WorldWideScience

Sample records for metallicity distribution functions

  1. METALLICITY DISTRIBUTION FUNCTIONS OF FOUR LOCAL GROUP DWARF GALAXIES

    Energy Technology Data Exchange (ETDEWEB)

    Ross, Teresa L.; Holtzman, Jon [Department of Astronomy, New Mexico State University, P.O. Box 30001, MSC 4500, Las Cruces, NM 88003-8001 (United States); Saha, Abhijit [NOAO, 950 Cherry Avenue, Tucson, AZ 85726-6732 (United States); Anthony-Twarog, Barbara J., E-mail: rosst@nmsu.edu, E-mail: holtz@nmsu.edu, E-mail: bjat@ku.edu [Department of Physics and Astronomy, University of Kansas, Lawrence, KS 66045-7582 (United States)

    2015-06-15

    We present stellar metallicities in Leo I, Leo II, IC 1613, and Phoenix dwarf galaxies derived from medium (F390M) and broad (F555W, F814W) band photometry using the Wide Field Camera 3 instrument on board the Hubble Space Telescope. We measured metallicity distribution functions (MDFs) in two ways, (1) matching stars to isochrones in color–color diagrams and (2) solving for the best linear combination of synthetic populations to match the observed color–color diagram. The synthetic technique reduces the effect of photometric scatter and produces MDFs 30%–50% narrower than the MDFs produced from individually matched stars. We fit the synthetic and individual MDFs to analytical chemical evolution models (CEMs) to quantify the enrichment and the effect of gas flows within the galaxies. Additionally, we measure stellar metallicity gradients in Leo I and II. For IC 1613 and Phoenix our data do not have the radial extent to confirm a metallicity gradient for either galaxy. We find the MDF of Leo I (dwarf spheroidal) to be very peaked with a steep metal-rich cutoff and an extended metal-poor tail, while Leo II (dwarf spheroidal), Phoenix (dwarf transition), and IC 1613 (dwarf irregular) have wider, less peaked MDFs than Leo I. A simple CEM is not the best fit for any of our galaxies; therefore we also fit the “Best Accretion Model” of Lynden-Bell. For Leo II, IC 1613, and Phoenix we find similar accretion parameters for the CEM even though they all have different effective yields, masses, star formation histories, and morphologies. We suggest that the dynamical history of a galaxy is reflected in the MDF, where broad MDFs are seen in galaxies that have chemically evolved in relative isolation and narrowly peaked MDFs are seen in galaxies that have experienced more complicated dynamical interactions concurrent with their chemical evolution.

  2. Charge distributions in metallic alloys: a charge-excess functional theory approach.

    Science.gov (United States)

    Bruno, Ezio; Zingales, Leon; Wang, Yang

    2003-10-17

    The distribution of local charge (DLC) excesses in metallic alloys, previously obtained as a result of the analysis of order N electronic structure calculations, is derived from a variational principle. A phenomenological charge-excess functional theory is obtained which is determined by three concentration dependent, material specific parameters that can be obtained from ab initio calculations. The theory requires modest computational efforts and reproduces with an excellent accuracy the DLC and the electrostatic energies of ordered, substitutionally disordered, or segregating metallic alloys and, hence, can be considered an efficient approach alternative to conventional electronic structure calculations. The substantial reduction of computing time opens new perspectives for the understanding of metallic systems and their mechanical properties.

  3. Revealing the spiral arms through radial migration and the shape of the metallicity distribution function

    Science.gov (United States)

    Martinez-Medina, L. A.; Pichardo, B.; Moreno, E.; Peimbert, A.

    2016-11-01

    Recent observations show that the Milky Way's metallicity distribution function (MDF) changes its shape as a function of radius. This new evidence of radial migration within the stellar disc sets additional constraints on Galactic models. By performing controlled test particle simulations in a very detailed, observationally motivated model of the Milky Way, we demonstrate that, in the inner region of the disc, the MDF is shaped by the joint action of the bar and spiral arms, while at outer radii the MDF is mainly shaped by the spiral arms. We show that the spiral arms are able to imprint their signature in the radial migration, shaping the MDF in the outskirts of the Galactic disc with a minimal participation of the bar. Conversely, this work has the potential to characterize some structural and dynamical parameters of the spiral arms based on radial migration and the shape of the MDF. Finally, the resemblance obtained with this approximation to the MDF curves of the Galaxy as seen by APOGEE, show that a fundamental factor influencing their shape is the Galactic potential.

  4. POPULATION EFFECTS ON THE METALLICITY DISTRIBUTION FUNCTION DERIVED FROM THE RED GIANT BRANCH

    International Nuclear Information System (INIS)

    Ordoñez, Antonio J.; Sarajedini, Ata

    2015-01-01

    We have tested the reliability of the red giant branch (RGB) as a metallicity indicator accounting for observational errors as well as the complexity of star formation histories and chemical evolution histories observed in various stellar systems. We generate model color–magnitude diagrams (CMDs) produced with a variety of evolutionary histories and compare the resultant metallicity estimates from the colors and magnitudes of RGB stars to the true input metallicities. We include realistic models for photometric errors and completeness in our synthetic CMDs. As expected, for simple simple stellar populations dominated by old stars, the RGB provides a very accurate estimate of the modular metallicity value for a population. An error in the age of a system targeted for this type of study may produce metallicity errors of a few tenths of a dex. The size of this metallicity error depends linearly on the age error, and we find this dependence to be stronger with more precise photometry. If the population has experienced any significant star formation within the last ∼6 Gyr, the metallicity estimates, [M/H], derived from the RGB may be in error by up to ∼0.5 dex. Perhaps the most important consideration for this technique is an accurate, independent estimate of the average age for the target stellar system, especially if it is probable that a significant fraction of the population formed less than ∼6 Gyr ago

  5. Optical emission spectroscopy of metal-halide lamps: Radially resolved atomic state distribution functions of Dy and Hg

    Science.gov (United States)

    Nimalasuriya, T.; Flikweert, A. J.; Stoffels, W. W.; Haverlag, M.; van der Mullen, J. J. A. M.; Pupat, N. B. M.

    2006-03-01

    Absolute line intensity measurements are performed on a metal-halide lamp. Several transitions of atomic and ionic Dy and atomic Hg are measured at different radial positions from which we obtain absolute atomic and ionic Dy intensity profiles. From these profiles we construct the radially resolved atomic state distribution function (ASDF) of the atomic and ionic Dy and the atomic Hg. From these ASDFs several quantities are determined as functions of radial position, such as the (excitation) temperature, the ion ratio Hg+/Dy+, the electron density, the ground state, and the total density of Dy atoms and ions. Moreover, these ASDFs give us insight about the departure from equilibrium. The measurements show a hollow density profile for the atoms and the ionization of atoms in the center. In the outer parts of the lamp molecules dominate.

  6. Applications of Total Scattering & Pair Distribution Function Analysis in Metal-Organic Framework Materials

    DEFF Research Database (Denmark)

    Xu, Hui; Birgisson, Steinar; Sommer, Sanna

    Metal-Organic Frameworks (MOFs) is constructed by metal-oxide nodes and organic ligands. The formation of different structures of metal-oxide nodes (also called secondary building units, SBU) is crucial for MOF final structures, because the connectivity of SBU greatly influence the final MOF...... structure. At the same time, there is an ongoing debate on whether the SBU is present prior, or during MOF crystallization in MOF chemistry. However, little is known about MOFs formation mechanism. Currently techniques to study the in situ MOF formation process mainly focused on after......-crystallization process, for example in situ XRD and SAXS/WAXS study on MOF formation. However, the pre-crystallization process in the early stage of MOF formation is still unexplored. In this project, total scattering and PDF study will be carried out to explore the MOF formation process in early stage. This includes...

  7. Spatially resolved distribution function and the medium-range order in metallic liquid and glass

    Energy Technology Data Exchange (ETDEWEB)

    Fang, Xiaowei; Wang, Cai-Zhuang; Hao, Shaogang; Kramer, Matthew; Yao, Yongxin; Mendelev, Mikhail; Napolitano, Ralph; Ho, Kai-Ming

    2011-12-23

    The structural description of disordered systems has been a longstanding challenge in physical science. We propose an atomic cluster alignment method to reveal the development of three-dimensional topological ordering in a metallic liquid as it undercools to form a glass. By analyzing molecular dynamic (MD) simulation trajectories of a Cu{sub 64.5}Zr{sub 35.5} alloy, we show that medium-range order (MRO) develops in the liquid as it approaches the glass transition. Specifically, around Cu sites, we observe 'Bergman triacontahedron' packing (icosahedron, dodecahedron and icosahedron) that extends out to the fourth shell, forming an interpenetrating backbone network in the glass. The discovery of Bergman-type MRO from our order-mining technique provides unique insights into the topological ordering near the glass transition and the relationship between metallic glasses and quasicrystals.

  8. Spatially resolved distribution function and the medium-range order in metallic liquid and glass.

    Science.gov (United States)

    Fang, X W; Wang, C Z; Hao, S G; Kramer, M J; Yao, Y X; Mendelev, M I; Ding, Z J; Napolitano, R E; Ho, K M

    2011-01-01

    The structural description of disordered systems has been a longstanding challenge in physical science. We propose an atomic cluster alignment method to reveal the development of three-dimensional topological ordering in a metallic liquid as it undercools to form a glass. By analyzing molecular dynamic (MD) simulation trajectories of a Cu(64.5)Zr(35.5) alloy, we show that medium-range order (MRO) develops in the liquid as it approaches the glass transition. Specifically, around Cu sites, we observe "Bergman triacontahedron" packing (icosahedron, dodecahedron and icosahedron) that extends out to the fourth shell, forming an interpenetrating backbone network in the glass. The discovery of Bergman-type MRO from our order-mining technique provides unique insights into the topological ordering near the glass transition and the relationship between metallic glasses and quasicrystals.

  9. Relationships between the distribution of O atoms on partially oxidized metal (Al, Ag, Cu, Ti, Zr, Hf) surfaces and the adsorption energy: A density-functional theory study

    Science.gov (United States)

    Houska, J.; Kozak, T.

    2017-06-01

    We investigate the oxidation of selected metal (Al, Ag, Cu, Ti, Zr, and Hf) surfaces by the density functional theory. We go through a wide range of (233 per metal) distributions of O atoms on a partially oxidized metal surface. First, we focus on the qualitative information whether the preferred distribution of O atoms is heterogeneous (stoichiometric oxide + metal) or homogeneous (substoichiometric oxide). We find that the former is energetically preferred, e.g., for Al, while the latter is energetically preferred, e.g., for Ti, Zr, and Hf. Second, we provide the quantitative values of adsorption energies corresponding to the energetically preferred O atom distributions for various partial coverages of various metals by O. Third, we discuss and show an example of implications of the aforementioned findings for the understanding and simulations of sputtering.

  10. Functional memory metals

    International Nuclear Information System (INIS)

    Dunne, D.P.

    2000-01-01

    The field of shape memory phenomena in metals and alloys has developed in a sporadic fashion from a scientific curiosity to a vigorously growing niche industry, over a period close to a full working lifetime. Memory metal research and development is replete with scientist and engineer 'true believers', who can finally feel content that their longstanding confidence in the potential of these unusual functional materials has not been misplaced. This paper reviews the current range of medical and non-medical systems and devices which are based on memory metals and attempts to predict trends in applications over the next decade. The market is dominated by Ni Ti alloys which have proved to exhibit the best and most reproducible properties for application in a wide range of medical and non-medical devices

  11. Nuclear Parton Distribution Functions

    Energy Technology Data Exchange (ETDEWEB)

    I. Schienbein, J.Y. Yu, C. Keppel, J.G. Morfin, F. Olness, J.F. Owens

    2009-06-01

    We study nuclear effects of charged current deep inelastic neutrino-iron scattering in the framework of a {chi}{sup 2} analysis of parton distribution functions (PDFs). We extract a set of iron PDFs which are used to compute x{sub Bj}-dependent and Q{sup 2}-dependent nuclear correction factors for iron structure functions which are required in global analyses of free nucleon PDFs. We compare our results with nuclear correction factors from neutrino-nucleus scattering models and correction factors for charged-lepton--iron scattering. We find that, except for very high x{sub Bj}, our correction factors differ in both shape and magnitude from the correction factors of the models and charged-lepton scattering.

  12. Influence of icosahedral order on the second peak splitting of pair distribution function for Mg{sub 70}Zn{sub 30} metallic glass

    Energy Technology Data Exchange (ETDEWEB)

    Liang, Yong-Chao [School of Physics and Microelectronics Science, Hunan University, Changsha 410082 (China); Liu, Rang-Su, E-mail: liurangsu@sina.com [School of Physics and Microelectronics Science, Hunan University, Changsha 410082 (China); Mo, Yun-Fei [School of Physics and Microelectronics Science, Hunan University, Changsha 410082 (China); Liu, Hai-Rong [College of Materials Science and Engineering, Hunan University, Changsha 410082 (China); Tian, Ze-An; Zhou, Qun-yi [School of Physics and Microelectronics Science, Hunan University, Changsha 410082 (China); Zhang, Hai-Tao [School of Physics and Microelectronics Science, Hunan University, Changsha 410082 (China); Department of Physics, Changsha University, Changsha 410022 (China); Zhou, Li-Li [Department of Information Engineering, Gannan Medical University, Ganzhou 341000 (China); Hou, Zhao-Yang [Department of Applied Physics, Chang’an University, Xi’an 710064 (China); Peng, Ping [College of Materials Science and Engineering, Hunan University, Changsha 410082 (China)

    2014-06-01

    Highlights: • The rapid solidification of liquid Mg{sub 70}Zn{sub 30} has been investigated by MD simulation. • The atomic configurations have been deeply analyzed by several microscopic methods. • Geometry analysis is for the icosahedron and the IS cluster linked of two icosahedra. • The second peak splitting in PDF g(r) curve of Mg{sub 70}Zn{sub 30} alloy has been confirmed. • The R{sub 2}/R{sub 1} = 1.69, R{sub 3}/R{sub 1} = 1.98 and R{sub 4}/R{sub 1} = 2.57, is mainly caused by IS clusters. - Abstract: A simulation study has been performed for the rapid solidification process of Mg{sub 70}Zn{sub 30} metallic glass by using molecular dynamics method. Several structural analysis methods have been adopted to characterize and analyze the atomic configurations in the system. Based on the geometry analysis of the icosahedron and the intercross-shared (IS) cluster linked of two icosahedra, it is confirmed that the second peak splitting in pair distribution function (PDF) g(r) curve of Mg{sub 70}Zn{sub 30} metallic glass is mainly caused by the IS clusters, and its corresponding to R{sub 2}/R{sub 1} = 1.69, R{sub 3}/R{sub 1} = 1.98 and R{sub 4}/R{sub 1} = 2.57, can be reasonably explained.

  13. Atomic Distribution in Catalytic Amorphous Metals

    Directory of Open Access Journals (Sweden)

    Sanghita Mridha

    2015-01-01

    Full Text Available The atomic distribution in catalytically active metallic glass alloys, Pd43Cu27Ni10P20 and Pt57.5Cu14.7Ni5.3P22.5, was investigated using three-dimensional atom probe microscopy. Atom probe analysis showed uniform distribution of constituent elements for both the starting amorphous alloys, with no phase separation. Both the crystallized alloys showed eutectic microstructure with a very sharp interface (~0.5 nm as determined from atom probe. The atomic distribution in the devitrified state is explained based on the “fragile liquid” behavior for these noble-metal glassy alloys.

  14. Structure functions and parton distributions

    International Nuclear Information System (INIS)

    Olness, F.; Tung, Wu-Ki

    1991-04-01

    Activities of the structure functions and parton distributions group is summarized. The impact of scheme-dependence of parton distributions (especially sea-quarks and gluons) on the quantitative formulation of the QCD parton model is highlighted. Recent progress on the global analysis of parton distributions is summarized. Issues on the proper use of the next-to-leading parton distributions are stressed

  15. Asymmetric pair distribution functions in catalysts

    DEFF Research Database (Denmark)

    Clausen, B. S.; Nørskov, Jens Kehlet

    2000-01-01

    it has been realized that often there is a need to use an improved EXAFS data analysis compared to the simple harmonic approach which works well for well-defined bulk structures. This is due to the fact that catalysts contain highly dispersed or disordered structures with pair distribution functions...... of asymmetric pair distribution functions for nano-sized particles and how they influence the structural parameters obtained from the standard data analysis. An alternative method, which takes into account deviations from the Gaussian pair distribution function typically used in the analysis of EXAFS spectra......, will be described. The method is based on an analysis of the pair distribution functions derived from molecular dynamics simulations of small metal particles and its reliability is demonstrated by comparing structural parameters obtained from independent X-ray diffraction experiments....

  16. Studies of helium distribution in metal tritides

    International Nuclear Information System (INIS)

    Bowman, R.C. Jr.; Attalla, A.

    1976-01-01

    The distribution of helium ( 3 He) in LiT, TiT 2 , and UT 3 , which are regarded as representative metal tritides, was investigated using pulse nuclear magnetic resonance (NMR) techniques. Analyses of the NMR lineshapes and nuclear relaxation times indicate the 3 He atoms are trapped in microscopic gas bubbles for each tritide. The effects of concentration and temperature on the 3 He distributions were investigated as well

  17. The probabilistic distribution of metal whisker lengths

    Energy Technology Data Exchange (ETDEWEB)

    Niraula, D., E-mail: Dipesh.Niraula@rockets.utoledo.edu; Karpov, V. G., E-mail: victor.karpov@utoledo.edu [Department of Physics and Astronomy, University of Toledo, Toledo, Ohio 43606 (United States)

    2015-11-28

    Significant reliability concerns in multiple industries are related to metal whiskers, which are random high aspect ratio filaments growing on metal surfaces and causing shorts in electronic packages. We derive a closed form expression for the probabilistic distribution of metal whisker lengths. Our consideration is based on the electrostatic theory of metal whiskers, according to which whisker growth is interrupted when its tip enters a random local “dead region” of a weak electric field. Here, we use the approximation neglecting the possibility of thermally activated escapes from the “dead regions,” which is later justified. We predict a one-parameter distribution with a peak at a length that depends on the metal surface charge density and surface tension. In the intermediate range, it fits well the log-normal distribution used in the experimental studies, although it decays more rapidly in the range of very long whiskers. In addition, our theory quantitatively explains how the typical whisker concentration is much lower than that of surface grains. Finally, it predicts the stop-and-go phenomenon for some of the whiskers growth.

  18. Detailed Mapping of the Local Ir4+ Dimers through the Metal-Insulator Transitions of CuIr2S4 Thiospinel by X-Ray Atomic Pair Distribution Function Measurements

    Science.gov (United States)

    Božin, E. S.; Masadeh, A. S.; Hor, Y. S.; Mitchell, J. F.; Billinge, S. J. L.

    2011-01-01

    The evolution of the short-range structural signature of the Ir4+ dimer state in CuIr2S4 thiospinel has been studied across the metal-insulator phase transitions as the metallic state is induced by temperature, Cr doping, and x-ray fluence. An atomic pair distribution function (PDF) approach reveals that there are no local dimers that survive into the metallic phase when this is invoked by temperature and doping. The PDF shows Ir4+ dimers when they exist, regardless of whether or not they are long-range ordered. At 100 K, exposure to a 98 keV x-ray beam melts the long-range dimer order within a few seconds, though the local dimers remain intact. This shows that the metallic state accessed on warming and doping is qualitatively different from the state obtained under x-ray irradiation.

  19. Detailed mapping of the local Ir{sup 4+} dimers through the metal-insulator transitions of CuIr{sub 2}S{sub 4} thiospinel by x-ray atomic pair distribution function measurements.

    Energy Technology Data Exchange (ETDEWEB)

    Bozin, E. S.; Masadeh, A. S.; Hor, Y. S.; Mitchell, J. F.; Billinge, S. J. L.; Materials Science Division; BNL; Michigan State Univ.; Univ. of Jordan; Columbia Univ.

    2011-01-24

    The evolution of the short-range structural signature of the Ir{sup 4+} dimer state in CuIr{sub 2}S{sub 4} thiospinel has been studied across the metal-insulator phase transitions as the metallic state is induced by temperature, Cr doping, and x-ray fluence. An atomic pair distribution function (PDF) approach reveals that there are no local dimers that survive into the metallic phase when this is invoked by temperature and doping. The PDF shows Ir{sup 4+} dimers when they exist, regardless of whether or not they are long-range ordered. At 100 K, exposure to a 98 keV x-ray beam melts the long-range dimer order within a few seconds, though the local dimers remain intact. This shows that the metallic state accessed on warming and doping is qualitatively different from the state obtained under x-ray irradiation.

  20. Metal uptake and distribution in the zebrafish (

    NARCIS (Netherlands)

    Böhme, Steffi; Baccaro, Marta; Schmidt, Matthias; Potthoff, Annegret; Stärk, Hans Joachim; Reemtsma, Thorsten; Kühnel, Dana

    2017-01-01

    The zebrafish (Danio rerio) embryo (ZFE) is an established test organism for investigating the toxicity of chemicals and is suitable for the assessment of the hazardous potential of nanoparticles. There is little knowledge on metal internalization and distribution in these organisms, as well as

  1. Beam distribution function after filamentation

    Energy Technology Data Exchange (ETDEWEB)

    Raubenheimer, T.O.; Decker, F.J.; Seeman, J.T.

    1995-05-01

    In this paper, the authors calculate the beam distribution function after filamentation (phase-mixing) of a focusing mismatch. This distribution is relevant when interpreting beam measurements and sources of emittance dilution in linear colliders. It is also important when considering methods of diluting the phase space density, which may be required for the machine protection system in future linear colliders, and it is important when studying effects of trapped ions which filament in the electron beam potential. Finally, the resulting distribution is compared with measured beam distributions from the SLAC linac.

  2. Structure functions and parton distributions

    International Nuclear Information System (INIS)

    Martin, A.D.; Stirling, W.J.; Roberts, R.G.

    1995-01-01

    The MRS parton distribution analysis is described. The latest sets are shown to give an excellent description of a wide range of deep-inelastic and other hard scattering data. Two important theoretical issues-the behavior of the distributions at small x and the flavor structure of the quark sea-are discussed in detail. A comparison with the new structure function data from HERA is made, and the outlook for the future is discussed

  3. Autoradiographic techniques to determine noble metal distribution in automotive catalyst substrates

    International Nuclear Information System (INIS)

    Lange, W.H.

    1976-01-01

    The distribution of noble metals in the ceramic substrates of automotive catalytic converter systems is important to the functional characteristics of the systems. A radiotracer technique involving microtomy of bead substrate samples and autoradiography using the resultant thin sections was developed to produce detailed images of the metal distributions. The method is particularly valuable to determine the distribution of one metal in the presence of another to aid in the development of more efficient systems

  4. Metal Distribution and Mobility under alkaline conditions

    International Nuclear Information System (INIS)

    Dario, Maarten

    2004-01-01

    The adsorption of an element, expressed as its distribution between liquid (aquatic) and solid phases in the bio geosphere, largely determines its mobility and transport properties. This is of fundamental importance in the assessment of the performance of e.g. geologic repositories for hazardous elements like radionuclides. Geologic repositories for low and intermediate level nuclear waste will most likely be based on concrete constructions in a suitable bedrock, leading to a local chemical environment with pH well above 12. At this pH metal adsorption is very high, and thus the mobility is hindered. Organic complexing agents, such as natural humic matter from the ground and in the groundwater, as well as components in the waste (cleaning agents, degradation products from ion exchange resins and cellulose, cement additives etc.) would affect the sorption properties of the various elements in the waste. Trace element migration from a cementitious repository through the pH- and salinity gradient created around the repository would be affected by the presence and creation of particulate matter (colloids) that may serve as carriers that enhance the mobility. The objective of this thesis was to describe and quantify the sorption of some selected elements representative of spent nuclear fuel (Eu, Am) and other heavy metals (Zn, Cd, Hg) in a clay/cement environment (pH 10-13) and in the pH-gradient outside this environment. The potential of organic complexing agents and colloids to enhance metal migration was also investigated. It was shown that many organic ligands are able to reduce trace metal sorption under these conditions. It was not possible to calculate the effect of well-defined organic ligands on the metal sorption in a cement environment by using stability constants from the literature. A simple method for comparing the effect of different complexing agents on metal sorption is, however, suggested. The stability in terms of the particle size of suspended

  5. High Resolution Orientation Distribution Function

    DEFF Research Database (Denmark)

    Schmidt, Søren; Gade-Nielsen, Nicolai Fog; Høstergaard, Martin

    2012-01-01

    A new method for reconstructing a High Resolution Orientation Distribution Function (HRODF) from X-ray diffraction data is presented. It is shown that the method is capable of accommodating very localized features, e.g. sharp peaks from recrystallized grains on a background of a texture component...... from the deformed material. The underlying mathematical formalism supports all crystallographic space groups and reduces the problem to solving a (large) set of linear equations. An implementation on multi-core CPUs and Graphical Processing Units (GPUs) is discussed along with an example on simulated...

  6. Spin Density Distribution in Open-Shell Transition Metal Systems: A Comparative Post-Hartree-Fock, Density Functional Theory, and Quantum Monte Carlo Study of the CuCl2 Molecule.

    Science.gov (United States)

    Caffarel, Michel; Giner, Emmanuel; Scemama, Anthony; Ramírez-Solís, Alejandro

    2014-12-09

    We present a comparative study of the spatial distribution of the spin density of the ground state of CuCl2 using Density Functional Theory (DFT), quantum Monte Carlo (QMC), and post-Hartree-Fock wave function theory (WFT). A number of studies have shown that an accurate description of the electronic structure of the lowest-lying states of this molecule is particularly challenging due to the interplay between the strong dynamical correlation effects in the 3d shell and the delocalization of the 3d hole over the chlorine atoms. More generally, this problem is representative of the difficulties encountered when studying open-shell metal-containing molecular systems. Here, it is shown that qualitatively different results for the spin density distribution are obtained from the various quantum-mechanical approaches. At the DFT level, the spin density distribution is found to be very dependent on the functional employed. At the QMC level, Fixed-Node Diffusion Monte Carlo (FN-DMC) results are strongly dependent on the nodal structure of the trial wave function. Regarding wave function methods, most approaches not including a very high amount of dynamic correlation effects lead to a much too high localization of the spin density on the copper atom, in sharp contrast with DFT. To shed some light on these conflicting results Full CI-type (FCI) calculations using the 6-31G basis set and based on a selection process of the most important determinants, the so-called CIPSI approach (Configuration Interaction with Perturbative Selection done Iteratively) are performed. Quite remarkably, it is found that for this 63-electron molecule and a full CI space including about 10(18) determinants, the FCI limit can almost be reached. Putting all results together, a natural and coherent picture for the spin distribution is proposed.

  7. An Empirical Mass Function Distribution

    Science.gov (United States)

    Murray, S. G.; Robotham, A. S. G.; Power, C.

    2018-03-01

    The halo mass function, encoding the comoving number density of dark matter halos of a given mass, plays a key role in understanding the formation and evolution of galaxies. As such, it is a key goal of current and future deep optical surveys to constrain the mass function down to mass scales that typically host {L}\\star galaxies. Motivated by the proven accuracy of Press–Schechter-type mass functions, we introduce a related but purely empirical form consistent with standard formulae to better than 4% in the medium-mass regime, {10}10{--}{10}13 {h}-1 {M}ȯ . In particular, our form consists of four parameters, each of which has a simple interpretation, and can be directly related to parameters of the galaxy distribution, such as {L}\\star . Using this form within a hierarchical Bayesian likelihood model, we show how individual mass-measurement errors can be successfully included in a typical analysis, while accounting for Eddington bias. We apply our form to a question of survey design in the context of a semi-realistic data model, illustrating how it can be used to obtain optimal balance between survey depth and angular coverage for constraints on mass function parameters. Open-source Python and R codes to apply our new form are provided at http://mrpy.readthedocs.org and https://cran.r-project.org/web/packages/tggd/index.html respectively.

  8. Mapping distributed brain function and networks with diffuse optical tomography

    Science.gov (United States)

    Eggebrecht, Adam T.; Ferradal, Silvina L.; Robichaux-Viehoever, Amy; Hassanpour, Mahlega S.; Dehghani, Hamid; Snyder, Abraham Z.; Hershey, Tamara; Culver, Joseph P.

    2014-06-01

    Mapping of human brain function has revolutionized systems neuroscience. However, traditional functional neuroimaging by positron emission tomography or functional magnetic resonance imaging cannot be used when applications require portability, or are contraindicated because of ionizing radiation (positron emission tomography) or implanted metal (functional magnetic resonance imaging). Optical neuroimaging offers a non-invasive alternative that is radiation free and compatible with implanted metal and electronic devices (for example, pacemakers). However, optical imaging technology has heretofore lacked the combination of spatial resolution and wide field of view sufficient to map distributed brain functions. Here, we present a high-density diffuse optical tomography imaging array that can map higher-order, distributed brain function. The system was tested by imaging four hierarchical language tasks and multiple resting-state networks including the dorsal attention and default mode networks. Finally, we imaged brain function in patients with Parkinson's disease and implanted deep brain stimulators that preclude functional magnetic resonance imaging.

  9. A Constant LGRB Metallicity Distribution Across Redshifts < 2.5

    Science.gov (United States)

    Graham, John

    2018-01-01

    Recent improvements in the population of Long-duration Gamma Ray Burst (LGRB) host galaxies with measured metallicities and host masses allows us to investigate how the distributions of both these properties change with redshift. First we examine possible biases in the populations caused by the efficiency of obtaining mass and metallicity measurements at different redshifts. In comparing the redshift distribu- tions of a variety of LGRB populations we find little bias out to a redshift of 2.5 with the exception of a reduced metallicity sampling at redshifts high enough to require a separate IR spectrum (z Graham & Schady (2015) and find good agreement.Having established that the mass and metallicity samples are unbiased we then find a curious consistency in the metallicity distribution across different redshifts. This is at odds with the general evolution in the mass metallicity relation, which becomes progressively more metal poor with increasing redshift. By converting the measured LGRB host masses and redshifts to their expected metallicities, we further find that the LGRB host galaxy mass distribution increase with redshift seen in the Perley et al. (2016) SHOALS sample is consistent with that needed to preserve the LGRB metallicity distribution as the mass metallicity relation decreases with redshift. Furthermore we find that such estimated LGRB host metallicities consistently overestimate the actual measured host metallicities by approximately a quarter dex. This corresponds to about a factor of two in raw metallicity and resolves much of the difference between the LGRB formation metallicity cutoff of about a third solar in Graham & Fruchter (2015) with the cutoff value of solar claimed in Perley et al. (2016) in favor of the former. As LGRB hosts do not follow the general mass metallicity relation, there is no substitute for actually measuring their metallicities!

  10. Distributions and natural levels of related metals in a trophic pathway

    International Nuclear Information System (INIS)

    Lemons, J.D.

    1976-06-01

    The first objective was to test the hypothesis that metal distributions and trends in organisms are, in part, a function of metal positions in the periodic table in unpolluted ecosystems. The data have shown that large soil crustal abundance differences of related elements (e.g. alkali metals) are proportionately approximated in higher organisms. Concentration factors for related nutritious and nonessential and toxic metals were determined along a trophic pathway. When the concentration factors were reported as the concentration of a particular metal by itself, all metal concentrations increased along the trophic pathway. The second objective of this study was to test the hypothesis that distributions and natural levels of chemically related nonessential and toxic metals can better be known when the metals are reported as a ratio, in ash, of the nonessential or toxic metal to its chemically related nutritious metal (e.g. strontium/calcium) as the metals are transferred through trophic pathways. The data have shown that when this method of reporting metal abundances in trophic levels is used, nonessential and toxic metals are discriminated against, relative to their chemically related nutritious metal, as the metals are transferred through the trophic pathway levels. The third objective was designed to test the hypothesis that surface deposition of toxic metals upon plants influences the trends of metal abundances through trophic pathways. This study indicates that metal pollution in the form of deposition upon plant surfaces bypasses the discrimination mechanisms in plants, and consequently elevates the total body burden in herbivores. It is likely that there is no herbivore defense for this type of metal exposure, because herbivores have probably come to rely, in part, upon the discriminatory mechanism of plants throughout the course of evolutionary history to keep toxic metal burdens low

  11. Ab initio work function of elemental metals

    DEFF Research Database (Denmark)

    Skriver, Hans Lomholt; Rosengaard, N. M.

    1992-01-01

    We have used a recently developed self-consistent Green’s-function technique based on tight-binding linear-muffin-tin-orbital theory to calculate the work function for the close-packed surfaces of 37 elemental metals. The results agree with the limited experimental data obtained from single...... crystals to within 15%, and they explain the smooth behavior of the polycrystalline data as a function of atomic number....

  12. Visualizing Metal Content and Intracellular Distribution in Primary Hippocampal Neurons with Synchrotron X-Ray Fluorescence.

    Directory of Open Access Journals (Sweden)

    Robert A Colvin

    Full Text Available Increasing evidence suggests that metal dyshomeostasis plays an important role in human neurodegenerative diseases. Although distinctive metal distributions are described for mature hippocampus and cortex, much less is known about metal levels and intracellular distribution in individual hippocampal neuronal somata. To solve this problem, we conducted quantitative metal analyses utilizing synchrotron radiation X-Ray fluorescence on frozen hydrated primary cultured neurons derived from rat embryonic cortex (CTX and two regions of the hippocampus: dentate gyrus (DG and CA1. Comparing average metal contents showed that the most abundant metals were calcium, iron, and zinc, whereas metals such as copper and manganese were less than 10% of zinc. Average metal contents were generally similar when compared across neurons cultured from CTX, DG, and CA1, except for manganese that was larger in CA1. However, each metal showed a characteristic spatial distribution in individual neuronal somata. Zinc was uniformly distributed throughout the cytosol, with no evidence for the existence of previously identified zinc-enriched organelles, zincosomes. Calcium showed a peri-nuclear distribution consistent with accumulation in endoplasmic reticulum and/or mitochondria. Iron showed 2-3 distinct highly concentrated puncta only in peri-nuclear locations. Notwithstanding the small sample size, these analyses demonstrate that primary cultured neurons show characteristic metal signatures. The iron puncta probably represent iron-accumulating organelles, siderosomes. Thus, the metal distributions observed in mature brain structures are likely the result of both intrinsic neuronal factors that control cellular metal content and extrinsic factors related to the synaptic organization, function, and contacts formed and maintained in each region.

  13. Asymptotic functions and multiplication of distributions

    International Nuclear Information System (INIS)

    Todorov, T.D.

    1979-01-01

    Considered is a new type of generalized asymptotic functions, which are not functionals on some space of test functions as the Schwartz distributions. The definition of the generalized asymptotic functions is given. It is pointed out that in future the particular asymptotic functions will be used for solving some topics of quantum mechanics and quantum theory

  14. Empirical distribution function under heteroscedasticity

    Czech Academy of Sciences Publication Activity Database

    Víšek, Jan Ámos

    2011-01-01

    Roč. 45, č. 5 (2011), s. 497-508 ISSN 0233-1888 Grant - others:GA UK(CZ) GA402/09/0557 Institutional research plan: CEZ:AV0Z10750506 Keywords : Robustness * Convergence * Empirical distribution * Heteroscedasticity Subject RIV: BB - Applied Statistics, Operational Research Impact factor: 0.724, year: 2011 http://library.utia.cas.cz/separaty/2011/SI/visek-0365534.pdf

  15. A Photographic View of Cumulative Distribution Functions

    Science.gov (United States)

    Jernigan, Robert W.

    2008-01-01

    This article shows a concrete and easy recognizable view of a cumulative distribution function(cdf). Photograph views of the search tabs on dictionaries are used to increase students' understanding and facility with the concept of a cumulative distribution function. Projects for student investigations are also given. This motivation and view helps…

  16. Recommended values of clean metal surface work functions

    International Nuclear Information System (INIS)

    Derry, Gregory N.; Kern, Megan E.; Worth, Eli H.

    2015-01-01

    A critical review of the experimental literature for measurements of the work functions of clean metal surfaces of single-crystals is presented. The tables presented include all results found for low-index crystal faces except cases that were known to be contaminated surfaces. These results are used to construct a recommended value of the work function for each surface examined, along with an uncertainty estimate for that value. The uncertainties are based in part on the error distribution for all measured work functions in the literature, which is included here. The metals included in this review are silver (Ag), aluminum (Al), gold (Au), copper (Cu), iron (Fe), iridium (Ir), molybdenum (Mo), niobium (Nb), nickel (Ni), palladium (Pd), platinum (Pt), rhodium (Rh), ruthenium (Ru), tantalum (Ta), and tungsten (W)

  17. Fog droplet distribution functions for lidar.

    Science.gov (United States)

    Mallow, J V

    1982-04-15

    The interpretation of lidar data on fog has been limited by two obstacles: approximations in the form of the Mie scattering cross sections for water droplets, and droplet size distribution functions whose relationship to the experiment has not been clear. This paper develops a method for generating distribution functions from experimental data. These functions are then used with newly available Mie cross sections to obtain backscattering and extinction coefficients for singly scattered ruby laser pulses in fog. The results show what experimental lidar accuracies are needed to uniquely determine fog droplet size distribution.

  18. The metallicity distribution of bulge clump giants in Baade's window

    Science.gov (United States)

    Hill, V.; Lecureur, A.; Gómez, A.; Zoccali, M.; Schultheis, M.; Babusiaux, C.; Royer, F.; Barbuy, B.; Arenou, F.; Minniti, D.; Ortolani, S.

    2011-10-01

    Aims: We seek to constrain the formation of the Galactic bulge by analysing the detailed chemical composition of a large sample of red clump stars in Baade's window. These stars were selected to minimise the contamination by other Galactic components, so they are good tracers of the bulge metallicity distribution in Baade's window, at least for stars more metal-rich than ~-1.5. Methods: We used an automatic procedure to measure [Fe/H] differentially with respect to the metal-rich star μLeo in a sample of 219 bulge red clump stars from R = 20 000 resolution spectra obtained with FLAMES/GIRAFFE at the VLT. For a subsample of 162 stars, we also derived [Mg/H] from spectral synthesis around the Mg i triplet at λ 6319 Å. Results: The Fe and Mg metallicity distributions are both asymmetric with median values of +0.16 and +0.21, respectively. They show only a small proportion of stars at low metallicities, extending down to [Fe/H] = -1.1 or [Mg/H] = -0.7. The iron distribution is clearly bimodal, as revealed both by a deconvolution (from observational errors) and a Gaussian decomposition. The decomposition of the observed Fe and Mg metallicity distributions into Gaussian components yields two populations of equal sizes (50% each): a metal-poor component centred on [Fe/H] = -0.30 and [Mg/H] = -0.06 with a large dispersion and a narrow metal-rich component centred on [Fe/H] = +0.32 and [Mg/H] = +0.35. The metal-poor component shows high [Mg/Fe] ratios (around 0.3), while stars in the metal-rich component are found to have nearly solar ratios. Kinematical differences between the two components have also been found: the metal-poor component shows kinematics compatible with an old spheroid, while the metal-rich component is consistent with a population supporting a bar. In view of their chemical and kinematical properties, we suggest different formation scenarii for the two populations: a rapid formation time scale as an old spheroid for the metal-poor component (old bulge

  19. Distribution of metal and adsorbed guest species in zeolites

    Energy Technology Data Exchange (ETDEWEB)

    Chmelka, B.F.

    1989-12-01

    Because of their high internal surface areas and molecular-size cavity dimensions, zeolites are used widely as catalysts, shape- selective supports, or adsorbents in a variety of important chemical processes. For metal-catalyzed reactions, active metal species must be dispersed to sites within the zeolite pores that are accessible to diffusing reactant molecules. The distribution of the metal, together with transport and adsorption of reactant molecules in zeolite powders, are crucial to ultimate catalyst performance. The nature of the metal or adsorbed guest distribution is known, however, to be dramatically dependent upon preparatory conditions. Our objective is to understand, at the molecular level, how preparatory treatments influence the distribution of guest species in zeolites, in order that macroscopic adsorption and reaction properties of these materials may be better understood. The sensitivity of xenon to its adsorption environment makes {sup 129}Xe NMR spectroscopy an important diagnostic probe of metal clustering and adsorbate distribution processes in zeolites. The utility of {sup 129}Xe NMR depends on the mobility of the xenon atoms within the zeolite-guest system, together with the length scale of the sample heterogeneity being studied. In large pore zeolites containing dispersed guest species, such as Pt--NaY, {sup 129}Xe NMR is insensitive to fine structural details at room temperature.

  20. Distribution of metal and adsorbed guest species in zeolites

    International Nuclear Information System (INIS)

    Chmelka, B.F.

    1989-12-01

    Because of their high internal surface areas and molecular-size cavity dimensions, zeolites are used widely as catalysts, shape- selective supports, or adsorbents in a variety of important chemical processes. For metal-catalyzed reactions, active metal species must be dispersed to sites within the zeolite pores that are accessible to diffusing reactant molecules. The distribution of the metal, together with transport and adsorption of reactant molecules in zeolite powders, are crucial to ultimate catalyst performance. The nature of the metal or adsorbed guest distribution is known, however, to be dramatically dependent upon preparatory conditions. Our objective is to understand, at the molecular level, how preparatory treatments influence the distribution of guest species in zeolites, in order that macroscopic adsorption and reaction properties of these materials may be better understood. The sensitivity of xenon to its adsorption environment makes 129 Xe NMR spectroscopy an important diagnostic probe of metal clustering and adsorbate distribution processes in zeolites. The utility of 129 Xe NMR depends on the mobility of the xenon atoms within the zeolite-guest system, together with the length scale of the sample heterogeneity being studied. In large pore zeolites containing dispersed guest species, such as Pt--NaY, 129 Xe NMR is insensitive to fine structural details at room temperature

  1. Distribution of interatomic distances in large metallic clusters

    International Nuclear Information System (INIS)

    Glossman, M.D.; Iniguez, M.P.; Alonso, J.A.

    1992-01-01

    Spherically averaged pseudopotential (SAPS) calculations have been done for Mg n clusters, with n up to 250 within the framework of density functional theory. The electronic structure is computed resorting to the Thomas-Fermi-Dirac-Weizsaecker (TFDW) approximation for the kinetic energy. The equilibrium geometries have been obtained by minimizing the total cluster energy with respect to the atomic positions using the steepest-descent method. The ground state geometries obtained in this way are formed by spherical atomic shells, the number of them increasing with cluster size, up to a number of four for the biggest sizes considered here. An analysis of the distribution of the interatomic distances shows that the more internal is the shell, the more contracted are the interatomic distances. This effect diminishes progressively with increasing cluster size. For the purpose of comparison, similar calculations have been done with Cs n clusters in the same size range, allowing us to reproduce previous results obtained using a more elaborated density functional technique (Kohn-Sham method). The inhomogeneous contraction of interatomic distances then appears as a general fact for simple metallic clusters and not only for alkaline ones. (orig.)

  2. Comparative study of Heavy Metals Distribution in a Mechanic ...

    African Journals Online (AJOL)

    A comparative study of heavy metals; Lead, Chromium, Arsenic, Nickel, Cadmium and Mercury distribution was carried out in Oluku and Otofure both in Metropolitan Benin City, Edo State Nigeria with the view to determine the level of concentration and contribution of each site investigated. Thirty eight (38) soil samples were ...

  3. Density functional study of ferromagnetism in alkali metal thin films

    Indian Academy of Sciences (India)

    model (UJM), and it is argued that within LSDA or GGA, alkali metal thin films cannot be claimed to have an FM ground state. Relevance of these results to the experiments on transition metal-doped alkali metal thin films and bulk hosts are also discussed. Keywords. Alkali metal; thin films; magnetism; density functional ...

  4. Elucidating the Composition and Distribution of Trace Metals in Corals

    Science.gov (United States)

    Farfan, G.; Webb, S. M.; Apprill, A.; Hansel, C. M.

    2014-12-01

    Coral reefs host a plethora of marine life and thereby provide a wealth of aesthetic and economic benefits to coastal countries. Anthropogenic influences, including local coastal water contamination, however threaten the health of these delicate ecosystems. Metal incorporation into carbonate minerals, the backbone of coral reefs, is known to have a large yet variable impact on carbonate structure and solubility. Yet, trace metal influences on the structure, porosity, composition, and solubility of coral skeletons is largely unknown. Here, we coupled synchrotron-based micro-X-ray fluorescence (u-XRF) mapping and X-ray absorption near edge structure (XANES) spectroscopy with micro-X-ray diffraction (XRD) to explore the distribution and speciation of trace metals associated with corals and their impact on the carbonate structure of corals obtained from reefs varying in anthropogenic influence - Florida Keys, FL USA and the Federated States of Micronesia. Iron and copper were the most abundant metals in the biological tissue, while in some areas zinc was observed in the tissue, overlapping with the skeleton. Trace metals were not detectable in the aragonite skeletons; in fact, the distributions of Ca and Fe were anti-correlated. XANES spectra show that the iron is primarily Fe(III), likely as the poorly crystalline iron oxide ferrihydrite structure or trapped within ferretin proteins. The same trace metals were observed in corals of different species and from different environments. This in situ investigation corroborates previous studies that corals tend to incorporate iron into the biological components but not into the aragonite skeleton. Given the dominant partitioning of metals within the biological tissue rather than the coral skeleton, the specific carbon molecules responsible for metal attenuation and their fate under changing geochemical conditions and following coral death require exploration.

  5. Value-distribution of L-functions

    CERN Document Server

    Steuding, Jörn

    2007-01-01

    These notes present recent results in the value-distribution theory of L-functions with emphasis on the phenomenon of universality. In 1975, Voronin proved that any non-vanishing analytic function can be approximated uniformly by certain shifts of the Riemann zeta-function in the critical strip. This spectacular universality property has a strong impact on the zero-distribution: Riemann’s hypothesis is true if and only if the Riemann zeta-function can approximate itself uniformly (in the sense of Voronin). Meanwhile universality is proved for a large zoo of Dirichlet series, and it is conjectured that all reasonable L-functions are universal. In these notes we prove universality for polynomial Euler products. Our approach follows mainly Bagchi's probabilistic method. We further discuss related topics as, e.g., almost periodicity, density estimates, Nevanlinna theory, and functional independence.

  6. Heavy metal distribution and bioaccumulation in Chihuahuan Desert Rough Harvester ant (Pogonomyrmex rugosus) populations

    International Nuclear Information System (INIS)

    Del Toro, I.; Floyd, K.; Gardea-Torresdey, J.; Borrok, D.

    2010-01-01

    Heavy metal contamination can negatively impact arid ecosystems; however a thorough examination of bioaccumulation patterns has not been completed. We analyzed the distribution of As, Cd, Cu, Pb and Zn in soils, seeds and ant (Pogonomyrmex rugosus) populations of the Chihuahuan Desert near El Paso, TX, USA. Concentrations of As, Cd, Cu, and Pb in soils, seeds and ants declined as a function of distance from a now inactive Cu and Pb smelter and all five metals bioaccumulated in the granivorous ants. The average bioaccumulation factors for the metals from seeds to ants ranged from 1.04x (As) to 8.12x (Cd). The findings show bioaccumulation trends in linked trophic levels in an arid ecosystem and further investigation should focus on the impacts of heavy metal contamination at the community level. - Heavy metals bioaccumulate in desert ants.

  7. Work function of elemental metals and its face dependence ...

    African Journals Online (AJOL)

    The calculated work functions for the flat surface of the metals were in perfect agreement with experimental values for metals in the low-density limit and the agreement with experimental values decreased towards the high-density limit. The calculated work functions for the body centred cubic metals were in good agreement ...

  8. Nuclear microprobe measurement of the spatial distribution on non-metals in metals

    International Nuclear Information System (INIS)

    McMillan, J.W.

    1981-01-01

    The spatial distributions of many non-metallic light elements and isotopes have been measured in metals by nuclear microprobe analysis, particularly through using nuclear reactions. In this paper, typical equipment and analysis techniques are briefly described. Applications are outlined, as is the range of elements that have been determined. Also, the advantages of nuclear microprobe methods are indicated, such as, their ability to discriminate against surface contamination, and their ability to measure isotopes. (orig./RB) [de

  9. Origin and spatial distribution of metals in agricultural soils

    International Nuclear Information System (INIS)

    Mohammadpour, Gh.A.; Karbassi, A.R.; Baghvand, A.

    2016-01-01

    Presence of toxic metals in agricultural soils can impose adverse health impact on consumers. The main purpose of this study was to determine spatial distribution of elements Fe, Sb, Mn in agriculture soils and crops of Hamedan Province in Iran. Soil samples (0-20 cm depth) were collected from an area of 2831 km 2 . Iron, Antimony and Manganese in samples of soil and agricultural crops were extracted and their amount was determined using atomic absorption spectrometer. The spatial distribution map of the studied elements was developed using Kriging method. The main concentration of Fe, Sb and Mn in the soil of the study area is about 3.8%, 2.5 and 403 mg/kg, respectively. According to chemical partitioning studies, the anthropogenic share of Fe, Sb and Mn is about 28.51%, 34.83% and 30.35%, respectively. Results of comparison of heavy metals pollution intensity in the agricultural soil with geoaccumulation index and also pollution index, illustrated that iron and manganese are classified in the Non-polluted class and antimony is in the moderately polluted class. Analysis of zoning map of pollution index showed that Fe, Sb and Mn are of geological sources. In fact, these metals are naturally found in soil. However, anthropogenic activities have led to more accumulation of these metals in the soil. The obtained health risk for metals in agricultural crops is indicative of safe value for consumers.

  10. The GIRAFFE Inner Bulge Survey (GIBS). III. Metallicity distributions and kinematics of 26 Galactic bulge fields

    Science.gov (United States)

    Zoccali, M.; Vasquez, S.; Gonzalez, O. A.; Valenti, E.; Rojas-Arriagada, A.; Minniti, J.; Rejkuba, M.; Minniti, D.; McWilliam, A.; Babusiaux, C.; Hill, V.; Renzini, A.

    2017-03-01

    Context. Several recent studies have demonstrated that the Galactic bulge hosts two components with different mean metallicities, and possibly different spatial distribution and kinematics. As a consequence, both the metallicity distribution and the radial velocity of bulge stars vary across different lines of sight. Aims: We present here the metallicity distribution function of red clump stars in 26 fields spread across a wide area of the bulge, with special emphasis on fields close to Galactic plane, at latitudes b = -2° and b = -1°, that have not been explored before. Methods: This paper includes new metallicities from a sample of approximately 5000 K giant stars, observed at spectral resolution R 6500, in the Calcium II Triplet region. These represent the main dataset from the GIRAFFE Inner Bulge Survey. As part of the same survey we have previously published results for a sample of approximately 600 K giant stars, at latitude b -4°, derived from higher resolution spectra (R = 22 500). Results: The combined sample allows us to trace and characterize the metal poor and metal rich bulge populations down to the inner bulge. We present a density map for each of the two components. Contrary to expectations from previous works, we found the metal poor population to be more centrally concentrated than the metal rich one, and with a more axisymmetric spatial distribution. The metal rich population, on the other hand, is arranged in a boxy distribution, consistent with an edge-on bar. By coupling metallicities and radial velocities we show that the metal poor population has a velocity dispersion that varies rather mildly with latitude. On the contrary, the metal rich population has a low velocity dispersion far from the plane (b = -8.5°), yet has a steeper gradient with latitude, becoming higher than the metal poor one in the innermost field (b = -1°). Conclusions: This work provides new observational constraints on the actual chemodynamical properties of the

  11. Distribution function of faint galaxy numbers

    International Nuclear Information System (INIS)

    Fesenko, L.M.

    1981-01-01

    The Lick observatory counts of galaxies are considered. The distribution of number of galaxies in elementary regions (ER) of 1 degx1 deg is investigated. Each field of 6 degx6 deg was treated separately At b>40 deg the probab+lity to observe of n galaxies in ER is an exponential decreasing function of n, if unequality n> were fulfilled. The mean apparent multiplicity of a galaxy (2.8+-0.9) was derived. The galaxy number distribution was simple model for the number of various systems of galaxies. The supperclustering of galaxies was not introduced. Based on that model the approximate expression for galaxy number distribution was considered and was compared with observed distributions. The agreement between these distributions become better with reducing of the interstellar absorption of light

  12. Distribution of heavy metals from flue gas in algal bioreactor

    Science.gov (United States)

    Napan, Katerine

    Flue gas from coal-fired power plants is a major source of CO2 to the atmosphere. Microalgae can use this enriched form of CO2 as carbon source and in turn the biomass can be used to produce food, feed, fertilizer and biofuels. However, along with CO2, coal-based flue gas will inevitably introduce heavy metals, which have a high affinity to bind algal cells, could be toxic to the organisms and if transferred to the products could limit their uses. This study seeks to address the distribution and impact of heavy metals present in flue gas on microalgae production systems. To comprehend its effects, algae Scenedesmus obliquus was grown in batch reactors in a multimetal system. Ten heavy metals (Cu, Co, Zn, Pb, As, Se, Cr, Hg, Ni and Cd) were selected and were evaluated at four concentrations (1X, 2X, 5X and 10X). Results show that most heavy metals accumulated mainly in biomass and were found in very low concentrations in media. Hg was shown to be lost from the culture, with low amounts present in the biomass. An upper limit for As uptake was observed, suggesting its likelihood to build-up in the system during medium recycle. The As limited bioaccumulation was overcome by addition of sulfur to the algal medium. Heavy metal at 2X, 5X and 10X inhibited both growth and lipid production, while at the reference concentration both biomass and lipids yields were increased. Heavy metal concentrations in the medium and biomass were time dependent, and at the end of the cultivation most heavy metals in the supernatant solution complied with the recommendations for irrigation water, while biomass was below limits for cattle and poultry feed, fertilizer, plastic and paper. This research shows that bioremediation of CO2 and heavy metals in combination with energy production can be integrated, which is an environmentally friendly form of biotechnology.

  13. Electron energy-distribution functions in gases

    International Nuclear Information System (INIS)

    Pitchford, L.C.

    1981-01-01

    Numerical calculation of the electron energy distribution functions in the regime of drift tube experiments is discussed. The discussion is limited to constant applied fields and values of E/N (ratio of electric field strength to neutral density) low enough that electron growth due to ionization can be neglected

  14. Bi-log-concave Distribution Functions

    DEFF Research Database (Denmark)

    Dümbgen, Lutz; Kolesnyk, Petro; Wilke, Ralf

    2017-01-01

    Nonparametric statistics for distribution functions F or densities f=F′ under qualitative shape constraints constitutes an interesting alternative to classical parametric or entirely nonparametric approaches. We contribute to this area by considering a new shape constraint: F is said to be bi-log...

  15. Systems and methods for producing metal clusters; functionalized surfaces; and droplets including solvated metal ions

    Science.gov (United States)

    Cooks, Robert Graham; Li, Anyin; Luo, Qingjie

    2017-08-01

    The invention generally relates to systems and methods for producing metal clusters; functionalized surfaces; and droplets including solvated metal ions. In certain aspects, the invention provides methods that involve providing a metal and a solvent. The methods additionally involve applying voltage to the solvated metal to thereby produce solvent droplets including ions of the metal containing compound, and directing the solvent droplets including the metal ions to a target. In certain embodiments, once at the target, the metal ions can react directly or catalyze reactions.

  16. Heavy metal distribution in sediment profiles of Tuul River, Mongolia

    Science.gov (United States)

    Soyol-Erdene, T. O.; Lin, S.; Tuuguu, E.; Daichaa, D.; Ulziibat, B.; Enkh-Amgalan, T.; Hsieh, I. C.

    2016-12-01

    The distribution, enrichment, and accumulation of heavy metals in the sediments of Tuul River, Mongolia were investigated. Sediment core samples with depths of 4.0-49 cm from thirteen locations along the Tuul River were collected in the period from Sept. 2013 to Aug. 2014 and characterized for metal contents (e.g., Al, Fe, Cu, Zn, Pb, Ni, Cd, Hg and Cr), water content, and grain size. Results showed that metal average concentrations in the sample cores varied from 0.02 mg kg-1 for Hg (0.01 - 0.03 mg kg-1) to 481 mg kg-1 for Mn (277 - 623 mg kg-1). Metal concentrations at the downstream of the capital city were higher than those at other locations. All heavy metals studied, had average enrichment factors less than 3.0, but some sites had relatively higher values of enrichment factors up to 18 for Cu, 4.1 for Hg, 5.9 for Zn, and 25 for Cr, especially at middle depth ( 8-12 cm) of the cores. Importantly, severe pollution of mercury (Hg) was found at the downstream of the capital city which requires immediate remediation before this metal propagates into the food chain. Metal concentrations correlated to the physical-chemical properties of the sediments, which suggested the influence of industrial and municipal wastewaters discharged from the nearby cities. Results of this work would help to develop strategy to remediate of Tuul river sediment and to reduce the exposure of inhabitants to toxic substances.

  17. Metal distribution characteristic of MSWI bottom ash in view of metal recovery.

    Science.gov (United States)

    Xia, Yi; He, Pinjing; Shao, Liming; Zhang, Hua

    2017-02-01

    Bottom ash is the major by-product of municipal solid waste incineration (MSWI), and is often reused as an engineering material, such as road-base aggregate. However, some metals (especially aluminum) in bottom ash can react with water and generate gas that could cause expansion and failure of products containing the ash; these metals must be removed before the ash is utilized. The size distribution and the chemical speciation of metals in the bottom ash from two Chinese MSWI plants were examined in this study, and the recovery potential of metals from the ash was evaluated. The metal concentrations in these bottom ashes were lower than that generated in other developed countries. Specifically, the contents of Al, Fe, Cu and Zn were 18.9-29.2, 25.5-32.3, 0.7-1.0 and 1.6-2.5g/kg, respectively. Moreover, 44.9-57.0wt.% of Al and 55.6-75.4wt.% of Fe were distributed in bottom ash particles smaller than 5mm. Similarly, 46.6-79.7wt.% of Cu and 42.9-74.2wt.% of Zn were concentrated in particles smaller than 3mm. The Fe in the bottom ash mainly existed as hematite, and its chemical speciation was considered to limit the recovery efficiency of magnetic separation. Copyright © 2016. Published by Elsevier B.V.

  18. Distribution functions and thermodynamic functions of many particle systems

    International Nuclear Information System (INIS)

    Isihara, A.; Rosa Junior, S.G.

    1976-01-01

    A method is given of determining and upper bound of the entropy of a classical interacting system. A family of gaussian trial distribution functions is introduced for an electron gas. It was found that the ring diagram energy corresponds to the minimum free energy which the family produces. In contrast to the ring diagram method, the new approach is extremely simple and general [pt

  19. Distributed Function Calculation over Noisy Networks

    Directory of Open Access Journals (Sweden)

    Zhidun Zeng

    2016-01-01

    Full Text Available Considering any connected network with unknown initial states for all nodes, the nearest-neighbor rule is utilized for each node to update its own state at every discrete-time step. Distributed function calculation problem is defined for one node to compute some function of the initial values of all the nodes based on its own observations. In this paper, taking into account uncertainties in the network and observations, an algorithm is proposed to compute and explicitly characterize the value of the function in question when the number of successive observations is large enough. While the number of successive observations is not large enough, we provide an approach to obtain the tightest possible bounds on such function by using linear programing optimization techniques. Simulations are provided to demonstrate the theoretical results.

  20. Lateral Distribution Functions of Extensive Air Showers

    Science.gov (United States)

    Geranios, A.; Fokitis, E.; Maltezos, S.; Koutsokosta, D.; Antoniadou, I.; Malandraki, O.; Mastichiadis, A.; Antonopoulou, E.; Gika, V.; Dimitrakoudis, S.

    The energy is among the characteristics of Ultra High Energy Cosmic Rays (E>5 x 1019 eV) which could be estimated experimentally. The following paper attempts to estimate the energy of an UHECR proton by applying a Monte Carlo simulation code. A number of extensive air showers, vertical and inclined, is simulated to derive the Lateral Distribution Functions of the shower muons. The scenario of simulations is adopted to the Cerenkov surface detector of the P. AUGER Observatory. Due to the fact that the Lateral Distribution Functions show minimal fluctuations of the muon density at a distance larger than 800 m from the core of the showers, and due to the fact that at a distance of 900 m the distribution functions for inclined showers coincide (which means that it does not change with the zenith angle of the showers), we select the muon density at 900 m to derive the energy of the primary protons. (The project is co-funded by the European Social Fund and National Resources (EPEAEK II) PYTHAGORAS II.)

  1. Distribution of heavy metals in sediments of ligurian coastal areas

    Energy Technology Data Exchange (ETDEWEB)

    Picollo, A.; Frache, R.; Magi, E.; Ianni, C. [Genua Univ., Genua (Italy). Dept. of Chemistry and Industrial Chemistry

    2000-08-01

    A study on the concentration and distribution of heavy metals (Zn, Pb, Fe, Cr, V, Mn, Cu) in the sediments of the Ligurian coast was carried out. The data are interpreted by the Principal Component Analysis and related, for Cr and Fe, to the fluvial sediments. The comparison between the data obtained from the present study and similar matrices of Mediterranean coastal environment has allowed the determination of values due chiefly to natural input. [Italian] Il lavoro riguarda la distribuzione e la concentrazione di alcuni metalli pesanti (Zn, Pb, Fe, Cr, V, Mn, Cu) nei sedimenti costieri della Liguria. I dati ottenuti sono stati interpretati con l'ausilio dell'analisi delle componenti principali (PCA) e i valori di concentrazione del Cr e del Fe sono risultati correlati agli apporti fluviali. Il confronto tra i dati ottenuti con matrici similari di ambienti costieri del Mediterraneo ha permesso di riscontrare valori dovuti principalmente ad apporti naturali.

  2. Wireless distributed functional electrical stimulation system.

    Science.gov (United States)

    Jovičić, Nenad S; Saranovac, Lazar V; Popović, Dejan B

    2012-08-09

    The control of movement in humans is hierarchical and distributed and uses feedback. An assistive system could be best integrated into the therapy of a human with a central nervous system lesion if the system is controlled in a similar manner. Here, we present a novel wireless architecture and routing protocol for a distributed functional electrical stimulation system that enables control of movement. The new system comprises a set of miniature battery-powered devices with stimulating and sensing functionality mounted on the body of the subject. The devices communicate wirelessly with one coordinator device, which is connected to a host computer. The control algorithm runs on the computer in open- or closed-loop form. A prototype of the system was designed using commercial, off-the-shelf components. The propagation characteristics of electromagnetic waves and the distributed nature of the system were considered during the development of a two-hop routing protocol, which was implemented in the prototype's software. The outcomes of this research include a novel system architecture and routing protocol and a functional prototype based on commercial, off-the-shelf components. A proof-of-concept study was performed on a hemiplegic subject with paresis of the right arm. The subject was tasked with generating a fully functional palmar grasp (closing of the fingers). One node was used to provide this movement, while a second node controlled the activation of extensor muscles to eliminate undesired wrist flexion. The system was tested with the open- and closed-loop control algorithms. The system fulfilled technical and application requirements. The novel communication protocol enabled reliable real-time use of the system in both closed- and open-loop forms. The testing on a patient showed that the multi-node system could operate effectively to generate functional movement.

  3. Wireless distributed functional electrical stimulation system

    Directory of Open Access Journals (Sweden)

    Jovičić Nenad S

    2012-08-01

    Full Text Available Abstract Background The control of movement in humans is hierarchical and distributed and uses feedback. An assistive system could be best integrated into the therapy of a human with a central nervous system lesion if the system is controlled in a similar manner. Here, we present a novel wireless architecture and routing protocol for a distributed functional electrical stimulation system that enables control of movement. Methods The new system comprises a set of miniature battery-powered devices with stimulating and sensing functionality mounted on the body of the subject. The devices communicate wirelessly with one coordinator device, which is connected to a host computer. The control algorithm runs on the computer in open- or closed-loop form. A prototype of the system was designed using commercial, off-the-shelf components. The propagation characteristics of electromagnetic waves and the distributed nature of the system were considered during the development of a two-hop routing protocol, which was implemented in the prototype’s software. Results The outcomes of this research include a novel system architecture and routing protocol and a functional prototype based on commercial, off-the-shelf components. A proof-of-concept study was performed on a hemiplegic subject with paresis of the right arm. The subject was tasked with generating a fully functional palmar grasp (closing of the fingers. One node was used to provide this movement, while a second node controlled the activation of extensor muscles to eliminate undesired wrist flexion. The system was tested with the open- and closed-loop control algorithms. Conclusions The system fulfilled technical and application requirements. The novel communication protocol enabled reliable real-time use of the system in both closed- and open-loop forms. The testing on a patient showed that the multi-node system could operate effectively to generate functional movement.

  4. Bulk-plasmon contribution to the work function of metals

    International Nuclear Information System (INIS)

    Gutierrez, F A; DIaz-Valdes, J; Jouin, H

    2007-01-01

    By consideration of the Koopmans theorem expression for the work function of a metal, we find that the total height of the surface barrier potential equals the value of the bulk-plasmon energy of pure metals. As a consequence a simple formula for the work function is obtained which shows better agreement with the experimental data than the most complete existent theories

  5. Analytic functions for calculating binary alloys of FCC metals ...

    African Journals Online (AJOL)

    The problem studied in this paper is that of obtaining appropriate electron density function and a pair potential function for an FCC metal within the EAM format. The approach adopted is to use the experimental dilute limit heats of solution of the binary alloys of FCC metals as input parameters into Johnson analytical model, ...

  6. The ion-electron correlation function in liquid metals

    International Nuclear Information System (INIS)

    Takeda, S.; Tamaki, S.; Waseda, Y.

    1985-01-01

    The structure factors of liquid Zn at 723 K, Sn at 523 K and Bi at 573 K have been determined by neutron diffraction with sufficient accuracy and compared with those of X-ray diffraction. A remarkable difference in the structural information between the two methods is clearly found around the first peak region as well as in the slightly varied peak positions, and it is apparently larger than the experimental errors. With these facts in mind, a new method evaluating the ion-electron correlation function in liquid metals has been proposed by using the measured structural data of X-rays and neutrons, with the help of theoretical values of the electron-electron correlation function by he Utsumi-Ichimaru scheme. This method has been applied to liquid Zn, Sn and Bi, and the radial distribution function of valence electrons around an ion has been estimated, from which the ionic radius and the schematic diagram of the electron distribution map are obtained. The ionic radii evaluated in this work have been found to agree well with those proposed by Pauling. (author)

  7. Functionalization of protein crystals with metal ions, complexes and nanoparticles.

    Science.gov (United States)

    Abe, Satoshi; Maity, Basudev; Ueno, Takafumi

    2018-04-01

    Self-assembled proteins have specific functions in biology. With inspiration provided by natural protein systems, several artificial protein assemblies have been constructed via site-specific mutations or metal coordination, which have important applications in catalysis, material and bio-supramolecular chemistry. Similar to natural protein assemblies, protein crystals have been recognized as protein assemblies formed of densely-packed monomeric proteins. Protein crystals can be functionalized with metal ions, metal complexes or nanoparticles via soaking, co-crystallization, creating new metal binding sites by site-specific mutations. The field of protein crystal engineering with metal coordination is relatively new and has gained considerable attention for developing solid biomaterials as well as structural investigations of enzymatic reactions, growth of nanoparticles and catalysis. This review highlights recent and significant research on functionalization of protein crystals with metal coordination and future prospects. Copyright © 2017 Elsevier Ltd. All rights reserved.

