gupta, Abhishek; Nandi, Chayan K

    2015-03-11

    The study presents dithiothreitol (DTT) functionalized anisotropic gold nanoparticles (GNP) based colorimetric sensor for detection of toxic lead ions in water. Our results demonstrate the selectivity and sensitivity of the developed sensor over various heavy metal ions with detection limit of ∼9 nM. The mechanism of sensing is explained on the basis of unique corona formation around the DTT functionalized anisotropic GNP. PMID:25719820

  6. Nanobubble trouble on gold surfaces

    DEFF Research Database (Denmark)

    Holmberg, Maria; Kuhle, A.; Garnaes, J.;

    2003-01-01

    When analyzing surfaces related to biosensors with in situ atomic force microscopy (AFM), the existence of nanobubbles called for our attention. The bubbles seem to form spontaneously when gold surfaces are immersed in clean water and are probably a general phenomenon at water-solid interfaces....... Besides from giving rise to undesired effects in, for example, biosensors, nanobubbles can also cause artifacts in AFM imaging. We have observed nanobubbles on unmodified gold surfaces, immersed in clean water, using standard silicon AFM probes. Nanobubbles can be made to disappear from contact mode AFM...

  7. Biomass processing over gold catalysts

    CERN Document Server

    Simakova, Olga A; Murzin, Dmitry Yu

    2013-01-01

    The book describes the valorization of biomass-derived compounds over gold catalysts. Since biomass is a rich renewable feedstock for diverse platform molecules, including those currently derived from petroleum, the interest in various transformation routes has become intense. Catalytic conversion of biomass is one of the main approaches to improving the economic viability of biorefineries.  In addition, Gold catalysts were found to have outstanding activity and selectivity in many key reactions. This book collects information about transformations of the most promising and important compounds

  8. Coalescence Behavior of Gold Nanoparticles

    Directory of Open Access Journals (Sweden)

    Wang YQ

    2009-01-01

    Full Text Available Abstract The tetraoctylammonium bromide (TOAB-stabilized gold nanoparticles have been successfully fabricated. After an annealing of the as-synthesized nanoparticles at 300 °C for 30 min, the coalescence behavior of gold nanoparticles has been investigated using high-resolution transmission electron microscopy in detail. Two types of coalescence, one being an ordered combination of two or more particles in appropriate orientations through twinning, and the other being an ordered combination of two small particles with facets through a common lattice plane, have been observed.

  9. Electrochemical Studies of Glutathione Monolayer Assembled on A Polycrystalline Gold Electrode

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The glutathione (GSH) monolayer and complex monolayer of GSH-metallic ion on polycrys-talline gold electrode were studied by using K3Fe(CN)6 as the redox probe. As for the GSH monolayer, itwas found that the metallic ions could open the ion-gate in the monolayer dramatically in the order La3+>Pb2+>> Ba2+> Ca2+ whereas Zn2+ ion closed the ion-gate. The complexes of GSH-metallic ions were ca-pable of self-assembling the different kind of monolayer. All the differences were related to the structuralconfiguration of the anchored GSH molecule, which changed with the different metallic ions or pH.

  10. 197Au Moessbauer study of gold ores, mattes, roaster products, and gold minerals

    International Nuclear Information System (INIS)

    The chemical state of gold in gold ores, mattes and roaster products has been studied by 197Au Moessbauer spectroscopy. Gold minerals were studied in order to provide reference data for the ore spectra. 57Fe Moessbauer spectroscopy was used to monitor the iron-compounds always present in gold ores and to follow their transformations caused by smelting and roasting. (orig.)

  11. Hydrogen evolution at nanoporous gold/tungsten sulfide composite film and its optimization

    DEFF Research Database (Denmark)

    Xiao, Xinxin; Engelbrekt, Christian; Li, Zheshen;

    2015-01-01

    Development of efficient and economical electrochemical systems for water splitting is a key part of renewable energy technology. Amorphous films of tungsten sulfide have been deposited by electrochemical reduction of tetrathiotungstate ions (WS42-) on dealloyed nanoporous gold (NPG) for electroc...

  12. Plasmon interactions between gold nanoparticles in aqueous solution with controlled spatial separation

    DEFF Research Database (Denmark)

    Sendroiu, I.E.; Mertens, Stijn; Schiffrin, D.J.

    2006-01-01

    The effects of interparticle distance on the UV-visible absorption spectrum of gold nanocrystals aggregates in aqueous solution have been investigated. The aggregates were produced by ion-templated chelation of omega-mercaptocarboxylic acid ligands covalently attached to the nanoparticles surface...

  13. Study of Vegetable Biodiesel Enhanced by Gold Nanoparticles Using Thermal-Lens Technique

    Science.gov (United States)

    Jiménez-Pérez, J. L.; Fuentes, R. Gutiérrez; Correa-Pacheco, Z. N.; Tánori-Cordova, J.; Cruz-Orea, A.; Gamboa, G. López

    2015-06-01

    In this work, experimental results for the enhancement of the thermal diffusivity of a colloidal suspension of gold nanoparticles in biodiesel oil are reported. Different concentrations of Au nanoparticles are prepared using a microemulsion method, by simultaneous reduction of Au ions in the presence of hydrazine as a reducing agent. The thermal diffusivity was found to increase with increasing nanoparticle concentration.

  14. Minerals in Afghanistan : the potential for gold

    OpenAIRE

    Benham, Antony John; Coats, Stan

    2006-01-01

    Gold has been worked in Afghanistan for centuries from many areas including Takhar province in the north and from Ghazni, Zabul, and Kandahar provinces in the south-west of the country. Currently, gold is produced almost solely by artisanal miners working the Samti Placer Deposit in Takhar Province. Gold deposits and prospects are known in rocks of Proterozoic to Neogene age. Many styles of gold mineralisation occur, in particular skarn, vein-hosted, porphyry and alluvial...

  15. A new green chemistry method based on plant extracts to synthesize gold nanoparticles

    Science.gov (United States)

    Montes Castillo, Milka Odemariz

    solved. In this work, secondary metabolites were extracted from alfalfa biomass in liquid phase by hot water, isopropanol, and methanol, and used to reduce tetrachloroaurate ion (AuCl4-) for the synthesis of gold nanoparticles. Biosyntheses of gold nanoparticles were performed by mixing 0.75, 1.5 and 3.0 mM Au3+ solutions with each one of the extracts at a ratio of 3:1 respectively, and shaken at room temperature for 1h. Resulting gold colloids were characterized by UV-Vis spectrophotometry and electron microscopy techniques, showing size and morphology dependency on the reaction conditions. Isopropanol alfalfa extracts reacted with Au 3+ produced gold nanoparticles with a size range of 15-60 nm. The most abundant were from 40-50 nm, and the morphologies found were polygons, decahedra and icosahedra. Methanol alfalfa extracts produced monodisperse 50 nm decahedral and icosahedral gold nanoparticles. Lastly, water alfalfa extracts reacted with Au3+ produced triangular, truncated triangular and hexagonal nanoplates with diameters ranging from 500 nm to 4 mum and thicknesses of ˜15-40 nm. The production of gold nanoplates by alfalfa extracts has never been reported before. In order to extract the formed gold nanoparticles from the biomass, physical and chemical extractions were used. For the chemical extraction, NaCl, dilute H2SO4, Triton X and DI water were tested. In these cases, the best results were obtained with DI water, followed by NaCl. The extracted nanoparticles had an absorption band at about 539 nm. For the physical extractions, alfalfa biomass containing gold nanoparticles were exposed to 400°C, 500°C, 550°C and 600°C to recover the gold nanoparticles. X-ray diffractograms taken after pyrolysis of the biomass showed that the recovered nanoparticles kept their crystal structure.

  16. Kinetics of cyaniding of gold comprising ores

    International Nuclear Information System (INIS)

    Present article is devoted to kinetics of cyaniding process of gold comprising ores. Thus in laboratory conditions the researches on leaching of gold and silver from ores of various deposits of Tajikistan by means of cyaniding were conducted. The results of laboratory researches on cyaniding of ores of various deposits are presented. The flowsheet of cyaniding of gold comprising ores was elaborated.

  17. Understanding Ligand Effects in Gold Clusters using Mass Spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, Grant E.; Laskin, Julia

    2016-06-16

    This review summarizes recent research on the influence of phosphine ligands on the size, stability, and reactivity of gold clusters synthesized in solution. Sub-nanometer clusters exhibit size- and composition-dependent properties that are unique from those of larger nanoparticles. The highly tunable properties of clusters and their high surface-to-volume ratio make them promising candidates for a variety of technological applications. However, because “each-atom-counts” toward defining cluster properties it is critically important to develop robust synthesis methods to efficiently prepare clusters of predetermined size. For decades phosphines have been known to direct the size-selected synthesis of gold clusters. Despite the preparation of numerous species it is still not understood how different functional groups at phosphine centers affect the size and properties of gold clusters. Using electrospray ionization mass spectrometry (ESI-MS) it is possible to characterize the effect of ligand substitution on the distribution of clusters formed in solution at defined reaction conditions. In addition, ligand exchange reactions on preformed clusters may be monitored using ESI-MS. Collision induced dissociation (CID) may also be employed to obtain qualitative insight into the fragmentation of mixed ligand clusters and the relative binding energies of differently substituted phosphines. Quantitative ligand binding energies and cluster stability may be determined employing surface induced dissociation (SID) in a custom-built Fourier transform ion cyclotron resonance mass spectrometer (FT-ICR-MS). Rice-Ramsperger-Kassel-Marcus (RRKM) based modeling of the SID data allows dissociation energies and entropy values to be extracted that may be compared with the results of high-level theoretical calculations. The charge reduction and reactivity of atomically precise gold clusters, including partially ligated species generated in the gas-phase by in source CID, on well

  18. Gold in Pyrite within Altai – Sayan Folded Belt Gold Deposits

    International Nuclear Information System (INIS)

    This article describes the result analysis of gold in pyrite for a number of some Altai – Sayan folded belt gold deposits. The analyzed pyrite samples showed gold grade from 0.04 to 20.0 g/t., which proves the fact that the gold concentrations in pyrites is irregular. Pyrites in productive mineral associations include significant metal enrichment, while pyrites of early poor gold-bearing associations and wallrock metasomatites are less prolific

  19. Excited States of Gold(I) Compounds, Luminescence and Gold-Gold Bonding

    OpenAIRE

    Fackler, John P.Jr.; Assefa, Zerihun; Forward, Jennifer M.; Staples, Richard J.

    1994-01-01

    It has long been established by Khan that the superoxide anion, O2 -, generates singlet oxygen, O2 1Δg, during dismutation. Auranofin, gold-phosphine thiols, β-Carotene, and metal-sulfur compounds can rapidly quench singlet O2. The quenching of the O2 1Δg, which exists at 7752 cm-1 above the ground state triplet, may be due to the direct interaction of the singlet O2 with gold(I) or may require special ligands such as those containing sulfur coordinated to the metal. Thus we have been examini...

  20. Gold color in dental alloys.

    Science.gov (United States)

    Cameron, T

    1997-01-01

    This article will help the dental laboratory with alloy selection by exploring how the relationship among color, ductility and strength applies to gold and how color can be quantified. Because higher quality materials translate into higher profits, upselling to the dentist and patient is also discussed.

  1. Ultrafast vibrations of gold nanorings

    DEFF Research Database (Denmark)

    Kelf, T; Tanaka, Y; Matsuda, O;

    2011-01-01

    We investigate the vibrational modes of gold nanorings on a silica substrate with an ultrafast optical technique. By comparison with numerical simulations, we identify several resonances in the gigahertz range associated with axially symmetric deformations of the nanoring and substrate. We elucid...

  2. Directed Assembly of Gold Nanoparticles

    DEFF Research Database (Denmark)

    Westerlund, Axel Rune Fredrik; Bjørnholm, Thomas

    2009-01-01

    As a complement to common "top-down" lithography techniques, "bottom-up" assembly techniques are emerging as promising tools to build nanoscale structures in a predictable way. Gold nanoparticles that are stable and relatively easy to synthesize are important building blocks in many such structures...

  3. Gold Medals and Overall Health

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    The 16th Asian Games concluded on November 27 in south China’s Guangzhou, Guangdong Province. The Chinese delegation set new records, with its number of gold medals and total medals, both far more than any other Asian countries and regions.

  4. Metallic gold beads in hyaluronic acid

    DEFF Research Database (Denmark)

    Pedersen, Dan Sonne; Tran, Thao Phuong; Smidt, Kamille;

    2013-01-01

    . In conclusion, our findings support that bio-liberation of gold from metallic gold surfaces have anti-inflammatory properties similar to classic gold compounds, warranting further studies into the pharmacological potential of this novel gold-treatment and the possible synergistic effects of hyaluronic acid....... investigates the anti-inflammatory properties of metallic gold/HA on the gene expression of tumor necrosis factor (Tnf-α), Interleukin (Il)-1β, Il-6, Il-10, Colony-stimulating factor (Csf)-v2, Metallothionein (Mt)-1/2, Bcl-2 associated X protein (Bax) and B cell lymphoma (Bcl)-2 in cultured J774 macrophages...

  5. Relativistic effects in homogeneous gold catalysis.

    Science.gov (United States)

    Gorin, David J; Toste, F Dean

    2007-03-22

    Transition-metal catalysts containing gold present new opportunities for chemical synthesis, and it is therefore not surprising that these complexes are beginning to capture the attention of the chemical community. Cationic phosphine-gold(i) complexes are especially versatile and selective catalysts for a growing number of synthetic transformations. The reactivity of these species can be understood in the context of theoretical studies on gold; relativistic effects are especially helpful in rationalizing the reaction manifolds available to gold catalysts. This Review draws on experimental and computational data to present our current understanding of homogeneous gold catalysis, focusing on previously unexplored reactivity and its application to the development of new methodology.

  6. Gold nephropathy in juvenile rheumatoid arthritis.

    Science.gov (United States)

    Husserl, F E; Shuler, S E

    1979-01-01

    A 2-year-old girl was treated with gold salts for juvenile rheumatoid arthritis. Treatment had to be discontinued when persistent proteinuria was detected. As this case report indicates, close monitoring of the urine is mandatory during treatment with gold salts to detect early signs of toxicity: hematuria followed by casts and then proteinuria as therapy is continued. Histologic examination with electron microscopy will help to differentiate the different forms of gold toxicity. When the findings are consistent with gold-induced renal involvement, therapy should be discontinued. The gold nephropathy usually resolves in time, with no permanent renal damage.

  7. Hydrofluorination of Alkynes Catalysed by Gold Bifluorides

    OpenAIRE

    Nahra, Fady; Patrick, Scott R.; Bello, Davide; Brill, Marcel; Obled, Alan; Cordes, David B.; Slawin, Alexandra M. Z.; O'Hagan, David; Steven P. Nolan

    2014-01-01

    We report the synthesis of nine new N-heterocyclic carbene gold bifluoride complexes starting from the corresponding N-heterocyclic carbene gold hydroxides. A new methodology to access N,N′-bis(2,6-diisopropylphenyl)imidazol-2-ylidene gold(I) fluoride starting from N,N′-bis(2,6-diisopropylphenyl)imidazol-2-ylidene gold(I) hydroxide and readily available potassium bifluoride is also reported. These gold bifluorides were shown to be efficient catalysts in the hydrofluorination of symmetrical an...

  8. New approach to fabricate nanoporous gold film

    Institute of Scientific and Technical Information of China (English)

    Hui Zhou; Lan Jin; Wei Xu

    2007-01-01

    A simple preparation of ultrathin nanoporous gold film was described. Copper and gold were used to fabricate Cu-Au alloy films through vacuum deposition. The formation of nanoporous gold films from the alloy films involved thermal process and chemical etch by hydrochloric acid or by nitric acid. The free-standing nanoporous gold films have been analyzed by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectrometer (XPS) and surface-enhanced Raman scattering (SERS). It was noted that the nanoporous gold film etched by hydrochloric acid is uniform with a cover of fog-like moieties.

  9. Gold recycling; a materials flow study

    Science.gov (United States)

    Amey, Earle B.

    2000-01-01

    This materials flow study includes a description of trends in consumption, loss, and recycling of gold-containing materials in the United States in 1998 in order to illustrate the extent to which gold is presently being recycled and to identify recycling trends. The quantity of gold recycled, as a percent of the apparent supply of gold, was estimated to be about 30 percent. Of the approximately 446 metric tons of gold refined in the United States in 1998, the fabricating and industrial use losses were 3 percent.

  10. [Biosynthesis of gold nanoparticles by Azospirillum brasilense].

    Science.gov (United States)

    Kupriashina, M A; Vetchinkina, E P; Burov, A M; Ponomareva, E G; Nikitina, V E

    2014-01-01

    Plant-associated nitrogen-fixing soil bacteria Azospirillum brasilense were shown to reduce the gold of chloroauric acid to elemental gold, resulting in formation of gold nanoparicles. Extracellular phenoloxidizing enzymes (laccases and Mn peroxidases) were shown to participate in reduction of Au+3 (HAuCl4) to Au(0). Transmission electron microscopy revealed accumulation of colloidal gold nanoparticles of diverse shape in the culture liquid of A. brasilense strains Sp245 and Sp7. The size of the electron-dense nanospheres was 5 to 50 nm, and the size of nanoprisms varied from 5 to 300 nm. The tentative mechanism responsible for formation of gold nanoparticles is discussed.

  11. The complex nature of phthalocyanine/gold interfaces

    Energy Technology Data Exchange (ETDEWEB)

    Lindner, Susi, E-mail: s.wintz@ifw-dresden.de [IFW Dresden, P.O. Box 270116, D-01171 Dresden (Germany); Treske, Uwe; Knupfer, Martin [IFW Dresden, P.O. Box 270116, D-01171 Dresden (Germany)

    2013-02-15

    We compare the electronic properties of the interface between Au(1 0 0) and cobalt phthalocyanine (CoPc), fluorinated F{sub 16}CoPc as well as CuPc using X-ray photoemission spectroscopy and valence band ultra-violet photoemission spectroscopy. Our results show that in addition to the formation of an interface dipole at the interfaces of CoPc and F{sub 16}CoPc to gold, there is a local charge transfer to the central Co ion, which as a result is reduced to Co(I).

  12. Control of average spacing of OMCVD grown gold nanoparticles

    Science.gov (United States)

    Rezaee, Asad

    Metallic nanostructures and their applications is a rapidly expanding field. Nobel metals such as silver and gold have historically been used to demonstrate plasmon effects due to their strong resonances, which occur in the visible part of the electromagnetic spectrum. Localized surface plasmon resonance (LSPR) produces an enhanced electromagnetic field at the interface between a gold nanoparticle (Au NP) and the surrounding dielectric. This enhanced field can be used for metal-dielectric interfacesensitive optical interactions that form a powerful basis for optical sensing. In addition to the surrounding material, the LSPR spectral position and width depend on the size, shape, and average spacing between these particles. Au NP LSPR based sensors depict their highest sensitivity with optimized parameters and usually operate by investigating absorption peak: shifts. The absorption peak: of randomly deposited Au NPs on surfaces is mostly broad. As a result, the absorption peak: shifts, upon binding of a material onto Au NPs might not be very clear for further analysis. Therefore, novel methods based on three well-known techniques, self-assembly, ion irradiation, and organo-meta1lic chemical vapour deposition (OMCVD) are introduced to control the average-spacing between Au NPs. In addition to covalently binding and other advantages of OMCVD grown Au NPs, interesting optical features due to their non-spherical shapes are presented. The first step towards the average-spacing control is to uniformly form self-assembled monolayers (SAMs) of octadecyltrichlorosilane (OTS) as resists for OMCVD Au NPs. The formation and optimization of the OTS SAMs are extensively studied. The optimized resist SAMs are ion-irradiated by a focused ion beam (Fill) and ions generated by a Tandem accelerator. The irradiated areas are refilled with 3-mercaptopropyl-trimethoxysilane (MPTS) to provide nucleation sites for the OMCVD Au NP growth. Each step during sample preparation is monitored by

  13. Mammalian sensitivity to elemental gold (Au?)

    Science.gov (United States)

    Eisler, R.

    2004-01-01

    There is increasing documentation of allergic contact dermatitis and other effects from gold jewelry, gold dental restorations, and gold implants. These effects were especially pronounced among females wearing body-piercing gold objects. One estimate of the prevalence of gold allergy worldwide is 13%, as judged by patch tests with monovalent organogold salts. Eczema of the head and neck was the most common response of individuals hypersensitive to gold, and sensitivity can last for at least several years. Ingestion of beverages containing flake gold can result in allergic-type reactions similar to those seen in gold-allergic individuals exposed to gold through dermal contact and other routes. Studies with small laboratory mammals and injected doses of colloidal gold showed increased body temperatures, accumulations in reticular cells, and dose enhancement in tumor therapy; gold implants were associated with tissue injuries. It is proposed that Au? toxicity to mammals is associated, in part, with formation of the more reactive Au+ and Au3+ species.

  14. Leaching behavior of butanedionedioxime as gold ligand

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Butanedionedioxime, a small organic compound with low-toxicity and good chemical stability, has been proposed as an effective gold ligand in gold extraction. The result of experiment shows that: 1) highly effective gold lixiviantcan be composed of butanedionedioxime (BDM) with many oxidants, especially potassium permanganate; 2)in the leaching system of BD M- K M nO4 the suitable Ox/Lig(ratio of oxidants to gold ligands) tange is 0.20 ~ 0. 50, optimally 0.25 ~0.45 at the pH range of 7 ~ 11; 3) BDM-KMnO4 extraction of gold from an oxide ore is similar to cyanide(cyanide-O2)extraction, but the leaching rate of gold by BDM-KMnO4 is faster than that by cyanide-O2; 4) gold may readily be recov-ered by carbon adsorption and zinc precipitation

  15. Cyto- and genotoxicity assessment of Gold nanoparticles obtained by laser ablation in A549 lung adenocarcinoma cells

    Energy Technology Data Exchange (ETDEWEB)

    Bucchianico, Sebastiano Di [Karolinska Institutet, Institute of Environmental Medicine (Sweden); Migliore, Lucia [University of Pisa, Department of Translational Research and New Technologies in Medicine and Surgery, Division of Medical Genetics (Italy); Marsili, Paolo [Institute of Complex Systems (ISC-CNR) (Italy); Vergari, Chiara [Plasma Diagnostics and Technologies s.r.l. (Italy); Giammanco, Francesco [University of Pisa, Department of Physics “E. Fermi” (Italy); Giorgetti, Emilia, E-mail: emilia.giorgetti@fi.isc.cnr.it [Institute of Complex Systems (ISC-CNR) (Italy)

    2015-05-15

    Gold nanoparticles have attracted enormous interest in biomedical applications, based on their unique optical properties. However, their toxicity on human tissues is still an open issue. Beyond the potential intrinsic toxicity of nanostructured gold, a non-negligible contribution of stabilizers or reaction by-products related to current wet chemical synthesis procedures can be expected. Aimed at isolating gold contribution from that of any other contaminant, we produced colloidal suspensions of Gold nanoparticles having average size <10 nm in deionized water or acetone by pulsed laser ablation, that permits preparation of uncoated and highly stable Gold nanoparticles in pure solvents. Subsequently, we investigated the role of surface chemistry, size, and dispersivity of synthesized Gold nanoparticles in exerting toxicity in a cell model system of deep respiratory tract, representing the main route of exposure to NPs, namely adenocarcinoma epithelial A549 cells. Gold nanoparticles prepared in water showed no particular signs of cytotoxicity, cytostasis, and/or genotoxicity as assessed by MTT colorimetric viability test and Cytokinesis-block micronucleus cytome assay up to concentrations of the order of 5 μg/mL. In contrast, Gold nanoparticles produced in pure acetone and then transferred into deionized water showed impaired cell viability, apoptosis responses, micronuclei, and dicentric chromosomes induction as well as nuclear budding, as a function of the amount of surface contaminants like amorphous carbon and enolate ions.

  16. The green synthesis of gold nanoparticles using the ethanol extract pf black tea and its tannin free fraction

    International Nuclear Information System (INIS)

    In this research the ethanol extract of black tea and its tannin free fraction used for green synthesis of gold nanoparticles. All the extracts were used separately for the synthesis of gold nanoparticles through the reduction of aqueous AuCl4-. Transmission electron microscopy and visible absorption spectroscopy confirmed the reduction of gold ions to gold nanoparticles. The ethanol extract of black tea and its tannin free ethanol extract produced gold nanoparticles in the size ranges of 2.5-27.5 nm and 1.25-17.5 nm with an average size of 10 nm and 3 nm, respectively. The prepared colloid gold nanoparticles, using the ethanol extract of black tea, did not show the appropriate stability during storage time (24 hours) at 4degC. In contrast, gold colloids, which were synthesized by a tannin free fraction showed no particle aggregation during short and long storage times at the same conditions. To the best of our knowledge, this is the first report on the rapid synthesis of gold nanoparticles using ethanol extract of black tea and its tannin free fraction.

  17. Cyto- and genotoxicity assessment of Gold nanoparticles obtained by laser ablation in A549 lung adenocarcinoma cells

    International Nuclear Information System (INIS)

    Gold nanoparticles have attracted enormous interest in biomedical applications, based on their unique optical properties. However, their toxicity on human tissues is still an open issue. Beyond the potential intrinsic toxicity of nanostructured gold, a non-negligible contribution of stabilizers or reaction by-products related to current wet chemical synthesis procedures can be expected. Aimed at isolating gold contribution from that of any other contaminant, we produced colloidal suspensions of Gold nanoparticles having average size <10 nm in deionized water or acetone by pulsed laser ablation, that permits preparation of uncoated and highly stable Gold nanoparticles in pure solvents. Subsequently, we investigated the role of surface chemistry, size, and dispersivity of synthesized Gold nanoparticles in exerting toxicity in a cell model system of deep respiratory tract, representing the main route of exposure to NPs, namely adenocarcinoma epithelial A549 cells. Gold nanoparticles prepared in water showed no particular signs of cytotoxicity, cytostasis, and/or genotoxicity as assessed by MTT colorimetric viability test and Cytokinesis-block micronucleus cytome assay up to concentrations of the order of 5 μg/mL. In contrast, Gold nanoparticles produced in pure acetone and then transferred into deionized water showed impaired cell viability, apoptosis responses, micronuclei, and dicentric chromosomes induction as well as nuclear budding, as a function of the amount of surface contaminants like amorphous carbon and enolate ions

  18. Straggling of heavy ions in aluminium

    International Nuclear Information System (INIS)

    An effort has been made to determine the straggling in aluminium of 4He, 16O and 35Cl ions of different energies produced by the tandem Van de Graaff at Harwell. The technique consists of scattering the accelerated and collimated ions in a scattering chamber from a 0.100 mg/cm2 gold foil, allowing the scattered ions to pass through a two aperture collimator, using different aluminium foils over one of the apertures and stopping the two emergent beams in a good quality silicon surface barrier detector the output of which is connected to a 4096 channel analyser. The energy widths obtained in the case of helium ions are in fair agreement with both the Bloch and the recent Tschalar (1968) theory. The measured widths in the case of heavy ions are very large and can be explained only if account is taken of their charge distributions in foils. This study should be useful in ion implantation work. (author)

  19. [Contact allergy to gold and its alloys. Pertinence of gold salt patch tests].

