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Sample records for cuprous oxide precipitate

  1. Magnetoexcitons in cuprous oxide

    Science.gov (United States)

    Schweiner, Frank; Main, Jörg; Wunner, Günter; Freitag, Marcel; Heckötter, Julian; Uihlein, Christoph; Aßmann, Marc; Fröhlich, Dietmar; Bayer, Manfred

    2017-01-01

    Two of the most striking experimental findings when investigating exciton spectra in cuprous oxide using high-resolution spectroscopy are the observability and the fine structure splitting of F excitons reported by J. Thewes et al. [Phys. Rev. Lett. 115, 027402 (2015), 10.1103/PhysRevLett.115.027402]. These findings show that it is indispensable to account for the complex valence band structure and the cubic symmetry of the solid in the theory of excitons. This is all the more important for magnetoexcitons, where the external magnetic field reduces the symmetry of the system even further. We present the theory of excitons in Cu2O in an external magnetic field and especially discuss the dependence of the spectra on the direction of the external magnetic field, which cannot be understood from a simple hydrogenlike model. Using high-resolution spectroscopy, we also present the corresponding experimental spectra for cuprous oxide in Faraday configuration. The theoretical results and experimental spectra are in excellent agreement as regards not only the energies but also the relative oscillator strengths. Furthermore, this comparison allows for the determination of the fourth Luttinger parameter κ of this semiconductor.

  2. Radiation annealing in cuprous oxide

    DEFF Research Database (Denmark)

    Vajda, P.

    1966-01-01

    Experimental results from high-intensity gamma-irradiation of cuprous oxide are used to investigate the annealing of defects with increasing radiation dose. The results are analysed on the basis of the Balarin and Hauser (1965) statistical model of radiation annealing, giving a square-root relati......-root relationship between the rate of change of resistivity and the resistivity change. The saturation defect density at room temperature is estimated on the basis of a model for defect creation in cuprous oxide....

  3. Resistance switching of electrodeposited cuprous oxide

    Science.gov (United States)

    Yazdanparast, Sanaz

    In this work, the resistance switching behavior of electrodeposited cuprous oxide (Cu2O) thin films in Au/Cu2O/top electrode (Pt, Au-Pd, Al) cells was studied. After an initial FORMING process, the fabricated cells show reversible switching between a low resistance state (16.6 O) and a high resistance state (0.4 x 106 O). Changing the resistance states in cuprous oxide films depends on the magnitude of the applied voltage which corresponds to unipolar resistance switching behavior of this material. The endurance and retention tests indicate a potential application of the fabricated cells for nonvolatile resistance switching random access memory (RRAM). The results suggest formation and rupture of one or several nanoscale copper filaments as the resistance switching mechanism in the cuprous oxide films. At high electric voltage in the as-deposited state of Au/Cu 2O/Au-Pd cell structure, the conduction behavior follows Poole-Frenkel emission. Various parameters, such as the compliance current, the cuprous oxide microstructure, the cuprous oxide thickness, top electrode area, and top electrode material, affect the resistance switching characteristics. The required FORMING voltage is higher for Au/Cu2O/Al cell compared with the Au/Cu2O/Pt which is related to the Schottky behavior of Al contact with Cu2O. Cu2O nanowires in Au-Pt/ Cu 2O/Au-Pt cell also show resistance switching behavior, indicating scalable potential of this cell for usage as RRAM. After an initial FORMING process under an electric field of 3 x 106 V/m, the Cu2O nanowire is switched to the LRS. During the FORMING process physical damages are observed in the cell, which may be caused by Joule heating and gas evolution.

  4. Evaluation of defects in cuprous oxide through exciton luminescence imaging

    Energy Technology Data Exchange (ETDEWEB)

    Frazer, Laszlo, E-mail: jl@laszlofrazer.com [Department of Physics, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208 (United States); Lenferink, Erik J. [Department of Physics, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208 (United States); Chang, Kelvin B. [Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208 (United States); Poeppelmeier, Kenneth R. [Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208 (United States); Chemical Sciences and Engineering Division, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439 (United States); Stern, Nathaniel P. [Department of Physics, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208 (United States); Ketterson, John B. [Department of Physics, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208 (United States); Department of Electrical Engineering and Computer Science, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208 (United States)

    2015-03-15

    The various decay mechanisms of excitons in cuprous oxide (Cu{sub 2}O) are highly sensitive to defects which can relax selection rules. Here we report cryogenic hyperspectral imaging of exciton luminescence from cuprous oxide crystals grown via the floating zone method showing that the samples have few defects. Some locations, however, show strain splitting of the 1s orthoexciton triplet polariton luminescence. Strain is reduced by annealing. In addition, annealing causes annihilation of oxygen and copper vacancies, which leads to a negative correlation between luminescence of unlike vacancies. - Highlights: • We use luminescence to observe defects in high quality cuprous oxide crystals. • Strain is reduced by annealing. • Annealing causes annihilation of oxygen and copper vacancies.

  5. Potentiostatic Deposition and Characterization of Cuprous Oxide Thin Films

    OpenAIRE

    2013-01-01

    Electrodeposition technique was employed to deposit cuprous oxide Cu2O thin films. In this work, Cu2O thin films have been grown on fluorine doped tin oxide (FTO) transparent conducting glass as a substrate by potentiostatic deposition of cupric acetate. The effect of deposition time on the morphologies, crystalline, and optical quality of Cu2O thin films was investigated.

  6. The Absorption of Benzotriazole on Copper and Cuprous Oxide

    Science.gov (United States)

    1988-07-01

    Cornell University, Ithaca INY, 14853 Copper surfaces are commonly treated with benzotriazole ( BTA ), 1. to inhibit cor- rosion. H1+ is thought to be...00 00 SIOFFICE OF NAVAL RESEARCH Contract N00014-82-K-0576 Technical Report No. 38 THE ADSORPTION OF BENZOTRIAZOLE ON COPPER AND CUPROUS OXIDE by M... Benzotriazole on Copper and Cuprous Oxide 12 7- `SONAL AUTHOR(S) M. C. Zonnevylle and R. Hoffmann 13a TYPE OF REPORT 13b TIME COVERED 14 DATE OF REPORT (Year

  7. Picosecond nonlinear optical properties of cuprous oxide with different nano-morphologies

    Indian Academy of Sciences (India)

    P Harshavardhan Reddy; H Sekhar; D Narayana Rao

    2014-02-01

    Cuprous oxide nanoclusters, microcubes and microparticles were successfully synthesized by a simple co-precipitation method. Phase purity and crystallinity of the samples were studied by using X-ray powder diffraction. Transmission electron microscopy (TEM) images show different morphologies like nanoclusters, microcubes and microparticles. For linear and nonlinear optical measurements, the as-synthesized Cu2O with different morphologies were dispersed in isopropanol solution. The absorption spectrum recorded in the visible regions shows peaks that depend on the morphology of the particles and the peak shifts towards red region as one goes from nanoclusters to microparticles. Simple open-aperture Z-scan technique is used to measure nonlinear optical properties of cuprous oxide at 532 nm, 30 ps excitation at 10 Hz repetition rate. Cuprous oxide nanoclusters show reverse saturable absorption (RSA) behaviour, the microcubes and microparticles at a similar concentration exhibit saturable absorption (SA) type of behaviour at lower peak intensities and exhibit RSA within SA at higher peak intensities. The results show that the transition from SA to RSA can be ascribed to the two-photon absorption (TPA) process.

  8. Green chemistry synthesis of nano-cuprous oxide.

    Science.gov (United States)

    Ceja-Romero, L R; Ortega-Arroyo, L; Ortega Rueda de León, J M; López-Andrade, X; Narayanan, J; Aguilar-Méndez, M A; Castaño, V M

    2016-04-01

    Green chemistry and a central composite design, to evaluate the effect of reducing agent, temperature and pH of the reaction, were employed to produce controlled cuprous oxide (Cu2O) nanoparticles. Response surface method of the ultraviolet-visible spectroscopy is allowed to determine the most relevant factors for the size distribution of the nanoCu2O. X-ray diffraction reflections correspond to a cubic structure, with sizes from 31.9 to 104.3 nm. High-resolution transmission electron microscopy reveals that the different shapes depend strongly on the conditions of the green synthesis.

  9. Microwave-assisted synthesis and optical properties of cuprous oxide micro/nanocrystals

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Dandan [Key Laboratory of Processing and Testing Technology of Glass and Functional Ceramics of Shandong Province, Qilu University of Technology, Jinan 250353 (China); Du, Yi, E-mail: duyi234@126.com [Key Laboratory of Processing and Testing Technology of Glass and Functional Ceramics of Shandong Province, Qilu University of Technology, Jinan 250353 (China); Tian, Xiuying, E-mail: xiuyingt@yahoo.com [Department of Chemistry and Materials Science, Hunan Institute of Humanities Science and Technology, Loudi 417000 (China); Li, Zhongfu; Chen, Zhongtao; Zhu, Chaofeng [Key Laboratory of Processing and Testing Technology of Glass and Functional Ceramics of Shandong Province, Qilu University of Technology, Jinan 250353 (China)

    2014-12-15

    Graphical abstract: Cuprous oxide micro/nanocrystals were fabricated by a facile and green microwave-assisted method using soluble starch as reductant and dispersant. Spheres with the diameter of about 100 and 600 nm, octahedron and truncated octahedron with the edge length of about 0.8–3 μm cuprous oxide micro/nanocrystals were successfully obtained. Microwave heating was proved to be a efficient method and was advantageous to the homogeneous nucleation. Growth mechanism of the prepared Cu{sub 2}O microcrystals were investigated carefully. Furthermore, the optical properties of the prepared cuprous oxide microcrystals were investigated by UV–vis diffuse reflectance spectroscopy, demonstrating that their band gaps of obtained samples were 1.96–2.07 eV, assigned to their different sizes and morphologies. - Abstract: Cuprous oxide micro/nanocrystals were fabricated by a facile and green microwave-assisted method using soluble starch as reductant and dispersant. It was observed that the addition amounts of NaOH had a prominent effect on the morphologies and size of cuprous oxide products, and microwave heating was proved to be a efficient method and was advantageous to the homogeneous nucleation. The as-obtained samples were characterized by X-ray diffraction (XRD), and field-emission scanning electron microscopy (FESEM). The results indicated that the samples were pure cuprous oxide. Spheres with the diameter of about 100 and 600 nm, octahedron and truncated octahedron with the edge length of about 0.8–3 μm cuprous oxide micro/nanocrystals were successfully obtained. Furthermore, the UV–vis diffuse reflectance spectroscopy was used to investigate the optical properties of the prepared cuprous oxide microcrystals, demonstrating that their band gaps of obtained samples were 1.96–2.07 eV, assigned to their different sizes and morphologies.

  10. Oxidation of cuprous stellacyanin by aminopolycarboxylatocobaltate(III) complexes.

    Science.gov (United States)

    Yoneda, G S; Mitchel, G L; Blackmer, G L; Holwerda, R A

    1978-01-01

    Rate parameters are reported for the oxidation of cuprous stellacyanin by Co(PDTA)-(k(25.0 degrees) = 17.9 M(-1)sec(-1), deltaH not equal to = 8.5 kcal/mol, deltaH not equal to = 8.5 kcal/mol, deltaS not equal to = -24 cal/mol-deg; pH 7.0, Mu 0.5 M) and Co(CyDTA)-(k(25.1 degrees) = 17.0 M(-1)sec(-1), deltaH not equal to = 8.7 kcal/mol, deltaS not equal to = -24 cal/mol-deg; pH 7.0 mu 0.5 M). The first order Co(PDTA)- and Co(CyDTA)- dependences observed over wide concentration ranges contrast with the saturation behavior reported previously for Co(EDTA)- as the oxidant. It is concluded that the- CH3 and -(CH2)4-substituents of PDTA and CyDTA, respectively, prevent the alkylated derivatives of Co(EDTA)- from hydrogen bonding with the reduced blue protein, causing precursor complex formation constants to fall far below that of 149M(-1) (25.1 degrees) observed for the EDTA complex. The similarity between deltaH not equal to and deltaS not equal to values for the oxidation of stellacyanin by Co(PDTA)- and Co(CyDTA)- indicates that the size of alkyl substituents linked to the carbon atoms of the EDTA ethylenediamine backbone has little influence on activation requirements for Cu(I) to Co(III) electron transfer. The electron transfer reactivity of aminopolycarboxylatocobalt(III) complexes with cuprous stellacyanin therefore appears to be linked to the accessibility of one or more of the ligated acetate groups to outer-sphere contact with the type 1 Cu(I) center. Saturation in kobsd vs. [oxidant] plots found for the reactions of Co(PDTA)- and Co(CyDTA)- with stellacyanin at pH 6 and at pH 7 in the presence of EDTA is attributed to the formation of "dead-end" oxidant-protein complexes.

  11. Microwave Synthesis of Cuprous Oxide Micro-/Nanocrystals with Different Morphologies and Photocatalytic Activities

    Institute of Scientific and Technical Information of China (English)

    Qingwei Zhu; Yihe Zhang; Jiajun Wang; Fengshan Zhou; Paul K. Chu

    2011-01-01

    Cuprous oxide micro-/nanocrystals were synthesized by using a simple liquid phase reduction process under microwave irradiation. Copper sulfate was used as the starting materials and macromolecule surfactants served as the templates.The morphologies phase and optical properties of them are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and ultraviolet-visible diffuse reflection absorptive spectra (UV-vis/DRS), respectively. The crystals had four different shapes, namely spheres, strips, octahedrons, and dandelions. The photocatalytic behavior of the cuprous oxide particles were investigated by monitoring the degradation of rhodamine B. In spite of the different morphologies, all of the cuprous oxide micro-/nanocrystals exhibited photocatalytic activities under visible light irradiation in the following order: dandelions, strips, spheres, and octahedral crystals. The photocatalytic degradation rates of rhodamine B are 56.37%, 55.68%, 51.83% and 46.16%, respectively. The morphology affects significantly the photocatalytic performance.

  12. Enhancement of convective heat transfer coefficient of ethylene glycol base cuprous oxide (Cu2O) nanofluids

    Science.gov (United States)

    Hassan, Ali; Ramzan, Naveed; Umer, Asim; Ahmad, Ayyaz; Muryam, Hina

    2017-08-01

    The enhancement in the convective heat transfer coefficient of the ethylene glycol (EG) base cuprous oxide (Cu2O) nanofluids were investigated. The nanofluids of different volume concentrations i-e 1%, 2.5% and 4.5% were prepared by the two step method. Cuprous oxide (Cu2O) nanoparticles were ultrasonically stirred for four hours in the ethylene glycol (EG). The experimental study has been performed through circular tube geometry in laminar flow regime at average Reynolds numbers 36, 71 and 116. The constant heat flux Q = 4000 (W/m2) was maintained during this work. Substantial enhancement was observed in the convective heat transfer coefficient of ethylene glycol (EG) base cuprous oxide (Cu2O) nanofluids than the base fluid. The maximum 74% enhancement was observed in convective heat transfer coefficient at 4.5 vol% concentration and Re = 116.

  13. Towards printed perovskite solar cells with cuprous oxide hole transporting layers

    DEFF Research Database (Denmark)

    Wang, Yan; Xia, Zhonggao; Liang, Jun

    2015-01-01

    Solution-processed p-type metal oxide materials have shown great promise in improving the stability of perovskite-based solar cells and offering the feasibility for a low cost printing fabrication process. Herein, we performed a device modeling study on planar perovskite solar cells with cuprous ...

  14. Optical characterization of gold-cuprous oxide interfaces for terahertz emission applications

    NARCIS (Netherlands)

    Ramanandan, G.K.P.; Adam, A.J.L.; Ramakrishnan, G.; Petrik, P.; Hendrikx, R.; Planken, P.C.M.

    2014-01-01

    We show that the interface between gold and thermally formed cuprous oxide, which emits terahertz radiation when illuminated with ultrafast femtosecond lasers, is in fact an AuCu/Cu2O interface due to the formation of the thermal diffusion alloy AuCu. The alloy enables the formation of a Schottky-ba

  15. Epitaxially aligned cuprous oxide nanowires for all-oxide, single-wire solar cells.

    Science.gov (United States)

    Brittman, Sarah; Yoo, Youngdong; Dasgupta, Neil P; Kim, Si-in; Kim, Bongsoo; Yang, Peidong

    2014-08-13

    As a p-type semiconducting oxide that can absorb visible light, cuprous oxide (Cu2O) is an attractive material for solar energy conversion. This work introduces a high-temperature, vapor-phase synthesis that produces faceted Cu2O nanowires that grow epitaxially along the surface of a lattice-matched, single-crystal MgO substrate. Individual wires were then fabricated into single-wire, all-oxide diodes and solar cells using low-temperature atomic layer deposition (ALD) of TiO2 and ZnO films to form the heterojunction. The performance of devices made from pristine Cu2O wires and chlorine-exposed Cu2O wires was investigated under one-sun and laser illumination. These faceted wires allow the fabrication of well-controlled heterojunctions that can be used to investigate the interfacial properties of all-oxide solar cells.

  16. Attenuated total reflectance spectroscopy of simultaneous processes: Corrosion inhibition of cuprous oxide by benzotriazole

    Science.gov (United States)

    Bratescu, Maria Antoaneta; Allred, Daniel B.; Saito, Nagahiro; Sarikaya, Mehmet; Takai, Osamu

    2008-03-01

    Attenuated total reflectance (ATR) spectroscopy was used to perform in situ studies of the corrosion inhibition of cuprous oxide (Cu 2O) by benzotriazole (BTA) in aqueous solution at concentrations from 1 to 20 μM. Because two separate processes occur simultaneously, that of Cu 2O corrosion and corrosion inhibition by BTA adsorption, the spectral information was subjected to deconvolution by a conjugate gradient minimization algorithm. Under these conditions, a solution phase concentration of 7-10 μM BTA nearly completely inhibited the corrosion of Cu 2O in deionized water. Using a Langmuir adsorption model, this represented only 25% of the maximally covered surface area.

  17. A photoemission study of benzotriazole on clean copper and cuprous oxide

    Science.gov (United States)

    Fang, Bo-Shung; Olson, Clifford G.; Lynch, David W.

    1986-11-01

    Photoemission spectra of benzotriazole (BTA) chemisorbed on clean Cu and on cuprous oxide were compared with the spectra of condensed- and gas-phase BTA. Chemisorbed BTA bonds to both Cu and Cu 2O via lone-pair orbitais on the nitrogen ring. The lack of a chemical shift for the π- orbitais indicates that BTA does not lie flat on the surface. We propose a model for the geometry and bonding of chemisorbed BTA which accounts for its corrosion inhibition on Cu, and for the corrosion inhibition, or lack of inhibition, by molecules similar to BTA.

  18. Numerical simulation of exciton dynamics in cuprous oxide at ultra low temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Som, Sunipa

    2015-06-29

    This thesis is a theoretical investigation of the relaxation behaviour of excitons in Cuprous Oxide at ultra low temperatures when the excitons are confined within a potential trap and also in a homogeneous system. Under the action of deformation potential phonon scattering only, Bose Einstein Condensation (BEC) occurs for all temperatures in the investigated range. In the case of Auger decay, we do not find at any temperature a BEC due to the heating of the exciton gas. In the case of elastic and phonon-scattering together BEC occurs in this case of 0.1 K.

  19. Cuprous Oxide Scale up: Gram Production via Bulk Synthesis using Classic Solvents at Low Temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Hall, A. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Han, T. Y. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2015-05-07

    Cuprous oxide is a p-type semiconducting material that has been highly researched for its interesting properties. Many small-scale syntheses have exhibited excellent control over size and morphology. As the demand for cuprous oxide grows, the synthesis method need to evolve to facilitate large-scale production. This paper supplies a facile bulk synthesis method for Cu₂O on average, 1-liter reaction volume can produce 1 gram of particles. In order to study the shape and size control mechanisms on such a scale, the reaction volume was diminished to 250 mL producing on average 0.3 grams of nanoparticles per batch. Well-shaped nanoparticles have been synthesized using an aqueous solution of CuCl₂, NaOH, SDS surfactant, and NH₂OH-HCl at mild temperatures. The time allotted between the addition of NaOH and NH₂OH-HCl was determined to be critical for Cu(OH)2 production, an important precursor to the final produce The effects of stirring rates on a large scale was also analyzed during reagent addition and post reagent addition. A morphological change from rhombic dodecahedra to spheres occurred as the stirring speed was increased. The effects of NH₂OH-HCl concentration were also studied to control the etching effects of the final product.

  20. A Facile One Step Solution Route to Synthesize Cuprous Oxide Nanofluid

    Directory of Open Access Journals (Sweden)

    Shenoy U. Sandhya

    2013-05-01

    Full Text Available A cuprous oxide nanofluid stabilized by sodium lauryl sulfate, synthesized by using the one step method, has been reported. Nanofluids were synthesized by using a well‐ controlled surfactant‐assisted solution phase synthesis. The method involved reduction of copper acetate by glucose in a mixture of water and ethylene glycol serving as the base fluid. The synthesized fluid was characterized by X‐ray and electron diffraction techniques, in addition, transmission and field emission microscopic techniques and Fourier transform infra red spectroscopic analysis was undertaken. The rheological property, as well as the thermal conductivity of the fluid, were measured. The variation of reaction parameters considerably affected the size of the particles as well as the reaction rate. The uniform dispersion of the particles in the base fluid led to a stability period of three months under stationary state, augmenting the thermal conductivity of the nanofluid. The method is found to be simple, reliable and fast for the synthesis of Newtonian nanofluids containing cuprous oxide nanoparticles.

  1. Cuprous Sulfide/Reduced Graphene Oxide Hybrid Nanomaterials: Solvothermal Synthesis and Enhanced Electrochemical Performance

    Science.gov (United States)

    He, Zhanjun; Zhu, Yabo; Xing, Zheng; Wang, Zhengyuan

    2016-01-01

    The cuprous sulfide nanoparticles (CuS NPs)-decorated reduced graphene oxide (rGO) nanocomposites have been successfully prepared via a facile and efficient solvothermal synthesis method. Scanning electron microscopy and transmission electron microscopy images demonstrated that CuS micronspheres composed of nanosheets and distributed on the rGO layer in well-monodispersed form. Fourier-transform infrared spectroscopy analyses and x-ray photoelectron spectroscopy showed that graphene oxide (GO) had been reduced to rGO. The electrochemical performances of CuS/rGO nanocomposites were investigated by cyclic voltammetry and charge/discharge techniques, which showed that the specific capacitance of CuS/rGO nanocomposites was enhanced because of the introduction of rGO.

  2. Intrinsic Defect Engineering of Cuprous Oxide to Enhance Electrical Transport Properties for Photovoltaic Applications

    Energy Technology Data Exchange (ETDEWEB)

    Lloyd, Michael A.; Siah, Sin-Cheng; Brandt, Riley E.; Serdy, James; Johnston, Steve W.; Lee, Yun Seog; Buonassisi, Tonio

    2014-06-08

    Intrinsic point-defect species in cuprous oxide films are manipulated based on their thermodynamic properties via the implementation of a controlled annealing process. A wide range of electrical properties is demonstrated, with a window suitable for high-quality solar cell devices. A variation of carrier concentration over two orders of magnitude is demonstrated. Minority carrier lifetime is investigated by means of microwave photoconductance decay measurements, demonstrating a strong correlation with carrier concentration. Spectrally resolved photoluminescence yields are analyzed to provide insight into lifetime limiting mechanisms as a function of Cu2O processing parameters. Hall measurements of carrier mobility and concentration are taken at room temperature to provide insight into the effect of these processing conditions on net ionized defect concentration.

  3. Investigations of the interaction between cuprous oxide nanoparticles and Staphylococcus aureus

    Institute of Scientific and Technical Information of China (English)

    SHEN ChengLing; LI YuanFang; QI WenJing; HUANG ChengZhi

    2009-01-01

    Cuprous oxide nanoparticles of 30-50 nm in size were prepared in the presence of cetyltrimethylammonium bromide (CTAB).By taking Staphylococcus aureus (S.a),which always causes a variety of suppurative infections and toxinoses in humans,as a model bioparticle,the negative bioeffect of nano-Cu2O on S.a cells was evaluated,and minimal inhibitory concentration (MIC) was determined by imitating the MIC of antibiotics.Cellularity and bactericidal effect were measured by flow cytometry (FCM),dark field light scattering imaging and SEM photography.The results showed that nano-Cu2O particles may,by absorbing on the cell surface,impair the cell wall,damage the cell membrane,and finally increase permeability of the cell membrane,thus leading to a decrease in the viability of bacteria in the nano-Cu2O solution.

  4. Investigations of the interaction between cuprous oxide nanoparticles and Staphylococcus aureus

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Cuprous oxide nanoparticles of 30-50 nm in size were prepared in the presence of cetyltrimethylam-monium bromide (CTAB). By taking Staphylococcus aureus (S.a), which always causes a variety of suppurative infections and toxinoses in humans, as a model bioparticle, the negative bioeffect of nano-Cu2O on S.a cells was evaluated, and minimal inhibitory concentration (MIC) was determined by imitating the MIC of antibiotics. Cellularity and bactericidal effect were measured by flow cytometry (FCM), dark field light scattering imaging and SEM photography. The results showed that nano-Cu2O particles may, by absorbing on the cell surface, impair the cell wall, damage the cell membrane, and finally increase permeability of the cell membrane, thus leading to a decrease in the viability of bacteria in the nano-Cu2O solution.

  5. Cuprous oxide photovoltaic cells. Final report, September 1, 1978-November 30, 1979

    Energy Technology Data Exchange (ETDEWEB)

    Trivich, D.

    1979-01-01

    The research described represents the beginning of a second phase of research on cuprous oxide photovoltaic cells. The first phase was concerned with the development of procedures of making Schottky barriers on isolated films of Cu/sub 2/O, including single crystals. It was found that properties of these Schottky barrier cells, in particular the barrier heights, were limited by chemical changes at the junction especially with metals of low work function which tend to be more active chemically, e.g., Al. The motivation of the present phase of the research was to construct junctions that would avoid this chemical degradation while maintaining electrical contact between the Cu/sub 2/O and a low work function material in order to attain larger barrier heights. Essentially the approach involved placing the Cu/sub 2/O in contact with a stable oxide. When this oxide is used as a thin layer between the Cu/sub 2/O and a top metal contact this gives an MIS structure. As another approach the other oxide can be an n-type semiconductor in thicker layers to form a heterojunction. Results are reported. (WHK)

  6. Facile fabrication of electrolyte-gated single-crystalline cuprous oxide nanowire field-effect transistors

    Science.gov (United States)

    Stoesser, Anna; von Seggern, Falk; Purohit, Suneeti; Nasr, Babak; Kruk, Robert; Dehm, Simone; Wang, Di; Hahn, Horst; Dasgupta, Subho

    2016-10-01

    Oxide semiconductors are considered to be one of the forefront candidates for the new generation, high-performance electronics. However, one of the major limitations for oxide electronics is the scarcity of an equally good hole-conducting semiconductor, which can provide identical performance for the p-type metal oxide semiconductor field-effect transistors as compared to their electron conducting counterparts. In this quest, here we present a bulk synthesis method for single crystalline cuprous oxide (Cu2O) nanowires, their chemical and morphological characterization and suitability as active channel material in electrolyte-gated, low-power, field-effect transistors (FETs) for portable and flexible logic circuits. The bulk synthesis method used in the present study includes two steps: namely hydrothermal synthesis of the nanowires and the removal of the surface organic contaminants. The surface treated nanowires are then dispersed on a receiver substrate where the passive electrodes are structured, followed by printing of a composite solid polymer electrolyte (CSPE), chosen as the gate insulator. The characteristic electrical properties of individual nanowire FETs are found to be quite interesting including accumulation-mode operation and field-effect mobility of 0.15 cm2 V-1 s-1.

  7. Cuprous oxide nanoparticle-inhibited melanoma progress by targeting melanoma stem cells.

    Science.gov (United States)

    Yu, Bin; Wang, Ye; Yu, Xinlu; Zhang, Hongxia; Zhu, Ji; Wang, Chen; Chen, Fei; Liu, Changcheng; Wang, Jingqiang; Zhu, Haiying

    2017-01-01

    Recent studies have shown that metal and metal oxide have a potential function in antitumor therapy. Our previous studies demonstrated that cuprous oxide nanoparticles (CONPs) not only selectively induce apoptosis of tumor cells in vitro but also inhibit the growth and metastasis of melanoma by targeting mitochondria with little hepatic and renal toxicities in mice. As a further study, our current research revealed that CONPs induced apoptosis of human melanoma stem cells (CD271(+/high) cells) in A375 and WM266-4 melanoma cell lines and could significantly suppress the expression of MITF, SOX10 and CD271 involved in the stemness maintenance and tumorigenesis of melanoma stem cells. CD271(+/high) cells could accumulate more CONPs than CD271(-/low) through clathrin-mediated endocytosis. In addition, lower dosage of CONPs exhibited good anti-melanoma effect by decreasing the cell viability, stemness and tumorigenesis of A375 and WM266-4 cells through reducing the expression of SOX10, MITF, CD271 and genes in MAPK pathway involved in tumor progression. Finally, CONPs obviously suppressed the growth of human melanoma in tumor-bearing nonobese diabetic-severe combined immunodeficiency (NOD-SCID) mice, accompanied with tumors structural necrosis and fibrosis remarkably and decreased expression of CD271, SOX10 and MITF. These results above proved the effectiveness of CONPs in inhibiting melanoma progress through multiple pathways, especially through targeting melanoma stem cells.

  8. Towards printed perovskite solar cells with cuprous oxide hole transporting layers: a theoretical design

    Science.gov (United States)

    Wang, Yan; Xia, Zhonggao; Liang, Jun; Wang, Xinwei; Liu, Yiming; Liu, Chuan; Zhang, Shengdong; Zhou, Hang

    2015-05-01

    Solution-processed p-type metal oxide materials have shown great promise in improving the stability of perovskite-based solar cells and offering the feasibility for a low cost printing fabrication process. Herein, we performed a device modeling study on planar perovskite solar cells with cuprous oxide (Cu2O) hole transporting layers (HTLs) by using a solar cell simulation program, wxAMPS. The performance of a Cu2O/perovskite solar cell was correlated to the material properties of the Cu2O HTL, such as thickness, carrier mobility, mid-gap defect, and doping concentrations. The effect of interfacial defect densities on the solar cell performance was also investigated. Our simulation indicates that, with an optimized Cu2O HTL, high performance perovskite solar cells with efficiencies above 13% could be achieved, which shows the potential of using Cu2O as an alternative HTL over other inorganic materials, such as NiOx and MoOx. This study provides theoretical guidance for developing perovskite solar cells with inorganic hole transporting materials via a printing process.

  9. One-pot synthesis of cuprous oxide-reduced graphene oxide nanocomposite with enhanced photocatalytic and electrocatalytic performance

    Science.gov (United States)

    Han, Fugui; Li, Heping; Yang, Jun; Cai, Xiaodong; Fu, Li

    2016-03-01

    We report on the facile one-step synthesis of porous cuprous oxide nanoparticles on reduced graphene oxide (Cu2O-RGO) by synchronously reducing Cu2+ ions and GO with ethylene glycol. The basic chemical components, crystal structure and surface morphology of prepared nanocomposite was carefully characterized. The photocatalytic activities of the as-prepared nanocomposite was investigated by photodegrading methylene blue (MB) under visible light. The electrocatalytic property of the nanocomposite was investigated by electrocatalytic determination of acetaminophen. The results indicate that the corporation of RGO with Cu2O nanoparticles could high enhance the both photocatalytic and electrocatalytic properties. Moreover, we found that the content of RGO introduced into nanocomposite could highly affect the product properties.

  10. Improvement in structural and electrical properties of cuprous oxide-coated multiwalled carbon nanotubes

    Indian Academy of Sciences (India)

    Shivani Dhall; Neena Jaggi

    2014-10-01

    In the present work, cuprous oxide (Cu2O) nanoparticles are coated on multi-walled carbon nanotubes (MWCNTs) using Fehling’s reaction. The coating of Cu2O nanoparticles on the nanotubes was confirmed by SEM and X-ray diffraction (XRD) spectra. The calculated D/G ratio of Cu2O (using 3% CuSO4 by wt)-coated MWCNTs by Raman spectra is found to decrease to 0.94 as compared to 1.14 for pristine MWCNTs. It shows that the presence of Cu2O nanoparticles on nanotubes decreases the inherent defects present in the form of some pentagons/heptagons in the honeycomb hexagonal carbon atoms in the structure of graphene sheets of MWCNTs and increases the crystalline nature of MWCNTs, which is also confirmed by the XRD peaks. Whereas the value of D/G ratio increases to 1.39 for sample 2 (using 5% CuSO4 by wt), which represents the structural deformation. Moreover, the electrical conductivity of MWCNTs was increased by 3 times after coating the nanotubes with Cu2O (using 3% CuSO4 by wt).

  11. Structural, Optical and Electrical Properties of Nanocrystalline Cuprous Oxide Thin Film Deposited By Chemical Method

    Directory of Open Access Journals (Sweden)

    Prakash Bansilal Ahirrao

    2010-06-01

    Full Text Available Cuprous oxide (Cu2O is an interesting p-type semiconductor material used in solar cell applications.  The Modified Chemical Bath Deposition (M-CBD method is suitable for growing thin multilayer structure due to low deposition temperature. This method does not require any sophisticated instrument and substrate need not to be conductive. The nanocrystalline Cu2O thin films were deposited on glass substrates by M-CBD method. The deposited films were characterized by different characterization techniques to study structural, surface morphological, optical and electrical properties. The structural studies show that, the formation of Cu2O thin films with an average crystallite size of 14 nm. Optical studies show a direct band gap 2.48 eV. The room temperature electrical resistivity is of the order of 1.3 kW-cm and activation energy 0.33 eV. The films exhibit p-type electrical conductivity as seen by thermo-emf measurements.

  12. Parameters controlling microstructures and resistance switching of electrodeposited cuprous oxide thin films

    Science.gov (United States)

    Yazdanparast, Sanaz

    2016-12-01

    Cuprous oxide (Cu2O) thin films were electrodeposited cathodically from a highly alkaline bath using tartrate as complexing agent. Different microstructures for Cu2O thin films were achieved by varying the applied potential from -0.285 to -0.395 V versus a reference electrode of Ag/AgCl at 50 °C in potentiostatic mode, and separately by changing the bath temperature from 25 to 50 °C in galvanostatic mode. Characterization experiments showed that both grain size and orientation of Cu2O can be controlled by changing the applied potential. Applying a high negative potential of -0.395 V resulted in smaller grain size of Cu2O thin films with a preferred orientation in [111] direction. An increase in the bath temperature in galvanostatic electrodeposition increased the grain size of Cu2O thin films. All the films in Au/Cu2O/Au-Pd cell showed unipolar resistance switching behavior after an initial FORMING process. Increasing the grain size of Cu2O thin films and decreasing the top electrode area increased the FORMING voltage and decreased the current level of high resistance state (HRS). The current in low resistance state (LRS) was independent of the top electrode area and the grain size of deposited films, suggesting a filamentary conduction mechanism in unipolar resistance switching of Cu2O.

  13. Carbon-layer-protected cuprous oxide nanowire arrays for efficient water reduction

    KAUST Repository

    Zhang, Zhonghai

    2013-02-26

    In this work, we propose a solution-based carbon precursor coating and subsequent carbonization strategy to form a thin protective carbon layer on unstable semiconductor nanostructures as a solution to the commonly occurring photocorrosion problem of many semiconductors. A proof-of-concept is provided by using glucose as the carbon precursor to form a protective carbon coating onto cuprous oxide (Cu2O) nanowire arrays which were synthesized from copper mesh. The carbon-layer-protected Cu2O nanowire arrays exhibited remarkably improved photostability as well as considerably enhanced photocurrent density. The Cu2O nanowire arrays coated with a carbon layer of 20 nm thickness were found to give an optimal water splitting performance, producing a photocurrent density of -3.95 mA cm-2 and an optimal photocathode efficiency of 0.56% under illumination of AM 1.5G (100 mW cm-2). This is the highest value ever reported for a Cu 2O-based electrode coated with a metal/co-catalyst-free protective layer. The photostability, measured as the percentage of the photocurrent density at the end of 20 min measurement period relative to that at the beginning of the measurement, improved from 12.6% on the bare, nonprotected Cu2O nanowire arrays to 80.7% on the continuous carbon coating protected ones, more than a 6-fold increase. We believe that the facile strategy presented in this work is a general approach that can address the stability issue of many nonstable photoelectrodes and thus has the potential to make a meaningful contribution in the general field of energy conversion. © 2013 American Chemical Society.

  14. Cytotoxicity of cuprous oxide nanoparticles to fish blood cells: hemolysis and internalization

    Energy Technology Data Exchange (ETDEWEB)

    Chen Liqiang, E-mail: chenlq@ynu.edu.cn; Kang Bin [Yunnan University, Asian International Rivers Center, Yunnan Key Laboratory of International Rivers and Trans-boundary Eco-security (China); Ling Jian [Yunnan University, College of Chemistry and Chemical Engineering (China)

    2013-03-15

    Cuprous oxide nanoparticles (Cu{sub 2}O NPs) possess unique physical and chemical properties which are employed in a broad variety of applications. However, little is known about the adverse effects of Cu{sub 2}O NPs on organisms. In the current study, in vitro cytotoxicity of Cu{sub 2}O NPs (ca. 60 nm in diameter) to the blood cells of freshwater fish Carassius auratus was evaluated. A concentration-dependent hemolytic activity of Cu{sub 2}O NPs to red blood cells (RBCs) and the phagocytosis of Cu{sub 2}O NPs by leukocytes were revealed. The results showed that dosages of Cu{sub 2}O NPs greater than 40 {mu}g/mL were toxic to blood cells, and could cause serious membrane damage to RBCs. The EC{sub 50} value of Cu{sub 2}O NPs as obtained from RBCs and whole blood exposure was 26 and 63 {mu}g/mL, respectively. The generation of reactive oxygen species and the direct interaction between Cu{sub 2}O NPs and the cell membrane were suggested as the possible mechanism for cytotoxicity, and the intrinsic hemolytic active of Cu{sub 2}O NPs was the main contributor to the toxicity rather than solubilized copper ions. The adsorption of plasma proteins on the surfaces of Cu{sub 2}O NPs led to their aggregation in whole blood, and aggregate formation can significantly alleviate the hemolytic effect and subsequently mediate the phagocytosis of Cu{sub 2}O NPs by leukocytes.

  15. Reduced graphene oxide–cuprous oxide composite via facial deposition for photocatalytic dye-degradation

    Energy Technology Data Exchange (ETDEWEB)

    Wang, MingYan, E-mail: mingyanlyg@hotmail.com [Department of Chemical Engineering, Huaihai Institute of Technology, Lianyungang 222005 (China); Intelligent Polymer Research Institute, ARC Centre of Excellence for Electromaterials Science, Australian Institute of Innovative Materials, University of Wollongong, Northfields Avenue, Wollongong, NSW 2522 (Australia); Huang, JunRao; Tong, ZhiWei [Department of Chemical Engineering, Huaihai Institute of Technology, Lianyungang 222005 (China); Li, WeiHua [School of Mechanical, Materials and Mechatronic Engineering, University of Wollongong, Northfields Avenue, Wollongong, NSW 2522 (Australia); Chen, Jun, E-mail: junc@uow.edu.au [Intelligent Polymer Research Institute, ARC Centre of Excellence for Electromaterials Science, Australian Institute of Innovative Materials, University of Wollongong, Northfields Avenue, Wollongong, NSW 2522 (Australia)

    2013-08-15

    Highlights: •Cubic Cu{sub 2}O were effectively loaded on n-propylamine (PA) intercalated graphene oxide. •The addition of PA on the carbon sheets supports the stable structure of the composites. •Cu{sub 2}O/PA/rGO showed superior adsorption capacity and photocatalytic activity. -- Abstract: Cubic Cu{sub 2}O nanoparticles have been successfully synthesized on n-propylamine (PA) intercalated graphene oxide (GO) with uniform distribution followed with a subsequent hydrazine hydrate reduction process to generate Cu{sub 2}O/PA/rGO composite. For comparison, Cu{sub 2}O conjugated reduced graphene oxide (Cu{sub 2}O/rGO) composite was also synthesized using the same method. The as-prepared Cu{sub 2}O/PA/rGO and Cu{sub 2}O/rGO nanocomposites are characterized by X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) spectroscopy, infrared spectroscopy (IR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Brunauer–Emmett–Teller (BET) surface area analysis, and Electrochemical impedance spectra (EIS) measurements. UV/vis diffuse reflectance spectroscopy was employed to estimate band gap energies of cuprous oxide composites. The results show that the intercalation of PA into the layered GO increases the surface area of the composites and provides an efficient strategy to load Cu{sub 2}O due to the large and uniform distribution of active sites for anchoring copper ions. The surface area of the Cu{sub 2}O/PA/rGO (123 m{sup 2}/g) nanocomposite was found to be almost 2.5 times higher than that of Cu{sub 2}O/rGO (55.7 m{sup 2}/g). The as-prepared Cu{sub 2}O/PA/rGO show significant improvement on both adsorption capacity and photocatalytic activity towards organic pigment pollution compared with Cu{sub 2}O/rGO under identical performance conditions.

  16. Hydrometallurgical process for the recycling of copper using anodic oxidation of cuprous ammine complexes and flow-through electrolysis

    Energy Technology Data Exchange (ETDEWEB)

    Oishi, T.; Yaguchi, M.; Koyama, K.; Tanaka, M. [Metals Recycling Group, Research Institute for Environmental Management Technology, National Institute of Advanced Industrial Science and Technology (AIST), 16-1 Onogawa, Tsukuba, Ibaraki 305-8569 (Japan); Lee, J.-C. [Minerals and Materials Processing Division, Korea Institute of Geoscience and Mineral Resources (KIGAM), 30 Gajeong-dong, Yuseong-ku, Daejeon 305-350 (Korea)

    2008-01-01

    Flow-through electrolysis for copper electrowinning from cuprous ammine complex was studied in order to develop a hydrometallurgical copper recycling process using an ammoniacal chloride solution, focusing on the anodic oxidation of cuprous to cupric ammine complexes. The current efficiency of this anodic oxidation was 96% at a current density of 200 A m{sup -2} under a batch condition. In a flow-through electrolysis using a sub-liter cell and a carbon felt anode, the anodic current efficiency increased with the flow rate and was typically higher than 97%. This tendency was explained by the backward flow of the cupric ammine complex, which was formed on the anode, through the diaphragm. The anodic overpotential was lower than 0.3 V even at an apparent current density of 1500 A m{sup -2}. A similar current efficiency and overpotential were also achieved in a liter scale cell, which indicates the scale flexibility of this electrolysis. The power consumption requirements for copper electrowinning in this cell were 460 and 770 kWh t{sup -1} at the current densities of 250 and 500 A m{sup -2}, respectively, which were much lower than that of the conventional copper electrowinning despite the longer interpolar distance. (author)

  17. Plasmon-induced selective carbon dioxide conversion on earth-abundant aluminum-cuprous oxide antenna-reactor nanoparticles.

    Science.gov (United States)

    Robatjazi, Hossein; Zhao, Hangqi; Swearer, Dayne F; Hogan, Nathaniel J; Zhou, Linan; Alabastri, Alessandro; McClain, Michael J; Nordlander, Peter; Halas, Naomi J

    2017-06-21

    The rational combination of plasmonic nanoantennas with active transition metal-based catalysts, known as 'antenna-reactor' nanostructures, holds promise to expand the scope of chemical reactions possible with plasmonic photocatalysis. Here, we report earth-abundant embedded aluminum in cuprous oxide antenna-reactor heterostructures that operate more effectively and selectively for the reverse water-gas shift reaction under milder illumination than in conventional thermal conditions. Through rigorous comparison of the spatial temperature profile, optical absorption, and integrated electric field enhancement of the catalyst, we have been able to distinguish between competing photothermal and hot-carrier driven mechanistic pathways. The antenna-reactor geometry efficiently harnesses the plasmon resonance of aluminum to supply energetic hot-carriers and increases optical absorption in cuprous oxide for selective carbon dioxide conversion to carbon monoxide with visible light. The transition from noble metals to aluminum based antenna-reactor heterostructures in plasmonic photocatalysis provides a sustainable route to high-value chemicals and reaffirms the practical potential of plasmon-mediated chemical transformations.Plasmon-enhanced photocatalysis holds promise for the control of chemical reactions. Here the authors report an Al@Cu2O heterostructure based on earth abundant materials to transform CO2 into CO at significantly milder conditions.

  18. Preparation of 3D nanoporous copper-supported cuprous oxide for high-performance lithium ion battery anodes.

    Science.gov (United States)

    Liu, Dequan; Yang, Zhibo; Wang, Peng; Li, Fei; Wang, Desheng; He, Deyan

    2013-03-01

    Three-dimensional (3D) nanoporous architectures can provide efficient and rapid pathways for Li-ion and electron transport as well as short solid-state diffusion lengths in lithium ion batteries (LIBs). In this work, 3D nanoporous copper-supported cuprous oxide was successfully fabricated by low-cost selective etching of an electron-beam melted Cu(50)Al(50) alloy and subsequent in situ thermal oxidation. The architecture was used as an anode in lithium ion batteries. In the first cycle, the sample delivered an extremely high lithium storage capacity of about 2.35 mA h cm(-2). A high reversible capacity of 1.45 mA h cm(-2) was achieved after 120 cycles. This work develops a promising approach to building reliable 3D nanostructured electrodes for high-performance lithium ion batteries.

  19. Optical Study of Cuprous Oxide and Ferric Oxide Based Materials for Applications in Low Cost Solar Cells

    Science.gov (United States)

    Than, Thi Cuc; Bui, Bao Thoa; Wegmuller, Benjamin; Nguyen, Minh Hieu; Hoang Ngoc, Lam Huong; Bui, Van Diep; Nguyen, Quoc Hung; Hoang, Chi Hieu; Nguyen-Tran, Thuat

    2016-05-01

    One of the interesting forms of cuprous oxide and ferric oxide based materials is CuFeO2 which can be a delafossite-type compound and is a well known p-type semiconductor. This compound makes up an interesting family of materials for technological applications. CuFeO2 thin films recently gained renewed interest for potential applications in solar cell devices especially as absorption layers. One of the interesting facts is that CuFeO2 is made from cheap materials such as copper and iron. In this study, CuFeO2 thin films are intentionally deposited on corning glass and silicon substrates by the radio-frequency and direct current sputtering method with complicated and well developed co-sputtering recipes. The deposition was performed at room temperature which leads to an amorphous phase with extremely low roughness and high density. The films also were annealed at 500°C in 5% H2 in Ar for the passivation. A detailed optical study was performed on these thin films by spectroscopic ellipsometry and by ultra-violet visible near infrared spectroscopy. Depending on sputtering conditions, the direct band gap was extrapolated to be from 1.96 eV to 2.2 eV and 2.92 eV to 2.96 eV and the indirect band gap is about 1.22 eV to 1.42 eV. A good electrical conduction is also observed which is suitable for solar cell applications. In future more study on the structural properties will be carried out in order to fully understand these materials.

  20. Cuprous oxide nanoparticles inhibit prostate cancer by attenuating the stemness of cancer cells via inhibition of the Wnt signaling pathway

    Science.gov (United States)

    Wang, Ye; Yang, Qi-Wei; Yang, Qing; Zhou, Tie; Shi, Min-Feng; Sun, Chen-Xia; Gao, Xiu-Xia; Cheng, Yan-Qiong; Cui, Xin-Gang; Sun, Ying-Hao

    2017-01-01

    Disordered copper metabolism plays a critical role in the development of various cancers. As a nanomedicine containing copper, cuprous oxide nanoparticles (CONPs) exert ideal antitumor pharmacological effects in vitro and in vivo. Prostate cancer is a frequently diagnosed male malignancy prone to relapse, and castration resistance is the main reason for endocrine therapy failure. However, whether CONPs have the potential to treat castration-resistant prostate cancer is still unknown. Here, using the castration-resistant PC-3 human prostate cancer cell line as a model, we report that CONPs can selectively induce apoptosis and inhibit the proliferation of cancer cells in vitro and in vivo without affecting normal prostate epithelial cells. CONPs can also attenuate the stemness of cancer cells and inhibit the Wnt signaling pathway, both of which highlight the great potential of CONPs as a new clinical castration-resistant prostate cancer therapy.

  1. Nonlinear optical properties of bulk cuprous oxide using single beam Z-scan at 790 nm

    Energy Technology Data Exchange (ETDEWEB)

    Serna, J.; Rueda, E. [Grupo de Óptica y Fotónica, Instituto de Física, Universidad de Antioquia U de A, Calle 70 No. 52-21, Medellín (Colombia); García, H., E-mail: hgarcia@siue.edu [Department of Physics, Southern Illinois University, Edwardsville, Illinois 60026 (United States)

    2014-11-10

    The two-photon absorption (TPA) coefficient β and the nonlinear index of refraction n{sub 2} for bulk cuprous oxide (Cu{sub 2}O) direct gap semiconductor single crystal have been measured by using a balance-detection Z-scan single beam technique, with an excellent signal to noise ratio. Both coefficients were measured at 790 nm using a 65 fs laser pulse at a repetition rate of 90.9 MHz, generated by a Ti:Sapphire laser oscillator. The experimental values for β were explained by using a model that includes allowed-allowed, forbidden-allowed, and forbidden-forbidden transitions. It was found that the forbidden-forbidden transition is the dominant mechanism, which is consistent with the band structure of Cu{sub 2}O. The low value for β found in bulk, as compared with respect to thin film, is explained in terms of the structural change in thin films that result in opposite parities of the conduction and valence band. The n{sub 2} is also theoretically calculated by using the TPA dispersion curve and the Kramers-Kronig relations for nonlinear optics.

  2. Novel Facile Technique for Synthesis of Stable Cuprous Oxide (Cu2O Nanoparticles – an Ageing Effect

    Directory of Open Access Journals (Sweden)

    Sachin S. Sawant

    2016-03-01

    Full Text Available A novel facile method to synthesize stable phase of Cuprous Oxide (Cu2O nanoparticles at room temperature is demonstrated. The structural and optical properties of (Cu2O nanoparticles were investigated by using X-ray diffraction (XRD, UV-VIS Spectroscopy. XRD analysis has indexed nanocrystalline nature of cubical phase Cu2O with an average edge length of about 20 nm. The Scanning Electron Microscopy (SEM measurements also ascertain the cubical morphology. The Fourier Transform Infrared Spectroscopy (FTIR affirms the presence of characteristic functional group of Cu2O. The absorbance peak at 485 nm in UV-VIS spectra also confirms the Cu2O synthesis. Furthermore, UV-VIS absorbance spectra at different ageing time substantiate the phase stability of Cu2O nanoparticles. The ageing leads to blue shift of absorbance peak mainly due to decrease in Cu2O particle size with no additional absorbance peak in UV-VIS spectra indicating the formation of secondary phase. The reduction in particle size may be attributed to tiny conversion Cu2O to CuO. The energy band gap measurements from Tauc plots for Cu2O nanoparticles shows the increasing trend (2.5 eV to 2.8 eV with ageing time (2 months, owing to quantum confinement effects.

  3. Preparation of cuprous oxides with different sizes and their behaviors of adsorption, visible-light driven photocatalysis and photocorrosion

    Science.gov (United States)

    Huang, Lei; Peng, Feng; Yu, Hao; Wang, Hongjuan

    2009-01-01

    Cuprous oxide (Cu 2O) nanoparticles and microparticles have been prepared by liquid phase chemical synthesis. The samples were characterized by means of SEM, XRD, UV/DRS and XPS. It was presented that as-prepared Cu 2O nanoparticles are substantially stable in ambient atmosphere and the Cu + as main state exists on the surface of Cu 2O nanoparticles. As-prepared Cu 2O microparticles can exist stably as a Cu 2O/CuO core/shell structure; and the Cu 2+ as main state exists on the surface of Cu 2O microparticles. The behaviors of adsorption, photocatalysis and photocorrosion of Cu 2O particles with different sizes were investigated in detail. The results show that Cu 2O nanoparticles are very easy to photocorrosion during the photocatalytic reaction, which cannot be used as photocatalyst directly to degrade organic compound, although as-prepared Cu 2O nanoparticles exhibit special property of adsorption. Cu 2O microparticles have a higher photocatalytic activity than Cu 2O nanoparticles because of its slower photocorrosion rate, although Cu 2O microparticles have much lower adsorption capacity than Cu 2O nanoparticles. The mechanisms of photocatalysis and photocorrosion for Cu 2O under visible light were also discussed.

  4. A novel reducing graphene/polyaniline/cuprous oxide composite hydrogel with unexpected photocatalytic activity for the degradation of Congo red

    Energy Technology Data Exchange (ETDEWEB)

    Miao, Jie; Xie, Anjian; Li, Shikuo; Huang, Fangzhi; Cao, Juan; Shen, Yuhua, E-mail: yhshen@ahu.edu.cn

    2016-01-01

    Graphical abstract: Excellent photocatalytic activity of the RGO/PANI/Cu{sub 2}O composite hydrogel for CR degradation under UV–vis light irradiation. - Highlights: • The RGO/PANI/Cu{sub 2}O composite hydrogel was first synthesized via a facile method. • Photocatalytic performance was studied under UV–vis light. • The ternary composite hydrogel shows unexpected photocatalytic activity. • A possible photocatalysis mechanism was illustrated. - Abstract: In this work, a novel reducing graphene/polyaniline/cuprous oxide (RGO/PANI/Cu{sub 2}O) composite hydrogel with a 3D porous network has been successfully prepared via a one-pot method in the presence of cubic Cu{sub 2}O nanoparticles. The as-synthesized ternary composites hydrogel shows unexpected photocatalytic activity such that Congo red (CR) degradation efficiency can reaches 97.91% in 20 min under UV–vis light irradiation, which is much higher than that of either the single component (Cu{sub 2}O nanoparticles), or two component systems (RGO/Cu{sub 2}O composite hydrogel and PANI/Cu{sub 2}O nanocomposites). Furthermore, the ternary composite hydrogel exhibits high stability and do not show any significant loss after five recycles. Such outstanding photocatalytic activity of the RGO/PANI/Cu{sub 2}O composite hydrogel was ascribed to the high absorption ability of the product for CR and the synergic effect among RGO, PANI and Cu{sub 2}O in photocatalytic process. The product of this work would provide a new sight for the construction of UV–vis light responsive photocatalyst with high performance.

  5. Plasma-produced phase-pure cuprous oxide nanowires for methane gas sensing

    Energy Technology Data Exchange (ETDEWEB)

    Cheng, Qijin, E-mail: ijin.cheng@xmu.edu.cn; Zhang, Fengyan [School of Energy Research, Xiamen University, Xiamen City, Fujian Province 361005 (China); Yan, Wei [School of Electrical Engineering and Telecommunications, University of New South Wales, Sydney, New South Wales 2052 (Australia); Plasma Nanoscience Laboratories, CSIRO Materials Science and Engineering, Lindfield, New South Wales 2070 (Australia); Randeniya, Lakshman [Plasma Nanoscience Laboratories, CSIRO Materials Science and Engineering, Lindfield, New South Wales 2070 (Australia); Ostrikov, Kostya [Plasma Nanoscience Laboratories, CSIRO Materials Science and Engineering, Lindfield, New South Wales 2070 (Australia); Plasma Nanoscience, School of Physics, The University of Sydney, Sydney, New South Wales 2006 (Australia)

    2014-03-28

    Phase-selective synthesis of copper oxide nanowires is warranted by several applications, yet it remains challenging because of the narrow windows of the suitable temperature and precursor gas composition in thermal processes. Here, we report on the room-temperature synthesis of small-diameter, large-area, uniform, and phase-pure Cu{sub 2}O nanowires by exposing copper films to a custom-designed low-pressure, thermally non-equilibrium, high-density (typically, the electron number density is in the range of 10{sup 11}–10{sup 13} cm{sup −3}) inductively coupled plasmas. The mechanism of the plasma-enabled phase selectivity is proposed. The gas sensors based on the synthesized Cu{sub 2}O nanowires feature fast response and recovery for the low-temperature (∼140 °C) detection of methane gas in comparison with polycrystalline Cu{sub 2}O thin film-based gas sensors. Specifically, at a methane concentration of 4%, the response and the recovery times of the Cu{sub 2}O nanowire-based gas sensors are 125 and 147 s, respectively. The Cu{sub 2}O nanowire-based gas sensors have a potential for applications in the environmental monitoring, chemical industry, mining industry, and several other emerging areas.

  6. Characterizations of Cuprous Oxide Thin Films Prepared by Sol-Gel Spin Coating Technique with Different Additives for the Photoelectrochemical Solar Cell

    Directory of Open Access Journals (Sweden)

    D. S. C. Halin

    2014-01-01

    Full Text Available Cuprous oxide (Cu2O thin films were deposited onto indium tin oxide (ITO coated glass substrate by sol-gel spin coating technique using different additives, namely, polyethylene glycol and ethylene glycol. It was found that the organic additives added had a significant influence on the formation of Cu2O films and lead to different microstructures and optical properties. The films were characterized by X-ray diffraction (XRD, field emission scanning electron microscopy (FESEM, and ultraviolet-visible spectroscopy (UV-Vis. Based on the FESEM micrographs, the grain size of film prepared using polyethylene glycol additive has smaller grains of about 83 nm with irregular shapes. The highest optical absorbance film was obtained by the addition of polyethylene glycol. The Cu2O thin films were used as a working electrode in the application of photoelectrochemical solar cell (PESC.

  7. Cupric and cuprous oxide by reactive ion beam sputter deposition and the photosensing properties of cupric oxide metal–semiconductor–metal Schottky photodiodes

    Energy Technology Data Exchange (ETDEWEB)

    Hong, Min-Jyun; Lin, Yong-Chen; Chao, Liang-Chiun, E-mail: lcchao@mail.ntust.edu.tw; Lin, Pao-Hung; Huang, Bohr-Ran

    2015-08-15

    Highlights: • CuO and Cu{sub 2}O were deposited by reactive ion beam sputter deposition. • Single phase CuO thin film is obtained with Ar:O{sub 2} = 2:1. • CuO MSM PD shows photoresponse from 400 nm to 1.30 μm. • CuO MSM PD is RC limited with a decay time less than 1 μs. - Abstract: Cupric (CuO) and cuprous (Cu{sub 2}O) oxide thin films have been deposited by reactive ion beam sputter deposition at 400 °C with an Ar:O{sub 2} ratio from 2:1 to 12:1. With an Ar:O{sub 2} ratio of 2:1, single phase polycrystalline CuO thin films were obtained. Decreasing oxygen flow rate results in CuO + Cu{sub 2}O and Cu{sub 2}O + Cu mixed thin films. As Ar:O{sub 2} ratio reaches 12:1, Cu{sub 2}O nanorods with diameter of 250 nm and length longer than 1 μm were found across the sample. Single phase CuO thin film exhibits an indirect band gap of 1.3 eV with a smooth surface morphology. CuO metal–semiconductor–metal (MSM) Schottky photodiodes (PD) were fabricated by depositing Cu interdigitated electrodes on CuO thin films. Photosensing properties of the CuO PD were characterized from 350 to 1300 nm and a maximum responsivity of 43 mA/W was found at λ = 700 nm. The MSM PD is RC limited with a decay time constant less than 1 μs.

  8. Literature review on the properties of cuprous oxide Cu{sub 2}O and the process of copper oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Korzhavyi, P. A.; Johansson, B. (Department of Materials Science and Engineering, Royal Institute of Technology, Stockholm (Sweden))

    2011-10-15

    The purpose of the present review is to provide a reference guide to the most recent data on the properties of copper(I) oxide as well as on the atomic processes involved in the initial stages of oxidation of copper. The data on the structure of surfaces, as obtained from atomic-resolution microscopy studies (for example, STM) or from first-principles calculations, are reviewed. Information of this kind may be useful for understanding the atomic mechanisms of corrosion and stress-corrosion cracking of copper

  9. Constructing heterostructure on highly roughened caterpillar-like gold nanotubes with cuprous oxide grains for ultrasensitive and stable nonenzymatic glucose sensor.

    Science.gov (United States)

    Chen, Anran; Ding, Yu; Yang, Zhimao; Yang, Shengchun

    2015-12-15

    In this study, a metal-metal oxide heterostructure was designed and constructed by growing cuprous oxide (Cu2O) grains on highly surface roughened caterpillar-like Au nanotubes (CLGNs) for ultrasensitive, selective and stable nonenzymatic glucose biosensors. The Cu2O grains are tightly anchored to the surface of CLGNs by the spines, resulting in a large increase in the contact area between Cu2O grains and the CLGNs, which facilitates the electron transport between metal and metal oxide and improves the sensitivity and stability of the sensors. The electron transfer coefficient (α) and electron transfer rate constant (ks) for redox reaction of Cu2O-CLGNs/GCE are found to be 0.50114 and 3.24±0.1 s(-1), respectively. The biosensor shows a linear response to glucose over a concentration range of 0.1-5mM and a high sensitivity of 1215.7 µA mM(-1) cm(-2) with a detection limit of 1.83 μM. Furthermore, the Cu2O-CLGNs biosensor exhibited strong anti-interference capability against uric acid (UA), ascorbic acid (AA), potassium chloride (KCl) and sodium ascorbate (SA), as well as a high stability and repeatability. Our current research indicates that the Cu2O-CLGNs hybrid electrode is a promising choice for constructing nonenzyme based electrochemical biosensors.

  10. Multilayer core-shell structured composite paper electrode consisting of copper, cuprous oxide and graphite assembled on cellulose fibers for asymmetric supercapacitors

    Science.gov (United States)

    Wan, Caichao; Jiao, Yue; Li, Jian

    2017-09-01

    An easily-operated and inexpensive strategy (pencil-drawing-electrodeposition-electro-oxidation) is proposed to synthesize a novel class of multilayer core-shell structured composite paper electrode, which consists of copper, cuprous oxide and graphite assembled on cellulose fibers. This interesting electrode structure plays a pivotal role in providing more active sites for electrochemical reactions, facilitating ion and electron transport and shorting their diffusion pathways. This electrode demonstrates excellent electrochemical properties with a high specific capacitance of 601 F g-1 at 2 A g-1 and retains 83% of this capacitance when operated at an ultrahigh current density of 100 A g-1. In addition, a high energy density of 13.4 W h kg-1 at the power density of 0.40 kW kg-1 and a favorable cycling stability (95.3%, 8000 cycles) were achieved for this electrode. When this electrode was assembled into an asymmetric supercapacitor with carbon paper as negative electrode, the device displays remarkable electrochemical performances with a large areal capacitances (122 mF cm-2 at 1 mA cm-2), high areal energy density (10.8 μW h cm-2 at 402.5 μW cm-2) and outstanding cycling stability (91.5%, 5000 cycles). These results unveil the potential of this composite electrode as a high-performance electrode material for supercapacitors.

  11. Physico-chemical studies of cuprous oxide (Cu{sub 2}O) nanoparticles coated on amorphous carbon nanotubes (α-CNTs)

    Energy Technology Data Exchange (ETDEWEB)

    Johan, Mohd Rafie, E-mail: mrafiej@um.edu.my; Meriam Suhaimy, Syazwan Hanani; Yusof, Yusliza, E-mail: yus_liza@siswa.um.edu.my

    2014-01-15

    Amorphous carbon nanotubes (α-CNTs) were synthesized by a chemical reaction between ferrocene and ammonium chloride at a temperature (∼250 °C) in an air furnace. As- synthesized α-CNTs were purified with deionized water and hydrochloric acid. A purified α-CNTs were hybridized with cuprous oxide nanoparticles (Cu{sub 2}O) through a simple chemical process. Morphology of the samples was analyzed with field emission scanning electron microscope (FESEM) and transmission electron microscopy (TEM). Fourier transform infrared (FTIR) spectra showed the attachment of acidic functional groups onto the surface of α-CNTs and the formation of hybridized α-CNTs-Cu{sub 2}O. Raman spectra reveal the amorphous nature of the carbon. X-ray diffraction (XRD) pattern confirmed the amorphous phase of the carbon and the formation of Cu{sub 2}O crystalline phase. The coating of Cu{sub 2}O was confirmed by FESEM, TEM, and XRD. Optical absorption of the samples has also been investigated and the quantum confinement effect was illustrated in the absorption spectra.

  12. Photocatalytic Degradation of Rhodamine B by Cuprous Oxide%氧化亚铜光催化降解罗丹明 B

    Institute of Scientific and Technical Information of China (English)

    黄涛; 吕重安; 杨水金

    2014-01-01

    Cuprous oxide ( Cu2 O) was successfully prepared by the method of reduction in aqueous at room temperature.All the powders were characterized by X -rays diffraction ( XRD) and scanning electron microscopy ( SEM) .The effect of different factors on the degradation was investigated .The best reaction conditions were found out.The photocatalytic degradation of rhodamine B by Cu 2 O under simulated natural light irradiation was investiga-ted.The results demonstrated that initial concentration of rhodamine B is 10 mg/L, catalyst dosage is 0.38 g/L and the pH is 5.2, the degradation ratio of rhodamine B is as high as 96.5%after 30 minutes simulated natural light ir-radiation .%利用室温液相还原法制备了氧化亚铜,通过XRD、 SEM对其进行了表征,探讨了该催化剂对罗丹明B的光催化降解的活性。在催化剂用量为0.38 g/L,过氧化氢量为1.8 mL,罗丹明B的浓度为10 mg/L, pH为5.2的条件下,光照30 min后罗丹明B的降解率为96.5%。

  13. 21 CFR 184.1265 - Cuprous iodide.

    Science.gov (United States)

    2010-04-01

    ... with potassium iodide under slightly acidic conditions. (b) The ingredient must be of a purity suitable... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Cuprous iodide. 184.1265 Section 184.1265 Food and... Substances Affirmed as GRAS § 184.1265 Cuprous iodide. (a) Cuprous iodide (copper (I) iodide, CuI, CAS...

  14. Nanometer-Thick Gold on Silicon as a Proxy for Single-Crystal Gold for the Electrodeposition of Epitaxial Cuprous Oxide Thin Films.

    Science.gov (United States)

    Switzer, Jay A; Hill, James C; Mahenderkar, Naveen K; Liu, Ying-Chau

    2016-06-22

    Single-crystal Au is an excellent substrate for electrochemical epitaxial growth due to its chemical inertness, but the high cost of bulk Au single crystals prohibits their use in practical applications. Here, we show that ultrathin epitaxial films of Au electrodeposited onto Si(111), Si(100), and Si(110) wafers can serve as an inexpensive proxy for bulk single-crystal Au for the deposition of epitaxial films of cuprous oxide (Cu2O). The Au films range in thickness from 7.7 nm for a film deposited for 5 min to 28.3 nm for a film deposited for 30 min. The film thicknesses are measured by low-angle X-ray reflectivity and X-ray Laue oscillations. High-resolution TEM shows that there is not an interfacial SiOx layer between the Si and Au. The Au films deposited on the Si(111) substrates are smoother and have lower mosaic spread than those deposited onto Si(100) and Si(110). The mosaic spread of the Au(111) layer on Si(111) is only 0.15° for a 28.3 nm thick film. Au films deposited onto degenerate Si(111) exhibit ohmic behavior, whereas Au films deposited onto n-type Si(111) with a resistivity of 1.15 Ω·cm are rectifying with a barrier height of 0.85 eV. The Au and the Cu2O follow the out-of-plane and in-plane orientations of the Si substrates, as determined by X-ray pole figures. The Au and Cu2O films deposited on Si(100) and Si(110) are both twinned. The films grown on Si(100) have twins with a [221] orientation, and the films grown on Si(110) have twins with a [411] orientation. An interface model is proposed for all Si orientations, in which the -24.9% mismatch for the Au/Si system is reduced to only +0.13% by a coincident site lattice in which 4 unit meshes of Au coincide with 3 unit meshes of Si. Although this study only considers the deposition of epitaxial Cu2O films on electrodeposited Au/Si, the thin Au films should serve as high-quality substrates for the deposition of a wide variety of epitaxial materials.

  15. Preparation and Instability of Nanocrystalline Cuprous Nitride.

    Science.gov (United States)

    Reichert, Malinda D; White, Miles A; Thompson, Michelle J; Miller, Gordon J; Vela, Javier

    2015-07-06

    Low-dimensional cuprous nitride (Cu3N) was synthesized by nitridation (ammonolysis) of cuprous oxide (Cu2O) nanocrystals using either ammonia (NH3) or urea (H2NCONH2) as the nitrogen source. The resulting nanocrystalline Cu3N spontaneously decomposes to nanocrystalline CuO in the presence of both water and oxygen from air at room temperature. Ammonia was produced in 60% chemical yield during Cu3N decomposition, as measured using the colorimetric indophenol method. Because Cu3N decomposition requires H2O and produces substoichiometric amounts of NH3, we conclude that this reaction proceeds through a complex stoichiometry that involves the concomitant release of both N2 and NH3. This is a thermodynamically unfavorable outcome, strongly indicating that H2O (and thus NH3 production) facilitate the kinetics of the reaction by lowering the energy barrier for Cu3N decomposition. The three different Cu2O, Cu3N, and CuO nanocrystalline phases were characterized by a combination of optical absorption, powder X-ray diffraction, transmission electron microscopy, and electronic density of states obtained from electronic structure calculations on the bulk solids. The relative ease of interconversion between these interesting and inexpensive materials bears possible implications for catalytic and optoelectronic applications.

  16. A facile one-pot oxidation-assisted dealloying protocol to massively synthesize monolithic core-shell architectured nanoporous copper@cuprous oxide nanonetworks for photodegradation of methyl orange

    Science.gov (United States)

    Liu, Wenbo; Chen, Long; Dong, Xin; Yan, Jiazhen; Li, Ning; Shi, Sanqiang; Zhang, Shichao

    2016-11-01

    In this report, a facile and effective one-pot oxidation-assisted dealloying protocol has been developed to massively synthesize monolithic core-shell architectured nanoporous copper@cuprous oxide nanonetworks (C-S NPC@Cu2O NNs) by chemical dealloying of melt-spun Al 37 at.% Cu alloy in an oxygen-rich alkaline solution at room temperature, which possesses superior photocatalytic activity towards photodegradation of methyl orange (MO). The experimental results show that the as-prepared nanocomposite exhibits an open, bicontinuous interpenetrating ligament-pore structure with length scales of 20 ± 5 nm, in which the ligaments comprising Cu and Cu2O are typical of core-shell architecture with uniform shell thickness of ca. 3.5 nm. The photodegradation experiments of C-S NPC@Cu2O NNs show their superior photocatalytic activities for the MO degradation under visible light irradiation with degradation rate as high as 6.67 mg min-1 gcat-1, which is a diffusion-controlled kinetic process in essence in light of the good linear correlation between photodegradation ratio and square root of irradiation time. The excellent photocatalytic activity can be ascribed to the synergistic effects between unique core-shell architecture and 3D nanoporous network with high specific surface area and fast mass transfer channel, indicating that the C-S NPC@Cu2O NNs will be a promising candidate for photocatalysts of MO degradation.

  17. Sensitivity of cuprous azide towards heat and impact

    Directory of Open Access Journals (Sweden)

    Kartar Singh

    1958-07-01

    Full Text Available "Rates of thermal decomposition of azide at six different temperatures have been measured. The sigmoid shapes of the curves representing increase in pressure with time suggest that a given temperature a fixed number of nuclei are formed at the end of the induction period. The nuclei increase in size in three dimensions. The radius of any nucleus at any instant (tis directly proportional to (t-t/Sub/owhere t/Sub/o is the induction period. The activation energy involved in thermal has been found decomposition to be 26.5K calories. It is suggested that this activation energy corresponds to the energy required for thermal transition of an electron 3 d band to the Fermi level of the metallic copper nuclei. The impact sensitivity and induction period necessary for explosion at various temperatures for crystalline and precipitated samples of cuprous azide have been measured. The results indicate that cuprous azide is more sensitive towards heat and impact than lead azide. The impact sensitivity of cuprous azide is found to increase in crystal size."

  18. Modification of metal/oxide interfaces by dissolution of Sb in oxide precipitates containing metal matrices

    NARCIS (Netherlands)

    Kooi, BJ; Westers, AR; Vreeling, JA; van Agterveld, DTL; De Hosson, JTM; Lejcek, P; Paidar,

    1999-01-01

    The influence of dissolution of a segregating element (Sb) in a metal matrix in which oxide precipitates are present on the precipitate morphology and the interface structure is studied using HRTEM. The influence on Mn3O4 precipitates in Ag is distinct: (i) the initial precipitates, sharply facetted

  19. 氧化锌/氧化亚铜异质结太阳能电池的研究进展∗%Research Progress in Zinc Oxide/Cuprous Oxide Heterojunction Solar Cell

    Institute of Scientific and Technical Information of China (English)

    冯云珠; 董磊; 于良民

    2015-01-01

    Much attention recently has been paid on p-n heterojunction solar cells fabricated with cuprous oxide combined with zinc oxide owing to the advantage of favorable alignment of conductive band edges and lattice matching. The formation of heterojunctions can enhance the seperation of photoinduced electrons and holes,as well as the absor-bance of the light.This review compiles the main milestones reached during the last decades in the development of ZnO/Cu2 O heterojunction solar cells comprehensively.Different junction structures of these cells as planar and ZnO nanoarray based ones related to deposition sequences and synthesis methods are introduced separately,while photovol-taic property influence factors as well as improving methods are discussed.Considering the accomplishments achieved in a relatively short period of time,it can be said that this kind of solar cell can be promisingly applied in clean energy exploitation in the future,in spite of improvement of cell performance still in need.%因氧化亚铜(Cu2 O)、氧化锌(ZnO)能级和晶格匹配较好,近年来较多的研究者将两者复合制备异质结太阳能电池。异质结的形成可提高光生电子-空穴对的分离效率,同时拓展复合结构的光响应范围,从而有效提高太阳能电池性能。介绍了3类主流的 ZnO/Cu2 O 异质结结构,分别阐述主要的进展,综述了异质结结构中 Cu2 O、ZnO的制备方法以及制备条件对电池效率的影响,讨论了电池性能的改进措施,并对 ZnO/Cu2 O 异质结太阳能电池未来的发展前景进行展望。

  20. Neptunium_Oxide_Precipitation_Kinetics_AJohnsen

    Energy Technology Data Exchange (ETDEWEB)

    Johnsen, A M; Roberts, K E; Prussin, S G

    2012-06-08

    We evaluate the proposed NpO{sub 2}{sup +}(aq)-NpO{sub 2}(cr) reduction-precipitation system at elevated temperatures to obtain primary information on the effects of temperature, ionic strength, O{sub 2} and CO{sub 2}. Experiments conducted on unfiltered solutions at 10{sup -4} M NpO{sub 2}{sup +}(aq), neutral pH, and 200 C indicated that solution colloids strongly affect precipitation kinetics. Subsequent experiments on filtered solutions at 200, 212, and 225 C showed consistent and distinctive temperature-dependent behavior at reaction times {le} 800 hours. At longer times, the 200 C experiments showed unexpected dissolution of neptunium solids, but experiments at 212 C and 225 C demonstrated quasi steady-state neptunium concentrations of 3 x 10{sup -6} M and 6 x 10{sup -6} M, respectively. Solids from a representative experiment analyzed by X-ray diffraction were consistent with NpO{sub 2}(cr). A 200 C experiment with a NaCl concentration of 0.05 M showed a dramatic increase in the rate of neptunium loss. A 200 C experiment in an argon atmosphere resulted in nearly complete loss of aqueous neptunium. Previously proposed NpO{sub 2}{sup +}(aq)-NpO{sub 2}(cr) reduction-precipitation mechanisms in the literature specified a 1:1 ratio of neptunium loss and H{sup +} production in solution over time. However, all experiments demonstrated ratios of approximately 0.4 to 0.5. Carbonate equilibria can account for only about 40% of this discrepancy, leaving an unexpected deficit in H+ production that suggests that additional chemical processes are occurring.