  8. Tight Bounds for Distributed Functional Monitoring

    DEFF Research Database (Denmark)

    Woodruff, David P.; Zhang, Qin

    2011-01-01

    $, our bound resolves their main open question. Our lower bounds are based on new direct sum theorems for approximate majority, and yield significant improvements to problems in the data stream model, improving the bound for estimating $F_p, p > 2,$ in $t$ passes from $\\tilde{\\Omega}(n^{1-2/p}/(\\eps^{2/p......} t))$ to $\\tilde{\\Omega}(n^{1-2/p}/(\\eps^{4/p} t))$, giving the first bound for estimating $F_0$ in $t$ passes of $\\Omega(1/(\\eps^2 t))$ bits of space that does not use the gap-hamming problem, and showing a distribution for the gap-hamming problem with high external information cost or super-polynomial......We resolve several fundamental questions in the area of distributed functional monitoring, initiated by Cormode, Muthukrishnan, and Yi (SODA, 2008). In this model there are $k$ sites each tracking their input and communicating with a central coordinator that continuously maintain an approximate...

  9. Orientation dependence of the work function for metal nanocrystals

    Science.gov (United States)

    Gao, Lingyuan; Souto-Casares, Jaime; Chelikowsky, James R.; Demkov, Alexander A.

    2017-12-01

    Work function values measured at different surfaces of a metal are usually different. This raises an interesting question: What is the work function of a nano-size crystal, where differently oriented facets can be adjacent? Work functions of metallic nanocrystals are also of significant practical interest, especially in catalytic applications. Using real space pseudopotentials constructed within density functional theory, we compute the local work function of large aluminum and gold nanocrystals. We investigate how the local work function follows the change of the surface plane orientation around multifaceted nanocrystals, and we establish the importance of the orbital character near the Fermi level in determining work function differences between facets.

  10. Treatment of metal-contaminated water and vertical distribution of metal precipitates in an upflow anaerobic bioreactor.

    Science.gov (United States)

    Quan, Z X; La, H J; Cho, Y G; Hwang, M H; Kim, L S; Lee, S T

    2003-03-01

    A lab-scale upflow anaerobic bioreactor filled with granular sludge and cow manure was operated for 140 days to determine the mechanism of metal removal and the vertical distribution of metal precipitates. Heavy metal ions were removed in the order of Cu2+, Cd2+, Zn2+, Fe2+ and Mn2+ with respect to the height in the reactor. The solid phase analysis showed that the heavy metals were mostly precipitated in the form of metal sulfides by sulfate reduction The contents of metal precipitates in the reactor were as follows: (i) Cd and Zn were highest in the bottom, (ii) Fe was highest at the low-middle layer, and (iii) Mn was increased with the height in the reactor. The vertical distribution of metal sulfides in the reactor was directly related to the solubility product (Ksp). Results obtained in this study suggest a feasibility of the application to separate precipitation metal-containing wastewater.

  11. H II REGION METALLICITY DISTRIBUTION IN THE MILKY WAY DISK

    International Nuclear Information System (INIS)

    Balser, Dana S.; Rood, Robert T.; Bania, T. M.; Anderson, L. D.

    2011-01-01

    The distribution of metals in the Galaxy provides important information about galaxy formation and evolution. H II regions are the most luminous objects in the Milky Way at mid-infrared to radio wavelengths and can be seen across the entire Galactic disk. We used the National Radio Astronomy Observatory (NRAO) Green Bank Telescope to measure radio recombination line and continuum emission in 81 Galactic H II regions. We calculated LTE electron temperatures using these data. In thermal equilibrium metal abundances are expected to set the nebular electron temperature with high abundances producing low temperatures. Our H II region distribution covers a large range of Galactocentric radius (5-22 kpc) and samples the Galactic azimuth range 330 0 -60 0 . Using our highest quality data (72 objects) we derived an O/H Galactocentric radial gradient of -0.0383 ± 0.0074 dex kpc -1 . Combining these data with a similar survey made with the NRAO 140 Foot telescope we get a radial gradient of -0.0446 ± 0.0049 dex kpc -1 for this larger sample of 133 nebulae. The data are well fit by a linear model and no discontinuities are detected. Dividing our sample into three Galactic azimuth regions produced significantly different radial gradients that range from -0.03 to -0.07 dex kpc -1 . These inhomogeneities suggest that metals are not well mixed at a given radius. We stress the importance of homogeneous samples to reduce the confusion of comparing data sets with different systematics. Galactic chemical evolution models typically derive chemical evolution along only the radial dimension with time. Future models should consider azimuthal evolution as well.

  12. ANIONS FUNCTIONS IN TRANSITION METALS COORDINATION COMPOUNDS

    Directory of Open Access Journals (Sweden)

    T. V. Koksharova

    2016-04-01

    Full Text Available The effect of anions on the structure and properties of coordination compounds of transition metals has been discussed. The examples of changes in the composition of the formed complexes by replacement of the anion are given: metal ratio to a neutral ligand, the composition of the inner sphere, the direction of template synthesis. Anions can determine the presence of isomers in complexes with different ligands. Examples of conformational, ionization isomerism, inner sphere bond isomerization are given. The nature of the coordination polyhedron is highly sensitive to the replacement of the anion too. Examples of coordination compounds where the anion change causes a change in coordination capacity of neutral ligands and the strength of their bonds with the metal, coordination number and geometry of the inner sphere, the organization of molecular structures (the structure of the hydrogen bond networks and the degree of polymerization, crystal packing. The anions significantly affect the binding of the solvent molecules, complexes magnetic and luminescent properties, they can change the compound color, the mechanisms of thermolysis. Anions make a very noticeable influence on possible redox processes following the complexation in some cases. Anions in the coordination sphere can change catalytic and biochemical processes as well as the ways of interaction of metal ions with drugs.

  13. MBOK: ITS DISTRIBUTION, MEANING, AND FUNCTION

    Directory of Open Access Journals (Sweden)

    Ajar Pradika A. Tur

    2015-12-01

    Full Text Available Mbok, in Javanese language, has not only a ’mother’ in meaning. As a lexicon in the language, mbok in one side truly means a ‘mother’ and still has the same meaning although it experiences the morphological process to be, at least, embok, simbok, or mboke. The variations exist and are spoken by Javanese native speakers throughout the Javanese dialects such as Suroboyoan, Solo, Yogyakarta, Bagelen, and Banyumasan dialects spread from the East Java, Yogyakarta, and Central Java. However, mbok, as a particle has different meaning, even different various meanings relying on its distribution in a sentence. Then the meanings bear its different various functions as well in the sentence based on the context of the sentence (grammatical-semantics meaning. Through Teknik Balik (Converse Technique the data gained was analyzed to distinguish the position of the particle in the sentence in order to reach its significant different meanings and functions. At least, from the analysis, we have three positions of mbok in the sentences, that are in the initial, middle, and the end of the sentences. These positions affect the meanings and functions that can be seen as follows; ‘, is not it?’ (Tag Question and ‘is/are” (Verbal Question for emphasizing, ‘please’ for requesting a help, ‘may be’ and ‘in case’ for expressing possibility, and ‘causing’ for expressing cause-effect. Keywords: mbok, semantics, Banyumasan dialect

  14. Distribution of heavy metals in cocoa farm soils in the Western Region of Ghana

    International Nuclear Information System (INIS)

    Ackah, Justice Edusei

    2012-10-01

    concentration for non-polluted soils and for European norms. However, total concentrations of Cd, Cu, Cr and Pb in the surface soils (0 – 10 cm) exceeded the thresholds for atmospheric fallout concentrations in top soil to 20 cm depth indicative of anthropogenic contamination. The lowest heavy metal contents were observed in the Haplic Luvisols while the highest metal loadings were in the Haplic Ferrasols and the Dystric Fluvisols. Depth function plots, ANOVA and correlation analyses indicated that clay influenced the distribution of Cr, Cu, Fe, Ni and Zn in the soils. Clay and total organic carbon controlled Cd distribution while pH and clay were associated with the distribution of Mn. Thus, clay had the most pronounce effect on the distribution of the metals in the soils. Accumulation-depletion ratios, enrichment factors and principal component analysis indicated that the distribution of Cd, Cu, Mn and Pb in the soils highlighted an anthropogenic pollution, most probably, from agrochemical inputs and/or from atmospheric deposition. Iron and Ni distributions were associated with lithogenic origin whereas Zn and Cr distribution were related to both anthropogenic and lithogenic contributions. (au)

  15. Metals affect soil bacterial and fungal functional diversity differently.

    Science.gov (United States)

    Stefanowicz, Anna M; Niklińska, Maria; Laskowski, Ryszard

    2008-03-01

    Heavy metals can cause a decrease in the taxonomic diversity of soil communities. Because of functional redundancy, it remains unclear to what extent different functions performed by the soil microbial communities may be affected by pollution. We studied the impact of metal contamination on soil bacterial and fungal functional diversity, active microbial biomass, and soil respiration rate. Soil samples were collected from 39 sites along three forest and five meadow pollution transects near an abandoned Pb/Zn smelter in Avonmouth (UK) and Ni smelter in Clydach (UK), in a Cu mining and smelting region near Glogów (Poland), and in a Zn/Pb mining and smelting region near Olkusz (Poland). Biolog GN2 and SFN2 plates were used to study the bacterial and fungal functional diversity, which subsequently was expressed as Shannon's diversity index (H'). The active microbial biomass was measured as substrate-induced respiration. We found that the bacterial functional diversity significantly decreased, whereas the fungal functional diversity slightly increased, with increasing metal concentration. We also observed a slight negative effect of metal pollution on the active microbial biomass. No relationship was found between metal contamination and total soil respiration rate. This suggests a higher sensitivity of bacterial functional diversity as an indicator for the effects of metal pollution compared with overall soil respiration. All microbial parameters were affected by nutrient concentrations and/or soil pH.

  16. Metal free synthesis of functionalized 1-aryl isoquinolines via iodine ...

    Indian Academy of Sciences (India)

    KAMSALI MURALI MOHAN ACHARI

    Metal free synthesis of functionalized 1-aryl isoquinolines via iodine mediated oxidative dehydrogenation and ring opening of lactam in isoindoloisoquinolinones. KAMSALI MURALI MOHAN ACHARI, MUTHUPANDI KARTHICK and CHINNASAMY RAMARAJ RAMANATHAN. ∗. Department of Chemistry, Pondicherry ...

  17. Metal free synthesis of functionalized 1-aryl isoquinolines via iodine ...

    Indian Academy of Sciences (India)

    Metal free synthesis of functionalized 1-aryl isoquinolines via iodine mediated oxidative dehydrogenation and ring opening of lactam in isoindoloisoquinolinones. KAMSALI MURALI MOHAN ACHARI MUTHUPANDI KARTHICK CHINNASAMY RAMARAJ RAMANATHAN. Regular Aricle Volume 129 Issue 6 June 2017 pp ...

  18. Bio-Functional Design, Application and Trends in Metallic Biomaterials

    Science.gov (United States)

    Yang, Ke; Zhou, Changchun; Fan, Hongsong; Fan, Yujiang; Jiang, Qing; Song, Ping; Fan, Hongyuan; Chen, Yu; Zhang, Xingdong

    2017-01-01

    Introduction of metals as biomaterials has been known for a long time. In the early development, sufficient strength and suitable mechanical properties were the main considerations for metal implants. With the development of new generations of biomaterials, the concepts of bioactive and biodegradable materials were proposed. Biological function design is very import for metal implants in biomedical applications. Three crucial design criteria are summarized for developing metal implants: (1) mechanical properties that mimic the host tissues; (2) sufficient bioactivities to form bio-bonding between implants and surrounding tissues; and (3) a degradation rate that matches tissue regeneration and biodegradability. This article reviews the development of metal implants and their applications in biomedical engineering. Development trends and future perspectives of metallic biomaterials are also discussed. PMID:29271916

  19. Reduced work function of graphene by metal adatoms

    Energy Technology Data Exchange (ETDEWEB)

    Legesse, Merid; Mellouhi, Fedwa El; Bentria, El Tayeb; Madjet, Mohamed E. [Qatar Environment and Energy Research Institute, Hamad Bin Khalifa University, Doha (Qatar); Fisher, Timothy S. [School of Mechanical Engineering and Birck Nanotechnology Center, Purdue University, West Lafayette, IN 47907 (United States); Kais, Sabre [Qatar Environment and Energy Research Institute, Hamad Bin Khalifa University, Doha (Qatar); Department of Chemistry and Physics, Purdue University, West Lafayette, IN 46323 (United States); College of Science and Engineering, Hamad Bin Khalifa University, Doha (Qatar); Alharbi, Fahhad H., E-mail: falharbi@qf.org.qa [Qatar Environment and Energy Research Institute, Hamad Bin Khalifa University, Doha (Qatar); College of Science and Engineering, Hamad Bin Khalifa University, Doha (Qatar)

    2017-02-01

    Highlights: • Using DFT, the maximum reduction of graphene workfunction is investigated. This is important for many applications. • The calculations show that the adatoms prefer to relax at hollow sites. • The transfer of electrons from the adatoms to graphene shifts up the Fermi level. So, graphene becomes metallic. • For those dopants that have been used experimentally, the calculations agree with the experimental data. • We found that 8% doping by Cs reduces the work function to 2.05 eV. - Abstract: In this paper, the work function of graphene doped by different metal adatoms and at different concentrations is investigated. Density functional theory is used to maximize the reduction of the work function. In general, the work function drops significantly before reaching saturation. For example in the case of Cs doping, the work function saturates at 2.05 eV with a modest 8% doping. The adsorption of different concentrations on metal adatoms on graphene is also studied. Our calculations show that the adatoms prefer to relax at hollow sites. The transfer of electron from metallic dopants to the graphene for all the studied systems shifts the Fermi energy levels above the Dirac-point and the doped graphenes become metallic. The value of Fermi energy shifts depends on the type of metallic dopants and its concentrations. A detail analysis of the electronic structure in terms of band structure and density of states, absorption energy, and charge transfer for each adatom-graphene system is presented.

  20. Recent Advances as Materials of Functional Metal-Organic Frameworks

    Directory of Open Access Journals (Sweden)

    Xiao-Lan Tong

    2013-01-01

    Full Text Available Metal-organic frameworks (MOFs, also known as hybrid inorganic-organic materials, represent an emerging class of materials that have attracted the imagination of solid-state chemists because MOFs combine unprecedented levels of porosity with a range of other functional properties that occur through the metal moiety and/or the organic ligand. The purpose of this critical review is to give a representative and comprehensive overview of the arising developments in the field of functional metal-organic frameworks, including luminescence, magnetism, and porosity through presenting examples. This review will be of interest to researchers and synthetic chemists attempting to design multifunctional MOFs.

  1. Concentrations and distributions of metals associated with dissolved organic matter from the Suwannee River (GA, USA)

    Science.gov (United States)

    Kuhn, M. Keshia; Neubauer, Elisabeth; Hofmann, Thilo; von der Kammer, Frank; Aiken, George R.; Maurice, Patricia A.

    2015-01-01

    Concentrations and distributions of metals in Suwannee River (SR) raw filtered surface water (RFSW) and dissolved organic matter (DOM) processed by reverse osmosis (RO), XAD-8 resin (for humic and fulvic acids [FA]), and XAD-4 resin (for “transphilic” acids) were analyzed by asymmetrical flow field-flow fractionation (AsFlFFF). SR samples were compared with DOM samples from Nelson's Creek (NLC), a wetland-draining stream in northern Michigan; previous International Humic Substances Society (IHSS) FA and RO samples from the SR; and an XAD-8 sample from Lake Fryxell (LF), Antarctica. Despite application of cation exchange during sample processing, all XAD and RO samples contained substantial metal concentrations. AsFlFFF fractograms allowed metal distributions to be characterized as a function of DOM component molecular weight (MW). In SR RFSW, Fe, Al, and Cu were primarily associated with intermediate to higher than average MW DOM components. SR RO, XAD-8, and XAD-4 samples from May 2012 showed similar MW trends for Fe and Al but Cu tended to associate more with lower MW DOM. LF DOM had abundant Cu and Zn, perhaps due to amine groups that should be present due to its primarily algal origins. None of the fractograms showed obvious evidence for mineral nanoparticles, although some very small mineral nanoparticles might have been present at trace concentrations. This research suggests that AsFlFFF is important for understanding how metals are distributed in different DOM samples (including IHSS samples), which may be key to metal reactivity and bioavailability.

  2. Theoretical method for determining particle distribution functions of classical systems

    International Nuclear Information System (INIS)

    Johnson, E.

    1980-01-01

    An equation which involves the triplet distribution function and the three-particle direct correlation function is obtained. This equation was derived using an analogue of the Ornstein--Zernike equation. The new equation is used to develop a variational method for obtaining the triplet distribution function of uniform one-component atomic fluids from the pair distribution function. The variational method may be used with the first and second equations in the YBG hierarchy to obtain pair and triplet distribution functions. It should be easy to generalize the results to the n-particle distribution function

  3. Nucleic acid-functionalized transition metal nanosheets for biosensing applications.

    Science.gov (United States)

    Mo, Liuting; Li, Juan; Liu, Qiaoling; Qiu, Liping; Tan, Weihong

    2017-03-15

    In clinical diagnostics, as well as food and environmental safety practices, biosensors are powerful tools for monitoring biological or biochemical processes. Two-dimensional (2D) transition metal nanomaterials, including transition metal chalcogenides (TMCs) and transition metal oxides (TMOs), are receiving growing interest for their use in biosensing applications based on such unique properties as high surface area and fluorescence quenching abilities. Meanwhile, nucleic acid probes based on Watson-Crick base-pairing rules are also being widely applied in biosensing based on their excellent recognition capability. In particular, the emergence of functional nucleic acids in the 1980s, especially aptamers, has substantially extended the recognition capability of nucleic acids to various targets, ranging from small organic molecules and metal ions to proteins and cells. Based on π-π stacking interaction between transition metal nanosheets and nucleic acids, biosensing systems can be easily assembled. Therefore, the combination of 2D transition metal nanomaterials and nucleic acids brings intriguing opportunities in bioanalysis and biomedicine. In this review, we summarize recent advances of nucleic acid-functionalized transition metal nanosheets in biosensing applications. The structure and properties of 2D transition metal nanomaterials are first discussed, emphasizing the interaction between transition metal nanosheets and nucleic acids. Then, the applications of nucleic acid-functionalized transition metal nanosheet-based biosensors are discussed in the context of different signal transducing mechanisms, including optical and electrochemical approaches. Finally, we provide our perspectives on the current challenges and opportunities in this promising field. Copyright © 2016 Elsevier B.V. All rights reserved.

  4. Effects of sulfate on heavy metal release from iron corrosion scales in drinking water distribution system.

    Science.gov (United States)

    Sun, Huifang; Shi, Baoyou; Yang, Fan; Wang, Dongsheng

    2017-05-01

    Trace heavy metals accumulated in iron corrosion scales within a drinking water distribution system (DWDS) could potentially be released to bulk water and consequently deteriorate the tap water quality. The objective of this study was to identify and evaluate the release of trace heavy metals in DWDS under changing source water conditions. Experimental pipe loops with different iron corrosion scales were set up to simulate the actual DWDS. The effects of sulfate levels on heavy metal release were systemically investigated. Heavy metal releases of Mn, Ni, Cu, Pb, Cr and As could be rapidly triggered by sulfate addition but the releases slowly decreased over time. Heavy metal release was more severe in pipes transporting groundwater (GW) than in pipes transporting surface water (SW). There were strong positive correlations (R 2  > 0.8) between the releases of Fe and Mn, Fe and Ni, Fe and Cu, and Fe and Pb. When switching to higher sulfate water, iron corrosion scales in all pipe loops tended to be more stable (especially in pipes transporting GW), with a larger proportion of stable constituents (mainly Fe 3 O 4 ) and fewer unstable compounds (β-FeOOH, γ-FeOOH, FeCO 3 and amorphous iron oxides). The main functional iron reducing bacteria (IRB) communities were favorable for the formation of Fe 3 O 4 . The transformation of corrosion scales and the growth of sulfate reducing bacteria (SRB) accounted for the gradually reduced heavy metal release with time. The higher metal release in pipes transporting GW could be due to increased Fe 6 (OH) 12 CO 3 content under higher sulfate concentrations. Copyright © 2017 Elsevier Ltd. All rights reserved.

  5. Surface energy and work function of elemental metals

    DEFF Research Database (Denmark)

    Skriver, Hans Lomholt; Rosengaard, N. M.

    1992-01-01

    We have performed an ab initio study of the surface energy and the work function for six close-packed surfaces of 40 elemental metals by means of a Green’s-function technique, based on the linear-muffin-tin-orbitals method within the tight-binding and atomic-sphere approximations. The results...... are in excellent agreement with a recent full-potential, all-electron, slab-supercell calculation of surface energies and work functions for the 4d metals. The present calculations explain the trend exhibited by the surface energies of the alkali, alkaline earth, divalent rare-earth, 3d, 4d, and 5d transition...

  6. A Visual Insight into the Degradation of Metals Used in Drinking Water Distribution Systems Using AFM

    Science.gov (United States)

    Evaluating the fundamental corrosion and passivation of metallic copper used in drinking water distribution materials is important in understanding the overall mechanism of the corrosion process. Copper pipes are widely used for drinking water distribution systems and although it...

  7. Thioether-functionalized vegetable oils: Metal-absorbing biobased ligands

    Science.gov (United States)

    Vegetable oils containing thioether groups have been synthesized and used to effectively remove a heavy metal ion from an aqueous solution. The use of thioether-functionalized corn oil (TF-corn oil) and thioether-functionalized canola oil (TF-canola oil) were both effective in the extraction of Ag+ ...

  8. Numerical simulations of the metallicity distribution in dwarf spheroidal galaxies

    NARCIS (Netherlands)

    Ripamonti, E.; Tolstoy, E.; Helmi, A.; Battaglia, G.; Abel, T.

    2006-01-01

    Abstract: Recent observations show that the number of stars with very low metallicities in the dwarf spheroidal satellites of the Milky Way is low, despite the low average metallicities of stars in these systems. We undertake numerical simulations of star formation and metal enrichment of dwarf

  9. Density functional theory studies of transition metal nanoparticles in catalysis

    DEFF Research Database (Denmark)

    Greeley, Jeffrey Philip; Rankin, Rees; Zeng, Zhenhua

    2013-01-01

    Periodic Density Functional Theory calculations are capable of providing powerful insights into the structural, energetics, and electronic phenomena that underlie heterogeneous catalysis on transition metal nanoparticles. Such calculations are now routinely applied to single crystal metal surfaces...... and electrocatalysis, in which single crystal models are combined with Wulff construction-based ideas to produce descriptions of average nanocatalyst behavior. Then, I will proceed to describe explicitly DFT-based descriptions of catalysis on truly nanosized particles (

  10. Alkylamine functionalized metal-organic frameworks for composite gas separations

    Energy Technology Data Exchange (ETDEWEB)

    Long, Jeffrey R.; McDonald, Thomas M.; D' Alessandro, Deanna M.

    2018-01-09

    Functionalized metal-organic framework adsorbents with ligands containing basic nitrogen groups such as alkylamines and alkyldiamines appended to the metal centers and method of isolating carbon dioxide from a stream of combined gases and carbon dioxide partial pressures below approximately 1 and 1000 mbar. The adsorption material has an isosteric heat of carbon dioxide adsorption of greater than -60 kJ/mol at zero coverage using a dual-site Langmuir model.

  11. Spatial distribution of trace metals in sediments from urban streams of Semarang, Central Java, Indonesia.

    NARCIS (Netherlands)

    Widianarko, B.; Verweij, R.A.; van Gestel, C.A.M.; van Straalen, N.M.

    2000-01-01

    Elevated environmental concentrations of metals are usually associated with the impact of urbanization. The present study is focused on metal contamination in urban sediments. A field survey was carried out to determine the distribution of four metals, i.e., cadmium (Cd), lead (Pb), copper (Cu), and

  12. Trace-metal distributions in seawater and anoxic brines in the eastern Mediterranean Sea

    NARCIS (Netherlands)

    Saager, Paul M.; Schijf, Johan; Baar, Hein J.W. de; Millero, F.J.

    1993-01-01

    The vertical distribution of dissolved and particulate trace metals (Mn, Fe, Ni, Cu, Cd) is reported for seawater and the anoxic brines of Tyro and Bannock Basins in the eastern Mediterranean. In normal Mediterranean seawater, the distribution of dissolved trace metals is governed by water mass

  13. About the Distribution of Metal Objects in Prepalatial Crete

    Directory of Open Access Journals (Sweden)

    Borja Legarra Herrero

    2004-11-01

    Full Text Available Although metal objects have been used as evidence in different interpretations of the socioeconomic changes identified in Prepalatial Crete (c.3100-1900 BC, they constitute an understudied category of material. This paper argues that metal objects on Crete were subject to complex processes regarding the creation of meaning; a more comprehensive appraisal of metal objects on the island may cast new light on these issues. Copper-based, gold, lead and silver objects are investigated from their ore extraction locations outside Crete to their final deposition, linking the different steps of the process of creating an artefact with different layers of meanings for the metal and, subsequently, for the finished objects. This study evaluates differences in the use of metals, with a particular focus on their intra-island depositional patterns. It seeks to identify differences in the roles of metals within Cretan communities as well as regional fashions in the use of metal objects. It is suggested that metals had different characters since their depositional patterns vary, and that people consciously chose certain metals to make specific objects and also used metal objects in different ways, reflecting the socio-economic context for each region.

  14. DISTRIBUTION OF HEAVY METALS AMONG THE COMPONENTS OF FRESHWATER ECOSYSTEMS (REVIEW)

    OpenAIRE

    N. Kolesnyk

    2014-01-01

    Purpose. To review scientific sources on the distribution of heavy metals among the components of freshwater ecosystems. Findings. The review of the works of many scientists showed that heavy metals are widespread in the biotic and abiotic components of freshwater ecosystems. The article highlights the distribution of heavy metals in water, bottom sediments, natural food base, fish organs and tissues. It has been shown that as a result of global pollution of the ecosystem, the majority of...

  15. Metal-molecular assembly for functional materials

    CERN Document Server

    Matsuo, Yutaka; Negishi, Yuichi; Yoshizawa, Michito; Uemura, Takashi; Takaya, Hikaru; Takeuchi, Masayuki; Yoshimoto, Soichiro

    2013-01-01

    This book focuses on modern coordination chemistry, covering porous coordination polymers, metalloproteins, metallopeptides, nanoclusters, nanocapsules, aligned polymers, and fullerenes. As well, it deals with applications to electronic devices and surface characterization. These wide-ranging topics are integrally described from the perspectives of dimensionality (one-, two-, and three-dimension), new materials design, synthesis, molecular assembly, function and application. The nine chapters making up this book have been authored by scientists who are at the cutting edge of research in this p

  16. Influence of water on the work function of certain metals

    Science.gov (United States)

    MUSUMECI, FRANCESCO; POLLACK, GERALD H.

    2012-01-01

    Experiments were carried out to explore the effect of light on Au, Pt and Cu surfaces immersed in water, in order to study the changes of work function arising from the interaction between the metallic surfaces and water. The results show an action of liquid water about three times larger than that of low-temperature ice. Theoretical calculations, present in literature, have predicted values much lower than those we measured. The substantial changes in work function measured here appear to arise from the complex structure of water in the vicinity of the metal surface. PMID:22639466

  17. On optimality of the empirical distribution function for the estimation ...

    African Journals Online (AJOL)

    Administrateur

    Estimation of the Invariant Distribution function of a diffusion process. Ilia Negri, pp. 83-104 .... 1996), that is, there exists an invariant probability measure µ such that for every measurable function g such that E|g(ξ)| ..... distribution function because, in virtue of the strong law of large numbers, we have that for every x ∈ R the ...

  18. Strain engineering the work function in monolayer metal dichalcogenides

    International Nuclear Information System (INIS)

    Lanzillo, Nicholas A; Simbeck, Adam J; Nayak, Saroj K

    2015-01-01

    We use first-principles density functional theory to investigate the effect of both tensile and compressive strain on the work functions of various metal dichalcogenide monolayers. We find that for all six species considered, including MoS 2 , WS 2 , SnS 2 , VS 2 , MoSe 2 and MoTe 2 , that compressive strain of up to 10% decreases the work function continuously by as much as 1.0 eV. Large enough tensile strain is also found to decrease the work function, although in some cases we observe an increase in the work function for intermediate values of tensile strain. This work function modulation is attributed to a weakening of the chalcogenide-metal bonds and an increase in total energy of each system as a function of strain. Values of strain which bring the metal atoms closer together lead to an increase in electrostatic potential energy, which in turn results in an increase in the vacuum potential level. The net effect on the work function can be explained in terms of the balance between the increases in the vacuum potential levels and Fermi energy. (paper)

  19. Seasonal Metal Distribution in Ondo Coastal Sediment, Nigeria ...

    African Journals Online (AJOL)

    However, the impact of oil related activities within the study r egion may be contributing to the levels of other metals, particularly Pb. Significant correlations ( r = 0.05; 0.01) were record ed between some of the metals, pH and %clay in the mud fraction. Cadmium vs Ni and Cu vs Ni were both significant at both seasons.

  20. Occurrence and distribution of heavy metals in indoor settled ...

    African Journals Online (AJOL)

    The results showed widespread heavy metals contamination especially Fe and Zn, which were present as the highest concentration while Cd was the lowest in the settled particles (dust). The order of occurrence of heavy metals in settled particles (dust) collected indoor in 2007 and 2008 respectively were as follows, ...

  1. Distribution of Heavy Metals in the Coastal Marine Surficial ...

    African Journals Online (AJOL)

    the trend of pollution in coastal areas has been increasing over time. In Tanzania, heavy metals in sediments have been determined in the Dar es. Salaam harbour (Machiwa 1992, 2000) and along. River Msimbazi (A'khabuhaya and Lodenius. 1988). Heavy metals concentration have also been measured from sediments ...

  2. 12 Trace Metals Distribution in Fish Tissues, Bottom Sediments and ...

    African Journals Online (AJOL)

    `123456789jkl''''#

    2 Science Laboratory Technology Departments, Delta State Polytechnic, Otefe, Nigeria. 12 ... metals including both essential and non essential elements .... Source Lab Analysis 2010. Table 2. The trace metal concentration in Okumeshi River Water and comparison with water quality guidelines (mg/L). Guidelines. Cd. Cr.

  3. Parametric Probability Distribution Functions for Axon Diameters of Corpus Callosum

    Directory of Open Access Journals (Sweden)

    Farshid eSepehrband

    2016-05-01

    Full Text Available Axon diameter is an important neuroanatomical characteristic of the nervous system that alters in the course of neurological disorders such as multiple sclerosis. Axon diameters vary, even within a fiber bundle, and are not normally distributed. An accurate distribution function is therefore beneficial, either to describe axon diameters that are obtained from a direct measurement technique (e.g., microscopy, or to infer them indirectly (e.g., using diffusion-weighted MRI. The gamma distribution is a common choice for this purpose (particularly for the inferential approach because it resembles the distribution profile of measured axon diameters which has been consistently shown to be non-negative and right-skewed. In this study we compared a wide range of parametric probability distribution functions against empirical data obtained from electron microscopy images. We observed that the gamma distribution fails to accurately describe the main characteristics of the axon diameter distribution, such as location and scale of the mode and the profile of distribution tails. We also found that the generalized extreme value distribution consistently fitted the measured distribution better than other distribution functions. This suggests that there may be distinct subpopulations of axons in the corpus callosum, each with their own distribution profiles. In addition, we observed that several other distributions outperformed the gamma distribution, yet had the same number of unknown parameters; these were the inverse Gaussian, log normal, log logistic and Birnbaum-Saunders distributions.

  4. Sheet-bulk metal forming – forming of functional components from sheet metals

    Directory of Open Access Journals (Sweden)

    Merklein Marion

    2015-01-01

    Full Text Available The paper gives an overview on the application of sheet-bulk metal forming operations in both scientific and industrial environment. Beginning with the need for an innovative forming technology, the definition of this new process class is introduced. The rising challenges of the application of bulk metal forming operations on sheet metals are presented and the demand on a holistic investigation of this topic is motivated. With the help of examples from established production processes, the latest state of technology and the lack on fundamental knowledge is shown. Furthermore, perspectives regarding new research topics within sheet-bulk metal forming are presented. These focus on processing strategies to improve the quality of functional components by the application of process-adapted semi-finished products as well as the local adaption of the tribological system.

  5. Light Manipulation in Metallic Nanowire Networks with Functional Connectivity

    KAUST Repository

    Galinski, Henning

    2016-12-27

    Guided by ideas from complex systems, a new class of network metamaterials is introduced for light manipulation, which are based on the functional connectivity among heterogeneous subwavelength components arranged in complex networks. The model system is a nanonetwork formed by dealloying a metallic thin film. The connectivity of the network is deterministically controlled, enabling the formation of tunable absorbing states.

  6. Nutrients and heavy metal distribution in thermally treated pig manure

    DEFF Research Database (Denmark)

    Kuligowski, Ksawery; Poulsen, Tjalfe G.; Stoholm, Peder

    2008-01-01

    Ash from pig manure treated by combustion and thermal gasification was characterized and compared in terms of nutrient, i.e., potassium (K), phosphorus (P) and heavy metal, i.e., cadmium (Cd), chromium (Cr), copper (Cu), nickel (Ni) and zinc (Zn) contents. Total nutrient and metal concentrations...... that ash from gasified manure contained more water-extractable K in comparison with combusted manure whereas the opposite was the case with respect to P. Heavy metals Ni, Cr and Cd were present in higher concentrations in the fine particle size fractions (

  7. The metallicity distribution of stars in the Galactic bulge and disc

    Science.gov (United States)

    Koeppen, J.; Arimoto, N.

    1989-06-01

    The chemical evolution of the three-component system of halo-bulge-disc is calculated. If the bulge accretes primordial halo matter quickly and forms stars rapidly before the gas is ejected by a galactic wind after 10 to the 9th yr, the metallicity distribution of the bulge K-giants (Rich, 1988) is reproduced. The metal-enriched matter in a wind from the bulge is mixed with the halo gas which is accreted into the disc. The metallicity distribution of the G-dwarfs and Twarog's (1980) age-metallicity relation in the solar neighborhood can be well reproduced by assuming reasonable bulge-to-disc mass ratio.

  8. Maternal blood metal levels and fetal markers of metabolic function

    International Nuclear Information System (INIS)

    Ashley-Martin, Jillian; Dodds, Linda; Arbuckle, Tye E.; Ettinger, Adrienne S.; Shapiro, Gabriel D.; Fisher, Mandy; Taback, Shayne; Bouchard, Maryse F.; Monnier, Patricia; Dallaire, Renee; Fraser, William D.

    2015-01-01

    Exposure to metals commonly found in the environment has been hypothesized to be associated with measures of fetal growth but the epidemiological literature is limited. The Maternal–Infant Research on Environmental Chemicals (MIREC) study recruited 2001 women during the first trimester of pregnancy from 10 Canadian sites. Our objective was to assess the association between prenatal exposure to metals (lead, arsenic, cadmium, and mercury) and fetal metabolic function. Average maternal metal concentrations in 1st and 3rd trimester blood samples were used to represent prenatal metals exposure. Leptin and adiponectin were measured in 1363 cord blood samples and served as markers of fetal metabolic function. Polytomous logistic regression models were used to estimate odds ratios (OR) and 95% confidence intervals (CI) for the association between metals and both high (≥90%) and low (≤10%) fetal adiponectin and leptin levels. Leptin levels were significantly higher in female infants compared to males. A significant relationship between maternal blood cadmium and odds of high leptin was observed among males but not females in adjusted models. When adjusting for birth weight z-score, lead was associated with an increased odd of high leptin. No other significant associations were found at the top or bottom 10th percentile in either leptin or adiponectin models. This study supports the proposition that maternal levels of cadmium influence cord blood adipokine levels in a sex-dependent manner. Further investigation is required to confirm these findings and to determine how such findings at birth will translate into childhood anthropometric measures. - Highlights: • We determined relationships between maternal metal levels and cord blood adipokines. • Cord blood leptin levels were higher among female than male infants. • Maternal cadmium was associated with elevated leptin in male, not female infants. • No significant associations were observed between metals and

  9. Maternal blood metal levels and fetal markers of metabolic function

    Energy Technology Data Exchange (ETDEWEB)

    Ashley-Martin, Jillian [Perinatal Epidemiology Research Unit, Dalhousie University, Halifax, Nova Scotia (Canada); Dodds, Linda, E-mail: l.dodds@dal.ca [Perinatal Epidemiology Research Unit, Dalhousie University, Halifax, Nova Scotia (Canada); Arbuckle, Tye E. [Health Canada, Ottawa (Canada); Ettinger, Adrienne S. [Yale University, New Haven, CT (United States); Shapiro, Gabriel D. [University of Montreal, Montreal, Quebec (Canada); CHU Sainte-Justine Research Centre, Montreal, Quebec (Canada); Fisher, Mandy [Health Canada, Ottawa (Canada); Taback, Shayne [University of Manitoba, Winnipeg, Manitoba (Canada); Bouchard, Maryse F. [University of Montreal, Montreal, Quebec (Canada); Monnier, Patricia [McGill University, Montreal, Quebec (Canada); Dallaire, Renee [Laval University, Quebec City, Quebec (Canada); Fraser, William D. [University of Montreal, Montreal, Quebec (Canada); CHU Sainte-Justine Research Centre, Montreal, Quebec (Canada)

    2015-01-15

    Exposure to metals commonly found in the environment has been hypothesized to be associated with measures of fetal growth but the epidemiological literature is limited. The Maternal–Infant Research on Environmental Chemicals (MIREC) study recruited 2001 women during the first trimester of pregnancy from 10 Canadian sites. Our objective was to assess the association between prenatal exposure to metals (lead, arsenic, cadmium, and mercury) and fetal metabolic function. Average maternal metal concentrations in 1st and 3rd trimester blood samples were used to represent prenatal metals exposure. Leptin and adiponectin were measured in 1363 cord blood samples and served as markers of fetal metabolic function. Polytomous logistic regression models were used to estimate odds ratios (OR) and 95% confidence intervals (CI) for the association between metals and both high (≥90%) and low (≤10%) fetal adiponectin and leptin levels. Leptin levels were significantly higher in female infants compared to males. A significant relationship between maternal blood cadmium and odds of high leptin was observed among males but not females in adjusted models. When adjusting for birth weight z-score, lead was associated with an increased odd of high leptin. No other significant associations were found at the top or bottom 10th percentile in either leptin or adiponectin models. This study supports the proposition that maternal levels of cadmium influence cord blood adipokine levels in a sex-dependent manner. Further investigation is required to confirm these findings and to determine how such findings at birth will translate into childhood anthropometric measures. - Highlights: • We determined relationships between maternal metal levels and cord blood adipokines. • Cord blood leptin levels were higher among female than male infants. • Maternal cadmium was associated with elevated leptin in male, not female infants. • No significant associations were observed between metals and

  10. Particulate trace metals in Cochin backwaters: Distribution of seasonal indices

    Digital Repository Service at National Institute of Oceanography (India)

    Sankaranarayanan, V.N.; Jayalakshmy, K.V.; Joseph, T.

    A seasonal analysis of particulate trace metals, viz. iron, manganese, zinc, copper, cobalt and nickel collected from 4 stations in Cochin backwaters are presented. The spatial trend for cobalt, iron and nickel was stationary at surface whereas...

  11. Soil Protists Diversity, Distribution and Ecological Functioning

    OpenAIRE

    Geisen, Stefan

    2014-01-01

    Soil protists occupy key nodes in soil food webs due to their high abundance, fast turnover and functional importance as bacterial grazers. However, methodological drawbacks obscure the knowledge of soil protists, so that many taxa remain unknown. The structure of natural protist communities and taxa-specific ecological functions are also largely unknown. This thesis aims to increase the knowledge on soil protists using a variety of approaches. In the first part, naked amoebae being pres...

  12. Factorial moment -generating function and the Pascal distribution ...

    African Journals Online (AJOL)

    Given a distribution, the cumulants or factorial moments can be used to obtain the skewness and kurtosis which in turn are used to determine the normal approximation of the given distribution. It is shown in this paper that for the Pascal Distribution, the factorial moment generating function provides a simpler technique.

  13. Patterns of metal distribution in hypersaline microbialites during early diagenesis: Implications for the fossil record.

    Science.gov (United States)

    Sforna, M C; Daye, M; Philippot, P; Somogyi, A; van Zuilen, M A; Medjoubi, K; Gérard, E; Jamme, F; Dupraz, C; Braissant, O; Glunk, C; Visscher, P T

    2017-03-01

    The use of metals as biosignatures in the fossil stromatolite record requires understanding of the processes controlling the initial metal(loid) incorporation and diagenetic preservation in living microbialites. Here, we report the distribution of metals and the organic fraction within the lithifying microbialite of the hypersaline Big Pond Lake (Bahamas). Using synchrotron-based X-ray microfluorescence, confocal, and biphoton microscopies at different scales (cm-μm) in combination with traditional geochemical analyses, we show that the initial cation sorption at the surface of an active microbialite is governed by passive binding to the organic matrix, resulting in a homogeneous metal distribution. During early diagenesis, the metabolic activity in deeper microbialite layers slows down and the distribution of the metals becomes progressively heterogeneous, resulting from remobilization and concentration as metal(loid)-enriched sulfides, which are aligned with the lamination of the microbialite. In addition, we were able to identify globules containing significant Mn, Cu, Zn, and As enrichments potentially produced through microbial activity. The similarity of the metal(loid) distributions observed in the Big Pond microbialite to those observed in the Archean stromatolites of Tumbiana provides the foundation for a conceptual model of the evolution of the metal distribution through initial growth, early diagenesis, and fossilization of a microbialite, with a potential application to the fossil record. © 2016 John Wiley & Sons Ltd.

  14. Wild Fluctuations of Random Functions with the Pareto Distribution

    Directory of Open Access Journals (Sweden)

    Ming Li

    2013-01-01

    Full Text Available This paper provides the fluctuation analysis of random functions with the Pareto distribution. By the introduced concept of wild fluctuations, we give an alternative way to classify the fluctuations from those with light-tailed distributions. Moreover, the suggested term wildest fluctuation may be used to classify random functions with infinite variance from those with finite variances.

  15. Wigner Function of Density Operator for Negative Binomial Distribution

    International Nuclear Information System (INIS)

    Xu Xinglei; Li Hongqi

    2008-01-01

    By using the technique of integration within an ordered product (IWOP) of operator we derive Wigner function of density operator for negative binomial distribution of radiation field in the mixed state case, then we derive the Wigner function of squeezed number state, which yields negative binomial distribution by virtue of the entangled state representation and the entangled Wigner operator

  16. On optimality of the empirical distribution function for the estimation ...

    African Journals Online (AJOL)

    In this work we present some results on the optimality of the empirical distribution function as estimator of the invariant distribution function of an ergodic diffusion process. The results presented were obtained in different previous works under conditions that are are rewritten in a unified form that make comparable those ...

  17. Optical properties (bidirectional reflectance distribution function) of shot fabric

    NARCIS (Netherlands)

    Lu, Rong; Koenderink, Jan J.; Kappers, Astrid M L

    2000-01-01

    To study the optical properties of materials, one needs a complete set of the angular distribution functions of surface scattering from the materials. Here we present a convenient method for collecting a large set of bidirectional reflectance distribution function (BRDF) samples in the hemispherical

  18. Statistical exponential distribution function as distance indicator to stellar groups

    Science.gov (United States)

    Abdel Rahman, H.; Sabry, M. A.; Issa, I. A.

    2012-12-01

    In this paper, statistical distribution functions are developed for distance determination of stellar groups. This method depends on the assumption that, absolute magnitudes and apparent magnitudes follow an exponential distribution function. The developed approaches have been implemented to determine distances of some clusters and stellar associations. The comparison with the distances derived by different authors revealed good agreement.

  19. The Wigner distribution function in modal characterisation

    CSIR Research Space (South Africa)

    Mredlana, Prince

    2016-07-01

    Full Text Available function in modal characterisation P. MREDLANA1, D. NAIDOO1, C MAFUSIRE2, T. KRUGER2, A. DUDLEY1,3, A. FORBES1,3 1CSIR National Laser Centre, PO BOX 395, Pretoria 0001, South Africa. 2Department of Physics, Faculty of Natural and Agricultural... these modal weights is the main aim of the decomposition, the coefficients yield information about the amplitude and phase of the orthogonal modes. Using this, we can reconstruct the entire field. Let 𝑓 𝑥 be a field function in the spatial domain...

  20. Density functional theory studies of transition metal nanoparticles in catalysis

    DEFF Research Database (Denmark)

    Greeley, Jeffrey Philip; Rankin, Rees; Zeng, Zhenhua

    2013-01-01

    Periodic Density Functional Theory calculations are capable of providing powerful insights into the structural, energetics, and electronic phenomena that underlie heterogeneous catalysis on transition metal nanoparticles. Such calculations are now routinely applied to single crystal metal surfaces...... and to subnanometer metal clusters. Descriptions of catalysis on truly nanosized structures, however, are generally not as well developed. In this talk, I will illustrate different approaches to analyzing nanocatalytic phenomena with DFT calculations. I will describe case studies from heterogeneous catalysis...... and electrocatalysis, in which single crystal models are combined with Wulff construction-based ideas to produce descriptions of average nanocatalyst behavior. Then, I will proceed to describe explicitly DFT-based descriptions of catalysis on truly nanosized particles (

  1. Wigner's function and other distribution functions in mock phase spaces

    International Nuclear Information System (INIS)

    Balazs, N.L.; Jennings, B.K.

    1983-06-01

    This review deals with the methods of associating functions with quantum mechanical operators in such a manner that these functions should furnish conveniently semiclassical approximations. We present a unified treatment of methods and result which usually appear under the expressions Wigner's functions, Weyl's association, Kirkwood's expansion, Glauber's coherent state representation, etc.; we also construct some new associations. The mathematical paraphernalia are collected in the appendices

  2. Unexpectedly wide distributions in the stochastic synthesis of functionalized nanoparticles.

    Science.gov (United States)

    Waddell, Jack; Mullen, Douglas; Orr, Bradford; Banaszak Holl, Mark; Sander, Leonard

    2009-03-01

    Functionalized nanoparticles are promising devices with a variety of applications, such as the targeted delivery of chemotherapy drugs to cancer cells. Their properties depend on the specifics of the distribution of functional groups on the nanoparticle. Stochastic ligand conjugation is an efficient strategy for synthesizing large quantities of functionalized nanoparticles. We developed a kinetic model for the study of ligand distribution on a generation 5 poly(amidoamine) dendrimer, as measured by HPLC and SPR. We found a cooperative effect in single species ligation, leading to a broader-than-Poisson distribution of ligands on nanoparticles, and suggesting a high spatial correlation of functional groups.

  3. Plasma polymer-functionalized silica particles for heavy metals removal.

    Science.gov (United States)

    Akhavan, Behnam; Jarvis, Karyn; Majewski, Peter

    2015-02-25

    Highly negatively charged particles were fabricated via an innovative plasma-assisted approach for the removal of heavy metal ions. Thiophene plasma polymerization was used to deposit sulfur-rich films onto silica particles followed by the introduction of oxidized sulfur functionalities, such as sulfonate and sulfonic acid, via water-plasma treatments. Surface chemistry analyses were conducted by X-ray photoelectron spectroscopy and time-of-flight secondary ion mass spectroscopy. Electrokinetic measurements quantified the zeta potentials and isoelectric points (IEPs) of modified particles and indicated significant decreases of zeta potentials and IEPs upon plasma modification of particles. Plasma polymerized thiophene-coated particles treated with water plasma for 10 min exhibited an IEP of less than 3.5. The effectiveness of developed surfaces in the adsorption of heavy metal ions was demonstrated through copper (Cu) and zinc (Zn) removal experiments. The removal of metal ions was examined through changing initial pH of solution, removal time, and mass of particles. Increasing the water plasma treatment time to 20 min significantly increased the metal removal efficiency (MRE) of modified particles, whereas further increasing the plasma treatment time reduced the MRE due to the influence of an ablation mechanism. The developed particulate surfaces were capable of removing more than 96.7% of both Cu and Zn ions in 1 h. The combination of plasma polymerization and oxidative plasma treatment is an effective method for the fabrication of new adsorbents for the removal of heavy metals.

  4. Elaiophores: their taxonomic distribution, morphology and functions

    OpenAIRE

    Possobom, Clivia Carolina Fiorilo; Machado, Silvia Rodrigues

    2017-01-01

    ABSTRACT Elaiophores are floral glands that secrete non-volatile oils as a reward for their pollinators. Their secretions mediate a specialized interaction between oil-producing plants and a few species of oil-collecting bees - Apidae and Melittidae. The present review focuses on the morphological and functional aspects of these secretory structures. We also provide information on their chemistry and pollination ecology. Our survey is organized taxonomically among the plant families for which...

  5. Modelling chemical abundance distributions for dwarf galaxies in the Local Group: the impact of turbulent metal diffusion

    Science.gov (United States)

    Escala, Ivanna; Wetzel, Andrew; Kirby, Evan N.; Hopkins, Philip F.; Ma, Xiangcheng; Wheeler, Coral; Kereš, Dušan; Faucher-Giguère, Claude-André; Quataert, Eliot

    2018-02-01

    We investigate stellar metallicity distribution functions (MDFs), including Fe and α-element abundances, in dwarf galaxies from the Feedback in Realistic Environment (FIRE) project. We examine both isolated dwarf galaxies and those that are satellites of a Milky Way-mass galaxy. In particular, we study the effects of including a sub-grid turbulent model for the diffusion of metals in gas. Simulations that include diffusion have narrower MDFs and abundance ratio distributions, because diffusion drives individual gas and star particles towards the average metallicity. This effect provides significantly better agreement with observed abundance distributions in dwarf galaxies in the Local Group, including small intrinsic scatter in [α/Fe] versus [Fe/H] of ≲0.1 dex. This small intrinsic scatter arises in our simulations because the interstellar medium in dwarf galaxies is well mixed at nearly all cosmic times, such that stars that form at a given time have similar abundances to ≲0.1 dex. Thus, most of the scatter in abundances at z = 0 arises from redshift evolution and not from instantaneous scatter in the ISM. We find similar MDF widths and intrinsic scatter for satellite and isolated dwarf galaxies, which suggests that environmental effects play a minor role compared with internal chemical evolution in our simulations. Overall, with the inclusion of metal diffusion, our simulations reproduce abundance distribution widths of observed low-mass galaxies, enabling detailed studies of chemical evolution in galaxy formation.

  6. Field Performance of Three-Phase Amorphous Metal Core Distribution Transformers at Pearl Harbor, Hawaii

    Science.gov (United States)

    1990-08-01

    the electrical performance and operational reliability of the amorphous metal core transformers compared to conventional silicon- steel transformers...electrical performance and operational reliability of the amorphous metal core transformers compared to conventional silicon- steel transformers, and...electric utilities, power distribution I& PRICE CODE 17. SECURITY CLASIFICATION 1 0S. SECURITY CLASSIFICATION 19. SECURITY CLASSIFICATION 20. UMITATION OF

  7. Metal tolerant species distribution and richness in and around the ...

    African Journals Online (AJOL)

    Abstract. Plant species growing in and around 38 metal welding workshops in Benin City, Nigeria, were surveyed. Eragrostis tenella occurred most frequently in all the sites, followed by Amaranthus spinosus, Eleusine indica, while Cucurbita pepo occurred least. The family Poaceae, was identified in all the sites visited.

  8. Studies on the occurrence and distribution of heavy metals in ...

    African Journals Online (AJOL)

    The bacteria isolated and identified were. Bacillus subtilis, Bacillus licheniformis, Arthrobacter sp and Achromobacter sp. Fungi isolated were Saccharomyces cerevisiae, Candida utilissima and Sporobolomyces sp. The values for heavy metals for all zones are of public health significance and pose a threat to the survival of ...

  9. Metal Distribution and Bioaccumulation in Water and Fish of a ...

    African Journals Online (AJOL)

    A study was conducted to investigate the metal (copper, zinc and manganese) concentrations in the surface water and fish of a man-made lake receiving agricultural and domestic effluents in Ibadan, Nigeria. The lake (Main Lake, IITA) is a site of drinking water abstraction and the major water source for the surrounding ...

  10. Studies on the occurrence and distribution of heavy metals in ...

    African Journals Online (AJOL)

    EJIRO

    Perry (1978) reported that chromate poisoning causes skin cancer and liver damage. Abdulrahman (2001) also advanced reasons to support the fact that chromates are carcinogenic. Mercury is a very dangerous metal with high significant hazard. Ewan et al. (1998) observed that chronic exposure to mercury might result in ...

  11. Trace Metals Distribution in Fish Tissues, Bottom Sediments and ...

    African Journals Online (AJOL)

    ... of tilapia while the lowest concentration with a value of 0.04mg/kg was recorded in tilapia bone. In most of the fish samples, cadmium concentration was found to be above the maximum tolerable values provided by international institutions. Keywords: Trace metals, Fish Tissues, Water, Bottom sediments, Okumeshi River ...

  12. New Function of Seaports: Logistics and Distribution

    Directory of Open Access Journals (Sweden)

    Igor Jakomin

    2003-01-01

    Full Text Available The globalization process occurs in all the spheres of ourlife and its quantitative and spatial dimensions affect theworld's development. These trends lead the enterprises to concentrateon their core business and outsource some auxilimy oradditional parts of their production or se1vices. It is vital for theoperation in such conditions that the logistics functionssmoothly and reliably in all its segments.To provide an answer to the given hypothesis, I have dealtwith all the major questions linked to the phenomenon of seaportsand their role in the development of new logistical anddistributional function.

  13. Elaiophores: their taxonomic distribution, morphology and functions

    Directory of Open Access Journals (Sweden)

    Clivia Carolina Fiorilo Possobom

    Full Text Available ABSTRACT Elaiophores are floral glands that secrete non-volatile oils as a reward for their pollinators. Their secretions mediate a specialized interaction between oil-producing plants and a few species of oil-collecting bees - Apidae and Melittidae. The present review focuses on the morphological and functional aspects of these secretory structures. We also provide information on their chemistry and pollination ecology. Our survey is organized taxonomically among the plant families for which elaiophore occurrence has been confirmed -for the monocots, Iridaceae and Orchidaceae, and for the eudicots, Calceolariaceae, Cucurbitaceae, Krameriaceae, Malpighiaceae, Plantaginaceae, Primulaceae, Scrophulariaceae, Solanaceae and Stilbaceae. Most oil flowers are zygomorphic, bisexual, nectarless and present their elaiophores on the protective whorls or on the androecium. Trichomal elaiophores are reported in all of these families except Krameriaceae and Malpighiaceae, and they vary in the density and morphology of the trichomes. Epithelial elaiophores occur in some monocot representatives and in Krameriaceae and Malpighiaceae, and are similar among species. An intermediate type of elaiophore is reported in some species of Orchidaceae. Regardless of elaiophore type, these glands have similar subcellular features and secretion-release mechanisms. Finally, we note the dearth of information on elaiophore ultrastructure and functioning for several plant families.

  14. The GS09 double parton distribution functions

    Science.gov (United States)

    Gaunt, J. R.

    It is anticipated that hard double parton scattering (DPS) will occur frequently in the collisions of the LHC, producing interesting signals and significant backgrounds to certain single scattering processes. In order to make theoretical predictions of double scattering rates and properties, the double parton distributions (dPDFs) D_p^{j_1j_2}(x_1,x_2;Q_A,Q_B) are required. We discuss the first publicly available set of equal-scale (Q_A=Q_B) leading order dPDFs -- the GS09 dPDFs. A brief account is given describing how pQCD evolution effects and sum rule constraints (the latter derived by us) have been incorporated into this set of dPDFs. We then present a summary of a phenomenological investigation into same-sign W pair production conducted using GS09. In this, the DPS signal produced using GS09 is compared with that obtained using simple products of single PDFs multiplied by (1-x_1-x_2)^n, and the single scattering backgrounds (W+-W+-jj, di-boson and heavy flavour) are carefully calculated. It is found that the correlations in GS09 manifest themselves in non-trivial kinematic correlations between the W bosons. However, it is unlikely that these correlations will be measurable at the LHC in the near future owing to the fact that the background is significant even after cuts.

  15. The auroral O+ non-Maxwellian velocity distribution function revisited

    Directory of Open Access Journals (Sweden)

    D. Hubert

    1997-02-01

    Full Text Available New characteristics of O+ ion velocity distribution functions in a background of atomic oxygen neutrals subjected to intense external electromagnetic forces are presented. The one dimensional (1-D distribution function along the magnetic field displays a core-halo shape which can be accurately fitted by a two Maxwellian model. The Maxwellian shape of the 1-D distribution function around a polar angle of 21 ± 1° from the magnetic field direction is confirmed, taking into account the accuracy of the Monte Carlo simulations. For the first time, the transition of the O+ 1-D distribution function from a core halo shape along the magnetic field direction to the well-known toroidal shape at large polar angles, through the Maxwellian shape at polar angle of 21 ± 1° is properly explained from a generic functional of the velocity moments at order 2 and 4.

  16. Rocket measurement of auroral partial parallel distribution functions

    Science.gov (United States)

    Lin, C.-A.

    1980-01-01

    The auroral partial parallel distribution functions are obtained by using the observed energy spectra of electrons. The experiment package was launched by a Nike-Tomahawk rocket from Poker Flat, Alaska over a bright auroral band and covered an altitude range of up to 180 km. Calculated partial distribution functions are presented with emphasis on their slopes. The implications of the slopes are discussed. It should be pointed out that the slope of the partial parallel distribution function obtained from one energy spectra will be changed by superposing another energy spectra on it.

  17. Formation energies of rutile metal dioxides using density functional theory

    DEFF Research Database (Denmark)

    Martinez, Jose Ignacio; Hansen, Heine Anton; Rossmeisl, Jan

    2009-01-01

    We apply standard density functional theory at the generalized gradient approximation (GGA) level to study the stability of rutile metal oxides. It is well known that standard GGA exchange and correlation in some cases is not sufficient to address reduction and oxidation reactions. Especially......, Ge, Ti, Cr, Nb, W, Mo, and V, using the electrochemical series as reference. The mean absolute error of the formation energy is 0.29 eV using the revised Perdew-Burke-Ernzerhof (PBE) GGA functional. We believe that the reason for the success is due to the reference level being H-2 and H2O and not O-2...

  18. Welding residual stress distributions for dissimilar metal nozzle butt welds in pressurized water reactors

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Ji Soo; Kim, Ju Hee; Bae, Hong Yeol; OH, Chang Young; Kim, Yun Jae [Korea Univ., Seoul (Korea, Republic of); Lee, Kyungsoo [Korea Electric Power Research Institute, Daejeon (Korea, Republic of); Song, Tae Kwang [Korea Institute of Nuclear Safety, Daejeon (Korea, Republic of)

    2012-02-15

    In pressurized water nuclear reactors, dissimilar metal welds are susceptible to primary water stress corrosion cracking. To access this problem, accurate estimation of welding residual stresses is important. This paper provides general welding residual stress profiles in dissimilar metal nozzle butt welds using finite element analysis. By introducing a simplified shape for dissimilar metal nozzle butt welds, changes in the welding residual stress distribution can be seen using a geometry variable. Based on the results, a welding residual stress profile for dissimilar metal nozzle butt welds is proposed that modifies the existing welding residual stress profile for austenitic pipe butt welds.

  19. Leveraging Distributions in Physical Unclonable Functions

    Directory of Open Access Journals (Sweden)

    Wenjie Che

    2017-10-01

    Full Text Available A special class of Physical Unclonable Functions (PUFs referred to as strong PUFs can be used in novel hardware-based authentication protocols. Strong PUFs are required for authentication because the bit strings and helper data are transmitted openly by the token to the verifier, and therefore are revealed to the adversary. This enables the adversary to carry out attacks against the token by systematically applying challenges and obtaining responses in an attempt to machine learn, and later predict, the token’s response to an arbitrary challenge. Therefore, strong PUFs must both provide an exponentially large challenge space and be resistant to machine-learning attacks in order to be considered secure. We investigate a transformation called temperature–voltage compensation (TVCOMP, which is used within the Hardware-Embedded Delay PUF (HELP bit string generation algorithm. TVCOMP increases the diversity and unpredictability of the challenge–response space, and therefore increases resistance to model-building attacks. HELP leverages within-die variations in path delays as a source of random information. TVCOMP is a linear transformation designed specifically for dealing with changes in delay introduced by adverse temperature–voltage (environmental variations. In this paper, we show that TVCOMP also increases entropy and expands the challenge–response space dramatically.

  20. A Comment on Quantum Distribution Functions and the OSV Conjecture

    CERN Document Server

    Gómez, C; Gomez, Cesar; Montanez, Sergio

    2006-01-01

    Using the attractor mechanism and the relation between the quantization of $H^{3}(M)$ and topological strings on a Calabi Yau threefold $M$ we define a map from BPS black holes into coherent states. This map allows us to represent the Bekenstein-Hawking-Wald entropy as a quantum distribution function on the phase space $H^{3}(M)$. This distribution function is a mixed Husimi/anti-Husimi distribution corresponding to the different normal ordering prescriptions for the string coupling and deviations of the complex structure moduli. From the integral representation of this distribution function in terms of the Wigner distribution we recover the Ooguri-Strominger-Vafa (OSV) conjecture in the region "at infinity" of the complex structure moduli space. The physical meaning of the OSV corrections are briefly discussed in this limit.

  1. New control system: distribution of the GANICIEL functions

    International Nuclear Information System (INIS)

    David, L.; Lecorche, E.

    1992-01-01

    This report describes the material configurations of the various processors, and of the distribution between them of the different software functions which constitute the GANICIEL. (A.B.). 9 refs., 4 figs

  2. Transverse momentum dependent (TMD) parton distribution functions : status and prospects

    NARCIS (Netherlands)

    Angeles-Martinez, R.; Bacchetta, A.; Balitsky, I.I.; Boer, D.; Boglione, M.; Boussarie, R.; Ceccopieri, F.A.; Cherednikov, I.O.; Connor, P.; Echevarria, M. G.; Ferrera, G.; Luyando, J. Grados; Hautmann, F.; Jung, H.; Kasemets, T.; Kutak, K.; Lansberg, J.P.; Lelek, A.; Lykasov, G.; Martinez, J. D. Madrigal; Mulders, P. J.; Nocera, Emanuele R.; Petreska, E.; Pisano, C.; Placakyte, R.; Radescu, V.; Radici, M.; Schnell, G.; Scimemi, I.; Signori, A.; Szymanowski, L.; Monfared, S. Taheri; van der Veken, F.F.; van Haevermaet, H.J.; van Mechelen, P.; Vladimirov, A.; Wallon, S.

    2015-01-01

    We review transverse momentum dependent (TMD) parton distribution functions, their application to topical issues in high-energy physics phenomenology, and their theoretical connections with QCD resummation, evolution and factorization theorems. We illustrate the use of TMDs via examples of

  3. Three-dimensional coupled double-distribution-function lattice ...

    Indian Academy of Sciences (India)

    Ruo-Fan Qiu

    2017-11-14

    dimensional coupled double-distribution-function lattice. Boltzmann models for compressible Navier–Stokes equations. RUO-FAN QIU, YAN-CHENG YOU. ∗. , CHENG-XIANG ZHU, RONG-QIAN CHEN and JIAN-FENG ZHU.

  4. Numerical distribution functions of fractional unit root and cointegration tests

    DEFF Research Database (Denmark)

    MacKinnon, James G.; Nielsen, Morten Ørregaard

    We calculate numerically the asymptotic distribution functions of likelihood ratio tests for fractional unit roots and cointegration rank. Because these distributions depend on a real-valued parameter, b, which must be estimated, simple tabulation is not feasible. Partly due to the presence...

  5. On the representation of distributions with rational moment generating functions

    DEFF Research Database (Denmark)

    Bladt, Mogens; Nielsen, Bo Friis

    This paper addresses a question concerning the generality of certain parameterisations of distributions which have a multivariate rational moment generating function. It is shown that the class of bilateral matrix-exponential distributions, as introduced in [2], is strictly larger than...

  6. MATERIAL DEPENDENCE OF TEMPERATURE DISTRIBUTION IN MULTI-LAYER MULTI-METAL COOKWARE

    Directory of Open Access Journals (Sweden)

    MOHAMMADREZA SEDIGH

    2017-09-01

    Full Text Available Laminated structure is becoming more popular in cookware markets; however, there seems to be a lack of enough scientific studies to evaluate its pros and cons, and to show that how it functions. A numerical model using a finite element method with temperature-dependent material properties has been performed to investigate material and layer dependence of temperature distribution in multi-layer multi-metal plate exposed to irregular heating. Behavior of two parameters including mean temperature value and uniformity on the inner surface of plate under variations of thermal properties and geometrical conditions have been studied. The results indicate that conductive metals used as first layer in bi-layer plates have better thermal performance than those used in the second layer. In addition, since cookware manufacturers increasingly prefer to use all-clad aluminium plate, recently, this structure is analysed in the present study as well. The results show all-clad copper and aluminum plate possesses lower temperature gradient compared with single layer aluminum and all-clad aluminum core plates.

  7. Metallicity Distribution of Disk Stars and the Formation History of the Milky Way

    Science.gov (United States)

    Toyouchi, Daisuke; Chiba, Masashi

    2018-03-01

    We investigate the formation history of the stellar disk component in the Milky Way (MW) based on our new chemical evolution model. Our model considers several fundamental baryonic processes, including gas infall, reaccretion of outflowing gas, and radial migration of disk stars. Each of these baryonic processes in the disk evolution is characterized by model parameters that are determined by fitting to various observational data of the stellar disk in the MW, including the radial dependence of the metallicity distribution function (MDF) of the disk stars, which has recently been derived in the APOGEE survey. We succeeded to obtain the best set of model parameters that well reproduces the observed radial dependences of the mean, standard deviation, skewness, and kurtosis of the MDFs for the disk stars. We analyze the basic properties of our model results in detail to gain new insights into the important baryonic processes in the formation history of the MW. One of the remarkable findings is that outflowing gas, containing many heavy elements, preferentially reaccretes onto the outer disk parts, and this recycling process of metal-enriched gas is a key ingredient for reproducing the observed narrower MDFs at larger radii. Moreover, important implications for the radial dependence of gas infall and the influence of radial migration on the MDFs are also inferred from our model calculation. Thus, the MDF of disk stars is a useful clue for studying the formation history of the MW.