    Science.gov (United States)

    Collet, E; Lacroix, M; Dalac, S; Ponnelle, C; Lambert, D

    1994-01-01

    Allergic contact dermatitis to gold and its alloys is a rare affection and it is difficult to interpret gold salts patch tests. We report two cases of patients with positive patch tests to 0.5% sodium aurothiosulfate discovered during a dermatology exploration of an occupational contact eczema (for the first patient) and an intolerance to gold jewelry (for the second). There is much confusion in the literature concerning the allergologic exploration of contact dermatitis to gold: no standardized test, possible cross reactions between different gold salts, the tests often irritate. The mechanism of sensitization to gold salts is unknown since pure gold is inalterable and does not contain any salts. The pertinence of a positive test to one or more gold salts must therefore be examined carefully and the diagnosis of gold allergy must not be made without sufficient evidence.

  20. 杏核的活性壳:一种用于黄金回收的有价值的吸附剂%Activated Hard Shell of Apricot Stones: A Promising Adsorbent in Gold Recovery

    Institute of Scientific and Technical Information of China (English)

    Mansooreh Soleimani; Tahereh Kaghazchi

    2008-01-01

    Activated carbon has been proven to be an effective adsorbent for the recovery of a wide variety of metal ions from aqueous solutions. In this research, the activated hard shell of Iranian apricot stones was used for gold recovery from electro-plating wastewater. The effect of parameters such as dose and particle size of adsorbent,pH, agitation speed of mixing on the gold recovery was investigated. The results showed that under the optimum operating conditions more than 98% of gold ions were adsorbed onto activated carbon after just 3 h. In addition, the adsorbed gold could be eluted from this adsorbent by improved striping method. The process involves contact of gold-laden adsorbent with a strong base at ambient temperatures followed by elution with an aqueous solution con-taining an organic solvent. It was found that activated hard shell of apricot stones has the potential to replace im-ported commercial activated carbons in gold adsorption processes.

  1. Gold-Speckled Multimodal Nanoparticles for Noninvasive Bioimaging

    Science.gov (United States)

    2008-01-01

    In this report the synthesis, characterization, and functional evaluation of a multimodal nanoparticulate contrast agent for noninvasive imaging through both magnetic resonance imaging (MRI) and photoacoustic tomography (PAT) is presented. The nanoparticles described herein enable high resolution and highly sensitive three-dimensional diagnostic imaging through the synergistic coupling of MRI and PAT capabilities. Gadolinium (Gd)-doped gold-speckled silica (GSS) nanoparticles, ranging from 50 to 200 nm, have been prepared in a simple one-pot synthesis using nonionic microemulsions. The photoacoustic signal is generated from a nonuniform, discontinuous gold nanodomains speckled across the silica surface, whereas the MR contrast is provided through Gd incorporated in the silica matrix. The presence of a discontinuous speckled surface, as opposed to a continuous gold shell, allows sufficient bulk water exchange with the Gd ions to generate a strong MR contrast. The dual imaging capabilities of the particles have been demonstrated through in silicio and in vitro methods. The described particles also have the capacity for therapeutic applications including the thermal ablation of tumors through the absorption of irradiated light. PMID:19466201

  2. Amorphous carbon interlayers for gold on elastomer stretchable conductors

    Science.gov (United States)

    Manzoor, M. U.; Tuinea-Bobe, C. L.; McKavanagh, F.; Byrne, C. P.; Dixon, D.; Maguire, P. D.; Lemoine, P.

    2011-06-01

    Gold on polydimethylsiloxane (PDMS) stretchable conductors were prepared using a novel approach by interlacing an hydrogenated amorphous carbon (a-C : H) layer between the deposited metal layer and the elastomer. AFM analysis of the a-C : H film surface before gold deposition shows nanoscale buckling, the corresponding increase in specific surface area corresponds to a strain compensation for the first 4-6% of bi-axial tensile loading. Without this interlayer, the deposited gold films show much smaller and uni-directional ripples as well as more cracks and delaminations. With a-C : H interlayer, the initial electrical resistivity of the metal film decreases markedly (280-fold decrease to 8 × 10-6 Ω cm). This is not due to conduction within the carbon interlayer; both a-C : H/PDMS and PDMS substrates are electrically insulating. Upon cyclic tensile loading, both films become more resistive, but return to their initial state after 20 tensile cycles up to 60% strain. Profiling experiments using secondary ion mass spectroscopy and x-ray photoelectron spectroscopy indicate that the a-C : H layer intermixes with the PDMS, resulting in a graded layer of decreasing stiffness. We believe that both this graded layer and the surface buckling contribute to the observed improvement in the electrical performance of these stretchable conductors.

  3. 一种简单快速检测汞离子的1,4-二硫苏糖醇膜修饰金平板电极%Simple and Rapid Determination of Mercury Ions Based on 1,4-Dithiothreitol Assembled Gold Plate Electrode

    Institute of Scientific and Technical Information of China (English)

    曹婷婷; 曹忠; 何婧琳; 梁海琴; 肖忠良

    2014-01-01

    将1,4-二硫苏糖醇(DTT)自组装在100 nm 厚的平整金膜表面,形成 DTT 膜修饰金平板电极(GPE),构建了一种新颖的简单、快速测定汞离子的选择性电极分析方法.通过电化学交流阻抗和循环伏安法探讨了该电极的响应原理,即固定在 Au 表面的 DTT 通过另一端的巯基与汞离子发生强配位作用而吸附结合带正电荷的汞离子,引起电极表面膜电位的变化,从而选择性地识别汞离子.实验结果表明,该电极在 pH =6.0的 Tris-HCl 缓冲溶液中对汞离子有良好的电位响应性能,其线性范围为1.0×10-8~1.0×10-3 mol/ L,能斯特响应斜率为(29.62±0.2) mV/-pc(25℃),检出限为5.1×10-9 mol/ L.该汞离子检测电极的响应时间仅为20 s,且有较好的重现性和稳定性.通过测定各种离子的选择性系数,发现 Cu2+, Fe2+, Na+, K+, Mg2+, Ba2+, Ca2+, Zn2+, Sn2+, Pb2+, Ag+, Al3+, Fe3+, Ni2+, NO-2, IO-3, BrO-3和 ClO-3等离子不干扰该电极对汞离子的检测.此外,将该电极用于实际水样中微量汞离子含量的测定,结果与双硫腙分光光度方法一致,且回收率为98.20%~101.75%.%A simply gold plate electrode(GPE) based on 1,4-dithiothreitol(DTT), which was self-assembled on a surface of flat gold film with a thickness of 100 nm, was developed to construct a novel selective electrode method for rapid detection of mercury ion. Through electrochemical impedance analysis and cyclic voltamme-tric method, the response mechanism of the electrode for selective recognition of Hg2+ was investigated, that the other terminal sulfhydryl group of DTT binding to Au surface can coordinate with Hg2+ due to their strong complexing interaction, resulting in change of membrane potential of the electrode surface. The proposed elec-trode possesses good potential performance responding to Hg2+ with a linear range of 1. 0 ×10-8-1. 0 ×10-3 mol/ L, a Nernst slope of (29. 62±0. 2) mV/ -pc(25 ℃), and a detection limit of 5. 1×10-9 mol/ L

  4. Von Gold Plasmonen und Exzitonen : Synthese, Charakterisierung und Applikationen von Gold Nanopartikeln

    OpenAIRE

    Bomm, Jana

    2013-01-01

    In dieser Arbeit wurden sphärische Gold Nanopartikel (NP) mit einem Durchmesser größer ~ 2 nm, Gold Quantenpunkte (QDs) mit einem Durchmesser kleiner ~ 2 nm sowie Gold Nanostäbchen (NRs) unterschiedlicher Länge hergestellt und optisch charakterisiert. Zudem wurden zwei neue Synthesevarianten für die Herstellung thermosensitiver Gold QDs entwickelt werden. Sphärische Gold NP zeigen eine Plasmonenbande bei ~ 520 nm, die auf die kollektive Oszillation von Elektronen zurückzuführen ist. Gold NRs ...

  5. Analysis of gold and silver concentration on gold mining tailings by neutron activation analysis

    International Nuclear Information System (INIS)

    Full text: Instrumental neutron-activation analysis without radiochemical separation is one of most applicable and often used methods to analyze the concentration of gold, silver and other rare and noble metals in gold ores. This method is not suitable for analyzing low concentration of gold and silver in gold mining tailings due to rather high concentration of some elements. Samples are dissolved by boiling in a mixture of concentrated hydrochloric and nitric acids to extract gold and silver into the solution. Chemical yield of gold and silver after dissolution of the sample and further chromatographic separation is between 92 and 95 percent respectively

  6. Switchable Imbibition in Nanoporous Gold

    CERN Document Server

    Xue, Yahui; Duan, Huiling; Weissmueller, Joerg; Huber, Patrick

    2014-01-01

    Spontaneous imbibition enables the elegant propelling of nano-flows because of the dominance of capillarity at small length scales. The imbibition kinetics are, however, solely determined by the static geometry of the porous host, the capillarity, and the fluidity of the imbibed liquid. This makes active control particularly challenging. Here, we show for aqueous electrolyte imbibition in nanoporous gold that the fluid flow can be reversibly switched on and off through electric potential control of the solid-liquid interfacial tension, i.e. we can accelerate the imbibition front, stop it, and have it proceed at will. Simultaneous measurements of the mass flux and the electrical current allow us to document simple scaling laws for the imbibition kinetics, and to explore the charge flow dynamics in the metallic nanopores. Our findings demonstrate that the high electric conductivity along with the pathways for ionic and/or fluid transport render nanoporous elemental gold a versatile, accurately controllable elec...

  7. CMS Industries awarded gold, crystal

    CERN Multimedia

    2006-01-01

    The CMS collaboration honoured 10 of its top suppliers in the seventh annual awards ceremony The representatives of the firms that recieved the CMS Gold and Crystal Awards stand with their awards after the ceremony. The seventh annual CMS Awards ceremony was held on Monday 13 March to recognize the industries that have made substantial contributions to the construction of the collaboration's detector. Nine international firms received Gold Awards, and General Tecnica of Italy received the prestigious Crystal Award. Representatives from the companies attended the ceremony during the plenary session of CMS week. 'The role of CERN, its machines and experiments, beyond particle physics is to push the development of equipment technologies related to high-energy physics,'said CMS Awards Coordinator Domenico Campi. 'All of these industries must go beyond the technologies that are currently available.' Without the involvement of good companies over the years, the construction of the CMS detector wouldn't be possible...

  8. Efficient coupling and transport of a surface plasmon at 780 nm in a gold nanostructure

    Science.gov (United States)

    Gong, Yu; Joly, Alan G.; El-Khoury, Patrick Z.; Hess, Wayne P.

    2015-08-01

    We study plasmonic nanostructures in single-crystal gold with scanning electron and femtosecond photoemission electron microscopies. We design an integrated laser coupling and nanowire waveguide structure by focused ion beam lithography in single-crystal gold flakes. The photoemission results show that the laser field is efficiently coupled into a propagating surface plasmon by a simple hole structure and propagates efficiently in an adjacent nano-bar waveguide. A strong local field is created by the propagating surface plasmon at the nano-bar tip. A similar structure, with a decreased waveguide width and thickness, displayed significantly more intense photoemission indicating enhanced local electric field at the sharper tip.

  9. Efficient Coupling and Transport of a Surface Plasmon at 780 nm in a Gold Nanostructure

    Energy Technology Data Exchange (ETDEWEB)

    Gong, Yu; Joly, Alan G.; El-Khoury, Patrick Z.; Hess, Wayne P.

    2015-08-28

    We studied plasmonic nanostructures in single-crystal gold with scanning electron and femtosecond photoemission electron microscopies. We designed an integrated laser coupling and nanowire waveguide structure by focused ion beam lithography in single-crystal gold flakes. The photoemission results show that the laser field is efficiently coupled into a propagating surface plasmon by a simple hole structure and propagates efficiently in an adjacent nano-bar waveguide. A strong local field is created by the propagating surface plasmon at the nano-bar tip. A similar structure, with a decreased waveguide width and thickness, displayed significantly more intense photoemission indicating enhanced local electric field at the sharper tip.

  10. Visual test and colorimetric determination of gold(III) with the use of indicator paper

    OpenAIRE

    Khudyakova, Svetlana N.; Kolesnikova, Еkaterina L.; Kholodelshchikova, Julіya A.

    2016-01-01

    A visual test method has been proposed for the evaluation of the gold content. It is based on the linear dependence between the length of the colored zone on an indicator paper and gold(III) concentration. Indicator paper was covered by a polymer film and was in contact with the solution tested along one edge during analysis. It was impregnated by 3-phenyl-2,6-dimercapto-1,4-thiopyrone or by precipitate of its complex with copper(II). Besides Cu(II) can be replaced by the Au(III) ion tested i...

  11. Invisible gold in Colombian auriferous soils

    Science.gov (United States)

    Bustos Rodriguez, H.; Oyola Lozano, D.; Rojas Martínez, Y. A.; Pérez Alcázar, G. A.; Balogh, A. G.

    2005-11-01

    Optic microscopy, X-ray diffraction (XRD), Mössbauer spectroscopy (MS), Electron microprobe analysis (EPMA) and secondary ions mass spectroscopy (SIMS) were used to study Colombian auriferous soils. The auriferous samples, collected from El Diamante mine, located in Guachavez-Nariño (Colombia), were prepared by means of polished thin sections and polished sections for EPMA and SIMS. Petrography analysis was made using an optical microscope with a vision camera, registering the presence, in different percentages, of the following phases: pyrite, quartz, arsenopyrite, sphalerite, chalcopyrite and galena. By XRD analysis, the same phases were detected and their respective cell parameters calculated. By MS, the presence of two types of pyrite was detected and the hyperfine parameters are: δ 1 = 0.280 ± 0.01 mm/s and Δ Q 1 = 0.642 ± 0.01 mm/s, δ 2 = 0.379 ± 0.01 mm/s and Δ Q 2 = 0.613 ± 0.01 mm/s. For two of the samples MS detected also the arsenopyrite and chalcopyrite presence. The mean composition of the detected gold regions, established by EPMA, indicated 73% Au and 27% Ag (electrum type). Multiple regions of approximately 200 × 200 μm of area in each mineral sample were analyzed by SIMS registering the presence of “invisible gold” associated mainly with the pyrite and occasionally with the arsenopyrite.

  12. Synthesis of One Dimensional Gold Nanostructures

    Directory of Open Access Journals (Sweden)

    Hongchen Li

    2010-01-01

    Full Text Available Gold nanostructures with shapes of rod, dumbbells, and dog bone have been fabricated by an improved seed-mediated method. It is found that the pH change (the addition of HNO3 or HCl and the presence of Ag+ ions have a great influence on the growth process and aspect ratios of these Au nanocrystals. UV-Vis-NIR absorption spectra for the Au colloidal show that the transverse plasmon absorption band locates at ~520 nm, while the longitudinal plasmon absorption band shifts in a wide spectra region of 750–1100 nm. The obtained Au nanostructures have been investigated by transmission electron microscopy, high-resolution transmission electron microscopy, and X-ray diffractometer. Based on the characterizations and FDTD simulations, most of the obtained Au nanorods are single crystals, possessing an octagonal cross-section bounded by {110} and {100} faces. One model for the anisotropic growth has been proposed. It is found that slow kinetics favor the formation of single-crystalline Au nanorods.

  13. Citrate-Stabilized Gold Nanorods

    OpenAIRE

    Mehtala, Jonathan G; Zemlyanov, Dmitry Y.; Max, Joann P.; Kadasala, Naveen; Zhao, Shou; Wei, Alexander

    2014-01-01

    Stable aqueous dispersions of citrate-stabilized gold nanorods (cit-GNRs) have been prepared in scalable fashion by surfactant exchange from cetyltrimethylammonium bromide (CTAB)-stabilized GNRs, using polystyrenesulfonate (PSS) as a detergent. The surfactant exchange process was monitored by infrared spectroscopy, surface-enhanced Raman scattering (SERS), and X-ray photoelectron spectroscopy (XPS). The latter established the quantitative displacement of CTAB (by PSS) and of PSS (by citrate)....

  14. Mikroscherversuche an Gold-Einkristallen

    OpenAIRE

    Heyer, Jenna-Kathrin

    2014-01-01

    In der vorliegenden Arbeit sollte ein Mikroscherexperiment entwickelt werden, das reproduzierbare mechanische Daten liefert und welches gestattet, die Proben während der Verformung im Rasterelektronenmikroskop (REM) zu beobachten. Dazu wurde eine Doppelscher-Mikroprobe verwendet und mit der flachen Spitze eines Nanoindentationssystems, das in ein modernes REM integriert ist, verformt. Die Versuche wurden an Gold-Einkristallen durchgeführt, die so hergestellt wurden, dass das krist...

  15. Biomolecular Assembly of Gold Nanocrystals

    Energy Technology Data Exchange (ETDEWEB)

    Micheel, Christine Marya [Univ. of California, Berkeley, CA (United States)

    2005-05-20

    Over the past ten years, methods have been developed to construct discrete nanostructures using nanocrystals and biomolecules. While these frequently consist of gold nanocrystals and DNA, semiconductor nanocrystals as well as antibodies and enzymes have also been used. One example of discrete nanostructures is dimers of gold nanocrystals linked together with complementary DNA. This type of nanostructure is also known as a nanocrystal molecule. Discrete nanostructures of this kind have a number of potential applications, from highly parallel self-assembly of electronics components and rapid read-out of DNA computations to biological imaging and a variety of bioassays. My research focused in three main areas. The first area, the refinement of electrophoresis as a purification and characterization method, included application of agarose gel electrophoresis to the purification of discrete gold nanocrystal/DNA conjugates and nanocrystal molecules, as well as development of a more detailed understanding of the hydrodynamic behavior of these materials in gels. The second area, the development of methods for quantitative analysis of transmission electron microscope data, used computer programs written to find pair correlations as well as higher order correlations. With these programs, it is possible to reliably locate and measure nanocrystal molecules in TEM images. The final area of research explored the use of DNA ligase in the formation of nanocrystal molecules. Synthesis of dimers of gold particles linked with a single strand of DNA possible through the use of DNA ligase opens the possibility for amplification of nanostructures in a manner similar to polymerase chain reaction. These three areas are discussed in the context of the work in the Alivisatos group, as well as the field as a whole.

  16. Jabiluka gold-uranium project

    International Nuclear Information System (INIS)

    The Jabiluka gold-uranium deposit, 230km east of Darwin in the Alligator Rivers Region of the Northern Territory, was discovered by Pancontinental Mining Limited in 1971. Jabiluka, with reserves in excess of 200,000 tonnes of contained U3O8 in two deposits 500 metres apart, is the world's largest high grade uranium deposit and also contains nearly 12 tonnes of gold. It is proposed that only the larger deposit, Jabiluka II will be mined - by underground extraction methods, and that 275,000 tonnes of ore per year will be mined and processed to produce 1,500 tonnes of U3O8 and up to 30,000 oz of gold. The revenue from the uranium sales is estimated to be of the order of A$100 million per year at A$30/lb. By the end of 1982 all necessary mining and environmental approvals had been obtained and significant marketing progress made. With the Australian Labor Party winning Commonwealth Government in the 1983 election, Pancontinental's permission to seek sales contracts was withdrawn and development of the Jabiluka deposit ceased. Jabiluka remains undeveloped - awaiting a change in Australian Government policy on uranium. figs., maps

  17. CO extrusion in homogeneous gold catalysis: reactivity of gold acyl species generated through water addition to gold vinylidenes.

    Science.gov (United States)

    Bucher, Janina; Stößer, Tim; Rudolph, Matthias; Rominger, Frank; Hashmi, A Stephen K

    2015-01-26

    Herein, we describe a new gold-catalyzed decarbonylative indene synthesis. Synergistic σ,π-activation of diyne substrates leads to gold vinylidene intermediates, which upon addition of water are transformed into gold acyl species, a type of organogold compound hitherto only scarcely reported. The latter are shown to undergo extrusion of CO, an elementary step completely unknown for homogeneous gold catalysis. By tuning the electronic and steric properties of the starting diyne systems, this new reactivity could be exploited for the synthesis of indene derivatives in high yields.

  18. Visualizing expanding warm dense matter heated by laser-generated ion beams

    Energy Technology Data Exchange (ETDEWEB)

    Bang, Woosuk [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2015-08-24

    This PowerPoint presentation concluded with the following. We calculated the expected heating per atom and temperatures of various target materials using a Monte Carlo simulation code and SESAME EOS tables. We used aluminum ion beams to heat gold and diamond uniformly and isochorically. A streak camera imaged the expansion of warm dense gold (5.5 eV) and diamond (1.7 eV). GXI-X recorded all 16 x-ray images of the unheated gold bar targets proving that it could image the motion of the gold/diamond interface of the proposed target.

  19. CO oxidation on gold nanoparticles: Theoretical studies

    DEFF Research Database (Denmark)

    Remediakis, Ioannis; Lopez, Nuria; Nørskov, Jens Kehlet

    2005-01-01

    We present a summary of our theoretical results regarding CO oxidation on both oxide-supported and isolated gold nanoparticles. Using Density Functional Theory we have studied the adsorption of molecules and the oxidation reaction of CO on gold clusters. Low-coordinated sites on the gold nanopart......We present a summary of our theoretical results regarding CO oxidation on both oxide-supported and isolated gold nanoparticles. Using Density Functional Theory we have studied the adsorption of molecules and the oxidation reaction of CO on gold clusters. Low-coordinated sites on the gold...... efficiency of Au-based catalysts. Finally, our theoretical simulations allow us to discuss the selectivity of supported Au nanoparticles....

  20. Feasibilty of electroplated gold for hybrid microcircuits

    Energy Technology Data Exchange (ETDEWEB)

    Blessner, P.L.

    1978-01-01

    Electroplating was investigated as a method of providing thick gold films. Because electroplated gold has never been used for hybrid microcircuit (HMC) substrate metallization, this feasibility study was also designed to determine the characteristics of electroplated gold and its compatibility with present HMC fabrication processes. Ceramic substrates 95 by 114 mm (3.75 by 4.5 in.) were electroplated with 6, 10, and 25 ..mu..m of gold after 0.02 ..mu..m of chromium and 0.5 ..mu..m of gold had been either sputtered or vacuum evaporated onto the substrate surfaces. Substrates vacuum evaporated with 6 ..mu..m of gold were used as a control group. The substrates were evaluated for via resistance, RF electrical characteristics, conductor definition and resolution, solder wettability, thermocompression bondability, and environmental stability.

  1. Application of Gold Nanoparticles to Paint Colorants

    Science.gov (United States)

    Ishibashi, Hideo

    Metal nanoparticles possess unique properties that they do not exhibit in their bulk states. One of these properties is the color due to surface plasmon resonance. Gold nanoparticles appear red. This color has been utilized in glass for a long long time. In recent years, highly concentrated pastes of gold and silver nanoparticles have been successfully produced by using a special type of protective polymer and a mild reductant. The paste of gold nanoparticles can be used for paint and other materials as red colorants. In this article,application examples of gold nanoparticles as colorant are introduced. Recently, methods for producing bimetal nanoparticles such as gold/silver and gold/copper have been developed. These nanoparticles allow colors from yellow to green to be created. These methods and colors they produce are also described in this article.

  2. Physiological investigation of gold nanorods toward watermelon.

    Science.gov (United States)

    Wan, Yujie; Li, Junli; Ren, Hongxuan; Huang, Jin; Yuan, Hong

    2014-08-01

    The objective of the present study was to evaluate the phytotoxicity and oxidant stress of the gold nanorods toward watermelon, and hence give a quantitative risk assessment of both seeds and plants phase. The seed germination, the activity of antioxidant enzymes, and the contents of soluble protein and malondialdehyde (MDA) have been measured while the plant roots were observed by transmission electron microscopy (TEM). It was found that the gold nanorods significantly promoted the root elongation. Furthermore, the results on the enzymes activities of plant indicated that oxidative stress happened in the plant treated with gold nanorods. However, the gold nanorods resulted in the phytotoxicity toward plant especially at high concentration. The TEM images of the plant roots with and without the treatment of gold nanorods showed the significant different size of starch granules. In conclusion, significant physiological changes of plant occurred after treatment with the gold nanorods. PMID:25936063

  3. Linear Optical Properties of Gold Colloid

    Directory of Open Access Journals (Sweden)

    Jingmin XIA

    2015-11-01

    Full Text Available Gold colloid was prepared by reducing HAuCl4·4H2O with Na3C6H5O7·2H2O. The morphology, size of gold nanoparticles and the optical property of colloid were characterized by transmission electron microscope and UV-Vis spectrophotometer, respectively. It shows that the gold nanoparticles are in the shape of spheres with diameters less than 8 nm, and the surface plasmon resonance absorption peak is located at about 438 nm. As the volume fraction of gold particles increases, the intensity of absorption peak strengthens. The optical property of gold colloid was analyzed by Maxwell-Garnett (MG effective medium theory in the company of Drude dispersion model. The results show that the matrix dielectric constant is a main factor, which influences the optical property of gold colloid.DOI: http://dx.doi.org/10.5755/j01.ms.21.4.9558

  4. Dielectric function of non-equilibrium warm dense gold

    Science.gov (United States)

    Ping, Yuan

    2009-06-01

    Warm dense matter lies in a regime where densities are near the solid density and temperatures are between 0.1 and 100 eV. The behavior of such systems is dominated by electron degeneracy, excited electronic states and ion-ion correlations, rendering them a truly daunting many-body problem. Interest in Warm Dense Matter has been growing among broad disciplines as driven by the fundamental urge to understand the convergence between plasma and condensed matter physics, and the practical need to understand dynamic behavior in the transformation of a cold solid into a high energy density plasma. A recent advance in this emerging field is the single state measurements of optical properties of non-equilibrium warm dense gold created by isochoric laser heating. This unveils for the first time the behavior of intraband and interband transitions in warm dense gold at high energy densities, providing a unique opportunity to examine effects of electron band structure and electron distribution. This talk is a review of the experimental technique and the new findings. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. [4pt] In collaboration with Andrew Ng, Tadashi Ogitsu, Eric Schwegler, David Prendergast, Byong-ick Cho, Phil Heimann, Tommy Ao, Klaus Widmann, Duncan Hanson, Ingrid Koslow, and Gilbert Collins.