  1. Formation of copper oxychloride and reactive oxygen species as causes of uterine injury during copper oxidation of Cu-IUD.

    Science.gov (United States)

    Beltran-Garcia, M J; Espinosa, A; Herrera, N; Perez-Zapata, A J; Beltran-Garcia, C; Ogura, T

    2000-02-01

    The lining of the uterus and cervix might be injured by a variety of oxidation products of Cu in a Cu-IUD, including cuprous ions, dissolved and precipitated cupric ions, and reactive oxygen species such as superoxide radicals, hydrogen peroxide, and hydroxyl radicals. In this study, the human amnious WISH cell line was employed as a model of uterine cells in the presence of copper. The cell viability was decreased by elemental copper, which was alleviated up to 70% by the addition of catalase. The addition of copper oxychloride caused cell death in a dose-dependent manner. Hydroxyl radicals in the presence of copper were determined by the formation of malondialdehyde. Soluble cuprous chloride complexes are formed in the uterus by slowly entering oxygen. The complexes are partly oxidized to insoluble copper oxychloride. which damages the endometrium. Unoxidized cuprous ions migrate to the oxygen-rich cervix and are oxidized to copper oxychloride, causing cervix damage.

  2. Preparation of poly(butyl methacrylate-co-ethyleneglyceldimethacrylate) monolithic column modified with β-cyclodextrin and nano-cuprous oxide and its application in polymer monolithic microextraction of polychlorinated biphenyls.

    Science.gov (United States)

    Zheng, Haijiao; Liu, Qingwen; Jia, Qiong

    2014-05-23

    A poly(butyl methacrylate-co-ethyleneglyceldimethacrylate) (poly(BMA-EDMA)) monolithic column was prepared with in situ polymerization method and modified with allylamine-β-cyclodextrin (ALA-β-CD) and nano-cuprous oxide (Cu2O). A polymer monolith microextraction method was developed with the modified monolithic column for the preconcentration of polychlorinated biphenyls combined with gas chromatography-electron capture detector. Various parameters affecting the extraction efficiency were investigated and optimized. Under the optimum experimental conditions, we obtained acceptable linearities, low limits of detection, and good intra-day/inter-day relative standard deviations. Because of the hydrophobic properties of β-CD and the porous nano structure of Cu2O, the enrichment capacity of the poly(BMA-EDMA) monolithic column was significantly improved. The extraction efficiency followed the order: poly(BMA-EDMA-ALA-β-CD-Cu2O)>poly(BMA-EDMA-ALA-β-CD)>poly(BMA-EDMA)>direct GC analysis. When applied to the determination of polychlorinated biphenyls in wine samples, low limits of detection (0.09ngmL(-1)) were obtained under the preoptimized conditions (sample volume 1.0mL, sample flow rate 0.1mLmin(-1), eluent volume 0.1mL, and eluent flow rate 0.05mLmin(-1)). In addition, the present method was employed to determine polychlorinated biphenyls in red wine samples and the accuracy was assessed through recovery experiments. The obtained recovery values were in the range of 78.8-104.1% with relative standard deviations less than 9.0%.

  3. Preparation of Cystein from Cysteine Cuprous Mercaptide%由半胱氨酸亚铜制取半胱氨酸

    Institute of Scientific and Technical Information of China (English)

    刘勋; 胡敏; 姚小平

    2015-01-01

    In this paper ,a new preparation method of cysteine hydrochloride monohydrate from cysteine cu‐prous mcercaptide ,which is prepared by the reduction and precipitation of cystine with cuprous oxide has been introduced ,including re‐precipitation of cysteine cuprous mercaptide ,removal of copper using H2 S , decoloration ,crystallization and recrystalization .The yield of the product is up to 12 .4% ,with the quality according with the Japanese AJI standards .%研究了一种用氧化亚铜将胱氨酸还原沉淀为半胱氨酸亚铜,再由此制备半胱氨酸盐酸盐一水物的新方法.该方法包含半胱氨酸亚铜再沉淀,H2 S法脱铜,脱色,产品结晶,重结晶等步骤,半胱氨酸盐酸盐一水物收率达12.4%,产品质量符合日本味之素标准.

  4. Helium trapping at erbium oxide precipitates in erbium hydride

    Energy Technology Data Exchange (ETDEWEB)

    Foiles, Stephen M. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Battaile, Corbett Chandler [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2016-02-01

    The formation of He bubbles in erbium tritides is a significant process in the aging of these materials. Due to the long-standing uncertainty about the initial nucleation process of these bubbles, there is interest in mechanisms that can lead to the localization of He in erbium hydrides. Previous work has been unable to identify nucleation sites in homogeneous erbium hydride. This work builds on the experimental observation that erbium hydrides have nano- scale erbium oxide precipitates due to the high thermodynamic stability of erbium oxide and the ubiquitous presence of oxygen during materials processing. Fundamental DFT calculations indicate that the He is energetically favored in the oxide relative to the bulk hydride. Activation energies for the motion of He in the oxide and at the oxide-hydride interface indicate that trapping is kinetically feasible. A simple kinetic Monte Carlo model is developed that demonstrates the degree of trapping of He as a function of temperature and oxide fraction.

  5. When do oxide precipitates form during consolidation of oxide dispersion strengthened steels?

    Science.gov (United States)

    Deschamps, A.; De Geuser, F.; Malaplate, J.; Sornin, D.

    2016-12-01

    The processing of oxide dispersion strengthened (ODS) steels involves ball milling, where the oxide forming species are driven in solid solution. Precipitation of the nanometre-scale oxides occurs during subsequent annealing and consolidation. This paper reports in-situ Small-Angle X-ray Scattering measurements of the formation of these precipitates during heating of cold-compressed as-milled powders. Clusters are already initially present, and precipitation starts at 300 °C. The maximum precipitate density is achieved at 600 °C, followed by very slow coarsening at higher temperature. These results open the way to understand the coupled evolution of precipitation and crystalline defects during heating and consolidation of ODS steels.

  6. Precipitation of metal oxide nanoparticles using a miniemulsion technique

    Institute of Scientific and Technical Information of China (English)

    Marion Winkelmann; Heike Petra Schuchmann

    2011-01-01

    A method to precipitate nanoparticles using a miniemulsion technique is described,in which miniemulsion droplets between 100 and 1000 nm in size serve as nanoreactors enabling both the control of particle formation and particle growth.The application ofminiemulsion droplets to synthesise nanoparticles comprises three advantages:first,the size of the precipitated particles is limited by the reactant concentration within the emulsion droplet; second,particle agglomeration is prevented as nanoparticle collision outside the nanoreactor is avoided; and third,easy technical scale up can be realized by increasing emulsion volume and thus the number of nanoreactors,while local conditions within the reactors are not changed.The miniemulsion technique is an easy scalable process which allows defined synthesis of particles by precipitation reactions.The miniemulsion technique involves first the preparation of a stable water-inoil miniemulsion by high pressure homogenisation.Whereas a water soluble reactant is provided within the aqueous droplets,another oil- as well as water-soluble reactant can be introduced to the emulsion after homogenisation.The precipitation reaction is induced by the diffusion of the second reactant into the emulsion droplet.Together with this contribution,a method is described and discussed which uses a high pressure homogenisation process to produce stable water-in-oil miniemulsions serving as a reaction medium to precipitate metal oxides.

  7. The effects of auroral precipitation on atmospheric nitric oxide concentration

    Science.gov (United States)

    Jones, S.; Lessard, M.; Fritz, B.

    2016-12-01

    The Pulsating Auroral Nitric Oxide Production in the Lower Ionosphere (PANOPLI) project addresses a science problem that has strong implications regarding the question of how solar variability may be related to climate change and terrestrial weather. Pulsating aurora is the ideal choice for studying auroral NO production since this type of aurora is caused by tens of keV electron precipitation (which is known to produce enhancements in thermospheric NO) and is a frequently occurring and long lasting phenomenon resulting in widespread auroral luminosity. The pulsating auroral precipitation results in a large transfer of power from the magnetosphere to the ionosphere-thermosphere and may be a significant contributor to thermospheric NO production, which is dependent on the energy flux and duration of the auroral precipitation. PANOPLI makes use of ground-based riometer measurements to characterize the electron precipitation causing pulsating aurora and determine the effects of pulsating aurora on the theremosphere-mesosphere NO reservoir. The inferred precipitating electron distribution function is input to a model to calculate the expected NO enhancement for comparison with NO enhancements inferred from ground-based Fabry-Perot interferometer measurements. This problem is particularly important because NO produced at low enough altitudes can transport downward to the stratosphere and chemically react with ozone causing depletion. Therefore, this work is a vital first step in quantifying the auroral contribution to ozone depletion. Previous studies have shown that the auroral contribution to atmospheric chemistry can be significant, with up to 60% of ozone depletion enhancements (above background levels) at 35-40 km altitude due to energetic electron precipitation (Randall et al., 2005).

  8. Effects of lithium (Li) on lithium-cuprous-oxide (Li-Cu2O) composite films grown by using electrochemical deposition for a PEC photoelectrode

    Science.gov (United States)

    Kim, Tae Gyoum; Ryu, Hyukhyun; Lee, Won-Jae

    2016-01-01

    In this study, Li-Cu2O composite films were grown on fluorine-doped tin-oxide (FTO) substrates by using the electrochemical deposition method. Various amounts of lithium (Li) were added to grow the Li-Cu2O composite films. We analyzed the morphology, structure, photocurrent density and photo-stability of the Li-Cu2O composite films by using various measurements such as field-emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD) and potentiostat/galvanostat measurements, respectively. As a result, the highest XRD Cu2O (111)/ LiO (011) peak intensity ratio was obtained for the 10-wt% sample, which also had the highest photocurrent density value of -5.00 mA/cm2. The highest photocurrent density value for the 10-wt% sample was approximately 5 times greater than that of the 0-wt% sample. As shown by this result, we found that adding Li could improve the photocurrent values of Li-Cu2O composite films.

  9. Precipitation of Zinc Oxide Nanoparticles in Bicontinuous Microemulsions

    Directory of Open Access Journals (Sweden)

    Liliana E. Romo

    2011-01-01

    Full Text Available Zinc oxide nanoparticles were obtained directly, avoiding the calcination step, by precipitation at 70°C in bicontinuous microemulsions stabilized with a mixture of surfactants sodium bis (2-ethylhexyl sulfosuccinate/sodium dodecyl sulfate (2/1, wt./wt. containing 0.7 M zinc nitrate aqueous solution. Two concentrations of aqueous solution of precipitating agent sodium hydroxide were used under different dosing times on microemulsion. Characterization by X-ray diffraction and electron microscopy allowed us to identify particles with an acicular rod-like morphology and a hexagonal wurtzite crystal structure as small as 8.5 and 30 nm in average diameter and length, respectively. Productivities much higher than those typical in the preparation of zinc oxide nanoparticles via reverse microemulsions were obtained. Particle size was the same at the two studied sodium hydroxide concentrations, while it increases as dosing time of the precipitant agent increases. It is believed that the surfactant film on the microemulsion channels restricts the particle diameter growth.

  10. Memristive Properties of Thin Film Cuprous Oxide

    Science.gov (United States)

    2011-03-01

    Banerjee and D Chakravorty, "Optical absorption by nanoparticles of Cu2O," Europhysics Letters , vol. 52, no. 4, pp. 468-473, November 2000. [20] Gunter...Kotsugi, "Inhomogeneous chemical states in resistance-switching devices with a planar-type Pt/CuO/Pt structure," Applied Physics Letters , vol. 95, p...11] R Dong et al., "Reproducible hysteresis and resistive switching in metal-CuxO- metal," Applied Physics Letters , vol. 90, p. 042107, 2007. [12

  11. Precipitation method and characterization of cobalt oxide nanoparticles

    Science.gov (United States)

    Prabaharan, D. Durai Manoharadoss; Sadaiyandi, K.; Mahendran, M.; Sagadevan, Suresh

    2017-04-01

    Cobalt oxide (Co3O4) nanoparticles were synthesized using precipitation method. The X-ray diffraction (XRD) pattern was used to determine the structure of Co3O4 nanoparticles. The presence of Co3O4 nanoparticles was confirmed by the FTIR spectrum. The fact about the surface morphology of Co3O4 nanoparticles was revealed by scanning electron microscopic analysis. Transmission electron microscopy was used to measure the particle size of the Co3O4 nanoparticles. The absorption spectrum made it possible to analyze the optical properties of Co3O4 nanoparticles. This work contributes to the study of dielectric properties such as the dielectric loss and the dielectric constant of Co3O4 nanoparticles, at varied frequencies and temperatures. The magnetic properties of the Co3O4 nanoparticles were also investigated.

  12. The fictile coordination chemistry of cuprous-thiolate sites in copper chaperones.

    Science.gov (United States)

    Pushie, M Jake; Zhang, Limei; Pickering, Ingrid J; George, Graham N

    2012-06-01

    Copper plays vital roles in the active sites of cytochrome oxidase and in several other enzymes essential for human health. Copper is also highly toxic when dysregulated; because of this an elaborate array of accessory proteins have evolved which act as intracellular carriers or chaperones for the copper ions. In most cases chaperones transport cuprous copper. This review discusses some of the chemistry of these copper sites, with a view to some of the structural factors in copper coordination which are important in the biological function of these chaperones. The coordination chemistry and accessible geometries of the cuprous oxidation state are remarkably plastic and we discuss how this may relate to biological function. This article is part of a Special Issue entitled: Biogenesis/Assembly of Respiratory Enzyme Complexes.

  13. Uranium co-precipitation with iron oxide minerals

    Science.gov (United States)

    Duff, Martine C.; Coughlin, Jessica Urbanik; Hunter, Douglas B.

    2002-10-01

    In oxidizing environments, the toxic and radioactive element uranium (U) is most soluble and mobile in the hexavalent oxidation state. Sorption of U(VI) on Fe-oxides minerals (such as hematite [α-Fe 2O 3] and goethite [α-FeOOH]) and occlusion of U(VI) by Fe-oxide coatings are processes that can retard U transport in environments. In aged U-contaminated geologic materials, the transport and the biological availability of U toward reduction may be limited by coprecipitation with Fe-oxide minerals. These processes also affect the biological availability of U(VI) species toward reduction and precipitation as the less soluble U(IV) species by metal-reducing bacteria. To examine the dynamics of interactions between U(VI) and Fe oxides during crystallization, Fe-oxide phases (containing 0.5 to 5.4 mol% U/(U + Fe)) were synthesized by means of solutions of U(VI) and Fe(III). Wet chemical (digestions and chemical extractions) and spectroscopic techniques were used to characterize the synthesized Fe oxide coprecipitates after rinsing in deionized water. Leaching the high mol% U solids with concentrated carbonate solution (for sorbed and solid-phase U(VI) species) typically removed most of the U, leaving, on average, about 0.6 mol% U. Oxalate leaching of solids with low mol% U contents (about 1 mol% U or less) indicated that almost all of the Fe in these solids was crystalline and that most of the U was associated with these crystalline Fe oxides. X-ray diffraction and Fourier-transform infrared (FT-IR) spectroscopic studies indicate that hematite formation is preferred over that of goethite when the amount of U in the Fe-oxides exceeds 1 mol% U (˜4 wt% U). FT-IR and room temperature continuous wave luminescence spectroscopic studies with unleached U/Fe solids indicate a relationship between the mol% U in the Fe oxide and the intensity or existence of the spectra features that can be assigned to UO 22+ species (such as the IR asymmetric υ 3 stretch for O = U = O for

  14. Formation and Thermal Stability of Large Precipitates and Oxides in Titanium and Niobium Microalloyed Steel

    Institute of Scientific and Technical Information of China (English)

    ZHUO Xiao-jun; WOO Dae-hee; WANG Xin-hua; LEE Hae-geon

    2008-01-01

    As-cast CC slabs of microalloyed steels are prone to surface and sub-surface cracking. Precipitation phenomena in-itiated during solidification reduce ductility at high temperature. The unidirectional solidification unit is employed to sim-ulate the solidification process during continuous casting. Precipitation behavior and thermal stability are systemati-cally investigated. Samples of adding titanium and niobium to steels have been examined using field emission scanning electron microscope (FE-SEM), electron probe X-ray microanalyzer (EPMA), and transmission electron microscope (TEM). It has been found that the addition of titanium and niobium to high-strength low-alloyed (HSLA) steel resuited in undesirable large precipitation in the steels, i. e. , precipitation of large precipitates with various morphologies. The composition of the large precipitates has been determined. The effect of cooling rate on (Ti, Nb)(C, N) precipitate formation is investigated. With increasing the cooling rate, titanium-rich (Ti,Nb)(C, N) precipitates are transformed to niobium-rich (Ti,Nb)(C,N) precipitates. The thermal stability of these large precipitates and oxides have been assessed by carrying out various heat treatments such as holding and quenching from temperature at 800 and 1 200 ℃. It has been found that titanium-rich (Ti,Nb)(C,N) precipitate is stable at about 1 200 ℃ and niobi-um-rich (Ti,Nb)(C,N) precipitate is stable at about 800 ℃. After reheating at 1 200 ℃ for 1 h, (Ca, Mn)S and TiN are precipitated from Ca-Al oxide. However, during reheating at 800 ℃ for 1 h, Ca-Al-Ti oxide in specimens was stable. The thermodynamic calculation of simulating the thermal process is employed. The calculation results are in good agreement with the experimental results.

  15. Isothermal precipitation and growth process of perovskite phase in oxidized titanium bearing slag

    Institute of Scientific and Technical Information of China (English)

    WANG Ming-yu; WANG Xue-wen; HE Yue-hui; LOU Tai-ping; SUI Zhi-tong

    2008-01-01

    The isothermal precipitating behavior of perovskite phase in oxidized titanium bearing slag was studied by quenching method. The kinetics of precipitating process and crystal growth of perovskite phase was analyzed. The results show that the precipitating and growth of perovskite are non-equilibrium process at the beginning of isothermal treatment. There are two factors influencing the growth rate of perovskite phase on non-equilibrium condition, one is the supersaturation concentration of perovskite and the other is the coarsening arising from the growth of larger perovskite at the expense of smaller ones. The precipitation kinetics of perovskite phase can be nearly described by the JMAK equation.

  16. Oxidation and Precipitation of Sulfide in Sewer Networks

    DEFF Research Database (Denmark)

    Nielsen, A. H.

    were studied in both wastewater and biofilms. Particular emphasis was on the importance of iron in the sulfur cycle. Iron is typically among the dominant metals in wastewater. The experiments showed that, ferric iron (Fe(III)) that was added to anaerobic wastewater was rapidly reduced to ferrous iron...... (Fe(II)) and precipitated subsequently with dissolved sulfide as ferrous sulfide (FeS). The ferrous sulfide precipitation was relatively fast, but not immediate. Despite the very low solubility of ferrous sulfide, initially present iron did not react completely with sulfide. This observation...

  17. Co-Precipitation Synthesis of Gadolinium Aluminum Gallium Oxide (GAGG) via Different Precipitants

    Science.gov (United States)

    Sun, Yan; Yang, Shenghui; Zhang, Ye; Jiang, Jun; Jiang, Haochuan

    2014-02-01

    In order to obtain a uniform transparent ceramic scintillator, well-dispersed fine starting powders with high-purity, small grain size, spherical morphology and high sinter-ability are necessary. In this study, Ce3+ doped gadolinium aluminum gallium garnet Gd3Al3Ga2O12 (GAGG) powders were synthesized by the co-precipitation method. NH4OH, NH4HCO3 and the mixed solution of NH4OH and NH4HCO3 were used as precipitants, respectively. The precursor composition, phase formation process, microstructure, morphology, particle size distribution and luminescent properties of obtained GAGG powders were measured. The results show that powders prepared using the mixed precipitant exhibit the best microstructural morphology, good sinter-ability and highest luminescent intensity. Pure GAGG polycrystalline powders could be obtained at about 950°C for 1.5 h and the average size of the particles is about 50 nm. The photoluminescence spectrum shows a strong green-yellow emission near 540 nm.

  18. Preparation and Characterization of Hydrous Zirconium Oxide Formed by Homogeneous Precipitation

    Directory of Open Access Journals (Sweden)

    Silva G.L.J.P. da

    2002-01-01

    Full Text Available This paper reports on the preparation, characterization and study of the ion exchange behavior of hydrous zirconium oxides formed by homogeneous precipitation from zirconium oxychloride. The precipitants used were obtained by thermal decomposition of urea, sodium nitrite or ammonium carbonate. Seven compounds were prepared and characterized by thermal analysis, X-ray diffractometry and by surface area measurements. Amorphous forms were obtained in each case, a result that agrees with those obtained by conventional gel precipitation methodology. All these materials present surface area values of >148 m².g-1, determined after heat treatment at 50 °C. The ion exchange behavior of each hydrous zirconium oxide prepared was studied using K+ as the exchanged species and the results compared with those obtained for hydrous zirconium oxide originally precipitated by the sol gel method.

  19. Formate oxidation driven calcium carbonate precipitation by Methylocystis parvus OBBP

    NARCIS (Netherlands)

    Ganendra, G; De Muynck, W; Ho, A.; Arvaniti, EC; Hosseinkhani, B; Ramos, JA; Rahier, H; Boon, N.

    2014-01-01

    Microbially Induced Carbonate Precipitation (MICP) applied in the construction industry poses several disadvantages such as ammonia release to the air and nitric acid production. An alternative MICP from calcium formate by Methylocystis parvus OBBP is presented in this study to overcome these disadv

  20. Tin clustering and precipitation in the oxide during autoclave corrosion of Zircaloy-2

    Energy Technology Data Exchange (ETDEWEB)

    Sundell, G., E-mail: gustav.sundell@chalmers.se; Thuvander, M.; Andrén, H.-O.

    2015-01-15

    Atom probe tomography has been used to study the evolution of tin distribution during the corrosion process in Zircaloy-2. From being completely soluble in the Zr metal matrix, some clustering is evident already in the newly formed oxide close to the metal–oxide interface. Analysis of thicker oxides a few hundred nanometers away from the interface reveals fully developed precipitates of metallic Sn particles of up to 20 nm in size. Although the precipitates contain significant amounts of Zr, it is concluded that they are in the process of being depleted in Zr, which is limited only by the slow diffusion in the oxide scale. The findings are interpreted as being a result of the nobility of the Sn yielding a strong driving force to remain in a metallic state after incorporation in the barrier oxide layer. As Sn occupies substitutional sites in the ZrO{sub 2} lattice it is oxidized to a 4+ state when incorporated into the oxide, and in order to remain metallic it must nucleate into precipitates within the inner part of the oxide scale before being re-oxidized to 2+ and eventually to 4+ when the oxygen activity is sufficiently high in the outer parts of the oxide.

  1. Oxidation and Precipitation of Sulfide in Sewer Networks

    DEFF Research Database (Denmark)

    Nielsen, A. H.

    wastewater and biofilms of sewer networks was studied in detail with emphasis on determination of process kinetics and stoichiometry. In the water phase, sulfide oxidation may be both chemical and biological and the investigations showed that both processes were of significant importance in the sulfur cycle...... transformations. The experiments indicated that biological sulfide oxidation in the water phase and sulfide oxidation by sewer biofilms produce elemental sulfur under the conditions investigated. The stoichiometry of chemical sulfide oxidation was apparently more complex producing both thiosulfate and sulfate......-workers at Aalborg University for more than a decade. In the basic version, the WATS model simulates changes in dissolved oxygen (DO) and organic fractions of different biodegradability under both aerobic and anaerobic conditions. Evaluation of the model concept has demonstrated that it can be successfully...

  2. Optimization of thorium oxalate precipitation conditions relative to thorium oxide sinterability

    Energy Technology Data Exchange (ETDEWEB)

    White, G.D.; Bray, L.A.; Hart, P.E.

    1980-01-01

    The effect of thorium oxalate precipitation conditions on derived oxide sinterability was investigated with the objective of producing ThO/sub 2/ powder that could be sintered to high density without premilling. Precipitation conditions examined were temperature, digestion time and agitation method which were employed in a two-level factorial experimental design to delineate their effects. The two levels for each of the factors, respectively, were 10/sup 0/C and 70/sup 0/C, 15 min and 360 min, and mechanical stirrer and a homogenizer that imparted both mechanical and ultrasonic agitation. The ThO/sub 2/ derived from each of the precipitation trials was characterized with respect to morphology, surface area, and crystallite size as well as sinterability. Only precipitation temperature had a significant effect upon all the properties of the derived oxide powders.

  3. Synthesis and Characterization of Large Surface Area Yttrium Oxide by Precipitation Method

    Institute of Scientific and Technical Information of China (English)

    崔大立; 龙志奇; 张顺利; 崔梅生; 黄小卫

    2004-01-01

    The method for preparing yttrium oxide with large specific surface area was introduced. By means of BET, SEM, TG and DTA analysis, the effects of precipitant, stirring velocity, non-RE impurity in solution, calcination temperature, on the surface area were studied respectively. The Y2O3 sample with specific surface area of more than 60 m2*g-1 and L.O.I less than 1% was prepared in the suitable precipitation condition and calcinations temperature when the ammonia used as precipitant. The SEM shows that the Y2O3 prepared with large surface area is the aggregation of about 50 nm particles.

  4. Effects of precipitate aging time on the cerium-zirconium composite oxides

    Institute of Scientific and Technical Information of China (English)

    钟强; 崔梅生; 岳梅; 王琦; 王磊; 郭荣贵; 龙志奇; 黄小卫

    2014-01-01

    Cerium-zirconium composite oxides with high performance were synthesized by a co-precipitation method, using zirco-nium oxychloride and rare earth chloride as raw materials. The effects of precipitate aging time on the properties of cerium-zirconium composite oxides were investigated. The prepared cerium-zirconium composite oxides were characterized by X-ray diffraction (XRD), BET specific surface area, pulsed oxygen chemical adsorption, H2 temperature-programmed-reduction (H2-TPR), scanning electron microscopy (SEM), etc. The results showed that the precipitate aging time caused great effects on the properties of cerium zirconium composite oxides. With the increase of aging time, the cerium zirconium composite oxides showed enhanced specific sur-face area, good thermal stability, and high oxygen storage capacity (OSC). The best performance sample was obtained while the pre-cipitate aging time up to 48 h, with the specific surface area of 140.7 m2/g, and OSC of 657.24μmolO2/g for the fresh sample. Even after thermal aged under 1000 ºC for 4 h, the aged specific surface area was 41.6 m2/g, moreover with a good OSC of 569.9μmolO2/g.

  5. Iron oxide and hydroxide precipitation from ferrous solutions and its relevance to Martian surface mineralogy

    Science.gov (United States)

    Posey-Dowty, J.; Moskowitz, B.; Crerar, D.; Hargraves, R.; Tanenbaum, L.

    1986-01-01

    Experiments were performed to examine if the ubiquitousness of a weak magnetic component in all Martian surface fines tested with the Viking Landers can be attributed to ferric iron precipitation in aqueous solution under oxidizing conditions at neutral pH. Ferrous solutions were mixed in deionized water and various minerals were added to separate liquid samples. The iron-bearing additives included hematite, goethite, magnetite, maghemite, lepidocrocite and potassium bromide blank at varying concentrations. IR spectroscopic scans were made to identify any precipitates resulting from bubbling oxygen throughout the solutions; the magnetic properties of the precipitates were also examined. The data indicated that the lepidocrocite may have been preferentially precipitated, then aged to maghemite. The process would account for the presumed thin residue of maghemite on the present Martian surface, long after abundant liquid water on the Martian surface vanished.

  6. Effect of oxide nanoparticles on structural properties of multiwalled carbon nanotubes

    Science.gov (United States)

    Dhall, Shivani; Jaggi, Neena

    2016-03-01

    A simple chemical precipitation route is reported to partially decorate mutliwalled carbon nanotubes (MWCNTs) with oxide nanoparticles in the present study. X-ray diffraction (XRD), Raman spectroscopy and Scanning electron microscopy (SEM) are used to investigate the structural properties of MWCNTs composite with nickel, cuprous, zinc and tin oxides nanoparticles. Raman analysis confirms that, ZnO nanoparticles attached nanotubes show more ordering of graphene layers as compared to the others because of uniform dispersion of nanoparticles. It is investigated that, adopted route proved helpful to improve the structural properties of the nanotubes.

  7. In-situ formation of complex oxide precipitates during processing of oxide dispersion strengthened ferritic steels

    Energy Technology Data Exchange (ETDEWEB)

    Jayasankar, K., E-mail: jayasankar.met@gmail.com [CSIR-Institute of Minerals & Materials Technology, Bhubaneswar 751013 (India); Pandey, Abhishek [CSIR-Advanced Materials & Processes Research Institute, Bhopal 462026 (India); Mishra, B.K. [CSIR-Institute of Minerals & Materials Technology, Bhubaneswar 751013 (India); Das, Siddhartha [Indian Institute of Technology, Kharagpur 721302 (India)

    2016-01-15

    Highlights: • Use of dual drive planetary ball mill for Bench scale (>1 kg) production. • X-ray diffraction and TEM were used to study transformations during sintering. • HIPped and rolled samples with nearly 99% density successfully produced. - Abstract: In fusion and fission reactor material development, ODS alloys are the most suitable candidate materials due to its high temperature creep properties and irradiation resistance properties. This paper describes the preparation of oxide dispersion strengthened alloy powder in large quantity (>1 kg batch) in dual drive planetary ball mill using pre-alloyed ferrtic steel powder with nano sized Y{sub 2}O{sub 3}. The consolidation of the powders was carried out in hot isostatic press (HIP) followed by hot rolling. 99% of the theoretical density was achieved by this method. The vickers hardness values of pressed and rolled samples were in the range of 380 ± 2HV and 719 ± 2HV, respectively. Samples were further investigated using X-ray diffraction particle size analyzer and electron microscope. Initial increase in particle size with milling was observed showing flattening of the particle. It was found that 5 h of milling time is sufficient to reduce the particle size to achieve the desired size. Transmission electron microscopy analysis of milled ODS steel powder revealed a uniform distribution of combustion synthesized nano-Y{sub 2}O{sub 3} in ferritic steel matrix after a milling time of 5 h. Preliminary results demonstrated suitability of dual drive planetary ball mill for mass production of alloy within a short time due to various kinds of forces acting at a time during milling process. Fine monoclinic Y{sub 2}Si{sub 2}O{sub 7} precipitates were also observed in the steel. This study explains the particle characteristics of nano Y{sub 2}O{sub 3} dispersed ODS powder and formation of nano clusters in ODS ferritic alloy.

  8. Biogenic precipitation of manganese oxides and enrichment of heavy metals at acidic soil pH

    Science.gov (United States)

    Mayanna, Sathish; Peacock, Caroline L.; Schäffner, Franziska; Grawunder, Anja; Merten, Dirk; Kothe, Erika; Büchel, Georg

    2014-05-01

    The precipitation of biogenic Mn oxides at acidic pH is rarely reported and poorly understood, compared to biogenic Mn oxide precipitation at near neutral conditions. Here we identified and investigated the precipitation of biogenic Mn oxides in acidic soil, and studied their role in the retention of heavy metals, at the former uranium mining site of Ronneburg, Germany. The site is characterized by acidic pH, low carbon content and high heavy metal loads including rare earth elements. Specifically, the Mn oxides were present in layers identified by detailed soil profiling and within these layers pH varied from 4.7 to 5.1, Eh varied from 640 to 660 mV and there were enriched total metal contents for Ba, Ni, Co, Cd and Zn in addition to high Mn levels. Using electron microprobe analysis, synchrotron X-ray diffraction and X-ray absorption spectroscopy, we identified poorly crystalline birnessite (δ-MnO2) as the dominant Mn oxide in the Mn layers, present as coatings covering and cementing quartz grains. With geochemical modelling we found that the environmental conditions at the site were not favourable for chemical oxidation of Mn(II), and thus we performed 16S rDNA sequencing to isolate the bacterial strains present in the Mn layers. Bacterial phyla present in the Mn layers belonged to Firmicutes, Actinobacteria and Proteobacteria, and from these phyla we isolated six strains of Mn(II) oxidizing bacteria and confirmed their ability to oxidise Mn(II) in the laboratory. The biogenic Mn oxide layers act as a sink for metals and the bioavailability of these metals was much lower in the Mn layers than in adjacent layers, reflecting their preferential sorption to the biogenic Mn oxide. In this presentation we will report our findings, concluding that the formation of natural biogenic poorly crystalline birnessite can occur at acidic pH, resulting in the formation of a biogeochemical barrier which, in turn, can control the mobility and bioavailability of heavy metals in

  9. 纳米Cu2O及其复合物的制备及光催化性能研究%Preparation and Photocatalytic Property of Nano Cuprous Oxide and Its Composites

    Institute of Scientific and Technical Information of China (English)

    胥桂萍; 邱黎

    2013-01-01

    Cu2O powders and TiO2-Cu2O composite powders were prepared by chemical deposi-tion method. With prepared Cu2O nanoparticles as photocatalyst,photocatalytic oxidation degrada-tion of methylene blue solution was explored. The effects of dosage of H2O2,the initial concentration of methylene blue and composite samples on the degradation performance were investigated with UV-visible spectrophotometer. The results showed that the degradation efficiency was the best when the amount of H2O2 was 5mL in 30mL methylene blue solution and the initial concentration of methy-lene blue was 10mg/L,and the catalytic efficiency of TiO2-Cu2O composite powders was much high-er than that of Cu2O.%采用化学沉积法制备Cu2O粉体,并且制备了TiO2-Cu2O复合粉体。以制备的纳米Cu2O为光催化剂,对亚甲基蓝溶液进行光催化氧化降解。通过紫外-可见分光光度计考察了H2O2的加入量、亚甲基蓝的初始浓度及复合样品对降解性能的影响。结果表明,当H2O2的用量在5 mL/30 mL,亚甲基蓝的初始浓度为10 mg/L时降解效果最好;复合粉体的催化效率远高于Cu2O的光催化效率。

  10. Evaluation of Co-precipitation Processes for the Synthesis of Mixed-Oxide Fuel Feedstock Materials

    Energy Technology Data Exchange (ETDEWEB)

    Collins, Emory D [ORNL; Voit, Stewart L [ORNL; Vedder, Raymond James [ORNL

    2011-06-01

    The focus of this report is the evaluation of various co-precipitation processes for use in the synthesis of mixed oxide feedstock powders for the Ceramic Fuels Technology Area within the Fuels Cycle R&D (FCR&D) Program's Advanced Fuels Campaign. The evaluation will include a comparison with standard mechanical mixing of dry powders and as well as other co-conversion methods. The end result will be the down selection of a preferred sequence of co-precipitation process for the preparation of nuclear fuel feedstock materials to be used for comparison with other feedstock preparation methods. A review of the literature was done to identify potential nitrate-to-oxide co-conversion processes which have been applied to mixtures of uranium and plutonium to achieve recycle fuel homogeneity. Recent studies have begun to study the options for co-converting all of the plutonium and neptunium recovered from used nuclear fuels, together with appropriate portions of recovered uranium to produce the desired mixed oxide recycle fuel. The addition of recycled uranium will help reduce the safeguard attractiveness level and improve proliferation resistance of the recycled fuel. The inclusion of neptunium is primarily driven by its chemical similarity to plutonium, thus enabling a simple quick path to recycle. For recycle fuel to thermal-spectrum light water reactors (LWRs), the uranium concentration can be {approx}90% (wt.), and for fast spectrum reactors, the uranium concentration can typically exceed 70% (wt.). However, some of the co-conversion/recycle fuel fabrication processes being developed utilize a two-step process to reach the desired uranium concentration. In these processes, a 50-50 'master-mix' MOX powder is produced by the co-conversion process, and the uranium concentration is adjusted to the desired level for MOX fuel recycle by powder blending (milling) the 'master-mix' with depleted uranium oxide. In general, parameters that must be

  11. Synthesis of cerium oxide (CeO{sub 2}) nanoparticles using simple CO-precipitation method

    Energy Technology Data Exchange (ETDEWEB)

    Farahmandjou, M.; Zarinkamar, M.; Firoozabadi, T. P., E-mail: farahamndjou@iauvaramin.ac.ir [Islamis Azad University, Varamin-Phisva Branch, Department of Physics, Varamin (Iran, Islamic Republic of)

    2016-11-01

    Synthesis of cerium oxide (CeO{sub 2}) nanoparticles was studied by new and simple co-precipitation method. The cerium oxide nanoparticles were synthesized using cerium nitrate and potassium carbonate precursors. Their physicochemical properties were characterized by high resolution transmission electron microscopy (HRTEM), scanning electron microscopy (Sem), X-ray diffraction (XRD), energy dispersive spectroscopy (EDS), Fourier transform infrared spectroscopy (Ftir) and UV-Vis spectrophotometer. XRD pattern showed the cubic structure of the cerium oxide nanoparticles. The average particle size of CeO{sub 2} was around 20 nm as estimated by XRD technique and direct HRTEM observations. The surface morphological studies from Sem and Tem depicted spherical particles with formation of clusters. The sharp peaks in Ftir spectrum determined the existence of CeO{sub 2} stretching mode and the absorbance peak of UV-Vis spectrum showed the bandgap energy of 3.26 eV. (Author)

  12. Synthesis of Tin Oxide/Carbon Nanotube Composite by Homogeneous Precipitation and Characterizations

    Science.gov (United States)

    Xie, Jining; Varadan, Vijay K.

    2004-07-01

    Nanosized tin oxide particles have shown excellent performance when used as anode material in lithium ion batteries. To further improve their electrochemical properties, functionalized carbon nanotubes were introduced during the homogenous precipitation synthesis. Various material characterization techniques such as XRD, SEM, TEM, TGA and BET were performed to check their crystalline, micro- and nano-structure, thermal stability and surface area. Compared with blank tin oxide nanoparticles, much finer tin oxide nanoparticles with higher surface area were observed with the presence of functional carbon nanotubes. It is proposed that functional carbon nanotubes play an important role for nanoparticles' nucleation, growth, coagulation processes. The potential application of this composite in lithium ion batteries is discussed.

  13. Synthesis and characterization of gold nanoparticles supported on zinc oxide via the deposition-precipitation method

    OpenAIRE

    Yazid, Hanani; Adnan, Rohana; HAMID, Shafida Abdul; Farrukh, Muhammad Akhyar

    2010-01-01

    Gold nanoparticles supported on zinc oxide nanoparticles were synthesized at several pH levels via the deposition-precipitation (DP) method. The effects of pH on gold loading, particle size, and particle size distribution on the support were studied at the iso-electric point (IEP) as well as below and above the IEP of ZnO. The addition of the support significantly changed the pH of the solution. The effects of adjusting the pH before and after the addition of the support into the gol...

  14. Synthesis, Characterization of Nano Tin Oxide via Co-precipitation Method

    Directory of Open Access Journals (Sweden)

    K. Sujatha

    2016-09-01

    Full Text Available Pure SnO2 nano powders were synthesized by co-precipitation method. The structure, surface, optical, and functional groups were analyzed by X-ray diffraction, FESEM, UV-Vis spectroscopy, FTIR and fluorescence spectra, respectively. The results were compared with pure tin oxide nanoparticle. X-ray analysis shows that the obtained power has tetragonal rutile structure with average crystallite size of 34 nm. Band gap is observed from UV-Vis spectroscopy. Fluorescence spectrum of pure sample detected a strong emission peaks at 634nm due to surface defect and oxygen vacancies in SnO2 nanoparticles.

  15. Defect engineering of the electronic transport through cuprous oxide interlayers

    KAUST Repository

    Fadlallah, Mohamed M.

    2016-06-03

    The electronic transport through Au–(Cu2O)n–Au junctions is investigated using first-principles calculations and the nonequilibrium Green’s function method. The effect of varying the thickness (i.e., n) is studied as well as that of point defects and anion substitution. For all Cu2O thicknesses the conductance is more enhanced by bulk-like (in contrast to near-interface) defects, with the exception of O vacancies and Cl substitutional defects. A similar transmission behavior results from Cu deficiency and N substitution, as well as from Cl substitution and N interstitials for thick Cu2O junctions. In agreement with recent experimental observations, it is found that N and Cl doping enhances the conductance. A Frenkel defect, i.e., a superposition of an O interstitial and O substitutional defect, leads to a remarkably high conductance. From the analysis of the defect formation energies, Cu vacancies are found to be particularly stable, in agreement with earlier experimental and theoretical work.

  16. Carbon nanotube-cuprous oxide composite based pressure sensors

    Institute of Scientific and Technical Information of China (English)

    Kh. S. Karimov; Muhammad Tariq Saeed Chani; Fazal Ahmad Khalid; Adam Khan; Rahim Khan

    2012-01-01

    In this paper,we present the design,the fabrication,and the experimental results of carbon nanotube (CNT) and Cu2O composite based pressure sensors.The pressed tablets of the CNT-Cu2O composite are fabricated at a pressure of 353 MPa.The diameters of the multiwalled nanotubes (MWNTs) are between 10 nm and 30 nm.The sizes of the Cu2O micro particles are in the range of 3-4 μrn.The average diameter and the average thickness of the pressed tablets are 10 mm and 4.0 mm,respectively.In order to make low resistance electric contacts,the two sides of the pressed tablet are covered by silver pastes.The direct current resistance of the pressure sensor decreases by 3.3 times as the pressure increases up to 37 kN/m2.The simulation result of the resistance-pressure relationship is in good agreement with the experimental result within a variation of ±2%.

  17. Investigation of ionic conductivity of lanthanum cerium oxide nano crystalline powder synthesized by co precipitation method

    Science.gov (United States)

    Tinwala, Hozefa; Shah, Patij; Siddhapara, Kirit; Shah, Dimple; Menghani, Jyoti

    2016-10-01

    Lanthanum (La) doped Ceria (CeO2) electrolyte has attracted considerable interest, as a candidate material for solid oxide fuel cells (SOFCs). The ionic conductivity of La doped CeO2 system (La2Ce2O7) nano-particles synthesized by the co-precipitation method has been investigated. The cubic fluorite structure was observed from the structural analysis of the material. Morphology of the sintered pellets are observed by scanning electron microscope (SEM), respectively. From the results of impedance spectroscopy from temperature range of room temperature to 400 °C, the oxide ion conductivity due to proton charge carrier was observed. Thermogravimetric analysis (TGA) was performed on the material to check stability of phase at high temperature.

  18. Structural characterization of mixed uranium-plutonium co-precipitates and oxides synthesized by oxalic co-conversion route

    Energy Technology Data Exchange (ETDEWEB)

    Arab-Chapelet, B.; De Bruycker, F.; Picart, S.; Leturcq, G.; Grandjean, S. [Laboratoire de Chimie des Actinides, CEA Valrho, bat 399, BP17171, 30207 Bagnols sur Ceze cedex (France)

    2008-07-01

    In this study, mixed uranium(IV)-plutonium(III) oxalate co-precipitates with Pu/(U+Pu) molar ratio equal to 29 and 45% were synthesized and characterized by X-ray powder diffraction (XRD) and Scanning Electron Microscopy (SEM). The thermal conversion step of these co-precipitates into oxide was carried out under argon flow up to 700 deg. C leading to mixed oxides. The structural investigation on these oxides indicates the formation of (U,Pu)O{sub 2} fluorite-type solid solution characterized by a very homogeneous distribution of plutonium and uranium, a controlled oxygen stoichiometry and well-defined morphology of particles. (authors)

  19. Corrosion resistance and calcium–phosphorus precipitation of micro-arc oxidized magnesium for biomedical applications

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Lichen; Cui, Chunxiang, E-mail: hutcui@hebut.edu.cn; Wang, Xin; Liu, Shuangjin; Bu, Shaojing; Wang, Qingzhou; Qi, Yumin

    2015-03-01

    Highlights: • Hydroxyapatite (HA) powders were added to the electrolyte. • The HA powders have participated in the formation reactions of MAO coating. • The growth efficiency of MAO coating was greatly enhanced owing to the HA addition. • The specimen anodized in the HA-containing electrolyte has a better corrosion resistance. • The specimen anodized in the HA-containing electrolyte can more efficiently induce Ca–P precipitation. - Abstract: To improve the corrosion resistance of magnesium, micro-arc oxidation (MAO) coatings were prepared on magnesium substrates in an aqueous solution with and without hydroxyapatite (HA) powders addition. The micrographs of scanning electron microscopy (SEM), the energy dispersive spectrometer (EDS) spectra, and X-ray diffraction (XRD) analysis show that the HA powders added into the electrolyte have participated in the formation reactions of MAO coating and the growth efficiency of MAO coating is greatly enhanced. Potentiodynamic polarization tests and immersion tests in simulated body fluid (SBF) confirm that the specimen anodized in the HA-containing electrolyte has a better corrosion resistance than the specimen anodized in the HA-free electrolyte. Immersion tests also indicate that the specimen anodized in the HA-containing electrolyte can more efficiently induce Ca–P precipitation compared with the specimen anodized in the HA-free electrolyte.

  20. Effect of calcium oxide on the efficiency of ferrous ion oxidation and total iron precipitation during ferrous ion oxidation in simulated acid mine drainage treatment with inoculation of Acidithiobacillus ferrooxidans.

    Science.gov (United States)

    Liu, Fenwu; Zhou, Jun; Jin, Tongjun; Zhang, Shasha; Liu, Lanlan

    2016-01-01

    Calcium oxide was added into ferrous ion oxidation system in the presence of Acidithiobacillus ferrooxidans at concentrations of 0-4.00 g/L. The pH, ferrous ion oxidation efficiency, total iron precipitation efficiency, and phase of the solid minerals harvested from different treatments were investigated during the ferrous ion oxidation process. In control check (CK) system, pH of the solution decreased from 2.81 to 2.25 when ferrous ions achieved complete oxidation after 72 h of Acidithiobacillus ferrooxidans incubation without the addition of calcium oxide, and total iron precipitation efficiency reached 20.2%. Efficiency of ferrous ion oxidation and total iron precipitation was significantly improved when the amount of calcium oxide added was ≤1.33 g/L, and the minerals harvested from systems were mainly a mixture of jarosite and schwertmannite. For example, the ferrous ion oxidation efficiency reached 100% at 60 h and total iron precipitation efficiency was increased to 32.1% at 72 h when 1.33 g/L of calcium oxide was added. However, ferrous ion oxidation and total iron precipitation for jarosite and schwertmannite formation were inhibited if the amount of calcium oxide added was above 2.67 g/L, and large amounts of calcium sulfate dihydrate were generated in systems.

  1. Removal of antimony (Sb(V)) from Sb mine drainage: biological sulfate reduction and sulfide oxidation-precipitation.

    Science.gov (United States)

    Wang, Huawei; Chen, Fulong; Mu, Shuyong; Zhang, Daoyong; Pan, Xiangliang; Lee, Duu-Jong; Chang, Jo-Shu

    2013-10-01

    Antimony (Sb(V)) in Sb mine drainage has adverse effects on the receiving water environments. This study for the first time demonstrated the feasibility of using sulfate-reducing bacteria (SRB) to convert sulfate ions in SMD into sulfides that reduce Sb(V) to Sb(III) and to form complex with Sb(III) as precipitate. The principal compound in the precipitate was stibnite (Sb2S3) at pH 7 and pH 9. The Sb(V) removal mechanism is sulfate-reduction and sulfide oxidization-precipitation, different from the conventional SRB-precipitation processes for heavy metals. The Sb(V)/sulfate ratio is noted an essential parameter affecting the Sb removal efficiency from SMD.

  2. Oxidative Precipitation of Manganese from Acid Mine Drainage by Potassium Permanganate

    Directory of Open Access Journals (Sweden)

    Regeane M. Freitas

    2013-01-01

    Full Text Available Although oxidative precipitation by potassium permanganate is a widely recognised process for manganese removal, research dealing with highly contaminated acid mine drainage (AMD has yet to be performed. The present study investigated the efficiency of KMnO4 in removing manganese from AMD effluents. Samples of AMD that originated from inactive uranium mine in Brazil were chemically characterised and treated by KMnO4 at pH 3.0, 5.0, and 7.0. Analyses by Raman spectroscopy and geochemical modelling using PHREEQC code were employed to assess solid phases. Results indicated that the manganese was rapidly oxidised by KMnO4 in a process enhanced at higher pH. The greatest removal, that is, 99%, occurred at pH 7.0, when treated waters presented manganese levels as low as 1.0 mg/L, the limit established by the Brazilian legislation. Birnessite (MnO2, hausmannite (Mn3O4, and manganite (MnOOH were detected by Raman spectroscopy. These phases were consistently identified by the geochemical model, which also predicted phases containing iron, uranium, manganese, and aluminium during the correction of the pH as well as bixbyite (Mn2O3, nsutite (MnO2, pyrolusite (MnO2, and fluorite (CaF2 following the KMnO4 addition.

  3. Adsorption of Zn2+ from solutions on manganese oxide obtained via ozone precipitation reaction

    Directory of Open Access Journals (Sweden)

    Contreras-Bustos Roberto

    2016-03-01

    Full Text Available Synthesis via ozone precipitation reaction was used to obtain manganese dioxide (OMD and it was probed as an adsorbent for zinc ions. Adsorption was followed along shaking time and increasing ratio [NO3−] / [Zn2+], and isotherms were obtained at different pH values and in the presence of several anions (chloride, nitrate, sulphate, and acetate. It was found that adsorption equilibrium is fast and follows the pseudo-second order model (qe = 34 ±1 mg/g and K = 0.07 ±0.01 g/mg h. Isotherms were fitted to Langmuir, Freundlich, and Langmuir-Freundlich models, and the best fitting was found with the last one. The process is dependent on pH and the efficiency increases from pH 1 to 4. The ratio [NO3−] / [Zn2+] up to 3 does not seem to change the behaviour of the process. Regarding the anions, the efficiency of Zn(II adsorption occurs according to: acetate > nitrate and sulphate > chloride. Manganese oxide obtained via ozonization is an excellent adsorbent for zinc ions.

  4. Structural and photoluminescence studies of Eu3+ doped zinc oxide nanorods prepared by precipitation method

    Institute of Scientific and Technical Information of China (English)

    Partha P.Pal; J.Manam

    2013-01-01

    Trivalent europium doped zinc oxide (ZnO:Eu3+) nanocrystals were synthesized via room temperature chemical co-precipitation and they were systematically characterized by means of X-ray diffraction (XRD),Fourier transform infrared spectroscopy (FTIR) and photoluminescence (PL) spectroscopy.The as-synthesized samples were found to have hexagonal wurtzite coexisted with the intermediate Zn5(OH)8Cl2·H2O phase,while the single hexagonal phase was facilitated due to the calcinations.The as obtained samples were broadly composed of nanoflakes while the highly crystalline nanorods were formed due to low temperature annealing of the as-synthesized samples.The crystallite size of the nanoflakes and nanorods (40-90 nm) were extracted from the XRD pattern which was found to be consistent with scanning electron microscopy (SEM) measurements.The photoluminescence (PL) spectra of nanophosphors showed bright red and orange emissions at 618 and 594 nm respectively with efficient broad blue green emission spectrum due to ZnO latticc.Further,a good cnergy transfer process from ZnO host to Eu3+ was observed in PL emission and excitation spectra of Eu3+ doped ZnO ions.In all,the present nanophosphors were found to have great potentiality for bio-applications.

  5. The formation of magnetic carboxymethyl-dextrane-coated iron-oxide nanoparticles using precipitation from an aqueous solution

    Energy Technology Data Exchange (ETDEWEB)

    Makovec, Darko [Department for Materials Synthesis, Jožef Stefan Institute, Jamova ulica 39, SI-1000 Ljubljana (Slovenia); Gyergyek, Sašo, E-mail: saso.gyergyek@ijs.si [Department for Materials Synthesis, Jožef Stefan Institute, Jamova ulica 39, SI-1000 Ljubljana (Slovenia); Primc, Darinka [Department for Materials Synthesis, Jožef Stefan Institute, Jamova ulica 39, SI-1000 Ljubljana (Slovenia); Plantan, Ivan [Lek Pharmaceuticals d.d., Mengeš (Slovenia)

    2015-03-01

    The formation of spinel iron-oxide nanoparticles during the co-precipitation of Fe{sup 3+}/Fe{sup 2+} ions from an aqueous solution in the presence of carboxymethyldextrane (CMD) was studied. To follow the formation of the nanoparticles, a mixture of the Fe ions, CMD and ammonia was heated to different temperatures, while the samples were taken, quenched in liquid nitrogen, freeze-dried and characterized using transmission electron microscopy (TEM), X-ray diffractometry (XRD) and magnetometry. The CMD plays a role in the reactions of the Fe ions' precipitation by partially immobilizing the Fe{sup 3+} ions into a complex. At room temperature, the amorphous material is precipitated. Then, above approximately 30 °C, the spinel nanoparticles form inside the amorphous matrix, and at approximately 40 °C the matrix decomposes into the suspension of carboxymethyl-dextrane-coated iron-oxide nanoparticles. The CMD bonded to the nanoparticles' surfaces hinders the mass transport and thus prevents their growth. - Highlights: • The carboxymethyl-dextrane coated iron-oxide nanoparticles were synthesized. • The carboxymethyl-dextrane significantly modifies formation of the spinel nanoparticles. • The spinel nanoparticles are formed inside the amorphous matrix. • At approximately 40 °C the matrix decomposes into the suspension of carboxymethyl-dextrane-coated iron-oxide nanoparticles.

  6. Copper electrodeposition from cuprous chloride solutions containing lead, zinc or iron ions

    Institute of Scientific and Technical Information of China (English)

    M. Tchoumou; M. Roynette Ehics

    2005-01-01

    Cuprous chloride hydrochloric acid solutions were electrolysed in a two compartments cell without agitation for copper extraction. It is found that the current density affects the colour and the size of copper deposits. During electrodeposition of copper from cuprous solution in the presence of various concentrations of lead, zinc or iron ions at different current densities, it is observed that lead is codeposited with copper by increasing current density.In all experiments, the current efficiency for the copper deposition reaction fluctuates between 88.50% and 95.50%.

  7. Effect of precipitating agent NaOH on the preparation of copper oxide nanostructures for electrochemical applications

    OpenAIRE

    Balasubramaniam, M.; S Balakumar

    2016-01-01

    Copper oxide (CuO) nanostructures with different concentrations of sodium hydroxide for electrochemical applications such as supercapacitors have been synthesized using a simple and low-cost precipitation method. X-ray diffraction pattern confirmed the formation of CuO nanostructures without any impurities and further confirmed its highly crystalline, single phase, monoclinic nature. UV-diffuse reflectance spectral (UVDRS) studies provided the absorption edge of the material and the estimated...

  8. Improvement of corrosion resistance of AZ31 Mg alloy by anodizing with co-precipitation of cerium oxide

    Institute of Scientific and Technical Information of China (English)

    Salah Abdelghany SALMAN; Ryoichi ICHINO; Masazumi OKIDO

    2009-01-01

    Anodizing of AZ31 Mg alloy in NaOH solution by co-precipitation of cerium oxide was investigated. The chemical composition and phase structure of the coating film were determined via optical microscopy, SEM and XRD. The corrosion properties of the anodic film were characterized by using potentiodynamic polarization curves in 17 mmol/L NaCl and 0.1 mol/L Na2SO4 solution at 298 K. The corrosion resistance of AZ31 magnesium alloy is significantly improved by adding cerium oxide to alkaline solution. In addition, the surface properties are enhanced and the film contains no crack.

  9. Characterization of CeO2-ZrO2 mixed oxides prepared by two different co-precipitation methods

    Institute of Scientific and Technical Information of China (English)

    YUE Mei; CUI Meisheng; ZHANG Na; LONG Zhiqi; HUANG Xiaowei

    2013-01-01

    A series of cerium zirconium mixed oxides were prepared by two co-precipitation methods using magnesium hydrogen carbonate (MHC) and mixed ammonia-ammonia hydrogen carbonate (AAHC) as precipitant respectively.The crystal structure,BET surface area and morphology of the produced cerium zirconium mixed oxides were characterized by X-ray diffraction (XRD),Brumauer-Emmett-Teller (BET) and scanning electron microscopy (SEM) techniques.The reduction-oxidation behavior and oxygen storage capacity (OSC) performance were also studied by temperature programmed reduction (TPR) and oxygen pulse chemical adsorption methods.The XRD results demonstrated that the cerium zirconium mixed oxides obtained by both methods possessed structure of cubic solid solution phase.The fresh surface area calcinated at 600 ℃,aged surface area after 1000 ℃ and OSC at 500 ℃ of cerium zirconium mixed oxides were determined to be 89.337,34.784 m2/g,and 567 μmol O2/g for MHC method and 122.010,46.307 m2/g,and 665 μmol O2/g for AAHC method,respectively.

  10. Ammonia-Oxidizing Archaea Are More Resistant Than Denitrifiers to Seasonal Precipitation Changes in an Acidic Subtropical Forest Soil

    Directory of Open Access Journals (Sweden)

    Jie Chen

    2017-07-01

    Full Text Available Seasonal precipitation changes are increasingly severe in subtropical areas. However, the responses of soil nitrogen (N cycle and its associated functional microorganisms to such precipitation changes remain unclear. In this study, two projected precipitation patterns were manipulated: intensifying the dry-season drought (DD and extending the dry-season duration (ED but increasing the wet-season storms following the DD and ED treatment period. The effects of these two contrasting precipitation patterns on soil net N transformation rates and functional gene abundances were quantitatively assessed through a resistance index. Results showed that the resistance index of functional microbial abundance (-0.03 ± 0.08 was much lower than that of the net N transformation rate (0.55 ± 0.02 throughout the experiment, indicating that microbial abundance was more responsive to precipitation changes compared with the N transformation rate. Spring drought under the ED treatment significantly increased the abundances of both nitrifying (amoA and denitrifying genes (nirK, nirS, and nosZ, while changes in these gene abundances overlapped largely with control treatment during droughts in the dry season. Interestingly, the resistance index of the ammonia-oxidizing archaea (AOA amoA abundance was significantly higher than that of the denitrifying gene abundances, suggesting that AOA were more resistant to the precipitation changes. This was attributed to the stronger environmental adaptability and higher resource utilization efficiency of the AOA community, as indicated by the lack of correlations between AOA gene abundance and environmental factors [i.e., soil water content, ammonium (NH4+ and dissolved organic carbon concentrations] during the experiment.

  11. Mercury (II) reduction and co-precipitation of metallic mercury on hydrous ferric oxide in contaminated groundwater.

    Science.gov (United States)

    Richard, Jan-Helge; Bischoff, Cornelia; Ahrens, Christian G M; Biester, Harald

    2016-01-01

    Mercury (Hg) speciation and sorption analyses in contaminated aquifers are useful for understanding transformation, retention, and mobility of Hg in groundwater. In most aquifers hydrous ferric oxides (HFOs) are among the most important sorbents for trace metals; however, their role in sorption or mobilization of Hg in aquifers has been rarely analyzed. In this study, we investigated Hg chemistry and Hg sorption to HFO under changing redox conditions in a highly HgCl2-contaminated aquifer (up to 870μgL(-1) Hg). Results from aqueous and solid phase Hg measurements were compared to modeled (PHREEQC) data. Speciation analyses of dissolved mercury indicated that Hg(II) forms were reduced to Hg(0) under anoxic conditions, and adsorbed to or co-precipitated with HFO. Solid phase Hg thermo-desorption measurements revealed that between 55 and 93% of Hg bound to HFO was elemental Hg (Hg(0)). Hg concentrations in precipitates reached more than 4 weight %, up to 7000 times higher than predicted by geochemical models that do not consider unspecific sorption to and co-precipitation of elemental Hg with HFO. The observed process of Hg(II) reduction and Hg(0) formation, and its retention and co-precipitation by HFO is thought to be crucial in HgCl2-contaminated aquifers with variable redox-conditions regarding the related decrease in Hg solubility (factor of ~10(6)), and retention of Hg in the aquifer.

  12. Formation of Al-Si Composite Oxide Film by Hydrolysis Precipitation and Anodizing

    Institute of Scientific and Technical Information of China (English)

    Zhe-Sheng Feng; Ying-Jie Xia; Jia Ding; Jin-Ju Chen

    2007-01-01

    This paper presents a new technique in the high dielectric constant composite oxide film preparation.On the basis of nanocompsite high dielectric constant aluminum oxide film growth technology, a new idea of adulterating Si oxide species into the aluminum composite film was proposed. As a result, the specific capacitance and withstanding voltage of the composite oxide film formed at the anodizing voltage of 20V are enhanced, and the leakage current of the aluminum composite oxide film is reduced through incorporation of Si oxide species.

  13. Mineral Liberation of Magnetite-Precipitated Copper Slag Obtained via Molten Oxidation by Using High-Voltage Electrical Pulses

    Science.gov (United States)

    Fan, Yong; Shibata, Etsuro; Iizuka, Atsushi; Nakamura, Takashi

    2016-10-01

    Our proposed method, i.e., a controlled molten oxidation process under 1 vol pct oxygen, leads to selective precipitation of magnetite in a copper smelter slag for downstream iron separation. In the present study, the preroasted magnetite precipitated copper slag was treated via magnetite liberation, which was realized by using high-voltage electrical pulses. The mineral distribution was determined by using a laser microscope and its image analysis; and it revealed that the 100- µm under-sieve product contains approximately 70 pct of liberated mineral particles. The study affirms the positive outcome of using this new technology for comminution to obtain micrometer-scale particles that yield monominerals via selective liberation. Using magnetic separation, iron was capable of finally separating into high- and low-iron-bearing concentrate and tailing that can be used in specific applications.

  14. The magnetic and oxidation behavior of bare and silica-coated iron oxide nanoparticles synthesized by reverse co-precipitation of ferrous ion (Fe2+) in ambient atmosphere

    Science.gov (United States)

    Mahmed, N.; Heczko, O.; Lancok, A.; Hannula, S.-P.

    2014-03-01

    The synthesis of iron oxide nanoparticles, i.e., magnetite was attempted by using only ferrous ion (Fe2+) as a magnetite precursor, under an ambient atmosphere. The room temperature reverse co-precipitation method was used, by applying two synthesis protocols. The freshly prepared iron oxide was also immediately coated with Stöber silica (SiO2) layer, forming the coreshell structure. The phase, stoichiometry, crystallite and the particle size of the synthesized powders were determined by using X-ray diffraction (XRD) and transmission electron microscope (TEM), while the magnetic and oxidation behaviors were studied by using the vibrating sample magnetometer (VSM) and Mössbauer spectroscopy. Based on the results, the bare iron oxide nanoparticles are in the stoichiometry between the magnetite and the maghemite stoichiometry, i.e., oxidation occurs. This oxidation is depending on the synthesis protocols used. With the silica coating, the oxidation can be prevented, as suggested by the fits of Mössbauer spectra and low temperature magnetic measurement.

  15. Performance improvement of electrochromic display devices employing micro-size precipitates of tungsten oxide

    Energy Technology Data Exchange (ETDEWEB)

    Cheng, Chin-Pao; Kuo, Yi; Chou, Chuan-Pu; Cheng, Chun-Hu [National Taiwan Normal University, Department of Mechatronic Technology, Taipei (China); Teng, Tun Ping [National Taiwan Normal University, Department of Industrial Education, Taipei (China)

    2014-09-15

    In this paper, we studied the effect of micro-size WO{sub 3} precipitates on the electrochromic characteristics based on aging test. The electrochromic mechanism can be effectively investigated by a solid-state TaN/WO{sub 3}/ITO capacitor. The experimental results reveal that WO{sub 3} electrochromic devices with optimized aging time of 4 days exhibit a higher optical contrast and longer retention time, which is mainly attributed to the formation of micro-size WO{sub 3} precipitates during aging process. The performance improvement using micro-size WO{sub 3} precipitates has the potential in future large-area window or energy efficient display applications. (orig.)

  16. Biogenic uraninite precipitation and its reoxidation by iron(III) (hydr)oxides: A reaction modeling approach

    Science.gov (United States)

    Spycher, Nicolas F.; Issarangkun, Montarat; Stewart, Brandy D.; Sevinç Şengör, S.; Belding, Eileen; Ginn, Tim R.; Peyton, Brent M.; Sani, Rajesh K.

    2011-08-01

    One option for immobilizing uranium present in subsurface contaminated groundwater is in situ bioremediation, whereby dissimilatory metal-reducing bacteria and/or sulfate-reducing bacteria are stimulated to catalyze the reduction of soluble U(VI) and precipitate it as uraninite (UO 2). This is typically accomplished by amending groundwater with an organic electron donor. It has been shown, however, that once the electron donor is entirely consumed, Fe(III) (hydr)oxides can reoxidize biogenically produced UO 2, thus potentially impeding cleanup efforts. On the basis of published experiments showing that such reoxidation takes place even under highly reducing conditions (e.g., sulfate-reducing conditions), thermodynamic and kinetic constraints affecting this reoxidation are examined using multicomponent biogeochemical simulations, with particular focus on the role of sulfide and Fe(II) in solution. The solubility of UO 2 and Fe(III) (hydr)oxides are presented, and the effect of nanoscale particle size on stability is discussed. Thermodynamically, sulfide is preferentially oxidized by Fe(III) (hydr)oxides, compared to biogenic UO 2, and for this reason the relative rates of sulfide and UO 2 oxidation play a key role on whether or not UO 2 reoxidizes. The amount of Fe(II) in solution is another important factor, with the precipitation of Fe(II) minerals lowering the Fe +2 activity in solution and increasing the potential for both sulfide and UO 2 reoxidation. The greater (and unintuitive) UO 2 reoxidation by hematite compared to ferrihydrite previously reported in some experiments can be explained by the exhaustion of this mineral from reaction with sulfide. Simulations also confirm previous studies suggesting that carbonate produced by the degradation of organic electron donors used for bioreduction may significantly increase the potential for UO 2 reoxidation through formation of uranyl carbonate aqueous complexes.

  17. Characterization of Oxide Layer with Precipitates of HANA-6 Exposed in Simulated PWR Primary Water Environment

    Energy Technology Data Exchange (ETDEWEB)

    Jang, Hun; Lim, Jea Young; Lee, Sung Yong; Kim, Yoon Ho; Mok, Yong Kyoon [KEPCO NF, Daejeon (Korea, Republic of)

    2016-10-15

    The delayed oxidation behaviors of β-Nb ppts and their amorphization behaviors in HANA-6 and other Zr-base alloys have been frequently reported. On the other hand, although Zr(Nb,Fe)2 ppts could be formed in the HANA-6 alloy due to Fe impurities contained in Zrsponge, the oxidation behavior of Zr(Nb,Fe)2 ppts contained in HANA-6 alloy has not been fully understood. In this study, oxide characteristics of HANA-6 corroded in simulated PWR environment for 165 and 315 days were investigated. And, oxidation behaviors of Zr(Nb,Fe)2 ppts contained in HANA-6 alloy were investigated by TEM with EDS techniques. The superior corrosion property of HANA-6 has been confirmed through corrosion test in simulated PWR water for 387 days. By using TEM/EDS technique, the oxide characteristics with presence of β- Nb (or β-enriched), and ZrNbFe (possibly Zr(Nb,Fe){sub 2}) ppts have been characterized as follows. 1. Delayed oxidation behaviors of β-Nb and Zr(Nb,Fe){sub 2} ppts and their amorphization due to oxidation were observed from TEM/EDS analyses. 2. The oxide layers having crystallite and partially amorphous ppts were slightly increased with increasing corrosion test time from 165 days to 315 days. 3. In outer oxide layer, Fe in Zr(Nb,Fe){sub 2} ppt was depleted and dissolved to outer layer of ppt and bulk oxide layer.

  18. Stabilization of microbial residues by co-precipitation with Fe and Al oxides

    Science.gov (United States)

    Miltner, Anja; Achtenhagen, Jan; Kästner, Matthias

    2016-04-01

    Recent studies have shown that microbial residues contribute significantly to soil organic matter (SOM) formation. This material, however, is readily degradable and thus needs to be stabilized in soil. We hypothesize that the interaction with minerals, in particular co-precipitation with metal oxyhydroxides, plays an important role in stabilization of cell envelope material. We therefore analyzed the mineralization of 14C-labelled Escherichia coli cells and cell envelope fragments during incubation of the cell materials alone or after co-precipitation with either Fe or Al oxyhydroxide. We also tested the effect of environmental conditions, in particular oxygen supply and redox potential, on the stabilizing effect of the mineral phases. Co-precipitation with both Fe and Al oxyhydroxides decreased the mineralization significantly, indicating strong protection of biomass and biomass-derived fragments. Surprisingly, the mineralization of intact cells was higher than that of cell envelope fragments. This points to a higher recalcitrance of the cell envelope fragments, which therefore may be selectively enriched in SOM. Reductive conditions obtained after water-logging combined with excessive supply of an easily available carbon source resulted in increased mineralization in the treatments containing Fe oxyhydroxides, due to reductive dissolution of the Fe oxyhydroxide and thus loss of the stabilizing agent. We therefore conclude that co-precipitation with and incrustation by Fe or Al oxyhydroxides is a relevant stabilization mechanism for microbial residues. The same mechanism also may apply for SOM in general.

  19. Recent changes in the oxidized to reduced nitrogen ratio in atmospheric precipitation

    Science.gov (United States)

    Kurzyca, Iwona; Frankowski, Marcin

    2017-10-01

    In this study, the characteristics of precipitation in terms of various nitrogen forms (NO3-, NO2-, NH4+, Norganic, Ntotal) is presented. The samples were collected in the areas of different anthropogenic pressure (urban area vs. ecologically protected woodland area, ∼30 km distant from each other; Wielkopolska region, Poland). Based on the Nox and Nred emission profiles (Nox/Nred ratio), temporal and spatial comparison was carried out. For both sites, during a decade of observation, more than 60% of samples had higher contribution of N-NH4+ than N-NO3-, the amount of N-NO2- was negligible, and organic nitrogen amounted to 30% of total nitrogen content which varied up to 16 mg/l. The precipitation events w ith high concentration of nitrogen species were investigated in terms of possible local and remote sources of nitrogen (synoptic meteorology), to indicate the areas which can act as potential sources of N-compounds. Based on the chemometric analysis, it was found that Nred implies Nox and vice versa, due to interactions between them in the atmosphere. Taking into account the analysis of precipitation occurring simultaneously in both locations (about 50% of all rainfall episodes), it was observed that such factor as anthropogenic pressure differentiates but does not determine the chemical composition of precipitation in the investigated areas (urban vs. woodland area; distance of ∼30 km). Thermodynamics of the atmosphere had a significant impact on concentrations of N-NO3- and N-NH4+ in precipitation, as well as the circulation of air masses and remote N sources responsible for transboundary inflow of pollutants.

  20. Mesoporous composite nickel cobalt oxide/graphene oxide synthesized via a template-assistant co-precipitation route as electrode material for supercapacitors

    Science.gov (United States)

    Xu, Yanjie; Wang, Lincai; Cao, Peiqi; Cai, Chuanlin; Fu, Yanbao; Ma, Xiaohua

    2016-02-01

    A simple co-precipitation method utilizing SDS (sodium dodecyl sulfate) as template and ammonia as precipitant is successfully employed to synthesize nickel cobalt oxide/graphene oxide (NiCo2O4/GO) composite. The as-prepared composite (NCG-10) exhibits a high capacitance of 1211.25 F g-1, 687 F g-1 at the current density of 1 A g-1, 10 A g-1 and good cycling ability which renders NCG-10 as promising electrode material for supercapacitors. An asymmetric supercapacitor (ASC) (full button cell) has been constructed with NCG-10 as positive electrode and lab-made reduced graphene oxide (rGO) as negative electrode. The fabricated NCG-10//rGO with an extended stable operational voltage of 1.6 V can deliver a high specific capacitance of 144.45 F g-1 at a current density of 1 A g-1. The as-prepared NCG-10//rGO demonstrates remarkable energy density (51.36 W h kg-1 at 1 A g-1), high power density (50 kW kg-1 at 20 A g-1). The retention of capacitance is 88.6% at the current density of 8 A g-1 after 2000 cycles. The enhanced capacitive performance can be attributed to the improved specific surface area and 3D open area of NCG-10 generated by the pores and channels with the substantial function of SDS.

  1. Photocatalytic degradation of methylene blue dye by zinc oxide nanoparticles obtained from precipitation and sol-gel methods.

    Science.gov (United States)

    Balcha, Abebe; Yadav, Om Prakash; Dey, Tania

    2016-12-01

    Zinc oxide (ZnO) nanoparticles were synthesized by precipitation and sol-gel methods. The aim of this study was to understand how different synthetic methods can affect the photocatalytic activity of ZnO nanoparticles. As-synthesized ZnO nanoparticles were characterized by X-ray diffraction (XRD) and UV-Visible spectroscopic techniques. XRD patterns of ZnO powders synthesized by precipitation and sol-gel methods revealed their hexagonal wurtzite structure with crystallite sizes of 30 and 28 nm, respectively. Their photocatalytic activities were evaluated by photocatalytic degradation of methylene blue, a common water pollutant, under UV radiation. The effects of operational parameters such as photocatalyst load and initial concentration of the dye on photocatalytic degradation of methylene blue were investigated. While the degradation of dye decreased over the studied dye concentration range of 20 to 100 mg/L, an optimum photocatalyst load of 250 mg/L was needed to achieve dye degradation as high as 81 and 92.5 % for ZnO prepared by precipitation and sol-gel methods, respectively. Assuming pseudo first-order reaction kinetics, this corresponded to rate constants of 8.4 × 10(-3) and 12.4 × 10(-3) min(-1), respectively. Hence, sol-gel method is preferred over precipitation method in order to achieve higher photocatalytic activity of ZnO nanostructures. Photocatalytic activity is further augmented by better choice of capping ligand for colloidal stabilization, starch being more effective than polyethylene glycol (PEG).