  8. Distribution and Evolution of Metals in the Magneticum Simulations

    Directory of Open Access Journals (Sweden)

    Klaus Dolag

    2017-08-01

    Full Text Available Metals are ideal tracers of the baryonic cycle within halos. Their composition is a fossil record connecting the evolution of the various stellar components of galaxies to the interaction with the environment by in- and out-flows. The Magneticum simulations allow us to study halos across a large range of masses and environments, from massive galaxy clusters containing hundreds of galaxies, down to isolated field galaxies. They include a detailed treatment of the chemo-energetic feedback from the stellar component and its evolution, as well as feedback from the evolution of supermassive black holes. Following the detailed evolution of various metal species and their relative composition due to continuing enrichment of the IGM and ICM by SNIa, SNII and AGB winds of the evolving stellar population is revealed the complex interplay of local star-formation processes, mixing, global baryonic flows, secular galactic evolution and environmental processes. We present results from the Magneticum simulations on the chemical properties of simulated galaxies and galaxy clusters, carefully comparing them to observations. We show that the simulations already reach a very high level of realism within their complex descriptions of the chemo-energetic feedback, successfully reproducing a large number of observed properties and scaling relations. Our simulated galaxies clearly indicate that there are no strong secondary parameters (such as star-formation rates at a fixed redshift driving the scatter in these scaling relations. The remaining differences clearly point to detailed physical processes, which have to be included in future simulations.

  9. Generalised partition functions: inferences on phase space distributions

    Directory of Open Access Journals (Sweden)

    R. A. Treumann

    2016-06-01

    Full Text Available It is demonstrated that the statistical mechanical partition function can be used to construct various different forms of phase space distributions. This indicates that its structure is not restricted to the Gibbs–Boltzmann factor prescription which is based on counting statistics. With the widely used replacement of the Boltzmann factor by a generalised Lorentzian (also known as the q-deformed exponential function, where κ = 1∕|q − 1|, with κ, q ∈ R both the kappa-Bose and kappa-Fermi partition functions are obtained in quite a straightforward way, from which the conventional Bose and Fermi distributions follow for κ → ∞. For κ ≠ ∞ these are subject to the restrictions that they can be used only at temperatures far from zero. They thus, as shown earlier, have little value for quantum physics. This is reasonable, because physical κ systems imply strong correlations which are absent at zero temperature where apart from stochastics all dynamical interactions are frozen. In the classical large temperature limit one obtains physically reasonable κ distributions which depend on energy respectively momentum as well as on chemical potential. Looking for other functional dependencies, we examine Bessel functions whether they can be used for obtaining valid distributions. Again and for the same reason, no Fermi and Bose distributions exist in the low temperature limit. However, a classical Bessel–Boltzmann distribution can be constructed which is a Bessel-modified Lorentzian distribution. Whether it makes any physical sense remains an open question. This is not investigated here. The choice of Bessel functions is motivated solely by their convergence properties and not by reference to any physical demands. This result suggests that the Gibbs–Boltzmann partition function is fundamental not only to Gibbs–Boltzmann but also to a large class of generalised Lorentzian distributions as well as to the

  10. Exact probability distribution function for the volatility of cumulative production

    Science.gov (United States)

    Zadourian, Rubina; Klümper, Andreas

    2018-04-01

    In this paper we study the volatility and its probability distribution function for the cumulative production based on the experience curve hypothesis. This work presents a generalization of the study of volatility in Lafond et al. (2017), which addressed the effects of normally distributed noise in the production process. Due to its wide applicability in industrial and technological activities we present here the mathematical foundation for an arbitrary distribution function of the process, which we expect will pave the future research on forecasting of the production process.

  11. Advanced Inverter Functions and Communication Protocols for Distribution Management

    Energy Technology Data Exchange (ETDEWEB)

    Nagarajan, Adarsh; Palmintier, Bryan; Baggu, Murali

    2016-05-05

    This paper aims at identifying the advanced features required by distribution management systems (DMS) service providers to bring inverter-connected distributed energy resources into use as an intelligent grid resource. This work explores the standard functions needed in the future DMS for enterprise integration of distributed energy resources (DER). The important DMS functionalities such as DER management in aggregate groups, including the discovery of capabilities, status monitoring, and dispatch of real and reactive power are addressed in this paper. It is intended to provide the industry with a point of reference for DER integration with other utility applications and to provide guidance to research and standards development organizations.

  12. Spatial Distribution of Heavy Metals in the Surface Sediments of the Southern Coast of Pacitan, Indonesia

    Directory of Open Access Journals (Sweden)

    Defri Yona

    2018-02-01

    Full Text Available This study was conducted to analyze the spatial distribution of heavy metals from four different coastal areas in southern Pacitan, Indonesia: Pantai Watu Karung (WK, Pantai Teleng Ria (TL, Pantai Pancer (TP dan Pantai Soge (SG. Data collected in this study included: temperature, salinity, DO, pH, sediment, organic matter and heavy metals in the sediments (Pb, Hg and Cd. The results showed different distribution patterns of heavy metals. Heavy metal concentrations, especially Pb and Hg, were found to be higher in Pantai Soge, while the concentration of Cd was higher in Pantai Pancer. An ANOVA test showed the distributions of Pb and Cd were significantly different (p < 0.01 between sampling sites. Variability of the physicochemical parameters influenced the variabilities of heavy metal concentrations among sampling sites. Overall, heavy metal concentrations in the study areas are rather low; however, attention is still needed due to heavy activities in the coastal areas of southern Pacitan that can contribute to heavy metal pollution.

  13. Distribution of dissolved and particulate metals in Antarctic sea ice

    NARCIS (Netherlands)

    Lannuzel, D.; Bowie, A.R.; van der Merwe, P.C.; Townsend, A.T.; Schoemann, V.

    2011-01-01

    Samples were collected in East Antarctic sea ice in late winter/early austral spring 2007 to assess the distributions of Al, Cr, Mn, Cu, Zn, Mo. Cd and Ba. Total dissolved (<02 mu m) and particulate (>0.2 mu m) concentrations were measured by Inductively Coupled Plasma-Sector Field Mass Spectrometry

  14. Effective heavy metal removal from aqueous systems by thiol functionalized magnetic mesoporous silica

    International Nuclear Information System (INIS)

    Li Guoliang; Zhao Zongshan; Liu Jiyan; Jiang Guibin

    2011-01-01

    A thiol-functionalized magnetic mesoporous silica material (called SH-mSi-Fe 3 O 4 ), synthesized by a modified Stoeber method, has been investigated as a convenient and effective adsorbent for heavy metal ions. Structural characterization by powder X-ray diffraction, N 2 adsorption-desorption isotherm, Fourier transform infrared spectroscopy and elemental analyses confirms the mesoporous structure and the organic moiety content of this adsorbent. The high saturation magnetization (38.4 emu/g) make it easier and faster to be separated from water under a moderate magnetic field. Adsorption kinetics was elucidated by pseudo-second-order kinetic equation and exhibited 3-stage intraparticle diffusion mode. Adsorption isotherms of Hg and Pb fitted well with Langmuir model, exhibiting high adsorption capacity of 260 and 91.5 mg of metal/g of adsorbent, respectively. The distribution coefficients of the tested metal ions between SH-mSi-Fe 3 O 4 and different natural water sources (groundwater, lake water, tap water and river water) were above the level of 10 5 mL/g. The material was very stable in different water matrices, even in strong acid and alkaline solutions. Metal-loaded SH-mSi-Fe 3 O 4 was able to regenerate in acid solution under ultrasonication. This novel SH-mSi-Fe 3 O 4 is suitable for repeated use in heavy metal removal from different water matrices.

  15. Assembly, Structure, and Functionality of Metal-Organic Networks and Organic Semiconductor Layers at Surfaces

    Science.gov (United States)

    Tempas, Christopher D.

    Self-assembled nanostructures at surfaces show promise for the development of next generation technologies including organic electronic devices and heterogeneous catalysis. In many cases, the functionality of these nanostructures is not well understood. This thesis presents strategies for the structural design of new on-surface metal-organic networks and probes their chemical reactivity. It is shown that creating uniform metal sites greatly increases selectivity when compared to ligand-free metal islands. When O2 reacts with single-site vanadium centers, in redox-active self-assembled coordination networks on the Au(100) surface, it forms one product. When O2 reacts with vanadium metal islands on the same surface, multiple products are formed. Other metal-organic networks described in this thesis include a mixed valence network containing Pt0 and PtII and a network where two Fe centers reside in close proximity. This structure is stable to temperatures >450 °C. These new on-surface assemblies may offer the ability to perform reactions of increasing complexity as future heterogeneous catalysts. The functionalization of organic semiconductor molecules is also shown. When a few molecular layers are grown on the surface, it is seen that the addition of functional groups changes both the film's structure and charge transport properties. This is due to changes in both first layer packing structure and the pi-electron distribution in the functionalized molecules compared to the original molecule. The systems described in this thesis were studied using high-resolution scanning tunneling microscopy, non-contact atomic force microscopy, and X-ray photoelectron spectroscopy. Overall, this work provides strategies for the creation of new, well-defined on-surface nanostructures and adds additional chemical insight into their properties.

  16. PM2.5-bound metal metabolic distribution and coupled lipid abnormality at different developmental windows.

    Science.gov (United States)

    Ku, Tingting; Zhang, Yingying; Ji, Xiaotong; Li, Guangke; Sang, Nan

    2017-09-01

    Atmospheric fine particulate matter (PM 2.5 ) is a serious threat to human health. As a toxicant constituent, metal leads to significant health risks in a population, but exposure to PM 2.5 -bound metals and their biological impacts are not fully understood. In this study, we determined the metal contents of PM 2.5 samples collected from a typical coal-burning city and then investigated the metabolic distributions of six metals (Zn, Pb, Mn, As, Cu, and Cd) following PM 2.5 inhalation in mice in different developmental windows. The results indicate that fine particles were mainly deposited in the lung, but PM 2.5 -bound metals could reach and gather in secondary off-target tissues (the lung, liver, heart and brain) with a developmental window-dependent property. Furthermore, elevations in triglycerides and cholesterol levels in sensitive developmental windows (the young and elderly stages) occurred, and significant associations between metals (Pb, Mn, As and Cd) and cholesterol in the heart, brain, liver and lung were observed. These findings suggest that PM 2.5 inhalation caused selective metal metabolic distribution in tissues with a developmental window-dependent property and that the effects were associated with lipid alterations. This provides a foundation for the underlying systemic toxicity following PM 2.5 exposure based on metal components. Copyright © 2017 Elsevier Ltd. All rights reserved.

  17. Modelling chelate-Induced phytoextraction: functional models predicting bioavailability of metals in soil, metal uptake and shoot biomass

    Directory of Open Access Journals (Sweden)

    Pasqualina Sacco

    Full Text Available Chelate-induced phytoextraction of heavy metals from contaminated soils requires special care to determine, a priori, the best method of chelate application, in terms of both dose and timing. In fact, the chelate dose must assure the bioavailability of the metal to the plant without increasing leaching risk and giving toxic effects. Three mathematical models are here proposed for usefully interpreting the processes taking place: a increased soil bioavailability of metals by chelants; b metal uptake by plants; c variation in plant biomass. The models are implemented and validated using data from pot and lysimeter trials. Both the chelate dose and the time elapsed since its application affected metal bioavailability and plant response. Contrariwise, the distribution strategy (single vs. split application seems to produce significant differences both in plant growth and metal uptake, but not in soil metal bioavailability. The proposed models may help to understand and predict the chelate dose – effect relationship with less experimental work.

  18. Estimation of flux distributions with Monte Carlo functional expansion tallies

    International Nuclear Information System (INIS)

    Griesheimer, D. P.; Martin, W. R.; Holloway, J. P.

    2005-01-01

    Monte Carlo methods provide a powerful technique for estimating the average radiation flux in a volume (or across a surface) in cases where analytical solutions may not be possible. Unfortunately, Monte Carlo simulations typically provide only integral results and do not offer any further details about the distribution of the flux with respect to space, angle, time or energy. In the functional expansion tally (FET) a Monte Carlo simulation is used to estimate the functional expansion coefficients for flux distributions with respect to an orthogonal set of basis functions. The expansion coefficients are then used in post-processing to reconstruct a series approximation to the true distribution. Discrete event FET estimators are derived and their application in estimating radiation flux or current distributions is demonstrated. Sources of uncertainty in the FET are quantified and estimators for the statistical and truncation errors are derived. Numerical results are presented to support the theoretical development. (authors)

  19. Ammonia and hydrazine. Transition-metal-catalyzed hydroamination and metal-free catalyzed functionalization

    Energy Technology Data Exchange (ETDEWEB)

    Bertrand, Guy [Univ. of California, San Diego, CA (United States)

    2012-06-29

    The efficient and selective preparation of organic molecules is critical for mankind. For the future, it is of paramount importance to find catalysts able to transform abundant and cheap feedstocks into useful compounds. Acyclic and heterocyclic nitrogen-containing derivatives are common components of naturally occurring compounds, agrochemicals, cosmetics, and pharmaceuticals; they are also useful intermediates in a number of industrial processes. One of the most widely used synthetic strategies, allowing the formation of an N-C bond, is the addition of an N-H bond across a carbon-carbon multiple bond, the so-called hydroamination reaction. This chemical transformation fulfills the principle of “green chemistry” since it ideally occurs with 100% atom economy. Various catalysts have been found to promote this reaction, although many limitations remain; one of the most prominent is the lack of methods that permit the use of NH3 and NH2NH2 as the amine partners. In fact, ammonia and hydrazine have rarely succumbed to homogeneous catalytic transformations. Considering the low cost and abundance of ammonia (136 million metric tons produced in 2011) and hydrazine, catalysts able to improve the reactivity and selectivity of the NH3- and NH2NH2-hydroamination reaction, and more broadly speaking the functionalization of these chemicals, are highly desirable. In the last funded period, we discovered the first homogeneous catalysts able to promote the hydroamination of alkynes and allenes with ammonia and the parent hydrazine. The key feature of our catalytic systems is that the formation of catalytically inactive Werner complexes is reversible, in marked contrast to most of the known ammonia and hydrazine transition metal complexes. This is due to the peculiar electronic properties of our neutral ancillary ligands, especially their strong donating capabilities. However, our catalysts currently require

  20. Development of cumulative distribution functions for dry bulb ...

    African Journals Online (AJOL)

    The probability density function (PDF) and cumulative distribution function (CDF) for eighteen locations in Nigeria were computed from long term hourly dry bulb temperature obtained from Nigerian Meteorological Services Agency, Oshodi, Nigeria for 1994-2008 or 1995-2009. Mathematical models were developed from the ...

  1. The Distribution of Heavy Metal Pollutants in Suez Bay Using Geographic Information System (GIS)

    International Nuclear Information System (INIS)

    Hassan, H.B.; Mohamed, W.M.

    2017-01-01

    Suez city represents the southern entrance of the Suez Canal. As a result of the rapid development of industrialization and anthropogenic activities of Suez city may be entered containments such as heavy metals through Suez bay boundaries. The geographical information system (Arc GIS 9.1) is used to study the spatial distribution of heavy metals concentrations (Cd, Mn, Fe, Ni, Pb, Cu and Zn) of water samples which were collected in four different sampling sites (I, II, III and IV) from Suez bay. In this study, tabular data representation of the spatial distribution was developed using the inverse distance weighted (IDW) interpolation method. The GIS technique was applied to transfer the information into a final map illustrating the spatial distribution of heavy metals within the studied area. GIS models showed the high concentrations of heavy metals in some sites in the Suez city affecting by their activities. An overall distribution map of heavy metals is observed from GIS special analysis. Site (IV) in Suez City demonstrated the highest polluted are a in the overall distribution map

  2. Electron polarization function and plasmons in metallic armchair graphene nanoribbons

    DEFF Research Database (Denmark)

    Shylau, A. A.; Badalyan, S. M.; Peeters, F. M.

    2015-01-01

    Plasmon excitations in metallic armchair graphene nanoribbons are investigated using the random phase approximation. An exact analytical expression for the polarization function of Dirac fermions is obtained, valid for arbitrary temperature and doping. We find that at finite temperatures, due...... mode whose energy dispersion is determined by the graphene's fine structure constant. In the case of two Coulomb-coupled nanoribbons, this plasmon splits into in-phase and out-of-phase plasmon modes with splitting energy determined by the inter-ribbon spacing....

  3. Application of Density Functional Theory to Systems Containing Metal Atoms

    Science.gov (United States)

    Bauschlicher, Charles W., Jr.

    2006-01-01

    The accuracy of density functional theory (DFT) for problems involving metal atoms is considered. The DFT results are compared with experiment as well as results obtained using the coupled cluster approach. The comparisons include geometries, frequencies, and bond energies. The systems considered include MO2, M(OH)+n, MNO+, and MCO+2. The DFT works well for frequencies and geometries, even in case with symmetry breaking; however, some examples have been found where the symmetry breaking is quite severe and the DFT methods do not work well. The calculation of bond energies is more difficult and examples of successes as well as failures of DFT will be given.

  4. DISTRIBUTION OF HEAVY METALS AMONG THE COMPONENTS OF FRESHWATER ECOSYSTEMS (REVIEW

    Directory of Open Access Journals (Sweden)

    N. Kolesnyk

    2014-09-01

    Full Text Available Purpose. To review scientific sources on the distribution of heavy metals among the components of freshwater ecosystems. Findings. The review of the works of many scientists showed that heavy metals are widespread in the biotic and abiotic components of freshwater ecosystems. The article highlights the distribution of heavy metals in water, bottom sediments, natural food base, fish organs and tissues. It has been shown that as a result of global pollution of the ecosystem, the majority of Ukrainian rivers belong to polluted and very polluted. Of special interest are the studies of the distribution of heavy metals in phytoplankton, zooplankton, and zoobenthos because these components occupy a certain position in fish food chain. The presence of heavy metals in the natural food base showed that, on one hand, it could accumulate heavy metals in large amounts in such a way cleaning the water; and on the other hand, the heavy metals could migrate in the food web and contaminate fish. Ones of objects, which should be given attention when assessing toxicologic pollution, are aquatic plants, in particular phytoplankton. Studies showed that the accumulation of heavy metals in plants occurred first of all by their adsorption on the cellular wall. It explains the maximum adsorption of heavy metals by plants immediately after introduction of heavy metals into their culture. Fish as a rule occupy in the food web of water bodies one of the last places. They actively move in the aquatic environment and accumulating heavy metals at the same time they provide the most integrated and precise estimate of environmental pollution. By analyzing the distribution of heavy metals in fish organs and tissues, depending on their ability to accumulate them, it can be noted that the accumulation is the most intensive in such organs as gills, liver, and kidneys. Usually, their lowest content is observed in muscles that is important for human life because they are the main

  5. Functional Role of Infective Viral Particles on Metal Reduction

    Energy Technology Data Exchange (ETDEWEB)

    Coates, John D.

    2014-04-01

    A proposed strategy for the remediation of uranium (U) contaminated sites was based on the immobilization of U by reducing the oxidized soluble U, U(VI), to form a reduced insoluble end product, U(IV). Previous studies identified Geobacter sp., including G. sulfurreducens and G. metallireducens, as predominant U(VI)-reducing bacteria under acetate-oxidizing and U(VI)-reducing conditions. Examination of the finished genome sequence annotation of the canonical metal reducing species Geobacter sulfurreducens strain PCA and G. metallireduceans strain GS-15 as well as the draft genome sequence of G. uraniumreducens strain Rf4 identified phage related proteins. In addition, the completed genome for Anaeromyxobacter dehalogenans and the draft genome sequence of Desulfovibrio desulfuricans strain G20, two more model metal-reducing bacteria, also revealed phage related sequences. The presence of these gene sequences indicated that Geobacter spp., Anaeromyxobacter spp., and Desulfovibrio spp. are susceptible to viral infection. Furthermore, viral populations in soils and sedimentary environments in the order of 6.4×10{sup 6}–2.7×10{sup 10} VLP’s cm{sup -3} have been observed. In some cases, viral populations exceed bacterial populations in these environments suggesting that a relationship may exist between viruses and bacteria. Our preliminary screens of samples collected from the ESR FRC indicated that viral like particles were observed in significant numbers. The objective of this study was to investigate the potential functional role viruses play in metal reduction specifically Fe(III) and U(VI) reduction, the environmental parameters affecting viral infection of metal reducing bacteria, and the subsequent effects on U transport.

  6. Distribution of metals in vacuum residuums, asphaltenes and maltenes by PIXE

    International Nuclear Information System (INIS)

    Romero G, E.T.; Camacho M, V.; Sanchez B, A.C.; Lopez M, J.; Ramirez T, J.J.; Villasenor S, P.; Aspiazu F, J.A.

    2001-01-01

    The PIXE technique for determining directly the distribution and abundance of trace metals in vacuum residuum, asphaltenes and maltenes separated with n-alkanes (C 5 -C 8 ) is used. The metal content of petroleum derivatives revealed that the vacuum residuum contains iron, aluminium, vanadium and nickel mainly, while that the asphaltenes and maltenes maintain inside of their composition only preferably the vanadium and nickel as majority elements. (Author)

  7. Biogeochemical studies on the distribution of heavy metals in the Elbe estuary

    OpenAIRE

    Ahlf, Wolfgang; Calmano, Wolfgang; Förstner, Ulrich

    1990-01-01

    [Introduction] The mixing of riverwater and seawater in an estuary is accompanied by a large number of biogeochemical and physical processes which change the distribution, partitioning and bioavailability of contaminants. Superimposed particulates may take place, which cause deviations from the theoretical mixing curve between dissolved metal ions and salinity. Seasonal fluctuations and year-to-year variations in concentrations of trace metals must be considered in characterizing the importan...

  8. Trace metal distributions in Posidonia oceanica and sediments from Taranto Gulf (Ionian Sea, Southern Italy

    Directory of Open Access Journals (Sweden)

    A. DI LEO

    2013-03-01

    Full Text Available Distribution of metals (Hg, Pb, Sn, Cu, Cd and Zn was determined in sediments and in different tissues of Posidonia oceanica collected from San Pietro Island, Taranto Gulf (Ionian Sea, Southern Italy. In seagrass, results, compared with metal concentrations in sediments, showed that the highest concentrations of Hg, Pb, Sn and Cu were found in the roots, while in the green leaves were found the highest levels of Cd and Zn. Instead the lowest metal concentrations were found in the basal part of the leaf. Levels of  metals in the leaves were similar to those found by other authors in uncontaminated areas of the Mediterranean Sea. Mercury levels in roots were correlated to levels in sediments. This could demonstrate the plant memorizes sediments contamination . This study reinforces the usefulness and the relevance of Posidonia oceanica as an indicator of spatial metal contamination and an interesting tool for environmental quality evaluation.

  9. Distribution of seven heavy metals among hot pepper plant parts.

    Science.gov (United States)

    Antonious, George F

    2016-01-01

    The main objective of this investigation was to monitor concentrations of seven metals (Cd, Pb, Ni, Mo, Cu, Zn, and Cr) in the fruits, leaves, stem, and roots of Capsicum annuum L. (cv. Xcatic) plants grown under four soil management practices: yard waste (YW), sewage sludge (SS), chicken manure (CM), and no-much (NM) bare soil. Elemental analyses were conducted using inductively coupled plasma mass spectrometer. Pb and Cd concentrations in soil amended with YW, SS, and CM were not significantly different (P fruits of plants grown in NM soil were greater compared to the fruits of plants grown in other treatments. Total Ni concentration (sum of Ni in all plant parts) in plants grown in NM bare soil was greater than in plants grown in SS-, YW-, and CM-amended soils. Values of the bioaccumulation factor indicated that pepper fruits of plants grown in YW, SS, and CM did not show any tendency to accumulate Pb, Cr, and Ni in their edible fruits.

  10. Uptake and distribution of soil-applied labelled heavy metals in cereal plants and products

    International Nuclear Information System (INIS)

    Oberlaender, H.E.; Roth, K.

    1983-01-01

    In the present paper investigations are described on the uptake, distribution and translocation of mercury, cadmium, chromium and zinc by spring and winter varieties of wheat, rye and barley. Pot experiments were carried out at low concentrations of the heavy metals in order to avoid growth interference during the uptake. Using radioisotopes the pathway of the metals was traced through different organs into the milling products. An ion-exchanger was added to the soils and its efficiency of reducing the uptake of the metals by the plants was tested

  11. Assessment of spatial distribution of soil heavy metals using ANN-GA, MSLR and satellite imagery.

    Science.gov (United States)

    Naderi, Arman; Delavar, Mohammad Amir; Kaboudin, Babak; Askari, Mohammad Sadegh

    2017-05-01

    This study aims to assess and compare heavy metal distribution models developed using stepwise multiple linear regression (MSLR) and neural network-genetic algorithm model (ANN-GA) based on satellite imagery. The source identification of heavy metals was also explored using local Moran index. Soil samples (n = 300) were collected based on a grid and pH, organic matter, clay, iron oxide contents cadmium (Cd), lead (Pb) and zinc (Zn) concentrations were determined for each sample. Visible/near-infrared reflectance (VNIR) within the electromagnetic ranges of satellite imagery was applied to estimate heavy metal concentrations in the soil using MSLR and ANN-GA models. The models were evaluated and ANN-GA model demonstrated higher accuracy, and the autocorrelation results showed higher significant clusters of heavy metals around the industrial zone. The higher concentration of Cd, Pb and Zn was noted under industrial lands and irrigation farming in comparison to barren and dryland farming. Accumulation of industrial wastes in roads and streams was identified as main sources of pollution, and the concentration of soil heavy metals was reduced by increasing the distance from these sources. In comparison to MLSR, ANN-GA provided a more accurate indirect assessment of heavy metal concentrations in highly polluted soils. The clustering analysis provided reliable information about the spatial distribution of soil heavy metals and their sources.

  12. Fate and Distribution of Heavy Metals in Wastewater Irrigated Calcareous Soils

    Directory of Open Access Journals (Sweden)

    Mohammed Hashem Stietiya

    2014-01-01

    Full Text Available Accumulation of heavy metals in Jordanian soils irrigated with treated wastewater threatens agricultural sustainability. This study was carried out to investigate the environmental fate of Zn, Ni, and Cd in calcareous soils irrigated with treated wastewater and to elucidate the impact of hydrous ferric oxide (HFO amendment on metal redistribution among soil fractions. Results showed that sorption capacity for Zarqa River (ZR1 soil was higher than Wadi Dhuleil (WD1 soil for all metals. The order of sorption affinity for WD1 was in the decreasing order of Ni > Zn > Cd, consistent with electrostatic attraction and indication of weak association with soil constituents. Following metal addition, Zn and Ni were distributed among the carbonate and Fe/Mn oxide fractions, while Cd was distributed among the exchangeable and carbonate fractions in both soils. Amending soils with 3% HFO did not increase the concentration of metals associated with the Fe/Mn oxide fraction or impact metal redistribution. The study suggests that carbonates control the mobility and bioavailability of Zn, Ni, and Cd in these calcareous soils, even in presence of a strong adsorbent such as HFO. Thus, it can be inferred that in situ heavy metal remediation of these highly calcareous soils using iron oxide compounds could be ineffective.

  13. Fate and Distribution of Heavy Metals in Wastewater Irrigated Calcareous Soils

    Science.gov (United States)

    Stietiya, Mohammed Hashem; Duqqah, Mohammad; Udeigwe, Theophilus; Zubi, Ruba; Ammari, Tarek

    2014-01-01

    Accumulation of heavy metals in Jordanian soils irrigated with treated wastewater threatens agricultural sustainability. This study was carried out to investigate the environmental fate of Zn, Ni, and Cd in calcareous soils irrigated with treated wastewater and to elucidate the impact of hydrous ferric oxide (HFO) amendment on metal redistribution among soil fractions. Results showed that sorption capacity for Zarqa River (ZR1) soil was higher than Wadi Dhuleil (WD1) soil for all metals. The order of sorption affinity for WD1 was in the decreasing order of Ni > Zn > Cd, consistent with electrostatic attraction and indication of weak association with soil constituents. Following metal addition, Zn and Ni were distributed among the carbonate and Fe/Mn oxide fractions, while Cd was distributed among the exchangeable and carbonate fractions in both soils. Amending soils with 3% HFO did not increase the concentration of metals associated with the Fe/Mn oxide fraction or impact metal redistribution. The study suggests that carbonates control the mobility and bioavailability of Zn, Ni, and Cd in these calcareous soils, even in presence of a strong adsorbent such as HFO. Thus, it can be inferred that in situ heavy metal remediation of these highly calcareous soils using iron oxide compounds could be ineffective. PMID:24723833

  14. Grain size effect on trace metals distribution in sediments from two coastal areas of Chile

    Energy Technology Data Exchange (ETDEWEB)

    I. De Gregori, H.; H. Pinochet, C.; M. Arancibia, J.; A. Vidal, B. [Universidad Catolica de Valparaiso, Casilla (Chile)

    1996-07-01

    Marine environment contamination by trace metals has received increased global attention during recent years. Presently it is widely recognized that marine ecosystem can become contaminated by trace metals from numerous and diverse sources. However, anthropogenic activities, such as mining and industrial processing of ores and metals, still remain the principal cause of the increased amount of heavy metals which have been dumped into oceans. After entering the aquatic environment trace metals are distributed among water, biotic and sediment compartments, this latter serving as a final sink for metal pollutants. The magnitude of this scavenging action of sediments depends on the physical, chemical and biological properties of the sediments. Concentrations of trace metals in sediments are usually of a greater magnitude order than concentrations in water. Sediments were considered as an important indicator for environmental pollution, they act as permanent or temporary traps for material spread into the environment. The purpose of this study was to determine the grain size effect on the copper, cadmium and zinc levels distribution in surface marine sediments along the Chilean Coast. 18 refs., 1 fig., 1 tab.

  15. Stand diameter distribution modelling and prediction based on Richards function.

    Directory of Open Access Journals (Sweden)

    Ai-guo Duan

    Full Text Available The objective of this study was to introduce application of the Richards equation on modelling and prediction of stand diameter distribution. The long-term repeated measurement data sets, consisted of 309 diameter frequency distributions from Chinese fir (Cunninghamia lanceolata plantations in the southern China, were used. Also, 150 stands were used as fitting data, the other 159 stands were used for testing. Nonlinear regression method (NRM or maximum likelihood estimates method (MLEM were applied to estimate the parameters of models, and the parameter prediction method (PPM and parameter recovery method (PRM were used to predict the diameter distributions of unknown stands. Four main conclusions were obtained: (1 R distribution presented a more accurate simulation than three-parametric Weibull function; (2 the parameters p, q and r of R distribution proved to be its scale, location and shape parameters, and have a deep relationship with stand characteristics, which means the parameters of R distribution have good theoretical interpretation; (3 the ordinate of inflection point of R distribution has significant relativity with its skewness and kurtosis, and the fitted main distribution range for the cumulative diameter distribution of Chinese fir plantations was 0.4∼0.6; (4 the goodness-of-fit test showed diameter distributions of unknown stands can be well estimated by applying R distribution based on PRM or the combination of PPM and PRM under the condition that only quadratic mean DBH or plus stand age are known, and the non-rejection rates were near 80%, which are higher than the 72.33% non-rejection rate of three-parametric Weibull function based on the combination of PPM and PRM.

  16. Evaluation and mapping spatial distribution of bottom sediment heavy metal contamination in Burullus Lake, Egypt

    Directory of Open Access Journals (Sweden)

    Yasser A. El-Amier

    2017-03-01

    Full Text Available Burullus Lake is one of most important lakes in north Delta of Egypt. It is exposed to huge amounts of serious pollutants especially heavy metals. The sediments within the lake aid in the dispersion of these metals. The main objectives of this research were to evaluate and map the spatial distribution of heavy metals in Burullus Lake sediments. Accordingly, 37 locations were randomly distributed within the lake. Sediment samples were taken from these locations. These samples were analyzed for seven metals including Fe, Cu, Zn, Cr, Co, Cd and Pb. Also, five indices were used to identify the status of metal pollutants in the Lake. These indices are: enrichment factor (EF, contamination factor (CF, degree of contamination (DC, pollution load index (PLI and geo-accumulation index (Igeo. Ordinary Kriging was used to interpolate the spatial distribution of the studied elements within the lake. The obtained results indicated that cadmium was the most enriched element in the lake sediments due to industrial and agricultural wastes drained into the lake. The Igeo index revealed that Cd and Pb were the common pollutants in lake sediments. The DC values ranged between low (near El-Boughaz and moderate (near drainage areas. The spatial distribution of pollutants within the lake indicated that the highly polluted areas are located close to the drains, whereas as the less polluted areas were close to El-Boughaz.

  17. Bending analysis of different material distributions of functionally graded beam

    Science.gov (United States)

    Aldousari, S. M.

    2017-04-01

    Most analyses of functional graded materials (FGM) focusing on power law distribution, which presents stress concentration at the interface when material properties change rapidly. The objective of the current paper is to develop two symmetric and anti-symmetric functions and compare their effects on the static deflection and bending stresses with classical power-law distribution. The proposed distributions are a symmetric power-law and a sigmoid function which is anti-symmetric. To homogenized micromechanical properties of FGM, the effective material properties are derived on the basis of Voigt model. Kinematic relation of Euler-Bernoulli beam is assumed and virtual work is proposed to derive the equilibrium equations. A finite element model is proposed to form stiffness matrix and force vector and then solve the problem numerically. Proposed model has been validated. Numerical results presents the effect of power exponent, and elasticity ratios on a static deflection and stresses of FG beams. The most significant finding is that, the symmetric power function is more reliable and can considerably reduce the stress than the other two functions. However, the sigmoid function distribution represents the highest stress.

  18. Dynamic radial distribution function from inelastic neutron scattering

    International Nuclear Information System (INIS)

    McQueeney, R.J.

    1998-01-01

    A real-space, local dynamic structure function g(r,ω) is defined from the dynamic structure function S(Q,ω), which can be measured using inelastic neutron scattering. At any particular frequency ω, S(Q,ω) contains Q-dependent intensity oscillations which reflect the spatial distribution and relative displacement directions for the atoms vibrating at that frequency. Information about local and dynamic atomic correlations is obtained from the Fourier transform of these oscillations g(r,ω) at the particular frequency. g(r,ω) can be formulated such that the elastic and frequency-summed limits correspond to the average and instantaneous radial distribution function, respectively, and is thus called the dynamic radial distribution function. As an example, the dynamic radial distribution function is calculated for fcc nickel in a model which considers only the harmonic atomic displacements due to phonons. The results of these calculations demonstrate that the magnitude of the atomic correlations can be quantified and g(r,ω) is a well-defined correlation function. This leads to a simple prescription for investigating local lattice dynamics. copyright 1998 The American Physical Society

  19. The spatial thickness distribution of metal films produced by large area pulsed laser deposition

    DEFF Research Database (Denmark)

    Pryds, Nini; Schou, Jørgen; Linderoth, Søren

    2007-01-01

    mm diameter positioned 80 turn from the target in vacuum. We have explored the distribution of deposited material on a stationary substrate from a fixed point of impact on the target relative to the substrate. In all cases the angular distribution of the deposited metal layers shows a distinct "flip......Thin films of metals have been deposited in the large-area Pulsed Laser Deposition (PLD) Facility at Riso National Laboratory. Thin films of Ag and Ni were deposited with laser pulses from an excimer laser at 248 nm with a rectangular beam spot at a fluence of 10 J/cm(2) on glass substrates of 127...

  20. Free energy distribution function of a random Ising ferromagnet

    International Nuclear Information System (INIS)

    Dotsenko, Victor; Klumov, Boris

    2012-01-01

    We study the free energy distribution function of a weakly disordered Ising ferromagnet in terms of the D-dimensional random temperature Ginzburg–Landau Hamiltonian. It is shown that besides the usual Gaussian 'body' this distribution function exhibits non-Gaussian tails both in the paramagnetic and in the ferromagnetic phases. Explicit asymptotic expressions for these tails are derived. It is demonstrated that the tails are strongly asymmetric: the left tail (for large negative values of the free energy) is much slower than the right one (for large positive values of the free energy). It is argued that at the critical point the free energy of the random Ising ferromagnet in dimensions D < 4 is described by a non-trivial universal distribution function which is non-self-averaging

  1. Density functional studies of functionalized graphitic materials with late transition metals for oxygen reduction reactions

    DEFF Research Database (Denmark)

    Vallejo, Federico Calle; Martinez, Jose Ignacio; Rossmeisl, Jan

    2011-01-01

    Reaction (OER). Spin analyses suggest that the oxidation state of those elements in the active sites should in general be +2. Moreover, our results verify that the adsorption behavior of transition metals is not intrinsic, since it can be severely altered by changes in the local geometry of the active site......) at the cathode. In this contribution, on the basis of Density Functional Theory (DFT) calculations, we show that graphitic materials with active sites composed of 4 nitrogen atoms and transition metal atoms belonging to groups 7 to 9 in the periodic table are active towards ORR, and also towards Oxygen Evolution...

  2. Particle-size dependence on metal(loid) distributions in mine wastes: Implications for water contamination and human exposure

    Science.gov (United States)

    Kim, C.S.; Wilson, K.M.; Rytuba, J.J.

    2011-01-01

    The mining and processing of metal-bearing ores has resulted in contamination issues where waste materials from abandoned mines remain in piles of untreated and unconsolidated material, posing the potential for waterborne and airborne transport of toxic elements. This study presents a systematic method of particle size separation, mass distribution, and bulk chemical analysis for mine tailings and adjacent background soil samples from the Rand historic mining district, California, in order to assess particle size distribution and related trends in metal(loid) concentration as a function of particle size. Mine tailings produced through stamp milling and leaching processes were found to have both a narrower and finer particle size distribution than background samples, with significant fractions of particles available in a size range (???250 ??m) that could be incidentally ingested. In both tailings and background samples, the majority of trace metal(loid)s display an inverse relationship between concentration and particle size, resulting in higher proportions of As, Cr, Cu, Pb and Zn in finer-sized fractions which are more susceptible to both water- and wind-borne transport as well as ingestion and/or inhalation. Established regulatory screening levels for such elements may, therefore, significantly underestimate potential exposure risk if relying solely on bulk sample concentrations to guide remediation decisions. Correlations in elemental concentration trends (such as between As and Fe) indicate relationships between elements that may be relevant to their chemical speciation. ?? 2011 Elsevier Ltd.

  3. The seasonal influence on the spatial distribution of dissolved selected metals in Lake Naivasha, Kenya

    Science.gov (United States)

    Kamau, Joseph Nyingi; Gachanja, Anthony; Ngila, Catherine; Kazungu, Johnson Michael; Zhai, Mingzhe

    Lake Naivasha is the only freshwater Lake in Rift Valley, in Kenya. It lies in a fertile semi-arid basin. The Lake has no surface water outlet and is presumed to be under stress. Dissolved metals are directly taken up by bacteria, algae, plants, and planktonic and benthic organisms. Dissolved metals can also adsorb to particulate matter in water column and enter aquatic organisms through various routes. Cadmium, copper, lead and zinc may bioaccumulate within lower organisms, yet they do not biomagnify up the food chain as do mercury and selenium. This study reports on the levels and distribution of dissolved heavy metals and investigates the influence of physicochemical parameters on metal mobilization. The bioavailability of selected metals was investigated by relating the levels of dissolved metals to that in fish. Water abstraction for irrigation and domestic use, compounded with organic matter inflow will affect physicochemical parameters and hence influences the mobilization of heavy metals. Dissolved Zn correlated highly with sediment pH (r = 0.67) indicating that dissolution increases with increase in pH. In addition, the fact that the pH also correlated positively with organic matter r = 0.50, Eh r = 0.63, temperature r = 0.56 and dissolved oxygen r = 56, would suggest that organic bound Zn contributed significantly to the concentration of dissolved Zn. In situ flux experiments indicated that the fringing papyrus reeds located along the shores of Lake Naivasha provided sites for metal immobilization due to their coprecipitation on redox sensitive.

  4. Angular distribution of atoms ejected by laser ablation of different metals

    International Nuclear Information System (INIS)

    Konomi, I.; Motohiro, T.; Asaoka, T.

    2009-01-01

    Angular distributions of 13 different metals ejected by laser ablation using fourth harmonics (wavelength=266 nm) of neodymium doped yttrium aluminum garnet laser and a fluence close to near-threshold value (2.3 J/cm 2 ) have been investigated with a high angular resolution. The angular distribution which is characterized by the exponent n of cos n θ distribution showed very broad range of values between 3 and 24 for different metals. A simple relation that the exponent n is proportional to the square root of particle atomic weight as reported previously has not been observed. Instead, a general trend has been found that the metals with higher sublimation energy such as Ta and Zr show narrower angular distribution than those with lower sublimation energy such as Sn and In. While the sublimation energy of metals has a great influence on the angular distribution of ejected atoms, a simple consideration suggests that their thermal conductivity and specific heat have little effect on it.

  5. Distribution functions and moments in the theory of coagulation

    International Nuclear Information System (INIS)

    Pich, J.

    1990-04-01

    Different distribution functions and their moments used in the Theory of coagulation are summarized and analysed. Relations between the moments of these distribution functions are derived and the physical meaning of individual moments is briefly discussed. The time evolution of the moment of order zero (total number concentration) during the coagulation process is analysed for the general kernel of the Smoluchowski equation. On this basis the time evolution of certain physically important quantities related to this moment such as mean particle size, surface and volume as well as surface concentration is described. Equations for the half time of coagulation for the general collision frequency factor are derived. (orig.) [de

  6. Effect of Jig Design and Assessment of Stress Distribution in Testing Metal-Ceramic Adhesion.

    Science.gov (United States)

    Özcan, Mutlu; Kojima, Alberto Noriyuki; Nishioka, Renato Sussumu; Mesquita, Alfredo Mikail Melo; Bottino, Marco Antonio; Filho, Gilberto Duarte

    2016-12-01

    In testing adhesion using shear bond test, a combination of shear and tensile forces occur at the interface, resulting in complex stresses. The jig designs used for this kind of test show variations in published studies, complicating direct comparison between studies. This study evaluated the effect of different jig designs on metal-ceramic bond strength and assessed the stress distribution at the interface using finite element analysis (FEA). Metal-ceramic (Metal: Ni-Cr, Wiron 99, Bego; Ceramic: Vita Omega 900, Vita) specimens (N = 36) (diameter: 4 mm, veneer thickness: 4 mm; base diameter: 5 mm, thickness: 1 mm) were fabricated and randomly divided into three groups (n = 12 per group) to be tested using one of the following jig designs: (a) chisel (CH) (ISO 11405), (b) steel strip (SS), (c) piston (PI). Metal-ceramic interfaces were loaded under shear until debonding in a universal testing machine (0.5 mm/min). Failure types were evaluated using scanning electron microscopy (SEM). FEA was used to study the stress distribution using different jigs. Metal-ceramic bond strength data (MPa) were analyzed using ANOVA and Tukey's tests (α = 0.05). The jig type significantly affected the bond results (p = 0.0001). PI type of jig presented the highest results (MPa) (p Metal-ceramic bond strength was affected by the jig design. Accordingly, the results of in vitro studies on metal-ceramic adhesion should be evaluated with caution. When adhesion of ceramic materials to metals is evaluated in in vitro studies, it should be noted that the loading jig type affects the results. Clinical observations should report on the location and type of ceramic fractures in metal-ceramic reconstructions so that the most relevant test method can be identified. © 2015 by the American College of Prosthodontists.

  7. Distribution and health risk assessment to heavy metals near smelting and mining areas of Hezhang, China.

    Science.gov (United States)

    Briki, Meryem; Zhu, Yi; Gao, Yang; Shao, Mengmeng; Ding, Huaijian; Ji, Hongbing

    2017-08-19

    Mining and smelting areas in Hezhang have generated a large amount of heavy metals into the environment. For that cause, an evaluative study on human exposure to heavy metals including Co, Ni, Cu, Zn, Cr, As, Cd, Pb, Sb, Bi, Be, and Hg in hair and urine was conducted for their concentrations and correlations. Daily exposure and non-carcinogenic and carcinogenic risk were estimated. Sixty-eight scalp hair and 66 urine samples were taken from participants of different ages (6-17, 18-40, 41-60, and ≥ 65 years) living in the vicinity of an agricultural soil near mine and smelting areas. The results compared to the earlier studies showed an elevated concentration of Pb, Be, Bi, Co, Cr, Ni, Sb, and Zn in hair and urine. These heavy metals were more elevated in mining than in smelting. Considering gender differences, females were likely to be more affected than male. By investigating age differences in this area, high heavy metal concentrations in male's hair and urine existed in age of 18-40 and ≥ 66, respectively. However, females did not present homogeneous age distribution. Hair and urine showed a different distribution of heavy metals in different age and gender. In some cases, significant correlation was found between heavy metals in hair and urine (P > 0.05 and P > 0.01) in mining area. The estimated average daily intake of heavy metals in vegetables showed a great contribution compared to the soil and water. Non-carcinogenic and carcinogenic risk values of total pathways in mining and smelting areas were higher than 1 and exceeded the acceptable levels. Thus, the obtained data might be useful for further studies. They can serve as a basis of comparison and assessing the effect of simultaneous exposure from heavy metals in mining and smelting areas, and potential health risks from exposure to heavy metals in vegetables need more consideration.

  8. A comprehensive study of metal distribution in three main classes of seaweed

    International Nuclear Information System (INIS)

    Ryan, Siobhan; McLoughlin, Peter; O'Donovan, Orla

    2012-01-01

    This paper provides one of the most comprehensive studies of metal distributions in three main macroalgae species. In this novel study, levels of total, intracellular and surface bound Pb, Zn, As, Cd, Co, Cr, Cu, Mn and Ni associated with Polysiphonia lanosa (L) Tandy, Ascophyllum nodosum (L) Le Jolis, Fucus vesiculosus (L) and Ulva sp. were determined. Additionally, water and sediment metal levels were analysed to gain an insight into the relative uptake efficiencies of different macroalgal species. Samples were collected from a clean site in Fethard-on-Sea, Wexford, Ireland (52°11′53.68′N, 6°49′34.64′W), in May 2008. Results demonstrated that total, intracellular and surface bound metal levels varied according to metal and seaweed species, with the highest proportion of metals found to be intracellular. Inhibition of Mn uptake by Zn was indicated for P. lanosa. Furthermore, P. lanosa had enhanced bioaccumulation ability, with the highest Concentration Factor reported of any seaweed to date. - Highlights: ► Three main classes of seaweed were collected from the South-East coast of Ireland. ► Metal levels (total, intracellular and surface-bound) in four seaweed species were determined. ► Metal levels of seawater and sediment samples collected from the same location were quantified. ► The Concentration Factors for P. lanosa, A. nodosum, F. vesiculosus and Ulva sp., were calculated. ► Interspecies variations in seaweed metal concentrations were demonstrated. - This study, reports the most comprehensive uptake efficiencies and distributions of metals in four main seaweed sps., with P. lanosa demonstrating excellent bioaccumulation ability.

  9. Function allocation in distributed safeguards and security systems

    International Nuclear Information System (INIS)

    Barlich, G.L.

    1991-01-01

    Computerized distributed systems are being used to collect and manage data for activities such as nuclear materials accounting, process control, laboratory coordination, and security. Poor choices made in allocating functions to individual processors can make a system unusable by burdening machines with excessive network retrievals and updates. During system design phases, data allocation algorithms based on operation frequencies, field sizes, security information, and reliability requirements can be applied in sensitivity studies to mathematically ensure processor efficiency. The Los Alamos Network Design System (NDS) implements such an allocation algorithm. The authors analyzed a large, existing distributed system to test the cost functions and to compare actual network problems with NDS results. Several common configurations were also designed and studied using the software. From these studies, some basic principles for allocating functions emerged. In this paper recommendations for function allocation in generic systems and related design options are discussed

  10. Distribution of Heavy Metals in the Different Parts of Cerithidea Obtusa and the Relationships between Metal Distribution and Allometric Parameters of the Snail

    Directory of Open Access Journals (Sweden)

    Chee Kong YAP

    2010-07-01

    Full Text Available The intertidal gastropod, Cerithidea obtusa were obtained from Bako and Sematan (Sarawak and Deralik (Perak. Besides the shell, the snails were dissected into five different soft tissues. The soft tissues and the shell were then analysed for heavy metals. It was found that the highest concentrations of Cu (112 - 178 μg/g dw and Zn (117 - 161 μg/g dw were found in the tentacle; the highest concentrations of Cd (4.41 - 5.37 μg/g dw, Pb (53.2 - 63.8 μg/g dw and Ni (26.1 - 27.9 μg/g dw were found in the shell. On the other hand, the highest Fe concentrations (910 - 2921 μg/g dw were found in the operculum. The Spearman's correlation coefficient and multiple stepwise linear regression also revealed that the allometric parameters can influence the distribution of heavy metals in some of the different parts. From the present findings indicated that the heavy metals accumulated by the C. obtusa from the environment might affect its physical growth, which was shown by the negative correlations found between the metals in the different parts with the allometric parameters.

  11. Removal of a hazardous heavy metal from aqueous solution using functionalized graphene and boron nitride nanosheets: Insights from simulations.

    Science.gov (United States)

    Azamat, Jafar; Sattary, Batoul Shirforush; Khataee, Alireza; Joo, Sang Woo

    2015-09-01

    A computer simulation was performed to investigate the removal of Zn(2+) as a heavy metal from aqueous solution using the functionalized pore of a graphene nanosheet and boron nitride nanosheet (BNNS). The simulated systems were comprised of a graphene nanosheet or BNNS with a functionalized pore containing an aqueous ionic solution of zinc chloride. In order to remove heavy metal from an aqueous solution using the functionalized pore of a graphene nanosheet and BNNS, an external voltage was applied along the z-axis of the simulated box. For the selective removal of zinc ions, the pores of graphene and BNNS were functionalized by passivating each atom at the pore edge with appropriate atoms. For complete analysis systems, we calculated the potential of the mean force of ions, the radial distribution function of ion-water, the residence time of ions, the hydrogen bond, and the autocorrelation function of the hydrogen bond. Copyright © 2015 Elsevier Inc. All rights reserved.

  12. Progress on Bayesian Inference of the Fast Ion Distribution Function

    DEFF Research Database (Denmark)

    Stagner, L.; Heidbrink, W.W,; Chen, X.

    2013-01-01

    . However, when theory and experiment disagree (for one or more diagnostics), it is unclear how to proceed. Bayesian statistics provides a framework to infer the DF, quantify errors, and reconcile discrepant diagnostic measurements. Diagnostic errors and weight functions that describe the phase space...... sensitivity of the measurements are incorporated into Bayesian likelihood probabilities. Prior probabilities describe physical constraints. This poster will show reconstructions of classically described, low-power, MHD-quiescent distribution functions from actual FIDA measurements. A description of the full...

  13. Tissue distribution patterns of solubilized metals from internalized tungsten alloy in the F344 rat

    Directory of Open Access Journals (Sweden)

    Vernieda B. Vergara

    2016-06-01

    Full Text Available Because of its unique physical and chemical properties, tungsten has been increasingly utilized in a variety of civilian and military applications. This expanded use also raises the risk of human exposure through internalization by various routes. In most cases the toxicological and carcinogenic properties of these tungsten-based compounds are not known nor are the dissolution biokinetics and ultimate fate of the associated metals. Using a laboratory rodent model system designed to assess the health effects of embedded metals, and a tungsten alloy comprised of tungsten (91.1%, nickel (6.0%, and cobalt (2.9%, we investigated the tissue distribution patterns of the metals over a six month period. Despite its perceived insolubility, tungsten rapidly solubilized from the implanted metal fragments, as did nickel and cobalt. All three metals distributed systemically over time with extremely elevated levels of all three metals found in kidney, liver, and spleen. Unexpectedly, tungsten was found to cross the blood-brain and blood-testis barriers and localize in those tissues. These results, along with recent reports suggesting that tungsten is a tumor promoter, raises serious concerns as to the long-term health effects of exposure to tungsten and tungsten-based compounds.

  14. Ion activity and distribution of heavy metals in acid mine drainage polluted subtropical soils

    International Nuclear Information System (INIS)

    Li Yongtao; Becquer, Thierry; Dai Jun; Quantin, Cecile; Benedetti, Marc F.

    2009-01-01

    The oxidative dissolution of mine wastes gives rise to acidic, metal-enriched mine drainage (AMD) and has typically posed an additional risk to the environment. The poly-metallic mine Dabaoshan in South China is an excellent test site to understand the processes affecting the surrounding polluted agricultural fields. Our objectives were firstly to investigate metal ion activity in soil solution, distribution in solid constituents, and spatial distribution in samples, secondly to determine dominant environment factors controlling metal activity in the long-term AMD-polluted subtropical soils. Soil Column Donnan Membrane Technology (SC-DMT) combined with sequential extraction shows that unusually large proportion of the metal ions are present as free ion in the soil solutions. The narrow range of low pH values prevents any pH effects during the binding onto oxides or organic matter. The differences in speciation of the soil solutions may explain the different soil degradation observed between paddy and non-paddy soils. - First evidence of the real free metal ion concentrations in acid mine drainage context in tropical systems

  15. Distribution of platinum and other traffic related metals in sediments and clams (Corbicula sp.).

    Science.gov (United States)

    Ruchter, Nadine; Sures, Bernd

    2015-03-01

    Platinum is part of traffic-emitted metals since the introduction of automotive catalyst converters. Still, automobile emissions are one of the major sources for metals in European river systems. However, field data on Pt is scarce and there is a lack of knowledge concerning the distribution and biological availability of Pt. Therefore, the distribution of traffic related metals (Cd, Cr, Cu, Ni, Pb, Pt, and Zn) was analyzed in sediment samples and in the Asian clam Corbicula sp. Samples were taken from three transects following road runoff inlets. Pt was introduced into the river by road runoff. The highest Pt concentrations in sediments were analyzed in the silt/clay fraction (45 ng/g), while the highest total Pt burden was obtained for the sand fraction, that makes up more than 60% of the sediment. Metal concentrations were related to the area of the drained street section as well as to their distance from the discharge point, and to grain size distribution within the sediment. Pt and other traffic related metals were accumulated by clams. Due to the feeding behavior of the freshwater mussel Corbicula sp. Pt concentrations in the soft tissue remain relatively low (max Pt concentration: 1.3 ng/g freeze dried soft tissue) and acute lethal or toxic effects therefore appear to be unlikely. Nonetheless, chronic exposure effects still have to be examined. Copyright © 2014 Elsevier Ltd. All rights reserved.

  16. Plasmon Modulation Spectroscopy of Noble Metals to Reveal the Distribution of the Fermi Surface Electrons in the Conduction Band

    Directory of Open Access Journals (Sweden)

    Kentaro Takagi

    2017-12-01

    Full Text Available To directly access the dynamics of electron distribution near the Fermi-surface after plasmon excitation, pump-probe spectroscopy was performed by pumping plasmons on noble-metal films and probing the interband transition. Spectral change in the interband transitions is sensitive to the electron distribution near the Fermi-surface, because it involves the d valence-band to the conduction band transitions and should reflect the k-space distribution dynamics of electrons. For the continuous-wave pump and probe experiment, the plasmon modulation spectra are found to differ from both the current modulation and temperature difference spectra, possibly reflecting signatures of the plasmon wave function. For the femtosecond-pulse pump and probe experiment, the transient spectra agree well with the known spectra upon the excitation of the respective electrons resulting from plasmon relaxation, probably because the lifetime of plasmons is shorter than the pulse duration.

  17. Fourier transform distribution function of relaxation times; application and limitations

    NARCIS (Netherlands)

    Boukamp, Bernard A.

    2015-01-01

    A simple Fourier transform (FT) method is presented for obtaining a Distribution Function of Relaxation Times (DFRT) for electrochemical impedance spectroscopy (EIS) data. By using a special data extension procedure the FT is performed over the range from -∞ ≤ lnω ≤ + ∞. The integration procedure is

  18. Electron-cyclotron-resonant-heated electron distribution functions

    International Nuclear Information System (INIS)

    Matsuda, Y.; Nevins, W.M.; Cohen, R.H.

    1981-01-01

    Recent studies at Lawrence Livermore National Laboratory (LLNL) with a bounce-averaged Fokker-Planck code indicate that the energetic electron tail formed by electron-cyclotron resonant heating (ECRH) at the second harmonic is not Maxwellian. We present the results of our bounce-averaged Fokker-Planck code along with some simple analytic models of hot-electron distribution functions

  19. Wave mode identification via wave distribution function analysis

    Czech Academy of Sciences Publication Activity Database

    Oscarsson, T.; Sternberg, G.; Santolík, Ondřej

    2001-01-01

    Roč. 26, 6, Part C (2001), s. 229-235 ISSN 1464-1917 R&D Projects: GA ČR GA205/99/1712 Institutional research plan: CEZ:AV0Z3042911 Keywords : auroral magnetosphere * wave propagation * wave distribution function Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 0.399, year: 2001

  20. Score Function of Distribution and Revival of the Moment Method

    Czech Academy of Sciences Publication Activity Database

    Fabián, Zdeněk

    2016-01-01

    Roč. 45, č. 4 (2016), s. 1118-1136 ISSN 0361-0926 R&D Projects: GA MŠk(CZ) LG12020 Institutional support: RVO:67985807 Keywords : characteristics of distributions * data characteristics * general moment method * Huber moment estimator * parametric methods * score function Subject RIV: BB - Applied Statistics, Operational Research Impact factor: 0.311, year: 2016

  1. Three-dimensional coupled double-distribution-function lattice ...

    Indian Academy of Sciences (India)

    Ruo-Fan Qiu

    2017-11-14

    Nov 14, 2017 ... Lattice Boltzmann method; compressible flows; double distribution function; finite difference. PACS Nos 47.11.–j; 51.10.+y; 05.20.Dd. 1. Introduction. The lattice Boltzmann method (LBM) [1–3] has become a prominent tool in computational fluid dynamic (CFD). Unlike the conventional numerical methods, ...

  2. Three-dimensional coupled double-distribution-function lattice ...

    Indian Academy of Sciences (India)

    dimensional coupled double-distribution-function lattice Boltzmann models for compressible Navier–Stokes equations. RUO-FAN QIU YAN-CHENG YOU CHENG-XIANG ZHU RONG-QIAN CHEN JIAN-FENG ZHU. Research Article Volume 89 Issue ...

  3. Family Functions' Distribution in Men and Women Concepts

    Science.gov (United States)

    Kasimova, Ramilya Sh.; Biktagirova, Gulnara F.

    2016-01-01

    Creating a happy family with a favorable psychological climate is important both for the individual and the society as a whole. One of the factors, that influence the creation of a welfare family, is the content of the spouses' concepts of the family, its functions and their possible distribution. The main purpose of this article is to identify…

  4. Limb distribution, motor impairment, and functional classification of cerebral palsy

    NARCIS (Netherlands)

    Gorter, J.A.; Rosenbaum, P.L.

    2004-01-01

    This study explored the relationships between the Gross Motor Function Classification System (GMFCS), limb distribution, and type of motor impairment. Data used were collected in the Ontario Motor Growth study, a longitudinal cohort study with a population-based sample of children with cerebral

  5. A new setup to measure bidirectional reflectance distribution functions

    NARCIS (Netherlands)

    Roosjen, P.P.J.; Clevers, J.G.P.W.; Bartholomeus, H.

    2012-01-01

    The Plant Facility, a new laboratory goniometer system, built by the Wageningen University has been tested in order to take bidirectional reflectance distribution function (BRDF) measurements. An ASD FieldSpec 3 spectroradiometer mounted on an industrial robot arm is able to measure small targets

  6. Parton distribution functions in the context of parton showers

    International Nuclear Information System (INIS)

    Nagy, Zoltán; Soper, Davison E.

    2014-01-01

    When the initial state evolution of a parton shower is organized according to the standard “backward evolution” prescription, ratios of parton distribution functions appear in the splitting probabilities. The shower thus organized evolves from a hard scale to a soft cutoff scale. At the end of the shower, one expects that only the parton distributions at the soft scale should affect the results. The other effects of the parton distributions should have cancelled. This means that the kernels for parton evolution should be related to the shower splitting functions. If the initial state partons can have non-zero masses, this requires that the evolution kernels cannot be the usual (MS)-bar kernels. We work out what the parton evolution kernels should be to match the shower evolution contained in the parton shower event generator DEDUCTOR, in which the b and c quarks have non-zero masses.

  7. Analysis of the distribution of heavy metals in the soils of Bagega ...

    African Journals Online (AJOL)

    Uncontrolled exploitation and degradation in the environment over the past few decades as the result of urbanization and poverty has caused a serious damage to lives and properties. The study analysed the spatial distribution of heavy metal (Fe, Cu and Zn) in Bagega, Zamfara state. Three mapping units were identified ...

  8. Metallicity and the spectral energy distribution and spectral types of dwarf O-stars

    NARCIS (Netherlands)

    Mokiem, M.R.; Martín-Hernández, N.L.; Lenorzer, A.; de Koter, A.; Tielens, A.G.G.M.

    2004-01-01

    We present a systematic study of the effect of metallicity on the stellar spectral energy distribution (SED) of O main sequence (dwarf) stars, focussing on the hydrogen and helium ionizing continua, and on the optical and near-IR lines used for spectral classification. The spectra are based on

  9. High resolution millimeter wave digitally controlled oscillator with reconfigurable distributed metal capacitor passive resonators

    NARCIS (Netherlands)

    Wu, W.; Long, J.R.; Staszewski, B.

    2014-01-01

    A novel and useful millimeter-wave digitally controlled oscillator (DCO) that achieve a tuning range greater than 10% and fine frequency resolution less than 1 MHz. Switched metal capacitors are distributed across a passive resonator for tuning the oscillation frequency. To obtain sub-MHz frequency

  10. Urbanization effects on sediment and trace metals distribution in an urban winter pond (Netanya, Israel)

    NARCIS (Netherlands)

    Zohar, I.; Teutsch, N.; Levin, N.; Mackin, G.; de Stigter, H.; Bookman, R.

    2017-01-01

    PurposeThis paper aims to elucidate urban development-induced processes affecting the sediment and the distribution of contaminating metals in a seasonal pond located in the highly populated Israeli Coastal Plain. The paper demonstrates how an integrated approach, including geochemical,

  11. Distribution of uranium and some selected trace metals in human scalp hair from Balkans

    International Nuclear Information System (INIS)

    Zunic, Z. S.; Tokonami, S.; Mishra, S.; Arae, H.; Kritsananuwat, R.; Sahoo, S. K.

    2012-01-01

    The possible consequences of the use of depleted uranium (DU) used in Balkan conflicts in 1995 and 1999 for the people and the environment of this reason need attention. The heavy metal content in human hair may serve as a good indicator of dietary, environmental and occupational exposures to the metal compounds. The present work summarises the distribution of uranium and some selected trace metals such as Mn, Ni, Cu, Zn, Sr, Cd and Cs in the scalp hair of inhabitants from Balkans exposed to DU directly and indirectly, i.e. Han Pijesak, Bratoselce and Gornja Stubla areas. Except U and Cs, all other metals were compared with the worldwide reported values of occupationally unexposed persons. Uranium concentrations show a wide variation ranging from 0.9±0.05 to 449±12 mg kg -1 . Although hair samples were collected from Balkan conflict zones, uranium isotopic measurement ( 235 U/ 238 U) shows a natural origin rather than DU. (authors)

  12. Distribution of uranium and some selected trace metals in human scalp hair from Balkans.

    Science.gov (United States)

    Zunic, Z S; Tokonami, S; Mishra, S; Arae, H; Kritsananuwat, R; Sahoo, S K

    2012-11-01

    The possible consequences of the use of depleted uranium (DU) used in Balkan conflicts in 1995 and 1999 for the people and the environment of this reason need attention. The heavy metal content in human hair may serve as a good indicator of dietary, environmental and occupational exposures to the metal compounds. The present work summarises the distribution of uranium and some selected trace metals such as Mn, Ni, Cu, Zn, Sr, Cd and Cs in the scalp hair of inhabitants from Balkans exposed to DU directly and indirectly, i.e. Han Pijesak, Bratoselce and Gornja Stubla areas. Except U and Cs, all other metals were compared with the worldwide reported values of occupationally unexposed persons. Uranium concentrations show a wide variation ranging from 0.9 ± 0.05 to 449 ± 12 µg kg(-1). Although hair samples were collected from Balkan conflict zones, uranium isotopic measurement ((235)U/(238)U) shows a natural origin rather than DU.

  13. Finite frequency Seebeck coefficient of metals: A memory function approach

    Science.gov (United States)

    Bhalla, Pankaj; Kumar, Pradeep; Das, Nabyendu; Singh, Navinder

    2017-10-01

    We study the dynamical thermoelectric transport in metals subjected to the electron-impurity and the electron-phonon interactions using the memory function formalism. We introduce a generalized Drude form for the Seebeck coefficient in terms of thermoelectric memory function and calculate the latter in various temperature and frequency limits. In the zero frequency and high temperature limit, we find that our results are consistent with the experimental findings and with the traditional Boltzmann equation approach. In the low temperature limit, we find that the Seebeck coefficient is quadratic in temperature. In the finite frequency regime, we report new results: In the electron-phonon interaction case, we find that the Seebeck coefficient shows frequency independent behavior both in the high frequency regime (ω ≫ωD , where ωD is the Debye frequency) and in the low frequency regime (ω ≪ωD), whereas in the intermediate frequencies, it is a monotonically increasing function of frequency. In the case of the electron-impurity interaction, first it decays and then after passing through a minimum it increases with the increase in frequency and saturates at high frequencies.

  14. Effect of sonication on particle dispersion, administered dose and metal release of non-functionalized, non-inert metal nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Pradhan, Sulena; Hedberg, Jonas, E-mail: jhed@kth.se; Blomberg, Eva [KTH Royal Institute of Technology, Division of Surface and Corrosion Science, Department of Chemistry (Sweden); Wold, Susanna [KTH Royal Institute of Technology, Division of Applied Physical Chemistry, Department of Chemistry (Sweden); Odnevall Wallinder, Inger [KTH Royal Institute of Technology, Division of Surface and Corrosion Science, Department of Chemistry (Sweden)

    2016-09-15

    In this study, we elucidate the effect of different sonication techniques to efficiently prepare particle dispersions from selected non-functionalized NPs (Cu, Al, Mn, ZnO), and corresponding consequences on the particle dose, surface charge and release of metals. Probe sonication was shown to be the preferred method for dispersing non-inert, non-functionalized metal NPs (Cu, Mn, Al). However, rapid sedimentation during sonication resulted in differences between the real and the administered doses in the order of 30–80 % when sonicating in 1 and 2.56 g/L NP stock solutions. After sonication, extensive agglomeration of the metal NPs resulted in rapid sedimentation of all particles. DLVO calculations supported these findings, showing the strong van der Waals forces of the metal NPs to result in significant NP agglomeration. Metal release from the metal NPs was slightly increased by increased sonication. The addition of a stabilizing agent (bovine serum albumin) had an accelerating effect on the release of metals in sonicated solutions. For Cu and Mn NPs, the extent of particle dissolution increased from <1.6 to ~5 % after sonication for 15 min. A prolonged sonication time (3–15 min) had negligible effects on the zeta potential of the studied NPs. In all, it is shown that it is of utmost importance to carefully investigate how sonication influences the physico-chemical properties of dispersed metal NPs. This should be considered in nanotoxicology investigations of metal NPs.Graphical Abstract.