  5. Hydrogen oxidation on gold electrode in perchloric acid solution

    Energy Technology Data Exchange (ETDEWEB)

    Sustersic, M.G.; Almeida, N.V.; Von Mengershausen, A.E. [Facultad de Ingenieria y Ciencias Economico Sociales, Universidad Nacional de San Luis, 25 de Mayo N 384, 5730 Villa Mercedes, San Luis (Argentina)

    2010-06-15

    The aim of this research is to study the interface gold/perchloric acid solution in presence of hydrogen. The reactive is generated by H{sup +} ion reduction and by saturating the electrolyte with the gaseous H{sub 2}. No evidence of H{sub 2} dissociative adsorption is found. In special conditions, a strongly adsorbed layer is formed from the atoms diffusing from inside of the metal. The mass transport occurs in three ways: the diffusion of H atoms inwards, the diffusion of H atoms back to the surface and the dissolved H{sub 2} diffusion from the bulk electrolyte to the surface. When dissolved H{sub 2} reacts, the reaction is kinetically controlled when the H{sub 2} partial pressure is high, and it is diffusionally controlled when the reactive partial pressure is low. Above 0.7 V, (measured vs. RHE), the (100) plane surface reconstruction lifts, and the rate determining step is the H diffusion towards inside of the metal, and the current suddenly falls. The Hydrogen redox reaction on gold shows reversibility with respect to the potential when the reactives are the H diffusing outwards of the metal and the H{sup +} ion present in the electrolyte. However, the absolute current values of oxidation and reduction are different because the reactive sources are different. (author)

  6. Lattice gas model for fragmentation from argon on scandium to gold on gold

    CERN Document Server

    Das-Gupta, S; Gupta, Subal Das; Pan, Jicai

    1995-01-01

    The recent fragmentation data for central collisions of Gold on Gold are even qualitatively different from those for central collisions of Argon on Scandium. The latter can be fitted with a lattice gas model calculation. Effort is made to understand why the model fails for Gold on Gold. The calculation suggests that the large Coulomb interaction which is operative for the larger system is responsible for this discrepancy. This is demonstrated by mapping the lattice gas model to a molecular dynamics calculation for disassembly. This mapping is quite faithful for Argon on Scandium but deviates strongly for Gold on Gold. The molecular dynamics calculation for disassembly reproduces the characteristics of the fragmentation data for both Gold on Gold and Argon on Scandium.

  7. Gold and Silver Extraction from Leach Solutions

    Directory of Open Access Journals (Sweden)

    Bagdaulet K. Kenzhaliyev

    2014-03-01

    Full Text Available There has been carried out an investigation on the extraction of gold and silver from thiosulfate solutions: standard test and technological solutions of chemical and electrochemical leaching. The influence of related metals on the process of extracting gold from solution was studied. There has been conducted a comparative study of the IR spectra of solutions after the sorption of gold, silver and related metals.

  8. Formation of gold nanoparticles in polymeric nanowires by low-temperature thermolysis of gold mesitylene

    OpenAIRE

    Erk, Christoph; Yau, Man Yan Eric; Lange, Holger; Thomsen, Christian; Miclea, Paul; Ralf B. Wehrspohn; Schlecht, Sabine; Steinhart, Martin

    2012-01-01

    The formation of polymer nanowires containing metal nanoparticle chains by low-temperature thermolyses of metal precursors has remained challenging. We report the block copolymer-assisted generation of locally regular chains of quasi-spherical gold nanoparticles with narrow particle diameter distribution by mild thermolysis of the non-polar gold precursor gold mesitylene inside the cylindrical nanopores of self-ordered anodic aluminium oxide (AAO). The block copolymer separates the gold mesit...

  9. Anodic stripping voltammetry of antimony using gold nanoparticle-modified carbon screen-printed electrodes

    International Nuclear Information System (INIS)

    Carbon screen-printed electrodes (CSPE) modified with gold nanoparticles present an interesting alternative in the determination of antimony using differential pulse anodic stripping voltammetry. Metallic gold nanoparticles deposits have been obtained by direct electrochemical deposition. Scanning electron microscopy measurements show that the electrochemically synthesized gold nanoparticles are deposited in aggregated form. Any undue effects caused by the presence of foreign ions in the solution were also analyzed to ensure that common interferents in the determination of antimony by ASV. The detection limit for Sb(III) obtained was 9.44 x 10-10 M. In terms of reproducibility, the precision of the above mentioned method in %R.S.D. values was calculated at 2.69% (n = 10). The method was applied to determine levels of antimony in seawater samples and pharmaceutical preparations

  10. Reactivity and resizing of gold nanorods in presence of Cu2+

    Indian Academy of Sciences (India)

    T S Sreeprasad; A K Samal; T Pradeep

    2008-06-01

    Due to the inherent anisotropy of the system, gold nanorods behave differently in comparison to their spherical counterparts. Reactivity of gold nanorods, in presence of cupric ions, was probed in an attempt to understand the chemistry of anisotropic particles. The reaction progresses through a series of intermediates. It can be arrested at any stage to get nanorods of desired dimension and therefore, can be used for their reshaping. The presence or absence of cetyltrimethylammonium bromide (CTAB) on the nanorod surface was found to be determining the site of initiation of the reaction. When a large concentration of CTAB is present in the system, selective etching of the tips of the nanorod occurs and when the nanorods are purified to reduce the amount of CTAB in the solution, the side faces of the nanorod also get reacted. Gold nanorods are converted to particles by further surface reconstructions in a systematic surface specific chemistry.

  11. The Effect of Surface Functionalization on the Immobilization of Gold Nanoparticles on Graphene Sheets

    Directory of Open Access Journals (Sweden)

    Min Song

    2012-01-01

    Full Text Available In our study, graphene oxide is synthesized by Hummers method. And then, carboxylic acid functionalized graphene (graphene-COOH, thiol-functionalized graphene (graphene-SH, and highly dispersive graphene are prepared by chemical modification of respective groups on the graphene surface. Furthermore, we explore a solution-based approach to prepare three differently functionalized graphene-gold composites by one-step chemical reduction of AuCl4 - ions in respective functionalized graphene suspensions, where the gold nanoparticles are deposited on the functionalized graphene surface during their synthesis process. In addition, we compare the influence of surface functionalization on the growth of gold nanoparticles on graphene surface. Transmission electron morphology (TEM and ultraviolet-visible (UV-Vis spectroscopy are employed to study the effect of surface functionalities on AuNPs distribution onto the graphene surface and demonstrate the successful immobilization of AuNPs on graphene surface.

  12. Direct effect of tetrahedral alcohol species on the SPB of gold colloids: a deconvolution study

    International Nuclear Information System (INIS)

    Aqueous gold colloids with a mean diameter of 15.4 ± 1.5 nm have been transferred into a range of water–alcohol mixtures. The influence of these mixtures (methanol, ethanol, 2-propanol, and tert-butanol), which present different hydrophobic properties, on the surface plasmon band of gold nanoparticles has been studied. Shifts of gold nanoparticles’ surface plasmon band (SPB) depend on the number of methyl groups and hydrophobic character of the alcohol molecule. Results from deconvolution analysis are explained considering variations on the grade of alcohol adsorption on the nanoparticle surface. TEM images indicate aggregation of the nanoclusters in mixtures of 2-propanol and tert-butanol. ζ potential measurements support the exchange of citrate ions by alcohol molecules, which in turn reflects the existence of an additional electrostatic component

  13. Fabrication of High Aspect Ratio Micro-Penning-Malmberg Gold Plated Silicon Trap Arrays

    CERN Document Server

    Narimannezhad, Alireza; Weber, Marc H; Lynn, Kelvin G

    2013-01-01

    Acquiring a portable high density charged particles trap might consist of an array of micro-Penning-Malmberg traps (microtraps) with substantially lower end barriers potential than conventional Penning-Malmberg traps [1]. We report on the progress of the fabrication of these microtraps designed for antimatter storage such as positrons. The fabrication of large length to radius aspect ratio (1000:1) microtrap arrays involved advanced techniques including photolithography, deep reactive ion etching (DRIE) of silicon wafers to achieve through-vias, gold sputtering of the wafers on the surfaces and inside the vias, and thermal compression bonding of the wafers. This paper describes the encountered issues during fabrication and addresses geometry errors and asymmetries. In order to minimize the patch effects on the lifetime of the trapped positrons, the bonded stacks were gold electroplated to achieve a uniform gold surface. We show by simulation and analytical calculation that how positrons confinement time depen...

  14. A study of Trace Gold Chloride and Hydroxide Speciation in Weak Alkaline Solution by Ion Chromatography-Inductively Coupled Plasma Mass Spectrometry%离子色谱电感耦合等离子体质谱研究痕量氯金酸在弱碱性体系中金(Ⅲ)的形态

    Institute of Scientific and Technical Information of China (English)

    刘德晔; 朱醇; 马永建

    2012-01-01

    A method based on ion chromatography-inductively coupled plasma mass spectrometry(IC-ICP-MS) was developed to study trace gold chloride and hydroxide speciation in weak alkaline solu-tion. The results revealed that, the main compounds in weak alkaline solution were [AuCl2(OH)2]~ and [AuCKOH)3]-when the total Au mass was between 4. 0 30 ng. Unlike high HAuCl4 4H2O concentration, trace [AuCl2 (OH)2]~ could exist between pH 7. 0 to 10. 0, at least. Additional chlo-ride brought promotion to [AuCl2(OH)2]~ and reduction to CAuCl(OH)3]~. When pH was 7. 0 or chloride concentration was above 0. 050 mol/L, AuflE) would generate a compound which could not be flushed out of chromatography system. According to hydrolysis process. that compound was deduced as [AuCl3(OH)]-. The equilibrium constant K3 of [AuCl2(OH)2]- + OH ←[AuCl (OH)3]-+Cl always changed with pH values and chloride concentrations. Therefore, there might exist other factor to influence the trace Au(Ⅲ) hydrolysis.%采用离子色谱电感耦合等离子体质谱联用方法研究弱碱性体系下痕量氯金酸中Au(Ⅲ)的形态.结果表明:在弱碱性条件下,总金含量在4.0~30 ng之间,Au(Ⅲ)主要以[AuCl2( OH)2]-和[AuCl(OH)3]-的形式存在.与较高含量的氯金酸溶渡相比,痕量氯金酸溶液中的[AuCl2(OH)2]-至少可以在pH 7.0~10.0范围内存在.溶液外加的Cl-可使[AuCl2 (OH)2]-含量升高同时降低[AuCl (OH)3]-含量;当pH=7.0或Cl-浓度高于0.050 mol/L,会产生不随色谱流出的金络合物,根据水解过程推断该络合物为[AuC13 (OH)]-.在pH 8.0~10.0,Cl-浓度在0.000~0.020 mol/L时,[AuCl2(OH)2]-+OH-=[AuCl (OH)3]-+Cl-的水解平衡常数为不定值,说明痕量氯金酸的水解不仅受pH值和Cl-浓度影响,还受其它因素影响.

  15. Gold/titania composites: An X-ray absorption spectroscopy study on the influence of the reduction method

    Science.gov (United States)

    Meire, Mieke; Tack, Pieter; De Keukeleere, Katrien; Balcaen, Lieve; Pollefeyt, Glenn; Vanhaecke, Frank; Vincze, Laszlo; Van Der Voort, Pascal; Van Driessche, Isabel; Lommens, Petra

    2015-08-01

    The functionalization of titania based materials with noble metal cocatalysts such as gold or platinum is a well known procedure to improve the catalytic activity of these materials in for example the degradation of organic pollutants or CO conversion. Parameters such as cocatalyst load, noble metal particle size and oxidation state influence the efficiency of these materials. We have impregnated a mesoporous titania powder with a gold salt and used different synthesis routes to reduce the gold ions. A structural analysis was performed using electron microscopy and nitrogen sorption. An X-ray absorption near edge structure spectroscopy study, in both high and low resolution, was performed to investigate the influence of the different reduction methods on the oxidation state of the gold atoms. This technique can also provide information on the local environment of the gold atoms and their interaction with the titanium dioxide host. We found that varying the reduction method has a significant impact on the oxidation state of the gold cocatalysts. This lead to varying interactions with the titania support and charging of the gold nanoparticles.

  16. Preparation and properties of buckypaper-gold nanoparticle composites

    OpenAIRE

    GOUNKO, IOURI; BYRNE, MICHELE THERESE; HANLEY, CORMAC

    2010-01-01

    PUBLISHED Highly conductive buckypaper-gold nanoparticles composites have been prepared by the in situ electroless deposition of gold nanoparticles during the filtration that resulted in increases in conductivities of up to 684% at very low gold content.

  17. Nuclear excitation in muonic gold

    CERN Document Server

    Robert Tissot, B; Debrunner, P; Engfer, R; Link, R; Schellenberg, L; Schneuwly, H; Walter, H K

    1973-01-01

    Energies and intensities of muonic X-rays in gold were measured at the CERN muon channel with an experimental set-up as described by Backe et al. (1972). The 2p-1s and 3d-2p transitions could only be analysed taking into account beside the static quadrupole interaction a dynamical hyperfine interaction of the 2p states, which leads to an excitation of the first four nuclear levels. The dynamical hyperfine interaction was calculated using the core excitation model (de Shalit, (1961)). (0 refs).

  18. Gold-Catalyzed Direct Arylation

    OpenAIRE

    Ball, L. T.; Lloyd-jones, G. C.; Russell, C. A.

    2012-01-01

    Biaryls (two directly connected aromatic rings, Ar1-Ar2) are common motifs in pharmaceuticals, agrochemicals, and organic materials. Current methods for establishing the Ar1-Ar2 bond are dominated by the cross-coupling of aryl halides (Ar1-X) with aryl metallics (Ar2-M). We report that, in the presence of 1 to 2 mole percent of a gold catalyst and a mild oxidant, a wide range of arenes (Ar1-H) undergo site-selective arylation by arylsilanes (Ar2-SiMe3) to generate biaryls (Ar1-Ar2), with litt...

  19. Gold-catalyzed naphthalene functionalization

    OpenAIRE

    Iván Rivilla; M. Mar Díaz-Requejo; Pedro J. Pérez

    2011-01-01

    The complexes IPrMCl (IPr = 1,3-bis(diisopropylphenyl)imidazol-2-ylidene, M = Cu, 1a; M = Au, 1b), in the presence of one equiv of NaBAr'4 (Ar' = 3,5-bis(trifluoromethyl)phenyl), catalyze the transfer of carbene groups: C(R)CO2Et (R = H, Me) from N2C(R)CO2Et to afford products that depend on the nature of the metal center. The copper-based catalyst yields exclusively a cycloheptatriene derivative from the Buchner reaction, whereas the gold analog affords a mixture of products derived either f...

  20. Gold nanoparticle photosensitized radical photopolymerization.

    Science.gov (United States)

    Anyaogu, Kelechi C; Cai, Xichen; Neckers, Douglas C

    2008-12-01

    We report the photopolymerization of an acrylic monomer using thiol-stabilized gold nanoparticles (AuNPs) and [4-[(octyloxy)phenyl] phenyl] iodonium hexafluoroantimonate (OPPI) as photoinitiator and coinitiator, respectively. Polymerization occurred only when the AuNPs, in the presence of the iodonium salt, were irradiated at the particle plasmonic absorption region (lambda>450 nm). The AuNPs activate the coinitiator by intermolecular electron transfer since OPPI has no absorption in the visible region. Fourier transform infrared spectroscopy was used to monitor polymerization. UV-Vis spectroscopy and transmission electron microscopy measurements were used to characterize the NPs. PMID:19037499

  1. Geological characteristics and metallogenic prognosis of main gold deposit in Altai gold ore belt, Xinjiang

    Institute of Scientific and Technical Information of China (English)

    SHEN Yuan-chao; SHEN Ping; ZHENG Qing-dong; LIU Tie-bing; LI Guang-ming

    2004-01-01

    Altai polymetallic mineralization belt is famous copper-polymetallic mineralization belt in the world. There are a lot of gold deposits in the Altai ore belt in Xinjiang, China. These gold deposits belong to two genetic types: volcanogene late-stage hydrothermal type and fractured altered rock type. The authors discuss mainly the geological and mineralized features of fractured altered rock type of gold deposits in Altai gold ore belt. Base on this study, the metallogenic law is summarized and the deep metallogenic prognosis has been done in Duolanasayi and Tuokuzibayi gold deposits, and some mineralized anomalys have been discovered.

  2. Transport and Concentration of Gold in Metamorphic—hosted Reworked Gold Deposits,China

    Institute of Scientific and Technical Information of China (English)

    王声远; 王秀璋; 等

    1993-01-01

    Calculations based on the available thermodynamic data of AuCl2- and Au(HS)2- indicate that AuCl2- is responsible for the transport and enrichment of gold during the stage of pre-concentration in the source bed while Au(HS)2- is the main gold species involved in the formation of gold deposits in response to hydrothermal reworking .Acid chloride solutions with αcl->10° and sulfur-rich solutions with a∑s in excess of 10-2 are held as important criteria for gold enrichment in the source bed and for the formation of gold deposits by subsequent hydrothermal event, respectively.

  3. Yangshan Gold Deposit: The Largest Carlin and Carlin-like Type Gold Deposit in China

    Institute of Scientific and Technical Information of China (English)

    YAN Fengzeng; LI Qiangzhi

    2008-01-01

    Gold Headquarter of the CAPF has discovered the Yangshan super large-scale gold depositin Gansu Province, which is a great breakthrough of gold exploration and prospecting in WesternQiniing Mountains of China. The gold resources of this deposit achieved 308 tons with increasingpotentials. Preliminary geological investigations indicate that the Yangshan gold deposit is located inthe intra-continental collision orogenic belt; and the deposit was formed during the continent-continentcollision orogenic processes. The geological characteristics of the deposit are similar to that of thetypical Carlin-type gold deposits, while differences still exist. The ore-forming background is notablydifferent from the Carlin gold deposit province in the United States; and the ore-forming fluids aresimilar with that of the orogenic-type gold deposit. Accordingly, the Yangshan gold deposit is atransitional type between the Carlin-type and the orogenic type gold deposits. At present, the Yangshangold deposit is the largest Carlin and Carlin-like type gold deposit that is ever discovered in China.Researches on metaliogeny, metaliogenic model and ore-enrichment regularities of the Yangshan golddeposit are crucial to meet the pressing needs of the current geological investigation and oreexploration of the deposit.

  4. Computational approaches to homogeneous gold catalysis.

    Science.gov (United States)

    Faza, Olalla Nieto; López, Carlos Silva

    2015-01-01

    Homogenous gold catalysis has been exploding for the last decade at an outstanding pace. The best described reactivity of Au(I) and Au(III) species is based on gold's properties as a soft Lewis acid, but new reactivity patterns have recently emerged which further expand the range of transformations achievable using gold catalysis, with examples of dual gold activation, hydrogenation reactions, or Au(I)/Au(III) catalytic cycles.In this scenario, to develop fully all these new possibilities, the use of computational tools to understand at an atomistic level of detail the complete role of gold as a catalyst is unavoidable. In this work we aim to provide a comprehensive review of the available benchmark works on methodological options to study homogenous gold catalysis in the hope that this effort can help guide the choice of method in future mechanistic studies involving gold complexes. This is relevant because a representative number of current mechanistic studies still use methods which have been reported as inappropriate and dangerously inaccurate for this chemistry.Together with this, we describe a number of recent mechanistic studies where computational chemistry has provided relevant insights into non-conventional reaction paths, unexpected selectivities or novel reactivity, which illustrate the complexity behind gold-mediated organic chemistry.

  5. Cholestasis and pneumonitis induced by gold therapy.

    Science.gov (United States)

    Farre, J M; Perez, T; Hautefeuille, P; Tonnel, F; Colombel, J F; Duquesnoy, B; Delcambre, B

    1989-12-01

    The authors describe the association of gold salt-induced cholestasis and lymphocytic alveolitis proved by liver biopsy and broncho-alveolar lavage. To our knowledge this is the third case report on the combination of liver disease and pulmonary infiltration induced by gold compounds. PMID:2612124

  6. 2008: Golden Time in Gold Market

    Institute of Scientific and Technical Information of China (English)

    Guo; Yan

    2008-01-01

      Pushed by increased demand from both jewelers and investors, China has become the drivin, g force behind the world's gold market in 2007. Chinas gold market this year has maintained its growing momentum with booming demand, not only in the domestic market but also in the international market.……

  7. 2008: Golden Time in Gold Market

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    @@ Pushed by increased demand from both jewelers and investors, China has become the drivin, g force behind the world's gold market in 2007. Chinas gold market this year has maintained its growing momentum with booming demand, not only in the domestic market but also in the international market.

  8. The Gold Mining Camp: A Simulation Game.

    Science.gov (United States)

    Stoltman, Joseph P.; Keach, Everett T., Jr.

    This economics simulation game complements the third grade Gold Mining Unit developed by Project Social Studies at the University of Minnesota. The simulation is designed for three purposes: 1) to reinforce the prior learning which occurs in the gold mining camp unit; 2) to involve eight-year-olds in the process of solving simulated economic…

  9. Goudafzettingen in Suriname (Gold deposits in Surinam)

    NARCIS (Netherlands)

    Brinck, J.W.

    1956-01-01

    THE GOLD DEPOSITS IN SURINAM AND THE DISTRIBUTION OF CONCESSIONS THROUGH THE COUNTRY The fieldwork on the occurrence of primary and secondary gold deposits in Surinam on which this thesis is based was carried out by order of the Welfare Fund Surinam (Welvaarts Fonds Suriname) during the periods Dece

  10. Nonlinear optical studies of single gold nanoparticles

    NARCIS (Netherlands)

    Dijk, Meindert Alexander van

    2007-01-01

    Gold nanoparticles are spherical clusters of gold atoms, with diameters typically between 1 and 100 nanometers. The applications of these particles are rather diverse, from optical labels for biological experiments to data carrier for optical data storage. The goal of my project was to develop new

  11. Dress Images on Gold-foil Figures

    DEFF Research Database (Denmark)

    Mannering, Ulla; Andersson Strand, Eva Birgitta

    2009-01-01

    From the Late Iron Age settlement Sorte Muld on Bornholm both gold foil figures with depictions of costumes and textile tools can tell about textile production.......From the Late Iron Age settlement Sorte Muld on Bornholm both gold foil figures with depictions of costumes and textile tools can tell about textile production....

  12. RF Sputtering of Gold Contacts On Niobium

    Science.gov (United States)

    Barr, D. W.

    1983-01-01

    Reliable gold contacts are deposited on niobium by combination of RF sputtering and photolithography. Process results in structures having gold only where desired for electrical contact. Contacts are stable under repeated cycling from room temperature to 4.2 K and show room-temperature contact resistance as much as 40 percent below indium contacts made by thermalcompression bonding.

  13. Single particle optical investigation of gold shell enhanced upconverted fluorescence emission

    Science.gov (United States)

    Green, Kory; Lim, Shuang Fang; Hallen, Hans

    2014-03-01

    Upconverting nanoparticles (UCNPs) excited in the near IR offer novel advantages as fluorescent contrast agents, allowing for background free bio-imaging. However, their fluorescence brightness is hampered by low quantum efficiency due to the low absorption cross section of Ytterbium and Erbium ions in the near IR. We enhance the efficiency of these particles by investigating the plasmonic coupling of 30nm diameter core NaYF4: Yb, Er upconverting particles (UCNPs) with a gold shell coating. An enhancement of green emission by a factor of five and a three times overall increase in emission intensity has been achieved for single particle spectra. UV-Vis absorption has confirmed the surface plasmon resonance (SPR) of the gold shell to the near IR and transmission electron microscope (TEM) images demonstrates successful growth of a gold shell around the upconversion particle. Time-resolved spectroscopy shows that gold shell coupling changes the lifetime of the energy levels of the Erbium ion that are relevant to the emission process.

  14. Gold nanoparticle growth control - Implementing novel wet chemistry method on silicon substrate

    KAUST Repository

    Al-Ameer, Ammar

    2013-04-01

    Controlling particle size, shape, nucleation, and self-assembly on surfaces are some of the main challenges facing electronic device fabrication. In this work, growth of gold nanoparticles over a wide range of sizes was investigated by using a novel wet chemical method, where potassium iodide is used as the reducing solution and gold chloride as the metal precursor, on silicon substrates. Four parameters were studied: soaking time, solution temperature, concentration of the solution of gold chloride, and surface pre-treatment of the substrate. Synthesized nanoparticles were then characterized using scanning electron microscopy (SEM). The precise control of the location and order of the grown gold overlayer was achieved by using focused ion beam (FIB) patterning of a silicon surface, pre-treated with potassium iodide. By varying the soaking time and temperature, different particle sizes and shapes were obtained. Flat geometrical shapes and spherical shapes were observed. We believe, that the method described in this work is potentially a straightforward and efficient way to fabricate gold contacts for microelectronics. © 2013 IEEE.

  15. CO oxidation over gold supported on Cs, Li and Ti-doped cryptomelane materials.

    Science.gov (United States)

    Carabineiro, Sónia A C; Santos, Vera P; Pereira, M Fernando R; Órfão, José J M; Figueiredo, José L

    2016-10-15

    Cryptomelane-type manganese oxides were synthesized by redox reaction under acid and reflux conditions. Different metals (cesium, lithium and titanium) were incorporated into the tunnel structure by the ion-exchange technique. Gold was loaded onto these materials (1wt%) by a double impregnation method. The obtained catalysts were characterized by high-resolution transmission electron microscopy, energy-dispersive X-ray spectrometry, scanning electron microscopy, X-ray diffraction and temperature-programmed reduction. The catalytic activity of these materials was evaluated in the oxidation of carbon monoxide. The incorporation of Cs, Li or Ti into cryptomelane was detrimental in terms of catalytic activity. Further addition of gold to cryptomelane doped materials significantly improved the catalytic performance, especially for Cs-K-OMS-2 and Li-K-OMS-2 (to a smaller extent). Addition of gold to the Ti containing material did not show a significant improvement. The observed trends are related to the effect of gold on samples reducibility and to the gold particle size. The lattice oxygen can also be considered accountable for the activity of the materials, since the most active cryptomelane catalysts are those with higher lattice oxygen donating ability for the oxidation of the CO molecule. PMID:27399615

  16. A simple strategy to fabricate poly (acrylamide-co-alginate)/gold nanocomposites for inactivation of bacteria

    Science.gov (United States)

    Zhang, Yanan; Lou, Zhichao; Zhang, Xiaohong; Hu, Xiaodan; Zhang, Haiqian

    2014-12-01

    A facile and efficient approach to prepare uniform gold nanoparticles (Au NPs) in hybrid hydrogel consisting of acrylamide (AM) and alginate (SA) for antibacterial applications is reported. In this study, reduction of gold ions by acrylamide and alginate (AM-SA) occurred before the polymerization and as-obtained gold colloids are stabilized by AM-SA immediately in the absence of commonly used reducing agents and protective reagents. Via transmittance electron microscopy results, we can conclude that the obtained gold nanoparticles in hydrogel are well dispersed. Furthermore, ultraviolet-visible absorption spectroscopy, Fourier transform infrared and thermogravimetric analysis were used to characterize the structure and composition of the synthetic nanocomposites. Our approach provides well-dispersed nanoparticles around 8 mm in size. It is important to underline that nanoparticle aggregation was not observed during and after gel formation. The prepared Au NPs exhibited remarkable stability in the presence of high pH s, and a range of salt concentrations. Importantly, the hydrogel/gold nanocomposites showed a non-compromised activity to inhibit the growth of a model bacterium, Escherichia coli. With their excellent mechanical behavior, as well as the remained antibacterial activity, the nanocomposites should get various potential applications in the fields of pharmaceutical science and tissue engineering.