  2. Final Report for DOE grant no. DE-FG02-04ER63883: Can soil genomics predict the impact of precipitation on nitrous oxide flux from soil

    Energy Technology Data Exchange (ETDEWEB)

    Egbert Schwartz

    2008-12-15

    Nitrous oxide is a potent greenhouse gas that is released by microorganisms in soil. However, the production of nitrous oxide in soil is highly variable and difficult to predict. Future climate change may have large impacts on nitrous oxide release through alteration of precipitation patterns. We analyzed DNA extracted from soil in order to uncover relationships between microbial processes, abundance of particular DNA sequences and net nitrous oxide fluxes from soil. Denitrification, a microbial process in which nitrate is used as an electron acceptor, correlated with nitrous oxide flux from soil. The abundance of ammonia oxidizing archaea correlated positively, but weakly, with nitrous oxide production in soil. The abundance of bacterial genes in soil was negatively correlated with gross nitrogen mineralization rates and nitrous oxide release from soil. We suggest that the most important control over nitrous oxide production in soil is the growth and death of microorganisms. When organisms are growing nitrogen is incorporated into their biomass and nitrous oxide flux is low. In contrast, when microorganisms die, due to predation or infection by viruses, inorganic nitrogen is released into the soil resulting in nitrous oxide release. Higher rates of precipitation increase access to microorganisms by predators or viruses through filling large soil pores with water and therefore can lead to large releases of nitrous oxide from soil. We developed a new technique, stable isotope probing with 18O-water, to study growth and mortality of microorganisms in soil.

  3. Ammonia-oxidizing archaea are more resistant than denitrifiers to seasonal precipitation changes in an acidic subtropical forest soil

    Science.gov (United States)

    Chen, Jie

    2017-04-01

    More frequent droughts and storms will occur globally in the prediction of global climate change model, which will influence soil microorganisms and nutrient cycles. Understanding the resistance of soil functional microorganisms and the associated biogeochemical cycles to such climate changes is important in evaluating responses of ecosystem functioning. In order to clarify the responses of soil functional microorganisms involved in nitrogen (N) cycle to the predicted precipitation scenarios, two contrasting precipitation manipulation experiments were conducted in an acidic subtropical forest soil. One experiment manipulated drier dry-season and wetter wet-season (DD) by reducing dry-season rainfall and adding the equivalently reduced rainfall to wet-season. Another experiment manipulated extending dry-season and wetter wet-season (ED) by reducing spring-season rainfall and adding the equivalent rainfall in the late wet-season. The resistance index of ammonia-oxidizing archaea (AOA) amoA and denitrifying (nirK, nirS and nosZ) genes abundance, soil net N mineralization and nitrification rates were calculated during experiments to examine their responses to precipitation changes. As the results, the resistance index of functional microbial abundance (-0.03 ± 0.08) was much lower than that of net N transformation rates (0.55 ± 0.02), indicating more sensitive of functional microorganisms in response to precipitation changes than the related N processes. Extending dry-season showed greater effects on both AOA amoA and denitrifying genes abundance than drier dry-season, with significant increases of these microbial abundance after extending dry-season. This was mainly due to the interaction effects of soil water content (SWC), dissolve organic carbon (DOC) and NH4+ concentration during rainfall reduction in spring-season. Interestingly, the resistance index of AOA amoA abundance was significantly higher than that of denitrifying gene abundance, indicating more

  4. In situ synthesis of magnetic mesoporous silica via sol-gel process coupled with precipitation and oxidation

    Institute of Scientific and Technical Information of China (English)

    Junqi Zhao; Yujun Wang; Guangsheng Luo; Shenlin Zhu

    2011-01-01

    A novel method was proposed for the in situ synthesis of magnetite-containing mesoporous silica SBA-16 via a sol-gel process coupled with precipitation and oxidation. The effect of the added amounts of reactants on the mesostructural and magnetic properties of the magnetic mesoporous silica was investigated. It was determined that the synthesized magnetic mesoporous silica with a total pore volume of 0.64-0.96 cm3/g and an average pore diameter of 4.0-14.9 nm had a relatively high saturation magnetization value (1.11-5.77 emu/g) and a large surface area (258-747 m2/g). Lysozyme was chosen as a model protein to test the performance of the magnetic mesoporous silica as a protein adsorbent. The high adsorption capacity (up to 212 mg/g) suggested a promising future as bimolecular hosts for the magnetic mesoporous silica.

  5. Mercury distribution and lipid oxidation in fish muscle: Effects of washing and isoelectric protein precipitation

    Science.gov (United States)

    Gong, Y.; Krabbenhoft, D.P.; Ren, L.; Egelandsdal, B.; Richards, M.P.

    2011-01-01

    Nearly all the mercury (Hg) in whole muscle from whitefish (Coregonus clupeaformis) and walleye (Sander vitreus) was present as methyl mercury (MeHg). The Hg content in whole muscle from whitefish and walleye was 0.04-0.09 and 0.14-0.81 ppm, respectively. The myofibril fraction contained approximately three-fourths of the Hg in whitefish and walleye whole muscle. The sarcoplasmic protein fraction (e.g., press juice) was the next most abundant source of Hg. Isolated myosin, triacylglycerols, and cellular membranes contained the least Hg. Protein isolates prepared by pH shifting in the presence of citric acid did not decrease Hg levels. Addition of cysteine during washing decreased the Hg content in washed muscle probably through the interaction of the sulfhydryl group in cysteine with MeHg. Primary and secondary lipid oxidation products were lower during 2 ??C storage in isolates prepared by pH shifting compared to those of washed or unwashed mince from whole muscle. This was attributed to removing some of the cellular membranes by pH shifting. Washing the mince accelerated lipid peroxide formation but decreased secondary lipid oxidation products compared to that of the unwashed mince. This suggested that there was a lipid hydroperoxide generating system that was active upon dilution of aqueous antioxidants and pro-oxidants. ?? 2011 American Chemical Society.

  6. Mechanism of β-FeSi{sub 2} precipitates growth-and-dissolution and pyramidal defects' formation during oxidation of Fe-contaminated silicon wafers

    Energy Technology Data Exchange (ETDEWEB)

    De Luca, Anthony; Texier, Michaël, E-mail: michael.texier@univ-amu.fr; Portavoce, Alain; Burle, Nelly [Aix Marseille Université, CNRS, IM2NP UMR 7334, bd Escadrille Normandie Niémen, F-13397 Marseille (France); Grosjean, Catherine [ST MicroElectronics, 190 av. Célestin Coq, Z.I. Peynier Rousset, F-13106 Rousset (France); Morata, Stéphane [Ion Beam Services, rue G. Imbert prolongée, Z.I. Peynier Rousset, F-13790 Rousset (France); Michel, Fabrice [Vegatec, 150 av. Célestin Coq, Z.I. Peynier Rousset, F-13106 Rousset (France)

    2015-03-21

    Fe-implanted Si-wafers have been oxidized at 900 °C and 1100 °C in order to investigate the behaviour of Fe atoms at the growing SiO{sub 2}/Si interface and the impact on the integrity of microelectronic devices of an involuntary Fe contamination before or during the oxidation process. As-implanted and oxidized wafers have been characterized using secondary ion mass spectroscopy, atom probe tomography, and high-resolution transmission electron microscopy. Experimental results were compared to calculated implantation profiles and simulated images. Successive steps of iron disilicide precipitation and oxidation were evidenced during the silicon oxidation process. The formation of characteristic pyramidal-shaped defects, at the SiO{sub 2}/Si interface, was notably found to correlate with the presence of β-FeSi{sub 2} precipitates. Taking into account the competitive oxidation of these precipitates and of the surrounding silicon matrix, dynamic mechanisms are proposed to model the observed microstructural evolution of the SiO{sub 2}/Si interface, during the growth of the silicon oxide layer.

  7. Controlling the Formation of Nanocavities in Kirkendall Nanoobjects through Sequential Thermal Ex Situ Oxidation and In Situ Reduction Reactions.

    Science.gov (United States)

    Mel, Abdel-Aziz El; Tessier, Pierre-Yves; Buffiere, Marie; Gautron, Eric; Ding, JunJun; Du, Ke; Choi, Chang-Hwan; Konstantinidis, Stephanos; Snyders, Rony; Bittencourt, Carla; Molina-Luna, Leopoldo

    2016-06-01

    Controlling the porosity, the shape, and the morphology of Kirkendall hollow nanostructures is the key factor to tune the properties of these tailor-made nanomaterials which allow in turn broadening their applications. It is shown that by applying a continuous oxidation to copper nanowires following a temperature ramp protocol, one can synthesize cuprous oxide nanotubes containing periodic copper nanoparticles. A further oxidation of such nanoobjects allows obtaining cupric oxide nanotubes with a bamboo-like structure. On the other hand, by applying a sequential oxidation and reduction reactions to copper nanowires, one can synthesize hollow nanoobjects with complex shapes and morphologies that cannot be obtained using the Kirkendall effect alone, such as necklace-like cuprous oxide nanotubes, periodic solid copper nanoparticles or hollow cuprous oxide nanospheres interconnected with single crystal cuprous oxide nanorods, and aligned and periodic hollow nanospheres embedded in a cuprous oxide nanotube. The strategy demonstrated in this study opens new avenues for the engineering of hollow nanostructures with potential applications in gas sensing, catalysis, and energy storage.

  8. Antisolvent Precipitation for the Synthesis of Monodisperse Mesoporous Niobium Oxide Spheres as Highly Effective Solid Acid Catalysts

    KAUST Repository

    Li, Cheng Chao

    2012-03-20

    We have developed a low-cost reaction protocol to synthesize mesoporous Nb 2O 5-based solid acid catalysts with external shape control. In the synthesis, monodisperse glycolated niobium oxide spheres (GNOS) were prepared by means of a simple antisolvent precipitation approach and subsequently converted to mesoporous niobium oxide spheres (MNOS) with a large surface area of 312m 2g -1 by means of the hydrothermal treatment. The antisolvent acetone used to obtain GNOS was recovered through distillation at high purity. The obtained mesoporous MNOS were functionalized further with sulfate anions at different temperatures or incorporated with tungstophosphoric acid to obtain recyclable solid acid catalysts. These MNOS-based catalysts showed excellent performance in a wide range of acid-catalyzed reactions, such as Friedel-Crafts alkylation, esterification, and hydrolysis of acetates. As they are monodisperse spheres with diameters in the submicrometer range, the catalysts can be easily separated and reused. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. An in situ powder neutron diffraction study of nano-precipitate formation during processing of oxide-dispersion-strengthened ferritic steels

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Hongtao, E-mail: hongtao.zhang@materials.ox.ac.uk [Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH (United Kingdom); Gorley, Michael J. [Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH (United Kingdom); Chong, Kok Boon; Fitzpatrick, Michael E. [Materials Engineering, The Open University, Walton Hall, Milton Keynes MK7 6AA (United Kingdom); Roberts, Steve G.; Grant, Patrick S. [Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH (United Kingdom)

    2014-01-05

    Highlights: • In situ powder neutron diffraction to study precipitate formation in ODS steel. • First real time observation of nano-precipitate formation during processing. • Y{sub 2}O{sub 3} particles were fully dissolved into steel matrix during mechanical alloy. • The precipitation occurred during annealing of as-milled powder above 900 °C. -- Abstract: The evolution of phases in a Fe–14Cr–10Y{sub 2}O{sub 3} (wt%) oxide-dispersion-strengthened ferritic steel during mechanical alloying (MA) and subsequent annealing was studied by high resolution powder neutron diffraction, with emphasis on the kinetics of oxide-based nano-precipitate formation. Y{sub 2}O{sub 3} particles were completely dissolved into the ferritic matrix during MA. The formation of nano-precipitates was then observed by in situ thermo-diffraction experiments during annealing of as-milled powder above 900 °C, supported by scanning electron microscopy. This revealed nano-precipitate coarsening with increasing annealing temperature. Powder microhardness was measured at various processing stages, and hardness changes are discussed in terms of the measured phase fractions, crystallite size and lattice strain at different temperatures and times.

  10. Synthesis of different architectures like stars, multipods, ellipsoids and spikes of zinc oxide by surfactantless precipitation.

    Science.gov (United States)

    Navaladian, S; Viswanathan, B

    2011-11-01

    Zinc oxide with different morphologies like stars, multipods, ellipsoids and spikes was synthesized using zinc nitrate and sodium hydroxide in the absence of surfactants. Seed mediation was found to be essential for the formation of ZnO nanospikes. Synthesized ZnO samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), high resolution transmission electron microscopy (HRTEM), UV-visible diffuse reflectance spectroscopy (UV-vis-DRS) and energy dispersive analysis by X-rays (EDAX) techniques. The predominant c-axis growth of hexagonal lattice was observed in ZnO anisotropic particles. TEM analysis revealed the formation of two types of ZnO ellipsoid particles. Concentration of the reactants was found to have a role in controlling the morphology of the resulting ZnO. Mechanism of formation of varying morphologies of ZnO particles has been proposed.

  11. Hydrous ferric oxide precipitation in the presence of nonmetabolizing bacteria: Constraints on the mechanism of a biotic effect

    Science.gov (United States)

    Rancourt, Denis G.; Thibault, Pierre-Jean; Mavrocordatos, Denis; Lamarche, Gilles

    2005-02-01

    We have used room temperature and cryogenic 57Fe Mössbauer spectroscopy, powder X-ray diffraction (pXRD), mineral magnetometry, and transmission electron microscopy (TEM), to study the synthetic precipitation of hydrous ferric oxides (HFOs) prepared either in the absence (abiotic, a-HFO) or presence (biotic, b-HFO) of nonmetabolizing bacterial cells ( Bacillus subtilis or Bacillus licheniformis, ˜10 8 cells/mL) and under otherwise identical chemical conditions, starting from Fe(II) (10 -2, 10 -3, or 10 -4 mol/L) under open oxic conditions and at different pH (6-9). We have also performed the first Mössbauer spectroscopy measurements of bacterial cell wall ( Bacillus subtilis) surface complexed Fe, where Fe(III) (10 -3.5-10 -4.5 mol/L) was added to a fixed concentration of cells (˜10 8 cells/mL) under open oxic conditions and at various pH (2.5-4.3). We find that non-metabolic bacterial cell wall surface complexation of Fe is not passive in that it affects Fe speciation in at least two ways: (1) it can reduce Fe(III) to sorbed-Fe 2+ by a proposed steric and charge transfer effect and (2) it stabilizes Fe(II) as sorbed-Fe 2+ against ambient oxidation. The cell wall sorption of Fe occurs in a manner that is not compatible with incorporation into the HFO structure (different coordination environment and stabilization of the ferrous state) and the cell wall-sorbed Fe is not chemically bonded to the HFO particle when they coexist (the sorbed Fe is not magnetically polarized by the HFO particle in its magnetically ordered state). This invalidates the concept that sorption is the first step in a heterogeneous nucleation of HFO onto bacterial cell walls. Both the a-HFOs and the b-HFOs are predominantly varieties of ferrihydrite (Fh), often containing admixtures of nanophase lepidocrocite (nLp), yet they show significant abiotic/biotic differences: Biotic Fh has less intraparticle (including surface region) atomic order (Mössbauer quadrupole splitting), smaller primary

  12. Nanowire-based All Oxide Solar Cells

    Energy Technology Data Exchange (ETDEWEB)

    Yang*, Benjamin D. Yuhas and Peidong; Yang, Peidong

    2008-12-07

    We present an all-oxide solar cell fabricated from vertically oriented zinc oxide nanowires and cuprous oxide nanoparticles. Our solar cell consists of vertically oriented n-type zinc oxide nanowires, surrounded by a film constructed from p-type cuprous oxide nanoparticles. Our solution-based synthesis of inexpensive and environmentally benign oxide materials in a solar cell would allow for the facile production of large-scale photovoltaic devices. We found that the solar cell performance is enhanced with the addition of an intermediate oxide insulating layer between the nanowires and the nanoparticles. This observation of the important dependence of the shunt resistance on the photovoltaic performance is widely applicable to any nanowire solar cell constructed with the nanowire array in direct contact with one electrode.

  13. SMALL-SCALE TESTING OF PLUTONIUM (IV) OXALATE PRECIPITATION AND CALCINATION TO PLUTONIUM OXIDE TO SUPPORT THE MOX FEED MISSION

    Energy Technology Data Exchange (ETDEWEB)

    Crowder, M.; Pierce, R.; Scogin, J.; Daniel, G.; King, W.

    2012-06-25

    The H-Canyon facility will be used to dissolve Pu metal for subsequent purification and conversion to plutonium dioxide (PuO{sub 2}) using Phase II of HB-Line. To support the new mission, SRNL conducted a series of experiments to produce calcined plutonium (Pu) oxide and measure the physical properties and water adsorption of that material. This data will help define the process operating conditions and material handling steps for HB-Line. An anion exchange column experiment produced 1.4 L of a purified 52.6 g/L Pu solution. Over the next nine weeks, seven Pu(IV) oxalate precipitations were performed using the same stock Pu solution, with precipitator feed acidities ranging from 0.77 M to 3.0 M nitric acid and digestion times ranging from 5 to 30 minutes. Analysis of precipitator filtrate solutions showed Pu losses below 1% for all precipitations. The four larger precipitation batches matched the target oxalic acid addition time of 44 minutes within 4 minutes. The three smaller precipitation batches focused on evaluation of digestion time and the oxalic acid addition step ranged from 25-34 minutes because of pump limitations in the low flow range. Following the precipitations, 22 calcinations were performed in the range of 610-690 C, with the largest number of samples calcined at either 650 or 635 C. Characterization of the resulting PuO{sub 2} batches showed specific surface areas in the range of 5-14 m{sup 2}/g, with 16 of the 22 samples in the range of 5-10 m2/g. For samples analyzed with typical handling (exposed to ambient air for 15-45 minutes with relative humidities of 20-55%), the moisture content as measured by Mass Spectrometry ranged from 0.15 to 0.45 wt % and the total mass loss at 1000 C, as measured by TGA, ranged from 0.21 to 0.58 wt %. For the samples calcined between 635 and 650 C, the moisture content without extended exposure ranged from 0.20 to 0.38 wt %, and the TGA mass loss ranged from 0.26 to 0.46 wt %. Of these latter samples, the samples

  14. SMALL-SCALE TESTING OF PLUTONIUM (IV) OXALATE PRECIPITATION AND CALCINATION TO PLUTONIUM OXIDE TO SUPPORT THE MOX FEED MISSION

    Energy Technology Data Exchange (ETDEWEB)

    Crowder, M.; Pierce, R.; Scogin, J.; Daniel, G.; King, W.

    2012-06-25

    The H-Canyon facility will be used to dissolve Pu metal for subsequent purification and conversion to plutonium dioxide (PuO{sub 2}) using Phase II of HB-Line. To support the new mission, SRNL conducted a series of experiments to produce calcined plutonium (Pu) oxide and measure the physical properties and water adsorption of that material. This data will help define the process operating conditions and material handling steps for HB-Line. An anion exchange column experiment produced 1.4 L of a purified 52.6 g/L Pu solution. Over the next nine weeks, seven Pu(IV) oxalate precipitations were performed using the same stock Pu solution, with precipitator feed acidities ranging from 0.77 M to 3.0 M nitric acid and digestion times ranging from 5 to 30 minutes. Analysis of precipitator filtrate solutions showed Pu losses below 1% for all precipitations. The four larger precipitation batches matched the target oxalic acid addition time of 44 minutes within 4 minutes. The three smaller precipitation batches focused on evaluation of digestion time and the oxalic acid addition step ranged from 25-34 minutes because of pump limitations in the low flow range. Following the precipitations, 22 calcinations were performed in the range of 610-690 C, with the largest number of samples calcined at either 650 or 635 C. Characterization of the resulting PuO{sub 2} batches showed specific surface areas in the range of 5-14 m{sup 2}/g, with 16 of the 22 samples in the range of 5-10 m2/g. For samples analyzed with typical handling (exposed to ambient air for 15-45 minutes with relative humidities of 20-55%), the moisture content as measured by Mass Spectrometry ranged from 0.15 to 0.45 wt % and the total mass loss at 1000 C, as measured by TGA, ranged from 0.21 to 0.58 wt %. For the samples calcined between 635 and 650 C, the moisture content without extended exposure ranged from 0.20 to 0.38 wt %, and the TGA mass loss ranged from 0.26 to 0.46 wt %. Of these latter samples, the samples

  15. Fluoride adsorption studies on mixed-phase nano iron oxides prepared by surfactant mediation-precipitation technique

    Energy Technology Data Exchange (ETDEWEB)

    Mohapatra, M., E-mail: mamatamohapatra@yahoo.com [Institute of Minerals and Materials Technology, Acharyavihar, Bhubaneswar 751 013, Orissa (India); Rout, K. [Institute of Minerals and Materials Technology, Acharyavihar, Bhubaneswar 751 013, Orissa (India); Singh, P. [Murdoch University, Perth, Western Australia (Australia); Anand, S. [Institute of Minerals and Materials Technology, Acharyavihar, Bhubaneswar 751 013, Orissa (India); Layek, S.; Verma, H.C. [Indian Institute of Technology, Kanpur (India); Mishra, B.K. [Institute of Minerals and Materials Technology, Acharyavihar, Bhubaneswar 751 013, Orissa (India)

    2011-02-28

    Mixed nano iron oxides powder containing goethite ({alpha}-FeOOH), hematite ({alpha}-Fe{sub 2}O{sub 3}) and ferrihydrite (Fe{sub 5}HO{sub 8}.4H{sub 2}O) was synthesized through surfactant mediation-precipitation route using cetyltrimethyl ammonium bromide (CTAB). The X-ray diffraction, FTIR, TEM, Moessbauer spectroscopy were employed to characterize the sample. These studies confirmed the nano powder contained 77% goethite, 9% hematite and 14% ferrihydrite. Fluoride adsorption onto the synthesized sample was investigated using batch adsorption method. The experimental parameters chosen for adsorption studies were: pH (3.0-10.0), temperature (35-55 deg. C), concentrations of adsorbent (0.5-3.0 g/L), adsorbate (10-100 mg/L) and some anions. Adsorption of fluoride onto mixed iron oxide was initially very fast followed by a slow adsorption phase. By varying the initial pH in the range of 3.0-10.0, maximum adsorption was observed at a pH of 5.75. Presence of either SO{sub 4}{sup 2-} or Cl{sup -} adversely affected the adsorption of fluoride in the order of SO{sub 4}{sup 2-} > Cl{sup -}. The FTIR studies of fluoride loaded adsorbent showed that partly the adsorption on the surface took place at surface hydroxyl sites. Moessbauer studies indicated that the overall absorption had gone down after fluoride adsorption that implies it has reduced the crystalline bond strength. The relative absorption area of ferrihydrite was marginally increased from 14 to 17%.

  16. Fluoride adsorption studies on mixed-phase nano iron oxides prepared by surfactant mediation-precipitation technique.

    Science.gov (United States)

    Mohapatra, M; Rout, K; Singh, P; Anand, S; Layek, S; Verma, H C; Mishra, B K

    2011-02-28

    Mixed nano iron oxides powder containing goethite (α-FeOOH), hematite (α-Fe(2)O(3)) and ferrihydrite (Fe(5)HO(8)·4H(2)O) was synthesized through surfactant mediation-precipitation route using cetyltrimethyl ammonium bromide (CTAB). The X-ray diffraction, FTIR, TEM, Mössbauer spectroscopy were employed to characterize the sample. These studies confirmed the nano powder contained 77% goethite, 9% hematite and 14% ferrihydrite. Fluoride adsorption onto the synthesized sample was investigated using batch adsorption method. The experimental parameters chosen for adsorption studies were: pH (3.0-10.0), temperature (35-55°C), concentrations of adsorbent (0.5-3.0 g/L), adsorbate (10-100 mg/L) and some anions. Adsorption of fluoride onto mixed iron oxide was initially very fast followed by a slow adsorption phase. By varying the initial pH in the range of 3.0-10.0, maximum adsorption was observed at a pH of 5.75. Presence of either SO(4)(2-) or Cl(-) adversely affected the adsorption of fluoride in the order of SO(4)(2-)>Cl(-). The FTIR studies of fluoride loaded adsorbent showed that partly the adsorption on the surface took place at surface hydroxyl sites. Mössbauer studies indicated that the overall absorption had gone down after fluoride adsorption that implies it has reduced the crystalline bond strength. The relative absorption area of ferrihydrite was marginally increased from 14 to 17%. Copyright © 2010 Elsevier B.V. All rights reserved.

  17. Competitive removal of Cu-EDTA and Ni-EDTA via microwave-enhanced Fenton oxidation with hydroxide precipitation.

    Science.gov (United States)

    Lin, Qintie; Pan, Hanping; Yao, Kun; Pan, Yonggang; Long, Wei

    2015-01-01

    Ethylenediaminetetraacetic acid (EDTA) can form very stable complexes with heavy metal ions, greatly inhibiting conventional metal-removal technologies used in water treatment. Both the oxidation of EDTA and the reduction of metal ions in metal-EDTA systems via the microwave-enhanced Fenton reaction followed by hydroxide precipitation were investigated. The Cu(II)-Ni(II)-EDTA, Cu(II)-EDTA and Ni(II)-EDTA exhibited widely different decomplexation efficiencies under equivalent conditions. When the reaction reached equilibrium, the chemical oxygen demand was reduced by a microwave-enhanced Fenton reaction in different systems and the reduction order from high to low was Cu(II)-Ni(II)-EDTA ≈ Cu(II)-EDTA > Ni(II)-EDTA. The removal efficiencies of both Cu(2+) and Ni(2+) in Cu-Ni-EDTA wastewaters were much higher than those in a single heavy metal system. The degradation efficiency of EDTA in Cu-Ni-EDTA was lower than that in a single metal system. In the Cu-Ni-EDTA system, the microwave thermal degradation and the Fenton-like reaction created by Cu catalyzed H2O2 altered the EDTA degradation pathway and increased the pH of the wastewater system, conversely inhibiting residual EDTA degradation.

  18. A modular continuous flow reactor system for the selective bio-oxidation of iron and precipitation of schwertmannite from mine-impacted waters.

    Science.gov (United States)

    Hedrich, Sabrina; Johnson, D Barrie

    2012-02-01

    A novel modular bioremediation system which facilitates the selective removal of soluble iron from extremely acidic (pH ∼2) metal-rich wastewaters by ferrous iron oxidation and selective precipitation of the ferric iron produced is described. In the first of the three modules, rapid ferrous iron oxidation was mediated by the recently-characterized iron-oxidizing autotrophic acidophile, "Ferrovum myxofaciens", which grew as long "streamers" within the reactor. Over 90% of the iron present in influent test liquors containing 280mg/L iron was oxidized at a dilution rate of 0.41h(-1), in a proton-consuming reaction. The ferric iron-rich solutions produced were pumped into a second reactor where controlled addition of sodium hydroxide caused the water pH to increase to 3.5 and ferric iron to precipitate as the mineral schwertmannite. Addition of a flocculating agent promoted rapid aggregation and settling of the fine-grain schwertmannite particles. A third passive module (a packed-bed bioreactor, also inoculated with "Fv. myxofaciens") acted as a polishing reactor, lowering soluble iron concentrations in the processed water to iron from a synthetic acidic (pH 2.1) mine water that contained soluble aluminum, copper, manganese and zinc in addition to iron. Schwertmannite was again produced, with little or no co-precipitation of other metals. Copyright © 2011 Elsevier Ltd. All rights reserved.

  19. Influencing factors in the CO-precipitation process of superparamagnetic iron oxide nano particles: A model based study

    Energy Technology Data Exchange (ETDEWEB)

    Roth, Hans-Christian; Schwaminger, Sebastian P.; Schindler, Michael [Bioseparation Engineering Group, Technische Universität München, Boltzmannstraße 15, Garching d-85748 (Germany); Wagner, Friedrich E. [Technische Universität München, Physics Department El5, Garching d-85748 (Germany); Berensmeier, Sonja, E-mail: s.berensmeier@tum.de [Bioseparation Engineering Group, Technische Universität München, Boltzmannstraße 15, Garching d-85748 (Germany)

    2015-03-01

    The study, presented here, focuses on the impact of synthesis parameters on the co-precipitation process of superparamagnetic iron oxide nanoparticles. Particle diameters between 3 and 17 nm and saturation magnetizations from 26 to 89 Am{sup 2} kg{sup −1} were achieved by variation of iron salt concentration, reaction temperature, ratio of hydroxide ions to iron ions and ratio of Fe{sup 3+}/Fe{sup 2+}. All synthesis assays were conceived according to the “design of experiments” method. The results were fitted to significant models. Subsequent validation experiments could confirm the models with an accuracy>95%. The characterization of the chemical composition, as well as structural and magnetic properties was carried out using powder X-ray diffraction, transmission electron microscopy, Raman and Mössbauer spectroscopy and superconducting quantum interference device magnetometry. The results reveal that the particles' saturation magnetization can be enhanced by the employment of high iron salt concentrations and a molar ratio of Fe{sup 3+}/Fe{sup 2+} below 2:1. Furthermore, the particle size can be increased by higher iron salt concentrations and a hyperstoichiometric normal ratio of hydroxide ions to iron ions of 1.4:1. Overall results indicate that the saturation magnetization is directly related to the particle size. - Highlights: • We model the impact of synthesis parameters in the Massart process. • Optimization of synthesis parameters according to particle size and magnetization. • Particles are fully characterized with XRD, TEM and SQUID magnetometry.

  20. Separation of Zinc and Cobalt from Dilute Sulfate Solution by Oxidation Precipitation%氧化沉淀法从稀溶液中分离锌钴

    Institute of Scientific and Technical Information of China (English)

    徐晓辉; 常耀超; 王云; 靳冉公

    2013-01-01

    以过硫酸钠为氧化剂,采用氧化沉淀法从除铁后液中分离锌钴,探讨了各因素对氧化沉淀的影响.结果表明,在过硫酸钠用量为钴理论耗量4倍、温度80℃、pH4.8~5.0、氧化时间3h的最佳条件下,钴完全氧化沉淀,酸洗后渣中钴含量达15.6%,钴富集了近9倍.沉钴后液用碳酸钠中和沉淀可得到含锌51.78%的碱式碳酸锌.%A new process of oxidation precipitation was developed to separate cobalt from dilute zinc-bearing deironing solution with sodium persulfate as oxidant.The effects of parameters on oxidative precipitation rate of metals were investigated.The results show that after acid washing cobalt content in residue is 15.6% which is nearly 9 times to that in existing residue under the optimum conditions including dosage of sodium persulfate of 4 times of theoretical cobalt consumptions,temperature of 80 ℃,pH of 4.8~5.0,and oxidation time of 3 h.Post-precipitation solution containing exclusively zinc can be neutralized by sodium carbonate to precipitate basic zinc carbonate product with zinc content of 51.78 %.

  1. Theory and experiment on the cuprous-cupric electron transfer rate at a copper electrode.

    Energy Technology Data Exchange (ETDEWEB)

    Halley, J. W.; Smith, B. B.; Walbran, S.; Curtiss, L. A.; Rigney, R. O.; Sutjianto, A.; Hung, N. C.; Yonco, R. M.; Nagy, Z.; Univ. of Minnesota; NREL

    1999-04-01

    We describe results of experiment and theory of the cuprous-cupric electron transfer rate in an aqueous solution at a copper electrode. The methods are similar to those we reported earlier for the ferrous-ferric rate. The comparison strongly suggests that, in marked distinction to the ferrous-ferric case, the electron transfer reaction is adiabatic. The model shows that the activation barrier is dominated by the energy required for the ion to approach the electrode, rather than by the energy required for rearrangement of the solvation shell, also in sharp distinction to the case of the ferric-ferrous electron transfer at a gold electrode. Calculated activation barriers based on this image agree with the experimental results reported here.

  2. Theory and experiment on the cuprous{endash}cupric electron transfer rate at a copper electrode

    Energy Technology Data Exchange (ETDEWEB)

    Halley, J.W. [School of Physics and Astronomy, University of Minnesota, Minneapolis, Minnesota 55455 (United States); Smith, B.B. [National Renewable Energy Laboratory, Golden, Colorado (United States); Walbran, S. [School of Physics and Astronomy, University of Minnesota, Minneapolis, Minnesota 55455 (United States); Curtiss, L.A.; Rigney, R.O.; Sutjianto, A.; Hung, N.C.; Yonco, R.M.; Nagy, Z. [Argonne National Laboratory, Divisions of Materials Science, Chemistry and Chemical Technology, Argonne, Illinois 60439-4837 (United States)

    1999-04-01

    We describe results of experiment and theory of the cuprous{endash}cupric electron transfer rate in an aqueous solution at a copper electrode. The methods are similar to those we reported earlier for the ferrous{endash}ferric rate. The comparison strongly suggests that, in marked distinction to the ferrous{endash}ferric case, the electron transfer reaction is adiabatic. The model shows that the activation barrier is dominated by the energy required for the ion to approach the electrode, rather than by the energy required for rearrangement of the solvation shell, also in sharp distinction to the case of the ferric{endash}ferrous electron transfer at a gold electrode. Calculated activation barriers based on this image agree with the experimental results reported here. {copyright} {ital 1999 American Institute of Physics.}

  3. Precipitation of iron (III) using magnesium oxide in fluidized bed; Precipitacion de hierro (III) utilizando oxido de magnesio en lecho fluidizado

    Energy Technology Data Exchange (ETDEWEB)

    Esteban-Bocardo, P. A.; Ferreira-Rocha, S. D.

    2006-07-01

    A process for iron (III) removal by hydroxide precipitation from and acid synthetic inorganic effluent using magnesium oxide as an alternative precipitant agent in a fluidized bed was developed. An acid synthetic inorganic effluent containing 100 and 200 mg/l of ferric ions (pH=1.0) was continuously fed up to the acrylic column (30 cm high and 2 cm diameter) during 180 minutes. Magnesium oxide pulp (3% v/v) was injected at the beginning of the experiment in order to allow the iron hydroxides precipitation. The concentration and pH profiles agreed in their curves, while the pH profile rose,the concentration profile decreased and a high percentage of iron removal (higher to 99%) was reached. Extremely low iron concentrations have been reached, thus permitting to attend to the environmental standard of 10.0 mg/l for discharge of effluent containing ferric ions established by the law DN 10/86 of COPAM (Conselho de Politica Ambiental do Estado de Minas Gerais-Brazil). (Author)

  4. 超声沉淀法合成氧化锌纳米粉体%Synthesis of Zinc Oxide Nanometer Powder with Precipitation under Ultrasonic Radiation

    Institute of Scientific and Technical Information of China (English)

    李东升; 王文亮; 杨文选

    2000-01-01

      分别采用超声沉淀法和沉淀法制备了氧化锌纳米粉体。借助XRD、TG-DTA、TEM及IR等技术对粉体前驱物的结构、热分解历程及粉体性能进行了研究。结果表明,超声沉淀法合成的氧化锌纳米粉体外貌呈球形,平均晶粒尺寸约为20nm,且大小均匀,分散性好,明显优于普通沉淀法所得产物。%  Zinc oxide nanometer-sized powders were prepared by precipitation under ultrasonic radiation and precipitation methods, respectively. The structure and the thermal decomposition mechanism of the predecessors, and characteristics of the powders were investigated by XRD, TG--DTA, TEM and IR techniques. The results show that the Zinc oxide nanometer powders synthesized with precipitation under ultrasonic radiation have an average diameter of 20nm with sphere-shaped and good dispersity.

  5. LAB-SCALE DEMONSTRATION OF PLUTONIUM PURIFICATION BY ANION EXCHANGE, PLUTONIUM (IV) OXALATE PRECIPITATION, AND CALCINATION TO PLUTONIUM OXIDE TO SUPPORT THE MOX FEED MISSION

    Energy Technology Data Exchange (ETDEWEB)

    Crowder, M.; Pierce, R.

    2012-08-22

    H-Canyon and HB-Line are tasked with the production of PuO{sub 2} from a feed of plutonium metal. The PuO{sub 2} will provide feed material for the MOX Fuel Fabrication Facility. After dissolution of the Pu metal in H-Canyon, the solution will be transferred to HB-Line for purification by anion exchange. Subsequent unit operations include Pu(IV) oxalate precipitation, filtration and calcination to form PuO{sub 2}. This report details the results from SRNL anion exchange, precipitation, filtration, calcination, and characterization tests, as requested by HB-Line1 and described in the task plan. This study involved an 80-g batch of Pu and employed test conditions prototypical of HB-Line conditions, wherever feasible. In addition, this study integrated lessons learned from earlier anion exchange and precipitation and calcination studies. H-Area Engineering selected direct strike Pu(IV) oxalate precipitation to produce a more dense PuO{sub 2} product than expected from Pu(III) oxalate precipitation. One benefit of the Pu(IV) approach is that it eliminates the need for reduction by ascorbic acid. The proposed HB-Line precipitation process involves a digestion time of 5 minutes after the time (44 min) required for oxalic acid addition. These were the conditions during HB-line production of neptunium oxide (NpO{sub 2}). In addition, a series of small Pu(IV) oxalate precipitation tests with different digestion times were conducted to better understand the effect of digestion time on particle size, filtration efficiency and other factors. To test the recommended process conditions, researchers performed two nearly-identical larger-scale precipitation and calcination tests. The calcined batches of PuO{sub 2} were characterized for density, specific surface area (SSA), particle size, moisture content, and impurities. Because the 3013 Standard requires that the calcination (or stabilization) process eliminate organics, characterization of PuO{sub 2} batches monitored the

  6. Oxidative lixiviation of pitchblende and precipitation of uranium with hydrogen; Lixiviation oxydante des pechblendes et precipitation de l'uranium par l'hydrogene

    Energy Technology Data Exchange (ETDEWEB)

    Mouret, P. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires; Balaceanu, J.C.; Coussemant, F. [Institut Francais du Petrole (IFP), 92 - Rueil-Malmaison (France)

    1958-07-01

    Earlier work on the preparation of uranium by F.A. Forward and his colleagues has shown the possibilities presented by oxidative lixiviation of ores in a carbonate medium, and the catalytic reduction of uranyl carbonate solutions by hydrogen. The carbonate attack is of considerable interest because of the selectivity of the uranium dissolution, which means it can be applied particularly to the treatment of low grade ores with a reduced consumption of cheap reagents. The subsequent reduction with hydrogen is of the same nature, and not only enables relatively dilute uranyl carbonate solutions to be treated, but also avoids any significant alteration of the attacking solution which can therefore be used again in the lixiviation stage. The experimental work, undertaken at the request of the Commissariat a I'Energie Atomique, was aimed at determining the quantitative characteristics of each of the two stages in order to ascertain their possibilities for industrial application to the principal low grade ores found in France. (author) [French] Les travaux anterieurs de F.A. FORWARD et de ses collaborateurs ont mis en evidence les possibilites que presentent, dans la preparation de l'uranium, la lixiviation oxydante des minerais en milieu carbonate, et la reduction catalytique des solutions d'uranyl carbonate par l'hydrogene. L'attaque carbonatee presente, en effet, un interet considerable du fait de la selectivite de la dissolution de l'uranium qui permet de l'appliquer en particulier au traitement des minerais pauvres avec une consommation reduite de reactifs peu couteux. La reduction subsequente par l'hydrogene presente les memes caracteres et permet non seulement de traiter des solutions relativement diluees d'uranyl carbonate, mais encore evite toute modification significative de la solution d'attaque qui peut donc etre reemployee dans l'etape de lixiviation. L'experimentation, entreprise a la demande du

  7. Ultrasound, its effects on ADU precipitation as precursor of uranium oxides; Ultrasonido, sus efectos en la precipitacion de ADU como precursor de oxidos de uranio

    Energy Technology Data Exchange (ETDEWEB)

    Mendez de Leo, Lucila; Sassone, Ariel; Novara, Oscar; Boero, Norma [Comision Nacional de Energia Atomica, Buenos Aires (Argentina). Planta de Fabricacion de Polvos de Uranio

    1999-11-01

    Ammonium poliuranate (ADU) is used as precursor of uranium oxides which are used as fuel for research reactors. The morphology of the oxides depends strongly on the structure of ADU. In this work we study the effect of acoustic energy of high frequency (ultrasound), on ADU precipitation for the obtention of U{sub 3} O{sub 8} and U O{sub 2}. Ultrasound changes ADU`s crystalline structure allowing the performance of a controlled precipitation. Experiences have been performed varying the times of ULTRASOUND appliance. X - Ray studies sustained the crystalline structure change. The difference in the state of agglomeration of particles was observed by electron scanning microscopy. This characteristic is maintained throughout the different thermal treatment performed on the powders (calcination at 800 deg C for U{sub 3} O{sub 8}, and 700 deg C in N{sub 2} - H{sub 2} atmosphere for U O{sub 2}). The oxides were characterized measuring specific area and particle size distribution. The results were good, being the change in the agglomeration state and ADU`s formula the most important features. (author) 5 refs., 4 figs., 2 tabs.

  8. Gas sensitivity and photocatalytic performance of cuprous oxide with novel morphologies

    Science.gov (United States)

    Wu, Ling; Wu, Yulin; Jin, Saijia; Zhang, Lun; Xun, Zhipeng

    2016-10-01

    In this work, Cu2O nanoparticles (NPs) with quasi-spherical and bookmark-like morphologies were successfully synthesized via a new facile solution method. The morphologies of products were characterized to show porous surfaces and the size is as small as approximately 20-50 nm. Given the special morphology, Cu2O NPs exhibited superior gas sensitivity to either ethanol or acetone vapors and strong adsorption abilities and high degradation activities for methyl orange under visible-light irradiation. The investigation provided not only a way of synthesizing Cu2O particles with dozens of nanoscale, but also a way of improving its gas sensitivity and catalytic degradation ability.

  9. Efficient visible-light photocatalytic performance of cuprous oxide porous nanosheet arrays

    Energy Technology Data Exchange (ETDEWEB)

    Li, Xianghua; Wang, Jianqiang [Key Laboratory of Cluster Science, Ministry of Education of China, Beijing Key Laboratory of Photoelectronic/Electrophotonic Conversion Materials, Department of Chemistry, Beijing Institute of Technology, Beijing 100081 (China); Zhang, Yihe [Beijing Key Laboratory of Mineral Materials and Utilization of Solid Waste, National Laboratory of Mineral Materials, School of Materials Sciences and Technology, China University of Geosciences, Beijing 100083 (China); Cao, Minhua, E-mail: caomh@bit.edu.cn [Key Laboratory of Cluster Science, Ministry of Education of China, Beijing Key Laboratory of Photoelectronic/Electrophotonic Conversion Materials, Department of Chemistry, Beijing Institute of Technology, Beijing 100081 (China)

    2015-10-15

    Graphical Abstract: We demonstrated a facile and efficient process for fabricating Cu{sub 2}O porous nanosheet arrays on Cu mesh. Benefiting from the 1D array structure and porous structure, the as-prepared Cu{sub 2}O sample exhibited significantly improved photocatalytic activity for methyl orange degradation under visible light irradiation. - Highlights: • Cu{sub 2}O porous nanosheet arrays on Cu mesh were synthesized via the facile and efficient process. • The Cu{sub 2}O sample exhibited the 1D array structure and porous nanosheet morphology. • The as-prepared Cu{sub 2}O porous nanosheet arrays exhibited significantly improved photocatalytic activity. - Abstract: One-dimensional nanostructures are of great interest for a wide range of applications. In this work, we demonstrated the fabrication of visible-light-responsive Cu{sub 2}O porous nanosheet arrays. The synthesis involved the growth of Cu(OH){sub 2} nanosheet arrays on Cu mesh by solution-based corrosion and thermal transformation of Cu(OH){sub 2} nanosheet to Cu{sub 2}O porous nanosheets on Cu mesh. Benefiting from the one dimensional array structure and porous structure, the as-prepared Cu{sub 2}O porous nanosheet arrays exhibited significantly improved photocatalytic activity for methyl orange degradation under visible light irradiation.

  10. Light-Induced Reduction of Cuprous Oxide in an Environmental Transmission Electron Microscope

    DEFF Research Database (Denmark)

    Cavalca, Filippo Carlo; Laursen, Anders Bo; Wagner, Jakob Birkedal

    2013-01-01

    . Environmental transmission electron microscopy (ETEM) makes it possible to obtain insight into the local structure, composition and reactivity of catalysts in their working environment, which is of fundamental interest for sustainable energy research and is essential for further material optimization. Herein...

  11. Enormous excitonic effects in bulk, mono- and bi- layers of cuprous halides using many-body perturbation technique

    Science.gov (United States)

    Azhikodan, Dilna; Nautiyal, Tashi

    2017-10-01

    Cuprous halides (CuX with X = Cl, Br, I), intensely studied about four decades ago by experimentalists for excitons, are again drawing attention of researchers recently. Potential of cuprous halide systems for device applications has not yet been fully explored. We go beyond the one-particle picture to capture the two-particle physics (electron-hole interaction to form excitons). We have deployed the full tool kit of many-body perturbation technique, GW approximation + Bethe Salpeter equation, to unfurl the rich excitonic physics of the bulk as well as layers of CuX. The negative spin-orbit contribution at the valence band top in CuCl, compared to CuBr and CuI, is in good agreement with experiments. We note that CuX have exceptionally strong excitons, defying the linear fit (between the excitonic binding energy and band gap) encompassing many semiconductors. The mono- and bi- layers of cuprous halides are predicted to be rich in excitons, with exceptionally large binding energies and the resonance energies in UV/visible region. Hence this work projects CuX layers as good candidates for optoelectronic applications. With advancement of technology, we look forward to experimental realization of CuX layers and harnessing of their rich excitonic potential.

  12. The magnetic and oxidation behavior of bare and silica-coated iron oxide nanoparticles synthesized by reverse co-precipitation of ferrous ion (Fe{sup 2+}) in ambient atmosphere

    Energy Technology Data Exchange (ETDEWEB)

    Mahmed, N., E-mail: norsuria.mahmed@aalto.fi [Aalto University School of Chemical Technology, Department of Materials Science and Engineering, P.O. Box 16200, FI-00076 Aalto (Finland); School of Materials Engineering, Kompleks Pusat Pengajian UniMAP, Taman Muhibbah, Universiti Malaysia Perlis, 02600 Jejawi, Perlis (Malaysia); Heczko, O., E-mail: heczko@fzu.cz [Institute of Physics, Academy of Sciences, Czech Republic Na Slovance 2, CZ-182 21 Praha 8 (Czech Republic); Lancok, A., E-mail: Lancok@seznam.cz [Institute of Physics, Academy of Sciences, Czech Republic Na Slovance 2, CZ-182 21 Praha 8 (Czech Republic); Hannula, S-P., E-mail: simo-pekka.hannula@aalto.fi [Aalto University School of Chemical Technology, Department of Materials Science and Engineering, P.O. Box 16200, FI-00076 Aalto (Finland)

    2014-03-15

    The synthesis of iron oxide nanoparticles, i.e., magnetite was attempted by using only ferrous ion (Fe{sup 2+}) as a magnetite precursor, under an ambient atmosphere. The room temperature reverse co-precipitation method was used, by applying two synthesis protocols. The freshly prepared iron oxide was also immediately coated with Stöber silica (SiO{sub 2}) layer, forming the coreshell structure. The phase, stoichiometry, crystallite and the particle size of the synthesized powders were determined by using X-ray diffraction (XRD) and transmission electron microscope (TEM), while the magnetic and oxidation behaviors were studied by using the vibrating sample magnetometer (VSM) and Mössbauer spectroscopy. Based on the results, the bare iron oxide nanoparticles are in the stoichiometry between the magnetite and the maghemite stoichiometry, i.e., oxidation occurs. This oxidation is depending on the synthesis protocols used. With the silica coating, the oxidation can be prevented, as suggested by the fits of Mössbauer spectra and low temperature magnetic measurement. - Highlights: • Synthesis of magnetite was attempted by using ferrous ion (Fe{sup 2+}) in air. • The synthesized particle has a stoichiometry in between magnetite and maghemite. • Silica shell partly prevented the oxidation as suggested by magnetic and Mössbauer study.

  13. Catalytic Oxidation of Propylene, Toluene, Carbon Monoxide, and Carbon Black over Au/CeO2 Solids: Comparing the Impregnation and the Deposition-Precipitation Methods

    Directory of Open Access Journals (Sweden)

    Antoine Aboukaïs

    2013-01-01

    Full Text Available Au/CeO2 solids were prepared by two methods: deposition-precipitation (DP and impregnation (Imp. The prepared solids were calcined under air at 400°C. Both types of catalysts have been tested in the total oxidation of propylene, toluene, carbon monoxide, and carbon black. Au/CeO2-DP solids were the most reactive owing to the high number of gold nanoparticles and Au+ species and the low concentration of Cl- ions present on its surface compared to those observed in Au/CeO2-Imp solids.

  14. Fe hydroxyphosphate precipitation and Fe(II) oxidation kinetics upon aeration of Fe(II) and phosphate-containing synthetic and natural solutions

    Science.gov (United States)

    van der Grift, B.; Behrends, T.; Osté, L. A.; Schot, P. P.; Wassen, M. J.; Griffioen, J.

    2016-08-01

    Exfiltration of anoxic Fe-rich groundwater into surface water and the concomitant oxidative precipitation of Fe are important processes controlling the transport of phosphate (PO4) from agricultural areas to aquatic systems. Here, we explored the relationship between solution composition, reaction kinetics, and the characteristics of the produced Fe hydroxyphosphate precipitates in a series of aeration experiments with anoxic synthetic water and natural groundwater. A pH stat device was used to maintain constant pH and to record the H+ production during Fe(II) oxidation in the aeration experiments in which the initial aqueous P/Fe ratios ((P/Fe)ini), oxygen concentration and pH were varied. In general, Fe(II) oxidation proceeded slower in the presence of PO4 but the decrease of the PO4 concentration during Fe(II) oxidation due to the formation of Fe hydroxyphosphates caused additional deceleration of the reaction rate. The progress of the reaction could be described using a pseudo-second-order rate law with first-order dependencies on PO4 and Fe(II) concentrations. After PO4 depletion, the Fe(II) oxidation rates increased again and the kinetics followed a pseudo-first-order rate law. The first-order rate constants after PO4 depletion, however, were lower compared to the Fe(II) oxidation in a PO4-free solution. Hence, the initially formed Fe hydroxyphosphates also affect the kinetics of continuing Fe(II) oxidation after PO4 depletion. Presence of aqueous PO4 during oxidation of Fe(II) led to the formation of Fe hydroxyphosphates. The P/Fe ratios of the precipitates ((P/Fe)ppt) and the recorded ratio of H+ production over decrease in dissolved Fe(II) did not change detectably throughout the reaction despite a changing P/Fe ratio in the solution. When (P/Fe)ini was 0.9, precipitates with a (P/Fe)ppt ratio of about 0.6 were formed. In experiments with (P/Fe)ini ratios below 0.6, the (P/Fe)ppt decreased with decreasing (P/Fe)ini and pH value. Aeration experiments with

  15. Simultaneous determination of seven impurities in high-purity cobalt oxide by ICP-AES after matrix separation using 1-nitroso-2-naphthol as a precipitant

    Institute of Scientific and Technical Information of China (English)

    王艳; 周春山; 段青兵; 陈萍

    2002-01-01

    A method was developed for the simultaneous determination of seven trace impurities (Cd, Mn, Pb, Zn, Cu, Fe and Ni) in high-purity cobalt oxide by ICP-AES. The matrix effect was eliminated by preci- pitation with 1-nitroso-2-naphthol. The matrix effect of cobalt on the absorptions of trace impurities, the effects of reaction time, pH value, dosage of precipitant on the formation of cobalt-1-nitroso-2-naphthol complex, the effects of hydrochloric acid on the stability of this complex and masking of elements were studied. Recoveries of the impurities in spiked sample are from 90% to 110% with a precision of 1.1%-5.0% RSD. The detection limits of the seven elements are in the range of 0.01-0.24μg/g. The method can be applied to the analysis of high-purity cobalt metal, cobalt oxide and other cobalt compounds.

  16. Simultaneous stripping recovery of ammonia-nitrogen and precipitation of manganese from electrolytic manganese residue by air under calcium oxide assist.

    Science.gov (United States)

    Chen, Hongliang; Liu, Renlong; Shu, Jiancheng; Li, Wensheng

    2015-01-01

    Leaching tests of electrolytic manganese residue (EMR) indicated that high contents of soluble manganese and ammonia-nitrogen posed a high environmental risk. This work reports the results of simultaneous stripping recovery of ammonia-nitrogen and precipitation of manganese by air under calcium oxide assist. The ammonia-nitrogen stripping rate increased with the dosage of CaO, the air flow rate and the temperature of EMR slurry. Stripped ammonia-nitrogen was absorbed by a solution of sulfuric acid and formed soluble (NH4)2SO4 and (NH4)3H(SO4)3. The major parameters that effected soluble manganese precipitation were the dosage of added CaO and the slurry temperature. Considering these two aspects, the efficient operation conditions should be conducted with 8 wt.% added CaO, 60°C, 800 mL min(-1) air flow rate and 60-min reaction time. Under these conditions 99.99% of the soluble manganese was precipitated as Mn3O4, which was confirmed by XRD and SEM-EDS analyses. In addition, the stripping rate of ammonia-nitrogen was 99.73%. Leaching tests showed the leached toxic substances concentrations of the treated EMR met the integrated wastewater discharge standard of China (GB8978-1996).

  17. The use of trimethylamine N-oxide as a primary precipitating agent and related methylamine osmolytes as cryoprotective agents for macromolecular crystallography

    Energy Technology Data Exchange (ETDEWEB)

    Marshall, Haley; Venkat, Murugappan; Hti Lar Seng, Nang San; Cahn, Jackson [Whitman College, Walla Walla, Washington (United States); Juers, Douglas H., E-mail: juersdh@whitman.edu [Whitman College, Walla Walla, Washington (United States); Whitman College, Walla Walla, Washington (United States)

    2012-01-01

    The stabilizing osmolyte trimethylamine N-oxide (TMAO) is shown to be an efficient primary precipitant for protein crystal growth. In addition to TMAO, two other methylamine osmolytes, sarcosine and betaine, are shown to be effective cryoprotective agents for protein crystal cooling. Both crystallization and cryoprotection are often bottlenecks for high-resolution X-ray structure determination of macromolecules. Methylamine osmolytes are known stabilizers of protein structure. One such osmolyte, trimethylamine N-oxide (TMAO), has seen occasional use as an additive to improve macromolecular crystal quality and has recently been shown to be an effective cryoprotective agent for low-temperature data collection. Here, TMAO and the related osmolytes sarcosine and betaine are investigated as primary precipitating agents for protein crystal growth. Crystallization experiments were undertaken with 14 proteins. Using TMAO, seven proteins crystallized in a total of 13 crystal forms, including a new tetragonal crystal form of trypsin. The crystals diffracted well, and eight of the 13 crystal forms could be effectively cryocooled as grown with TMAO as an in situ cryoprotective agent. Sarcosine and betaine produced crystals of four and two of the 14 proteins, respectively. In addition to TMAO, sarcosine and betaine were effective post-crystallization cryoprotective agents for two different crystal forms of thermolysin. Precipitation reactions of TMAO with several transition-metal ions (Fe{sup 3+}, Co{sup 2+}, Cu{sup 2+} and Zn{sup 2+}) did not occur with sarcosine or betaine and were inhibited for TMAO at lower pH. Structures of proteins from TMAO-grown crystals and from crystals soaked in TMAO, sarcosine or betaine were determined, showing osmolyte binding in five of the 12 crystals tested. When an osmolyte was shown to bind, it did so near the protein surface, interacting with water molecules, side chains and backbone atoms, often at crystal contacts.

  18. Influences of pH value in deposition-precipitation synthesis process on Pt-doped TiO2 catalysts for photocatalytic oxidation of NO

    Institute of Scientific and Technical Information of China (English)

    Shuzhen Song; Zhongyi Sheng; Yue Liu; Haiqiang Wang; Zhongbiao Wu

    2012-01-01

    This work has been undertaken to study the influences of pH value on the characteristics and activity of photocatalyst by deposition-precipitation method during its preparation process.A series of Pt-modified TiO2 were prepared by deposition-precipitation method at different pH values as well as wet impregnation method,and characterized by XRD,XPS,TEM,UV-Vis and photoluminescence(PL).It was found that the catalysts had the highest photocatalytic activity for NO conversion when pH value was kept at around 7.And the sample prepared by deposition-precipitation method showed higher activity than that by impregnation method.This was mainly due to their high value in highly-dispersed platinum oxides(PtOx)content on the surface of the catalysts.The results from UV-Vis absorption showed that highest absorbance was obtained for Pt/TiO2 prepared at pH values of around 7.And PL spectra results indicated that the recombination rate of photogenerated electrons and holes of the samples prepared by deposition-precipitation method was lower than that prepared by impregnation method.And in the zeta potential study,the pH values for the isoelectric point of the preparing slurry of 0.05 wt.%Pt/TiO2 and 0.5 wt.%Pt/TiO2 were determined to be 6.5-8.5,which further confirmed the enrichment of PtOx dopants for the catalysts repapered when pH value was around 7.

  19. Comparison of Poly Aluminum Chloride and Chlorinated Cuprous for Chemical Oxygen Demand and Color Removal from Kashan Textile Industries Company Wastewater

    Directory of Open Access Journals (Sweden)

    Hoseindoost Gh.1 MSPH,

    2016-08-01

    Full Text Available Aims Textile wastewaters are the most important health and environmental problems in Kashan. This research was aimed to compare the poly aluminum chloride and chlorinated cuprous efficiency for removal of Chemical Oxygen Demand (COD and color from Kashan Textile Industries Company wastewater. Materials & Methods This experimental bench scale study in a batch system was conducted on 20 composed wastewater samples collected from Kashan Textile Industries Company raw wastewater. During 5 months, in the beginning of every week a day was selected randomly and in the day a composed sample was taken and studied. PAC at the doses of 10, 20, 30, 40 and 50mg.l-1 and chlorinated cuprous at the doses of 100, 200, 300, 400 and 500mg.l-1 were applied. The optimum pH also optimum concentration of PAC and chlorinated cuprous were determined using Jar test. The data was analyzed by SPSS 16 using descriptive statistics and Fisher Exact test. Findings The average concentration of COD in the raw textile wastewater was 2801.56±1398.29mg.l-1. The average COD concentration has been decreased to 1125.47±797.55mg.l-1. There was a significant difference between the effects of these two coagulants efficiency (p<0.05. The average COD removal efficiency for chlorinated cuprous and PAC was 58.52% and 72.56%, respectively. Also, the average color removal efficiency by chlorinated cuprous and PAC were 17.23 and 64.45%, respectively. Conclusion PAC is more efficient than chlorinated cuprous for both COD and color removal from KTIC wastewater.

  20. Aquifer Thermal Energy Storage as an ecosystem service for Brussels, Belgium: investigating iron (hydr)oxide precipitation with reactive transport modeling

    Science.gov (United States)

    Anibas, Christian; Possemiers, Mathias; Huysmans, Marijke

    2016-04-01

    In an evolving energy system it is important that urbanized areas contribute to their own energy demands. To reduce greenhouse gas emissions sustainable energy systems with a high efficiency are required, e.g. using urban aquifers as an ecosystem service. Here the potential of seasonal aquifer thermal energy storage and recovery (ATES) for the Brussels-Capital Region, Belgium is investigated. An important shallow geologic formation in the Brussels Capital Region is the Brussels Sand formation, a 20-60 m thick phreatic aquifer. The Brussels Sand Formation is known for its potential for ATES systems, but also for its varying redox and hydraulic conditions. Important limiting factors for ATES systems in the Brussels Sand Formation therefore are the hydraulic conductivity and the geochemical composition of the groundwater. Near the redox boundary iron hydroxide precipitation can negatively influence ATES well performance due to clogging. The interactions between physical processes (e.g. particle transport and clogging in the wider proximity of the ATES well) and chemical processes (e.g. influence of the operation temperatures on precipitation processes) during ATES operation are complex but not well understood. Therefore we constructed numerical groundwater flow models in MODFLOW to estimate maximum pumping and injection rates of different hydraulic conditions and competing water uses in the Brussels Sand Formation. In further steps the thermal potential for ATES was quantified using MT3DMS and the reactive transport model PHT3D was applied to assess the effects of operating ATES systems near the redox boundary. Results show that initial mixing plays an important role in the development of iron(hydr)oxide precipitation around the ATES wells, with the highest concentrations around the cold wells. This behavior is enhanced by the temperature effect; temperature differences of ΔT≈10°C already influence the iron (hydr)oxide concentration. The initial injection into the

  1. Fabrication of cuprous chloride films on copper substrate by chemical bath deposition

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Yu-Ting; Ci, Ji-Wei; Tu, Wei-Chen [Department of Electronic Engineering, College of Electrical Engineering and Computer Science, Chung Yuan Christian University, Chung-Li 32023, Taiwan (China); Uen, Wu-Yih, E-mail: uenwuyih@ms37.hinet.net [Department of Electronic Engineering, College of Electrical Engineering and Computer Science, Chung Yuan Christian University, Chung-Li 32023, Taiwan (China); Lan, Shan-Ming [Department of Electronic Engineering, College of Electrical Engineering and Computer Science, Chung Yuan Christian University, Chung-Li 32023, Taiwan (China); Yang, Tsun-Neng; Shen, Chin-Chang; Wu, Chih-Hung [Institute of Nuclear Energy Research, P.O. Box 3-11, Lungtan 32500, Taiwan (China)

    2015-09-30

    Polycrystalline CuCl films were fabricated by chemical bath deposition (CBD) on a Cu substrate at a low solution temperature of 90 °C. Continuous CuCl films were prepared using the copper (II) chloride (CuCl{sub 2}) compound as the precursor for both the Cu{sup 2+} and Cl{sup −} sources, together with repeated HCl dip treatments. An HCl dip pretreatment of the substrate favored the nucleation of CuCl crystallites. Further, interrupting the film deposition and including an HCl dip treatment of the film growth surface facilitated the deposition of a full-coverage CuCl film. A dual beam (FIB/SEM) system with energy dispersive spectrometry facilities attached revealed a homogeneous CuCl layer with a flat-top surface and an average thickness of about 1 μm. Both the excitonic and biexcitonic emission lines were well-resolved in the 6.4 K photoluminescence spectra. In particular, the free exciton emission line was observable at room temperature, indicating the good quality of the CuCl films prepared by CBD. - Highlights: • Cuprous chloride (CuCl) was prepared on Cu substrate by chemical bath deposition. • HCl dip treatments facilitated the deposition of a full-coverage CuCl film. • A homogeneous elemental distribution was recognized for the deposited CuCl layer. • Excitonic and biexcitonic photoluminescence lines of CuCl films were well-resolved. • The free exciton emission line of CuCl films was observable at room temperature.

  2. Novel doxorubicin loaded PEGylated cuprous telluride nanocrystals for combined photothermal-chemo cancer treatment.

    Science.gov (United States)

    Wang, Xianwen; Ma, Yan; Chen, Huajian; Wu, Xiaoyi; Qian, Haisheng; Yang, Xianzhu; Zha, Zhengbao

    2017-02-06

    Recently, combined photothermal-chemo therapy has attracted great attention due to its enhanced anti-tumor efficiency via synergistic effects. Herein, PEGylated cuprous telluride nanocrystals (PEGylated Cu2Te NCs) were developed as novel drug nanocarriers for combined photothermal-chemo treatment of cancer cells. PEGylated Cu2Te NCs were fabricated through a simple two-step process, comprised of hot injection and thin-film hydration. The as-prepared PEGylated Cu2Te NCs (average diameter of 5.21±1.05nm) showed a noticeable photothermal conversion efficiency of 33.1% and good capacity to load hydrophobic anti-cancer drug. Due to the protonated amine group at low pH, the doxorubicin (DOX)-loaded PEGylated Cu2Te NCs (PEGylated Cu2Te-DOX NCs) exhibited an acidic pH promoted drug release profile. Moreover, a three-parameter model, which considers the effects of drug-carrier interactions on the initial burst release and the sustained release of drug from micro- and nano-sized carriers, was used to gain insight into how pH and laser irradiation affect drug release from PEGylated Cu2Te-DOX NCs. Based on the results from in vitro cell study, PEGylated Cu2Te-DOX NCs revealed remarkably photothermal-chemo synergistic effect to HeLa cells, attributed to both the PEGylated Cu2Te NCs mediated photothermal ablation and enhanced cellular uptake of the drug. Thus, our results encourage the usage of Cu2Te-DOX drug nanocarriers for enhanced treatment of cancer cells by combined photothermal-chemo therapy.

  3. Effect of zinc oxide nanoparticles synthesized by a precipitation method on mechanical and morphological properties of the CR foam

    Indian Academy of Sciences (India)

    Rudeerat Suntako

    2015-08-01

    ZnO nanoparticles were synthesized by a precipitation method in aqueous media from zinc nitrate hexahydrate and sodium hydroxide. The synthesized ZnO nanoparticles exhibited a crystalline structure with hexagonal structure of the wurtzite. The morphology of the synthesized ZnO nanoparticles presented a spherical shape with the average primary size of 54.53 nm and the specific surface area of 20.28 m2 g−1. The effect of the synthesized ZnO nanoparticles by the precipitation method as a crosslinking agent for chloroprene rubber foam (CR foam) on cure characteristics, mechanical properties and morphologies was investigated. The aim of this study is to vary the synthesized ZnO nanoparticles’ level in the range of 0.5–5 parts per hundred parts of rubber (phr) compared with the conventional ZnO at 5 phr. The rheological characterization showed that the maximum torque (H), the minimum torque (L), the differential torque (H–L) and Mooney viscosity increased with the increase in synthesized ZnO nanoparticles’ content, whereas the optimum cure time (90) and scorch time (5) decreased. On the other hand, the mechanical properties such as hardness, tensile strength and specific gravity were improved. For CR foam, the results compared to the amount of conventional ZnO, only 60 wt% (3 phr) nano-ZnO was enough to obtain similar cure characteristics and mechanical properties. The synthesized ZnO nanoparticles showed the mechanical properties higher than conventional ZnO because of small particle size and large specific surface area which led to the increase in the degree of crosslinking.

  4. 沉淀法制备纳米ZnO超细粉体%Preparation of Superfine Particles of Zinc Oxide by Precipitation Method

    Institute of Scientific and Technical Information of China (English)

    徐华军; 朱振中; 等

    2001-01-01

    以硝酸锌、碳酸钠为原料,通过在沉淀反应中加入表面活性剂的方法制备出ZnO超细粉体.讨论了制备过程中Zn2+浓度、反应物配比、表面活性剂的浓度和种类对ZnO粉体平均粒径的影响,并对其作用机理进行了分析.试验结果表明:在阴离子表面活性剂的作用下得到的沉淀粒子于450 ℃热分解3 h,得到的ZnO粉体的晶体尺寸约为50 nm左右.%Zinc oxide nanoparticles were prepared by using zinc nitrate and natrium carbonate as the starting materials. The crystalloid growth of precipitated zinc carbonate hydroxide precursor was inhabited by adding surfactants during the precipitation process. The effects on the average diameter of ZnO crystals of the Zn2+ concentration, mixing ratio of reactants and the concentration, the types of surfactants were discussed. The mechanism of inhabitation on the crystalloid growth was also analyzed. The results indicated that the particle size of ZnO at 450 ℃, 3 h was about 50 nm.

  5. Electrochemical synthesis and characterization of copper (I oxide

    Directory of Open Access Journals (Sweden)

    Bugarinović Sanja J.

    2009-01-01

    Full Text Available The quest and need for clean and economical energy sources have increased interest in the development of thin film cells technologies. Electrochemical deposition is an attractive method for synthesis of thin films. It offers the advantages of low synthesis temperature, low cost and high purity. Copper (I oxide or cuprous oxide is an oxide semiconductor which is used as the anodic material in the form of thin film in lithium batteries and solar cells. The cathodic process of synthesis of cuprous oxide thin film is carried out in a potentiostatic mode from the organic electrolyte. The process parameters are chosen in that way to accomplish maximum difference between the potentials at which Cu2O and CuO are obtained. The electrochemical characterization was carried out by cyclic voltammetry. The electrodeposition techniques are particularly well suited for the deposition of single elements but it is also possible to carry out simultaneous depositions of several elements and syntheses of well-defined alternating layers of metals and oxides with thicknesses down to a few nm. Nanomaterials exhibit novel physical properties and play an important role in fundamental research. In addition, cuprous oxide is commonly used as a pigment, a fungicide, and an antifouling agent for marine paints. It is insoluble in water and organic solvents. This work presents the examinations of the influence of bath, temperature, pH and current density on the characteristics of electrochemically synthesized cuprous oxide. In the 'classic' process of synthesis, which is carried out under galvanostatic conditions on the anode, the grain size of the powder decreases with the increase in current density while the grain colour becomes lighter. The best commercial quality of the Cu2O (grain size, colour, content of choride was obtained at the temperature of 80°C, concentration of NaCl of 3 mol/dm3 and current density of 400 A/m2.

  6. Influência do agente precipitante na preparação do óxido de nióbio (V hidratado pelo método da precipitação em solução homogênea Influence of precipitating agent in the preparation of hydrous niobium oxide by the method of homogeneous precipitation

    Directory of Open Access Journals (Sweden)

    Geronimo Virginio Tagliaferro

    2005-03-01

    Full Text Available This work reports the preparation, characterization and study of the ion exchange behavior of hydrous niobium oxide prepared by a homogeneous precipitation method. The precipitating agent was obtained in aqueous solution by thermal decomposition of urea or ammonium carbonate. The compounds were chemically and physically characterized by X-ray diffractometry, thermal analysis (TG/DTG, surface area measurements and ion exchange behavior with sodium. The materials prepared with ammonium carbonate presented a higher degree of crystallinity and better ion exchange capacity with sodium than materials prepared with urea. In the homogeneous precipitation method, materials were obtained with specific surface area of 123 - 224 m² g-1. A variation of the preparation process produced hydrous niobium oxide with a different degree of hydration and specific surface area. This provided materials with different physico-chemical properties.

  7. Effect of Thermal Annealing on the Structural and Optical Properties Nanostructured Cobalt-Manganese and Cobalt-Nickel Oxides Prepared by Co-Precipitation

    Science.gov (United States)

    Indulal, C. R.; Kumar, G. Sajeev; Vaidyan, A. V.; Raveendran, R.

    2011-10-01

    Cobalt-Manganese and Cobalt-Nickel oxide (CoMnO and CoNiO) nanoparticles were synthesized via chemical co-precipitation method by decomposition of their respective metal sulfides and sodium carbonate using ethylene diamene tetra acetic acid as the capping agent. The samples were heated at 400, 600 and 800 °C. The average particle sizes were determined from the X-ray line broadening. The diffractogram were compared with JCPDS data to identify the crystallographic phase and cubic structure of the particles. The samples were characterized by XRD, FTIR and UV analyses. The internal elastic micro strains were calculated and it was seen that as the particle size increases strain decreases. The FTIR studies have been used to confirm the metal oxide formation. The chemical compositions of the samples were verified using EDX spectra. The surface morphologies of the samples were studied from the SEM images. The absorption spectra of the materials in the UV-Vis-NIR range were recorded. From the analysis of the absorption spectra, the direct band gaps of the materials were calculated.

  8. A possible evolutionary origin for the Mn4 cluster of the photosynthetic water oxidation complex from natural MnO2 precipitates in the early ocean

    Energy Technology Data Exchange (ETDEWEB)

    Sauer, Kenneth; Yachandra, Vittal K.

    2002-04-30

    The photosynthetic water oxidation complex consists of a cluster of 4 Mn atoms bridged by O atoms, associated with Ca2+ and Cl- and incorporated into protein. The structure is similar in higher plants and algae, as well as in cyanobacteria of more ancient lineage, dating back more than 2.5 Ga on Earth. It has been proposed that the proto-enzyme derived from a component of a natural early marine manganese precipitate that contained a CaMn4O9 cluster. A variety of MnO2 minerals is found in nature. Three major classes are spinels, sheet-like layered structures and 3-dimensional networks that contain parallel tunnels. These relatively open structures readily incorporate cations (Na+, Li+, Mg2+, Ca2+, Ba2+, H+ and even Mn2+) and water. The minerals have different ratios of Mn(III) and Mn(IV) octahedrally coordinated to oxygens. Using X-ray spectroscopy we compare the chemical structures of Mn in the minerals with what is known about the arrangement in the water-oxidation complex to define the parameters of a structural model for the photosynthetic catalytic site. This comparison provides for the structural model a set of candidate Mn4 clusters -- some previously proposed and considered and others entirely novel.

  9. Influence of 300 °C thermal conversion of Fe-Ce hydrous oxides prepared by hydrothermal precipitation on the adsorptive performance of five anions : Insights from EXAFS/XANES, XRD and FTIR (companion paper)

    NARCIS (Netherlands)

    Chubar, Natalia; Gerda, Vasyl; Banerjee, Dipanjan

    2017-01-01

    In this work, we report atomic-scale reconstruction processes in Fe-Ce oxide-based composites (hydrothermally precipitated at Fe-to-Ce dosage ratios of 1:0, 2:1, 1:1, 1:2, and 0:1), upon treatment at 300 °C. The structural changes are correlated with the adsorptive removal of arsenate, phosphate,

  10. Enhanced Al and Zn removal from coal-mine drainage during rapid oxidation and precipitation of Fe oxides at near-neutral pH

    Science.gov (United States)

    Burrows, Jill E.; Cravotta, Charles A.; Peters, Stephen C.

    2017-01-01

    Net-alkaline, anoxic coal-mine drainage containing ∼20 mg/L FeII and ∼0.05 mg/L Al and Zn was subjected to parallel batch experiments: control, aeration (Aer 1 12.6 mL/s; Aer 2 16.8 mL/s; Aer 3 25.0 mL/s), and hydrogen peroxide (H2O2) to test the hypothesis that aeration increases pH, FeII oxidation, hydrous FeIII oxide (HFO) formation, and trace-metal removal through adsorption and coprecipitation with HFO. During 5.5-hr field experiments, pH increased from 6.4 to 6.7, 7.1, 7.6, and 8.1 for the control, Aer 1, Aer 2, and Aer 3, respectively, but decreased to 6.3 for the H2O2 treatment. Aeration accelerated removal of dissolved CO2, Fe, Al, and Zn. In Aer 3, dissolved Al was completely removed within 1 h, but increased to ∼20% of the initial concentration after 2.5 h when pH exceeded 7.5. H2O2 promoted rapid removal of all dissolved Fe and Al, and 13% of dissolved Zn.Kinetic modeling with PHREEQC simulated effects of aeration on pH, CO2, Fe, Zn, and Al. Aeration enhanced Zn adsorption by increasing pH and HFO formation while decreasing aqueous CO2 available to form ZnCO30 and Zn(CO3)22− at high pH. Al concentrations were inconsistent with solubility control by Al minerals or Al-containing HFO, but could be simulated by adsorption on HFO at pH pH where Al(OH)4− was predominant. Thus, aeration or chemical oxidation with pH adjustment to ∼7.5 could be effective for treating high-Fe and moderate-Zn concentrations, whereas chemical oxidation without pH adjustment may be effective for treating high-Fe and moderate-Al concentrations.

  11. VOCs elimination and health risk reduction in e-waste dismantling workshop using integrated techniques of electrostatic precipitation with advanced oxidation technologies.