  15. Sources, distribution, bioavailability, toxicity, and risk assessment of heavy metal(loid)s in complementary medicines.

    Science.gov (United States)

    Bolan, Shiv; Kunhikrishnan, Anitha; Seshadri, Balaji; Choppala, Girish; Naidu, Ravi; Bolan, Nanthi S; Ok, Yong Sik; Zhang, Ming; Li, Chun-Guang; Li, Feng; Noller, Barry; Kirkham, Mary Beth

    2017-11-01

    The last few decades have seen the rise of alternative medical approaches including the use of herbal supplements, natural products, and traditional medicines, which are collectively known as 'Complementary medicines'. However, there are increasing concerns on the safety and health benefits of these medicines. One of the main hazards with the use of complementary medicines is the presence of heavy metal(loid)s such as arsenic (As), cadmium (Cd), lead (Pb), and mercury (Hg). This review deals with the characteristics of complementary medicines in terms of heavy metal(loid)s sources, distribution, bioavailability, toxicity, and human risk assessment. The heavy metal(loid)s in these medicines are derived from uptake by medicinal plants, cross-contamination during processing, and therapeutic input of metal(loid)s. This paper discusses the distribution of heavy metal(loid)s in these medicines, in terms of their nature, concentration, and speciation. The importance of determining bioavailability towards human health risk assessment was emphasized by the need to estimate daily intake of heavy metal(loid)s in complementary medicines. The review ends with selected case studies of heavy metal(loid) toxicity from complementary medicines with specific reference to As, Cd, Pb, and Hg. The future research opportunities mentioned in the conclusion of review will help researchers to explore new avenues, methodologies, and approaches to the issue of heavy metal(loid)s in complementary medicines, thereby generating new regulations and proposing fresh approach towards safe use of these medicines. Copyright © 2017 Elsevier Ltd. All rights reserved.

  16. Pollution distribution of heavy metals in surface soil at an informal electronic-waste recycling site.

    Science.gov (United States)

    Fujimori, Takashi; Takigami, Hidetaka

    2014-02-01

    We studied distribution of heavy metals [lead (Pb), copper (Cu) and zinc (Zn)] in surface soil at an electronic-waste (e-waste) recycling workshop near Metro Manila in the Philippines to evaluate the pollution size (spot size, small area or the entire workshop), as well as to assess heavy metal transport into the surrounding soil environment. On-site length-of-stride-scale (~70 cm) measurements were performed at each surface soil point using field-portable X-ray fluorescence (FP-XRF). The surface soil at the e-waste recycling workshop was polluted with Cu, Zn and Pb, which were distributed discretely in surface soil. The site was divided into five areas based on the distance from an entrance gate (y-axis) of the e-waste recycling workshop. The three heavy metals showed similar concentration gradients in the y-axis direction. Zn, Pb and Cu concentrations were estimated to decrease to half of their maximum concentrations at ~3, 7 and 7 m from the pollution spot, respectively, inside the informal e-waste recycling workshop. Distance from an entrance may play an important role in heavy metal transport at the soil surface. Using on-site FP-XRF, we evaluated the metal ratio to characterise pollution features of the solid surface. Variability analysis of heavy metals revealed vanishing surficial autocorrelation over metre ranges. Also, the possibility of concentration prediction at unmeasured points using geostatistical kriging was evaluated, and heavy metals had a relative "small" pollution scales and remained inside the original workshop compared with toxic organohalogen compounds. Thus, exposure to heavy metals may directly influence the health of e-waste workers at the original site rather than the surrounding habitat and environmental media.

  17. [Effects of Tillage on Distribution of Heavy Metals and Organic Matter Within Purple Paddy Soil Aggregates].

    Science.gov (United States)

    Shi, Qiong-bin; Zhao, Xiu-lan; Chang, Tong-ju; Lu, Ji-wen

    2016-05-15

    A long-term experiment was utilized to study the effects of tillage methods on the contents and distribution characteristics of organic matter and heavy metals (Cu, Zn, Pb, Cd, Fe and Mn) in aggregates with different sizes (including 1-2, 0.25-1, 0.05-0.25 mm and soil under two tillage methods including flooded paddy field (FPF) and paddy-upland rotation (PR). The relationship between heavy metals and organic matter in soil aggregates was also analyzed. The results showed that the aggregates of two tillage methods were dominated by 0.05-0.25 mm and organic matter in each aggregate decreased with the decrease of aggregate sizes, however, compared to PR, FPF could significantly increase the contents of organic matter in soils and aggregates. The tillage methods did not significantly affect the contents of heavy metals in soils, but FPF could enhance the accumulation and distribution of aggregate, organic matter and heavy metals in aggregates with diameters of 1-2 mm and 0.25-1 mm. Correlation analysis found that there was a negative correlation between the contents of heavy metals and organic matter in soil aggregates, but a positive correlation between the amounts of heavy metal and organic matter accumulated in soil aggregates. From the slope of the correlation analysis equations, we could found that the sensitivities of heavy metals to the changes of soil organic matters followed the order of Mn > Zn > Pb > Cu > Fe > Cd under the same tillage. When it came to the same heavy metal, it was more sensitive in PR than in FPF.

  18. Thermocouple and infrared sensor-based measurement of temperature distribution in metal cutting.

    Science.gov (United States)

    Kus, Abdil; Isik, Yahya; Cakir, M Cemal; Coşkun, Salih; Özdemir, Kadir

    2015-01-12

    In metal cutting, the magnitude of the temperature at the tool-chip interface is a function of the cutting parameters. This temperature directly affects production; therefore, increased research on the role of cutting temperatures can lead to improved machining operations. In this study, tool temperature was estimated by simultaneous temperature measurement employing both a K-type thermocouple and an infrared radiation (IR) pyrometer to measure the tool-chip interface temperature. Due to the complexity of the machining processes, the integration of different measuring techniques was necessary in order to obtain consistent temperature data. The thermal analysis results were compared via the ANSYS finite element method. Experiments were carried out in dry machining using workpiece material of AISI 4140 alloy steel that was heat treated by an induction process to a hardness of 50 HRC. A PVD TiAlN-TiN-coated WNVG 080404-IC907 carbide insert was used during the turning process. The results showed that with increasing cutting speed, feed rate and depth of cut, the tool temperature increased; the cutting speed was found to be the most effective parameter in assessing the temperature rise. The heat distribution of the cutting tool, tool-chip interface and workpiece provided effective and useful data for the optimization of selected cutting parameters during orthogonal machining.

  19. Thermocouple and Infrared Sensor-Based Measurement of Temperature Distribution in Metal Cutting

    Directory of Open Access Journals (Sweden)

    Abdil Kus

    2015-01-01

    Full Text Available In metal cutting, the magnitude of the temperature at the tool-chip interface is a function of the cutting parameters. This temperature directly affects production; therefore, increased research on the role of cutting temperatures can lead to improved machining operations. In this study, tool temperature was estimated by simultaneous temperature measurement employing both a K-type thermocouple and an infrared radiation (IR pyrometer to measure the tool-chip interface temperature. Due to the complexity of the machining processes, the integration of different measuring techniques was necessary in order to obtain consistent temperature data. The thermal analysis results were compared via the ANSYS finite element method. Experiments were carried out in dry machining using workpiece material of AISI 4140 alloy steel that was heat treated by an induction process to a hardness of 50 HRC. A PVD TiAlN-TiN-coated WNVG 080404-IC907 carbide insert was used during the turning process. The results showed that with increasing cutting speed, feed rate and depth of cut, the tool temperature increased; the cutting speed was found to be the most effective parameter in assessing the temperature rise. The heat distribution of the cutting tool, tool-chip interface and workpiece provided effective and useful data for the optimization of selected cutting parameters during orthogonal machining.

  20. Thermocouple and Infrared Sensor-Based Measurement of Temperature Distribution in Metal Cutting

    Science.gov (United States)

    Kus, Abdil; Isik, Yahya; Cakir, M. Cemal; Coşkun, Salih; Özdemir, Kadir

    2015-01-01

    In metal cutting, the magnitude of the temperature at the tool-chip interface is a function of the cutting parameters. This temperature directly affects production; therefore, increased research on the role of cutting temperatures can lead to improved machining operations. In this study, tool temperature was estimated by simultaneous temperature measurement employing both a K-type thermocouple and an infrared radiation (IR) pyrometer to measure the tool-chip interface temperature. Due to the complexity of the machining processes, the integration of different measuring techniques was necessary in order to obtain consistent temperature data. The thermal analysis results were compared via the ANSYS finite element method. Experiments were carried out in dry machining using workpiece material of AISI 4140 alloy steel that was heat treated by an induction process to a hardness of 50 HRC. A PVD TiAlN-TiN-coated WNVG 080404-IC907 carbide insert was used during the turning process. The results showed that with increasing cutting speed, feed rate and depth of cut, the tool temperature increased; the cutting speed was found to be the most effective parameter in assessing the temperature rise. The heat distribution of the cutting tool, tool-chip interface and workpiece provided effective and useful data for the optimization of selected cutting parameters during orthogonal machining. PMID:25587976

  1. Density functional study of ferromagnetism in alkali metal thin films

    Indian Academy of Sciences (India)

    thickness uniform jellium model (UJM), and it is argued that within LSDA or GGA, alkali metal thin films cannot be claimed to have an FM ground state. Relevance of these results to the experiments on transition metal-doped alkali metal thin films ...

  2. Recursive confidence band construction for an unknown distribution function.

    Science.gov (United States)

    Kiatsupaibul, Seksan; Hayter, Anthony J

    2015-01-01

    Given a sample X1,...,Xn of independent observations from an unknown continuous distribution function F, the problem of constructing a confidence band for F is considered, which is a fundamental problem in statistical inference. This confidence band provides simultaneous inferences on all quantiles and also on all of the cumulative probabilities of the distribution, and so they are among the most important inference procedures that address the issue of multiplicity. A fully nonparametric approach is taken where no assumptions are made about the distribution function F. Historical approaches to this problem, such as Kolmogorov's famous () procedure, represent some of the earliest inference methodologies that address the issue of multiplicity. This is because a confidence band at a given confidence level 1-α allows inferences on all of the quantiles of the distribution, and also on all of the cumulative probabilities, at that specified confidence level. In this paper it is shown how recursive methodologies can be employed to construct both one-sided and two-sided confidence bands of various types. The first approach operates by putting bounds on the cumulative probabilities at the data points, and a recursive integration approach is described. The second approach operates by providing bounds on certain specified quantiles of the distribution, and its implementation using recursive summations of multinomial probabilities is described. These recursive methodologies are illustrated with examples, and R code is available for their implementation. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Determination of the size distribution of metallic nanoparticles by optical extinction spectroscopy

    International Nuclear Information System (INIS)

    Pena, Ovidio; Rodriguez-Fernandez, Luis; Rodriguez-Iglesias, Vladimir; Kellermann, Guinther; Crespo-Sosa, Alejandro; Cheang-Wong, Juan Carlos; Silva-Pereyra, Hector Gabriel; Arenas-Alatorre, Jesus; Oliver, Alicia

    2009-01-01

    A method is proposed to estimate the size distribution of nearly spherical metallic nanoparticles (NPs) from optical extinction spectroscopy (OES) measurements based on Mie's theory and an optimization algorithm. The described method is compared against two of the most widely used techniques for the task: transmission electron microscopy (TEM) and small-angle x-ray scattering (SAXS). The size distribution of Au and Cu NPs, obtained by ion implantation in silica and a subsequent thermal annealing in air, was determined by TEM, grazing-incidence SAXS (GISAXS) geometry, and our method, and the average radius obtained by all the three techniques was almost the same for the two studied metals. Concerning the radius dispersion (RD), OES and GISAXS give very similar results, while TEM considerably underestimates the RD of the distribution

  4. Universal Probability Distribution Function for Bursty Transport in Plasma Turbulence

    International Nuclear Information System (INIS)

    Sandberg, I.; Benkadda, S.; Garbet, X.; Ropokis, G.; Hizanidis, K.; Castillo-Negrete, D. del

    2009-01-01

    Bursty transport phenomena associated with convective motion present universal statistical characteristics among different physical systems. In this Letter, a stochastic univariate model and the associated probability distribution function for the description of bursty transport in plasma turbulence is presented. The proposed stochastic process recovers the universal distribution of density fluctuations observed in plasma edge of several magnetic confinement devices and the remarkable scaling between their skewness S and kurtosis K. Similar statistical characteristics of variabilities have been also observed in other physical systems that are characterized by convection such as the x-ray fluctuations emitted by the Cygnus X-1 accretion disc plasmas and the sea surface temperature fluctuations.

  5. Multi-Functional Distributed Generation Unit for Power Quality Enhancement

    DEFF Research Database (Denmark)

    Zeng, Zheng; Yang, Huan; Guerrero, Josep M.

    2015-01-01

    A multi-functional distributed generation unit (MFDGU) and its control strategy are proposed in this paper for the purpose of enhancing power quality in low-voltage networks. By using the 3H-bridge converter structure, an MFDGU can be applied in 3-phase 4-wire low-voltage distribution networks...... reference of the MFDGU, which can be easily implemented in three-phase networks. A 15kVA prototype consisting of three full bridge converters has been built and tested. Experimental results show the feasibility of the proposed topology and control strategy....

  6. Electrical Distribution System Functional Inspection (EDSFI) data base program

    International Nuclear Information System (INIS)

    Gautam, A.

    1993-01-01

    This document describes the organization, installation procedures, and operating instructions for the database computer program containing inspection findings from the US Nuclear Regulatory Commission's (NRC's) Electrical Distribution System Functional Inspections (EDSFIs). The program enables the user to search and sort findings, ascertain trends, and obtain printed reports of the findings. The findings include observations, unresolved issues, or possible deficiencies in the design and implementation of electrical distribution systems in nuclear plants. This database will assist those preparing for electrical inspections, searching for deficiencies in a plant, and determining the corrective actions previously taken for similar deficiencies. This database will be updated as new EDSFIs are completed

  7. Confidence bounds on an empirical cumulative distribution function

    International Nuclear Information System (INIS)

    Andres, T.H.

    1986-11-01

    Methods are developed for using data from an empirical cumulative distribution function (CDF) to generate, at each point in the range of the data an upper confidence bound on the estimated value of the underlying CDF. Applications are demonstrated where a confidence bound is applied to the empirical distribution of maximum effective annual dose equivalent obtained from a set of Monte Carlo simulations in an environmental assessment of nuclear fuel waste disposal. This bound can then be used to compare the empirical dose CDF with possible regulatory guidelines for dose from a disposal facility. Methods presented in the report can be used to select the number of simulations needed to meet such guidelines

  8. Distribution of metals and metalloids in dried seaweeds and health risk to population in southeastern China.

    Science.gov (United States)

    Chen, Qing; Pan, Xiao-Dong; Huang, Bai-Fen; Han, Jian-Long

    2018-02-23

    Concern about metals and metalloids, especially heavy metals in seaweeds has risen due to potential health risk. This study investigated the distribution of 10 metals and metalloids in 295 dried seaweeds (brown and red) and estimated the possible health risk via hazard index (HI). Elements in seaweeds can be sequenced in descending order by mean values: Al > Mn > As > Cu > Cr > Ni > Cd > Se > Pb > Hg. The levels of Cd, Cu, Mn and Ni in red seaweeds were significantly higher than those in brown seaweeds (P < 0.01). Correlation analysis showed contents of Ni-Cr (r = 0.59, P < 0.01) in seaweeds had moderate positive correlations. Seaweeds from different geographical origins had diverse element distribution. Risk assessment showed that HI at mean level was less than the threshold of 1. It indicates that for the general people there is low health risk to these elements by the intake of seaweeds. Furthermore, in terms of the confirmative toxicity of some metals, such as Cd, Pb and Hg, surveillance of metals in seaweeds should be performed continuously.

  9. Spatial Distribution, Sources Apportionment and Health Risk of Metals in Topsoil in Beijing, China

    Directory of Open Access Journals (Sweden)

    Chunyuan Sun

    2016-07-01

    Full Text Available In order to acquire the pollution feature and regularities of distribution of metals in the topsoil within the sixth ring road in Beijing, a total of 46 soil samples were collected, and the concentrations of twelve elements (Nickel, Ni, Lithium, Li, Vanadium, V, Cobalt, Co, Barium, Ba, Strontium, Sr, Chrome, Cr, Molybdenum, Mo, Copper, Cu, Cadmium, Cd, Zinc, Zn, Lead, Pb were analyzed. Geostatistics and multivariate statistics were conducted to identify spatial distribution characteristics and sources. In addition, the health risk of the analyzed heavy metals to humans (adult was evaluated by an U.S. Environmental Protection Agency health risk assessment model. The results indicate that these metals have notable variation in spatial scale. The concentration of Cr was high in the west and low in the east, while that of Mo was high in the north and low in the south. High concentrations of Cu, Cd, Zn, and Pb were found in the central part of the city. The average enrichment degree of Cd is 5.94, reaching the standard of significant enrichment. The accumulation of Cr, Mo, Cu, Cd, Zn, and Pb is influenced by anthropogenic activity, including vehicle exhaustion, coal burning, and industrial processes. Health risk assessment shows that both non-carcinogenic and carcinogenic risks of selected heavy metals are within the safety standard and the rank of the carcinogenic risk of the four heavy metals is Cr > Co > Ni > Cd.

  10. Spatial Distribution, Sources Apportionment and Health Risk of Metals in Topsoil in Beijing, China.

    Science.gov (United States)

    Sun, Chunyuan; Zhao, Wenji; Zhang, Qianzhong; Yu, Xue; Zheng, Xiaoxia; Zhao, Jiayin; Lv, Ming

    2016-07-20

    In order to acquire the pollution feature and regularities of distribution of metals in the topsoil within the sixth ring road in Beijing, a total of 46 soil samples were collected, and the concentrations of twelve elements (Nickel, Ni, Lithium, Li, Vanadium, V, Cobalt, Co, Barium, Ba, Strontium, Sr, Chrome, Cr, Molybdenum, Mo, Copper, Cu, Cadmium, Cd, Zinc, Zn, Lead, Pb) were analyzed. Geostatistics and multivariate statistics were conducted to identify spatial distribution characteristics and sources. In addition, the health risk of the analyzed heavy metals to humans (adult) was evaluated by an U.S. Environmental Protection Agency health risk assessment model. The results indicate that these metals have notable variation in spatial scale. The concentration of Cr was high in the west and low in the east, while that of Mo was high in the north and low in the south. High concentrations of Cu, Cd, Zn, and Pb were found in the central part of the city. The average enrichment degree of Cd is 5.94, reaching the standard of significant enrichment. The accumulation of Cr, Mo, Cu, Cd, Zn, and Pb is influenced by anthropogenic activity, including vehicle exhaustion, coal burning, and industrial processes. Health risk assessment shows that both non-carcinogenic and carcinogenic risks of selected heavy metals are within the safety standard and the rank of the carcinogenic risk of the four heavy metals is Cr > Co > Ni > Cd.

  11. Functionalization of silicon nanowire surfaces with metal-organic frameworks

    KAUST Repository

    Liu, Nian

    2011-12-28

    Metal-organic frameworks (MOFs) and silicon nanowires (SiNWs) have been extensively studied due to their unique properties; MOFs have high porosity and specific surface area with well-defined nanoporous structure, while SiNWs have valuable one-dimensional electronic properties. Integration of the two materials into one composite could synergistically combine the advantages of both materials and lead to new applications. We report the first example of a MOF synthesized on surface-modified SiNWs. The synthesis of polycrystalline MOF-199 (also known as HKUST-1) on SiNWs was performed at room temperature using a step-by-step (SBS) approach, and X-ray photoelectron spectroscopy, X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and energy dispersive spectroscopy elemental mapping were used to characterize the material. Matching of the SiNW surface functional groups with the MOF organic linker coordinating groups was found to be critical for the growth. Additionally, the MOF morphology can by tuned by changing the soaking time, synthesis temperature and precursor solution concentration. This SiNW/MOF hybrid structure opens new avenues for rational design of materials with novel functionalities. © 2011 Tsinghua University Press and Springer-Verlag Berlin Heidelberg.

  12. Metal-organic framework templated electrodeposition of functional gold nanostructures

    International Nuclear Information System (INIS)

    Worrall, Stephen D.; Bissett, Mark A.; Hill, Patrick I.; Rooney, Aidan P.; Haigh, Sarah J.; Attfield, Martin P.; Dryfe, Robert A.W.

    2016-01-01

    Highlights: • Electrodeposition of anisotropic Au nanostructures templated by HKUST-1. • Au nanostructures replicate ∼1.4 nm pore spaces of HKUST-1. • Encapsulated Au nanostructures active as SERS substrate for 4-fluorothiophenol. - Abstract: Utilizing a pair of quick, scalable electrochemical processes, the permanently porous MOF HKUST-1 was electrochemically grown on a copper electrode and this HKUST-1-coated electrode was used to template electrodeposition of a gold nanostructure within the pore network of the MOF. Transmission electron microscopy demonstrates that a proportion of the gold nanostructures exhibit structural features replicating the pore space of this ∼1.4 nm maximum pore diameter MOF, as well as regions that are larger in size. Scanning electron microscopy shows that the electrodeposited gold nanostructure, produced under certain conditions of synthesis and template removal, is sufficiently inter-grown and mechanically robust to retain the octahedral morphology of the HKUST-1 template crystals. The functionality of the gold nanostructure within the crystalline HKUST-1 was demonstrated through the surface enhanced Raman spectroscopic (SERS) detection of 4-fluorothiophenol at concentrations as low as 1 μM. The reported process is confirmed as a viable electrodeposition method for obtaining functional, accessible metal nanostructures encapsulated within MOF crystals.

  13. Intragenic tandem repeats in Daphnia magna: structure, function and distribution

    Directory of Open Access Journals (Sweden)

    Du Pasquier Louis

    2009-10-01

    Full Text Available Abstract Background Expressed sequence tag (EST databases provide a valuable source of genetic data in organisms whose genome sequence information is not yet compiled. We used a published EST database for the waterflea Daphnia magna (Crustacea:Cladocera to isolate variable number of tandem repeat (VNTR markers for linkage mapping, Quantitative Trait Loci (QTL, and functional studies. Findings Seventy-four polymorphic markers were isolated and characterised. Analyses of repeat structure, putative gene function and polymorphism indicated that intragenic tandem repeats are not distributed randomly in the mRNA sequences; instead, dinucleotides are more frequent in non-coding regions, whereas trinucleotides (and longer motifs involving multiple-of-three nucleotide repeats are preferentially situated in coding regions. We also observed differential distribution of repeat motifs across putative genetic functions. This indicates differential selective constraints and possible functional significance of VNTR polymorphism in at least some genes. Conclusion Databases of VNTR markers situated in genes whose putative function can be inferred from homology searches will be a valuable resource for the genetic study of functional variation and selection.

  14. Oxygen effect on the work function of electropositive metal films adsorbed on 4d and 5d-transition metals

    International Nuclear Information System (INIS)

    Kultashev, O.K.; Makarov, A.P.; Rozhkov, S.E.

    1976-01-01

    The thermionic emission method was used to study the effect of oxygen upon the work function of films of electropositive metals, Sc, Y, La and Ba on some monocrystal and polycrystalline specimens of 4d- and 5d-transition metals of groups 4-8 of the Periodic system. It was revealed that when the supports were polycrystalline and monocrystalline specimens of transition metals of Group 5 (niobium and tantalum), the work function phi of films of electropositive adsorbates dropped substantially as compared, e.g., to the phi values on the same faces of tungsten. When the concentration of the electropositive adsorbate exceeds the optimum value (in the absence of oxygen), oxygen exerts an appreciably activating action upon the work function phi of films of electropositive adsorbates on transition metals of the Groups 7 and 8. The activating action of oxygen is assumed to be due to a possibility of formation of surface interstitial structures

  15. Effects of perfluorochemical distribution and elimination dynamics on cardiopulmonary function.

    Science.gov (United States)

    Miller, T F; Milestone, B; Stern, R; Shaffer, T H; Wolfson, M R

    2001-03-01

    Based on a physicochemical property profile, we tested the hypothesis that different perfluorochemical (PFC) liquids may have distinct effects on intrapulmonary PFC distribution, lung function, and PFC elimination kinetics during partial liquid ventilation (PLV). Young rabbits were studied in five groups [healthy, PLV with perflubron (PFB) or with perfluorodecalin (DEC); saline lavage injury and conventional mechanical ventilation (CMV); saline lavage injury PLV with PFB or with DEC]. Arterial blood chemistry, respiratory compliance (Cr), quantitative computed tomography of PFC distribution, and PFC loss rate were assessed for 4 h. Initial distribution of PFB was more homogenous than that of DEC; over time, PFB redistributed to dependent regions whereas DEC distribution was relatively constant. PFC loss rate decreased over time in all groups, was higher with DEC than PFB, and was lower with injury. In healthy animals, arterial PO(2) (Pa(O(2))) and Cr decreased with either PFC; the decrease was greater and sustained with DEC. Lavaged animals treated with either PFC demonstrated increased Pa(O(2)), which was sustained with PFB but deteriorated with DEC. Lavaged animals treated with PFB demonstrated increased Cr, higher Pa(O(2)), and lower arterial PCO(2) than with CMV or PLV with DEC. The results indicate that 1) initial distribution and subsequent intrapulmonary redistribution of PFC are related to PFC properties; 2) PFC distribution influences PFC elimination, gas exchange, and Cr; and 3) PFC elimination, gas exchange, and Cr are influenced by PFC properties and lung condition.

  16. Engineering metal precipitate size distributions to enhance gettering in multicrystalline silicon

    Energy Technology Data Exchange (ETDEWEB)

    Hofstetter, Jasmin; Fenning, David P.; Buonassisi, Tonio [Massachusetts Institute of Technology, 77 Massachusetts Ave., Cambridge MA, 02139 (United States); Lelievre, Jean-Francois [Universidad Politecnica de Madrid, Avd. Complutense s/n, 28040 Madrid (Spain); Del Canizo, Carlos [Centro de Tecnologia del Silicio Solar CENTESIL, Getafe (Spain)

    2012-10-15

    The extraction of metal impurities during phosphorus diffusion gettering (PDG) is one of the crucial process steps when fabricating high-efficiency solar cells using low-cost, lower-purity silicon wafers. In this work, we show that for a given metal concentration, the size and density of metal silicide precipitates strongly influences the gettering efficacy. Different precipitate size distributions can be already found in silicon wafers grown by different techniques. In our experiment, however, the as-grown distribution of precipitated metals in multicrystalline Si sister wafers is engineered through different annealing treatments in order to control for the concentration and distribution of other defects. A high density of small precipitates is formed during a homogenization step, and a lower density of larger precipitates is formed during extended annealing at 740 C. After PDG, homogenized samples show a decreased interstitial iron concentration compared to as-grown and ripened samples, in agreement with simulations. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  17. Concentration, enrichment and distribution of heavy metals in surface sediments of the Tangier Bay, Morocco

    Directory of Open Access Journals (Sweden)

    María Rocío Rodríguez-Barroso

    2010-11-01

    Full Text Available The distribution, enrichment, and accumulation of heavy metals in the surface sediments of the Tangier Bay, Morocco, were investigated. Surface sediment samples from eleven locations in the Bay of Tangier were collected in 2007 and characterized for grain size, organic matter and metal content (e.g. Fe, Mn, Cr, Cu, Ni, Pb, Zn and Cd. The evaluation of the heavy metal contamination status of the bay showed minor enrichment by the enrichment factors (EF calculation, corroborated by the metal pollution index (MPI. The results of a Pearson correlation showed high positive correlations among organic carbon and most metals (0.788 < r < 0.939 and cluster analysis grouped the stations inside the harbour (stations 1, 10 and 9 and in the vicinity of the principal rivers in the bay (stations 3 and 11, which showed the highest concentrations of metal content. The main sources of contamination are domestic and industrial effluents, which arise due to the lack of sewage treatment. However, these areas could not be classified as polluted when the data were compared with sediment quality guidelines (USEPA, 1997.

  18. Distribution, relationship, and risk assessment of toxic heavy metals in walnuts and growth soil.

    Science.gov (United States)

    Han, Yongxiang; Ni, Zhanglin; Li, Shiliang; Qu, Minghua; Tang, Fubin; Mo, Runhong; Ye, Caifen; Liu, Yihua

    2018-04-14

    Walnut is one of the most popular nuts worldwide and contains various mineral nutrients. Little is known, however, about the relationship between toxic heavy metals in walnuts and growth soil. In this study, we investigated the distribution, relationship, and risk assessment of five toxic heavy metals-lead (Pb), arsenic (As), chromium (Cr), cadmium (Cd), and mercury (Hg)-in walnuts and growth soil in the main production areas of China. The results showed that the main heavy metal pollution in walnut and soil was Pb and Cd. Regionally, positive relationships existed between heavy metals and the pH and organic matter of soil. In addition, we observed a notable uptake effect between walnut and growth soil. In this study, we found a significant correlation (r = 0.786, P toxic heavy metal pollution in walnuts and growth soil could be helpful to screen suitable planting sites to prevent and control heavy metal pollution and improve the quality and safety of walnut.

  19. History of heavy metal accumulation in the Svalbard area: Distribution, origin and transport pathways.

    Science.gov (United States)

    Zaborska, Agata; Beszczyńska-Möller, Agnieszka; Włodarska-Kowalczuk, Maria

    2017-12-01

    In this study temporal changes of Pb, Zn, Cd and Cu concentrations were studied in 19 dated sediment cores collected from Svalbard fjords and the Barents Sea. The main aim was to study spatial and historical variations in heavy metal concentrations, deposition rates and sources in the context of different metal transport pathways. Metal concentrations ranged from 5.7 to 45.8 mg kg -1 for Pb, from 13.4 to 54.5 mg kg -1 for Cu, from 0.01 to 0.90 mg kg -1 for Cd and from 55.6 to 130.4 mg kg -1 for Zn. Some fjords were unpolluted by heavy metals while in others a clear signal of metal enrichment was found (outer Kongsfjorden, Hornsund, Adventfjorden). Large-scale processes such as atmospheric and oceanic transport were found to be important drivers of heavy metal contaminant distribution. The significance of global drivers varied among the fjords, due to coupling with local processes. Outer fjord parts, the most impacted by oceanic transport, were characterized by the excess 206 Pb/ 207 Pb values of ∼1.17, while the inner basins were characterized by the excess 206 Pb/ 207 Pb of ∼1.14 suggesting possible different importance of Pb sources (marine currents and atmospheric transport). Copyright © 2017 Elsevier Ltd. All rights reserved.

  20. Spatial distribution and risk assessment of heavy metals in sediments of Shuangtaizi estuary, China

    International Nuclear Information System (INIS)

    Li, Chen; Song, Chengwen; Yin, Yanyan; Sun, Menghan; Tao, Ping; Shao, Mihua

    2015-01-01

    Highlights: • Five heavy metals are analyzed in the sediments from Shuangtaizi estuary. • Particle size of the sediment effects the concentration of heavy metals. • Pb, Cu, Zn and Hg pose low ecological risks in the Shuangtaizi estuary. • Heavy metal pollution in Shuangtaizi estuary is mainly dominated by Cd. - Abstract: In order to evaluate the spatial distribution and potential ecological risk of Pb, Cu, Zn, Cd, and Hg, the surface sediments were collected from 18 sites in the Shuangtaizi estuary. The concentrations of Pb, Cu, Zn, Cd, and Hg were analyzed by atomic absorption spectrophotometry and atomic fluorescence spectrometry after digestion. The particle sizes of the sediments were analyzed using a laser diffraction particle size analyzer. The results show that the heavy metal contents in the sediments are observed in the following order: Zn (18.25–126.75 mg/kg) > Pb (4.38–9.65 mg/kg) > Cu (1.80–17.68 mg/kg) > Cd (0.241–0.764 mg/kg) > Hg (0.007–0.021 mg/kg). In comparison with the concentrations of heavy metals in other regions, the concentrations of Pb, Cu, and Zn in the Shuangtaizi estuary are generally low, and the Cd concentrations are close to those reported in other regions. Both the potential ecological risk index and the geoaccumulation index reveal that the heavy metal pollution in Shuangtaizi estuary is mainly dominated by Cd

  1. Transverse momentum-dependent parton distribution functions in lattice QCD

    Energy Technology Data Exchange (ETDEWEB)

    Engelhardt, Michael G. [New Mexico State University; Musch, Bernhard U. [Tech. University Munich; Haegler, Philipp G. [Tech. University Munich; Negele, John W. [MIT; Schaefer, Andreas [Regensburg

    2013-08-01

    A fundamental structural property of the nucleon is the distribution of quark momenta, both parallel as well as perpendicular to its propagation. Experimentally, this information is accessible via selected processes such as semi-inclusive deep inelastic scattering (SIDIS) and the Drell-Yan process (DY), which can be parametrized in terms of transversemomentum-dependent parton distributions (TMDs). On the other hand, these distribution functions can be extracted from nucleon matrix elements of a certain class of bilocal quark operators in which the quarks are connected by a staple-shaped Wilson line serving to incorporate initial state (DY) or final state (SIDIS) interactions. A scheme for evaluating such matrix elements within lattice QCD is developed. This requires casting the calculation in a particular Lorentz frame, which is facilitated by a parametrization of the matrix elements in terms of invariant amplitudes. Exploratory results are presented for the time-reversal odd Sivers and Boer-Mulders transverse momentum shifts.

  2. Spatial distribution measured by the modulation transfer function

    International Nuclear Information System (INIS)

    Rossi, P.; Brice, D.K.; Doyle, B.L.

    2003-01-01

    Spatial distributions in ion micro-beam and IBA experimental practice are regularly characterized through the parameters of FWHM and tail area percentage (TF, tail fraction). Linear and stationary transducer theory allows these distributions to be described in the Fourier-dual frequency space, and provides an indirect method to evaluate them through measurement of the modulation transfer function (MTF). We suggest direct measurement of MTF by employing bar pattern grids, similar to those used for calibration of radiological equipment. Assuming spatial distributions of the form exp(-(|αx|) η ), we are able to relate the MTF measurements to the more popular FWHM and TF. This new approach to determine spatial resolution can become a standard for use by the micro-beam community

  3. Use of the Digamma Function in Statistical Astrophysics Distributions

    Science.gov (United States)

    Cahill, Michael

    2017-06-01

    Relaxed astrophysical statistical distributions may be constructed by using the inverse of a most probable energy distribution equation giving the energy ei of each particle in cell i in terms of the cell’s particle population Ni. The digamma mediated equation is A + Bei = Ψ(1+ Ni), where the constants A & B are Lagrange multipliers and Ψ is the digamma function given by Ψ(1+x) = dln(x!)/dx. Results are discussed for a Monatomic Ideal Gas, Atmospheres of Spherical Planets or Satellites and for Spherical Globular Clusters. These distributions are self-terminating even if other factors do not cause a cutoff. The examples are discussed classically but relativistic extensions are possible.

  4. Multi-Functional Distributed Secondary Control for Autonomous Microgrids

    DEFF Research Database (Denmark)

    Shafiee, Qobad

    or connected to the main grid. Apart from the obvious benefits of MGs, their introduction into the traditional distribution network raises many new challenges, thus, a hierarchical control concept has been introduced for these systems. While the decentralized primary control of this hierarchy ensures...... power exchange with external grid or/and with other MGs and includes functions related to efficiency and economic enhancement. This thesis is focused on development of distributed control strategies for secondary control of autonomous ac and dc MGs to avoid a central controller and complex communication...... to proportionally share the load power even at the presence of different control parameters and initial values. This thesis also proposes a distributed hierarchical control framework for dc MG clusters to ensure smooth connection and reliable operation of these systems. A decentralize adaptive droop method...

  5. Sequential function approximation on arbitrarily distributed point sets

    Science.gov (United States)

    Wu, Kailiang; Xiu, Dongbin

    2018-02-01

    We present a randomized iterative method for approximating unknown function sequentially on arbitrary point set. The method is based on a recently developed sequential approximation (SA) method, which approximates a target function using one data point at each step and avoids matrix operations. The focus of this paper is on data sets with highly irregular distribution of the points. We present a nearest neighbor replacement (NNR) algorithm, which allows one to sample the irregular data sets in a near optimal manner. We provide mathematical justification and error estimates for the NNR algorithm. Extensive numerical examples are also presented to demonstrate that the NNR algorithm can deliver satisfactory convergence for the SA method on data sets with high irregularity in their point distributions.

  6. Parton distribution functions with QED corrections in the valon model

    Science.gov (United States)

    Mottaghizadeh, Marzieh; Taghavi Shahri, Fatemeh; Eslami, Parvin

    2017-10-01

    The parton distribution functions (PDFs) with QED corrections are obtained by solving the QCD ⊗QED DGLAP evolution equations in the framework of the "valon" model at the next-to-leading-order QCD and the leading-order QED approximations. Our results for the PDFs with QED corrections in this phenomenological model are in good agreement with the newly related CT14QED global fits code [Phys. Rev. D 93, 114015 (2016), 10.1103/PhysRevD.93.114015] and APFEL (NNPDF2.3QED) program [Comput. Phys. Commun. 185, 1647 (2014), 10.1016/j.cpc.2014.03.007] in a wide range of x =[10-5,1 ] and Q2=[0.283 ,108] GeV2 . The model calculations agree rather well with those codes. In the latter, we proposed a new method for studying the symmetry breaking of the sea quark distribution functions inside the proton.

  7. Beam brightness calculation for analytical and empirical distribution functions

    International Nuclear Information System (INIS)

    Myers, T.J.; Boulais, K.A.; O, Y.S.; Rhee, M.J.

    1992-01-01

    The beam brightness, a figure of merit for a beam quality useful for high-current low-emittance beams, was introduced by van Steenbergen as B = I/V 4 , where I is the beam current and V 4 is the hypervolume in the four-dimensional trace space occupied by the beam particles. Customarily, the brightness is expressed in terms of the product of emittances ε x ε y as B = ηI/(π 2 ε x ε y ), where η is a form factor of order unity which depends on the precise definition of emittance and hypervolume. Recently, a refined definition of the beam brightness based on the arithmetic mean value defined in statistics is proposed. The beam brightness is defined as B triple-bond 4 > = I -1 ∫ ρ 4 2 dxdydx'dy', where I is the beam current given by I ∫ ρ 4 dxdydx'dy'. Note that in this definition, neither the hypervolume V 4 nor the emittance, are explicitly used; the brightness is determined solely by the distribution function. Brightnesses are unambiguously calculated and expressed analytically in terms of the respective beam current and effective emittance for a few commonly used distribution functions, including Maxwellian and water-bag distributions. Other distributions of arbitrary shape frequently encountered in actual experiments are treated numerically. The resulting brightnesses are expressed in the form B = ηI/(π 2 ε x ε y ), and η is found to be weakly dependent on the form of velocity distribution as well as spatial distribution

  8. The distributional zeta-function in disordered field theory

    Science.gov (United States)

    Svaiter, B. F.; Svaiter, N. F.

    2016-09-01

    In this paper, we present a new mathematical rigorous technique for computing the average free energy of a disordered system with quenched randomness, using the replicas. The basic tool of this technique is a distributional zeta-function, a complex function whose derivative at the origin yields the average free energy of the system as the sum of two contributions: the first one is a series in which all the integer moments of the partition function of the model contribute; the second one, which cannot be written as a series of the integer moments, can be made as small as desired. This result supports the use of integer moments of the partition function, computed via replicas, for expressing the average free energy of the system. One advantage of the proposed formalism is that it does not require the understanding of the properties of the permutation group when the number of replicas goes to zero. Moreover, the symmetry is broken using the saddle-point equations of the model. As an application for the distributional zeta-function technique, we obtain the average free energy of the disordered λφ4 model defined in a d-dimensional Euclidean space.

  9. Symmetry Breaking in the Parton Distribution Functions of the Nucleon

    Science.gov (United States)

    Cao, Fu-Guang; Signal, A. I.

    We study flavour symmetry breaking in the nucleon's parton distribution functions (PDF) using the meson cloud model and `Pauli blocking' mechanism. It was found that the `Pauli blocking' contribution to the integrated polarized asymmetry is much larger than the meson cloud, in contrast to approximate equality in the unpolarized case. We also investigate charge symmetry breaking in the nucleon's PDF using the meson cloud model. Our results are very different from the quark model calculations.

  10. Brookhaven Reactor Experiment Control Facility, a distributed function computer network

    International Nuclear Information System (INIS)

    Dimmler, D.G.; Greenlaw, N.; Kelley, M.A.; Potter, D.W.; Rankowitz, S.; Stubblefield, F.W.

    1975-11-01

    A computer network for real-time data acquisition, monitoring and control of a series of experiments at the Brookhaven High Flux Beam Reactor has been developed and has been set into routine operation. This reactor experiment control facility presently services nine neutron spectrometers and one x-ray diffractometer. Several additional experiment connections are in progress. The architecture of the facility is based on a distributed function network concept. A statement of implementation and results is presented

  11. Generic trend of work functions in transition-metal carbides and nitrides

    Energy Technology Data Exchange (ETDEWEB)

    Yoshitake, Michiko, E-mail: yoshitake.michiko@nims.go.jp [MANA Nanoelectronics Materials Unit, National Institute for Materials Science, Tsukuba, Ibaraki 305-0003 (Japan)

    2014-11-15

    Transition-metal carbides and nitrides (TMCs and TMNs) are promising electrode materials for various electronic devices such as metal-oxide-semiconductor field-effect transistors and metal-insulator-metal capacitors. In this paper, the work functions of TMCs and TMNs are discussed systematically. Based upon the origin of the work function, the effect upon transition metal species by different periodic table groups is explained, carbides are compared with nitrides for the same transition metal, and the effect of carbon or nitrogen vacancies is discussed. In addition, a method to estimate the generic trend of the work function is proposed for TMC{sub x}, TMN{sub x}, TMC{sub 1−y}N{sub y} (transition metal carbonitrides), and TM{sub 1−z}TM′{sub z}C (alloy carbides)

  12. Luminescent metal nanoclusters: controlled synthesis and functional applications

    OpenAIRE

    Sun, Hong-Tao; Sakka, Yoshio

    2013-01-01

    Luminescent metal nanoclusters that consist of only several, to tens of, metal atoms and which possess sizes comparable to the Fermi wavelength of electrons have recently attracted significant attention. This new class of luminescent materials not only provides the missing link between atomic and nanoparticle behaviors in metals but also they present abundant novel information for the development of new applicable material systems to meet urgent needs in many areas (such as ultrasensitive sen...

  13. [Impact of heavy metals pollution on the community structure and spatial distribution of soil animals].

    Science.gov (United States)

    Sun, Xian-Bin; Liu, Hong-Yu; Li, Yu-Cheng; Zhang, Xiao-Ping

    2007-09-01

    By sampling at 8 plots surrounding the coal-mining and coal-ash areas in Huannan City of Anhui Province, a total of 3859 individuals of soil macro-, meso-, and micro-fauna belonging to 22 groups, 9 classes and 4 phyla were collected. The dominant groups were Collembola, Acarina and Nematoda, accounting for 74% of the total, and the others were frequent and rare groups. Heavy metals pollution had powerful impact on soil animals. The individual numbers and groups of soil animals declined with the aggravation of heavy metals pollution from out of the dam site to the nearing site of coal-ash area in Luohe Power Plant, and showed an abnormal distribution or little change in vertical and disappeared in surface layer. The heavy metals pollution resulted in a decline in the diversity index, evenness and density-group index, but a rise in the dominance index of soil animals.

  14. Angular and mass resolved energy distribution measurements with a gallium liquid metal ion source

    International Nuclear Information System (INIS)

    Marriott, Philip

    1987-06-01

    Ionisation and energy broadening mechanisms relevant to liquid metal ion sources are discussed. A review of experimental results giving a picture of source operation and a discussion of the emission mechanisms thought to occur for the ionic species and droplets emitted is presented. Further work is suggested by this review and an analysis system for angular and mass resolved energy distribution measurements of liquid metal ion source beams has been constructed. The energy analyser has been calibrated and a series of measurements, both on and off the beam axis, of 69 Ga + , Ga ++ and Ga 2 + ions emitted at various currents from a gallium source has been performed. A comparison is made between these results and published work where possible, and the results are discussed with the aim of determining the emission and energy spread mechanisms operating in the gallium liquid metal ion source. (author)

  15. Functional brain networks develop from a "local to distributed" organization.

    Directory of Open Access Journals (Sweden)

    Damien A Fair

    2009-05-01

    Full Text Available The mature human brain is organized into a collection of specialized functional networks that flexibly interact to support various cognitive functions. Studies of development often attempt to identify the organizing principles that guide the maturation of these functional networks. In this report, we combine resting state functional connectivity MRI (rs-fcMRI, graph analysis, community detection, and spring-embedding visualization techniques to analyze four separate networks defined in earlier studies. As we have previously reported, we find, across development, a trend toward 'segregation' (a general decrease in correlation strength between regions close in anatomical space and 'integration' (an increased correlation strength between selected regions distant in space. The generalization of these earlier trends across multiple networks suggests that this is a general developmental principle for changes in functional connectivity that would extend to large-scale graph theoretic analyses of large-scale brain networks. Communities in children are predominantly arranged by anatomical proximity, while communities in adults predominantly reflect functional relationships, as defined from adult fMRI studies. In sum, over development, the organization of multiple functional networks shifts from a local anatomical emphasis in children to a more "distributed" architecture in young adults. We argue that this "local to distributed" developmental characterization has important implications for understanding the development of neural systems underlying cognition. Further, graph metrics (e.g., clustering coefficients and average path lengths are similar in child and adult graphs, with both showing "small-world"-like properties, while community detection by modularity optimization reveals stable communities within the graphs that are clearly different between young children and young adults. These observations suggest that early school age children and adults

  16. Value-distribution of the Riemann zeta-function and related functions near the critical line

    OpenAIRE

    Christ, Thomas

    2013-01-01

    The Riemann zeta-function forms a central object in multiplicative number theory; its value-distribution encodes deep arithmetic properties of the prime numbers. Here, a crucial role is assigned to the analytic behavior of the zeta-function on the so called critical line. In this thesis we study the value-distribution of the Riemann zeta-function near and on the critical line. Amongst others we focus on the following. PART I: A modified concept of universality, a-points near the critical ...

  17. Influence of Flue Gas Desulfurization Gypsum Amendments on Heavy Metal Distribution in Reclaimed Sodic Soils

    Science.gov (United States)

    Chen, Qun; Wang, Shujuan; Li, Yan; Zhang, Ning; Zhao, Bo; Zhuo, Yuqun; Chen, Changhe

    2015-01-01

    Abstract Although flue gas desulfurization (FGD) gypsum has become an effective soil amendment for sodic soil reclamation, it carries extra heavy metal contamination into the soil environment. The fate of heavy metals introduced by FGD gypsum in sodic or saline–alkali soils is still unclear. This work aims to investigate the effects of FGD gypsum addition on the heavy metal distributions in a sodic soil. Original soil samples were collected from typical sodic land in north China. Soil column leaching tests were conducted to investigate the influence of FGD gypsum addition on the soil properties, especially on distribution profiles of the heavy metals (Pb, Cd, Cr, As, and Hg) in the soil layers. Results showed that pH, electrical conductivity, and exchangeable sodium percentage in amended soils were significantly reduced from 10.2 to 8.46, 1.8 to 0.2 dS/m, and 18.14% to 1.28%, respectively. As and Hg concentrations in the soils were found to be positively correlated with FGD gypsum added. The amount of Hg in the leachate was positively correlated with FGD gypsum application ratio, whereas a negative correlation was observed between the Pb concentration in the leachate and the FGD gypsum ratio. Results revealed that heavy metal concentrations in soils complied well with Environmental Quality Standard for Soils in China (GB15618-1995). This work helps to understand the fate of FGD gypsum-introduced heavy metals in sodic soils and provides a baseline for further environmental risk assessment associated with applying FGD gypsum for sodic soil remediation. PMID:26064038

  18. Spatial distribution of metals in urban topsoils of Xuzhou (China): controlling factors and environmental implications

    Science.gov (United States)

    Wang, Xue-Song; Qin, Yong

    2006-03-01

    The contamination of soils by metals from various sources is a subject of increasing concern in recent times. Twenty-eight elements (Fe, Ti, Cr, Al, Ga, Pb, Sc, Ba, Li, Cd, Be, Co, Cu, Mn, Ni, V, Zn, Mo, Pt, Pd, Au, As, Sb, Se, Hg, Bi, Ag and Sn) have been analyzed from urban topsoil from the city of Xuzhou. The concentrations of these analyzed elements have been correlated to some soil parameters such as organic matter, pH, cation exchange capacity, carbonate content, and granulometric fractions (clay, silt and sand). Results of the statistical analysis show a large variety and complexity in these relationships. The spatial distributions of these metal concentrations were also constructed using geographical information system. The spatial distribution patterns of the elements analyzed show that traffic and industrial activities are the principal anthropogenic pollutant sources.

  19. Distribution of heavy metals around the Barakah nuclear power plant in the United Arab Emirates.

    Science.gov (United States)

    Al Rashdi, Mouza Rashid; Alaabed, Sulaiman; El Tokhi, Mohamed; Howari, Fares M; El Mowafi, Walid; Arabi, Alya A

    2017-08-01

    Inductively coupled plasma emission spectroscopy was used to measure the concentrations of heavy metals in 58 samples collected from the Barakah nuclear power plant (BNPP) area, UAE. The grain size distribution was symmetric, but the samples ranged from fine to coarse sand. The inverse relationship between grain size and heavy metal contaminations was validated. The pre-operational average heavy metal contaminations around the BNPP were 0.03, 0.40, 1.2, 2.05, 1.66, 1.6, 5.9, 7.3, 7, 8.8, 60, and 2521 ppm for Cd, Mo, Co, Cu, Pb, As, Zn, Ni, V, Cr, Mn, and Fe, respectively. The spatial distribution was more compact in the south compared to the north, with less severe contaminations in the east and west. The negative geoaccumulation indices suggest an uncontaminated area, and the BNPP has minor enrichments. All concentrations were significantly below the safe limits set by the Dutch guidelines. The levels of heavy metals reported in the UAE were lower than levels reported in countries around the world.

  20. Heavy Metal Distribution in Opportunistic Beach Nourishment: A Case Study in Greece

    Directory of Open Access Journals (Sweden)

    Spyros Foteinis

    2013-01-01

    Full Text Available The existence and distribution of persistent pollutants, such as heavy metals, in coastal sediment used for opportunistic beach nourishment, is a problem that has not received much attention. Here, we assessed the coastal sediments in one restoration project for the occurrence and distribution of heavy metals, by utilizing an Energy Dispersive X-Ray Fluorescence (EDXRF system. Heavy metal point sources included (i the effluents of small industries (tanneries, (ii wastewater treatment plant effluents, and (iii paint and oil scraps from substandard ship maintenance activities that take place on ports breakwaters. A few neighboring beaches were found to have similar heavy metal concentrations, with mean values of Cu, Zn, and Pb ranging from 80 to 130, 15 to 25, and 25 to 40 mg/kg, respectively. Existing legislation regarding dredging activities in Greece appears insufficient for sustainable and environmentally friendly nourishment. We conclude that before opportunistic beach restoration projects materialize with material borrowed from ports and harbors the quality of the dredged material needs to be assessed.

  1. The GIRAFFE Inner Bulge Survey (GIBS). II. Metallicity distributions and alpha element abundances at fixed Galactic latitude

    Science.gov (United States)

    Gonzalez, O. A.; Zoccali, M.; Vasquez, S.; Hill, V.; Rejkuba, M.; Valenti, E.; Rojas-Arriagada, A.; Renzini, A.; Babusiaux, C.; Minniti, D.; Brown, T. M.

    2015-12-01

    Aims: We investigate metallicity and α-element abundance gradients along a Galactic longitude strip, at latitude b ~ -4°, with the aim of providing observational constraints for the structure and origin of the Milky Way bulge. Methods: High-resolution (R ~ 22 500) spectra for 400 K giants, in four fields within -4.8° ≲ b ≲ -3.4° and -10° ≲ l ≲ +10°, were obtained within the GIRAFFE Inner Bulge Survey (GIBS) project. To this sample we added another ~400 stars in Baade's Window at (l,b) = (1°,-4°), observed with the identical instrumental configuration: FLAMES GIRAFFE in Medusa mode with HR13 setup. All target stars lie within the red clump of the bulge colour-magnitude diagram, thus minimising contamination from the disc or halo stars. The spectroscopic stellar surface parameters were derived with an automatic method based on the GALA code, while the [Ca/Fe] and [Mg/Fe] abundances as a function of [Fe/H] were derived through a comparison with the synthetic spectra using MOOG. We constructed the metallicity distributions for the entire sample, and for each field individually, in order to investigate the presence of gradients or field-to-field variations in the shape of the distributions. Results: The metallicity distributions in the five fields are consistent with being drawn from a single parent population, indicating the absence of a gradient along the major axis of the Galactic bar. The global metallicity distribution is nicely fitted by two Gaussians. The metal-poor component is rather broad, with a mean at ⟨ [Fe/H] ⟩ = -0.31 dex and σ = 0.31 dex. The metal-rich component is narrower, with mean ⟨ [Fe/H] ⟩ = + 0.26 and σ = 0.2 dex. The [Mg/Fe] ratio follows a tight trend with [Fe/H], with enhancement with respect to solar in the metal-poor regime similar to the value observed for giant stars in the local thick disc. [Ca/Fe] abundances follow a similar trend, but with a considerably larger scatter than [Mg/Fe]. A decrease in [Mg/Fe] is

  2. Surficial and vertical distribution of heavy metals in different estuary wetlands in the Pearl river, South China

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Honggang; Cui, Baoshan [State Key Joint Laboratory of Environmental Simulation and Pollution Control, School of Environment, Beijing Normal University, Beijing (China); Zhang, Kejiang [Xinjiang Research Center of Water and Wastewater Treatment, Xinjiang Deland Co., LTD., Urumqi (China)

    2012-10-15

    A total of 87 soil profiles sampled from five types of wetlands in the Pearl River estuary were analyzed to investigate the surficial and vertical distributions of heavy metals (Cd, Cr, Cu, Ni, Pb, and Zn). The results show that wetlands directly connected with rivers (e.g., riparian wetlands, estuarine wetlands, and mangrove wetlands) has much higher metal concentrations than those indirectly connected with rivers (e.g., pond wetlands and reclaimed wetlands). The river water is the major pollution source for all investigated heavy metals. The vertical distribution of heavy metals can be classified into three patterns: (i) linear distribution pattern. The concentration of heavy metals gradually decreases with an increase in soil depth (for riparian and estuarine wetlands); (ii) irregular and stable pattern (for pond and reclaimed wetlands); and (iii) middle enrichment pattern (for mangrove wetlands). In addition to river-borne inputs, a variety of vegetation composition, hydraulic conditions, and human activities also contribute to the variation in distribution of heavy metals in different wetlands. Soil properties (e.g., particle size, pH, salinity, and SOM) also affect the distribution of trace metals in each soil layer. The major pollution source of heavy metals is industrial wastewater. Other sources include agriculture and domestic premises, and atmospheric deposition. This study provides a sound basis for the risk assessment of heavy metals in the studied wetlands and for wetland conservation in general. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  3. Temporal variations in metallothionein concentration and subcellular distribution of metals in gills and digestive glands of the oyster Crassostrea angulata

    Directory of Open Access Journals (Sweden)

    Chiara Trombini

    2010-11-01

    Full Text Available The metallothionein levels and metal concentrations in whole body, digestive gland and gills of Crassostrea angulata were analyzed in field samples collected from the River Guadalquivir estuary over several years following a mining waste spill upstream. The subcellular distribution of metals was analyzed to determine the mechanisms involved in the detoxification process. The highest metallothionein levels were reported in the digestive gland shortly after the mining contamination event. In this organ, metals are stored preferentially in the non-cytosolic fraction when increased bioaccumulation takes place. In the cytosol of the gills, metals are associated with metallothionein, whereas in the digestive gland, the distribution of metals between metallothioneins and high molecular weight proteins is similar. Metallothionein variation cannot be explained by metals alone; other abiotic factors must be taken into account. In order to use metallothionein as a metal exposure biomarker in field studies, natural variability needs to be taken into account for the correct interpretation of results.

  4. STATISTICAL DISTRIBUTION PATTERNS IN MECHANICAL AND FATIGUE PROPERTIES OF METALLIC MATERIALS

    OpenAIRE

    Tatsuo, SAKAI; Masaki, NAKAJIMA; Keiro, TOKAJI; Norihiko, HASEGAWA; Department of Mechanical Engineering, Ritsumeikan University; Department of Mechanical Engineering, Toyota College of Technology; Department of Mechanical Engineering, Gifu University; Department of Mechanical Engineering, Gifu University

    1997-01-01

    Many papers on the statistical aspect of materials strength have been collected and reviewed by The Research Group for Statistical Aspects of Materials Strength.A book of "Statistical Aspects of Materials Strength" was written by this group, and published in 1992.Based on the experimental data compiled in this book, distribution patterns of mechanical properties are systematically surveyed paying an attention to metallic materials.Thus one can obtain the fundamental knowledge for a reliabilit...

  5. The Particle Distribution in Liquid Metal with Ceramic Particles Mould Filling Process

    Science.gov (United States)

    Dong, Qi; Xing, Shu-ming

    2017-09-01

    Adding ceramic particles in the plate hammer is an effective method to increase the wear resistance of the hammer. The liquid phase method is based on the “with the flow of mixed liquid forging composite preparation of ZTA ceramic particle reinforced high chromium cast iron hammer. Preparation method for this system is using CFD simulation analysis the particles distribution of flow mixing and filling process. Taking the 30% volume fraction of ZTA ceramic composite of high chromium cast iron hammer as example, by changing the speed of liquid metal viscosity to control and make reasonable predictions of particles distribution before solidification.

  6. Spatial distribution and ecological risk assessment of metals in sediments of Baiyangdian wetland ecosystem.

    Science.gov (United States)

    Su, Liya; Liu, Jingling; Christensen, Per

    2011-07-01

    Although there are many studies of heavy metal contaminations of sediments, attention has seldom been paid to the problem in developing countries. The purpose of this article is to find the distribution and ecological risk of As, Hg, Cr, Cd, Pb, Cu, and Zn in surface sediment of Baiyangdian which is the biggest wetland in Northeast China. We apply three methodologies. The first is literature analysis comparing total concentrations of heavy metals with other water bodies around world. The second is Chinese Environmental Quality Standard for Soils (EQSS), National Environmental Protection Agency of China 1995, and the third is Soil and Aquatic Sediment Guidelines and Standards issued by New York Department of Environmental Conservation (NYSDEC). The results show that compared to other water bodies around the world, the seven heavy metals are low. However, Cd was found in the most polluting level of EQSS near a village and was second grade some distance from it. The village was also the most polluted site of Zn, which was in the second grade. When assessed by NYSDEC, Cu, Cr, and As contaminated the sediment and with moderate impacts on benthic life while Pb, Hg, and Zn were found at tolerable levels throughout Baiyangdian. The centre of Cu and Cr contamination was also near the village. As is the most polluting heavy metals with a major occurrence in the middle of the wetland. There were no heavy metals creating severe disturbance to the benthic communities. Based on the assessment, this article proposes different options for more sustainable management.

  7. The spatial and temporal distribution of heavy metals in sediments of Victoria Harbour, Hong Kong

    International Nuclear Information System (INIS)

    Tang, Chloe Wing-yee; Ip, Carman Ching-man; Zhang Gan; Shin, Paul K.S.; Qian Peiyuan; Li Xiangdong

    2008-01-01

    Victoria Harbour has received substantial loadings of pollutants from industrial and municipal wastewater discharged since the 1950s. Inputs of contaminants have declined dramatically during the last two decades as a result of better controls at the source and improved wastewater treatment facilities. To assess the spatial and temporal changes of metal contaminants in sediments in Victoria Harbour, core and grab sediments were collected. The central harbour areas were generally contaminated with heavy metals. The spatial distribution of trace metals can probably be attributed to the proximity of major urban and industrial discharge points, and to the effect of tidal flushing in the harbour. In the sediment cores, the highest concentrations of trace metals were observed to have accumulated during the 1950s-1980s, corresponding with the period of rapid urban and industrial development in Hong Kong. From the late 1980s, there has been a major decline in the concentrations of trace metals, due to a reduction in industrial activities and to the enactment of wastewater pollution controls in the territory. The Pb isotopic compositions of the sediments revealed the anthropogenic inputs of Pb to the harbour. The 206 Pb/ 207 Pb ratios varied from 1.154 to 1.190, which were lower than those of background geological materials in Hong Kong ( 206 Pb/ 207 Pb: 1.201-1.279). The data also indicated that the Pb in the harbour sediments most likely originated from mixed sources, including the leaded gasoline used in the past and other anthropogenic sources

  8. Distribution and transfer of trace metals in the Aegean Seawater (Eastern Mediterranean Basin

    Directory of Open Access Journals (Sweden)

    F. VOUTSINOU-TALIADOURI

    2000-12-01

    Full Text Available Recent measurements of dissolved Cd, Cu, Ni and Mn in 324 water samples of the Aegean Sea fill the gap of missing knowledge in this part of the Eastern Mediterranean and try to identify their main input sources and spreading pathways. The analyses indicate that trace metal concentrations in the North and South Aegean Sea are generally in good agreement with those reported for the Western Mediterranean Sea. In the North Aegean Sea the trace metal distribution patterns differentiate mainly according to the existing water masses. Hence, a strong influence of the Black Sea Water, enriched in trace metals, is clearly recorded for Mn. Concentrations of this metal are one order of magnitude higher in the surface layer than those of the deeper waters. This feature is followed to a lesser degree also by Cd, Cu and Ni. Trace metal concentrations in the South Aegean Sea reveal almost constant values throughout the watercolumn similar to those observed in the North Aegean Sea below the depth of 100 m. Manganese values in the South Aegean Sea are considerably lower comparing with the North Aegean ones, showing relatively enhanced surface values which decrease with depth.

  9. Distribution of heavy metals and environmental assessment of surface sediment of typical estuaries in eastern China.

    Science.gov (United States)

    Bi, Shipu; Yang, Yuan; Xu, Chengfen; Zhang, Yong; Zhang, Xiaobo; Zhang, Xianrong

    2017-08-15

    Estuary sediment is a major pollutant enrichment medium and is an important biological habitat. This sediment has attracted the attention of the marine environmental scientists because it is a more stable and effective medium than water for monitoring regional environmental quality conditions and trends. Based on a large amount of measurement data, we analyzed the concentrations, distribution, and sources of seven heavy metals (As, Cd, Cr, Cu, Hg, Pb, and Zn) in the surface sediment of typical estuaries that empty into the sea in eastern China: the Liaohe River Estuary, Yellow River Estuary, Yangtze River Estuary, Minjiang River Estuary, and Pearl River Estuary. The heavy metal concentrations in the sediments vary considerably from one estuary to the next. The Liaohe River Estuary sediment contains elevated levels of Cd, Hg, and Zn. The Yellow River Estuary sediment contains elevated levels of As. The sediments in the Yangtze River and Minjiang River estuaries contain elevated levels of Cd and Cu and of Pb and Zn, respectively. The sediment in the Pearl River Estuary contains elevated levels of all seven heavy metals. We used the Nemerow index method to assess the environment quality. The heavy metal pollution in the Liaohe River and Pearl River estuaries is more severe than that in the other estuaries. Additional work indicates that the heavy metal pollution in the Liaohe River and Pearl River estuaries is caused mainly by human activity. Copyright © 2017. Published by Elsevier Ltd.

  10. Heavy metals concentration and distribution in soils and vegetation at Korle Lagoon area in Accra, Ghana

    DEFF Research Database (Denmark)

    Fosu-Mensah, Benedicta Yayra; Addae, Emmanuel; Yirenya-Tawiah, Dzidzo

    2017-01-01

    The call for reclamation of land around Korle Lagoon in Accra, Ghana, where burning of E-waste and cultivation of vegetables takes place, make risk assessment of heavy metal contaminations important. This study aimed at evaluating the levels and risk of heavy metal contamination in soils and vege......The call for reclamation of land around Korle Lagoon in Accra, Ghana, where burning of E-waste and cultivation of vegetables takes place, make risk assessment of heavy metal contaminations important. This study aimed at evaluating the levels and risk of heavy metal contamination in soils...... and vegetation around the Korle lagoon area in Accra. Geoaccumulation index, enrichment factor and pollution load index were determined to assess the risk of contamination. The levels and distribution of nine heavy metals (Pb, Hg, Cd, As, Zn, Sn, Ni, Cu and Cr) in soil (0 – 20 cm) and common vegetation (Panicum...... maximum, Imperata cylindrica, Lactuca sativa and Hibiscus sabdariffa) from the area using Atomic Absorption Spectrometer (AAS) were assessed. The area was divided into five sites namely; the e-waste site (S1), gardens area (S2), recreational area (S3), reclaimed area (S4) estuary (S5), and the control (S6...

  11. Distribution and Analysis of Heavy Metals Contamination in Soil, Perlis, Malaysia

    Science.gov (United States)

    Nihla Kamarudzaman, Ain; Woo, Yee Shan; Jalil, Mohd Faizal Ab

    2018-03-01

    The concentration of six heavy metals such as Cu, Cr, Ni, Cd, Zn and Mn were studied in the soils around Perlis. The aim of the study is to assess the heavy metals contamination distribution due to industrialisation and agricultural activities. Soil samples were collected at depth of 0 - 15 cm in five stations around Perlis. The soil samples are subjected to soil extraction and the concentration of heavy metals was determined via ICP - OES. Overall concentrations of Cr, Cu, Zn, Ni, Cd and Mn in the soil samples ranged from 0.003 - 0.235 mg/L, 0.08 - 41.187 mg/L, 0.065 - 45.395 mg/L, 0.031 - 2.198 mg/L, 0.01 - 0.174 mg/L and 0.165 - 63.789 mg/L respectively. The concentration of heavy metals in the soil showed the following decreasing trend, Mn > Zn > Cu > Ni > Cr > Cd. From the result, the level of heavy metals in the soil near centralised Chuping industrial areas gives maximum value compared to other locations in Perlis. As a conclusion, increasing anthropogenic activities have influenced the environment, especially in increasing the pollution loading.