  17. Absorption, fluorescence and resonance Rayleigh scattering spectral characteristics of interaction of gold nanoparticle with safranine T

    Institute of Scientific and Technical Information of China (English)

    HE Youqiu; LIU Shaopu; LIU Qin; LIU Zhongfang; HU Xiaoli

    2005-01-01

    The interaction between gold nanoparticle and safranine T (ST) has been studied with resonance Rayleigh scattering (RRS) spectra, absorption and fluorescence spectra. In the pH 5 solution, citrate [(H2L)2-] self-assembles on the surface of positively-charged gold nanoparticle, which results in the [(Au)n(H2L)m]x- complex. In other words, one of carboxylate oxygens in (H2L)2- moves inward and combines with gold nanoparticle. The other carboxylate oxygens moves outward to form a supermolecular complex anion with x negative charges. Then by virtue of electrostatic attraction, hydrophobic force and charge transfer action, the complex anion binds with ST cation to form a new ion-association complex. Here (H2L)2- acts as a bridge. The formation of the complex results in the significant enhancement of RRS intensity, the appearance of new RRS spectrum, the red shift of plasma absorption band of gold nanoparticle as well as the decrease in the absorbance and fluorescence quenching for safranine T. In this work, the interaction between gold nanoparticle and ST on the RRS, absorption and fluorescence spectra has been investigated. The reason why RRS intensity increases greatly and the reaction mechanism have been inquired. The results show that RRS spectra can not only be used to study nanoparticle and reaction product, but also are a sensitive means to characterize and detect nanoparticles.

  18. Synthesis of camptothecin-loaded gold nanomaterials

    International Nuclear Information System (INIS)

    Camptothecin-loaded gold nanomaterials have been synthesized by the sodium borohydride reduction method under a strong basic condition. The obtained gold nanomaterials have been characterized by transmission electron microscopy (TEM), atomic force microscopy (AFM) and UV-vis absorption spectroscopy. The camptothecin-loaded gold colloidal solution was very stable and can be stored for more than two months at room temperature without obvious changes. The color of the colloidal solution can change from wine red to purple and blue during the acidifying process. It was revealed that the release of camptothecin and the aggregation of gold nanoparticles can be controlled by tuning the solution pH. The present study implied that the gold nanomaterials can be used as the potential carrier for CPT delivery.

  19. Functionalization of gold nanoparticles as antidiabetic nanomaterial

    Science.gov (United States)

    Venkatachalam, M.; Govindaraju, K.; Mohamed Sadiq, A.; Tamilselvan, S.; Ganesh Kumar, V.; Singaravelu, G.

    2013-12-01

    In the present investigation, functionalization of gold nanoparticles synthesized using propanoic acid 2-(3-acetoxy-4,4,14-trimethylandrost-8-en-17-yl) (PAT) an active biocomponent isolated from Cassia auriculata is studied in detail. On reaction of PAT with aqueous HAuCl4, rapid formation of stable gold nanoparticles was achieved. Formation of gold nanoparticles was confirmed by UV-vis spectroscopy, XRD, GC-MS, FTIR, TEM and SEM with EDAX. Gold nanoparticles mostly were monodisperse, spherical in shape and ranged in size 12-41 nm. Gold nanoparticles synthesised using PAT was administered to alloxan (150 mg/kg body weight) induced diabetic male albino rats at different doses (0.25, 0.5, 0.75 and 1.0 mg/kg body weight) for 28 days. Plasma glucose level, cholesterol and triglyceride were significantly (p phosphatase 1B inhibitory activity.

  20. Gold analysis by the gamma absorption technique.

    Science.gov (United States)

    Kurtoglu, Arzu; Tugrul, A Beril

    2003-01-01

    Gold (Au) analyses are generally performed using destructive techniques. In this study, the Gamma Absorption Technique has been employed for gold analysis. A series of different gold alloys of known gold content were analysed and a calibration curve was obtained. This curve was then used for the analysis of unknown samples. Gold analyses can be made non-destructively, easily and quickly by the gamma absorption technique. The mass attenuation coefficients of the alloys were measured around the K-shell absorption edge of Au. Theoretical mass attenuation coefficient values were obtained using the WinXCom program and comparison of the experimental results with the theoretical values showed generally good and acceptable agreement. PMID:12485656

  1. Ion colliders

    International Nuclear Information System (INIS)

    Ion colliders are research tools for high-energy nuclear physics, and are used to test the theory of Quantum Chromo Dynamics (QCD). The collisions of fully stripped high-energy ions create matter of a temperature and density that existed only microseconds after the Big Bang. Ion colliders can reach higher densities and temperatures than fixed target experiments although at a much lower luminosity. The first ion collider was the CERN Intersecting Storage Ring (ISR), which collided light ions (77Asb1, 81Bou1). The BNL Relativistic Heavy Ion Collider (RHIC) is in operation since 2000 and has collided a number of species at numerous energies. The CERN Large Hadron Collider (LHC) started the heavy ion program in 2010. Table 1 shows all previous and the currently planned running modes for ISR, RHIC, and LHC. All three machines also collide protons, which are spin-polarized in RHIC. Ion colliders differ from proton or antiproton colliders in a number of ways: the preparation of the ions in the source and the pre-injector chain is limited by other effects than for protons; frequent changes in the collision energy and particle species, including asymmetric species, are typical; and the interaction of ions with each other and accelerator components is different from protons, which has implications for collision products, collimation, the beam dump, and intercepting instrumentation devices such a profile monitors. In the preparation for the collider use the charge state Z of the ions is successively increased to minimize the effects of space charge, intrabeam scattering (IBS), charge change effects (electron capture and stripping), and ion-impact desorption after beam loss. Low charge states reduce space charge, intrabeam scattering, and electron capture effects. High charge states reduce electron stripping, and make bending and acceleration more effective. Electron stripping at higher energies is generally more efficient. Table 2 shows the charge states and energies in the

  2. Enzyme-catalysed deposition of ultrathin silver shells on gold nanorods: a universal and highly efficient signal amplification strategy for translating immunoassay into a litmus-type test.

    Science.gov (United States)

    Yang, Xinjian; Gao, Zhiqiang

    2015-04-25

    On the basis of enzyme-catalysed reduction of silver ions and consequent deposition of ultrathin silver shells on gold nanorods, a highly efficient signal amplification method for immunoassay is developed. For a model analyte prostate-specific antigen, a 10(4)-fold improvement over conventional enzyme-linked immunosorbent assay is accomplished by leveraging on the cumulative nature of the enzymatic reaction and the sensitive response of plasnomic gold nanorods to the deposition the silver shells.

  3. Ion implantation inhibits cell attachment to glassy polymeric carbon

    International Nuclear Information System (INIS)

    Implantation of MeV gold, oxygen, carbon ions into GPC alters the surface topography of GPC and enhances the already strong tendency for cells to attach to GPC. We have shown that implantation of silver ions near the surface strongly inhibits cell growth on GPC. Both enhanced adhesion of and inhibition of cell growth are desirable improvements on cardiac implants that have long been successfully fabricated from biocompatible glassy polymeric carbon (GPC). In vitro biocompatibility tests have been carried out with model cell lines to demonstrate that ion beam assisted deposition (IBAD) of silver, as well as silver ion bombardment, can favorably influence the surface of GPC for biomedical applications

  4. Molecular Beam Optical Study of Gold Sulfide and Gold Oxide

    Science.gov (United States)

    Zhang, Ruohan; Yu, Yuanqin; Steimle, Timothy

    2016-06-01

    Gold-sulfur and gold-oxygen bonds are key components to numerous established and emerging technologies that have applications as far ranging as medical imaging, catalysis, electronics, and material science. A major theoretical challenge for describing this bonding is correctly accounting for the large relativistic and electron correlation effects. Such effects are best studied in diatomic, AuX, molecules. Recently, the observed AuS electronic state energy ordering was measured and compared to a simple molecular orbital diagram prediction. Here we more thoroughly investigate the nature of the electronic states of both AuS and AuO from the analysis of high-resolution (FWHM\\cong35MHz) optical Zeeman spectroscopy of the (0,0){B}2Σ--{X}2Π3/2 bands. The determined fine and hyperfine parameters for the {B}2Σ- state of AuO differ from those extracted from the analysis of a hot, Doppler-limited, spectrum. It is demonstrated that the nature of the {B}2Σ- states of AuO and AuS are radically different. The magnetic tuning of AuO and AuS indicates that the {B}2Σ- states are heavily contaminated. Supported by the National Science Foundation under Grant No.1265885. D. L. Kokkin, R. Zhang, T. C. Steimle, I. A. Wyse, B. W. Pearlman and T. D. Varberg, J. Phys. Chem. A., 119(48), 4412, 2015. L. C. O'Brien, B. A. Borchert, A. Farquhar, S. Shaji, J. J. O'Brien and R. W. Field, J. Mol. Spectrosc., 252(2), 136, 2008

  5. Carbonate hosted gold deposit in Tasmania, Australia

    International Nuclear Information System (INIS)

    Full text: This study uses elemental and isotopic composition of carbonates associated with gold from Henty and Beaconsfield in Tasmania, Australia, to illustrate source of gold-bearing fluids, salinity, temperature and dissolution and reprecipitation of carbonate. The Beaconsfield and Henty gold mines are located in northern and western Tasmania respectively. Gold mineralisation in Beaconsfield occurs within the quartz-carbonate Tasmania Reef (Lower to Middle Palaeozoic sequence, Hills, 1998). The Henty gold mine is located at the base of the Cambrian Tyndall Group (volcano-sedimentary succession, White and McPhie, 1996) close to Henty Fault. Gold in carbonate samples from Henty ranges from 7.7 to 9360 ppm and in Beaconsfield ranges from 0.01 to 434 ppm. The amount of carbonate in samples from Henty and Beaconsfield gold mines varies from approximately 24 to 99.8%. Bivariate plot of Ca relative to total amounts of Mg, Fe and Mn illustrates that the major carbonate minerals at Beaconsfield and Henty gold mines are magnesian ankerite and calcite. The difference in carbonate mineralogy, at Henty and Beaconsfield gold mines, is attributed to the composition of fluids responsible for carbonate alteration. Gold and magnesium in Beaconsfield ankerite are derived from the leaching of Cambrian ultramafic rocks during the Devonian by the passage of meteoric fluids through tectonically affected Ordovician carbonates (Rao and Adabi, 1999). The total concentration of Fe and Mn are low (0.5 to 2%) in Henty and high (1 to 17.5%) in Beaconsfield ankerite, possibly due to oxidising conditions at Henty and reducing conditions at Beaconsfield gold mines during gold mineralisation. Variation of Sr values between Beaconsfield ankerite and Henty calcite is related to dissolution of limestone that increase Sr concentrations in gold mineralising fluids. Na values in both Beaconsfield (20 to 1100 ppm) and Henty carbonates (25 to 1650 ppm) suggest low salinity fluids responsible for gold

  6. Seed-mediated biomineralizaton toward the high yield production of gold nanoprisms.

    Science.gov (United States)

    Geng, Xi; Roth, Kristina L; Freyman, Megan C; Liu, Jianzhao; Grove, Tijana Z

    2016-07-28

    Gold nanotriangles (Au NTs) with tunable edge length were synthesized via a green chemical route in the presence of the designed consensus sequence tetratricopeptide repeat (CTPR) protein, halide anions (Br(-)) and CTPR-stabilized Ag seeds. The well-defined morphologies, tailored plasmonic absorbance from visible-light to the near infrared (NIR) region, colloidal stability and biocompatibility are attributed to the synergistic action of CTPR, halide ions, and CTPR-stabilized Ag seeds. PMID:27424736

  7. The Effect of Surface Functionalization on the Immobilization of Gold Nanoparticles on Graphene Sheets

    OpenAIRE

    Min Song; Juan Xu; Changzi Wu

    2012-01-01

    In our study, graphene oxide is synthesized by Hummers method. And then, carboxylic acid functionalized graphene (graphene-COOH), thiol-functionalized graphene (graphene-SH), and highly dispersive graphene are prepared by chemical modification of respective groups on the graphene surface. Furthermore, we explore a solution-based approach to prepare three differently functionalized graphene-gold composites by one-step chemical reduction of AuCl4 - ions in respective functionalized graphene sus...

  8. A Chemical-Medical Mystery: Gold Jewelry and Black Marks on Skin

    Science.gov (United States)

    Kebbekus, Barbara B.

    2000-10-01

    Gold jewelry at times makes a black mark or smudge on skin. This may be caused by abrasive powders on the skin (e.g. zinc oxide) but the phenomenon may also be caused by other skin conditions, possibly the presence of chloride ion, acidity, or sulfur-containing amino acids. Some anecdotal evidence is published, but properly designed studies to clarify the actual causes are not available.

  9. Energy Reflection from Gold Bombarded with keV Protons at Various Angles of Incidence

    DEFF Research Database (Denmark)

    Sørensen, H.

    1976-01-01

    The calorimetric deuterium film method operating at liquid‐helium temperature was used for measuring the energy reflection coefficient γ for 1–10‐keV protons incident on gold at angles of incidence up to 75°. H+2 and H+3 ions were used to obtain the lowest velocities. The growth with angle...... increases with energy. There is fair agreement with the theoretical results of Robinson and of Oen and Robinson....

  10. Energy reflection from gold bombarded with keV protons at various angles of incidence

    International Nuclear Information System (INIS)

    The calorimetric deuterium film method operating at liquid-helium temperature was used for measuring the energy reflection coefficient γ for 1--10-keV protons incident on gold at angles of incidence up to 75degree. H+2 and H+3 ions were used to obtain the lowest velocities. The growth with angle increases with energy. There is fair agreement with the theoretical results of Robinson and of Oen and Robinson

  11. Gold-silver alloy nanoshells: a new candidate for nanotherapeutics and diagnostics

    Directory of Open Access Journals (Sweden)

    Karmonik Christof

    2011-01-01

    Full Text Available Abstract We have developed novel gold-silver alloy nanoshells as magnetic resonance imaging (MRI dual T 1 (positive and T 2 (negative contrast agents as an alternative to typical gadolinium (Gd-based contrast agents. Specifically, we have doped iron oxide nanoparticles with Gd ions and sequestered the ions within the core by coating the nanoparticles with an alloy of gold and silver. Thus, these nanoparticles are very innovative and have the potential to overcome toxicities related to renal clearance of contrast agents such as nephrogenic systemic fibrosis. The morphology of the attained nanoparticles was characterized by XRD which demonstrated the successful incorporation of Gd(III ions into the structure of the magnetite, with no major alterations of the spinel structure, as well as the growth of the gold-silver alloy shells. This was supported by TEM, ICP-AES, and SEM/EDS data. The nanoshells showed a saturation magnetization of 38 emu/g because of the presence of Gd ions within the crystalline structure with r 1 and r 2 values of 0.0119 and 0.9229 mL mg-1 s-1, respectively (Au:Ag alloy = 1:1. T 1- and T 2-weighted images of the nanoshells showed that these agents can both increase the surrounding water proton signals in the T 1-weighted image and reduce the signal in T 2-weighted images. The as-synthesized nanoparticles exhibited strong absorption in the range of 600-800 nm, their optical properties being strongly dependent upon the thickness of the gold-silver alloy shell. Thus, these nanoshells have the potential to be utilized for tumor cell ablation because of their absorption as well as an imaging agent.

  12. The 'price' of Olympic Gold.

    Science.gov (United States)

    Hogan, K; Norton, K

    2000-06-01

    In 1981 the Commonwealth Government established the Australian Institute of Sport (AIS). The Australian Sports Commission (ASC) which administers the AIS has 2 objectives: (1) excellence in sports performances; and (2) increased participation in sports and sports activities. State-based institutes of sport have also been established with the same or very similar objectives. Federal policy directs the bulk of the ASC budget to elite athlete programs. A smaller proportion goes towards community participation. The official reason is based on the notion of the 'trickle-down' or 'demonstration' effect. That is, a flow-on of benefits to the broader community in the form of increased participation as a direct result of elite sports success. The aims of this study were to determine the (1) spending pattern to elite sports programs for the 5 Olympics 1976/77 to 1995/96, (2) evidence for the two ASC objectives having been met, and (3) expected medal tally at the 2000 Olympic Games. Results show funding (in 1998 dollars), has accelerated from about $1.2 million (1976/77) to $106 million in (1997/98), particularly since the Games were awarded to Sydney. The total amount spent on elite athletes was $0.918 billion. In the period 1980-96 Australia won 25 gold and 115 total Olympic medals. This equates to approximately $37 million per gold and $8 million per medal in general. There was a significant linear relationship between money spent and total medals won. This was also found when all medal types were analysed independently. The predicted medal tally in 2000 (based on the cost per medal and the expenditure towards Sydney) indicates the medal count will be about 14+/-1 gold, 15+/-2 silver and 33+/-4 bronze. Based on our nation's record of international sporting achievement, there is little doubt we have fulfilled the ASC's first objective. Current data on physical activity patterns of Australians suggest the second objective has not been met. Focusing attention on and achieving

  13. The giant Jiaodong gold province:The key to a unified model for orogenic gold deposits?

    Institute of Scientific and Technical Information of China (English)

    David I. Groves; M. Santosh

    2016-01-01

    Although the term orogenic gold deposit has been widely accepted for all gold-only lode-gold deposits, with the exception of Carlin-type deposits and rare intrusion-related gold systems, there has been continuing debate on their genesis. Early syngenetic models and hydrothermal models dominated by meteoric fluids are now clearly unacceptable. Magmatic-hydrothermal models fail to explain the genesis of orogenic gold deposits because of the lack of consistent spatially e associated granitic intrusions and inconsistent temporal relationships. The most plausible, and widely accepted, models involve meta-morphic fluids, but the source of these fluids is hotly debated. Sources within deeper segments of the supracrustal successions hosting the deposits, the underlying continental crust, and subducted oceanic lithosphere and its overlying sediment wedge all have their proponents. The orogenic gold deposits of the giant Jiaodong gold province of China, in the delaminated North China Craton, contain ca. 120 Ma gold deposits in Precambrian crust that was metamorphosed over 2000 million years prior to gold mineralization. The only realistic source of fluid and gold is a subducted oceanic slab with its overlying sulfide-rich sedimentary package, or the associated mantle wedge. This could be viewed as an exception to a general metamorphic model where orogenic gold has been derived during greenschist- to amphibolite-facies metamorphism of supracrustal rocks: basaltic rocks in the Precambrian and sedi-mentary rocks in the Phanerozoic. Alternatively, if a holistic view is taken, Jiaodong can be considered the key orogenic gold province for a unified model in which gold is derived from late-orogenic metamorphic devolatilization of stalled subduction slabs and oceanic sediments throughout Earth history. The latter model satisfies all geological, geochronological, isotopic and geochemical constraints but the precise mechanisms of auriferous fluid release, like many other subduction

  14. Hierarchical organization and molecular diffusion in gold nanorod/silica supercrystal nanocomposites

    Science.gov (United States)

    Hamon, Cyrille; Sanz-Ortiz, Marta N.; Modin, Evgeny; Hill, Eric H.; Scarabelli, Leonardo; Chuvilin, Andrey; Liz-Marzán, Luis M.

    2016-04-01

    Hierarchical organization of gold nanorods was previously obtained on a substrate, allowing precise control over the morphology of the assemblies and macroscale spatial arrangement. Herein, a thorough description of these gold nanorod assemblies and their orientation within supercrystals is presented together with a sol-gel technique to protect the supercrystals with mesoporous silica films. The internal organization of the nanorods in the supercrystals was characterized by combining focused ion beam ablation and scanning electron microscopy. A mesoporous silica layer is grown both over the supercrystals and between the individual lamellae of gold nanorods inside the structure. This not only prevented the detachment of the supercrystal from the substrate in water, but also allowed small molecule analytes to infiltrate the structure. These nanocomposite substrates show superior Raman enhancement in comparison with gold supercrystals without silica owing to improved accessibility of the plasmonic hot spots to analytes. The patterned supercrystal arrays with enhanced optical and mechanical properties obtained in this work show potential for the practical implementation of nanostructured devices in spatially resolved ultradetection of biomarkers and other analytes.Hierarchical organization of gold nanorods was previously obtained on a substrate, allowing precise control over the morphology of the assemblies and macroscale spatial arrangement. Herein, a thorough description of these gold nanorod assemblies and their orientation within supercrystals is presented together with a sol-gel technique to protect the supercrystals with mesoporous silica films. The internal organization of the nanorods in the supercrystals was characterized by combining focused ion beam ablation and scanning electron microscopy. A mesoporous silica layer is grown both over the supercrystals and between the individual lamellae of gold nanorods inside the structure. This not only prevented the

  15. Gold-catalyzed naphthalene functionalization

    Directory of Open Access Journals (Sweden)

    Iván Rivilla

    2011-05-01

    Full Text Available The complexes IPrMCl (IPr = 1,3-bis(diisopropylphenylimidazol-2-ylidene, M = Cu, 1a; M = Au, 1b, in the presence of one equiv of NaBAr'4 (Ar' = 3,5-bis(trifluoromethylphenyl, catalyze the transfer of carbene groups: C(RCO2Et (R = H, Me from N2C(RCO2Et to afford products that depend on the nature of the metal center. The copper-based catalyst yields exclusively a cycloheptatriene derivative from the Buchner reaction, whereas the gold analog affords a mixture of products derived either from the formal insertion of the carbene unit into the aromatic C–H bond or from its addition to a double bond. In addition, no byproducts derived from carbene coupling were observed.

  16. Shaped gold and silver nanoparticles

    Science.gov (United States)

    Sun, Yugang; An, Changhua

    2011-03-01

    Advance in the synthesis of shaped nanoparticles made of gold and silver is reviewed in this article. This review starts with a new angle by analyzing the relationship between the geometrical symmetry of a nanoparticle shape and its internal crystalline structures. According to the relationship, the nanoparticles with well-defined shapes are classified into three categories: nanoparticles with single crystallinity, nanoparticles with angular twins, and nanoparticles with parallel twins. Discussion and analysis on the classical methods for the synthesis of shaped nanoparticles in each category are also included and personal perspectives on the future research directions in the synthesis of shaped metal nanoparticles are briefly summarized. This review is expected to provide a guideline in designing the strategy for the synthesis of shaped nanoparticles and analyzing the corresponding growth mechanism.

  17. Chloro(trimesitylphosphine)gold(I)

    OpenAIRE

    Alyea, Elmer C.; Ferguson, George; Gallagher, John F.; Malto, John

    1993-01-01

    Chloro(trimesitylphosphine)gold(I), [AuCl(C9H11)P3], has approximate threefold symmetry in the solid state [dihedral angles between the mesityl ring planes and the relevant Au--PnC planes are 47.0(1), 48.0(1) and 48.5 (1)°]. The Au atom has a linear coordination geometry with AumC1 and Au--P bond lengths of 2.2716 (19) and 2.2634 (15) A, respectively, and a PmAu--C1 bond angle of 178.01 (8) °. The Ca~--Ca~ bond lengths are in the range 1.360 (10) to 1.424 (8) ,4,, while the ...

  18. Charge-State Distributions of Accelerated ^{48}Ca Ions

    CERN Document Server

    Skobelev, N K; Astabatyan, R A; Vincour, J; Kulko, A A; Lobastov, S P; Lukyanov, S M; Markaryan, E R; Maslov, V A; Penionzhkevich, Yu E; Sobolev, Yu G; Ugryumov, V Yu

    2003-01-01

    A stepped pole broad-range magnetic analyzer has been used to measure the charge-state distributions of accelerated ^{48}Ca ions at the two incident energies 242.8 and 264.5 MeV after passing through thin carbon or gold target foils. The measured charge-state distributions and the mean equilibrium charge of the ^{48}Ca ions are compared with various calculations. It has been shown that the calculations can be used only for evaluation purposes.

  19. Smart textile device using ion polymer metal compound.

    Science.gov (United States)

    Nakamura, Taro; Ihara, Tadashi

    2013-01-01

    We have developed a smart textile device that detects angular displacement of attached surface using ion polymer metal compound. The device was composed of ion polymer metal compound (IPMC) which was fabricated from Nafion resin by heat-press and chemical gold plating. The generated voltage from IPMC was measured as a function of bending angle. Fabricated IPMC device was weaved into a cotton cloth and multidirectional movements were detected. PMID:24109750

  20. Gel Electrophoresis of Gold-DNA Nanoconjugates

    Directory of Open Access Journals (Sweden)

    T. Pellegrino

    2007-01-01

    Full Text Available Gold-DNA conjugates were investigated in detail by a comprehensive gel electrophoresis study based on 1200 gels. A controlled number of single-stranded DNA of different length was attached specifically via thiol-Au bonds to phosphine-stabilized colloidal gold nanoparticles. Alternatively, the surface of the gold particles was saturated with single stranded DNA of different length either specifically via thiol-Au bonds or by nonspecific adsorption. From the experimentally determined electrophoretic mobilities, estimates for the effective diameters of the gold-DNA conjugates were derived by applying two different data treatment approaches. The first method is based on making a calibration curve for the relation between effective diameters and mobilities with gold nanoparticles of known diameter. The second method is based on Ferguson analysis which uses gold nanoparticles of known diameter as reference database. Our study shows that effective diameters derived from gel electrophoresis measurements are affected with a high error bar as the determined values strongly depend on the method of evaluation, though relative changes in size upon binding of molecules can be detected with high precision. Furthermore, in this study, the specific attachment of DNA via gold-thiol bonds to Au nanoparticles is compared to nonspecific adsorption of DNA. Also, the maximum number of DNA molecules that can be bound per particle was determined.