    Science.gov (United States)

    Chen, Jiangyao; Huang, Yong; Li, Guiying; An, Taicheng; Hu, Yunkun; Li, Yunlu

    2016-01-25

    Volatile organic compounds (VOCs) emitted during the electronic waste dismantling process (EWDP) were treated at a pilot scale, using integrated electrostatic precipitation (EP)-advanced oxidation technologies (AOTs, subsequent photocatalysis (PC) and ozonation). Although no obvious alteration was seen in VOC concentration and composition, EP technology removed 47.2% of total suspended particles, greatly reducing the negative effect of particles on subsequent AOTs. After the AOT treatment, average removal efficiencies of 95.7%, 95.4%, 87.4%, and 97.5% were achieved for aromatic hydrocarbons, aliphatic hydrocarbons, halogenated hydrocarbons, as well as nitrogen- and oxygen-containing compounds, respectively, over 60-day treatment period. Furthermore, high elimination capacities were also seen using hybrid technique of PC with ozonation; this was due to the PC unit's high loading rates and excellent pre-treatment abilities, and the ozonation unit's high elimination capacity. In addition, the non-cancer and cancer risks, as well as the occupational exposure cancer risk, for workers exposed to emitted VOCs in workshop were reduced dramatically after the integrated technique treatment. Results demonstrated that the integrated technique led to highly efficient and stable VOC removal from EWDP emissions at a pilot scale. This study points to an efficient approach for atmospheric purification and improving human health in e-waste recycling regions.

  12. Kilogram-scale synthesis of iron oxy-hydroxides with improved arsenic removal capacity: study of Fe(II) oxidation--precipitation parameters.

    Science.gov (United States)

    Tresintsi, Sofia; Simeonidis, Konstantinos; Vourlias, George; Stavropoulos, George; Mitrakas, Manassis

    2012-10-15

    Various iron oxy-hydroxides were synthesized in a continuous flow kilogram-scale production reactor through the precipitation of FeSO(4) and FeCl(2) in the pH range 3-12 under intense oxidative conditions to serve as arsenic adsorbents. The selection of the optimum adsorbent and the corresponding conditions of the synthesis was based not only on its maximum As(III) and As(V) adsorption capacity but also on its potential efficiency to achieve the arsenic health regulation limit in NSF challenge water. As a result, the adsorbent prepared at pH 4, which consists of schwertmannite, was selected because it exhibited the highest adsorption capacity of 13 μg As(V)/mg, while maintaining a residual arsenic concentration of 10 μg/L at an equilibrium pH 7. The high surface charge and the activation of an ion-exchange mechanism between SO(4)(2-) adsorbed in the Stern layer and arsenate ions were found to significantly contribute to the increased adsorption capacity. Adsorption capacity values observed in rapid scale column experiments illustrate the improved efficiency of the qualified adsorbent compared to the common commercial arsenic adsorbents.

  13. MnO(x)/TiO(2) composite nanoxides synthesized by deposition-precipitation method as a superior catalyst for NO oxidation.

    Science.gov (United States)

    Wu, Zhongbiao; Tang, Nian; Xiao, Ling; Liu, Yue; Wang, Haiqiang

    2010-12-01

    A series of MnO(x)/TiO(2) composite nanoxides were prepared by deposition-precipitation (DP) method, and the sample with the Mn/Ti ratio of 0.3 showed a superior activity for NO catalytic oxidation to NO(2). The maximum NO conversion over MnO(x)(0.3)/TiO(2)(DP) could reach 89% at 250°C with a GHSV of 25,000h(-1), which was much higher than that over the catalyst prepared by conventional wet-impregnation (WI) method (69% at 330°C). Characterization results including XRD, HRTEM, FTIR, XPS, H(2)-TPR, NO-TPD and Nitrogen adsorption-desorption implied that the higher activity of MnO(x)(0.3)/TiO(2)(DP) could be attributed to the enrichment of well-dispersed MnO(x) on the surface and the abundance of Mn(3+) species. Furthermore, DRIFT investigations and long-time running test indicated that NO(2) came from the decomposition of adsorbed nitrogen-containing species.

  14. Copper oxide as a high temperature battery cathode material

    Science.gov (United States)

    Ritchie, A. G.; Mullins, A. P.

    1994-10-01

    Copper oxide has been tested as a cathode material for high temperature primary reserve thermal batteries in single cells at 530 to 600 C and at current densities of 0.1 to 0.25 A cm(exp -2) using lithium-aluminium alloy anodes and lithium fluoride-lithium chloride-lithium bromide molten salt electrolytes. Initial on-load voltages were around 2.3 V, falling to 1.5 V after about 0.5 F mol(exp -1) had been withdrawn. Lithium copper oxide, LiCu2O2, and cuprous oxide, Cu2O, were identified as discharge products.

  15. Effects of precipitation methods on the structure and properties of propylene oxidation catalyst%不同沉淀方式对丙烯氧化催化剂结构和性能的影响

    Institute of Scientific and Technical Information of China (English)

    曾贤君; 孙彦民; 苗静; 李世鹏; 李晓云; 于海斌; 郭郢; 费家明

    2011-01-01

    Mo-Bi-Co-Fe-O mixed oxide catalysts for acrolein synthesis were prepared by three methods of incomplete precipitation, co-precipitation and stepwise precipitation and characterized by XRD, SEM, EDS and H2-TPR techniques. The results showed that the catalyst prepared by stepwise precipitation method had high catalytic activity under the reaction condition of temperature 320 ℃ and pressure 111 kPa,with propylene conversion of 97.68% and acrolein yield of 94.04%.%采用不完全沉淀、共沉淀和分步沉淀法制备Mo-Bi-Co-Fe-O复合氧化物催化剂,对其结构进行表征,并应用于丙烯氧化制丙烯醛反应.结果表明,使用分步沉淀法制备的催化剂在反应温度320℃和反应压力111 kPa条件下,丙烯转化率为97.68%,收率达94.04%.

  16. Effect of cuprous halide interlayers on the device performance of ZnPc/C{sub 60} organic solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jinho; Park, Dasom; Heo, Ilsu; Yim, Sanggyu, E-mail: sgyim@kookmin.ac.kr

    2014-10-15

    Highlights: • Effect of CuX interlayers on subsequently deposited films and devices was studied. • CuI is the most effective for the performance of ZnPc/C{sub 60}-based solar cells. • Results were related to the molecular geometry of ZnPc and HOMO level of interlayers. - Abstract: The effect of various cuprous halide (CuX) interlayers introduced between a poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) layer and zinc phthalocyanine (ZnPc) layer on the physical properties of the ZnPc thin films and device performances of ZnPc/C{sub 60}-based small-molecule organic solar cells was studied. Strong substrate–molecule interaction between the CuX and ZnPc partly converted surface-perpendicular stacking geometry of ZnPc molecules into surface-parallel one. This flat-lying geometry led to an enhancement in electronic absorption and charge transport within the ZnPc films. As a result, the overall power conversion efficiency of the cell with CuI interlayer increased by ∼37%. In the case of the cells with CuBr and CuCl interlayer, however, the enhancement in device performances was limited because of the reduced conversion of the molecular geometry and increased energy barrier for hole extraction due to the low highest occupied molecular orbital level of the interlayer.

  17. Co-precipitation synthesis of nano-composites consists of zinc and tin oxides coatings on glass with enhanced photocatalytic activity on degradation of Reactive Blue 160 KE2B.

    Science.gov (United States)

    Habibi, Mohammad Hossein; Mardani, Maryam

    2015-02-25

    Nano-composite containing zinc oxide-tin oxide was obtained by a facile co-precipitation route using tin chloride tetrahydrate and zinc chloride as precursors and coated on glass by Doctor Blade deposition. The crystalline structure and morphology of composites were evaluated by X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM). The XRD results showed peaks relative to zinc oxide with hexagonal wurtzite structure and tin oxide with tetragonal structure. FESEM observations showed that the nano-composite consisted of aggregates of particles with an average particle size of 18 nm. The photocatalytic activity of the pure SnO2, pure ZnO, ZnSnO3-Zn2SnO4 and ZnO-SnO2 nano-structure thin films was examined using the degradation of a textile dye Reactive Blue 160 (KE2B). ZnO-SnO2 nano-composite showed enhanced photo-catalytic activity than the pure zinc oxide and tin oxide. The enhanced photo-catalytic activity of the nano-composite was ascribed to an improved charge separation of the photo-generated electron-hole pairs.

  18. Reduction of Resistivity in Cu Thin Films by Partial Oxidation: Microstructural Mechanisms

    Energy Technology Data Exchange (ETDEWEB)

    Prater, W

    2003-10-14

    We report the electrical resistance and microstructure of sputter deposited copper thin films grown in an oxygen containing ion-beam sputtering atmosphere. For films thinner than 5 nm, 2-10% oxygen causes a decrease in film resistance, while for thicker films there is a monotonic increase in resistivity. X-ray reflectivity measurements show significantly smoother films for these oxygen flow rates. X-ray diffraction shows that the oxygen doping causes a refinement of the copper grain size and the formation of cuprous oxide. We suggest that the formation of cuprous oxide limits copper grain growth, which causes smoother interfaces, and thus reduces resistivity by increasing specular scattering of electrons at interfaces.

  19. Perspective: Maintaining surface-phase purity is key to efficient open air fabricated cuprous oxide solar cells

    Directory of Open Access Journals (Sweden)

    Robert L. Z. Hoye

    2015-02-01

    Full Text Available Electrochemically deposited Cu2O solar cells are receiving growing attention owing to a recent doubling in efficiency. This was enabled by the controlled chemical environment used in depositing doped ZnO layers by atomic layer deposition, which is not well suited to large-scale industrial production. While open air fabrication with atmospheric pressure spatial atomic layer deposition overcomes this limitation, we find that this approach is limited by an inability to remove the detrimental CuO layer that forms on the Cu2O surface. Herein, we propose strategies for achieving efficiencies in atmospherically processed cells that are equivalent to the high values achieved in vacuum processed cells.

  20. Cuprous Oxide as a Potential Low-Cost Hole-Transport Material for Stable Perovskite Solar Cells.

    Science.gov (United States)

    Nejand, Bahram Abdollahi; Ahmadi, Vahid; Gharibzadeh, Saba; Shahverdi, Hamid Reza

    2016-02-08

    Inorganic hole-transport materials are commercially desired to decrease the fabrication cost of perovskite solar cells. Here, Cu2O is introduced as a potential hole-transport material for stable, low-cost devices. Considering that Cu2O formation is highly sensitive to the underlying mixture of perovskite precursors and their solvents, we proposed and engineered a technique for reactive magnetron sputtering. The rotational angular deposition of Cu2O yields high surface coverage of the perovskite layer for high rate of charge extraction. Deposition of this Cu2O layer on the pinhole-free perovskite layer produces devices with power conversion efficiency values of up to 8.93%. The engineered Cu2O layers showed uniform, compact, and crack-free surfaces on the perovskite layer without affecting the perovskite structure, which is desired for deposition of the top metal contact and for surface shielding against moisture and mechanical damages. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Synthesis and characterization of different metal oxide nanostructures by simple electrolysis based oxidation of metals.

    Science.gov (United States)

    Singh, Dinesh Pratap; Srivastava, Onkar Nath

    2009-09-01

    We report the Synthesis of different metal oxide (Cu2O, SnO2, Fe3O4 and PbO2) nanostructures by simple electrolysis based oxidation of metals (Cu, Sn, Fe and Pb). We have utilized the two electrode set up for the electrolysis and used different metal electrodes as anode and platinum as cathode. The synthesized nanomaterials were delaminated in the electrolyte. The microstructural characterization of synthesized materials in electrolytes after electrolysis at different electrode potentials revealed that the nanostructures strongly depend on the applied voltage between the electrodes. Various nanostructures (nanothreads, nanowires, nanocubes, nanotetrapods and hexagons-like) of metal oxides have been synthesized by this method. In case of copper electrode we have found nanothreads and nanowires of cuprous oxide. Tin electrode resulted nanothreads, nanotetrapod and nanocube like structures of tin oxide. Iron electrode resulted, nanowire like structures of iron oxide and lead sheet transformed into hexagon like and six petals like structures of lead oxide.

  2. Oxidation of Octopus vulgaris hemocyanin by nitrogen oxides

    Energy Technology Data Exchange (ETDEWEB)

    Salvato, B.; Giacometti, G.M.; Beltramini, M.; Zilio, F.; Giacometti, G.; Magliozzo, R.S.; Peisach, J.

    1989-01-24

    The reaction of Octopus vulgaris hemocyanin with nitrite was studied under a variety of conditions in which the green half-met derivative is formed. Analytical evidence shows that the amount of chemically detectable nitrite in various samples of the derivative is not proportional to the cupric copper detected by EPR. The kinetics of oxidation of hemocyanin as a function of protein concentration and pH, in the presence of nitrite and ascorbate, is consistent with a scheme in which NO/sub 2/ is the reactive oxidant. We suggest that the green half-methemocyanin contains a metal center with one cuprous and one cupric copper without an exogenous nitrogen oxide ligand.

  3. Production of hydrogen from methanol over Cu/ZnO and Cu/ZnO/Al2O3 catalysts prepared by homogeneous precipitation : Steam reforming and oxidative steam reforming

    OpenAIRE

    2006-01-01

    Two series of Cu/ZnO and Cu/ZnO/Al2O3 catalysts with varying Cu/Zn ratio have been prepared by the homogeneous precipitation (hp) method using urea hydrolysis. Steam reforming and oxidative steam reforming of methanol were performed using the hp-Cu/Zn-based catalysts for catalytic production of hydrogen. The hp-Cu/ZnO/Al2O3 catalyst showed a higher activity than the hp-Cu/ZnO catalysts. In both cases, the catalytic activity was well correlated with the surface area of Cu metal, and the maximu...

  4. Study of the structural phase transformation of iron oxide nanoparticles from an Fe{sup 2+} ion source by precipitation under various synthesis parameters and temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Šutka, A., E-mail: andris.sutka@rtu.lv [Institute of Silicate Materials, Riga Technical University, Paula Valdena 3, Riga LV-1048 (Latvia); Lagzdina, S. [Institute of Silicate Materials, Riga Technical University, Paula Valdena 3, Riga LV-1048 (Latvia); Käämbre, T.; Pärna, R. [Institute of Physics, University of Tartu, Riia 142, 51014 Tartu (Estonia); Kisand, V. [Institute of Physics, University of Tartu, Riia 142, 51014 Tartu (Estonia); Estonian Nanotechnology Competence Center, Riia 142, 51014 Tartu (Estonia); Kleperis, J. [Institute of Solid State Physics, University of Latvia, Kengaraga 8, Riga LV-1063 (Latvia); Maiorov, M. [Institute of Physics, University of Latvia, Miera 32, Salaspils LV-2169 (Latvia); Kikas, A.; Kuusik, I. [Institute of Physics, University of Tartu, Riia 142, 51014 Tartu (Estonia); Jakovlevs, D. [Riga Biomaterials Innovation and Development Centre, Riga Technical University, Riga (Latvia)

    2015-01-15

    Magnetite nanoparticles were precipitated from a pure aqueous ferrous salt solution in an air atmosphere. The influence of the solution molarity, the rate of precipitator agent addition, stirring time and annealing temperature was studied. The morphology, crystalline phase purity and magnetic properties of the obtained powders were studied by X-Ray powder diffraction (XRD), Scanning electron microscopy (SEM), Differential thermal analysis (DTA), X-ray photoelectron spectroscopy (XPS), X-ray absorption spectroscopy (XAS) and Vibrating sample magnetometer (VSM). The synthesis conditions were seen to have an effect on phase composition. It was possible to obtain near stoichiometric Fe{sub 3}O{sub 4} or a mixture of Fe{sub 3}O{sub 4}, γ-Fe{sub 2}O{sub 3}, α-Fe{sub 2}O{sub 3} and FeOOH. Fe{sub 3}O{sub 4} nanoparticles showed high saturation magnetization ∼86 emu/g. - Highlights: • We synthesized near stoichiometric Fe{sub 3}O{sub 4} nanoparticles at room temp. in the air. • Fe{sub 3}O{sub 4} co-precipitation was done from aqueous ferrous Fe{sup 2+} salt solution only. • The influence of synthesis conditions was investigated. • Detailed structural studies were done by XRD, XPS and XAS.

  5. Effect of Precipitation Method and Ce Doping on the Catalytic Activity of Copper Manganese Oxide Catalysts for CO Oxidation%沉淀方法及铈掺杂对铜锰氧化物催化剂催化氧化CO性能的影响

    Institute of Scientific and Technical Information of China (English)

    张学彬; 马扩颜; 张灵辉; 雍国平; 戴亚; 刘少民

    2011-01-01

    The influence of Ce doping and the precipitation method on structural properties and the catalytic activity of copper manganese oxides for CO oxidation at ambient temperature have been investigated. The catalysts were characterized by means of the powder X-ray diffraction and N2 adsorption-desorption, the inductively coupled plasma atomic emission spectrometry, the temperature programmed reduction, diffuse reflectance UV-Vis spectra,and the X-ray photoelectron spectroscopy. It was found that after doping little amount of Ce in copper manganese oxide, CeO2 phase was highly dispersed and could prevent sintering and aggregating of the catalyst, the size of the catalytic material was decreased, the reducibility was enhanced, the specific surface area was increased and the formation of the active sites for the oxidation of CO was improved significantly. Therefore, the activity of the rare earth promoted catalyst was enhanced remarkably.

  6. Preparation of Cobalt-Molybdenum bimetallic oxides supported on alumina by Co-precipitation method%氧化铝负载Co-Mo双金属氧化物的共沉淀制备

    Institute of Scientific and Technical Information of China (English)

    张新波; 张斌; 张雅娟; 秦永华

    2012-01-01

    采用双溶剂体系(硝酸铝和硝酸钴的乙醇溶液与钼酸铵的碳酸铵水溶液)共沉淀制备了氧化铝负载Co-Mo双金属氧化物.研究了双溶剂体系中乙醇和水的体积比对共沉淀的影响,考察了老化时间对氧化物结构参数的影响,研究了焙烧温度对氧化物还原性能的影响.结果表明:乙醇和水体积比对钼酸根离子的沉淀有重要影响,为了保证钼酸根离子的完全沉淀,乙醇的体积要随着MoO3负载量的增加而提高;随着老化时间的增加,氧化物的比表面积先增加后下降,6h 老化的样品具有最大的比表面积;低温焙烧制得的氧化物较容易还原.%Cobalt-molybdenum bimetallic oxides supported on alumina were prepared by co-precipitation method with etha- nol-water binary solvent system,which is composed of ethanol solution of aluminium nitrate and cobalt nitrate, and aqueous solution of ammonium carbonate and ammonium molybdate. The effects of ethanol/water volume ratio and MoO3 loading ore the coprecipitation were invesitigated. X-ray diffraction ( XRD) , N2 physical adsorption and temperature programmed reduction (TPR) were employed to characterize the oxides. Results show that the precipitation of Mo7O246- ions was affected by the ethanol/water volume ratio and MoO3 loading. The volume of ethanol to guarantee the precipitation of Mo7O246~ ions should be increased with the increase of MoO, loading. The specific surface area firstly increased then decreased with the increase of aging time. The oxide with aging time of 6 h has the largest specific surface area. The oxides calcined at low temperature are reduced more easily than that calcined at high temperature.

  7. Growth and characterization of single phase Cu2O by thermal oxidation of thin copper films

    Science.gov (United States)

    Choudhary, Sumita; Sarma, J. V. N.; Gangopadhyay, Subhashis

    2016-04-01

    We report a simple and efficient technique to form high quality single phase cuprous oxide films on glass substrate using thermal evaporation of thin copper films followed by controlled thermal oxidation in air ambient. Crystallographic analysis and oxide phase determination, as well as grain size distribution have been studied using X-ray diffraction (XRD) method, while scanning electron microscopy (SEM) has been utilized to investigate the surface morphology of the as grown oxide films. The formation of various copper oxide phases is found to be highly sensitive to the oxidation temperature and a crystalline, single phase cuprous oxide film can be achieved for oxidation temperatures between 250°C to 320°C. Cu2O film surface appeared in a faceted morphology in SEM imaging and a direct band gap of about 2.1 eV has been observed in UV-visible spectroscopy. X-ray photoelectron spectroscopy (XPS) confirmed a single oxide phase formation. Finally, a growth mechanism of the oxide film has also been discussed.

  8. Synthesis of nanostructured β-Ni(OH)2 by electrochemical dissolution-precipitation and its application as a water oxidation catalyst

    Science.gov (United States)

    Jung, Sang Cheol; Sim, Soong Leong; Woan Soon, Ying; Lim, Chee Ming; Hing, Peter; Jennings, James Robert

    2016-07-01

    A straightforward electrochemical dissolution-precipitation approach has been developed to synthesize nanostructured β-Ni(OH)2 powders (particle size 10-100 nm, specific surface area ˜100 m2 g-1) from Ni metal anodes. The approach differs from existing electrochemical synthesis methods in that it predominantly results in bulk precipitation of nanoparticles, without significant film growth on either of the electrodes. Heat treatment of the as-synthesized β-Ni(OH)2 afforded NiO with mostly preserved nanostructure and very high specific surface area (≤100 m2 g-1, depending on calcination temperature). The as-synthesized β-Ni(OH)2 was found to be an excellent catalyst for the oxygen evolution reaction (OER) in the technologically important water electrolysis process, apparently contradicting recent reports that the α polymorph is required for such high activity. With catalyst loadings <0.1 mg cm-2, OER current densities of 10 mA cm-2 were sustained at overpotentials as low as 340 mV, with Tafel slopes of only ˜38 mV/decade. The catalyst was highly stable in alkaline media over the course of electrolysis experiments lasting for several hours. This performance surpasses that of many previously reported earth-abundant OER catalysts and is comparable to that obtained with state-of-the-art RuO2 and IrO2 catalysts.

  9. PRECIPITATION OF PLUTONOUS PEROXIDE

    Science.gov (United States)

    Barrick, J.G.; Manion, J.P.

    1961-08-15

    A precipitation process for recovering plutonium values contained in an aqueous solution is described. In the process for precipitating plutonium as plutonous peroxide, hydroxylamine or hydrazine is added to the plutoniumcontaining solution prior to the addition of peroxide to precipitate plutonium. The addition of hydroxylamine or hydrazine increases the amount of plutonium precipitated as plutonous peroxide. (AEC)

  10. CO oxidation over CuO catalysts supported on CeO2-ZrO2 prepared by microwave-assisted co-precipitation:The influence of CuO content

    Institute of Scientific and Technical Information of China (English)

    杨志强; 毛东森; 郭晓明; 卢冠忠

    2014-01-01

    CeO2-ZrO2 mixed oxide (Ce0.6Zr0.4O2) prepared by microwave-assisted heating co-precipitation was used as a support to prepare a series of CuO/Ce0.6Zr0.4O2 catalysts with various CuO contents (0 wt.%-15 wt.%) via the method of incipient-wetness im-pregnation. The obtained CuO/Ce0.6Zr0.4O2 samples were characterized by N2 adsorption, XRD, Raman, TEM and H2-TPR technolo-gies, and their catalytic activities for CO oxidation were investigated. The results showed that the activity of CuO/Ce0.6Zr0.4O2 catalyst was strongly influenced by the content of CuO, and the catalyst with 10 wt.%CuO exhibited the best catalytic activity in CO oxida-tion, which could be attributed to the high dispersion and reducibility of CuO, and high oxygen vacancy concentration in the catalyst.

  11. Chemical Data for Precipitate Samples

    Science.gov (United States)

    Foster, Andrea L.; Koski, Randolph A.

    2008-01-01

    During studies of sulfide oxidation in coastal areas of Prince William Sound in 2005, precipitate samples were collected from onshore and intertidal locations near the Ellamar, Threeman, and Beatson mine sites (chapter A, fig. 1; table 7). The precipitates include jarosite and amorphous Fe oxyhydroxide from Ellamar, amorphous Fe oxyhydroxide from Threeman, and amorphous Fe oxyhydroxide, ferrihydrite, and schwertmannite from Beatson. Precipitates occurring in the form of loose, flocculant coatings were harvested using a syringe and concentrated in the field by repetitive decanting. Thicker accumulations were either scraped gently from rocks using a stainless steel spatula or were scooped directly into receptacles (polyethylene jars or plastic heavy-duty zippered bags). Most precipitate samples contain small amounts of sedimentary detritus. With three jarosite-bearing samples from Ellamar, an attempt was made to separate the precipitate from the heavy-mineral fraction of the sediment. In this procedure, the sample was stirred in a graduated cylinder containing deionized water. The jarosite-rich suspension was decanted onto analytical filter paper and air dried before analysis. Eleven precipitate samples from the three mine sites were analyzed in laboratories of the U.S. Geological Survey (USGS) in Denver, Colorado (table 8). Major and trace elements were determined by inductively coupled plasma-mass spectrometry following multiacid (HCl-HNO3-HClO4-HF) digestion (Briggs and Meier, 2002), except for mercury, which was analyzed by cold-vapor atomic absorption spectroscopy (Brown and others, 2002a). X-ray diffraction (XRD) analyses were performed on powdered samples (<200 mesh) by S. Sutley of the USGS. Additional details regarding sample preparation and detection limits are found in Taggert (2002). Discussions of the precipitate chemistry and associated microbial communities are presented in Koski and others (2008) and Foster and others (2008), respectively.

  12. Behavior of Aqueous Electrolytes in Steam Cycles - The Final Report on the Solubility and Volatility of copper(I) and Copper(II) Oxides

    Energy Technology Data Exchange (ETDEWEB)

    Palmer, Donald [ORNL; Benezeth, Pascale [Laboratoire des Mecanismes et Transferts en Geologie, Toulouse, France; Simonson, J Michael {Mike} [ORNL

    2004-05-01

    Measurements were completed on the solubility of cupric and cuprous oxides in liquid water and steam at controlled pH conditions from 25 to 400 C (77 to 752 F). The results of this study have been combined with those reported from this laboratory in two previous EPRI reports to provide a complete description of the solubility of these oxides and the speciation of copper dissolved in liquid water and steam as a function of oxidation state, temperature, pH, and in the case of steam, pressure. These constitute the first set of reliable data for cuprous oxide solubility over this range of conditions. For the more intensively studied CuO case, agreement was found between our results and those of previous studies of its solubility in steam, whereas only partial agreement was evident for its solubility in liquid water. For both oxides this disagreement often amounted to orders of magnitude. The solubility of cuprous oxide is somewhat lower than that of CuO at ambient conditions, except as very high pH. However, by 350 C (662 F), Cu{sub 2}O is the more soluble phase. At 100 C (212 F) and above, the logarithm of the solubility of both phases decreases linearly with increasing pH to a minimum value then sharply increases linearly with pH. In other words, above 100 C the solubility of both oxides become highly pH dependent. In fact at constant pH during startup, very high copper concentrations can be reached in the boiler water, more than an order of magnitude above those at ambient or operating temperatures. The enhancing effect of added ammonia on the solubility of both oxides is most significant at low temperatures and is much greater for cuprous oxide. Consequently, the mobility of copper is affected significantly under AVT startup conditions. The oxidation of copper metal and presumably cuprous oxide by addition of air-saturated makeup water can lead to much higher copper concentrations than equilibrium with cupric oxide would allow, but the presence of both copper metal

  13. A perfectly aligned 63 helical tubular cuprous bromide single crystal for selective photo-catalysis, luminescence and sensing of nitro-explosives.

    Science.gov (United States)

    Yao, Ru-Xin; Hailili, Reshalaiti; Cui, Xin; Wang, Li; Zhang, Xian-Ming

    2015-02-21

    A perfectly aligned 63 helical tubular cuprous bromide single crystal has been synthesized and characterized, which can selectively decompose negatively charged dyes of Methyl Orange (MO) and Kermes Red (KR), and the photocatalytic efficiency is higher than that of nanosized (∼25 nm) TiO2 and ZnO. The direction and magnitude of the dipole moments as well as the band structure were calculated to reveal high photocatalytic efficiency. Moreover, luminescence studies indicate that the CuBr tube materials show very strong yellowish green emissions in the solid state and emulsion even at room temperature, and exhibit extremely high detection sensitivity towards nitro-explosives via fluorescence quenching. Detectable luminescence responses were observed at a very low concentration of 20 ppm with a high quenching efficiency of 94.90%. The results suggest that they may be promising multifunctional materials for photo-catalysis, luminescence and sensing of nitro-explosives.

  14. Modelled Precipitation Over Greenland

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set includes the annual total precipitation from 1985 to 1999 and monthly total precipitation from January 1985 to December 1999. The data is derived from...

  15. Enhanced performance of light-controlled conductive switching in hybrid cuprous oxide/reduced graphene oxide (Cusub>2sub>O/rGO) nanocomposites.

    Science.gov (United States)

    Wei, Jing; Zang, Zhigang; Zhang, Yubo; Wang, Ming; Du, Jihe; Tang, Xiaosheng

    2017-03-01

    A significant enhancement of photoresponse from the light-controlled conductive switching based on Cusub>2sub>O/rGO nanocomposites was experimentally demonstrated. Cusub>2sub>O/rGO nanocomposites were synthesized via a facile wet-reduced method. The crystalline structure, morphologies, and photoluminescence of the Cusub>2sub>O/rGO nanocomposites were characterized and analyzed. The fabricated conductive switching was measured under the irradiation of a continuous laser. When the laser was turned on and off alternately, the photoconductive switching obviously displayed a state conversion between "on" and "off" reversibly. Furthermore, the typical current-voltage (I-V) and current-time (I-t) curves exhibited a relatively high switching ratio (Isub>onsub>/Isub>offsub>) of 3.25 and a fast response time of 0.45 s. The excellent "on-off" characteristics of the device show promising applications in memory storage and logic circuits.

  16. Precipitates in electrical steels

    Energy Technology Data Exchange (ETDEWEB)

    Jenkins, Keith [Development and Market Research, Cogent Power Limited, Corporation Road, Newport, South Wales NP19 OXT (United Kingdom)], E-mail: keith.jenkins@cogent-power.com; Lindenmo, Magnus [Development and Market Research, Cogent Power Limited, Corporation Road, Newport, South Wales NP19 OXT (United Kingdom)

    2008-10-15

    Precipitates heavily influence the magnetic properties of electrical steels, either as a key controlled requirement as part of the manufacturing process or as an unwanted harmful residual in the final product. In this current work copper-manganese sulphides precipitates are the primary inhibitor species in the conventional grain-oriented (CGO) steels examined and grain boundary pinning is effective at a mean precipitate size of 30-70 nm. The growth of CuMnS has been studied and the results show that a precipitate size above {approx}100 nm allows the onset of secondary recrystallisation in the heating conditions applied. The effect of precipitates on the magnetic properties of both grain-oriented and non-oriented steels in their final product form is then examined. Examples of grain-oriented material still containing large numbers of precipitates clearly show the detrimental effects with increases in total power loss of 40% or more. Loss deterioration by about 20% is also seen in samples of high silicon non-oriented material in which titanium carbo-nitride precipitates have been observed. In this case the precipitates are believed to have formed during cooling after final annealing. Finally a grain-oriented steel with a large number of very small precipitates, which do not seem to have any harmful effect on the magnetic properties, is demonstrated.

  17. Global Precipitation Measurement Poster

    Science.gov (United States)

    Azarbarzin, Art

    2010-01-01

    This poster presents an overview of the Global Precipitation Measurement (GPM) constellation of satellites which are designed to measure the Earth's precipitation. It includes the schedule of launches for the various satellites in the constellation, and the coverage of the constellation, It also reviews the mission capabilities, and the mission science objectives.

  18. Room temperature inorganic polycondensation of oxide (Cu{sub 2}O and ZnO) nanoparticles and thin films preparation by the dip-coating technique

    Energy Technology Data Exchange (ETDEWEB)

    Salek, G.; Tenailleau, C., E-mail: tenailleau@chimie.ups-tlse.fr; Dufour, P.; Guillemet-Fritsch, S.

    2015-08-31

    Oxide thin solid films were prepared by dip-coating into colloidal dispersions of oxide nanoparticles stabilized at room temperature without the use of chelating or complex organic dispersing agents. Crystalline oxide nanoparticles were obtained by inorganic polycondensation and characterized by X-ray diffraction and field emission gun scanning electron microscopy. Water and ethanol synthesis and solution stabilization of oxide nanoparticle method was optimized to prepare two different structural and compositional materials, namely Cu{sub 2}O and ZnO. The influence of hydrodynamic parameters over the particle shape and size is discussed. Spherical and rod shape nanoparticles were formed for Cu{sub 2}O and ZnO, respectively. Isoelectric point values of 7.5 and 8.2 were determined for cuprous and zinc oxides, respectively, after zeta potential measurements. A shear thinning and thixotropic behavior was observed in both colloidal sols after peptization at pH ~ 6 with dilute nitric acid. Every colloidal dispersion stabilized in a low cost and environmentally friendly azeotrope solution composed of 96 vol.% of ethanol with water was used for the thin film preparation by the dip-coating technique. Optical properties of the light absorber cuprous oxide and transparent zinc oxide thin solid films were characterized by means of transmittance and reflectance measurements (300–1100 nm). - Highlights: • Room temperature inorganic polycondensation of crystalline oxides • Water and ethanol synthesis and solution stabilization of oxide nanoparticles • Low cost method for thin solid film preparation.

  19. A Study on the Influencing Factors in the Preparation of Bismuth-doped Tin Oxide Nano-powders by Co-Precipitation%化学共沉淀法制备纳米铋掺杂氧化锡

    Institute of Scientific and Technical Information of China (English)

    黄旭珊; 吕维忠; 罗仲宽; 宋力昕

    2011-01-01

    以SnCl4·5H2O和Bi( NO3)3·5H2O为原料,氨水为沉淀剂,采用化学共沉淀法制备了铋掺杂氧化锡(BTO)纳米粉体,考察了反应温度、滴定终点pH、铋掺杂量、煅烧温度和分散剂PEG - 600对所得的纳米BTO粉体物相、晶粒度和形貌的影响,对粉末的前驱体进行综合热分析(TG-DTA),用X射线衍射(XRD)、扫描电镜(SEM)对产物的结构和形貌进行表征,得到共沉淀法制备纳米BTO粉体的最佳条件:反应温度60℃,滴定终点pH =3,煅烧温度600℃;该条件下制得BTO粉体的电阻率最小为3.48 Ω·cm.%Bismuth-doped tin oxide ( BTO) nano-particles were prepared by chemical co-precipitation method using SnCl4 ? 5H2O and Bi(NO3)3 ? 5H2O as precursors and NH3 ? H2O as precipitant. The effect of processing parameters on the particles was investigated. These parameters include reaction temperature, terminal pH, doping bismuth content, calcine temperature, and PEG - 600 dispersant. The BTO precursors were studied by means of TG - DTA. The product particles were characterized by means of X-ray diffraction (XRD) and scanning electron microscopy ( SEM). The optimized conditions for preparing nanometer BTO powders were proposed: reaction temperature of 60℃, terminal pH of 3, and the calcine temperature of 600℃ , the minimum resistivity of BTO powders is 3. 48 Ω· cm under the optimized conditions.

  20. Nano Copper Oxide-Modified Carbon Cloth as Cathode for a Two-Chamber Microbial Fuel Cell

    Science.gov (United States)

    Dong, Feng; Zhang, Peng; Li, Kexun; Liu, Xianhua; Zhang, Pingping

    2016-01-01

    In this work, Cu2O nanoparticles were deposited on a carbon cloth cathode using a facile electrochemical method. The morphology of the modified cathode, which was characterized by scanning electron microscopy (SEM) and Brunauer-Emmett-Teller (BET) tests, showed that the porosity and specific surface area of the cathode improved with longer deposition times. X-ray photoelectron spectroscopy (XPS) and cyclic voltammetry (CV) results showed that cupric oxide and cuprous oxide coexisted on the carbon cloth, which improved the electrochemical activity of cathode. The cathode with a deposition time of 100 s showed the best performance, with a power density twice that of bare carbon cloth. Linear sweep voltammetry (LSV) and electrochemical impedance spectroscopy (EIS) results revealed that moderate deposition of nano copper oxide on carbon cloth could dramatically reduce the charge transfer resistance, which contributed to the enhanced electrochemical performance. The mediation mechanism of copper oxide nanocatalyst was illustrated by the fact that the recycled conversion between cupric oxide and cuprous oxide accelerated the electron transfer efficiency on the cathode.

  1. Nano Copper Oxide-Modified Carbon Cloth as Cathode for a Two-Chamber Microbial Fuel Cell

    Directory of Open Access Journals (Sweden)

    Feng Dong

    2016-12-01

    Full Text Available In this work, Cu2O nanoparticles were deposited on a carbon cloth cathode using a facile electrochemical method. The morphology of the modified cathode, which was characterized by scanning electron microscopy (SEM and Brunauer-Emmett-Teller (BET tests, showed that the porosity and specific surface area of the cathode improved with longer deposition times. X-ray photoelectron spectroscopy (XPS and cyclic voltammetry (CV results showed that cupric oxide and cuprous oxide coexisted on the carbon cloth, which improved the electrochemical activity of cathode. The cathode with a deposition time of 100 s showed the best performance, with a power density twice that of bare carbon cloth. Linear sweep voltammetry (LSV and electrochemical impedance spectroscopy (EIS results revealed that moderate deposition of nano copper oxide on carbon cloth could dramatically reduce the charge transfer resistance, which contributed to the enhanced electrochemical performance. The mediation mechanism of copper oxide nanocatalyst was illustrated by the fact that the recycled conversion between cupric oxide and cuprous oxide accelerated the electron transfer efficiency on the cathode.

  2. Oxidation Mechanism of Copper Selenide

    Science.gov (United States)

    Taskinen, Pekka; Patana, Sonja; Kobylin, Petri; Latostenmaa, Petri

    2014-09-01

    The oxidation mechanism of copper selenide was investigated at deselenization temperatures of copper refining anode slimes. The isothermal roasting of synthetic, massive copper selenide in flowing oxygen and oxygen - 20% sulfur dioxide mixtures at 450-550 °C indicate that in both atmospheres the mass of Cu2Se increases as a function of time, due to formation of copper selenite as an intermediate product. Copper selenide oxidises to copper oxides without formation of thick copper selenite scales, and a significant fraction of selenium is vaporized as SeO2(g). The oxidation product scales on Cu2Se are porous which allows transport of atmospheric oxygen to the reaction zone and selenium dioxide vapor to the surrounding gas. Predominance area diagrams of the copper-selenium system, constructed for selenium roasting conditions, indicate that the stable phase of copper in a selenium roaster gas with SO2 is the sulfate CuSO4. The cuprous oxide formed in decomposition of Cu2Se is further sulfated to CuSO4.

  3. Influence of 300°C thermal conversion of Fe-Ce hydrous oxides prepared by hydrothermal precipitation on the adsorptive performance of five anions: Insights from EXAFS/XANES, XRD and FTIR (companion paper).

    Science.gov (United States)

    Chubar, Natalia; Gerda, Vasyl; Banerjee, Dipanjan

    2017-04-01

    In this work, we report atomic-scale reconstruction processes in Fe-Ce oxide-based composites (hydrothermally precipitated at Fe-to-Ce dosage ratios of 1:0, 2:1, 1:1, 1:2, and 0:1), upon treatment at 300°C. The structural changes are correlated with the adsorptive removal of arsenate, phosphate, fluoride, bromide, and bromate. The presence of the carbonate-based Ce-component and surface sulfate in precursor samples creates favorable conditions for phase transformation, resulting in the formation of novel (unknown) layered compounds of Fe and Ce. These compounds are of the layered double hydroxide type, with sulfate in the interlayer space. In spite of general awareness of the importance of surface area in adsorptive removal, the increase in surface area upon thermal treatment did not increase adsorption of the studied anions. However, EXAFS simulations and the adsorption tests provided evidence of regularities between local structures of Fe in composites obtained at 80 and 300°C and adsorption performance of most studied anions. The best adsorption of tetrahedral anions was demonstrated by samples whose simulated outer Fe shells resulted from oscillations from both O and Fe atoms. In contrast, the loss of extended x-ray absorption fine structure was correlated with the decrease of adsorptive removal. Both Fe K-edge and Ce L3 -edge EXAFS suggested the formation of solid solutions. For the first time, the utilization of extended x-ray absorption fine structure is suggested as a methodological approach (first expressed in the companion paper) to estimate the surface reactivity of inorganic materials intended for use as anion exchange adsorbents. Copyright © 2016 Elsevier Inc. All rights reserved.

  4. Influence of 300°C thermal conversion of Fe-Ce hydrous oxides prepared by hydrothermal precipitation on the adsorptive performance of five anions: Insights from EXAFS/XANES, XRD and FTIR (companion paper)

    KAUST Repository

    Chubar, Natalia

    2016-12-07

    In this work, we report atomic-scale reconstruction processes in Fe-Ce oxide-based composites (hydrothermally precipitated at Fe-to-Ce dosage ratios of 1:0, 2:1, 1:1, 1:2, and 0:1), upon treatment at 300 °C. The structural changes are correlated with the adsorptive removal of arsenate, phosphate, fluoride, bromide, and bromate. The presence of the carbonate-based Ce-component and surface sulfate in precursor samples creates favorable conditions for phase transformation, resulting in the formation of novel (unknown) layered compounds of Fe and Ce. These compounds are of the layered double hydroxide type, with sulfate in the interlayer space. In spite of general awareness of the importance of surface area in adsorptive removal, the increase in surface area upon thermal treatment did not increase adsorption of the studied anions. However, EXAFS simulations and the adsorption tests provided evidence of regularities between local structures of Fe in composites obtained at 80 and 300 °C and adsorption performance of most studied anions. The best adsorption of tetrahedral anions was demonstrated by samples whose simulated outer Fe shells resulted from oscillations from both O and Fe atoms. In contrast, the loss of extended x-ray absorption fine structure was correlated with the decrease of adsorptive removal. Both Fe K-edge and Ce L3 -edge EXAFS suggested the formation of solid solutions. For the first time, the utilization of extended x-ray absorption fine structure is suggested as a methodological approach (first expressed in the companion paper) to estimate the surface reactivity of inorganic materials intended for use as anion exchange adsorbents.

  5. Electrocatalytic activity of Cu2O nanocubes-based electrode for glucose oxidation

    Indian Academy of Sciences (India)

    Sathiyanathan Felix; Pratap Kollu; Bala P C Raghupathy; Soon Kwan Jeong; Andrews Nirmala Grace

    2014-01-01

    A direct electrocatalytic activity of glucose oxidation on cuprous oxide modified glassy carbon electrode is reported. Cu2O nanocubes were synthesized by a simple wet chemical route in the absence of surfactants. Purity, shape and morphology of Cu2O are characterized by XRD, SEM, XPS and DRS-UV. The Cu2O nanocubes-modified glassy carbon electrode (GCE) exhibited high electrocatalytic activity towards glucose oxidation compared with bare GCE electrode. At an applied potential of +0.60V, the Cu2O electrode presented a high sensitivity of 121.7 A/mM. A linear response was obtained from 0 to 500 M, a response time less than 5 s and a detection limit of 38 M (signal/noise=3). The Cu2O nanocubes-modified electrode was stable towards interfering molecules like uric acid (UA), ascorbic acid (AA) and dopamine (DA). In short, a facile chemical preparation process of cuprous oxide nanocubes, and the fabricated modified electrode allow highly sensitive, selective, and fast amperometric sensing of glucose, which is promising for the future development of non-enzymatic glucose sensors.

  6. Storage Gage Precipitation Observations

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — A storage gage is a precipitation gage that requires reading and maintenance only monthly or seasonal intervals. This library includes reports from such gages,...

  7. WPA Precipitation Tabulations

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Hourly precipitation data tabulated under the Work Projects Administration (WPA), a New Deal program created to reduce unemployment during the Great Depression....

  8. Chemisorption And Precipitation Reactions

    Science.gov (United States)

    The transport and bioavailability of chemical components within soils is, in part, controlled by partitioning between solids and solution. General terms used to describe these partitioning reactions include chemisorption and precipitation. Chemisorption is inclusive of the suit...

  9. Microbially Induced Precipitation of Strontianite Nanoparticles.

    Science.gov (United States)

    Kang, Serku; Yumi Kim; Lee, Young Jae; Roh, Yul

    2015-07-01

    The objectives of this study were to investigate the microbially mediated precipitation of strontium by microorganisms, and to examine the mineralogical characteristics of the precipitates. Wu Do-1 (Proteus mirabilis) enriched from rhodoliths was used to precipitate strontium at room temperature under aerobic environment. The growth of Wu Do-1 gradually increased over 16 days (OD600 = 2.6) and then decreased until 22 days (OD600 = 2.0) during microbial incubation for strontium precipitation. Also, the pH decreased from 6.5 to 5.3 over 4 days of incubation due to microbial oxidation of organic acids, and then the pH increased up to 8.6 at 25 days of incubation due to NH3+ generation. The Sr2+ concentration in the biotic group sharply decreased from 2,953 mg/L to 5.7 mg/L over 29 days of incubation. XRD, SEM-/TEM-EDS analyses revealed that the precipitates formed by Wu Do-1 (Proteus mirabilis) were identified as 20-70 nm sized strontianite (SrCO3). Therefore, these results suggested that formation of sparingly soluble Sr precipitates mediated by Wu Do-1 (Proteus mirabilis) sequesters strontium and carbon dioxide into a more stable and less toxic form such as strontianite (SrCO3). These results also suggest that bioremediation of metal-contaminated water and biominealization of carbonate minerals may be feasible in the marine environment.

  10. as the Strengthening Precipitates

    Science.gov (United States)

    Lu, Qi; Xu, Wei; van der Zwaag, Sybrand

    2014-12-01

    Generally, Laves phase and M23C6 are regarded as undesirable phases in creep-resistant steels due to their very high-coarsening rates and the resulting depletion of beneficial alloying elements from the matrix. In this study, a computational alloy design approach is presented to develop martensitic steels strengthened by Laves phase and/or M23C6, for which the coarsening rates are tailored such that they are at least one order of magnitude lower than those in existing alloys. Their volume fractions are optimized by tuning the chemical composition in parallel. The composition domain covering 10 alloying elements at realistic levels is searched by a genetic algorithm to explore the full potential of simultaneous maximization of the volume fraction and minimization of the precipitates coarsening rate. The calculations show that Co and W can drastically reduce the coarsening rate of Laves and M23C6 and yield high-volume fractions of precipitates. Mo on the other hand was shown to have a minimal effect on coarsening. The strengthening effects of Laves phase and M23C6 in the newly designed alloys are compared to existing counterparts, showing substantially higher precipitation-strengthening contributions especially after a long service time. New alloys were designed in which both Laves phase and M23C6 precipitates act as strengthening precipitates. Successfully combining MX and M23C6 was found to be impossible.

  11. Ultrasound promoted mild and facile one-pot, three component synthesis of 2H-indazoles by consecutive condensation, CN and NN bond formations catalysed by copper-doped silica cuprous sulphate (CDSCS) as an efficient heterogeneous nano-catalyst.

    Science.gov (United States)

    Soltani Rad, Mohammad Navid

    2017-01-01

    An ultrasonic promoted facile and convenient one-pot three-component procedure for the synthesis of 2H-indazole derivatives using copper-doped silica cuprous sulphate (CDSCS) as a heterogeneous nano-catalyst has been described. In this approach, ultrasonic mediated reaction of different substituted 2-bromobenzaldehydes, structurally diverse primary amines, and tetrabutylammonium azide (TBAA) as an azide source in the presence of CDSCS in DMSO at room temperature furnishes 2H-indazoles in good to excellent yields. Utilizing ultrasonic irradiation techniques provided the dramatic improvements in terms of higher yields and shorter reaction times compared with conventional heating method.

  12. Precipitating factors of asthma.

    Science.gov (United States)

    Lee, T H

    1992-01-01

    Asthma is characterised by bronchial hyperresponsiveness. This feature of the asthmatic diathesis predisposes patients to wheezing in response to a number of different factors. These precipitating factors include specific allergen acting via sensitised mediator cells through an IgE-dependent mechanism. There are irritants which may work through a non-specific manner, or stimuli such as exercise and hyperventilation, which probably also act through mediator release via a non-IgE-dependent manner. The mechanism whereby physical stimuli such as exercise induce bronchoconstriction is of interest, because it increases the context in which the mast cell may participate in acute asthmatic bronchoconstriction. Respiratory infections also commonly provoke asthma, especially in infants and may, indeed, precipitate the asthmatic state itself. Finally, drugs can often trigger asthma attacks and the mechanisms of asthma precipitated by non-steroidal anti-inflammatory drugs such as aspirin have been the subject of recent research.

  13. Precipitation-Regulated Feedback

    Science.gov (United States)

    Voit, Mark

    2016-07-01

    Star formation in the central galaxies of galaxy clusters appears to be fueled by precipitation of cold clouds out of hot circumgalactic gas via thermal instability. I will present both observational and theoretical support for the precipitation mode in large galaxies and discuss how it can be implemented in cosmological simulations of galaxy evolution. Galaxy cluster cores are unique laboratories for studying the astrophysics of thermal instability and may be teaching us valuable lessons about how feedback works in galaxies spanning the entire mass spectrum.

  14. Precipitation Reconstruction (PREC)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The PREC data set is an analysis of monthly precipitation constructed on a 2.5(o)lat/lon grid over the global for the period from 1948 to the present. The land...

  15. Reaction systems with precipitation

    Directory of Open Access Journals (Sweden)

    Marek Rogalski

    2015-04-01

    Full Text Available This article proposes expanding Reaction Systems of Ehrenfeucht and Rozenberg by incorporating precipitation reactions into it. This improves the computing power of Reaction Systems by allowing us to implement a stack. This addition enables us to implement a Deterministic Pushdown Automaton.

  16. Synthesis of BiFeO3 by carbonate precipitation

    Indian Academy of Sciences (India)

    V Kothai; Rajeev Ranjan

    2012-04-01

    Magnetoelectric multiferroic BiFeO3 (BFO) was synthesized by a simple carbonate precipitation technique of metal nitrate solutions. X-ray powder diffraction and thermo-gravimetric analysis (TGA) revealed that the precipitate consists of an intimate mixture of crystalline bismuth carbonate and an amorphous hydroxide of iron. The precipitate yielded BiFeO3 at an optimal calcination temperature of ∼560°C. Energy dispersive X-ray (EDX) analysis showed 1:1 ratio between Bi and Fe in the oxide. X-ray photoelectron spectroscopy (XPS) studies confirmed that Fe to be in +3 oxidation states both in the precipitated powder and BiFeO3. The synthesized BFO exhibits a very weak ferromagnetic correlation at room temperature and the degree of which increases slightly on cooling down to 10 K suggesting alteration in the long range spatial modulation of the spins arrangement as compared to the bulk BiFeO3.

  17. Uncertainties in Arctic Precipitation

    Science.gov (United States)

    Majhi, I.; Alexeev, V. A.; Cherry, J. E.; Cohen, J. L.; Groisman, P. Y.

    2012-12-01

    Arctic precipitation is riddled with measurement biases; to address the problem is imperative. Our study focuses on comparison of various datasets and analyzing their biases for the region of Siberia and caution that is needed when using them. Five sources of data were used ranging from NOAA's product (RAW, Bogdanova's correction), Yang's correction technique and two reanalysis products (ERA-Interim and NCEP). The reanalysis dataset performed better for some months in comparison to Yang's product, which tends to overestimate precipitation, and the raw dataset, which tends to underestimate. The sources of bias vary from topography, to wind, to missing data .The final three products chosen show higher biases during the winter and spring season. Emphasis on equations which incorporate blizzards, blowing snow and higher wind speed is necessary for regions which are influenced by any or all of these factors; Bogdanova's correction technique is the most robust of all the datasets analyzed and gives the most reasonable results. One of our future goals is to analyze the impact of precipitation uncertainties on water budget analysis for the Siberian Rivers.

  18. Hourly Precipitation Data (HPD) Publication

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Hourly Precipitation Data (HPD) Publication is archived and available from the National Climatic Data Center (NCDC). This publication contains hourly precipitation...

  19. Uranium (III) precipitation in molten chloride by wet argon sparging

    Science.gov (United States)

    Vigier, Jean-François; Laplace, Annabelle; Renard, Catherine; Miguirditchian, Manuel; Abraham, Francis

    2016-06-01

    In the context of pyrochemical processes for nuclear fuel treatment, the precipitation of uranium (III) in molten salt LiCl-CaCl2 (30-70 mol%) at 705 °C is studied. First, this molten chloride is characterized with the determination of the water dissociation constant. With a value of 10-4.0, the salt has oxoacid properties. Then, the uranium (III) precipitation using wet argon sparging is studied. The salt is prepared using UCl3 precursor. At the end of the precipitation, the salt is totally free of solubilized uranium. The main part is converted into UO2 powder but some uranium is lost during the process due to the volatility of uranium chloride. The main impurity of the resulting powder is calcium. The consequences of oxidative and reductive conditions on precipitation are studied. Finally, coprecipitation of uranium (III) and neodymium (III) is studied, showing a higher sensitivity of uranium (III) than neodymium (III) to precipitation.

  20. Modeling solid-state precipitation

    CERN Document Server

    Nebylov, AlexanderKozeschnik, Ernst

    2012-01-01

    Over recent decades, modeling and simulation of solid-state precipitation has attracted increased attention in academia and industry due to their important contributions in designing properties of advanced structural materials and in increasing productivity and decreasing costs for expensive alloying. In particular, precipitation of second phases is an important means for controlling the mechanical-technological properties of structural materials. However, profound physical modeling of precipitation is not a trivial task. This book introduces you to the classical methods of precipitation model

  1. Tailoring oxides of copper-Cu{sub 2}O and CuO nanoparticles and evaluation of organic dyes degradation

    Energy Technology Data Exchange (ETDEWEB)

    Raghav, Ragini; Aggarwal, Priyanka; Srivastava, Sudha, E-mail: sudha.srivastava@jiit.ac.in [Department of Biotechnology, Jaypee Institute of Information Technology, A-10, Sector-62, Noida-201307,Uttar Pradesh (India)

    2016-04-13

    We report a simple one-pot colloidal synthesis strategy tailoring cuprous or cupric nano-oxides in pure state. NaOH provided alkaline conditions (pH 12.5 -13) for nano-oxides formation, while its concentration regulated the oxidation state of the nano-oxides. The morphological, structural and optical properties of synthesized Cu{sub 2}O and CuO nanoparticles were studied by transmission electron microscopy (TEM), X-Ray diffraction (XRD) and UV-vis spectroscopy. Dye degradation capability of CuO and Cu2O nanoparticles was evaluated using four organic dyes - Malachite green, Methylene blue, Methyl orange and Methyl red. The results demonstrate effective degradation of all four dyes employing with almost comparable activity both Cu{sub 2}O and CuO nanoparticles.

  2. Tailoring oxides of copper-Cu2O and CuO nanoparticles and evaluation of organic dyes degradation

    Science.gov (United States)

    Raghav, Ragini; Aggarwal, Priyanka; Srivastava, Sudha

    2016-04-01

    We report a simple one-pot colloidal synthesis strategy tailoring cuprous or cupric nano-oxides in pure state. NaOH provided alkaline conditions (pH 12.5 -13) for nano-oxides formation, while its concentration regulated the oxidation state of the nano-oxides. The morphological, structural and optical properties of synthesized Cu2O and CuO nanoparticles were studied by transmission electron microscopy (TEM), X-Ray diffraction (XRD) and UV-vis spectroscopy. Dye degradation capability of CuO and Cu2O nanoparticles was evaluated using four organic dyes - Malachite green, Methylene blue, Methyl orange and Methyl red. The results demonstrate effective degradation of all four dyes employing with almost comparable activity both Cu2O and CuO nanoparticles.

  3. Evaluation of the structure and microstructure of Ni{sub x}Mg{sub 1-x}O oxides obtained by co-precipitation; Evaluacion de la estructura y microestructura de oxidos de Ni{sub x}Mg{sub 1-x}O obtenidos por co-precipitacion

    Energy Technology Data Exchange (ETDEWEB)

    Martinez L, G.; Kryshtab, T. [IPN, Escuela Superior de Fisica y Matematicas, Departamento de Fisica, Av. Instituto Politecnico Nacional s/n, Edif. 9, 07738 Mexico D. F. (Mexico); Hesiquio G, M. [IPN, Escuela Superior de Ingenieria Quimica e Industrias Extractivas, Av. Instituto Politecnico Nacional s/n, Edif. 6, 07738 Mexico D. F. (Mexico); Kryvko, A., E-mail: marloz7@yahoo.com.mx [IPN, Escuela Superior de Ingenieria Mecanica y Electrica, Departamento de Sistemas, Av. Instituto Politecnico Nacional s/n, Edif. Z-4, 07738 Mexico D. F. (Mexico)

    2013-06-01

    Ni{sub x}Mg{sub 1-x}O oxides were prepared by thermal treatment at temperatures of 400, 600 and 800 C from a hydrotalcite-like precursor obtained by co-precipitation at constant ph. The oxides obtained were characterized by X-ray diffraction methods. From the obtained results we concluded that the oxides calcined at temperatures of 400, and 600 C are unstable that means that there exists the effect of memory and with a time they return to the precursor. Presence of Ni in Mg oxide provides stability of the compounds thermally treated at 800 C. In order to analyze the structure and microstructure, the reflections 111, 200 and 220 were used. The positions of the maxima of the diffraction peaks are shifted with respect to the simulated ones for Mg O and Ni O. This result reveals that in solid solutions studied compressive strains or vacation are present. The parameters of the microstructure (coherent domain size and micro deformations) were evaluated. The coherent domain size was found to be in the range of 8 - 10 nm and the presence of residual strains of micro deformation can be associated with the existence of extended defects. (Author)

  4. The Global Precipitation Climatology Project (GPCP) Combined Precipitation Dataset

    Science.gov (United States)

    Huffman, George J.; Adler, Robert F.; Arkin, Philip; Chang, Alfred; Ferraro, Ralph; Gruber, Arnold; Janowiak, John; McNab, Alan; Rudolf, Bruno; Schneider, Udo

    1997-01-01

    The Global Precipitation Climatology Project (GPCP) has released the GPCP Version 1 Combined Precipitation Data Set, a global, monthly precipitation dataset covering the period July 1987 through December 1995. The primary product in the dataset is a merged analysis incorporating precipitation estimates from low-orbit-satellite microwave data, geosynchronous-orbit -satellite infrared data, and rain gauge observations. The dataset also contains the individual input fields, a combination of the microwave and infrared satellite estimates, and error estimates for each field. The data are provided on 2.5 deg x 2.5 deg latitude-longitude global grids. Preliminary analyses show general agreement with prior studies of global precipitation and extends prior studies of El Nino-Southern Oscillation precipitation patterns. At the regional scale there are systematic differences with standard climatologies.

  5. Treatment of port-wine stains by photodynamic therapy of cuprous bromide laser%溴化亚铜激光光动力学疗法治疗鲜红斑痣

    Institute of Scientific and Technical Information of China (English)

    唐建民; 刘爱琴; 陈祖林; 杨名娟

    2000-01-01

    运用溴化亚铜激光光动力学疗法治疗鲜红斑痣296例,红斑完全消退185例(62.5%),部分消退111例(37.5%),无效0,并发疤痕15例,证实该疗法疗效确切同时仍需完善。%296 Cases of port-wine stains(PWS) were treated by photodynamic therapy(PDT) of cuprous bromide laser,including which 185 cases (62.5%)gained the result of thorough remission,111 cases (37.5%)gained the result of partial remission and 15 cases complicated with scar formation.PDT is proved to be an effective therapy for PWS while it also needs improving.

  6. Precipitation extremes under climate change

    CERN Document Server

    O'Gorman, Paul A

    2015-01-01

    The response of precipitation extremes to climate change is considered using results from theory, modeling, and observations, with a focus on the physical factors that control the response. Observations and simulations with climate models show that precipitation extremes intensify in response to a warming climate. However, the sensitivity of precipitation extremes to warming remains uncertain when convection is important, and it may be higher in the tropics than the extratropics. Several physical contributions govern the response of precipitation extremes. The thermodynamic contribution is robust and well understood, but theoretical understanding of the microphysical and dynamical contributions is still being developed. Orographic precipitation extremes and snowfall extremes respond differently from other precipitation extremes and require particular attention. Outstanding research challenges include the influence of mesoscale convective organization, the dependence on the duration considered, and the need to...

  7. Effective Assimilation of Global Precipitation

    Science.gov (United States)

    Lien, G.; Kalnay, E.; Miyoshi, T.; Huffman, G. J.

    2012-12-01

    Assimilating precipitation observations by modifying the moisture and sometimes temperature profiles has been shown successful in forcing the model precipitation to be close to the observed precipitation, but only while the assimilation is taking place. After the forecast start, the model tends to "forget" the assimilation changes and lose their extra skill after few forecast hours. This suggests that this approach is not an efficient way to modify the potential vorticity field, since this is the variable that the model would remember. In this study, the ensemble Kalman filter (EnKF) method is used to effectively change the potential vorticity field by allowing ensemble members with better precipitation to receive higher weights. In addition to using an EnKF, two other changes in the precipitation assimilation process are proposed to solve the problems related to the highly non-Gaussian nature of the precipitation variable: a) transform precipitation into a Gaussian distribution based on its climatological distribution, and b) only assimilate precipitation at the location where some ensemble members have positive precipitation. The idea is first tested by the observing system simulation experiments (OSSEs) using SPEEDY, a simplified but realistic general circulation model. When the global precipitation is assimilated in addition to conventional rawinsonde observations, both the analyses and the medium range forecasts are significantly improved as compared to only having rawinsonde observations. The improvement is much reduced when only modifying the moisture field with the same approach, which shows the importance of the error covariance between precipitation and all other model variables. The effect of precipitation assimilation is larger in the Southern Hemisphere than that in the Northern Hemisphere because the Northern Hemisphere analyses are already accurate as a result of denser rawinsonde stations. Assimilation of precipitation using a more comprehensive

  8. Electrical operation of electrostatic precipitators

    CERN Document Server

    Parker, Ken

    2003-01-01

    The electrostatic precipitator remains on of the most cost effective means of controlling the emission of particulates from most industrial processes. This book will be of interest to both users and suppliers of electrostatic precipitators as well as advanced students on environmental based courses. The author identifies the physical and engineering basis for the development of electrical equipment for electrostatic precipitators and thoroughly explores the technological factors which optimize the efficiency of the precipitator and hence minimize emissions, as well as future developments in th

  9. Rising Precipitation Extremes across Nepal

    Directory of Open Access Journals (Sweden)

    Ramchandra Karki

    2017-01-01

    Full Text Available As a mountainous country, Nepal is most susceptible to precipitation extremes and related hazards, including severe floods, landslides and droughts that cause huge losses of life and property, impact the Himalayan environment, and hinder the socioeconomic development of the country. Given that the countrywide assessment of such extremes is still lacking, we present a comprehensive picture of prevailing precipitation extremes observed across Nepal. First, we present the spatial distribution of daily extreme precipitation indices as defined by the Expert Team on Climate Change Detection, Monitoring and Indices (ETCCDMI from 210 stations over the period of 1981–2010. Then, we analyze the temporal changes in the computed extremes from 76 stations, featuring long-term continuous records for the period of 1970–2012, by applying a non-parametric Mann−Kendall test to identify the existence of a trend and Sen’s slope method to calculate the true magnitude of this trend. Further, the local trends in precipitation extremes have been tested for their field significance over the distinct physio-geographical regions of Nepal, such as the lowlands, middle mountains and hills and high mountains in the west (WL, WM and WH, respectively, and likewise, in central (CL, CM and CH and eastern (EL, EM and EH Nepal. Our results suggest that the spatial patterns of high-intensity precipitation extremes are quite different to that of annual or monsoonal precipitation. Lowlands (Terai and Siwaliks that feature relatively low precipitation and less wet days (rainy days are exposed to high-intensity precipitation extremes. Our trend analysis suggests that the pre-monsoonal precipitation is significantly increasing over the lowlands and CH, while monsoonal precipitation is increasing in WM and CH and decreasing in CM, CL and EL. On the other hand, post-monsoonal precipitation is significantly decreasing across all of Nepal while winter precipitation is decreasing

  10. 酒石酸对直接沉淀法制备纳米Bi2O3晶体结构的影响%Effect of Tartaric Acid on Crystal Type of Bismuth Oxide Nano-particles Prepared by Direct Precipitation Method

    Institute of Scientific and Technical Information of China (English)

    刘芳芳; 戴亚堂; 张欢; 赵文

    2011-01-01

    以高氯酸铋和氢氧化钠为原料,采用一步直接沉淀法,通过添加和控制酒石酸的用量,制备出纺锤形的纳米氧化铋粒子,采用X射线衍射、扫描电镜和差热分析等手段对产品进行分析与表征,并且对反应机理进行初步分析.结果表明;当酒石酸盐的质量分数为8%左右时,合成的纳米氧化铋为纺锤形,粒子分布均匀,粒度较小,平均粒度约为90 nm.%Using Bi(ClO3)]3and NaOH as raw materials, adding and controlling the concentration of tartaric acid, the spindle bismuth oxide nano-particles were synthesized by direct precipitation method. The particles characterized by X ray diffraction (XRD), scan electron microscopy(SEM) and thermogravimetry-differential scanning calorimetry(TGDSC). The reaction mechanism of bismuth oxide nano-particles was discussed. The results showed that the as-prepared bismuth oxide nano-particles had uniform size distribution and smaller granularity, when the mass fraction of taitaric acid was 8%, the mean particle size was about 90 nm.

  11. Uranium (III) precipitation in molten chloride by wet argon sparging

    Energy Technology Data Exchange (ETDEWEB)

    Vigier, Jean-François, E-mail: jean-francois.vigier@ec.europa.eu [CEA, Nuclear Energy Division, Radiochemistry & Processes Department, F-30207 Bagnols sur Cèze (France); Unité de Catalyse et de Chimie du Solide, UCCS UMR CNRS 8181, Univ. Lille Nord de France, ENSCL-USTL, B.P. 90108, 59652 Villeneuve d' Ascq Cedex (France); Laplace, Annabelle [CEA, Nuclear Energy Division, Radiochemistry & Processes Department, F-30207 Bagnols sur Cèze (France); Renard, Catherine [Unité de Catalyse et de Chimie du Solide, UCCS UMR CNRS 8181, Univ. Lille Nord de France, ENSCL-USTL, B.P. 90108, 59652 Villeneuve d' Ascq Cedex (France); Miguirditchian, Manuel [CEA, Nuclear Energy Division, Radiochemistry & Processes Department, F-30207 Bagnols sur Cèze (France); Abraham, Francis [Unité de Catalyse et de Chimie du Solide, UCCS UMR CNRS 8181, Univ. Lille Nord de France, ENSCL-USTL, B.P. 90108, 59652 Villeneuve d' Ascq Cedex (France)

    2016-06-15

    In the context of pyrochemical processes for nuclear fuel treatment, the precipitation of uranium (III) in molten salt LiCl-CaCl{sub 2} (30–70 mol%) at 705 °C is studied. First, this molten chloride is characterized with the determination of the water dissociation constant. With a value of 10{sup −4.0}, the salt has oxoacid properties. Then, the uranium (III) precipitation using wet argon sparging is studied. The salt is prepared using UCl{sub 3} precursor. At the end of the precipitation, the salt is totally free of solubilized uranium. The main part is converted into UO{sub 2} powder but some uranium is lost during the process due to the volatility of uranium chloride. The main impurity of the resulting powder is calcium. The consequences of oxidative and reductive conditions on precipitation are studied. Finally, coprecipitation of uranium (III) and neodymium (III) is studied, showing a higher sensitivity of uranium (III) than neodymium (III) to precipitation. - Highlights: • Precipitation of Uranium (III) is quantitative in molten salt LiCl-CaCl{sub 2} (30–70 mol%). • The salt is oxoacid with a water dissociation constant of 10{sup −4.0} at 705 °C. • Volatility of uranium chloride is strongly reduced in reductive conditions. • Coprecipitation of U(III) and Nd(III) leads to a consecutive precipitation of the two elements.

  12. Precipitation in the Solar System

    Science.gov (United States)

    McIntosh, Gordon

    2007-01-01

    As an astronomy instructor, I am always looking for commonly observed Earthly experiences to help my students and me understand and appreciate similar occurrences elsewhere in the solar system. Recently I wrote a short TPT article on frost. This paper is on the related phenomena of precipitation. Precipitation, so common on most of the Earth's…

  13. Precipitation in the Solar System

    Science.gov (United States)

    McIntosh, Gordon

    2007-01-01

    As an astronomy instructor, I am always looking for commonly observed Earthly experiences to help my students and me understand and appreciate similar occurrences elsewhere in the solar system. Recently I wrote a short TPT article on frost. This paper is on the related phenomena of precipitation. Precipitation, so common on most of the Earth's…

  14. Modeling solid-state precipitation

    CERN Document Server

    Nebylov, AlexanderKozeschnik, Ernst

    2012-01-01

    Over recent decades, modeling and simulation of solid-state precipitation has attracted increased attention in academia and industry due to their important contributions in designing properties of advanced structural materials and in increasing productivity and decreasing costs for expensive alloying. In particular, precipitation of second phases is an important means for controlling the mechanical-technological properties of structural materials. However, profound physical modeling of precipitation is not a trivial task. This book introduces you to the classical methods of precipitation modeling and to recently-developed advanced, computationally-efficient techniques. If you're a research professional, academic, or student, you'll learn: nucleation theory, precipitate growth, calculation of interfacial energies. advanced techniques for technologically relevant multicomponent systems and complex thermo-mechanical treatments. numerical approaches using evolution equations and discrete particle size distribu...

  15. Encoding information into precipitation structures

    Science.gov (United States)

    Martens, Kirsten; Bena, Ioana; Droz, Michel; Rácz, Zoltan

    2008-12-01

    Material design at submicron scales would be profoundly affected if the formation of precipitation patterns could be easily controlled. It would allow the direct building of bulk structures, in contrast to traditional techniques which consist of removing material in order to create patterns. Here, we discuss an extension of our recent proposal of using electrical currents to control precipitation bands which emerge in the wake of reaction fronts in A+ + B- → C reaction-diffusion processes. Our main result, based on simulating the reaction-diffusion-precipitation equations, is that the dynamics of the charged agents can be guided by an appropriately designed time-dependent electric current so that, in addition to the control of the band spacing, the width of the precipitation bands can also be tuned. This makes straightforward the encoding of information into precipitation patterns and, as an amusing example, we demonstrate the feasibility by showing how to encode a musical rhythm.

  16. Role of oxygen flow rate on the structural and optical properties of copper oxide thin films grown by reactive magnetron sputtering

    Science.gov (United States)

    Ali, M.; Gobinner, C. R.; Kekuda, D.

    2016-02-01

    Copper oxide thin films were grown by DC reactive magnetron sputtering. The structural investigation of the sputtered films was carried out using X-ray diffraction. The surface morphology of the films was observed through atomic force microscopy. A crossover in the crystalline phase from cuprous to cupric oxide (tenorite) was observed as a result of variation in the oxygen flow rate during sputtering. Deposition rate was also found to be a function of the oxygen flow rate, and it was found that the deposition rate decreased with an increase in the oxygen flow rate which could be attributed to the possible target oxidation at higher oxygen flow rates. Variation of grain size of the films with oxygen flow rate was analyzed through AFM analysis. Dependence of oxygen flow rate on the formation of two phases of copper oxide was also confirmed through the optical band gap measurements.

  17. Development of a methodology for the separation of europium and samarium from a mixture of rare earth oxides by electroreduction/ precipitation; Desenvolvimento de uma metodologia para a separacao de samario e europio a partir de mistura de oxidos de terras raras por reducao eletroquimica/precipitacao

    Energy Technology Data Exchange (ETDEWEB)

    Chepcanoff, Vera

    2006-07-01

    The rare earths (RE) were first used in 1903, when Welsbach developed a lighter that is still used today. Nowadays, the RE are employed in many different fields, as in the production of super-alloys , as catalysts for petroleum industry, in the manufacture of non-ferrous alloys, color television tubes, x-ray screens, special glasses, ceramics, computer industries, nuclear medicine, lasers, pigments, etc., moving, in the last decade , a market of US$ 2 billions per year. Due to their similar properties, the RE elements are very difficult to separate, requiring complex processes, what make the products very expensive. Elements like Eu and Sm, which contents in the minerals are low (0.05% and 2.0%, respectively, in monazite) are extremely expensive, but their field of application justifies the research for looking for other processes, more simple and/or more effective. Trivalent state is a characteristic of all RE, but some of them presents oxidation state +2, like Ce, Eu, Sm and Yb. In the case of Eu and Sm, the focus of the present work, the divalent state is achieved by electro-reduction in the potentials -0.65 and -1.55 (SCE), respectively. This makes possible the separation of these elements from the other rare earths and from each other. Thus, making use of this characteristic, a process for the individual separation of Eu and Sm in (NH{sub 4}){sub 2}SO{sub 4} solution by electro-reduction/precipitation is proposed, where Sm is first separated from the solution as sulfate, and Eu, that remains in the solution, is precipitated after the decrease of temperature and potential applied. The process developed from a synthetic Eu and Sm solution was applied to a mixture of semi-heavy RE oxide, produced at IPEN-CNEN/SP, obtaining the separation of Sm. This product was analyzed by spectrophotometry, showing high purity. (author)

  18. Precipitation of iron in windopane oyster shells by marine shell-boring cyanobacteria

    Digital Repository Service at National Institute of Oceanography (India)

    Raghukumar, C.; Rao, V.P.; Iyer, S.D.

    electron microscopy, suggested the presence of iron as iron oxides. The cyanobacteria from such black shells were cultured in enriched seawater medium. In this medium also they precipitated iron as confirmed by Prussian blue reaction. They were identified...

  19. Effect of manganese sulfide on the precipitation behavior of tin in steel

    Institute of Scientific and Technical Information of China (English)

    Gui-lin Sun; Bo Song; Ling-zhi Yang; Su-fen Tao; Yong Yang

    2014-01-01

    Tramp elements such as tin are considered harmful to steel because of hot brittleness they induce at high temperatures. Because tramp elements retained in steel scrap will be enriched in new steel due to the difficultly of their removal, studies on the precipitation behav-ior of tin are essential. In this study, the effects of different inclusions on the precipitation behavior of tin in steel were studied. The results show that the tin-rich phase precipitates at austenite grain boundaries in an Fe–5%Sn alloy without MnS precipitates, whereas Sn precipitates at the boundaries of MnS inclusions in steel that contains MnS precipitates. MnS is more effective than silicon dioxide or aluminum oxide as a nucleation site for the precipitation of the tin phase, which is consistent with the disregistry between the lattice parameters of the tin phase and those of the inclusions.