  12. Luminescent metal nanoclusters: controlled synthesis and functional applications

    Directory of Open Access Journals (Sweden)

    Hong-Tao Sun

    2014-04-01

    Full Text Available Luminescent metal nanoclusters that consist of only several, to tens of, metal atoms and which possess sizes comparable to the Fermi wavelength of electrons have recently attracted significant attention. This new class of luminescent materials not only provides the missing link between atomic and nanoparticle behaviors in metals but also they present abundant novel information for the development of new applicable material systems to meet urgent needs in many areas (such as ultrasensitive sensors for heavy metals, bioimaging, as well as information technology mainly because of their attractive characteristics, including ultra-small size, good dispersibility, excellent biocompatibility and photostability. In this review, we summarize recent advances in the controlled synthesis and application of luminescent metal nanoclusters, with a particular emphasis on Pt, Mo, Bi and alloy clusters. We also speculate on their future and discuss potential developments for their use in sensors, bioimaging and energy harvesting and conversion.

  13. Luminescent metal nanoclusters: controlled synthesis and functional applications

    Science.gov (United States)

    Sun, Hong-Tao; Sakka, Yoshio

    2014-02-01

    Luminescent metal nanoclusters that consist of only several, to tens of, metal atoms and which possess sizes comparable to the Fermi wavelength of electrons have recently attracted significant attention. This new class of luminescent materials not only provides the missing link between atomic and nanoparticle behaviors in metals but also they present abundant novel information for the development of new applicable material systems to meet urgent needs in many areas (such as ultrasensitive sensors for heavy metals, bioimaging, as well as information technology) mainly because of their attractive characteristics, including ultra-small size, good dispersibility, excellent biocompatibility and photostability. In this review, we summarize recent advances in the controlled synthesis and application of luminescent metal nanoclusters, with a particular emphasis on Pt, Mo, Bi and alloy clusters. We also speculate on their future and discuss potential developments for their use in sensors, bioimaging and energy harvesting and conversion.

  14. Microbial community composition and functions are resilient to metal pollution along two forest soil gradients.

    NARCIS (Netherlands)

    Azarbad, H.; Niklinska, M.; Laskowski, R.; van Straalen, N.M.; van Gestel, C.A.M.; Zhou, J.; He, Z.; Wen, C.; Roling, W.F.M.

    2015-01-01

    Despite the global importance of forests, it is virtually unknown how their soil microbial communities adapt at the phylogenetic and functional level to long-term metal pollution. Studying 12 sites located along two distinct gradients of metal pollution in Southern Poland revealed that functional

  15. Melatonin membrane receptors in peripheral tissues: Distribution and functions

    Science.gov (United States)

    Slominski, Radomir M.; Reiter, Russel J.; Schlabritz-Loutsevitch, Natalia; Ostrom, Rennolds S.; Slominski, Andrzej T.

    2012-01-01

    Many of melatonin’s actions are mediated through interaction with the G-protein coupled membrane bound melatonin receptors type 1 and type 2 (MT1 and MT2, respectively) or, indirectly with nuclear orphan receptors from the RORα/RZR family. Melatonin also binds to the quinone reductase II enzyme, previously defined the MT3 receptor. Melatonin receptors are widely distributed in the body; herein we summarize their expression and actions in non-neural tissues. Several controversies still exist regarding, for example, whether melatonin binds the RORα/RZR family. Studies of the peripheral distribution of melatonin receptors are important since they are attractive targets for immunomodulation, regulation of endocrine, reproductive and cardiovascular functions, modulation of skin pigmentation, hair growth, cancerogenesis, and aging. Melatonin receptor agonists and antagonists have an exciting future since they could define multiple mechanisms by which melatonin modulates the complexity of such a wide variety of physiological and pathological processes. PMID:22245784

  16. Microbial community composition and functions are resilient to metal pollution along two forest soil gradients.

    Science.gov (United States)

    Azarbad, Hamed; Niklińska, Maria; Laskowski, Ryszard; van Straalen, Nico M; van Gestel, Cornelis A M; Zhou, Jizhong; He, Zhili; Wen, Chongqing; Röling, Wilfred F M

    2015-01-01

    Despite the global importance of forests, it is virtually unknown how their soil microbial communities adapt at the phylogenetic and functional level to long-term metal pollution. Studying 12 sites located along two distinct gradients of metal pollution in Southern Poland revealed that functional potential and diversity (assessed using GeoChip 4.2) were highly similar across the gradients despite drastically diverging metal contamination levels. Metal pollution level did, however, significantly impact bacterial community structure (as shown by MiSeq Illumina sequencing of 16S rRNA genes), but not bacterial taxon richness and community composition. Metal pollution caused changes in the relative abundance of specific bacterial taxa, including Acidobacteria, Actinobacteria, Bacteroidetes, Chloroflexi, Firmicutes, Planctomycetes and Proteobacteria. Also, a group of metal-resistance genes showed significant correlations with metal concentrations in soil. Our study showed that microbial communities are resilient to metal pollution; despite differences in community structure, no clear impact of metal pollution levels on overall functional diversity was observed. While screens of phylogenetic marker genes, such as 16S rRNA genes, provide only limited insight into resilience mechanisms, analysis of specific functional genes, e.g. involved in metal resistance, appears to be a more promising strategy. © FEMS 2014. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  17. The influence of silica functionalized with silanes on migration of heavy metals in soil

    Directory of Open Access Journals (Sweden)

    Grzesiak Piotr

    2016-03-01

    Full Text Available 3-Mercaptopropyl-trimethoxysilane and [3-(2-aminoethylaminopropyl]trimethoxysilane were used to functionalize the surface of silica from Piotrowice in Poland to stabilize heavy metals (HMs and arsenic in soil. The soil for the study was sampled from the impact zone of Głogów Copper Smelter and Refinery. The soil samples were exposed to five-step Tessier sequential extraction. The speciation studies were limited to five sequentially defined fractions in which metal content was determined. The addition of unmodified silica did not affect significantly the concentration of metals in individual fractions. Significant changes were noted upon introduction of functionalized silica in the soil. The hybrid formulations obtained significantly reduce the release of heavy metals and arsenic from soil sorption complex. The results indicate the potential use of functional formulations for reduction of metal migration in soil in the areas of exceeded concentration of heavy metals and arsenic in the soil, caused by industrial activity.

  18. Synchrotron X-ray microfluorescence measurement of metal distributions in Phragmites australis root system in the Yangtze River intertidal zone

    Energy Technology Data Exchange (ETDEWEB)

    Feng, Huan; Zhang, Weiguo; Qian, Yu; Liu, Wenliang; Yu, Lizhong; Yoo, Shinjae; Wang, Jun; Wang, Jia-Jun; Eng, Christopher; Liu, Chang-Jun; Tappero, Ryan

    2016-06-15

    This study investigates the distributions of Br, Ca, Cl, Cr, Cu, K, Fe, Mn, Pb, Ti, V and Zn inPhragmites australisroot system and the function of Fe nanoparticles in scavenging metals in the root epidermis using synchrotron X-ray microfluorescence, synchrotron transmission X-ray microscope measurement and synchrotron X-ray absorption near-edge structure techniques. The purpose of this study is to understand the mobility of metals in wetland plant root systems after their uptake from rhizosphere soils.Phragmites australissamples were collected in the Yangtze River intertidal zone in July 2013. The results indicate that Fe nanoparticles are present in the root epidermis and that other metals correlate significantly with Fe, suggesting that Fe nanoparticles play an important role in metal scavenging in the epidermis.

  19. Spatial Distribution and Mobility Assessment of Carcinogenic Heavy Metals in Soil Profiles Using Geostatistics and Random Forest, Boruta Algorithm

    Directory of Open Access Journals (Sweden)

    Asma Shaheen

    2018-03-01

    Full Text Available In third world countries, industries mainly cause environmental contamination due to lack of environmental policies or oversight during their implementation. The Sheikhupura industrial zone, which includes industries such as tanneries, leather, chemical, textiles, and colour and dyes, contributes massive amounts of untreated effluents that are released directly into drains and used for the irrigation of crops and vegetables. This practice causes not only soil contamination with an excessive amount of heavy metals, but is also considered a source of toxicity in the food chain, i.e., bioaccumulation in plants and ultimately in human body organs. The objective of this research study was to assess the spatial distribution of the heavy metals chromium (Cr, cadmium (Cd, and lead (Pb, at three depths of soil using geostatistics and the selection of significant contributing variables to soil contamination using the Random Forest (RF function of the Boruta Algorithm. A total of 60 sampling locations were selected in the study area to collect soil samples (180 samples at three depths (0–15 cm, 15–30 cm, and 60–90 cm. The soil samples were analysed for their physico-chemical properties, i.e., soil saturation, electrical conductivity (EC, organic matter (OM, pH, phosphorus (P, potassium (K, and Cr, Cd, and Pb using standard laboratory procedures. The data were analysed with comprehensive statistics and geostatistical techniques. The correlation coefficient matrix between the heavy metals and the physico-chemical properties revealed that electrical conductivity (EC had a significant (p ≤ 0.05 negative correlation with Cr, Cd, and Pb. The RF function of the Boruta Algorithm employed soil depth as a classifier and ranked the significant soil contamination parameters (Cr, Cd, Pb, EC, and P in relation to depth. The mobility factor indicated the leachate percentage of heavy metals at different vertical depths of soil. The spatial distribution pattern of

  20. High-resolution insight into the competitive adsorption of heavy metals on natural sediment by site energy distribution.

    Science.gov (United States)

    Huang, Limin; Jin, Qiang; Tandon, Puja; Li, Aimin; Shan, Aidang; Du, Jiajie

    2018-04-01

    Investigating competitive adsorption on river/lake sediments is valuable for understanding the fate and transport of heavy metals. Most studies have studied the adsorption isotherms of competitive heavy metals, which mainly comparing the adsorption information on the same concentration. However, intrinsically, the concentration of each heavy metal on competitive adsorption sites is different, while the adsorption energy is identical. Thus, this paper introduced the site energy distribution theory to increase insight into the competitive adsorption of heavy metals (Cu, Cd and Zn). The site energy distributions of each metal with and without other coexisting heavy metals were obtained. It illustrated that site energy distributions provide much more information than adsorption isotherms through screening of the full energy range. The results showed the superior heavy metal in each site energy area and the influence of competitive metals on the site energy distribution of target heavy metal. Site energy distributions can further help in determining the competitive sites and ratios of coexisting metals. In particular, in the high-energy area, which has great environmental significance, the ratios of heavy metals in the competitive adsorption sites obtained for various competitive systems were as follows: slightly more than 3:1 (Cu-Cd), slightly less than 3:1 (Cu-Zn), slightly more than 1:1 (Cd-Zn), and nearly 7:2:2 (Cu-Cd-Zn). The results from this study are helpful to deeply understand competitive adsorption of heavy metals (Cu, Cd, Zn) on sediment. Therefore, this study was effective in presenting a general pattern for future reference in competitive adsorption studies on sediments. Copyright © 2018 Elsevier Ltd. All rights reserved.

  1. Transverse momentum dependent (TMD) parton distribution functions. Status and prospects

    International Nuclear Information System (INIS)

    Angeles-Martinez, R.; Bacchetta, A.; Pavia Univ.; Balitsky, I.I.

    2015-07-01

    We provide a concise overview on transverse momentum dependent (TMD) parton distribution functions, their application to topical issues in high-energy physics phenomenology, and their theoretical connections with QCD resummation, evolution and factorization theorems. We illustrate the use of TMDs via examples of multi-scale problems in hadronic collisions. These include transverse momentum q T spectra of Higgs and vector bosons for low q T , and azimuthal correlations in the production of multiple jets associated with heavy bosons at large jet masses. We discuss computational tools for TMDs, and present an application of a new tool, TMDlib, to parton density fits and parameterizations.

  2. Unbiased Polarised Parton Distribution Functions and their Uncertainties

    CERN Document Server

    Nocera, Emanuele R.; Ridolfi, Giovanni; Rojo, Juan

    2012-01-01

    We present preliminary results on the determination of spin-dependent, or polarised, Parton Distribution Functions (PDFs) from all relevant inclusive polarised DIS data. The analysis is performed within the NNPDF approach, which provides a faithful and statistically sound representation of PDFs and their uncertainties. We describe how the NNPDF methodology has been extended to the polarised case, and compare our results with other recent polarised parton sets. We show that polarised PDF uncertainties can be sizeably underestimated in standard determinations, most notably for the gluon.

  3. METHODS FOR ESTIMATING THE PARAMETERS OF THE POWER FUNCTION DISTRIBUTION.

    Directory of Open Access Journals (Sweden)

    azam zaka

    2013-10-01

    Full Text Available Normal 0 false false false EN-US X-NONE X-NONE In this paper, we present some methods for estimating the parameters of the two parameter Power function distribution. We used the least squares method (LSM, relative least squares method (RELS and ridge regression method (RR. Sampling behavior of the estimates is indicated by a Monte Carlo simulation. The objective of identifying the best estimator amongst them we use the Total Deviation (T.D and Mean Square Error (M.S.E as performance index. We determined the best method for estimation using different values for the parameters and different sample sizes.

  4. CONTROL OF METAL SURFACES MACHINED IN ACCORDANCE WITH THE DIAMOND NANOMACHINING TECHNOLOGY BASED ON THE ELECTRON WORK FUNCTION

    Directory of Open Access Journals (Sweden)

    G. V. Sharonov

    2015-01-01

    Full Text Available Dimensional machining technology is based on the use of integrated geometric parameters of machined surfaces. Technological impact of a pick results in oxidation processes and changes in physic-chemical parameters of surface. Control of only geometric parameters is insufficient to describe characteristics of machining and formation of ultra-smooth surfaces. The electron work function is therefore used. The aim of the work was to study electrophysical states of optic surfaces of non-ferrous metals and alloys in relation to geometric and physic-chemical parameters according to the distribution of the electron work function over the surface. We conducted the study on experimental metal samples made of copper and aluminum alloy, machined in accordance with the diamond nanomachining technology. The diamond nanomachining technology would be capable of ensuring the roughness of non-ferrous metals and alloys machined at the level of Ra ≤ 0,005 µm. Modernized Kelvin probe was used as the registration technique of the changes of the electron work function over the surface. Dependence between the electron work function value, as well as its alteration and the physicchemical and geometric parameters of a surface has been determined. It has been shown that the diamond nanomachining technology makes it possible to obtain electro-physically uniform optical surfaces on copper and aluminum alloy with the minimal range of the distribution of the electric potential over the surface. 

  5. DNA breathing dynamics: analytic results for distribution functions of relevant Brownian functionals.

    Science.gov (United States)

    Bandyopadhyay, Malay; Gupta, Shamik; Segal, Dvira

    2011-03-01

    We investigate DNA breathing dynamics by suggesting and examining several Brownian functionals associated with bubble lifetime and reactivity. Bubble dynamics is described as an overdamped random walk in the number of broken base pairs. The walk takes place on the Poland-Scheraga free-energy landscape. We suggest several probability distribution functions that characterize the breathing process, and adopt the recently studied backward Fokker-Planck method and the path decomposition method as elegant and flexible tools for deriving these distributions. In particular, for a bubble of an initial size x₀, we derive analytical expressions for (i) the distribution P(t{f}|x₀) of the first-passage time t{f}, characterizing the bubble lifetime, (ii) the distribution P(A|x₀) of the area A until the first-passage time, providing information about the effective reactivity of the bubble to processes within the DNA, (iii) the distribution P(M) of the maximum bubble size M attained before the first-passage time, and (iv) the joint probability distribution P(M,t{m}) of the maximum bubble size M and the time t{m} of its occurrence before the first-passage time. These distributions are analyzed in the limit of small and large bubble sizes. We supplement our analytical predictions with direct numericalsimulations of the related Langevin equation, and obtain a very good agreement in the appropriate limits. The nontrivial scaling behavior of the various quantities analyzed here can, in principle, be explored experimentally.

  6. Spatial distribution and potential sources of trace metals in insoluble particles of snow from Urumqi, China.

    Science.gov (United States)

    Li, Xiaolan; Jiang, Fengqing; Wang, Shaoping; Turdi, Muyesser; Zhang, Zhaoyong

    2015-01-01

    The purpose of this work is to characterize trace elements in snow in urban-suburb gradient over Urumqi city, China. The spatial distribution patterns of 11 trace metals in insoluble particulate matters of snow were revealed by using 102 snow samples collected in and around urban areas of Urumqi, a city suffering from severe wintertime air pollution in China. Similar spatial distribution for Mn, Cu, Zn, Ni, and Pb was found and their two significant high-value areas located in the west and east, respectively, and a high-value area in the south, which were correlated with factory emissions, traffic activities, and construction fugitive dust. The high-value areas of Cr, Ni, and V occurred in the northeast corner and along main traffic paths, which were linked to oil refinery and vehicular emissions. High value of Be presented in the west of the city. The high-value area of Co in the northeast could be related to local soil. Cd and U displayed relatively even spatial patterns in the urban area. In view of distance from the urban center, e.g., from the first circular belt to the fourth circular belt, except Be, V, Cd, and U, the contents of other metals generally decreased from the first circular belt to the forth circular belt, implying the effect of human activity clearly. Additionally, prevailing northwesterly winds and occasionally southeasterly winds in winter were associated with decreased, generally, concentrations of trace metal in snow from the urban center to the southern suburb along a northwest and southeast transect. The information on concentrations and spatial distributions of these metals in insoluble particles of snow in winter will be valuable for further environmental protection and planning.

  7. Partial Discharge Monitoring on Metal-Enclosed Switchgear with Distributed Non-Contact Sensors

    Directory of Open Access Journals (Sweden)

    Chongxing Zhang

    2018-02-01

    Full Text Available Metal-enclosed switchgear, which are widely used in the distribution of electrical energy, play an important role in power distribution networks. Their safe operation is directly related to the reliability of power system as well as the power quality on the consumer side. Partial discharge detection is an effective way to identify potential faults and can be utilized for insulation diagnosis of metal-enclosed switchgear. The transient earth voltage method, an effective non-intrusive method, has substantial engineering application value for estimating the insulation condition of switchgear. However, the practical application effectiveness of TEV detection is not satisfactory because of the lack of a TEV detection application method, i.e., a method with sufficient technical cognition and analysis. This paper proposes an innovative online PD detection system and a corresponding application strategy based on an intelligent feedback distributed TEV wireless sensor network, consisting of sensing, communication, and diagnosis layers. In the proposed system, the TEV signal or status data are wirelessly transmitted to the terminal following low-energy signal preprocessing and acquisition by TEV sensors. Then, a central server analyzes the correlation of the uploaded data and gives a fault warning level according to the quantity, trend, parallel analysis, and phase resolved partial discharge pattern recognition. In this way, a TEV detection system and strategy with distributed acquisition, unitized fault warning, and centralized diagnosis is realized. The proposed system has positive significance for reducing the fault rate of medium voltage switchgear and improving its operation and maintenance level.

  8. The spatial thickness distribution of metal films produced by large area pulsed laser deposition

    International Nuclear Information System (INIS)

    Pryds, Nini; Schou, Jorgen; Linderoth, Soren

    2007-01-01

    Thin films of metals have been deposited in the large-area Pulsed Laser Deposition (PLD) Facility at Riso National Laboratory. Thin films of Ag and Ni were deposited with laser pulses from an excimer laser at 248 nm with a rectangular beam spot at a fluence of 10 J/cm 2 on glass substrates of 127 mm diameter positioned 80 mm from the target in vacuum. We have explored the distribution of deposited material on a stationary substrate from a fixed point of impact on the target relative to the substrate. In all cases the angular distribution of the deposited metal layers shows a distinct 'flip-over' of the plume. The thickness of the deposited films over the full area has been determined by energy-dispersive X-ray spectrometry in a scanning electron microscope (SEM). The measured distributions were then compared with analytical expressions. Finally, the angular distribution of the film thickness has been utilized in an algorithm for production of films over large areas

  9. Surface/structure functionalization of copper-based catalysts by metal-support and/or metal-metal interactions

    Science.gov (United States)

    Konsolakis, Michalis; Ioakeimidis, Zisis

    2014-11-01

    Cu-based catalysts have recently attracted great attention both in catalysis and electro-catalysis fields due to their excellent catalytic performance and low cost. Given that their performance is determined, to a great extent, by Cu sites local environment, considerable efforts have been devoted on the strategic modifications of the electronic and structural properties of Cu sites. In this regard, the feasibility of tuning the local structure of Cu entities by means of metal-support or metal-metal interactions is investigated. More specifically, the physicochemical properties of Cu entities are modified by employing: (i) different oxides (CeO2, La2O3, Sm2O3), or (ii) ceria-based mixed oxides (Ce1-xSmxOδ) as supporting carriers, and (iii) a second metal (Cobalt) adjacent to Cu (bimetallic Cu-Co/CeO2). A characterization study, involving BET, XRD, TPR, and XPS, reveal that significant modifications on structural, redox and electronic properties of Cu sites can be induced by adopting either different oxide carriers or bimetallic complexes. Fundamental insights into the tuning of Cu local environment by metal-support or metal-metal interactions are provided, paving the way for real-life industrial applications.

  10. Memory intensive functional architecture for distributed computer control systems

    International Nuclear Information System (INIS)

    Dimmler, D.G.

    1983-10-01

    A memory-intensive functional architectue for distributed data-acquisition, monitoring, and control systems with large numbers of nodes has been conceptually developed and applied in several large-scale and some smaller systems. This discussion concentrates on: (1) the basic architecture; (2) recent expansions of the architecture which now become feasible in view of the rapidly developing component technologies in microprocessors and functional large-scale integration circuits; and (3) implementation of some key hardware and software structures and one system implementation which is a system for performing control and data acquisition of a neutron spectrometer at the Brookhaven High Flux Beam Reactor. The spectrometer is equipped with a large-area position-sensitive neutron detector

  11. Nonlocal adiabatic theory. I. The action distribution function

    Science.gov (United States)

    Bénisti, Didier

    2017-09-01

    In this paper, we address the motion of charged particles acted upon by a sinusoidal electrostatic wave, whose amplitude and phase velocity vary slowly enough in time for neo-adiabatic theory to apply. Moreover, we restrict to the situation when only few separatrix crossings have occurred, so that the adiabatic invariant, I , remains nearly constant. We insist here on the fact that I is different from the dynamical action, I. In particular, we show that I depends on the whole time history of the wave variations, while the action is usually defined as a local function of the wave amplitude and phase velocity. Moreover, we provide several numerical results showing how the action distribution function, f(I), varies with time, and we explain how to derive it analytically. The derivation is then generalized to the situation when the wave is weakly inhomogeneous.

  12. Metal concentrations and distribution in paint waste generated during bridge rehabilitation in New York State.

    Science.gov (United States)

    Shu, Zhan; Axe, Lisa; Jahan, Kauser; Ramanujachary, Kandalam V; Kochersberger, Carl

    2015-09-01

    Between 1950 and 1980, lead and chromium along with other metals have been used in paint coatings to protect bridges from corrosion. In New York State with 4500 bridges in 11 Regions 2385 of the bridges have been rehabilitated and subsequently repainted after 1989 when commercial use of lead based paint was prohibited. The purpose of this research was to address the concentration and distribution of trace metals in the paint waste generated during bridge rehabilitation. Using hypothesis testing and stratified sampling theory, a representative sample size of 24 bridges from across the state was selected that resulted in 117 paint waste samples. Field portable X-ray fluorescence (FP-XRF) analysis revealed metal concentrations ranged from 5 to 168,090 mg kg(-1) for Pb, 49,367 to 799,210 mg kg(-1) for Fe, and 27 to 425,510 mg kg(-1) for Zn. Eighty percent of the samples exhibited lead concentrations greater than 5000 mg kg(-1). The elevated iron concentrations may be attributed to the application of steel grit as an abrasive blasting material routinely used by state Departments of Transportation in the paint removal process. Other metals including Ba and Cr were observed in the paint waste as well. As a result of the paint formulation, metals were found to be associated in the paint waste (Pb correlated with Cr (r=0.85)). The elevated metal concentrations observed raises concern over the potential impact of leaching from this waste stream. Copyright © 2015 Elsevier B.V. All rights reserved.

  13. [Heavy metal distribution in superficial sedimenta ta Saco, Gulf of Cariaco, Sucre, Venezuela].

    Science.gov (United States)

    Valentina Fuentes, María; Rojas de Astudillo, Luisa; Diaz, Alfredo; Martínez, Gregorio

    2010-10-01

    The Gulf of Cariaco is a marine ecosystem with high primary productivity, which gives it an ecological and socioeconomic importance. Nevertheless, anthropogenic activities around the Gulf produce wastes that are deposited directly or by runoff into the sediments, and consequently, increases concentrations of metals in this ecosystem. The objective of this study was to determine the distribution of cadmium, copper, lead, manganese, nickel and zinc in geochemical fractions of surface sediments, using modified BCR sequential extraction procedure. The concentrations were measured using flame atomic absorption spectroscopy. In addition, the contents of soluble and exchangeable metals associated to carbonate fractions, determined by BCR, were compared with those determined by the method of Campanella. Samples were collected in 12 stations during June 2007. The applied methodologies were evaluated with a certified reference material of marine sediments (HISS-1) and the results indicated that these methods provide adequate accuracy and precision for the extraction of metals. The total metal concentrations (microg g(-1)) were, Cd: < limit of detection (LD)-5.0; Pb: 1.79-60.41; Cu: no detected (ND)-42.18; Zn: 25.13-104.57; Mn: 66.31-80.29 and Ni: 3.29-24.58. Cd, Cu, Ni and Pb at several stations, exceeded the Canadian Sediment Quality Guidelines of the Lowest Effect Levels (LEL). Cadmium was identified as being the most mobile of the elements, having the highest concentrations in soluble and exchangeable cations and carbonates. However, Pb, Cu, Mn and Zn levels were found highly associated to organic matter and sulfide fractions. The methods did not show significant statistical differences for the extraction of soluble and exchangeable cations and the metals associated to carbonate fraction. There are several significant correlations between heavy metals, which suggest their common origin.

  14. Correlation functions between specific volume and stoichiometry for transition metal nitrides

    International Nuclear Information System (INIS)

    Soto, G.; Aparicio, E.; Avalos-Borja, M.

    2005-01-01

    A methodology is proposed to correlate the structural aspects of transition metal nitrides (TMN) to the stoichiometric ratio: x = [N]/[M]. The method is based on a numeric figure, υ, given by the difference between the atomic concentrations of nitride and parent metal normalized to the atomic concentration of parent metal. Numerical regression is used to construct interpolating functions for υ(x) using as input the available data for TMN in two well-recognized databases (ICDD and ICSD). In summary we obtain functions of x that describe the deformation caused in the parent metal lattice by the nitrogen assimilation. The results are attractive, since TMN show remarkable trends

  15. Adsorptive Removal of Metal Ions from Water using Functionalized Biomaterials.

    Science.gov (United States)

    Deshpande, Kanchanmala

    2017-01-01

    Synthesis and modification of cost-effective sorbents for removing heavy metals from water resources is an area of significance. It had been reported that materials with biological origins, such as agricultural and animal waste, are excellent alternatives to conventional adsorbents due to their higher affinity, capacity and selectivity towards metal ions. These properties of biomaterials help to reduce or detoxify metal ions concentration in contaminated water to acceptable regulatory standards. Synthesis of novel, efficient, cost effective, eco-friendly biomaterials for heavy metal adsorption from water is still an area of challenge. In this comprehensive review, acompilation of patents as well as published articles is carried out to outline the properties of different biomaterials based on their precursors along withdetailed description of biomaterial morphology and various surface modification approaches. A detailed study of the performance of adsorbents and the role of physical and chemical modification in terms of enhancing their potential for metal adsorption from water is compiled here. The factors affecting adsorption behavior i.e., capacity and affinity of e biomaterials is also compiled. This paper presents a concise review of reported studies on the synthesis and modification of biomaterials, their use for heavy metal removal from waters and future prospects of this technology. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

  16. Versatile Surface Functionalization of Metal-Organic Frameworks through Direct Metal Coordination with a Phenolic Lipid Enables Diverse Applications

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Wei [Univ. of New Mexico, Albuquerque, NM (United States); Xiang, Guolei [Univ. of Cambridge (United Kingdom); Shang, Jin [Univ. of Hong Kong (China); Guo, Jimin [Univ. of New Mexico, Albuquerque, NM (United States); Motevalli, Benyamin [Monash Univ., Clayton, VIC (Australia); Durfee, Paul [Univ. of New Mexico, Albuquerque, NM (United States); Agola, Jacob Ongudi [Univ. of New Mexico, Albuquerque, NM (United States); Coker, Eric N. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Brinker, C. Jeffrey [Univ. of New Mexico, Albuquerque, NM (United States); Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2018-02-22

    Here, a novel strategy for the versatile functionalization of the external surface of metal-organic frameworks (MOFs) has been developed based on the direct coordination of a phenolic-inspired lipid molecule DPGG (1,2-dipalmitoyl-sn-glycero-3-galloyl) with metal nodes/sites surrounding MOF surface. X-ray diffraction and Argon sorption analysis prove that the modified MOF particles retain their structural integrity and porosity after surface modification. Density functional theory calculations reveal that strong chelation strength between the metal sites and the galloyl head group of DPGG is the basic prerequisite for successful coating. Due to the pH-responsive nature of metal-phenol complexation, the modification process is reversible by simple washing in weak acidic water, showing an excellent regeneration ability for water-stable MOFs. Moreover, the colloidal stability of the modified MOFs in the nonpolar solvent allows them to be further organized into 2 dimensional MOF or MOF/polymer monolayers by evaporation-induced interfacial assembly conducted on an air/water interface. Lastly, the easy fusion of a second functional layer onto DPGG-modified MOF cores, enabled a series of MOF-based functional nanoarchitectures, such as MOFs encapsulated within hybrid supported lipid bilayers (so-called protocells), polyhedral core-shell structures, hybrid lipid-modified-plasmonic vesicles and multicomponent supraparticles with target functionalities, to be generated. for a wide range of applications.

  17. Assessment of factors related to heavy metals distribution in abandoned mining soils in Madrid, central Spain

    Science.gov (United States)

    Torres, Manuel; Carral, Pilar; Alvarez, Ana M.; Hernández, Zulimar; Lorena, Recio-Vázquez; Marques, Maria J.; Almendros, Gonzalo

    2013-04-01

    Exploitation of metallic mineral deposits and its subsequent abandonment in last decades has lead to significant environmental hazard for natural systems. The present study concerns the distribution and mobility of heavy metals and trace elements mainly As, Cu, Cd, Co, Mn and V, in sulphide-rich soils. The site studied (Sierra de Guadarrama, Garganta de los Montes, Madrid) is at 1200 m asl. Soils are Humic and Dystric Cambisols (WRB) developed on gneisses; the main minerals consist of sulphides and include chalcopyrite, pyrite, marcasite, galena and arsenopyrite. Concentration data of the different species of heavy metals as dependent variables in addition to a series of independent variables mainly soil organic matter were subjected to multivariate chemometric treatments including multidimensional scaling (MDS), principal component analysis (PCA) and support vector machine (SVM) for a preliminary survey on the possible role of soil organic matter in the distribution and speciation of heavy metals in soils. The soil heavy metals speciation was determined using the BCR (Community Bureau of Reference, European Commission) sequential extraction procedure and analysed by ICP-MS. The total contents of these elements were calculated as the sum of the four BCR fractions. The results showed element concentrations decreasing with the distance from the source of pollution. The highest amounts of As and Mn, and Cu, Cd, Co and V were found at 10 and 100 m respectively. These values exceed the allowed limits of the environmental regulation. The percentages of extractable elements (step one of BCR) in relation to total elements show that Cu and Cd were significantly more easily extractable than the other elements. Metal availability in soils was generally controlled by total metal concentration. Data processing techniques coincided in pointing out the association of high levels of organic matter with the concentrations of elements extracted just in the most available forms: i

  18. A Noninformative Prior on a Space of Distribution Functions

    Directory of Open Access Journals (Sweden)

    Alexander Terenin

    2017-07-01

    Full Text Available In a given problem, the Bayesian statistical paradigm requires the specification of a prior distribution that quantifies relevant information about the unknowns of main interest external to the data. In cases where little such information is available, the problem under study may possess an invariance under a transformation group that encodes a lack of information, leading to a unique prior—this idea was explored at length by E.T. Jaynes. Previous successful examples have included location-scale invariance under linear transformation, multiplicative invariance of the rate at which events in a counting process are observed, and the derivation of the Haldane prior for a Bernoulli success probability. In this paper we show that this method can be extended, by generalizing Jaynes, in two ways: (1 to yield families of approximately invariant priors; and (2 to the infinite-dimensional setting, yielding families of priors on spaces of distribution functions. Our results can be used to describe conditions under which a particular Dirichlet Process posterior arises from an optimal Bayesian analysis, in the sense that invariances in the prior and likelihood lead to one and only one posterior distribution.

  19. Lattice QCD exploration of parton pseudo-distribution functions

    Science.gov (United States)

    Orginos, Kostas; Radyushkin, Anatoly; Karpie, Joseph; Zafeiropoulos, Savvas

    2017-11-01

    We demonstrate a new method of extracting parton distributions from lattice calculations. The starting idea is to treat the generic equal-time matrix element M (P z3,z32) as a function of the Ioffe time ν =P z3 and the distance z3. The next step is to divide M (P z3,z32) by the rest-frame density M (0 ,z32). Our lattice calculation shows a linear exponential z3-dependence in the rest-frame function, expected from the Z (z32) factor generated by the gauge link. Still, we observe that the ratio M (P z3,z32)/M (0 ,z32) has a Gaussian-type behavior with respect to z3 for 6 values of P used in the calculation. This means that Z (z32) factor was canceled in the ratio. When plotted as a function of ν and z3, the data are very close to z3-independent functions. This phenomenon corresponds to factorization of the x - and k⊥-dependence for the TMD F (x ,k⊥2). For small z3≤4 a , the residual z3-dependence is explained by perturbative evolution, with αs/π =0.1 .

  20. Speciation and Distribution of Trace Metals and Organic Matter in Marine Lake as In Situ Laboratory

    Science.gov (United States)

    Mlakar, M.; Fiket, Ž.; Cuculić, V.; Cukrov, N.; Geček, S.

    2016-02-01

    Marine lakes are unique, isolated marine systems, also recognized as in situ "laboratories" in which geochemical processes on a different scale compared to the open sea, can be observed. Impact of organic matter cycling on distribution of trace metals in the marine lake Mir, located on Dugi Otok Island, in the central part of the eastern Adriatic Sea, was investigated. Intense spatial and seasonal variations of physico-chemical parameters and organic matter concentrations in the water column of the Lake are governed predominantly by natural processes. Enhanced oxygen consumption in the Lake during summer season, high organic carbon concentrations and low redox potential result in occasional occurrence of anoxic conditions in the bottom layers. Speciation modelling showed that dissolved trace metals Cu, Pb and Zn, are mostly bound to organic matter, while Cd, Co and Ni are present predominantly as free ions and inorganic complexes. Trace metals removal from the water column and their retention in the sediment was found to depend on the nature of the relationship between specific metal and high proportion of organic matter (up to 9%) and inorganic phases, Fe-oxyhydroxydes or biogenic calcite. Surrounding karstic background, with occasional occurrences of red soil characterize deposited sediments as coarse grained and carbonate rich, whose elemental composition is affected by bathymetry of the basin and overall biological production.

  1. Spatial distribution of metals in soil samples from Zona da Mata, Pernambuco, Brazil using XRF technique

    International Nuclear Information System (INIS)

    Fernandez, Zahily Herrero; Santos Junior, Jose Araujo dos; Amaral, Romilton dos Santos; Menezes, Romulo Simoes Cezar; Santos, Josineide Marques do Nascimento; Bezerra, Jairo Dias; Damascena, Kennedy Francys Rodrigues; Silva, Edvane Borges da; Silva, Alberto Antonio da

    2015-01-01

    Soil contamination is today one of the most important environmental issues for society. In the past, soil pollution was not considered as important as air and water contamination, because this was more difficult to be controlled, becoming an important topic in studies of environmental protection worldwide. Based on this, this paper provides information on the determination of metals in soil samples collected in Zona da Mata, Pernambuco, Brazil, where normally the application of pesticides, insecticides and other agricultural additives are used in a disorderly manner and without control. A total of 24 sampling points were monitored. The analysis of Mn, Fe, Ni, Zn, Br, Rb, Sr, Pb, Ti, La, Al, Si and P were performed using Energy Dispersive X-Ray Fluorescence. In order to assess the development of analytical method, inorganic Certified Reference Materials (IAEA-SOIL-7 and SRM 2709) were analyzed. In each sampling site, the geoaccumulation index were calculated to estimate the level of metal contamination in the soil, this was made taking into account the resolution 460 of the National Environmental Council (CONAMA in Portuguese). The elemental distribution patterns obtained for each metal were associated with different pollution sources. This assessment provides an initial description of pollution levels presented by metals in soils from several areas of Zona da Mata, providing quantitative evidence and demonstrating the need to improve the regulation of agricultural and industrial activities. (author)

  2. Spatial distribution of metals in soil samples from Zona da Mata, Pernambuco, Brazil using XRF technique

    Energy Technology Data Exchange (ETDEWEB)

    Fernandez, Zahily Herrero; Santos Junior, Jose Araujo dos; Amaral, Romilton dos Santos; Menezes, Romulo Simoes Cezar; Santos, Josineide Marques do Nascimento; Bezerra, Jairo Dias; Damascena, Kennedy Francys Rodrigues, E-mail: zahily1985@gmail.com, E-mail: jaraujo@ufpe.br, E-mail: romilton@ufpe.br, E-mail: rmenezes@ufpe.br, E-mail: neideden@hotmail.com, E-mail: jairo.dias@ufpe.br, E-mail: kennedy.eng.ambiental@gmail.com [Universidade Federal de Pernambuco (UFPE), Recife, PE (Brazil). Centro de Tecnologia e Geociencias. Departamento de Energia Nuclear; Alvarez, Juan Reinaldo Estevez, E-mail: jestevez@ceaden.cu [Centro de Aplicaciones Tecnologicas y Desarrollo Nuclear (CEADEN), Havana (Cuba); Silva, Edvane Borges da, E-mail: edvane.borges@pq.cnpq.br [Universidade Federal de Pernambuco (UFPE), Vitoria de Santo Antao, PE (Brazil). Nucleo de Biologia; Franca, Elvis Joacir de; Farias, Emerson Emiliano Gualberto de, E-mail: ejfranca@cnen.gov.br, E-mail: emersonemiliano@yahoo.com.br [Centro Regional de Ciencias Nucleares do Nordeste (CRCN-NE/CNEN-PE), Recife, PE (Brazil); Silva, Alberto Antonio da, E-mail: alberto.silva@barreiros.ifpe.edu.br [Instituto Federal de Educacao, Ciencia e Tecnologia de Pernambuco (IFPE), Barreiros, PE (Brazil)

    2015-07-01

    Soil contamination is today one of the most important environmental issues for society. In the past, soil pollution was not considered as important as air and water contamination, because this was more difficult to be controlled, becoming an important topic in studies of environmental protection worldwide. Based on this, this paper provides information on the determination of metals in soil samples collected in Zona da Mata, Pernambuco, Brazil, where normally the application of pesticides, insecticides and other agricultural additives are used in a disorderly manner and without control. A total of 24 sampling points were monitored. The analysis of Mn, Fe, Ni, Zn, Br, Rb, Sr, Pb, Ti, La, Al, Si and P were performed using Energy Dispersive X-Ray Fluorescence. In order to assess the development of analytical method, inorganic Certified Reference Materials (IAEA-SOIL-7 and SRM 2709) were analyzed. In each sampling site, the geoaccumulation index were calculated to estimate the level of metal contamination in the soil, this was made taking into account the resolution 460 of the National Environmental Council (CONAMA in Portuguese). The elemental distribution patterns obtained for each metal were associated with different pollution sources. This assessment provides an initial description of pollution levels presented by metals in soils from several areas of Zona da Mata, providing quantitative evidence and demonstrating the need to improve the regulation of agricultural and industrial activities. (author)

  3. Distribution Characteristic and Migration Pathways of Metals in Subsidence Zone in a Coal Mine, China.

    Science.gov (United States)

    Han, Fushun; Zhang, Yan

    2017-04-01

    Subsidence can influence the distribution characteristics and migration pathways of metals in coal mines. In order to understand the two important and related issues of subsidence and pollution in coal mines, ten sample cores were collected in the coal mining subsidence and non-subsidence zones in Anhui province, China, and the concentration and forms of metals were analyzed. The results showed that concentrations for all metals significantly increased at the depth of 0-20 cm in these two zones. Concentrations of Cd, Cu, and Zn in the non-subsidence zone were 1.14, 1.69 and 1.48 times higher, respectively, than those in the subsidence zone, while concentrations of Cr and Pb showed no significant difference. The proportion of exchangeable and acid-extracted fractions of Cd, Cu and Zn in the non-subsidence zone were higher than those in the subsidence zone. This may be due to the different migration pathways for exchangeable and acid-extracted fractions of metals in subsidence and non-subsidence zones.

  4. The distribution of star formation and metals in the low surface brightness galaxy UGC 628

    Science.gov (United States)

    Young, J. E.; Kuzio de Naray, Rachel; Wang, Sharon X.

    2015-09-01

    We introduce the MUSCEL Programme (MUltiwavelength observations of the Structure, Chemistry and Evolution of LSB galaxies), a project aimed at determining the star-formation histories of low surface brightness galaxies. MUSCEL utilizes ground-based optical spectra and space-based UV and IR photometry to fully constrain the star-formation histories of our targets with the aim of shedding light on the processes that led low surface brightness galaxies down a different evolutionary path from that followed by high surface brightness galaxies, such as our Milky Way. Here we present the spatially resolved optical spectra of UGC 628, observed with the VIRUS-P IFU at the 2.7-m Harlen J. Smith Telescope at the McDonald Observatory, and utilize emission-line diagnostics to determine the rate and distribution of star formation as well as the gas-phase metallicity and metallicity gradient. We find highly clustered star formation throughout UGC 628, excluding the core regions, and a log(O/H) metallicity around -4.2, with more metal-rich regions near the edges of the galactic disc. Based on the emission-line diagnostics alone, the current mode of star formation, slow and concentrated in the outer disc, appears to have dominated for quite some time, although there are clear signs of a much older stellar population formed in a more standard inside-out fashion.

  5. Distribution of heavy metals (Cu and Fe) in sea water of Gresik coastal area

    Science.gov (United States)

    Nindyapuspa, Ayu; Ni'am, Achmad Chusnun

    2018-02-01

    The improvement of industrial activities at Gresik Regency will increase the heavy metals concentration on the seawater at Gresik Regency. Therefore, the research of Fe and Cr distribution on the seawater at Gresik Regency has been conducted. Methods that were used is sampling by Nansen water sampler at three sampling points (housing in northern coastal Gresik Regency, Maspion V Industrial Estate, and Petrokimia Port). Samples were analyzed by Atomic Absorption Spectrophotometry (AAS) to determine the concentration of heavy metals. The results showed that the highest Fe and Cr concentration are located at Maspion V Industrial Estate (0.452 mg/L and 0.081 mg/L respectively). Meanwhile, Fe and Cr concentrations at the housing in northern coastal are (0.408 mg/L and 0.081 mg/L respectively). The concentration of Fe and Cr at Petrokimia Port are 0.174 mg/L and 0.021 mg/L respectively.

  6. Applying Incremental Sampling Methodology to Soils Containing Heterogeneously Distributed Metallic Residues to Improve Risk Analysis.

    Science.gov (United States)

    Clausen, J L; Georgian, T; Gardner, K H; Douglas, T A

    2018-01-01

    This study compares conventional grab sampling to incremental sampling methodology (ISM) to characterize metal contamination at a military small-arms-range. Grab sample results had large variances, positively skewed non-normal distributions, extreme outliers, and poor agreement between duplicate samples even when samples were co-located within tens of centimeters of each other. The extreme outliers strongly influenced the grab sample means for the primary contaminants lead (Pb) and antinomy (Sb). In contrast, median and mean metal concentrations were similar for the ISM samples. ISM significantly reduced measurement uncertainty of estimates of the mean, increasing data quality (e.g., for environmental risk assessments) with fewer samples (e.g., decreasing total project costs). Based on Monte Carlo resampling simulations, grab sampling resulted in highly variable means and upper confidence limits of the mean relative to ISM.

  7. Impact of Saw Dust Application on the Distribution of Potentially Toxic Metals in Contaminated Soil.

    Science.gov (United States)

    Awokunmi, Emmmanuel E

    2017-12-01

    The need to develop an approach for the reclamation of contaminated site using locally available agricultural waste has been considered. The present study investigated the application of sawdust as an effective amendment in the immobilization of potentially toxic metals (PTMs) by conducting a greenhouse experiment on soil collected from an automobile dumpsite. The amended and non-amended soil samples were analyzed for their physicochemical parameters and sequential extraction of PTMs. The results revealed that application of amendment had positive impact on the physicochemical parameters as organic matter content and cation exchange capacity increased from 12.1% to 12.8% and 16.4 to 16.8 meq/100 g respectively. However, the mobility and bioavalability of these metals was reduced as they were found to be distributed mostly in the non-exchangeable phase of soil. Therefore, application of sawdust successfully immobilized PTMs and could be applied for future studies in agricultural soil reclamation.

  8. Distribution, enrichment and source of heavy metals in Rizhao offshore area, southeast Shandong Province.

    Science.gov (United States)

    Song, Hongying; Liu, Jinqing; Yin, Ping; Zhang, Yong

    2017-06-30

    50 surface sediments were collected from Rizhao offshore area to determine heavy metals (Cu, Pb, Zn, Cr, Cd, As, Hg) pollution. High heavy metal values were located near the two ports in the north and south study areas, which was consistent with the distribution of fine-grained sediments. According to threshold effect level (TEL) and probable effect level (PEL), Cu and As had occasionally adverse biological effects on the aquatic ecosystems. The enrichment factor (EF) values showed that most of the study area was moderate or moderately severe enrichment for As, and minor enrichment for Pb, but Hg was only moderately enriched in the river estuaries. The sources of Cu, Zn and Cr were mainly influenced by natural weathering processes via the river inputs, whereas Pb, Cd and As were mainly derived from anthropogenic sources. Hg may have both natural and anthropogenic sources. Copyright © 2017 Elsevier Ltd. All rights reserved.

  9. Heavy metals seasonal variability and distribution in Lake Qaroun sediments, El-Fayoum, Egypt

    Science.gov (United States)

    Redwan, Mostafa; Elhaddad, Engy

    2017-10-01

    This study was carried out to investigate the seasonal variability and distribution of heavy metals ;HMs; (Fe, Mn, Co, Cr, Cu, Ni, Pb, Zn and V) in the bottom sediments of Lake Qaroun, in Egypt. The samples were collected from 10 sites in summer and winter seasons in 2015. Total metals concentrations were measured using inductively coupled plasma spectrometer. Multivariate techniques were applied to analyse the distribution and potential source of heavy metals. The mean seasonal concentrations follow a descending order of Fe > Mn > V > Zn > Cr > Ni > Cu > Co > Pb. The mean concentrations of HMs in sediments during summer were higher than the concentrations during winter and above the average world shale values, except for Pb, suggesting potential adverse toxicity to aquatic organisms. All metals showed enrichment during summer and winter at sites S3 and S5 in the southeastern parts of the lake due to the heavy discharge of contaminants from El-Bats and El-Wadi drains. Principal component analysis results suggested two principal components controlling HMs variability in sediments, which accounted for 63.9% (factor 1: Co, Cr, Cu, Ni, Zn, Pb and V), 15.9% (factor 2: Mn and Fe) during summer, and 76.7% (factor 1: Fe, Co, Cr, Cu, Ni, Zn, Pb and V), 13.8% (factor 2: Mn) during winter of the total variance. Geo-accumulation index (Igeo) showed some pollution risk at the southeastern and southern parts (sites S3 and S5). Dilution during winter, concentration during summer, impact of non-point sources from different agricultural, industrial, municipal sewage and fish farms in the southern part of Lake Qaroun, adsorption and salt dissolution reactions and lithogenic sources are the main controlling factors for HMs in the study area. Monitoring of contaminant discharge at Lake Qaroun should be introduced for future remediation and management strategies.

  10. Selective distributions of functionalized single-walled carbon nanotubes in a polymeric reverse hexagonal phase.

    Science.gov (United States)

    Ha, Jae-Min; Jang, Hyung-Sik; Lim, Sung-Hwan; Choi, Sung-Min

    2015-08-07

    We have investigated the distributions of individually isolated and hydrophilically functionalized single-walled carbon nanotubes (p-SWNTs) in the Pluronic L121-water system at the reverse hexagonal phase using small-angle X-ray scattering (SAXS) and contrast-matched small-angle neutron scattering (SANS) measurements. As the p-SWNT-L121-water system is transitioned from the lamellar phase to the reverse hexagonal phase with temperature, p-SWNTs which were selectively distributed in the polar layers of the lamellar structure become selectively distributed in the cylindrical polar cores of the reverse hexagonal structure, forming a hexagonal array of p-SWNTs. This was clearly confirmed by the contrast-matched SANS measurements. The selective distribution of p-SWNTs in the reverse hexagonal phase is driven by the selective affinity of p-SWNTs to the polar domains of the block copolymer system. The method demonstrated in this study provides a new route for fabricating ordered SWNT superstructures and may be applicable for inorganic 1D nanoparticles such as semiconducting, metallic and magnetic nanorods which are of great interest.

  11. Beyond Flory theory: Distribution functions for interacting lattice trees

    Science.gov (United States)

    Rosa, Angelo; Everaers, Ralf

    2017-01-01

    While Flory theories [J. Isaacson and T. C. Lubensky, J. Physique Lett. 41, 469 (1980), 10.1051/jphyslet:019800041019046900; M. Daoud and J. F. Joanny, J. Physique 42, 1359 (1981), 10.1051/jphys:0198100420100135900; A. M. Gutin et al., Macromolecules 26, 1293 (1993), 10.1021/ma00058a016] provide an extremely useful framework for understanding the behavior of interacting, randomly branching polymers, the approach is inherently limited. Here we use a combination of scaling arguments and computer simulations to go beyond a Gaussian description. We analyze distribution functions for a wide variety of quantities characterizing the tree connectivities and conformations for the four different statistical ensembles, which we have studied numerically in [A. Rosa and R. Everaers, J. Phys. A: Math. Theor. 49, 345001 (2016), 10.1088/1751-8113/49/34/345001 and J. Chem. Phys. 145, 164906 (2016), 10.1063/1.4965827]: (a) ideal randomly branching polymers, (b) 2 d and 3 d melts of interacting randomly branching polymers, (c) 3 d self-avoiding trees with annealed connectivity, and (d) 3 d self-avoiding trees with quenched ideal connectivity. In particular, we investigate the distributions (i) pN(n ) of the weight, n , of branches cut from trees of mass N by severing randomly chosen bonds; (ii) pN(l ) of the contour distances, l , between monomers; (iii) pN(r ⃗) of spatial distances, r ⃗, between monomers, and (iv) pN(r ⃗|l ) of the end-to-end distance of paths of length l . Data for different tree sizes superimpose, when expressed as functions of suitably rescaled observables x ⃗=r ⃗/√{ } or x =l / . In particular, we observe a generalized Kramers relation for the branch weight distributions (i) and find that all the other distributions (ii-iv) are of Redner-des Cloizeaux type, q (x ⃗) =C |x| θexp(-(K|x |) t) . We propose a coherent framework, including generalized Fisher-Pincus relations, relating most of the RdC exponents to each other and to the contact and Flory

  12. Metal-Ligand Bonds of Second- and Third-Row d-Block Metals Characterized by Density Functional Theory

    DEFF Research Database (Denmark)

    Kepp, Kasper Planeta

    2009-01-01

    This paper presents systematic data for 200 neutral diatomic molecules ML (M is it second- or third-row d-block metal and L = H, F, Cl, Br, I, C, N, O, S, or Se) Computed with the density functionals TPSSh and BP86. With experimental Structures and bond enthalpies available for many...... of these molecules, the computations first document the high accuracy of TPSSh, giving metal-ligand bond lengths with a mean absolute error of similar to 0.01 angstrom for the second row and 0.03 angstrom for the third row. TPSSh provides metal-ligand bond enthalpies with mean absolute errors of 37 and 44 k...... metal-ligand bond lengths, and bond enthalpies for many as yet uncharacterized diatomics, of interest to researchers in the field of second- and third-row d-block chemistry. We stress that the success of TPSSh cannot be naively extrapolated to other special situations such as, e.g., metal-metal bonds...

  13. Structural and functional studies of heavy metal ATPases

    DEFF Research Database (Denmark)

    Sitsel, Oleg

    2015-01-01

    to handle heavy metal ions. LpCopA is then compared to its two human homologues ATP7A and ATP7B, which cause the severe Menkes and Wilson diseases when malfunctioning. The differences between the three proteins are described and disease-causing mutations in the human proteins are analyzed. The crystal......Copper and zinc are trace elements that are crucial for the well-being of all cells and are an indispensable part of many proteins. At the same time, the intracellular levels of these metals require careful regulation, as an excess or deficiency may be lethal. P1B-ATPases are key players in Cu...

  14. Analysis of wind speed distributions: Wind distribution function derived from minimum cross entropy principles as better alternative to Weibull function

    International Nuclear Information System (INIS)

    Kantar, Yeliz Mert; Usta, Ilhan

    2008-01-01

    In this study, the minimum cross entropy (MinxEnt) principle is applied for the first time to the wind energy field. This principle allows the inclusion of previous information of a wind speed distribution and covers the maximum entropy (MaxEnt) principle, which is also discussed by Li and Li and Ramirez as special cases in their wind power study. The MinxEnt probability density function (pdf) derived from the MinxEnt principle are used to determine the diurnal, monthly, seasonal and annual wind speed distributions. A comparison between MinxEnt pdfs defined on the basis of the MinxEnt principle and the Weibull pdf on wind speed data, which are taken from different sources and measured in various regions, is conducted. The wind power densities of the considered regions obtained from Weibull and MinxEnt pdfs are also compared. The results indicate that the pdfs derived from the MinxEnt principle fit better to a variety of measured wind speed data than the conventionally applied empirical Weibull pdf. Therefore, it is shown that the MinxEnt principle can be used as an alternative method to estimate both wind distribution and wind power accurately

  15. Study on a control system for autonomous distributed cooperative function

    International Nuclear Information System (INIS)

    Matsuoka, Takeshi

    1996-01-01

    Developments of an autonomous plant simulator, a plant function model and an indicating function for plant conditions were further progressed in the second stage of this project based on the concept of autonomous plant. And integration of the results from the research of operation control system by Power Reactor and Nuclear Fuel Development Corp. and the research of maintenance system by Institute of Physical and Chemical Research was attempted in this stage. Developments of system techniques which can provide transparent informations on the cooperation among the artificial intelligent units distributed in various sites and the process and results of judgement were conducted focusing on a monitoring system for plant operation. And it became possible to express the plant conditions such as temperature, pressure and flow rate at nearly real time using three-dimensional color graphics. Automatic classification method for clustering the plant conditions was investigated using COBWEB and 14 kinds of conditions were defined using 6 factors. The functional certification of them is undertaken. (M.N.)

  16. Distribution of heavy metals in peri-urban agricultural areas soils

    International Nuclear Information System (INIS)

    Iram, S.; Ahmad, I.; Akhtar, S.

    2012-01-01

    In industry oriented peri-urban areas, the heavy metals accumulation in soils caused by industrialization has become a potential threat. The top soil sample from 48 agricultural fields were collected from a typical industry based peri-urban areas (Lahore, Faisalabad, Multan, Kasur, Islamabad, Wah Cantt.) of Punjab, Pakistan to study the accumulation and distribution of heavy metals (Pb, Cd, Cr, Cu, Ni and Zn) by atomic absorption spectrophotometer. The aim of the study was to investigate influence of an industrialized environment on the accumulation of heavy metals in peri-urban agricultural soils. The results of the study showed that the Pb content in the soil ranged from 17.24 to 126.4 mg/kg and the highest Pb content was observed in Islamabad soil samples, and the lowest in that of Multan area. The Cd content ranged from 1.1 to 4.0 mg/kg in Lahore while the highest Cr concentration level was 210.2 mg/kg and it was observed in Kasur and lowest 30.60 in that of Multan. The Cu content ranged from 31.2 to 127.9 mg/kg (Kasur-Lahore). The highest Ni concentration (82.0 mg/kg) was observed in Lahore from the urban area and the lowest level of 12.15 mg/kg was observed in Multan. The Zn content ranged from 42.5 to 267.7 mg/kg (Faisalabad-Wah Cantt). The study concluded that the concentration level of the heavy metals (Pb, Cd, Cu, Ni, Cr, Zn) in the studied peri-urban areas was higher as compared to heavy metal content of normal Dutch soil. High automobile traffic and industrial waste both are the most likely sources of the contamination of the peri urban areas of Pakistan. (author)

  17. The spatial and temporal distribution of heavy metals in sediments of Victoria Harbour, Hong Kong

    Energy Technology Data Exchange (ETDEWEB)

    Tang, Chloe Wing-yee; Ip, Carman Ching-man [Department of Civil and Structural Engineering, The Hong Kong Polytechnic University, Hung Hom, Kowloon (Hong Kong); Zhang Gan [State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640 (China); Shin, Paul K.S. [Department of Biology and Chemistry, City University of Hong Kong, Tat Chee Avenue, Kowloon (Hong Kong); Qian Peiyuan [Department of Biology and Coastal Marine Laboratory, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon (Hong Kong); Li Xiangdong [Department of Civil and Structural Engineering, The Hong Kong Polytechnic University, Hung Hom, Kowloon (Hong Kong)], E-mail: cexdli@polyu.edu.hk

    2008-07-01

    Victoria Harbour has received substantial loadings of pollutants from industrial and municipal wastewater discharged since the 1950s. Inputs of contaminants have declined dramatically during the last two decades as a result of better controls at the source and improved wastewater treatment facilities. To assess the spatial and temporal changes of metal contaminants in sediments in Victoria Harbour, core and grab sediments were collected. The central harbour areas were generally contaminated with heavy metals. The spatial distribution of trace metals can probably be attributed to the proximity of major urban and industrial discharge points, and to the effect of tidal flushing in the harbour. In the sediment cores, the highest concentrations of trace metals were observed to have accumulated during the 1950s-1980s, corresponding with the period of rapid urban and industrial development in Hong Kong. From the late 1980s, there has been a major decline in the concentrations of trace metals, due to a reduction in industrial activities and to the enactment of wastewater pollution controls in the territory. The Pb isotopic compositions of the sediments revealed the anthropogenic inputs of Pb to the harbour. The {sup 206}Pb/{sup 207}Pb ratios varied from 1.154 to 1.190, which were lower than those of background geological materials in Hong Kong ({sup 206}Pb/{sup 207}Pb: 1.201-1.279). The data also indicated that the Pb in the harbour sediments most likely originated from mixed sources, including the leaded gasoline used in the past and other anthropogenic sources.

  18. Distributions of traces of metals on sorption from solutions of vanadium(V)

    International Nuclear Information System (INIS)

    Evseeva, N.K.; Turnaov, A.N.; Telegin, G.F.; Kremenskaya, I.N.

    1983-01-01

    A study is made of the distributions of traces of metals between aqueous solutions of vanadium(V) and a solid reagent made by introducing di-2-ethylhexylphosphoric acid into an inert matrix: a nonionic macroporous copolymer of polystyrene with divinyl benzene (wofatit Y 29). As regards degree of extraction, the trace components fall in the series zinc > cadmium > manganese > copper > cobalt, which resemble the extractability series. The vanadium content of the solution and the concentrations of the trace components have virtually no effect on the sorption. The process is effective in concentrating trace components from solutions containing vanadium(V)

  19. Distribution of microimpurities of metals at their sorption from vanadium (5) solutions

    International Nuclear Information System (INIS)

    Evseeva, N.K.; Turanov, A.N.; Telegin, G.F.; Kremenskaya, I.N.

    1983-01-01

    Distribution of metal microimpurities (Zn, Mn, Cu, Co, Fe) between aqueous solutions of vanadium (5) and solid extracting agent, prepared by means of introduction of di-2-ethylhexylphosphoric acid into inert matrix-nonionogeneous macropore copolymer of polystyrene with divinylbenzene (vofatit Y-29), has been studied. Accroding to the degree of extraction the microimpurities are arranged in the series: zinc > cadmium > manganese > copper > cobalt, which is similar to the series of extractability. Vanadium content in solution and concentration of microimpurities practically does not affect the sorption. It has been established that the process is effective for microimpurities concentration from solutions containing vanadium (5)

  20. Distribution of microimpurities of metals at their sorption from vanadium (5) solutions

    Energy Technology Data Exchange (ETDEWEB)

    Evseeva, N.K.; Turanov, A.N.; Telegin, G.F.; Kremenskaya, I.N.

    1983-01-01

    Distribution of metal microimpurities (Zn, Mn, Cu, Co, Fe) between aqueous solutions of vanadium (5) and solid extracting agent, prepared by means of introduction of di-2-ethylhexylphosphoric acid into inert matrix-nonionogeneous macropore copolymer of polystyrene with divinylbenzene (vofatit Y-29), has been studied. According to the degree of extraction the microimpurities are arranged in the series: zinc > cadmium > manganese > copper > cobalt, which is similar to the series of extractability. Vanadium content in solution and concentration of microimpurities practically does not affect the sorption. It has been established that the process is effective for microimpurities concentration from solutions containing vanadium (5).

  1. Metal-Ligand Bonds of Second- and Third-Row d-Block Metals Characterized by Density Functional Theory

    Science.gov (United States)

    Jensen, Kasper P.

    2009-08-01

    This paper presents systematic data for 200 neutral diatomic molecules ML (M is a second- or third-row d-block metal and L = H, F, Cl, Br, I, C, N, O, S, or Se) computed with the density functionals TPSSh and BP86. With experimental structures and bond enthalpies available for many of these molecules, the computations first document the high accuracy of TPSSh, giving metal-ligand bond lengths with a mean absolute error of ˜0.01 Å for the second row and 0.03 Å for the third row. TPSSh provides metal-ligand bond enthalpies with mean absolute errors of 37 and 44 kJ/mol for the second- and third-row molecules, respectively. Pathological cases (e.g., HgC and HgN) have errors of up to 155 kJ/mol, more than thrice the mean (observed with both functionals). Importantly, the systematic error component is negligible as measured by a coefficient of the linear regression line of 0.99. Equally important, TPSSh provides uniform accuracy across all three rows of the d-block, which is unprecedented and due to the 10% exact exchange, which is close to optimal for the d-block as a whole. This work provides an accurate and systematic prediction of electronic ground-state spins, characteristic metal-ligand bond lengths, and bond enthalpies for many as yet uncharacterized diatomics, of interest to researchers in the field of second- and third-row d-block chemistry. We stress that the success of TPSSh cannot be naively extrapolated to other special situations such as, e.g., metal-metal bonds. The high accuracy of the procedure further implies that the effective core functions used to model relativistic effects are necessary and sufficient for obtaining accurate geometries and bond enthalpies of second- and third-row molecular systems.

  2. Phthalates, perfluoroalkyl acids, metals and organochlorines and reproductive function

    DEFF Research Database (Denmark)

    Lenters, Virissa; Portengen, Lützen; Smit, Lidwien A M

    2015-01-01

    than 70% of blood samples, including metabolites of di(2-ethylhexyl) and diisononyl phthalates (DEHP, DiNP), perfluoroalkyl acids, metals and organochlorines. Twenty-two reproductive biomarkers were assessed, including serum levels of reproductive hormones, markers of semen quality, sperm chromatin...

  3. (II) metal ions using phosphonate-functionalized polymer

    Indian Academy of Sciences (India)

    The metal binding was examined by the energy dispersive spectroscopy and scanning electron microscopy for the adsorbed Sr(II). Batch adsorption studies were performed by varying three parameters, namely initial pH, adsorbentdose and the contact time. The reaction kinetics was determined by the Langmuir, Freundlich, ...

  4. 3rd Workshop on metal ceramic materials for functional applications

    International Nuclear Information System (INIS)

    Korb, G.

    1997-01-01

    This workshop contains contributions about materials and processing, characterization and modeling of properties and applications of metallic ceramics and composite structures. It was held on behalf of the Taiwan-Austrian scientific collaboration in Vienna, June 4 th - 6 th 1997. (Suda)

  5. Alzheimer’s disease: How metal ions define β-amyloid function

    DEFF Research Database (Denmark)

    Kepp, Kasper Planeta

    2017-01-01

    Alzheimer’s disease is increasingly recognized to be linked to the function and status of metal ions, and recently, the amyloid hypothesis has been strongly intertwined with the metal ion hypothesis; in fact, these two hypotheses fit well together and are not mutually contradictory. This review...

  6. Investigation of the metal binding site in methionine aminopeptidase by density functional theory

    DEFF Research Database (Denmark)

    Jørgensen, Anne Techau; Norrby, Per-Ola; Liljefors, Tommy

    2002-01-01

    All methionine aminopeptidases exhibit the same conserved metal binding site. The structure of this site with either Co2+ ions or Zn2+ ions was investigated using density functional theory. The calculations showed that the structure of the site was not influenced by the identity of the metal ions...

  7. Parton distribution functions and benchmark cross sections at NNLO

    Energy Technology Data Exchange (ETDEWEB)

    Alekhin, S. [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany); Institute for High Energy Physics (IHEP), Protvino (Russian Federation); Bluemlein, J.; Moch, S. [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany)

    2012-02-15

    We present a determination of parton distribution functions (ABM11) and the strong coupling constant {alpha}{sub s} at next-to-leading order and next-to-next-to-leading order (NNLO) in QCD based on world data for deep-inelastic scattering and fixed-target data for the Drell-Yan process. The analysis is performed in the fixed-flavor number scheme for n{sub f}=3,4,5 and uses the MS-scheme for {alpha}{sub s} and the heavy-quark masses. At NNLO we obtain the value {alpha}{sub s}(MZ)=0.1134{+-}0.0011. The fit results are used to compute benchmark cross sections at hadron colliders to NNLO accuracy and to compare to data from the LHC. (orig.)

  8. Smooth conditional distribution function and quantiles under random censorship.

    Science.gov (United States)

    Leconte, Eve; Poiraud-Casanova, Sandrine; Thomas-Agnan, Christine

    2002-09-01

    We consider a nonparametric random design regression model in which the response variable is possibly right censored. The aim of this paper is to estimate the conditional distribution function and the conditional alpha-quantile of the response variable. We restrict attention to the case where the response variable as well as the explanatory variable are unidimensional and continuous. We propose and discuss two classes of estimators which are smooth with respect to the response variable as well as to the covariate. Some simulations demonstrate that the new methods have better mean square error performances than the generalized Kaplan-Meier estimator introduced by Beran (1981) and considered in the literature by Dabrowska (1989, 1992) and Gonzalez-Manteiga and Cadarso-Suarez (1994).