  1. Nature vs. nurture: gold perpetuates "stemness".

    Science.gov (United States)

    Paul, Willi; Sharma, Chandra P; Deb, Kaushik Dilip

    2011-01-01

    Adult tissues contain quiescent reservoirs of multipotent somatic stem cells and pluripotent embryonic-like stem cells (ELSCs). Credited with regenerative properties gold is used across both -contemporary and -ancient medicines. Here, we show that gold exerted these effects by enhancing the pool of pluripotent ELSC while improving their stemness. We used hESCs as an in-vitro model to understand if gold could enhance self-renewal and pluripotency. Swarna-bhasma (SB), an ancient Indian gold microparticulate (41.1 nm), preparation, reduced spontaneous-differentiation, improved self-renewal, pluripotency and proliferation of hESCs. Colloidal gold-nanoparticles (GNP) (15.59 nm) were tested to confirm that the observations were attributable to nanoparticulate-gold. SB and GNP exposure: maintained -stemness, -karyotypic stability, enhanced pluripotency till day-12, increased average colony-sizes, and reduced the number of autonomously-derived differentiated FGFR1 positive fibroblast-niche-cells/colony. Particulate-gold induced upregulation of FGFR1 and IGF2 expression, and decrease in IGF1 secretion indicates IGF1/2 mediated support for enhanced pluripotency and self-renewal in hESCs.

  2. Brightening gold nanoparticles: new sensing approach based on plasmon resonance energy transfer.

    Science.gov (United States)

    Shi, Lei; Jing, Chao; Gu, Zhen; Long, Yi-Tao

    2015-05-11

    Scattering recovered plasmonic resonance energy transfer (SR-PRET) was reported by blocking the plasmon resonance energy transfer (PRET) from gold nanoparticle (GNP) to the adsorbed molecules (RdBS). Due to the selective cleavage of the Si-O bond by F- ions, the quenching is switched off causing an increase in the brightness of the GNPs,detected using dark-field microscopy (DFM) were brightened. This method was successfully applied to the determination of fluoride ions in water. The SR-PRET provides a potential approach for a vitro/vivo sensing with high sensitivity and selectivity.

  3. Brightening Gold Nanoparticles: New Sensing Approach Based on Plasmon Resonance Energy Transfer

    OpenAIRE

    Lei Shi; Chao Jing; Zhen Gu; Yi-Tao Long

    2015-01-01

    Scattering recovered plasmonic resonance energy transfer (SR-PRET) was reported by blocking the plasmon resonance energy transfer (PRET) from gold nanoparticle (GNP) to the adsorbed molecules (RdBS). Due to the selective cleavage of the Si-O bond by F− ions, the quenching is switched off causing an increase in the brightness of the GNPs,detected using dark-field microscopy (DFM) were brightened. This method was successfully applied to the determination of fluoride ions in water. The SR-PRET p...

  4. Investigation of thiol derivatized gold nanoparticle sensors for gas analysis

    Science.gov (United States)

    Stephens, Jared S.

    Analysis of volatile organic compounds (VOCs) in air and exhaled breath by sensor array is a very useful testing technique. It can provide non-invasive, fast, inexpensive testing for many diseases. Breath analysis has been very successful in identifying cancer and other diseases by using a chemiresistor sensor or array with gold nanoparticles to detect biomarkers. Acetone is a biomarker for diabetes and having a portable testing device could help to monitor diabetic and therapeutic progress. An advantage to this testing method is it is conducted at room temperature instead of 200 degrees Celsius. 3. The objective of this research is to determine the effect of thiol derivatized gold nanoparticles based on sensor(s) detection of VOCs. The VOCs to be tested are acetone, ethanol, and a mixture of acetone and ethanol. Each chip is tested under all three VOCs and three concentration levels (0.1, 1, and 5.0 ppm). VOC samples are used to test the sensors' ability to detect and differentiate VOCs. Sensors (also referred to as a chip) are prepared using several types of thiol derivatized gold nanoparticles. The factors are: thiol compound and molar volume loading of the thiol in synthesis. The average resistance results are used to determine the VOC selectivity of the sensors tested. The results show a trend of increasing resistance as VOC concentration is increased relative to dry air; which is used as baseline for VOCs. Several sensors show a high selectivity to one or more VOCs. Overall the 57 micromoles of 4-methoxy-toluenethiol sensor shows the strongest selectivity for VOCs tested. 3. Gerfen, Kurt. 2012. Detection of Acetone in Air Using Silver Ion Exchanged ZSM-5 and Zinc Oxide Sensing Films. Master of Science thesis, University of Louisville.

  5. Ion Chromatography.

    Science.gov (United States)

    Mulik, James D.; Sawicki, Eugene

    1979-01-01

    Accurate for the analysis of ions in solution, this form of analysis enables the analyst to directly assay many compounds that previously were difficult or impossible to analyze. The method is a combination of the methodologies of ion exchange, liquid chromatography, and conductimetric determination with eluant suppression. (Author/RE)

  6. Phytomining for Artisanal Gold Mine Tailings Management

    Directory of Open Access Journals (Sweden)

    Baiq Dewi Krisnayanti

    2016-08-01

    Full Text Available Mine tailings are generally disposed of by artisanal and small scale gold miners in poorly constructed containment areas and this leads to environmental risk. Gold phytomining could be a possible option for tailings management at artisanal and small-scale gold mining (ASGM locations where plants accumulate residual gold in their above ground biomass. The value of metal recovered from plants could offset some of the costs of environmental management. Getting gold into plants has been repeatedly demonstrated by many research groups; however, a simple working technology to get gold out of plants is less well described. A field experiment to assess the relevance of the technology to artisanal miners was conducted in Central Lombok, Indonesia between April and June 2015. Tobacco was planted in cyanidation tailings (1 mg/kg gold and grown for 2.5 months before the entire plot area was irrigated with NaCN to induce metal uptake. Biomass was then harvested (100 kg, air dried, and ashed by miners in equipment currently used to ash activated carbon at the end of a cyanide leach circuit. Borax and silver as a collector metal were added to the tobacco ash and smelted at high temperature to extract metals from the ash. The mass of the final bullion (39 g was greater than the mass of silver used as a collector (31 g, indicating recovery of metals from the biomass through the smelt process. The gold yield of this trial was low (1.2 mg/kg dry weight biomass concentration, indicating that considerable work must still be done to optimise valuable metal recovery by plants at the field scale. However, the described method to process the biomass was technically feasible, and represents a valid technique that artisanal and small-scale gold miners are willing to adopt if the economic case is good.

  7. A simple method for energy calibration of heavy-ion beams

    NARCIS (Netherlands)

    Evers, E.J.; Vries, J.W.; Engelbertink, G.A.P.; Leun, C. van der

    1987-01-01

    A method is described for the calibration of analyzing-magnet systems of heavy-ion accelerators. It makes use of resonances in inverse (p, αγ) reactions, i.e. with heavy-ion beams on hydrogen targets. Instead of a gas target we use the very thin hydrogen-containing surface layer on a gold foil, whic

  8. Gold's monetary roll will be strengthened - Plumbridge

    International Nuclear Information System (INIS)

    Delivering his Presidential address at the Chamber's annual general meeting, Mr Plumbridge said the gold market would enter a new phase and listed seven reasons why gold's monetary role would be strengthened. There was a dramatic increase in the demand for gold jewellery. He also forecasted that South African uranium production would again attain its former peak annual production of about 6000t. There is an essential need for a sustained growth in nuclear power and the prospects for uranium mining industry remain encouraging

  9. Resonance scattering spectroscopy of gold nanoparticle

    Institute of Scientific and Technical Information of China (English)

    JIANG; Zhiliang; FENG; Zhongwei; LI; Tingsheng; LI; Fang; ZHONG; Fuxin; XIE; Jiyun; YI; Xianghui

    2001-01-01

    The gold nanoparticles in diameter of 10-95 nm have been prepared by Frens procedure, all of which exhibit a resonance scattering peak at 580 nm. The mechanism of resonance scattering for gold nanoparticle has been considered according to the wave motion theory of nanoparticle in liquid. The principle of superamolecular interface energy band(SIEB) has been set up and utilized to explain the relationship between the diameter and colors for gold nanoparticle in liquid. A novel spectrophotometric ruler for the determination of the diameter has been proposed according to the relationship of the maximum absorption wavelength and diameter.

  10. Gold Photoluminescence Wavelength and Polarization Engineering

    CERN Document Server

    Andersen, Sebastian K H; Bozhevolnyi, Sergey I

    2016-01-01

    We demonstrate engineering of the spectral content and polarization of photoluminescence (PL) from arrayed gold nanoparticles atop a subwavelength-thin dielectric spacer and optically-thick gold film, a configuration that supports gap-surface plasmon resonances (GSPRs). Choice of shapes and dimensions of gold nanoparticles influences the GSPR wavelength and polarization characteristics, thereby allowing us to enhance and spectrally mold the plasmon-assisted PL while simultaneously controlling its polarization. In order to understand the underlying physics behind the plasmon-enhanced PL, we develop a simple model that faithfully reproduces all features observed in our experiments showing also good quantitative agreement for the PL enhancement

  11. Gold Photoluminescence: Wavelength and Polarization Engineering

    DEFF Research Database (Denmark)

    Andersen, Sebastian Kim Hjælm; Pors, Anders Lambertus; Bozhevolnyi, Sergey I.

    2015-01-01

    and dimensions of gold nanoparticles influences the GSPR wavelength and polarization characteristics, thereby allowing us to enhance and spectrally mold the plasmon-assisted PL while simultaneously controlling its polarization. In order to understand the underlying physics behind the plasmon-enhanced PL, we......We demonstrate engineering of the spectral content and polarization of photoluminescence (PL) from arrayed gold nanoparticles atop a subwavelength-thin dielectric spacer and optically-thick gold film, a configuration that supports gap-surface plasmon resonances (GSPRs). Choice of shapes...

  12. Synthesis of rectangular plate like gold nanoparticles by in situ generation of seeds by combining both radiation and chemical methods

    Energy Technology Data Exchange (ETDEWEB)

    Biswal, Jayashree, E-mail: jbiswal@barc.gov.i [Radiation Technology Development Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085 (India); Ramnani, S.P. [Radiation Technology Development Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085 (India); Shirolikar, Seema [Department of Biological Sciences, Tata Institute of Fundamental Research, Mumbai 400005 (India); Sabharwal, S. [Radiation Technology Development Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085 (India)

    2011-01-15

    Synthesis of gold nanoparticles of morphology other than spheres or rods in a single step by combining the radiolytic and chemical methods has been investigated. The seeds of gold nanoparticle are generated in situ by irradiating aqueous solution containing 4x10{sup -4} mol dm{sup -3} gold precursor ion (Au{sup III}), 0.1 mol dm{sup -3} cetyltrimethyl ammonium bromide (CTAB), 0.2 mol dm{sup -3} isopropanol, 6x10{sup -5} mol dm{sup -3} Ag{sup +} and 7.2x10{sup -4} mol dm{sup -3} ascorbic acid (AA) at a dose rate 3.4 kGy hr{sup -1}. After a short irradiation time sufficient number of seeds were formed in the solution. Au{sup I} present in the system get adsorbed upon these seeds and then subsequently reduction of Au{sup I} to Au{sup 0} by ascorbic acid and growth of the seeds results in formation of gold nanoparticles. TEM image confirmed that plate like gold nanoparticles have been formed. The anisotropic growth of nanoparticles was found to be controlled by bilayer structure of CTAB and selective adsorption of silver ion present in the system.

  13. Development of Yttrium alloy ion source and its application in nanofabrication

    CERN Document Server

    Kukharchyk, Nadezhda; Mazarov, Swetlana; Bushev, Pavel; Wieck, Andreas; Mazarov, Paul

    2016-01-01

    We present a new YAuSi Liquid Metal Alloy Ion Source (LMAIS), generating focused ion beams of yttrium ions, and its prospective applications for nanofabrication, sample preparation, lithographic and implantation processes. Working parameters of the AuSiY LMAIS are similar to other gold-silicon based LMAIS. We found anomalously high emission current of triple charged Yttrium ions. Influence of Yttrium implantation on optical qualities of the implanted ion-ensembles is shown in luminescence of co-implanted Erbium ions.

  14. Coulomb driven energy boost of heavy ions for laser plasma acceleration

    OpenAIRE

    Braenzel, J.; Andreev, A. A.; Platonov, K.; Klingsporn, M.; Ehrentraut, L.; Sandner, W.; Schnürer, M

    2014-01-01

    An unprecedented increase of kinetic energy of laser accelerated heavy ions is demonstrated. Ultra thin gold foils have been irradiated by an ultra short laser pulse at an intensity of $6\\times 10^{19}$ W/cm$^{2}$. Highly charged gold ions with kinetic energies up to $> 200$ MeV and a bandwidth limited energy distribution have been reached by using $1.3$ Joule laser energy on target. $1$D and $2$D Particle in Cell simulations show how a spatial dependence on the ions ionization leads to an en...

  15. Burn-off dominated uranium and asymmetric copper-gold operation in RHIC

    Science.gov (United States)

    Luo, Y.; Fischer, W.; Blaskiewicz, M.; Brennan, J. M.; Kling, N.; Mernick, K.; Roser, T.

    2014-08-01

    In 2012 the Relativistic Heavy Ion Collider collided uranium-uranium ions with a particle energy of 96.4 GeV/nucleon and copper-gold (Cu-Au) ions at 100 GeV/nucleon for the first time. 3-dimensional stochastic cooling became operational for the first time and greatly enhanced the luminosity. Together with a new lattice configuration, we achieved a burn-off dominated uranium beam lifetime at physics stores. In the asymmetric Cu-Au collision, we observed an increased Cu beam loss stemming from different intrabeam-scattering and cooling rates between the Au and Cu ion bunches. By intentionally slowing down the cooling rate for the Au beam at the beginning of store, we reduced the Cu beam loss and maximized the integrated luminosity.

  16. Simulations of nonequilibrium warm dense gold produced by ultrafast heating

    Science.gov (United States)

    Holst, B.; Recoules, V.; Torrent, M.; Chen, Z.; Sametoglu, V.; Tsui, Y. Y.; Kirkwood, S. E.; Reid, M.; Mazevet, S.; Ng, A.

    2013-03-01

    The interaction of femtosecond laser pulses with metals produces nonequilibrium states consisting of hot electrons and cold ions. These can last for many picoseconds before relaxing to a thermodynamic equilibrium. Recent experiments using a chirped pulse probe technique provided AC conductivity data of gold at a sufficient time resolution to observe this relaxation process. We developed an ab-initio model that characterizes thermodynamic properties of warm dense matter states in nonequilibrium. Our theoretical scheme combines a standard two temperature model with temperature dependent material parameters and an energy transfer rate that are obtained by means of ab-initio simulations. This enables us to give a prediction for the temperature evolution during the relaxation process. Additionally, we derive the AC conductivity of the nonequilibrium states from our simulations using the Kubo-Greenwood formula. It is used to test our model against measurements. We observe agreement with experiment using an energy relaxation rate, that is smaller than predicted, giving us reason to revisit its determination. We can furthermore provide thermodynamical and structural data of nonequilibrium warm dense gold which are not accessible in experiment.

  17. The optical nonlinearity of gold nanoparticles prepared by bioreduction method

    Science.gov (United States)

    Balbuena Ortega, A.; Arroyo Carrasco, M. L.; Gayou, V. L.; Orduña Díaz, A.; Delgado Macuil, R.; Rojas López, Marlon

    2013-11-01

    Nonlinear optical and electronic properties of nanosized metal particles have drawn considerable attention because of their strong and size-dependent plasmon resonance absorption. In a metal nanoparticle system such as gold dispersed in a transparent matrix, an absorption peak due to surface plasmon resonance is usually observed in the visible spectral region. Metal nanoparticles are of special interest as nonlinear materials for optical switching and computing because of their relatively large third-order nonlinearity (χ3) and ultrafast response time. The purpose of this study was to analyze the nonlinear optical properties of biosynthesized gold nanoparticles. The samples were prepared by biosynthesis method using yeast extract as reducing agent and the nonlinear optical properties of the nanoparticles were investigated using a single beam Z-scan technique with a beam power of 20 mW and operated at wavelength of 514 nm. The reaction between metal ions and yeast extracts were monitored by UV-visible spectra of Au nanoparticles in aqueous solution with different pH (3-6). The surface plasmon peak position was shifted from 528 nm to 573 nm, according to of pH variation 4 to 6. The average particle size was calculated by the absorption peak position using the Fernig method, from 42 to 103 nm. The z-scan curves showed a negative nonlocal nonlinear refractive index with a magnitude dependent on the nanoparticle size.

  18. Synthesis of highly fluorescent gold nanoclusters using egg white proteins.

    Science.gov (United States)

    Joseph, Dickson; Geckeler, Kurt E

    2014-03-01

    Gold nanoclusters (AuNCs) have gained interest during the recent years because of their low toxicity and finer size for the bioimaging and biolabeling applications in comparison to the semiconductor quantum dot analogues. Diverse materials such as sulfur compounds, peptides, dendrimers, proteins, etc., are exploited for the preparation of AuNCs. Henceforth, highly fluorescent, water-soluble, and few atom-containing gold nanoclusters are created using a rapid, straightforward, and green method. In this regard for the first time chicken egg white (CEW), one of the most unique materials, is utilized in an aqueous solution under basic conditions at physiological temperature for the preparation of AuNCs. Tyrosine and tryptophan amino acid residues are responsible for the conversion of Au ions to Au(0) under alkaline condtions. CEW contains four major proteins of which the main constituent protein, ovalbumin also leads to the formation of the AuNCs with a higher fluorescence emission compared to the CEW. The ratios between the different reaction partners are very crucial, along with temperature and time for the preparation of AuNCs with high photoluminescence emission. The limited vibrational motion of the proteins under alkaline condition and the bulkiness of the proteins help in the formation of AuNCs. PMID:24321847

  19. Aggregation and adhesion of gold nanoparticles in phosphate buffered saline

    Energy Technology Data Exchange (ETDEWEB)

    Du Shangfeng, E-mail: s.du@bham.ac.uk; Kendall, Kevin; Toloueinia, Panteha; Mehrabadi, Yasamin; Gupta, Gaurav; Newton, Jill [University of Birmingham, School of Chemical Engineering (United Kingdom)

    2012-03-15

    In applications in medicine and more specifically drug delivery, the dispersion stability of nanoparticles plays a significant role on their final performances. In this study, with the use of two laser technologies, dynamic light scattering (DLS) and nanoparticle tracking analysis (NTA), we report a simple method to estimate the stability of nanoparticles dispersed in phosphate buffered saline (PBS). Stability has two features: (1) self-aggregation as the particles tend to stick to each other; (2) disappearance of particles as they adhere to surrounding substrate surfaces such as glass, metal, or polymer. By investigating the effects of sonication treatment and surface modification by five types of surfactants, including nonylphenol ethoxylate (NP9), polyvinyl pyrrolidone (PVP), human serum albumin (HSA), sodium dodecyl sulfate (SDS) and citrate ions on the dispersion stability, the varying self-aggregation and adhesion of gold nanoparticles dispersed in PBS are demonstrated. The results showed that PVP effectively prevented aggregation, while HSA exhibited the best performance in avoiding the adhesion of gold nanoparticle in PBS onto glass and metal. The simple principle of this method makes it a high potential to be applied to other nanoparticles, including virus particles, used in dispersing and processing.

  20. An Empirical Analysis of Australian Gold Mining Firms

    OpenAIRE

    Baur, Dirk G.

    2012-01-01

    This paper studies the exposure of Australian gold-mining firms to changes in the gold price, the stock market and the Australian dollar - US dollar exchange rate. The empirical analysis uses daily, weekly and monthly data of all gold-mining firms in the S&P/ASX All Ordinaries Gold Index for the period from January 1980 to December 2010 and finds that the average gold beta is 0.67 for gold denominated in US dollar and 0.38 for gold denominated in Australian dollars. The study also finds subst...

  1. Source Strata of Gold in Western Guangdong—Their Identification and Significance in Gold Mineralization

    Institute of Scientific and Technical Information of China (English)

    陆建军; 吴劲薇; 等

    1995-01-01

    Strata of different geological periods extensively outcrop in western Guang-dong Province, but most gold deposits are restricted to the Middle-Late Proterozoic Yunkai Group and the Cambrian Bacun Group,showing obvious strata-boun character-istics .Gold abundance and trace element geochemistry of the Yunkai and Bacun Groups are compared with those of the Ordovician and Silurian strta.The Yunkai Group is considered to be the source strata for gold mineralization in the region.

  2. Enhancing the reactivity of gold: Nanostructured Au(111) adsorbs CO

    Science.gov (United States)

    Hoffmann, F. M.; Hrbek, J.; Ma, S.; Park, J. B.; Rodriguez, J. A.; Stacchiola, D. J.; Senanayake, S. D.

    2016-08-01

    Low-coordinated sites are surface defects whose presence can transform a surface of inert or noble metal such as Au into an active catalyst. Starting with a well-ordered Au(111) surface we prepared by ion sputtering gold surfaces modified by pits, used microscopy (STM) for their structural characterization and CO spectroscopy (IRAS and NEXAFS) for probing reactivity of surface defects. In contrast to the Au(111) surface CO adsorbs readily on the pitted surfaces bonding to low-coordinated sites identified as step atoms forming {111} and {100} microfacets. Pitted nanostructured surfaces can serve as interesting and easily prepared models of catalytic surfaces with defined defects that offer an attractive alternative to vicinal surfaces or nanoparticles commonly employed in catalysis science.

  3. Biomedical Applications of DNA-Conjugated Gold Nanoparticles.

    Science.gov (United States)

    Wang, Chun-Chi; Wu, Shou-Mei; Li, Hung-Wen; Chang, Huan-Tsung

    2016-06-16

    Gold nanoparticles (AuNPs) are useful for diagnostic and biomedical applications, mainly because of their ease in preparation and conjugation, biocompatibility, and size-dependent optical properties. However, bare AuNPs do not possess specificity for targets. AuNPs conjugated with DNA aptamers offer specificity for various analytes, such as proteins and small molecules/ions. Although DNA aptamers themselves have therapeutic and target-recognizing properties, they are susceptible to degradation in vivo. When DNA aptamers are conjugated to AuNPs, their stability and cell uptake efficiency both increase, making aptamer-AuNPs suitable for biomedical applications. Additionally, drugs can be efficiently conjugated with DNA aptamer-AuNPs to further enhance their therapeutic efficiency. This review focuses on the applications of DNA aptamer-based AuNPs in several biomedical areas, including anticoagulation, anticancer, antibacterial, and antiviral applications.

  4. Mechanism of glucose electrochemical oxidation on gold surface

    KAUST Repository

    Pasta, Mauro

    2010-08-01

    The complex oxidation of glucose at the surface of gold electrodes was studied in detail in different conditions of pH, buffer and halide concentration. As observed in previous studies, an oxidative current peak occurs during the cathodic sweep showing a highly linear dependence on glucose concentration, when other electrolyte conditions are unchanged. The effect of the different conditions on the intensity of this peak has stressed the limitations of the previously proposed mechanisms. A mechanism able to explain the presence of this oxidative peak was proposed. The mechanism takes into account ion-sorption and electrochemical adsorption of OH-, buffer species (K2HPO4/KH2PO4) and halides. © 2010 Elsevier Ltd. All rights reserved.

  5. Electrochemical measurements on a droplet using gold microelectrodes

    Science.gov (United States)

    Jenabi, Amin; Souri, Asma; Rastkhadiv, Ali

    2016-03-01

    Facile methods of ion recognition are important for the fabrication of electronic tongue systems. In this work, we demonstrate performing pulsed conductometry on microliter electrolyte droplets dropped on gold microelectrodes vapor deposited on soda lime glass slides. A droplet is dropped between two microelectrodes when a voltage waveform from a preprogramed power supply is applied on them. The temporal variation of the electric current passing through the droplet is recorded, digitized and stored. The obtained data are compared with the database formed out of the previous experiences for the classification of the sample electrolytes. It is shown that the shape of the voltage waveform is the important parameter of the process. We devised a method for the optimization of the voltage waveform profile for obtaining the maximum of discriminating information from the recorded current variations.

  6. Bio-fabrication of gold nanoparticles using aqueous extract of red tomato and its use as a colorimetric sensor

    Science.gov (United States)

    Barman, Gadadhar; Maiti, Swarnali; Laha, Jayasree Konar

    2013-04-01

    In this work, we report a green method for the synthesis of gold nanoparticles (GNP) using the aqueous extract of red tomato ( Lycopersicon esculentum). We believe that citric acid and ascorbic acid present in tomato juice are responsible for the reduction of gold ions. This biosynthesized GNP in the presence of sodium dodecyl sulfate has been used as a colorimetric sensor to detect and estimate the pesticide, methyl parathion. The GNP in the presence of methyl parathion shows a new peak at 400 nm due to the formation of 4-nitrophenolate ion by catalytic hydrolysis of methyl parathion in alkaline medium. A calibration curve between the absorption coefficients of the 400-nm peak versus the concentration of the pesticide allows the quantitative estimation of the 4-nitrophenolate ion, thereby enabling indirect estimation of methyl parathion present in the system.

  7. Structural controls on Carlin-type gold mineralization in the gold bar district, Eureka County, Nevada

    Science.gov (United States)

    Yigit, O.; Nelson, E.P.; Hitzman, M.W.; Hofstra, A.H.

    2003-01-01

    The Gold Bar district in the southern Roberts Mountains, 48 km northwest of Eureka, Nevada, contains one main deposit (Gold Bar), five satellite deposits, and other resources. Approximately 0.5 Moz of gold have been recovered from a resource of 1,639,000 oz of gold in Carlin-type gold deposits in lower plate, miogeoclinal carbonate rocks below the Roberts Mountains thrust. Host rocks are unit 2 of the Upper Member of the Devonian Denay Formation and the Bartine Member of the McColley Canyon Formation. Spatial and temporal relations between structures and gold mineralization indicate that both pre-Tertiary and Tertiary structures were important controls on gold mineralization. Gold mineralization occurs primarily along high-angle Tertiary normal faults, some of which are reactivated reverse faults of Paleozoic or Mesozoic age. Most deposits are localized at the intersection of northwest- and northeast-striking faults. Alteration includes decalcification, and to a lesser extent, silicification along high-angle faults. Jasperoid (pervasive silicification), which formed along most faults and in some strata-bound zones, accounts for a small portion of the ore in every deposit. In the Gold Canyon deposit, a high-grade jasperoid pipe formed along a Tertiary normal fault which was localized along a zone of overturned fault-propagation folds and thrust faults of Paleozoic or Mesozoic age.

  8. 从浮选尾矿中回收含金黄铁矿实践%Reclamation of pyrite containing gold from gold floatation tailings

    Institute of Scientific and Technical Information of China (English)

    朱飞; 赵建伟; 王艳慧; 石凤野; 唐彦臣

    2012-01-01

    对河南金源金矿浮选尾矿采用螺旋溜槽粗选、摇床精选重选工艺进行二次回收,得到含金硫精矿,取得了较好的经济效益,每年可为企业获得约1 660万元利润.%Nowadays, cyanidation method is still the most important method for gold leaching from ore in commercial production. The commercial methods to recover gold from pregnant solution or slurry of cyanidation are zinc powder displacement, activated carbon adsorption, ion-exchange and electrodeposition; while the dissolvent leaching and liquid membrane methods are still in research. The paper discusses the progress, application, research and choosing of the mentioned recovery methods.