  20. Cadmium, lead and silver adsorption in hydrous niobium oxide(V) prepared by precipitation in homogeneous solution method; Adsorcao de chumbo, cadmio e prata em oxido de niobio(V) hidratado preparado pelo metodo da precipitacao em solucao homogenea

    Energy Technology Data Exchange (ETDEWEB)

    Tagliaferro, Geronimo V.; Pereira, Paulo Henrique F.; Rodrigues, Liana Alvares; Silva, Maria Lucia Caetano Pinto da, E-mail: fernandes_eng@yahoo.com.b [Universidade de Sao Paulo (USP), Lorena, SP (Brazil). Escola de Engenharia. Dept. de Engenharia Quimica

    2011-07-01

    This paper describes the adsorption of heavy metals ions from aqueous solution by hydrous niobium oxide. Three heavy metals were selected for this study: cadmium, lead and silver. Adsorption isotherms were well fitted by Langmuir model. Maximum adsorption capacity (Q{sub 0}) for Pb{sup 2+}, Ag{sup +} and Cd{sup 2+} was found to be 452.5, 188.68 and 8.85 mg g{sup -1}, respectively. (author)

  1. Preparation and Photocatalytic Sterilization Property of Cu_2O Nanostructure with Copper Anode Oxidation Method%Cu_2O纳米阵列的铜阳极氧化法制备及其光催化杀菌性能研究

    Institute of Scientific and Technical Information of China (English)

    闫丽丽; 王艳; 熊良斌; 李家麟; 某浩然; 王保强; 余颖

    2009-01-01

    本文通过阳极氧化法直接在铜片上生长出纳米氧化亚铜阵列,所得到的样品通过扫描电子显微镜(SEM),紫外可见漫反射(UV-Vis diffuser reflectance),X-射线光电子能谱(XPS)等方法进行了表征,并研究了不同形貌氧化亚铜的杀菌效果.实验结果表明:反应过程中在阳极液中加入一定量的CTAB,有助于氧化亚铜的定向生长.通过控制反应条件(如电流密度,温度,和反应时间),可以得到不同形貌的氧化亚铜.随着电流密度的增大,氧化亚铜的形貌从网状,片状到棒状进行转化.所得到氧化亚铜的禁带宽度为1.95 eV.用所得样品进行杀菌实验,1 h内棒状氧化亚铜的杀菌率达到90.85%,而其它形貌的氧化亚铜杀菌率只有50%左右,与空铜片的杀菌率30%相比,所制得氧化亚铜具有较好的杀菌效果.%Cuprous oxide nanostructures were prepared by the method of copper anode oxidation. The obtained cuprous oxide was characterized with the techques of scanning electron microscopy, UV-Vis diffuse reflectance and X-ray photoelectron spectroscopy. The sterilization property of the samples was also investigated. It is found that CTAB plays an important role in the directional growth of the cuprous oxide. By controlling the reaction condition, such as current density, temperature and the reaction time, we can get different morphologies of Cu_2O. With the increase of current density, the morphology of Cu_2O can be nanonet, nanosheet and nanorod arrays respectively. In addition, the nanorod cuprous oxide has the best activity in sterilization and the sterilization efficiency can reach 90.85% in an hour.

  2. Atrial Ectopics Precipitating Atrial Fibrillation

    OpenAIRE

    Johnson Francis

    2015-01-01

    Holter monitor tracing showing blocked atrial ectopics and atrial ectopic precipitating atrial fibrillation is being demonstrated. Initially it was coarse atrial fibrillation, which rapidly degenerated into fine atrial fibrillation.

  3. CPC Merged Analysis of Precipitation

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The monthly data set consists of two files containing global monthly averaged precipitation rate values at a 2.5x2.5 resolution starting in 1979. Values are obtained...

  4. Hourly and Daily Precipitation Data

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Precipitation reports submitted on many form types, including tabular and autographic charts. Reports are almost exclusively from the US Cooperative Observer Network.

  5. 水相中金属铜表面生成亚铜-邻菲罗啉配合物的反应%FORMATION OF BIS ( 1 , 10-PHENANTHROLINE) CUPROUS COMPLEXES ON METALLIC COPPER SURFACE IN AQUEOUS SOLUTION

    Institute of Scientific and Technical Information of China (English)

    聂崇实; 顾亦君; 孙杰

    1996-01-01

    本文研究了零价铜在邻菲罗啉水溶液中的反应.当溶液敞露于空气并存在有机阴离子X-时,例如苯甲酸盐(Bz)、对甲基苯磺酸盐(Ts)等,铜的表面生成了致密的反应产物的薄层,经IR、UV/VIS、MS和元素分析证明了该薄层为相当纯的亚铜的邻菲罗啉配位化合物,结构为[Cu(phen)2]+X-.在乙醇/甲苯混合溶剂中得到了表面反应产物的晶体[Cu(phen)2](CH3C4H6SO3)C2HsOH,并用X-ray测得了结构.本工作表明溶液中的Cu1离子抑制Cu0氧化成Cu1而影响反应层的形成,同时又促进Cu1氧化成Cu1的过程.%The formation of cuprous complex on metallic copper surface in 1,10-phenanthroline (phen) aqueous solution has been investigated as exposed in air and in the presence of common organic anions (X-) such as benzoate (Bz-) and toluene sulphonate (Ts-). The complexes deposited on the surface of metallic copper have been proved to be rather pure cuprous phenanthroline complexes having the structure [Cu(phen)2]X based on the elemental analysis, IR, UV/C2H5OH was determined by X-ray diffraction analysis. The work demonstrated that the Cu1 ion in the reaction solution hindered the process of Cu0 to Cu1 and in the meanwhile accelerated the process of Cu 1 to Cu 1.

  6. Metal particle's precipitation behavior in direct reading ferrography precipitator tube

    Institute of Scientific and Technical Information of China (English)

    尹凤福; 李谋渭

    2004-01-01

    A new metal particle monitoring instrument was developed by improving the traditional direct reading ferrography. The precipitation behaviors of sub-magnetic particles, magnetic particles, and the mixture of these particles were examined with the instrument. The results show that the precipitation behavior of sub-magnetic metal particles of copper and aluminum is not random as it was believed previously. The sub-magnetic particles show a distribution in the precipitator tube, almost the same as the deposition curves as the magnetic particles have. The deposition amount of particles is increased in the oil which consists of several different kinds of particles. On the base of these experiments, a new index used for the total quantity of wear was redefined.

  7. The Global Precipitation Measurement Mission

    Science.gov (United States)

    Jackson, Gail

    2014-05-01

    The Global Precipitation Measurement (GPM) mission's Core satellite, scheduled for launch at the end of February 2014, is well designed estimate precipitation from 0.2 to 110 mm/hr and to detect falling snow. Knowing where and how much rain and snow falls globally is vital to understanding how weather and climate impact both our environment and Earth's water and energy cycles, including effects on agriculture, fresh water availability, and responses to natural disasters. The design of the GPM Core Observatory is an advancement of the Tropical Rainfall Measuring Mission (TRMM)'s highly successful rain-sensing package [3]. The cornerstone of the GPM mission is the deployment of a Core Observatory in a unique 65o non-Sun-synchronous orbit to serve as a physics observatory and a calibration reference to improve precipitation measurements by a constellation of 8 or more dedicated and operational, U.S. and international passive microwave sensors. The Core Observatory will carry a Ku/Ka-band Dual-frequency Precipitation Radar (DPR) and a multi-channel (10-183 GHz) GPM Microwave Radiometer (GMI). The DPR will provide measurements of 3-D precipitation structures and microphysical properties, which are key to achieving a better understanding of precipitation processes and improving retrieval algorithms for passive microwave radiometers. The combined use of DPR and GMI measurements will place greater constraints on possible solutions to radiometer retrievals to improve the accuracy and consistency of precipitation retrievals from all constellation radiometers. Furthermore, since light rain and falling snow account for a significant fraction of precipitation occurrence in middle and high latitudes, the GPM instruments extend the capabilities of the TRMM sensors to detect falling snow, measure light rain, and provide, for the first time, quantitative estimates of microphysical properties of precipitation particles. The GPM Core Observatory was developed and tested at NASA

  8. Are hourly precipitation extremes increasing faster than daily precipitation extremes?

    Science.gov (United States)

    Barbero, Renaud; Fowler, Hayley; Blenkinsop, Stephen; Lenderink, Geert

    2016-04-01

    Extreme precipitation events appear to be increasing with climate change in many regions of the world, including the United States. These extreme events have large societal impacts, as seen during the recent Texas-Oklahoma flooding in May 2015 which caused several billion in damages and left 47 deaths in its path. Better understanding of past changes in the characteristics of extreme rainfall events is thus critical for reliable projections of future changes. Although it has been documented in several studies that daily precipitation extremes are increasing across parts of the contiguous United States, very few studies have looked at hourly extremes. However, this is of primary importance as recent studies on the temperature scaling of extreme precipitation have shown that increases above the Clausius-Clapeyron (~ 7% °C-1) are possible for hourly precipitation. In this study, we used hourly precipitation data (HPD) from the National Climatic Data Center and extracted more than 1,000 stations across the US with more than 40 years of data spanning the period 1950-2010. As hourly measurements are often associated with a range of issues, the data underwent multiple quality control processes to exclude erroneous data. While no significant changes were found in annual maximum precipitation using both hourly and daily resolution datasets, significant increasing trends in terms of frequency of episodes exceeding present-day 95th percentiles of wet hourly/daily precipitation were observed across a significant portion of the US. The fraction of stations with significant increasing trends falls outside the confidence interval range during all seasons but the summer. While less than 12% of stations exhibit significant trends at the daily scale in the wintertime, more than 45% of stations, mostly clustered in central and Northern United States, show significant increasing trends at the hourly scale. This suggests that short-duration storms have increased faster than daily

  9. Acid precipitation: effects on forest and fish. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Overrein, L.N.; Seip, H.M.; Tollan, A.

    1980-12-01

    This interdisciplinary research program was launched in 1972 in response to concern in Scandinavian countries that acid precipitation was causing changes to the natural environment. A major hypothesis was that anthropogenic release of sulfur oxides and other pollutants may alter geobiochemical and biochemical cycles with consequences for the biota. The main research efforts were directed towards possible threats to forest and freshwater fish. Results of the entire program are summarized. Information is presented under the following section headings: emissions and transport; atmospheric deposits in Norway; water acidification - status and trends; chemical modifications of precipitation in contact with soil and vegetation; snow and snowmelt; land-use changes and acidification; effects of acid precipitation on soil productivity and plant growth; and effects of acid water on aquatic life.

  10. Continuous Precipitation of Ceria Nanoparticles from a Continuous Flow Micromixer

    Energy Technology Data Exchange (ETDEWEB)

    Tseng, Chih Heng; Paul, Brian; Chang, Chih-hung; Engelhard, Mark H.

    2013-01-01

    Cerium oxide nanoparticles were continuously precipitated from a solution of cerium(III) nitrate and ammonium hydroxide using a micro-scale T-mixer. Findings show that the method of mixing is important in the ceria precipitation process. In batch mixing and deposition, disintegration and agglomeration dominates the deposited film. In T-mixing and deposition, more uniform nanorod particles are attainable. In addition, it was found that the micromixing approach reduced the exposure of the Ce(OH)3 precipates to oxygen, yielding hydroxide precipates in place of CeO2 precipitates. Advantages of the micro-scale T-mixing approach include shorter mixing times, better control of nanoparticle shape and less agglomeration.

  11. Homogeneous Precipitation Synthesis and Magnetic Properties of Cobalt Ferrite Nanoparticles

    Directory of Open Access Journals (Sweden)

    Zhigang Liu

    2008-01-01

    Full Text Available Magnetic nanoparticles (NPs of cobalt ferrite have been synthesized via a homogeneous precipitation route using hexamethylenetetramine (HMT as the precipitant. The particle size, crystal structure, and magnetic properties of the synthesized particles were investigated by X-ray diffraction, transmission electron microscopy, and vibrating sample magnetometer. The NPs are of cubic inverse spinel structure and nearly spherical shape. With the increase of oxidation time from 30 to 180 minutes in the reaction solution at 90∘C, the average particle size increases from ~30 nm to ~45 nm. The as-synthesized NPs ~30 nm in size show higher Ms (61.5 emu/g and moderate Hc (945 Oe and Mr/Ms (0.45 value compared with the materials synthesized by coprecipitation method using NaOH as precipitate at high pH value.

  12. Towards Quantitative Ocean Precipitation Validation

    Science.gov (United States)

    Klepp, C.; Bakan, S.; Andersson, A.

    2009-04-01

    A thorough knowledge of global ocean precipitation is an indispensable prerequisite for the understanding and successful modelling of the global climate system as it is an important component of the water cycle. However, reliable detection of quantitative precipitation over the global oceans, especially at high latitudes during the cold season remains a challenging task for remote sensing and model based estimates. Quantitative ship validation data using reliable instruments for measuring rain and snowfall hardly exist but are highly demanded for ground validation of such products. The satellite based HOAPS (Hamburg Ocean Atmosphere Parameters and Fluxes from Satellite Data) climatology contains fields of precipitation, evaporation and the resulting freshwater flux along with 12 additional atmospheric parameters over the global ice-free ocean between 1987 and 2005. Except for the NOAA Pathfinder SST, all basic state variables are calculated from SSM/I passive microwave radiometer measurements. HOAPS contains three main data subsets that originate from one common pixel-level data source. Gridded 0.5 degree monthly, pentad and twice daily data products are freely available from www.hoaps.org. Especially for North Atlantic mid-latitude mix-phase precipitation, the HOAPS precipitation retrieval has been investigated in some depth. This analysis revealed that the HOAPS retrieval qualitatively well represents cyclonic and intense mesoscale precipitation in agreement with ship observations and Cloudsat data, while GPCP, ECMWF forecast, ERA-40 and regional model data miss mesoscale precipitation substantially. As the differences between the investigated data sets are already large under mix-phase precipitation conditions, further work is carried out on snowfall validation during the cold season at high-latitudes. A Norwegian Sea field campaign in winter 2005 was carried out using an optical disdrometer capable of measuring quantitative amounts of snowfall over the ocean

  13. Measurement of precipitation using lysimeters

    Science.gov (United States)

    Fank, Johann; Klammler, Gernot

    2013-04-01

    Austria's alpine foothill aquifers contain important drinking water resources, but are also used intensively for agricultural production. These groundwater bodies are generally recharged by infiltrating precipitation. A sustainable water resources management of these aquifers requires quantifying real evapotranspiration (ET), groundwater recharge (GR), precipitation (P) and soil water storage change (ΔS). While GR and ΔS can be directly measured by weighable lysimeters and P by separate precipitation gauges, ET is determined by solving the climatic water balance ET = P GR ± ΔS. According to WMO (2008) measurement of rainfall is strongly influenced by precipitation gauge errors. Most significant errors result from wind loss, wetting loss, evaporation loss, and due to in- and out-splashing of water. Measuring errors can be reduced by a larger area of the measuring gaugés surface and positioning the collecting vessel at ground level. Modern weighable lysimeters commonly have a surface of 1 m², are integrated into their typical surroundings of vegetation cover (to avoid oasis effects) and allow scaling the mass change of monolithic soil columns in high measuring accuracy (0.01 mm water equivalent) and high temporal resolution. Thus, also precipitation can be quantified by measuring the positive mass changes of the lysimeter. According to Meissner et al. (2007) also dew, fog and rime can be determined by means of highly precise weighable lysimeters. Furthermore, measuring precipitation using lysimeters avoid common measuring errors (WMO 2008) at point scale. Though, this method implicates external effects (background noise, influence of vegetation and wind) which affect the mass time series. While the background noise of the weighing is rather well known and can be filtered out of the mass time series, the influence of wind, which blows through the vegetation and affects measured lysimeter mass, cannot be corrected easily since there is no clear relation between

  14. Kinetics of asphaltene precipitation from crude oils

    Energy Technology Data Exchange (ETDEWEB)

    Maqbool, T.; Hussein, I.A.; Fogler, H.S. [Michigan Univ., Ann Arbor (United States). Dept. of Chemical Engineering

    2008-07-01

    The kinetics of asphaltene precipitation from crude oils was investigated using n-alkane precipitants. Recent studies have shown that there is a kinetic phenomenon associated with asphaltene precipitation. This study showed that the time needed to precipitate the asphaltenes can vary from a few minutes to several months, depending on the amount of n-alkane precipitant added. As such, the onset of asphaltene precipitation is a function of the concentration of precipitant and time. A technique to quantify the amount of asphaltenes precipitated as a function of time and precipitant concentration was presented. This study also investigated the kinetic effects caused by various precipitants. Optical microscopy was used to monitor the growth of asphaltene aggregates with time. Refractive index measurements provided further insight into the kinetics of asphaltene precipitation. Polarity based fractionation and dielectric constant measurements were used to compare the nature of asphaltenes precipitated early in the precipitation process with the asphaltenes precipitated at later times. It was concluded that asphaltenes precipitating at different times from the same crude oil-precipitant mixture are different from one another. 3 refs.

  15. Particle precipitation in connection with KOH etching of silicon

    DEFF Research Database (Denmark)

    Nielsen, Christian Bergenstof; Christensen, Carsten; Pedersen, Casper

    2004-01-01

    This paper considers the precipitation of iron oxide particles in connection with the KOH etching of cavities in silicon wafers. The findings presented in this paper suggest that the source to the particles is the KOH pellets used for making the etching solution. Experiments show that the precipi...... of the change in free energy of adsorption, the Pourbaix diagram, the electrochemical double- layer thickness and silicon dopant type, and concentration. (C) 2004 The Electrochemical Society.......This paper considers the precipitation of iron oxide particles in connection with the KOH etching of cavities in silicon wafers. The findings presented in this paper suggest that the source to the particles is the KOH pellets used for making the etching solution. Experiments show...... that the precipitation is independent of KOH etching time, but that the amount of deposited material varies with dopant type and dopant concentration. The experiments also suggest that the precipitation occurs when the silicon wafers are removed from the KOH etching solution and not during the etching procedure. When...

  16. Radar-Derived Quantitative Precipitation Estimation Based on Precipitation Classification

    Directory of Open Access Journals (Sweden)

    Lili Yang

    2016-01-01

    Full Text Available A method for improving radar-derived quantitative precipitation estimation is proposed. Tropical vertical profiles of reflectivity (VPRs are first determined from multiple VPRs. Upon identifying a tropical VPR, the event can be further classified as either tropical-stratiform or tropical-convective rainfall by a fuzzy logic (FL algorithm. Based on the precipitation-type fields, the reflectivity values are converted into rainfall rate using a Z-R relationship. In order to evaluate the performance of this rainfall classification scheme, three experiments were conducted using three months of data and two study cases. In Experiment I, the Weather Surveillance Radar-1988 Doppler (WSR-88D default Z-R relationship was applied. In Experiment II, the precipitation regime was separated into convective and stratiform rainfall using the FL algorithm, and corresponding Z-R relationships were used. In Experiment III, the precipitation regime was separated into convective, stratiform, and tropical rainfall, and the corresponding Z-R relationships were applied. The results show that the rainfall rates obtained from all three experiments match closely with the gauge observations, although Experiment II could solve the underestimation, when compared to Experiment I. Experiment III significantly reduced this underestimation and generated the most accurate radar estimates of rain rate among the three experiments.

  17. Preparation of uniform mixed metal oxide and superconductive oxides

    Energy Technology Data Exchange (ETDEWEB)

    Barder, T.J.

    1991-04-30

    This paper describes a method for producing a uniform mixed metal oxide. It includes dissolving metals as their salts of a carboxylic acid in an aliphatic alcohol in the substantial absence of water, the metals are in the same proportions as in the corresponding mixed metal oxide; co-precipitating the metals as their oxalates by mixing the alcohol solution with oxalic acid; separating the co-precipitated metal oxalates and calcining the oxalates in air or oxygen above about 500{degrees} C to convert the oxalates to the corresponding metal oxides.

  18. How often precipitation records break?

    Science.gov (United States)

    Papalexiou, Simon Michael; Oikonomou, Maria; Floutsakou, Athina; Bessas, Nikolaos; Mamassis, Nikos

    2016-04-01

    How often precipitation records break? Are there any factors that determine the average time needed for the next maximum to occur? In order to investigate these simple questions we use several hundreds of daily precipitation records (more than 100 years long each) and we study the time intervals between each successive maximum precipitation value. We investigate if the record breaking time interval is related (a) to the autocorrelation structure, (b) to probability dry, and (c) to the tail of the marginal distribution. For the last, we first, evaluate which type of tail is better fitted by choosing among three general types of tails corresponding to the distributions Pareto, Lognormal and Weibull; and second, we assess the heaviness of the tail based on the estimated shape parameter. The performance of each tail is evaluated in terms of return period values, i.e., we compare the empirical return periods of precipitation values above a threshold with the predicted ones by each of the three types of fitted tails.

  19. Experimental study of brushite precipitation

    Science.gov (United States)

    Arifuzzaman, S. M.; Rohani, S.

    2004-07-01

    A systematic approach was developed for the synthesis of orthophosphates in the laboratory. A set of experiments was designed to investigate the influence of initial calcium and phosphorus concentration on the precipitated phase, nucleation pH and product size distribution at 25°C. Another goal was to characterize the precipitated phase. The investigation was conducted in a batch reactor. The initial molar concentration of calcium chloride and hydrated sodium phosphate solutions was varied from 0.005 to 0.08-mole dm -3 and the solution pH was kept under 7.1. Analysis by powder XRD, FTIR and elemental P/Ca revealed that the crystals precipitated were pure brushite (dicalcium phosphate dihydrate), as expected, except in one experiment in which amorphous calcium phosphate precipitated. The brushite crystals produced had plate-like morphology as investigated by scanning electron microscopy (SEM). The nucleation pH showed a decreasing trend as the concentration of the calcium and phosphorus increased in the reactor, but the volume mean diameter of the crystals and the span of the crystal size distribution did not show any sensitivity to the changes in the initial calcium and phosphorus concentration.

  20. Electrostatic Precipitator (ESP) TRAINING MANUAL

    Science.gov (United States)

    The manual assists engineers in using a computer program, the ESPVI 4.0W, that models all elements of an electrostatic precipitator (ESP). The program is a product of the Electric Power Research Institute and runs in the Windows environment. Once an ESP is accurately modeled, the...

  1. Grassland responses to precipitation extremes

    Science.gov (United States)

    Grassland ecosystems are naturally subjected to periods of prolonged drought and sequences of wet years. Climate change is expected to enhance the magnitude and frequency of extreme events at the intraannual and multiyear scales. Are grassland responses to extreme precipitation simply a response to ...

  2. Dextran-modified iron oxide nanoparticles

    Institute of Scientific and Technical Information of China (English)

    Ji(r)í Hradil; Alexander Pisarev; Michal Babi(c); Daniel Horák

    2007-01-01

    Dextran-modified iron oxide nanoparticles were prepared by precipitation of Fe(Ⅱ) and Fe(Ⅲ) salts with ammonium hydroxide by two methods.Iron oxide was precipitated either in the presence of dextran solution, or the dextran solution was added after precipitation. In the second method,the iron oxide particle size and size distribution could be controlled depending on the concentration of dextran in the solution. The nanoparticles were characterized by size-exclusion chromatography, transmission electron microscopy and dynamic light scattering. Optimal conditions for preparation of stable iron oxide colloid particles were determined. The dextran/iron oxide ratio 0-0.16 used in precipitation of iron salts can be recommended for synthesis of nanoparticles suitable for biomedical applications, as the colloid does not contain excess dextran and does not coagulate.

  3. 混凝沉淀-生物法-高级氧化处理颜料废水工程应用%Engineering appIication of coaguIation precipitation-bioIogicaI process-advanced oxidation process to the treatment of pigment wastewater

    Institute of Scientific and Technical Information of China (English)

    董建威; 司马卫平

    2015-01-01

    某颜料企业针对其排放的高浓度有机废水,采用混凝沉淀—生物法—高级氧化的组合工艺进行处理。工程实践表明:在系统维持相对稳定的情况下,经处理后的出水水质达到了《污水综合排放标准》(GB 8978—1996)的一级标准要求。%Aiming at the problems that the wastewater from a pigment enterprise contains highly concentrated orga-nics,the combined process coagulation precipitation-biological method-advanced oxidation,has been used for its treatment. The engineering practice shows that when the systems conditions keep relatively stable ,the effluent water quality can meet the requirements of I-class criteria specified in the Integrated Wastewater Discharge Standard (GB 8978—1996).

  4. Mesoporous metal oxide graphene nanocomposite materials

    Science.gov (United States)

    Liu, Jun; Aksay, Ilhan A.; Kou, Rong; Wang, Donghai

    2016-05-24

    A nanocomposite material formed of graphene and a mesoporous metal oxide having a demonstrated specific capacity of more than 200 F/g with particular utility when employed in supercapacitor applications. A method for making these nanocomposite materials by first forming a mixture of graphene, a surfactant, and a metal oxide precursor, precipitating the metal oxide precursor with the surfactant from the mixture to form a mesoporous metal oxide. The mesoporous metal oxide is then deposited onto a surface of the graphene.

  5. Trends in Precipitation Extremes over Southeast Asia

    Science.gov (United States)

    Endo, N.; Matsumoto, J.

    2010-12-01

    Trends in precipitation extremes were examined using daily precipitation data from Southeast Asian countries during 1950's to 2000's. Number of wet day, defined by a day with daily precipitation exceeding 1 mm, tends to decrease over these countries, while average precipitation intensity of wet day shows an increasing trend. Heavy precipitation indices, which are defined by precipitation amount and percentile, demonstrate that the number of stations with significant upward trend is larger than that with significant downward trend. Heavy precipitation increases in southern Vietnam, northern part of Myanmar, and the Visayas and Luzon Islands in the Philippines, while heavy precipitation decreases in northern Vietnam. Annual maximum number of consecutive dry days decreases in the region where winter monsoon precipitation dominates. Prolongation of the dry season is suggested in Myanmar.

  6. Correlation between total precipitable water and precipitation over East Asia

    Science.gov (United States)

    Keum, Wangho; Lim, Gyu-Ho

    2017-04-01

    The precipitation rate(PR) and the total precipitable water(TPW) interact with various physical mechanisms. The correlation of two variables changes with difference of domain resolution and characteristics of the region. This poster analyzes the correlation between PR and TPW over East Asia using Cyclostationary Empirical Orthogonal Function(CSEOF) which is one of the PCA analysis. The CSEOF is useful to search a periodic pattern of the data. The anomalies which is subtracted climatological mean from the original data are used to represent annual cycles. Two variances of ERA-Interim Monthly Total Column Water vapor and GPCP monthly precipitation amounts with 372 time since January, 1984 to December, 2014 are decomposed into several modes separately. The first mode which explain largest variance are used in analysis. PC of both PR and TPW increase recently on mean value and amplitude, and they show considerable correlation on phase. The correlation coefficient of PR and TPW is 0.61 and maintains the same values by month. The result of harmonic analysis shows 2 to 6 year oscillations. As result of decomposed modes of two variables, there is the relationship between TPW PC series and horizontal moisture gradient. The Horizontal moist gradient can change affect moisture flux convergence which is one of important variable of rainfall events.

  7. Niobium carbide precipitation in microalloyed steel

    Energy Technology Data Exchange (ETDEWEB)

    Klinkenberg, C.; Hulka, K. [Niobium Products Co. GmbH, Duesseldorf (Germany); Bleck, W. [Inst. for Ferrous Metallurgy, RWTH Aachen Univ., Aachen (Germany)

    2004-11-01

    The precipitation of niobium carbo-nitrides in the austenite phase, interphase and ferrite phase of microalloyed steel was assessed by a critical literature review and a round table discussion. This work analyses the contribution of niobium carbide precipitates formed in ferrite in the precipitation hardening of commercially hot rolled strip. Thermodynamics and kinetics of niobium carbo-nitride precipitation as well as the effect of deformation and temperature on the precipitation kinetics are discussed in various examples to determine the amount of niobium in solid solution that will be available for precipitation hardening after thermomechanical rolling in the austenite phase and successive phase transformation. (orig.)

  8. Pyrite oxidation by thermophilic archaebacteria

    Energy Technology Data Exchange (ETDEWEB)

    Larsson, L.; Olsson, G.; Holst, O.; Karlsson, H.T. (Lund Univ. (Sweden))

    1990-03-01

    Three species of thermophilic archaebacteria of the genera Sulfolobus (Sulfolobus acidocaldarius and S. solfataricus) and Acidianus (Acidianus brierleyi) were tested for their ability to oxidize pyrite and to grow autotropbically on pyrite, to explore their potential for use in coal desulfurization. Only A. brierleyi was able to oxidize and grow autotrophically on pyrite. Jarosite was formed during the pyrite oxidation, resulting in the precipitation of sulfate and iron. The medium composition affected the extent of jarosite formation.

  9. Acid precipitation; an annotated bibliography

    Science.gov (United States)

    Wiltshire, Denise A.; Evans, Margaret L.

    1984-01-01

    This collection of 1660 bibliographies references on the causes and environmental effects of acidic atmospheric deposition was compiled from computerized literature searches of earth-science and chemistry data bases. Categories of information are (1) atmospheric chemistry (gases and aerosols), (2) precipitation chemistry, (3) transport and deposition (wet and dry), (4) aquatic environments (biological and hydrological), (5) terrestrial environments, (6) effects on materials and structures, (7) air and precipitation monitoring and data collection, and (8) modeling studies. References date from the late 1800 's through December 1981. The bibliography includes short summaries of most documents. Omitted are unpublished manuscripts, publications in press, master 's theses and doctoral dissertations, newspaper articles, and book reviews. Coauthors and subject indexes are included. (USGS)

  10. Precipitation patterns during channel flow

    Science.gov (United States)

    Jamtveit, B.; Hawkins, C.; Benning, L. G.; Meier, D.; Hammer, O.; Angheluta, L.

    2013-12-01

    Mineral precipitation during channelized fluid flow is widespread in a wide variety of geological systems. It is also a common and costly phenomenon in many industrial processes that involve fluid flow in pipelines. It is often referred to as scale formation and encountered in a large number of industries, including paper production, chemical manufacturing, cement operations, food processing, as well as non-renewable (i.e. oil and gas) and renewable (i.e. geothermal) energy production. We have studied the incipient stages of growth of amorphous silica on steel plates emplaced into the central areas of the ca. 1 meter in diameter sized pipelines used at the hydrothermal power plant at Hellisheidi, Iceland (with a capacity of ca 300 MW electricity and 100 MW hot water). Silica precipitation takes place over a period of ca. 2 months at approximately 120°C and a flow rate around 1 m/s. The growth produces asymmetric ca. 1mm high dendritic structures ';leaning' towards the incoming fluid flow. A novel phase-field model combined with the lattice Boltzmann method is introduced to study how the growth morphologies vary under different hydrodynamic conditions, including non-laminar systems with turbulent mixing. The model accurately predicts the observed morphologies and is directly relevant for understanding the more general problem of precipitation influenced by turbulent mixing during flow in channels with rough walls and even for porous flow. Reference: Hawkins, C., Angheluta, L., Hammer, Ø., and Jamtveit, B., Precipitation dendrites in channel flow. Europhysics Letters, 102, 54001

  11. Global Precipitation Mission Visualization Tool

    Science.gov (United States)

    Schwaller, Mathew

    2011-01-01

    The Global Precipitation Mission (GPM) software provides graphic visualization tools that enable easy comparison of ground- and space-based radar observations. It was initially designed to compare ground radar reflectivity from operational, ground-based, S- and C-band meteorological radars with comparable measurements from the Tropical Rainfall Measuring Mission (TRMM) satellite's precipitation radar instrument. This design is also applicable to other groundbased and space-based radars, and allows both ground- and space-based radar data to be compared for validation purposes. The tool creates an operational system that routinely performs several steps. It ingests satellite radar data (precipitation radar data from TRMM) and groundbased meteorological radar data from a number of sources. Principally, the ground radar data comes from national networks of weather radars (see figure). The data ingested by the visualization tool must conform to the data formats used in GPM Validation Network Geometry-matched data product generation. The software also performs match-ups of the radar volume data for the ground- and space-based data, as well as statistical and graphical analysis (including two-dimensional graphical displays) on the match-up data. The visualization tool software is written in IDL, and can be operated either in the IDL development environment or as a stand-alone executable function.

  12. European climate change experiments on precipitation change

    DEFF Research Database (Denmark)

    Beier, Claus

    Presentation of European activities and networks related to experiments and databases within precipitation change......Presentation of European activities and networks related to experiments and databases within precipitation change...

  13. Seasonal precipitation forecast skill over Iran

    CSIR Research Space (South Africa)

    Shirvani, A

    2015-07-01

    Full Text Available of the Global Precipitation Climatology Centre (GPCC) Version 6 gridded precipitation data, using model output statistics (MOS) developed through the canonical correlation analysis (CCA) option of the Climate Predictability Tool (CPT). Retroactive validations...

  14. River Forecasting Center Quantitative Precipitation Estimate Archive

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — Radar indicated-rain gage verified and corrected hourly precipitation estimate on a corrected ~4km HRAP grid. This archive contains hourly estimates of precipitation...

  15. U.S. 15 Minute Precipitation Data

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — U.S. 15 Minute Precipitation Data is digital data set DSI-3260, archived at the National Climatic Data Center (NCDC). This is precipitation data. The primary source...

  16. Nickel hydroxide precipitation from aqueous sulfate media

    Science.gov (United States)

    Sist, Cinziana; Demopoulos, George P.

    2003-08-01

    Hydrometallurgical processing of laterite ores constitutes a major industrial and R&D activity in extractive metallurgy. In some of the process flowsheets, nickel hydroxide precipitation is incorporated. For these operations, the optimization of nickel hydroxide precipitation is important to assure efficiency and product quality. The main objective of this investigation was to study and improve the precipitation characteristics of Ni(OH)2 in a sulfate system using supersaturation controlled precipitation.

  17. Global Precipitation Measurement (GPM) Mission: NASA Precipitation Processing System (PPS)

    Science.gov (United States)

    Stocker, Erich Franz

    2008-01-01

    NASA is contributing the precipitation measurement data system PPS to support the GPM mission. PPS will distribute all GPM data products including NASA s GMI data products freely and quickly. PPS is implementing no system mechanisms for restricting access to GPM data. PPS is implementing no system mechanisms for charging for GPM data products. PPS will provide a number of geographical and parameter subsetting features available to its users. The first implementation of PPS (called PPS--) will assume processing of TRMM data effective 1 June 2008. TRMM realtime data will be available via PPS- to all users requesting access

  18. Calcium phosphate bioceramics prepared from wet chemically precipitated powders

    Directory of Open Access Journals (Sweden)

    Kristine Salma

    2010-03-01

    Full Text Available In this work calcium phosphates were synthesized by modified wet chemical precipitation route. Contrary to the conventional chemical precipitation route calcium hydroxide was homogenized with planetary mill. Milling calcium oxide and water in planetary ball mill as a first step of synthesis provides a highly dispersed calcium hydroxide suspension. The aim of this work was to study the influence of main processing parameters of wet chemical precipitation synthesis product and to control the morphology, phase and functional group composition and, consequently, thermal stability and microstructure of calcium phosphate bioceramics after thermal treatment. The results showed that it is possible to obtain calcium phosphates with different and reproducible phase compositions after thermal processing (hydroxyapatite [HAp], β-tricalcium phosphate [β-TCP] and HAp/β-TCP by modified wet-chemical precipitation route. The β-TCP phase content in sintered bioceramics samples is found to be highly dependent on the changes in technological parameters and it can be controlled with ending pH, synthesis temperature and thermal treatment. Pure, crystalline and highly thermally stable (up to 1300°C HAp bioceramics with homogenous grainy microstructure, grain size up to 200–250 nm and high open porosity can be successfully obtained by powder synthesized at elevated synthesis temperature of 70°C and stabilizing ending pH at 9.

  19. Microbially-Mediated Precipitation of Calcium Carbonate Nanoparticles.

    Science.gov (United States)

    Kang, Ser Ku; Roh, Yul

    2016-02-01

    The objective of this study was to investigate the biomineralization of carbonate minerals using microorganisms (Wu Do-1) enriched from rhodoliths. A 16S rRNA sequence analysis showed that Wu Do-1 mainly contained Proteus mirabilis. The pH decreased from 6.5 to 5.3 over the first 4 days of incubation due to microbial oxidation of organic acids, after which it increased to 7.8 over the remaining incubation period. XRD analysis showed that the precipitates were Mg-rich cal- cite (MgxCa(1-x)CO3), whereas no precipitates were formed without the addition of Wu Do-1 in D-1 medium. SEM-EDS analyses showed that the Mg-rich calcite had a rhombohedron shape and consisted of Ca, Si and Mg with an extracelluar polymeric substance (EPS). In addition, TEM-EDS analyses revealed they were hexagon in shape, 500-700 nm in size, and composed of Ca, Mg, C, and O. These results indicated that Wu Do-1 induced precipitation of Mg-rich calcite on the cell walls and EPS via the accumulation of Ca and/or Mg ions. Therefore, microbial precipitation of carbonate nanoparticles may play an important role in metal and carbon biogeochemistry, as well as in carbon sequestration in natural environments.

  20. Skill assessment of precipitation nowcasting in Mediterranean Heavy Precipitation Events

    Science.gov (United States)

    Bech, Joan; Berenguer, Marc

    2013-04-01

    Very short-term precipitation forecasting (i.e nowcasting) systems may provide valuable support in the weather surveillance process as they allow to issue automated early warnings for heavy precipitation events (HPE) as reviewed recently by Pierce et al. (2012). The need for warnings is essential in densely populated regions of small catchments, such as those typically found in Mediterranean coastal areas, prone to flash-floods. Several HPEs that occurred in NE Spain are analyzed using a nowcasting system based on the extrapolation of rainfall fields observed with weather radar following a Lagrangian approach developed and tested successfully in previous studies (Berenguer et al. 2005, 2011). Radar-based nowcasts, with lead times up to 3 h, are verified here against quality-controlled weather radar quantitative precipitation estimates and also against a dense network of raingauges. The basic questions studied are the dependence of forecast quality with lead time and rainfall amounts in several high-impact HPEs such as the 7 September 2005 Llobregat Delta river tornado outbreak (Bech et al. 2007) or the 2 November 2008 supercell tornadic thunderstorms (Bech et al. 2011) - both cases had intense rainfall rates (30' amounts exceeding 38.2 and 12.3 mm respectively) and daily values above 100 mm. Verification scores indicated that forecasts of 30' precipitation amounts provided useful guidance for lead times up to 60' for moderate intensities (up to 1 mm in 30') and up to 2.5h for lower rates (above 0.1 mm). On the other hand correlations of radar estimates and forecasts exceeded Eulerian persistence of precipitation estimates for lead times of 1.5 h for moderate intensities (up to 0.8 mm/h). We complete the analysis with a discussion on the reliability of threshold to lead time dependence based on the event-to-event variability found. This work has been done in the framework of the ProFEWS project (CGL2010-15892). References Bech J, N Pineda, T Rigo, M Aran, J Amaro, M

  1. Limnological aspects of acid precipitation

    Energy Technology Data Exchange (ETDEWEB)

    Hendrey, G.R. (ed.)

    1978-01-01

    Lakes and streams in parts of Norway, Sweden, Canada, and the United States are being severely impacted by acidic precipitation. Scientists meeting at Sagamore, New York, agreed that this is the most serious limnological problem today. The factor responsible for determining the sensitivity of surface waters to acidification is alkalinity derived by weathering of soils and bedrock in the watershed. Acidification, defined as a reduction in alkalinity, can be quantified if preacidification alkalinity data exist, but often they do not. Data on pH and Ca from surface waters in areas not affected by acid precipitation were compared to similar data from areas which receive precipitation with a weighted average hydrogen ion concentration of pH < 4.6. A semiquantitative estimation of surface water acidification can be made for lakes and streams, where earlier chemistry data are lacking, based on this analysis of pH and Ca data. Biological responses to acidification range from a reduction in numbers of species of algae and zooplankton to complete elimination of all fish life. Major biological processes such as primary production and decomposition may be altered leading to an accumulation of plant material and organic debris within lakes and streams. Increased concentrations of aluminum from the ..mu..g/l to mg/l range have been found at levels shown to be toxic to fish. These elevated levels apparently result from the exchange of H/sup +/ and Al in the watershed. There also appears to be a relationship between lake acidification and the accumulation of mercury in fish. Problems of aluminum analysis received detailed attention, and watershed mass balances, comparative watershed studies, whole lake manipulations, synoptic surveys, and the liming of acidified waters were discussed. A priority-rated list of recommendations for research was presented.

  2. Struvite Precipitation and Biological Dissolutions.

    OpenAIRE

    Ezquerro, Ander

    2010-01-01

    Struvite is a salt that is formed out of  Mg2+,NH4+ and PO43- and it crystallizes in form of MgNH4PO4.6H2O. Struvite‟s (magnesium ammonium phosphate or MAP) precipitation has recently been regarded as an interesting technique to remove phosphate and ammonium from waste water. The high elimination rates and the possibility of recycling the struvite as a direct slow release fertilizer make this process feasible and appealing. However, the costs due to the raw chemicals needed are drawbacks that...

  3. The Contribution of Extreme Precipitation to the Total Precipitation in China

    Institute of Scientific and Technical Information of China (English)

    SUN Jian-Qi

    2012-01-01

    Using daily precipitation data from weather stations in China, the variations in the contribution of extreme precipitation to the total precipitation are analyzed. It is found that extreme precipitation accounts for approximately one third of the total precipitation based on the overall mean for China. Over the past half century, extreme precipitation has played a dominant role in the year-to-year variability of the total precipitation. On the decadal time scale, the extreme precipitation makes different contributions to the wetting and drying regions of China. The wetting trends of particular regions are mainly attributed to increases in extreme precipitation; in contrast, the drying trends of other regions are mainly due to decreases in non-extreme precipitation.

  4. Heavy precipitation episodes and cosmic rays variation

    Directory of Open Access Journals (Sweden)

    A. Mavrakis

    2006-01-01

    Full Text Available In this paper an attempt is made to investigate the possible temporal correlation between heavy precipitation episodes and cosmic rays' activity, on various time scales. Cosmic rays measurements are sparse and cover less extended periods than those of precipitation. Precipitation is largely influenced by local climatic and even physiographic conditions, while cosmic rays' distribution is far more uniform over an area. Thus, in an effort to cover a larger range of climatic characteristics, each cosmic rays station was correlated with several nearby precipitation stations. Selected statistical methods were employed for the data processing. The analysis was preformed on annual, seasonal, monthly and daily basis whenever possible. Wet and dry regions and/or seasons seem to present a different response of precipitation to cosmic rays variations. Also Forbush decreases in most cases will not lead to heavy precipitation, yet this might be sensitive to precipitable water availability.

  5. Estimating Tropical Cyclone Precipitation from Station Observations

    Institute of Scientific and Technical Information of China (English)

    REN Fumin; WANG Yongmei; WANG Xiaoling; LI Weijing

    2007-01-01

    In this paper, an objective technique for estimating the tropical cyclone (TC) precipitation from station observations is proposed. Based on a comparison between the Original Objective Method (OOM) and the Expert Subjective Method (ESM), the Objective Synoptic Analysis Technique (OSAT) for partitioning TC precipitation was developed by analyzing the western North Pacific (WNP) TC historical track and the daily precipitation datasets. Being an objective way of the ESM, OSAT overcomes the main problems in OOM,by changing two fixed parameters in OOM, the thresholds for the distance of the absolute TC precipitation (D0) and the TC size (D1), into variable parameters.Case verification for OSAT was also carried out by applying CMORPH (Climate Prediction Center MORPHing technique) daily precipitation measurements, which is NOAA's combined satellite precipitation measurement system. This indicates that OSAT is capable of distinguishing simultaneous TC precipitation rain-belts from those associated with different TCs or with middle-latitude weather systems.

  6. Membrane-based wet electrostatic precipitation.

    Science.gov (United States)

    Bayless, David J; Shi, Liming; Kremer, Gregory; Stuart, Ben J; Reynolds, James; Caine, John

    2005-06-01

    Emissions of fine particulate matter, PM2.5, in both primary and secondary form, are difficult to capture in typical dry electrostatic precipitators (ESPs). Wet (or water-based) ESPs are well suited for collection of acid aerosols and fine particulates because of greater corona power and virtually no re-entrainment. However, field disruptions because of spraying (misting) of water, formation of dry spots (channeling), and collector surface corrosion limit the applicability of current wet ESPs in the control of secondary PM2.5. Researchers at Ohio University have patented novel membrane collection surfaces to address these problems. Water-based cleaning in membrane collectors made of corrosion-resistant fibers is facilitated by capillary action between the fibers, maintaining an even distribution of water. This paper presents collection efficiency results of lab-scale and pilot-scale testing at FirstEnergy's Bruce Mansfield Plant for the membrane-based wet ESP. The data indicate that a membrane wet ESP was more effective at collecting fine particulates, acid aerosols, and oxidized mercury than the metal-plate wet ESP, even with approximately 15% less collecting area.

  7. Precipitation chemistry in central Amazonia

    Science.gov (United States)

    Andreae, M. O.; Talbot, R. W.; Berresheim, H.; Beecher, K. M.

    1990-01-01

    Rain samples from three sites in central Amazonia were collected over a period of 6 weeks during the 1987 wet season and analyzed for ionic species and dissolved organic carbon. A continuous record of precipitation chemistry and amount was obtained at two of these sites, which were free from local or regional pollution, for a time period of over 1 month. The volume-weighted mean concentrations of most species were found to be about a factor of 5 lower during the wet season compared with previous results from the dry season. Only sodium, potassium, and chloride showed similar concentrations in both seasons. When the seasonal difference in rainfall amount is taken into consideration, the deposition fluxes are only slightly lower for most species during the wet season than during the dry season, again with the exception of chloride, potassium, and sodium. Sodium and chloride are present in the same ratio as in sea salt; rapid advection of air masses of marine origin to the central Amazon Basin during the wet season may be responsible for the observed higher deposition flux of these species. Statistical analysis suggests that sulfate is, to a large extent, of marine (sea salt and biogenic) origin, but that long-range transport of combustion-derived aerosols also makes a significant contribution to sulfate and nitrate levels in Amazonian rain. Organic acid concentrations in rain were responsible for a large fraction of the observed precipitation acidity; their concentration was strongly influenced by gas/liquid interactions.

  8. Characterization of iron and manganese precipitates from an in situ ground water treatment plant.

    Science.gov (United States)

    Mettler, S; Abdelmoula, M; Hoehn, E; Schoenenberger, R; Weidler, P; von Gunten, U

    2001-01-01

    Aquifer samples from the precipitation zone of an in situ iron and manganese removal plant that was operated for 10 years were analyzed for iron and manganese minerals. Measurements were performed by various chemical extraction techniques (5 M HCI, 0.008 M Ti(III)-EDTA, 0.114 M ascorbic acid), X-ray diffraction and Mössbauer spectroscopy. Chemical extractions showed that iron was precipitated as ferric oxides, whereas manganese was not oxidized but deposited as Mn(II) probably within carbonates. The ferric oxides in particular accumulate preferentially in the smaller grain- size fractions. This tendency was observed to a lesser extent for manganese. X-ray diffraction and Mössbauer spectroscopy showed that the ferric oxides were mainly crystalline (goethite, 50% to 100% of the iron). Ferrihydrite was found as well, but only as a minor fraction (< or = 12%). Pure manganese minerals were not found by X-ray diffraction. The precipitated amounts of iron (5 to 27 micromol/g Fe as ferric oxide) and manganese (1 to 4 micromol/g Mn) during 10 years operation of the treatment plant agree with values that were estimated from operational parameters (9 to 31 micromol/g Fe and 3 to 6 micromol/g Mn). Considering the small amounts of precipitated iron and manganese, no long-term risks of clogging of the aquifer are expected.

  9. Effects of sputtering power on properties of copper oxides thin films deposited on glass substrates

    Energy Technology Data Exchange (ETDEWEB)

    Ooi, P. K.; Ng, S. S.; Abdullah, M. J. [Nano-Optoelectronics Research and Technology Laboratory, School of Physics, Universiti Sains Malaysia, 11800 Penang (Malaysia)

    2015-04-24

    Copper oxides are deposited by radio frequency sputtering using copper target in the mixture of argon and oxygen gasses. The structural and optical properties of the copper oxides deposited at different sputtering powers have been investigated. All the films are single phase polycrystalline. At low RF power (100 W), the film is monoclinic structure of cupric oxide (CuO). Meanwhile, the films are cubic structure of cuprous oxide (Cu2O) at higher RF power. Field emission scanning electron microscopy images show the films have different morphologies with small grain size and consist of a lot of voids. The analysis of energy dispersive X-ray spectroscopy shows that the ratio of Cu to O is increased as the RF power increased. From the ultraviolet–visible spectroscopy, the films have a broad absorption edge in the range of 300–500 nm. The band gap of the films grown at RF power of 100 W, and 120 W and above, were 1.18 eV and 2.16 eV, respectively.

  10. Factors Affection Cr(Ⅲ) Oxidation by Manganese Oxides

    Institute of Scientific and Technical Information of China (English)

    CHENYINGXU; CHENYIYI; 等

    1997-01-01

    The high oxidation ability of manganese oxides or soils was used to study effects of PH and coating on Cr(Ⅲ) oxidation,The results indicated that Cr(Ⅲ) oxidation peaked in PH 4.0-6.5,The amount and rate of Cr(Ⅲ) being oxidized by uncoated δ-MnO2 were larger than those by Fe oxide- of CaCo3-coated one.Inorganic Cr(Ⅲ) wa more easily oxidzed by MnO2 than organic complex Cr(Ⅲ) due to different surface affinities. Precipitated Cr(Ⅲ) and adsorbed Cr(Ⅲ) might be transferred onto MnO2 surface and then oxidized to Cr(Ⅵ)

  11. Bias Adjusted Precipitation Threat Scores

    Directory of Open Access Journals (Sweden)

    F. Mesinger

    2008-04-01

    Full Text Available Among the wide variety of performance measures available for the assessment of skill of deterministic precipitation forecasts, the equitable threat score (ETS might well be the one used most frequently. It is typically used in conjunction with the bias score. However, apart from its mathematical definition the meaning of the ETS is not clear. It has been pointed out (Mason, 1989; Hamill, 1999 that forecasts with a larger bias tend to have a higher ETS. Even so, the present author has not seen this having been accounted for in any of numerous papers that in recent years have used the ETS along with bias "as a measure of forecast accuracy".

    A method to adjust the threat score (TS or the ETS so as to arrive at their values that correspond to unit bias in order to show the model's or forecaster's accuracy in extit{placing} precipitation has been proposed earlier by the present author (Mesinger and Brill, the so-called dH/dF method. A serious deficiency however has since been noted with the dH/dF method in that the hypothetical function that it arrives at to interpolate or extrapolate the observed value of hits to unit bias can have values of hits greater than forecast when the forecast area tends to zero. Another method is proposed here based on the assumption that the increase in hits per unit increase in false alarms is proportional to the yet unhit area. This new method removes the deficiency of the dH/dF method. Examples of its performance for 12 months of forecasts by three NCEP operational models are given.

  12. Cerium and neodymium co-precipitation in molten chloride by wet argon sparging

    Energy Technology Data Exchange (ETDEWEB)

    Vigier, J.F. [CEA, Nuclear Energy Division, RadioChemistry and Processes Department, SMCS/LEPS, F-30207 Bagnols sur Ceze (France); Unite de Catalyse et de Chimie du Solide, UCCS UMR CNRS 8181, Univ. Lille Nord de France, ENSCL-USTL, B.P. 90108, 59652 Villeneuve d' Ascq Cedex (France); Renard, C., E-mail: catherine.renard@ensc-lille.fr [Unite de Catalyse et de Chimie du Solide, UCCS UMR CNRS 8181, Univ. Lille Nord de France, ENSCL-USTL, B.P. 90108, 59652 Villeneuve d' Ascq Cedex (France); Laplace, A. [CEA, Nuclear Energy Division, RadioChemistry and Processes Department, SMCS/LEPS, F-30207 Bagnols sur Ceze (France); Lacquement, J. [CEA, Nuclear Energy Division, DTEC/DIR, F-30207 Bagnols sur Ceze (France); Abraham, F. [Unite de Catalyse et de Chimie du Solide, UCCS UMR CNRS 8181, Univ. Lille Nord de France, ENSCL-USTL, B.P. 90108, 59652 Villeneuve d' Ascq Cedex (France)

    2013-01-15

    Co-precipitations of cerium (III) and neodymium (III) at 10 wt.% in LiCl-CaCl{sub 2} (30-70 mol%) molten salt at 705 Degree-Sign C have been achieved using an original way of precipitation, wet argon sparging. Several CeCl{sub 3}/NdCl{sub 3} ratios have been studied, and the isolated powders were analyzed using different characterization methods including XRD investigations. The lanthanides precipitation yields have been determined around 99.9% using ICP-AES analysis. XRD demonstrated that the precipitates mainly contained mixed oxychloride (Ce{sub 1-x}Nd{sub x})OCl and a small amount of the mixed oxide Ce{sub 1-y}Nd{sub y}O{sub 2-0.5y}. Calcination of these precipitates has resulted in the cerium and neodymium mixed oxides. For the precipitation with a Ce/Nd = 50/50 ratio, an hydroxychloride Ln(OH){sub 2}Cl and the oxychloride Ce{sup IV}(Nd{sub 0.7}Ce{sub 0.3}){sup III}O{sub 3}Cl have been identified as unexpected intermediate compounds.

  13. Improved Electronic Control for Electrostatic Precipitators

    Science.gov (United States)

    Johnston, D. F.

    1986-01-01

    Electrostatic precipitators remove particulate matter from smoke created by burning refuse. Smoke exposed to electrostatic field, and particles become electrically charged and migrate to electrically charged collecting surfaces. New microprocessor-based electronic control maintains precipitator power at maximum particulate-collection level. Control automatically senses changes in smoke composition due to variations in fuel or combustion and adjusts precipitator voltage and current accordingly. Also, sensitive yet stable fault detection provided.

  14. The photosensitive effect of Ce on the precipitation of Ag nanoparticles induced by femtosecond laser in silicate glass

    Institute of Scientific and Technical Information of China (English)

    Dai Ye; Qiu Jian-Rong

    2009-01-01

    This paper studies the photosensitive effect of cerium oxide on the precipitation of Ag nanoparticles after femtosecond laser irradiating into silicate glass and successive annealing. Spectroscopy analysis and diffraction efficiency measurements show that the introduction of cerium oxide may increase the concentration of Ag atoms in the femtosecond laser-irradiated regions resulting from the photoreduction reaction Ce3+ + Ag+→ Ce4+ + Ag0 via multiphoton excitation. These results promote the aggregation of Ag nanoparticles during the annealing process. It is also found that different concentrations of cerium oxide may influence the Ag nanoparticle precipitation in the corresponding glass.

  15. Shifting covariability of North American summer monsoon precipitation with antecedent winter precipitation

    Science.gov (United States)

    McCabe, G.J.; Clark, M.P.

    2006-01-01

    Previous research has suggested that a general inverse relation exists between winter precipitation in the southwestern United states (US) and summer monsoon precipitation. In addition, it has been suggested that this inverse relation between winter precipitation and the magnitude of the southwestern US monsoon breaks down under certain climatic conditions that override the regional winter/monsoon precipitation relations. Results from this new study indicate that the winter/monsoon precipitation relations do not break down, but rather shift location through time. The strength of winter/monsoon precipitation relations, as indexed by 20-year moving correlations between winter precipitation and monsoon precipitation, decreased in Arizona after about 1970, but increased in New Mexico. The changes in these correlations appear to be related to an eastward shift in the location of monsoon precipitation in the southwestern US. This eastward shift in monsoon precipitation and the changes in correlations with winter precipitation also appear to be related to an eastward shift in July/August atmospheric circulation over the southwestern US that resulted in increased monsoon precipitation in New Mexico. Results also indicate that decreases in sea-surface temperatures (SSTs) in the central North Pacific Ocean also may be associated with th changes in correlations between winter and monsoon precipitation. Copyright ?? 2006 Royal Meteorological Society.

  16. MOLECULAR DYNAMICS SIMULATION OF INTERACTION BETWEEN CUPROUS OXIDE CRYSTAL AND BENZOTRIAZOLE DERIVATIVES%苯并三氮唑及其衍生物与氧化亚铜晶体相互作用的MD模拟

    Institute of Scientific and Technical Information of China (English)

    张曙光; 陈瑜; 王风云

    2007-01-01

    用分子动力学(MD)方法,模拟计算了4种铜缓蚀剂[苯并三氮唑(BTA)、5-羧甲基苯并三氮唑(CBTAH-ME)、5-羧丁基苯并三氮唑(CBTAH-BU)、5-羧辛基苯并三氮唑(CBTAH-OC)]与Cu2O晶体的相互作用.结果表明,缓蚀剂分子与Cu2O晶体的结合能排序为CBTAH-OC>CBTAH-BU>CBTAH-ME>BTA.对体系各种相互作用以及对关联函数g(r)的分析表明,体系结合能主要来自库仑作用.在与Cu2O(001)晶面结合过程中,BTA及其衍生物分子发生了扭曲变形,且分子中的N原子与Cu2O晶体中的Cu原子之间形成了配位键.

  17. Circulation factors affecting precipitation over Bulgaria

    Science.gov (United States)

    Nojarov, Peter

    2017-01-01

    The objective of this paper is to determine the influence of circulation factors on precipitation in Bulgaria. The study succeeds investigation on the influence of circulation factors on air temperatures in Bulgaria, as the focus here is directed toward precipitation amounts. Circulation factors are represented through two circulation indices, showing west-east or south-north transport of air masses over Bulgaria and four teleconnection indices (patterns)—North Atlantic Oscillation, East Atlantic, East Atlantic/Western Russia, and Scandinavian. Omega values at 700-hPa level show vertical motions in the atmosphere. Annual precipitation trends are mixed and not statistically significant. A significant decrease of precipitation in Bulgaria is observed in November due to the strengthening of the eastward transport of air masses (strengthening of EA teleconnection pattern) and anticyclonal weather (increase of descending motions in the atmosphere). There is also a precipitation decrease in May and June due to the growing influence of the Azores High. An increase of precipitation happens in September. All this leads to a redistribution of annual precipitation course, but annual precipitation amounts remain the same. However, this redistribution has a negative impact on agriculture and winter ski tourism. Zonal circulation has a larger influence on precipitation in Bulgaria compared to meridional. Eastward transport throughout the year leads to lower than the normal precipitation, and vice versa. With regard to the four teleconnection patterns, winter precipitation in Bulgaria is determined mainly by EA/WR teleconnection pattern, spring and autumn by EA teleconnection pattern, and summer by SCAND teleconnection pattern.

  18. Precipitation Ground Validation over the Oceans

    Science.gov (United States)

    Klepp, C.; Bakan, S.

    2012-04-01

    State-of-the-art satellite derived and reanalysis based precipitation climatologies show remarkably large differences in detection, amount, variability and temporal behavior of precipitation over the oceans. The uncertainties are largest for light precipitation within the ITCZ and for cold season high-latitude precipitation including snowfall. Our HOAPS (Hamburg Ocean Atmosphere Parameters and Fluxes from Satellite data, www.hoaps.org) precipitation retrieval exhibits fairly high accuracy in such regions compared to our ground validation data. However, the statistical basis for a conclusive validation has to be significantly improved with comprehensive ground validation efforts. However, existing in-situ instruments are not designed for precipitation measurements under high wind speeds on moving ships. To largely improve the ground validation data basis of precipitation over the oceans, especially for snow, the systematic data collection effort of the Initiative Pro Klima funded project at the KlimaCampus Hamburg uses automated shipboard optical disdrometers, called ODM470 that are capable of measuring liquid and solid precipitation on moving ships with high accuracy. The main goal of this project is to constrain the precipitation retrievals for HOAPS and the new Global Precipitation Measurement (GPM) satellite constellation. Currently, three instruments are long-term mounted on the German research icebreaker R/V Polarstern (Alfred Wegner Institut) since June 2010, on R/V Akademik Ioffe (P.P.Shirshov Institute of Oceanology, RAS, Moscow, Russia) since September 2010 and on R/V Maria S. Merian (Brise Research, University of Hamburg) since December 2011. Three more instruments will follow shortly on further ships. The core regions for these long-term precipitation measurements comprise the Arctic Ocean, the Nordic Seas, the Labrador Sea, the subtropical Atlantic trade wind regions, the Caribbean, the ITCZ, and the Southern Oceans as far south to Antarctica. This

  19. Mean Annual Precipitation in West-Central Nevada using the Precipitation-Zone Method

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This data set contains 1971-2000 mean annual precipitation estimates for west-central Nevada. This is a raster data set developed using the precipitation-zone...

  20. Sorption of trace metals on calcite: Applicability of the surface precipitation model

    NARCIS (Netherlands)

    Comans, R.N.J.; Middelburg, J.J.

    1987-01-01

    Published Sorption isotherm data of Cd2+, Mn2+, Zn2+, and Co2+ on calcite are adequately described by the surface precipitation model which was originally developed by FArley et al. (1985) for the sorption of cations on metal oxides. In addition to monolayer adsorption, the model accounts for the fo

  1. In-Drift Precipitates/Salts Model

    Energy Technology Data Exchange (ETDEWEB)

    P. Mariner

    2003-10-21

    As directed by ''Technical Work Plan For: Engineered Barrier System Department Modeling and Testing FY03 Work Activities'' (BSC 2003 [165601]), the In-Drift Precipitates/Salts (IDPS) model is developed and refined to predict the aqueous geochemical effects of evaporation in the proposed repository. The purpose of this work is to provide a model for describing and predicting the postclosure effects of evaporation and deliquescence on the chemical composition of water within the proposed Engineered Barrier System (EBS). Application of this model is to be documented elsewhere for the Total System Performance Assessment License Application (TSPA-LA). The principal application of this model is to be documented in REV 02 of ''Engineered Barrier System: Physical and Chemical Environment Model'' (BSC 2003 [165601]). The scope of this document is to develop, describe, and validate the IDPS model. This model is a quasi-equilibrium model. All reactions proceed to equilibrium except for several suppressed minerals in the thermodynamic database not expected to form under the proposed repository conditions within the modeling timeframe. In this revision, upgrades to the EQ3/6 code (Version 8.0) and Pitzer thermodynamic database improve the applicable range of the model. These new additions allow equilibrium and reaction-path modeling of evaporation to highly concentrated brines for potential water compositions of the system Na-K-H-Mg-Ca-Al-Cl-F-NO{sub 3}-SO{sub 4}-Br-CO{sub 3}-SiO{sub 2}-CO{sub 2}-O{sub 2}-H{sub 2}O at temperatures in the range of 0 C to 125 C, pressures in the atmospheric range, and relative humidity in the range of 0 to 100 percent. This system applies to oxidizing conditions only, and therefore limits the model to applications involving oxidizing conditions. A number of thermodynamic parameters in the Pitzer database have values that have not been determined or verified for the entire temperature range. In these cases

  2. Impacts of extreme precipitation and seasonal changes in precipitation on plants

    Directory of Open Access Journals (Sweden)

    M. J. B. Zeppel

    2013-10-01

    Full Text Available The hydrological cycle is predicted to become more intense in future climates, with both larger precipitation events and longer times between events. Redistribution of precipitation may occur both within and across seasons, and the resulting wide fluctuations in soil water content may dramatically affect plants. Though these responses remain poorly understood, recent research in this emerging field suggests the effects of redistributed precipitation may differ from predictions based on previous drought studies. We review available studies on both extreme precipitation (redistribution within seasons and seasonal changes in precipitation (redistribution across seasons on grasslands and forests. Extreme precipitation differentially affected Aboveground Net Primary Productivity (ANPP, depending on whether extreme precipitation led to increased or decreased soil water content (SWC, which differed based on the current precipitation at the site. Specifically, studies to date reported that extreme precipitation decreased ANPP in mesic sites, but, conversely, increased ANPP in xeric sites, suggesting that plant available water is a key factor driving responses to extreme precipitation. Similarly, the effects of seasonal changes in precipitation on ANPP, phenology, and leaf and fruit development varied with the effect on SWC. Reductions in spring or summer generally had negative effects on plants, associated with reduced SWC, while subsequent reductions in autumn or winter had little effect on SWC or plants. Similarly, increased summer precipitation had a more dramatic impact on plants than winter increases in precipitation. The patterns of response suggest xeric biomes may respond positively to extreme precipitation, while comparatively mesic biomes may be more likely to be negatively affected. And, seasonal changes in precipitation during warm or dry seasons may have larger effects than changes during cool or wet seasons. Accordingly, responses to

  3. Application of quantitative precipitation forecasting and precipitation ensemble prediction for hydrological forecasting

    OpenAIRE

    Tao, P.; Tie-Yuan, S.; Zhi-Yuan, Y.; Jun-Chao, W.

    2015-01-01

    The precipitation in the forecast period influences flood forecasting precision, due to the uncertainty of the input to the hydrological model. Taking the ZhangHe basin as the example, the research adopts the precipitation forecast and ensemble precipitation forecast product of the AREM model, uses the Xin Anjiang hydrological model, and tests the flood forecasts. The results show that the flood forecast result can be clearly improved when considering precipitation during the forecast period....

  4. Nucleation pathway in coherent precipitation

    Science.gov (United States)

    Philippe, T.; Blavette, D.

    2011-12-01

    The non-classical nucleation pathway of coherent precipitates has been computed through minimisation of the nucleation barrier in the composition (c)-size (R) space to predict the evolution of nucleus composition. The generalized Gibbs model, developed by Schmelzer et al. [J. Chem. Phys. 112 (2000) p.3820; J. Colloid Interface Sci. 272 (2004) p.109], has been extended to include misfit elastic energy. The composition of critical embryos c* was found to be independent of the interfacial constant. The composition of critical nuclei (c*) decreased with supersaturation. The elastic energy increased both c* and the nucleation barrier, as well as R*. The evolution of nucleus composition (c) as a function of size (R) along the minimum energy pathway was computed. Nucleation only starts when a size threshold is exceeded. Then, rapid enrichment to the expected composition (c β) precedes a constant composition regime. However, for small supersaturations, the change in cluster composition can occur sharply for a very small radius and then the composition slowly increased with a significant change in size. Coherency misfit energy was found to slow down the evolution of nuclei composition with R. The model was compared to experimental results.

  5. Oxidation behavior of Cu nanoparticles embedded into semiconductive TiO{sub 2} matrix

    Energy Technology Data Exchange (ETDEWEB)

    Stranak, Vitezslav, E-mail: stranak@prf.jcu.cz [University of South Bohemia, Faculty of Science, Branisovska 31, 37005 Ceske Budejovice (Czech Republic); Drache, Steffen; Wulff, Harm [University of Greifswald, Institute of Physics, Felix-Hausdorff-Str. 6, 17489 Greifswald (Germany); Hubicka, Zdenek [Institute of Physics, Academy of Science of the Czech Republic, Na Slovance 2, 18221 Prague (Czech Republic); Tichy, Milan [Charles University in Prague, Faculty of Mathematics and Physics, V Holesovickach 2, 18000 Prague (Czech Republic); Kruth, Angela [Leibniz Institute for Plasma Science and Technology, INP Greifswald e.V., Felix-Hausdorff-Straße 2, 17489 Greifswald (Germany); Helm, Christiane A.; Hippler, Rainer [University of Greifswald, Institute of Physics, Felix-Hausdorff-Str. 6, 17489 Greifswald (Germany)

    2015-08-31

    Metal nanoparticles embedded into a semiconductive matrix represent a promising material for widely sought advanced technological applications. We focused our interest on the preparation of TiO{sub 2} matrix with embedded Cu nanoparticles. In particular, we studied the effect of reactive discharge (Ar/O{sub 2}) exposition on copper oxidation, which can result in two stable forms: cuprous oxide (Cu{sub 2}O) and cupric oxide (CuO). Copper nanoparticles, of size in range 10–50 nm, were produced by magnetron sputtering in combination with gas aggregation. The beam of Cu nanoparticles was impinging onto a silicon substrate which was directly exposed to a reactive Ar/O{sub 2} magnetron discharge providing sputtering of Ti target at the same time. The properties of deposited nanocomposite Cu({sub x}O)–TiO{sub 2} were investigated by X-ray photoelectron spectroscopy, grazing incidence X-ray diffractometry, X-ray reflectometry and scanning electron microscopy techniques to reveal the nanocomposite properties and to understand the oxidation process of embedded Cu nanoparticles. It was found that CuO is preferentially formed if copper is exposed to active oxygen species (O{sup +}, O{sup −}, O{sup ⁎} etc.) produced in the reactive magnetron discharge. On the other hand, Cu{sub 2}O was observed in the case of copper reaction in ambient Ar/O{sub 2} atmosphere. As a result, two possible copper oxidation mechanisms are proposed, employing chemical kinetics. - Highlights: • Cu–TiO{sub 2} nanocomposite was prepared by plasma assisted methods. • Embedded Cu always occurs in oxidized phase depending on the way of oxidation. • CuO is formed if copper is exposed to active oxygen species produced in Ar/O{sub 2} discharge. • Cu{sub 2}O appears in the case of copper reaction in an ambient oxygen-based atmosphere. • Two possible copper oxidation mechanisms are proposed.

  6. Precipitation of humic acid with divalent ions

    DEFF Research Database (Denmark)

    Andersen, Niels Peder Raj; Mikkelsen, Lene Haugaard; Keiding, Kristian

    2001-01-01

    and Ba2+. The phase diagram model can not account for the observed precipitation in region III and However, in region IV the HA appears to posses colloidal properties, which is supported by precipitation taking place at a constant zeta-potential -21mV with the same amount of added barium ion regardless...

  7. Dissolution of ordered precipitates under ion irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Camus, E.; Bourdeau, F.; Abromeit, C.; Wanderka, N.; Wollenberger, H. [Hahn-Meitner-Institut Berlin GmbH (Germany)

    1995-09-01

    The stability of the ordered {gamma}{prime} precipitates under 300-keV Ni{sup +} irradiation was investigated between room temperature and 623 K. The two competing mechanisms of destabilization by cascade producing irradiation, i.e. disordering and dissolution of the {gamma}{prime} precipitates in Nimonic PE16 alloy, has been studied separately by electron microscopy and field-ion microscopy with atom probe. At high temperatures, the precipitates are stable. At intermediate temperatures, the precipitates dissolve by ballistic mixing into the matrix, but the interface is restored by the radiation-enhanced atomic jumps. The order in the precipitates remains stable. At low temperatures, the precipitates are dissolved by atomic mixing. The dissolution proceeds in a diffusional manner with a diffusion coefficient normalized by the displacement rate D/K = 0.75 nm{sup 2}dpa{sup {minus}1}. The precipitates become disordered by a fluence of 0.1 dpa, whereas precipitate dissolution needs much higher fluences.

  8. MAXIS Balloon Observations of Electron Microburst Precipitation

    Science.gov (United States)

    Millan, R. M.; Hunter, A. E.; McCarthy, M. P.; Lin, R. P.; Smith, D. M.

    2003-12-01

    Quantifying and understanding losses is an integral part of understanding relativistic electron variability in the radiation belts. SAMPEX observations indicate that electron microburst precipitation is a major loss mechanism during active periods; the loss of relativistic electrons during a six hour period due to microburst precipitation was recently estimated to be comparable to the total number of trapped electrons in the outer zone (Lorentzen et al., 2001). Microburst precipitation was first observed from a balloon (Anderson and Milton, 1964), but these early measurements were only sensitive to MAXIS 2000 long duration balloon campaign. MAXIS was launched from McMurdo Station in Antarctica carrying a germanium spectrometer, a BGO scintillator and two X-ray imagers designed to measure the bremsstrahlung produced by precipitating electrons. The balloon circumnavigated the south pole in 18 days covering magnetic latitudes ranging from 58o-90o South. During the week following a moderate geomagnetic storm (with Dst reaching -91 nT), MAXIS detected a total of over 16 hours of microburst precipitation. We present high resolution spectra obtained with the MAXIS germanium spectrometer which allow us to determine the precipitating electron energy distribution. The precipitating distribution will then be compared to the trapped distribution measured by the GPS and LANL satellites. We also examine the spatial distribution of the precipitation.

  9. Study of asphaltene precipitation by Calorimetry

    DEFF Research Database (Denmark)

    Verdier, Sylvain Charles Roland; Plantier, Frédéric; Bessières, David;

    2007-01-01

    of experiments showed that weak forces determine precipitation. Indeed, isothermal titration calorimetry could not detect any clear signal although this technique can detect low-energy transitions such as liquid-liquid equilibrium and rnicellization. The second series of tests proved that precipitation caused...

  10. Asphaltene precipitates in oil production wells

    DEFF Research Database (Denmark)

    Kleinitz, W,; Andersen, Simon Ivar

    1998-01-01

    At the beginning of production in a southern German oil field, flow blockage was observed during file initial stage of production from the oil wells. The hindrance was caused by the precipitation of asphaltenes in the proximity of the borehole and in the tubings. The precipitates were of solid...

  11. Investigation of Asphaltene Precipitation at Elevated Temperature

    DEFF Research Database (Denmark)

    Andersen, Simon Ivar; Lindeloff, Niels; Stenby, Erling Halfdan

    1998-01-01

    In order to obtain quantitative data on the asphaltene precipitation induced by the addition of n-alkane (heptane) at temperatures above the normal boiling point of the precipitant, a high temperature/high pressure filtration apparatus has been constructed. Oil and alkane are mixed at the appropr...

  12. Titanium-iridium oxide layer coating to suppress photocorrosion during photocatalytic water splitting

    Energy Technology Data Exchange (ETDEWEB)

    Kwon, Yongwoo; Lee, Hyunjoo [Korea Advanced Institute of Science and Technology, Daejeon (Korea, Republic of); Kwon, Yongwoo; Lee, Hyunjoo [Korea Advanced Institute of Science and Technology, Daejeon (Korea, Republic of)

    2015-12-15

    Photocatalysts with a small band gap energy have received a great deal of interest due their high solar conversion efficiencies. Cuprous oxide (Cu{sub 2}O) has attracted attention because of its small bandgap energy, a direct bandgap structure, its suitable band structure for water splitting, high absorption coefficient, non-toxicity, and its large abundance. However, it has poor stability due to the fickle oxidation states of copper. To enhance the stability and the production rate of hydrogen and oxygen, a TiIrOX overlayer was successfully formed on the Cu{sub 2}O under various synthesis conditions. The composition and oxidation state of the Ir species in the overlayer were optimized through the control of the Ir precursor and the amount of water. The Ir/Ti precursor molar ratio was linearly related to the surface Ir/Ti molar ratio. The addition of water converted the Ir precursor to IrO{sub 2}. The thickness of the overlayer was controlled by differing the synthesis times of the coating. Then, the largest amounts of hydrogen and oxygen were produced through the optimization of the TiIrOX overlayer with a higher IrO{sub 2} fraction and a thicker overlayer.