  9. Alternative Equation on Magnetic Pair Distribution Function for Quantitative Analysis

    Science.gov (United States)

    Kodama, Katsuaki; Ikeda, Kazutaka; Shamoto, Shin-ichi; Otomo, Toshiya

    2017-12-01

    We derive an alternative equation of magnetic pair distribution function (mPDF) related to the mPDF equation given in a preceding study [B. A. Frandsen, X. Yang, and S. J. L. Billinge, https://doi.org/10.1107/S2053273313033081" xlink:type="simple">Acta Crystallogr., Sect. A 70, 3 (2014)] for quantitative analysis of realistic experimental data. The additional term related to spontaneous magnetization included in the equation is particularly important for the mPDF analysis of ferromagnetic materials. Quantitative estimation of mPDF from neutron diffraction data is also shown. The experimental mPDFs estimated from the neutron diffraction data of the ferromagnet MnSb and the antiferromagnet MnF2 are quantitatively consistent with the mPDFs calculated using the presented equation.

  10. Spin and orbital angular momentum distribution functions of the nucleon

    Science.gov (United States)

    Wakamatsu, M.; Watabe, T.

    2000-09-01

    A theoretical prediction is given for the spin and orbital angular momentum distribution functions of the nucleon within the framework of an effective quark model of QCD, i.e., the chiral quark soliton model. An outstanding feature of the model is that it predicts a fairly small quark spin fraction of the nucleon ΔΣ~=0.35, which in turn dictates that the remaining 65% of the nucleon spin is carried by the orbital angular momentum of quarks and antiquarks at the model energy scale of Q2~=0.3 GeV2. This large orbital angular momentum necessarily affects the scenario of scale dependence of the nucleon spin contents in a drastic way.

  11. Theoretical characterization of electron energy distribution function in RF plasmas

    International Nuclear Information System (INIS)

    Capitelli, M.; Capriati, G.; Dilonardo, M.; Gorse, C.; Longo, S.

    1993-01-01

    Different methods for the modeling of low-temperature plasmas of both technological and fundamental interest are discussed. The main concept of all these models is the electron energy distribution function (eedf) which is necessary to calculate the rate coefficients for any chemical reaction involving electrons. Results of eedf calculations in homogeneous SF 6 and SiH 4 plasmas are discussed based on solution of the time-dependent Boltzmann equation. The space-dependent eedf in an RF discharge in He is calculated taking into account the sheath oscillations by a Monte Carlo model assuming the plasma heating mechanism and the electric field determined by using a fluid model. The need to take into account the ambipolar diffusion of electrons in RF discharge modeling is stressed. A self-consistent model based on coupling the equations of the fluid model and the chemical kinetics ones is presented. (orig.)

  12. Noncovalent functionalization of carbon nanotubes with porphyrins: meso-tetraphenylporphine and its transition metal complexes.

    Science.gov (United States)

    Basiuk, Elena V; Basiuk, Vladimir A; Santiago, Patricia; Puente-Lee, Iván

    2007-01-01

    Noncovalent functionalization of carbon nanotubes with meso-tetraphenylporphine (H2TPP) and its metal(II) complexes NiTPP and CoTPP was studied by means of different experimental techniques and theoretical calculations. As follows from the experimental adsorption curves, free H2TPP ligand exhibits the strongest adsorption of three porphyrins tested, followed by CoTPP and NiTPP. At the highest porphyrin concentrations studied, the adsorption at multi-walled carbon nanotubes was about 2% (by weight) for H2TPP, 1% for CoTPP, and 0.5% for NiTPP. Transmission electron microscopy observations revealed carbon nanotubes with a variable degree of surface coverage with porphyrin molecules. According to scanning electron microscopy, the nanotubes glue together rather than debundle; apparently, a large porphyrin excess resulting in polymolecular adsorption is essential for exfoliation/debundling of the nanotube ropes. The nanotube/porphyrins hybrids were studied by infrared and Raman spectroscopy, as well as by scanning tunneling microscopy. Electronic structure calculations were performed at the B3LYP/LANL2MB theoretical level with the unsubstituted porphine (H2P) and its Co(II) complex, on one hand, and open-end armchair (5,5) (ANT) and zigzag (8,0) (ZNT) SWNT models, on the other hand. The interaction of H2P with ANT was found to be by 3.9 kcal mol(-1) stronger than that of CoP. At the same time, CoP+ZNT complex is more stable by 42.7 kcal mol(-1) as compared to H2P+ZNT According to these calculated results, the free porphyrins interact less selectively with zigzag and armchair (i.e., semiconducting and metallic) nanotubes, whereas the difference becomes very large for the metal porphyrins. HOMO-LUMO structure, electrostatic potential and spin density distribution for the paramagnetic cobalt(II) complexes were analyzed.

  13. LUMINOUS SATELLITES. II. SPATIAL DISTRIBUTION, LUMINOSITY FUNCTION, AND COSMIC EVOLUTION

    Energy Technology Data Exchange (ETDEWEB)

    Nierenberg, A. M.; Treu, T. [Department of Physics, University of California, Santa Barbara, CA 93106 (United States); Auger, M. W. [Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB30HA (United Kingdom); Marshall, P. J. [Department of Physics, University of Oxford, Keble Road, Oxford OX1 3RH (United Kingdom); Fassnacht, C. D. [Department of Physics, University of California, Davis, CA 95616 (United States); Busha, Michael T., E-mail: amn01@physics.ucsb.edu [Institute for Theoretical Physics, University of Zuerich, Zuerich (Switzerland)

    2012-06-20

    We infer the normalization and the radial and angular distributions of the number density of satellites of massive galaxies (log{sub 10}[M*{sub h}/M{sub Sun }] > 10.5) between redshifts 0.1 and 0.8 as a function of host stellar mass, redshift, morphology, and satellite luminosity. Exploiting the depth and resolution of the COSMOS Hubble Space Telescope images, we detect satellites up to 8 mag fainter than the host galaxies and as close as 0.3 (1.4) arcsec (kpc). Describing the number density profile of satellite galaxies to be a projected power law such that P(R){proportional_to}R{sup {gamma}{sub p}}, we find {gamma}{sub p} = -1.1 {+-} 0.3. We find no dependency of {gamma}{sub p} on host stellar mass, redshift, morphology, or satellite luminosity. Satellites of early-type hosts have angular distributions that are more flattened than the host light profile and are aligned with its major axis. No significant average alignment is detected for satellites of late-type hosts. The number of satellites within a fixed magnitude contrast from a host galaxy is dependent on its stellar mass, with more massive galaxies hosting significantly more satellites. Furthermore, high-mass late-type hosts have significantly fewer satellites than early-type galaxies of the same stellar mass, possibly indicating that they reside in more massive halos. No significant evolution in the number of satellites per host is detected. The cumulative luminosity function of satellites is qualitatively in good agreement with that predicted using SubHalo Abundance Matching techniques. However, there are significant residual discrepancies in the absolute normalization, suggesting that properties other than the host galaxy luminosity or stellar mass determine the number of satellites.

  14. A study of the distribution of rare-metals in kuroko-type ore

    Energy Technology Data Exchange (ETDEWEB)

    Murao, S. [Commonwealth Scientific and Industrial Research Organisation (CSIRO), North Ryde, NSW (Australia). Div. of Exploration Geoscience]|[Geological Survey of Japan, Tsukuba, Ibaraki (Japan); Sie, S.H.; Suter, G.F. [Commonwealth Scientific and Industrial Research Organisation (CSIRO), North Ryde, NSW (Australia). Div. of Exploration Geoscience

    1996-12-31

    We have performed PIXE analysis of kuroko-type ore from the JADE hydrothermal site of the Okinawa Trough, Japan using the proton microprobe (PIXEPROBE). We analysed five kinds of ores dredged from the sea floor: (I) barite ore with small sulfide dissemination; (2) sphalerite-pyrite chimney; (3) pyrite ore; (4) sulfide veinlets in strongly altered rock; and (5) pyrite megacrystals in strongly altered rock. The analyses revealed that the trace element distribution is regulated by the occurrence mode of the ore, and within each ore, by the crystal structure. The distribution suggests that the hydrothermal system for kuroko ore formation is quite heterogeneous and its chemistry is controlled by local factors such as difference in temperature, and that in-situ PIXE analyses are essential for effective beneficiation strategy for the rare-metals from kuroko-type ore. (authors). 10 refs., 1 tab.

  15. A study of the distribution of rare-metals in kuroko-type ore

    International Nuclear Information System (INIS)

    Murao, S.; Sie, S.H.; Suter, G.F.

    1996-01-01

    We have performed PIXE analysis of kuroko-type ore from the JADE hydrothermal site of the Okinawa Trough, Japan using the proton microprobe (PIXEPROBE). We analysed five kinds of ores dredged from the sea floor: (I) barite ore with small sulfide dissemination; (2) sphalerite-pyrite chimney; (3) pyrite ore; (4) sulfide veinlets in strongly altered rock; and (5) pyrite megacrystals in strongly altered rock. The analyses revealed that the trace element distribution is regulated by the occurrence mode of the ore, and within each ore, by the crystal structure. The distribution suggests that the hydrothermal system for kuroko ore formation is quite heterogeneous and its chemistry is controlled by local factors such as difference in temperature, and that in-situ PIXE analyses are essential for effective beneficiation strategy for the rare-metals from kuroko-type ore. (authors). 10 refs., 1 tab

  16. Impact of implanted metal plates on radiation dose distribution in vivo

    International Nuclear Information System (INIS)

    Liu Ming; Li Xingde; Niu Qingguo; Zhai Fushan

    2010-01-01

    Objective: To investigate the impact of metal plate on radiation dose distribution in surrounding tissues in cadaver specimens. Methods: Stainless steel plate, titanium plate, and muscle strip were implanted into the left thigh of a corpse, respectively. All the specimens were irradiated with 6 MV X-ray , SSD = 100 cm. The absorbed dose of surface was measured by thermoluminescent elements. Results: Surface dose distributions differed significantly among the three different materials (F = 57.35, P < 0.01), with the amounts of 1.18 Gy ± 0.04 Gy (stainless steel plate), 1.12 Gy ± 0.04 Gy (titanium plate) and 0.97 Gy ± 0.03 Gy (muscle strip), respectively. The surface absorbed doses on incident plane of stainless steel plate and titanium plate were significantly increased by 21.65% and 15.46% respectively as compared with that of muscle strip. The absorbed doses on the exit surface of stainless steel plate, titanium plate and muscle strip were 0.87 Gy ± 0.03 Gy, 0.90 Gy ± 0.02 Gy and 0.95 Gy ± 0.04 Gy, respectively (F =13.37, P <0.01). The doses on the exit surface of stainless steel plate and titanium plate were significantly lowered by 8.42% and 5.26% when compared with that of muscle strip. Using treatment planning system,the differences between dose distribution with and without metal plate were compared. Within 1 cm away from the incident plate, there was an obvious increase in the absorbed dose, while the influence was less than 5% 1 cm outside the surface. The effect of dose distribution on exit surface was less than 2%. Conclusions: The influence of metal plate on the radiotherapy dose distribution is significant. The deviations ranges from 5% to 29%. Under the same condition, the impact of stainless steel plate is much more than that of titanium alloy plate. (authors)

  17. Planar Indium Tin Oxide Heater for Improved Thermal Distribution for Metal Oxide Micromachined Gas Sensors.

    Science.gov (United States)

    Çakır, M Cihan; Çalışkan, Deniz; Bütün, Bayram; Özbay, Ekmel

    2016-09-29

    Metal oxide gas sensors with integrated micro-hotplate structures are widely used in the industry and they are still being investigated and developed. Metal oxide gas sensors have the advantage of being sensitive to a wide range of organic and inorganic volatile compounds, although they lack selectivity. To introduce selectivity, the operating temperature of a single sensor is swept, and the measurements are fed to a discriminating algorithm. The efficiency of those data processing methods strongly depends on temperature uniformity across the active area of the sensor. To achieve this, hot plate structures with complex resistor geometries have been designed and additional heat-spreading structures have been introduced. In this work we designed and fabricated a metal oxide gas sensor integrated with a simple square planar indium tin oxide (ITO) heating element, by using conventional micromachining and thin-film deposition techniques. Power consumption-dependent surface temperature measurements were performed. A 420 °C working temperature was achieved at 120 mW power consumption. Temperature distribution uniformity was measured and a 17 °C difference between the hottest and the coldest points of the sensor at an operating temperature of 290 °C was achieved. Transient heat-up and cool-down cycle durations are measured as 40 ms and 20 ms, respectively.

  18. Planar Indium Tin Oxide Heater for Improved Thermal Distribution for Metal Oxide Micromachined Gas Sensors

    Directory of Open Access Journals (Sweden)

    M. Cihan Çakır

    2016-09-01

    Full Text Available Metal oxide gas sensors with integrated micro-hotplate structures are widely used in the industry and they are still being investigated and developed. Metal oxide gas sensors have the advantage of being sensitive to a wide range of organic and inorganic volatile compounds, although they lack selectivity. To introduce selectivity, the operating temperature of a single sensor is swept, and the measurements are fed to a discriminating algorithm. The efficiency of those data processing methods strongly depends on temperature uniformity across the active area of the sensor. To achieve this, hot plate structures with complex resistor geometries have been designed and additional heat-spreading structures have been introduced. In this work we designed and fabricated a metal oxide gas sensor integrated with a simple square planar indium tin oxide (ITO heating element, by using conventional micromachining and thin-film deposition techniques. Power consumption–dependent surface temperature measurements were performed. A 420 °C working temperature was achieved at 120 mW power consumption. Temperature distribution uniformity was measured and a 17 °C difference between the hottest and the coldest points of the sensor at an operating temperature of 290 °C was achieved. Transient heat-up and cool-down cycle durations are measured as 40 ms and 20 ms, respectively.

  19. Strong links between metal contamination, habitat modification and estuarine larval fish distributions

    International Nuclear Information System (INIS)

    McKinley, Andrew C.; Miskiewicz, Anthony; Taylor, Matthew D.; Johnston, Emma L.

    2011-01-01

    Changes to larval fish assemblages may have far reaching ecological impacts. Correlations between habitat modification, contamination and marine larval fish communities have rarely been assessed in situ. We investigated links between the large-scale distribution of stressors and larval fish assemblages in estuarine environments. Larval fish communities were sampled using a benthic sled within the inner and outer zones of three heavily modified and three relatively unmodified estuaries. Larval abundances were significantly greater in modified estuaries, and there were trends towards greater diversity in these systems. Differences in larval community composition were strongly related to sediment metal levels and reduced seagrass cover. The differences observed were driven by two abundant species, Paedogobius kimurai and Ambassis jacksoniensis, which occurred in large numbers almost exclusively in highly contaminated and pristine locations respectively. These findings suggest that contamination and habitat alteration manifest in substantial differences in the composition of estuarine larval fish assemblages. - Highlights: → We examine contamination/habitat modification impacts on larval fish. → Larvae communities differ between modified/unmodified estuaries. → Larvae are more abundant/diverse in modified areas. → Trends are strongly related to sediment metals/seagrass cover. → Larval impacts have wider ecological importance. - We describe strong links between sediment metals contamination, habitat modification and substantial differences in the composition of the estuarine larval fish assemblage.

  20. Strong links between metal contamination, habitat modification and estuarine larval fish distributions

    Energy Technology Data Exchange (ETDEWEB)

    McKinley, Andrew C., E-mail: andrew.mckinley@hotmail.com [Evolution and Ecology Research Centre, School of Biological, Earth and Environmental Sciences, University of New South Wales, Sydney, New South Wales 2052 (Australia); Miskiewicz, Anthony [Environment and Recreation, Wollongong City Council, 41 Burelli Street, Wollongong, New South Wales 2500 (Australia); Taylor, Matthew D.; Johnston, Emma L. [Evolution and Ecology Research Centre, School of Biological, Earth and Environmental Sciences, University of New South Wales, Sydney, New South Wales 2052 (Australia)

    2011-06-15

    Changes to larval fish assemblages may have far reaching ecological impacts. Correlations between habitat modification, contamination and marine larval fish communities have rarely been assessed in situ. We investigated links between the large-scale distribution of stressors and larval fish assemblages in estuarine environments. Larval fish communities were sampled using a benthic sled within the inner and outer zones of three heavily modified and three relatively unmodified estuaries. Larval abundances were significantly greater in modified estuaries, and there were trends towards greater diversity in these systems. Differences in larval community composition were strongly related to sediment metal levels and reduced seagrass cover. The differences observed were driven by two abundant species, Paedogobius kimurai and Ambassis jacksoniensis, which occurred in large numbers almost exclusively in highly contaminated and pristine locations respectively. These findings suggest that contamination and habitat alteration manifest in substantial differences in the composition of estuarine larval fish assemblages. - Highlights: > We examine contamination/habitat modification impacts on larval fish. > Larvae communities differ between modified/unmodified estuaries. > Larvae are more abundant/diverse in modified areas. > Trends are strongly related to sediment metals/seagrass cover. > Larval impacts have wider ecological importance. - We describe strong links between sediment metals contamination, habitat modification and substantial differences in the composition of the estuarine larval fish assemblage.

  1. Distribution functions to estimate radionuclide solid-liquid distribution coefficients in soils: the case of Cs

    Energy Technology Data Exchange (ETDEWEB)

    Ramirez-Guinart, Oriol; Rigol, Anna; Vidal, Miquel [Analytical Chemistry department, Faculty of Chemistry, University of Barcelona, Mart i Franques 1-11, 08028, Barcelona (Spain)

    2014-07-01

    In the frame of the revision of the IAEA TRS 364 (Handbook of parameter values for the prediction of radionuclide transfer in temperate environments), a database of radionuclide solid-liquid distribution coefficients (K{sub d}) in soils was compiled with data coming from field and laboratory experiments, from references mostly from 1990 onwards, including data from reports, reviewed papers, and grey literature. The K{sub d} values were grouped for each radionuclide according to two criteria. The first criterion was based on the sand and clay mineral percentages referred to the mineral matter, and the organic matter (OM) content in the soil. This defined the 'texture/OM' criterion. The second criterion was to group soils regarding specific soil factors governing the radionuclide-soil interaction ('cofactor' criterion). The cofactors depended on the radionuclide considered. An advantage of using cofactors was that the variability of K{sub d} ranges for a given soil group decreased considerably compared with that observed when the classification was based solely on sand, clay and organic matter contents. The K{sub d} best estimates were defined as the calculated GM values assuming that K{sub d} values were always log-normally distributed. Risk assessment models may require as input data for a given parameter either a single value (a best estimate) or a continuous function from which not only individual best estimates but also confidence ranges and data variability can be derived. In the case of the K{sub d} parameter, a suitable continuous function which contains the statistical parameters (e.g. arithmetical/geometric mean, arithmetical/geometric standard deviation, mode, etc.) that better explain the distribution among the K{sub d} values of a dataset is the Cumulative Distribution Function (CDF). To our knowledge, appropriate CDFs has not been proposed for radionuclide K{sub d} in soils yet. Therefore, the aim of this works is to create CDFs for

  2. General atomistic approach for modeling metal-semiconductor interfaces using density functional theory and nonequilibrium Green's function

    DEFF Research Database (Denmark)

    Stradi, Daniele; Martinez, Umberto; Blom, Anders

    2016-01-01

    an atomistic approach based on density functional theory and nonequilibrium Green's function, which includes all the relevant ingredients required to model realistic metal-semiconductor interfaces and allows for a direct comparison between theory and experiments via I-Vbias curve simulations. We apply...

  3. Spatial Distribution of Selected Heavy Metals in Surface Sediments of the EEZ of the East Coast of Peninsular Malaysia

    Directory of Open Access Journals (Sweden)

    Hasrizal Shaari

    2015-01-01

    Full Text Available Spatial distribution of selected metals (Al, Fe, Mn, Zn, Cu, and Co in surface sediments in the EEZ of the east coast of Peninsular Malaysia was investigated. The aim of this paper is to determine the distribution pattern and pollution status of heavy metals in tropical shelf sediments since limited information is available. Heavy metal concentrations ranged between 207.58 and 491.33 µg·g−1 for Mn, 36.13 and 125.93 µg·g−1 for Zn, 14.49 and 22.33 µg·g−1 for Cu, 2.00 and 11.12 µg·g−1 for Co, 6.20 and 8.95% for Fe, and 0.94 and 6.62% for Al. The mean concentrations of heavy metals are in decreasing order as follows: Fe > Al > Mn > Zn > Cu > Co. Most metals registered low concentrations at the nearshore areas. Pearson correlation indicates that most of the metals are derived from the miscellaneous sources. Based on the EFs and Igeo, it is implied that the surface sediment trace metal levels in the study area might be enriched by anthropogenic sources. However, the PLI suggests that this area is not contaminated from the measured heavy metals. This work is important to register the current levels of metals so that any change in concentration can be monitored and managed.

  4. The distribution and extent of heavy metal accumulation in song sparrows along Arizona's upper Santa Cruz River

    Science.gov (United States)

    Lester, Michael B.; van Riper, Charles

    2014-01-01

    Heavy metals are persistent environmental contaminants, and transport of metals into the environment poses a threat to ecosystems, as plants and wildlife are susceptible to long-term exposure, bioaccumulation, and potential toxicity. We investigated the distribution and cascading extent of heavy metal accumulation in southwestern song sparrows (Melospiza melodia fallax), a resident riparian bird species that occurs along the US/Mexico border in Arizona’s upper Santa Cruz River watershed. This study had three goals: (1) quantify the degree of heavy metal accumulation in sparrows and determine the distributional patterns among study sites, (2) compare concentrations of metals found in this study to those found in studies performed prior to a 2009 international wastewater facility upgrade, and (3) assess the condition of song sparrows among sites with differing potential levels of exposure. We examined five study sites along with a reference site that reflect different potential sources of contamination. Body mass residuals and leukocyte counts were used to assess sparrow condition. Birds at our study sites typically had higher metal concentrations than birds at the reference site. Copper, mercury, nickel, and selenium in song sparrows did exceed background levels, although most metals were below background concentrations determined from previous studies. Song sparrows generally showed lower heavy metal concentrations compared to studies conducted prior to the 2009 wastewater facility upgrade. We found no cascading effects as a result of metal exposure.

  5. CONTRIBUTIONS TO THE STUDY OF HEAVY METALS DISTRIBUTION (Zn, Pb, Cd, Bi, Cu IN SOME SOILS FROM GIURGEU MOUNTAINS

    Directory of Open Access Journals (Sweden)

    D. Bulgariu

    2005-10-01

    Full Text Available In this paper are presented the results of mineralogical and geochemical studies, realized for few soils from Giurgeu Mountains, which have as main purpose the distribution and mobility interpretation of minor elements (Cd, Cu, Pb, Zn, Bi in studied soil samples. The determination of fixed fractions and mobile fractions weight, at total contents of studied elements, and relative association of these elements with main mineral and organic components of soil samples, was realized on the basis of results obtained by sequential solid/ liquid extraction. The same, we try to use the correlation establish between metallic ions contents, as indicators of mineral paragenesis (the genetic type and formation conditions. The obtained results are agree with the results of similar studies from literature and they, underline of some interesting aspects about of distribution and migration of heavy metals in soils: (1 exist of some selectivity in heavy metals distribution in mineral components from soils, correlated with reciprocals geochemical affinities between speciation forms of metals and mineral components, in a given pedogeochemical context; (2 the heavy metals distribution between solid phases and soil solution are realized in competitive regime, and the inter-phases equilibrium evolution are thermodynamic and kinetics controlled by the solid/ liquid interfaces processes; (3 the fast elementary processes and local fluctuations of physic-chemical parameters are the main factors which controlled the inter-phases transfer ratio and the evolution direction of equilibriums of heavy metals distribution.

  6. Characteristic functions of scale mixtures of multivariate skew-normal distributions

    KAUST Repository

    Kim, Hyoung-Moon

    2011-08-01

    We obtain the characteristic function of scale mixtures of skew-normal distributions both in the univariate and multivariate cases. The derivation uses the simple stochastic relationship between skew-normal distributions and scale mixtures of skew-normal distributions. In particular, we describe the characteristic function of skew-normal, skew-t, and other related distributions. © 2011 Elsevier Inc.

  7. Insights into the effects of metal nanostructuring and oxidation on the work function and charge transfer of metal/graphene hybrids

    Science.gov (United States)

    Giangregorio, M. M.; Jiao, W.; Bianco, G. V.; Capezzuto, P.; Brown, A. S.; Bruno, G.; Losurdo, M.

    2015-07-01

    Graphene/metal heterojunctions are ubiquitous in graphene-based devices and, therefore, have attracted increasing interest of researchers. Indeed, the literature on the field reports apparently contradictory results about the effect of a metal on graphene doping. Here, we elucidate the effect of metal nanostructuring and oxidation on the metal work function (WF) and, consequently, on the charge transfer and doping of graphene/metal hybrids. We show that nanostructuring and oxidation of metals provide a valid support to frame WF and doping variation in metal/graphene hybrids. Chemical vapour-deposited monolayer graphene has been transferred onto a variety of metal surfaces, including d-metals, such as Ag, Au, and Cu, and sp-metals, such as Al and Ga, configured as thin films or nanoparticle (NP) ensembles of various average sizes. The metal-induced charge transfer and the doping of graphene have been investigated using Kelvin probe force microscopy (KPFM), and corroborated by Raman spectroscopy and plasmonic ellipsometric spectroscopy. We show that when the appropriate WF of the metal is considered, without any assumption, taking into account WF variations by nanostructure and/or oxidation, a linear relationship between the metal WF and the doping of graphene is found. Specifically, for all metals, nanostructuring lowers the metal WF. In addition, using gold as an example, a critical metal nanoparticle size is found at which the direction of charge transfer, and consequently graphene doping, is inverted.

  8. Desmin Cytoskeleton Linked to Muscle Mitochondrial Distribution and Respiratory Function

    Science.gov (United States)

    Milner, Derek J.; Mavroidis, Manolis; Weisleder, Noah; Capetanaki, Yassemi

    2000-01-01

    Ultrastructural studies have previously suggested potential association of intermediate filaments (IFs) with mitochondria. Thus, we have investigated mitochondrial distribution and function in muscle lacking the IF protein desmin. Immunostaining of skeletal muscle tissue sections, as well as histochemical staining for the mitochondrial marker enzymes cytochrome C oxidase and succinate dehydrogenase, demonstrate abnormal accumulation of subsarcolemmal clumps of mitochondria in predominantly slow twitch skeletal muscle of desmin-null mice. Ultrastructural observation of desmin-null cardiac muscle demonstrates in addition to clumping, extensive mitochondrial proliferation in a significant fraction of the myocytes, particularly after work overload. These alterations are frequently associated with swelling and degeneration of the mitochondrial matrix. Mitochondrial abnormalities can be detected very early, before other structural defects become obvious. To investigate related changes in mitochondrial function, we have analyzed ADP-stimulated respiration of isolated muscle mitochondria, and ADP-stimulated mitochondrial respiration in situ using saponin skinned muscle fibers. The in vitro maximal rates of respiration in isolated cardiac mitochondria from desmin-null and wild-type mice were similar. However, mitochondrial respiration in situ is significantly altered in desmin-null muscle. Both the maximal rate of ADP-stimulated oxygen consumption and the dissociation constant (K m) for ADP are significantly reduced in desmin-null cardiac and soleus muscle compared with controls. Respiratory parameters for desmin-null fast twitch gastrocnemius muscle were unaffected. Additionally, respiratory measurements in the presence of creatine indicate that coupling of creatine kinase and the adenine translocator is lost in desmin-null soleus muscle. This coupling is unaffected in cardiac muscle from desmin-null animals. All of these studies indicate that desmin IFs play a significant

  9. Spatial distribution and source analysis of heavy metals in the marine sediments of Hong Kong.

    Science.gov (United States)

    Zhang, Xuan; Man, Xiaobing; Jiang, Honglei

    2015-08-01

    A data matrix, obtained during a 3-year monitoring period (2010-2012) from 45 sampling locations in the marine of Hong Kong, was subjected to pollution indicator and multivariate statistical technique analysis to investigate the spatial distribution and origin of the selected 12 heavy metals. Results suggested that V, Ni, and Ba were at safe levels, and there was a significant anthropogenic effect on Zn, Pb, Cu, Cd, and Cr, which were moderate to severe enrichment at some locations. Sampling locations 1, 2, 7, 9, 12, 13, 14, 30, 31, and 32 were identified as pollution hot spots. Principal component analysis and cluster analysis showed that Zn, Pb, Cu, Cd, and Cr were primarily controlled by anthropogenic sources and Ni, Ba, and V by natural sources. Whereas, Al, Fe, Mn, and As were controlled by both anthropogenic and natural sources. Cluster analysis classified 45 sampling sites into five groups and analysis of variance indicated there were significant differences between different groups. The pollution hot spots were classified into moderate or high polluted groups, and the influential factor of the heavy metal distribution was analyzed.

  10. Regional distribution and pollution evaluation of heavy metal pollution in topsoils of the Chengdu plain

    International Nuclear Information System (INIS)

    Li Bing; Wang Changquan; Yang Juan; Tan Ting; Li Huanxiu; Li Qiquan; Yuan Quan

    2009-01-01

    197 farm field samples were designated by GPS and the spatial distribution characteristic and pollution evaluation of Cd, Pb, Cr and Hg in the soils were studied. Compared to the background investigated 20 years ago, the content of Cd in Guanghan, Xindu, Qionglai increased 1, 1.26 and 2 times; respectively; and the content of Pb in Xinjin, Deyang, Guanghan, Xindu increased 1.1 and 3.3 times. However, the content of Cr and Hg in most regions changed much smaller. The results of Kriging interpolation analysis of the heavy metals showed that the content of Cd was grandly decreased followed with the direction from northeast to southwest, the content of other elements exhibited the regional characteristics. The geoaccumulation index was used to evaluate the heavy metals pollution and results indicated that nearly 50% of the soils was polluted by Pb and Cd in different degrees influenced by men activities. With the key contaminated area of Xindu, Guanghan, Xinjing, Deyang the pollution ranks of Pb in soils was in 1 to 4. The Cd pollution although small, but still ranks in 1 to 2 level, the pollution area was bigger, mainly distributed in Xindu, Deyang, Guanghan, Shuangliu, Xinjing, Pengzhou. Only a small number of samples was contaminated by Cr or Hg. (authors)

  11. Blood metal levels and metal-influenced immune functions of harbour seals in captivity

    International Nuclear Information System (INIS)

    Kakuschke, Antje; Valentine-Thon, Elizabeth; Griesel, Simone; Rosenberger, Tanja; Mundry, Roger; Siebert, Ursula; Prange, Andreas

    2008-01-01

    Immunological blood parameters and the effects of environmental pollutants on the immune system are important to assess the health status of seals. Animals living permanently in seal centres are useful for development and validation of diagnostic tools for free-ranging animals. In this study, parameters of cellular immunity as well as metal concentrations in blood and metal influence on cell proliferation of seven seals from a seal centre were investigated repeatedly using multi-element analysis and a lymphocyte proliferation assay. The metal concentrations, except for tin and chromium, were in general comparable to those of free-ranging animals of the North Sea. The unstimulated and mitogen-stimulated lymphocyte proliferation showed strong intra- and inter-individual variability, which reflected variability in activation of the immune status. Furthermore, both immunosuppressive and stimulative influences of metals on lymphocytes were found. Summarising, the methods used in this investigation provided useful information on these animals, and their application to free-ranging animals can be recommended

  12. The Gaia-ESO Survey: the present-day radial metallicity distribution of the Galactic disc probed by pre-main-sequence clusters

    Science.gov (United States)

    Spina, L.; Randich, S.; Magrini, L.; Jeffries, R. D.; Friel, E. D.; Sacco, G. G.; Pancino, E.; Bonito, R.; Bravi, L.; Franciosini, E.; Klutsch, A.; Montes, D.; Gilmore, G.; Vallenari, A.; Bensby, T.; Bragaglia, A.; Flaccomio, E.; Koposov, S. E.; Korn, A. J.; Lanzafame, A. C.; Smiljanic, R.; Bayo, A.; Carraro, G.; Casey, A. R.; Costado, M. T.; Damiani, F.; Donati, P.; Frasca, A.; Hourihane, A.; Jofré, P.; Lewis, J.; Lind, K.; Monaco, L.; Morbidelli, L.; Prisinzano, L.; Sousa, S. G.; Worley, C. C.; Zaggia, S.

    2017-05-01

    Context. The radial metallicity distribution in the Galactic thin disc represents a crucial constraint for modelling disc formation and evolution. Open star clusters allow us to derive both the radial metallicity distribution and its evolution over time. Aims: In this paper we perform the first investigation of the present-day radial metallicity distribution based on [Fe/H] determinations in late type members of pre-main-sequence clusters. Because of their youth, these clusters are therefore essential for tracing the current interstellar medium metallicity. Methods: We used the products of the Gaia-ESO Survey analysis of 12 young regions (age ages is not easily explained by the models. Our results reveal a complex interplay of several processes (e.g. star formation activity, initial mass function, supernova yields, gas flows) that controlled the recent evolution of the Milky Way. Based on observations made with the ESO/VLT, at Paranal Observatory, under program 188.B-3002 (The Gaia-ESO Public Spectroscopic Survey).Full Table 1 is only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/601/A70

  13. Brain Metal Distribution and Neuro-Inflammatory Profiles after Chronic Vanadium Administration and Withdrawal in Mice

    Directory of Open Access Journals (Sweden)

    Oluwabusayo R. Folarin

    2017-07-01

    Full Text Available Vanadium is a potentially toxic environmental pollutant and induces oxidative damage in biological systems including the central nervous system (CNS. Its deposition in brain tissue may be involved in the pathogenesis of certain neurological disorders which after prolonged exposure can culminate into more severe pathology. Most studies on vanadium neurotoxicity have been done after acute exposure but in reality some populations are exposed for a lifetime. This work was designed to ascertain neurodegenerative consequences of chronic vanadium administration and to investigate the progressive changes in the brain after withdrawal from vanadium treatment. A total of 85 male BALB/c mice were used for the experiment and divided into three major groups of vanadium treated (intraperitoneally (i.p. injected with 3 mg/kg body weight of sodium metavanadate and sacrificed every 3 months till 18 months; matched controls; and animals that were exposed to vanadium for 3 months and thereafter the metal was withdrawn. Brain tissues were obtained after animal sacrifice. Sagittal cut sections of paraffin embedded tissue (5 μm were analyzed by the Laser ablation-inductively coupled plasma-mass spectrometry (LA–ICP–MS to show the absorption and distribution of vanadium metal. Also, Haematoxylin and Eosin (H&E staining of brain sections, and immunohistochemistry for Microglia (Iba-1, Astrocytes (GFAP, Neurons (Neu-N and Neu-N + 4′,6-diamidine-2′-pheynylindole dihydrochloride (Dapi Immunofluorescent labeling were observed for morphological and morphometric parameters. The LA–ICP–MS results showed progressive increase in vanadium uptake with time in different brain regions with prediction for regions like the olfactory bulb, brain stem and cerebellum. The withdrawal brains still show presence of vanadium metal in the brain slightly more than the controls. There were morphological alterations (of the layering profile, nuclear shrinkage in the prefrontal

  14. Difference in metallic wear distribution released from commercially pure titanium compared with stainless steel plates.

    Science.gov (United States)

    Krischak, G D; Gebhard, F; Mohr, W; Krivan, V; Ignatius, A; Beck, A; Wachter, N J; Reuter, P; Arand, M; Kinzl, L; Claes, L E

    2004-03-01

    Stainless steel and commercially pure titanium are widely used materials in orthopedic implants. However, it is still being controversially discussed whether there are significant differences in tissue reaction and metallic release, which should result in a recommendation for preferred use in clinical practice. A comparative study was performed using 14 stainless steel and 8 commercially pure titanium plates retrieved after a 12-month implantation period. To avoid contamination of the tissue with the elements under investigation, surgical instruments made of zirconium dioxide were used. The tissue samples were analyzed histologically and by inductively coupled plasma atomic emission spectrometry (ICP-AES) for accumulation of the metals Fe, Cr, Mo, Ni, and Ti in the local tissues. Implant corrosion was determined by the use of scanning electron microscopy (SEM). With grades 2 or higher in 9 implants, steel plates revealed a higher extent of corrosion in the SEM compared with titanium, where only one implant showed corrosion grade 2. Metal uptake of all measured ions (Fe, Cr, Mo, Ni) was significantly increased after stainless steel implantation, whereas titanium revealed only high concentrations for Ti. For the two implant materials, a different distribution of the accumulated metals was found by histological examination. Whereas specimens after steel implantation revealed a diffuse siderosis of connective tissue cells, those after titanium exhibited occasionally a focal siderosis due to implantation-associated bleeding. Neither titanium- nor stainless steel-loaded tissues revealed any signs of foreign-body reaction. We conclude from the increased release of toxic, allergic, and potentially carcinogenic ions adjacent to stainless steel that commercially pure Ti should be treated as the preferred material for osteosyntheses if a removal of the implant is not intended. However, neither material provoked a foreign-body reaction in the local tissues, thus cpTi cannot be

  15. Gold-functionalized DNAzyme Nanosensors to Quantify Heavy Metal Gradients

    Science.gov (United States)

    Adriaens, P.; Vannela, R.

    2005-12-01

    The presence of heavy metals in environmental systems is characterized by steep gradients due to the presence of solid and soluble redox species. The capability to selectively quantify low concentrations of individual redox species continues to present a challenge for site characterization and risk assessment. Recently, DNAzymes, single-stranded DNA molecules with catalytic capabilities that are isolated from random-sequence DNA libraries by ``in vitro selection'', have come to the fore as unique molecular tools for metal detection in aqueous environment. Here we describe the selection and characterization of an RNA-cleaving autocatalytic DNAzyme that links chemical catalysis with real-time fluorescence signaling in the single molecule. From a random pool of 40-nt templates, we have isolated Hg-active DNAzymes using in vitro selection procedures in combination with non-homologous random recombination (NRR). However, significant cleavage was seen for DNA sequences isolated in generation G5. By G8 cycle, more than 32% of the DNA construct was cleaved after 3-h incubation. After eight rounds of selection and amplification, the amount of eluted DNA after respective reaction was found to produce active sequences leading to 32 % catalysis. The introduction of nonhomologous random recombination at 9th cycle yielded drastic increase in catalysis to 55% of the total oligonucleotide pool. DNA sequences from the 9th round of selection (G9) were amplified by PCR and cloned into a vector. DNA sequencing was performed and the M-fold software revealed variety of different families of sequences in the active pool - with DNA-010 sequence being dominant in each family. Similar experiments conducted with As5+ and selection did not show any cleavage until the 8th cycle, with cleavage increasing to 18 % at 14th cycle. Since the catalytic activity can be characterized in terms of metal specificity, speciation and affinity, the catalytic DNA serves as a sensor for a variety of metal ion

  16. Effect of the metal work function on the electrical properties of carbon nanotube network transistors

    International Nuclear Information System (INIS)

    Kim, Un Jeong; Ko, Dae Young; Kil, Joon Pyo; Lee, Jung Wha; Park, Wan Jun

    2012-01-01

    A nearly perfect semiconducting single-walled carbon nanotube random network thin film transistor array was fabricated, and its reproducible transport properties were investigated. The effects of the metal work function for both the source and the drain on the electrical properties of the transistors were systematically investigated. Three different metal electrodes, Al, Ti, and Pd, were employed. As the metal work function increased, p-type behavior became dominant, and the field effect hole mobility dramatically increased. Also, the Schottky barrier of the Ti-nanotube contact was invariant to the molecular adsorption of species in air.

  17. Pair distribution function analysis applied to decahedral gold nanoparticles

    International Nuclear Information System (INIS)

    Nakotte, H; Silkwood, C; Kiefer, B; Karpov, D; Fohtung, E; Page, K; Wang, H-W; Olds, D; Manna, S; Fullerton, E E

    2017-01-01

    The five-fold symmetry of face-centered cubic (fcc) derived nanoparticles is inconsistent with the translational symmetry of a Bravais lattice and generally explained by multiple twinning of a tetrahedral subunit about a (joint) symmetry axis, with or without structural modification to the fcc motif. Unlike in bulk materials, five-fold twinning in cubic nanoparticles is common and strongly affects their structural, chemical, and electronic properties. To test and verify theoretical approaches, it is therefore pertinent that the local structural features of such materials can be fully characterized. The small size of nanoparticles severely limits the application of traditional analysis techniques, such as Bragg diffraction. A complete description of the atomic arrangement in nanoparticles therefore requires a departure from the concept of translational symmetry, and prevents fully evaluating all the structural features experimentally. We describe how recent advances in instrumentation, together with the increasing power of computing, are shaping the development of alternative analysis methods of scattering data for nanostructures. We present the application of Debye scattering and pair distribution function (PDF) analysis towards modeling of the total scattering data for the example of decahedral gold nanoparticles. PDF measurements provide a statistical description of the pair correlations of atoms within a material, allowing one to evaluate the probability of finding two atoms within a given distance. We explored the sensitivity of existing synchrotron x-ray PDF instruments for distinguishing four different simple models for our gold nanoparticles: a multiply twinned fcc decahedron with either a single gap or multiple distributed gaps, a relaxed body-centered orthorhombic (bco) decahedron, and a hybrid decahedron. The data simulations of the models were then compared with experimental data from synchrotron x-ray total scattering. We present our experimentally

  18. Pair distribution function analysis applied to decahedral gold nanoparticles

    Science.gov (United States)

    Nakotte, H.; Silkwood, C.; Page, K.; Wang, H.-W.; Olds, D.; Kiefer, B.; Manna, S.; Karpov, D.; Fohtung, E.; Fullerton, E. E.

    2017-11-01

    The five-fold symmetry of face-centered cubic (fcc) derived nanoparticles is inconsistent with the translational symmetry of a Bravais lattice and generally explained by multiple twinning of a tetrahedral subunit about a (joint) symmetry axis, with or without structural modification to the fcc motif. Unlike in bulk materials, five-fold twinning in cubic nanoparticles is common and strongly affects their structural, chemical, and electronic properties. To test and verify theoretical approaches, it is therefore pertinent that the local structural features of such materials can be fully characterized. The small size of nanoparticles severely limits the application of traditional analysis techniques, such as Bragg diffraction. A complete description of the atomic arrangement in nanoparticles therefore requires a departure from the concept of translational symmetry, and prevents fully evaluating all the structural features experimentally. We describe how recent advances in instrumentation, together with the increasing power of computing, are shaping the development of alternative analysis methods of scattering data for nanostructures. We present the application of Debye scattering and pair distribution function (PDF) analysis towards modeling of the total scattering data for the example of decahedral gold nanoparticles. PDF measurements provide a statistical description of the pair correlations of atoms within a material, allowing one to evaluate the probability of finding two atoms within a given distance. We explored the sensitivity of existing synchrotron x-ray PDF instruments for distinguishing four different simple models for our gold nanoparticles: a multiply twinned fcc decahedron with either a single gap or multiple distributed gaps, a relaxed body-centered orthorhombic (bco) decahedron, and a hybrid decahedron. The data simulations of the models were then compared with experimental data from synchrotron x-ray total scattering. We present our experimentally

  19. Distributed Analysis of Hip Implants Using Six National and Regional Registries: Comparing Metal-on-Metal with Metal-on-Highly Cross-Linked Polyethylene Bearings in Cementless Total Hip Arthroplasty in Young Patients

    Science.gov (United States)

    Furnes, Ove; Paxton, Elizabeth; Cafri, Guy; Graves, Stephen; Bordini, Barbara; Comfort, Thomas; Rivas, Moises Coll; Banerjee, Samprit; Sedrakyan, Art

    2014-01-01

    Background: The regulation of medical devices has attracted controversy recently because of problems related to metal-on-metal hip implants. There is growing evidence that metal-on-metal implants fail early and cause local and systemic complications. However, the failure associated with metal-on-metal head size is not consistently documented and needs to be communicated to patients and surgeons. The purpose of this study is to compare implant survival of metal on metal with that of metal on highly cross-linked polyethylene. Methods: Using a distributed health data network, primary total hip arthroplasties were identified from six national and regional total joint arthroplasty registries (2001 to 2010). Inclusion criteria were patient age of forty-five to sixty-four years, cementless total hip arthroplasties, primary osteoarthritis diagnosis, and exclusion of the well-known outlier implant ASR (articular surface replacement). The primary outcome was revision for any reason. A meta-analysis of survival probabilities was performed with use of a fixed-effects model. Metal-on-metal implants with a large head size of >36 mm were compared with metal-on-highly cross-linked polyethylene implants. Results: Metal-on-metal implants with a large head size of >36 mm were used in 5172 hips and metal-on-highly cross-linked polyethylene implants were used in 14,372 hips. Metal-on-metal total hip replacements with a large head size of >36 mm had an increased risk of revision compared with metal-on-highly cross-linked polyethylene total hip replacements with more than two years of follow-up, with no difference during the first two years after implantation. The results of the hazard ratios (and 95% confidence intervals) from the multivariable model at various durations of follow-up were 0.95 (0.74 to 1.23) at zero to two years (p = 0.698), 1.42 (1.16 to 1.75) at more than two years to four years (p = 0.001), 1.78 (1.45 to 2.19) at more than four years to six years (p implants and

  20. Distribution of metals and extent of contamination in sediments from the south-eastern Baltic Sea (Lithuanian zone

    Directory of Open Access Journals (Sweden)

    Nijolė Remeikaitė-Nikienė

    2018-04-01

    Full Text Available Summary: The distribution of metals (Pb, Cu, Cd, Ni, Cr, Zn in surface sediments and the potential pollution sources in the south-eastern part (SE of the Baltic Sea (Lithuanian zone were investigated in relation to the environmental characteristics (amount of fine-grained particles, TOC content in sediments, origin of sedimentary organic matter, salinity, water depth in 2011–2014. The higher metal concentrations were measured in sediments of the Curonian Lagoon and in the open waters. An approach using various environmental indices (enrichment factor EF, geoaccumulation index Igeo and contamination factor CF was used to quantitatively assess a contamination degree. The principal component analysis (PCA was applied in order to further scrutinize pollution from metal sources. The values of the contamination indices showed no/very low sediment contamination with Ni and Cr, minor–moderate contamination with Cu, Zn and Pb and moderate–considerable pollution with Cd. The strong relationships among metals suggested their similar distribution pattern and a combination of natural and anthropogenic sources. The higher metal concentrations coincided with an increasing amount of fine-grained fraction and organic carbon. In the territorial waters, the distribution of elements was related to the water depth. In addition, the binding of metals with insoluble iron sulphides might explain their high concentrations at the most remote and deepest stations. Keywords: Metals, Enrichment factor, Geoaccumulation index, Contamination factor, The Baltic Sea, The Curonian Lagoon

  1. Trace metal distribution in the Arosa estuary (N.W. Spain): The application of a recently developed sequential extraction procedure for metal partitioning

    Energy Technology Data Exchange (ETDEWEB)

    Santamaria-Fernandez, Rebeca [School of Earth, Ocean and Environmental Sciences, University of Plymouth, Plymouth, PL4 8AA (United Kingdom); Cave, Mark R. [British Geological Survey, Keyworth, Nottingham, NG12 5GG (United Kingdom); Hill, Steve J. [School of Earth, Ocean and Environmental Sciences, University of Plymouth, Plymouth, PL4 8AA (United Kingdom)]. E-mail: SJHill@plymouth.ac.uk

    2006-01-31

    A study of the trace metal distribution in sediment samples from the Galician coast (Spain) has been performed. A multielement extraction method optimised via experimental design has been employed. The method uses centrifugation to pass the extractant solution at varying pH, through the sediment sample. The sequential leaches were collected and analysed by ICP-AES. Chemometric approaches were utilised to identify the composition of the physico-chemical components in order to characterise the sample. The samples collected at different sites could be classified according to their differences in metal bio-availability and important information regarding element distribution within the physico-chemical components is given. The method has proved to be a quick and reliable way to evaluate sediment samples for environmental geochemistry analysis. In addition, this approach has potential as fast screening method for the bio-availability of metals in the environment.

  2. Study on the Effects of Irrigation with Reclaimed Water on the Content and Distribution of Heavy Metals in Soil

    Directory of Open Access Journals (Sweden)

    Shibao Lu

    2016-03-01

    Full Text Available Reclaimed water is an important resource for irrigation, and exploration in making full use of it is an important way to alleviate water shortage. This paper analyzes the effects of irrigation with reclaimed water through field trials on the content and distribution of heavy metals in both tomatoes and the soil. By exploring the effects of reclaimed water after secondary treatment on the content and distribution characteristics of heavy metals in tomatoes and the heavy metal balance in the soil-crop system under different conditions, the study shows that there are no significant differences in the heavy metal content when the quantity of reclaimed water for irrigation varies. Reclaimed water for short-term irrigation does not cause pollution to either the soil environment or the crops. Nor will it cause the accumulation of heavy metals, and the index for the heavy metal content is far below the critical value of the national standard, which indicates that the vegetables irrigated with reclaimed water during their growth turn out to be free of pollutants. The heavy metals brought into the soil by reclaimed water are less than that taken away by the crops. The input and output quantities have only small effects on the heavy metal balance in the soil. This paper provides a reference for the evaluation and safety control of irrigation with reclaimed water.

  3. Distribution and Identification of Sources of Heavy Metals in the Voghji River Basin Impacted by Mining Activities (Armenia

    Directory of Open Access Journals (Sweden)

    A. V. Gabrielyan

    2018-01-01

    Full Text Available The objective of this research is to assess the distribution of heavy metals in the waters and sediments of the Voghji River and its tributaries impacted by mining activity and to reveal the real source of each of the heavy metals in the environment for assessing the pollution level of heavy metals. Voghji River with two main tributaries (Geghi and Norashenik drain two mining regions. To identify distribution and pollution sources of heavy metals, the water and sediment samples were collected from eight sampling sites. The results of statistical analysis based on data sets of the period 2014–2016 showed that, after the influence of drainage water and wastewater of mining regions, heavy metal contents in the Voghji River basin dramatically increased. The waters of the Voghji River were highly polluted by Mn, Co, Cu, Zn, Mo, Cd, and Pb. The relation of metals content was highly changed due to anthropogenic impact disturbing the geochemical balance of the Voghji River. The water quality based on only heavy metal contents in the source of the Voghji River belongs to “good” chemical status, and in the sources of Geghi and Norashenik Rivers it is “moderate.” The water quality of Voghji and Norashenik Rivers is sharply worsening after the influence of mining activity, becoming “bad” chemical status. The research revealed the pollution sources of each metal.

  4. Dithiocarbamate Self-Assembled Monolayers as Efficient Surface Modifiers for Low Work Function Noble Metals

    Energy Technology Data Exchange (ETDEWEB)

    Meyer, Dominik; Schäfer, Tobias; Schulz, Philip; Jung, Sebastian; Rittich, Julia; Mokros, Daniel; Segger, Ingolf; Maercks, Franziska; Effertz, Christian; Mazzarello, Riccardo; Wuttig, Matthias

    2016-09-06

    Tuning the work function of the electrode is one of the crucial steps to improve charge extraction in organic electronic devices. Here, we show that N,N-dialkyl dithiocarbamates (DTC) can be effectively employed to produce low work function noble metal electrodes. Work functions between 3.1 and 3.5 eV are observed for all metals investigated (Cu, Ag, and Au). Ultraviolet photoemission spectroscopy (UPS) reveals a maximum decrease in work function by 2.1 eV as compared to the bare metal surface. Electronic structure calculations elucidate how the complex interplay between intrinsic dipoles and dipoles induced by bond formation generates such large work function shifts. Subsequently, we quantify the improvement in contact resistance of organic thin film transistor devices with DTC coated source and drain electrodes. These findings demonstrate that DTC molecules can be employed as universal surface modifiers to produce stable electrodes for electron injection in high performance hybrid organic optoelectronics.

  5. Distributed stimulation increases force elicited with functional electrical stimulation

    Science.gov (United States)

    Buckmire, Alie J.; Lockwood, Danielle R.; Doane, Cynthia J.; Fuglevand, Andrew J.

    2018-04-01

    Objective. The maximum muscle forces that can be evoked using functional electrical stimulation (FES) are relatively modest. The reason for this weakness is not fully understood but could be partly related to the widespread distribution of motor nerve branches within muscle. As such, a single stimulating electrode (as is conventionally used) may be incapable of activating the entire array of motor axons supplying a muscle. Therefore, the objective of this study was to determine whether stimulating a muscle with more than one source of current could boost force above that achievable with a single source. Approach. We compared the maximum isometric forces that could be evoked in the anterior deltoid of anesthetized monkeys using one or two intramuscular electrodes. We also evaluated whether temporally interleaved stimulation between two electrodes might reduce fatigue during prolonged activity compared to synchronized stimulation through two electrodes. Main results. We found that dual electrode stimulation consistently produced greater force (~50% greater on average) than maximal stimulation with single electrodes. No differences, however, were found in the fatigue responses using interleaved versus synchronized stimulation. Significance. It seems reasonable to consider using multi-electrode stimulation to augment the force-generating capacity of muscles and thereby increase the utility of FES systems.

  6. Radial Distribution Functions of Strongly Coupled Two-Temperature Plasmas

    Science.gov (United States)

    Shaffer, Nathaniel R.; Tiwari, Sanat Kumar; Baalrud, Scott D.

    2017-10-01

    We present tests of three theoretical models for the radial distribution functions (RDFs) in two-temperature strongly coupled plasmas. RDFs are useful in extending plasma thermodynamics and kinetic theory to strong coupling, but they are usually known only for thermal equilibrium or for approximate one-component model plasmas. Accurate two-component modeling is necessary to understand the impact of strong coupling on inter-species transport, e.g., ambipolar diffusion and electron-ion temperature relaxation. We demonstrate that the Seuferling-Vogel-Toeppfer (SVT) extension of the hypernetted chain equations not only gives accurate RDFs (as compared with classical molecular dynamics simulations), but also has a simple connection with the Yukawa OCP model. This connection gives a practical means to recover the structure of the electron background from knowledge of the ion-ion RDF alone. Using the model RDFs in Effective Potential Theory, we report the first predictions of inter-species transport coefficients of strongly coupled plasmas far from equilibrium. This work is supported by NSF Grant No. PHY-1453736, AFSOR Award No. FA9550-16-1-0221, and used XSEDE computational resources.

  7. Algorithm for systematic peak extraction from atomic pair distribution functions.

    Science.gov (United States)

    Granlund, L; Billinge, S J L; Duxbury, P M

    2015-07-01

    The study presents an algorithm, ParSCAPE, for model-independent extraction of peak positions and intensities from atomic pair distribution functions (PDFs). It provides a statistically motivated method for determining parsimony of extracted peak models using the information-theoretic Akaike information criterion (AIC) applied to plausible models generated within an iterative framework of clustering and chi-square fitting. All parameters the algorithm uses are in principle known or estimable from experiment, though careful judgment must be applied when estimating the PDF baseline of nanostructured materials. ParSCAPE has been implemented in the Python program SrMise. Algorithm performance is examined on synchrotron X-ray PDFs of 16 bulk crystals and two nanoparticles using AIC-based multimodeling techniques, and particularly the impact of experimental uncertainties on extracted models. It is quite resistant to misidentification of spurious peaks coming from noise and termination effects, even in the absence of a constraining structural model. Structure solution from automatically extracted peaks using the Liga algorithm is demonstrated for 14 crystals and for C60. Special attention is given to the information content of the PDF, theory and practice of the AIC, as well as the algorithm's limitations.

  8. Distribution functions for resonantly trapped orbits in the Galactic disc

    Science.gov (United States)

    Monari, Giacomo; Famaey, Benoit; Fouvry, Jean-Baptiste; Binney, James

    2017-11-01

    The present-day response of a Galactic disc stellar population to a non-axisymmetric perturbation of the potential has previously been computed through perturbation theory within the phase-space coordinates of the unperturbed axisymmetric system. Such an Eulerian linearized treatment, however, leads to singularities at resonances, which prevent quantitative comparisons with data. Here, we manage to capture the behaviour of the distribution function (DF) at a resonance in a Lagrangian approach, by averaging the Hamiltonian over fast angle variables and re-expressing the DF in terms of a new set of canonical actions and angles variables valid in the resonant region. We then follow the prescription of Binney, assigning to the resonant DF the time average along the orbits of the axisymmetric DF expressed in the new set of actions and angles. This boils down to phase-mixing the DF in terms of the new angles, such that the DF for trapped orbits depends only on the new set of actions. This opens the way to quantitatively fitting the effects of the bar and spirals to Gaia data in terms of DFs in action space.

  9. Synchrotron Radiation Pair Distribution Function Analysis of Gels in Cements

    Directory of Open Access Journals (Sweden)

    Ana Cuesta

    2017-10-01

    Full Text Available The analysis of atomic ordering in a nanocrystalline phase with small particle sizes, below 5 nm, is intrinsically complicated because of the lack of long-range order. Furthermore, the presence of additional crystalline phase(s may exacerbate the problem, as is the case in cement pastes. Here, we use the synchrotron pair distribution function (PDF chiefly to characterize the local atomic order of the nanocrystalline phases, gels, in cement pastes. We have used a multi r-range analysis approach, where the ~4–7 nm r-range allows determining the crystalline phase contents; the ~1–2.5 nm r-range is used to characterize the atomic ordering in the nanocrystalline component; and the ~0.2–1.0 nm r-range gives insights about additional amorphous components. Specifically, we have prepared four alite pastes with variable water contents, and the analyses showed that a defective tobermorite, Ca11Si9O28(OH2.8.5H2O, gave the best fit. Furthermore, the PDF analyses suggest that the calcium silicate hydrate gel is composed of this tobermorite and amorphous calcium hydroxide. Finally, this approach has been used to study alternative cements. The hydration of monocalcium aluminate and ye’elimite pastes yield aluminum hydroxide gels. PDF analyses show that these gels are constituted of nanocrystalline gibbsite, and the particle size can be as small as 2.5 nm.

  10. Implication of heavy metals distribution for a municipal solid waste management system - a case study in Shanghai

    International Nuclear Information System (INIS)

    Zhang Hua; He Pinjing; Shao Liming

    2008-01-01

    Heavy metal contamination in municipal solid waste (MSW) is of increasing concern. The occurrence and distribution of heavy metals in MSW and their implications for the integrated MSW management system in mega-cities have been investigated by means of material flow analysis based on a case study of Shanghai in China. A good statistical basis was provided through a one-year monitoring program on the mass and metals composition of the waste from three MSW treatment facilities. The results showed that the main heavy metals in the MSW were Zn, Cr, Cu, and Pb (on average > 100 mg kg -1 ), followed by Ni, Cd, and Hg. The MSW contained higher levels of Cu and Ni in metals, Cr and Pb in plastics, and Pb and Zn in the inorganic fractions. Regardless of the sources, the statistically similar heavy metal contents in the organic fractions indicated that effective blending and diffusion of heavy metals had taken place throughout the MSW collection, transfer, transportation, and storage, leading to cross-contamination of the waste fractions. PU (composed of putrescible waste and miscellaneous indistinguishable particles) contributed the majority of the heavy metals to the MSW, followed by plastics, as a result of the predominance in the overall composition of PU and plastics rather than from differences in their heavy metal contents. Therefore, manual or mechanical separation of some significantly heavy metal-rich fractions alone is not sufficient to reduce the heavy metal contents in the MSW. Source separation of organic waste and the diversion of tailored inorganic waste such as hazardous components, construction and demolition waste, etc., are proposed to control the heavy metal contamination in MSW. For the mixed MSW management system, physicochemical fractionation to exclude particles containing high levels of heavy metals can be conducted

  11. Graphene on metals: A van der Waals density functional study

    DEFF Research Database (Denmark)

    Vanin, Marco; Mortensen, Jens Jørgen; Kelkkanen, Kari André

    2010-01-01

    We use density functional theory (DFT) with a recently developed van der Waals density functional (vdW-DF) to study the adsorption of graphene on Co, Ni, Pd, Ag, Au, Cu, Pt, and Al(111) surfaces. In contrast to the local-density approximation (LDA) which predicts relatively strong binding for Ni...

  12. The effects of pH and concentration on heavy metal speciation and mobility, and its relation to heavy metal hyperaccumulation and distribution in selected native Australian flora

    International Nuclear Information System (INIS)

    Menon, D.D.; McPhail, D.C.; Hallam, N.

    2000-01-01

    Full text: The purpose of this research is to establish a clearer understanding of the relations that exist between heavy metal activity, speciation, bioavailability and their uptake and spatial distribution into plants. A combination of experimental modeling and pot trials using toxic heavy metals (cadmium, lead, mercury, copper, chromium and zinc) will be carried out. In the experiments, selected native Australian flora (Eucalyptus, Acacia, Atriplex) adapted to adverse environmental conditions will be used. Varying external factors such as pH, and metal concentration altered the composition of heavy metal speciation in the soil solution. Mathematical and geochemical (PHREEQC) models were used to vary these factors and emulate the conditions under which experimentation will be taking place. These variations help determine the possible heavy metal speciation that would occur in both soil and hydroponic based experiments under given conditions. The rhizosphere, soil solution and the plant material will be analysed by Inductively Coupled Plasma Mass Spectroscopy (ICPMS). Proton Ion X-ray Emission (PIXE) and Secondary Ion Mass spectrometry will help ascertain the distribution, concentration of heavy metal taken up into plant tissues. Information derived from these data will be used to determine and understand how varying such environmental conditions and hence heavy metal speciation affect their bioavailability in the medium, and how their acceptance, accumulation and storage within the selected flora. Preliminary experimentation showed that, for lead and cadmium, the variation in soil solution pH affected the quantity of heavy metal accumulated into selected native Australian flora. ICP-MS analysis of plants subjected to a known soil solution spiked with 200 μmol of lead and cadmium showed that the quantities of lead and cadmium accumulated into plant sections (roots, stems and leaves) varied in the selected woody species. A. heteroclita, A. saligna, and A

  13. On-Surface Synthesis and Reactivity of Functional Organic and Metal-Organic Adsorbates at Metal Surfaces by Vibrational Spectroscopy

    Science.gov (United States)

    Williams, Christopher Glen

    Surface self-assembly is a promising way to introduce functionality to a surface through design at the molecular level. These self-assembled species allow for new on-surface type reactions to be observed and studied. The experiments described in this thesis demonstrate that the molecules used in self-assembly can potentially lead to interesting synthesis pathways and can be used to explore previously under-researched reaction pathways and surface molecular architecture activity or stability. Alkanes are an unreactive species typically used for driving molecular assembly in surface structures. However, with molecular design, alkanes are capable of reacting on surfaces not typically associated with alkane reactivity. Utilizing high-resolution electron energy loss spectroscopy (HREELS) and octaethylporphyrin, we could observe that dehydrogenation is possible on Cu(100) and Ag(111) surfaces at 500 and 610 K respectively. HREELS revealed that after the dehydrogenation, the molecule undergoes an intramolecular C-C bond formation leading to a tetrabenzo-porphyrin structure. Controls with deposited tetrabenzo-porphyrin were performed to verify the structure. This work provides the first example of dehydrocyclization on Cu(100) and Ag(111) to be analyzed by vibrational spectroscopy. Alkyl species in the 1,3,5-tris-(3,5-diethylphenyl)benzene molecule also undergo a dehydrogenation on Cu(100) and Au(111) at 450 and 500 K. The design of this molecule does not let the intramolecular dehydrocyclization reaction take place, but instead the dehydrogenation leads to intermolecular C-C bond formation between molecular species as noted by the formation of extended structure across the surface. Controls with triphenyl-benzene were done to help characterize the peaks in the spectra and observe varying reactivity when the ethyl groups are absent. The fabrication of uniform single-site metal centers at surfaces is important for higher selectivity in next-generation heterogeneous

  14. [Distribution of heavy metals in waters and pollution assessment in thallium contaminated area of Yunfu, Guangdong].

    Science.gov (United States)

    Li, Xiang-ping; Qi, Jian-ying; Wang, Chun-lin; Chen, Yong-heng

    2011-05-01

    Distribution of Thallium(T1), Cadmium( Cd), Chromium (Cr), Lead (Pb), Nickel (Ni), Arsenic (As), Copper (Cu), Zinc (Zn) in water and sediments of Yunfu pyrite mine area was studied. The environmental risk assessment was conducted systematically using Sediment Quality Guidelines (SQGs) and Hakanson potential ecological risk index. The results indicated that concentration range of Tl in stream water was 0.19-65.25 microg/L, which is higher than the environmental quality standards for surface water. Concentration ranges of Tl, Zn, As, Cd, Pb in sediments were 5.89-63.0 mg/kg, 1215-5754 mg/kg, 208.4-1327 mg/kg, 4.20-17.5 mg/kg, 282-13,770 mg/kg. According to Sediments Quality Guidelines, sediments was moderately to severe level of pollution since concentrations of Tl, Cd, Cr, Pb, Ni, As, Cu, Zn were much higher than LEL (lowest effect level) values, and the concentrations of Pb, As, Zn were higher than SEL (severe effect level) values, the others were partly higher than SEL values, which may result in severe negative biota effects in the watersheds. Compared to soil background values of Guangdong province, the metals in stream sediment showed strong to severe strong ecological risk, and the ecological risk of heavy metals in the descending order of Tl, Cd, As, Pb, Cr, Ni, Zn and Cu. Besides, the sediments were severe contained by toxic element thallium and cadmium. Besides, the mainly ecological risk of heavy metal is thallium. More emphasis should be placed on thallium and cadmium control and disposal in

  15. Heavy metal distribution at dump-field Ľubietová – Podlipa

    Directory of Open Access Journals (Sweden)

    Peter Andráš

    2009-09-01

    Full Text Available The article present the results of the environmental study at the Ľubietová Podlipa dump-field. The distribution of the selectedelements and heavy metals is unequal and depend on the geochemical behaviour of the elements (mainly on their migration ability.The present natural sorbents are predominantly the clay minerals (illite, muscovite, caolinite, smectite and hydrogoethite. The clay mineralsare good sorbents of K, Na, Li, Al, Rb, Sr, Hf, V, Cr, Ti, W, Zr, Nb, Ta a Th and at the hydrogoethite of Cu, Zn, Mo, Mn, Mg, P (± Fe, Cd,Co, Ca. In the case of the Fe, As, Sb, Ag, Pb, Zn, Mn, Mo, Bi, U was proved also the free sorption capacity.

  16. Mass spectrometric probes of metal cluster distributions and metastable ion decay

    International Nuclear Information System (INIS)

    Parks, E.K.; Liu, K.; Cole, S.K.; Riley, S.J.