  9. Adsorption-induced restructuring of gold nanochains

    DEFF Research Database (Denmark)

    Bahn, Sune Rastad; Lopez, Nuria; Nørskov, Jens Kehlet;

    2002-01-01

    The chemical properties of single-atomic chains of gold atoms are investigated using density functional calculations. The nanochains are shown to be unusually chemically active with strong chemisorption of oxygen atoms and carbon monoxide. The chemisorption energies vary significantly with the st......The chemical properties of single-atomic chains of gold atoms are investigated using density functional calculations. The nanochains are shown to be unusually chemically active with strong chemisorption of oxygen atoms and carbon monoxide. The chemisorption energies vary significantly...... with the strain/stress conditions for the chain. Oxygen atoms are found to energetically prefer to get incorporated into a chain forming a new type of gold-oxygen nanochain with a conductance of one quantum unit. We suggest that the long bond lengths observed in electron microscopy investigations of gold chains...

  10. Alaska gold rush trails study: Preliminary draft

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — Preliminary study draft, with maps, of seven gold rush trails in Alaska, to determine suitability for inclusion in the National Scenic Trails system and their...

  11. Novel Catalysis by Gold: A Modern Alchemy

    Science.gov (United States)

    Haruta, Masatake

    Gold has long been neglected as a catalyst because of its chemical inertness. However, when gold is deposited as nanoparticles on carbon and polymer materials as well as on base metal oxides and hydroxides, it exhibits unique catalytic properties for many reactions such as CO oxidation at a temperature as low as 200 K, gas phase direct epoxidation of propylene, and aerobic oxidation of glucose to gluconic acid. The structure-catalytic activity correlations are discussed with emphasis on the contact structure, support selection, and the size control of gold particles. Gold clusters with diameters smaller than 2 nm are expected to exhibit novel properties in catalysis, optics, and electronics depending on the size (number of atoms), shape, and the electronic and chemical interaction with the support materials. The above achievements and attempts can be regarded as a modern alchemy that creates valuables by means of the noblest element with little practical use.

  12. Preparation of Gold Nanoparticles Protected with Polyelectrolyte

    Institute of Scientific and Technical Information of China (English)

    Xu Ping SUN; Zhe Ling ZHANG; Bai Lin ZHANG; Xian Dui DONG; Shao Jun DONG; Er Kang WANG

    2003-01-01

    Gold nanoparticles were synthesized through the reduction of tetrachlorauric acid (HAuCl4) by NaBH4, with polyethyleneimine(PEI) as stabilizer. The nanoparticles were characterized by UV-vis spectroscopy and atomic force microscopy(AFM).

  13. Analysis on the Impact of the Fluctuation of the International Gold Prices on the Chinese Gold Stocks

    Directory of Open Access Journals (Sweden)

    Jiankang Jin

    2014-01-01

    Full Text Available Five gold stocks in Chinese Shanghai and Shenzhen A-share and Comex gold futures are chosen to form the sample, for the purpose of analysing the impact of the fluctuation of the international gold prices on the gold stocks in Chinese Shanghai and Shenzhen A-share. Using the methods of unit root test, Granger causality test, VAR model, and impulse response function, this paper has analysed the relationship between the price change of the international gold futures and the price fluctuation of gold stocks in Chinese Shanghai and Shenzhen comprehensively. The results suggest the fluctuation of the international gold futures has a strong influence on the domestic futures.

  14. Selective detection and recovery of gold at tannin-immobilized non-conducting electrode

    International Nuclear Information System (INIS)

    Highlights: • Selective detection of gold at non-conducting (NC) polymer modified electrode. • Mimosa tannin oxidized on glassy carbon electrode surface as NC polymeric film. • Permselective diffusion and mediated electron transfer at NC electrode surface. • Chemical recovery of gold is due to the reducing ability of the NC polymeric film. • Adsorption capacity of Au(III) on carbon fiber was 29 ± 1.45 mg g−1 at 60 °C. - Abstract: A tannin-immobilized glassy carbon electrode (TIGC) was prepared via electrochemical oxidation of the naturally occurring polyphenolic mimosa tannin, which generated a non-conducting polymeric film (NCPF) on the electrode surface. The fouling of the electrode surface by the electropolymerized film was evaluated by monitoring the electrode response of ferricyanide ions as a redox marker. The NCPF was permselective to HAuCl4, and the electrochemical reduction of HAuCl4 to metallic gold at the TIGC electrode was evaluated by recording the reduction current during cyclic voltammetry measurement. In the mixed electrolyte containing HAuCl4 along with FeCl3 and/or CuCl2, the NCPF remained selective toward the electrochemical reduction of HAuCl4 into the metallic state. The chemical reduction of HAuCl4 into metallic gold was also observed when the NCPF was inserted into an acidic gold solution overnight. The adsorption capacity of Au(III) on tannin-immobilized carbon fiber was 29 ± 1.45 mg g−1 at 60 °C. In the presence of excess Cu(II) and Fe(III), tannin-immobilized NCPF proved to be an excellent candidate for the selective detection and recovery of gold through both electrochemical and chemical processes

  15. Selective detection and recovery of gold at tannin-immobilized non-conducting electrode

    Energy Technology Data Exchange (ETDEWEB)

    Banu, Khaleda, E-mail: kbanu@ucla.edu [Department of Molecular and Medical Pharmacology, University of California, Los Angeles, CA 90095 (United States); Venture Business Laboratory, Center for Advanced Science and Innovation, Osaka University, Suita, Osaka 565-0871 (Japan); Shimura, Takayoshi [Venture Business Laboratory, Center for Advanced Science and Innovation, Osaka University, Suita, Osaka 565-0871 (Japan); Department of Material and Life Science, Division of Advanced Science and Biotechnology, Graduate School of Engineering, Osaka University (Japan); Sadeghi, Saman, E-mail: samsadeghi@mednet.ucla.edu [Department of Molecular and Medical Pharmacology, University of California, Los Angeles, CA 90095 (United States)

    2015-01-01

    Highlights: • Selective detection of gold at non-conducting (NC) polymer modified electrode. • Mimosa tannin oxidized on glassy carbon electrode surface as NC polymeric film. • Permselective diffusion and mediated electron transfer at NC electrode surface. • Chemical recovery of gold is due to the reducing ability of the NC polymeric film. • Adsorption capacity of Au(III) on carbon fiber was 29 ± 1.45 mg g{sup −1} at 60 °C. - Abstract: A tannin-immobilized glassy carbon electrode (TIGC) was prepared via electrochemical oxidation of the naturally occurring polyphenolic mimosa tannin, which generated a non-conducting polymeric film (NCPF) on the electrode surface. The fouling of the electrode surface by the electropolymerized film was evaluated by monitoring the electrode response of ferricyanide ions as a redox marker. The NCPF was permselective to HAuCl{sub 4}, and the electrochemical reduction of HAuCl{sub 4} to metallic gold at the TIGC electrode was evaluated by recording the reduction current during cyclic voltammetry measurement. In the mixed electrolyte containing HAuCl{sub 4} along with FeCl{sub 3} and/or CuCl{sub 2}, the NCPF remained selective toward the electrochemical reduction of HAuCl{sub 4} into the metallic state. The chemical reduction of HAuCl{sub 4} into metallic gold was also observed when the NCPF was inserted into an acidic gold solution overnight. The adsorption capacity of Au(III) on tannin-immobilized carbon fiber was 29 ± 1.45 mg g{sup −1} at 60 °C. In the presence of excess Cu(II) and Fe(III), tannin-immobilized NCPF proved to be an excellent candidate for the selective detection and recovery of gold through both electrochemical and chemical processes.

  16. Critical View on Electrochemical Impedance Spectroscopy Using the Ferri/Ferrocyanide Redox Couple at Gold Electrodes.

    Science.gov (United States)

    Vogt, Stephan; Su, Qiang; Gutiérrez-Sánchez, Cristina; Nöll, Gilbert

    2016-04-19

    Electrochemical or faradaic impedance spectroscopy (EIS) using the ferri/ferrocyanide couple as a redox probe at gold working electrodes was evaluated with respect to its ability to monitor consecutive surface modification steps. As a model reaction, the reversible hybridization and dehybridization of DNA was studied. Thiol-modified single stranded DNA (ssDNA, 20 bases, capture probe) was chemisorbed to a gold electrode and treated with a solution of short thiols to release nonspecifically adsorbed DNA before hybridization with complementary ssDNA (20 bases, target) was carried out. Reversible dehybridization was achieved by intense rinsing with pure water. The experimental procedures were optimized by kinetic surface plasmon resonance (SPR) and quartz crystal microbalance with dissipation (QCM-D) measurements to maximize the increase in reflectivity or decrease in frequency upon hybridization before hybridization/dehybridization was also monitored by EIS. In contrast to SPR and QCM-D, repeatable EIS measurements were not possible at first. Combined SPR/EIS and QCM-D/EIS measurements revealed that during EIS the gold surface is seriously damaged due to the presence of CN(-) ions, which are released from the ferri/ferrocyanide redox probe. Even at optimized experimental conditions, etching the gold electrodes could not be completely suppressed and the repeatability of the EIS measurements was limited. In three out of four experimental runs, only two hybridization/dehybridization steps could be monitored reversibly by EIS. Thereafter etching the gold electrode significantly contributed to the EIS spectra whereas the QCM-D response was still repeatable. Hence great care has to be taken when this technique is used to monitor surface modification at gold electrodes.

  17. Gold and Silver as Monetary Metals

    OpenAIRE

    John Cooper

    2006-01-01

    Commodity money systems, based upon gold or silver, provided relative economic stability for centuries. On the other hand, our modern paper money system, based upon unbacked government liabilities, is particularly vulnerable to abuse. The various financial crises during the twentieth century bear witness to that. This paper seeks to explain the mechanics of the former Gold and Silver Standards and provides an overview of America’s experience with its bimetallic system.

  18. Radiochemical separation of gold by amalgam exchange

    Science.gov (United States)

    Ruch, R.R.

    1970-01-01

    A rapid and simple method for the radiochemical separation of gold after neutron activation. The technique is based on treatment with a dilute indium-gold amalgam, both chemical reduction and isotopic exchange being involved. The counting efficiency for 198Au in small volumes of the amalgam is good. Few interferences occur and the method is applicable to clays, rocks, salts and metals. The possibility of determining silver, platinum and palladium by a similar method is mentioned. ?? 1970.

  19. PIXE analysis of Trojan gold jewelry

    Science.gov (United States)

    Swann, C. P.; Betancourt, P. P.; Fleming, S.; Floyd, C. R.

    1997-07-01

    Technological advancements in the production of gold jewelry from the Troad in northwest Anatolia in the third millennium BC are investigated by PIXE. Results indicate a higher percentage of Cu at the interface between joined pieces of gold than exists elsewhere on the jewelry, away from joinings. The results indicate the probable use of copper salts as a flux in the manufacture of jewelry with granulation.

  20. Price Discovery in the Chinese Gold Market

    OpenAIRE

    Jin, Muzhao; Li, Youwei; Wang, Jianxin; Yang, Yung Chiang

    2016-01-01

    This study conducts price discovery analysis in the Chinese gold market. Our result indicates that the price discovery in Chinese gold market occurs predominantly in the futures market. The result is robust to the different measures of price discovery, namely information share, component share, and information leadership share. Partitioning the daily trades into three trading sessions, we find that the dominance of the futures market occurs in all trading sessions. We further investigate the ...

  1. Surface modification of gold nanoparticles and nanoclusters

    OpenAIRE

    Sokolowska, Karolina

    2016-01-01

    Gold nanoparticles are used in many beneficial technological applications in biochemistry, medicine and electronics. Among them, monolayer protected gold nanoclusters (MPCs) have received a significant attention in the scientific community due to their well-defined atomic structure, which is important for fundamental studies of nanoparticles properties and their functionalization. These particles, with a precise number of atoms, exhibit size-dependent optical, chemical and electronic properti...

  2. Effective PEGylation of gold nanorods

    Science.gov (United States)

    Schulz, F.; Friedrich, W.; Hoppe, K.; Vossmeyer, T.; Weller, H.; Lange, H.

    2016-03-01

    Standard procedures to coat gold nanorods (AuNR) with poly(ethylene glycol) (PEG)-based ligands are not reliable and high PEG-grafting densities are not achieved. In this work, the ligand exchange of AuNR with PEGMUA, a tailored PEG-ligand bearing a C10 alkylene spacer, is studied. PEGMUA provides AuNR with very high stability against oxidative etching with cyanide. This etching reaction is utilized to study the ligand exchange in detail. Ligand exchange is faster, less ligand consuming and more reproducible with assisting chloroform extraction. Compared to PEG ligands commonly used, PEGMUA provides much higher colloidal and chemical stability. Further analyses based on NMR-, IR- and UV/Vis-spectroscopy reveal that significantly higher PEG-grafting densities, up to ~3 nm-2, are obtained with PEGMUA. This demonstrates how the molecular structure of the PEG ligand can be used to dramatically improve the ligand exchange and to synthesize PEGylated AuNR with high chemical and colloidal stability and high PEG grafting densities. Such AuNR are especially interesting for applications in nanomedicine.Standard procedures to coat gold nanorods (AuNR) with poly(ethylene glycol) (PEG)-based ligands are not reliable and high PEG-grafting densities are not achieved. In this work, the ligand exchange of AuNR with PEGMUA, a tailored PEG-ligand bearing a C10 alkylene spacer, is studied. PEGMUA provides AuNR with very high stability against oxidative etching with cyanide. This etching reaction is utilized to study the ligand exchange in detail. Ligand exchange is faster, less ligand consuming and more reproducible with assisting chloroform extraction. Compared to PEG ligands commonly used, PEGMUA provides much higher colloidal and chemical stability. Further analyses based on NMR-, IR- and UV/Vis-spectroscopy reveal that significantly higher PEG-grafting densities, up to ~3 nm-2, are obtained with PEGMUA. This demonstrates how the molecular structure of the PEG ligand can be used to

  3. Composite fluorocarbon membranes by surface-initiated polymerization from nanoporous gold-coated alumina.

    Science.gov (United States)

    Escobar, Carlos A; Zulkifli, Ahmad R; Faulkner, Christopher J; Trzeciak, Alex; Jennings, G Kane

    2012-02-01

    This manuscript describes the versatile fabrication and characterization of a novel composite membrane that consists of a porous alumina support, a 100 nm thick nanoporous gold coating, and a selective poly(5-(perfluorohexyl)norbornene) (pNBF6) polymer that can be grown exclusively from the nanoporous gold or throughout the membrane. Integration of the three materials is achieved by means of silane and thiol chemistry, and the use of surface-initiated ring-opening metathesis polymerization (SI-ROMP) to grow the pNBF6. The use of SI-ROMP allows tailoring of the extent of polymerization of pNBF6 throughout the structure by varying polymerization time. Scanning electron microscopy (SEM) images indicate that the thin polymer films cover the structure entirely. Cross-sectional SEM images of the membrane not only corroborate growth of the pNBF6 polymer within both the porous alumina and the nanoporous gold coating but also show the growth of a pNBF6 layer between these porous substrates that lifts the nanoporous gold coating away from the alumina. Advancing contact angle (θ(A)) measurements show that the surfaces of these composite membranes exhibit both hydrophobic (θ(A) = 121-129)° and oleophobic (θ(A) = 69-74)° behavior due to the fluorocarbon side chains of the pNBF6 polymer that dominate the surface. Results from electrochemical impedance spectroscopy (EIS) confirm that the membranes provide effective barriers to aqueous ions, as evidenced by a resistive impedance on the order of 1 × 10(7) Ω cm(2). Sulfonation of the polymer backbone substantially enhances ion transport through the composite membrane, as indicated by a 40-60 fold reduction in resistive impedance. Ion transport and selectivity of the membrane change by regulating the polymerization time. The fluorinated nature of the sulfonated polymer renders the membrane selective toward molecules with similar chemical characteristics. PMID:22195729

  4. A thermally stable gold(III) hydride: synthesis, reactivity, and reductive condensation as a route to gold(II) complexes.

    Science.gov (United States)

    Roşca, Dragoş-Adrian; Smith, Dan A; Hughes, David L; Bochmann, Manfred

    2012-10-15

    Going for gold: The first thermally stable gold(III) hydride [(C N C)*AuH] is presented. It undergoes regioselective insertions with allenes to give gold(III) vinyl complexes, and reductive condensation with [(C N C)*AuOH] to the air-stable Au(II) product, [(C N C)*(2)Au(2)], with a short nonbridged gold-gold bond.

  5. Coulomb-driven energy boost of heavy ions for laser-plasma acceleration.

    Science.gov (United States)

    Braenzel, J; Andreev, A A; Platonov, K; Klingsporn, M; Ehrentraut, L; Sandner, W; Schnürer, M

    2015-03-27

    An unprecedented increase of kinetic energy of laser accelerated heavy ions is demonstrated. Ultrathin gold foils have been irradiated by an ultrashort laser pulse at a peak intensity of 8×10^{19}  W/  cm^{2}. Highly charged gold ions with kinetic energies up to >200  MeV and a bandwidth limited energy distribution have been reached by using 1.3 J laser energy on target. 1D and 2D particle in cell simulations show how a spatial dependence on the ion's ionization leads to an enhancement of the accelerating electrical field. Our theoretical model considers a spatial distribution of the ionization inside the thin target, leading to a field enhancement for the heavy ions by Coulomb explosion. It is capable of explaining the energy boost of highly charged ions, enabling a higher efficiency for the laser-driven heavy ion acceleration.

  6. Coulomb-driven energy boost of heavy ions for laser-plasma acceleration.

    Science.gov (United States)

    Braenzel, J; Andreev, A A; Platonov, K; Klingsporn, M; Ehrentraut, L; Sandner, W; Schnürer, M

    2015-03-27

    An unprecedented increase of kinetic energy of laser accelerated heavy ions is demonstrated. Ultrathin gold foils have been irradiated by an ultrashort laser pulse at a peak intensity of 8×10^{19}  W/  cm^{2}. Highly charged gold ions with kinetic energies up to >200  MeV and a bandwidth limited energy distribution have been reached by using 1.3 J laser energy on target. 1D and 2D particle in cell simulations show how a spatial dependence on the ion's ionization leads to an enhancement of the accelerating electrical field. Our theoretical model considers a spatial distribution of the ionization inside the thin target, leading to a field enhancement for the heavy ions by Coulomb explosion. It is capable of explaining the energy boost of highly charged ions, enabling a higher efficiency for the laser-driven heavy ion acceleration. PMID:25860747

  7. Curcumin: the Indian solid gold.

    Science.gov (United States)

    Aggarwal, Bharat B; Sundaram, Chitra; Malani, Nikita; Ichikawa, Haruyo

    2007-01-01

    Turmeric, derived from the plant Curcuma longa, is a gold-colored spice commonly used in the Indian subcontinent, not only for health care but also for the preservation of food and as a yellow dye for textiles. Curcumin, which gives the yellow color to turmeric, was first isolated almost two centuries ago, and its structure as diferuloylmethane was determined in 1910. Since the time of Ayurveda (1900 Bc) numerous therapeutic activities have been assigned to turmeric for a wide variety of diseases and conditions, including those of the skin, pulmonary, and gastrointestinal systems, aches, pains, wounds, sprains, and liver disorders. Extensive research within the last half century has proven that most of these activities, once associated with turmeric, are due to curcumin. Curcumin has been shown to exhibit antioxidant, anti-inflammatory, antiviral, antibacterial, antifungal, and anticancer activities and thus has a potential against various malignant diseases, diabetes, allergies, arthritis, Alzheimer's disease, and other chronic illnesses. These effects are mediated through the regulation of various transcription factors, growth factors, inflammatory cytokines, protein kinases, and other enzymes. Curcumin exhibits activities similar to recently discovered tumor necrosis factor blockers (e.g., HUMIRA, REMICADE, and ENBREL), a vascular endothelial cell growth factor blocker (e.g., AVASTIN), human epidermal growth factor receptor blockers (e.g., ERBITUX, ERLOTINIB, and GEFTINIB), and a HER2 blocker (e.g., HERCEPTIN). Considering the recent scientific bandwagon that multitargeted therapy is better than monotargeted therapy for most diseases, curcumin can be considered an ideal "Spice for Life".

  8. Crystal structure of gold hydride

    International Nuclear Information System (INIS)

    Highlights: • Volume expansion of metal hydrides is due to the increase in the s-band filling. • AuH structure is similar to that of Hg having one more s electron compared to Au. • Structure stability of both Hg and AuH is governed by the Hume-Rothery rule. - Abstract: A number of transition metal hydrides with close-packed metal sublattices of fcc or hcp structures with hydrogen in octahedral interstitial positions were obtained by the high-pressure-hydrogen technique described by Ponyatovskii et al. (1982). In this paper we consider volume increase of metals by hydrogenation and possible crystal structure of gold hydride in relation with the structure of mercury, the nearest neighbor of Au in the Periodic table. Suggested structure of AuH has a basic tetragonal body-centered cell that is very similar to the mercury structure Hg-t I 2. The reasons of stability for this structure are discussed within the model of Fermi sphere–Brillouin zone interactions

  9. Crystal structure of gold hydride

    Energy Technology Data Exchange (ETDEWEB)

    Degtyareva, Valentina F., E-mail: degtyar@issp.ac.ru

    2015-10-05

    Highlights: • Volume expansion of metal hydrides is due to the increase in the s-band filling. • AuH structure is similar to that of Hg having one more s electron compared to Au. • Structure stability of both Hg and AuH is governed by the Hume-Rothery rule. - Abstract: A number of transition metal hydrides with close-packed metal sublattices of fcc or hcp structures with hydrogen in octahedral interstitial positions were obtained by the high-pressure-hydrogen technique described by Ponyatovskii et al. (1982). In this paper we consider volume increase of metals by hydrogenation and possible crystal structure of gold hydride in relation with the structure of mercury, the nearest neighbor of Au in the Periodic table. Suggested structure of AuH has a basic tetragonal body-centered cell that is very similar to the mercury structure Hg-t I 2. The reasons of stability for this structure are discussed within the model of Fermi sphere–Brillouin zone interactions.

  10. Subchronic inhalation toxicity of gold nanoparticles

    Directory of Open Access Journals (Sweden)

    Chung Yong

    2011-05-01

    Full Text Available Abstract Background Gold nanoparticles are widely used in consumer products, including cosmetics, food packaging, beverages, toothpaste, automobiles, and lubricants. With this increase in consumer products containing gold nanoparticles, the potential for worker exposure to gold nanoparticles will also increase. Only a few studies have produced data on the in vivo toxicology of gold nanoparticles, meaning that the absorption, distribution, metabolism, and excretion (ADME of gold nanoparticles remain unclear. Results The toxicity of gold nanoparticles was studied in Sprague Dawley rats by inhalation. Seven-week-old rats, weighing approximately 200 g (males and 145 g (females, were divided into 4 groups (10 rats in each group: fresh-air control, low-dose (2.36 × 104 particle/cm3, 0.04 μg/m3, middle-dose (2.36 × 105 particle/cm3, 0.38 μg/m3, and high-dose (1.85 × 106 particle/cm3, 20.02 μg/m3. The animals were exposed to gold nanoparticles (average diameter 4-5 nm for 6 hours/day, 5 days/week, for 90-days in a whole-body inhalation chamber. In addition to mortality and clinical observations, body weight, food consumption, and lung function were recorded weekly. At the end of the study, the rats were subjected to a full necropsy, blood samples were collected for hematology and clinical chemistry tests, and organ weights were measured. Cellular differential counts and cytotoxicity measurements, such as albumin, lactate dehydrogenase (LDH, and total protein were also monitored in a cellular bronchoalveolar lavage (BAL fluid. Among lung function test measurements, tidal volume and minute volume showed a tendency to decrease comparing control and dose groups during the 90-days of exposure. Although no statistically significant differences were found in cellular differential counts, histopathologic examination showed minimal alveoli, an inflammatory infiltrate with a mixed cell type, and increased macrophages in the high-dose rats. Tissue

  11. Tectonic setting of Late Cenozoic gold mineralization in the gold belt of Costa Rica

    Energy Technology Data Exchange (ETDEWEB)

    Deruyter, V.D.

    1985-01-01

    The Gold Belt of Costa Rica is a northwest-elongated zone 15 km wide by 120 km long containing numerous auriferous quartz veins and pyritic silicified patterns upon which abundant small mines are developed. Gold veins are related principally to northeast-southwest and north-south striking, steeply dipping faults. Higher grade ore and thicker veins invariably occur at intersections of these fracture orientations, indicating simultaneous opening at the time of gold introduction. Restriction of gold veins to the northwest-trending arc of Miocene Aguacate Group andesite volcanic rocks, a product of Cocos Plate subduction, suggested approximately coeval formation, but recognition by the writer of the important role played by 2-5 m.y. old altered, gold mineralized rhyolite dikes intruded along north-south gold vein structures and intimately involved with high grade ores at the Esperanza Mine and Rio Chiquito prospect, for example, suggest a much younger period of fracturing and gold introduction. The rhyolite intrusions are more brittle and stockwork mineralized than andesite host rocks and form bulk tonnage gold targets. Initiation of right-lateral movement along the north-south Panama Fracture Zone at 5 m.y.a. within the pattern of northeastward Cocos Plate subduction may have tapped rhyolites from subvolcanic magma chambers into new faults.

  12. Assembling Tunable Time-Resolved Fluorescence Layer onto Nano-Gold

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The assembling of a coating of time-resolved fluorescent chelator BSPDA (abbreviated for 4,7-bis(sulfhydrylphenyl)-1,10-phenanthroline-2,9-dicarboxylic acid) onto a nano-gold layer was demonstrated. First, BSPDA was synthesized by simple procedures, and then an approach was developed to immobilize BSPDA onto the nano-gold layer deposited on a silane modified glass substrate, whereby europium ion (Ⅲ, Eu3+) was captured and released owing to the interactive process of complexation and dissociation between BSPDA functionalized coating and Eu3+ solution. The fluorescence spectra and related lifetimes were determined. Also, the BSPDA functionalized coating's specific complexation with Eu3+ on the BSPDA assembly layer and the nonspecific adsorption of Eu3+ on the nano-gold layer were compared. These results allowed a selective complexation of Eu3+ by assembling a BSPDA chelating layer on the nano-gold layer;thus, a tunable time-resolved fluorescent layer was covalently attached. The results of the nanoparticle assembling and probing (or labeling) processes to specific bio-systems were very interesting and had significant implications to time-resolved-fluorescence-based detection on biosensor surfaces such as DNA chip and to arrayed light display devices.