  13. C isotope fractionation during heterotrophic activity driven carbonate precipitation

    Science.gov (United States)

    Balci, Nurgul; Demirel, Cansu

    2016-04-01

    Stable carbon isotopic fractionation during carbonate precipitation induced by environmentally enriched heterotrophic halophilic microorganims was experimentally investigated under various salinity (% 4.5, %8, %15) conditions at 30 °C. Halophilic heterotrophic microorganims were enriched from a hypersaline Lake Acigöl located in SW Turkey (Balci et al.,2015) and later used for the precipitation experiments (solid and liquid medium). The carbonate precipitates had relatively high δ13C values (-4.3 to -16.9 ‰) compared to the δ13C values of the organic compounds that ranged from -27.5 to -25.4 ‰. At salinity of 4.5 % δ13C values of carbonate ranged from -4.9 ‰ to -10.9 ‰ with a 13C-enrichment factor of +20 to +16 ‰ higher than the δ13C values of the associated DOC (-27.5) . At salinity 8 % δ13C values of carbonate ranged from -16.3 ‰ to -11.7 ‰ with a 13C-enrichment factor of+11.3 to+15.9 ‰ higher than the δ13C values of the associated DOC. The respected values for 15 % salinity ranged from -12.3 ‰ to -9.7 ‰ with a 13C-enrichment factor of +15.2 to+16.8 ‰ higher than the δ13C values of the associated DOC. The carbonate precipitates produced in the solid medium are more enriched in 13C relative to liquid culture experiments. These results suggest that the carbon in the solid was derived from both the bacterial oxidation of organic compounds in the medium and from the atmospheric CO2. A solid medium used in the experiments may have suppressed convective and advective mass transport favouring diffusion-controlled system. This determination suggests that the rate and equilibration of CO2 exchange with the atmosphere is the major control on C isotope composition of carbonate minerals precipitated in the experiments. Key words: Lake Acıgöl, halophilic bacteria, carbonate biomineralization, C isotopes References Nurgul Balci, Meryem Menekşe, Nevin Gül Karagüler, M. Şeref Sönmez,Patrick Meister 2015.Reproducing authigenic carbonate

  14. Precipitation hardening in 350 grade maraging steel

    Energy Technology Data Exchange (ETDEWEB)

    Viswanathan, U.K. (Bhabha Atomic Research Centre, Bombay, (India). Radiometallurgy Div.); Dey, G.K. (Bhabha Atomic Research Centre, Bombay, (India). Metallurgy Division); Asundi, M.K. (Government Colony, Bombay, (India))

    1993-11-01

    Evolution of microstructure in 350 grade commercial maraging steel has been examined. In the earlier stages of aging, the strengthening phases are formed by the heterogeneous precipitation, and these phases have been identified as intermetallic compounds of the Ni[sub 3] (Ti, Mo) and Fe[sub 2]Mo types. The kinetics of precipitation are studied in terms of the activation energy by carrying out isothermal hardness measurements of aged material. The mechanical properties in the peak-aged and overaged conditions were evaluated and the flow behavior examined. The overaging behavior of the steel has been studied and the formation of austenite of different morphologies identified. The crystallography of the austenite has been examined in detail. From the microstructural examination of peak-aged and deformed samples, it could be inferred that the dislocation-precipitate interaction is by precipitate shearing. Increased work hardening of the material in the overaged condition was suggestive of looping of precipitates by dislocations.

  15. Precipitation hardening in 350 grade maraging steel

    Science.gov (United States)

    Viswanathan, U. K.; Dey, G. K.; Asundi, M. K.

    1993-11-01

    Evolution of microstructure in a 350 grade commercial maraging steel has been examined. In the earlier stages of aging, the strengthening phases are formed by the heterogeneous precipitation, and these phases have been identified as intermetallic compounds of the Ni3 (Ti, Mo) and Fe2Mo types. The kinetics of precipitation are studied in terms of the activation energy by carrying out isothermal hardness measurements of aged material. The mechanical properties in the peak-aged and overaged conditions were evaluated and the flow behavior examined. The overaging behavior of the steel has been studied and the formation of austenite of different morphologies identified. The crystallography of the austenite has been examined in detail. From the microstructural examination of peak-aged and deformed samples, it could be inferred that the dislocation-precipitate interaction is by precipitate shearing. Increased work hardening of the material in the overaged condition was suggestive of looping of precipitates by dislocations.

  16. Calcium isotopic fractionation in microbially mediated gypsum precipitates

    Science.gov (United States)

    Harouaka, Khadouja; Mansor, Muammar; Macalady, Jennifer L.; Fantle, Matthew S.

    2016-07-01

    Gypsum (CaSO4·2H2O) precipitation experiments were carried out at low pH in the presence of the sulfur oxidizing bacterium Acidithiobacillus thiooxidans. The observed Ca isotopic fractionation (expressed as Δ44/40Cas-f = δ44/40Casolid-δ44/40Cafluid) at the end of each experimental time period (∼50 to 60 days) was -1.41‰ to -1.09‰ in the biotic experiments, -1.09‰ in the killed control, and -1.01‰ to -0.88‰ in the abiotic controls. As there were no strong differences in the solution chemistry and the rate at which gypsum precipitated in the biotic and abiotic controls, we deduce a biological Ca isotope effect on the order of -0.3‰. The isotope effect correlates with a difference in crystal aspect ratios between the biotic experiments (8.05 ± 3.99) and abiotic controls (31.9 ± 8.40). We hypothesize that soluble and/or insoluble organic compounds selectively inhibit crystal growth at specific crystal faces, and that the growth inhibition affects the fractionation factor associated with gypsum precipitation. The experimental results help explain Ca isotopic variability in gypsum sampled from a sulfidic cave system, in which gypsum crystals exhibiting a diversity of morphologies (microcrystalline to cm-scale needles) have a broad range of δ44/40Ca values (∼1.2-0.4‰) relative to the limestone wall (δ44/40Ca = 1.3‰). In light of the laboratory experiments, the variation in Ca isotope values in the caves can be interpreted as a consequence of gypsum precipitation in the presence of microbial organic matter and subsequent isotopic re-equilibration with the Ca source.

  17. Preparation of nanosized barium zirconate powder by thermal decomposition of urea in an aqueous solution containing barium and zirconium, and by calcination of the precipitate

    OpenAIRE

    Boschini, Frédéric; Robertz, B.; Rulmont, André; Cloots, Rudi

    2003-01-01

    The synthesis of barium zirconate was initiated by urea induced homogeneous precipitation followed by a "low temperature" thermal treatment. The kinetic of the reaction and the optimum urea/cation ratio have been determined by means of X-ray diffraction and Inductive Coupled Plasma analyses. It has been demonstrated that an amorphous zirconium hydrated oxide starts to precipitate followed by the precipitation of barium carbonate. A calcination at 1200 degreesC during 2 h gives rise to the for...

  18. Application of quantitative precipitation forecasting and precipitation ensemble prediction for hydrological forecasting

    Directory of Open Access Journals (Sweden)

    P. Tao

    2015-05-01

    Full Text Available The precipitation in the forecast period influences flood forecasting precision, due to the uncertainty of the input to the hydrological model. Taking the ZhangHe basin as the example, the research adopts the precipitation forecast and ensemble precipitation forecast product of the AREM model, uses the Xin Anjiang hydrological model, and tests the flood forecasts. The results show that the flood forecast result can be clearly improved when considering precipitation during the forecast period. Hydrological forecast based on Ensemble Precipitation prediction gives better hydrological forecast information, better satisfying the need for risk information for flood prevention and disaster reduction, and has broad development opportunities.

  19. The influence of precipitation temperature on the properties of ceria–zirconia solid solution composites

    Energy Technology Data Exchange (ETDEWEB)

    Cui, Yajuan [College of Architecture and Environment, Sichuan University, Chengdu 610065, Sichuan (China); Fang, Ruimei; Shang, Hongyan [College of Chemical Engineering, Sichuan University, Chengdu 610064, Sichuan (China); Shi, Zhonghua; Gong, Maochu [Key Laboratory of Green Chemistry & Technology, Ministry of Education, College of Chemistry, Sichuan University, Chengdu 610064, Sichuan (China); Center of Engineering of Vehicular Exhaust Gases Abatement, Chengdu 610064, Sichuan (China); Center of Engineering of Environmental Catalytic Material, Chengdu 610064, Sichuan (China); Chen, Yaoqiang, E-mail: nic7501@scu.edu.cn [College of Architecture and Environment, Sichuan University, Chengdu 610065, Sichuan (China); College of Chemical Engineering, Sichuan University, Chengdu 610064, Sichuan (China); Key Laboratory of Green Chemistry & Technology, Ministry of Education, College of Chemistry, Sichuan University, Chengdu 610064, Sichuan (China); Center of Engineering of Vehicular Exhaust Gases Abatement, Chengdu 610064, Sichuan (China); Center of Engineering of Environmental Catalytic Material, Chengdu 610064, Sichuan (China)

    2015-04-15

    Highlights: • The crystallite size of precipitate increases as the precipitation temperature rises. • The stack of large crystallite can form nanoparticles with big pore size. • Big pore sizes are advantageous to improve the thermal stability. • Phase segregation is restricted in CZ solid solution precipitated at 70 °C. • The reducibility and OSC of the solid solution precipitated at 70 °C are improved. - Abstract: The ceria–zirconia composites (CZ) with a Ce/Zr mass ratio of 1/1 were synthesized by a back-titration method, in which the influence of precipitation temperature on the properties of ceria–zirconia precipitates was investigated. The resulting precipitation and mixed oxides at different precipitation temperatures were then characterized by a range of techniques, including textural properties, X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS), H{sub 2}-temperature programmed reduction (H{sub 2}-TPR) as well as oxygen storage capacity (OSC) measurement. The results revealed that ceria–zirconia composites were formed as solid solution and such structure is favored of thermostability and texture properties. In particular, the composite CZ-70 synthesized at 70 °C exhibited prominent thermostability with a surface area of 32 m{sup 2}/g as well as a pore volume of 0.15 cc/g after aging treatment at 1000 °C for 5 h. And this was found to be associated with the wider pore size distribution which maybe owed to the formation of large crystal at the primary stage of precipitation. Additionally, the composite CZ-70 showed excellent reduction property and OSC benefiting from stable texture and structure.

  20. Precipitation behavior and effect of new precipitated β phase in AZ80 magnesium alloy

    Institute of Scientific and Technical Information of China (English)

    TANG Wei; HAN En-hou; XU Yong-bo; LIU Lu

    2006-01-01

    Granular precipitate that was a new kind of β-Mg17Al12 phase found in aged AZ80 wrought Mg alloy at all aging temperature was studied. The structure and precipitation behavior of this granular β-Mg17Al12 precipitate were studied by environmental scanning electron microscopy (ESEM) and transmission electron microscopy (TEM). The effect of the granular precipitate on mechanical properties of AZ80 alloy was also studied. The new precipitate that was granular and nucleated both on grain boundaries (GBs) and twin boundaries, has the same crystal structure and lattice parameter as those of the continuous or discontinuous precipitated β-Mg17Al12. And the nucleation and growth of the granular precipitate are faster than those of the other two precipitates at higher temperatures (above 583 K), but are suppressed at lower temperatures (below 423 K). At lower temperatures, the discontinuous β-Mg17Al12 precipitates firstly and the granular β-Mg17Al12 precipitates after aged more than 40 h. The crack is easily nucleated on the phase boundaries of granular phase and matrix because of the weak binding force. As a result, the strength and ductility of AZ80 Mg alloy are decreased by the granular β-Mg17Al12 precipitate.

  1. Interaction of a pseudo-π C—C bond with cuprous and argentous chlorides: Cyclopropane⋯CuCl and cyclopropane⋯AgCl investigated by rotational spectroscopy and ab initio calculations

    Energy Technology Data Exchange (ETDEWEB)

    Zaleski, Daniel P.; Mullaney, John C.; Bittner, Dror M.; Walker, Nicholas R., E-mail: a.c.legon@bristol.ac.uk, E-mail: nick.walker@newcastle.ac.uk [School of Chemistry, Newcastle University, Bedson Building, Newcastle-Upon-Tyne NE1 7RU (United Kingdom); Tew, David P.; Legon, Anthony C., E-mail: a.c.legon@bristol.ac.uk, E-mail: nick.walker@newcastle.ac.uk [School of Chemistry, University of Bristol, Bristol BS8 1TS (United Kingdom)

    2015-10-28

    Strongly bound complexes (CH{sub 2}){sub 3}⋯MCl (M = Cu or Ag), formed by non-covalent interaction of cyclopropane and either cuprous chloride or argentous chloride, have been generated in the gas phase by means of the laser ablation of either copper or silver metal in the presence of supersonically expanded pulses of a gas mixture containing small amounts of cyclopropane and carbon tetrachloride in a large excess of argon. The rotational spectra of the complexes so formed were detected with a chirped-pulse, Fourier transform microwave spectrometer and analysed to give rotational constants and Cu and Cl nuclear quadrupole coupling constants for eight isotopologues of each of (CH{sub 2}){sub 3}⋯CuCl and (CH{sub 2}){sub 3}⋯AgCl. The geometry of each of these complexes was established unambiguously to have C{sub 2v} symmetry, with the three C atoms coplanar, and with the MCl molecule lying along a median of the cyclopropane C{sub 3} triangle. This median coincides with the principal inertia axis a in each of the two complexes (CH{sub 2}){sub 3}⋯MCl. The M atom interacts with the pseudo-π bond linking the pair of equivalent carbon atoms {sup F}C (F = front) nearest to it, so that M forms a non-covalent bond to one C—C edge of the cyclopropane molecule. The (CH{sub 2}){sub 3}⋯MCl complexes have similar angular geometries to those of the hydrogen- and halogen-bonded analogues (CH{sub 2}){sub 3}⋯HCl and (CH{sub 2}){sub 3}⋯ClF, respectively. Quantitative details of the geometries were determined by interpretation of the observed rotational constants and gave results in good agreement with those from ab initio calculations carried out at the CCSD(T)(F12*)/aug-cc-pVTZ-F12 level of theory. Interesting geometrical features are the lengthening of the {sup F}C—{sup F}C bond and the shrinkage of the two equivalent {sup B}C—{sup F}C (B = back) bonds relative to the C—C bond in cyclopropane itself. The expansions of the {sup F}C—{sup F}C bond are 0

  2. Regional Bias of Satellite Precipitation Estimates

    Science.gov (United States)

    Modrick, T. M.; Georgakakos, K. P.; Spencer, C. R.

    2012-12-01

    Satellite-based estimates of precipitation have improved the spatial availability of precipitation data particularly for regions with limited gauge networks due to limited accessibility or infrastructure. Understanding the quality and reliability of satellite precipitation estimates is important, especially when the estimates are utilitized for real-time hydrologic forecasting and for fast-responding phenomena. In partnership with the World Meteorological Organization (WMO), the U.S. Agency of International Development (USAID) and the National Ocean and Atmospheric Administration (NOAA), the Hydrologic Research Center has begun implementation of real-time flash flood warning systems for diverse regions around the world. As part of this effort, bias characteristics of satellite precipitation have been examined in these various regions, such includes portions of Southeastern Asia, Southeastern Europe, the Middle East, Central America, and the southern half of the African continent. The work has focused on the Global Hydro-Estimator (GHE) precipitation product from NOAA/NESDIS. These real-time systems utilize the GHE given low latency times of this product. This presentation focuses on the characterization of precipitation bias as compared to in-situ gauge records, and the regional variations or similarities. Additional analysis is currently underway considering regional bias for other satellite precipitation products (e.g., CMORPH) for comparison with the GHE results.

  3. Facile synthesis of flower like copper oxide and their application to hydrogen peroxide and nitrite sensing

    Directory of Open Access Journals (Sweden)

    Zhang Li

    2011-12-01

    Full Text Available Abstract Background The detection of hydrogen peroxide (H2O2 and nitrite ion (NO2- is of great important in various fields including clinic, food, pharmaceutical and environmental analyses. Compared with many methods that have been developed for the determination of them, the electrochemical detection method has attracted much attention. In recent years, with the development of nanotechnology, many kinds of micro/nano-scale materials have been used in the construction of electrochemical biosensors because of their unique and particular properties. Among these catalysts, copper oxide (CuO, as a well known p-type semiconductor, has gained increasing attention not only for its unique properties but also for its applications in many fields such as gas sensors, photocatalyst and electrochemistry sensors. Continuing our previous investigations on transition-metal oxide including cuprous oxide and α-Fe2O3 modified electrode, in the present paper we examine the electrochemical and electrocatalytical behavior of flower like copper oxide modified glass carbon electrodes (CuO/GCE. Results Flower like copper oxide (CuO composed of many nanoflake was synthesized by a simple hydrothermal reaction and characterized using field-emission scanning electron microscopy (FE-SEM and X-ray diffraction (XRD. CuO modified glass carbon electrode (CuO/GCE was fabricated and characterized electrochemically. A highly sensitive method for the rapid amperometric detection of hydrogen peroxide (H2O2 and nitrite (NO2- was reported. Conclusions Due to the large specific surface area and inner characteristic of the flower like CuO, the resulting electrode show excellent electrocatalytic reduction for H2O2 and oxidation of NO2-. Its sensitivity, low detection limit, fast response time and simplicity are satisfactory. Furthermore, this synthetic approach can also be applied for the synthesis of other inorganic oxides with improved performances and they can also be extended to

  4. A substorm in midnight auroral precipitation

    Directory of Open Access Journals (Sweden)

    V. G. Vorobjev

    Full Text Available DMSP F7 spacecraft observations for the whole of 1986 were used to construct the empirical model of the midnight auroral precipitation during a substorm. The model includes the dynamics of different auroral precipitation boundaries and simultaneous changes in average electron precipitation energy and energy flux in different precipitation regions during all substorm phases, as well as the IMF and solar wind plasma signatures during a substorm. The analysis of the model shows a few important features of precipitation. (1 During the magnetic quietness and just before the beginning of the substorm expansive phase the latitudinal width of the auroral precipitation in the nightside sector is about 5 – 6° CGL, while that of the auroral oval is about 2 – 3° CGL during such periods. (2 For about 5 min before the substorm onset a decrease in the average precipitating electron energy in the equatorward part of auroral zone was observed simultaneously, with an increase in both the average electron energy and energy flux of electron precipitation in the poleward part of the auroral zone. (3 The isotropy boundary position in the beginning of the substorm expansive phase coincides well with the inner edge of the central plasma sheet. The analysis of interplanetary medium parameters shows that, on average, during the substorm development, the solar wind dynamic pressure was about 1.5 times that of the magnetic quietness period. Substorms occurred predominantly during the southward IMF orientation, suggesting that substorm onset often was not associated with the northern turn or decrease in the southward interplanetary Bz . The Northern Hemisphere’s substorms occurred generally during the positive interplanetary By in winter, and they were observed when the interplanetary By was negative in summer.

    Key words. Ionosphere (auroral ionosphere; particle precipitation – Magnetospheric physics

  5. Scales of Topographic Dependence of Alpine Precipitation

    Science.gov (United States)

    Hutchinson, M. F.

    2002-12-01

    Scales of topographic dependence of daily precipitation over the Swiss Alps are examined using a new multivariate precipitation interpolation technique. The method of additive regression splines has been designed to incorporate spatially varying dependences on several topographic variables. It avoids the "curse of dimension" by restricting the underlying spline structure to be two-dimensional. This is in keeping with the overall goal of delivering essentially two-dimensional maps. Moreover, it permits a separation between physical process, as represented by various topographic variables, and the empirically determined, continuous two-dimensional effects of these variables on precipitation across the landscape. The analysis determines horizontal and vertical scales of the interaction of precipitation with topography. A common limitation with existing precipitation interpolation methods lies in their difficulty in identifying effective topographic parameters other than elevation. Orographic effects associated with slope and aspect are often discussed but are not always statistically significant. The effects of two topographic parameters, the northern and eastern components of the unit normal to an appropriately vertically exaggerated digital elevation model, are investigated. These parameters have some basis in process modelling studies and, unlike topographic aspect, are continuous functions of horizontal position. They are used to identify significant topographic aspect effects on precipitation without prior knowledge of the prevailing wind field. Short range correlation structure has rarely been explicitly identified in precipitation interpolation studies but its impact is surprisingly strong. Evidence for its existence in these precipitation data was provided in an earlier study but effective methods for calibrating such correlation in spline analyses have only recently been developed. The spatial scale of correlation found here, around 5 km, is large enough to

  6. A New Method for Near Real Time Precipitation Estimates Using a Derived Statistical Relationship between Precipitable Water Vapor and Precipitation

    Science.gov (United States)

    Roman, J.

    2015-12-01

    The IPCC 5th Assessment found that the predicted warming of 1oC would increase the risk of extreme events such as heat waves, droughts, and floods. Weather extremes, like floods, have shown the vulnerability and susceptibility society has to these extreme weather events, through impacts such as disruption of food production, water supply, health, and damage of infrastructure. This paper examines a new way of near-real time forecasting of precipitation. A 10-year statistical climatological relationship was derived between precipitable water vapor (PWV) and precipitation by using the NASA Atmospheric Infrared Sounder daily gridded PWV product and the NASA Tropical Rainfall Measuring Mission daily gridded precipitation total. Forecasting precipitation estimates in real time is dire for flood monitoring and disaster management. Near real time PWV observations from AIRS on Aqua are available through the Goddard Earth Sciences Data and Information Service Center. In addition, PWV observations are available through direct broadcast from the NASA Suomi-NPP ATMS/CrIS instrument, the operational follow on to AIRS. The derived climatological relationship can be applied to create precipitation estimates in near real time by utilizing the direct broadcasting capabilities currently available in the CONUS region. The application of this relationship will be characterized through case-studies by using near real-time NASA AIRS Science Team v6 PWV products and ground-based SuomiNet GPS to estimate the current precipitation potential; the max amount of precipitation that can occur based on the moisture availability. Furthermore, the potential contribution of using the direct broadcasting of the NUCAPS ATMS/CrIS PWV products will be demonstrated. The analysis will highlight the advantages of applying this relationship in near-real time for flash flood monitoring and risk management. Relevance to the NWS River Forecast Centers will be discussed.

  7. Recent and future extreme precipitation over Ukraine

    Science.gov (United States)

    Vyshkvarkova, Olena; Voskresenskaya, Elena

    2014-05-01

    The aim of study is to analyze the parameters of precipitation extremes and inequality over Ukraine in recent climate epoch and their possible changes in the future. Data of observations from 28 hydrometeorological stations over Ukraine and output of GFDL-CM3 model (CMIP5) for XXI century were used in the study. The methods of concentration index (J. Martin-Vide, 2004) for the study of precipitation inequality while the extreme precipitation indices recommended by the ETCCDI - for the frequency of events. Results. Precipitation inequality on the annual and seasonal scales was studied using estimated CI series for 1951-2005. It was found that annual CI ranges vary from 0.58 to 0.64. They increase southward from the north-west (forest zone) and the north-east (forest steppe zone) of Ukraine. CI maxima are located in the coastal regions of the Black Sea and the Sea of Azov. Annual CI spatial distribution indicates that the contribution of extreme precipitation into annual totals is most significant at the boundary zone between steppe and marine regions. At the same time precipitation pattern at the foothill of Carpathian Mountains is more homogenous. The CI minima (0.54) are typical for the winter season in foothill of Ukrainian Carpathians. The CI maxima reach 0.71 in spring at the steppe zone closed to the Black Sea coast. It should be noted that the greatest ranges of CI maximum and CI minimum deviation are typical for spring. It is associated with patterns of cyclone trajectories in that season. The most territory is characterized by tendency to decrease the contribution of extreme precipitation into the total amount (CI linear trends are predominantly negative in all seasons). Decadal and interdecadal variability of precipitation inequality associated with global processes in ocean-atmosphere system are also studied. It was shown that precipitation inequality over Ukraine on 10 - 15 % stronger in negative phase of Pacific Decadal Oscillation and in positive phase

  8. Nanoparticular metal oxide/anatase catalysts

    DEFF Research Database (Denmark)

    2010-01-01

    The present invention concerns a method of preparation of nanoparticular metal oxide catalysts having a narrow particle size distribution. In particular, the invention concerns preparation of nanoparticular metal oxide catalyst precursors comprising combustible crystallization seeds upon which...... the catalyst metai oxide is co-precipitated with the carrier metal oxide, which crystallization seeds are removed by combustion in a final calcining step. The present invention also concerns processes wherein the nanoparticular metal oxide catalysts of the invention are used, such as SCR (deNOx) reactions...

  9. Recovery of yttrium from fluorescent powder of cathode ray tube, CRT: Zn removal by sulphide precipitation.

    Science.gov (United States)

    Innocenzi, Valentina; De Michelis, Ida; Ferella, Francesco; Beolchini, Francesca; Kopacek, Bernd; Vegliò, Francesco

    2013-11-01

    This work is focused on the recovery of yttrium and zinc from fluorescent powder of cathode ray tube (CRT). Metals are extracted by sulphuric acid in the presence of hydrogen peroxide. Leaching tests are carried out according to a 2(2) full factorial plan and the highest extraction yields for yttrium and zinc equal to 100% are observed under the following conditions: 3M of sulphuric acid, 10% v/v of H2O2 concentrated solution at 30% v/v, 10% w/w pulp density, 70°C and 3h of reaction. Two series of precipitation tests for zinc are carried out: a 2(2) full factorial design and a completely randomized factorial design. In these series the factors investigated are pH of solution during the precipitation and the amount of sodium sulphide added to precipitate zinc sulphide. The data of these tests are used to describe two empirical mathematical models for zinc and yttrium precipitation yields by regression analysis. The highest precipitation yields for zinc are obtained under the following conditions: pH equal to 2-2.5% and 10-12%v/v of Na2S concentrated solution at 10%w/v. In these conditions the coprecipitation of yttrium is of 15-20%. Finally further yttrium precipitation experiments by oxalic acid on the residual solutions, after removing of zinc, show that yttrium could be recovered and calcined to obtain the final product as yttrium oxide. The achieved results allow to propose a CRT recycling process based on leaching of fluorescent powder from cathode ray tube and recovery of yttrium oxide after removing of zinc by precipitation. The final recovery of yttrium is 75-80%.

  10. Precipitation Recycling and the Vertical Distribution of Local and Remote Sources of Water for Precipitation

    Science.gov (United States)

    Bosilovich, Michael G.; Atlas, Robert (Technical Monitor)

    2002-01-01

    Precipitation recycling is defined as the amount of water that evaporates from a region that precipitates within the same region. This is also interpreted as the local source of water for precipitation. In this study, the local and remote sources of water for precipitation have been diagnosed through the use of passive constituent tracers that represent regional evaporative sources along with their transport and precipitation. We will discuss the differences between this method and the simpler bulk diagnostic approach to precipitation recycling. A summer seasonal simulation has been analyzed for the regional sources of the United States Great Plains precipitation. While the tropical Atlantic Ocean (including the Gulf of Mexico) and the local continental sources of precipitation are most dominant, the vertically integrated column of water contains substantial water content originating from the Northern Pacific Ocean, which is not precipitated. The vertical profiles of regional water sources indicate that local Great Plains source of water dominates the lower troposphere, predominantly in the PBL. However, the Pacific Ocean source is dominant over a large portion of the middle to upper troposphere. The influence of the tropical Atlantic Ocean is reasonably uniform throughout the column. While the results are not unexpected given the formulation of the model's convective parameterization, the analysis provides a quantitative assessment of the impact of local evaporation on the occurrence of convective precipitation in the GCM. Further, these results suggest that local source of water is not well mixed throughout the vertical column.

  11. Fundamental features of copper ion precipitation using sulfide as a precipitant in a wastewater system.

    Science.gov (United States)

    Choi, Jung-Yoon; Kim, Dong-Su; Lim, Joong-Yeon

    2006-01-01

    We have investigated the precipitation features of copper ion using sulfide as a precipitant by varying the mole ratio of sulfide to copper ion, pH, temperature and the kind and concentration of complexing agent. In the precipitation of copper ion by sulfide, sludge is produced as cupric sulfide; thus, there is a possibility for its recycled use in photochemical and ceramic processes. When the ratio of the concentration of copper ion to sulfide was increased to more than 1.0, the extent of precipitation was very high. As the ratio was increased, nucleation time was decreased and crystal growth rate was raised. The higher the pH, the greater the amount of precipitated copper ion due to lowered solubility of cupric sulfide. When temperature changed from 25 degrees C to 55 degrees C, the precipitation of copper ion was increased a little. On the basis of estimated thermodynamic parameters such as Gibbs free energy and enthalpy, the precipitation reaction was spontaneous and endothermic. The precipitation of copper ion was lowered in the presence of complexing agent and it was affected by the stability of the copper complex. The feasibility test for the application of precipitation treatment to actual wastewater containing copper ion showed, although there was a little decrease in the removal of copper, the precipitation extent of copper was higher than 90% compared with that for artificial wastewater.

  12. Influence of thermal annealing on microstructural, morphological, optical properties and surface electronic structure of copper oxide thin films

    Energy Technology Data Exchange (ETDEWEB)

    Akgul, Funda Aksoy, E-mail: fundaaksoy01@gmail.com [Department of Physics, Nigde University, 51240 Nigde (Turkey); Center for Solar Energy Research and Applications, Middle East Technical University, 06800 Ankara (Turkey); Akgul, Guvenc, E-mail: guvencakgul@gmail.com [Bor Vocational School, Nigde University, 51700 Nigde (Turkey); Center for Solar Energy Research and Applications, Middle East Technical University, 06800 Ankara (Turkey); Yildirim, Nurcan [Department of Physics Engineering, Ankara University, 06100 Ankara (Turkey); Department of Metallurgical and Materials Engineering, Middle East Technical University, 06800 Ankara (Turkey); Unalan, Husnu Emrah [Department of Metallurgical and Materials Engineering, Middle East Technical University, 06800 Ankara (Turkey); Center for Solar Energy Research and Applications, Middle East Technical University, 06800 Ankara (Turkey); Turan, Rasit [Department of Physics, Middle East Technical University, 06800 Ankara (Turkey); Center for Solar Energy Research and Applications, Middle East Technical University, 06800 Ankara (Turkey)

    2014-10-15

    In this study, effect of the post-deposition thermal annealing on copper oxide thin films has been systemically investigated. The copper oxide thin films were chemically deposited on glass substrates by spin-coating. Samples were annealed in air at atmospheric pressure and at different temperatures ranging from 200 to 600°C. The microstructural, morphological, optical properties and surface electronic structure of the thin films have been studied by diagnostic techniques such as X-ray diffraction (XRD), Raman spectroscopy, ultraviolet–visible (UV–VIS) absorption spectroscopy, field emission scanning electron microscopy (FESEM), atomic force microscopy (AFM), and X-ray photoelectron spectroscopy (XPS). The thickness of the films was about 520 nm. Crystallinity and grain size was found to improve with annealing temperature. The optical bandgap of the samples was found to be in between 1.93 and 2.08 eV. Cupric oxide (CuO), cuprous oxide (Cu{sub 2}O) and copper hydroxide (Cu(OH){sub 2}) phases were observed on the surface of as-deposited and 600 °C annealed thin films and relative concentrations of these three phases were found to depend on annealing temperature. A complete characterization reported herein allowed us to better understand the surface properties of copper oxide thin films which could then be used as active layers in optoelectronic devices such as solar cells and photodetectors. - Highlights: • Effect of post-deposition annealing on copper oxide thin films was investigated. • Structural, optical, and electronic properties of the thin films were determined. • Oxidation states of copper oxide thin films were confirmed by XPS analysis. • Mixed phases of CuO and Cu{sub 2}O were found to coexist in copper oxide thin films.

  13. NESDIS Blended Total Precipitable Water (TPW) Products

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The blended Total Precipitable Water (TPW) product is derived from multiple sensors/satellites. The Percentage of TPW normal (PCT), or TPW anomaly, shows the...

  14. U.S. Hourly Precipitation Data Publication

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This publication contains hourly precipitation amounts obtained from recording rain gages located at National Weather Service, Federal Aviation Administration, and...

  15. U.S. Hourly Precipitation Data

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Hourly Precipitation Data (HPD) is digital data set DSI-3240, archived at the National Climatic Data Center (NCDC). The primary source of data for this file is...

  16. Processing NPP Bottoms by Ferrocyanide Precipitation

    Energy Technology Data Exchange (ETDEWEB)

    Savkin, A. E.; Slastennikov Y. T.; Sinyakin O. G.

    2002-02-25

    The purpose of work is a laboratory test of a technological scheme for cleaning bottoms from radionuclides by use of ozonization, ferrocyanide precipitation, filtration and selective sorption. At carrying out the ferrocyanide precipitation after ozonization, the specific activity of bottoms by Cs{sup 137} is reduced in 100-500 times. It has been demonstrated that the efficiency of ferrocyanide precipitation depends on the quality of consequent filtration. Pore sizes of a filter has been determined to be less than 0.2 {micro}m for complete separation of ferrocyanide residue. The comparison of two technological schemes for cleaning bottoms from radionuclides, characterized by presence of the ferrocyanide precipitation stage has been performed. Application of the proposed schemes allows reducing volumes of radioactive waste in many times.

  17. Acid precipitation - Effects on forest and fish

    Energy Technology Data Exchange (ETDEWEB)

    Overrein, L.N.; Seip, H.M.; Tollan, A.

    1980-01-01

    The Norwegian Interdisciplinary Research Programme 'Acid Precipitation - Effects on Forest and Fish' (The SNSF-project) was initiated in 1972. The main objectives of the SNSF-project have been to: (1) establish as precisely as possible the effects of acid precipitation on forest and freshwater fish, (2) investigate the effects of air pollutants on soil, vegetation and water, required to satisfy point 1. The final report summarizes the results of the entire program on the basis of some 300 SNSF reports and data presented in various international journals in the period 1972-80. Attention is given to emissions and transport, atmospheric deposits in Norway, water acidification - status and trends, chemical modifications of precipitation in contact with soil and vegetation, snow and snowmelt, land-use changes and acidification, conceptual models for water acidification, effects of acid precipitation on soil productivity and plant growth, and effects of acid water on aquatic life.

  18. Identifying external influences on global precipitation

    Energy Technology Data Exchange (ETDEWEB)

    Marvel, K.; Bonfils, C.

    2013-11-11

    Changes in global (ocean and land) precipitation are among the most important and least well-understood consequences of climate change. Increasing greenhouse gas concentrations are thought to affect the zonal-mean distribution of precipitation through two basic mechanisms. First, increasing temperatures will lead to an intensification of the hydrological cycle (“thermodynamic” changes). Second, changes in atmospheric circulation patterns will lead to poleward displacement of the storm tracks and subtropical dry zones and to a widening of the tropical belt (“dynamic” changes). We demonstrate that both these changes are occurring simultaneously in global precipitation, that this behavior cannot be explained by internal variability alone, and that external influences are responsible for the observed precipitation changes. Whereas existing model experiments are not of sufficient length to differentiate between natural and anthropogenic forcing terms at the 95% confidence level, we present evidence that the observed trends result from human activities.

  19. Precipitation Reconstruction over Land (PREC/L)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The monthly data set consists files of 3 resolutions of monthly averaged precipitation totals. The global analyses are defined by interpolation of gauge observations...

  20. BOREAS HYD-8 Gross Precipitation Data

    Science.gov (United States)

    Fernandes, Richard; Hall, Forrest G. (Editor); Knapp, David E. (Editor); Smith, David E. (Technical Monitor)

    2000-01-01

    The Boreal Ecosystem-Atmosphere Study (BOREAS) Hydrology (HYD)-08 team made measurements of surface hydrological processes at the Southern Study Area-Old Black Spruce (SSA-OBS) Tower Flux site to support its research into point hydrological processes and the spatial variation of these processes. Data collected may be useful in characterizing canopy interception, drip, throughfall, moss interception, drainage, evaporation, and capacity during the growing season at daily temporal resolution. This particular data set contains the gross precipitation measurements for July to August 1996. Gross precipitation is the precipitation that falls that is not intercepted by tree canopies. These data are stored in ASCII text files. The HYD-08 gross precipitation data are available from the Earth Observing System Data and Information System (EOSDIS) Oak Ridge National Laboratory (ORNL) Distributed Active Archive Center (DAAC). The data files are available on a CD-ROM (see document number 20010000884).

  1. Application of probabilistic precipitation forecasts from a ...

    African Journals Online (AJOL)

    Application of probabilistic precipitation forecasts from a deterministic model towards increasing the lead-time of flash flood forecasts in South Africa. ... An ensemble set of 30 adjacent basins is then identified as ensemble members for each ...

  2. Average Annual Precipitation (PRISM model) 1961 - 1990

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This map layer shows polygons of average annual precipitation in the contiguous United States, for the climatological period 1961-1990. Parameter-elevation...

  3. VT Mean Annual Precipitation - 1971-2000

    Data.gov (United States)

    Vermont Center for Geographic Information — (Link to Metadata) ClimatePrecip_PRECIPA7100 includes mean annual precipitation data (in inches) for Vermont (1971-2000). It's a raster dataset derived from...

  4. VT Mean Winter Precipitation - 1971-2000

    Data.gov (United States)

    Vermont Center for Geographic Information — (Link to Metadata) ClimatePrecip_PRECIPW7100 includes mean winter precipitation data (October through March) for Vermont (1971-2000). It's a raster dataset derived...

  5. Oligo(L-lysine)-induced titanium dioxide: Effects of consecutive lysine on precipitation

    Science.gov (United States)

    Ahn, Sungjun; Park, Sangwoo; Lee, Sang-Yup

    2011-11-01

    Biomineralization of metal oxide utilizes biomolecular substances, such as peptides and proteins, to induce mineralization of metal precursors in a mild aqueous solution. In this study, we investigated biomineralization of an abiological substance, titanium dioxide (TiO 2), by oligo(L-lysine). Specifically, we systemically studied the influence of the number of consecutive lysine on TiO 2 precipitation. Oligo(L-lysine) was chosen as a homopeptide lysine source whose lysine quantity was adjusted. When oligo(L-lysine) contains more than three consecutive lysine, it induces notably fast precipitation, while single and dilysine do not readily form TiO 2 precipitates. Precipitation of TiO 2 was promoted with the length of oligo(L-lysine). The oligo(L-lysine) was associated with TiO 2 precipitate, which was confirmed by spectroscopic and thermogravitational analyses. The outcomes of this research provide a plausible rationale for explaining precipitation of the Ti precursor that is highly dependent on peptide sequences.

  6. Characterization and comparison of iron oxyhydroxide precipitates from biotic and abiotic groundwater treatments

    DEFF Research Database (Denmark)

    Arturi, Katarzyna Ratajczyk; Koch, Christian Bender; Søgaard, Erik Gydesen

    2017-01-01

    Removal of iron is an important step in groundwater treatment for drinking water production. It is performed to prevent organoleptic issues and clogging in water supply systems. Iron can be eliminated with a purely physico-chemical (abiotic) method or biotically with the help of iron......-oxidizing bacteria (FeOB). Each of the purification methods requires different operating conditions and results in formation of iron oxyhydroxide (FeOOH) precipitates. Knowledge about the differences in composition and properties of the biotic and abiotic precipitates is desirable from a technical, but also...

  7. New insight into nanoparticle precipitation by electron beams in borosilicate glasses

    Science.gov (United States)

    Sabri, M. M.; Möbus, G.

    2017-06-01

    Nanoprecipitation in different oxide glasses by means of electron irradiation in transmission electron microscopy (TEM) has been compared in this study. Upon irradiation, groups or patterns of nanoparticles with various morphologies and sizes were formed in borosilicate glasses, loaded with zinc, copper, and silver. The study successfully includes loading ranges for the target metal from doping level (1%) over medium level (20%) to majority phase (60%). It is found that particle patterning resolution is affected by parallel processes of amorphous phase separation, glass ablation, and delocalised precipitation. In addition, via an in-situ study, it is confirmed that by heating alone without irradiation, no precipitate nanoparticles form.

  8. Characterization and comparison of iron oxyhydroxide precipitates from biotic and abiotic groundwater treatments

    DEFF Research Database (Denmark)

    Arturi, Katarzyna Ratajczyk; Koch, Christian Bender; Søgaard, Erik Gydesen

    2017-01-01

    Removal of iron is an important step in groundwater treatment for drinking water production. It is performed to prevent organoleptic issues and clogging in water supply systems. Iron can be eliminated with a purely physico-chemical (abiotic) method or biotically with the help of iron......-oxidizing bacteria (FeOB). Each of the purification methods requires different operating conditions and results in formation of iron oxyhydroxide (FeOOH) precipitates. Knowledge about the differences in composition and properties of the biotic and abiotic precipitates is desirable from a technical, but also...

  9. Comparison of Characteristics of Sol-Gel and Precipitation Synthesis of Nanosized ZnO Powders

    Institute of Scientific and Technical Information of China (English)

    Xiaoping Liang; Shaobo Xin; Xiaohui Wang; Yajin Liu

    2006-01-01

    Zinc oxide nanosized powders with different sizes and morphologies were obtained by the sol-gel method and the precipitation method, respectively. The effects of the sintering temperature on the characteristics of nanosized ZnO powders were discussed. ZnO particles were characterized by XRD and TEM. The results show that the powders prepared by both methods are of hexagon crystalline, and the average diameter of the particles prepared by the sol-gel method is smaller than that by the precipitation method.

  10. Precipitation Aggregation and the Local Environment

    Science.gov (United States)

    Smalley, Mark

    The details of large-scale spatial structures of precipitation have only recently become apparent with the advent of high-resolution near-global observations from space-borne radars. As such, the relationships between these structures and the local environment and global climate are just beginning to emerge in the scientific community. Precipitation aggregates on a wide variety of scales, from individual boundary layer instabilities to extra-tropical cyclones. Separate aggregation states have been associated with widely varying precipitation rates and atmospheric states, motivating the inclusion of spatial information in hydrologic and climate models. This work adds to the body of knowledge surrounding large-scale precipitation aggregation and its driving factors by describing and demonstrating a new method of defining the spatial characteristics of precipitation events. The analysis relies on the high sensitivity and high resolution of the CloudSat Cloud Profiling Radar for the identification of precipitation with near-global coverage. The method is based on the dependence of the probability of precipitation on search area, or spatial resolution. Variations in this relationship are caused by variations in the principal characteristics of event spatial patterns: the relative spacing between events, the number density of events, and the overall fraction of precipitating scenes at high resolution. Here, this relationship is modeled by a stretched exponential containing two coefficients, that are shown to depict seasonal general circulation patterns as well as local weather. NASA's Modern-Era Retrospective analysis for Research and Applications is then used to place those spatial characteristics in the context of the local and large-scale environment. At regional scale, precipitation event density during the Amazon wet season is shown to be dependent on zonal wind speed. On a global scale, the relative spacing of shallow oceanic precipitation depends on the

  11. Nordic Seas Precipitation Ground Validation Project

    Science.gov (United States)

    Klepp, Christian; Bumke, Karl; Bakan, Stephan; Andersson, Axel

    2010-05-01

    A thorough knowledge of global ocean precipitation is an indispensable prerequisite for the understanding of the water cycle in the global climate system. However, reliable detection of precipitation over the global oceans, especially of solid precipitation, remains a challenging task. This is true for both, passive microwave remote sensing and reanalysis based model estimates. The satellite based HOAPS (Hamburg Ocean Atmosphere Parameters and Fluxes from Satellite Data) climatology contains fields of precipitation, evaporation and the resulting freshwater flux along with 12 additional atmospheric parameters over the global ice-free ocean between 1987 and 2005. Except for the NOAA Pathfinder SST, all basic state variables are calculated from SSM/I passive microwave radiometer measurements. HOAPS contains three main data subsets that originate from one common pixel-level data source. Gridded 0.5 degree monthly, pentad and twice daily data products are freely available from www.hoaps.org. The optical disdrometer ODM 470 is a ground validation instrument capable of measuring rain and snowfall on ships even under high wind speeds. It was used for the first time over the Nordic Seas during the LOFZY 2005 campaign. A dichotomous verification for these snowfall events resulted in a perfect score between the disdrometer, a precipitation detector and a shipboard observer's log. The disdrometer data is further point-to-area collocated against precipitation from three satellite derived climatologies, HOAPS-3, the Global Precipitation Climatology Project (GPCP) one degree daily (1DD) data set, and the Goddard Profiling algorithm, version 2004 (GPROF 2004). Only the HOAPS precipitation turns out to be overall consistent with the disdrometer data resulting in an accuracy of 0.96. The collocated data comprises light precipitation events below 1 mm/h. Therefore two LOFZY case studies with high precipitation rates are presented that still indicate plausible results. Overall, this

  12. Climate Prediction Center (CPC) Global Precipitation Time Series

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The global precipitation time series provides time series charts showing observations of daily precipitation as well as accumulated precipitation compared to normal...

  13. Aspects of precipitation in alloy Inconel 718

    OpenAIRE

    Azadian, Saied

    2004-01-01

    A study was made of the microstructure of the Ni-base alloy Inconel 718 with emphasis on the precipitation and stability of intermetallic phases as affected by heat treatments. In addition the effect of the precipitation on selected mechanical properties namely hardness, creep notch sensitivity and hot ductlity were investigated. The materials studied were a spray-formed version and three wrought versions of the alloy. The spray-formed version of the alloy was of interest since it exhibited a...

  14. Precipitation Nowcast using Deep Recurrent Neural Network

    Science.gov (United States)

    Akbari Asanjan, A.; Yang, T.; Gao, X.; Hsu, K. L.; Sorooshian, S.

    2016-12-01

    An accurate precipitation nowcast (0-6 hours) with a fine temporal and spatial resolution has always been an important prerequisite for flood warning, streamflow prediction and risk management. Most of the popular approaches used for forecasting precipitation can be categorized into two groups. One type of precipitation forecast relies on numerical modeling of the physical dynamics of atmosphere and another is based on empirical and statistical regression models derived by local hydrologists or meteorologists. Given the recent advances in artificial intelligence, in this study a powerful Deep Recurrent Neural Network, termed as Long Short-Term Memory (LSTM) model, is creatively used to extract the patterns and forecast the spatial and temporal variability of Cloud Top Brightness Temperature (CTBT) observed from GOES satellite. Then, a 0-6 hours precipitation nowcast is produced using a Precipitation Estimation from Remote Sensing Information using Artificial Neural Network (PERSIANN) algorithm, in which the CTBT nowcast is used as the PERSIANN algorithm's raw inputs. Two case studies over the continental U.S. have been conducted that demonstrate the improvement of proposed approach as compared to a classical Feed Forward Neural Network and a couple simple regression models. The advantages and disadvantages of the proposed method are summarized with regard to its capability of pattern recognition through time, handling of vanishing gradient during model learning, and working with sparse data. The studies show that the LSTM model performs better than other methods, and it is able to learn the temporal evolution of the precipitation events through over 1000 time lags. The uniqueness of PERSIANN's algorithm enables an alternative precipitation nowcast approach as demonstrated in this study, in which the CTBT prediction is produced and used as the inputs for generating precipitation nowcast.

  15. Discontinuous precipitation in copper base alloys

    Indian Academy of Sciences (India)

    K T Kashyap

    2009-08-01

    Discontinuous precipitation (DP) is associated with grain boundary migration in the wake of which alternate plates of the precipitate and the depleted matrix form. Some copper base alloys show DP while others do not. In this paper the misfit strain parameter, , has been calculated and predicted that if 100 > ± 0.1, DP is observed. This criterion points to diffusional coherency strain theory to be the operative mechanism for DP.

  16. Precipitation in a lead calcium tin anode

    Energy Technology Data Exchange (ETDEWEB)

    Perez-Gonzalez, Francisco A., E-mail: fco.aurelio@inbox.com [Facultad de Ingenieria Mecanica y Electrica, Universidad Autonoma de Nuevo Leon (Mexico); Centro de Innovacion, Investigacion y Desarrollo en Ingenieria y Tecnologia, Universidad Autonoma de Nuevo Leon (Mexico); Camurri, Carlos G., E-mail: ccamurri@udec.cl [Departamento de Ingenieria de Materiales, Universidad de Concepcion (Chile); Carrasco, Claudia A., E-mail: ccarrascoc@udec.cl [Departamento de Ingenieria de Materiales, Universidad de Concepcion (Chile); Colas, Rafael, E-mail: rafael.colas@uanl.edu.mx [Facultad de Ingenieria Mecanica y Electrica, Universidad Autonoma de Nuevo Leon (Mexico); Centro de Innovacion, Investigacion y Desarrollo en Ingenieria y Tecnologia, Universidad Autonoma de Nuevo Leon (Mexico)

    2012-02-15

    Samples from a hot rolled sheet of a tin and calcium bearing lead alloy were solution heat treated at 300 Degree-Sign C and cooled down to room temperature at different rates; these samples were left at room temperature to study natural precipitation of CaSn{sub 3} particles. The samples were aged for 45 days before analysing their microstructure, which was carried out in a scanning electron microscope using secondary and backscattered electron detectors. Selected X-ray spectra analyses were conducted to verify the nature of the precipitates. Images were taken at different magnifications in both modes of observation to locate the precipitates and record their position within the images and calculate the distance between them. Differential scanning calorimeter analyses were conducted on selected samples. It was found that the mechanical properties of the material correlate with the minimum average distance between precipitates, which is related to the average cooling rate from solution heat treatment. - Highlights: Black-Right-Pointing-Pointer The distance between precipitates in a lead alloy is recorded. Black-Right-Pointing-Pointer The relationship between the distance and the cooling rate is established. Black-Right-Pointing-Pointer It is found that the strengthening of the alloy depends on the distance between precipitates.

  17. Improved Aeration Process - Catalytic Role Of The Iron Oxides In Arsenic Oxidation And Coprecipitation

    DEFF Research Database (Denmark)

    Kowalski, Krysztof; Søgaard, Erik Gydesen

    2013-01-01

    an improved aeration process that can also help in developing better arsenic removal treatment. The results present advantages of arsenic oxidation in an aeration process in the presence of ferrihydrite surface that have been shown to adsorb arsenic simultaneously to its oxidation. The presence...... of precipitated (ferrihydrite surface) and dissolved iron enhanced arsenic oxidation in comparison to solution with absence of precipitated iron in laboratory scale experiments. However, in the pilot scale studies the adsorption of arsenite on ferrihydrite was found to be the main process occurring during...... implementation of the process in the waterworks that are struggling with arsenic related issues....

  18. Poly(ethylene oxide) functionalization

    Energy Technology Data Exchange (ETDEWEB)

    Pratt, Russell Clayton

    2014-04-08

    A simple procedure is provided by which the hydroxyl termini of poly(ethylene oxide) can be appended with functional groups to a useful extent by reaction and precipitation. The polymer is dissolved in warmed toluene, treated with an excess of organic base and somewhat less of an excess of a reactive acylating reagent, reacted for several hours, then precipitated in isopropanol so that the product can be isolated as a solid, and salt byproducts are washed away. This procedure enables functionalization of the polymer while not requiring laborious purification steps such as solvent-solvent extraction or dialysis to remove undesirable side products.

  19. Ergothioneine prevents copper-induced oxidative damage to DNA and protein by forming a redox-inactive ergothioneine-copper complex.

    Science.gov (United States)

    Zhu, Ben-Zhan; Mao, Li; Fan, Rui-Mei; Zhu, Jun-Ge; Zhang, Ying-Nan; Wang, Jing; Kalyanaraman, Balaraman; Frei, Balz

    2011-01-14

    Ergothioneine (2-mercaptohistidine trimethylbetaine) is a naturally occurring amino acid analogue found in up to millimolar concentrations in several tissues and biological fluids. However, the biological functions of ergothioneine remain incompletely understood. In this study, we investigated the role of ergothioneine in copper-induced oxidative damage to DNA and protein, using two copper-containing systems: Cu(II) with ascorbate and Cu(II) with H(2)O(2) [0.1 mM Cu(II), 1 mM ascorbate, and 1 mM H(2)O(2)]. Oxidative damage to DNA and bovine serum albumin was measured as strand breakage and protein carbonyl formation, respectively. Ergothioneine (0.1-1.0 mM) provided strong, dose-dependent protection against oxidation of DNA and protein in both copper-containing systems. In contrast, only limited protection was observed with the purported hydroxyl radical scavengers, dimethyl sulfoxide and mannitol, even at concentrations as high as 100 mM. Ergothioneine also significantly inhibited copper-catalyzed oxidation of ascorbate and competed effectively with histidine and 1,10-phenanthroline for binding of cuprous copper, but not cupric copper, as demonstrated by UV-visible and low-temperature electron spin resonance techniques. We conclude that ergothioneine is a potent, natural sulfur-containing antioxidant that prevents copper-dependent oxidative damage to biological macromolecules by forming a redox-inactive ergothioneine-copper complex.

  20. Effect of copper oxide electrocatalyst on CO2 reduction using Co3O4 as anode

    Directory of Open Access Journals (Sweden)

    V.S.K. Yadav

    2016-09-01

    Full Text Available The reduction of carbon dioxide (CO2 to products electrochemically (RCPE in 0.5 M NaHCO3 and Na2CO3 liquid phase electrolyte solutions was investigated. Cobalt oxide (Co3O4 as anode and cuprous oxide (Cu2O as the cathode were considered, respectively. The impacts of applied potential with time of reaction during reduction of CO2 to products were studied. The anode and cathode were prepared by depositing electrocatalysts on the graphite plate. Ultra-fast liquid chromatography (UFLC was used to analyze the products obtained from the reduction of CO2. The feasible way of reduction by applying voltages with current densities was clearly correlated. The results illustrate the capability of electrocatalyst successfully to remove atmospheric CO2 in the form of valuable chemicals. Maximum Faradaic efficiency of ethanol was 98.1% at 2 V and for formic acid (36.6% at 1.5 V was observed in NaHCO3. On the other hand, in Na2CO3 electrolyte solution maximum efficiency for ethanol was 55.21% at 1.5 V and 25.1% for formic acid at 2 V. In both electrolytes other end products like methanol, propanol, formaldehyde and acetic acid were formed at various applied voltage and output current densities.

  1. Global Precipitation Measurement (GPM) Mission: Precipitation Processing System (PPS) GPM Mission Gridded Text Products Provide Surface Precipitation Retrievals

    Science.gov (United States)

    Stocker, Erich Franz; Kelley, O.; Kummerow, C.; Huffman, G.; Olson, W.; Kwiatkowski, J.

    2015-01-01

    In February 2015, the Global Precipitation Measurement (GPM) mission core satellite will complete its first year in space. The core satellite carries a conically scanning microwave imager called the GPM Microwave Imager (GMI), which also has 166 GHz and 183 GHz frequency channels. The GPM core satellite also carries a dual frequency radar (DPR) which operates at Ku frequency, similar to the Tropical Rainfall Measuring Mission (TRMM) Precipitation Radar, and a new Ka frequency. The precipitation processing system (PPS) is producing swath-based instantaneous precipitation retrievals from GMI, both radars including a dual-frequency product, and a combined GMIDPR precipitation retrieval. These level 2 products are written in the HDF5 format and have many additional parameters beyond surface precipitation that are organized into appropriate groups. While these retrieval algorithms were developed prior to launch and are not optimal, these algorithms are producing very creditable retrievals. It is appropriate for a wide group of users to have access to the GPM retrievals. However, for researchers requiring only surface precipitation, these L2 swath products can appear to be very intimidating and they certainly do contain many more variables than the average researcher needs. Some researchers desire only surface retrievals stored in a simple easily accessible format. In response, PPS has begun to produce gridded text based products that contain just the most widely used variables for each instrument (surface rainfall rate, fraction liquid, fraction convective) in a single line for each grid box that contains one or more observations.This paper will describe the gridded data products that are being produced and provide an overview of their content. Currently two types of gridded products are being produced: (1) surface precipitation retrievals from the core satellite instruments GMI, DPR, and combined GMIDPR (2) surface precipitation retrievals for the partner constellation

  2. Characteristics of the precipitation recycling ratio and its relationship with regional precipitation in China

    Science.gov (United States)

    Hua, Lijuan; Zhong, Linhao; Ke, Zongjian

    2017-02-01

    A dynamic recycling model (DRM) with an analytical moisture trajectory tracking method, together with Japan Meteorological Agency 25-year reanalysis data, is used to study the regional precipitation recycling process across China, by calculating the regional recycling ratio ( ρ r ) at the daily time scale during 1979-2010. The distribution of ρ r shows that, in western China, especially the Tibetan Plateau and its surrounding areas, precipitation is strongly dependent on the recycling process associated with regional evaporation. In Southeast China, however, the contribution from the recycling processes is much smaller due to the influence of the summer monsoon. A precipitation threshold value of about 4 mm/day is obtained from detailed analysis of both extreme and all-range ρ r years. According to this threshold, China is classified into three types of sub-regions: low-precipitation sub-regions (mainly in the northwest), high-precipitation sub-regions (mainly in the south), and medium-precipitation sub-regions (mainly in the northeast). It is found that ρ r correlates positively with precipitation, as well as convective precipitation ( P CP) and large-scale precipitation ( P LP) in the low-precipitation sub-regions. However, negative ρ r ˜ P LP correlations are found in the high-precipitation sub-regions and nonsignificant correlations exist in the medium-precipitation sub-regions. As P CP is mainly locally generated due to mid-latitude mesoscale systems and the cumulus parameterization used in producing the reanalysis, the recycling ratio positively correlates to the ratio P CP/ P LP in almost all sub-regions, particularly in the Tibetan Plateau and its surrounding areas. The correlation between radiation flux and ρ r suggests more net radiation supports more evaporation and higher ρ r , especially in the high-precipitation sub-regions. The influence of clouds on shortwave radiation is crucial, since evaporation is suppressed when the amount of cloudiness

  3. [Comment on “A new interdisciplinary focus on precipitation research”] Precipitation research

    Science.gov (United States)

    Rodda, John C.

    I am writing concerning the lead article in the June 5, 1984, Eos, entitled “A new interdisciplinary focus on precipitation research,” particularly the paragraph headed “Measurement of Precipitation.” Measurement of precipitation is a subject of which I know a little. My knowledge comes largely from experimental work in the 1960s and 1970s and committee work subsequently (I even attended one meeting of the 1970 AGU committee). I imagined that, at that time and subsequently, it had become an acknowledged fact in the United States and elsewhere that measurements of precipitation are not easy to make.

  4. Germanium separation and purification by leaching and precipitation

    Institute of Scientific and Technical Information of China (English)

    Saeid Bayat; Sajjad Aghazadeh; Mohammad Noaparast; Mahdi Gharabaghi; Behrooz Taheri

    2016-01-01

    In this research work, extraction and purification of germanium from zinc leach residues (ZLR) were investigated. The results of ICP, XRF, and atomic adsorption spectroscopy (AAS) tests show that contents of germanium, iron, lead, and zinc within the leaching residue were 105×10−6, 3.53%, 10.35%, and 8.8%, respectively. XRD results indicate that the main minerals were in different forms of sulfates (CaSO4·2H2O, PbSO4 and ZnSO4·6H2O), silicate (SiO2), and oxide (Fe2O3). Dissolution of leaching filter cake was carried out using 5 parameters and each in 4 levels (acid concentration, temperature, time, liquid-to-solid ratio, and stirring speed) by Taguchi method (L16), and then optimization of the effective parameters by response surface method. Under optimum conditions, zinc and germanium dissolution efficiencies were 88.71% and 8%, respectively. Leaching tests with sulfuric acid (added di-ammonium oxalate monohydrate) and hydrochloric acid (HCl) on the residues obtained from previous-stage sulfuric acid dissolution, yielded germanium and iron recoveries of 83%, 88%, 40%, and 90%, respectively. Thus, leaching experiment with sulfuric acid (added di-ammonium oxalate monohydrate) was superior to that with hydrochloric acid due to high and low extraction amounts of germanium and iron, respectively. Precipitation experiments revealed that germanium purification with tannic acid presented a better result compared to sodium hydroxide and ammonia. Under optimum conditions, contents of germanium and iron in the solution after precipitation were 0.1505% and 14.7% with precipitation yields of 91% and 52%, respectively.

  5. Methods of producing adsorption media including a metal oxide

    Science.gov (United States)

    Mann, Nicholas R; Tranter, Troy J

    2014-03-04

    Methods of producing a metal oxide are disclosed. The method comprises dissolving a metal salt in a reaction solvent to form a metal salt/reaction solvent solution. The metal salt is converted to a metal oxide and a caustic solution is added to the metal oxide/reaction solvent solution to adjust the pH of the metal oxide/reaction solvent solution to less than approximately 7.0. The metal oxide is precipitated and recovered. A method of producing adsorption media including the metal oxide is also disclosed, as is a precursor of an active component including particles of a metal oxide.

  6. Precipitating Mechanism of Carbide in Cold-Welding Surfacing Metals

    Institute of Scientific and Technical Information of China (English)

    Yuanbin ZHANG; Dengyi REN

    2004-01-01

    Carbides in a series of cold-welding weld metals were studied by means of SEM, TEM and EPMA, and the forming mechanism of carbide was proposed according to their distribution and morphology. Due to their different carbide-forming tendency, Nb and Ti could combine with C to form particulate carbide in liquid weld metal and depleted the carbon content in matrix, while V induced the carbide precipitated along grain boundary. But too much Nb or Ti alone resulted in coarse carbide and poor strengthened matrix. When suitable amount of Nb, Ti and V coexisted in weld metal, both uniformly distributed particulate carbide and well strengthened matrix could be achieved. It was proposed that the carbide nucleated on the oxide which dispersed in liquid weld metal, and then grew into multi-layer complex carbide particles by epitaxial growth. At different sites, carbide particles may present as different morphologies.

  7. Binary Oxide p-n Heterojunction Piezoelectric Nanogenerators with an Electrochemically Deposited High p-Type Cu2O Layer.

    Science.gov (United States)

    Baek, Seung Ki; Kwak, Sung Soo; Kim, Joo Sung; Kim, Sang Woo; Cho, Hyung Koun

    2016-08-31

    The high performance of ZnO-based piezoelectric nanogenerators (NGs) has been limited due to the potential screening from intrinsic electron carriers in ZnO. We have demonstrated a novel approach to greatly improve piezoelectric power generation by electrodepositing a high-quality p-type Cu2O layer between the piezoelectric semiconducting film and the metal electrode. The p-n heterojunction using only oxides suppresses the screening effect by forming an intrinsic depletion region, and thus sufficiently enhances the piezoelectric potential, compared to the pristine ZnO piezoelectric NG. Interestingly, a Sb-doped Cu2O layer has high mobility and low surface trap states. Thus, this doped layer is an attractive p-type material to significantly improve piezoelectric performance. Our results revealed that p-n junction NGs consisting of Au/ZnO/Cu2O/indium tin oxide with a Cu2O:Sb (cuprous oxide with a small amount of antimony) layer of sufficient thickness (3 μm) exhibit an extraordinarily high piezoelectric potential of 0.9 V and a maximum output current density of 3.1 μA/cm(2).

  8. Arsenic precipitation from metallurgical effluents; Precipitacion de arsenico desde efluentes metalurgicos

    Energy Technology Data Exchange (ETDEWEB)

    Navarro, P.; Vargas, C.; Araya, E.; Martin, I.; Alguacil, F. J.

    2004-07-01

    In the mining-metallurgical companies different liquid effluents are produced, which can contain a series of dissolved elements that are considered dangerous from an environmental point of view. One of these elements is the arsenic, especially in the state of oxidation +5 that can be precipitated as calcium or iron arsenate. To fulfil the environmental requests it should have in solution a content of arsenic lower than 0,5 mg/l and the obtained solid product should be very stable under the condition in which it will be stored. this work looks for the best conditions of arsenic precipitation, until achieving contents in solution lower than such mentioned concentration. Also, the stability of the precipitates was studied. (Author) 7 refs.

  9. Homogeneous Precipitation of Nickel Hydroxide Powders

    Energy Technology Data Exchange (ETDEWEB)

    Bora Mavis

    2003-12-12

    Precipitation and characterization of nickel hydroxide powders were investigated. A comprehensive precipitation model incorporating the metal ion hydrolysis, complexation and precipitation reactions was developed for the production of the powders with urea precipitation method. Model predictions on Ni{sup 2+} precipitation rate were confirmed with precipitation experiments carried out at 90 C. Experimental data and model predictions were in remarkable agreement. Uncertainty in the solubility product data of nickel hydroxides was found to be the large contributor to the error. There were demonstrable compositional variations across the particle cross-sections and the growth mechanism was determined to be the aggregation of primary crystallites. This implied that there is a change in the intercalate chemistry of the primary crystallites with digestion time. Predicted changes in the concentrations of simple and complex ions in the solution support the proposed mechanism. The comprehensive set of hydrolysis reactions used in the model described above allows the investigation of other systems provided that accurate reaction constants are available. the fact that transition metal ions like Ni{sup 2+} form strong complexes with ammonia presents a challenge in the full recovery of the Ni{sup 2+}. On the other hand, presence of Al{sup 3+} facilitates the complete precipitation of Ni{sup 2+} in about 3 hours of digestion. A challenge in their predictive modeling studies had been the fact that simultaneous incorporation of more than one metal ion necessitates a different approach than just using the equilibrium constants of hydrolysis, complexation and precipitation reactions. Another limitation of using equilibrium constants is that the nucleation stage of digestion, which is controlled mainly by kinetics, is not fully justified. A new program released by IBM Almaden Research Center (Chemical Kinetics Simulator{trademark}, Version 1.01) lets the user change the order of

  10. Complex precipitation pathways in multicomponent alloys

    Energy Technology Data Exchange (ETDEWEB)

    Clouet, Emmanuel; Nastar, Maylise [Service de Recherches de Metallurgie Physique, CEA/Saclay, 91191 Gif-sur-Yvette (France); Lae, Ludovic; Deschamps, Alexis [LTPCM/ENSEEG, UMR CNRS 5614, Domaine Universitaire, BP 75, 38402 St Martin d' Heres (France); Epicier, Thierry [Groupe d' Etudes de Metallurgie Physique et de Physique des Materiaux, UMR CNRS 5510, INSA, 69621 Villeurbanne (France); Lefebvre, Williams [Groupe de Physique des Materiaux, UMR CNRS 6634, Universite de Rouen, 76801 Saint Etienne du Rouvray (France)

    2006-07-01

    One usual way to strengthen a metal is to add alloying elements and to control the size and the density of the precipitates obtained. However, precipitation in multicomponent alloys can take complex pathways depending on the relative diffusivity of solute atoms and on the relative driving forces involved. In Al - Zr - Sc alloys, atomic simulations based on first-principle calculations combined with various complementary experimental approaches working at different scales reveal a strongly inhomogeneous structure of the precipitates: owing to the much faster diffusivity of Sc compared with Zr in the solid solution, and to the absence of Zr and Sc diffusion inside the precipitates, the precipitate core is mostly Sc-rich, whereas the external shell is Zr-rich. This explains previous observations of an enhanced nucleation rate in Al - Zr - Sc alloys compared with binary Al - Sc alloys, along with much higher resistance to Ostwald ripening, two features of the utmost importance in the field of light high-strength materials. (authors)

  11. Global Precipitation Measurement Cold Season Precipitation Experiment (GCPEx): For Measurement Sake Let it Snow

    Science.gov (United States)

    Skofronick-Jackson, Gail; Hudak, David; Petersen, Walter; Nesbitt, Stephen W.; Chandrasekar, V.; Durden, Stephen; Gleicher, Kirstin J.; Huang, Gwo-Jong; Joe, Paul; Kollias, Pavlos; Reed, Kimberly A.; Schwaller, Mathew R.; Stewart, Ronald; Tanelli, Simone; Tokay, Ali; Wang, James R.; Wolde, Mengistu

    2014-01-01

    As a component of the Earth's hydrologic cycle, and especially at higher latitudes,falling snow creates snow pack accumulation that in turn provides a large proportion of the fresh water resources required by many communities throughout the world. To assess the relationships between remotely sensed snow measurements with in situ measurements, a winter field project, termed the Global Precipitation Measurement (GPM) mission Cold Season Precipitation Experiment (GCPEx), was carried out in the winter of 2011-2012 in Ontario, Canada. Its goal was to provide information on the precipitation microphysics and processes associated with cold season precipitation to support GPM snowfall retrieval algorithms that make use of a dual-frequency precipitation radar and a passive microwave imager on board the GPM core satellite,and radiometers on constellation member satellites. Multi-parameter methods are required to be able to relate changes in the microphysical character of the snow to measureable parameters from which precipitation detection and estimation can be based. The data collection strategy was coordinated, stacked, high-altitude and in-situ cloud aircraft missions with three research aircraft sampling within a broader surface network of five ground sites taking in-situ and volumetric observations. During the field campaign 25 events were identified and classified according to their varied precipitation type, synoptic context, and precipitation amount. Herein, the GCPEx fieldcampaign is described and three illustrative cases detailed.

  12. The Role of CO2 Physiological Forcing in Driving Future Precipitation Variability and Precipitation Extremes

    Science.gov (United States)

    Skinner, C. B.; Poulsen, C. J.

    2015-12-01

    Transpired water contributes roughly 25% to total precipitation over the Earth's land surface. In addition to transpiration's impact on climatological mean precipitation, recent work suggests that transpiration reduces daily and intraseasonal precipitation variability in tropical forest regions. Projected increases in the concentration of CO2 are expected to reduce transpiration through changes in plant physiology (termed the CO2 physiological effect). Here, we use an ensemble of climate model experiments to assess the potential contribution of the CO2 physiological effect to future changes in precipitation variability and extreme precipitation events. Within our model simulations, precipitation responses to the physiological effects of increased CO2 concentrations are greatest throughout the tropics. In most tropical forest regions CO2 physiological forcing increases the annual number of dry (less than 0.1 mm/day) and extremely wet (rainfall exceeds 95th percentile) days. Changes in precipitation are primarily driven by an increase in surface temperature and subsequent changes in atmospheric stability and moisture convergence over vegetated tropical land regions. Our results suggest that the plant physiological response to CO2 forcing may serve as an important contributor to future precipitation variability in the tropics, and that future work should aim to reduce uncertainty in the response of plant physiology to changes in climate.

  13. Analysis of nanometer-scale precipitation in a rapidly solidified stainless steel

    Energy Technology Data Exchange (ETDEWEB)

    Wisutmethangoon, S.; Kelly, T.F.; Camus, P.P.; Flinn, J.E. [Univ. of Wisconsin, Madison, WI (United States). Dept. of Materials Science and Engineering; Larson, D.J.; Miller, M.K. [Oak Ridge National Lab., TN (United States). Metals and Ceramics Div.

    1997-03-21

    The authors have rapid-solidification-processed many stainless steels by gas atomization and achieved strength improvements of over 50% relative to conventionally-processed stainless steels with concomitant improvement in corrosion and oxidation behavior. These strength improvements are most pronounced after aging treatments when elevated concentrations of oxygen and vanadium are present in the stainless steel. An austenitic (FCC) stainless steel was prepared by gas atomization and consolidated by hot extrusion at 900 C. These specimens were heat treated for 1 hour at 1,000 C and aged at 600 C for 500 hours. The microstructure of each alloy composition was observed in TEM with bright field imaging. After aging, most alloys showed the same precipitate morphology as before aging. An obvious change, however, was found only in the alloy with highest oxygen content. A high number density of 15 to 20 nm diameter precipitates was measured in this alloy. Moreover, with weak-beam dark field imaging, a very high number density of coherent, 6 to 10 nm diameter precipitates is observed throughout the matrix by Moire fringe contrast. An atom probe field ion microscopy (APFIM) investigation showed that FIM provides high contrast imaging the precipitates. In order to get a more global view of the structure, energy-filtered composition imaging on a LEO EM 912 was used to map the oxygen and nitrogen in carbon extraction replicas of the aged specimens. These images confirm that the 18 nm precipitates are oxides, however, it appears that the 8 nm precipitates are not extracted.

  14. Chlorination of bromide-containing waters: Enhanced bromate formation in the presence ofsynthetic metal oxides and deposits formed indrinking water distribution systems

    KAUST Repository

    Liu, Chao

    2013-09-01

    Bromate formation from the reaction between chlorine and bromide in homogeneous solution is a slow process. The present study investigated metal oxides enhanced bromate formation during chlorination of bromide-containing waters. Selected metal oxides enhanced the decay of hypobromous acid (HOBr), a requisite intermediate during the oxidation of bromide to bromate, via (i) disproportionation to bromate in the presence of nickel oxide (NiO) and cupric oxide (CuO), (ii) oxidation of a metal to a higher valence state in the presence of cuprous oxide (Cu2O) and (iii) oxygen formation by NiO and CuO. Goethite (α-FeOOH) did not enhance either of these pathways. Non-charged species of metal oxides seem to be responsible for the catalytic disproportionation which shows its highest rate in the pH range near the pKa of HOBr. Due to the ability to catalyze HOBr disproportionation, bromate was formed during chlorination of bromide-containing waters in the presence of CuO and NiO, whereas no bromate was detected in the presence of Cu2O and α-FeOOH for analogous conditions. The inhibition ability of coexisting anions on bromate formation at pH 8.6 follows the sequence of phosphate>>sulfate>bicarbonate/carbonate. A black deposit in a water pipe harvested from a drinking water distribution system exerted significant residual oxidant decay and bromate formation during chlorination of bromide-containing waters. Energy dispersive spectroscopy (EDS) analyses showed that the black deposit contained copper (14%, atomic percentage) and nickel (1.8%, atomic percentage). Cupric oxide was further confirmed by X-ray diffraction (XRD). These results indicate that bromate formation may be of concern during chlorination of bromide-containing waters in distribution systems containing CuO and/or NiO. © 2013 Elsevier Ltd.

  15. Chlorination of bromide-containing waters: enhanced bromate formation in the presence of synthetic metal oxides and deposits formed in drinking water distribution systems.

    Science.gov (United States)

    Liu, Chao; von Gunten, Urs; Croué, Jean-Philippe

    2013-09-15

    Bromate formation from the reaction between chlorine and bromide in homogeneous solution is a slow process. The present study investigated metal oxides enhanced bromate formation during chlorination of bromide-containing waters. Selected metal oxides enhanced the decay of hypobromous acid (HOBr), a requisite intermediate during the oxidation of bromide to bromate, via (i) disproportionation to bromate in the presence of nickel oxide (NiO) and cupric oxide (CuO), (ii) oxidation of a metal to a higher valence state in the presence of cuprous oxide (Cu2O) and (iii) oxygen formation by NiO and CuO. Goethite (α-FeOOH) did not enhance either of these pathways. Non-charged species of metal oxides seem to be responsible for the catalytic disproportionation which shows its highest rate in the pH range near the pKa of HOBr. Due to the ability to catalyze HOBr disproportionation, bromate was formed during chlorination of bromide-containing waters in the presence of CuO and NiO, whereas no bromate was detected in the presence of Cu2O and α-FeOOH for analogous conditions. The inhibition ability of coexisting anions on bromate formation at pH 8.6 follows the sequence of phosphate > sulfate > bicarbonate/carbonate. A black deposit in a water pipe harvested from a drinking water distribution system exerted significant residual oxidant decay and bromate formation during chlorination of bromide-containing waters. Energy dispersive spectroscopy (EDS) analyses showed that the black deposit contained copper (14%, atomic percentage) and nickel (1.8%, atomic percentage). Cupric oxide was further confirmed by X-ray diffraction (XRD). These results indicate that bromate formation may be of concern during chlorination of bromide-containing waters in distribution systems containing CuO and/or NiO. Copyright © 2013 Elsevier Ltd. All rights reserved.