    1988-01-01

    The study of metal clusters has provided both an opportunity and a challenge to the application of mass spectrometry. These days the most often-used technique for cluster generation - laser vaporization - leads to extensive distributions of cluster sizes, from one to perhaps thousands of atoms, and most studies reported to date use excimer laser ionization and time-of-flight mass spectrometry for cluster detection. Our apparatus is a simple one-stage TOF design employing Wiley-McLauren spatial focusing and a one-meter drift tube. In a second apparatus employing a pulsed valve in the cluster source, we see asymmetric broadening of niobium cluster mass peaks under multiphoton ionization conditions, indicating metastable decay of parent cluster ions. Other studies of niobium clusters have shown no such asymmetric peaks. 2 figs

  17. Antibodies labeled with metallic radionuclides: influence of nuclide chemistry on dose distribution

    International Nuclear Information System (INIS)

    Vaughan, A.T.; Yankuba, S.C.; Anderson, P.

    1987-01-01

    An antibody with human CEA specificity has been labeled with either yttrium-90, scandium-47, or indium-111, via a diethylenetriamine pentaacetic acid (DTPA) link covalently bound to the protein. The clearance of these proteins from the blood of mice can be described by a single exponential; the half-life decreases in the order indium-111 greater than yttrium-90 greater than scandium-47. Associated with the blood clearance is an uptake of radioactivity into the liver; scandium-47 has the highest concentration, indium-111 has the least, and yttrium-90 is intermediate. There is no correlation between these results and the equilibrium stability constants of the metals with DTPA-like ligands. The results obtained show that, in vivo, scandium-47 and yttrium-90 are more easily displaced from DTPA by other ions than is indium-111. They also show that free DTPA is able to extract yttrium-90 and scandium-47, but not indium-111, from the liver of treated animals, indicating that indium-111 is resistant to ligand exchange reactions in vivo. These data indicate that 1) the equilibrium stability constant is not a good indicator of the in vivo stability of metal-labeled proteins and 2) it is possible to manipulate the ion distribution and therefore the dose from scandium-47 and yttrium-90 after injection of the labeled proteins

  18. Distribution and temporal variation of trace metal enrichment in surface sediments of San Jorge Bay, Chile.

    Science.gov (United States)

    Valdés, Jorge; Román, Domingo; Guiñez, Marcos; Rivera, Lidia; Morales, Tatiana; Morales, Tomás; Avila, Juan; Cortés, Pedro

    2010-08-01

    Cu, Pb, and Hg concentrations were determined in surface sediment samples collected at three sites in San Jorge Bay, northern Chile. This study aims to evaluate differences in their spatial distribution and temporal variability. The highest metal concentrations were found at the site "Puerto", where minerals (Cu and Pb) have been loaded for more than 60 years. On the other hand, Hg does not pose a contamination problem in this bay. Cu and Pb concentrations showed significant variations from 1 year to another. These variations seem to be a consequence of the combination of several factors, including changes in the loading and/or storage of minerals in San Jorge Bay, the dredging of bottom sediments (especially at Puerto), and seasonal changes in physical-chemical properties of the water column that modify the exchange of metals at the sediment-water interface. Differences in the contamination factor and geoaccumulation index suggest that pre-industrial concentrations measured in marine sediments of this geographical zone, were better than geological values (average shale, continental crust average) for evaluating the degree of contamination in this coastal system. Based on these last two indexes, San Jorge Bay has a serious problem of Cu and Pb pollution at the three sampling locations. However, only Cu exceeds the national maximum values used to evaluate ecological risk and the health of marine environments. It is suggested that Chilean environmental legislation for marine sediment quality--presently under technical discussion--is not an efficient tool for protecting the marine ecosystem.

  19. Covalent functionalization of carbon nanotube forests grown in situ on a metal-silicon chip

    KAUST Repository

    Johansson, Johan R.

    2012-03-12

    We report on the successful covalent functionalization of carbon nanotube (CNT) forests, in situ grown on a silicon chip with thin metal contact film as the buffer layer between the CNT forests and the substrate. The CNT forests were successfully functionalized with active amine and azide groups, which can be used for further chemical reactions. The morphology of the CNT forests was maintained after the functionalization. We thus provide a promising foundation for a miniaturized biosensor arrays system that can be easily integrated with Complementary Metal-Oxide Semiconductor (CMOS) technology.

  20. Distribution of trace metals at Hopewell Furnace National Historic Site, Berks and Chester Counties, Pennsylvania

    Science.gov (United States)

    Sloto, Ronald A.; Reif, Andrew G.

    2011-01-01

    Hopewell Furnace, located approximately 50 miles northwest of Philadelphia, was a cold-blast, charcoal iron furnace that operated for 113 years (1771 to 1883). The purpose of this study by the U.S. Geological Survey, in cooperation with the National Park Service, was to determine the distribution of trace metals released to the environment from an historical iron smelter at Hopewell Furnace National Historic Site (NHS). Hopewell Furnace used iron ore from local mines that contained abundant magnetite and accessory sulfide minerals enriched in arsenic, cobalt, copper, and other metals. Ore, slag, cast iron furnace products, soil, groundwater, stream base flow, streambed sediment, and benthic macroinvertebrates were sampled for this study. Soil samples analyzed in the laboratory had concentrations of trace metals low enough to meet Pennsylvania Department of Environmental Protection standards for non-residential use. Groundwater samples from the supply well met U.S. Environmental Protection Agency drinking-water regulations. Concentrations of metals in surface-water base flow at the five stream sampling sites were below continuous concentration criteria for protection of aquatic organisms. Concentrations of metals in sediment at the five stream sites were below probable effects level guidelines for protection of aquatic organisms except for copper at site HF-3. Arsenic, copper, lead, zinc, and possibly cobalt were incorporated into the cast iron produced by Hopewell Furnace. Manganese was concentrated in slag along with iron, nickel, and zinc. The soil near the furnace has elevated concentrations of chromium, copper, iron, lead, and zinc compared to background soil concentrations. Concentrations of toxic elements were not present at concentrations of concern in water, soil, or stream sediments, despite being elevated in ore, slag, and cast iron furnace products. The base-flow surface-water samples indicated good overall quality. The five sampled sites generally had

  1. Contamination and distribution of heavy metals, polybrominated diphenyl ethers and alternative halogenated flame retardants in a pristine mangrove.

    Science.gov (United States)

    Wu, Qihang; Leung, Jonathan Y S; Tam, Nora F Y; Peng, Yisheng; Guo, Pengran; Zhou, Song; Li, Qing; Geng, Xinhua; Miao, Shenyu

    2016-02-15

    Owing to the expanding metal and electronics industries, pollution in the Pearl River Estuary needs special concern. Given the hydrodynamic effect, the pristine mangrove in Qi'ao Island would be contaminated by tidal flushing. Thus, we examined (1) the contamination of pollutants in this mangrove, including heavy metals, polybrominated diphenyl ethers (PBDEs) and alternative halogenated flame retardants (AHFRs), and (2) how habitat characteristics and sediment properties affect their distribution. Results showed that the sediment in Qi'ao mangrove had higher concentrations of heavy metals, PBDEs and AHFRs than that in other pristine mangroves, and similar concentrations to those mangroves impacted by point sources. Heavy metal concentrations were lower in the vegetated areas than mudflat, while the opposite was found for PBDEs and AHFRs. The findings imply that tidal flushing was an important pollution source, while mangrove plants have the capacity to minimize the impact of heavy metals, but not PBDEs and AHFRs. Copyright © 2015 Elsevier Ltd. All rights reserved.

  2. Analytical expression for high-frequency dielectric function of metals at moderate temperatures

    Science.gov (United States)

    Veysman, M. E.; Röpke, G.; Reinholz, H.

    2018-01-01

    Analytical expressions are derived for the dielectric function of metals at moderate temperatures, determined by electron–phonon interactions, taking a quantum statistical approach and linear response theory as a basis. The obtained formulas permit one to calculate an effective electron–phonon collision frequency and the dielectric function of two-temperature plasmas for arbitrary laser radiation frequencies. Different limiting cases are considered.

  3. Work function anisotropy and surface stability of half-metallic CrO(2)

    NARCIS (Netherlands)

    Attema, J. J.; Uijttewaal, M. A.; de Wijs, G. A.; de Groot, R. A.

    Insight in the interplay between work function and stability is important for many areas of physics. In this paper, we calculate the anisotropy in the work function and the surface stability of CrO(2), a prototype half-metal, and find an anisotropy of 3.8 eV. An earlier model for the relation

  4. Metal-free ferromagnetic metal and intrinsic spin semiconductor: two different kinds of SWCNT functionalized BN nanoribbons.

    Science.gov (United States)

    Lou, Ping

    2015-03-28

    Two different kinds of SWCNT functionalized zigzag edge BN nanoribbons with n chains (n-ZBNNRs), namely, (a) B-edge functionalized by (m,m)SWCNT and N-edge modified with H (nZBNNR-B-(m,m)SWCNTs); and (b) the B-edge modified with H and the N-edge functionalized by (m,m)SWCNT (nZBNNR-N-(m,m)SWCNTs), have been predicted. Amazingly, we find that unlike the semiconducting and nonmagnetic H-modified n-ZBNNRs, the nZBNNR-B-(m,m)SWCNTs are intrinsic ferromagnetic metals, regardless of ribbon widths n and tube diameters (m,m). At a given (m,m), their local magnetic moments, at first, exhibit oscillation with increasing n, whereas when n is larger than 5, they are independent of n. In contrast, unlike the metallic and nonmagnetic (m,m)SWCNTs, the nZBNNR-N-(m,m)SWCNTs are ferromagnetic intrinsic spin-semiconductors with direct band gaps, regardless of n and (m,m). Their local magnetic moments and band gaps are independent of n and (m,m). The DFT calculations reveal that the process of SWCNT functionalization of the n-ZBNNRs does not need any activation energy. Moreover, the formation energies of the SWCNT functionalized n-ZBNNRs are always less than zero. Therefore, the SWCNT functionalized n-ZBNNRs are not only stable, but can also be spontaneously formed. Furthermore, compared with n-ZBNNRs, the SWCNT functionalized n-ZBNNRs show significant improvements in their thermal and mechanical stabilities. Thus, (m,m)SWCNT functionalization of n-ZBNNRs may open new routes toward practical nanoelectronic and optoelectronic as well as spintronic devices based on BNC-based materials.

  5. A preliminary investigation of the distribution of heavy metals in surface sediments of the Cona tidal marsh (Venice Lagoon)

    International Nuclear Information System (INIS)

    Bernardi, S.; Costa, F.; Vazzoler, S.; Zonta, R.

    1988-01-01

    Data are from the two series of surface sediment sampling in an interface area between the Venice Lagoon and the mainland. The distribution of heavy metals gives a correlation with polluted sourcesites-identified in the channel systems with a highly polluted input-and allows us to identify the localities of accumulation. Restricted to the estuary of the river tributary transporting a high concentration of pollutants into a tidal marsh area of the lagoon, the study shows the effect of the fresh water forcing to distribute heavy metals on surface sediments. Within the scope of this preliminary investigation, indications from sampling identify a sector of the 'palude of Cona' in this estuary, which is highly suitable for detailed studies on precesses affecting heavy-metal distributions in bottom surface sediments of shallow-water areas

  6. Synthesis and metal binding properties of salicylate-, catecholate-, and hydroxypyridinonate-functionalized dendrimers.

    Science.gov (United States)

    Cohen, S M; Petoud, S; Raymond, K N

    2001-01-05

    The synthesis, characterization, and metal-binding studies of chelate-functionalized dendrimers is reported. Salicylate, catecholate, and hydroxypyridinonate bidentate chelators have been coupled to the surface of both poly(propyleneimine) (Astramol) and poly(amidoamine) (Starburst, PAMAM) dendrimers up to the fifth generation (64 endgroups). A general method has been developed for the facile and high quality chromatographic purification of poly(propyleneimine) and poly(amidoamine) dendrimer derivatives. One- and two-dimensional (TOCSY) 1H NMR experiments and electrospray ionization mass spectrometry (ESI-MS) have confirmed the exhaustive coupling of these chelators to the primary amine functionalities of the dendrimers. Spectrophotometric titrations were used to investigate the metal binding ability of these macrochelates. Spectral analysis shows that ferric iron binding to these ligands is localized to the chelating endgroups. The ability of these dendritic polymers to bind large numbers of metal ions may lead to applications as metal sequestering agents for waste remediation technologies.

  7. Functional nucleic acid-based sensors for heavy metal ion assays.

    Science.gov (United States)

    Zhu, Guichi; Zhang, Chun-yang

    2014-12-21

    Heavy metal contaminants such as lead ions (Pb(2+)), mercury ions (Hg(2+)) and silver ions (Ag(+)) can cause significant harm to humans and generate enduring bioaccumulation in ecological systems. Even though a variety of methods have been developed for Pb(2+), Hg(2+) and Ag(+) assays, most of them are usually laborious and time-consuming with poor sensitivity. Due to their unique advantages of excellent catalytic properties and high affinity for heavy metal ions, functional nucleic acids such as DNAzymes and aptamers show great promise in the development of novel sensors for heavy metal ion assays. In this review, we summarize the development of functional nucleic acid-based sensors for the detection of Pb(2+), Hg(2+) and Ag(+), and especially focus on two categories including the direct assay and the amplification-based assay. We highlight the emerging trends in the development of sensitive and selective sensors for heavy metal ion assays as well.

  8. On the distribution of metals deposited onto the limiter and the liner of tokamaks after long-term operation

    International Nuclear Information System (INIS)

    Wolff, H.; Grote, H.; Herrmann, A.; Hildebrandt, D.; Laux, M.; Pech, P.; Reiner, H.D.; Ziegenhagen, G.; Chicherov, V.M.; Grashin, S.A.; Kopecky, V.; Jakubka, K.

    1987-01-01

    Three inspections of the inner parts of the discharge vessels of T-10 and TM1-MH after long-term operation revealed that metals originating from the various construction materials are distributed inhomogeneously over the first wall of these tokamaks. This partially allows one to identify local metal sources and to indicate anisotropies of the transport. Different materials from inner structures, even if they were only used in earlier experiments, are observed at all limiter surfaces and as components of the debris consisting of macroparticles of different size, shape and elemental composition. There are metallic deposits of the form of structured films or of solidified droplets. (orig.)

  9. Spatiotemporal Distribution of Metals along a Salinity Gradient in a River Estuary of the Northern Gulf of Mexico

    Science.gov (United States)

    He, S.; Xu, Y. J.

    2015-12-01

    Saltwater intrusion has become a significant problem for many coastal rivers due to global climate change and the continuous sea level rise. The flocculation of dissolved metals during estuarine mixing plays a critical role in self-purification of metals. A number of studies have investigated pH and salinity effects on metal mobility. Many of these studies were conducted in a laboratory setting. The reported field studies considered only few metals and their dynamics under marginal pH / salinity variation, typically over a short period of time. Since the spring of 2013, we have been conducting a study on spatiotemporal distribution of metals along a 90-km reach of the Calcasieu River estuary in the northern Gulf of Mexico. Monthly field trips were made to conduct in-situ measurements and collect water samples at six sites along the river. In addition, sediment samples from the riverbed surface were collected at the same sites four times to assess metal accumulation. Field measurements included water temperature, pH, salinity, and specific conductivity; Water samples were analyzed for concentration of a range of metals including Al, Ba, B, Cd, Ca, Cr, Cu, Fe, Pb, Li, Mg, Mn, Ni, P, K, Si, Ag, Na, Sr, Ti, V, and Zn. The estuarine river reach showed a wide range of salinity and pH (salinity: 0.04 - 21.78 ppt; pH: 6.2-8.1), strongly affected by river hydrology and tidal mixing. Concentration and spatial distribution of the metals in river water show response to flow regimes from the low (400 cfs) to the intermediate (400-2600 cfs) and high flows. This paper presents the dynamics of the metals under varying flow, pH and salinity gradients over the seasons and discusses a potential "intrusion" of metal accumulation in riverbed upstream as sea level rise persists.

  10. 4-(2-Pyridylazo)-resorcinol Functionalized Thermosensitive Ionic Microgels for Optical Detection of Heavy Metal Ions at Nanomolar Level.

    Science.gov (United States)

    Zhou, Xianjing; Nie, Jingjing; Du, Binyang

    2015-10-07

    4-(2-Pyridylazo)-resorcinol (PAR) functionalized thermosensitive ionic microgels (PAR-MG) were synthesized by a one-pot quaternization method. The PAR-MG microgels were spherical in shape with radius of ca. 166.0 nm and narrow size distribution and exhibited thermo-sensitivity in aqueous solution. The PAR-MG microgels could optically detect trace heavy metal ions, such as Cu(2+), Mn(2+), Pb(2+), Zn(2+), and Ni(2+), in aqueous solutions with high selectivity and sensitivity. The PAR-MG microgel suspensions exhibited characteristic color with the presence of various trace heavy metal ions, which could be visually distinguished by naked eyes. The limit of colorimetric detection (DL) was determined to be 38 nM for Cu(2+) at pH 3, 12 nM for Cu(2+) at pH 7, and 14, 79, 20, and 21 nM for Mn(2+), Pb(2+), Zn(2+), and Ni(2+), respectively, at pH 11, which was lower than (or close to) the United States Environmental Protection Agency standard for the safety limit of these heavy metal ions in drinking water. The mechanism of detection was attributed to the chelation between the nitrogen atoms and o-hydroxyl groups of PAR within the microgels and heavy metal ions.

  11. Temperature/Stress Distributions in a Stress-Relief-Type Plate of Functionally Graded Materials under Thermal Shock

    Science.gov (United States)

    Awaji, Hideo; Takenaka, Hiromitsu; Honda, Sawao; Nishikawa, Tadahiro

    This paper presents a numerical technique for analyzing one-dimensional transient temperature and stress distributions in a stress-relief-type plate of functionally graded ceramic-metal based materials (FGMs), in relation to both the temperature-dependent thermal properties and continuous and gradual variation of the thermo-mechanical properties of the FGM. The FGM plate is assumed to be initially in steady state of temperature gradient, suffering high temperature at the ceramic side and low temperature at the metallic side associated with its in-service performance. The FGM plate is then rapidly cooled at the ceramic side of the plate by a cold medium. The transient temperature and related thermal stresses in the FGM plate are analyzed numerically for a model alumina-nickel FGM system. The proposed analytical technique for determining the temperature distribution is quite simple and widely applicable for various boundary conditions of FGMs, compared with methods recently proposed by other researchers. The optimum composition of FGMs is also discussed to reduce the thermal stresses in the FGM plate, relating to the function of the volume fraction of the metal across the thickness.

  12. Efficiency of SPIONs functionalized with polyethylene glycol bis(amine) for heavy metal removal

    Energy Technology Data Exchange (ETDEWEB)

    Wanna, Yongyuth, E-mail: yongyuth.wanna@gmail.com [College of KMITL Nanotechnology, King Mongkut' s Institute of Technology Ladkrabang, Chalongkrung Rd., Ladkrabang, Bangkok 10520 (Thailand); Nara Machinery Co., Ltd., 2-5-7, Jonan-Jima, Ohta-ku, Tokyo 143-0002 (Japan); Chindaduang, Anon; Tumcharern, Gamolwan [National Nanotechnology Center (NANOTEC), 111 Thailand Science Park, Pahol Yothin Rd, Klong Luang, Pathum Thani 12120 (Thailand); Phromyothin, Darinee [College of KMITL Nanotechnology, King Mongkut' s Institute of Technology Ladkrabang, Chalongkrung Rd., Ladkrabang, Bangkok 10520 (Thailand); Porntheerapat, Supanit [NECTEC, National Science and Technology Development Agency (NSTDA), 112 Thailand Science Park, Phahonyothin Rd., Khlong Nueng, Khlong Luang, Pathum Thani 12120 (Thailand); Nukeaw, Jiti [College of KMITL Nanotechnology, King Mongkut' s Institute of Technology Ladkrabang, Chalongkrung Rd., Ladkrabang, Bangkok 10520 (Thailand); Hofmann, Heirich [Laboratory of Powder Technology, Ecole Polytechnique Fédérale de Lausanne (Switzerland); Pratontep, Sirapat [College of KMITL Nanotechnology, King Mongkut' s Institute of Technology Ladkrabang, Chalongkrung Rd., Ladkrabang, Bangkok 10520 (Thailand)

    2016-09-15

    Hybrid magnetic nanoparticles based on poly(methylmethacrylate) (PMMA) and super-paramagnetic iron oxide nanopaticles (SPIONs) with selective surface modification has been developed for heavy metal removal by applying external magnetic fields. The nanoparticles were prepared by the emulsion polymerization technique in an aqueous suspension of SPIONs. The hydrolysis of carboxyl functional group was then applied for grafting polyethylene glycol bis(amine)(PEG-bis(amine)) onto the PMMA-coated SPIONs. The morphology, the chemical structure and the magnetic properties of the grafted nanoparticles were investigated. The efficiency of the hybrid nanoparticles for heavy metal removal were conducted on Pb(II), Hg(II), Cu(II) and Co(II) in aqueous solutions.The metal concentration in the solutions after separation by the hybrid nanoparticles was determined by inductively coupled plasma optical emission spectrometer (ICP-OES). The results show the heavy metal uptake ratios of 0.08, 0.04, 0.03, and 0.01 mM per gramme of the grafted SPIONs for Pb(II), Hg(II), Cu(II), and Co(II), respectively. A competitive removal of Cu(II), Pb(II), Co(II) and Hg(II) ions in mixed metal salt solutions has also been studied.The heavy metal removal efficiency of the hybrid nanoparitcles was found to depend on the cation radius, in accordance with capture of metal ions by the amine group. - Highlights: • We synthesis hybrid magnetic nanoparticles for heavy metal removal. • The efficiency of hybrid nanoparticles for heavy metal removal is proposed. • We investigated the characteristic of hybrid nanoparticle. • The heavy metal removal efficiency of the hybrid nanoparticle was founded that depend on the heavy metal cation radius.

  13. Determination of distribution pattern of the heavy metal concentrations in the potable network of Gachsaran by Geographical Information System (GIS

    Directory of Open Access Journals (Sweden)

    G Paraham

    2013-12-01

    . Methods: In this descriptive, cross-sectional study, samples were taken from11 spots of the drinking water distribution network and tested for concentration of 10 metals by Inductivity Coupled Ions Plasma (ICP method in summer of 2010. The research data were compared with national and international water standards. Then the distribution map of heavy metals concentrations in the drinking water wells of the region was prepared by using the Geographical Information System (GIS software. Data were analyzed by the Kruskal-Wallis tests. Results: In all samples, the average concentration of heavy metals were: Arsenic 0.54, Cadmium 0.05, Zinc 55.9, Lead 0.18, Copper .82, Chromium 1.6, Barium 36.5, Selenium0.5, Mercury 0.1 and Silver 0.05 micrograms per liter and was less than the water quality standard. Conclusion: Based on the results obtained, it can be concluded that concentrations of heavy metals in Gachsaran’s drinking water distribution network are not higher than national and international standards and therefore not harmful for people. Key words: Heavy metals, Distribution network, Gachsaran, geographical information system (GIS

  14. Enhanced chlorine dioxide decay in the presence of metal oxides: Relevance to drinking water distribution systems

    KAUST Repository

    Liu, Chao

    2013-07-19

    Chlorine dioxide (ClO2) decay in the presence of typical metal oxides occurring in distribution systems was investigated. Metal oxides generally enhanced ClO2 decay in a second-order process via three pathways: (1) catalytic disproportionation with equimolar formation of chlorite and chlorate, (2) reaction to chlorite and oxygen, and (3) oxidation of a metal in a reduced form (e.g., cuprous oxide) to a higher oxidation state. Cupric oxide (CuO) and nickel oxide (NiO) showed significantly stronger abilities than goethite (α-FeOOH) to catalyze the ClO2 disproportionation (pathway 1), which predominated at higher initial ClO2 concentrations (56-81 μM). At lower initial ClO2 concentrations (13-31 μM), pathway 2 also contributed. The CuO-enhanced ClO2 decay is a base-assisted reaction with a third-order rate constant of 1.5 × 10 6 M-2 s-1 in the presence of 0.1 g L -1 CuO at 21 ± 1 C, which is 4-5 orders of magnitude higher than in the absence of CuO. The presence of natural organic matter (NOM) significantly enhanced the formation of chlorite and decreased the ClO 2 disproportionation in the CuO-ClO2 system, probably because of a higher reactivity of CuO-activated ClO2 with NOM. Furthermore, a kinetic model was developed to simulate CuO-enhanced ClO 2 decay at various pH values. Model simulations that agree well with the experimental data include a pre-equilibrium step with the rapid formation of a complex, namely, CuO-activated Cl2O4. The reaction of this complex with OH- is the rate-limiting and pH-dependent step for the overall reaction, producing chlorite and an intermediate that further forms chlorate and oxygen in parallel. These novel findings suggest that the possible ClO2 loss and the formation of chlorite/chlorate should be carefully considered in drinking water distribution systems containing copper pipes. © 2013 American Chemical Society.

  15. Metabolic data and retention functions for the intracellular alkali metals

    International Nuclear Information System (INIS)

    Leggett, R.W.

    1983-05-01

    This report is a collection and discussion of the information needed for interpretation of bioassay results for the important radioelement cesium (Cs), as well as a comparison of the physiological behavior of Cs with that of potassium (K) and rubidium (Rb). This report is intended not only as an investigation of the metabolism of the intracellular alkali metals by humans, but also as a case study of the limitations inherent in applying ICRP 30 retention models in bioassay programs. In particular, the relationship between the mathematical components of the ICRP 30 retention model for Cs and actual physiological or anatomical entities is examined, and ways are suggested for modifying the ICRP 30 models for Cs, Rb, and K to yield better accuracy and to better account for biological variability among humans. Although the physiological behaviors of both Rb and Cs resemble that of K, quantitative differences arise because of differences in transport of K, Rb, and Cs by cell membranes. The resemblance is close enough, however, that total body K can be used as an index of whole-body retention times of Rb and Cs, and of compartmental fractions of Cs. The Cs half-time based on total body K appears to be within a factor of 1.5 for all adults. Total body K may be determined by whole-body gamma-ray counting techniques and hence is a reasonable index to use in many bioassay programs

  16. Efficient functionalization of poly (styrene) beads immobilized metal ...

    Indian Academy of Sciences (India)

    Three types of new bead-shaped heterogeneous nanoparticle (NP) catalysts were synthesized by simplified procedures and studied for continuous reduction of crystal violet (CV) dye. The stabilizing agent, viz., 2-acryloxyethyltrimethyl ammonium chloride (PAC) was functionalized efficiently onto the surface of insoluble ...

  17. Multi-point Distribution Function for the Continuous Time Random Walk

    OpenAIRE

    Barkai, E.; Sokolov, I. M.

    2007-01-01

    We derive an explicit expression for the Fourier-Laplace transform of the two-point distribution function $p(x_1,t_1;x_2,t_2)$ of a continuous time random walk (CTRW), thus generalizing the result of Montroll and Weiss for the single point distribution function $p(x_1,t_1)$. The multi-point distribution function has a structure of a convolution of the Montroll-Weiss CTRW and the aging CTRW single point distribution functions. The correlation function $$ for the biased CTRW process is found. T...

  18. Ecological and health risks assessment and spatial distribution of residual heavy metals in the soil of an e-waste circular economy park in Tianjin, China.

    Science.gov (United States)

    Han, Wei; Gao, Guanghai; Geng, Jinyao; Li, Yao; Wang, Yingying

    2018-04-01

    Ziya Circular Economy Park is the biggest e-waste recycle park in North China before 2011, its function was then transformed in response to regulations and rules. In this paper, investigation was conducted to research the residual concentrations of 14 analytes (12 heavy metals and 2 non-metals) in the surface soil of Ziya Circular Economy Park and surrounding area. Both ecological and health assessments were evaluated using GI (geo-accumulation index) and NPI (Nemerow pollution index), and associated health risk was assessed by using USEPA model. According to the ecological risk assessment, Cu, Sb, Cd, Zn and Co were seriously enriched in the soil of the studied area. The health risk assessment proposed by USEPA indicated no significant health risks to the population. Soil properties, such as pH and organic matter, were found to correlate with the enrichment of heavy metals. Arsenic concentrations in the soil were found positively correlated to dead bacteria concentrations. Spatial distribution of heavy metals revealed that Ziya Circular Economy Park was the dominant pollution source in the studied area. Findings in this study suggest that enough attention should be payed to the heavy metal pollution in Ziya Circular Economy Park. Copyright © 2018 Elsevier Ltd. All rights reserved.

  19. Distribution of metals and trace elements in sediments of three Alpine lakes

    Directory of Open Access Journals (Sweden)

    Zoran Jeran

    2002-12-01

    Full Text Available In three Alpine lakes (Jezero na Planini pri Jezeru, Krnsko jezero and in Jezero v Ledvicah the distribution of some metals and trace elements was determined in sediment cores using multielemental instrumental neutron activation analysis. Sediments wereanalysed to depths of 32 cm, 19 cm and 16 cm, respectively. Dating of sediments was done on the basis of 210Pb measurements.It was found that the levels of rare earth elements and some other lithophilic elements such as Sc, Cr, Th and U in Krnsko jezero were significantly lower than those found in the other two investigated lakes. In all three lakes changes with depth were noticed forpractically all anthropogenic elements, namely As, Br, Cd, Hg, Mo and Zn. Three periods of lake history can be distinguished which reflect industrial activities in the 19th and 20th century.In the sediment profile of lake Krnsko jezero three well expressed lows of all investigated elements were found at depths of 3-3.5 cm, 6-6.5 cm and 8 cm which can be linked to two earthquakes in 1976 and 1942 and the First World War. The influence of earthquakeson the distribution of trace elements in the other two lakes was less evident.

  20. Spatial distribution of heavy metals in solid adjacent to the Naples-Salerno motor way

    International Nuclear Information System (INIS)

    Imperato, M.; Monetti, V.; Naimo, D.; Stanzione, D.

    1999-01-01

    This work analyses the distribution of heavy metal in soil adjacent to the Naples-Salerno motor way, an area which typically contains volcanic products from Somma-Vesuvio. The various concentrations of Pb, Cd, Zn, Mn, Cu and Cr found in different portions of the motor way (embankment, road cut, field level) are reported. The data obtained indicate high level of pollution in soil adjacent to the motor way fencing, with maximum concentrations of 1220 ppm Pb, 1.9 ppm Cd and 341 ppm Zn. Gradients of decreasing pollution with distance from the fencing and with altitude from the road surface are highest for Zn followed by Pb and Cd. The presence of these three materials in depth follows an averagely constant falling gradient, with minimum detected values at 50 cm depth. The spatial distribution of Cr does not reveal any significant differences. Relatively big levels are due to the presence in the soil of Chromium-rich minerals such as augite and olivine. Mn and Cu are found, due to local contribution, probably as a consequence of the use of copper compounds in agriculture [it

  1. Anisotropy of electron work function and reticular compacting of friable faces of metallic crystals

    International Nuclear Information System (INIS)

    Vladimirov, A.F.

    1999-01-01

    The review and statistical estimate of experimental data on work functions for BCC-, FCC- and HCP - metals (W, Mo, Ta, Nb, Cr, V, Ni, Y) as well as the earlier developed quantum-mechanical statistical model of double electrical layer formation at metal surface and the calculation of an electron work function dipole constituent serve as a basis for the development of a semi-empirical theory of electron work function anisotropy. A coefficient of reticular compacting of friable crystal faces is introduced and statistically estimated. A coefficient of crystal emission anisotropy is also introduced and estimated both theoretically and empirically. The theory permits calculating work functions for all crystal faces and a volumetric constituent of the work function from the measured value of electron work function for a single face [ru

  2. Synthesis, characterization and heterogeneous base catalysis of amino functionalized lanthanide metal-organic frameworks

    Science.gov (United States)

    Huang, Jinping; Li, Chunmei; Tao, Lingling; Zhu, Huilin; Hu, Gang

    2017-10-01

    Lanthanide metal-organic frameworks (Ln-MOFs) are featured by their tolerance to water and dense structure. In this work, an amine-functionalized Ln-MOF was facilely synthesized by coordination of terbium with 2-aminoterephthalic acid under the condition of microwave irradiation. The crystal structure was characterized by single crystal X-ray diffraction, FT-IR, Raman, TG-DTA and XPS analysis. The basic catalytic activity of the NH2-Tb-MOF was evaluated for Knoevenagel condensation and Henry reactions. Apart from the high activity and 100% selectivity to the condensation product, the NH2-Tb-MOF catalyst could be easily recycled and reused owing to the high stability of the MOF framework formed by coordination of Tb3+ with carboxylic groups. Remarkably, the NH2-Tb-MOF exhibited size-selective catalysis to substrates. For the small-sized reactants, it displayed comparable activity to the homogeneous catalyst of aniline owing to the high dispersion of NH2- active sites and the low diffusion limits. However, in the same reaction system, extremely poor activity in Knoevenagel condensation and Henry reaction for the bulky substrate 4-(tert-butyl) benzaldehyde was observed due to the both effects of substitute and inhibition of diffusion into the micropores. Crystal structure analysis provided a mechanistic evidence that the heterogeneous base catalysis arose from the amino groups densely distributed inside the micropores.

  3. Distribution of Heavy Metals in the Liver of Foetuses and Female Mice after Oral Administration during Pregnancy - a Histochemical Study

    Directory of Open Access Journals (Sweden)

    Lenka Krejčířová

    2010-01-01

    Full Text Available The aim of this work was to study the distribution of heavy metals and of subsequently developed morphological changes in the liver of female mice and their foetuses after oral administration of high doses of lead, mercury, and cadmium (0.03 mg of metal per mouse and day. Heavy metals were administered to pregnant female mice on days 9-20 of pregnancy. The animals were euthanised by cervical dislocation. Samples of mother and foetal liver were subsequently collected and processed by means of the common technique for light and electron microscopy. Histochemical reaction based on metal conversion into appropriate sulphide that conjugates with silver was used for detection of heavy metals. Deposits of heavy metals were found at the periphery of lobules of the central vein in the liver of female mice. On the contrary, in the liver of foetuses no predilection site for localisation of the reaction product could be identified. At the electron microscopy level, accumulation of heavy metals was connected as a rule with the occurrence of certain damage to some organelles. Deposits of the reaction product were located mainly in hepatocytes and Kupffer cells. Heavy metals were bound to the heterochromatin of cell nuclei, as well as to some cytoplasmic organelles, such as rough endoplasmic reticulum, mitochondria, ribosomes, and lysosomes. The presence of heavy metals was associated with obliteration of cisternae of the rough endoplasmic reticulum, separation of ribosomes, and destruction of lysosomes. Vacuolation of cell cytoplasm was also a frequent phenomenon. An interesting finding was the "contrasting" of structures containing nucleic acids. Accumulation of metals in the liver of pregnant mice and their foetuses observed in our study indicated that placental barrier does not protect the foetal organism against penetration of metals. Their higher accumulation in foetal compared to maternal liver can be explained by the intense metabolism of

  4. Cathodoluminescence and phase-change functionality of metallic nanoparticles

    OpenAIRE

    Denisyuk, A.I.

    2009-01-01

    Nanoscale resolution cathodoluminescence (CL) has been used to demonstrate and investigate the functionality of nanoparticle-based components for future nanophotonic phase-change memory and optical antenna applications. An integrated experimental system based on a scanning electron microscope was developed for the fabrication and in situ characterization of nanoparticles. It was equipped with an atomic beam source for gallium nanoparticle growth, a liquid-nitrogen-cooled cryostat to control s...

  5. Decomposing a Utility Function Based on Discrete Distribution Independence

    DEFF Research Database (Denmark)

    He, Ying; Dyer, James; Butler, John

    2014-01-01

    For two-attribute decision-making problems, the multilinear utility model cannot be applied when the risk aversion on one attribute depends on the level of the other attribute. We propose a family of general preference conditions called nth-degree discrete distribution independence that can...... accommodate a variety of dependence relationships between two attributes. The special case of second-degree discrete distribution independence is equivalent to the utility independence condition. We focus on third-degree discrete distribution independence that leads to a decomposition formula that contains...

  6. Heavy Metal Pollution in Settled Dust Associated with Different Urban Functional Areas in a Heavily Air-Polluted City in North China.

    Science.gov (United States)

    Wan, Dejun; Han, Zhangxiong; Yang, Jinsong; Yang, Guanglin; Liu, Xingqi

    2016-11-10

    Understanding variations of heavy metals in atmospheric particles between different functional areas is significant for pollution control and urban planning in cities. To reveal pollution and spatial distribution of heavy metals in atmospheric particles from different urban functional areas in Shijiazhuang in North China, 43 settled dust samples were collected over the main urban area and heavy metal concentrations were determined in their pollution indexes (IPIs) of the ten heavy metals are 2.7-13.6 (5.7 ± 2.2), suggesting high or very high pollution levels of most dust. Relatively lower IPIs occur mainly in the administration-education area, the commercial area, and other unclassified sites; while peaks occur mainly in the North Railway Station, the northeastern industrial area, and some sites near heavily trafficked areas, implying the significant influence of intensive industrial (including coal combustion) and traffic activities on atmospheric heavy metal accumulation. These results suggest a clear need of mitigating atmospheric heavy metal pollution via controlling emissions of toxic metals (especially Cd and Pb) from industrial and traffic sources in the city.

  7. Heavy Metal Pollution in Settled Dust Associated with Different Urban Functional Areas in a Heavily Air-Polluted City in North China

    Science.gov (United States)

    Wan, Dejun; Han, Zhangxiong; Yang, Jinsong; Yang, Guanglin; Liu, Xingqi

    2016-01-01

    Understanding variations of heavy metals in atmospheric particles between different functional areas is significant for pollution control and urban planning in cities. To reveal pollution and spatial distribution of heavy metals in atmospheric particles from different urban functional areas in Shijiazhuang in North China, 43 settled dust samples were collected over the main urban area and heavy metal concentrations were determined in their pollution indexes (IPIs) of the ten heavy metals are 2.7–13.6 (5.7 ± 2.2), suggesting high or very high pollution levels of most dust. Relatively lower IPIs occur mainly in the administration-education area, the commercial area, and other unclassified sites; while peaks occur mainly in the North Railway Station, the northeastern industrial area, and some sites near heavily trafficked areas, implying the significant influence of intensive industrial (including coal combustion) and traffic activities on atmospheric heavy metal accumulation. These results suggest a clear need of mitigating atmospheric heavy metal pollution via controlling emissions of toxic metals (especially Cd and Pb) from industrial and traffic sources in the city. PMID:27834903

  8. Geochemical atlas of Radovish and the environs and the distribution of heavy metals in the air

    International Nuclear Information System (INIS)

    Stafilov, Trajche; Bacheva, Katerina; Boev, Blazho; Shajn, Robert; Balabanova, Biljana

    2010-01-01

    Mining activities, ore processing and processing of waste are potential emitters of heavy metals in air. As more important are mining activities on surface excavation of ore due to the large number of direct polluting factors that are difficult to control and manage. Special emphasis is given to the organization of the pit (road movement of dampers carrying ore waste), waste management (ore and flotation tailings) as well as the frequency of explosions for excavation of mining minerals. One of the major emission sources of some metals in the eastern part of the R. Macedonia is Buchim copper mine and flotation, near the town of Radovish. The mine and plant for the preparation of ore are in function from the late seventies of the last century. Ore excavation is from open pit and the ore tailings are stored in the open, in mine vicinity. The produced copper ore from the mine is processed in the flotation tailings are separated, disposed of and deposited on a dump site in an adjacent valley near the village Topolnica.

  9. Impact of Internal Metallic Ports in Temporary Tissue Expanders on Postmastectomy Radiation Dose Distribution

    International Nuclear Information System (INIS)

    Chen, Susie A.; Ogunleye, Tomiwa; Dhabbaan, Anees; Huang, Eugene H.; Losken, Albert; Gabram, Sheryl; Davis, Lawrence; Torres, Mylin A.

    2013-01-01

    Purpose: Temporary tissue expanders (TTE) with an internal magnetic metal port (IMP) have been increasingly used for breast reconstruction in post-mastectomy patients who receive radiation therapy (XRT). We evaluated XRT plans of patients with IMP to determine its effect on XRT dose distribution. Methods and Materials: Original treatment plans with CT simulation scans of 24 consecutive patients who received XRT (ORI), planned without heterogeneity corrections, to a reconstructed breast containing an IMP were used. Two additional treatment plans were then generated: one treatment plan with the IMP assigned the electron density of the rare earth magnet, nickel plated neodymium-iron-boron (HET), and a second treatment plan with the IMP assigned a CT value of 1 to simulate a homogeneous breast without an IMP (BRS). All plans were prescribed 50 Gy to the reconstructed breast (CTV). Results: CTV coverage by 50 Gy was significantly lower in the HET (mean 87.7% CTV) than in either the ORI (mean 99.7% CTV, P<.001) or BRS plans (mean 95.0% CTV, P<.001). The effect of the port was more pronounced on CT slices containing the IMP with prescription dose coverage of the CTV being less in the HET than in either ORI (mean difference 33.6%, P<.01) or BRS plans (mean difference 30.1%, P<.001). HET had a less homogeneous and conformal dose distribution than BRS or ORI. Conclusion: IMPs increase dose heterogeneity and reduce dose to the breast CTV through attenuation of the beam. For optimal XRT treatment, heterogeneity corrections should be used in XRT planning for patients with TTE with IMP, as the IMP impacts dose distribution

  10. Impact of Internal Metallic Ports in Temporary Tissue Expanders on Postmastectomy Radiation Dose Distribution

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Susie A.; Ogunleye, Tomiwa; Dhabbaan, Anees [Department of Radiation Oncology, Winship Cancer Institute, Emory University, Atlanta, Georgia (United States); Huang, Eugene H. [North Coast Cancer Care, Sandusky, Ohio (United States); Losken, Albert [Division of Plastic Surgery and Reconstructive Surgery, Department of Surgery, Emory University, Atlanta, Georgia (United States); Gabram, Sheryl [Division of Surgical Oncology, Department of Surgery, Emory University, Atlanta, Georgia (United States); Davis, Lawrence [Department of Radiation Oncology, Winship Cancer Institute, Emory University, Atlanta, Georgia (United States); Torres, Mylin A., E-mail: matorre@emory.edu [Department of Radiation Oncology, Winship Cancer Institute, Emory University, Atlanta, Georgia (United States)

    2013-03-01

    Purpose: Temporary tissue expanders (TTE) with an internal magnetic metal port (IMP) have been increasingly used for breast reconstruction in post-mastectomy patients who receive radiation therapy (XRT). We evaluated XRT plans of patients with IMP to determine its effect on XRT dose distribution. Methods and Materials: Original treatment plans with CT simulation scans of 24 consecutive patients who received XRT (ORI), planned without heterogeneity corrections, to a reconstructed breast containing an IMP were used. Two additional treatment plans were then generated: one treatment plan with the IMP assigned the electron density of the rare earth magnet, nickel plated neodymium-iron-boron (HET), and a second treatment plan with the IMP assigned a CT value of 1 to simulate a homogeneous breast without an IMP (BRS). All plans were prescribed 50 Gy to the reconstructed breast (CTV). Results: CTV coverage by 50 Gy was significantly lower in the HET (mean 87.7% CTV) than in either the ORI (mean 99.7% CTV, P<.001) or BRS plans (mean 95.0% CTV, P<.001). The effect of the port was more pronounced on CT slices containing the IMP with prescription dose coverage of the CTV being less in the HET than in either ORI (mean difference 33.6%, P<.01) or BRS plans (mean difference 30.1%, P<.001). HET had a less homogeneous and conformal dose distribution than BRS or ORI. Conclusion: IMPs increase dose heterogeneity and reduce dose to the breast CTV through attenuation of the beam. For optimal XRT treatment, heterogeneity corrections should be used in XRT planning for patients with TTE with IMP, as the IMP impacts dose distribution.

  11. APPLICATIONS OF SOME NEW TRANSMUTED CUMULATIVE DISTRIBUTION FUNCTIONS IN POPULATION DYNAMICS

    Directory of Open Access Journals (Sweden)

    Vesselin Kyurkchiev

    2017-05-01

    Full Text Available Motivation: In literature, several transformations exists to obtain a new cumulative distribution function (cdf using other(s well-known cdf(s. Results: In this note we find applications of some new cumulative distribution function transformations to construct a family of sigmoidal functions based on the Verhulst logistic function. We prove estimates for the Hausdorff approximation of the shifted Heaviside step function by means of this family. Numerical examples, illustrating our results are given.

  12. Probability Distribution Function of the Upper Equatorial Pacific Current Speeds

    National Research Council Canada - National Science Library

    Chu, Peter C

    2005-01-01

    ...), constructed from hourly ADCP data (1990-2007) at six stations for the Tropical Atmosphere Ocean project satisfies the two-parameter Weibull distribution reasonably well with different characteristics between El Nino and La Nina events...

  13. Analysis of the Elastic Large Deflection Behavior for Metal Plates under Nonuniformly Distributed Lateral Pressure with In-Plane Loads

    Directory of Open Access Journals (Sweden)

    Jeom Kee Paik

    2012-01-01

    Full Text Available The Galerkin method is applied to analyze the elastic large deflection behavior of metal plates subject to a combination of in-plane loads such as biaxial loads, edge shear and biaxial inplane bending moments, and uniformly or nonuniformly distributed lateral pressure loads. The motive of the present study was initiated by the fact that metal plates of ships and ship-shaped offshore structures at sea are often subjected to non-uniformly distributed lateral pressure loads arising from cargo or water pressure, together with inplane axial loads or inplane bending moments, but the current practice of the maritime industry usually applies some simplified design methods assuming that the non-uniform pressure distribution in the plates can be replaced by an equivalence of uniform pressure distribution. Applied examples are presented, demonstrating that the current plate design methods of the maritime industry may be inappropriate when the non-uniformity of lateral pressure loads becomes more significant.

  14. MEP family of wind speed distribution function and comparison with the empirical Weibull distribution. Paper no. IGEC-1-156

    International Nuclear Information System (INIS)

    Li, M.; Li, X.

    2005-01-01

    The probabilistic distribution of wind speed is one of the important wind characteristics for the assessment of wind energy potential and for the performance of wind energy conversion systems, as well as for the structural and environmental design and analysis. In this study, an exponential family of distribution functions has been developed for the description of the probabilistic distribution of wind speed, and comparison with the wind speed data taken from different sources and measured at different geographical locations in the world has been made. This family of distributions is developed by introducing a pre-exponential term to the theoretical distribution derived from the Maximum Entropy Principle (MEP). The statistical analysis parameter based on the wind power density is used as the suitability judgement for the distribution functions. It is shown that the MEP-type distributions not only agree better with a variety of the measured wind speed data than the conventionally used empirical Weibull distribution, but also can represent the wind power density much more accurately. Therefore, the MEP-type distributions are more suitable for the assessment of the wind energy potential and the performance of wind energy conversion systems. (author)

  15. Distribution of metals in fauna, flora and sediments of wet detention ponds and natural shallow lakes

    DEFF Research Database (Denmark)

    Stephansen, Diana; Nielsen, Asbjørn Haaning; Hvitved-Jacobsen, Thorkild

    2014-01-01

    . For the sediments, however, this observed trend was not statistically significant for any of the metals. Comparing the different metals accumulated in the sediments, the fauna, and the flora, no correlation between any of these could be detected. Neither fauna nor flora metal concentrations did correlate......, chromium, nickel, lead, and phosphorus. There was a trend toward the studied wet detention ponds being more polluted by metals than the lakes. For the fauna this trend was statistically significant for all metals, while it for the plants was statistically significant for most of the metals...... with sediment metal concentrations, and fauna metal concentrations did not correlate with flora metal concentrations. Comparing the diversity of species in the wet detention ponds and the shallow lakes, molluscs were more abundant in the wet detention ponds. For other fauna and flora, no clear difference...

  16. Differential Pair Distribution Function Study of the Structure of Arsenate Adsorbed on Nanocrystalline [gamma]-Alumina

    Energy Technology Data Exchange (ETDEWEB)

    Li, Wei; Harrington, Richard; Tang, Yuanzhi; Kubicki, James D.; Aryanpour, Masoud; Reeder, Richard J.; Parise, John B.; Phillips, Brian L. (SBU); (Penn)

    2012-03-15

    Structural information is important for understanding surface adsorption mechanisms of contaminants on metal (hydr)oxides. In this work, a novel technique was employed to study the interfacial structure of arsenate oxyanions adsorbed on {gamma}-alumina nanoparticles, namely, differential pair distribution function (d-PDF) analysis of synchrotron X-ray total scattering. The d-PDF is the difference of properly normalized PDFs obtained for samples with and without arsenate adsorbed, otherwise identically prepared. The real space pattern contains information on atomic pair correlations between adsorbed arsenate and the atoms on {gamma}-alumina surface (Al, O, etc.). PDF results on the arsenate adsorption sample on {gamma}-alumina prepared at 1 mM As concentration and pH 5 revealed two peaks at 1.66 {angstrom} and 3.09 {angstrom}, corresponding to As-O and As-Al atomic pair correlations. This observation is consistent with those measured by extended X-ray absorption fine structure (EXAFS) spectroscopy, which suggests a first shell of As-O at 1.69 {+-} 0.01 {angstrom} with a coordination number of 4 and a second shell of As-Al at 3.13 {+-} 0.04 {angstrom} with a coordination number of 2. These results are in agreement with a bidentate binuclear coordination environment to the octahedral Al of {gamma}-alumina as predicted by density functional theory (DFT) calculation.

  17. Differential pair distribution function study of the structure of arsenate adsorbed on nanocrystalline γ-alumina.

    Science.gov (United States)

    Li, Wei; Harrington, Richard; Tang, Yuanzhi; Kubicki, James D; Aryanpour, Masoud; Reeder, Richard J; Parise, John B; Phillips, Brian L

    2011-11-15

    Structural information is important for understanding surface adsorption mechanisms of contaminants on metal (hydr)oxides. In this work, a novel technique was employed to study the interfacial structure of arsenate oxyanions adsorbed on γ-alumina nanoparticles, namely, differential pair distribution function (d-PDF) analysis of synchrotron X-ray total scattering. The d-PDF is the difference of properly normalized PDFs obtained for samples with and without arsenate adsorbed, otherwise identically prepared. The real space pattern contains information on atomic pair correlations between adsorbed arsenate and the atoms on γ-alumina surface (Al, O, etc.). PDF results on the arsenate adsorption sample on γ-alumina prepared at 1 mM As concentration and pH 5 revealed two peaks at 1.66 Å and 3.09 Å, corresponding to As-O and As-Al atomic pair correlations. This observation is consistent with those measured by extended X-ray absorption fine structure (EXAFS) spectroscopy, which suggests a first shell of As-O at 1.69 ± 0.01 Å with a coordination number of ~4 and a second shell of As-Al at ~3.13 ± 0.04 Å with a coordination number of ~2. These results are in agreement with a bidentate binuclear coordination environment to the octahedral Al of γ-alumina as predicted by density functional theory (DFT) calculation.

  18. Density functional theory analysis of hexagonal close-packed elemental metal photocathodes

    Directory of Open Access Journals (Sweden)

    Tuo Li

    2015-07-01

    Full Text Available A density function theory based analysis of photoemission from hexagonal close packed (hcp metals is presented and the calculated values of the rms transverse momentum (Δp_{T} are in good agreement with the available experimental data on Be [Phys. Rev. Lett. 111, 237401 (2013] and Mg [Proceedings of LINAC 2002, Gyeongju, Korea (2002]. The lattice constants and work functions of the hcp metals are also examined and are consistent with the available experimental values. In addition, emission from (0001-oriented Be is examined due to the presence of a strong surface state.

  19. On time boundary of functional metal properties maintainance under extreme conditions

    Directory of Open Access Journals (Sweden)

    Zhabyka L.V.

    2012-08-01

    Full Text Available There are established the boundaries of conserving functional properties of metals at dynamic failure under extreme conditions (longevity range t ∼10−6÷10−10s. The methods of non-linear physics made it possible to determine universal attributes of non-equilibrium systems evolution conditioned by collective effects and phenomena of self-organization in the appearing dissipative structures. In the paper there is presented a universal failure surface that allows simulation of metals behavior under laboratory conditions and forecast of time boundary of functional properties conservation.

  20. Slow electron distribution function in a cylindrical hollow-cathode discharge

    International Nuclear Information System (INIS)

    Arslanbekov, R.R.; Kudryavtsev, A.A.; Movchan, I.A.

    1992-01-01

    The formation of the electron distribution function in a cylindrical hollow cathode at energies up to the threshold for inelastic processes is examined. It is shown that the distribution function is a Maxwellian distribution in the thermal region plus a step determined by the sources of fast electrons. The distribution develops nonlocally, and the distinctive feature of this regime is the absence of a radial dependence when scaled to the total energy. The derived formulas can be used to calculate the electron distribution function simply from a given current and geometrical dimensions of the discharge. 14 refs., 3 figs

  1. Migration, speciation and distribution of heavy metals in an oil-polluted soil affected by crude oil extraction processes.

    Science.gov (United States)

    Fu, Xiaowen; Cui, Zhaojie; Zang, Guolong

    2014-07-01

    Heavy metals are among the major pollutants in the worldwide soil environment. In oilfields, the crude oil extraction process results in the simultaneous contamination of the soil with petroleum and heavy metals. In this work, we investigated the influence of oil extraction on the migration, speciation, and temporal distribution of heavy metals (Cu, Zn, Pb, Cd, Cr, Mn, Ni, V, and Mn) in soils of an oil region of Shengli Oilfield, China. The results showed that oil-polluted soils were contaminated with Cu, Zn, Cd and Ni, with mean concentrations of 27.63, 67.12, 0.185 and 33.80 mg kg(-1), respectively (greater than the background values of local surface soils). Compared with the control profile, the vertical distributions of Cu, Zn, Pb, Cd, Ni, and V were affected in oil-polluted soils, particularly those of Cd and Ni. The concentrations of Zn, Cd, Ni, V, and Mn in oil-polluted soils increased with the duration of oil well development, which indicated the levels of these metals in the oil field were enhanced by human activities. Fractionation analysis revealed that the mobility potential of heavy metals in oil polluted soil decreased in the sequence Cd > Mn > Zn > Ni > Pb > Cu > Cr > V. The most important proportion of Cd is ion exchangeable and acid soluble, which indicates that Cd is the most labile, available, and harmful heavy metal among the elements that damage the soil environment in oil-polluted soil.

  2. Effects of simulated acid rain, EDTA, or their combination, on migration and chemical fraction distribution of extraneous metals in Ferrosol.

    Science.gov (United States)

    Wen, Fang; Hou, Hong; Yao, Na; Yan, Zengguang; Bai, Liping; Li, Fasheng

    2013-01-01

    A laboratory repacked soil-leaching column experiment was conducted to study the effects of simulated acid rain or EDTA by themselves or in combination, on migration and chemical speciation distribution of Pb and its alternative rare metals including Ag, Bi, In, Sb, and Sn. Experimental results demonstrate that leaching with simulated acid rain promoted the migration of Bi, In and Pb, and their migration reached down to 8 cm in the soil profile, no enhancement of Sb, Ag or Sn migration was observed. Addition of EDTA significantly enhanced the migration of all six metals, especially Bi, In and Pb. The migration of metals was in the order Pb>Bi>In>Sb>Sn>Ag. The individual and combined effects of acid rain and EDTA increased the environmental risk of metals, by increasing the soluble content of metals in soil solutions and the relative distribution of the exchangeable fraction. Leaching risks of Bi, In and Pb were higher than other three metals. Copyright © 2012 Elsevier Ltd. All rights reserved.

  3. Influence of Metal and Ceramic Abutments on the Stress Distribution Around Narrow Implants: A Photoelastic Stress Analysis.

    Science.gov (United States)

    Galvão, Gustavo Holtz; Grossi, João Almeida; Zielak, João César; Giovanini, Allan Fernando; Furuse, Adilson Yoshio; Gonzaga, Carla Castiglia

    2016-08-01

    This study aimed to compare, through photoelastic analysis, the distribution of stresses around narrow implants with external hexagon (EH) and Morse taper (MT) connections, when single crowns made with metal and ceramic abutments were used. Six photoelastic models were prepared, simulating the use of narrow EH and MT implants replacing a lateral incisor. These 2 groups received 3 different abutments: prefabricated metal abutments, customized metal abutments, and customized zirconia abutments. All crowns were identical and made with a leucite reinforced glass-ceramic. Vertical loads of 0 to 100 N were applied on the palatal surface of the crowns, and the photoelastic stress fringes developed in each model were captured in a high-definition video, and digital photographs were taken at 100 N. The abutment type and material influenced the stress distribution patterns around narrow implants with EH and MT connections. Stresses were generated mainly around the apical and lingual regions of the implants. For both connections, the prefabricated metal abutments presented better stress distribution around the implants when compared to customized metal and zirconia abutments because low stress levels were developed in smaller areas around the implants.

  4. Early-stage evolution of particle size distribution with Johnson's SB function due to Brownian coagulation

    International Nuclear Information System (INIS)

    Tang Hong; Lin Jianzhong

    2013-01-01

    The moment method can be used to determine the time evolution of particle size distribution due to Brownian coagulation based on the general dynamic equation (GDE). But the function form of the initial particle size distribution must be determined beforehand for the moment method. If the assumed function type of the initial particle size distribution has an obvious deviation from the true particle population, the evolution of particle size distribution may be different from the real evolution tendency. Thus, a simple and general method is proposed based on the moment method. In this method, the Johnson's S B function is chosen as a general distribution function to fit the initial distributions including the log normal (L-N), Rosin–Rammler (R-R), normal (N-N) and gamma distribution functions, respectively. Meanwhile, using the modified beta function to fit the L-N, R-R, N-N and gamma functions is also conducted as a comparison in order to present the advantage of the Johnson's S B function as the general distribution function. And then, the time evolution of particle size distributions using the Johnson's S B function as the initial distribution can be obtained by several lower order moment equations of the Johnson's S B function in conjunction with the GDE during the Brownian coagulation process. Simulation experiments indicate that fairly reasonable results of the time evolution of particle size distribution can be obtained with this proposed method in the free molecule regime, transition regime and continuum plus near continuum regime, respectively, at the early time stage of evolution. The Johnson's S B function has the ability of describing the early time evolution of different initial particle size distributions. (paper)

  5. Nonparametric estimation of the stationary M/G/1 workload distribution function

    DEFF Research Database (Denmark)

    Hansen, Martin Bøgsted

    In this paper it is demonstrated how a nonparametric estimator of the stationary workload distribution function of the M/G/1-queue can be obtained by systematic sampling the workload process. Weak convergence results and bootstrap methods for empirical distribution functions for stationary...... associated sequences are used to derive asymptotic results and bootstrap methods for inference about the workload distribution function. The potential of the method is illustrated by a simulation study of the M/D/1 model....

  6. Material flow analysis of scarce metals: sources, functions, end-uses and aspects for future supply.

    Science.gov (United States)

    Peiró, Laura Talens; Méndez, Gara Villalba; Ayres, Robert U

    2013-03-19

    A number of metals that are now important to the electronic industry (and others) will become much more important in the future if current trends in technology continue. Most of these metals are byproducts (or hitch-hikers) of a small number of important industrial metals (attractors). By definition, the metals in the hitch-hiker group are not mined by themselves, and thus their production is limited by the demand for the major attractors. This article presents a material flow analysis (MFA) of the complex inter-relationships between these groups of metals. First, it surveys the main sources of geologically scarce (byproduct) metals currently considered critical by one or other of several recent studies. This is followed by a detailed survey of their major functions and the quantities contained in intermediate and end-products. The purpose is to identify the sectors and products where those metals are used and stocked and thus potentially available for future recycling. It concludes with a discussion of the limitations of possible substitution and barriers to recycling.

  7. CO adsorption on transition metal clusters: Trends from density functional theory

    Science.gov (United States)

    Zeinalipour-Yazdi, Constantinos D.; Cooksy, Andrew L.; Efstathiou, Angelos M.

    2008-05-01

    This work reports for the first time the trends for carbon monoxide (CO) chemisorption on transition metal clusters present in supported metal catalysts. In particular, the energetic, structural and infrared adsorption characteristics of linearly (atop) CO adsorbed on transition metal nano-clusters of less than 10 Å in size were explored. Spin-unrestricted density functional theory (DFT) calculations were employed to explore the trends of CO adsorption energy (AM-CO) and C-O vibrational frequency (νCO) for clusters composed of Ni, Cu, Ru, Rh, Pd, Ag, Ir, Pt and Au. The effects of the transition metal electronic structure onto the adsorption energy of CO and the vibrational stretching frequency of C-O, and how these chemical parameters can be correlated to the catalytic activity of transition supported metal catalysts that involve the adsorption, surface diffusion, and C-O bond dissociation elementary steps in heterogeneous catalytic surface reactions, are discussed. Our findings show that an increase of the electronic d-shell occupancy and the principal quantum number (n) in transition metals causes an increase in the vibrational stretching frequency of the C-O bond. This trend is inconsistent with the classical Blyholder model for the metal-carbonyl bond.

  8. Trends in the chemical properties in early transition metal carbide surfaces: A density functional study

    DEFF Research Database (Denmark)

    Kitchin, J.R.; Nørskov, Jens Kehlet; Barteau, M.A.

    2005-01-01

    In this paper we present density functional theory (DFT) investigations of the physical, chemical and electronic structure properties of several close-packed surfaces of early transition metal carbides, including beta-Mo2C(0 0 0 1), and the (1 1 1) surfaces of TiC, VC, NbC, and TaC. The results...... are in excellent agreement with experimental values of lattice constants and bulk moduli. The adsorption of atomic hydrogen is used as a probe to compare the chemical properties of various carbide surfaces. Hydrogen adsorbs more strongly to the metal-terminated carbide surfaces than to the corresponding closest......-packed pure metal surfaces, due to the tensile strain induced in the carbide surfaces upon incorporation of carbon into the lattice. Hydrogen atoms were found to adsorb more weakly on carbide surfaces than on the corresponding closest-packed pure metal surfaces only when there were surface carbon atoms...

  9. Distribution of pesticides, PAHs and heavy metals in prawn ponds near Kolleru lake wetland, India.

    Science.gov (United States)

    Amaraneni, Sreenivasa Rao

    2006-04-01

    This paper discussed the distribution of pesticides, polycyclic aromatic hydrocarbons (PAHs) and heavy metals in water, sediment and prawn from intensive prawn ponds (n=8) near the Kolleru lake wetland, India and assessed the quality of prawn for human consumption and also discussed the possible effects of these pollutants on pond environment and aquatic environment. The chemicals and other products used in prawn ponds near the Kolleru lake wetland were documented. The sediment, prawn and water samples were collected six times from selected prawn ponds during the production period of 3 months. Water samples were analyzed for selected physico-chemical parameters. The levels of pesticides, PAHs and heavy metals were found to decrease in the order sediment followed by prawn and water. The maximum concentrations of pesticides in sediment, prawn and water were alpha-BHC (174.2 microg g(-)(1)), gamma-BHC (234 microg g(-)(1)), malathion (256 microg g(-)(1)), chloripyrifos (198.5 microg g(-)(1)), endosulfan (238 microg g(-)(1)), dieldrin (19.6 microg g(-)(1)) and p,p'-DDT (128.6 microg g(-)(1)). Isodrin was found below detectable limit. The maximum concentrations of PAHs in sediment, prawn and water are anthracene (0.901 microg kg(-)(1)), fluranthene (0.601 microg kg(-)(1)), pyrene (0.786 microg kg(-)(1)), chrysene (0.192 microg kg(-)(1)), benzo(a)pyrene (0.181 microg kg(-)(1)) and benzo(ghi)perylene (227 microg kg(-)(1)). Benzo(e)pyrene, perylene, isomers of dibenzoanthracene and coronene were found below detectable limits. The maximum concentrations of heavy metals in sediment, prawn and water and also in prawn feed are Cu (791 microg g(-)(1)), Pb (270 microg g(-)(1)), Cd (1.07 microg g(-)(1)), Mn (4417 microg g(-)(1)), Ni (8.1 microg g(-)(1)), Co (5.8 microg g(-)(1)), Zn (1076 microg g(-)(1)), Cr (36.4 microg g(-)(1)), As (2.9 microg g(-)(1)), Se (6.3 microg g(-)(1)), Th (2.1 microg g(-)(1)) and Mo (0.762 microg g(-)(1)).

  10. A new approach to texture measurements: Orientation distribution function (ODF) determination by Rietveld refinement

    International Nuclear Information System (INIS)

    Vondreele, R.; Larson, A.; Lawson, A.; Sheldon, R.; Wright, S.

    1996-01-01

    The preferred orientation of crystal grains within a manufactured part is described most fully by its orientation distribution function (ODF), which is a mapping of the probability of each of the possible grain orientations with respect to the exterior dimensions. Traditionally, an ODF is determined from pole figures for a relatively small number of reflections. These pole figures are measured with x-rays or neutrons using short detector scans over the center of an individual diffraction peak for a large number of different sample orientations. This is efficient if the selected diffraction peaks are reasonably strong (relative to background) and well separated, such as in pure fcc and bcc metals. It is also appropriate for constant wavelength sources where collection of individual diffraction peak intensities is a reasonably efficient use of the source. However, the traditional method is not very efficient for neutron diffraction at a spallation source such as LANSCE where the entire diffraction pattern is accessible for each sample setting. Moreover, a different approach is necessary for complicated diffraction patterns, such as from composite materials, intermetallic compounds, high T c ceramics, polyphasic minerals and polymers where there is expected to be heavy overlap of adjacent diffraction peaks. In addition, the large number of settings normally collected for an individual pole figure may not be necessary, since the entire pattern is obtained at each setting. Thus, a new method of ODF analysis needs to be developed to handle the more complex diffraction patterns obtained from modern technological materials as well as take advantage of the particular characteristics of spallation neutron sources. This project sought to develop the experimental procedures and the mathematical treatment needed to produce an orientation distribution function (ODF) directly from full diffraction patterns from a sample in a limited number of orientations

  11. A Study Of Stress Distribution At The Cement Interface Of Metal Ceramic Restoration-Dentin By Finite ElementAnalysis

    Directory of Open Access Journals (Sweden)

    Emamieh M. Emamieh S

    2003-07-01

    Full Text Available  Since three decade ago, the application of the concept of finite element analysis (EEA have received a keen interest among dental investigators. In practice the FEA provides detailed stress information regarding to a non-homogenious body such as craniofocal skeletal growth, tooth post ceramo-metal crowns and etc. The aim of this study was the determination of the influence of stress distribution at the cement interface of metal ceramic restoration-dentin."nMaterials and Methods: An idealized metal-ceramic crown model was developed. The model was divided into very small segments. Various loading conditions was applied to the model. A super sap software was used for analyzing the stress distribution."nResults & Conclusion: The results of this study suggest that the higher shear stress was developed in the cervical region by two dimensional methods."n"n"n"n"n 

  12. Effect of Grain Boundary Character Distribution on the Impact Toughness of 410NiMo Weld Metal

    DEFF Research Database (Denmark)

    Divya, M.; Das, Chitta Ranjan; Chowdhury, Sandip Ghosh

    2016-01-01

    Grain boundary character distributions in 410NiMo weld metal were studied in the as-welded, first-stage, and second-stage postweld heat treatment (PWHT) conditions, and these were correlated with the Charpy-V impact toughness values of the material. The high impact toughness values in the weld...