  13. Gold nanoparticles directly modified glassy carbon electrode for non-enzymatic detection of glucose

    Energy Technology Data Exchange (ETDEWEB)

    Chang, Gang; Shu, Honghui; Ji, Kai [Ministry-of-Education Key Laboratory for the Green Preparation and Application of Functional Materials, Faculty of Materials Science and Engineering, Hubei University, No. 368 Youyi Avenue, Wuchang, Wuhan 430062 (China); Oyama, Munetaka [Department of Material Chemistry, Graduate School of Engineering, Kyoto University, Nishikyo-ku, Kyoto 615-8520 (Japan); Liu, Xiong [Ministry-of-Education Key Laboratory for the Green Preparation and Application of Functional Materials, Faculty of Materials Science and Engineering, Hubei University, No. 368 Youyi Avenue, Wuchang, Wuhan 430062 (China); He, Yunbin, E-mail: ybhe@hubu.edu.cn [Ministry-of-Education Key Laboratory for the Green Preparation and Application of Functional Materials, Faculty of Materials Science and Engineering, Hubei University, No. 368 Youyi Avenue, Wuchang, Wuhan 430062 (China)

    2014-01-01

    This work describes controllable preparation of gold nanoparticles on glassy carbon electrodes by using the seed mediated growth method, which contains two steps, namely, nanoseeds attachment and nanocrystals growth. The size and the dispersion of gold nanoparticles grown on glassy carbon electrodes could be easily tuned through the growth time based on results of field-emission scanning electron microscopy. Excellent electrochemical catalytic characteristics for glucose oxidation were observed for the gold nanoparticles modified glassy carbon electrodes (AuNPs/GC), resulting from the extended active surface area provided by the dense gold nanoparticles attached. It exhibited a wide linear range from 0.1 mM to 25 mM with the sensitivity of 87.5 μA cm{sup −2} mM{sup −1} and low detection limit down to 0.05 mM for the sensing of glucose. The common interfering species such as chloride ion, ascorbic acid, uric acid and 4-acetamidophenol were verified having no interference effect on the detection of glucose. It is demonstrated that the seed mediated method is one of the facile approaches for fabricating Au nanoparticles modified substrates, which could work as one kind of promising electrode materials for the glucose nonenzymatic sensing.

  14. Biological synthesis and characterization of intracellular gold nanoparticles using biomass of Aspergillus fumigatus

    Indian Academy of Sciences (India)

    Pranav Vasanthi Bathrinarayanan; Dilliganesh Thangavelu; Vasanth Kumar Muthukumarasamy; Chamundeeswari Munusamy; Baskar Gurunathan

    2013-12-01

    Nanotechnology is emerging as one of the most important and revolutionizing area in research field. Nanoparticles are produced by various methods like physical, chemical, mechanical and biological. Biological methods of reduction of metal ions using plants or microorganisms are often preferred because they are clean, nontoxic, safe, biocompatible and environmentally acceptable. In the present study, Aspergillus fumigatus was used for the intracellular synthesis of gold nanoparticles. Stable nanoparticles were produced when an aqueous solution of chloroauric acid (HAuCl4) was reduced by A. fumigatus biomass as the reducing agent. Production of nanoparticles was confirmed by the colour change from yellow to pinkish violet after ∼72 h of reaction. The produced nanoparticles were then characterized by Fourier transform infrared spectroscopy (FT–IR), scanning electron microscope (SEM), energy dispersive spectroscopy (EDS) and X-ray diffraction spectroscopy (XRD). SEM images of sample revealed that the nanoparticles were spherical, irregularly shaped with indefinite morphology. Biosynthesized gold nanoparticles were in the range of 85.1–210 nm in size. The presence of gold nanoparticle was confirmed by EDS analysis. Crystalline nature and face-centred cubic structure of synthesized gold nanoparticle was confirmed by XRD pattern.

  15. Moessbauer study of the chemical state of gold in gold ores

    International Nuclear Information System (INIS)

    Information on the chemical state of gold in gold ores has been obtained by 197Au Moessbauer spectroscopy in cases where the state of this element cannot be determined by such standard methods as optical or electron microscopy. Ore concentrates consisting mainly of pyrite or arsenopyrite and roasted ore and matte samples were studied. The results yielded directly the respective amounts of metallic and chemically bound gold. Unless the gold is metallic, its chemical state in the ores turns out to be different from that in the minerals studied so far as reference materials. The chemical processes taking place during various treatments of the ores, such as roasting or leaching, can also be followed by Moessbauer spectroscopy. It is hoped that Moessbauer spectroscopy will eventually facilitate the development of more efficient methods of gold extraction

  16. New method for measuring stopping powers using ion induced x-ray emission

    International Nuclear Information System (INIS)

    A new method for measuring the stopping power of matter for ions is presented. The techniques used are those developed for use in trace element analysis by proton induced x-ray emission. This new method has been validated by comparing the measured stopping powers for copper, silver, and gold at 100 keV with those reported by Allison and Warshaw for free standing foils. The agreement is excellent: +-1% for both copper and silver and +-2% for gold

  17. Kinetics and mechanism of the reaction of gold(III chloride complexes with formic acid

    Directory of Open Access Journals (Sweden)

    Pacławski K.

    2015-01-01

    Full Text Available In this work, the results of kinetic studies of the redox reaction of gold(III chloride complexes ([AuCl4]- with formic acid, are presented. Obtained data suggest the complex character of the reaction which leads to the [AuCl2]- and [AuCl3(COOH]- ions formation as intermediates. In the pH range over 2.5, the final product of the reaction is metallic gold. From the analysis of kinetic data, the rate limiting step is found to be the gold metallic phase formation. The stage of Au(III reduction is relatively fast with the second-order rate constant equal to 61.8 M-1s-1 at temperature 50ºC. The rate of the studied reaction depends on the temperature, reactants concentration and chloride ions concentration. As a result of the data analysis, the scheme of the reaction path has been suggested. Also, the values of enthalpy and entropy of activation for the reaction have been determined.

  18. Electrochemical Metalloimmunoassay Based on Enlargement of Gold Nanoparticle Label Treated with Ag Enhancement System

    Institute of Scientific and Technical Information of China (English)

    WANG Mei-jia; BAI Yu-bai; LI Tie-jin; YUAN Hang; JI Xiao-hui; LIU Zhao-yue; JIA Ruo-kun; WANG Lian-ying; LIU Yan-mei; MA Lan; LI Jing-hong

    2003-01-01

    A novel sensitive electrochemical immunoassay with colloidal gold as the antibody labeling tag and subsequent signal amplification by silver enhancement is described. Colloidal gold was treated by a light-sensitive silver enhancement system which made silver deposit on the surface of colloidal gold(form Au/Ag core-shell structure), followed by the release of the metallic silver atoms anchored on the antibody by oxidative dissolution of them in an acidic solution and the indirect determination of the dissolved Ag+ ions by anodic stripping voltammetry(ASV) at a carbon fiber microelectrode. The electrochemical signal is directly proportional to the amount of analyte(goat IgG) in the standard or a sample. The method was evaluated by means of a noncompetitive heterogeneous immunoassay of immunoglobulin G(IgG) with a concentration as low as 0.2 ng/mL. The high performance of the method is related to the sensitive ASV determination of silver(Ⅰ) at a carbon fiber microelectrode and to the release of a large number of Ag+ ions from each silver shell anchored on the analyte(goat IgG).

  19. EUV and Visible Spectroscopy of Promethiumlike Heavy Ions

    CERN Document Server

    Kobayashi, Yusuke; Omote, Kazuki; Komatsu, Akihiro; Sakoda, Junpei; Minoshima, Maki; Kato, Daiji; Li, Jiguang; Sakaue, Hiroyuki A; Murakami, Izumi; Nakamura, Nobuyuki

    2015-01-01

    We present extreme ultraviolet and visible spectra of promethiumlike tungsten and gold obtained with an electron beam ion trap (EBIT). Although the contributions from a few charge states are involved in the spectra, the charge state of the ion assigned to the observed lines is definitely identified by the time-of-flight analysis of the ions performed at the same time with the spectroscopic measurements. Experimental results are compared with collisional-radiative model calculations as well as previous experimental and theoretical studies.

  20. Silver, gold, and alloyed silver-gold nanoparticles: characterization and comparative cell-biologic action

    Energy Technology Data Exchange (ETDEWEB)

    Mahl, Dirk; Diendorf, Joerg; Ristig, Simon [University of Duisburg-Essen, Department of Inorganic Chemistry, Center for Nanointegration Duisburg-Essen (CeNIDE) (Germany); Greulich, Christina [Ruhr-University of Bochum, Bergmannsheil University Hospital/Surgical Research (Germany); Li Zian; Farle, Michael [University of Duisburg-Essen, Faculty of Physics, Center for Nanointegration Duisburg-Essen (CeNIDE) (Germany); Koeller, Manfred [Ruhr-University of Bochum, Bergmannsheil University Hospital/Surgical Research (Germany); Epple, Matthias, E-mail: matthias.epple@uni-due.de [University of Duisburg-Essen, Department of Inorganic Chemistry, Center for Nanointegration Duisburg-Essen (CeNIDE) (Germany)

    2012-10-15

    Silver, gold, and silver-gold-alloy nanoparticles were prepared by citrate reduction modified by the addition of tannin during the synthesis, leading to a reduction in particle size by a factor of three. Nanoparticles can be prepared by this easy water-based synthesis and subsequently functionalized by the addition of either tris(3-sulfonatophenyl)phosphine or poly(N-vinylpyrrolidone). The resulting nanoparticles of silver (diameter 15-25 nm), gold (5-6 nm), and silver-gold (50:50; 10-12 nm) were easily dispersable in water and also in cell culture media (RPMI + 10 % fetal calf serum), as shown by nanoparticle tracking analysis and differential centrifugal sedimentation. High-resolution transmission electron microscopy showed a polycrystalline nature of all nanoparticles. EDX on single silver-gold nanoparticles indicated that the concentration of gold is higher inside a nanoparticle. The biologic action of the nanoparticles toward human mesenchymal stem cells (hMSC) was different: Silver nanoparticles showed a significant concentration-dependent influence on the viability of hMSC. Gold nanoparticles showed only a small effect on the viability of hMSC after 7 days. Surprisingly, silver-gold nanoparticles had no significant influence on the viability of hMSC despite the silver content. Silver nanoparticles and silver-gold nanoparticles in the concentration range of 5-20 {mu}g mL{sup -1} induced the activation of hMSC as indicated by the release of IL-8. In contrast, gold nanoparticles led to a reduction of the release of IL-6 and IL-8.

  1. Electron-Positron Production in Ultra-Peripheral Heavy-Ion Collisions with the STAR Experiment

    OpenAIRE

    Morozov, Vladimir Borisovitch

    2004-01-01

    This thesis presents a measurement of the cross-section of the purely electromagnetic production of $e^+e^-$ pairs accompanied by mutual nuclear Coulomb excitation $AuAu\\to Au^*Au^*+e^+e^-$, in ultra-peripheral gold-gold collisions at RHIC at the center-of-mass collision energy of $\\sqrt{s_{NN}} = 200$ GeV per nucleon. These reactions were selected by detecting neutron emission by the excited gold ions in the Zero Degree Calorimeters. The charged tracks in the $e^+e^-$ events were reconstruct...

  2. Application of gold in the field of heterogeneous catalysis

    CERN Document Server

    Luo, Siwei

    2014-01-01

    Gold has been long thought as an inert metal which finds most of its use in jewelry and monetary exchange. However, catalysis by gold has rapidly become a hot topic in chemistry ever since Haruta and Hutchings found gold to be an extraordinary good heterogeneous catalyst in certain reactions. Here in this paper, several model reactions which made gold historically famous as a catalyst and a currently hot topic will be demonstrated, such as oxidation of CO, selective oxidation, and hydrodechlorination. Conclusions on the chemical nature of gold will be made as well as future perspectives of designing gold as a better catalyst.

  3. Lantana camara Linn leaf extract mediated green synthesis of gold nanoparticles and study of its catalytic activity

    Science.gov (United States)

    Dash, Shib Shankar; Bag, Braja Gopal; Hota, Poulami

    2015-03-01

    A facile one-step green synthesis of stable gold nanoparticles (AuNPs) has been described using chloroauric acid (HAuCl4) and the leaf extract of Lantana camara Linn (Verbenaceae family) at room temperature. The leaf extract enriched in various types of plant secondary metabolites is highly efficient for the reduction of chloroaurate ions into metallic gold and stabilizes the synthesized AuNPs without any additional stabilizing or capping agents. Detailed characterizations of the synthesized gold nanoparticles were carried out by surface plasmon resonance spectroscopy, transmission electron microscopy, dynamic light scattering, Zeta potential, X-ray diffraction and Fourier transform-infrared spectroscopy studies. The synthesized AuNPs have been utilized as a catalyst for the sodium borohydride reduction of 4-nitrophenol to 4-aminophenol in water at room temperature under mild reaction condition. The kinetics of the reduction reaction has been studied spectrophotometrically.

  4. Simple fabrication of gold nanobelts and patterns.

    Directory of Open Access Journals (Sweden)

    Renyun Zhang

    Full Text Available Gold nanobelts are of interest in several areas; however, there are only few methods available to produce these belts. We report here on a simple evaporation induced self-assembly (EISA method to produce porous gold nanobelts with dimensions that scale across nanometer (thickness ∼80 nm and micrometer (width ∼20 µm, to decimeter (length ∼0.15 m. The gold nanobelts are well packed on the beaker wall and can be easily made to float on the surface of the solution for depositing onto other substrates. Microscopy showed that gold nanobelts had a different structure on the two sides of the belt; the density of gold nanowires on one side was greater than on the other side. Electrical measurements showed that these nanobelts were sensitive to compressive or tensile forces, indicating a potential use as a strain sensor. The patterned nanobelts were further used as a template to grow ZnO nanowires for potential use in applications such as piezo-electronics.

  5. Engineered Gold Nanoparticles and Plant Adaptation Potential

    Science.gov (United States)

    Siddiqi, Khwaja Salahuddin; Husen, Azamal

    2016-09-01

    Use of metal nanoparticles in biological system has recently been recognised although little is known about their possible effects on plant growth and development. Nanoparticles accumulation, translocation, growth response and stress modulation in plant system is not well understood. Plants exposed to gold and gold nanoparticles have been demonstrated to exhibit both positive and negative effects. Their growth and yield vary from species to species. Cytoxicity of engineered gold nanoparticles depends on the concentration, particle size and shape. They exhibit increase in vegetative growth and yield of fruit/seed at lower concentration and decrease them at higher concentration. Studies have shown that the gold nanoparticles exposure has improved free radical scavenging potential and antioxidant enzymatic activities and alter micro RNAs expression that regulate different morphological, physiological and metabolic processes in plants. These modulations lead to improved plant growth and yields. Prior to the use of gold nanoparticles, it has been suggested that its cost may be calculated to see if it is economically feasible.

  6. Engineered Gold Nanoparticles and Plant Adaptation Potential.

    Science.gov (United States)

    Siddiqi, Khwaja Salahuddin; Husen, Azamal

    2016-12-01

    Use of metal nanoparticles in biological system has recently been recognised although little is known about their possible effects on plant growth and development. Nanoparticles accumulation, translocation, growth response and stress modulation in plant system is not well understood. Plants exposed to gold and gold nanoparticles have been demonstrated to exhibit both positive and negative effects. Their growth and yield vary from species to species. Cytoxicity of engineered gold nanoparticles depends on the concentration, particle size and shape. They exhibit increase in vegetative growth and yield of fruit/seed at lower concentration and decrease them at higher concentration. Studies have shown that the gold nanoparticles exposure has improved free radical scavenging potential and antioxidant enzymatic activities and alter micro RNAs expression that regulate different morphological, physiological and metabolic processes in plants. These modulations lead to improved plant growth and yields. Prior to the use of gold nanoparticles, it has been suggested that its cost may be calculated to see if it is economically feasible. PMID:27637892

  7. Gold Nanoparticle Labels Amplify Ellipsometric Signals

    Science.gov (United States)

    Venkatasubbarao, Srivatsa

    2008-01-01

    The ellipsometric method reported in the immediately preceding article was developed in conjunction with a method of using gold nanoparticles as labels on biomolecules that one seeks to detect. The purpose of the labeling is to exploit the optical properties of the gold nanoparticles in order to amplify the measurable ellipsometric effects and thereby to enable ultrasensitive detection of the labeled biomolecules without need to develop more-complex ellipsometric instrumentation. The colorimetric, polarization, light-scattering, and other optical properties of nanoparticles depend on their sizes and shapes. In the present method, these size-and-shape-dependent properties are used to magnify the polarization of scattered light and the diattenuation and retardance of signals derived from ellipsometry. The size-and-shape-dependent optical properties of the nanoparticles make it possible to interrogate the nanoparticles by use of light of various wavelengths, as appropriate, to optimally detect particles of a specific type at high sensitivity. Hence, by incorporating gold nanoparticles bound to biomolecules as primary or secondary labels, the performance of ellipsometry as a means of detecting the biomolecules can be improved. The use of gold nanoparticles as labels in ellipsometry has been found to afford sensitivity that equals or exceeds the sensitivity achieved by use of fluorescence-based methods. Potential applications for ellipsometric detection of gold nanoparticle-labeled biomolecules include monitoring molecules of interest in biological samples, in-vitro diagnostics, process monitoring, general environmental monitoring, and detection of biohazards.

  8. Authentication of gold products by nuclear methods

    International Nuclear Information System (INIS)

    The falsification of valuable gold items is a threat to the authenticity of gold products. To solve this, there is a continuous search for reliable, practicle and cost-effective means of identifying forgeries. Because nuclear techniques as applied to elemental analysis have a high degree of specificity, are non-destructive and permit the availability of results within a relatively short time, a few of these techniques were investigated and reviewed in the article. Work on some promising methods in the author's laboratory is also discussed. Constraints such as those imposed by the time taken by the measurement, negligible residual activity within a relatively short time were also considered. The techniques that were investigated include: the transmission of electromagnetic radiation through a medium; scattering of electromagnetic radiation; x-ray fluorescence analysis; neutron activation analysis; activation by the inelastic scattering of gamma radiation; activation by the inelastic scattering of fast neutrons; absorption and scattering of fast neutrons; self-attenuation of gamma radiation. The shape of the object being investigated, should also be considered. It is concluded that a system based on the inelastic scattering of neutrons emitted by a 241Am/Be source (halflife = 433 years) is practical and capable of authenticating gold and gold alloy coins such as Krugerrands. The feasibility study on the assaying of gold jewelry by means of nuclear methods also showed it to be impractical

  9. Evolution of ac conductivity in nonequilibrium warm dense gold

    International Nuclear Information System (INIS)

    Using a chirped pulse probe technique, we have obtained single-shot measurements of temporal evolution of ac conductivity at 1.55 eV (800 nm) during electron energy relaxation in nonequilibrium warm dense gold with energy densities up to 4.1 MJ/kg (8*1010 J/m3). The results uncover important changes that have been masked in an earlier experiment. Equally significant, they provide valuable tests of an ab initio model for the calculation of electron heat capacity, electron-ion coupling, and ac conductivity in a single, first principles framework. While measurements of the real part of ac conductivity corroborate our theoretical temperature-dependent electron heat capacity, they point to an electron-ion coupling factor of 2.2*1016 W/m3K, significantly below that predicted by theory. In addition, measurements of the imaginary part of ac conductivity reveal the need to improve theoretical treatment of intraband contributions at very low photon energy. (authors)

  10. Measurement of charge of heavy ions in emulsion using a CCD camera

    CERN Document Server

    Kudzia, D; Dabrowska, A; Deines-Jones, P; Holynski, R; Olszewski, A; Nilsen, B S; Sen-Gupta, K; Szarska, M; Trzupek, A; Waddington, C J; Wefel, J P; Wilczynska, B; Wilczynski, H; Wolter, W; Wosiek, B; Wozniak, K

    1999-01-01

    A system has been developed for semi-automated determination of the charges of heavy ions recorded in nuclear emulsions. The profiles of various heavy ion tracks in emulsion, both accelerator beam ions and fragments of heavy projectiles, were obtained with a CCD camera mounted on a microscope. The dependence of track profiles on illumination, emulsion grain size and density, background in emulsion, and track geometry was analyzed. Charges of the fragments of heavy projectiles were estimated independently by the delta ray counting method. A calibration of both width and height of track profiles against ion charges was made with ions of known charges ranging from helium to gold nuclei. (author)

  11. Gold grade variation and particle microchemistry in exploration pits of the Batouri gold district, SE Cameroon

    Science.gov (United States)

    Vishiti, A.; Suh, C. E.; Lehmann, B.; Egbe, J. A.; Shemang, E. M.

    2015-11-01

    The Batouri area hosts lode-gold mineralization under several-m-thick lateritic cover. Pitting to bed rock on a geochemical Au anomaly defined from previous reconnaissance soil sampling identified five horizons ranging from saprock at the base to laterite at the top. Analysis of bulk samples from each horizon by fire assay shows that most of the horizons are barren although 119 ppb and 48 ppb Au values were obtained from one laterite horizon and one saprolite horizon, respectively, from two separate pits. All the horizons were panned and particulate gold was also recovered only from these two horizons. The gold grains from both horizons are morphologically and compositionally indistinguishable with rare quartz, pyrite and galena inclusions. The grains have irregular, sub-rounded, bean to elongated shapes and they show a remarkable core-rim zonation. Electron microprobe analysis of the grains recorded high gold content in the rims (86.3-100 wt%) and along fissures within the grains (95.1-100 wt%). The cores are relatively Ag rich (11.8-14 wt% Ag) while the rims (0.63-13.7 wt% Ag, most of the values fall within the lower limit of this range) and fissures (0.03-5.02 wt% Ag) are poor in Ag. The low Ag concentration in the rims and along fissures is attributed to preferential leaching of Ag; a process recognized in gold grains and platiniferous alloys from alluvia. The core composition of the grains is similar to that of primary gold composition in the bedrock. These results show that gold in the soil is relic particulate gold derived from the primary source with no evidence of secondary gold precipitation in the weathering cycle. In all the pits no horizon was systematically enriched in gold suggesting there has been no chemical remobilization of gold in this environment. Rather the dispersion of gold here is in the particulate form. Therefore combining particulate gold features with assay data is relevant to exploration in such tropical environments.

  12. Investigation of biophysical mechanisms in gold nanoparticle mediated laser manipulation of cells using a multimodal holographic and fluorescence imaging setup.

    Directory of Open Access Journals (Sweden)

    Stefan Kalies

    Full Text Available Laser based cell manipulation has proven to be a versatile tool in biomedical applications. In this context, combining weakly focused laser pulses and nanostructures, e.g. gold nanoparticles, promises to be useful for high throughput cell manipulation, such as transfection and photothermal therapy. Interactions between laser pulses and gold nanoparticles are well understood. However, it is still necessary to study cell behavior in gold nanoparticle mediated laser manipulation. While parameters like cell viability or perforation efficiency are commonly addressed, the influence of the manipulation process on other essential cell parameters is not sufficiently investigated yet. Thus, we set out to study four relevant cell properties: cell volume and area, ion exchange and cytoskeleton structure after gold nanoparticle based laser manipulation. For this, we designed a multimodal imaging and manipulation setup. 200 nm gold nanoparticles were attached unspecifically to canine cells and irradiated by weakly focused 850 ps laser pulses. Volume and area change in the first minute post laser manipulation was monitored using digital holography. Calcium imaging and cells expressing a marker for filamentous actin (F-actin served to analyze the ion exchange and the cytoskeleton, respectively. High radiant exposures led to cells exhibiting a tendency to shrink in volume and area, possibly due to outflow of cytoplasm. An intracellular raise in calcium was observed and accompanied by an intercellular calcium wave. This multimodal approach enabled for the first time a comprehensive analysis of the cell behavior in gold nanoparticle mediated cell manipulation. Additionally, this work can pave the way for a better understanding and the evaluation of new applications in the context of cell transfection or photothermal therapy.

  13. Selectable Ultrasensitive Detection of Hg2+ with Rhodamine 6G-Modified Nanoporous Gold Optical Sensor

    Science.gov (United States)

    Wang, Zheng; Yang, Min; Chen, Chao; Zhang, Ling; Zeng, Heping

    2016-01-01

    An extremely sensitive fluorescence sensor has been developed for selectively detection of mercury ions based on metallophilic Hg2+-Au+ interactions, which results in an effective release of pre-adsorbed rhodamine 6G (R6G) molecules from the nanoporous gold substrate, associated with a significant decrease of fluorescence intensity. The optical sensor has a detection sensitivity down to 0.6 pM for Hg2+ and CH3Hg+ ions, in particular a superior selectivity in a complex aqueous system containing 13 different types of metal ions, meanwhile maintaining a long-term stability after 10 cycles. Such a fluorescence sensor combining multiple advantages therefore present promising potentials in various applications. PMID:27403721

  14. Selectable Ultrasensitive Detection of Hg2+ with Rhodamine 6G-Modified Nanoporous Gold Optical Sensor

    Science.gov (United States)

    Wang, Zheng; Yang, Min; Chen, Chao; Zhang, Ling; Zeng, Heping

    2016-07-01

    An extremely sensitive fluorescence sensor has been developed for selectively detection of mercury ions based on metallophilic Hg2+-Au+ interactions, which results in an effective release of pre-adsorbed rhodamine 6G (R6G) molecules from the nanoporous gold substrate, associated with a significant decrease of fluorescence intensity. The optical sensor has a detection sensitivity down to 0.6 pM for Hg2+ and CH3Hg+ ions, in particular a superior selectivity in a complex aqueous system containing 13 different types of metal ions, meanwhile maintaining a long-term stability after 10 cycles. Such a fluorescence sensor combining multiple advantages therefore present promising potentials in various applications.

  15. Potassium permanganate-glutaraldehyde chemiluminescence system catalyzed by gold nanoprisms toward selective determination of fluoride.