  16. Precipitation-runoff modeling system; user's manual

    Science.gov (United States)

    Leavesley, G.H.; Lichty, R.W.; Troutman, B.M.; Saindon, L.G.

    1983-01-01

    The concepts, structure, theoretical development, and data requirements of the precipitation-runoff modeling system (PRMS) are described. The precipitation-runoff modeling system is a modular-design, deterministic, distributed-parameter modeling system developed to evaluate the impacts of various combinations of precipitation, climate, and land use on streamflow, sediment yields, and general basin hydrology. Basin response to normal and extreme rainfall and snowmelt can be simulated to evaluate changes in water balance relationships, flow regimes, flood peaks and volumes, soil-water relationships, sediment yields, and groundwater recharge. Parameter-optimization and sensitivity analysis capabilites are provided to fit selected model parameters and evaluate their individual and joint effects on model output. The modular design provides a flexible framework for continued model system enhancement and hydrologic modeling research and development. (Author 's abstract)

  17. Stochastic Precipitation Downscaling with Orographic Corrections

    Science.gov (United States)

    Brussolo, Elisa; von Hardenberg, Jost; Rebora, Nicola; Provenzale, Antonello

    2010-05-01

    Few existing stochastic precipitation downscaling methods take into account orography, even if orographic precipitation plays an important role in determining precipitation intensities at small scales, particularly in Alpine areas. In this work we present a modification of the RainFARM stochastic downscaling method (Rebora et al. 2006) in order to take into account orographic effects. The model is calibrated using an orographic signature obtained from a database of 450 pluviometric timeseries in North-Western Italy from 2004 to 2008. An out-of-sample verification is performed on data from 2009. We discuss the limitations and the applicability of this approach to downscaling of climate scenarios. References: N. Rebora, L. Ferraris, J. von Hardenberg, A. Provenzale, 2006: RainFARM: Rainfall Downscaling by a Filtered Autoregressive Model. J. Hydrometeorology, 7, 724-738.

  18. Silicide precipitation strengthened TiAl

    Energy Technology Data Exchange (ETDEWEB)

    Noda, T. [Special Steel Research Laboratory, Daido Steel Co. Ltd., 2-30 Daido-cho, Minami-ku, Nagoya 457 (Japan); Okabe, M. [Special Steel Research Laboratory, Daido Steel Co. Ltd., 2-30 Daido-cho, Minami-ku, Nagoya 457 (Japan); Isobe, S. [Special Steel Research Laboratory, Daido Steel Co. Ltd., 2-30 Daido-cho, Minami-ku, Nagoya 457 (Japan); Sayashi, M. [Materials Research Laboratory, Nissan Research Center, Nissan Motor Co. Ltd., 1 Natushima-cho, Yokosuka 237 (Japan)

    1995-02-28

    Precipitation of a titanium silicide Ti{sub 5}Si{sub 3} was found to be beneficial to improvement of the creep resistance of a fully lamellar Ti-48Al-1.5Cr cast alloy without the sacrifice of tensile properties. The addition of 0.26-0.65 mol% Si generates fine precipitates less than 200 nm in size during aging at 900 C for 5 h. The precipitates are effective obstacles to dislocation motion and raise the stress exponents of power law creep significantly. The specific creep strength of Si-containing alloys is better than that of a conventional Ni-base cast superalloy Inconel 713C at 800 C for 10000 h. ((orig.))

  19. Solute mixing regulates heterogeneity of mineral precipitation in porous media: Effect of Solute Mixing on Precipitation

    Energy Technology Data Exchange (ETDEWEB)

    Cil, Mehmet B.; Xie, Minwei; Packman, Aaron I.; Buscarnera, Giuseppe (NWU); (HKUST-- China)

    2017-07-04

    Synchrotron X-ray microtomography was used to track the spatiotemporal evolution of mineral precipitation and the consequent alteration of the pore structure. Column experiments were conducted by injecting CaCl2 and NaHCO3 solutions into granular porous media either as a premixed supersaturated solution (external mixing) or as separate solutions that mixed within the specimen (internal mixing). The two mixing modes produced distinct mineral growth patterns. While internal mixing promoted transverse heterogeneity with precipitation at the mixing zone, external mixing favored relatively homogeneous precipitation along the flow direction. The impact of precipitation on pore water flow and permeability was assessed via 3-D flow simulations, which indicated anisotropic permeability evolution for both mixing modes. Under both mixing modes, precipitation decreased the median pore size and increased the skewness of the pore size distribution. Such similar pore-scale evolution patterns suggest that the clogging of individual pores depends primarily on local supersaturation state and pore geometry.

  20. The precipitation of mucin by aluminium.

    Science.gov (United States)

    Exley, C

    1998-07-01

    The interactions of Al with a mucin glycopeptide have been studied. A number of specific reactions were identified the nature of which were dependent upon the Al chemistry in the hydration environment. In particular, Al was observed to precipitate mucin and it is suggested that this proceeded via the intercalation of the hydroxide within the hydrated macroreticular network of the mucin biopolymer. This precipitation of mucin was visible by eye and abolished the viscosity of native mucin. Viscometry indicated that Al was bound by mucin at low pH. At pH > 3 Al formed a low molecular weight complex with mucin which was hydrolytically stable and was not precipitated at pH up to 8. In an additional and competitive reaction Al was bound by mucin and the resultant mucin-Al complex was suggested to be the precursor to self-assembled mucin-Al spheres identified in solution, by photon correlation spectroscopy, and in precipitate using selective histochemistry. The majority of these spherical structures were of sub-micron diameter and, through their interaction with each other, were probably responsible for the observed pH-dependent peaks of mucin solution viscosity. The larger spheres, between 20 and 80 microns in diameter, were only identified in isolated mucin/Al precipitates and, being comparatively rare, were unlikely to have influenced solution viscosities. These large spheres were observed to act as possible nucleation sites for the flocculation of mucin/Al precipitate. Al at concentrations as low as 0.015 mM induced changes in the rheological properties of mucin. Considering the ubiquitous nature of mucin and the degree to which it is conserved within biota the interactions of Al with mucin may have wide ranging implications for biological systems.

  1. Calcite precipitation dominates the electrical signatures of zero valent iron columns under simulated field conditions.

    Science.gov (United States)

    Wu, Yuxin; Versteeg, Roelof; Slater, Lee; LaBrecque, Douglas

    2009-05-12

    Calcium carbonate is a secondary mineral precipitate influencing zero valent iron (ZVI) barrier reactivity and hydraulic performance. We conducted column experiments to investigate electrical signatures resulting from concurrent CaCO(3) and iron oxides precipitation under simulated field geochemical conditions. We identified CaCO(3) as a major mineral phase throughout the columns, with magnetite present primarily close to the influent based on XRD analysis. Electrical measurements revealed decreases in conductivity and polarization of both columns, suggesting that electrically insulating CaCO(3) dominates the electrical response despite the presence of electrically conductive iron oxides. SEM/EDX imaging suggests that the electrical signal reflects the geometrical arrangement of the mineral phases. CaCO(3) forms insulating films on ZVI/magnetite surfaces, restricting charge transfer between the pore electrolyte and ZVI particles, as well as across interconnected ZVI particles. As surface reactivity also depends on the ability of the surface to engage in redox reactions via charge transfer, electrical measurements may provide a minimally invasive technology for monitoring reactivity loss due to CaCO(3) precipitation. Comparison between laboratory and field data shows consistent changes in electrical signatures due to iron corrosion and secondary mineral precipitation.

  2. Calcite precipitation dominates the electrical signatures of zero valent iron columns under simulated field conditions

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Yuxin; Versteeg, R.; Slater, L.; LaBrecque, D.

    2009-06-01

    Calcium carbonate is a secondary mineral precipitate influencing zero valent iron (ZVI) barrier reactivity and hydraulic performance. We conducted column experiments to investigate electrical signatures resulting from concurrent CaCO{sub 3} and iron oxides precipitation under simulated field geochemical conditions. We identified CaCO{sub 3} as a major mineral phase throughout the columns, with magnetite present primarily close to the influent based on XRD analysis. Electrical measurements revealed decreases in conductivity and polarization of both columns, suggesting that electrically insulating CaCO{sub 3} dominates the electrical response despite the presence of electrically conductive iron oxides. SEM/EDX imaging suggests that the electrical signal reflects the geometrical arrangement of the mineral phases. CaCO{sub 3} forms insulating films on ZVI/magnetite surfaces, restricting charge transfer between the pore electrolyte and ZVI particles, as well as across interconnected ZVI particles. As surface reactivity also depends on the ability of the surface to engage in redox reactions via charge transfer, electrical measurements may provide a minimally invasive technology for monitoring reactivity loss due to CaCO{sub 3} precipitation. Comparison between laboratory and field data shows consistent changes in electrical signatures due to iron corrosion and secondary mineral precipitation.

  3. Structural Characterisation of ZnO Particles Obtained by the Emulsion Precipitation Method

    Directory of Open Access Journals (Sweden)

    Agnieszka Kołodziejczak-Radzimska

    2012-01-01

    Full Text Available Zinc oxide was obtained by precipitation in an emulsion system with zinc acetate used as a precursor of ZnO and potassium hydroxide or sodium hydroxide as a precipitating agent. The cyclohexane, as an organic phase, and a nonionic surfactant mixture were also used for preparation of the emulsion. By applying modifications of the ZnO precipitation process, such as changing the precipitating agent, composition of substrates, and the rate of substrate dosing, some interesting structures of ZnO particles were obtained. The morphology of the modified samples was analysed based on SEM (scanning electron microscope and TEM (transmission electron microscope images. Moreover the samples were characterised by determination of their dispersive properties using the noninvasive back scattering method (NIBS, adsorption parameters (BET, and crystalline structure (XRD. Thermogravimetric analysis (TG as well as infrared spectrophotometry (FT-IR was also applied. For selected samples their electrical properties (dielectric permittivity and electric conductivity were also measured. The zinc oxide obtained consisted of particles in the shapes of solids, ellipsoids, rods, and flakes, with size ranging from 164 to 2670 nm and showed well-developed surface area with values as high as 20 m2/g.

  4. Precipitation of metallic chromium during rapid cooling of Cr2O3 slags

    Directory of Open Access Journals (Sweden)

    J. Burja

    2017-01-01

    Full Text Available The slag systems of CaO-SiO2- Cr2O3 and Al2O3-CaO-MgO-SiO2- Cr2O3 were analyzed. These slag systems occur in the production of stainless steel and are important from the process metallurgy point of view. Synthetic slag samples with different chromium oxide content were prepared and melted. The melted slag samples where then rapidly cooled on large steel plates, so that the high temperature microstructure was preserved. The samples were analyzed by scanning electron microscopy (SEM and X-ray diffraction (XRD. The precipitation of different chromium oxide phases was studied, but most importantly the precipitation of metallic chromium was observed. These findings help us interpret industrial slag samples.

  5. Iron content of soils as a precipitation proxy

    Science.gov (United States)

    Dzombak, R.; Sheldon, N. D.

    2016-12-01

    Given that different iron phases form under different precipitation and drainage regimes, soil iron content could be used as a proxy for both volume and seasonality of precipitation. Constraining these factors is important for predicting future precipitation trends, especially for a warmer climate that will likely see more frequent extreme weather events. Specifically, using paleoprecipitation data from periods of higher temperatures and atmospheric CO2 concentrations helps inform models of future `greenhouse' climate. Forty-five modern samples from across the continental United States were analyzed, with MAP ranging from 200 to 1200 mm yr-1 and MAT ranging from 5 to 22°C. Soil types included Alfisols (N=15), Inceptisols (N=8), Mollisols (N=15), and Aridisols (N=7), and ranged from seasonally wet to well-drained. Analytical techniques included combustion-elemental analysis and organic carbon isotope analysis, a sequential iron extraction modified with a sodium hypochlorite step for the extraction of organic matter-bound iron, and the extraction of iron sulfides. The sequential extractions yield five different `pools' of iron found in sediment: crystalline iron oxides (e.g., goethite, hematite), magnetite, carbonate-bound, organic matter-bound, and labile/easily reducible iron minerals (e.g., ferrihydrite). Analysis by ICP-OES yielded a strong relationship between magnetite-bound iron and MAP, and fair relationships between the other iron pools and MAP. Individual soil orders tended to show stronger relationships to the iron pools than all soils analyzed together, potentially indicating the need for separate proxy relationships for each soil order. Pyrite concentrations were well below 1% by weight for these soils, suggesting that none of these soils has a long enough wet season to encourage its formation and that the presence vs. absence of pyrite in paleosols may be a useful proxy for soil moisture state. In contrast to some earlier work, no significant

  6. Precipitating Condensation Clouds in Substellar Atmospheres

    Science.gov (United States)

    Ackerman, Andrew S.; Marley, Mark S.; Gore, Warren J. (Technical Monitor)

    2000-01-01

    We present a method to calculate vertical profiles of particle size distributions in condensation clouds of giant planets and brown dwarfs. The method assumes a balance between turbulent diffusion and precipitation in horizontally uniform cloud decks. Calculations for the Jovian ammonia cloud are compared with previous methods. An adjustable parameter describing the efficiency of precipitation allows the new model to span the range of predictions from previous models. Calculations for the Jovian ammonia cloud are found to be consistent with observational constraints. Example calculations are provided for water, silicate, and iron clouds on brown dwarfs and on a cool extrasolar giant planet.

  7. High volume, multiple use, portable precipitator

    Science.gov (United States)

    Carlson, Duane C.

    2011-10-25

    A portable high air volume electrostatic collection precipitator for analyzing air is provided which is a relatively small, self-contained device. The device has a collection electrode adapted to carry a variety of collecting media. An air intake is provided such that air to be analyzed flows through an ionization section with a transversely positioned ionization wire to ionize analytes in the air, and then flows over the collection electrode where ionized analytes are collected. Air flow is maintained at but below turbulent flow, Ionizable constituents in the air are ionized, attracted to the collection electrode, and precipitated in the selected medium which can be removed for analysis.

  8. Analysis on Summer Precipitation Efficiency in Shenyang

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    [Objective] The research aimed to analyze summer precipitation efficiency in Shenyang.[Method] By using the method which estimated the cloud water resource,based on the vertical accumulated liquid water content which was observed by "QFW-1 dual-channel microwave radiometer" and the rain intensity data which had 1min interval and were inverted by "particle laser-based optical measurement" (Parsivel),the precipitation efficiency in Shenyang area during July-August,2007 was analyzed.[Result] When the rain inte...

  9. Atmospheric deposition of organic carbon via precipitation

    Science.gov (United States)

    Iavorivska, Lidiia; Boyer, Elizabeth W.; DeWalle, David R.

    2016-12-01

    Atmospheric deposition is the major pathway for removal of organic carbon (OC) from the atmosphere, affecting both atmospheric and landscape processes. Transfers of OC from the atmosphere to land occur as wet deposition (via precipitation) and as dry deposition (via surface settling of particles and gases). Despite current understanding of the significance of organic carbon inputs with precipitation to carbon budgets, transfers of organic matter between the atmosphere and land are not explicitly included in most carbon cycle models due to limited data, highlighting the need for further information. Studies regarding the abundance of OC in precipitation are relatively sparse, in part due to the fact that concentrations of organics in precipitation and their associated rates of atmospheric deposition are not routinely measured as a part of major deposition monitoring networks. Here, we provide a new data synthesis from 83 contemporary studies published in the peer reviewed literature where organic matter in precipitation was measured around the world. We compiled data regarding the concentrations of organic carbon in precipitation and associated rates of atmospheric deposition of organic carbon. We calculated summary statistics in a common set of units, providing insights into the magnitude and regional variability of OC in precipitation. A land to ocean gradient is evident in OC concentrations, with marine sites generally showing lower values than continental sites. Our synthesis highlights gaps in the data and challenges for data intercomparison. There is a need to concentrate sampling efforts in areas where anthropogenic OC emissions are on the rise (Asia, South America), as well as in remote sites suggesting background conditions, especially in Southern Hemisphere. It is also important to acquire more data for marine rainwater at various distances from the coast in order to assess a magnitude of carbon transfer between the land and the ocean. Our integration of

  10. Electrostatic Precipitation in Nearly Pure Gaseous Nitrogen

    Science.gov (United States)

    Buhler, Charles; Calle, Carlos; Clements, Sid; Cox, Bobby; Ritz, Mindy

    2008-01-01

    Electrostatic precipitation was performed in a nearly pure gaseous nitrogen system as a possible remedy for black dust contaminant from high pressure 6000 psi lines at the NASA Kennedy Space Center. The results of a prototype electrostatic precipitator that was built and tested using nitrogen gas at standard atmospheric pressures is presented. High voltage pulsed waveforms are generated using a rotating spark gap system at 30 Hz. A unique dust delivery system utilizing the Venturi effect was devised that supplies a given amount of dust per unit time for testing purposes.

  11. The Interaction of Dissolved H with Internally Oxidized Pd-Rh Alloys

    Energy Technology Data Exchange (ETDEWEB)

    Shanahan, K.L.

    2001-04-20

    Binary Pd-M alloys containing small amounts of readily oxidizable solute metals such as M equals Al, Mg, or Zr, can be internally oxidized to form essentially pure Pd matrices containing a second phase of nano-sized oxide precipitates. During internal oxidation Pd atoms are transported to the surface forming Pd nodules while vacancies are transported from the surface to the metal/oxide interface relieving the compressive stress which develops within the alloy due to the expanding metal oxide precipitates. The Pd alloys that have been studied contain that form very stable oxides.

  12. Correlative Microscopy of Alpha Prime Precipitation in Neutron-Irradiated Fe-Cr-Al Alloys

    Energy Technology Data Exchange (ETDEWEB)

    Briggs, Samuel A. [Univ. of Wisconsin, Madison, WI (United States)

    2016-12-01

    Fe-Cr-Al alloys are currently being considered for accident tolerant light water reactor fuel cladding applications due to their superior high temperature oxidation and corrosion resistance compared to Zr-based alloys. This work represents the current state-of-the-art on both techniques for analysis of α' precipitate microstructures and the processes and mechanisms governing its formation in neutron-irradiated Fe-Cr-Al alloys.

  13. Global cloud and precipitation chemistry and wet deposition: tropospheric model simulations with ECHAM5/MESSy1

    Directory of Open Access Journals (Sweden)

    J. Lelieveld

    2007-05-01

    Full Text Available The representation of cloud and precipitation chemistry and subsequent wet deposition of trace constituents in global atmospheric chemistry models is associated with large uncertainties. To improve the simulated trace gas distributions we apply the new submodel SCAV, which includes detailed cloud and precipitation chemistry and present results of the atmospheric chemistry general circulation model ECHAM5/MESSy1. A good agreement with observed wet deposition fluxes for species causing acid rain is obtained. The new scheme enables prognostic calculations of the pH of clouds and precipitation, and these results are also in accordance with observations. We address the influence of detailed cloud and precipitation chemistry on trace constituents based on sensitivity simulations. The results confirm previous results from regional scale and box models, and we extend the analysis to the role of aqueous phase chemistry on the global scale. Some species are directly affected through multiphase removal processes, and many also indirectly through changes in oxidant concentrations, which in turn have an impact on the species lifetime. While the overall effect on tropospheric ozone is relatively small (3 can reach ≈20%, and several important compounds (e.g., H2O2, HCHO are substantially depleted by clouds and precipitation.

  14. A kinetic model for corrosion and precipitation in non-isothermal LBE flow loop

    Science.gov (United States)

    He, By Xiaoyi; Li, Ning; Mineev, Mark

    2001-08-01

    A kinetic model was developed to estimate the corrosion/precipitation rate in a non-isothermal liquid lead-bismuth eutectic (LBE) flow loop. The model was based on solving the mass transport equation with the assumptions that convective transport dominates in the longitudinal flow direction and diffusion dominates in the transverse direction. The species concentration at wall is assumed to be determined either by the solubility of species in LBE in the absence of oxygen or by the reduction reaction of the protective oxide film when active oxygen control is applied. Analyses show that the corrosion/precipitation rate depends on the flow velocity, the species diffusion rate, the oxygen concentration in LBE, as well as the temperature distribution along a loop. Active oxygen control can significantly reduce the corrosion/precipitation of the structural materials. It is shown that the highest corrosion/precipitation does not necessarily locate at places with the highest/lowest temperature. For a material testing loop being constructed at the Los Alamos National Laboratory (LANL), the highest corrosion occurs at the end of the heater zone, while the highest precipitation occurs in the return flow in the recuperator.

  15. Global cloud and precipitation chemistry and wet deposition: tropospheric model simulations with ECHAM5/MESSy1

    Directory of Open Access Journals (Sweden)

    H. Tost

    2007-01-01

    Full Text Available The representation of cloud and precipitation chemistry and subsequent wet deposition of trace constituents in global atmospheric chemistry models is associated with large uncertainties. To improve the simulated trace gas distributions we apply the new submodel SCAV, which includes detailed cloud and precipitation chemistry and present results of the atmospheric chemistry general circulation model ECHAM5/MESSy1. A good agreement with observed wet deposition fluxes for species causing acid rain is obtained. The new scheme enables prognostic calculations of the pH of clouds and precipitation, and these results are also in accordance with observations. We address the influence of detailed cloud and precipitation chemistry on trace constituents based on sensitivity simulations. The results confirm previous results from regional scale and box models, and we extend the analysis to the role of aqueous phase chemistry on the global scale. Some species are directly affected through multiphase removal processes, and many also indirectly through changes in oxidant concentrations, which in turn have an impact on the species lifetime. While the overall effect on tropospheric ozone is relatively small (<10%, regional effects on O3 can reach ~20%, and several important compounds (e.g., H2O2, HCHO are substantially depleted by clouds and precipitation.

  16. Liquid Phase Plasma Synthesis of Iron Oxide/Carbon Composite as Dielectric Material for Capacitor

    Directory of Open Access Journals (Sweden)

    Heon Lee

    2014-01-01

    Full Text Available Iron oxide/carbon composite was synthesized using a liquid phase plasma process to be used as the electrode of supercapacitor. Spherical iron oxide nanoparticles with the size of 5~10 nm were dispersed uniformly on carbon powder surface. The specific capacitance of the composite increased with increasing quantity of iron oxide precipitate on the carbon powder up to a certain quantity. When the quantity of the iron oxide precipitate exceeds the threshold, however, the specific capacitance was rather reduced by the addition of precipitate. The iron oxide/carbon composite containing an optimum quantity (0.33 atomic % of iron oxide precipitate exhibited the smallest resistance and the largest initial resistance slope.

  17. The effect of molybdenum on niobium, titanium carbonitride precipitate evolution and grain refinement in high-temperature vacuum carburizing alloys

    Science.gov (United States)

    Enloe, Charles M.

    Existing commercial carburizing alloys can be processed at higher temperatures and shorter processing times utilizing vacuum carburizing due to the suppression of intergranular oxidation. To provide resistance to undesired grain coarsening at these elevated temperatures and associated reduction in fatigue performance, microalloyed steel variants have been developed which employ fine Ti- and Nb-carbonitrides to suppress grain growth. Grain coarsening resistance is believed to be limited by the coarsening resistance of the precipitates themselves at high temperature, so further alloy/processing developments to enhance microalloy precipitate coarsening resistance based on a greater mechanistic understanding of solute interaction with microalloy precipitates would be beneficial. Molybdenum is known to affect microalloy precipitate evolution during processing in ferrite and austenite, but a unified explanation of the role of Mo in precipitate evolution is still lacking. Accordingly, the effect of molybdenum on microalloy precipitate size and composition evolutions and the associated onset of abnormal grain growth in austenite was investigated in Mo-bearing and Mo-free, Nb,Ti-microalloyed SAE 4120 steels. Molybdenum additions of 0.30 wt pct to alloys containing Nb additions of 0.05 and 0.10 wt pct Nb delayed the onset of abnormal grain growth in hot-rolled alloys reheated and soaked at 1050 °C and 1100 °C. The coarsening rate of microalloy precipitates was also reduced in Mo-bearing alloys relative to Mo-free alloys during isothermal soaking at 1050 °C, 1100 °C, and 1150 °C. The observed microalloy precipitate coarsening rates exceeded those predicted by the Lifshitz-Slyozov-Wagner relation for volume-diffusion-controlled coarsening, which is attributed to an initial bimodal precipitate size distribution prior to reheating to elevated temperature. Heat-treatments of hot-rolled alloys (tempering and solutionizing) prior to reheating to elevated temperature in

  18. Characteristics of oxide scale formed on Cu-bearing austenitic stainless steel during early stages of high temperature oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Swaminathan, Srinivasan, E-mail: swaminathan@kist.re.kr [Metallurgy & Materials Group, Indira Gandhi Centre for Atomic Research, Kalpakkam 603 102 (India); High Temperature Energy Materials Research Center, Korea Institute of Science and Technology, Seongbuk-gu, Seoul 136 791 (Korea, Republic of); Krishna, Nanda Gopala [Metallurgy & Materials Group, Indira Gandhi Centre for Atomic Research, Kalpakkam 603 102 (India); Kim, Dong-Ik, E-mail: dongikkim@kist.re.kr [High Temperature Energy Materials Research Center, Korea Institute of Science and Technology, Seongbuk-gu, Seoul 136 791 (Korea, Republic of)

    2015-10-30

    Highlights: • Initial oxidation characteristics of Cu-bearing austenitic stainless steel at 650 °C were studied. • Strong segregation and oxidation of Mn and Nb were found in the entire oxide scale. • Surface coverage by metallic Cu-rich precipitates increases with exposure time. • Chemical heterogeneity of oxide scale revealed initial oxidation to be non-selective. • Fe-Cr and Mn-Cr mixed oxides were realized along with binary oxides of Fe, Cr and Mn. - Abstract: Oxide scale evolution on Cu-bearing austenitic stainless steel 304H at 650 °C, in ambient air, for exposure times 100, 300, 500 and 1000 h, has been investigated. Surface morphology and chemistry of the oxide scale grown were examined using SEM/EDX and XPS. The oxidation kinetics was determined by measuring the weight change using an electronic balance. At the initial stage, up to 500 h of exposure time, the oxidation rate was rapid due to surface reactions governed primarily by oxygen ingress, and then, dropped to a low rate after prolonged oxidation for 1000 h. The diffusion of reactants through the initially formed oxide scale limits the oxidation rate at longer times, thus, the progress of reaction followed the parabolic kinetics. The formed oxide scale was enriched significantly with segregation and subsequent oxidation of Nb, and finely dispersed metallic Cu particles. Within the time frame of oxidation, the oxide scale was mainly composed of mixed oxides such as FeCr{sub 2}O{sub 4} and MnCr{sub 2}O{sub 4} along with the binary oxides of Fe, Cr and Mn. Moreover, the precipitation fraction of Cu-rich particles on the oxide scale increased markedly with increase of exposure times. The chemical heterogeneity of oxide scale suggests that the oxidation occurred in a non-selective manner.

  19. Ethanol precipitation analysis of thymus histone

    NARCIS (Netherlands)

    Bijvoet, P.

    1957-01-01

    An analytical ethanol precipitation technique, similar to 's salting-out procedure, was used for the characterisation of whole thymus histone and the products obtained by preparative ethanol fractionation. The analysis was carried out at —5° C and pH 6.5. Whole histone prepared according to et al.,

  20. Precipitation properties observed during CHUVA Field Campaign

    Science.gov (United States)

    Morales, C.; Machado, L. A.; Angelis, C. F.; Silva Dias, M. A. F.; Fisch, G.; Carvalho, I. C.; Biscaro, T.; Sakuragi, J.; Neves, J. R.; Anselmo, E. M.; Lacerda, M.

    2012-04-01

    CHUVA is a Brazilian research program that seeks to depict the main precipitating systems observed in Brazil as a support for the Global Precipitation Measurement (GPM) mission. CHUVA is conducting a series of field campaigns in the time frame of 2010-2013 to sample raining systems that vary from maritime to continental regime and in polluted and clean environments. For this study, we will present initially the drop size distribution (DSD) variability observed in the field experiments of Alcantara (March/2010), Fortaleza (April/2011), Belém (June/2011) and Vale do Paraiba (November-December/2011). Secondly, with the help of the mobile X-Band and MRR-2, we will show the DSD differences observed on warm and cold phase clouds, and convective and stratiform precipitation. Finally, by employing the vertical electrical field and lightning measurements together with the weather radar, we will present the main vertical precipitation features observed in thunderstorms and non- thunderstorms, in addition to the different raining systems observed during the four field campaigns.

  1. Dilution physics modeling: Dissolution/precipitation chemistry

    Energy Technology Data Exchange (ETDEWEB)

    Onishi, Y.; Reid, H.C.; Trent, D.S.

    1995-09-01

    This report documents progress made to date on integrating dilution/precipitation chemistry and new physical models into the TEMPEST thermal-hydraulics computer code. Implementation of dissolution/precipitation chemistry models is necessary for predicting nonhomogeneous, time-dependent, physical/chemical behavior of tank wastes with and without a variety of possible engineered remediation and mitigation activities. Such behavior includes chemical reactions, gas retention, solids resuspension, solids dissolution and generation, solids settling/rising, and convective motion of physical and chemical species. Thus this model development is important from the standpoint of predicting the consequences of various engineered activities, such as mitigation by dilution, retrieval, or pretreatment, that can affect safe operations. The integration of a dissolution/precipitation chemistry module allows the various phase species concentrations to enter into the physical calculations that affect the TEMPEST hydrodynamic flow calculations. The yield strength model of non-Newtonian sludge correlates yield to a power function of solids concentration. Likewise, shear stress is concentration-dependent, and the dissolution/precipitation chemistry calculations develop the species concentration evolution that produces fluid flow resistance changes. Dilution of waste with pure water, molar concentrations of sodium hydroxide, and other chemical streams can be analyzed for the reactive species changes and hydrodynamic flow characteristics.

  2. Recent changes in precipitation extremes in Romania

    Directory of Open Access Journals (Sweden)

    Adina-Eliza CROITORU

    2014-11-01

    Full Text Available Changes in daily extreme precipitations have been identified in many studies conducted at local, regional or global scales. In Romania, only little research on this issue has been done so far. The present study is focused on the analysis of the trends in daily extreme precipitations indices over a period of 53 years (1961-2013. Data sets of daily precipitation recorded in 34 weather stations were analyzed. Among them, three are located in the Carpathian Mountains area and four are located on the Black Sea Coast. The main goal was to find changes in extreme daily precipitation using a set of 13 indices adopted from the core indices developed by ETCCDMI with appropriate modifications to suit to the studied area. The series of the indices as well as their trends were generated using RClimDex software. The trends have been calculated using the linear mean square method. The findings are similar to those obtained at the global and European continental scales and the most noteworthy are: increasing trends dominate for the most of the indices, but only about 25% of them are statistically significant at α=0.05; decreasing trends are more specific to southern area of the country; decreasing trends of  R0.1, CDD and CWD dominate for the great majority of locations; the spatial distribution of the significant slopes in the area is extremely irregular.

  3. Influence of sea ice on Arctic precipitation.

    Science.gov (United States)

    Kopec, Ben G; Feng, Xiahong; Michel, Fred A; Posmentier, Eric S

    2016-01-05

    Global climate is influenced by the Arctic hydrologic cycle, which is, in part, regulated by sea ice through its control on evaporation and precipitation. However, the quantitative link between precipitation and sea ice extent is poorly constrained. Here we present observational evidence for the response of precipitation to sea ice reduction and assess the sensitivity of the response. Changes in the proportion of moisture sourced from the Arctic with sea ice change in the Canadian Arctic and Greenland Sea regions over the past two decades are inferred from annually averaged deuterium excess (d-excess) measurements from six sites. Other influences on the Arctic hydrologic cycle, such as the strength of meridional transport, are assessed using the North Atlantic Oscillation index. We find that the independent, direct effect of sea ice on the increase of the percentage of Arctic sourced moisture (or Arctic moisture proportion, AMP) is 18.2 ± 4.6% and 10.8 ± 3.6%/100,000 km(2) sea ice lost for each region, respectively, corresponding to increases of 10.9 ± 2.8% and 2.7 ± 1.1%/1 °C of warming in the vapor source regions. The moisture source changes likely result in increases of precipitation and changes in energy balance, creating significant uncertainty for climate predictions.

  4. Diabetic Ketoacidosis: Pattern of Precipitating Causes

    Directory of Open Access Journals (Sweden)

    Ashraf Uddin Ahmed

    2014-05-01

    Full Text Available Background: Diabetic ketoacidosis (DKA is one of the most common acute complications of diabetes mellitus (DM. DKA is a recognised presenting feature of type 1 DM, but it commonly complicates previously diagnosed diabetic patients of all types, specially if they get infection or discontinue treatment. Objective: To describe the precipitating causes of DKA. Materials and Methods: This cross-sectional study was done from September to November, 2010 in Bangladesh Institute of Research & Rehabilitation in Diabetes, Endocrine and Metabolic Disorders (BIRDEM. Diagnosed DKA cases were evaluated clinically and by laboratory investigations for identification of precipitating causes. Results: Out of 50 patients, 28 were female. Mean age was 38.3 years. Forty patients (80% were known diabetics and 10 (20% were detected diabetic first time during this admission. Severe DKA cases were less common. Infection (20, 40% was the commonest precipitating cause followed by noncompliance (14, 28%. In 7 (14% cases no cause could be identified. Other less common causes included acute myocardial infarction, acute pancreatitis, stroke and surgery. Conclusion: Infection and noncompliance were the major precipitants of DKA. So, it is assumed that many DKA cases might be prevented by proper counselling regarding adherence to medication and sick days’ management.

  5. Precipitation and Solubility of Calcium Hydrogenurate Hexahydrate.

    Science.gov (United States)

    Babić-Ivančić, V; Füredi-Milhofer, H; Brničević, N; Marković, M

    1992-01-01

    Solid phases formed in the quaternary system: uric acid-calcium hydroxide -hydrochloric acid-water aged for 2 months at 310 K were studied to determine conditions for calcium hydrogenurate hexahydrate, Ca(C5H3N4O)2 · 6H2O precipitation. The precipitates were identified by chemical and thermogravimetric analyses, x-ray powder diffraction, infrared spectroscopy, light microscopy, and scanning electron microscopy. In the precipitation diagram the concentration region in which calcium hydrogenurate hexahydrate precipitated as a single solid phase was established. The solubility of calcium hydrogenurate hexahydrate was investigated in the pH range from 6.2 to 10.1 at different temperatures. The total soluble and ionic concentration of calcium (atomic absorption spectroscopy and Ca-selective electrode), total urate concentration (spectrophotometry), and pH were determined in equilibrated solutions. The data are presented in the form of tables and chemical potential diagrams. By using these data the thermodynamic solubility products of calcium hydrogenurate hexahydrate, Ks = a(Ca(2+)) · a(2)(C5H3N4O3(-)), were determined: [Formula: see text]The formation of calcium hydrogenurate hexahydrate crystals in urinary tract of patients with pathologically high concentrations of calcium and urates (hypercalciuria and hyperuricosiuria) is possible.

  6. Separation of aromatic precipitates from simulated high level radioactive waste by hydrolysis, evaporation and liquid-liquid extraction

    Energy Technology Data Exchange (ETDEWEB)

    Young, S.R.; Shah, H.B.; Carter, J.T.

    1991-01-01

    The Defense Waste Processing Facility (DWPF) at the SRS will be the United States' first facility to process High Level radioactive Waste (HLW) into a borosilicate glass matrix. The removal of aromatic precipitates by hydrolysis, evaporation and liquid-liquid extraction will be a key step in the processing of the HLW. This step, titled the Precipitate Hydrolysis Process, has been demonstrated by the Savannah River Laboratory with the Precipitate Hydrolysis Experimental Facility (PHEF). The mission of the PHEF is to demonstrate processing of simulated high level radioactive waste which contains tetraphenylborate precipitates and nitrite. Reduction of nitrite by hydroxylamine nitrate and hydrolysis of the tetraphenylborate by formic acid is discussed. Gaseous production, which is primarily benzene, nitrous oxide and carbon dioxide, has been quantified. Production of high-boiling organic compounds and the accumulation of these organic compounds within the process are addressed.

  7. Separation of aromatic precipitates from simulated high level radioactive waste by hydrolysis, evaporation and liquid-liquid extraction

    Energy Technology Data Exchange (ETDEWEB)

    Young, S.R.; Shah, H.B.; Carter, J.T.

    1991-12-31

    The Defense Waste Processing Facility (DWPF) at the SRS will be the United States` first facility to process High Level radioactive Waste (HLW) into a borosilicate glass matrix. The removal of aromatic precipitates by hydrolysis, evaporation and liquid-liquid extraction will be a key step in the processing of the HLW. This step, titled the Precipitate Hydrolysis Process, has been demonstrated by the Savannah River Laboratory with the Precipitate Hydrolysis Experimental Facility (PHEF). The mission of the PHEF is to demonstrate processing of simulated high level radioactive waste which contains tetraphenylborate precipitates and nitrite. Reduction of nitrite by hydroxylamine nitrate and hydrolysis of the tetraphenylborate by formic acid is discussed. Gaseous production, which is primarily benzene, nitrous oxide and carbon dioxide, has been quantified. Production of high-boiling organic compounds and the accumulation of these organic compounds within the process are addressed.

  8. Experimental observations of boric acid precipitation scenarios

    Energy Technology Data Exchange (ETDEWEB)

    Vaghetto, R., E-mail: r.vaghetto@tamu.edu; Childs, M., E-mail: masonchilds@tamu.edu; Jones, P., E-mail: pgjones87@tamu.edu; Lee, S., E-mail: sayalee@tamu.edu; Kee, E., E-mail: erniekee@gmail.com; Hassan, Y.A., E-mail: y-hassan@tamu.edu

    2017-02-15

    During a Loss of Coolant Accident (LOCA) in Light Water Reactors (LWR), borated water is injected into the core through the safety injection system. The continuous vaporization of the water from the core may increase the concentration of boric acid in the core that, under certain conditions may reach the solubility limit and precipitate. This includes scenarios where the liquid water supply to the core is affected by possible blockages due to debris accumulation. Questions have been raised on the effects of the precipitate in the core on the flow behavior, including the possibility of additional blockages produced by precipitate accumulation. A simple experimental facility was constructed to perform experimental observations of the behavior of borated water under the combined effects of the boiling and the boric acid precipitation (BAP). The facility consists of a transparent polycarbonate vertical pipe where forty-five heated rods have been installed to supply the power to the water to reach the saturation temperature, and maintain a desired boil-off rate. The layout and geometry of the experimental apparatus were conceived to emulate a simplified core of a Pressurized Water Reactor (PWR). Experimental observations have been conducted under two different conditions. Preliminary tests were conducted to observe the behavior of the water and the boric acid precipitate during a boil-off scenario without borated water addition (decreasing water level). During the main test runs, borated water was constantly injected from the top of the test section to maintain a constant mixture level in the test section. Both tests assumed no flow from the bottom of the test section which may be the case of PWR LOCA scenarios in presence of debris-generated core blockage. The observations performed with a set of cameras installed around the test section showed interesting effects of the vapor bubbles on the boric acid precipitate migration and accumulation in the test section. The

  9. 含铜半导体氧化物的光催化应用进展%Photocatalytic research progress of Cu-based semiconductor oxides

    Institute of Scientific and Technical Information of China (English)

    康园丽; 王桂赟; 刘宗园; 王延吉

    2012-01-01

    It is a hot point in material research area,that semiconductive materials are used to split water for hydrogen evolution and degrade pollutants,in recent decades.From the point of the development range of photocatalyst material,the basic properties,preparation method and the photocatalytic application of the containing copper semiconductor oxides are summarized.The oxides discussed in this paper include two kinds of oxides,the first type containing Cu(Ⅰ) named cuprous oxide and delafossite oxides,and second type containing Cu(Ⅱ) named copper oxide and spinelle composite oxides.Composing Cu-based semiconductor oxides with n-type semiconductor material to obtain p-n heterogeneity composite oxides should be a promising research direction.%应用半导体材料光催化降解污染物和光催化分解水制氢是近几十年来的材料研究热点之一。从拓展光催化材料种类的角度出发,本文对含铜半导体氧化物的基本性质、制备方法及其在光催化方面的应用情况进行了综述。所涉及的氧化物包括含一价铜的氧化亚铜和铜铁矿类复合氧化物,以及含二价铜的氧化铜和尖晶石类复合氧化物。指出将含铜p型半导体氧化物与n型半导体材料复合,制备p-n异质型复合氧化物是有前途的研发方向。

  10. in situ Calcite Precipitation for Contaminant Immobilization

    Energy Technology Data Exchange (ETDEWEB)

    Yoshiko Fujita; Robert W. Smith

    2009-08-01

    in situ Calcite Precipitation for Contaminant Immobilization Yoshiko Fujita (Yoshiko.fujita@inl.gov) (Idaho National Laboratory, Idaho Falls, Idaho, USA) Robert W. Smith (University of Idaho-Idaho Falls, Idaho Falls, Idaho, USA) Subsurface radionuclide and trace metal contaminants throughout the U.S. Department of Energy (DOE) complex pose one of DOE’s greatest challenges for long-term stewardship. One promising stabilization mechanism for divalent trace ions, such as the short-lived radionuclide strontium-90, is co-precipitation in calcite. Calcite, a common mineral in the arid western U.S., can form solid solutions with trace metals. The rate of trace metal incorporation is susceptible to manipulation using either abiotic or biotic means. We have previously demonstrated that increasing the calcite precipitation rate by stimulating the activity of urea hydrolyzing microorganisms can result in significantly enhanced Sr uptake. Urea hydrolysis causes the acceleration of calcium carbonate precipitation (and trace metal co-precipitation) by increasing pH and alkalinity, and also by liberating the reactive cations from the aquifer matrix via exchange reactions involving the ammonium ion derived from urea: H2NCONH2 + 3H2O ? 2NH4+ + HCO3- + OH- urea hydrolysis >X:2Ca + 2NH4+ ? 2>X:NH4 + Ca2+ ion exchange Ca2+ + HCO3- + OH- ? CaCO3(s) + H2O calcite precipitation where >X: is a cation exchange site on the aquifer matrix. This contaminant immobilization approach has several attractive features. Urea hydrolysis is catalyzed by the urease enzyme, which is produced by many indigenous subsurface microorganisms. Addition of foreign microbes is unnecessary. In turn the involvement of the native microbes and the consequent in situ generation of reactive components in the aqueous phase (e.g., carbonate and Ca or Sr) can allow dissemination of the reaction over a larger volume and/or farther away from an amendment injection point, as compared to direct addition of the reactants at

  11. Synthesis and functionalisation of metal and metal oxide nanoparticles for theranostics

    OpenAIRE

    2013-01-01

    Metal and metal oxide nanoparticles including calcium oxide, gold, and superparamagnetic iron oxide nanoparticles (SPIOs) were synthesised using a range of techniques including reduction, co-precipitation and spinning disc technology. SPIOs were primarily synthesised via a co-precipitation method using iron (II) chloride, iron (III) chloride and ammonia; a spinning disc reactor and gaseous ammonia were trialled successfully for scale up, producing spherical particles of 10-40 nm in diameter a...

  12. Bacteria attenuation by iron electrocoagulation governed by interactions between bacterial phosphate groups and Fe(III) precipitates

    NARCIS (Netherlands)

    Delaire, Caroline; van Genuchten, Case M.; Amrose, Susan E.; Gadgil, Ashok J.

    2016-01-01

    Iron electrocoagulation (Fe-EC) is a low-cost process in which Fe(II) generated from an Fe(0) anode reacts with dissolved O2 to form (1) Fe(III) precipitates with an affinity for bacterial cell walls and (2) bactericidal reactive oxidants. Previous work suggests that Fe-EC is a promising treatment o

  13. A global satellite-assisted precipitation climatology

    Science.gov (United States)

    Funk, C.; Verdin, A.; Michaelsen, J.; Peterson, P.; Pedreros, D.; Husak, G.

    2015-10-01

    Accurate representations of mean climate conditions, especially in areas of complex terrain, are an important part of environmental monitoring systems. As high-resolution satellite monitoring information accumulates with the passage of time, it can be increasingly useful in efforts to better characterize the earth's mean climatology. Current state-of-the-science products rely on complex and sometimes unreliable relationships between elevation and station-based precipitation records, which can result in poor performance in food and water insecure regions with sparse observation networks. These vulnerable areas (like Ethiopia, Afghanistan, or Haiti) are often the critical regions for humanitarian drought monitoring. Here, we show that long period of record geo-synchronous and polar-orbiting satellite observations provide a unique new resource for producing high-resolution (0.05°) global precipitation climatologies that perform reasonably well in data-sparse regions. Traditionally, global climatologies have been produced by combining station observations and physiographic predictors like latitude, longitude, elevation, and slope. While such approaches can work well, especially in areas with reasonably dense observation networks, the fundamental relationship between physiographic variables and the target climate variables can often be indirect and spatially complex. Infrared and microwave satellite observations, on the other hand, directly monitor the earth's energy emissions. These emissions often correspond physically with the location and intensity of precipitation. We show that these relationships provide a good basis for building global climatologies. We also introduce a new geospatial modeling approach based on moving window regressions and inverse distance weighting interpolation. This approach combines satellite fields, gridded physiographic indicators, and in situ climate normals. The resulting global 0.05° monthly precipitation climatology, the Climate

  14. A global satellite assisted precipitation climatology

    Directory of Open Access Journals (Sweden)

    C. Funk

    2015-05-01

    Full Text Available Accurate representations of mean climate conditions, especially in areas of complex terrain, are an important part of environmental monitoring systems. As high-resolution satellite monitoring information accumulates with the passage of time, it can be increasingly useful in efforts to better characterize the earth's mean climatology. Current state-of-the-science products rely on complex and sometimes unreliable relationships between elevation and station-based precipitation records, which can result in poor performance in food and water insecure regions with sparse observation networks. These vulnerable areas (like Ethiopia, Afghanistan, or Haiti are often the critical regions for humanitarian drought monitoring. Here, we show that long period of record geo-synchronous and polar-orbiting satellite observations provide a unique new resource for producing high resolution (0.05° global precipitation climatologies that perform reasonably well in data sparse regions. Traditionally, global climatologies have been produced by combining station observations and physiographic predictors like latitude, longitude, elevation, and slope. While such approaches can work well, especially in areas with reasonably dense observation networks, the fundamental relationship between physiographic variables and the target climate variables can often be indirect and spatially complex. Infrared and microwave satellite observations, on the other hand, directly monitor the earth's energy emissions. These emissions often correspond physically with the location and intensity of precipitation. We show that these relationships provide a good basis for building global climatologies. We also introduce a new geospatial modeling approach based on moving window regressions and inverse distance weighting interpolation. This approach combines satellite fields, gridded physiographic indicators, and in situ climate normals. The resulting global 0.05° monthly precipitation climatology

  15. Quantification of asphaltene precipitation by scaling equation

    Science.gov (United States)

    Janier, Josefina Barnachea; Jalil, Mohamad Afzal B. Abd.; Samin, Mohamad Izhar B. Mohd; Karim, Samsul Ariffin B. A.

    2015-02-01

    Asphaltene precipitation from crude oil is one of the issues for the oil industry. The deposition of asphaltene occurs during production, transportation and separating process. The injection of carbon dioxide (CO2) during enhance oil recovery (EOR) is believed to contribute much to the precipitation of asphaltene. Precipitation can be affected by the changes in temperature and pressure on the crude oil however, reduction in pressure contribute much to the instability of asphaltene as compared to temperature. This paper discussed the quantification of precipitated asphaltene in crude oil at different high pressures and at constant temperature. The derived scaling equation was based on the reservoir condition with variation in the amount of carbon dioxide (CO2) mixed with Dulang a light crude oil sample used in the experiment towards the stability of asphaltene. A FluidEval PVT cell with Solid Detection System (SDS) was the instrument used to gain experimental knowledge on the behavior of fluid at reservoir conditions. Two conditions were followed in the conduct of the experiment. Firstly, a 45cc light crude oil was mixed with 18cc (40%) of CO2 and secondly, the same amount of crude oil sample was mixed with 27cc (60%) of CO2. Results showed that for a 45cc crude oil sample combined with 18cc (40%) of CO2 gas indicated a saturation pressure of 1498.37psi and asphaltene onset point was 1620psi. Then for the same amount of crude oil combined with 27cc (60%) of CO2, the saturation pressure was 2046.502psi and asphaltene onset point was 2230psi. The derivation of the scaling equation considered reservoir temperature, pressure, bubble point pressure, mole percent of the precipitant the injected gas CO2, and the gas molecular weight. The scaled equation resulted to a third order polynomial that can be used to quantify the amount of asphaltene in crude oil.

  16. A global satellite assisted precipitation climatology

    Science.gov (United States)

    Funk, Christopher C.; Verdin, Andrew P.; Michaelsen, Joel C.; Pedreros, Diego; Husak, Gregory J.; Peterson, P.

    2015-01-01

    Accurate representations of mean climate conditions, especially in areas of complex terrain, are an important part of environmental monitoring systems. As high-resolution satellite monitoring information accumulates with the passage of time, it can be increasingly useful in efforts to better characterize the earth's mean climatology. Current state-of-the-science products rely on complex and sometimes unreliable relationships between elevation and station-based precipitation records, which can result in poor performance in food and water insecure regions with sparse observation networks. These vulnerable areas (like Ethiopia, Afghanistan, or Haiti) are often the critical regions for humanitarian drought monitoring. Here, we show that long period of record geo-synchronous and polar-orbiting satellite observations provide a unique new resource for producing high resolution (0.05°) global precipitation climatologies that perform reasonably well in data sparse regions. Traditionally, global climatologies have been produced by combining station observations and physiographic predictors like latitude, longitude, elevation, and slope. While such approaches can work well, especially in areas with reasonably dense observation networks, the fundamental relationship between physiographic variables and the target climate variables can often be indirect and spatially complex. Infrared and microwave satellite observations, on the other hand, directly monitor the earth's energy emissions. These emissions often correspond physically with the location and intensity of precipitation. We show that these relationships provide a good basis for building global climatologies. We also introduce a new geospatial modeling approach based on moving window regressions and inverse distance weighting interpolation. This approach combines satellite fields, gridded physiographic indicators, and in situ climate normals. The resulting global 0.05° monthly precipitation climatology, the Climate

  17. RNA oxidation

    DEFF Research Database (Denmark)

    Kjaer, L. K.; Cejvanovic, V.; Henriken, T.

    2015-01-01

    in diabetes resulting from the diabetic state, a dysfunction that includes increased production of hydrogen peroxide. We suggest that the intracellular RNA oxidation is compartmentalized from the traditional biomarkers in the extracellular compartment, and therefore provides independent prognostic value...... diabetes. In agreement with our previous finding, DNA oxidation did not show any prognostic value. RNA oxidation represents oxidative stress intracellularly, presumably predominantly in the cytosol. The mechanism of RNA oxidation is not clear, but hypothesized to result from mitochondrial dysfunction...

  18. Recovery of yttrium from fluorescent powder of cathode ray tube, CRT: Zn removal by sulphide precipitation

    Energy Technology Data Exchange (ETDEWEB)

    Innocenzi, Valentina, E-mail: valentina.innocenzi1@univaq.it [Department of Industrial Engineering and Information and Economy, University of L’Aquila, Via Giovanni Gronchi n.18, Nucleo Ind.le di Pile, 67100 L’Aquila (Italy); De Michelis, Ida; Ferella, Francesco [Department of Industrial Engineering and Information and Economy, University of L’Aquila, Via Giovanni Gronchi n.18, Nucleo Ind.le di Pile, 67100 L’Aquila (Italy); Beolchini, Francesca [Department of Marine Sciences, Polytechnic Institute of Marche, Via Brecce Bianche, 60131 Ancona (Italy); Kopacek, Bernd [SAT, Austrian Society for Systems Engineering and Automation, Gurkasse 43/2, A-1140 Vienna (Austria); Vegliò, Francesco [Department of Industrial Engineering and Information and Economy, University of L’Aquila, Via Giovanni Gronchi n.18, Nucleo Ind.le di Pile, 67100 L’Aquila (Italy)

    2013-11-15

    Highlights: • Treatment of fluorescent powder of CRT waste. • Factorial experimental designs to study acid leaching of fluorescent powder and the purification of leach liquors. • Recover of yttrium by precipitation using oxalic acid. • Suitable flowsheet to recover yttrium from fluorescent powder. - Abstract: This work is focused on the recovery of yttrium and zinc from fluorescent powder of cathode ray tube (CRT). Metals are extracted by sulphuric acid in the presence of hydrogen peroxide. Leaching tests are carried out according to a 2{sup 2} full factorial plan and the highest extraction yields for yttrium and zinc equal to 100% are observed under the following conditions: 3 M of sulphuric acid, 10% v/v of H{sub 2}O{sub 2} concentrated solution at 30% v/v, 10% w/w pulp density, 70 °C and 3 h of reaction. Two series of precipitation tests for zinc are carried out: a 2{sup 2} full factorial design and a completely randomized factorial design. In these series the factors investigated are pH of solution during the precipitation and the amount of sodium sulphide added to precipitate zinc sulphide. The data of these tests are used to describe two empirical mathematical models for zinc and yttrium precipitation yields by regression analysis. The highest precipitation yields for zinc are obtained under the following conditions: pH equal to 2–2.5% and 10–12% v/v of Na{sub 2}S concentrated solution at 10% w/v. In these conditions the coprecipitation of yttrium is of 15–20%. Finally further yttrium precipitation experiments by oxalic acid on the residual solutions, after removing of zinc, show that yttrium could be recovered and calcined to obtain the final product as yttrium oxide. The achieved results allow to propose a CRT recycling process based on leaching of fluorescent powder from cathode ray tube and recovery of yttrium oxide after removing of zinc by precipitation. The final recovery of yttrium is 75–80%.

  19. Comparison of the Oxidation Rates of Some New Copper Alloys

    Science.gov (United States)

    Ogbuji, Linus U. J. Thomas; Humphrey, Donald L.

    2002-01-01

    Copper alloys were studied for oxidation resistance and mechanisms between 550 and 700 C, in reduced-oxygen environments expected in rocket engines, and their oxidation behaviors compared to that of pure copper. They included two dispersion-strengthened alloys (precipitation-strengthened and oxide-dispersion strengthened, respectively) and one solution-strengthened alloy. In all cases the main reaction was oxidation of Cu into Cu2O and CuO. The dispersion-strengthened alloys were superior to both Cu and the solution-strengthened alloy in oxidation resistance. However, factors retarding oxidation rates seemed to be different for the two dispersion-strengthened alloys.

  20. Linkages between Icelandic Low position and SE Greenland winter precipitation

    Science.gov (United States)

    Berdahl, M.; Rennermalm, A. K.; Hammann, A. C.; Mioduszewski, J.; Hameed, S.; Tedesco, M.; Stroeve, J. C.; Mote, T. L.

    2015-12-01

    Greenland's largest flux of precipitation occurs in its Southeast (SE) region. An understanding of the mechanisms controlling precipitation in this region is lacking despite its disproportionate importance in the mass balance of Greenland and the consequent contributions to sea level rise. We use weather station data from the Danish Meteorological Institute to reveal the governing influences on precipitation in SE Greenland during the winter and fall. We find that precipitation in the fall is significantly correlated to the longitude of the Icelandic Low and the NAO. Winter precipitation is correlated with the strength and longitude of the Icelandic Low, as well as the NAO. We show that in years of extreme high precipitation, onshore winds dominate, thereby advecting more moisture inland. In low precipitation years, winds are more westerly, approaching the stations from land. Understanding the controls of SE Greenland precipitation will help us predict how future precipitation in this key region may change in a warming climate.

  1. Effects of copper(II) and copper oxides on THMs formation in copper pipe.

    Science.gov (United States)

    Li, Bo; Qu, Jiuhui; Liu, Huijuan; Hu, Chengzhi

    2007-08-01

    Little is known about how the growth of trihalomethanes (THMs) in drinking water is affected in copper pipe. The formation of THMs and chlorine consumption in copper pipe under stagnant flow conditions were investigated. Experiments for the same water held in glass bottles were performed for comparison. Results showed that although THMs levels firstly increased in the presence of chlorine in copper pipe, faster decay of chlorine as compared to the glass bottle affected the rate of THMs formation. The analysis of water phase was supplemented by surface analysis of corrosion scales using X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM) and energy dispersive spectroscopy (EDX). The results showed the scales on the pipe surface mainly consisted of Cu(2)O, CuO and Cu(OH)(2) or CuCO(3). Designed experiments confirmed that the fast depletion of chlorine in copper pipe was mainly due to effect of Cu(2)O, CuO in corrosion scales on copper pipe. Although copper(II) and copper oxides showed effect on THMs formation, the rapid consumption of chlorine due to copper oxide made THM levels lower than that in glass bottles after 4h. The transformations of CF, DCBM and CDBM to BF were accelerated in the presence of copper(II), cupric oxide and cuprous oxide. The effect of pH on THMs formation was influenced by effect of pH on corrosion of copper pipe. When pH was below 7, THMs levels in copper pipe was higher as compared to glass bottle, but lower when pH was above 7.

  2. Relative importance of precipitation frequency and intensity in inter-annual variation of precipitation in Singapore during 1980-2013

    Science.gov (United States)

    Li, Xin; Babovic, Vladan

    2017-04-01

    Observed studies on inter-annual variation of precipitation provide insight into the response of precipitation to anthropogenic climate change and natural climate variability. Inter-annual variation of precipitation results from the concurrent variations of precipitation frequency and intensity, understanding of the relative importance of frequency and intensity in the variability of precipitation can help fathom its changing properties. Investigation of the long-term changes of precipitation schemes has been extensively carried out in many regions across the world, however, detailed studies of the relative importance of precipitation frequency and intensity in inter-annual variation of precipitation are still limited, especially in the tropics. Therefore, this study presents a comprehensive framework to investigate the inter-annual variation of precipitation and the dominance of precipitation frequency and intensity in a tropical urban city-state, Singapore, based on long-term (1980-2013) daily precipitation series from 22 rain gauges. First, an iterative Mann-Kendall trend test method is applied to detect long-term trends in precipitation total, frequency and intensity at both annual and seasonal time scales. Then, the relative importance of precipitation frequency and intensity in inducing the inter-annual variation of wet-day precipitation total is analyzed using a dominance analysis method based on linear regression. The results show statistically significant upward trends in wet-day precipitation total, frequency and intensity at annual time scale, however, these trends are not evident during the monsoon seasons. The inter-annual variation of wet-day precipitation is mainly dominated by precipitation intensity for most of the stations at annual time scale and during the Northeast monsoon season. However, during the Southwest monsoon season, the inter-annual variation of wet-day precipitation is mainly dominated by precipitation frequency. These results have

  3. Precipitating and non-precipitating monoclonal antibodies against chicken avidin. Significance of epitope density.

    Science.gov (United States)

    Krohn, K; Ashorn, R; Ashorn, P; Kulomaa, M

    1987-01-01

    1. Monoclonal antibodies, generated against chicken avidin, were characterized in Ouchterlony's immunodiffusion. 2. Of the nine antibodies three were non-precipitable but six could form clear visible precipitation lines with egg-white avidin in agarose gel. 3. The latter six antibodies could be divided into two groups according to their reactive pattern in immunodiffusion. 4. Antibodies belonging to the first group precipitated both dimeric as well as tetrameric avidin molecules, while those of the second group precipitated only the tetrameric avidin molecules. 5. The relevance of these results to the structure of avidin as well as possibilities to use monoclonal antibodies and the immunodiffusion technique to compare the structure of avidin induced by different factors are discussed.

  4. Correlating GRACE with Standardized Precipitation Indices and Precipitation Gauges for the High Plains Aquifer

    Science.gov (United States)

    Miller, K. A.; Clancy, K.

    2016-12-01

    The NASA and German Aerospace Center Gravity Recovery and Climate Experiment (GRACE) detects monthly changes in the gravity of the earth assumed to be water storage using the distance between two satellites, GRACE A and GRACE B, as a phase change. We will use level 3 GRACE Tellus data from the NASA Jet Propulsion Laboratory Physical Oceanography Distributed Active Archive Center (PO.DAAC). The data have a resolution of 9 km2 and are available for 2002 to 2015. We examine GRACE data for the High Plains aquifer (Texas, Oklahoma, Wyoming, Nebraska, Kansas, New Mexico, Colorado and South Dakota) and compare changes to monthly averaged precipitation gauges, standardized precipitation indices for one, three, six, and twelve-months. We hypothesize that GRACE data will correlate best with 1) three-month standardized precipitation indices; 2) regions with natural land cover; 3) and in years where precipitation is at or above average.

  5. Optical and Morphological Characterization of Sonochemically Assisted Europium Doped Copper (I) Oxide Nanostructures

    Science.gov (United States)

    Cosico, J. A. M.; Ruales, P. K.; Marquez, M. C.

    2017-06-01

    In the age where application of nanotechnology in our society has proven to be eminent, different routes of synthesizing nanoparticles have emerged. In this study nanoparticles of cuprous oxide (Cu2O) doped with different amounts of europium was prepared by using solution precursor route approach with the aid of ultrasonic sound. Copper sulphate and europium (III) nitrate pentahydrate was used as source for copper ions and europium ions respectively. X-ray diffraction (XRD) and Fourier Transform Infrared spectroscopy (FTIR) were used to elucidate the cubic crystal structure and organic impurities present on Cu2Onanoparticles. UV-Vis spectroscopy was used to determine the absorption spectrum of the nanoparticles in the wavelength range of 400nm to 700nm. The bandgap of the undoped and doped Cu2O were found to fall between 2.1eV - 2.3eV. Scanning Electron Microscopy (SEM) coupled with energy dispersive x-ray was used to observe the dendritic and rodlike morphology and the presence of europium in the synthesized Cu2O nanoparticles. The observed effect on the absorbance of Cu2O upon adding Eu and a facile way of synthesizing Cu2O nanoparticles could bring a positive impact on the production of functional devices for optoelectronic and energy applications.

  6. Extreme Precipitation and High-Impact Landslides

    Science.gov (United States)

    Kirschbaum, Dalia; Adler, Robert; Huffman, George; Peters-Lidard, Christa

    2012-01-01

    It is well known that extreme or prolonged rainfall is the dominant trigger of landslides; however, there remain large uncertainties in characterizing the distribution of these hazards and meteorological triggers at the global scale. Researchers have evaluated the spatiotemporal distribution of extreme rainfall and landslides at local and regional scale primarily using in situ data, yet few studies have mapped rainfall-triggered landslide distribution globally due to the dearth of landslide data and consistent precipitation information. This research uses a newly developed Global Landslide Catalog (GLC) and a 13-year satellite-based precipitation record from Tropical Rainfall Measuring Mission (TRMM) data. For the first time, these two unique products provide the foundation to quantitatively evaluate the co-occurence of precipitation and rainfall-triggered landslides globally. The GLC, available from 2007 to the present, contains information on reported rainfall-triggered landslide events around the world using online media reports, disaster databases, etc. When evaluating this database, we observed that 2010 had a large number of high-impact landslide events relative to previous years. This study considers how variations in extreme and prolonged satellite-based rainfall are related to the distribution of landslides over the same time scales for three active landslide areas: Central America, the Himalayan Arc, and central-eastern China. Several test statistics confirm that TRMM rainfall generally scales with the observed increase in landslide reports and fatal events for 2010 and previous years over each region. These findings suggest that the co-occurrence of satellite precipitation and landslide reports may serve as a valuable indicator for characterizing the spatiotemporal distribution of landslide-prone areas in order to establish a global rainfall-triggered landslide climatology. This research also considers the sources for this extreme rainfall, citing

  7. Ensemble postprocessing for probabilistic quantitative precipitation forecasts

    Science.gov (United States)

    Bentzien, S.; Friederichs, P.

    2012-12-01

    Precipitation is one of the most difficult weather variables to predict in hydrometeorological applications. In order to assess the uncertainty inherent in deterministic numerical weather prediction (NWP), meteorological services around the globe develop ensemble prediction systems (EPS) based on high-resolution NWP systems. With non-hydrostatic model dynamics and without parameterization of deep moist convection, high-resolution NWP models are able to describe convective processes in more detail and provide more realistic mesoscale structures. However, precipitation forecasts are still affected by displacement errors, systematic biases and fast error growth on small scales. Probabilistic guidance can be achieved from an ensemble setup which accounts for model error and uncertainty of initial and boundary conditions. The German Meteorological Service (Deutscher Wetterdienst, DWD) provides such an ensemble system based on the German-focused limited-area model COSMO-DE. With a horizontal grid-spacing of 2.8 km, COSMO-DE is the convection-permitting high-resolution part of the operational model chain at DWD. The COSMO-DE-EPS consists of 20 realizations of COSMO-DE, driven by initial and boundary conditions derived from 4 global models and 5 perturbations of model physics. Ensemble systems like COSMO-DE-EPS are often limited with respect to ensemble size due to the immense computational costs. As a consequence, they can be biased and exhibit insufficient ensemble spread, and probabilistic forecasts may be not well calibrated. In this study, probabilistic quantitative precipitation forecasts are derived from COSMO-DE-EPS and evaluated at more than 1000 rain gauges located all over Germany. COSMO-DE-EPS is a frequently updated ensemble system, initialized 8 times a day. We use the time-lagged approach to inexpensively increase ensemble spread, which results in more reliable forecasts especially for extreme precipitation events. Moreover, we will show that statistical

  8. Impact of Precipitants on the Structure and Properties of Fe-Co-Ce Composite Catalysts

    Directory of Open Access Journals (Sweden)

    Yongli Zhang

    2016-01-01

    Full Text Available Fe-Co-Ce composite catalysts were prepared by coprecipitation method using CO(NH22, NaOH, NH4HCO3, and NH3·H2O as precipitant agents. The effects of the precipitant agents on the physicochemical properties of the Fe-Co-Ce based catalysts were investigated by SEM, TEM, BET, TG-DTA, and XRD. It was found that the precipitant agents remarkably influenced the morphology and particle size of the catalysts and affected the COD removal efficiency, decolorization rate, and pH of methyl orange for catalytic wet air oxidation (CWAO. The specific surface area of the Fe-Co-Ce composite catalysts successively decreased in the order of NH3·H2O, NH4HCO3, NaOH, and CO(NH22, which correlated to an increasing particle size that increased for each catalyst. For the CWAO of a methyl orange aqueous solutions, the effects of precipitant agents NH3·H2O and NaOH were superior to those of CO(NH22 and NH4HCO3. The catalyst prepared using NH3·H2O as the precipitant agent was mostly composed of Fe2O3, CoO, and CeO2. The COD removal efficiency of methyl orange aqueous solution for NH3·H2O reached 92.9% in the catalytic wet air oxidation. Such a catalytic property was maintained for six runs.

  9. Preparation and characterization of Cu-Ce-La mixed oxide as water-gas shift catalyst for fuel cells application

    Institute of Scientific and Technical Information of China (English)

    ZHI Keduan; LIU Quansheng; ZHAO Ruigang; HE Runxia; ZHANG Lifeng

    2008-01-01

    Cu-Ce-La mixed oxides were prepared by three precipitation methods (coprecipitation, homogeneous precipitation, and deposition precipitation) with variable precipitators and characterized using X-ray diffraction, BET, temperature-programmed reduction, and catalytic reaction for the water-gas shift. The Cu-Ce-La mixed oxide prepared by coprecipitation method with NaOH as precipitator presented the highest activity and thermal stability. Copper ion substituted quadrevalent ceria entered CeO2 (111) framework was in favor of activity and thermal stability of catalyst. The crystallinity of fresh catalysts increased with the reduction process. La3+ or Ce4+ substituted copper ion entered the CeO2 framework during reduction process. The coexistence of surface copper oxide (crystalline) and pure bulk crystalline copper oxide both contributed to the high activity and thermal stability of Cu-Ce-La mixes oxide catalyst.

  10. Radioactive mineral spring precipitates, their analytical and statistical data and the uranium connection

    Science.gov (United States)

    Cadigan, R.A.; Felmlee, J.K.

    1982-01-01

    Major radioactive mineral springs are probably related to deep zones of active metamorphism in areas of orogenic tectonism. The most common precipitate is travertine, a chemically precipitated rock composed chiefly of calcium carbonate, but also containing other minerals. The mineral springs are surface manifestations of hydrothermal conduit systems which extend downward many kilometers to hot source rocks. Conduits are kept open by fluid pressure exerted by carbon dioxide-charged waters rising to the surface propelled by heat and gas (CO2 and steam) pressure. On reaching the surface, the dissolved carbon dioxide is released from solution, and calcium carbonate is precipitated. Springs also contain sulfur species (for example, H2S and HS-), and radon, helium and methane as entrained or dissolved gases. The HS- ion can react to form hydrogen sulfide gas, sulfate salts, and native sulfur. Chemical salts and native sulfur precipitate at the surface. The sulfur may partly oxidize to produce detectable sulfur dioxide gas. Radioactivity is due to the presence of radium-226, radon-222, radium-228, and radon-220, and other daughter products of uranium-238 and thorium-232. Uranium and thorium are not present in economically significant amounts in most radioactive spring precipitates. Most radium is coprecipitated at the surface with barite. Barite (barium sulfate) forms in the barium-containing spring water as a product of the oxidation of sulfur species to sulfate ions. The relatively insoluble barium sulfate precipitates and removes much of the radium from solution. Radium coprecipitates to a lesser extent with manganese-barium- and iron-oxy hydroxides. R-mode factor analysis of abundances of elements suggests that 65 percent of the variance of the different elements is affected by seven factors interpreted as follows: (1) Silica and silicate contamination and precipitation; (2) Carbonate travertine precipitation; (3) Radium coprecipitation; (4) Evaporite precipitation

  11. PYROLYSIS KINETICS OF WASHED PRECIPITATED LIGNIN

    Directory of Open Access Journals (Sweden)

    Christina Gustafsson

    2009-02-01

    Full Text Available This article describes the pyrolysis behavior of precipitated washed lignin in a Laminar Entrained Flow Reactor between 700 and 1000°C and at different residence times. Lignin was precipitated by acidification of softwood black liquor using CO2. After acid washing, the solid material was dried and sieved (80-100 μm. This material was then fed into the reactor at a rate of about 0.1 g/min. The formed gases were analyzed with respect to CO, CO2, and CH4, and char was collected and weighed. A traditional first order Arrhenius kinetic expression, based on the temperature of the particles with respect to residence time, was adapted to the experimental results. The activation energy was found to be 32.1 kJ/mol. The low ash content in the washed lignin gave a very low solid material residue after the reactor.

  12. PRECIPITATION-REGULATED STAR FORMATION IN GALAXIES

    Energy Technology Data Exchange (ETDEWEB)

    Voit, G. Mark; O’Shea, Brian W.; Donahue, Megan [Department of Physics and Astronomy, Michigan State University, East Lansing, MI 48824 (United States); Bryan, Greg L., E-mail: voit@pa.msu.edu [Department of Astronomy, Columbia University, New York, NY (United States)

    2015-07-20

    Galaxy growth depends critically on the interplay between radiative cooling of cosmic gas and the resulting energetic feedback that cooling triggers. This interplay has proven exceedingly difficult to model, even with large supercomputer simulations, because of its complexity. Nevertheless, real galaxies are observed to obey simple scaling relations among their primary observable characteristics. Here we show that a generic emergent property of the interplay between cooling and feedback can explain the observed scaling relationships between a galaxy's stellar mass, its total mass, and its chemical enrichment level, as well as the relationship between the average orbital velocity of its stars and the mass of its central black hole. These relationships naturally result from any feedback mechanism that strongly heats a galaxy's circumgalactic gas in response to precipitation of colder clouds out of that gas, because feedback then suspends the gas in a marginally precipitating state.

  13. Forecasting Monsoon Precipitation Using Artificial Neural Networks

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    This paper explores the application of Artificial Intelligent (AI) techniques for climate forecast. It pres ents a study on modelling the monsoon precipitation forecast by means of Artificial Neural Networks (ANNs). Using the historical data of the total amount of summer rainfall over the Delta Area of Yangtze River in China, three ANNs models have been developed to forecast the monsoon precipitation in the corre sponding area one year, five-year, and ten-year forward respectively. Performances of the models have been validated using a 'new' data set that has not been exposed to the models during the processes of model development and test. The experiment results are promising, indicating that the proposed ANNs models have good quality in terms of the accuracy, stability and generalisation ability.

  14. Energy spectra in relativistic electron precipitation events.

    Science.gov (United States)

    Rosenberg, T. J.; Lanzerotti, L. J.; Bailey, D. K.; Pierson, J. D.

    1972-01-01

    Two events in August 1967, categorized as relativistic electron precipitation (REP) events by their effect on VHF transmissions propagated via the forward-scatter mode, have been examined with regard to the energy spectra of trapped and precipitated electrons. These two substorm-associated events August 11 and August 25 differ with respect to the relativistic, trapped electron population at synchronous altitude; in the August 25 event there was a nonadiabatic enhancement of relativistic (greater than 400 keV) electrons, while in the August 11 event no relativistic electrons were produced. In both events electron spectra deduced from bremsstrahlung measurements (made on a field line close to that of the satellite) had approximately the same e-folding energies as the trapped electron enhancements. However, the spectrum of electrons in the August 25 event was significantly harder than the spectrum in the event of August 11.

  15. What controls deuterium excess in global precipitation?

    Directory of Open Access Journals (Sweden)

    S. Pfahl

    2013-08-01

    Full Text Available The deuterium excess (d of precipitation is widely used in the reconstruction of past climatic changes from ice cores. However, its most common interpretation as moisture source temperature cannot directly be inferred from present-day water isotope observations. Here, we use a new empirical relation between d and near-surface relative humidity together with reanalysis data to globally predict d of surface evaporation from the ocean. The very good quantitative agreement of the predicted hemispherically averaged seasonal cycle with observed d in precipitation indicates that moisture source relative humidity, and not sea surface temperature, is the main driver of d variability on seasonal time scales. There is no convincing evidence that RH might be less important for long-term palaeoclimatic d changes compared to moisture source temperature variations. Ice core d data may thus have to be reinterpreted, focusing on climatic influences on relative humidity during evaporation, in particular related to atmospheric circulation changes.

  16. Atom probe analysis of titanium hydride precipitates.

    Science.gov (United States)

    Takahashi, J; Kawakami, K; Otsuka, H; Fujii, H

    2009-04-01

    It is expected that the three-dimensional atom probe (3DAP) will be used as a tool to visualize the atomic scale of hydrogen atoms in steel is expected, due to its high spatial resolution and very low detection limit. In this paper, the first 3DAP analysis of titanium hydride precipitates in metal titanium is reported in terms of the quantitative detection of hydrogen. FIB fabrication techniques using the lift-out method have enabled the production of needle tips of hydride precipitates, of several tens of microns in size, within a titanium matrix. The hydrogen concentration estimated from 3DAP analysis was slightly smaller than that of the hydride phase predicted from the phase diagram. We discuss the origin of the difference between the experimental and predicted values and the performance of 3DAP for the quantitative detection of hydrogen.