  13. Distribution and behaviour of selected heavy metals and other elements in various components of the southern Baltic ecosystem

    International Nuclear Information System (INIS)

    Szefer, P.

    1998-01-01

    The concentrations and discrimination of selected heavy metals in biota from the southern Baltic indicate that a large group of the Baltic organisms bioaccumulates Fe and Pb but discriminates against U. There appears to be no significant transfer of heavy metals along successive levels of the food chain. The distribution of the heavy metals in the associated sediments is a result of the anthropogenic input of Zn, Pb, Cd, Ag, P and Cu. It is suggested that Pb is introduced to the Polish sector of the Baltic Sea mainly by atmospheric transport whereas other heavy-metal pollutants are introduced mainly from the Vistula River. (Copyright (c) 1998 Elsevier Science B.V., Amsterdam. All rights reserved.)

  14. Heavy metal ion removal by thiol functionalized aluminum oxide hydroxide nanowhiskers

    Science.gov (United States)

    Xia, Zhiyong; Baird, Lance; Zimmerman, Natasha; Yeager, Matthew

    2017-09-01

    In this study, we developed a cost effective method of using thiol functionalized γ-aluminum oxide hydroxide (γ-AlOOH) filters for removing three key heavy metals from water: mercury, lead, and cadmium under non-concomitant conditions. Compared to non-thiol treated γ-AlOOH filters, the introduction of thiol functional groups greatly improved the heavy metal removal efficiency under both static and dynamic filtration conditions. The adsorption kinetics of thiol functionalized γ-AlOOH were investigated using the Lagergren first order and pseudo-second order kinetics models; whereas the isothermal adsorption behavior of these membranes was revealed through the Langmuir and Freundlich models. Heavy metal concentration was quantified by Inductively Coupled Plasma-Mass Spectroscopy, and the thiol level on γ-AlOOH surface was measured by a colorimetric assay using Ellman's reagent. X-ray photoelectron spectroscopy was used to further address the surface sulfur state on the membranes after heavy metal exposure. Mechanisms for heavy metal adsorption were also discussed.

  15. [Distributions and pollution status of heavy metals in the suspended particles of the estuaries and coastal area of eastern Hainan].

    Science.gov (United States)

    Xin, Cheng-Lin; Ren, Jing-Ling; Zhang, Gui-Ling; Shao, Ya-Ping; Zhang, Guo-Ling; Liu, Su-Mei

    2013-04-01

    The distributions and pollution status of heavy metals in the suspended particles were investigated in the Wanquan and Wenchang/Wenjiao estuaries and the coastal area of eastern Hainan in July 2008. The concentrations of metal elements (Al, Fe, Mn, Cr, Cu, Ni, V, Zn) were determined by ICP-AES after microwave digestion. Multivariate statistical methods (e. g. correlation analysis and principal factor analysis) were used to discuss the major factors controlling the variability of heavy metal concentrations and the pollution status in those areas. There was an obvious variability in particulate metal concentrations from upstream to estuary of both rivers. The concentrations first increased with increasing salinity and then decreased with further increase of the salinity; the concentrations were slightly higher at the coastal area in the east. The variability of particulate metal concentrations reduced significantly after the normalization by Al, indicating the effects of grain size. Enrichment factor calculation results showed that there was heavy metal pollution (especially Cu, Ni) in the Wenchang/Wenjiao River and estuary, while the situation in Wanquan River remained at pristine level. Concentrations of particulate metals in the study area were mainly controlled by source geology and provenance, as well as contamination from the discharge of waste water and biological activity.

  16. THE EATING HABITS OF MILKY WAY-MASS HALOS: DESTROYED DWARF SATELLITES AND THE METALLICITY DISTRIBUTION OF ACCRETED STARS

    International Nuclear Information System (INIS)

    Deason, Alis J.; Mao, Yao-Yuan; Wechsler, Risa H.

    2016-01-01

    We study the mass spectrum of destroyed dwarfs that contribute to the accreted stellar mass of Milky Way (MW)-mass (M vir  ∼ 10 12.1 M ⊙ ) halos using a suite of 45 zoom-in dissipationless simulations. Empirical models are employed to relate (peak) subhalo mass to dwarf stellar mass, and we use constraints from z = 0 observations and hydrodynamical simulations to estimate the metallicity distribution of the accreted stellar material. The dominant contributors to the accreted stellar mass are relatively massive dwarfs with M star  ∼ 10 8 –10 10 M ⊙ . Halos with more quiescent accretion histories tend to have lower mass progenitors (10 8 –10 9 M ⊙ ), and lower overall accreted stellar masses. Ultra-faint mass (M star  < 10 5 M ⊙ ) dwarfs contribute a negligible amount (≪1%) to the accreted stellar mass and, despite having low average metallicities, supply a small fraction (∼2%–5%) of the very metal-poor stars with [Fe/H] < −2. Dwarfs with masses 10 5  < M star /M ⊙  < 10 8 provide a substantial amount of the very metal-poor stellar material (∼40%–80%), and even relatively metal-rich dwarfs with M star  > 10 8 M ⊙ can contribute a considerable fraction (∼20%–60%) of metal-poor stars if their metallicity distributions have significant metal-poor tails. Finally, we find that the generic assumption of a quiescent assembly history for the MW halo seems to be in tension with the mass spectrum of its surviving dwarfs. We suggest that the MW could be a “transient fossil”; a quiescent halo with a recent accretion event(s) that disguises the preceding formation history of the halo

  17. Management with willow short rotation coppice increase the functional gene diversity and functional activity of a heavy metal polluted soil.

    Science.gov (United States)

    Xue, K; van Nostrand, J D; Vangronsveld, J; Witters, N; Janssen, J O; Kumpiene, J; Siebielec, G; Galazka, R; Giagnoni, L; Arenella, M; Zhou, J-Z; Renella, G

    2015-11-01

    We studied the microbial functional diversity, biochemical activity, heavy metals (HM) availability and soil toxicity of Cd, Pb and Zn contaminated soils, kept under grassland or short rotation coppice (SRC) to attenuate the risks associated with HM contamination and restore the soil ecological functions. Soil microbial functional diversity was analyzed by the GeoChip, a functional gene microarray containing probes for genes involved in nutrient cycling, metal resistance and stress response. Soil under SRC showed a higher abundance of microbial genes involved in C, N, P and S cycles and resistance to various HM, higher microbial biomass, respiration and enzyme activity rates, and lower HM availability than the grassland soil. The linkages between functional genes of soil microbial communities and soil chemical properties, HM availability and biochemical activity were also investigated. Soil toxicity and N, P and Pb availability were important factors in shaping the microbial functional diversity, as determined by CCA. We concluded that in HM contaminated soils the microbial functional diversity was positively influenced by SRC management through the reduction of HM availability and soil toxicity increase of nutrient cycling. The presented results can be important in predicting the long term environmental sustainability of plant-based soil remediation. Copyright © 2015 Elsevier Ltd. All rights reserved.

  18. Bio-functionalized silver nanoparticles for selective colorimetric sensing of toxic metal ions and antimicrobial studies

    Science.gov (United States)

    Vinod Kumar, V.; Anbarasan, S.; Christena, Lawrence Rene; SaiSubramanian, Nagarajan; Philip Anthony, Savarimuthu

    2014-08-01

    Hibiscus Sabdariffa (Gongura) plant extracts (leaves (HL) and stem (HS) were used for the first time in the green synthesis of bio-functionalized silver nanoparticles (AgNPs). The bio-functionality of AgNPs has been successfully utilized for selective colorimetric sensing of potentially health and environmentally hazardous Hg2+, Cd2+ and Pb2+ metal ions at ppm level in aqueous solution. Importantly, clearly distinguishable colour for all three metal ions was observed. The influence of extract preparation condition and pH were also explored on the formation of AgNPs. Both selectivity and sensitivity differed for AgNPs synthesized from different parts of the plant. Direct correlation between the stability of green synthesized AgNPs at different pH and its antibacterial effects has been established. The selective colorimetric sensing of toxic metal ions and antimicrobial effect of green synthesized AgNPs demonstrated the multifunctional applications of green nanotechnology.

  19. Polymer functionalized nanocomposites for metals removal from water and wastewater: An overview.

    Science.gov (United States)

    Lofrano, Giusy; Carotenuto, Maurizio; Libralato, Giovanni; Domingos, Rute F; Markus, Arjen; Dini, Luciana; Gautam, Ravindra Kumar; Baldantoni, Daniela; Rossi, Marco; Sharma, Sanjay K; Chattopadhyaya, Mahesh Chandra; Giugni, Maurizio; Meric, Sureyya

    2016-04-01

    Pollution by metal and metalloid ions is one of the most widespread environmental concerns. They are non-biodegradable, and, generally, present high water solubility facilitating their environmental mobilisation interacting with abiotic and biotic components such as adsorption onto natural colloids or even accumulation by living organisms, thus, threatening human health and ecosystems. Therefore, there is a high demand for effective removal treatments of heavy metals, making the application of adsorption materials such as polymer-functionalized nanocomposites (PFNCs), increasingly attractive. PFNCs retain the inherent remarkable surface properties of nanoparticles, while the polymeric support materials provide high stability and processability. These nanoparticle-matrix materials are of great interest for metals and metalloids removal thanks to the functional groups of the polymeric matrixes that provide specific bindings to target pollutants. This review discusses PFNCs synthesis, characterization and performance in adsorption processes as well as the potential environmental risks and perspectives. Copyright © 2016 Elsevier Ltd. All rights reserved.

  20. Local structure studies using the pair distribution function

    Directory of Open Access Journals (Sweden)

    Bordet Pierre

    2015-01-01

    Full Text Available The pair distribution analysis method is a fast spreading structural analysis method allowing to go beyond classical crystallographic analysis by providing quantitative information about local as well as meso-structure. It based on powder diffraction data fourier transformed to direct space. We will present here the main characteristics of the method, and its domain of application.

  1. Global marine plankton functional type biomass distributions : Phaeocystis spp

    NARCIS (Netherlands)

    Vogt, M.; O'Brien, C.; Peloquin, J.; Schoemann, V.; Breton, E.; Estrada, M.; Gibson, J.; Karentz, D.; van Leeuwe, M. A.; Stefels, J.; Widdicombe, C.; Peperzak, L.

    2012-01-01

    The planktonic haptophyte Phaeocystis has been suggested to play a fundamental role in the global biogeochemical cycling of carbon and sulphur, but little is known about its global biomass distribution. We have collected global microscopy data of the genus Phaeocystis and converted abundance data to

  2. Functional distribution of coronary vascular volume in beating goat hearts

    NARCIS (Netherlands)

    van der Ploeg, C. P.; Dankelman, J.; Spaan, J. A.

    1993-01-01

    With use of hemoglobin-bound O2 as an endogenous tracer, intramyocardial blood volume distribution between vessels involved in O2 exchange and more distal vessels was estimated. In nine anesthetized open-chest goats, the left main coronary artery was cannulated and perfused at a constant flow.

  3. Unpolarized structure functions and the parton distributions for ...

    Indian Academy of Sciences (India)

    the valence distributions so extracted at the bound state scale can provide adequate model based inputs for appropriate .... nucleon ground state; only the ground state positive energy eigenmodes Φґ·µ. Хo (Ц) would .... Thus keeping in mind that uЪ(m, Q¾)=0= dЪ(m, Q¾) as per our initial assumption and considering the ...

  4. Distribution of emphysema in heavy smokers: impact on pulmonary function.

    NARCIS (Netherlands)

    Gietema, H.A.; Zanen, P.; Schilham, A.; Ginneken, B. van; Klaveren, R.J.J. van; Prokop, M.; Lammers, J.W.

    2010-01-01

    PURPOSE: To investigate impact of distribution of computed tomography (CT) emphysema on severity of airflow limitation and gas exchange impairment in current and former heavy smokers participating in a lung cancer screening trial. MATERIALS AND METHODS: In total 875 current and former heavy smokers

  5. Correlation between the distribution of lignin and pectin and distribution of sorbed metal ions (lead and zinc) on coir (Cocos nucifera L.).

    Science.gov (United States)

    Conrad, Kathrine

    2008-11-01

    Plant fibres are capacious for sorption of metal ions, and can be used in water cleaning. Knowledge about the sorption will help in selection of the fibre and optimisation of its chemical modification, if any. The aim of this paper is to investigate the connection, if any, between the distribution of lignin and pectin and the loading of Pb and Zn on coir (mesocarp fibres from Cocos nucifera L.). The coir consisted mainly of xylem and a fibre sheath. The lignin was evenly distributed in the cell walls of the fibre sheath, but in the xylem, there was no detectable content in the compound middle lamella, and a smaller content of lignin in the secondary walls than in the walls of the fibre sheath. The only detectable content of pectin in the fibre sheath walls was in the middle lamella, cell corners and extracellular matrix, while in the xylem, the pectin was almost evenly distributed in the wall, with a higher concentration in the middle lamella and cell corners. All cell walls facing the lacuna had a high content of pectin. The metal ions were mainly loaded on the xylem and cell walls facing the lacuna, maybe with an additional trend to be loaded on the large fibres. Lead was distributed on and across the whole secondary wall. Zinc was loaded on the secondary walls, but there was no information about the distribution across the wall. If there is a simple correlation between the loading of metal ions and the distribution of lignin or pectin, these investigations point at no correlation with lignin and a positive correlation with pectin. It has to be stressed that these conclusions are made on limited material and are therefore preliminary in nature.

  6. Calculation of equilibrium stable isotope partition function ratios for aqueous zinc complexes and metallic zinc

    Science.gov (United States)

    Black, Jay R.; Kavner, Abby; Schauble, Edwin A.

    2011-02-01

    The goal of this study is to determine reduced partition function ratios for a variety of species of zinc, both as a metal and in aqueous solutions in order to calculate equilibrium stable isotope partitioning. We present calculations of the magnitude of Zn stable-isotope fractionation ( 66,67,68Zn/ 64Zn) between aqueous species and metallic zinc using measured vibrational spectra (fit from neutron scattering studies of metallic zinc) and a variety of electronic structure models. The results show that the reduced metal, Zn(0), will be light in equilibrium with oxidized Zn(II) aqueous species, with the best estimates for the Zn(II)-Zn(0) fractionation between hexaquo species and metallic zinc being Δ 66/64Zn aq-metal ˜ 1.6‰ at 25 °C, and Δ 66/64Zn aq-metal ˜ 0.8‰ between the tetrachloro zinc complex and metallic zinc at 25 °C using B3LYP/aug-cc-pVDZ level of theory and basis set. To examine the behavior of zinc in various aqueous solution chemistries, models for Zn(II) complex speciation were used to determine which species are thermodynamically favorable and abundant under a variety of different conditions relevant to natural waters, experimental and industrial solutions. The optimal molecular geometries for [Zn(H 2O) 6] 2+, [Zn(H 2O) 6]·SO 4, [ZnCl 4] 2- and [Zn(H 2O) 3(C 3H 5O(COO) 3)] - complexes in various states of solvation, protonation and coordination were calculated at various levels of electronic structure theory and basis set size. Isotopic reduced partition function ratios were calculated from frequency analyses of these optimized structures. Increasing the basis set size typically led to a decrease in the calculated reduced partition function ratios of ˜0.5‰ with values approaching a plateau using the aug-cc-pVDZ basis set or larger. The widest range of species were studied at the B3LYP/LAN2DZ/6-31G ∗ level of theory and basis-set size for comparison. Aqueous zinc complexes where oxygen is bound to the metal center tended to have the

  7. Effect of preemptive weld overlay sequence on residual stress distribution for dissimilar metal weld of Kori nuclear power plant pressurizer

    Energy Technology Data Exchange (ETDEWEB)

    Bae, Hong Yeol; Song, Tae Kwang; Chun, Yun Bae; Oh, Chang Young; Kim, Yun Jae [Korea Univ., Seoul (Korea, Republic of); Lee, Kyoung Soo; Park, Chi Yong [Korea Electric Power Research Institute, Daejeon (Korea, Republic of)

    2008-07-01

    Weld overlay is one of the residual stress mitigation method which arrest crack. An overlay weld sued in this manner is termed a Preemptive Weld OverLay(PWOL). PWOL was good for distribution of residual stress of Dissimilar Metal Weld(DMW) by previous research. Because range of overlay welding is wide relatively, residual stress distribution on PWR is affected by welding sequence. In order to examine the effect of welding sequence, PWOL was applied to a specific DMW of KORI nuclear power plant by finite element analysis method. As a result, the welding direction that from nozzle to pipe is better good for residual stress distribution on PWR.

  8. Task scheduler and service subsystem for the common node of a distributed function laboratory computer network

    International Nuclear Information System (INIS)

    Stubblefield, F.W.; Dimmler, D.G.

    1976-01-01

    In a functionally distributed computer system, the system function is partitioned into less complex functions which reside at decreasing functional hierarchy levels. At some point in the partitioning process, all software and hardware required to implement an identified function are confined to a node of the system. The type of hardware elements and the form of the software required at the node are determined by the node function. This principle is illustrated in the case of a task scheduler for the common node of a distributed function laboratory computer system having a star-like configuration

  9. Improved Accuracy of Density Functional Theory Calculations for CO2 Reduction and Metal-Air Batteries

    DEFF Research Database (Denmark)

    Christensen, Rune; Hansen, Heine Anton; Vegge, Tejs

    2015-01-01

    , Nano Lett., 14, 1016 (2014) [6] J. Wellendorff, K. T. Lundgaard, A. Møgelhøj, V. Petzold, D. D. Landis, J. K. Nørskov, T. Bligaard, and K. W. Jacobsen, Phys. Rev. B, 85, 235149 (2012) Figure 1: Calculated enthalpies of reaction from CO2 to CH3OH (x axis) and HCOOH (y axis). Functional variations.......e. the electrocatalytic reduction of CO2 and metal-air batteries. In theoretical studies of electrocatalytic CO2 reduction, calculated DFT-level enthalpies of reaction for CO2reduction to various products are significantly different from experimental values[1-3]. In theoretical studies of metal-air battery reactions...... through first principle methods. Ensembles generated using a Bayesian error estimation functional, in this case the BEEF-vdW functional[6], are used for the error identification. The ensembles, which consist of perturbations of the main van der Waals density functional, can be generated at low...

  10. Metal leaching in drinking water domestic distribution system: an Italian case study.

    Science.gov (United States)

    Sorlini, Sabrina; Gialdini, Francesca; Collivignarelli, Carlo

    2014-01-01

    The objective of this study was to evaluate metal contamination of tap water in seven public buildings in Brescia (Italy). Two monitoring periods were performed using three different sampling methods (overnight stagnation, 30-min stagnation, and random daytime). The results show that the water parameters exceeding the international standards (Directive 98/83/EC) at the tap were lead (max = 363 μg/L), nickel (max = 184 μg/L), zinc (max = 4900 μg/L), and iron (max = 393 μg/L). Compared to the total number of tap water samples analyzed (122), the values higher than limits of Directive 98/83/EC were 17% for lead, 11% for nickel, 14% for zinc, and 7% for iron. Three buildings exceeded iron standard while five buildings exceeded the standard for nickel, lead, and zinc. Moreover, there is no evident correlation between the leaching of contaminants in the domestic distribution system and the age of the pipes while a significant influence is shown by the sampling methods.

  11. Density functional theory studies of screw dislocation core structures in bcc metals

    DEFF Research Database (Denmark)

    Frederiksen, Søren Lund; Jacobsen, Karsten Wedel

    2003-01-01

    The core structures of (I 11) screw dislocations in bee metals are studied using density functional theory in the local-density approximation. For Mo and Fe, direct calculations of the core structures show the cores to be symmetric with respect to 180degrees rotations around an axis perpendicular...

  12. Removal of chlorine gas by an amine functionalized metal-organic framework via electrophilic aromatic substitution.

    Science.gov (United States)

    DeCoste, Jared B; Browe, Matthew A; Wagner, George W; Rossin, Joseph A; Peterson, Gregory W

    2015-08-11

    Here we report the removal of chlorine gas from air via a reaction with an amine functionalized metal-organic framework (MOF). It is found that UiO-66-NH2 has the ability to remove 1.24 g of Cl2 per g of MOF via an electrophilic aromatic substitution reaction producing HCl, which is subsequently neutralized by the MOF.

  13. Channel length scaling and the impact of metal gate work function ...

    Indian Academy of Sciences (India)

    Further- more, quantum effects on the performance of DG-MOSFETs are addressed and discussed. We also study the influence of metal gate work function on the performance of nanoscale MOSFETs. We use a self-consistent Poisson–Schrödinger solver in two dimensions over the entire device. A good agreement with ...

  14. Doping of graphite by an alkaline-earth metal to reduce the work function

    NARCIS (Netherlands)

    Baturin, AS; Nikolski, KN; Knyazev, AI; Tchesov, RG; Sheshin, EP

    2004-01-01

    A technique for reducing the work function of a field-emission graphite cathode by doping it by an alkaline-earth metal (barium) is suggested. A model of formation of a barium monolayer on the cathode surface is proposed. Field-emission tests show that the operating voltage of the doped cathode is

  15. Work functions of self-assembled monolayers on metal surfaces by first-principles calculations

    NARCIS (Netherlands)

    Rusu, P.C.; Brocks, G.

    2006-01-01

    Using first-principles calculations we show that the work function of noble metals can be decreased or increased by up to 2 eV upon the adsorption of self-assembled monolayers of organic molecules. We identify the contributions to these changes for several (fluorinated) thiolate molecules adsorbed

  16. Spatial distribution of heavy metals in sediments from the Gulf of Paria,Trinidad

    Directory of Open Access Journals (Sweden)

    Wendy Norville

    2005-05-01

    Full Text Available The Gulf of Paria receives heavy metal input from urban runoff,industrial and agricultural activity, sewage and domestic wastes:both from the west coast and from inland areas of Trinidad.Non-residual concentrations of nine metals,as well as total mercury concentrations,were used to determine spatial distributions of heavy metals in sediments in the Gulf of Paria.Surficial sediment samples were collected at 37 stations,which included the mouths of 11 major rivers that flow into the Gulf of Paria.Stations were sampled twice during the wet season (July 1998 and November/December 1998and twice during the dry season (March 1999 and April 1999.Sediments were analyzed for aluminium (Al,cadmium (Cd,chromium (Cr,copper (Cu,iron (Fe, lead (Pb,manganese (Mn,nickel (Ni,zinc (Znand mercury (Hg.Total Organic Carbon (TOCand grain size analyses were also performed on the sediments.Principal component analysis showed that sediments from river mouths subject to greatest land use and anthropogenic input,were distinct from other sediments in the Gulf of Paria.This was due to higher Pb,Zn,Cu and Hg concentrations (3.53-73.30 µg g-1 ,45.8-313.9 µg g-1 ,8.43-39.71 µg g-1 and 0.03-0.10 µg g-1 ,respectively.Sediments further from the coast were also distinct due to their higher Al,Fe,Cr and Mn concentrations (1.37-3.16 mg g-1 ,9.51-18.91 mg g-1 ,17.22-28.41 µg g-1 and 323.6 -1,564.2 µg g-1 ,respectively.Cd and Pb were higher in the wet season while Ni was higher in the dry season.Pb,Zn,Cu and Hg were correlated with each other and with TOC.Correlation was also observed between Al,Fe,Cr,Mn and Ni.Al,Fe,Cr and Mn were correlated with percentage clay in sediments.The results suggest that Pb,Zn, Cu and Hg are preferentially removed by organic matter,which settles at the river-mouths,while Al,Fe,Cr,Mn, and Ni become associated with clay minerals and are transported away from the coast.El Golfo de Paria recibe metales pesados de zonas urbanas,industriales y agr

  17. Scattering influences in quantitative fission neutron radiography for the in situ analysis of hydrogen distribution in metal hydrides

    Energy Technology Data Exchange (ETDEWEB)

    Börries, S., E-mail: stefan.boerries@hzg.de [Helmholtz-Zentrum Geesthacht, Centre for Materials and Coastal Research, Max-Planck-Strasse 1, D-21502 Geesthacht (Germany); Metz, O.; Pranzas, P.K. [Helmholtz-Zentrum Geesthacht, Centre for Materials and Coastal Research, Max-Planck-Strasse 1, D-21502 Geesthacht (Germany); Bücherl, T. [ZTWB Radiochemie München (RCM), Technische Universität München (TUM), Walther-Meissner-Str. 3, D-85748 Garching (Germany); Söllradl, S. [Forschungs-Neutronenquelle Heinz Maier-Leibnitz (FRMII), Technische Universität München (TUM), Lichtenbergstr. 1, D-85748 Garching (Germany); Dornheim, M.; Klassen, T.; Schreyer, A. [Helmholtz-Zentrum Geesthacht, Centre for Materials and Coastal Research, Max-Planck-Strasse 1, D-21502 Geesthacht (Germany)

    2015-10-11

    In situ neutron radiography allows for the time-resolved study of hydrogen distribution in metal hydrides. However, for a precise quantitative investigation of a time-dependent hydrogen content within a host material, an exact knowledge of the corresponding attenuation coefficient is necessary. Additionally, the effect of scattering has to be considered as it is known to violate Beer's law, which is used to determine the amount of hydrogen from a measured intensity distribution. Within this study, we used a metal hydride inside two different hydrogen storage tanks as host systems, consisting of steel and aluminum. The neutron beam attenuation by hydrogen was investigated in these two different setups during the hydrogen absorption process. A linear correlation to the amount of absorbed hydrogen was found, allowing for a readily quantitative investigation. Further, an analysis of scattering contributions on the measured intensity distributions was performed and is described in detail.

  18. Scattering influences in quantitative fission neutron radiography for the in situ analysis of hydrogen distribution in metal hydrides

    Science.gov (United States)

    Börries, S.; Metz, O.; Pranzas, P. K.; Bücherl, T.; Söllradl, S.; Dornheim, M.; Klassen, T.; Schreyer, A.

    2015-10-01

    In situ neutron radiography allows for the time-resolved study of hydrogen distribution in metal hydrides. However, for a precise quantitative investigation of a time-dependent hydrogen content within a host material, an exact knowledge of the corresponding attenuation coefficient is necessary. Additionally, the effect of scattering has to be considered as it is known to violate Beer's law, which is used to determine the amount of hydrogen from a measured intensity distribution. Within this study, we used a metal hydride inside two different hydrogen storage tanks as host systems, consisting of steel and aluminum. The neutron beam attenuation by hydrogen was investigated in these two different setups during the hydrogen absorption process. A linear correlation to the amount of absorbed hydrogen was found, allowing for a readily quantitative investigation. Further, an analysis of scattering contributions on the measured intensity distributions was performed and is described in detail.

  19. Towards Bayesian Inference of the Fast-Ion Distribution Function

    DEFF Research Database (Denmark)

    Stagner, L.; Heidbrink, W.W.; Salewski, Mirko

    2012-01-01

    sensitivity of the measurements are incorporated into Bayesian likelihood probabilities, while prior probabilities enforce physical constraints. As an initial step, this poster uses Bayesian statistics to infer the DIII-D electron density profile from multiple diagnostic measurements. Likelihood functions....... However, when theory and experiment disagree (for one or more diagnostics), it is unclear how to proceed. Bayesian statistics provides a framework to infer the DF, quantify errors, and reconcile discrepant diagnostic measurements. Diagnostic errors and ``weight functions" that describe the phase space...

  20. Metal Insulator Transition of Cr doped V2O3 calculated by hybrid density functional

    OpenAIRE

    Guo, Yuzheng; Clark, Stewart J.; Robertson, John

    2013-01-01

    The electronic structure of vanadium sesquioxide in its different phases has been calculated using the screened exchange (sX) hybrid functional. The hybrid functional reproduces the electronic properties of all three phases, the paramagnetic metal (PM) phase, the anti-ferromagnetic insulating phase, and the Cr-doped paramagnetic insulating (PI) phase. A fully relaxed supercell model of Cr-doped V2O3 has a polaronic distortion around the substitutional Cr atoms and this local strain drives the...

  1. Electrical control of the light absorption in quantum-well functionalized junctions between thin metallic films

    Science.gov (United States)

    Marinica, Dana Codruta; Kazansky, Andrey K.; Borisov, Andrei G.

    2017-12-01

    We use a time-dependent density functional theory approach to study the optical response of a hybrid nanostructure where the junction between thin metallic films is functionalized with a quantum well (QW) structure. We show that an unoccupied QW-localized electronic state opens the possibility of the active electrical control of the photoassisted electron transport through the junction and of the absorption at optical frequencies. Control strategies based on an applied bias or an external THz field are demonstrated.

  2. Computational Investigations of Potential Energy Function Development for Metal--Organic Framework Simulations, Metal Carbenes, and Chemical Warfare Agents

    Science.gov (United States)

    Cioce, Christian R.

    Metal-Organic Frameworks (MOFs) are three-dimensional porous nanomaterials with a variety of applications, including catalysis, gas storage and separation, and sustainable energy. Their potential as air filtration systems is of interest for designer carbon capture materials. The chemical constituents (i.e. organic ligands) can be functionalized to create rationally designed CO2 sequestration platforms, for example. Hardware and software alike at the bleeding edge of supercomputing are utilized for designing first principles-based molecular models for the simulation of gas sorption in these frameworks. The classical potentials developed herein are named PHAST --- Potentials with High Accuracy, Speed, and Transferability, and thus are designed via a "bottom-up" approach. Specifically, models for N2 and CH4 are constructed and presented. Extensive verification and validation leads to insights and range of applicability. Through this experience, the PHAST models are improved upon further to be more applicable in heterogeneous environments. Given this, the models are applied to reproducing high level ab initio energies for gas sorption trajectories of helium atoms in a variety of rare-gas clusters, the geometries of which being representative of sorption-like environments commonly encountered in a porous nanomaterial. This work seeks to push forward the state of classical and first principles materials modeling. Additionally, the characterization of a new type of tunable radical metal---carbene is presented. Here, a cobalt(II)---porphyrin complex, [Co(Por)], was investigated to understand its role as an effective catalyst in stereoselective cyclopropanation of a diazoacetate reagent. Density functional theory along with natural bond order analysis and charge decomposition analysis gave insight into the electronics of the catalytic intermediate. The bonding pattern unveiled a new class of radical metal---carbene complex, with a doublet cobalt into which a triplet carbene

  3. Effects of a kappa distribution function of electrons on incoherent scatter spectra

    Directory of Open Access Journals (Sweden)

    S. Saito

    2000-09-01

    Full Text Available In usual incoherent scatter data analysis, the plasma distribution function is assumed to be Maxwellian. In space plasmas, however, distribution functions with a high energy tail which can be well modeled by a generalized Lorentzian distribution function with spectral index kappa (kappa distribution have been observed. We have theoretically calculated incoherent scatter spectra for a plasma that consists of electrons with kappa distribution function and ions with Maxwellian neglecting the effects of the magnetic field and collisions. The ion line spectra have a double-humped shape similar to those from a Maxwellian plasma. The electron temperatures are underestimated, however, by up to 40% when interpreted assuming Maxwellian distribution. Ion temperatures and electron densities are affected little. Accordingly, actual electron temperatures might be underestimated when an energy input maintaining a high energy tail exists. We have also calculated plasma lines with the kappa distribution function. They are enhanced in total strength, and the peak frequencies appear to be slightly shifted to the transmitter frequency compared to the peak frequencies for a Maxwellian distribution. The damping rate depends on the electron temperature. For lower electron temperatures, plasma lines for electrons with a κ distribution function are more strongly damped than for a Maxwellian distribution. For higher electron temperatures, however, they have a relatively sharp peak.Key words: Ionosphere (auroral ionosphere; plasma waves and instabilities – Space plasma physics (kinetic and MHD theory

  4. Surface distribution of dissolved trace metals in the oligotrophic ocean and their influence on phytoplankton biomass and productivity

    KAUST Repository

    Pinedo-González, Paulina

    2015-10-25

    The distribution of bioactive trace metals has the potential to enhance or limit primary productivity and carbon export in some regions of the world ocean. To study these connections, the concentrations of Cd, Co, Cu, Fe, Mo, Ni, and V were determined for 110 surface water samples collected during the Malaspina 2010 Circumnavigation Expedition (MCE). Total dissolved Cd, Co, Cu, Fe, Mo, Ni, and V concentrations averaged 19.0 ± 5.4 pM, 21.4 ± 12 pM, 0.91 ± 0.4 nM, 0.66 ± 0.3 nM, 88.8 ± 12 nM, 1.72 ± 0.4 nM, and 23.4 ± 4.4 nM, respectively, with the lowest values detected in the Central Pacific and increased values at the extremes of all transects near coastal zones. Trace metal concentrations measured in surface waters of the Atlantic Ocean during the MCE were compared to previously published data for the same region. The comparison revealed little temporal changes in the distribution of Cd, Co, Cu, Fe, and Ni over the last 30 years. We utilized a multivariable linear regression model to describe potential relationships between primary productivity and the hydrological, biological, trace nutrient and macronutrient data collected during the MCE. Our statistical analysis shows that primary productivity in the Indian Ocean is best described by chlorophyll a, NO3, Ni, temperature, SiO4, and Cd. In the Atlantic Ocean, primary productivity is correlated with chlorophyll a, NO3, PO4, mixed layer depth, Co, Fe, Cd, Cu, V, and Mo. The variables salinity, temperature, SiO4, NO3, PO4, Fe, Cd, and V were found to best predict primary productivity in the Pacific Ocean. These results suggest that some of the lesser studied trace elements (e.g., Ni, V, Mo, and Cd) may play a more important role in regulating oceanic primary productivity than previously thought and point to the need for future experiments to verify their potential biological functions.

  5. Frequency distribution function of stellar flares in the Orion association

    International Nuclear Information System (INIS)

    Parsamian, E.S.

    1981-01-01

    The temporal distributions of flare stars in the Orion association and the numbers of stars with different flare frequencies are determined by means of Ambartsumian's (1978) method, which uses the chronology of discovery of 'first' flares and the chronology of confirmations, i.e., the temporal distributions of 'repeated' flares. It is shown that flare stars with high flare frequency (not greater than 1000 hours) in the Pleiades are basically stars of low luminosity with M(U) not less than 13m. Two independent methods of determining the number of flare stars in the aggregates confirm that there are about 1.5 times more flare stars in the Orion association than in the Pleiades

  6. Quantum arrival-time distributions from intensity functions

    DEFF Research Database (Denmark)

    Wlodarz, Joachim

    2002-01-01

    The quantum time-of-arrival problem is discussed within the standard formulation of nonrelativistic quantum mechanics with parametric time. It is shown that a general class of arrival-time probability distributions results from the assumption that the arrival process of a quantum particle...... is similar in nature to other time-dependent arrival-type processes occurring, e.g., in population biology or queue theory. A simple but illustrative example related to the well-known Wigner discussion of the time-energy uncertainty relation is given and the numerical results obtained are compared...... with Kijowski's distribution [Rep. Math. Phys. 6, 362 (1974)] of arrival times for a free quantum particle....

  7. QCD phenomenology of parton distribution functions at small x

    International Nuclear Information System (INIS)

    Tung, Wu-Ki

    1990-09-01

    The small x behavior of parton distributions is studied phenomenologically by examining in detail a series of QCD-evolved distribution sets obtained in a new global analysis of deep inelastic scattering and lepton-pair production experiments. The importance of 2-loop evolution is discussed. The main features and results of the global analysis are described. The range of small x behavior consistent with next-to-leading order QCD and current data is delineated. The extrapolated small x behavior is parameterized by effective Q-dependent power- and logarithmic-law parameters. Intriguing features of the evolution of these parameters with Q are presented. Alternative parametrizations based on the analytic solution for small x is also explored. 20 refs., 6 figs., 1 tab

  8. Charaterisation of function spaces via mollification; fractal quantities for distributions

    Directory of Open Access Journals (Sweden)

    Hans Triebel

    2003-01-01

    Full Text Available The aim of this paper is twofold. First we characterise elements f belonging to the Besov spaces Bpqs(ℝn with s∈ℝ,  0distributions generalising well-known corresponding quantities for Radon measures.

  9. On k-Gamma and k-Beta Distributions and Moment Generating Functions

    Directory of Open Access Journals (Sweden)

    Gauhar Rahman

    2014-01-01

    Full Text Available The main objective of the present paper is to define k-gamma and k-beta distributions and moments generating function for the said distributions in terms of a new parameter k>0. Also, the authors prove some properties of these newly defined distributions.

  10. Spatial distribution and contamination assessment of heavy metals in urban topsoils from Las Tunas city (Cuba) using XRF

    International Nuclear Information System (INIS)

    Diaz Rizo, O.; Fonticiella Morell, D.; Arado Lopez, J. O.; Boreel Munnoz, J. L.; D'Alessandro Rodriguez, K.; Lopez Pino, N.

    2013-01-01

    Concentrations of Cr, Co, Ni, Cu, Zn, Pb and Fe in the topsoils (0-10 cm) from Las Tunas city were measured by X-ray fluorescence analysis. The mean Cr, Co, Ni, Zn and Pb contents in the urban topsoil samples (97± 30, 14 ± 2, 35 ± 36, 94 ± 26, 199 ± 87 and 42 ± 29 mg.kg -1 respectively) were compared with mean concentrations for other cities around the world with similar population. Cr content in school grounds, parks and residential areas exceed background level in 20%. Highest content for Ni was determined in residential areas, for Zn in market gardens soils and as for Pb, the highest content ratios were observed for market gardens (2.7) and residential areas (2.3). Spatial distribution maps indicated the same behaviour for Cr-Co-Ni and Pb-Zn, respectively, whereas the spatial distribution of Cu differs from other heavy metals. On the other hand, the metal-to-iron normalisation, using (10-20) cm bottom soil contents as background, showed that topsoils in Las Tunas city are severe enriched with lead and not enriched with the rest of determined metals. The average values of integrated pollution index (IPI) indicated that soils are moderate contaminated by heavy metals (1.17 ≤ IPI ave ≤ 1.39), but enrichment index values (EI) shows that metal concentrations on the studied locations are not above the permissible levels for urban agriculture. (Author)

  11. Study of the distribution of ions and metals in blood using nuclear methodology

    International Nuclear Information System (INIS)

    Oliveira, Laura Cristina de

    2008-01-01

    The present study consists of using nuclear tools aiming to establish an alternative procedure to perform biochemistry analyses in whole blood to help the diagnosis of diverse pathologies. The aim is to determine the ions and metals concentrations in whole blood of human beings (specifically: Br, Cl, K e Na), using neutron activation analysis, providing the limits of normality, as well as, the matrix of the correlation for these elements. To perform this study, 283 samples of whole blood had been analyzed (of healthy volunteers selected from blood banks), resulting in the limits of normality for Br (0.0067 - 0.0263 gl -1 ), Cl (2.54 - 3.50 gl -1 ), K (1.33 - 1.89 gl -1 ) and Na (1.48 - 2.06 gl -1 ). These data are the first estimates for reference values in whole blood of the Brazilian population. These limits were evaluated in function of the sex and age for checking the biological differences. The behavior of these limits was also evaluated for different populations, i.e., in two distinct regions: Southeast (blood collection carried out in Sao Paulo city) and Northeast (blood collection carried out in Recife city). These places were chosen in function of the similarities (cities with high concentration people and industrialized). Furthermore, a systematic study of these limits was also evaluated, in the period of 4 (four) years, in Sao Paulo city. This analysis was elaborated in function of time due the necessity to update these data, therefore they act as environment monitors. The estimation for Ca and Fe were also proposal for a set of 22 samples of whole blood.(author)

  12. Digital technique for inverse function obtaining and electron emission power distribution calculation

    International Nuclear Information System (INIS)

    Sorokin, O.M.

    1984-01-01

    The way to obtain energy distribution of electron emission using the method of the inverse function, in which two amplitude pulse analyzers are Used, has been improved. One of them, the flowsheet of which is somewhat changed, is used to obtain the inverse function in the regime of tracing search of channel address of the set ordinate of voltammetric characteristics distribution, and second one - to obtain amplitude distribution of standard pulses, discriminated according to the law of inverse voltammetric characteristics. The distribution function as to the energy which is obtained as a result can have a statistical error of 1-2% at emission currents up to 10-100 electron/s

  13. The mechanism of exchange of cyclopentane with deuterium on metal catalysts: determination of initial product distributions by a Monte Carlo method

    International Nuclear Information System (INIS)

    Faro, A.C. Jr.; Kemball, C.

    1984-01-01

    Monte Carlo methods have been used to calculate the initial distributions of products from the exchange of cyclopentane with deuterium based on different mechanisms for the reaction. Comparisons of the distributions, so obtained, were made with the experimental results on a series of metal catalysts in order to determine which mechanisms appeared to be operating on each metal. (author)

  14. Distribution and contamination of heavy metals in surface sediments of the Daya Bay and adjacent shelf, China.

    Science.gov (United States)

    Zhao, Guangming; Ye, Siyuan; Yuan, Hongming; Ding, Xigui; Wang, Jin

    2016-11-15

    Heavy metal (arsenic (As), cadmium (Cd), chromium (Cr), copper (Cu), mercury (Hg), lead (Pb), and zinc (Zn)) concentrations from the Daya Bay and adjacent shelf were determined to evaluate their levels and spatial distributions. The measured concentrations ranged from 1.94-13.67mg/kg for As, 0.03-0.13mg/kg for Cd, 10-85mg/kg for Cr, 1-39.5mg/kg for Cu, 0.01-0.09mg/kg for Hg, 11-56mg/kg for Pb, and 13-125mg/kg for Zn. The spatial distributions exhibited a gradual decrease from west to east, and the concentrations of the seven heavy metals met the China Marine Sediment Quality criteria. Both metal enrichment factor (EF) and geo-accumulation index (Igeo) values showed that Cd, Cr, Cu, Hg, and Zn were not at pollution levels in the region. Multivariate analysis (PCA) revealed that lithogenic factors dominated the distribution of most of the metals, whereas As and Hg were clearly influenced by anthropogenic input. Copyright © 2016 Elsevier Ltd. All rights reserved.

  15. METALS DISTRIBUTION AND PARTICLE SIZE ANALYSIS IN WATER AND SEDIMENT OF THE DJETINJA RIVER AND DRAGIĆA SPRING (SERBIA

    Directory of Open Access Journals (Sweden)

    JELENA KIURSKI

    2010-12-01

    Full Text Available This paper reports the results on total metal concentration (Al, Fe, Cr, Cu, Ni and Zn in water and sediment of the Djetinja river basin in the area of western Serbia. Samples were collected in spring season. Based on the comparison of the concentrations of all analyzed metals it is possible to differentiate two zo¬nes: zone I (sampling sites 1-4, affected by the discharge of the Dragića spring, and zone II (sites 5-8, affected by the confluence of the Dragića spring with the Djetinja river. The analysis of suspended solid particle size in water as well as in sediment samples was performed in size range 0.02-2000 m and a posi¬tive corelation was found with the concentration of aluminium, zinc, iron and nickel in water samples. The study of particle size and metals distribution through the river basin of the Djetinja was a useful tool for getting information about the distribution degree of the polluting agents, and their possible evolution growth and pollution sources. The research of metals distribution and particle size analysis in water and sediment of the Djetinja river and Dragića spring (Serbia was conducted for the first time.

  16. Spatial distribution and historical trends of heavy metals in the sediments of petroleum producing regions of the Beibu Gulf, China

    International Nuclear Information System (INIS)

    Yang, Jichao; Wang, Weiguo; Zhao, Mengwei; Chen, Bin; Dada, Olusegun A.; Chu, Zhihui

    2015-01-01

    Highlights: • The spatial distribution and historical trend of heavy metals were discussed. • The contents of heavy metals reached their highest level near the platforms. • The trend of heavy metals corresponded with the history of petroleum industry. • The environment around the platforms had a very high ecological risk. • The petroleum production was the cause of the severe enrichment of heavy metals. - Abstract: The concentrations of As, Sb, Hg, Pb, Cd, and Ba in the surface and core sediments of the oil and gas producing region of the Beibu Gulf were measured by Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES), Inductively Coupled Plasma Mass Spectrometry (ICP-MS) and Atomic Fluorescence Spectrometry (AFS), and the spatial distribution and historical trends of these elements are discussed. The results show that the concentrations of these elements are highest near the platforms. The results of Enrichment Factor (EF) and Potential Ecological Risk Index (PERI) also reveal significantly higher enrichment around the platforms, which imply that the offshore petroleum production was the cause of the unusual distribution and severe enrichment of these elements in the study area. The environment around the platforms was highly laden with toxic elements, thereby representing a very high ecological risk to the environment of the study area

  17. Differences in forest plant functional trait distributions across land-use and productivity gradients

    Science.gov (United States)

    Margaret M. Mayfield; John M. Dwyer; Loic Chalmandrier; Jessie A. Wells; Stephen P. Bonser; Carla P. Catterall; Fabrice DeClerck; Yi Ding; Jennifer M. Fraterrigo; Daniel J. Metcalfe; Cibele Queiroz; Peter A. Vesk; John W. Morgan

    2013-01-01

    • Premise of study: Plant functional traits are commonly used as proxies for plant responses to environmental challenges, yet few studies have explored how functional trait distributions differ across gradients of land-use change. By comparing trait distributions in intact forests with those across land-use change gradients, we can improve our understanding of the ways...

  18. CT-quantified emphysema distribution is associated with lung function decline

    NARCIS (Netherlands)

    Hoesein, F.A.A.M.; Rikxoort, E.M. van; Ginneken, B. van; de Jong, P. A.; Prokop, M.; Lammers, J.W.; Zanen, P.

    2012-01-01

    Emphysema distribution is associated with COPD. It is however unknown whether CT-quantified emphysema distribution (upper/lower lobe) is associated with lung function decline in heavy (former) smokers.587 male participants underwent lung CT-scanning and pulmonary function testing at baseline and

  19. Nonparametric estimation of the stationary M/G/1 workload distribution function

    DEFF Research Database (Denmark)

    Hansen, Martin Bøgsted

    2005-01-01

    In this paper it is demonstrated how a nonparametric estimator of the stationary workload distribution function of the M/G/1-queue can be obtained by systematic sampling the workload process. Weak convergence results and bootstrap methods for empirical distribution functions for stationary associ...

  20. Prospective analysis of human leukocyte functional tests reveals metal sensitivity in patients with hip implant

    Science.gov (United States)

    2013-01-01

    Background The aim of the study was to examine the reactivity of peripheral human leukocytes to various metal ions prior and following hip replacement in order to investigate implant-induced metal sensitivity. Methods Three patient groups were set up: (1) individuals without implants and no history of metal allergy (7 cases), (2) individuals without implants and known history of metal allergy (7 cases), and (3) patients undergoing cementless hip replacement (40 cases). Blood samples were taken in groups 1 and 2 at three different occasions; in group 3, prior and 3, 6, 12, 24, and 36 months after surgery. Peripheral leukocytes were separated and left either untreated or challenged with Ti, NiCl2, CoCl2, CrCl3, and phytohemagglutinin. Cell proliferation, cytokine release, and leukocyte migration inhibition assays were performed. Metal-induced reactivity was considered when all three assays showed significant change. Skin patch tests were also carried out. Results Both skin patch tests and leukocyte functional tests were negative in group 1, and both were positive in group 2. In group 3, after 6 months, 12% of the patients showed reactivity to the tested metals except for NiCl2. Following the 36-month period, 18% of group three became sensitive to metals (including all the earlier 12%). In contrast, patch tests were negative at each time point in group 3. Conclusions Orthopedic implant material may induce metal reactivity after implantation in a manner where susceptibility is yet to be elucidated. Leukocyte triple assay technique might be a useful tool to test implant material-related sensitivity. PMID:23680415

  1. Accumulation and distribution of heavy metals in surface sediments of a semienclosed basin in the southeastern Mediterranean Sea, Egypt

    Directory of Open Access Journals (Sweden)

    M.A.M. ABDALLAH

    2007-06-01

    Full Text Available The distribution, enrichment and accumulation of heavy metals in the surficial sediments of the Alexandria City Eastern Harbour (Mediterranean coast of Egypt were investigated. Surface sediments (in the <63mm fraction collected from 12 sites representing the entire area of the harbour, were analyzed by AAS for Cd, Cu, Zn, Cr, Pb and Al. Metal contents were compared with literature data to assess the pollution status of sediments. Enrichment factors (EFs and the geoaccumulation Index (Igeo were calculated as a criterion of possible contamination.

  2. Tripartite entangled Wigner operator, the Wigner function and its marginal distributions

    CERN Document Server

    Fan Hong Yi

    2003-01-01

    For a tripartite entangled system, based on the newly constructed tripartite Einstein-Podolsky-Rosen entangled state, we find the entangled state representation of the Wigner operator. The corresponding Wigner function then leads us to obtain the physical marginal distributions. We emphasize that, for an entangled-particle system, the physical meaning of the Wigner distribution function should lie in that its marginal distributions give the probability of finding the particles in an entangled way.

  3. Measurement-induced decoherence and Gaussian smoothing of the Wigner distribution function

    International Nuclear Information System (INIS)

    Chun, Yong-Jin; Lee, Hai-Woong

    2003-01-01

    We study the problem of measurement-induced decoherence using the phase-space approach employing the Gaussian-smoothed Wigner distribution function. Our investigation is based on the notion that measurement-induced decoherence is represented by the transition from the Wigner distribution to the Gaussian-smoothed Wigner distribution with the widths of the smoothing function identified as measurement errors. We also compare the smoothed Wigner distribution with the corresponding distribution resulting from the classical analysis. The distributions we computed are the phase-space distributions for simple one-dimensional dynamical systems such as a particle in a square-well potential and a particle moving under the influence of a step potential, and the time-frequency distributions for high-harmonic radiation emitted from an atom irradiated by short, intense laser pulses

  4. Distribution and accumulation of heavy metals in carbonate and reducible fractions of marine sediment from offshore mid-western Taiwan.

    Science.gov (United States)

    Liu, Hou-Chun; You, Chen-Feng; Huang, Bor-Jiun; Huh, Chih-An

    2013-08-15

    Two marine sediment cores from offshore mid-western Taiwan were subsampled and pre-treated using a sequential extraction procedure to separate carbonate and reducible fractions. Aliquots of these extracts were analyzed to determine their chemical composition to evaluate the geochemical processes responsible for heavy metal distribution and accumulation in the coastal environment. Our data demonstrate that sedimentation rates derived from excess (210)Pb associated with metal fluxes show large increases circa A.D. 1990. A well-synchronized increase in metal flux in both geochemical fractions was found and validated by Pearson's correlation. Principal component analysis revealed the heavy metal fluxes to be highly correlated with the sediment deposition rate, with metal contamination potentially driven by a sole contributor. This study emphasizes the changes in sedimentation rate is potentially caused by activities associated with the inland economic development during this time, rather than by raising heavy metal pollution dominated the accumulation offshore mid-western Taiwan. Copyright © 2013 Elsevier Ltd. All rights reserved.

  5. Non-parametric kernel density estimation of species sensitivity distributions in developing water quality criteria of metals.

    Science.gov (United States)

    Wang, Ying; Wu, Fengchang; Giesy, John P; Feng, Chenglian; Liu, Yuedan; Qin, Ning; Zhao, Yujie

    2015-09-01

    Due to use of different parametric models for establishing species sensitivity distributions (SSDs), comparison of water quality criteria (WQC) for metals of the same group or period in the periodic table is uncertain and results can be biased. To address this inadequacy, a new probabilistic model, based on non-parametric kernel density estimation was developed and optimal bandwidths and testing methods are proposed. Zinc (Zn), cadmium (Cd), and mercury (Hg) of group IIB of the periodic table are widespread in aquatic environments, mostly at small concentrations, but can exert detrimental effects on aquatic life and human health. With these metals as target compounds, the non-parametric kernel density estimation method and several conventional parametric density estimation methods were used to derive acute WQC of metals for protection of aquatic species in China that were compared and contrasted with WQC for other jurisdictions. HC5 values for protection of different types of species were derived for three metals by use of non-parametric kernel density estimation. The newly developed probabilistic model was superior to conventional parametric density estimations for constructing SSDs and for deriving WQC for these metals. HC5 values for the three metals were inversely proportional to atomic number, which means that the heavier atoms were more potent toxicants. The proposed method provides a novel alternative approach for developing SSDs that could have wide application prospects in deriving WQC and use in assessment of risks to ecosystems.

  6. The spatial distribution pattern of heavy metal concentrations in urban soils — a study of anthropogenic effects in Berehove, Ukraine

    Science.gov (United States)

    Vince, Tímea; Szabó, György; Csoma, Zoltán; Sándor, Gábor; Szabó, Szilárd

    2014-09-01

    In the present study we examined the Ba, Cd, Cr, Cu, Fe, Mn, Ni, Pb and Zn contamination levels of the soils of Berehove, a small city in West-Ukraine. As a first step we determined the spatial distribution of the heavy metal contents of the urban soils; then, by studying the land use structure of the city and by statistical analysis we identified the major sources of contamination; we established a matrix of correlations between the heavy metal contents of the soils and the different types of land use; and finally, we drew a conclusion regarding the possible origin(s) of these heavy metals. By means of multivariate statistical analysis we established that of the investigated metals, Ba, Cd, Cu, Pb and Zn accumulated in the city's soils primarily as a result of anthropogenic activity. In the most polluted urban areas (i.e. in the industrial zones and along the roads and highways with heavy traffic), in the case of several metals (Ba, Cd, Cu, Pb, Zn) we measured concentration levels even two or three times higher than the threshold limit values. Furthermore, Cr, Fe and Ni are primarily of lithogenic origin; therefore, the soil concentrations of these heavy metals depend mainly on the chemical composition of the soil-forming rocks.

  7. Spatio-temporal distribution of metals in household dust from rural, semi-urban and urban environments in the Niger Delta, Nigeria.

    Science.gov (United States)

    Iwegbue, Chukwujindu M A; Oliseyenum, Ejiro C; Martincigh, Bice S

    2017-06-01

    Concentrations of metals in household dust samples from rural, semi-urban and urban zones of the Niger Delta in Nigeria were measured during both 2009 and 2014 with the aim of providing information on changes in the concentrations, distribution patterns, sources and risks of metals in these zones. The concentrations of metals in the dust samples were quantified by using inductively coupled plasma atomic emission spectrophotometry (ICP-AES) after digestion with aqua regia. The measured concentrations (mg kg -1 ) of metals in the three zones within the study periods were as follows: furniture, metal-based fittings, metal roofing and pesticides.

  8. Performance of exchange-correlation functionals in density functional theory calculations for liquid metal: A benchmark test for sodium

    Science.gov (United States)

    Han, Jeong-Hwan; Oda, Takuji

    2018-04-01

    The performance of exchange-correlation functionals in density-functional theory (DFT) calculations for liquid metal has not been sufficiently examined. In the present study, benchmark tests of Perdew-Burke-Ernzerhof (PBE), Armiento-Mattsson 2005 (AM05), PBE re-parameterized for solids, and local density approximation (LDA) functionals are conducted for liquid sodium. The pair correlation function, equilibrium atomic volume, bulk modulus, and relative enthalpy are evaluated at 600 K and 1000 K. Compared with the available experimental data, the errors range from -11.2% to 0.0% for the atomic volume, from -5.2% to 22.0% for the bulk modulus, and from -3.5% to 2.5% for the relative enthalpy depending on the DFT functional. The generalized gradient approximation functionals are superior to the LDA functional, and the PBE and AM05 functionals exhibit the best performance. In addition, we assess whether the error tendency in liquid simulations is comparable to that in solid simulations, which would suggest that the atomic volume and relative enthalpy performances are comparable between solid and liquid states but that the bulk modulus performance is not. These benchmark test results indicate that the results of liquid simulations are significantly dependent on the exchange-correlation functional and that the DFT functional performance in solid simulations can be used to roughly estimate the performance in liquid simulations.

  9. Density functional theory studies of screw dislocation core structures in bcc metals

    DEFF Research Database (Denmark)

    Frederiksen, Søren Lund; Jacobsen, Karsten Wedel

    2003-01-01

    The core structures of (I 11) screw dislocations in bee metals are studied using density functional theory in the local-density approximation. For Mo and Fe, direct calculations of the core structures show the cores to be symmetric with respect to 180degrees rotations around an axis perpendicular...... to the dislocation line. The magnetic moment in the Fe core is shown to be reduced relative to the bulk value. Calculations of gamma surfaces and the elastic constants B, C' and c(44) are reported for Fe and all group VB and VIB metals. Using a criterion suggested by Vitek and Duesbery the calculations point...

  10. Adhesion of oxide layer to metal-doped aluminum hydride surface: Density functional calculations

    Science.gov (United States)

    Takezawa, Tomoki; Itoi, Junichi; Kannan, Takashi

    2017-07-01

    The density functional theory (DFT) calculations were carried out to evaluate the adhesion energy of the oxide layer to the metal-doped surface of hydrogen storage material, aluminum hydride (alane, AlH3). The total energy calculations using slab model revealed that the surface doping of some metals to aluminum hydride weakens the adhesion strength of the oxide layer. The influence of titanium, iron, cobalt, and zirconium doping on adhesion strength were evaluated. Except for iron doping, the adhesion strength becomes weak by the doping.

  11. The Functionalization, Size Control and Properties of Metal-Organic Frameworks

    DEFF Research Database (Denmark)

    Xu, Hui; Iversen, Bo Brummerstedt

    Recent years, Metal-Organic Framework (MOF) materials have drawn great attentions due to their potential applications in gas sorption/separation and luminescent sensing. In this dissertation, the recent progress of MOF materials is reviewed, with specific focus on the functionalization, size...... control and properties of MOF materials. A cationic MOF material was synthesized, and small hydrocarbons C1/C2 sorption/separation properties were studied. A MOF with both open metal sites and Lewis basic pyridyl sites was developed, and C2H2, CO2 and CH4 gas sorption/separation properties were explored...

  12. Understanding charge transfer of Li+ and Na+ ions scattered from metal surfaces with high work function

    International Nuclear Information System (INIS)

    Chen Lin; Wu Wen-Bin; Liu Pin-Yang; Xiao Yun-Qing; Li Guo-Peng; Liu Yi-Ran; Jiang Hao-Yu; Guo Yan-Ling; Chen Xi-Meng

    2016-01-01

    For Li + and Na + ions scattered from high work function metal surfaces, efficient neutralization is observed, and it cannot be explained by the conventional free electron model. In order to explain these experimental data, we investigate the velocity-dependent neutral fraction with the modified Brako–Newns (BN) model. The calculated results are in agreement with the experimental data. We find that the parallel velocity effect plays an important role in neutralizing the Li + and Na + ions for large angle scattering. The nonmonotonic velocity behavior of neutral fraction is strongly related to the distance-dependent coupling strength between the atomic level and metal states. (paper)

  13. Benchmark Calculations of Energetic Properties of Groups 4 and 6 Transition Metal Oxide Nanoclusters Including Comparison to Density Functional Theory

    Energy Technology Data Exchange (ETDEWEB)

    Fang, Zongtang; Both, Johan; Li, Shenggang; Yue, Shuwen; Aprà, Edoardo; Keçeli, Murat; Wagner, Albert F.; Dixon, David A.

    2016-08-09

    The heats of formation and the normalized clustering energies (NCEs) for the group 4 and group 6 transition metal oxide (TMO) trimers and tetramers have been calculated by the Feller-Peterson-Dixon (FPD) method. The heats of formation predicted by the FPD method do not differ much from those previously derived from the NCEs at the CCSD(T)/aT level except for the CrO3 nanoclusters. New and improved heats of formation for Cr3O9 and Cr4O12 were obtained using PW91 orbitals instead of Hartree-Fock (HF) orbitals. Diffuse functions are necessary to predict accurate heats of formation. The fluoride affinities (FAs) are calculated with the CCSD(T) method. The relative energies (REs) of different isomers, NCEs, electron affinities (EAs), and FAs of (MO2)n ( M = Ti, Zr, Hf, n = 1 – 4 ) and (MO3)n ( M = Cr, Mo, W, n = 1 – 3) clusters have been benchmarked with 55 exchange-correlation DFT functionals including both pure and hybrid types. The absolute errors of the DFT results are mostly less than ±10 kcal/mol for the NCEs and the EAs, and less than ±15 kcal/mol for the FAs. Hybrid functionals usually perform better than the pure functionals for the REs and NCEs. The performance of the two types of functionals in predicting EAs and FAs is comparable. The B1B95 and PBE1PBE functionals provide reliable energetic properties for most isomers. Long range corrected pure functionals usually give poor FAs. The standard deviation of the absolute error is always close to the mean errors and the probability distributions of the DFT errors are often not Gaussian (normal). The breadth of the distribution of errors and the maximum probability are dependent on the energy property and the isomer.

  14. Hermite-distributed approximating functional-based formulation of ...

    Indian Academy of Sciences (India)

    2016-07-29

    Jul 29, 2016 ... A case study of quantum tunnelling in a coupled double-well system. KAUSHIK MAJI. ∗. Department of Chemistry ... The HDAF space discretiza- tion of the kinetic energy operator on a regular grid consists of. − .... are implicit functions of time and that imparts great flexibility to the single-particle basis. In.

  15. The distribution function of a probability measure on a space with a fractal structure

    Energy Technology Data Exchange (ETDEWEB)

    Sanchez-Granero, M.A.; Galvez-Rodriguez, J.F.

    2017-07-01

    In this work we show how to define a probability measure with the help of a fractal structure. One of the keys of this approach is to use the completion of the fractal structure. Then we use the theory of a cumulative distribution function on a Polish ultrametric space and describe it in this context. Finally, with the help of fractal structures, we prove that a function satisfying the properties of a cumulative distribution function on a Polish ultrametric space is a cumulative distribution function with respect to some probability measure on the space. (Author)

  16. Surfactant nebulisation : lung function, surfactant distribution and pulmonary blood flow distribution in lung lavaged rabbits

    NARCIS (Netherlands)

    Dijk, Peter H.; Heikamp, A; Bambang Oetomo, Sidarto

    1997-01-01

    Objective: Surfactant nebulisation is a promising alternative to surfactant instillation in newborns with the respiratory distress syndrome. Although less surfactant is deposited in the lung, it improves gas exchange, probably due to a superior distribution. We hypothesize that a more uniform

  17. Multi-level methods and approximating distribution functions

    International Nuclear Information System (INIS)

    Wilson, D.; Baker, R. E.

    2016-01-01

    Biochemical reaction networks are often modelled using discrete-state, continuous-time Markov chains. System statistics of these Markov chains usually cannot be calculated analytically and therefore estimates must be generated via simulation techniques. There is a well documented class of simulation techniques known as exact stochastic simulation algorithms, an example of which is Gillespie’s direct method. These algorithms often come with high computational costs, therefore approximate stochastic simulation algorithms such as the tau-leap method are used. However, in order to minimise the bias in the estimates generated using them, a relatively small value of tau is needed, rendering the computational costs comparable to Gillespie’s direct method. The multi-level Monte Carlo method (Anderson and Higham, Multiscale Model. Simul. 10:146–179, 2012) provides a reduction in computational costs whilst minimising or even eliminating the bias in the estimates of system statistics. This is achieved by first crudely approximating required statistics with many sample paths of low accuracy. Then correction terms are added until a required level of accuracy is reached. Recent literature has primarily focussed on implementing the multi-level method efficiently to estimate a single system statistic. However, it is clearly also of interest to be able to approximate entire probability distributions of species counts. We present two novel methods that combine known techniques for distribution reconstruction with the multi-level method. We demonstrate the potential of our methods using a number of examples.

  18. Spatial distribution of heavy metals in soil, water, and vegetables of farms in Sanandaj, Kurdistan, Iran

    OpenAIRE

    Maleki, Afshin; Amini, Hassan; Nazmara, Shahrokh; Zandi, Shiva; Mahvi, Amir Hossein

    2014-01-01

    Background Heavy metals are ubiquitous elsewhere in nature and their measurement in environment is necessary to develop health management strategies. In this study, we aimed to find out concentrations and spatial patterns of heavy metals in main farms of Sanandaj in Kurdistan, Iran. Methods Over May to October 2012, six farms were selected to analyze concentrations and spatial patterns of several heavy metals, namely aluminum (Al), arsenic (As), cadmium (Cd), cobalt (Co), chromium (Cr), coppe...

  19. THE DISTRIBUTION OF COMMERCIAL CROWN ETHER DC18C6 AND THE EXTRACTION STUDY OF ALKALI AND EARTH ALKALI METALS

    Directory of Open Access Journals (Sweden)

    Bambang Rusdiarso

    2010-06-01

    Full Text Available Distribution of A and B isomers of crown-ether DC18C6 on their organic and water phases (chloride, nitrate and sulphocyanide salts and extraction of alkali and earth alkali metals has been studied. In LiCl 0.1 M environment, lithium extraction could be ignored. The presence of extracted potassium metal may affect the crown ether DC18C6 distribution albeit only a little. In KNO3 0.1 M environment, the distribution coefficient values (d were 6.1 and 10.3 for A and B isomers, respectively ; while in KCl  0.1 M environment the values were 4.9 and 11.8, respectively. In KSCN 0.1 M, d values for A and B isomers were 40.4 and 36.6, respectively, which were higher than the value obtained from both KNO3 and KCl  0.1 M environments. Caesium metal extraction using DC18C6 occurred weakly, up to only 5%. Strontium extraction using DC18C6 achieved better yield than the caesium extraction. The percentage of extraction increased under organic solvent according to the following: toluene (4% < chloroform (28% < TBP (35%.   Keywords: distribution, crown-ether DC18C6, extraction.

  20. Separation of heavy metals from water by functionalized glycidyl methacrylate poly (high internal phase emulsions).

    Science.gov (United States)

    Huš, Sebastjan; Kolar, Mitja; Krajnc, Peter

    2016-03-11

    Removal of silver, lead and cadmium ions from both model solutions and real contaminated water was achieved, in a flow through manner, by using highly porous functionalized poly(glycidyl methacrylate) materials, prepared by the polymerisation of high internal phase emulsions (polyHIPE), with significant sorption differences between metals allowing for selective removal. PolyHIPEs, initially prepared from glycidyl methacrylate as a functional monomer, were functionalized with pentaerythritol tetrakis(3-mercaptopropionate), 1,9-nonanedithiol and 2-aminobenzenethiol via the epoxy ring opening on the polymer supports and applied in a flow-through manner via encasements into dedicated disk holders. Capacity of 21.7mg Ag per gram of polymer was found for 1,9-nonanedithiol functionalized polymers, while the capacity was decreasing with the decreasing ionic radius of the metal; the dynamics of sorption also depended on metal ion size and furthermore on the thiol used for the polymer functionalization. Copyright © 2016 Elsevier B.V. All rights reserved.