    Science.gov (United States)

    Abolhasani, Jafar; Hassanzadeh, Javad; Ghorbani-Kalhor, Ebrahim

    2016-02-01

    Gold and silver nanoparticles (NPs) are shown to exert a positive effect on the chemiluminescence (CL) reaction of permanganate aldehydes. Interestingly, between various shapes examined, Au nanoprisms have the highest beneficial effect. This effect is even more notable in the presence of sodium dodecyl sulfate (SDS) surfactant. UV-vis spectra and transmission electron microscopy were used to characterize the NP shapes and sizes. Furthermore, it was observed that iron(III) ions can slightly increase CL emission of this system. This intensification is very effective in the presence of fluoride ions (F(-)). These observations form the basis of the method for the high sensitive determination of F(-) in the 6-1200 nmol L(-1) concentration range, with a detection limit of 2.1 nmol L(-1). The proposed method has good precision and was satisfactorily used in the selective determination of low concentrations of fluoride ion in real samples. PMID:26110514

  16. Gold Nanoparticle-Graphene Oxide Nanocomposites That Enhance the Device Performance of Polymer Solar Cells

    Directory of Open Access Journals (Sweden)

    Ming-Kai Chuang

    2014-01-01

    Full Text Available Metal nanoparticle-decorated graphene oxides are promising materials for use in various optoelectronic applications because of their unique plasmonic properties. In this paper, a simple, environmentally friendly method for the synthesis of gold nanoparticle-decorated graphene oxide that can be used to improve the efficiency of organic photovoltaic devices (OPVs is reported. Here, the amino acid glycine is employed as an environmentally friendly reducing reagent for the reduction of gold ions in the graphene oxide solutions. Transmission electron microscopy, atomic force microscopy, X-ray photoelectron spectroscopy, UV-Vis spectroscopy, and Raman spectroscopy are used to characterize the material properties of the resulting nanomaterials. Furthermore, these nanocomposites are employed as the anode buffer layer in OPVs to trigger surface plasmonic resonance, which improved the efficiency of the OPVs. The results indicate that such nanomaterials appear to have great potential for application in OPVs.

  17. Preparation of Nanoelectrode Ensembles by Assembly of Nano- Silver Colloid on Gold Surface

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    A novel method for preparing silver nanoelectrode ensembles (SNEEs) and gold nanoelectrode ensembles (GNEEs) has been developed. Silver colloid particles were first absorbed to the gold electrode surface to form a monolayer silver colloid. N-hexadecyl mercaptan was then assembled on the electrode to form a thiol monolayer on which hydrophilic ions cannot be transfered. The SNEEs was prepared by removing thiol from silver colloid surface through applying an AC voltage with increasing frequency at 0.20 V (vs. SCE). Finally, GNEEs was obtained by immersing a SNEEs into 6 mol/L HNO3 to remove the silver colloid particles. By comparison with other methods such as template method etc., this method enjoys some advantages of lower resistance, same diameter, easy preparation, controllable size and density.

  18. Preparation of Nanoelectrode Ensembles by Assembly of Nano—Silver Colloid on Gold Surface

    Institute of Scientific and Technical Information of China (English)

    GangXIA; XiaoYaHU; 等

    2002-01-01

    A novel method for preparing silver nanoelectrode ensembles(SNEEs) and gold nanoelectrode ensembles (GNEEs) has been developed. Silver colloid particles were first absorbed to the gold electrode surface to form a monolayer silver colloid. N-hexadecyl nercaptan was then assembled on the electrode to form a thoil monolayer on which hydrophilic ions cannot be transfered. The SNEEs was prepared by removing thiol from silver colloid surface through applying and AC voltage with increasing frequency at 0.20V(vs.SCE). Finally,GNEEs was obtained by immersing a SNEEs into 6 mol/L HNO3 to remove the silver colloid particles. By comparison with other methods such as template method ect., this method enjoys some advantages of lower resistance, same diameter,easy preparation,controllable size and density.

  19. Surface analysis of gold nanoparticles functionalized with thiol-modified glucose SAMs for biosensor applications.

    Directory of Open Access Journals (Sweden)

    Valentina eSpampinato

    2016-02-01

    Full Text Available In this work, Time of Flight Secondary Ion Mass Spectrometry (ToF-SIMS, Principal Component Analysis (PCA and X-ray Photoelectron Spectroscopy (XPS have been used to characterize the surface chemistry of gold substrates before and after functionalization with thiol-modified glucose self-assembled monolayers and subsequent biochemical specific recognition of maltose binding protein (MBP.The results indicate that the surface functionalization is achieved both on flat and nanoparticles gold substrates thus showing the potential of the developed system as biodetection platform. Moreover, the method presented here has been found to be a sound and valid approach to characterize the surface chemistry of nanoparticles functionalized with large molecules.Both techniques were proved to be very useful tools for monitoring all the functionalization steps, including the investigation of the biological behaviour of the glucose-modified particles in presence of the maltose binding protein.

  20. Gold nanoparticle translocation dynamics and electrical detection of single particle diffusion using solid-state nanopores.

    Science.gov (United States)

    Goyal, Gaurav; Freedman, Kevin J; Kim, Min Jun

    2013-09-01

    This paper describes the use of gold nanoparticles to study particle translocation dynamics through silicon nitride solid-state nanopores. Gold nanoparticles were dispersed in 20 mM KCl solution containing nonionic surfactant Triton X-100 and their translocation was studied at different applied voltages. The use of low electrolyte concentration resulted in current enhancement upon particle translocation. The counterion cloud around the nanoparticles is proposed to be the reason for current enhancement phenomena because associated counterion cloud is believed to increase the ion density inside the pore during particle translocation. Further, single particle diffusion events were also recorded at 0 mV voltage bias and 0 pA background ionic current with high signal-to-noise ratio as the particles moved down their concentration gradient. The ability of nanopore sensors to detect single particle diffusion can be extended to field-free analysis of biomolecules in their native state and at or near physiological salt concentrations.

  1. In Situ 3D Imaging of Catalysis Induced Strain in Gold Nanoparticles.

    Energy Technology Data Exchange (ETDEWEB)

    Ulvestad, Andrew; Sasikumar, Kiran; Kim, Jong Woo; Harder, Ross; Maxey, Evan; Clark, Jesse N.; Narayanan, Badri; Deshmukh, Sanket; Ferrier, Nicola; Mulvaney, Paul; Sankaranarayanan, Subramanian K.R.S.; Shpyrko, Oleg G.

    2016-08-04

    Multielectron transfer processes are crucially important in energy and biological science but require favorable catalysts to achieve fast kinetics. Nanostructuring catalysts can dramatically improve their properties, which can be difficult to understand due to strain- and size-dependent thermodynamics, the influence of defects, and substrate-dependent activities. Here, we report three-dimensional (3D) imaging of single gold nanoparticles during catalysis of ascorbic acid decomposition using Bragg coherent diffractive imaging (BCDI). Local strains were measured in single nanoparticles and modeled using reactive molecular dynamics (RMD) simulations and finite element analysis (FEA) simulations. RMD reveals the pathway for local strain generation in the gold lattice: chemisorption of hydroxyl ions. FEA reveals that the RMD results are transferable to the nanocrystal sizes studied in the experiment. Our study probes the strain-activity connection and opens a powerful avenue for theoretical and experimental studies of nanocrystal catalysis.

  2. Roasting of refractory gold and silver concentrate

    International Nuclear Information System (INIS)

    In processing of precious metal ores with high pyrite content, refractory concentrates are obtained, which are difficult to process. A refractory gold and silver concentrate was leached with sodium cyanide. Results show low extraction percentages, being 34 % of gold and 40 % of silver. A roasting method to oxidize the concentrate was used, making it more susceptible to cyanidation, hence a more efficient way to extract precious metals. The variables include roasting temperature and roasting and cyanidation time. In addition, the hot calcine was added to the leaching solution at room temperature to analyze the effect on particle size and recovery. The best results, although not entirely satisfactory (50 % of gold and 61 % of silver) were obtained by roasting the concentrate for 4 h at 600 degree centigrade, followed by cyanidation for 20 h. The lime consumption to raise the pH to about 11.3 was increased markedly to 25 kg/m3. (Author) 11 refs.

  3. Hybrid gold single crystals incorporating amino acids

    CERN Document Server

    Chen, Linfeng; Weber, Eva; Fitch, Andy N; Pokroy, Boaz

    2016-01-01

    Composite hybrid gold crystals are of profound interest in various research areas ranging from materials science to biology. Their importance is due to their unique properties and potential implementation, for example in sensing or in bio-nanomedicine. Here we report on the formation of hybrid organic-metal composites via the incorporation of selected amino acids histidine, aspartic acid, serine, glutamine, alanine, cysteine, and selenocystine into the crystal lattice of single crystals of gold. We used electron microscopy, chemical analysis and high-resolution synchrotron powder X ray diffraction to examine these composites. Crystal shape, as well as atomic concentrations of occluded amino acids and their impact on the crystal structure of gold, were determined. Concentration of the incorporated amino acid was highest for cysteine, followed by serine and aspartic acid. Our results indicate that the incorporation process probably occurs through a complex interaction of their individual functional groups with ...

  4. Preparation of radioactive colloidal gold 198Au

    International Nuclear Information System (INIS)

    The preparation with simple equipment of radioactive colloidal gold of particle size about approximately 300 A from seed colloid stabilized by gelatine is described. Some physico-chemical parameters which can affect the process of formation of these colloidal particles are analysed; particle size has been meassured with an electron microscope. The colloid stability has been studied as a function of dilution, age and pH. Nucleation and growth of radioactive colloidal gold have been studied using spectrophotometry. Absorption spectra of the two ones are presented and compared. Quality control of the production process is verified through measurement of parameters, such as radioactive and radiochemical purity and biological distribution in laboratorial animals. This distribution was evalusted for rats injected endovenously with the gold colloidal solution.(Author)

  5. Reversible multi polyelectrolyte layers on gold nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Djoumessi Lekeufack, Diane; Brioude, Arnaud, E-mail: arnaud.brioude@univ-lyon1.fr [UMR CNRS 5615, Universite Claude Bernard Lyon 1, Laboratoire des Multimateriaux et Interfaces (LMI) (France); Lalatonne, Yoann; Motte, Laurence [UMR 7244 CNRS, Universite Paris 13, Laboratoire CSPBAT (France); Coleman, Anthony W.; Miele, Philippe [UMR CNRS 5615, Universite Claude Bernard Lyon 1, Laboratoire des Multimateriaux et Interfaces (LMI) (France)

    2012-06-15

    Gold nanoparticles surface can be easily modified by different molecules such as polyelectrolytes. In a typical multilayer system made of polyethyleneimine and poly(styrene sulfonate)sodium alternated layers around gold nanoparticles, we have evaluated the interactions between the different layers and the relative strength of interfacial properties. By means of UV-Visible and FTIR spectroscopies, we have shown that due to its amine functionalities, the bonding of polyethyleneimine to gold particles is stronger than the one implied with the sulfonate anion in the PSS inducing a clean removal of this latter after the last polyethyleneimine deposition. Considering that polyethyleneimine is cytotoxic and that only weak covalent bonds are concerned in polyelectrolyte multilayer, this last point is of main importance since external degradation thus exposing polyethyleneimine sub-layer of multilayer films to in vivo tissue cells can occur by many ways.

  6. Gold nanocrystals with DNA-directed morphologies.

    Science.gov (United States)

    Ma, Xingyi; Huh, June; Park, Wounjhang; Lee, Luke P; Kwon, Young Jik; Sim, Sang Jun

    2016-01-01

    Precise control over the structure of metal nanomaterials is important for developing advanced nanobiotechnology. Assembly methods of nanoparticles into structured blocks have been widely demonstrated recently. However, synthesis of nanocrystals with controlled, three-dimensional structures remains challenging. Here we show a directed crystallization of gold by a single DNA molecular regulator in a sequence-independent manner and its applications in three-dimensional topological controls of crystalline nanostructures. We anchor DNA onto gold nanoseed with various alignments to form gold nanocrystals with defined topologies. Some topologies are asymmetric including pushpin-, star- and biconcave disk-like structures, as well as more complex jellyfish- and flower-like structures. The approach of employing DNA enables the solution-based synthesis of nanocrystals with controlled, three-dimensional structures in a desired direction, and expands the current tools available for designing and synthesizing feature-rich nanomaterials for future translational biotechnology. PMID:27633935

  7. Gold nanocrystals with DNA-directed morphologies

    Science.gov (United States)

    Ma, Xingyi; Huh, June; Park, Wounjhang; Lee, Luke P.; Kwon, Young Jik; Sim, Sang Jun

    2016-09-01

    Precise control over the structure of metal nanomaterials is important for developing advanced nanobiotechnology. Assembly methods of nanoparticles into structured blocks have been widely demonstrated recently. However, synthesis of nanocrystals with controlled, three-dimensional structures remains challenging. Here we show a directed crystallization of gold by a single DNA molecular regulator in a sequence-independent manner and its applications in three-dimensional topological controls of crystalline nanostructures. We anchor DNA onto gold nanoseed with various alignments to form gold nanocrystals with defined topologies. Some topologies are asymmetric including pushpin-, star- and biconcave disk-like structures, as well as more complex jellyfish- and flower-like structures. The approach of employing DNA enables the solution-based synthesis of nanocrystals with controlled, three-dimensional structures in a desired direction, and expands the current tools available for designing and synthesizing feature-rich nanomaterials for future translational biotechnology.

  8. Recovery of gold from gold slag by wood shaving fly ash.

    Science.gov (United States)

    Aworn, Amphol; Thiravetyan, Paitip; Nakbanpote, Woranan

    2005-07-15

    Wood shaving fly ash was used as an alternative adsorbent for gold preconcentration from gold slag. The maximum gold adsorption capacity of wood shaving fly ash washed with tap water (WSFW) at 20, 30, 40, and 60 degrees C was 8.68, 7.79, 7.44, and 7.25 mg(Au)/g(adsorbent), respectively, while of activated carbon it was 76.78, 60.95, 56.13, and 51.90 mg(Au)/g(adsorbent), respectively. Deionized water at 100 degrees C could elute gold adsorbed onto WSFW to 71%. The effect of the increasing temperature of water, 30, 60, and 100 degrees C, implied that the adsorption mechanism was mainly physical adsorption. The negative values of enthalpy change (DeltaH) and free energy change (DeltaG) indicated an exothermic and spontaneous process, respectively. The positive values of entropy change (DeltaS) indicated increasing disorder of the system. The advantages of wood shaving fly ash are the purification of gold and the easier recycling of gold from the gold-adsorbed adsorbent. PMID:15925603

  9. Direct formation of gold nanorods on surfaces using polymer-immobilised gold seeds.

    Science.gov (United States)

    Abyaneh, Majid K; Parisse, Pietro; Casalis, Loredana

    2016-01-01

    Herein, we present the formation of gold nanorods (GNRs) on novel gold-poly(methyl methacrylate) (Au-PMMA) nanocomposite substrates with unprecedented growth control through the polymer molecular weight (M w) and gold-salt-to-polymer weight ratio. For the first time, GNRs have been produced by seed-mediated direct growth on surfaces that were pre-coated with polymer-immobilised gold seeds. A Au-PMMA nanocomposite formed by UV photoreduction has been used as the gold seed. The influence of polymer M w and gold concentration on the formation of GNRs has been investigated and discussed. The polymer nanocomposite formed with a lower M w PMMA and 20 wt % gold salt provides a suitable medium for growing well-dispersed GNRs. In this sample, the average dimension of produced GNRs is 200 nm in length with aspect ratios up to 10 and a distribution of GNRs to nanoparticles of nearly 22%. Suitable characterization techniques such as AFM and SEM have been used to support concept of the proposed growth method. PMID:27547597

  10. Major Brazilian gold deposits - 1982 to 1999

    Science.gov (United States)

    Thorman, Charles H.; DeWitt, Ed; Maron, Marcos A.; Ladeira, Eduardo A.

    2001-07-01

    Brazil has been a major but intermittent producer of gold since its discovery in 1500. Brazil led the world in gold production during the 18th and early 19th centuries. From the late 19th century to the late 20th century, total mining company and garimpeiro production was small and relatively constant at about 5 to 8 t/year. The discovery of alluvial deposits in the Amazon by garimpeiros in the 1970s and the opening of eight mines by mining companies from 1983 to 1990 fueled a major boom in Brazil's gold production, exceeding 100 t/year in 1988 and 1989. However, garimpeiro alluvial production decreased rapidly in the 1990s, to about 10 t/year by 1999. Company production increased about tenfold from about 4 t/year in 1982 to 40 t in 1992. Production from 1992 to the present remained relatively stable, even though several mines were closed or were in the process of closing and no new major mines were put into production during that period. Based on their production history from 1982-1999, 17 gold mines are ranked as major (>20 t) and minor (3-8 t) mines. From 1982-1999, deposits hosted in Archean rocks produced 66% of the gold in Brazil, whereas deposits in Paleoproterozoic and Neoproterozoic rocks accounted for 19% and 15%, respectively. Deposits in metamorphosed sedimentary rocks, especially carbonate-rich rocks and carbonate iron-formation, yielded the great bulk of the gold. Deposits in igneous rocks were of much less importance. The Archean and Paleoproterozoic terranes of Brazil largely lack base-metal-rich volcanogenic massive sulfide deposits, porphyry deposits, and polymetallic veins and sedimentary exhalative deposits. An exception to this is in the Carajás Mineral Province.

  11. Facet Control of Gold Nanorods.

    Science.gov (United States)

    Zhang, Qingfeng; Han, Lili; Jing, Hao; Blom, Douglas A; Lin, Ye; Xin, Huolin L; Wang, Hui

    2016-02-23

    While great success has been achieved in fine-tuning the aspect ratios and thereby the plasmon resonances of cylindrical Au nanorods, facet control with atomic level precision on the highly curved nanorod surfaces has long been a significantly more challenging task. The intrinsic structural complexity and lack of precise facet control of the nanorod surfaces remain the major obstacles for the atomic-level elucidation of the structure-property relationships that underpin the intriguing catalytic performance of Au nanorods. Here we demonstrate that the facets of single-crystalline Au nanorods can be precisely tailored using cuprous ions and cetyltrimethylammonium bromide as a unique pair of surface capping competitors to guide the particle geometry evolution during nanorod overgrowth. By deliberately maneuvering the competition between cuprous ions and cetyltrimethylammonium bromide, we have been able to create, in a highly controllable and selective manner, an entire family of nanorod-derived anisotropic multifaceted geometries whose surfaces are enclosed by specific types of well-defined high-index and low-index facets. This facet-controlled nanorod overgrowth approach also allows us to fine-tune the particle aspect ratios while well-preserving all the characteristic facets and geometric features of the faceted Au nanorods. Taking full advantage of the combined structural and plasmonic tunability, we have further studied the facet-dependent heterogeneous catalysis on well-faceted Au nanorods using surface-enhanced Raman spectroscopy as an ultrasensitive spectroscopic tool with unique time-resolving and molecular finger-printing capabilities. PMID:26795706

  12. X-ray computed tomography contrast agents prepared by seeded growth of gold nanoparticles in PEGylated dendrimer

    Energy Technology Data Exchange (ETDEWEB)

    Kojima, Chie [Nanoscience and Nanotechnology Research Center, Research Organization for the 21st Century, Osaka Prefecture University, 1-2 Gakuen-cho, Naka-ku, Sakai, Osaka 599-8570 (Japan); Umeda, Yasuhito; Harada, Atsushi; Kono, Kenji [Department of Applied Chemistry, Graduate School of Engineering, Osaka Prefecture University, 1-1 Gakuen-cho, Naka-ku, Sakai, Osaka 599-8531 (Japan); Ogawa, Mikako; Magata, Yasuhiro, E-mail: c-kojima@21c.osakafu-u.ac.jp [Photon Medical Research Center, Hamamatsu University School of Medicine, 1-20-1 Handayama, Higashi-ku, Hamamatsu, Shizuoka 431-3192 (Japan)

    2010-06-18

    Gold nanoparticles (Au NPs) are a potential x-ray computed tomography (CT) contrast agent. A biocompatible and bioinactive surface is necessary for application of gold nanoparticle to CT imaging. Polyethylene glycol (PEG)-attached dendrimers have been used as a drug carrier with long blood circulation. In this study, the Au NPs were grown in the PEGylated dendrimer to produce a CT contrast agent. The Au NPs were grown by adding gold ions and ascorbic acid at various equivalents to the Au NP-encapsulated dendrimer solution. Both size and surface plasmon absorption of the grown Au NPs increased with adding a large number of gold ions. The x-ray attenuation of the Au NPs also increased after the seeded growth. The Au NPs grown in the PEG-attached dendrimer at the maximum under our conditions exhibited a similar CT value to a commercial iodine agent, iopamidol, in vitro. The Au NP-loaded PEGylated dendrimer and iopamidol were injected into mice and CT images were obtained at different times. The Au NP-loaded PEGylated dendrimer achieved a blood pool imaging, which was greater than a commercial iodine agent. Even though iopamidol was excreted rapidly, the PEGylated dendrimer loading the grown Au NP was accumulated in the liver.

  13. X-ray computed tomography contrast agents prepared by seeded growth of gold nanoparticles in PEGylated dendrimer

    Science.gov (United States)

    Kojima, Chie; Umeda, Yasuhito; Ogawa, Mikako; Harada, Atsushi; Magata, Yasuhiro; Kono, Kenji

    2010-06-01

    Gold nanoparticles (Au NPs) are a potential x-ray computed tomography (CT) contrast agent. A biocompatible and bioinactive surface is necessary for application of gold nanoparticle to CT imaging. Polyethylene glycol (PEG)-attached dendrimers have been used as a drug carrier with long blood circulation. In this study, the Au NPs were grown in the PEGylated dendrimer to produce a CT contrast agent. The Au NPs were grown by adding gold ions and ascorbic acid at various equivalents to the Au NP-encapsulated dendrimer solution. Both size and surface plasmon absorption of the grown Au NPs increased with adding a large number of gold ions. The x-ray attenuation of the Au NPs also increased after the seeded growth. The Au NPs grown in the PEG-attached dendrimer at the maximum under our conditions exhibited a similar CT value to a commercial iodine agent, iopamidol, in vitro. The Au NP-loaded PEGylated dendrimer and iopamidol were injected into mice and CT images were obtained at different times. The Au NP-loaded PEGylated dendrimer achieved a blood pool imaging, which was greater than a commercial iodine agent. Even though iopamidol was excreted rapidly, the PEGylated dendrimer loading the grown Au NP was accumulated in the liver.

  14. Laser induced ablation studies from gold target

    International Nuclear Information System (INIS)

    Laser produced gold plasmas show an enhanced mass ablation rate and ablation pressure as compared to theoretical prediction. This is attributed to radiation effect. Experimental results indicate an increase in the C-J point density and an agreement with self-regulating ablation scaling. Using 1.06 μm laser radiation on 12.5 μm thick planar gold targets, at an absorbed laser intensity IA ≤ 2 x 1013 W/cm2, the experimental results are presented. (Author)

  15. Nanoporous Gold: Fabrication, Characterization, and Applications

    Directory of Open Access Journals (Sweden)

    Michael L. Reed

    2009-12-01

    Full Text Available Nanoporous gold (np-Au has intriguing material properties that offer potential benefits for many applications due to its high specific surface area, well-characterized thiol-gold surface chemistry, high electrical conductivity, and reduced stiffness. The research on np-Au has taken place on various fronts, including advanced microfabrication and characterization techniques to probe unusual nanoscale properties and applications spanning from fuel cells to electrochemical sensors. Here, we provide a review of the recent advances in np-Au research, with special emphasis on microfabrication and characterization techniques. We conclude the paper with a brief outline of challenges to overcome in the study of nanoporous metals.

  16. Gold Rushes and mineral property rights allocation

    DEFF Research Database (Denmark)

    Sinding, Knud

    Even today, mineral property rights are allocated on what is essentially a first-come, first-serve or open access basis. Access to prospect and locate claims may be restricted in some areas such as national parks, but elsewhere a policy of open access is widely practised, albeit subject to a set...... influxes of prospectors competing for a very limited area. This paper charts significant gold rush events in the mineral industry in recent decades and uses preliminary data on the areas impacted by these gold rushes to argue that many mineral tenure systems should be modified in order to be better able...

  17. Gold nanowires and the effect of impurities

    Directory of Open Access Journals (Sweden)

    Novaes Frederico

    2006-01-01

    Full Text Available AbstractMetal nanowires and in particular gold nanowires have received a great deal of attention in the past few years. Experiments on gold nanowires have prompted theory and simulation to help answer questions posed by these studies. Here we present results of computer simulations for the formation, evolution and breaking of very thin Au nanowires. We also discuss the influence of contaminants, such as atoms and small molecules, and their effect on the structural and mechanical properties of these nanowires.

  18. Crack injection in silver gold alloys

    Science.gov (United States)

    Chen, Xiying

    Stress corrosion cracking (SCC) is a materials degradation phenomena resulting from a combination of stress and a corrosive environment. Among the alphabet soup of proposed mechanism of SCC the most important are film-rupture, film-induced cleavage and hydrogen embrittlement. This work examines various aspects of film-induced cleavage in gold alloys for which the operation of hydrogen embrittlement processes can be strictly ruled out on thermodynamic grounds. This is so because in such alloys SCC occurs under electrochemical conditions within which water is stable to hydrogen gas evolution. The alloy system examined in this work is AgAu since the corrosion processes in this system occur by a dealloying mechanism that results in the formation of nanoporous gold. The physics behind the dealloying process as well as the resulting formation of nanoporous gold is today well understood. Two important aspects of the film-induced cleavage mechanism are examined in this work: dynamic fracture in monolithic nanoporous gold and crack injection. In crack injection there is a finite thickness dealloyed layer formed on a AgAu alloy sample and the question of whether or not a crack that nucleates within this layer can travel for some finite distance into the un-corroded parent phase alloy is addressed. Dynamic fracture tests were performed on single edge-notched monolithic nanoporous gold samples as well as "infinite strip" sample configurations for which the stress intensity remains constant over a significant portion of the crack length. High-speed photography was used to measure the crack velocity. In the dynamic fracture experiments cracks were observed to travel at speeds as large as 270 m/s corresponding to about 68% of the Raleigh wave velocity. Crack injection experiments were performed on single crystal Ag77Au23, polycrystalline Ag72Au28 and pure gold, all of which had thin nanoporous gold layers on the surface of samples. Through-thickness fracture was seen in both the

  19. Gold and Silver Inlaid Bronze Sheep

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Gold and silver inlaying is a metal processing technique popular during the Spring and Autumn Period (770-476 B. C.) and the Warring States Period (475-221 B. C.). Patterns on the surface of the bronze figure are chiselled out and gold and silver threads (which can be as thin as hair) are inlaid. Finally the whole figure is filed and polished resulting in a splendid artistic work highlighting the different colours of the three different kinds of metal. The artifact shown here was unearthed from Ningxia'...

  20. Radiation Heat Waves in Gold Plasma

    Institute of Scientific and Technical Information of China (English)

    YANG Jia-Min; XU Yan; DING Yao-Nan; LAI Dong-Xian; DING Yong-Kun; JIANG Shao-En; ZHENG Zhi-Jian; MIAO Wen-Yong

    2003-01-01

    Eight beams 0.35/um laser with pulse duration of about 1.0ns and energy of 260 J per beam was injected into a cylindrical cavity to generate intense x-ray radiation on the "Shengguang I" high power laser facility. Gold foils with a thickness in the range of 0.09-0.52/j,m were attached on the diagnostic hole of the cavity and ablated by the intense x-ray radiation. The propagating radiation heat wave in the high-Z gold plasma was observed clearly. For comparison, we also simulated the experimental results.