  17. Prediction of the size distribution of precipitates

    Energy Technology Data Exchange (ETDEWEB)

    Prikhodovsky, A. [Forschungszentrum Juelich GmbH (Germany). Inst. fuer Werkstoffe und Verfahren der Energietechnik 2: Werkstoffstruktur und Eigenschaften

    2001-12-01

    Modelling has proven to be an efficient way of cutting the time and costs associated with the investigation of materials properties. A new mathematical model for the prediction of the particle size distribution of precipitates has been developed. The model allows the description of all stages of the precipitation process: nucleation, growth and Ostwald ripening of particles. The incorporation of existing thermodynamic databases allows the simulation of a formation of dispersed phases in commercial multicomponent alloys. The influence of the model parameters on the final particle size distribution was investigated with the example of NbC formation in austenite. It was shown that the interfacial energy of a particle-matrix interface has the most significant effect on the final particle arrangement. A pre-exponential factor, which is the subject of nucleation theories, plays a less significant role in the final particle arrangement. (orig.)

  18. Thyroid Storm Precipitated by Duodenal Ulcer Perforation

    Directory of Open Access Journals (Sweden)

    Shoko Natsuda

    2015-01-01

    Full Text Available Thyroid storm is a rare and life-threatening complication of thyrotoxicosis that requires prompt treatment. Thyroid storm is also known to be associated with precipitating events. The simultaneous treatment of thyroid storm and its precipitant, when they are recognized, in a patient is recommended; otherwise such disorders, including thyroid storm, can exacerbate each other. Here we report the case of a thyroid storm patient (a 55-year-old Japanese male complicated with a perforated duodenal ulcer. The patient was successfully treated with intensive treatment for thyroid storm and a prompt operation. Although it is believed that peptic ulcer rarely coexists with hyperthyroidism, among patients with thyroid storm, perforation of a peptic ulcer has been reported as one of the causes of fatal outcome. We determined that surgical intervention was required in this patient, reported despite ongoing severe thyrotoxicosis, and reported herein a successful outcome.

  19. Twentieth century ENSO-related precipitation mean states in twentieth century reanalysis, reconstructed precipitation and CMIP5 models

    Science.gov (United States)

    Dai, Ni; Arkin, Phillip A.

    2017-05-01

    El Niño-Southern Oscillation (ENSO)-related precipitation during the entire twentieth century is compared among the twentieth century reanalysis (20CR), a statistically reconstructed precipitation dataset (REC) and 30 Coupled Model Intercomparison Project Phase 5 (CMIP5) models. Empirical orthogonal functions, ENSO-related precipitation composites based on sea surface temperature (SST)-constructed ENSO index and singular value decomposition (SVD) are employed to extract ENSO-related precipitation/SST signals in each dataset. With the background trend being removed in all of the data, our results show that the REC and the 20CR resemble both in their precipitation climatology and ENSO-related precipitation results. The biases in the CMIP5 models precipitation climatology such as dry equator over the Pacific Ocean, "double-intertropical convergence zones (ITCZs)" and overly zonal Southern Pacific convergence zone (SPCZ) are major reasons for lowering spatial correlations with the REC and the 20CR precipitation climatology. Two groups of CMIP5 models are built based on severity of these biases in their precipitation background and the spatial correlations of ENSO-related precipitation with the observations. Compared with the group with more severe biases in its precipitation climatology, the group with smaller biases tends to produce more ENSO-like precipitation patterns, simulate more realistic mean magnitude and seasonal variability of ENSO precipitation signals, as well as generating better ENSO-related SST/precipitation correlation patterns produced in its SVD analysis. The ENSO-related precipitation biases in the CMIP5 models over the western Pacific and Indian Ocean, as well as the equatorial Pacific, are strongly related with their precipitation climatology biases over these regions. The ENSO-related precipitation biases over the off-equator eastern Pacific Ocean are associated with both the "double-ITCZs" biases in the precipitation climatology and the ENSO

  20. Twentieth century ENSO-related precipitation mean states in twentieth century reanalysis, reconstructed precipitation and CMIP5 models

    Science.gov (United States)

    Dai, Ni; Arkin, Phillip A.

    2016-07-01

    El Niño-Southern Oscillation (ENSO)-related precipitation during the entire twentieth century is compared among the twentieth century reanalysis (20CR), a statistically reconstructed precipitation dataset (REC) and 30 Coupled Model Intercomparison Project Phase 5 (CMIP5) models. Empirical orthogonal functions, ENSO-related precipitation composites based on sea surface temperature (SST)-constructed ENSO index and singular value decomposition (SVD) are employed to extract ENSO-related precipitation/SST signals in each dataset. With the background trend being removed in all of the data, our results show that the REC and the 20CR resemble both in their precipitation climatology and ENSO-related precipitation results. The biases in the CMIP5 models precipitation climatology such as dry equator over the Pacific Ocean, "double-intertropical convergence zones (ITCZs)" and overly zonal Southern Pacific convergence zone (SPCZ) are major reasons for lowering spatial correlations with the REC and the 20CR precipitation climatology. Two groups of CMIP5 models are built based on severity of these biases in their precipitation background and the spatial correlations of ENSO-related precipitation with the observations. Compared with the group with more severe biases in its precipitation climatology, the group with smaller biases tends to produce more ENSO-like precipitation patterns, simulate more realistic mean magnitude and seasonal variability of ENSO precipitation signals, as well as generating better ENSO-related SST/precipitation correlation patterns produced in its SVD analysis. The ENSO-related precipitation biases in the CMIP5 models over the western Pacific and Indian Ocean, as well as the equatorial Pacific, are strongly related with their precipitation climatology biases over these regions. The ENSO-related precipitation biases over the off-equator eastern Pacific Ocean are associated with both the "double-ITCZs" biases in the precipitation climatology and the ENSO

  1. The Precipitation Characteristics of ISCCP Tropical Weather States

    Science.gov (United States)

    Lee, Dongmin; Oreopoulos, Lazaros; Huffman, George J.; Rossow, William B.; Kang, In-Sik

    2011-01-01

    We examine the daytime precipitation characteristics of the International Satellite Cloud Climatology Project (ISCCP) weather states in the extended tropics (35 deg S to 35 deg N) for a 10-year period. Our main precipitation data set is the TRMM Multisatellite Precipitation Analysis 3B42 data set, but Global Precipitation Climatology Project daily data are also used for comparison. We find that the most convective weather state (WS1), despite an occurrence frequency below 10%, is the most dominant state with regard to surface precipitation, producing both the largest mean precipitation rates when present and the largest percent contribution to the total precipitation of the tropical zone of our study; yet, even this weather state appears to not precipitate about half the time. WS1 exhibits a modest annual cycle of domain-average precipitation rate, but notable seasonal shifts in its geographic distribution. The precipitation rates of the other weather states tend to be stronger when occurring before or after WS1. The relative contribution of the various weather states to total precipitation is different between ocean and land, with WS1 producing more intense precipitation on average over ocean than land. The results of this study, in addition to advancing our understanding of the current state of tropical precipitation, can serve as a higher order diagnostic test on whether it is distributed realistically among different weather states in atmospheric models.

  2. Risk assessment of precipitation extremes in northern Xinjiang, China

    Science.gov (United States)

    Yang, Jun; Pei, Ying; Zhang, Yanwei; Ge, Quansheng

    2017-04-01

    This study was conducted using daily precipitation records gathered at 37 meteorological stations in northern Xinjiang, China, from 1961 to 2010. We used the extreme value theory model, generalized extreme value (GEV) and generalized Pareto distribution (GPD), statistical distribution function to fit outputs of precipitation extremes with different return periods to estimate risks of precipitation extremes and diagnose aridity-humidity environmental variation and corresponding spatial patterns in northern Xinjiang. Spatiotemporal patterns of daily maximum precipitation showed that aridity-humidity conditions of northern Xinjiang could be well represented by the return periods of the precipitation data. Indices of daily maximum precipitation were effective in the prediction of floods in the study area. By analyzing future projections of daily maximum precipitation (2, 5, 10, 30, 50, and 100 years), we conclude that the flood risk will gradually increase in northern Xinjiang. GEV extreme value modeling yielded the best results, proving to be extremely valuable. Through example analysis for extreme precipitation models, the GEV statistical model was superior in terms of favorable analog extreme precipitation. The GPD model calculation results reflect annual precipitation. For most of the estimated sites' 2 and 5-year T for precipitation levels, GPD results were slightly greater than GEV results. The study found that extreme precipitation reaching a certain limit value level will cause a flood disaster. Therefore, predicting future extreme precipitation may aid warnings of flood disaster. A suitable policy concerning effective water resource management is thus urgently required.

  3. Precipitation sensitivity to warming estimated from long island records

    Science.gov (United States)

    Polson, D.; Hegerl, G. C.; Solomon, S.

    2016-07-01

    Some of the most damaging impacts of climate change are a consequence of changes to the global water cycle. Atmospheric warming causes the water cycle to intensify, increasing both atmospheric water vapor concentrations and global precipitation and enhancing existing patterns of precipitation minus evaporation (P - E). This relationship between temperature and precipitation therefore makes understanding how precipitation has changed with global temperatures in the past crucial for projecting changes with future warming. In situ observations cannot readily estimate global precipitation sensitivity to temperature (dP/dT), as land precipitation changes are affected by water limitation. Satellite observations of precipitation over ocean are only available after 1979, but studies based on them suggest a precipitation sensitivity over wet tropical (30N-30S) oceans that exceeds the Clausius-Clapeyron value. Here, we determine for the first time precipitation sensitivity using longer (1930-2005), island-based in situ observations to estimate dP/dT over islands. The records show a robust pattern of increasing precipitation in the tropics and decreasing precipitation in the subtropics, as predicted from physical arguments, and heavy precipitation shows a stronger sensitivity than mean precipitation over many islands. The pattern and magnitude of island-based dP/dT agree with climate models if masked to island locations, supporting model predictions of future changes.

  4. Optimum conditions for microbial carbonate precipitation.

    Science.gov (United States)

    Okwadha, George D O; Li, Jin

    2010-11-01

    The type of bacteria, bacterial cell concentration, initial urea concentration, reaction temperature, the initial Ca(2+) concentration, ionic strength, and the pH of the media are some factors that control the activity of the urease enzyme, and may have a significant impact on microbial carbonate precipitation (MCP). Factorial experiments were designed based on these factors to determine the optimum conditions that take into consideration economic advantage while at the same time giving quality results. Sporosarcina pasteurii strain ATCC 11859 was used at constant temperature (25°C) and ionic strength with varying amounts of urea, Ca(2+), and bacterial cell concentration. The results indicate that the rate of ureolysis (k(urea)) increases with bacterial cell concentration, and the bacterial cell concentration had a greater influence on k(urea) than initial urea concentration. At 25 mM Ca(2+) concentration, increasing bacterial cell concentration from 10(6) to 10(8)cells mL⁻¹ increased the CaCO(3) precipitated and CO(2) sequestrated by over 30%. However, when the Ca(2+) concentration was increased 10-fold to 250 mM Ca(2+), the amount of CaCO(3) precipitated and CO(2) sequestrated increased by over 100% irrespective of initial urea concentration. Consequently, the optimum conditions for MCP under our experimental conditions were 666 mM urea and 250 mM Ca(2+) at 2.3×10⁸ cells mL⁻¹ bacterial cell concentration. However, a greater CaCO(3) deposition is achievable with higher concentrations of urea, Ca(2+), and bacterial cells so long as the respective quantities are within their economic advantage. X-ray Diffraction, Scanning Electron Microscopy and Energy Dispersive X-ray analyzes confirmed that the precipitate formed was CaCO(3) and composed of predominantly calcite crystals with little vaterite crystals.

  5. Asphaltene Precipitation inHeavy-Oil Systems

    OpenAIRE

    Verås, Tor Jørgen

    2011-01-01

    Vapor-Assisted Petroleum Extraction (VAPEX) is a relatively new and promising method for recovering heavy crude oils in Canada. The technique upgrades the oil in-situ through asphaltene precipitation, but it may also cause damage to the formation by clogging its pore throats. This thesis brings some clarity to what asphaltenes are and how they form from mixes of bitumen and solvent, depending on the type and amount of solvent used. This was investigated through a series of laboratory experime...

  6. Conditional simulations for fields of extreme precipitation

    Science.gov (United States)

    Bechler, Aurélien; Vrac, Mathieu; Bel, Liliane

    2014-05-01

    Many environmental models, such as hydrological models, require input data, e.g. precipitation values, correctly simulated and distributed, even at locations where no observation is available. This is particularly true for extreme events that may be of high importance for impact studies. The last decade has seen max-stable processes emerge as a powerful tool for the statistical modeling of spatial extremes. Recently, such processes have been used in climate context to perform simulations at ungauged sites based on empirical distributions of a spatial field conditioned by observed values in some locations. In this work conditional simulations of extremal t process are investigated, taking benefits of its spectral construction. The methodology of conditional simulations proposed by Dombry et al. [2013] for Brown-Resnick and Schlather models is adapted for the extremal t process with some improvements which enlarge the possible number of conditional points. A simulation study enables to highlight the role of the different parameters of the model and to emphasize the importance of the steps of the algorithm. In this work, we focus on the French Mediterranean basin, which is a key spot of occurrences of meteorological extremes such as heavy precipitation. Indeed, major extreme precipitation are regularly observed in this region near the 'cévenol" mountains. The modeling and the understanding of these extreme precipitation - the so-called 'cévenol events" - are of major importance for hydrological studies in this complex terrain since they often trigger major floods in this region. The application of our methodology on real data in this region shows that the model and the algorithm perform well provided the stationary assumptions are fulfilled.

  7. Analysis of microalloy precipitate reversion in steels

    Science.gov (United States)

    Michal, G. M.; Locci, I. E.

    1988-01-01

    The influence of the ferrite to austenite allotropic transformation on the stability of MXn precipitates in an iron matrix is studied. In the MX phase, M is a group IVb or Vb transition metal, such as niobium, titanium, or vanadium. X is carbon or nitrogen and n is in the range of 0.75-1.0. The application of the present model to the case of vanadium carbide reversion in a microalloyed steel is discussed.

  8. Precipitates/Salts Model Sensitivity Calculation

    Energy Technology Data Exchange (ETDEWEB)

    P. Mariner

    2001-12-20

    The objective and scope of this calculation is to assist Performance Assessment Operations and the Engineered Barrier System (EBS) Department in modeling the geochemical effects of evaporation on potential seepage waters within a potential repository drift. This work is developed and documented using procedure AP-3.12Q, ''Calculations'', in support of ''Technical Work Plan For Engineered Barrier System Department Modeling and Testing FY 02 Work Activities'' (BSC 2001a). The specific objective of this calculation is to examine the sensitivity and uncertainties of the Precipitates/Salts model. The Precipitates/Salts model is documented in an Analysis/Model Report (AMR), ''In-Drift Precipitates/Salts Analysis'' (BSC 2001b). The calculation in the current document examines the effects of starting water composition, mineral suppressions, and the fugacity of carbon dioxide (CO{sub 2}) on the chemical evolution of water in the drift.

  9. Global warming without global mean precipitation increase?

    Science.gov (United States)

    Salzmann, Marc

    2016-06-01

    Global climate models simulate a robust increase of global mean precipitation of about 1.5 to 2% per kelvin surface warming in response to greenhouse gas (GHG) forcing. Here, it is shown that the sensitivity to aerosol cooling is robust as well, albeit roughly twice as large. This larger sensitivity is consistent with energy budget arguments. At the same time, it is still considerably lower than the 6.5 to 7% K(-1) decrease of the water vapor concentration with cooling from anthropogenic aerosol because the water vapor radiative feedback lowers the hydrological sensitivity to anthropogenic forcings. When GHG and aerosol forcings are combined, the climate models with a realistic 20th century warming indicate that the global mean precipitation increase due to GHG warming has, until recently, been completely masked by aerosol drying. This explains the apparent lack of sensitivity of the global mean precipitation to the net global warming recently found in observations. As the importance of GHG warming increases in the future, a clear signal will emerge.

  10. How extreme is extreme hourly precipitation?

    Science.gov (United States)

    Papalexiou, Simon Michael; Dialynas, Yannis G.; Pappas, Christoforos

    2016-04-01

    The importance of accurate representation of precipitation at fine time scales (e.g., hourly), directly associated with flash flood events, is crucial in hydrological design and prediction. The upper part of a probability distribution, known as the distribution tail, determines the behavior of extreme events. In general, and loosely speaking, tails can be categorized in two families: the subexponential and the hyperexponential family, with the first generating more intense and more frequent extremes compared to the latter. In past studies, the focus has been mainly on daily precipitation, with the Gamma distribution being the most popular model. Here, we investigate the behaviour of tails of hourly precipitation by comparing the upper part of empirical distributions of thousands of records with three general types of tails corresponding to the Pareto, Lognormal, and Weibull distributions. Specifically, we use thousands of hourly rainfall records from all over the USA. The analysis indicates that heavier-tailed distributions describe better the observed hourly rainfall extremes in comparison to lighter tails. Traditional representations of the marginal distribution of hourly rainfall may significantly deviate from observed behaviours of extremes, with direct implications on hydroclimatic variables modelling and engineering design.

  11. A subgrid parameterization scheme for precipitation

    Directory of Open Access Journals (Sweden)

    S. Turner

    2011-07-01

    Full Text Available With increasing computing power, the horizontal resolution of numerical weather prediction (NWP models is improving and today reaches 1 to 5 km. Nevertheless, clouds and precipitation are still subgrid scale processes for most cloud types, such as cumulus and stratocumulus. Subgrid scale parameterizations for water vapor condensation have been in use for many years and are based on a prescribed PDF of relative humidity spatial variability within the grid, thus providing a diagnosis of the cloud fraction. A similar scheme is developed and tested here. It is based on a prescribed PDF of cloud water variability and a threshold value of liquid water content for droplet collection to derive a rain fraction within the model grid. Precipitation of rainwater raises additional concerns relative to the overlap of cloud and rain fractions, however. The scheme is developed following an analysis of data collected during field campaigns in stratocumulus (DYCOMS-II and fair weather cumulus (RICO and tested in a 1-D framework against large eddy simulations of these observed cases. The new parameterization is then implemented in a 3-D NWP model with a horizontal resolution of 2.5 km to simulate real cases of precipitating cloud systems over France.

  12. Preparation and photocatalytic kinetics of nano-ZnO powders by precipitation stripping process

    Institute of Scientific and Technical Information of China (English)

    Dongxiang ZHANG; Hang XU; Min XUE; Wenguo XU; V TARASOV

    2008-01-01

    Ultra-fine zinc oxalate powders were prepared through a precipitation stripping method with bis(2-ethyl-hexyl) phosphate (HDEHP) diluted by tetrachloride carbon as the extractant,and oxalic acid ethanol aqueous solution as the re-extractant and precipitator.Zinc oxide powders were obtained by decomposing zinc oxalate powders at 450℃.The prepared zinc oxide powders were characterized by transmission electron microscope (TEM),Scanning elec-tron microscope (SEM),Thermogravimetric analysis (TG),X-ray diffraction (XRD) and Fourier transmission infrared (FT-IR) spectrum.The photocatalytic performance of methylene blue by zinc oxide was studied based on the Langmuir model and Photo-Layer model.The results show that some zinc oxide powders were micro-multipore mate-rials with hexagonal crystal.The particle size was around 32 nm.The photocatalytic process was the control step in the chemical reaction.The photo catalytic process followed pseudo-first order kinetics and ,OH concentration inside the photo-layer in different reaction condition were calcu-lated according to the Photo-Layer model.

  13. Correlative Microscopy of alpha' Precipitation in Neutron-Irradiated Fe-Cr-Al Alloys

    Science.gov (United States)

    Briggs, Samuel A.

    Fe-Cr-Al alloys are currently being considered for accident tolerant light water reactor fuel cladding applications due to their superior high temperature oxidation and corrosion resistance compared to Zr-based alloys. However, precipitation of the Cr-rich alpha' phase during exposure to LWR operational environments can result in application-limiting hardening and embrittlement. To study this effect, four Fe-Cr-Al model alloys with compositions between 10-18 at.% Cr and 5.8-9.3 at.% Al have been neutron-irradiated in the High Flux Isotope Reactor at a target temperature of 320°C to nominal damage doses of up to 7 dpa in order to emulate typical LWR exposure conditions. A correlative microscopy approach involving atom probe tomography, small-angle neutron scattering, and scanning transmission electron microscopy coupled with energy dispersive x-ray spectroscopy was employed to study the resulting precipitate microstructure. This approach necessitated the development of various analysis techniques to allow for cross-comparison between experimental techniques, including a novel method for correcting for trajectory aberration artifacts in atom probe data sets through phase density comparison. Successful correlation of results from these techniques allows for the individual limitations of each to be overcome and enables the detailed microstructural information gleaned from highly localized atom probe tomography analyses to be extrapolated to bulk alloy behavior. Precipitation response was found to increase with Cr content, while Al additions appeared to partially destabilized the alpha' phase, resulting in precipitate compositions with reduced Cr content compared to binary Fe-Cr systems. Observed precipitate evolution with radiation dose indicates a diffusion-limited coarsening mechanism that is similar to what is observed in the thermally aged system. This work represents the current state-of-the-art on both techniques for analysis of alpha' precipitate

  14. Experimental Marvin Windshield Effects on Precipitation Records in Leadville, Colorado

    Science.gov (United States)

    Jarrett, Robert D.; Crow, Loren W.

    1988-01-01

    An evaluation of the Leadville, Colorado, precipitation records that include a reported record-breaking storm (and flood) at higher elevations in the Rocky Mountains has indicated that the use of an experimental Marvin windshield (designed to decrease the effects of wind on precipitation-gage catchment of snow during winter) resulted in substantially overregistered summer precipitation for 1919 to 1938. The July monthly precipitation for these years was over-registered by an average of 157 percent of the long-term July monthly precipitation at Leadville. The cause of the overregistration of precipitation was the almost 4-foot-top-diameter cone-shaped windshield that had the effect of 'funneling' hail and rain splash into the rain gage. Other nearby precipitation gages, which did not use this Marvin windshield, did not have this trend of increased precipitation for the same period. Streamflow records from the Leadville area also do not indicate an increase in streamflow from 1919 to 1938.

  15. Biogrout, ground improvement by microbial induced carbonate precipitation

    NARCIS (Netherlands)

    Van Paassen, L.A.

    2009-01-01

    Biogrout is a new ground improvement method based on microbially induced precipitation of calcium carbonate (MICP). When supplied with suitable substrates, micro-organisms can catalyze biochemical conversions in the subsurface resulting in precipitation of inorganic minerals, which change the

  16. Real Time River Forecasting Center Quantitative Precipitation Estimate

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — Radar indicated-rain gage verified and corrected hourly precipitation estimate on a corrected ~4km HRAP grid. This archive contains hourly estimates of precipitation...

  17. Trend analysis of precipitation in Jharkhand State, India - Investigating precipitation variability in Jharkhand State

    Science.gov (United States)

    Chandniha, Surendra Kumar; Meshram, Sarita Gajbhiye; Adamowski, Jan Franklin; Meshram, Chandrashekhar

    2016-08-01

    Jharkhand is one of the eastern states of India which has an agriculture-based economy. Uncertain and erratic distribution of precipitation as well as a lack of state water resources planning is the major limitation to crop growth in the region. In this study, the spatial and temporal variability in precipitation in the state was examined using a monthly precipitation time series of 111 years (1901-2011) from 18 meteorological stations. Autocorrelation and Mann-Kendall/modified Mann-Kendall tests were utilized to detect possible trends, and the Theil and Sen slope estimator test was used to determine the magnitude of change over the entire time series. The most probable change year (change point) was detected using the Pettitt-Mann-Whitney test, and the entire time series was sub-divided into two parts: before and after the change point. Arc-Map 9.3 software was utilized to assess the spatial patterns of the trends over the entire state. Annual precipitation exhibited a decreasing trend in 5 out of 18 stations during the whole period. For annual, monsoon and winter periods of precipitation, the slope test indicated a decreasing trend for all stations during 1901-2011. The highest variability was observed in post-monsoon precipitation (77.87 %) and the lowest variability was observed in the annual series (15.76 %) over the 111 years. An increasing trend in precipitation in the state was found during the period 1901-1949, which was reversed during the subsequent period (1950-2011).

  18. Magnesium Oxide

    Science.gov (United States)

    Magnesium is an element your body needs to function normally. Magnesium oxide may be used for different reasons. Some ... to relieve heartburn, sour stomach, or acid indigestion. Magnesium oxide also may be used as a laxative ...

  19. Impact of Precipitation Fluctuation on Desert-Grassland ANPP

    Directory of Open Access Journals (Sweden)

    Liangxu Liu

    2016-11-01

    Full Text Available Precipitation change has significantly influenced annual net primary productivity (ANPP at either annual or seasonal scales in desert steppes in arid and semi-arid regions. In order to reveal the process of precipitation driving ANPP at different time scales, responses of different ANPP levels to the inter-annual and intra-annual precipitation fluctuations were analyzed. ANPP was reversed by building a ground reflectance spectrum model, from 2000 to 2015, using the normalized differential vegetation index of the Moderate-Resolution Imaging Spectroradiometer (MODIS-NDVI data at 250 m × 250 m spatial resolution. Since the description of the differently expressing forms of precipitation are not sufficient in former studies in order to overcome the deficiency of former studies, in this study, intra-annual precipitation fluctuations were analyzed not only with precipitation of May–August, June–August, July–August, and August, respectively, which have direct influence on vegetation productivity within the year, but quantitative description, vector precipitation (R, concentration ratio (Cd, and concentration period (D, were also used to describe the overall characteristics of intra-annual precipitation fluctuations. The concentration ratio and the maximum precipitation period of the intra-annual precipitation were represented by using monthly precipitation. The results showed that: (1 in the period from 1971 to 2015, the maximum annual precipitation is 3.76 times that of the minimum in the Urat desert steppe; (2 vector precipitation is more significantly related to ANPP (r = 0.7724, p = 0.000 compared to meteorological annual precipitation and real annual precipitation influence; and (3 annual precipitation is almost concentrated in 5–8 months and monthly precipitation accumulation has significantly effected ANPP, especially in the period of June–August, since the vegetation composition in the study area was mainly sub-shrubs and perennial

  20. IN-SITU CHEMICAL STABILIZATION OF METALS AND RADIONUCLIDES THROUGH ENHANCED ANAEROBIC REDUCTIVE PRECIPITATION

    Energy Technology Data Exchange (ETDEWEB)

    Christopher C. Lutes; Angela Frizzell, PG; Todd A. Thornton; James M. Harrington

    2003-08-01

    The objective of this NETL sponsored bench-scale study was to demonstrate the efficacy of enhanced anaerobic reductive precipitation (EARP) technology for precipitating uranium using samples from contaminated groundwater at the Fernald Closure Project (FCP) in Cincinnati, Ohio. EARP enhances the natural biological reactions in the groundwater through addition of food grade substrates (typically molasses) to drive the oxidative-reductive potential of the groundwater to a lower, more reduced state, thereby precipitating uranium from solution. In order for this in-situ technology to be successful in the long term, the precipitated uranium must not be re-dissolved at an unacceptable rate once groundwater geochemical conditions return to their pretreatment, aerobic state. The approach for this study is based on the premise that redissolution of precipitated uranium will be slowed by several mechanisms including the presence of iron sulfide precipitates and coatings, and sorption onto fresh iron oxides. A bench-scale study of the technology was performed using columns packed with site soil and subjected to a continuous flow of uranium-contaminated site groundwater (476 {micro}g/L). The ''treated'' column received a steady stream of dilute food grade molasses injected into the contaminated influent. Upon attainment of a consistently reducing environment and demonstrated removal of uranium, an iron sulfate amendment was added along with the molasses in the influent solution. After a month long period of iron addition, the treatments were halted, and uncontaminated, aerobic, unamended water was introduced to the treated column to assess rebound of uranium concentrations. In the first two months of treatment, the uranium concentration in the treated column decreased to the clean-up level (30 {micro}g/L) or below, and remained there for the remainder of the treatment period. A brief period of resolubilization of uranium was observed as the treated column

  1. Confirmation of EMIC wave-driven relativistic electron precipitation

    Science.gov (United States)

    Hendry, Aaron T.; Rodger, Craig J.; Clilverd, Mark A.; Engebretson, Mark J.; Mann, Ian R.; Lessard, Marc R.; Raita, Tero; Milling, David K.

    2016-06-01

    Electromagnetic ion cyclotron (EMIC) waves are believed to be an important source of pitch angle scattering driven relativistic electron loss from the radiation belts. To date, investigations of this precipitation have been largely theoretical in nature, limited to calculations of precipitation characteristics based on wave observations and small-scale studies. Large-scale investigation of EMIC wave-driven electron precipitation has been hindered by a lack of combined wave and precipitation measurements. Analysis of electron flux data from the POES (Polar Orbiting Environmental Satellites) spacecraft has been suggested as a means of investigating EMIC wave-driven electron precipitation characteristics, using a precipitation signature particular to EMIC waves. Until now the lack of supporting wave measurements for these POES-detected precipitation events has resulted in uncertainty regarding the driver of the precipitation. In this paper we complete a statistical study comparing POES precipitation measurements with wave data from several ground-based search coil magnetometers; we further present a case study examining the global nature of this precipitation. We show that a significant proportion of the precipitation events correspond with EMIC wave detections on the ground; for precipitation events that occur directly over the magnetometers, this detection rate can be as high as 90%. Our results demonstrate that the precipitation region is often stationary in magnetic local time, narrow in L, and close to the expected plasmapause position. Predominantly, the precipitation is associated with helium band rising tone Pc1 waves on the ground. The success of this study proves the viability of POES precipitation data for investigating EMIC wave-driven electron precipitation.

  2. Increased precipitation acidity in the central Sierra Nevada

    Science.gov (United States)

    Byron, Earl R.; Axler, Richard P.; Goldman, Charles R.

    Between 1979 and 1986, precipitation acidity increased significantly on the crest of the central Sierra Nevada. Variation in precipitation pH was closely associated with change in nitrate concentrations but not to sulfate. This area of the Sierra Nevada crest contains many acid-sensitive, poorly buffered lakes and ponds which can be adversely affected by increasing precipitation acidity.

  3. Precipitate coarsening and self organization in erbium-doped silica

    DEFF Research Database (Denmark)

    Sckerl, Mads W.; Guldberg-Kjær, Søren Andreas; Poulsen, Mogens Rysholt

    1999-01-01

    , and formation of erbium-rich. precipitates is seen to occur if the erbium concentration exceeds similar to 0.01 at. %. These precipitates are observed to coarsen and subsequently dissolve with increasing annealing time. Moreover, self organization of precipitates has been observed in the form of layering...

  4. Radioactive demonstration of the ``late wash`` Precipitate Hydrolysis Process

    Energy Technology Data Exchange (ETDEWEB)

    Bibler, N.E.; Ferrara, D.M.; Ha, B.C.

    1992-06-30

    This report presents results of the radioactive demonstration of the DWPF Precipitate Hydrolysis Process as it would occur in the ``late wash`` flowsheet in the absence of hydroxylamine nitrate. Radioactive precipitate containing Cs-137 from the April, 1983, in-tank precipitation demonstration in Tank 48 was used for these tests.

  5. The Version 2 Global Precipitation Climatology Project (GPCP) Monthly Precipitation Analysis (1979-Present)

    Science.gov (United States)

    Adler, Robert F.; Huffman, George J.; Chang, Alfred; Ferraro, Ralph; Xie, Ping-Ping; Janowiak, John; Rudolf, Bruno; Schneider, Udo; Curtis, Scott; Bolvin, David

    2003-01-01

    The Global Precipitation Climatology Project (GPCP) Version 2 Monthly Precipitation Analysis is described. This globally complete, monthly analysis of surface precipitation at 2.5 degrees x 2.5 degrees latitude-longitude resolution is available from January 1979 to the present. It is a merged analysis that incorporates precipitation estimates from low-orbit-satellite microwave data, geosynchronous-orbit-satellite infrared data, and rain gauge observations. The merging approach utilizes the higher accuracy of the low-orbit microwave observations to calibrate, or adjust, the more frequent geosynchronous infrared observations. The data set is extended back into the premicrowave era (before 1987) by using infrared-only observations calibrated to the microwave-based analysis of the later years. The combined satellite-based product is adjusted by the raingauge analysis. This monthly analysis is the foundation for the GPCP suite of products including those at finer temporal resolution, satellite estimate, and error estimates for each field. The 23-year GPCP climatology is characterized, along with time and space variations of precipitation.

  6. Integrated Precipitation and Hydrology Experiment (IPHEx)/Orographic Precipitation Processes Study Field Campaign Report

    Energy Technology Data Exchange (ETDEWEB)

    Barros, A. P. [Duke Univ., Durham, NC (United States); Petersen, W. [National Aeronautics and Space Administration (NASA), Washington, DC (United States); Wilson, A. M. [Duke Univ., Durham, NC (United States)

    2016-04-01

    Three Microwave Radiometers (two 3-channel and one 2-channel) were deployed in the Southern Appalachian Mountains in western North Carolina as part of the Integrated Precipitation and Hydrology Experiment (IPHEx), which was the first National Aeronautics and Space Administration (NASA) Global Precipitation Mission (GPM) Ground Validation (GV) field campaign after the launch of the GPM Core Satellite (Barros et al. 2014). The radiometers were used along with other instrumentation to estimate the liquid water content of low-level clouds and fog. Specifically, data from the radiometers were collected to help, with other instrumentation, to characterize fog formation, evolution, and dissipation in the region (by monitoring the liquid water path in the column) and observe the effect of that fog on the precipitation regime. Data were collected at three locations in the Southern Appalachians, specifically western North Carolina: a valley in the inner mountain region, a valley in the open mountain pass region, and a ridge in the inner region. This project contributes to the U.S. Department of Energy (DOE)’s Atmospheric Radiation Measurement (ARM) Climate Research Facility mission by providing in situ observations designed to improve the understanding of clouds and precipitation processes in complex terrain. The end goal is to use this improved understanding of physical processes to improve remote-sensing algorithms and representations of orographic precipitation microphysics in climate and earth system models.

  7. Liberation of Adsorbed and Co-Precipitated Arsenic from Jarosite, Schwertmannite, Ferrihydrite, and Goethite in Seawater

    Directory of Open Access Journals (Sweden)

    Rodrigo Alarcón

    2014-07-01

    Full Text Available Sea level rise is able to change the geochemical conditions in coastal systems. In these environments, transport of contaminants can be controlled by the stability and adsorption capacity of iron oxides. The behavior of adsorbed and co-precipitated arsenic in jarosite, schwertmannite, ferrihydrite, and goethite in sea water (common secondary minerals in coastal tailings was investigated. The aim of the investigation was to establish As retention and transport under a marine flood scenario, which may occur due to climate change. Natural and synthetic minerals with co-precipitated and adsorbed As were contacted with seawater for 25 days. During this period As, Fe, Cl, SO4, and pH levels were constantly measured. The larger retention capability of samples with co-precipitated As, in relation with adsorbed As samples, reflects the different kinetics between diffusion, dissolution, and surface exchange processes. Ferrihydrite and schwertmannite showed good results in retaining arsenic, although schwertmannite holding capacity was enhanced due its buffering capacity, which prevented reductive dissolution throughout the experiment. Arsenic desorption from goethite could be understood in terms of ion exchange between oxides and electrolytes, due to the charge difference generated by a low point-of-zero-charge and the change in stability of surface complexes between synthesis conditions and natural media.

  8. The influence of calcium, magnesium, phosphorus and silica in vanadium precipitation in acidic sulfate solutions

    Energy Technology Data Exchange (ETDEWEB)

    Martins, A.H. [Minas Gerais Univ., Belo Horizonte, MG (Brazil). Dept. de Engenharia Metalurgica e de Materiais. E-mail: ahmartin@demet.ufmg.br

    2000-06-01

    The experimental research work was carried out in accordance with the Factorial Design Statistical Method to evaluate and analyze the influence of calcium, magnesium, silica and phosphorus on the precipitation of vanadates. precipitation was performed by neutralization with H{sub 2} SO{sub 4} of alkaline aqueous solutions containing vanadium pentoxide (V{sub 2} O{sub 5}) at 60 {+-} 2 deg C. The experimental responses measured were percent of vanadium recovery and vanadium pentoxide content in the precipitate. These impurities are considered representative of those present in a leach liquor from the ore obtained at Campo Alegre de Lourdes (Brazil). The operational variables in this work were used optimum conditions as determined by the statistical approach. Among the impurities under study, phosphorus exhibited the highest negative influence on the experimental responses. Phosphorus diminished the percent of vanadium recovered from 98.9 to 34.5 and the vanadium oxide content in the precipitate from 91.2% to 39.3%. (author)

  9. Chromium (III Removal and Recovery from Tannery Wastewater by Precipitation Process

    Directory of Open Access Journals (Sweden)

    Abass Esmaeili

    2005-01-01

    Full Text Available Chromium (III salts are the most widely used chemicals for tanning processes, but 60-70% of total chromium salts reacts with the hides. In the other word, about 30-40% of the chromium amount remains in the solids and liquid wastes (especially spent tanning solutions. Therefore, the removal and recovery of the chromium content of these wastewaters are necessary for environmental protection and economic reasons. Removal and recovery of chromium were carried out by using precipitation process. For this purpose, three precipitating agents calcium hydroxide, sodium hydroxide and magnesium oxide were used. The effects of pH, stirring time, settling rate and sludge volume were studied in batch experiments. Results show that the optimum pH is 8-9 and the good sludge with high settling rate and lower volume obtain by the MgO precipitating agent. Hence the MgO is a good precipitating agent for removal and recovery of chromium from tanning wastewater.

  10. The influence of organic compounds on the development of precipitation acidity in maritime clouds

    Directory of Open Access Journals (Sweden)

    L. Alfonso

    2004-01-01

    Full Text Available In order to estimate the anthropogenic influence of gas and aerosol emissions from the Petroleum Industry in maritime zones with clouds of small vertical extent, a numerical 1-D Eulerian cloud-chemical model with detailed microphysics (Alfonso and Raga, 2002 is used to simulate the influence of water soluble organic compounds (WSOC and organic+inorganic gas emissions on cloud development. Following Mircea et al. (2002, we tested the sensitivity of the cloud and precipitation development in the classical inorganic case (CIC and the inorganic+organic case (IOC with respect to CCN compositions. The results indicate an increase in the droplet concentration for the IOC, and a delay in the development of precipitation. The pH spectral evolution was studied during both the development and precipitation stages. The influence of the diffusion of formic acid and its generation by oxidation of hydrated formaldehyde in the aqueous phase result in a reduction in the pH of precipitation in the range between 0.05 and 0.15 pH units (from 1 to 3% for the high ambient SO2 concentration (20 ppb and between 0.2-0.5 pH units (from 4 to 10% for the low ambient SO2 concentration (1 ppb case.

  11. Proactive modeling of water quality impacts of extreme precipitation events in a drinking water reservoir.

    Science.gov (United States)

    Jeznach, Lillian C; Hagemann, Mark; Park, Mi-Hyun; Tobiason, John E

    2017-10-01

    Extreme precipitation events are of concern to managers of drinking water sources because these occurrences can affect both water supply quantity and quality. However, little is known about how these low probability events impact organic matter and nutrient loads to surface water sources and how these loads may impact raw water quality. This study describes a method for evaluating the sensitivity of a water body of interest from watershed input simulations under extreme precipitation events. An example application of the method is illustrated using the Wachusett Reservoir, an oligo-mesotrophic surface water reservoir in central Massachusetts and a major drinking water supply to metropolitan Boston. Extreme precipitation event simulations during the spring and summer resulted in total organic carbon, UV-254 (a surrogate measurement for reactive organic matter), and total algae concentrations at the drinking water intake that exceeded recorded maximums. Nutrient concentrations after storm events were less likely to exceed recorded historical maximums. For this particular reservoir, increasing inter-reservoir transfers of water with lower organic matter content after a large precipitation event has been shown in practice and in model simulations to decrease organic matter levels at the drinking water intake, therefore decreasing treatment associated oxidant demand, energy for UV disinfection, and the potential for formation of disinfection byproducts. Copyright © 2017 Elsevier Ltd. All rights reserved.

  12. Fabrication and characterization of NiO nanoparticles by precipitation from aqueous solution

    Energy Technology Data Exchange (ETDEWEB)

    Moghaddam, Javad; Hashemi, Elham [Sahand University of Technology, Tabriz (Iran, Islamic Republic of)

    2014-03-15

    Present work involves synthesis of NiO nanoparticles using chemical homogeneous precipitation (CHP) method as a facile procedure. Ammonia as a complex agent was used in this method. Effects of different types of complexation-precipitation methods on the crystallinity and morphology of nanoparticles were investigated. NiO particles were prepared by direct precipitation method from NiSO4 solution to compare crystallinity and morphology of NiO particles with particles obtained via complexation-precipitation methods. Our major intent was to investigate the effect of complex agent on the crystallization and growth of NiO nanoparticles. Results showed that the best condition for synthesizing spherical NiO shape was using NaOH as decomposing agent, of which the consequence was more uniformity and spherical nanoparticles with a diameter in the range of 40-60 nm. The size of the nickel oxide and nickel hydroxide nanoparticles was estimated by X-ray powder diffraction (XRD) pattern. The chemical structure information of the particles was studied by Fourier transform infrared (FT-IR) spectroscopy. Spherical, elliptical, sheet or flowerlike shapes were detected by field emission scanning electron microscopy (FESEM) analysis. Results showed that by the use of ammonia as complex agent, crystalline state and particles size distribution of NiO nanoparticles improved.

  13. The influence of calcium, magnesium, phosphorus and silica on vanadium precipitation in acidic sulfate solutions

    Directory of Open Access Journals (Sweden)

    A. H. Martins

    2000-06-01

    Full Text Available The experimental research work was carried out in accordance with the Factorial Design Statistical Method to evaluate and analyze the influence of calcium, magnesium, silica and phosphorus on the precipitation of vanadates. Precipitation was performed by neutralization with H2SO4 of alkaline aqueous solutions containing vanadium pentoxide (V2O5 at 60± 2ºC. The experimental responses measured were percent of vanadium recovery and vanadium pentoxide content in the precipitate. These impurities are considered representative of those present in a leach liquor from the ore obtained at Campo Alegre de Lourdes (Brazil. The operational variables in this work were used under optimum conditions as determined by the statistical approach. Among the impurities under study, phosphorus exhibited the highest negative influence on the experimental responses. Phosphorus diminished the percent of vanadium recovered from 98.9 to 34.5 and the vanadium oxide content in the precipitate from 91.2 % to 39.3 %.

  14. Biotechnological aspects of anaerobic oxidation of methane coupled to sulfate reduction

    NARCIS (Netherlands)

    Meulepas, R.J.W.

    2009-01-01

    Sulfate reduction (SR) can be used for the removal and recovery of metals and oxidized sulfur compounds from waste streams. Sulfate-reducing bacteria reduce oxidized sulfur compounds to sulfide. Subsequently, sulfide can precipitate dissolved metals or can be oxidized to elemental sulfur. Both metal

  15. Biotechnological aspects of anaerobic oxidation of methane coupled to sulfate reduction

    NARCIS (Netherlands)

    Meulepas, R.J.W.

    2009-01-01

    Sulfate reduction (SR) can be used for the removal and recovery of metals and oxidized sulfur compounds from waste streams. Sulfate-reducing bacteria reduce oxidized sulfur compounds to sulfide. Subsequently, sulfide can precipitate dissolved metals or can be oxidized to elemental sulfur. Both metal

  16. Carbonate precipitation by the thermophilic archaeon Archaeoglobus fulgidus: a model of carbon flow for an ancient microorganism

    Directory of Open Access Journals (Sweden)

    P. Ostrom

    2008-08-01

    Full Text Available Microbial carbonate precipitation experiments were conducted using the archaeon bacteria Archaeoglobus fulgidus to determine chemical and isotopic fractionation of organic and inorganic carbon into mineral phases. Carbonate precipitation was induced in two different experiments using A. fulgidus to determine the relative abundance of organically derived carbon incorporated into carbonate minerals as well as to define any distinct phases or patterns that could be attributed to the precipitation process. One experiment used a medium containing 13C-depleted organic carbon and 13C-enriched inorganic carbon, and the other used a 14C-labeled organic carbon source. Results indicated that 0.9–24.8% organic carbon was incorporated into carbonates precipitated by A. fulgidus and that this process was mediated primarily by pH and CO2 emission from cells. Data showed that the carbon in the CO2 produced from this microorganism is incorporated into carbonates and that the rate at which precipitation occurs and the dynamics of the carbonate precipitation process are strongly mediated by the specific steps involved in the biochemical process for lactate oxidation by A. fulgidus.

  17. Carbonate precipitation by the thermophilic archaeon Archaeoglobus fulgidus: A model of carbon flow for an ancient microorganism

    Science.gov (United States)

    Robbins, L.L.; Van Cleave, K. A.; Ostrom, P.

    2008-01-01

    Microbial carbonate precipitation experiments were conducted using the archaeon bacteria Archaeoglobus fulgidus to determine chemical and isotopic fractionation of organic and inorganic carbon into mineral phases. Carbonate precipitation was induced in two different experiments using A. fulgidus to determine the relative abundance of organically derived carbon incorporated into carbonate minerals as well as to define any distinct phases or patterns that could be attributed to the precipitation process. One experiment used a medium containing 13C-depleted organic carbon and 13C-enriched inorganic carbon, and the other used a 14C-labeled organic carbon source. Results indicated that 0.9 - 24.8% organic carbon was incorporated into carbonates precipitated by A. fulgidus and that this process was mediated primarily by pH and CO2 emission from cells. Data showed that the carbon in the CO2 produced from this microorganism is incorporated into carbonates and that the rate at which precipitation occurs and the dynamics of the carbonate precipitation process are strongly mediated by the specific steps involved in the biochemical process for lactate oxidation by A. fulgidus.

  18. Phase Stability under Irradiation of Precipitates and Solid Solutions in Model ALloys and in ODS Alloys Relevant for Gen IV

    Energy Technology Data Exchange (ETDEWEB)

    Arthur T. Motta; Robert C. Birtcher

    2007-10-17

    The overall objective of this program is to investigate the irradiation-altered phase stability of oxide precipitates in ODS steels and of model alloy solid solutions of associated systems. This information can be used to determine whether the favorable mechanical propertiies of these steels are maintained under irradiation, thus addressing one of the main materials research issues for this class of steels as identified by the GenIV working groups. The research program will also create fundamental understanding of the irradiation precipitation/dissolution problem by studying a "model" system in which the variables can be controlled and their effects understood individually.

  19. Gold-Iron Oxide Catalyst for CO Oxidation: Effect of Support Structure

    Directory of Open Access Journals (Sweden)

    Hui-Zhen Cui

    2016-03-01

    Full Text Available Gold-iron oxide (Au/FeOx is one of the highly active catalysts for CO oxidation, and is also a typical system for the study of the chemistry of gold catalysis. In this work, two different types of iron oxide supports, i.e., hydroxylated (Fe_OH and dehydrated iron oxide (Fe_O, have been used for the deposition of gold via a deposition-precipitation (DP method. The structure of iron oxide has been tuned by either selecting precipitated pH of 6.7–11.2 for Fe_OH or changing calcination temperature of from 200 to 600 °C for Fe_O. Then, 1 wt. % Au catalysts on these iron oxide supports were measured for low-temperature CO oxidation reaction. Both fresh and used samples have been characterized by multiple techniques including transmission electron microscopy (TEM and high-resolution TEM (HRTEM, X-ray diffraction (XRD, X-ray photoelectron spectroscopy (XPS, X-ray absorption near edge structure (XANES and temperature-programmed reduction by hydrogen (H2-TPR. It has been demonstrated that the surface properties of the iron oxide support, as well as the metal-support interaction, plays crucial roles on the performance of Au/FeOx catalysts in CO oxidation.

  20. Generation of a stochastic precipitation model for the tropical climate

    Science.gov (United States)

    Ng, Jing Lin; Abd Aziz, Samsuzana; Huang, Yuk Feng; Wayayok, Aimrun; Rowshon, MK

    2017-06-01

    A tropical country like Malaysia is characterized by intense localized precipitation with temperatures remaining relatively constant throughout the year. A stochastic modeling of precipitation in the flood-prone Kelantan River Basin is particularly challenging due to the high intermittency of precipitation events of the northeast monsoons. There is an urgent need to have long series of precipitation in modeling the hydrological responses. A single-site stochastic precipitation model that includes precipitation occurrence and an intensity model was developed, calibrated, and validated for the Kelantan River Basin. The simulation process was carried out separately for each station without considering the spatial correlation of precipitation. The Markov chains up to the fifth-order and six distributions were considered. The daily precipitation data of 17 rainfall stations for the study period of 1954-2013 were selected. The results suggested that second- and third-order Markov chains were suitable for simulating monthly and yearly precipitation occurrences, respectively. The fifth-order Markov chain resulted in overestimation of precipitation occurrences. For the mean, distribution, and standard deviation of precipitation amounts, the exponential, gamma, log-normal, skew normal, mixed exponential, and generalized Pareto distributions performed superiorly. However, for the extremes of precipitation, the exponential and log-normal distributions were better while the skew normal and generalized Pareto distributions tend to show underestimations. The log-normal distribution was chosen as the best distribution to simulate precipitation amounts. Overall, the stochastic precipitation model developed is considered a convenient tool to simulate the characteristics of precipitation in the Kelantan River Basin.

  1. Irrigation enhances precipitation at the mountains downwind

    Directory of Open Access Journals (Sweden)

    J. Jódar

    2010-05-01

    Full Text Available Atmospheric circulation models predict an irrigation-rainfall feedback. However, actual field evidences are very weak. We present strong field evidence about an increase in rainfall at the mountains located downwind of irrigated zones. We chose two regions, located in semiarid southern Spain, where irrigation started at a well defined date, and we analyzed rainfall statistics before and after the beginning of irrigation. Analyzed statistics include the variation of (1 mean rainfall Δ P, (2 ratio of monthly precipitation to annual precipitation Δ r, and (3 number of months with minimum rainfall episodes Δ Pmin after a transition period from unirrigated to irrigated conditions. All of them show statistically significant increases. Δ P and Δ r show larger and more statistically significant variations in June and July. Their variation is proportional to the mean annual water volume applied in the neighboring upwind irrigation lands. Variations in Δ Pmin are statistically significant in the whole summer. That is, the number of months with some rain displays a relevant increase after irrigation. However, increase in rainfall while statistically significant is distributed over a broad region, so that it is of little relevance from a water resources perspective. The joint increment in Δ P and Δ Pmin after the irrigation transition period denotes a net increase in the number of months having a minimum cumulated precipitation in summer.

  2. Characterization of accumulated precipitates during subsurface iron removal

    KAUST Repository

    Van Halem, Doris

    2011-01-01

    The principle of subsurface iron removal for drinking water supply is that aerated water is periodically injected into the aquifer through a tube well. On its way into the aquifer, the injected O2-rich water oxidizes adsorbed Fe 2+, creating a subsurface oxidation zone. When groundwater abstraction is resumed, the soluble Fe 2+ is adsorbed and water with reduced Fe concentrations is abstracted for multiple volumes of the injection water. In this article, Fe accumulation deposits in the aquifer near subsurface treatment wells were identified and characterized to assess the sustainability of subsurface iron removal regarding clogging of the aquifer and the potential co-accumulation of other groundwater constituents, such as As. Chemical extraction of soil samples, with Acid-Oxalate and HNO3, showed that Fe had accumulated at specific depths near subsurface iron removal wells after 12 years of operation. Whether it was due to preferred flow paths or geochemical mineralogy conditions; subsurface iron removal clearly favoured certain soil layers. The total Fe content increased between 11.5 and 390.8 mmol/kg ds in the affected soil layers, and the accumulated Fe was found to be 56-100% crystalline. These results suggest that precipitated amorphous Fe hydroxides have transformed to Fe hydroxides of higher crystallinity. These crystalline, compact Fe hydroxides have not noticeably clogged the investigated well and/or aquifer between 1996 and 2008. The subsurface iron removal wells even need less frequent rehabilitation, as drawdown increases more slowly than in normal production wells. Other groundwater constituents, such as Mn, As and Sr were found to co-accumulate with Fe. Acid extraction and ESEM-EDX showed that Ca occurred together with Fe and by X-ray Powder Diffraction it was identified as calcite. © 2010 Elsevier Ltd. All rights reserved.

  3. High Nitrogen Austenitic Stainless Steel Precipitation During Isothermal Annealing

    Directory of Open Access Journals (Sweden)

    Maria Domankova

    2016-07-01

    Full Text Available The time-temperature-precipitation in high-nitrogen austenitic stainless steel was investigated using light optical microscopy, transmission electron microscopy, selected area diffraction and energy-dispersive X-ray spectroscopy. The isothermal precipitation kinetics curves and the corresponding precipitation activation energy were obtained. The diffusion activation energy of M2N precipitation is 129 kJ/mol. The results show that critical temperature for M2N precipitation is about 825°C with the corresponding incubation period 2.5 min.

  4. Characterization of Strain-Induced Precipitation in Inconel 718 Superalloy

    Science.gov (United States)

    Calvo, Jessica; Penalva, Mariluz; Cabrera, José María

    2016-08-01

    Inconel 718 presents excellent mechanical properties at high temperatures, as well as good corrosion resistance and weldability. These properties, oriented to satisfy the design requirements of gas turbine components, depend on microstructural features such as grain size and precipitation. In this work, precipitation-temperature-time diagrams have been derived based on a stress relaxation technique and the characterization of precipitates by scanning electron microscopy. By using this methodology, the effect of strain accumulation during processing on the precipitation kinetics can be determined. The results show that the characteristics of precipitation are significantly modified when plastic deformation is applied, and the kinetics are slightly affected by the amount of total plastic deformation.

  5. Tritium time series in precipitation of Rm. Valcea, Romania.

    Science.gov (United States)

    Varlam, Carmen; Duliu, Octavian G; Faurescu, Ionut; Vagner, Irina; Faurescu, Denisa

    2016-01-01

    Following tritium concentration records in precipitation for the period 1999-2013 and tritium concentration behaviour during this period for the Ramnicu Valcea (Rm. Valcea) location, the tritium level of individual precipitations of the late spring and summer for the 2009-2013 period was investigated. Despite good correlation between monthly mean tritium concentrations and monthly mean precipitations over the 15-year period of observations (Pearson coefficient 0.87), the individual precipitations had no linear correlation between the tritium concentration and the amount of precipitation.

  6. Precipitation of neptunium dioxide from aqueous solution

    Energy Technology Data Exchange (ETDEWEB)

    Roberts, K E

    1999-12-01

    Tens of thousands of metric tons of highly radioactive, nuclear waste have been generated in the US. Currently, there is no treatment or disposal facility for these wastes. Of the radioactive elements in high-level nuclear waste, neptunium (Np) is of particular concern because it has a long half-life and may potentially be very mobile in groundwaters associated with a proposed underground disposal site at Yucca Mountain, Nevada. Aqueous Np concentrations observed in previous, short-term solubility experiments led to calculated potential doses exceeding proposed long-term regulatory limits. However, thermodynamic data for Np at 25 C showed that these observed aqueous Np concentrations were supersaturated with respect to crystalline NpO{sub 2}. It was hypothesized that NpO{sub 2} is the thermodynamically stable solid phase in aqueous solution, but it is slow to form in an aqueous solution of NpO{sub 2}{sup +} on the time scale of previous experiments. The precipitation of NpO{sub 2} would provide significantly lower aqueous Np concentrations leading to calculated doses below proposed regulatory limits. To test this hypothesis, solubility experiments were performed at elevated temperature to accelerate any slow precipitation kinetics. Ionic NpO{sub 2}{sup +} (aq) was introduced into very dilute aqueous solutions of NaCl with initial pH values ranging from 6 to 10. The reaction vessels were placed in an oven and allowed to react at 200 C until steady-state aqueous Np concentrations were observed. In all cases, aqueous Np concentrations decreased significantly from the initial value of 10{sup {minus}4} M. The solids that formed were analyzed by x-ray powder diffraction, x-ray absorption spectroscopy, and scanning electron microscopy. The solids were determined to be high-purity crystals of NpO{sub 2}. This is the first time that crystalline NpO{sub 2} has been observed to precipitate from NpO{sub 2}{sup +}(aq) in near-neutral aqueous solutions. The results obtained

  7. Stability and precipitation of diverse nanoparticles

    Science.gov (United States)

    Desai, Chintal

    Nanotechnology is a rapidly growing industry that is exploiting the novel characteristics of materials manufactured at the nanoscale. Carbon based nanomaterials such as Carbon Nanotubes (CNTs) and Detonation Nanodiamond (DND) possess unique properties and find a wide range of industrial applications. With the advent of mass production of such materials, there is a possibility of contamination of water resources. Depending on the surface properties and structures, they might aggregate and settle down, or be dispersed and transported by the water. Therefore, there is a need to develop an understanding of the fate of such materials in aqueous media. The understanding and effect of solution chemistry is a key to predicting their deposition, transport, reactivity, and bioavailability in aquatic environments. The colloidal behavior of organic dispersed CNTs and water dispersed DNDs is investigated. The aggregation behavior of these two colloidal systems is quite different from that of hydrophilic, water soluble functionalized CNTs (F-CNTs). The values of the Fuchs stability ratio or the critical coagulant concentration are determined experimentally using time-resolved dynamic light scattering and are used to predict the stability of such systems. It is found that the aggregation behavior of the organic dispersed, antisolvent precipitated system does not follow the conventional Derjaguin--Landau--Verwey-- Overbeek (DLVO) theory. But they stabilize in the long term, which is attributed to the supersaturation generated by different solubility of a solute in the solvent/antisolvent. Based on particle size distribution, zeta potential as well as the aggregation kinetics, the water dispersed DNDs are found to be relatively stable in aqueous solutions, but aggregate rapidly in presence of mono and divalent salts. Also, the formation of carboxylic groups on the DND surface does not alter colloidal behavior as dramatically as it does for other nanocarbons especially carbon

  8. Mucuna pruriens (Konch Beej precipitates manic symptoms

    Directory of Open Access Journals (Sweden)

    Supriya Vaish

    2014-01-01

    Full Text Available Owing to the popular misconception that all ayurvedic preparations are completely safe, a vast majority of these are indiscriminately consumed by people procured as over the counter drugs. These preparations are combinations of multiple products that are often unidentified and dangerous and can precipitate various psychiatric symptoms. Hereby, we present a case of adolescent male in acute manic excitement after consumption of ayurvedic preparation containing "konchbeej" (Mucuna pruriens which is rich in l-3,4 dihydroxyphenyl alanine; precursor of dopamine.

  9. Modeling Tropical Precipitation in a Single Column.

    Science.gov (United States)

    Sobel, Adam H.; Bretherton, Christopher S.

    2000-12-01

    A modified formulation of the traditional single column model for representing a limited area near the equator is proposed. This formulation can also be considered a two-column model in the limit as the area represented by one of the columns becomes very large compared to the other. Only a single column is explicitly modeled, but its free tropospheric temperature, rather than its mean vertical velocity, is prescribed. This allows the precipitation and vertical velocity to be true prognostic variables, as in prior analytical theories of tropical precipitation. Two models developed by other authors are modified according to the proposed formulation. The first is the intermediate atmospheric model of J. D. Neelin and N. Zeng, but with the horizontal connections between columns broken, rendering it a set of disconnected column models. The second is the column model of N. O. Rennó, K. A. Emanuel, and P. H. Stone. In the first model, the set of disconnected column models is run with a fixed temperature that is uniform in the Tropics, and insolation, SST, and surface wind speed taken from a control run of the original model. The column models produce a climatological precipitation field that is grossly similar to that of the control run, despite that the circulation implied by the column models is not required to conserve mass. The addition of horizontal moisture advection by the wind from the control run substantially improves the simulation in dry regions. In the second model the sensitivity of the modeled steady-state precipitation and relative humidity to varying SST and wind speed is examined. The transition from shallow to deep convection is simulated in a `Lagrangian' calculation in which the column model is subjected to an SST that increases in time. In this simulation, the onset of deep convection is delayed to a higher SST than in the steady-state case, due to the effect of horizontal moisture advection (viewed in a Lagrangian reference frame). In both of the

  10. Standardized precipitation index zones for Mexico

    Energy Technology Data Exchange (ETDEWEB)

    Giddings, L.; Soto, M. [Instituto de Ecologia, A.C., Xalapa, Veracruz (Mexico); Rutherford, B.M.; Maarouf, A. [Faculty of Environmental Studies, York University, Toronto, Ontario (Canada)

    2005-01-01

    Precipitation zone systems exists for Mexico based on seasonality, quantity of precipitation, climates and geographical divisions, but none are convenient for the study of the relation of precipitation with phenomena such as El nino. An empirical set of seven exclusively Mexican and six shared zones was derived from three series of Standardized Precipitation Index (SPI) images, from 1940 through 1989: a whole year series (SPI-12) of 582 monthly images, a six month series (SPI-6) of 50 images for winter months (November through April), and a six month series (SPI-6) of 50 images for summer months (May through October). By examination of principal component and unsupervised classification images, it was found that all three series had similar zones. A set of basic training fields chosen from the principal component images was used to classify all three series. The resulting thirteen zones, presented in this article, were found to be approximately similar, varying principally at zones edges. A set of simple zones defined by just a few vertices can be used for practical operations. In general the SPI zones are homogeneous, with almost no mixture of zones and few outliers of one zone in the area of others. They are compared with a previously published map of climatic regions. Potential applications for SPI zones are discussed. [Spanish] Existen varios sistemas de zonificacion de Mexico basados en la estacionalidad, cantidad de precipitacion, climas y divisiones geograficas, pero ninguno es conveniente para el estudio de la relacion de la precipitacion con fenomenos tales como El Nino. En este trabajo se presenta un conjunto de siete zonas empiricas exclusivamente mexicanas y seis compartidas, derivadas de tres series de imagenes de SPI (Indice Estandarizado de la Precipitacion), desde 1940 a 1989: una serie de 582 imagenes mensuales (SPI-12), una series de 50 imagenes (SPI-6) de meses de invierno (noviembre a abril), y otra de 50 imagenes (SPI-6) de meses de verano

  11. Duodenal Perforation Precipitated by Scrub Typhus.

    Science.gov (United States)

    Rajat, Raghunath; Deepu, David; Jonathan, Arul Jeevan; Prabhakar, Abhilash Kundavaram Paul

    2015-01-01

    Scrub typhus is an acute febrile illness usually presenting with fever, myalgia, headache, and a pathognomonic eschar. Severe infection may lead to multiple organ failure and death. Gastrointestinal tract involvement in the form of gastric mucosal erosions and ulcerations owing to vasculitis resulting in gastrointestinal bleeding is common. This process may worsen a pre-existent asymptomatic peptic ulcer, causing duodenal perforation, and present as an acute abdomen requiring surgical exploration. We report the case of a patient with no previous symptoms or risk factors for a duodenal ulcer, who presented with an acute duodenal perforation, probably precipitated by scrub typhus infection.

  12. Duodenal perforation precipitated by scrub typhus

    Directory of Open Access Journals (Sweden)

    Raghunath Rajat

    2015-01-01

    Full Text Available Scrub typhus is an acute febrile illness usually presenting with fever, myalgia, headache, and a pathognomonic eschar. Severe infection may lead to multiple organ failure and death. Gastrointestinal tract involvement in the form of gastric mucosal erosions and ulcerations owing to vasculitis resulting in gastrointestinal bleeding is common. This process may worsen a pre-existent asymptomatic peptic ulcer, causing duodenal perforation, and present as an acute abdomen requiring surgical exploration. We report the case of a patient with no previous symptoms or risk factors for a duodenal ulcer, who presented with an acute duodenal perforation, probably precipitated by scrub typhus infection.

  13. Anhydrite precipitation in seafloor hydrothermal systems

    Science.gov (United States)

    Theissen-Krah, Sonja; Rüpke, Lars H.

    2016-04-01

    The composition and metal concentration of hydrothermal fluids venting at the seafloor is strongly temperature-dependent and fluids above 300°C are required to transport metals to the seafloor (Hannington et al. 2010). Ore-forming hydrothermal systems and high temperature vents in general are often associated with faults and fracture zones, i.e. zones of enhanced permeabilities that act as channels for the uprising hydrothermal fluid (Heinrich & Candela, 2014). Previous numerical models (Jupp and Schultz, 2000; Andersen et al. 2015) however have shown that high permeabilities tend to decrease fluid flow temperatures due to mixing with cold seawater and the resulting high fluid fluxes that lead to short residence times of the fluid near the heat source. A possible mechanism to reduce the permeability and thereby to focus high temperature fluid flow are mineral precipitation reactions that clog the pore space. Anhydrite for example precipitates from seawater if it is heated to temperatures above ~150°C or due to mixing of seawater with hydrothermal fluids that usually have high Calcium concentrations. We have implemented anhydrite reactions (precipitation and dissolution) in our finite element numerical models of hydrothermal circulation. The initial results show that the precipitation of anhydrite efficiently alters the permeability field, which affects the hydrothermal flow field as well as the resulting vent temperatures. C. Andersen et al. (2015), Fault geometry and permeability contrast control vent temperatures at the Logatchev 1 hydrothermal field, Mid-Atlantic Ridge, Geology, 43(1), 51-54. M. D. Hannington et al. (2010), Modern Sea-Floor Massive Sulfides and Base Metal Resources: Toward an Estimate of Global Sea-Floor Massive Sulfide Potential, in The Challenge of Finding New Mineral Resources: Global Metallogeny, Innovative Exploration, and New Discoveries, edited by R. J. Goldfarb, E. E. Marsh and T. Monecke, pp. 317-338, Society of Economic Geologists

  14. Global warming without global mean precipitation increase?

    OpenAIRE

    Salzmann, Marc

    2016-01-01

    Global climate models simulate a robust increase of global mean precipitation of about 1.5 to 2% per kelvin surface warming in response to greenhouse gas (GHG) forcing. Here, it is shown that the sensitivity to aerosol cooling is robust as well, albeit roughly twice as large. This larger sensitivity is consistent with energy budget arguments. At the same time, it is still considerably lower than the 6.5 to 7% K−1 decrease of the water vapor concentration with cooling from anthropogenic aeroso...

  15. Study of method for synthetic precipitation data for ungauged sites using quantitative precipitation model

    Science.gov (United States)

    Bae, Hyo-Jun; Oh, Jai-Ho

    2017-08-01

    A method was developed to estimate a synthetic precipitation record for ungauged sites using irregular coarse observations. The proposed synthetic precipitation data were produced with ultrahigh hourly resolution on a regular 1 × 1 km grid. The proposed method was used to analyze selected real-time observational data collected in South Korea from 2010 to the end of 2014. The observed precipitation data were measured using the Automatic Weather System and Automated Synoptic Observing System. The principal objective of the proposed method was to estimate the additional effects of orography on precipitation introduced by ultrahigh- resolution (1 × 1 km) topography provided by a digital elevation model. The Global Forecast System analysis of the National Centers for Environmental Prediction was used for the upper-atmospheric conditions, necessary for estimating the orographic effects. Precipitation data from 48 of the more than 600 observation sites used in the study, which matched the grid points of the synthetic data, were not included in the synthetic data estimation. Instead, these data were used to evaluate the proposed method by direct comparison with the real observations at these sites. A bias score was investigated by comparison of the synthetic precipitation data with the observations. In this comparison, the number of Hit, False, Miss, and Correct results for 2010-2014 was 74738, 25778, 7544, and 367981, respectively. In the Hit cases, the bias score was 1.22 and the correlation coefficient was 0.74. The means of the differences between the synthetic data and the observations were 0.3, -3.9, -14.4, and -34.9 mm h-1 and the root mean square errors (RMSEs) were 2.7, 8.3, 19.3, and 39.6 mm h-1 for the categories of 0.5-10.0, 10.0-30.0, 30.0-50.0, and 50.0-100.0 mm h-1, respectively. In addition, in each range, the 60% difference between the synthetic precipitation data and the observation data was -1.5 to +1.5, -5.0 to +5.0, -17.0 to +17.0, and -33.0 to +33

  16. Cross-track sensor precipitation retrievals for the Global Precipitation Measurement mission

    Science.gov (United States)

    Kidd, Chris; Randel, David; Stocker, Erich; Kummerow, Christian

    2014-05-01

    The utilization of observations from passive microwave cross-track, or sounders, for global precipitation estimation provides a number of distinct advantages including the potential to retrieve precipitation over cold surface backgrounds and improvements in temporal sampling. As part of the Global Precipitation Measurement (GPM) mission, observations from these cross-track instruments are being incorporated into the overall retrieval framework to enable better temporal and spatial sampling, particularly over regions where surface conditions provide a challenging background against which to observe precipitation. GPM is an international satellite mission and brings together a number of different component satellites and sensors, each contributing observations capable of providing information on precipitation. The joint US-Japan core observatory was launched in early 2014 and carries the GPM Microwave Imager (GMI) and the Dual-frequency Precipitation Radar (DPR). The core observatory serves as a standard against which other sensors in the constellation are calibrated, providing a consistent observational dataset to ensure the highest quality precipitation retrievals to be made. The conically-scanning GMI provides observations from 10.65 GHz through to 166 GHz with dual polarization capabilities, and two 183 GHz channels (+-1 and +-3 GHz) with vertical polarization. The highest frequencies provide resolutions in the order of 4.4x7.3 km. 885 km swath width. The DPR operates at 35.5 GHz and 13.6 GHz with swath widths 120 and 245 km respectively, and a vertical resolution of 250 m. The higher frequency radar will provide a sensitivity down to 12 dBZ, or about 0.2 mmh-1 equivalent rainrate, particularly useful for higher latitudes where light precipitation dominates. Integration of the cross-track sensors into the overall retrieval scheme of the GPM mission is achieved through the GPROF retrieval scheme, utilizing databases based upon observational and modelled data sets

  17. Rare earth element partitioning between hydrous ferric oxides and acid mine water during iron oxidation

    Science.gov (United States)

    Verplanck, P.L.; Nordstrom, D.K.; Taylor, H.E.; Kimball, B.A.

    2004-01-01

    Ferrous iron rapidly oxidizes to Fe (III) and precipitates as hydrous Fe (III) oxides in acid mine waters. This study examines the effect of Fe precipitation on the rare earth element (REE) geochemistry of acid mine waters to determine the pH range over which REEs behave conservatively and the range over which attenuation and fractionation occur. Two field studies were designed to investigate REE attenuation during Fe oxidation in acidic, alpine surface waters. To complement these field studies, a suite of six acid mine waters with a pH range from 1.6 to 6.1 were collected and allowed to oxidize in the laboratory at ambient conditions to determine the partitioning of REEs during Fe oxidation and precipitation. Results from field experiments document that even with substantial Fe oxidation, the REEs remain dissolved in acid, sulfate waters with pH below 5.1. Between pH 5.1 and 6.6 the REEs partitioned to the solid phases in the water column, and heavy REEs were preferentially removed compared to light REEs. Laboratory experiments corroborated field data with the most solid-phase partitioning occurring in the waters with the highest pH. ?? 2004 Elsevier Ltd. All rights reserved.

  18. Errors and Correction of Precipitation Measurements in China

    Institute of Scientific and Technical Information of China (English)

    REN Zhihua; LI Mingqin

    2007-01-01

    In order to discover the range of various errors in Chinese precipitation measurements and seek a correction method, 30 precipitation evaluation stations were set up countrywide before 1993. All the stations are reference stations in China. To seek a correction method for wind-induced error, a precipitation correction instrument called the "horizontal precipitation gauge" was devised beforehand. Field intercomparison observations regarding 29,000 precipitation events have been conducted using one pit gauge, two elevated operational gauges and one horizontal gauge at the above 30 stations. The range of precipitation measurement errors in China is obtained by analysis of intercomparison measurement results. The distribution of random errors and systematic errors in precipitation measurements are studied in this paper.A correction method, especially for wind-induced errors, is developed. The results prove that a correlation of power function exists between the precipitation amount caught by the horizontal gauge and the absolute difference of observations implemented by the operational gauge and pit gauge. The correlation coefficient is 0.99. For operational observations, precipitation correction can be carried out only by parallel observation with a horizontal precipitation gauge. The precipitation accuracy after correction approaches that of the pit gauge. The correction method developed is simple and feasible.

  19. [A new precipitation distribution hydrological model and its application].

    Science.gov (United States)

    Zhang, Shengtang; Kang, Shaozhong; Liu, Yin

    2005-03-01

    In distribution hydrological models, precipitation is the key input data for analyzing and computing hydrological processes. Finding a way to produce distribution precipitation data is a hotspot in hydrological research. This paper presented the hypothesis that the distribution of precipitation on the earth surface is the result of the effects of atmosphere system and terrain. Moreover, the spatial distribution of natural precipitation is a group of concentric ovals on the flat earth surface, and has a definite centre with maximum precipitation not affected by terrain. Supporting by the hypothesis, this paper established a new precipitation distribution hydrological model which could simulate the spatial distribution of precipitation, and modified the terrain effect on precipitation through Newton interpolation. The position of the precipitation centre and its precipitation amount were simulated in first time, and thus, the model could have a practical value in basin storm analysis and real-time runoff forecasting. The model was tested by the precipitation data of the Xichuan river basin in the Loess Plateau, which indicated that the model had a high precision.

  20. Uncertainty Estimation of Global Precipitation Measurement through Objective Validation Strategy

    Science.gov (United States)

    KIM, H.; Utsumi, N.; Seto, S.; Oki, T.

    2014-12-01

    Since Tropical Rainfall Measuring Mission (TRMM) has been launched in 1997 as the first satellite mission dedicated to measuring precipitation, the spatiotemporal gaps of precipitation observation have been filled significantly. On February 27th, 2014, Dual-frequency Precipitation Radar (DPR) satellite has been launched as a core observatory of Global Precipitation Measurement (GPM), an international multi-satellite mission aiming to provide the global three hourly map of rainfall and snowfall. In addition to Ku-band, Ka-band radar is newly equipped, and their combination is expected to introduce higher precision than the precipitation measurement of TRMM/PR. In this study, the GPM level-2 orbit products are evaluated comparing to various precipitation observations which include TRMM/PR, in-situ data, and ground radar. In the preliminary validation over intercross orbits of DPR and TRMM, Ku-band measurements in both satellites shows very close spatial pattern and intensity, and the DPR is capable to capture broader range of precipitation intensity than of the TRMM. Furthermore, we suggest a validation strategy based on 'objective classification' of background atmospheric mechanisms. The Japanese 55-year Reanalysis (JRA-55) and auxiliary datasets (e.g., tropical cyclone best track) is used to objectively determine the types of precipitation. Uncertainty of abovementioned precipitation products is quantified as their relative differences and characterized for different precipitation mechanism. Also, it is discussed how the uncertainty affects the synthesis of TRMM and GPM for a long-term satellite precipitation observation records which is internally consistent.